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Nuclear Power

Nuclear power

Nuclear power is any method of doing work that makes use of nuclear fission or fusion reactions. In its broadest sense, the term refers both to the uncontrolled release of energy, as in fission or fusion weapons, and to the controlled release of energy, as in a nuclear power plant. Most commonly, however, the expression nuclear power is reserved for the latter of these two processes.

The world's first exposure to nuclear power came when two fission (atomic) bombs were exploded over Hiroshima and Nagasaki, Japan, in August 1945. These actions are said to have brought World War II to a conclusion. After the war, a number of scientists and laypersons looked for some potential peacetime use for this horribly powerful new form of energy. They hoped that the power of nuclear energy could be harnessed to perform work, but those hopes have been realized only to a modest degree. Some serious problems associated with the use of nuclear power have never been satisfactorily solved. As a result, after three decades of progress in the development of controlled nuclear power, interest in this energy source has leveled off and, in many nations, declined.

Words to Know

Cladding: A material that covers the fuel elements in a nuclear reactor in order to prevent the loss of heat and radioactive materials from the fuel.

Coolant: Any material used in a nuclear power plant to transfer the heat produced in the reactor core to another unit in which electricity is generated.

Containment: Any system developed for preventing the release of radioactive materials from a nuclear power plant to the outside world.

Generator: A device for converting kinetic energy (the energy of movement) into electrical energy.

Neutron: A subatomic particle that carries no electrical charge.

Nuclear fission: A reaction in which a larger atomic nucleus breaks apart into two roughly equal, smaller nuclei.

Nuclear fusion: A reaction in which two small nuclei combine with each other to form one larger nucleus.

Nuclear pile: The name given to the earliest form of a nuclear reactor.

Nuclear reactor: Any device for controlling the release of nuclear power so that it can be used for constructive purposes.

Radioactivity: The property possessed by some elements of spontaneously emitting energy in the form of particles or waves by disintegration of their atomic nuclei.

Subatomic particle: Basic unit of matter and energy (proton, neutron, electron, neutrino, and positron) smaller than an atom.

Turbine: A device consisting of a series of baffles (baffles are plates, mounts, or screens that regulate the flow of somethingin this case, a liquid) mounted on a wheel around a central shaft. Turbines are used to convert the energy of a moving fluid into the energy of mechanical rotation.

The nuclear power plant

A nuclear power plant is a system in which energy released by fission reactions is captured and used for the generation of electricity. Every such plant contains four fundamental elements: the reactor, the coolant system, the electrical power generating unit, and the safety system.

The source of energy in a nuclear reactor is a fission reaction in which neutrons collide with nuclei of uranium-235 or plutonium-239 (the fuel), causing them to split apart. The products of any fission reaction include not only huge amounts of energy, but also waste products, known as fission products, and additional neutrons. A constant and reliable flow of neutrons is ensured in the reactor by means of a moderator, which slows down the speed of neutrons, and control rods, which control the number

of neutrons available in the reactor and, hence, the rate at which fission can occur.

Energy produced in the reactor is carried away by means of a coolanta fluid such as water, or liquid sodium, or carbon dioxide gas. The fluid absorbs heat from the reactor and then begins to boil itself or to cause water in a secondary system to boil. Steam produced in either of these ways is then piped into the electrical generating unit, where it turns the blades of a turbine. The turbine, in turn, powers a generator that produces electrical energy.

Safety systems. The high cost of constructing a modern nuclear power plant reflects in part the enormous range of safety features needed to protect against various possible mishaps. Some of those features are incorporated into the reactor core itself. For example, all of the fuel in a reactor is sealed in a protective coating made of a zirconium alloy. The protective coating, called a cladding, helps retain heat and radioactivity within the fuel, preventing it from escaping into the power plant itself.

Every nuclear plant is also required to have an elaborate safety system to protect against the most serious potential problem of all: the loss of coolant. If such an accident were to occur, the reactor core might well melt down, releasing radioactive materials to the rest of the plant and, perhaps, to the outside environment. To prevent such an accident from happening, the pipes carrying the coolant are required to be very thick and strong. In addition, backup supplies of the coolant must be available to replace losses in case of a leak.

On another level, the whole plant itself is required to be encased within a dome-shaped containment structure. The containment structure is designed to prevent the release of radioactive materials in case of an accident within the reactor core.

Another safety feature is a system of high-efficiency filters through which all air leaving the building must pass. These filters are designed to trap microscopic particles of radioactive materials that might otherwise be released to the atmosphere. Additional specialized devices and systems have been developed for dealing with other kinds of accidents in various parts of the power plant.

Types of nuclear power plants. Nuclear power plants differ from each other primarily in the methods they use for transferring heat produced in the reactor to the electricity-generating unit. Perhaps the simplest design of all is the boiling water reactor (BWR) plant. In a BWR plant, coolant water surrounding the reactor is allowed to boil and form steam. That steam is then piped directly to turbines, which spin and drive the electrical generator. A very different type of plant is one that was popular in Great Britain for many yearsone that used carbon dioxide as a coolant. In this type of plant, carbon dioxide gas passes through the reactor core, absorbs heat produced by fission reactions, and is piped into a secondary system. There the heated carbon dioxide gas gives up its energy to water, which begins to boil and change to steam. That steam is then used to power the turbine and generator.

Safety concerns. In spite of all the systems developed by nuclear engineers, the general public has long had serious concerns about the use of such plants as sources of electrical power. Those concerns vary considerably from nation to nation. In France, for example, more than half of all that country's electrical power now comes from nuclear power plants. By contrast, the initial enthusiasm for nuclear power in the United States in the 1960s and 1970s soon faded, and no new nuclear power plant has been constructed in this country since the mid-1980s. Currently, 104 commercial nuclear power reactors in 31 states generate about 22 percent of the total electricity produced in the country.

One concern about nuclear power plants, of course, is the memory of the world's first exposure to nuclear power: the atomic bomb blasts. Many people fear that a nuclear power plant may go out of control and explode like a nuclear weapon. Most experts insist that such an event is impossible. But a few major disasters continue to remind the public about the worst dangers associated with nuclear power plants. By far the most serious of those disasters was the explosion that occurred at the Chernobyl Nuclear Power Plant near Kiev in Ukraine in 1986.

On April 16 of that year, one of the four power-generating units in the Chernobyl complex exploded, blowing the top off the containment building. Hundreds of thousands of nearby residents were exposed to deadly or damaging levels of radiation and were removed from the area. Radioactive clouds released by the explosion were detected as far away as western Europe. More than a decade later, the remains of the Chernobyl reactor were still far too radioactive for anyone to spend more than a few minutes in the area.

Critics also worry about the amount of radioactivity released by nuclear power plants on a day-to-day basis. This concern is probably of less importance than is the possibility of a major disaster. Studies have shown that nuclear power plants are so well shielded that the amount of radiation to which nearby residents are exposed under normal circumstances is no more than that of a person living many miles away.

In any case, safety concerns in the United States have been serious enough essentially to bring the construction of new plants to a halt. By the end of the twentieth century, licensing procedures were so complex and so expensive that few industries were interested in working their way through the bureaucratic maze to construct new plants.

Nuclear waste management. Perhaps the single most troubling issue for the nuclear power industry is waste management. After a period of time, the fuel rods in a reactor are no longer able to sustain a chain reaction and must be removed. These rods are still highly radioactive, however, and present a serious threat to human life and the environment. Techniques must be developed for the destruction and/or storage of these wastes.

Nuclear wastes can be classified into two general categories: low-level wastes and high-level wastes. The former consist of materials that release a relatively modest level of radiation and/or that will soon decay to a level where they no longer present a threat to humans and the environment. Storing these materials in underground or underwater reservoirs for a few years is usually satisfactory.

High-level wastes are a different matter. The materials that make up these wastes are intensely radioactive and are likely to remain so for thousands of years. Short-term methods of storage are unsatisfactory because containers would leak and break open long before the wastes were safe.

For more than two decades, the U.S. government has been attempting to develop a plan for the storage of high-level nuclear wastes. At one time, the plan was to bury the wastes in a salt mine near Lyons, Kansas. Objections from residents of the area and other concerned citizens caused that plan to be shelved. More recently, the government decided to construct a huge crypt in the middle of Yucca Mountain in Nevada for the burial of high-level wastes. Again, complaints by residents of Nevada and other citizens have delayed putting that plan into operation. The government insists, however, that Yucca Mountain will eventually become the long-term storage site for the nation's high-level radioactive wastes. Until then, those wastes are in "temporary" storage at nuclear power sites throughout the United States.

History

The first nuclear reactor was built during World War II (193945) as part of the Manhattan Project to build an atomic bomb. The reactor was constructed under the direction of Enrico Fermi in a large room beneath the squash courts at the University of Chicago. It was built as the first concrete test of existing theories of nuclear fission.

Until December 2, 1942, when the reactor was first put into operation, scientists had relied entirely on mathematical calculations to determine the effectiveness of nuclear fission as an energy source. It goes without saying that the scientists who constructed the first reactor were taking an extraordinary chance.

That first reactor consisted of alternating layers of uranium and uranium oxide with graphite as a moderator. Cadmium control rods were used to control the concentration of neutrons in the reactor. Since the various parts of the reactor were constructed by piling materials on top of each other, the unit was at first known as an atomic pile. The moment at which Fermi directed the control rods to be withdrawn occurred at 3:45 p.m. on December 2, 1945. That date can legitimately be regarded as the beginning of the age of controlled nuclear power in human history.

Nuclear fusion power

Many scientists believe that the ultimate solution to the world's energy problems may be in the harnessing of nuclear fusion power. A fusion reaction is one in which two small nuclei combine with each other to form one larger nucleus. For example, two hydrogen nuclei may combine with each other to form the nucleus of an atom known as deuterium, or heavy hydrogen.

The world was introduced to the concept of fusion reactions in the 1950s, when the Soviet Union and the United States exploded the first fusion (hydrogen) bombs. The energy released in the explosion of each such bomb was more than 1,000 times greater than the energy released in the explosion of a single fission bomb.

As with fission, scientists and nonscientists alike expressed hope that fusion reactions could someday be harnessed as a source of energy for everyday needs. This line of research has been much less successful, however, than research on fission power plants. In essence, the problem has been to find a way of containing the very high temperatures produced (a few million degrees Celsius) when fusion occurs. Optimistic reports of progress on a fusion power plant appear in the press from time to time, but some authorities now doubt that fusion power will ever be an economic reality.

[See also Nuclear fission; Nuclear fusion ]

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Nuclear Power

NUCLEAR POWER

NUCLEAR POWER refers to the energy produced by fission, when atoms are split, or by fusion, when two nuclei of a light atomare fused to forma single nucleus. The energy produced can be used for weapons or for peaceful purposes. The phrase is also used to designate those nations that have nuclear weapons. The first five nations to declare that they had nuclear weapons were the United States (1945), the former Soviet Union (1949), Great Britain (1952), France (1960), and China (1964), known as the "Big Five." The breakup of the Soviet Union in the early 1990s resulted in the addition of Belarus, Kazakhstan, and Ukraine as nuclear-weapon states because the nuclear missiles and storage sites placed on their territory by the Soviet Union became the property of these newly independent states; all three, however, transferred their weapons to Russia. India conducted its first nuclear test in 1974, followed by Pakistan in 1998. North Korea is believed to have the capacity to develop nuclear weapons within a short time. Others, such as Israel, have likely developed one or more such weapons secretly. Some analysts believe that another group of countries, including Iraq, were trying to develop nuclear weapons at the turn of the twenty-first century.

Nuclear power also refers to plants and industry that generate electric power from nuclear sources. The possibility of using the energy in the atomic nucleus as a power source was widely recognized soon after the discovery of nuclear fission late in 1938, but only the United States was able to devote any significant effort to atomic energy development during World War II. On 2 December 1942 Enrico Fermi and others achieved the first self-sustained chain reaction at Stagg Field at the University of Chicago. This experiment made possible the construction of three large plutonium-producing reactors; each generated about 250,000 kilowatts of energy, but they were not used for electric power production.

Despite the initial popular belief that the use of nuclear power was imminent, technical progress was slow after the war. The U.S. Atomic Energy Commission (AEC), facing extreme shortages of uranium ore, supported only three small reactor projects before 1950. One of these, the Experimental Breeder Reactor No. 1, succeeded in generating a few kilowatts of electric power late in 1951, an accomplishment more symbolic than practical.

Growing industrial interest in nuclear power by 1952, basic revision in atomic energy legislation in 1954, and increasing ore supplies made a more ambitious program possible in the 1950s. The AEC adopted a five-year plan designed to test the feasibility of five different reactor systems. One of these, the pressurized water reactor (PWR)—designed and and built by a joint AEC-Navy tea munder Rear Adm. H. G. Rickover, at Shippingport, Pennsylvania—produced 60,000 kilowatts of electricity for commercial use before the end of 1957. The AEC's Argonne National Laboratory, at Lemont, Illinois, under Walter H. Zinn, successfully developed the experimental boiling water reactor (EBWR). The PWR and EBWR committed the United States almost exclusively to water-cooled reactors for the next two decades. By the end of 1957, the AEC had seven experimental reactors in operation, and American industry had started nine independent or cooperative projects expected to produce 800,000 kilowatts of electricity by the mid-1960s.

Nuclear power plants differ from hydroelectric plants—which generate electricity from the force of flowing water—and from coal-, oil-, or gas-fired electric plants, which generate electricity from the heat drawn from burning fossil fuels. Nuclear power plants generate steam to drive electric turbines by circulating liquid through a nuclear reactor. The reactor produces heat through the controlled fission of atomic fuel. Normally the fuel for power reactors is slightly enriched uranium. These differences give nuclear reactors several advantages over power generation using other fuels. Unlike fossil fuels, nuclear fuel does not foul the air and is not dependent on oil imports from unstable parts of the world. Before the environmental effects of radioactive wastes and the safety hazards of nuclear plants became apparent in the 1960s and 1970s, some environmentalists were strong advocates of nuclear power as a "clean" energy source. Others, aware of the rising costs of the world's diminishing coal, oil, and natural gas resources and the limitation on the number of hydroelectric power plants that could be built, believed that nuclear plants could be the key to an independent American energy supply.

The attraction of electricity generated by nuclear power was not limited to the United States. In contrast to the American emphasis on water-cooled reactors, both the United Kingdom and France chose to rely on gas-cooled systems. By 1957 the United Kingdom was building or planning twelve reactors with a capacity of more than 1 million kilowatts; the French were building five reactors totaling more than 350,000 kilowatts. The Soviet Union was planning a 200,000-kilowatt PWR and two smaller boiling-water reactors. By 1966 nuclear power generators were being built or operating in five countries. By 1980 there were a hundred nuclear power plants in the United States.

Technical difficulties prevented any of these national plans from being realized by the early 1960s. In the United States the AEC countered the resulting pessimism


by predicting the imminence of economically competitive nuclear power and concentrating resources on the most promising reactor designs—water-cooled reactors for the immediate future and sodium-cooled breeder reactors for later decades in the century. This confidence was fulfilled by early 1964, when an American power company first announced its decision, on the basis of economics alone, to construct a nuclear power plant. Despite a temporary dampening effect of licensing delays and challenges from environmentalists protesting the dumping of radioactive wastes, the trend toward nuclear power accelerated again in the early 1970s. By the fall of 1972, the total nuclear gross generating capacity of all nations outside the Communist bloc had reached 32 million kilowatts. Of this total, the United States provided 13 million electrical kilowatts generated in twenty-eight operating plants. More than a hundred additional plants with a total capacity of more than 116 million kilowatts had been ordered or were under construction in the United States.

A serious accident at Three Mile Island in 1979 proved to be a major turning point for nuclear power in the United States, and no new nuclear generators have been ordered since. All of the increases in nuclear-generated electricity since 1979 have come from existing plants, which have boosted their national capacity factor from under 65 percent in 1970 to 76 percent in 1996.

One of the byproducts of nuclear-power generation is plutonium, a material that can be chemically processed for use in nuclear weapons. The danger of such use by nonnuclear nations led to international safeguards under the 1968 Nuclear Nonproliferation Treaty. In Article III signatory nations agreed to inspections by the International Atomic Energy Agency (IAEA), "with a view to

preventing diversion of nuclear energy from peaceful uses to nuclear weapons or other nuclear explosive devices." Most of the world's nuclear and nonnuclear nations signed this treaty. Iraq in 1992 and North Korea in 1994 were subjected to IAEA inspections that proved treaty violations in the former and raised serious suspicions about the latter. Both nations were signatories of the treaty, although North Korea announced its withdrawal some months prior to inspection. Iraq's nuclear-weapon production facilities were discovered as a result of a series of highly intrusive IAEA inspections and were subsequently destroyed by the United Nations.

When Congress passed the Atomic Energy Act of 1954, it approved President Dwight D. Eisenhower's Atoms for Peace program, which included commercial development of nuclear reactors for the purpose of generating electric power. During the 1960s electricity generated by nuclear power contributed 1 to 2 percent of the nation's energy total. Since then that percentage has grown steadily, surpassing the proportion from hydroelectric sources in 1984.By 1990 nuclear power amounted to one-fifth of the nation's total generation of electricity. By 1992 nuclear generation reached 619 billion net kilowatt hours, more than double the amount generated in 1979, the year of the Three Mile Island accident.

In reaction to the 1973 oil embargo, U.S. consumers temporarily used less energy, which diminished the rate of growth in electricity generation. As a result of this and other factors, such as higher construction costs, delays brought on by antinuclear protests, increased operating costs resulting from new federal regulations, and uncertainties about disposal of high-level radioactive waste, no requests for construction of new nuclear power plants have been received by the Nuclear Regulatory Commission since 1978.The level of generation was still rising, however, because plants started in the 1970s had gone on-line, and modernization after 1979 made power plants more efficient. The rising production trend continued until the end of the twentieth century; in the year 2000, for example, 104 commercial nuclear plants in the United States produced 20.5 percent of all electricity consumed in the United States. Nuclear power's future is far from clear, however. The Energy Information Administration projected in 2001 that 27 percent of the nation's nuclear generating capacity then in existence would be retired by 2020, with no construction of new plants anticipated.

BIBLIOGRAPHY

Department of Energy, Energy Information Administration. Annual Energy Outlook 2002 with Projections to 2020. Washington, D.C.: Department of Energy, 2001.

Deudney, Daniel, and Christopher Flavin. Renewable Energy: The Power to Choose. New York: W.W. Norton, 1983.

Duffy, Robert J. Nuclear Politics in America: A History and Theory of Government Regulation. Lawrence: University Press of Kansas, 1997.

Henderson, Harry. Nuclear Power: A Reference Handbook. Santa Barbara, Calif.: ABC-CLIO, 2000.

Robert M.Guth

Richard G.Hewlett/c. w.

See alsoNuclear Non-Proliferation Treaty (1978) ; Nuclear Test Ban Treaty .

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Nuclear Power

NUCLEAR POWER

A form of energy produced by an atomic reaction, capable of producing an alternative source of electrical power to that supplied by coal, gas, or oil.

The dropping of the atom bomb on Hiroshima, Japan, by the United States in 1945 initiated the atomic age. Nuclear energy immediately became a military weapon of terrifying magnitude. For the physicists who worked on the atom bomb, the promise of nuclear energy was not solely military. They envisioned nuclear power as a safe, clean, cheap, and abundant source of energy that would end society's dependence on fossil fuels. At the end of world war ii, leaders called for the peaceful use of nuclear energy.

Congress passed the Atomic Energy Act of 1946 (42 U.S.C.A. §§ 2011 et seq.), which shifted nuclear development from military to civilian government control. Very little development of commercial nuclear power occurred from 1946 to 1954 because the 1946 law maintained a federal government monopoly over the control, use, and ownership of nuclear reactors and fuels.

Congress amended the Atomic Energy Act in 1954 (68 Stat. 919) to encourage the private commercial development of nuclear power. The act ended the federal government's monopoly over nonmilitary uses of nuclear energy and allowed private ownership of reactors under licensing procedures established by the Atomic Energy Commission (AEC). Private power companies did not rush to build nuclear power plants because they feared the financial consequences of a nuclear accident. Congress responded by passing the Price-Anderson Act of 1957 (42 U.S.C.A. § 2210), which limited the liability of the nuclear power industry and assured compensation for the public. With the passage of the Price-Anderson Act, power companies began to build nuclear plants.

At first, nuclear power was attractive largely because the demand for electricity grew at a steady rate in the 1960s and coal-burning facilities were becoming an environmentally unacceptable alternative. The high price of oil during the mid-1970s continued to make nuclear power economically desirable and helped keep nuclear energy a prominent part of national energy plans. By the 1990s, approximately 110 nuclear plants were operating in the United States, supplying 20 percent of the nation's electricity.

A nuclear reactor produces energy through a chain reaction that splits a uranium nucleus, releasing energy in the form of heat. Fast breeder reactors, which use plutonium as fuel, generate more energy than they expend. Plutonium is not a natural element. It must be recycled from the excess uranium produced from a chain reaction. The radioactivity of plutonium is higher and its life is longer than that of any other element. Because of these characteristics, the public became concerned about the safety of its development and use.

Until 1969, the AEC did not have a formal process for evaluating the environmental impact of building nuclear power plants. In that year Congress passed the national environmental policy act of 1969 (42 U.S.C.A. §§ 4321– 4370), which required environmental impact statements for all major federal activities. In the 1970s, the temper of nuclear regulation changed. People were no longer complacent about nuclear power safety or convinced by environmental claims made by industry and government.

This lack of public trust centered on the role of the AEC as both a promoter of nuclear technology and a regulator of the nuclear power industry. In 1974, realizing the cross purposes of promotion and safety, Congress passed the Energy Reorganization Act (42 U.S.C.A. §§ 5801–5879), which created two agencies with different missions. The nuclear regulatory commission (NRC) is an independent agency

responsible for safety and licensing. The Energy Research and Development Administration (ERDA), later absorbed into the energy department, is responsible for promotion and development of nuclear power. This alignment did not completely remove fundamental regulatory conflict for the NRC, because the agency is responsible both for licensing plants and for safety oversight. If the NRC is too vigorous in exercising its safety role, the resulting compliance costs act as a disincentive to invest in nuclear plants.

A nuclear facility cannot be built without a construction permit issued by the NRC. An environmental impact statement that assesses the effect the facility will have on the environment must also be filed with the environmental protection agency (EPA). Once built, a nuclear plant must operate pursuant to a license from the NRC. A license requires that the facility use the lowest levels of radiation necessary to reasonably and efficiently maintain operations. The NRC also issues licenses for the use of nuclear materials, for transportation of nuclear materials, and for the export and import of nuclear materials, facilities, and components.

Nuclear power regulation is highly centralized in the federal government when nuclear safety and radiological hazards are at issue. States may address the financial capability of power companies to dispose of waste and may define state tort liability for injuries suffered at nuclear facilities.

Public confidence in the nuclear power industry suffered a major blow in 1979 when an accident occurred at the Three Mile Island Nuclear Station near Harrisburg, Pennsylvania. No one was hurt during the accident although radioactive gases escaped through the plant's ventilating system. The accident did reveal, however, the nuclear power industry's lack of emergency preparedness. Following the incident, the NRC increased safety inspections, stepped up enforcement, required the retrofitting of systems to enhance safety, and developed emergency preparedness rules. These regulations delayed the opening of new nuclear plants during the early 1980s.

In 1986, however, the safety of nuclear power again was challenged when a nuclear reactor exploded at Chernobyl in the Ukraine. Radiation 50 times higher than that at Three Mile Island exposed people nearest the reactor, and a cloud of radioactive fallout spread to Western Europe, causing the deaths of more than 30 people. People the world over questioned the logic of using such a volatile energy source.

Nuclear power also became less attractive to energy companies in the 1980s. The problem of disposing of nuclear waste became the focal point for the industry. Congress passed the Nuclear Waste Policy Act of 1982 (42 U.S.C.A. §§ 10101-10226), which directed the Department of Energy to formally begin planning the disposal of nuclear wastes and imposed most of the costs of disposal on the industry. The escalating costs of waste disposal helped bring construction of new nuclear facilities to a stop.

The problem of what to do with nuclear waste has proved difficult to solve. Nuclear material is contained in fuel rods. When spent fuel rods and other waste products fill the storage capacity at utility plants, the plants must either expand their storage capacity or find permanent off-site storage. Developing permanent nuclear waste sites is imperative because nuclear waste continues to accumulate. In addition, more than one hundred of the nuclear power facilities must be permanently shut down between 2010 and 2025 because their equipment and infrastructure will no longer be safe. This will entail removing most radioactive elements within each plant's nuclear reactor and then razing the entire plant.

The federal government has encountered political controversy and public opposition in its attempt to identify potential permanent nuclear waste sites. Since 1986 it has been unsuccessful in finding an acceptable site. Yucca Mountain, Nevada, has been earmarked as a nuclear waste repository, against the objections of citizens of Nevada and other advocacy groups. In January 2002, Secretary of Energy Spencer Abraham sent a letter to Nevada Governor Kenny C. Guinn notifying Guinn that Abraham had recommended to President george w. bush the development of the Yucca Mountain site. Guinn responded that the decision was premature and that further testing was necessary. When Bush approved the development of the site, Guinn vetoed, thus sending the issue to Congress.

The House and Senate both passed resolutions in 2002 with significant majorities approving the development of the Yucca Mountain site. The Energy Department must apply for a license from the NRC in order to construct the site; the application is not expected to be filed until 2004. The state of Nevada filed lawsuits against Abraham, President Bush, the DOE, the NRC, and the Environmental Protection Agency, seeking to block the future development of this site.

The commercial prospects for nuclear energy have faded. The decommissioning of nuclear plants in the early twenty-first century will be a huge undertaking. The cost, per plant, will be more than one billion dollars. Utility customers will pay for the costs in higher utility rates, but power companies will have to devote significant amounts of time, energy, and money to complete the process.

further readings

"Nevada Yucca Mountain Lawsuits." Yucca Mountain: Eureka County Nuclear Waste Page. Available online at <www.yuccamountain.org/court/lawsuits.htm> (accessed August 9, 2003).

cross-references

Energy Department; Environmental Law; Public Utilities; Solid Wastes, Hazardous Substances, and Toxic Pollutants.

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Nuclear Capability and Nuclear Energy

NUCLEAR CAPABILITY AND NUCLEAR ENERGY

Nuclear proliferation in the greater Middle East is a central issue in international affairs.

In the 1990s and into the twenty-first century, the issue of nuclear weapons in the Greater Middle East came to the fore as never before. Several developments played a role in this change: In 1998 nearby India and Pakistan almost simultaneously tested several nuclear weapons each. In 2002 these nations' ongoing conflict over Kashmir brought them close to the nuclear brink. Then came reports of the transfer of nuclear technology and materials from Pakistan to North Korea and perhaps also Iran. Other reports suggested that Pakistan considered its nuclear program to be an "Islamic bomb" enterprise that could provide extended deterrence to Israel's nuclear threat to the Arabs. Israel implied that it would use nuclear weapons if attacked by Iraq with chemical or biological weapons. Also of great concern was the proliferation of various delivery systemsballistic and cruise missiles, long-range aircraft abetted by aerial refuelingby several states in the region that might be joined to nuclear weapons arsenals. Around the world fears grew that terrorist organizations such as al-Qaʿida might somehow acquire nuclear weapons or materials for a "dirty" nuclear weapon derived from radioactive wastes. There were also increasing fears about Iraq's acquisition of nuclear weaponsa major rationale for the U.S.-led coalition's invasion of Iraq in 2003and Iran's seemingly imminent development of nuclear weapons.


Israel

Israel was the first of the nations in the region to cross the nuclear threshold. But despite a growing body of writings about the history of its nuclear program, vast gaps remain in what is known about the size of its arsenal, the dates of its initial deployments, and its current command-and-control structure. It appears that the initial decisions to move toward nuclear weapons status were made shortly after the Jewish state was created. Crucial to Israel's nuclear development was its nuclear cooperation with France, which grew out of the two nations' close relations at the time of the 1956 Suez War and continued until 19671968. Israel's nuclear development was centered on the French-supplied Dimona reactor, which went into operation around 1961, and continued to produce plutonium despite remonstrances from the Kennedy administration and some limited U.S. inspections.

Israel probably began plutonium separation and the deployment of operational nuclear weapons between the 1967 and 1973 Arab-Israel wars, with the Soviet Union's active involvement in the Suez "war of attrition" (19691970) perhaps serving as a final trigger. In 1973 Israel's implicit threats to use nuclear weapons after the initial military setbacks in Sinai and on the Golan Heights appear to have impelled the U.S. arms resupply airlift after initial hesitation.

In 1979 U.S. satellites detected a flash over the southern Indian Ocean that was widely, though not definitively, attributed to an Israeli or joint Israeli-South African nuclear test. In 1986 Mordechai Vanunu, a disaffected Israeli who had worked at the Dimona reactor, leaked voluminous information and photographs that revealed the scope of the Israeli nuclear program. Those disclosures, now widely considered credible, indicated a program consisting of both fission and fusion weapons, involving up to or more than 200 weapons, mounted on delivery systems that could cover the entire Middle East. The latter delivery systems included now longer-range Jericho missiles (perhaps up to 1,500 miles), F-16 fighter aircraft with aerial refueling capability, andperhapsthree diesel submarines purchased from Germany.

Various rationales have been offered for the Israeli nuclear program. The main rationale is that the program serves as a credible deterrent against the threat of an overwhelming Arab conventional force, which some deem inevitable. The size of Israel's program appears to imply the prospective use of tactical nuclear weapons in such a scenario, backed by a threat against cities. Other rationales for the nuclear program are that it offers increased assurance of American arms resupply during crises; it may convince Arab nations of Israel's permanence, thereby nudging them along in the "peace process"; and it may deter involvement in the Arab-Israeli conflict by powerful peripheral nations such as Iran, Pakistan, and Turkey, the latter semi-allied to Israel.


Iraq

Iraq's initial efforts to become the second Middle Eastern nuclear power were thwarted by Israel's bombing of the Osirak reactor in Baghdad in 1981. During the subsequent decade, Iraq allegedly built a clandestine nuclear infrastructure with the aid of numerous Western suppliers of relevant technologies, most notably that of gas centrifuges. That operation apparently was vastly underestimated by Western intelligence services, and the full scope of the program was revealed only in the wake of Iraq's defeat in the Gulf War of 1991 and its subsequent submission to United Nations inspections, which appear to have resulted in the dismantling of part of Iraq's nuclear infrastructure. In the aftermath of the 2003 invasion, however, the status of the Iraqi nuclear program was unclear. Little evidence was found. Various analysts suggested that intelligence reports had overstated the program; that it was well hidden by the Saddam regime; or that prior to the invasion it had been dismantled or the evidence moved to Syria or elsewhere outside of Iraq.


Iran, Algeria, and Libya

Since the end of the Iran-Iraq War in 1988 and subsequent to the Gulf War, Iran is widely believed to have embarked on an energetic effort to acquire nuclear weapons. That effort is centered on its nuclear research complex at Isfahan. Reports suggest extensive outside assistance, particularly from Pakistan and perhaps from China and Russia. There are reports of work on centrifuge technology, and on plutonium production reactors. Israel in particular dreads the possible advent of an Iranian nuclear weapons program that would include long-range missiles capable of reaching Israel.

During the latter part of the shah's reign, Iran embarked on a program to build several nuclear reactors. One was nearly completed by a West German firm. In 2003 Iran was negotiating with Russia over the building of four new reactors, plans that were fiercely opposed by the United States. One reactor, at Bushehr, is apparently under construction.

Algeria has acquired a small nuclear reactor, causing anxiety in Western Europe over the threat that Islamic fundamentalism could lead to a European-Algerian conflict. Libya reportedly has made efforts to acquire nuclear weapons or technology, but to no avail. In December 2003, Libya announced the cessation of all of its nuclear, chemical, and biological weapons programs.


Conclusion

The vast oil and gas resources of the Middle East presumably render almost superfluous the acquisition of nuclear power reactors for peaceful purposes. Statements about generating electricity appear to provide rhetorical cover for intended nuclear weapons programs.

Nuclear disarmament is unlikely to be achieved in the region in the foreseeable future. Israel clearly sees nuclear deterrence as vital to its survival. It could not conceivably abandon its stockpile unless Pakistan did so as well, which would require India also to disarm, and thus also China, the United States, and Russia. That is a daunting row of dominoes.

see also dimona.


Bibliography


Aronson, Shlomo. The Politics and Strategy of Nuclear Weapons in the Middle East. Albany: State University of New York Press, 1992.

Burrows, William E., and Windrem, Robert. Critical Mass: The Dangerous Race for Superweapons in a Fragmenting World. New York: Simon and Schuster, 1994.

Cohen, Avner. Israel and the Bomb. New York: Columbia University Press, 1998.

Cordesman, Anthony. Weapons of Mass Destruction in the Middle East. Washington, DC: Center for Strategic and International Studies, 2003.

Feldman, Shai. Israeli Nuclear Deterrence: A Strategy for the 1980s. New York: Columbia University Press, 1982.

Hersh, Seymour. The Samson Option: Israel's Nuclear Arsenal and American Foreign Policy. New York: Random House, 1991.

Jones, Rodney W., McDonough, Mark G., et al. Tracking Nuclear Proliferation: A Guide in Maps and Charts, 1998. Washington, DC: Carnegie Endowment for International Peace, 1998.

Khan, Saira. Nuclear Proliferation Dynamics in Protracted Conflict Regions: A Comparative Study of South Asia and the Middle East.

Aldershot, U.K., and Burlington, VT: Ashgate, 2002.

Peimani, Hooman. Nuclear Proliferation in the Indian Subcontinent: The Self-Exhausting "Superpowers" and Emerging Alliances. Westport, CT: Praeger, 2000.

Sagan, Scott D., and Waltz, Kenneth N. The Spread of Nuclear Weapons: A Debate Renewed. New York: Norton, 2003.

robert e. harkavy

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nuclear energy

nuclear energy, the energy stored in the nucleus of an atom and released through fission, fusion, or radioactivity. In these processes a small amount of mass is converted to energy according to the relationship E = mc2, where E is energy, m is mass, and c is the speed of light (see relativity). The most pressing problems concerning nuclear energy are the possibility of an accident or systems failure at a nuclear reactor or fuel plant, such as those which occurred at Three Mile Island (1979), Chernobyl (1986), and Fukushima (2011), and the potential threat to the continued existence of the human race posed by nuclear weapons (see disarmament, nuclear).

Nuclear Reactions

The release of nuclear energy is associated with changes from less stable to more stable nuclei and produces far more energy for a given mass of fuel than any other source of energy. In fission processes, a fissionable nucleus absorbs a neutron, becomes unstable, and splits into two nearly equal nuclei. In fusion processes, two nuclei combine to form a single, heavier nucleus. The most stable nuclei—those with the highest binding energies per nucleon holding their components together—are in the middle range of atomic weights, with the maximum stability at weights near 60. Thus, fission, which produces two lighter fragments, occurs for very heavy nuclei, while fusion occurs for the lightest nuclei.

Nuclear Fission

The process of nuclear fission was discovered in 1938 by Otto Hahn and Fritz Strassmann and was explained in early 1939 by Lise Meitner and Otto Frisch. The fissionable isotope of uranium, U-235, can be split by bombarding it with a slow, or thermal, neutron. (Slow neutrons are called "thermal" because their average kinetic energies are about the same as those of the molecules of air at ordinary temperatures.) The atomic numbers of the nuclei resulting from the fission add up to 92, which is the atomic number of uranium. A number of pairs of product nuclei are possible, with the most frequently produced fragments being krypton and barium.

Since this reaction also releases an average of 2.5 neutrons, a chain reaction is possible, provided at least one neutron per fission is captured by another nucleus and causes a second fission. In an atomic bomb, the number is greater than 1 and the reaction increases rapidly to an explosion. In a nuclear reactor, where the chain reaction is controlled, the number of neutrons producing additional fission must be exactly 1.0 in order to maintain a steady flow of energy.

Uranium-235, which occurs naturally as one part in 140 in a natural mixture of uranium isotopes, is not the only material fissionable by thermal neutrons. Uranium-233 and plutonium-239 can also be used but must be produced artificially. Uranium-233 is produced from thorium-232, which absorbs a neutron and then undergoes beta decay (the loss of an electron). Plutonium-239 is produced in a similar manner from uranium-238, which is the most common isotope of natural uranium. The average energy released by the fission of uranium-235 is 200 million electron volts, and that released by uranium-233 and plutonium-239 is comparable. Fission can also occur spontaneously, but the time required for a heavy nucleus to decay spontaneously by fission (10 million billion years in the case of uranium-238) is so long that induced fission by thermal neutrons is the only practical application of nuclear fission. However, spontaneous fission of uranium can be used in the dating of very old rock samples.

The development of nuclear energy from fission reactions began with the program to produce atomic weapons in the United States. Early work was carried out at several universities, and the first sustained nuclear chain reaction was achieved at the Univ. of Chicago in 1942 by a group under Enrico Fermi. Later the weapons themselves were developed at Los Alamos, N.Mex., under the direction of J. Robert Oppenheimer (see Manhattan Project).

Nuclear Fusion

Nuclear fusion, although it was known theoretically in the 1930s as the process by which the sun and most other stars radiate their great output of energy, was not achieved by scientists until the 1950s. Fusion reactions are also known as thermonuclear reactions because the temperatures required to initiate them are more than 1,000,000°C. In the hydrogen bomb, such temperatures are provided by the detonation of a fission bomb. The energy released during fusion is even greater than that released during fission. Moreover, the fuel for fusion reactions, isotopes of hydrogen, is readily available in large amounts, and there is no release of radioactive byproducts.

In stars ordinary hydrogen, whose nucleus consists of a single proton, is the fuel for the reaction and is fused to form helium through a complex cycle of reactions (see nucleosynthesis). This reaction takes place too slowly, however, to be of practical use on the earth. The heavier isotopes of hydrogen—deuterium and tritium—have much faster fusion reactions.

For sustained, controlled fusion reactions, a fission bomb obviously cannot be used to trigger the reaction. The difficulties of controlled fusion center on the containment of the nuclear fuel at the extremely high temperatures necessary for fusion for a time long enough to allow the reaction to take place. For deuterium-tritium fusion, this time is about 0.1 sec. At such temperatures the fuel is no longer in one of the ordinary states of matter but is instead a plasma, consisting of a mixture of electrons and charged atoms. Obviously, no solid container could hold such a hot mixture; therefore, containment attempts have been based on the electrical and magnetic properties of a plasma, using magnetic fields to form a "magnetic bottle." In 1994 U.S. researchers achieved a fusion reaction that lasted about a second and generated 10.7 million watts, using deuterium and tritium in a magnetically confined plasma. The use of tritium lowers the temperature required and increases the rate of the reaction, but it also increases the release of radioactive neutrons. Another method uses laser beams aimed at tiny pellets of fusion fuel to create the necessary heat and pressure to initiate fusion.

If practical controlled fusion is achieved, it could have great advantages over fission as a source of energy. Deuterium is relatively easy to obtain, since it constitutes a small percentage of the hydrogen in water and can be separated by electrolysis, in contrast to the complex and expensive methods required to extract uranium-235 from its sources. In 2007 China, the European Union, India, Japan, Russia, South Korea, and the United States formally established the International Thermonuclear Experimental Reactor (ITER) Organization to build an experimental fusion reactor at Cadarache in S France that would use the "magnetic bottle" approach. The Lawrence Livermore National Laboratory's National Ignition Facility, based in Livermore, Calif., and dedicated in 2009, is exploring the use of high-energy lasers focused on hydrogen fuel to achieve nuclear fusion.

Bibliography

See H. Foreman, ed., Nuclear Power and the Public (1970); R. C. Lewis, Nuclear Power Rebellion: Citizen vs. the Atomic Industrial Establishment (1972); C. K. Ebinger, International Politics of Nuclear Energy (1978); S. Glasstone, Sourcebook on Atomic Energy (1979); G. S. Bauer and A. McDonald, ed., Nuclear Technologies in a Sustainable Energy System (1983); G. H. Clarfield and W. W. Wiecek, Nuclear America (1984).

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Nuclear Energy

Nuclear Energy


Nuclear energy, strictly conceived, has received rather scant attention within the literature of science and religion. However, if the focus is broadened to include nuclear technologythat is, nuclear energy and nuclear weapons considered togetherthen there is a modest increase in its treatment.


Benefits and risks

Nuclear energy has long been viewed as an alternative energy source to coal and petroleum, which are currently the principal sources of energy. Coal and petroleum provide efficient sources of energy, but their combustion also generates considerable carbon dioxide that escapes into the atmosphere. Although a few dissenters remain, the vast majority of climatologists hold that the build up of carbon dioxide in the atmosphere creates a greenhouse effect. This greenhouse effect dramatically warms the planet, which leads, in turn, to global climate change, resulting in different impacts on different regions of the planet.

Nuclear energy provides an especially attractive alternative to coal and petroleum because it does not contribute to the concentration of carbon dioxide in the atmosphere. Shifting to nuclear energy could potentially lead to a cleaner, healthier environment without a reduction in the human consumption of energy. However, the benefits of nuclear energy must be weighed against its substantial costs and risks. The principal cost of nuclear energy occurs with the safe disposal of radioactive wastes. In addition to the costs of disposal, there is the risk that nuclear radiation could be released into the environment, either at the nuclear power plant or at the site of waste disposal. Such a release could be accidental, the result of equipment malfunction or human error. There is also the risk of an intentional release of nuclear radiation as an act of terrorism. Whether accidental or intentional, such a release could potentially destroy all biotic life in the affected area and make the area sterile for life for the foreseeable future.

Although as of 2002 there have been no intentional releases of nuclear radiation into the environment, there have been two serious accidents at nuclear power plants. In 1979, there was an accident at the Three Mile Island nuclear power plant in Pennsylvania. There was another accident in 1986 at the Chernobyl nuclear power plant in Ukraine. Although very little nuclear radiation escaped from the Three Mile Island accident, nuclear radiation did escape from the Chernobyl accident, causing substantial ecological damage and the deaths of a number of people.


Theological perspectives

Within the science and religion literature, Ian Barbour provides one of the few focused treatments of nuclear energy in his book Ethics in an Age of Technology (1993). Barbour begins his examination with a discussion of risk. If risk is defined as the probability of an accident multiplied by the magnitude of its consequences, then the risk posed by nuclear energy is low, compared to other daily activities, such as driving a car. However, Barbour argues that evaluations of such technological risks must also be influenced by assumptions about human nature and social institutions. Taking a Christian religious perspective, Barbour argues that the individual and social sin inherent in the human condition calls for extreme caution in the development of nuclear energy because the risks and consequences are so high.

Shifting his focus to the safe disposal of radioactive wastes, Barbour identifies three ethical issues. First, Barbour notes that an issue of regional justice arises because radioactive waste disposal imposes extreme risks for a local population in order to provide a national benefit for everyone. Intergenerational justice raises a second ethical issue. The present generation would enjoy the benefits of nuclear energy, but passes on some of the burdens and risks of waste disposal to future generations. Finally, Barbour identifies the loss of public confidence in governments and the energy industry as a third ethical issue. His point here is that historically government and industry have been secretive and have failed to protect the public, rather than being transparent and promoting public discourse concerning the benefits, costs, and risks of nuclear energy. Barbour believes that more promising energy alternatives lie in energy conservation and in the use of other renewal energy sources, such as solar power.

In the 1980s, several religious writers warned that nuclear weapons and nuclear war threatened not only human life but the ecological viability of the planet. Two Christian theologians, Gordon Kaufman and Sallie McFague, argued further that these interconnected challenges were rooted in what has become a flawed understanding of God's power. In Theology for a Nuclear Age (1985), Kaufman argues that the threat of nuclear war and annihilation elicits two contrasting responses from traditional Christian conceptions of God. On the one hand, nuclear annihilation is interpreted in eschatological terms as God's action to bring the present age to an end. On the other hand, the threat of nuclear war is discounted because of the view that an almighty creator God, who loves humans and the rest of creation, would not allow such a disaster to occur. Kaufman notes that both responses have the effect of obscuring and undermining the responsibility that humans have for their actions. While the traditional understanding of God as omnipotent may have been appropriate for earlier times, Kaufman argues that this understanding is no longer appropriate in a nuclear age. In light of the threat of nuclear weapons, Kaufman proposes that Christian theologians need to reconceive of God's power, moving from a dualistic to an interdependent understanding. This would require theologians to rethink their formulation of the symbols "God" and "Christ." McFague concurs with Kaufman's analysis in her book Models of God: Theology for an Ecological, Nuclear Age (1987). As alternative models for thinking about God, McFague proposes mother, lover, and friend.

While both Kaufman and McFague were thinking initially of the threat of nuclear annihilation, they both extend their analyses to include ecological concerns. Thus, whether conceived broadly as nuclear technology, or more narrowly as nuclear energy, the literature of science and religion has consistently seen critical ecological implications for the planet.


See also Ecology; Ecology, Ethics of; Ecology, Religious and Philosophical Aspects; Ecology, Science of; Greenhouse Effect


Bibliography

barbour, ian. ethics in an age of technology. san francisco: harper, 1993.

kaufman, gordon d. theology for a nuclear age. manchester, uk: manchester university press, 1985.

mcfague, sallie. models of god: theology for an ecological, nuclear age. philadelphia: fortress press, 1987.

richard o. randolph

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Energy, Nuclear

Energy, Nuclear


Nuclear energy is produced during reactions in the nucleus of an atom. Atoms can be thought of as miniature solar systems with the nucleus at the center like a sun and electrons orbiting around it like planets. Densely packed neutrons and protons make up the nucleus, which is held together with great force, the "strongest force in nature." When the nucleus is bombarded with a neutron, it can be split apart, a process called fission. Uranium is the heaviest natural element and has ninety-two protons. Because uranium atoms are so large, the atomic force that binds it together is relatively weak, so fission is more likely with uranium than other elements.

Fusion, another type of nuclear reaction, is the joining of atoms and can occur with elements of low atomic number, such as hydrogen, the lightest element, which has one proton. The first time physicists achieved fusion was in the 1950s with the hydrogen bomb. Fusion releases a tremendous amount of energy, but the energy is released so quickly and uncontrollably that fusion has not yet been harnessed as a usable source of energy.

Physicists formulated the principles of nuclear power in the early twentieth century. In 1939 German scientists discovered the process of nuclear fission, triggering a race with American scientists to use the massive energy release of fission to create a bomb. The atomic bomb was created by the United States in 1945; it was used to destroy Hiroshima and Nagasaki in Japan at the end of World War II.

After World War II, atomic power was seen as a potential new energy source. The U.S. government thought atomic explosions would be a laborsaving way to dig canals and reservoirs and to mine for gas and oil. As late as the 1960s, bombs were being set off above and below ground to test different ideas, resulting in radionuclide contamination of the soil that is still being addressed today.

A more successful use of atomic power was nuclear reactors that controlled the release of energy. Admiral Hyman G. Rickover guided the development of small reactors to power submarines, greatly extending their range and power. By the late 1950s, nuclear power was being developed for commercial electric power, initially in England. Morris, Illinois, was the site of the first U.S. commercial reactor. Nuclear weapons research was advanced by Russia and the United States during the Cold War, and a number of other countries, including China and India, have now developed nuclear weapons.


Nuclear Power Plants

Uranium is one of the least plentiful of minerals, making up only two parts per million (ppm) in the earth's crust. But because of its radioactivity, it is a plentiful supply of energy: one pound of uranium has as much energy as three million pounds of coal.

In 2002 there were 104 nuclear power reactors licensed to operate in the United States, and they accounted for 20 percent of the nation's electricity production and more than one-fourth of nuclear power capacity in the world. Many other countries, including France, Japan, and the United Kingdom, have nuclear power plants. Nuclear power accounts for about 80 percent of France's electrical power production.


How Nuclear Power Works

In nuclear power plants, neutrons collide with uranium atoms, splitting them. This split releases neutrons from the uranium that, in turn, collide with other atoms, causing a chain reaction. This chain reaction is regulated (or governed) by "control rods" that absorb neutrons. Fission releases energy that heats water to approximately 520°F in the core of the plant. The steam that is created is then used to spin turbines that are connected to generators, which produce electricity.

After the steam is used to power the turbine, it is cooled off and condensed into water. Some plants use water from rivers, lakes, or the ocean to cool the steam; returning this water to the environment can cause thermal pollution. Other plants use the hourglass-shaped cooling towers that are the familiar hallmark of many nuclear plants. For every unit of electricity produced by a nuclear power plant, about two units of wasted heat are sent into the environment.

Nuclear reactors are also used to power military submarines and surface ships. As in land-based reactors, nuclear-powered vessels use the heat produced by the chain reaction to make steam for a turbine. The turbine is connected to the propeller shafts aboard the ships rather than generators that produce electricity.


Radioactive Pollution from Nuclear Energy

By 1995 over 32,000 metric tons of highly radioactive waste had been produced by American nuclear reactors. That number is expected to rise to 75,000 metric tons by 2015.

Before the mid-1970s, the plan for fuel removed from nuclear reactors was to reprocess it and recycle the uranium into new fuel. Because a by-product of reprocessing is plutonium, a highly unstable element that can be used to make nuclear weapons, President Jimmy Carter ordered the end of reprocessing in 1977 due to security risks. Reprocessing also had a difficult time competing economically with the production of new uranium fuel.

Since then, the U.S. Department of Energy (DOE) has been studying storage sites for the long-term burial of such waste and is now focusing on Yucca Mountain in Nevada. The DOE has built a full-scale system of tunnels in the mountain at a cost of over $5 billion. Although the Yucca Mountain site is still controversial, there are no other sites presently under consideration.

Meanwhile, radioactive waste continues to be stored at the nuclear plants where it is produced. The most common option is to store it in a large steel-lined pool. As these pools fill up, fuel rods are stored in large steel and concrete casks.

see also Radioactive Fallout; Radioactive Waste; Thermal Pollution; Yucca Mountain.

Bibliography

mazuzan, george t., and walker, j. samuel. (1984). controlling the atom: the beginnings of nuclear regulation 19461962. berkeley: university of california press.

asimov, isaac. (1991). atom: journey across the subatomic cosmos. new york: truman talley books.

daley, michael j. (1997). nuclear power: promise or peril? minneapolis: lerner publications.

ramsey, charles b., and modarres, mohammad. (1998). commercial nuclear power: assuring safety for the future. new york: john wiley & sons.


internet resource

columbia college web site. "nuclear energy guide." available from http://www.spacekid.net/nuclear.

David Lochbaum

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Nuclear Power

NUCLEAR POWER

The use of nuclear power to generate electricity began in the late 1950s. At the close of the twentieth century, nuclear power was supplying about 20 percent of the electricity generated in the United States and about 16 percent worldwide.

Nuclear power has been the most controversial of all energy sources. Public concerns about reactor safety and environmental issues were especially heightened by the 1979 accident at Three Mile Island in Pennsylvania and the much more serious accident in 1986 at Chernobyl in Ukraine. Construction of new nuclear power plants has slowed considerably since then, and some industrialized countries may abandon this energy source. Concerns about disposal of spent nuclear fuel have also affected public confidence in nuclear power. Although many scientists believe that spent fuel and other highly radioactive wastes can be disposed of safely in a geologic repository located far below ground, disposal sites for these wastes have not been approved, and the need to store spent fuel until disposal facilities are available raises safety and environmental concerns. The public also has not supported development of new disposal facilities for low-level radioactive wastes generated at nuclear power plants and in many other commercial activities. Other factors contributing to public concerns have included environmental problems at sites operated under nuclear weapons programs and fears that plutonium produced at nuclear power plants could be diverted for use in nuclear weapons.

Public concerns about safety and environmental issues have been exacerbated by financial risks in the nuclear power industry, including the high cost of constructing and operating nuclear power plants, potentially high costs of decommissioning nuclear facilities, and costs for storage and disposal of spent fuel and other nuclear wastes. Nuclear power may not remain competitive with other energy sources unless these costs are reduced.

Proponents of nuclear power emphasize its significant benefits. Past accidents notwithstanding, the nuclear power industry has an enviable safety record in those industrialized countries that require extensive reactor safety systems. Uranium used in nuclear fuel is abundant, which reduces dependence on foreign energy supplies and preserves oil and natural gas for essential uses. Nuclear reactors produce the greatest amount of energy per amount of fuel of any nonrenewable energy source, and the environmental damage from use of nuclear power is less than with other major energy sources, especially coal. Perhaps most importantly, the use of nuclear power in place of coal, oil, and natural gas greatly reduces emissions of carbon dioxide, which is believed to be a factor in global warming, and other hazardous air pollutants.

Given these benefits, many energy experts believe that nuclear power is an important energy source for the future. A major challenge will be to address public concerns about safety and environmental issues. The keys to meeting this challenge may include resolving concerns about nuclear waste disposal, siting of new reactors in remote areas, developing smaller reactors that incorporate passive safety systems, and using standard power plant designs to lower construction and operating costs.

David C. Kocher

(see also: Chernobyl; Energy; Not In My Backyard [NIMBY]; Nuclear Waste; Risk Assessment, Risk Management; Three Mile Island )

Bibliography

Cohen, B. L. (1990). The Nuclear Energy Option: An Alternative for the 90s. New York: Plenum Press.

Gofman, J. W., and Tamplin, A. R. (1971). Poisoned Power: The Case Against Nuclear Power Plants. Emmaus, PA: Rodale Press.

Jungk, R. (1979). The New Tyranny: How Nuclear Power Enslaves Us. New York: Grosset & Dunlap, Inc.

Rhodes, R. (1993). Nuclear Renewal: Common Sense about Energy. New York: Whittle Books.

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nuclear energy

nuclear energy is obtained by releasing the binding energy which holds together atomic nuclei, for example, in uranium. This fission process was used in the development of the atomic bomb during the Second World War, but by the mid-1950s scientists had been able to control it within the reactor cores of experimental power stations to produce utilizable energy. The nuclear reactor releases energy in the form of heat which is used to generate steam, and the steam to generate electricity. Plutonium, a highly fissile material used in the manufacture of nuclear bombs, is a byproduct.

The Atomic Energy Authority oversaw the development of the nuclear industry, which from the outset proved controversial on strategic, cost, and environmental grounds. When in 1956 power was switched from the first generator at Calder Hall to the National Grid it was hailed as a great achievement but scant attention was paid to the real purpose of the programme, to breed plutonium for Britain's nuclear deterrent. An experimental fast reactor, built at Dounreay in the north of Scotland, began operation in 1959, and paved the way for the first fast-breeder reactor power station.

From the standpoint of the 1950s, discounting the perceived need for a nuclear deterrent during the Cold War, nuclear power seemed an excellent investment, given the likelihood that unit costs could be as little as a fifth that of fossil-fuel electricity. In the ensuing years the industry expanded, though the balance of cost advantage remained uncertain. But the upsurge of oil prices in the 1970s, coupled with uneasy labour relations in the coal-mines, added to the comparative economic attraction of nuclear power, which began to accelerate dramatically, as did the nuclear component of electricity output.

Successive British governments since the 1950s wanted to lessen dependence on petroleum-exporting countries, but with the development of North Sea oil and gas, this was less pressing. Energy requirements in general began to be adjusted as a response to the energy crisis, and this brought about a reassessment of the high-energy role of nuclear power. While in its early stages of development nuclear energy appeared environmentally inoffensive to the general public, increased concern was voiced about its safety following major disasters at power plants internationally during the 1980s, and about the twin problems of waste disposal and decommissioning of redundant plant.

Ian Donnachie

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nuclear energy

nuclear energy Energy released during a nuclear reaction as a result of the conversion of mass into energy according to Einstein's equation E = mc2. The conversion involves the binding energy of the nucleus of an atom. Nuclear energy is released in two ways: by fission (splitting a heavy atomic nucleus in two) and by fusion (combining light aomic nuclei). Fission, discovered in 1938, is the process responsibile for the atomic bomb and for nuclear reactors in nuclear power stations that produce electricity. In 1942, German-born US physicist Enrico Fermi achieved the first sustained nuclear chain reaction. Fusion provides the energy for the stars and the hydrogen bomb. It also offers the prospect of cheap energy, once a method has been perfected for controlling fusion reactions. See also critical mass; Manhattan Project; nuclear weapon

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Nuclear Energy (Issue)

NUCLEAR ENERGY (ISSUE)


In 1954 the U.S. government authorized private ownership of nuclear reactors as part of President Dwight D. Eisenhower's (19531961) Atoms for Peace initiative, paving the way for utility companies to build nuclear power plants. By the mid-1960s many utility companies had "gone nuclear," though building reactors proved far more costly than the early hopes; reactor energy did not meet expectations that they could provide power for pennies a day.

Most U.S. citizens' sole experience with the power of the atom was the devastating bombing of Hiroshima and Nagasaki in 1945; accordingly, some opposed the whole issue of nuclear energy. In California, after an earthquake disrupted construction, residents demanded the cancellation of the planned Bodega Bay reactor which was sited on a geological fault. Inhabitants of New York City resisted the siting of a plant within its borders because of the dense population.

Regardless of fears about nuclear weaponry, most people liked the idea of building atomic energy plants. The country was using increasing amounts of electrical energy (produced by burning fossil fuels which created air pollution. Nuclear power promised to be cheaper and cleaner. Moreover, nuclear power had the aura of a neat, high-tech solution to the complicated problems that people had come to expect from politics and business. When an oil embargo by countries in the Middle East hit in 19731974, the United States faced shortages of electricity, gasoline, and heating oil. Factories and schools were shut down. There were also cancellations of commercial airline flights, electrical brownouts, and increased lines at gasoline service stations. Blackouts plagued cities and industries, most spectacularly in New York City on July 13 and 14, 1977. High fuel prices reduced the productivity of U.S. industry. To all of these complaints the supporters of nuclear energy claimed a solution. They also argued that nuclear energy would solve the balance of payments problem and neutralize the damage to the international monetary system that was being done by the heavy U.S. imports of fuel.

To some U.S. citizens, atomic energy seemed to offer a way for the nation to achieve energy independence. Support for nuclear power steadily increased. Meanwhile the anti-nuclear movement carried forward the traditions of the anti-Vietnam War movement and many opponents initiated demonstrations at nuclear power plants. At Seabrook Station in New Hampshire, opponents staged sit-ins, civil disobedience, celebrity concerts, and rallies. Supporters of nuclear energy ridiculed the protesters' fear of technology and charged the anti-nuclear movement with a vaguely un-American variety of consumer elitism. One writer caricatured the protesters as "vegetarians in leather jackets who drive imported cars to Seabrook listening to the Grateful Dead on their Japanese tape decks amid a marijuana haze."

Regardless of this culture clash, the United States' energy crisis was real and was caused by several factors. One was that in the 1950s and 1960s strategic geopolitical concerns led the government to promote the import of fuel from overseas, especially from the Middle East. Another was that President Richard Nixon's (19691974) 1971 attempt to halt inflation (called the New Economic Policy) had imposed price controls on the entire economy. But when the other restrictions were lifted, oil remained regulated, keeping the price artificially low to consumers and increasing demand. The United States was extravagant in its use of energyfew U.S.-made cars got better than 10 miles to the gallon, and homes and businesses were poorly insulated and inefficiently designed. Diverse special interests had skewed portions of the government's oversight and regulation of the oil industry toward their particular interests, and passing general legislation regarding energy became a political nightmare. Accordingly, efforts to develop a consistent energy policy throughout the 1970s were diluted and diverted. The decade ended much as it began, with the United States wastefully consuming inordinate amounts of energy, subject, once again, to an oil crisis.

During the 1960s utility companies were aware of the coming energy shortage. One of their methods to prepare for the shortfall was to construct nuclear reactors. In January 1973 there were 27 functioning reactors in the United States, providing only five percent of the power generated. Fifty-five plants were under construction, and an additional 78 were in the planning stages. The majority, however, were never built. Security expenses, nuclear-waste disposal costs, and construction overruns made the return on investment slim in nuclear-power plants.

In 1974, seeking to assist the nuclear industry, the administration of President Gerald R. Ford (19741977) disbanded the Atomic Energy Commission (AEC), which had overseen U.S. nuclear development for 28 years. In its place were constructed two more industry-friendly commissions: the Nuclear Regulatory Commission (NRC) and the Energy Research and Development Administration (ERDA). The latter agency was empowered to develop new energy sources and market U.S. nuclear industry abroad. The NRC streamlined the licensing and commission of reactor projects, but many of the old problems remained. Safety was a pressing issue: fires underscored the potential for a catastrophic accident at nuclear plants (at the Indian Point Two reactor in New York in 1971, the Zion reactor in Illinois in 1974, the Trojan reactor in Oregon in 1974, and the Brown's Ferry reactor in Alabama in 1975). In 1975 the Union of Concerned Scientists presented the White House with a petition signed by 2,000 scientists which called for a reduction in nuclear construction. Public opinion followed that of the scientists. Environmental groups increasingly challenged the construction of nuclear projects in the NRC and in the courts, delaying the deployment of projects and driving up the start-up costs. The 19781979 protests at the Seabrook nuclear power plant in New Hampshire were particularly vocal and drew national attention to the issue. Then, in the spring of 1979, an accident at the Harrisburg, Pennsylvania, Three Mile Island nuclear power plant resulted in a partial core meltdown. Although no one was injured, the accident terrified the public and placed the future of the nuclear industry in jeopardy.

On April 26, 1986, near the town of Pripyat in the Soviet Union, attention was again focused on the issue of safety in the nuclear power industry. One of four nuclear reactors at the Chernobyl Nuclear Power Station in the Ukraine exploded with such force that the roof of the building was completely blown off. Eight tons of radioactive materials were scattered about the region immediately surrounding the plant. Airborne radioactivity from the blast rained down on northern Europe and Scandinavia. Fallout contaminating farm produce was measured as far away as Scotland. Engineers at Chernobyl had accidentally initiated an uncontrolled chain reaction in the reactor's core during an unauthorized test in which they unlawfully incapacitated the reactor's emergency systems. In the immediate aftermath of the catastrophe, more than 30 people lost their lives. Moreover, one estimate placed the number at 20,000 who would eventually live shortened lives as a result of the effects of their exposure to radiation from the accident.

In the United States experts argued that the disaster at Chernobyl was not pertinent to the domestic nuclear industry. They noted that the technology employed at Chernobyl was not being used in the United States. The Soviets, they pointed out, were using a weapons-material production reactor to generate electricity for their domestic marketsomething not done in the United States. Furthermore, the Chernobyl reactor lacked a containment buildinga required safety component mandated for all U.S. reactors. Nevertheless, many in the United States drew uneasy parallels between Chernobyl and Three Mile Island, among them, that operator error and equipment failure was possible in the nuclear industry. The consequences of a single major mistake could be catastrophic.

During the 1980s scores of "anti-nuke" organizations warned of the hazards of nuclear energy and protested plant construction and operation. In Seabrook, New Hampshire, protesters rallied around the citizens' action group, the Clamshell Alliance, to oppose the building of two nuclear reactors. By 1987 the utility that owned Seabrook was near bankruptcy, in part due to the increased vigilance of oversight safety committees insisted upon by the Clamshell Alliance. At Long Island's Shoreham nuclear facility the story was much the same. Besieged by civic-group opposition and having far exceeded initial cost estimates of $241 million (its actual cost to the utility had surpassed $5 billion), the Shoreham "nuke" was closed by the state government in 1988. The utility that owned Shoreham had failed to develop an adequate evacuation plan for the region of Long Island that would be affected in the event of a meltdown. Sold to the state government for one dollar, the completed plant was to be dismantled even before it opened.

Cost overruns and construction problems continued to plague the industry. Florida's St. Lucie Two plant cost about four times its original estimate of $360 million. This price, as it would turn out, was a relative bargain. By mid-decade Michigan's Midland nuclear power plant (initial cost estimate: $267 million) had cost the utility constructing it $4.4 billion, and it was nine years behind schedule. In the West, at the Diablo Canyon Plant, earthquake supports were installed backwards.

Another problem the industry faced was the disposal of irradiated fuel rods. During the 1980s utility companies stored these rods on site at the power plants, in large vats resembling swimming pools, but this was only considered a temporary solution. In 1982 Congress passed the Nuclear Waste Policy Act. The act called upon the Department of Energy (DOE) to find a suitable site to bury radioactive waste. DOE, however, was unsuccessful in locating a site that included both the necessary stable rock formation (free of groundwater) and the requisite local public support. By the end of the 1980s, no solution to the problem of nuclear waste had been found.


FURTHER READING

Glasstone, Samuel. Sourcebook on Atomic Energy. Princeton, NJ: D. Van Nostrand, 1967.

Inglis, David R. Nuclear Energy: Its Physics and Its Social Challenge. Reading, MA: Addison-Wesley, 1973.

Marion, Jerry B., and Roush, Marvin L. Energy in Perspective, 2d ed. New York: Academic Press, 1982.

Stobaugh, Robert, Daniel Yergin, eds. Energy Future: Report of the Energy Project at the Harvard Business School. New York: Random House, 1979.

Williams, Robert C., Philip L. Cantelon, eds. The American Atom: A Documentary History of Nuclear Policies from the Discovery of Fission to the Present, 19391984. Philadelphia: University of Pennsylvania Press, September, 1984.

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nuclear power

nu·cle·ar pow·er • n. 1. electric or motive power generated by a nuclear reactor. 2. a country that has nuclear weapons. DERIVATIVES: nu·cle·ar-pow·ered adj.

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Nuclear Energy

Nuclear Energy

How Nuclear Energy Works
Domestic Nuclear Energy Production
Outlook for Domestic Nuclear Energy
International Production
Aging Nuclear Power Plants
A New Generation of Nuclear Plants
Nuclear Safety
Radioactive Waste
Radioactive Waste Disposal

In the early 1970s many Americans favored the use of nuclear power to generate electricity. Reactors had been in operation since 1956, providing what appeared to be cleaner, more efficient energy than power plants that burned fossil fuels. In addition, the nation had plenty of uranium, the fuel used in U.S. reactors, so nuclear plants could help reduce U.S. dependence on foreign energy sources.

However, by the beginning of the twenty-first century opinion had turned: Voices were being raised in the United States—as well as around the world—in opposition to building additional nuclear power plants. In fact, some people wanted existing plants shut down. Two incidents—an accident in 1979 at the Three Mile Island nuclear power plant in Pennsylvania, in which the reactor core lost coolant and partially melted, and the 1986 catastrophe at Chernobyl in the Soviet Union, in which a reactor exploded and released huge amounts of radioactivity into the atmosphere—greatly increased concerns about the safety of nuclear power. Reports of design flaws, cracks, and leaks in other reactors fueled public fears. Furthermore, the safe disposal of radioactive waste, which is a by-product of nuclear energy, had become a scientific and political headache.

Supporters of nuclear power say it is as safe as any other form of energy production, as long as it is monitored properly. They point to the growing problems related to the use of fossil fuels: global warming, acid rain, and the damage caused by mining and transporting fossil fuels. This concern over fossil fuels has led some environmentalists who had previously opposed nuclear power to reconsider their position. Nonetheless, environmental, safety, and economic concerns have restrained growth in the nuclear industry since the mid-1970s. Figure 5.1 shows that from 1988 through 2007 nuclear energy’s share of electricity production leveled off at about 19%.

How Nuclear Energy Works

In a nuclear power plant, fuel (uranium in the United States) in the core of the reactor generates a nuclear reaction (fission) that produces heat. In a pressurized water reactor, the heat from the reaction is carried away by water under high pressure, which heats a second water stream, producing steam. (See Figure 5.2.) The steam runs through a turbine, making the attached generator spin, which produces electricity. The large cooling towers associated with nuclear plants cool the steam after it has run through the turbines. A boiling water reactor works much the same way, except that the water surrounding the core boils and directly produces the steam, which is then piped to the turbine generator.

The challenges faced by those who operate a nuclear power reactor include finding fuel (uranium 235) that will sustain a chain reaction, maintaining the reaction at a level that yields heat but does not escalate out of control and explode, and coping with the radiation produced by the chain reaction.

Radioactivity

Radioactivity is the spontaneous emission of energy and/or high-energy particles from the nucleus of an atom. One type of radioactivity is produced naturally and is emitted by radioactive isotopes (or radioisotopes), such as radioactive carbon (carbon 14, or C-14) and radioactive hydrogen (H-3, or tritium). The energy and high-energy particles that radioactive isotopes emit include alpha rays, beta rays, and gamma rays.

Isotopes are atoms of an element that have the usual number of protons but different numbers of neutrons in their nuclei. For example, twelve protons and twelve neutrons make up the nucleus of the element carbon. One isotope of carbon, C-14, has twelve protons and fourteen neutrons in its nucleus.

Radioisotopes (such as C-14) are unstable isotopes, and their nuclei decay (break apart) at a steady rate. Decaying radioisotopes produce other isotopes as they emit energy and/or high-energy particles. If the newly formed nuclei are radioactive as well, they emit radiation and change into other nuclei. The final products in this chain are stable, nonradioactive nuclei.

Radiation and radioisotopes reach our bodies daily, emitted from sources in outer space and from rocks and soil on earth. Figure 5.3 shows that radon is the largest source of radiation to which humans are exposed. This gas is formed in rocks and soil from the radioactive decay of radium. Most prevalent in the northern half of the United States, radon can enter cracks in basement walls and remain trapped there. Prolonged exposure to high levels of radioactive radon is thought to lead to lung cancer. Other radioisotopes, in minute quantities, are used in medicine as diagnostic tools.

Radiation was discovered at the beginning of the twentieth century by Antoine Henri Becquerel (1852–1908), Marie Curie (1867–1934), and Pierre Curie (1859–1906). Decades later, other scientists determined that they could unleash energy by artificially breaking apart atomic nuclei. Such a process is called nuclear fission. Scientists discovered that they could produce the most energy by bombarding the nuclei of an isotope of uranium called uranium 235 (U-235). The fission of a U-235 atom releases several neutrons, which have the potential to penetrate other U-235 atomic nuclei and cause them to fission. In this way the fission of a single U-235 atom begins a cascading chain of nuclear reactions. (See Figure 5.4.) If this series of reactions is regulated to occur slowly, as it is in nuclear power plants, the energy emitted can be captured for a variety of uses, such as generating electricity. If this series of reactions is allowed to occur all at once, as in an atomic bomb, the energy emitted is explosive. (Plutonium 239 can also be used to generate a chain reaction similar to that of U-235.)

Mining Nuclear Fuel

In the United States, U-235 is used as nuclear fuel. Most of it is found in the form of ore in Wyoming and New Mexico, where it is mined using methods similar to those for other metal ores. The one difference is that uranium mining can expose workers to radioactivity. Uranium atoms split by themselves at a slow rate, causing radioactive substances such as radon to accumulate slowly in the deposits.

After it is mined, uranium must be concentrated, because uranium ore generally contains only 0.1% uranium metal by weight. To concentrate the uranium, it goes through a process called milling: the ore is first crushed, and then various chemicals are poured slowly through the crushed ore to dissolve the uranium. When the uranium—called yellowcake because of its color—is extracted from this chemical solution, it is 85% pure by weight. However, this uranium is 99.3% nonfissionable U-238 and only 0.7% fissionable U-235. Other processes are necessary to create enriched uranium, which has a higher percentage of fissionable uranium.

To enrich uranium, yellowcake is first converted into uranium hexafluoride (UF6). Cylinders of this gas are sent to a gaseous diffusion plant, where the uranium is heated in a furnace (UF6 vaporization). (See Figure 5.5.) The enriched uranium is then converted into oxide powder (UO2), which is made into fingertip-sized fuel pellets. The pellets are less than 0.5 inches (1.3 cm) in diameter, but each one can produce as much energy as 120 gallons (454 L) of oil. The pellets are stacked in rods, which are tubes about 12 feet (3.7 m) long. Many rods (see “Control rods” in Figure 5.2) are bundled together in assemblies, and hundreds of these assemblies make up the core of a nuclear reactor.

Domestic Nuclear Energy Production

The percentage of U.S. electricity supplied by nuclear power grew considerably during the 1970s and early to mid-1980s and then leveled off. (See Figure 5.1.) According to the Energy Information Administration (EIA), in Annual Energy Review 2007 (June 2008, http://www.eia.doe.gov/aer/pdf/aer.pdf), nuclear power supplied only 5% of the total electricity generated in the United States in 1973. In 2007 nuclear electricity net generation reached 806.5 billion kilowatt-hours (kWh), or 19% of the nation’s electricity. Thirty-one states had 104 nuclear reactors in operation in 2005. Figure 5.6 shows that most of these reactors were located east of the Mississippi River.

No new nuclear power plants have been ordered since 1978, and some have closed. (See Table 5.1.) The number of operable nuclear generating units peaked in 1990 with 112 units; as of 2007, 104 units were operating. (See Figure 5.7.) The decline in nuclear power plants stems from several related issues. Financing is difficult to find, and construction has become more expensive, partly because of longer delays for licensing, but also because of regulations instituted following the Three Mile Island accident in 1979. Still, output of electricity at existing plants has increased, achieved largely through an increase

TABLE 5.1 Nuclear generating units, 1955–2007
SOURCE: Adapted from “Table 9.1. Nuclear Generating Units, 1955–2007,” in Annual Energy Review 2007, U.S. Department of Energy, Energy Information
Administration, Office of Energy Markets and End Use, June 2008, http://www.eia.doe.gov/aer/pdf/aer.pdf (accessed June 28, 2008). Non-U.S. governmental
data from the Nuclear Energy Institute Historical Profile of U.S. Nuclear Power Development, 1988, and various utility, Federal, and contractor officials.
Original licensing regulations (10 CFR Part 50)a Current licensing regulations (10 CFR Part 52)a
Year Construction permits issuedb, c Low-power operating licenses issuedc, d Full-power operating licenses issuedc, e Early site permits issuedc Combined license applications under review Combined licenses issuedc Permanent shutdownsf Operable unitsg
195510000
195630000
195711101
195800001
195931102
196071103
196100003
196217609
1963132011
1964323113
1965100013
1966512114
19671433215
19682300213
1969744017
19701043020
1971452022
1972866127
1973141215042
1974231415255
1975932057
1976977163
19771544067
19781334170
1979200169
1980052071
1981034075
1982064178
1983033081
1984076087
1985079096
19860750101
19870682107
19880120109
19890342111
19900121112
19910001111
19920002109
19930110110
19940001109
19950100109
19960011109
19970000002107
19980000003104
1999–20060000000104
20070003400104
Total 177 132 132 3 4 0 28
aData in columns 1–3 are based on the U.S. Nuclear Regulatory Commission (NRC) regulation 10 CFR Part 50. Data in columns 4–6 are based on the NRC regulation 10 CFR Part 52.
bIssuance by regulatory authority of a permit, or equivalent permission, to begin construction.
cNumbers reflect permits or licenses issued in a given year, not extant permits or licenses.
dIssuance by regulatory authority of license, or equivalent permission, to conduct testing but not to operate at full power.
eIssuance by regulatory authority of full-power operating license, or equivalent permission (note that some units receive full-power licenses the same year they receive low-power licenses). Units initially undergo low-power testing prior to commercial operation.
fNumber of nuclear generating units, in a given year, ceasing operation permanently.
gTotal of nuclear generating units holding full-power licenses, or equivalent permission to operate, at the end of the year (the number of operable units equals the cumulative number of units holding full-power licenses minus the cumulative number of permanent shutdowns).
— = Not applicable.
Web page: For related information, see http://www.eia.doe.gov/fuelnuclear.html.

in average capacity factor. The capacity factor is the proportion of electricity produced to what could have been produced at full-power operation. The EIA reveals that in 2007 the average capacity factor for U.S. nuclear power plants was 92%, an all-time high. Better training for operators, longer operating cycles between refueling, and control-system improvements contributed to increased plant performance.

Outlook for Domestic Nuclear Energy

In Annual Energy Outlook 2008 (2008, http://www.eia.doe.gov/oiaf/aeo/pdf/0383(2008).pdf), the EIA predicts that the capacity of nuclear power plants will increase from 100.2 gigawatts in 2006 to 114.9 gigawatts in 2030. About 17 gigawatts of capacity will come from new plants and 2.7 gigawatts from power uprates (an increase in the power output of a nuclear power plant accomplished by adding a more highly enriched uranium fuel to the existing fuel). The plant must be able to operate safely at the higher power level. These increases will be partially offset by 4.5 gigawatts of retirements. A power uprate is accomplished by adding a more highly enriched uranium fuel to the existing fuel. The plant must be able to operate safely at the higher power level.

Electricity generation from nuclear power plants is predicted to grow from 787 billion kWh in 2006 to 917 billion kWh in 2030. The share that nuclear power contributes to electricity generation in the United States is expected to decrease slightly from 19% in 2007 to 18% in 2030.

International Production

At 2.6 trillion kWh, nuclear power provided about 15% of the total 17.3 trillion kWh of electricity produced in the world during 2005. (See Table 5.2.) The U.S. Nuclear Regulatory Commission (NRC) indicates in 2007–2008 Information Digest (2007, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1350/v19/sr1350v19.pdf) that as of December 31, 2006, electricity was being produced by 439 nuclear plants worldwide. Fifty-two other plants were under construction or on order.

In 2005 the United States led the world in nuclear power electricity generation with 782 billion kWh, followed by France (429 billion kWh) and Japan (278.4 billion kWh). (See Table 5.2.) Together, the three countries generated 57% of the world’s nuclear electric power. About 80% of France’s electrical power was produced by nuclear energy in 2005, followed by Belgium (56%), Sweden (45%), and Switzerland (38%). Japan produced 27% of its electricity by nuclear power generation in 2005, and the United States, 19%. Canada produced 14% of its electricity with nuclear power; the primary source for electricity generation in Canada is hydroelectric power.

Worldwide, the EIA projects in International Energy Outlook 2008 (June 2008, http://www.eia.doe.gov/oiaf/ieo/) that nuclear generating capacity will increase slightly from 374 gigawatts in 2005 to 498 gigawatts in 2030. Some countries whose capacities are projected to increase are:

  • Canada, from 13 gigawatts in 2005 to 18 gigawatts in 2030
  • Japan, from 47 gigawatts in 2005 to 58 gigawatts by 2030
  • China, from 7 gigawatts in 2005 to 52 gigawatts by 2030
  • India, from 3 gigawatts in 2005 to 20 gigawatts by 2030
  • United States, from 100 gigawatts in 2005 to 116 gigawatts in 2025, and then drop to 115 gigawatts by 2030

Aging Nuclear Power Plants

At some point, the nuclear plants now operating worldwide may need to be retired. Most of them were designed to last about thirty years. Some plants showed serious levels of deterioration after as few as fifteen years; some have lasted well beyond their thirty-year expectations.

There are three methods of retiring, or decommissioning, a reactor. Safe enclosure, or mothballing, involves removing the fuel from the plant, monitoring any radioactive contamination (which is usually very low or nonexistent), and guarding the structure to prevent anyone from entering until eventual dismantling and decontamination activities occur. Entombment, which was used at Chernobyl, involves permanently encasing the structure in a long-lived material such as concrete. This procedure allows the radioactive material to remain safely on-site. Immediate dismantling involves decontaminating and tearing down the facility within a few months or years. This method is initially more expensive than the other options but removes the long-term costs of

TABLE 5.2 World net electric power generation by type, 1980, 1990, and 2005
[Billion kilowatthours]
Fossil fuels Nuclear electric power Hydroelectric powera Totalb
Region and country 1980 1990 2005P 1980 1990 2005P 1980 1990 2005P 1980 1990 2005P
North America 1,880.1 2,292.0 3,238.4 287.0 648.9 879.7 546.9 606.5 651.1 2,721.6 3,624.0 4,888.4
Canada79.8101.9152.235.969.287.4251293.9359.9367.9468.7609.6
Mexico46.085.7175.2.02.810.316.723.227.563.6116.6222.4
United States1,753.82,103.82,910.0251.1576.9782.0279.2289.4263.82,289.63,038.04,055.4
Other.5.71.0.0.0.0.0.0.0.5.71.0
Central and South America 99.8 114.8 253.3 2.2 9.0 16.3 201.5 365.1 613.2 308.2 497.2 908.7
Argentina22.220.959.52.27.06.417.320.233.941.848.3101.1
Brazil7.58.134.1.01.99.9128.4204.6334.1138.3219.6396.4
Paraguay(s)(s)(s).0.0.0.727.250.7.827.250.7
Venezuela17.621.024.9.0.0.014.436.674.332.057.699.2
Other52.464.8134.9.0.0.040.676.4120.295.3144.4261.4
Europec R1,453.3 R1,441.0 1,837.7 229.6 761.3 957.3 458.0 474.5 539.6 R2,154.7 R2,696.4 3,494.7
Belgium38.325.033.011.940.645.2.3.3.350.866.580.8
Czech Republic50.823.52.477.4
Finland22.022.822.06.618.322.110.110.813.638.751.867.1
France118.044.357.263.4298.4429.068.352.851.2250.8397.6543.6
Germany390.3358.9362.355.6145.1154.918.817.219.4469.9526.0579.4
Italy125.5167.5231.12.1.0.045.031.333.3176.4202.1278.5
Netherlands58.063.281.83.93.33.8.0.1.162.967.794.3
Norway.1.2.5.0.0.082.7119.9134.482.9120.4135.8
Poland111.1125.0142.1.0.0.02.31.42.2113.8126.7146.2
Romania51.449.731.6.0.05.312.510.920.063.960.656.9
Spain74.566.5173.15.251.654.729.225.219.4109.2143.9270.3
Sweden10.13.23.725.364.868.658.171.872.194.3141.5153.2
Switzerland.9.61.012.922.422.232.529.530.946.453.056.1
Turkey12.032.3114.8.0.0.011.222.939.223.355.2154.2
United Kingdom228.9230.0277.532.362.575.23.95.14.9265.1299.0372.6
OtherR212.1R251.6255.310.354.452.983.275.496.3R306.3R384.3428.2
Eurasiad 1,037.1 1,204.1 843.6 72.9 201.3 235.8 184.0 230.7 244.7 1,294.0 1,636.1 1,327.3
Kazakhstan56.5.07.864.2
Russia588.4140.2172.9904.4
Ukraine79.783.312.4175.4
Other1,037.11,204.1119.172.9201.312.3184.0230.751.71,294.01,636.1183.3
Middle East R81.8 R215.5 581.7 .0 .0 .0 9.6 9.6 21.0 R 91.4 R 225.1 602.7
Iran15.749.8154.4.0.0.05.66.015.921.355.9170.4
Saudi Arabia20.564.9165.6.0.0.0.0.0.020.564.9165.6
OtherR45.7R100.7261.7.0.0.04.13.65.0R 49.7R 104.3266.7
Africa 128.8 243.6 430.3 .0 8.4 12.2 60.1 54.9 88.7 188.9 307.3 533.2
Egypt8.631.589.8.0.0.09.79.912.118.341.4102.5
South Africa92.1146.6214.9.08.412.21.01.0.993.1156.0228.3
Other28.265.5125.7.0.0.049.444.075.677.6109.9202.4

monitoring both the structure and the radiation levels. It also frees the site for other uses, including the construction of another nuclear power plant. Nuclear power companies are also seeking alternative uses for nuclear shells, including the conversion of old nuclear plants to gas-fired plants.

Paying for the closing, decontamination, or dismantling of nuclear plants has become an issue of intense public debate. The industry contends that the cost of decommissioning retired plants and handling radioactive wastes will continue to escalate, causing serious financial problems for electric utilities.

A New Generation of Nuclear Plants

In 2001 the Generation IV International Forum (July 14, 2005, http://gif.inel.gov/roadmap/), a group of nuclear nations, agreed to work together to create a new generation of nuclear reactors. Their intent was to develop new systems by 2030 that “present significant improvements in economics, safety and reliability and sustainability over currently operating reactor technologies.” As of September 2008, its members included Argentina, Brazil, Canada, the European Atomic Energy Community, France, Japan, the Republic of Korea, the Republic of South Africa, Switzerland, the United Kingdom, and the United States.

The group chose six nuclear power technologies for development:

  • Gas-cooled fast reactor —this technology would provide a closed system, helium-cooled reactor that minimizes long-lived radioactive waste by recycling it.
  • Very-high-temperature reactor (VHTR) — with core outlet temperatures reaching 1,832° Fahrenheit (1,000° C),
    TABLE 5.2 World net electric power generation by type, 1980, 1990, and 2005 [CONTINUED]
    SOURCE: “Table 11.16. World Net Generation of Electricity by Type, 1980, 1990, and 2005 (Billion Kilowatthours),” in Annual Energy Review 2007, U.S.
    Department of Energy, Energy Information Administration, Office of Energy Markets and End Use, June 2008, http://www.eia.doe.gov/aer/pdf/aer.pdf
    (accessed June 28, 2008)
    [Billion kilowatthours]
    Fossil fuels Nuclear electric power Hydroelectric powera Totalb
    Region and country 1980 1990 2005P 1980 1990 2005P 1980 1990 2005P 1980 1990 2005P
    Asia and Oceaniac 907.7 1,626.8 4,270.2 92.7 279.9 524.3 262.7 404.1 735.3 1,268.0 2,333.0 5,589.1
    Australia74.5131.8218.4.0.0.012.814.015.587.7146.4236.7
    China227.9465.21,922.1.0.050.357.6125.1397.0285.5590.32,371.8
    India69.7198.9539.23.05.615.746.570.999.0119.3275.5661.6
    Indonesia10.635.3103.4.0.0.02.26.710.712.843.0120.3
    Japan381.6524.0645.578.6192.2278.487.888.477.4549.1817.31,024.6
    South Korea29.845.5222.73.350.2139.41.54.63.634.6100.4366.2
    Taiwan31.343.6164.57.831.638.02.98.27.842.083.3210.3
    Thailand12.338.7115.7.0.0.01.34.95.713.643.7124.6
    Other70.1143.8338.6(s).42.450.081.2118.5123.5233.2472.9
    World 5,588.5 7,137.9 11,455.3 684.4 1,908.8 2,625.6 1,722.9 2,145.4 2,893.5 8,026.9 R11,319.2 17,344.0
    aExcludes pumped storage, except for the United States.
    bWood, waste, geothermal, solar, wind, batteries, chemicals, hydrogen, pitch, purchased steam, sulfur, and miscellaneous technologies are included in total.
    cExcludes countries that were part of the former U.S.S.R.
    dIncludes only countries that were part of the former U.S.S.R.
    P = Preliminary.
    — = Not applicable.
    (s) = Less than 0.05 billion kilowatthours.
    Note: Totals may not equal sum of components due to independent rounding.
    web page: For related information, see http://www.eia.doe.gov/international.
    the VHTR would be used to produce hydrogen and to meet specific high-temperature heating needs of the petrochemical industry and others.
  • Supercritical-water-cooled reactor (SCWR) —the SCWR is a high-temperature, high-pressure water-cooled reactor that increases efficiency by operating above the thermodynamic critical point of water. Water under high pressure does not boil and turn to steam; the thermodynamic critical point of water refers to the temperature and pressure at which the liquid state ceases to exist and the liquid and gaseous forms become indistinguishable. For water, this point is 705° Fahrenheit (374 ° C).
  • Sodium-cooled fast reactor (SFR) —intended for electricity generation, this system uses a sodium-cooled reactor and a closed fuel cycle to increase safety and reduce high-level radioactive waste.
  • Lead-cooled fast reactor (LFR) —designed with small electricity grids and developing countries in mind, the LFR proposes a factory-built system that would need refueling only every fifteen to twenty years. It features a fast-spectrum lead or liquid metal-cooled reactor and a closed cycle for reducing waste.
  • Molten salt reactor —in this system, the fuel is a liquid mixture of sodium, zirconium, and uranium fluorides, which eliminates the need for fuel production. By-products can be recycled back into the fuel mixture.

Each of the new technologies builds on the knowledge gained during the three other periods of nuclear reactor development: Generation I—the experimental reactors developed in the 1950s and 1960s; Generation II—large, central-station nuclear power reactors, such as the 104 plants still operating in the United States, built in the 1970s and 1980s; and Generation III—the advanced light-water reactors built in the 1990s, primarily in East Asia, to meet that region’s expanding electricity needs.

Nuclear Safety

Safety has been an issue from the beginning of the industry. For example, some plant sites, especially those near earthquake fault lines, have raised serious questions for governments, industry leaders, and environmentalists. Plants can be shut down for a variety of reasons. For example, in 1987 the NRC shut down the Peach Bottom nuclear plant in Delta, Pennsylvania, because control room operators were found sleeping on duty. The plant was not restarted until 1989, after reactor operators had been retrained and changes in management had occurred. In addition, many workers resigned, retired, or were demoted—a few were even fired. The plant, as well as some of the workers, was fined by the NRC. In February 2005 the Kewaunee Power Station in Carlton, Wisconsin, was shut down after it was discovered that emergency shutdown systems could be compromised by flooding from water storage tanks located in an adjacent part of the plant. Even though no flood actually occurred, operations at the plant were halted until the shutdown systems could be protected from a potential water threat. In November 2007 the Perry Nuclear Power Plant near Cleveland, Ohio, automatically shut down when the system that supplies coolant water to the reactor malfunctioned. Nuclear plants shut down from time to time, but most safety questions have been focused by major accidents since the late 1970s.

Three Mile Island

On March 28, 1979, the Three Mile Island nuclear facility near Harrisburg, Pennsylvania, was the site of the worst nuclear accident in U.S. history. Information released several years after the accident revealed that Unit 2, one of the reactors operating at the site, came much closer to meltdown than either the NRC or the industry had previously indicated. Temperatures inside the reactor, which were first said to have reached 3,500° Fahrenheit (1,927° C), are now known to have reached at least 4,800° Fahrenheit (2,649° C). The temperature needed to melt uranium dioxide fuel is 5,080° Fahrenheit (2,804° C). When meltdown occurs, an uncontrolled explosion may result, unlike the controlled nuclear reaction of normal operation.

The emergency system at Three Mile Island was designed to dump water on the hot core of the reactor and spray water into the reactor building to stop the production of steam. During the accident, however, the valves leading to the emergency water pumps closed. Another valve was stuck in the open position, drawing water away from the core, which then became partially uncovered and began to melt.

The accident resulted in no deaths or injuries to plant workers or the nearby community. On average, area residents were exposed to less radiation than that of a chest X-ray. Nevertheless, the incident raised concerns about nuclear safety, which resulted in more rigorous safety standards in the nuclear power industry and at the NRC. Antinuclear sentiment was fueled as well, heightening Americans’ wariness of nuclear power as an energy source.

The nuclear reactor in Unit 2 at Three Mile Island has been in monitored storage since it underwent cleanup. Operation of the reactor in Unit 1 resumed in 1985.

Chernobyl

On April 26, 1986, the most serious nuclear accident ever occurred at Chernobyl, a nuclear plant in what is now Ukraine (then part of the Soviet Union). At least thirty-one people died and hundreds were injured when one of the four reactors exploded during a badly run test. Millions of people were exposed to some levels of radiation when radioactive particles were released into the atmosphere. About 350,000 people were eventually evacuated from the area, including residents of what are now the neighboring nations of Belarus and the Russian Federation, who were endangered by fallout carried by the prevailing winds.

The cleanup was a huge project. Helicopters dropped tons of limestone, sand, clay, lead, and boron on the smoldering reactor to stop the radiation leakage and reduce the heat. Workers built a giant steel and cement sarcophagus to entomb the remains of the reactor and contain the radioactive waste.

The International Atomic Energy Agency (IAEA) indicates in Chernobyl’s Legacy: Health, Environmental, and Socioeconomic Impacts (April 2006, http://www.iaea.org/Publications/Booklets/Chernobyl/chernobyl.pdf) that about one thousand people involved in the initial cleanup, including emergency workers and the military, received high doses of radiation. Eventually, over six hundred thousand people would be involved in decontamination and containment activities. The long-term effects of whatever exposure they received are being monitored. According to the IAEA, the most measurable effect of the radiation has been the incidence of thyroid cancer in children. At least four thousand children—which is considered a very large number, given the size of the population—have been treated for the cancer.

Even though some of the evacuated land has been declared fit for habitation again, several areas that received heavy concentrations of radiation are expected to be closed for decades. The three remaining nuclear reactors at Chernobyl continue to operate. The site itself is off-limits to all but official personnel.

An International Agreement on Safety

In September 1994 forty nations, including the United States, signed the International Convention on Nuclear Safety, an agreement that requires them to shut down nuclear power plants if necessary safety measures cannot be guaranteed. In “Summary Report of the 4th Review Meeting of the Contracting Parties to the Convention on Nuclear Safety” (June 2008, http://www-ns.iaea.org/downloads/ni/safety_convention/summary-report-april2008-final.pdf), the IAEA states that as of April 14, 2008, sixty countries and one regional organization had ratified the agreement. The agreement applies to land-based civil nuclear power plants and seeks to avert accidents such as the 1986 explosion at Chernobyl. Ukraine, which inherited the Chernobyl plant after the collapse of the Soviet Union, signed the agreement. Signers must submit reports on atomic installations and, if necessary, make improvements to upgrade safety at the sites. Neighboring countries may call for an urgent study if they are concerned about a reactor’s safety and the potential fallout that could affect their own population or crops.

Radioactive Waste

Working in a laboratory in Chicago, Illinois, in 1942, the physicist Enrico Fermi (1901–1954) assembled enough uranium to cause a nuclear fission reaction. His discovery transformed both warfare and energy production. The experiment also produced a small packet of radioactive waste material that may remain dangerous for one hundred thousand years. That first radioactive waste lies buried under a foot of concrete and two feet of dirt on a hillside in Illinois.

Radioactive waste is produced at all stages of the nuclear fuel cycle, from the initial mining of the uranium to the final disposal of the spent fuel from the reactor. The term radioactive waste encompasses a broad range of material with widely varying characteristics. Some is barely radioactive and safe to handle, whereas other types are intensely hot and highly radioactive. Some waste decays to safe levels of radioactivity in a matter of days or weeks, whereas other types will remain dangerous for thousands of years. The U.S. Department of Energy and the NRC have defined the major types of radioactive waste.

Uranium Mill Tailings

Uranium mill tailings are sandlike wastes produced in uranium refining operations. Even though they emit low levels of radiation, their large volume (10 million to 15 million short tons [9.1 million to 13.6 million t] annually) poses a hazard, particularly from radon emissions and groundwater contamination. The dangers of uranium mill tailings were not realized until the early 1970s, so many miners and residents of the western United States were exposed to them. Cancer incidences are high among miners who worked before the 1970s. In addition, the World Information Source on Energy Uranium Project reports in “Health Impacts for Uranium Mine and Mill Residents— Science Issues” (April 9, 2008, http://www.wise-uranium.org/uhr.html) that those residing near uranium mills have shown increased risks of leukemia, lung and renal cancer, and birth defects.

Low-Level Waste

Low-level waste, which contains lesser levels of radioactivity, includes trash (such as wiping rags, swabs, and syringes), contaminated clothing (such as shoe covers and protective gloves), and hardware (such as luminous dials, filters, and tools). This waste comes from nuclear reactors, industrial users, government users (but not nuclear weapons sites), research universities, and medical facilities. In general, low-level waste decays relatively quickly (in ten to one hundred years).

High-Level Waste

Spent nuclear fuel (used reactor fuel) is high-level radioactive waste. Uranium fuel can be used for twelve to eighteen months, after which it is no longer as efficient in splitting its atoms and producing the heat needed to generate electricity. It must be removed from the reactor and replaced with fresh fuel. Some of the spent fuel is reprocessed to recover the usable uranium and plutonium, but the radioactive material that remains is dangerous for thousands of years.

Transuranic Wastes

Transuranic wastes are eleven man-made radioactive elements with atomic numbers greater than that of uranium (ninety-two) and therefore beyond (trans-) uranium (-uranic) on the Periodic Table of the elements. Their half-lives (the time it takes for half the radioisotopes present in a sample to decay to nonradioactive elements) are thousands of years. They are found in trash produced mainly by nuclear weapons plants and are therefore part of the nuclear waste problem but not directly the concern of nuclear power utilities.

Mixed Waste

Mixed waste is high-level, low-level, or transuranic waste that also contains hazardous nonradioactive waste. Such waste poses serious institutional problems, because the radioactive portion is regulated by the Department of Energy or the NRC under the Atomic Energy Act of 1954, whereas the U.S. Environmental Protection Agency (EPA) regulates the nonradioactive elements under the Resource Conservation and Recovery Act of 1976.

Radioactive Waste Disposal

Disposing of radioactive waste is unquestionably one of the major problems associated with the development of nuclear power; radioactive waste is also a by-product of nuclear weapons plants, hospitals, and scientific research. Even though federal policy is based on the assumption that radioactive waste can be disposed of safely, new storage and disposal facilities for all types of radioactive waste have frequently been delayed or blocked by concerns about safety, health, and the environment.

The highly toxic wastes must be isolated from the environment until the radioactivity decays to a safe level. In the case of plutonium, for example, the half-life is twenty-six thousand years. At that rate, it will take at least one hundred thousand years before radioactive plutonium is no longer dangerous. Any facilities built to store such materials must last at least that long.

Regulation of Radioactive Waste Disposal

As of January 2006 the NRC had entered into agreements with thirty-three states to regulate the management, storage, and disposal of certain nuclear waste within their borders.

Disposal of Uranium Mill Tailings

Mill tailings are usually deposited in large piles next to the mill that processed the ore. In 1978 Congress passed the Uranium Mill Tailing Radiation Control Act, which requires mill owners to follow EPA standards for the cleanup of uranium and thorium after milling operations have permanently closed. The companies must cover the mill tailings to control the release of radon gas for one thousand years.

Disposal of Low-Level Waste

According to the NRC, in 2007–2008 Information Digest, as of June 2007 three low-level licensed nuclear waste facilities were operating in the United States: in Barnwell, South Carolina; in Hanford, Washington; and in Clive, Utah, where Energy Solutions accepts large amounts of mill tailings and low-level waste, such as contaminated soil or debris from demolished buildings. Four low-level radioactive waste facilities have been closed: in West Valley, New York (closed 1975); in Maxey Flats, Kentucky (closed 1977); in Sheffield, Illinois (closed 1978); and in Beatty, Nevada (closed 1993).

The design of a low-level waste facility is shown in Figure 5.8. Wastes are buried in shallow underground

TABLE 5.3 Low-level waste compacts, June 2007
SOURCE: “Table 15. U.S. Low-Level Waste Compacts,” in Information Digest 2007–2008, vol. 19, U.S. Nuclear Regulatory Commission, Division of Planning, Budget, and Analysis, Office of the Chief Financial Officer, August 2007, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1350/v19/sr1350v19.pdf (accessed July 3, 2008)
Appalachian Rocky Mountain
DelawareColorado
MarylandNevada
PennsylvaniaNew Mexico
West Virginia
Southeast
Atlantic Alabama
New JerseyFlorida
South Carolina*Georgia
Mississippi
Central Tennessee
ArkansasVirginia
Kansas
LouisianaSouthwestern
NebraskaArizona
OklahomaCalifornia
North Dakota
Central Midwest South Dakota
Illinois
KentuckyTexas
Texas
Midwest Vermont
Indiana
IowaUnaffiliated
MinnesotaMaine
MissouriMassachusetts
OhioMichigan
WisconsinNew Hampshire
New York
Northwest North Carolina
AlaskaRhode Island
Hawaii
Idaho
Montana
Oregon
Utah*
Washington*
Wyoming
*There are three active, licensed low-level waste disposal facilities located in agreement states.
Barnwell, located in Barnwell, South Carolina: Currently, Barnwell accepts waste from all U.S. generators. Beginning in 2008, Barnwell will only accept waste from the Atlantic Compact States (Connecticut, New Jersey, and South Carolina). Barnwell is licensed by the state of South Carolina to receive waste for classes A-C waste.
Energy Solutions, located in Clive, Utah: Energy Solutions accepts waste from all regions of the United States. It is licensed by the state of Utah for class A waste only.
Hanford, located in Hanford, Washington: Hanford accepts waste from the Northwest and Rocky Mountain compacts. Hanford is licensed by the state of Washington to receive waste for classes A-C waste.

sites in specially designed canisters. Underground storage may or may not include protection by concrete vaults.

The Low-Level Radioactive Waste Policy Amendments Act of 1985 encouraged states to enter into compacts, which are legal agreements among states for low-level radioactive waste disposal. Table 5.3 shows these compacts. Even though each compact is responsible for the development of disposal capacity for the low-level waste generated within the compact, new disposal sites have yet to be built. As Table 5.3 shows, two of the three operational low-level sites are located in the Northwest Compact and one is in the Atlantic Compact. Nuclear power facilities located in compacts without low-level waste disposal sites must petition the compact to export their low-level radioactive waste to one of the three operating disposal sites.

Disposal of High-Level Waste

A major step toward shifting the responsibility for disposal of high-level radioactive wastes (spent fuel) from the nuclear power industry to the federal government was taken in 1982, when Congress passed the Nuclear Waste Policy Act. It established national policy, set a detailed timetable for the disposal and management of high-level nuclear waste, and authorized construction of the first high-level nuclear waste repository. A 1987 amendment to the Nuclear Waste Policy Act directed investigation of Yucca Mountain, about 100 miles (161 km) northwest of Las Vegas, Nevada, as a potential site.

The project was highly controversial, however, and Congress did not approve the Yucca Mountain site until July 2002. The state of Nevada challenged the decision, but in 2004 federal courts dismissed the challenge. In April 2006 the U.S. secretary of energy announced proposals to facilitate licensing and construction of the repository, which was expected to take about five years. In June 2008 the Department of Energy submitted a waste repository license application to the NRC—more than a decade after the repository was originally scheduled to open. Thus, by mid-2008, no long-term, permanent disposal repository for high-level waste existed, and construction of the Yucca Mountain Repository had not yet begun.

While waiting for the development of the Yucca Mountain site, as of September 2008 spent fuel was being stored at facilities away from the power plants that generated the waste, such as at the General Electric Company facility in Morris, Illinois. Alternately, spent fuel was being stored at the nuclear power plants that generated the waste. The map in Figure 5.9 notes the sites storing spent nuclear fuel and high-level radioactive waste as of June 2008.

Figure 5.10 shows the plan for the proposed Yucca Mountain high-level nuclear waste repository. Aboveground structures for handling and packaging nuclear waste would cover approximately 400 acres (162 hectares) and be surrounded by a 3-mile (4.8-km) buffer zone. Underground, about 1,400 acres (567 hectares) would be mined, with tunnels leading to areas where sealed metal containers would be placed. This type of deep geologic disposal is widely considered by governments, scientists, and engineers to be the best option for isolating highly radioactive waste.

The repository would be designed to contain radioactive material by using layers of man-made and natural barriers. Regulations require that a repository isolate waste until the radiation decays to a level that is about the same as that from a natural underground uranium deposit. This decay time was originally estimated to be about ten thousand years, but the National Academy of Sciences has more recently recommended a higher standard of about three hundred thousand years.

After the repository has been filled to capacity, regulations require the Department of Energy to keep the facility open and to monitor it for at least fifty years from the fill date. Eventually, the repository shafts would be filled with rock and earth and sealed. At ground level, facilities would be removed and, as much as possible, the site returned to its original condition.

Scientists expect some of the man-made barriers in a repository to break down over thousands of years. Once that happens, natural barriers will be counted on to stop or slow the movement of radiation particles. The most likely way for particles to reach humans and the environment would be through water, which is why the low water tables at Yucca Mountain are so crucial. In addition, Yucca Mountain contains minerals called zeolites that will stick to the particles and slow their movement throughout the environment.

The long delay in providing disposal sites for spent nuclear fuel has been expensive for the industry. Several aging power plants are being maintained at a cost of $20 million per reactor per year simply because there is no place to send the waste once the plants are decommissioned. As of 2002, 47,023.4 metric tons (51,834.4 short tons) of nuclear uranium waste were sitting in spent fuel pools at the 104 operating and 28 permanently closed nuclear power plants. (See Table 5.4 and Table 5.1.)

Disposal of Transuranic Waste

The Waste Isolation Pilot Plant (WIPP) is the first disposal facility licensed to dispose of transuranic waste. It does not accept waste from commercial sources or electrical power plants, but disposes only of defense-related transuranic waste. It opened in March 1999 in southeastern New Mexico. Its disposal rooms were mined 2,150 feet (655 m) underground in a salt formation that is 2,000 feet (610 m) thick and that has been stable for over 200 million years. Beginning with one or two shipments per week, operations grew over the years, expanding to an all-time high of thirty-three shipments received during a single week in February 2006. In September 2006 the plant received its five-thousandth shipment of transuranic waste and announced that thirteen sites around the country, most notably the Rocky Flats Environmental Technology site in Colorado, had been completely cleaned up by that time. As of August 25, 2008, WIPP (http://www.wipp.energy.gov/shipments.htm) had received 6,851 shipments from eight sites.

Disposal of Mixed Waste

Several commercial facilities in the United States accept mixed waste. However, only the Energy Solutions facility in Clive, Utah, is permitted to accept solid mixed waste. It stores the waste in aboveground, capped embankments designed to last at least one thousand years. The storage facility is located in an isolated area 20 miles (32 km) from the nearest water supply and more than 40 miles (64 km) from the nearest populated area. Containment efforts are supported by area soil and weather conditions, as well, with little permeability (the capacity of rock or soil to transmit water) in the clay soil and fewer than 6 inches (15 cm) of rain per year.

Sites in Florida, Tennessee, and Texas offer storage for liquid or sludge materials or use thermal or chemical processes to neutralize them. Among them, Diversified Scientific Services in Kingston, Tennessee, generates electrical power from liquid mixed waste through an industrial boiler system, and the Texas-based NSSI provides drum storage.

TABLE 5.4 Total commercial spent nuclear fuel discharges, 1968–2002
SOURCE: “Table 1. Total U.S. Commercial Spent Nuclear Fuel Discharges, 1968–2002,” in Spent Nuclear Fuel, U.S. Department of Energy, Energy Information Administration, October 1, 2004, http://www.eia.doe.gov/cneaf/nuclear/spent_fuel/ussnfdata.html (accessed July 3, 2008)
Number of assemblies
Reactor type Stored at reactor sites Stored at away-from-reactor facilities Total
Boiling-water reactor90,3982,95793,355
Pressurized-water reactor69,80049170,291
High-temperature gas cooled reactor1,4647442,208
Total 161,662 4,192 165,854
Metric tonnes of uranium (MTU)
Boiling-water reactor16,153.6055416,707.60
Pressurized-water reactor30,099.00192.630,291.60
High-temperature gas cooled reactor15.48.824.2
Total 46,268.00 755.4 47,023.40
Notes: A number of assemblies discharged prior to 1972, which were reprocessed, are not included in this table (no data is available for assemblies reprocessed before 1972). Totals may not equal sum of components because of independent rounding.

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Nuclear Energy

Nuclear Energy

Nuclear power, an important source of electricity, can be obtained by two types of nuclear reaction: nuclear fission, the splitting of the nuclei of atoms; and nuclear fusion, the uniting of the nuclei of atoms. Both types of nuclear reactions release huge amounts of energy. Nuclear power plants are able to produce energy by splitting uranium or plutonium atoms in controlled fission reactions, using a device called a nuclear reactor. The heat energy released from the nuclear fission is captured and used to generate electricity. In 2007, there were 435 nuclear power plants in operation worldwide and 37 plants under construction. Nuclear power provided about 17 percent of the world's electricity.

The United States had 104 operating nuclear power plants in 2007, the most of any country in the world. However, public concern over safety issues brought the construction of new nuclear power plants to a virtual halt. Besides the possibility of accidents occurring in nuclear plants, Americans were concerned that other countries might use nuclear power plants, materials, technology, and knowledge to secretly develop nuclear weapons.

U.S. historical background

In 1954, the U.S. government authorized private ownership of nuclear reactors, paving the way for utility companies to build nuclear power plants. There were fears early on, mainly because most Americans’ sole experience of nuclear power had been the devastating atomic bombings of Hiroshima and Nagasaki, Japan, in 1945, near the end of World War II (1939–45), which destroyed the cities, killed an estimated 150,000 people, and injured another 200,000 or more.

By the 1960s, the United States was using increasing amounts of electrical energy produced by burning fossil fuels, such as coal, oil, and natural gas, which created air pollution. Despite safety fears, many people came to support the idea of building nuclear energy plants, which promised to provide cheaper and cleaner energy.

Energy shortage

In 1973 and 1974, countries in the Middle East, the largest supplier of oil to the United States, took part in an oil embargo—a refusal to ship their oil to countries that supported Israel in its conflicts with other nations in the Middle East. The embargo resulted in severe shortages of electricity, gasoline, and heating oil in the United States. Factories and schools shut down, commercial airlines cancelled flights, and long lines at gas stations frustrated drivers. The embargo made it clear that the United States depended too heavily on other countries for its energy.

The energy shortage was made worse by the extravagant quantities of oil the United States was consuming. Few U.S.-made cars got more than 10 miles to the gallon, and homes and businesses were poorly insulated and inefficiently designed, and therefore extremely costly to heat or cool.

Utility companies, foreseeing the coming energy shortage, had prepared by constructing nuclear reactors. By 1973, there were twenty-seven functioning reactors in the United States, providing about 5 percent of the nation's power. More than a hundred more plants were in development, though many of these were never built.

Safety issues

Safety remained a pressing issue with nuclear energy. During the 1970s, fires at several different nuclear reactors underscored the potential for a disastrous accident. In 1975, the Union of Concerned Scientists presented

the White House with a petition signed by two thousand scientists that called for a reduction in the construction of nuclear facilities due to safety issues. Environmental groups challenged the construction of nuclear projects, delaying them and driving up their start-up costs by demanding extensive safety precautions.

In spring 1979 an accident at the Three Mile Island nuclear power plant in Harrisburg, Pennsylvania , resulted in a partial core meltdown. A meltdown in a nuclear reactor is an accident that impedes the cooling of the reactor's core. Without proper cooling, the radioactive fuel (material that gives out harmful radiation) inside the reactor begins to overheat and melt. If it gets hot enough, under certain circumstances the radioactive fuel could escape in liquid form into the environment, causing untold injury to humans and other life forms. Fortunately, no one was injured at Three Mile Island, but the accident terrified the public and placed the future of the nuclear industry in jeopardy.

Chernobyl

On April 26, 1986, one of four nuclear reactors at the Chernobyl Nuclear Power Station in the Ukraine exploded. Engineers there accidentally had started an uncontrolled chain reaction in the reactor's core during an unauthorized test. They also had unlawfully turned off the reactor's emergency systems. The reactor exploded with such force that the roof of the building was completely blown off. Eight tons of radioactive materials were scattered about the region immediately surrounding the plant. Airborne radioactivity from the blast rained down on northern Europe. Fallout contaminating farm produce was measured as far away as Scotland. In the immediate aftermath of the catastrophe, more than thirty people lost their lives. Moreover, an estimated twenty thousand more people would eventually die as a result of their exposure to radiation, which can cause cancer and other serious health problems.

Supporters of nuclear energy argued that the accident had little to do with U.S. nuclear systems. The United States did not use the same kind of technology that had been employed at Chernobyl. Furthermore, the Chernobyl reactor lacked a containment building—a safety component required for all U.S. reactors. Nevertheless, many Americans remained uneasy, noting that operator error and equipment failure were always possible. In the nuclear industry, it seemed, the consequences of a single major mistake could be catastrophic.

Anti-nuke movement

During the 1980s, scores of “anti-nuke” organizations warned of the hazards of nuclear energy and protested plant construction and operation. In Seabrook, New Hampshire , protesters rallied to oppose the building of two nuclear reactors. By 1987, the utility that owned Seabrook was near financial collapse, in part due to the safety precautions that the protesters demanded. Many other nuclear facilities under construction at that time were shut down before they had even opened, largely due to the excessive costs.

Nuclear waste disposal

Another problem the industry faced was the disposal of nuclear waste, the radioactive products of nuclear fission. Some parts of nuclear waste can remain hazardous for thousands of years, so it must be kept well out of contact with any living environment. In 1982, Congress passed the Nuclear Waste Policy Act, which called upon the Department of Energy to find a suitable site to bury radioactive waste. But as the United States proposed disposal sites for the waste in the 1980s, local communities raised an uproar.

Ongoing research brought about many new ways to treat nuclear waste. Before it is stored, much nuclear waste today is put through processes that stabilize it into a form that will not decay for many years. There are nuclear-waste disposal sites throughout the world. Research continues to seek the best ways to dispose of nuclear waste.

Besides safety factors, nuclear waste poses a problem because it can be used to create certain types of nuclear weapons, such as the “dirty bomb.” A dirty bomb is a crude nuclear device created from radioactive nuclear waste material and conventional explosives that can be set off to spread radioactive material in a targeted area. One of the key factors in nuclear waste storage is making sure it is not possible for enemies to raid the storage site for material to build weapons that can be used against the United States or its allies.

Regulating nuclear weapons development

After World War II, the United States and the Soviet Union entered into an arms race, with both sides developing thousands of nuclear weapons. During this arms race, in the early 1950s, President Dwight D. Eisenhower (1890–1969; served 1953–61) decided to try to separate the development of nuclear energy from the development of nuclear weapons. In an address delivered before the United Nations in 1953, he outlined his “Atoms for Peace” proposal to extend the benefits of nuclear technology to all countries in return for their guarantees that such assistance would be used for peaceful purposes only.

In 1957, the United Nations created the International Atomic Energy Agency (IAEA) to accelerate the development of nuclear energy throughout the world. The IAEA helps its member countries acquire the necessary skills and materials to share in the benefits of nuclear power.

One of IAEA's objectives is to ensure that the materials, services, equipment, facilities, and information that the IAEA makes available for nuclear energy plants are not used for military purposes.

The Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which was passed by the United Nations in 1968 and came into force in 1970, greatly aided the task of the IAEA. Under the NPT, states without nuclear weapons agreed to accept IAEA safeguards on all their peaceful nuclear activities. These safeguards include detection of the removal of significant quantities of nuclear material from nuclear energy plants for the possible manufacture of nuclear weapons. To ensure that this does not happen, nuclear plants are required to provide strict accounting and reporting in connection with nuclear materials.

The NPT did not impose this reporting duty on countries that already have nuclear weapons, but the United States voluntarily offered to allow its nuclear facilities to be overseen by the IAEA. Other countries followed suit, and today the IAEA applies its safeguards under voluntary agreements to China, France, Russia, and the United Kingdom as well as the United States.

Secret nuclear programs

Secret nuclear weapons development was discovered in places such as Iraq and North Korea during the 1990s. By mid-1997, the IAEA could provide the international community with early warning about the possible removal of nuclear materials from energy plants for weapons purposes. Still, the organization relies on the international community to force nations to comply.

In the aftermath of the September 11, 2001, terrorist attacks on the United States, the IAEA approved a plan to upgrade worldwide protection against acts of terrorism involving nuclear and other radioactive materials.

In the early 2000s, Iran's ambitious plans to construct nuclear power plants raised concerns in the international community about the country's possible plans to produce nuclear weapons.

The future of nuclear power

In the United States in 2007, the issue of constructing more nuclear power facilities remained at a standstill. Proponents argued that construction of new plants should be undertaken to meet growing electricity demands. Coal-fired plants presently produce most of the world's electricity, but release air pollution and greenhouse gases (gases, such as carbon dioxide, ozone, or water vapor, that contribute to the warming of the Earth's atmosphere by reflecting radiation from the Earth's surface). Nuclear power, its advocates argue, does not release these substances.

Opponents of nuclear power respond that greater reductions in air pollution and greenhouse-gas emissions could be achieved by spending the same money on nonnuclear technologies such as efficiency improvements and renewable energy sources such as solar and wind power. They also argue that a massive increase in the number of nuclear power plants will bring increased risks of nuclear accidents and of introducing nuclear weapons to countries that do not have them yet.

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Nuclear Energy

Nuclear Energy

INTRODUCTION: WHAT IS NUCLEAR ENERGY?

Nuclear energy is energy that can be released from the nucleus of an atom. There are two ways to produce this energy, either by fission or fusion. Fission occurs when the atomic nucleus is split apart. Fusion is the result of combining two or more light nuclei into one heavier nucleus. Most often, when people discuss nuclear power, they are talking about nuclear fission. Power production from fusion is still in its infancy.

Atoms are made up of several parts: protons, neutrons, electrons, and a nucleus. A nucleus is the positively charged center of an atom. Protons are positively charged particles, and neutrons are uncharged particles. Electrons orbit around the nucleus and are negatively charged. Fission can occur in two waysfirst, in some very heavy elements, such as rutherfordium, the nucleus of an atom can split apart into smaller pieces spontaneously. With lighter elements, it is possible to hit the nucleus with a free neutron, which will also cause the nucleus to break apart.

Either way, a significant amount of energy is released when the nucleus splits. The energy released takes two forms: light energy and heat energy. Radioactivity is also produced. Atomic bombs let this energy out all at once, creating an explosion. Nuclear reactors let this energy out slowly in a continuous chain reaction to make electricity. After the nucleus splits, new lighter atoms are formed. More free neutrons are thrown off that can split other atoms, continuing to produce nuclear energy. The first controlled nuclear reaction took place in 1942.

Nuclear fission

Since at least the 1920s, scientists had believed that it might someday be possible to produce energy by splitting atoms. They based this belief on their growing understanding of the physics of the atom. They knew that atoms contain energy, and they believed that by "splitting" the atom, or breaking it apart, they could release that energy. The process would come to be called nuclear fission.

An atom is made up of three kinds of particles: neutrons, protons, and electrons. Two of these particles, neutrons and protons, are found in the nucleus, or center, of an atom. A neutron does not have an electrical charge. It is called a neutron because its electrical charge is neutral. A proton has a positive electrical charge. Circling around the nucleus of an atom in layers are electrons, which have a negative electrical charge. To keep the overall electrical charge neutral, an atom has to have the same number of protons and electrons. Positive and negative electrical charges attract each other. The charges bind the particles of an atom together. When an atom is split, some of this energy is released.

Words to Know

Critical mass
An amount of fissile material needed to produce an ongoing nuclear chain reaction.
Decay
The breakdown of a radioactive substance over time as its atoms spontaneously give off neutrons.
Enrichment
The process of increasing the purity of a radioactive element such as uranium to make it suitable as nuclear fuel.
Fission
Splitting of an atom.
Fusion
The joining of atoms to produce energy.
Meltdown
Term used to refer to the possibility that a nuclear reactor could become so overheated that it would melt into the earth below.
Pile
A mass of radioactive material in a nuclear reactor.

The atoms of different elements have different numbers of particles. Some elements are very simple and light. Hydrogen is the simplest and lightest element because it has only one proton, one electron, and no neutrons. In contrast, the heaviest element in nature is uranium. (Some heavier elements have been artificially produced in laboratories, but these elements do not exist in nature.) Uranium atoms contain ninety-two protons and ninety-two electrons. The number of neutrons can vary, depending on the isotope of uranium under consideration. An isotope is a "species" of an element. It contains a different number of neutrons from other isotopes of the same element. Generally, uranium nuclei contain either 143 or 146 neutrons.

For nuclear energy, uranium is the most important element. Uranium is used as fuel to produce nuclear reactions. It makes a good fuel source because uranium atoms are so big and heavy. They are easier to break apart. These large atoms can be thought of as a house built with playing cards. The house becomes increasingly unstable as cards are added, and is more likely to fall apart the bigger and heavier it gets. In a nuclear power plant, the goal is to create fission from uranium fuel and to be able to speed the reaction up (or slow it down) to control the amount of energy being produced.

HISTORICAL OVERVIEW: NOTABLE DISCOVERIES AND THE PEOPLE WHO MADE THEM

Scientists such as Enrico Fermi (19011954) noticed that the free neutrons in elements such as uranium bombard other uranium atoms. This bombardment causes the other atoms to split and release additional neutrons. These additional neutrons then bombard other atoms. The process continues in a chain reaction, or a reaction that keeps going on its own. A neutron in this way can be thought of as similar to a cue ball on a pool table. The cue ball bombards the cluster of balls at the other end of the table, causing the cluster to break apart. All the balls then bounce around, bumping into one another, causing further collisions, and so on.

Spontaneous Fission

Some elements, including uranium, undergo fission spontaneously, or on their own, as neutrons break away from the atom. These elements are said to be radioactive because they release subatomic particles and energy. This spontaneous fission is generally a very slow process. Scientists use the word decay to refer to the breakdown of a radioactive substance over time as it releases its neutrons.

Fermi had conducted experiments in nuclear fission in 1934 while he was still living in Rome, Italy. He had bombarded uranium with neutrons and discovered that what was left over afterwards were elements that were much lighter than uranium. This led him to believe that the uranium atoms had been split. The mass number of the leftover elements was smaller, so the uranium must have transformed into different elements as it broke down. In 1938 German scientists Otto Hahn (18981968) and Fritz Strassman (19021980) conducted a similar experiment. They discovered that what was left over after bombarding uranium with neutrons

The Periodic Table of the Elements

Elements are the fundamental building blocks of nature. Each box in the Periodic Table of the Elements provides basic information about the size and weight of each element. It arranges the elements from lightest to heaviest. It also arranges them into families that share some important characteristics. Each element has a name and a chemical symbol. In the case of uranium, the symbol is simple, U. The symbols for some elements seem strange. The symbol for lead, for example, is Pb because the symbol is taken from the Latin word for lead, plumbum.

The periodic table also contains each element's atomic number and atomic weight. The atomic number is found in the upper left-hand corner of the element's box. It specifies the number of protons in the element's nucleus. Thus, it is equal to the number of electrons. The atomic number for hydrogen is 1, for uranium, 92.

At the bottom center of each box is the element's atomic weight. Atomic weight is a little more complicated. Basically, it represents the combined total of protons and neutrons in the nucleus, called the mass number. But the atomic weight of uranium is given as 238.02891 rather than just 238. The reason for the digits to the right of the decimal point is that many elements, including uranium, occur in different isotopes.

Uranium, for example, has sixteen different isotopes, though only three are found with any frequency. These isotopes are U234, U235, and U238. (Sometimes scientists write these differently, as 234U and so on or U-234.) While the number of protons and electrons in a given element is always the same, the number of neutrons can vary, producing different isotopes. This accounts for the different atomic weights (234, 235, and 238 for uranium). For uranium and other elements, the odd digits to the right of the decimal point occur because on the Periodic Table scientists provide a weighted average of the different isotopes. Therefore, the number may not be a whole number. As a practical matter, the atomic weight figure can be rounded off to the closest whole number.

was the much lighter element barium. This experiment confirmed that the uranium atoms had split.

Other scientists such as Lise Meitner (18781968) from Austria and Niels Bohr (18851962) from Denmark arrived at similar results. But they also made a startling discovery. When the atomic weights of the by-products of their experiment were added together, something was missing. If every piece of a broken window is swept up and weighed, the total weight of the pieces should be the same as the weight of the original window. Scientists expected that the same principle would apply to atoms. If atoms broke down because of fission, the atomic weight of the new elements formed, when added together, should be the same as the atomic weight of the original uranium. But Meitner and Bohr found that the elements in the reaction lost mass. Some of the mass had changed to energy. In this way they proved the truth of the famous equation from Albert Einstein (18791955), E = mc2. This equation says that energy (E) is equal to mass (m) multiplied by the speed of light (c) squared. Mass, or matter, could be converted into energy.

The Italian Navigator

In December 1942 a message was sent to a number of high officials in the U.S. government. The message was written in code because at the time, the United States was at war and the authorities wanted to keep the contents of the message secret. The message read: "The Italian navigator has just landed in the new world."

The "Italian navigator" was physicist Enrico Fermi. Fermi had left his native Italy for the United States in 1938 because he saw the storm clouds of World War II (19391945) gathering over Europe. "The new world" referred to the successful outcome of an experiment. The experiment was conducted by Fermi and a team of researchers at the University of Chicago. On December 2, 1942, in a squash court under the athletic stadium, Fermi oversaw the world's first controlled nuclear reaction. On that date, humanity did indeed land in a new world, the world of nuclear energy.

None of these experiments produced a chain reaction, or a continuing fissioning of atoms. However, in 1942 Fermi thought of a way to create such a chain reaction. He took 40 tons of uranium, a nuclear "pile," and surrounded it with 385 tons of graphite blocks to contain the uranium. (A "pile" of nuclear materials is not literally a pile. "Pile" refers to a quantity of nuclear materials in a nuclear reactor.) This would provide him with the "critical mass" needed to produce an ongoing atomic reaction.

Fermi's main concern was to make sure that the reaction did not get out of control. A controlled chain reaction produces a flow of energy, but an uncontrolled chain reaction produces an explosion. Fermi needed a way to make sure that he did not blow up Chicago by letting his planned reaction get out of control. The graphite blocks would help, but he also inserted rods made of cadmium, a soft bluish-white element, into the pile. Cadmium absorbs neutrons, so it can keep nuclear fission reactions under control.

Lise Meitner

Lise Meitner's contributions are often overlooked in the history of nuclear power development. As a woman, Meitner was barred from higher education in her native Austria until 1901, when she began studying physics at the University of Vienna. After she completed her doctorate in 1907, she worked with the famous German physicist Max Planck (18581947) and chemist Otto Hahn.

Meitner was born into a Jewish family. Although she had converted to Christianity, she was still driven out of Austria and Germany after the Nazi regime took power. She settled in Stockholm, Sweden, where she continued her work on radioactivity. There she worked with Hahn and Strassman. She and another physicist, Otto Frisch (19041979), actually coined the phrase "nuclear fission."

One of science's worst scandals took place in 1945. That year, Otto Hahn was given the Nobel Prize in Chemistry for the discovery of nuclear fission. The contributions of Lise Meitner were entirely ignored. While such names as Planck, Fermi, Hahn, Einstein, and others were famous in the scientific community, Meitner's name was largely forgotten. Later scientists acknowledged her important role, and in 1966 she was awarded the U.S. Fermi Prize in Physics.

On that December afternoon in 1942, Fermi and his team slowly pulled a few of the cadmium rods out of the pile. Now some of the spontaneously released neutrons in the uranium could bombard other uranium atoms. Each collision produced an average of 2.5 new free neutrons, which in turn bombarded other atoms, releasing 2.5 more free neutrons, and so on. More rods were slowly pulled out, and the pace of the reaction increased. When rods were pushed back in, the reaction slowed as the cadmium soaked up neutrons. Chicago did not blow up, and Fermi had created the world's first nuclear reactor.

From the Manhattan Project to Atoms for Peace

Fermi conducted his successful experiment almost exactly one year after the Japanese attacked the U.S. naval base at Pearl Harbor, Hawaii, on December 7, 1941. This event pulled the United States into World War II. The war had begun in September 1939, when German dictator Adolf Hitler (18891945) ordered his troops to invade Poland. In the years that followed, Germany occupied much of Europe. Meanwhile, the Japanese empire was spreading throughout Asia and the Pacific.

Most of the leading scientists involved in nuclear research were from Germany. U.S. policy makers learned that German scientists were trying to develop an atomic bomb, a bomb whose enormous destructive force would come from an uncontrolled fission reaction. Such a bomb in the hands of Germany could have changed the outcome of the war. Thus, American policy makers developed a plan for the United States to create such a bomb first. This is the reason for the secrecy surrounding the message informing the government that Enrico Fermi's experiment had been successful.

The World's First Nuclear Reactor

Enrico Fermi is credited with building the world's first nuclear reactor. Strictly speaking, this is only partially true. He actually built the first "artificial" nuclear reactor. In 1972 a team of French scientists came across an old mine in West Africa. Inside they found some uranium ore. In this ore they found concentrations of U235 of 0.4 percent. But the concentration of U235 in uranium ore found in nature is always 0.72 percent. By analyzing the trace elements in the ore, the scientists concluded that the amount of U235 was less than normal because a chain reaction had occurred. In other words, a naturally occurring nuclear reactor had developed in the mine. The scientists estimate that the reaction occurred more than two billion years ago over a period lasting about 600,000 to 800,000 years.

The research program to develop the bomb was the Manhattan Project. (The name Manhattan has no particular meaning. The branch of the army that oversaw the project was based in Manhattan, New York.) Beginning in 1943, the nation's top scientists, many of them from top-ranked universities, came to Los Alamos, New Mexico. The brilliant physicist J. Robert Oppenheimer (19041967) directed the research. They worked in shacks and lived in primitive conditions, all the while keeping their work top secret.

Continuing the research of Fermi and others, the scientists succeeded in building an atomic bomb, which they tested in the New Mexico desert on July 16, 1945. By this time, though, Germany had surrendered and the war in Europe was over. The war continued to rage in the Pacific as the United States and its allies fought the determined Japanese empire. During the final months of the war with Japan, both countries lost large numbers of troops in bloody island battles, such as those on the Japanese island of Iwo Jima. The Japanese were defeated, but the nation refused to surrender. To put a quick end to the war, the United States released an atomic bomb over the Japanese city of Hiroshima on August 6, 1945. A similar bomb destroyed Nagasaki three days later. Together, the two bombs immediately killed over one hundred thousand people, and many more would later die as a result of burns and radiation sickness. Faced with such a destructive weapon, the Japanese finally surrendered.

The decision to use the atomic bomb was highly controversial. Many U.S. policy makers urged use of the bomb as a way to save the lives of U.S. (and Japanese) troops, who faced the possibility of a difficult invasion of Japan. Others, including many nuclear scientists, believed that using the bomb would cause too much destruction and death. Many believed that it was just a matter of time before Japan would surrender.

After the Soviet Union developed its own atomic weapons, the world's two superpowers began to stockpile them. They accumulated far more nuclear weapons than would ever be needed to defeat the other side. In the 1950s and beyond, the world lived in fear that a nuclear war would erupt, with devastating consequences. Scientists, though, searched for peaceful ways to use nuclear energy. On December 8, 1953, U.S. president Dwight D. Eisenhower (18901969) addressed the United Nations. In his speech, he outlined the "Atoms for Peace" program. He suggested that atomic development and research be turned over to an international agency and that research be conducted to find peaceful uses for atomic energy. This speech gave a major push to efforts to harness atomic energy for the benefit of humankind rather than as a weapon.

Atomic energy development

Those efforts had already begun in the United States. In 1946 the government created the Atomic Energy Commission. Its job was to oversee the development of nuclear power. One of its first steps was to authorize the development of Experimental Breeder Reactor I in Arco, Idaho. On December 20, 1951, the reactor produced the world's first electricity fueled by nuclear power, lighting four 200-watt light bulbs. On July 17, 1955, Arco, home to one thousand people, became the world's first town to be powered by nuclear energy.

Until this time, nuclear energy had been firmly under the control of the military. The first civilian power plant began operating in Susana, California, on July 12, 1957. The world's first commercial-sized nuclear power plant reached full operating power in 1957 in Shippingport, Pennsylvania. (Most nuclear power plants, for safety reasons, operate at about 70 to 90 percent of their maximum capacity.) Meanwhile, on July 14, 1952, the keel had been laid for the world's first nuclear-powered submarine, the Nautilus. On March 30, 1953, the sub powered up its nuclear generators for the first time.

Nuclear power developed rapidly in the late 1950s and into the 1960s. On October 15, 1959, the Dresden-I Nuclear Power Station came online (that is, began to operate) in Illinois. This was the first nuclear power plant to be built entirely without money from the government. On August 19, 1960, the Yankee Rowe Nuclear Power Station in Massachusetts became the nation's third nuclear power plant. On November 22, 1961, the U.S. Navy commissioned the U.S.S. Enterprise, the world's largest ship. Powered by nuclear energy, the aircraft carrier could operate at speeds up to 30 knots for as far as 400,000 miles (740,800 kilometers) without having to refuel. Another milestone was passed on December 12, 1963, when the Jersey Central Power and Light Company launched construction of the Oyster Creek nuclear power plant. This was the first nuclear plant to be ordered as an economic alternative to a fossil-fuel plant.

By 1971 the United States was operating twenty-two nuclear power plants that provided 2.4 percent of the nation's electricity. By the end of the 1970s, seventy-two plants were producing 12 percent of the nation's electricity. And by the end of the 1980s, 109 power plants were generating 14 percent of the nation's electricity. These numbers peaked in 1991, when the number of plants rose to 111, together supplying about 22 percent of the nation's electricity. By the early 1990s nuclear power plants were generating more power in the United States than all power sources combined generated in 1956.

Similar developments were taking place worldwide. As of late 2005, 441 nuclear reactors were producing 2,618.6 billion kilowatt-hours of electricity in thirty countries. The United States led the way with 103 nuclear reactors still in operation. Other countries with a large number of nuclear reactors included Canada (18), France (59), Germany (17), Japan (55), Russia (31), and the United Kingdom (23). The country that generated the highest percentage of its electricity needs from nuclear power was France, at 78 percent. Close behind was Lithuania, whose one power plant generated 72 percent of the nation's electricity.

Setbacks

In the 1950s and 1960s scientists around the world believed that nuclear power had unlimited potential. Along with most of the public, they believed that nuclear plants would provide an endless source of cheap, renewable, clean energy. Yet by late 2005 only thirty-nine new nuclear power plants had been proposed by the nations of the world, and none were proposed for the United States. The percentage of electricity produced worldwide amounted to just 16 percent. The nuclear energy industry seemed to be stagnating (standing still; not moving forward).

Throughout the 1980s and 1990s and into the new millennium, the public began to have serious doubts about the safety of nuclear power. Those doubts arose because of the industry's first major setback, which took place on March 28, 1979. On that day an accident occurred at the Three Mile Island nuclear power plant near Harrisburg, Pennsylvania. No one was injured or killed, and no one was overexposed to radiation from the plant. Still, the accident shut the plant down. If the accident had not been contained, a meltdown could have occurred. ("Meltdown" refers to an out-of-control reaction that overheats the reactor, causing it potentially to melt into the earth below, releasing radiation into groundwater and the atmosphere.) Many Americans started to distrust nuclear power, believing that the possibility of a catastrophe was too great. Not helping the industry was a major movie that year called The China Syndrome. The movie dramatized events at a fictional California nuclear power plant that were eerily similar to the Three Mile Island accident. Its title referred to the theoretical possibility that an overheated nuclear reactor could melt its way through the Earth to China.

Then in 1986 a major disaster struck. On April 26 an explosion took place in reactor number 4 at the nuclear power plant in Chernobyl, a city in Ukraine (formerly part of the Soviet Union) about 70 miles (112 kilometers) north of Kiev. In this accident, a large amount of radiation was released into the atmosphere. Scientists estimate that the amount of this radiation was 100 to 150 million curies (although this unit is well known scientists now use the Bequerel as the unit of radiation), primarily in the form of radioactive cesium and iodine. Thirty-one people were killed in the accident, including firefighters, and 135,000 people within a 20-mile (32-kilometer) radius had to be permanently evacuated. Several years later, an additional 110,000 people were evacuated. Entire villages had to be decontaminated, and in the years that followed the rates of certain cancers among people in the area were noticeably higher. (Exposure to radiation increases the risk of developing cancer.) Radioactivity spread over large areas of the Soviet Union, into Eastern Europe, and as far away as Scandinavia. It is estimated that the accident cost the Soviet Union $12.8 billion. The human costsstress, lost homes, poor healthcannot be measured.

These accidents burst the nuclear industry's bubble. People began to fear a major accident that would dwarf the kinds of accidents that took place at conventional coal-fired electric-generating stations. On December 16, 2005, the world held its breath when a large explosion damaged a Russian nuclear power plant outside the city of St. Petersburg.

Measuring Radiation

In measuring radiation and radiation exposure, physicists use a number of units of measurement, depending on exactly what they are trying to measure. Complicating matters is that there are "common units" of measurement and so-called "SI units," or "standard units." SI units are those recommended by the worldwide General Conference of Weights and Measures. Some of these units, such as curies (named after French physicists Pierre [18591906] and Marie [18671934] Curie) measure amounts of radiation. Others, such as rems, measure doses of radiation people might receive.

The nuclear industry began to face other problems in the 1980s and beyond. The cost of building nuclear power plants was spiraling out of control. Most new plants went far over budget. Also in the 1980s and 1990s, the first aging nuclear plants had to be shut down and taken out of operation. It was discovered then that the cost of decommissioning (shutting down) a nuclear power plant was high because extreme care had to be taken to dispose of radioactive components properly. On top of these problems, the waste from nuclear power plants was beginning to accumulate, and no one knew quite what to do with it.

Because of these problems, plans for construction of new plants were in many cases canceled. By 2005 the number of operating plants in the United States had declined (to 103) as older plants were decommissioned. Nuclear power had become an emotional issue. Its supporters believe that by the year 2050, the energy needs of the United States will triple. They believe that other forms of alternative energy can help, but only nuclear plants can provide power on a large scale. Opponents of nuclear power, however, believe that the costs and the risks are too high.

HOW NUCLEAR ENERGY WORKS

Generating electricity through nuclear power is an enormously complex technical feat. It takes the combined skills of geologists (scientists who study Earth's structure, especially rocks), mine operators, engineers, and scientists, as well as large numbers of highly trained and skilled plant operators. The federal government oversees the construction and operation of these plants to make sure that they are built and operated to the very highest standards.

Uranium

Producing nuclear power begins with the fuel, uranium. Uranium was discovered in 1789 by a German chemist, Martin Klaproth (17431817). He discovered uranium in a mineral called pitchblende. The element was named after the planet Uranus, which had been discovered just eight years earlier. Scientists' best guess is that uranium was formed in supernovas (or exploding stars) about 6.6 billion years ago. In the Earth, radioactive decay of uranium is the planet's main source of internal heat.

Uranium is used primarily in the nuclear industry, but it has other uses as well. Because it is a dense, heavy element (18.7 times as dense as water), it is sometimes used in the keels of boats as a weight to keep them upright. (Density refers to weight relative to volume. A ton of feathers weighs as much as a ton of lead, but because lead is denser than feathers, it takes up far less volume.) Its density also makes it useful as a counterweight in such applications as airplane rudders, and it makes a good radiation shield.

The uranium atom

Uranium is the heaviest naturally occurring element. It has sixteen different isotopes, although the most common ones are U235 and U238. U234 is found in trace amounts and results from the decay of U238. The more abundant isotope, U238 (which accounts for 99.3 percent of the uranium in the Earth's crust) plays a role in keeping the Earth warm. Like any radioactive substance, U238 decays, but it decays very slowly. Its half-life is about the same as the age of the Earth, 4.5 billion years. ("Half-life" is a term scientists use to refer to the rate at which a radioactive substance decays, or breaks down. Thus, half of all U238 has broken down over the past 4.5 billion years. Half of the half that is left will break down over the next 4.5 billion years, and so on.) From the standpoint of nuclear energy, the important isotope of uranium is U235.

The nucleus of a U235 atom consists of ninety-two protons and 143 neutrons. This is the isotope of uranium whose atoms can be split relatively easily. When a U235 atom is struck by a neutron, the atom splits, releasing energy. It also releases two or three neutrons of its own, which in turn split other atoms, and on and on in a chain reaction. In a nuclear reactor, the released energy is at first kinetic energy. Kinetic energy is the energy contained in anything (such as water, wind, or a neutron) that is in motion. But submicroscopic particles travel only tiny distances, so the kinetic energy is rapidly converted to heat (similar to the way the brakes on a car get hot when they stop the kinetic energy of a moving car). This heat is then used to produce steam, which turns a generator to produce electricity. Heat makes up about 85 percent of the energy released. Most of the rest of the energy is in the form of gamma rays. (A gamma ray is a photon that is released by a radioactive substance. A photon is a form of energy, like light.)

In many respects, the process as described is much more complex. For example, physicists note that only isotopes with an odd number of particles in the nucleus, like U235, are fissile (able to be split). Further, not every neutron that hits a uranium atom causes fission. Sometimes the neutrons are absorbed by the atoms they strike, so no fission takes place. Other neutrons simply escape and do nothing. Another complication has to do with the speed of the neutrons. Some are called "prompt neutrons," but others experience a delay of up to 56 seconds.

The challenge for nuclear engineers is to keep the ongoing fission reaction in precise balance. When the reaction is in balance, scientists say that it has reached "criticality." At criticality, the neutrons are doing their work in balance, meaning that their numbers remain constant and under control. The pace of the reaction can be speeded up or slowed down by increasing or decreasing the number of neutrons. If the increase is too rapid, the reaction can almost instantaneously get out of control.

Plutonium

Plutonium (chemical symbol Pu), named after the planet Pluto, is an element that forms in a reactor core as the isotope Pu239. It forms when U238, which is also present in nuclear fuel, absorbs a neutron. Now the atom has an odd number of particles in the nucleus, making it fissile in the same way that U235 is. But like U235, it sometimes just absorbs the neutron, creating the isotope Pu240, which is not fissile. Over time, the amount of Pu240 builds up in the fuel rods. When the rods are "spent," or no longer usable as fuel, this plutonium can be recycled. It undergoes a conversion process that makes it usable as nuclear fuel. Not all nuclear reactors are designed to allow this recovery and conversion process. Those that do are called "breeder reactors," for they "breed," or produce, additional fuel.

Plutonium is perhaps the most highly toxic substance that exists. The smallest amount can cause such diseases as lung cancer. Workers who handle plutonium observe the strictest safeguards to avoid exposure.

Uranium: From the ground to the reactor

While uranium can be found in seawater, it is found most commonly in rocks and is as common as the elements tin and gold. It exists in concentrations of about two to four parts per million. Uranium is mined in at least two ways. One is to dig up the ore that contains it, crush the ore, and then treat it with acid, which dissolves the uranium to remove it from the ore. The other is a process called in situ leaching (in situ is Latin for "in place"). In this process, the uranium is dissolved from rock and pumped to the surface of the Earth. Either way, the end result is a compound called uranium oxide, or U3O8. This material is often referred to as "yellowcake."

The uranium, though, cannot be used as fuel in this form. It first has to be "enriched," so mine operators sell the yellowcake to uranium enrichment plants. The first step in converting it into a usable fuel is to convert it into a gas, uranium hexafluoride, or UF6. This increases the amount of uranium from its natural level of 0.7 percent to 3 to 4 percent, so the uranium is said to be "enriched." The next step is to convert the uranium hexafluoride to uranium dioxide, or UO2. Uranium dioxide can then be processed into pellets that are about the size of a knuckle on a person's finger. The pellets are then inserted into thin, 12-foot-long (3.5-meter-long) metal tubes, called fuel rods. Bundles of these tubes are then inserted underwater into the core of the nuclear reactor.

Inside the reactor

A nuclear power plant has been constructed, probably at a cost of anywhere from $3 billion to $5 billion, or even more. Construction of the plant took at least four years, possibly up to ten years. Geologists have carefully considered the site of the plant to make sure that the chances of it being damaged by an earthquake or volcanic activity are small. Engineers and construction workers have carefully built the plant. The materials used were of the highest standards. Every weld in metal components was closely examined and even x-rayed to be sure it is as close to perfect as possible. Provisions were made to ensure that the plant is secure, so that terrorists or others cannot enter and take it over. Provisions have also been made for the safety of the plant's employees so they can quickly shield themselves from radiation in the event of an accident. The plant is built with "redundant," or repetitive, safety systems, so that if something breaks down, there is a backup. The most critical of these systems is water that can be used to cool an overheated reactor. No detail is overlooked.

As the time approaches for the plant to come online and begin producing power, the fuel is inserted into the tubes and the tubes, up to 200 of them, are inserted into the reactor core. Then, at the appropriate moment, the control rods are slowly pulled out. These rods are generally made of graphite or boron, and they control the pace of the nuclear reaction by absorbing neutrons. The farther the rods are inserted, the more neutrons they absorb, slowing down or stopping the reaction. As they are withdrawn, more and more neutrons make it to their target, and the chain reaction begins.

At this point the plant is nowhere near ready to operate at maximum power output. For weeks, the plant's engineers will fire up the reactor very slowly. They will check and recheck every component of the plant to make sure that everything is operating properly and safely. After a period of several weeks of testing, the reactor will begin producing power at its normal operating level, and consumers will begin enjoying the benefits of the electricity it produces.

CURRENT AND FUTURE TECHNOLOGY

Nuclear power plants come in many different shapes and designs. Many of the first plants to be constructed were huge, enabling them to produce the greatest amount of power possible. More recent designs are smaller, making them less costly and easier to build. But despite their many technical and engineering differences, nuclear reactors come in two basic types: pressurized water systems and boiling water systems.

Pressurized water reactor system

One system in common use is called the pressurized water reactor system. It is given this name because it relies on water under pressure to produce the heat needed to produce electricity. In such a system, the fuel rods are inserted into a steel pressure tank that contains ordinary water. The water acts as a coolant, but it also moderates the reaction because it can absorb neutrons. Protruding (sticking out) through the lid of the pressure tank are the control rods.

As the control rods are slowly pulled out, the chain reaction begins. The reaction produces heat, which heats the water in the pressure tank. The water heats to 518° Fahrenheit (270° Celsius). The water does not boil, though, because it is under intense pressure.

The heated water is then channeled to a heat exchanger in a closed circuit. The water in the heat exchanger is then heated up, producing steam. The steam drives a turbine generator that is little different in principle from a turbine used in a windmill or a hydroelectric dam. As the generator turns, it produces electricity. Meanwhile, the steam is condensed, usually by cool water from a lake or river, and returned to the heat exchanger.

Boiling water reactor system

The other major system, the boiling water reactor system, is more efficient than the pressurized water system. One noticeable difference is that with a boiling water system, the control rods protrude from the bottom of the containment chamber. Inside the chamber is the reactor core. The control rods are at the bottom because the water inside the chamber is allowed to boil. The steam created by the boiling water is allowed to rise to the top of the chamber. Pipelines carry the steam directly to the turbines, where its heat causes them to turn to create electricity. The steam then condenses and is channeled back into the containment chamber. Underneath the reactor is a circular tunnel filled partway with water. This tunnel is a safety mechanism. If any steam or water were to escape from the containment chamber, it would fall into the tunnel, where it could do no immediate harm.

The possibility of nuclear fusion

Scientists look forward to the discovery of a power source that is clean, safe, universally available at all times to all people throughout the world, and that uses a fuel that is abundant, cheap, and efficient. It would not contribute to global warming or air pollution, require large plants that would disrupt the natural environment, or produce dangerous by-products. To that end, some scientists conduct research into what is called "cold fusion." Cold fusion uses fuel that is commonly available from the hydrogen in water. However, governments have favored a more conventional approach to fusion at extremely high temperatures. In 2005, Cadarache in France was chosen as the site for the International Thermonuclear Experimental Reactor. This will be built as a cooperative venture between the EU, U.S., Russia, China, Japan, and South Korea. This is a major step in the development of fusion as a potential large-scale source of electricity that will not contribute to climate change.

Nuclear fission refers to the splitting, or breaking apart, of atoms. Nuclear fusion, as the name suggests, involves the fusing, or joining together, of atoms. The light nuclei of two atoms bind together during nuclear fusion to form a single heavier nucleus. One example is the deuteron, a single particle formed by the combination of a neutron and a proton. When a deuteron or similar particle is formed, its mass is generally less than the total mass of the two original particles. The mass that disappears is released as energy. What appeals to scientists seeking to harness nuclear fusion is that such reactions occur in nature throughout the universe, particularly in stars. Fusion takes place in stars because of their high temperatures, up to 18,000,032° Fahrenheit (10 million° Celsius), possibly even hundreds of millions of degrees. The problem is that while such high temperatures can be found in the center of stars, including the Earth's sun, they do not occur naturally on Earth.

Despite the high temperature needed for fusion to occur, scientists have tried to reproduce fusion reactions on Earth. The process they formulated was to use two isotopes of hydrogen. These isotopes, called "heavy hydrogen" because they contain extra atomic particles, are deuterium and tritium. While a normal hydrogen atom consists of a single electron and a single proton in the nucleus, deuterium also contains one neutron in the nucleus and tritium contains two. These isotopes fuse at lower temperatures than do the nuclei of regular hydrogen atoms, and they are relatively abundant. In the oceans, about one in 6,500 or 7,000 hydrogen atoms are deuterium, and they can be easily extracted. The source of tritium is an element called lithium, which is abundant in the Earth's crust.

Scientists discovered that when a mixture of deuterium and tritium is raised to a high enough temperature, or when the elements are accelerated to a very high speed, one deuterium nucleus fuses with one tritium nucleus. The result is a new element, helium. More importantly, excess energy is given off in the form of a neutron that moves at a very high speed. Scientists believe that fusion could be the "fuel of the future" because the fueldeuterium and tritiumcontains an enormous amount of energy, called "density" by scientists. It has been estimated that a single thimbleful of heavy hydrogen contains the same amount of energy as 20 tons of coal. An amount that would fill the bed of a pickup truck would provide the same amount of energy as 21,000 rail cars full of coal or 10 million barrels of oil. Further, using such fuel would be extremely safe. The only by-product is helium, and there is no danger of a fusion reaction spinning out of control. If the fuel escapes, the fusion reaction simply stops.

So far, fusion experiments have failed to produce any power in excess of the power needed to produce the fusion reaction. In other words, there was a net power loss. For many scientists, the enormous energy demands of hot fusion make it impractical. Instead, they have searched for a way to create fusion reactions at low temperatures, called "cold fusion." Cold fusion is a term coined in 1986 by Dr. Paul Palmer of Brigham Young University in Utah. It is the popular term for what scientists call "low energy nuclear reactions" in a field that is sometimes called "condensed matter nuclear science."

In 1984 two scientists, Stanley Pons of the University of Utah and Martin Fleischmann from England's University of Southampton, began conducting cold fusion experiments at the University of Utah. On March 23, 1989, Pons and Fleischmann made an announcement that startled the world. The two claimed that they had successfully carried out a cold fusion experiment. This experiment produced excess heat that could be explained only by a fusion reaction, not by chemical processes. Many scientists, though, disputed their claim. They tried to duplicate the Pons-Fleischmann experiment and failed.

So the question remains: Is cold fusion possible? Some scientists answer with a no. Many other scientists, though, disagree. They point out that cold fusion research is still just beginning. Some of the problems reported with duplicating the Pons-Fleischmann findings have been the result of normal uncertainties about how to design and conduct experiments to get consistent results.

Meanwhile, many scientists have made claims that they have produced cold fusion. Some of the most prominent researchers in the field are in Japan, where the level of funding for cold fusion research is much higher than it is in the United States. At Japan's Hokkaido University, for example, D. T. Munzo reported experiments in which the ratio of energy output to energy input was seventy thousand to one. As of 2005, though, the world seemed decades away from seeing a commercial fusion reactor, whether hot or cold.

BENEFITS AND DRAWBACKS

In the imaginations of many people, nuclear power plants are surrounded by a field of radiation. As they drive down the highway and see the characteristic cooling tower of a nuclear power plant rising on the horizon, some people feel a slight twinge of anxiety. They know that they are not being exposed to radiation, yet their emotions make them wonder whether maybe they are.

Supporters of nuclear energy dismiss these concerns. They argue that nuclear power plants are safe and that nuclear power offers many significant benefits. At the same time, nuclear power has significant drawbacks, particularly the potential for accidents, the problem of nuclear waste disposal, and the possibility that terrorists could attack nuclear power plants.

Benefits

The benefits of nuclear energy include the following:

  1. Many scientists believe that nuclear energy remains the best way to provide large amounts of power for a large and growing world population. A typical nuclear power plant produces 1,000 megawatts, or 1 billion watts, of electricity. Other forms of alternative energy produce far less, particularly relative to their size. For example, the largest wind farm in the United States is the Stateline Wind Energy Center along the Columbia River on the Washington-Oregon border. This massive farm consists of 454 wind turbines, each 166 feet (50 meters) tall and, at peak capacity, generating 660 kilowatts, or 660,000 watts of power. Because of changing wind conditions, the windmills do not always operate at peak capacity. To provide power equivalent to that of nuclear power plants, immense numbers of large wind farms would have to be built.
  2. Nuclear energy is reliable. In contrast to most other forms of alternative energy, nuclear energy can be provided on a consistent, predictable basis nearly anywhere in the world. It is not subject to weather conditions. In contrast, solar power requires consistent sunshine, so not all areas are suitable for solar power. Wind power has similar limitations. Hydroelectric dams provide large amounts of power worldwide, but the number of rivers that remain suitable for damming is limited. Such alternatives as ocean wave power and tidal power are likewise limited by geography and unpredictable weather patterns.
  3. The supply of fuel for nuclear power is abundant. Uranium exists throughout the Earth's crust, although in some places, it can be mined more easily than in others. Scientists estimate that the amount of uranium known to be readily available is enough to last fifty years. However, they also point out that its relative abundance has not made it necessary for mining companies to search very hard for it. Scientists are confident that more intensive searching will yield abundant new reserves of uranium. While uranium is not renewable, as wind and solar power are, enough probably exists for many centuries to come. Further, nuclear plants produce plutonium as a by-product of the nuclear reaction. This plutonium can be reprocessed into fuel.
  1. The price of nuclear fuel remains relatively constant, and its sources remain relatively consistent. Uranium is mined extensively in about twenty countries throughout the world. The relatively large number of suppliers ensures that prices do not change rapidly and unexpectedly. In contrast, the world's petroleum reserves are in the hands of a small number of countries. Many of these countries are politically unstable. As the Arab oil embargoes of the 1970s showed, oil supplies to the United States and other countries can be cut off overnight for political reasons. Uranium is not subject to these uncertainties, and nations such as the United States and Canada can mine their own uranium. In fact, Canada leads the world in uranium mining. Another leading producer is Australia, which, ironically, has no nuclear power plants.
  2. Nuclear power plants have a low impact on the environment. A chief advantage of nuclear power is that it does not require the burning of fossil fuels such as coal. Thus, it is cleaner than fossil fuels and does not contribute to pollution.
  3. Nuclear power plants are safe. As of late 2005 the only deaths that have ever resulted from a nuclear power plant accident occurred at the Chernobyl plant in Ukraine. Nuclear experts, though, note that the design of the Chernobyl plant was extremely outdated and that the plant was not very well constructed. This was a common problem for all types of construction under the Communist regime of the old Soviet Union. They believe that the kind of accident that happened at Chernobyl is much less likely with more modern and better built plants. This has meant that despite worries among the public, politicians have increasingly seen modern nuclear reactors as a source of energy that avoids emission of greenhouse gases and after a period where few reactors have been built they are being re-considered as energy sources.
  4. With regard to safety, the track record of the nuclear industry has improved over the 1990s and early 2000s. For example, when something in the operation of a nuclear plant gets out of kilter, a "scram" takes places. This refers to a wide range of automatic safety mechanisms. Alarms sound, backup systems kick in if necessary, and the plant's controls automatically make necessary adjustments, particularly making sure that water surrounds the reactor core to keep its temperature under control. If necessary, the nuclear reaction stops and the reactor shuts down. The nuclear industry keeps track of the number of scrams per 7,000 hours of operation, or about one year. In the late 1990s two-thirds of U.S. nuclear power plants had zero scrams. The number of scrams at the other third was extremely low, and usually the problems that caused them were minor and easily fixed.
  5. A major concern for nuclear plant workers is exposure to radiation. People are exposed to radiation every day of their lives. Radiation reaches the Earth from the sun, and it radiates from rocks in the earth. This radiation is referred to as "background radiation," and it varies with altitude (height above sea level) and geography. People in such countries as Finland are exposed to three times as much background radiation as Australians. Even on an airline flight over the North Pole from, say, Tokyo to London, people are exposed to cosmic radiation seven to eight times the normal level.

Drawbacks

Despite its many benefits, nuclear power has significant drawbacks as well. Throughout the 1990s and into the new millennium, scientists, environmentalists, and the public have focused more of their attention on these drawbacks. As a result, nuclear power has become an emotional political issue. Its opponents are passionate in their belief that nuclear power poses a significant danger to the world. Some of their concerns include the following.

Catastrophic accident

The potential for a catastrophic accident continues to exist. The world's nuclear power plants have accumulated a total of about twelve thousand years of operation. During that time, there have been only two significant accidents, Three Mile Island (although the public was not exposed to radiation during that accident) and Chernobyl. Supporters of nuclear power point out that far more people lose their lives in accidents at conventional power plants in one year than have lost their lives in nuclear accidents.

The problem is one of public attitudes rather than statistics. Opponents of nuclear power note that a catastrophic accident at a conventional power plant might be tragic for those injured and killed. Still, the effects would be limited to the plant itself and perhaps the immediately surrounding area. Deadly radiation would not be released into the atmosphere. People would not have to be evacuated, and those nearby when the accident occurred would not suffer the ill effects of radiation.

In contrast, a catastrophic accident at a nuclear plant could have enormous effects on the surrounding environment, effects that would last for decades, if not longer. Nuclear opponents believe that the risk is simply too great. One mistake, one faulty component, one operator error could create an environmental catastrophe. The margin for error is nearly zero. While the risk of a nuclear catastrophe is low, such a catastrophe would have high consequences.

Adding to the problem is the mysteriousness of anything nuclear. Ever since the atomic bombings of Japan at the end of the Second World War, people have been afraid of nuclear power. Excessive exposure to nuclear radiation can cause cancer, another word people respond to with fear. Few people understand nuclear physics. That sense of awe and mystery spills over into fear of anything "nuclear," including nuclear power plants.

Waste storage and disposal

Nuclear waste comes in two types: low-level and high-level. Low-level waste is produced by hospitals, which use radioactive materials for certain medical tests. Similar low-level waste is also used for research purposes at universities and other research facilities. This material has to be disposed of safely, and if it is done so, it poses little health risk to the public. The radioactivity in these materials breaks down quickly (usually in days or at most weeks), and the material can then be disposed of as normal trash.

Safety Stats

In 1998 the U.S. Bureau of Labor Statistics reported that for every 200,000 hours of work performed in nuclear plants, there were 0.34 accidents that resulted in injury. In contrast, for all other industries, the number was seven times greater, or 2.3 accidents per 200,000 worker hours.

High-level nuclear waste, such as that produced by nuclear power plants and in producing and dismantling (taking apart) nuclear weapons, is another matter. As of 2003 the United States had accumulated about 49,000 metric tons (a metric ton is about 2,200 pounds) of spent nuclear fuel rods. These are fuel rods that have been removed from power plants because the fuel is depleted. This amount would cover a football field to a height of 10 feet (3 meters). The U.S. Department of Energy estimates that the amount will total 105,000 metric tons by the year 2035. Much of this material is stored in water pools on the sites of nuclear power plants. No one knows what to do with this accumulating waste.

The problem with nuclear waste is the half-life of such elements as uranium and plutonium, as well as other radioactive materials produced in nuclear power reactors as by-products. Some of these by-products include cesium-137 and strontium-90, both highly radioactive. Most of these elements have extremely long half-lives. The half-life of plutonium is 24,000 years. The half-lives of some other radioactive elements are 100,000 years, even longer. This means that nuclear waste disposal has to be thought of in terms of geologic time, not next year or even next century. The ancient Roman Empire was thriving just 2,000 years ago; the ancient Egyptians, 3,000 years ago. Humans find it hard to think that far ahead.

Roughly every twelve to eighteen months, a nuclear plant has to shut down and all the fuel rods have to be replaced. These fuel rods are highly radioactive, so they cannot simply be taken to the nearest landfill. Strict precautions have to be taken to make sure that the spent rods do not pose a risk to the environment or to the public. Further, when a nuclear plant is "decommissioned," or shut down, the radioactive components in the core have to be disposed of properly. All of this is a difficult technical undertaking and one that carries a high expense.

Several proposals have been made for ways to dispose of high-level nuclear waste. One proposal is to launch it into space. Others are to bury it on a remote island or in the polar ice sheets. So far, these have not been attempted. Another proposal is to bury the waste under the seabeds. While technically possible, the expense of doing so would be enormous.

The most widely accepted possibility is to bury nuclear waste underground in stable geological formations. The waste would undergo first a process called vitrification (from the Latin word vitrium, meaning "glass"). This means that the waste is mixed with silica (like sand) and melted into glass beads. This process makes the waste more stable and reduces the chance that radiation could seep out into the air or water. The beads are then buried in an area that is geologically stable (that is, it does not experience earthquakes, tremors, or volcanic activity). When the storage facility is full, it would be sealed with rock.

The problem with this method is that no community wants to be home to the storage site. Nuclear waste would have to be trucked in, with the potential for accidents. Then the nuclear waste would be stored nearby, essentially forever. In 1983 President Ronald Reagan signed into law the Nuclear Waste Disposal Act. Under the act, the federal government took on responsibility for nuclear waste disposal. The act required the U.S. Department of Energy to find a suitable site for underground storage, then build the facility. In 2002 the department identified Yucca Mountain in Nevada as the most suitable site. Understandably, Nevadans do not want to be the dumping ground for the nation's nuclear industry and have opposed this plan. The state's governor notified the federal government that Nevada opposed the plan. The U.S. Congress voted to override the governor's objections. Accordingly, the federal government has designated the Yucca Mountain site as a long-term storage facility for about 70,000 metric tons of nuclear waste. As of late 2005, however, the issue was still not entirely resolved. No steps had been taken to construct the facility.

Another problem the nuclear industry has created is "mill tailings." These are waste materials created in mining uranium ore. The materials contain trace amounts of uranium left behind, as well as radium and thorium, both radioactive. The radioactive material cannot simply be left in place. The federal government, specifically the U.S. Nuclear Regulatory Commission, regulates the removal, storage, and monitoring of mill tailings.

Terrorism

After the terrorist attacks on the United States on September 11, 2001, policy makers raised concerns about the security of the nation's nuclear power plants. It is known that members of al-Qaeda, the Islamic terrorist network, have been instructed and trained in ways to attack power plants. The concerns of policy makers and nuclear regulatory officials are many:

As they did on September 11, terrorists could hijack an airliner and fly it into a nuclear power plant. The scientific director of the Nuclear Control Institute believes that a direct, high-speed impact by a large airliner "would in fact have a high likelihood of penetrating a containment building" with a nuclear reactor inside. "Following such an assault," he said, "the possibility of an unmitigated [unstopped] loss-of-coolant accident and significant release of radiation into the environment is a very real one." Other scientists believe that most nuclear plants could withstand the impact of an airliner.

Why Yucca Mountain?

The federal government identified Yucca Mountain, about 100 miles (161 kilometers) northwest of Las Vegas, as the best site in the United States for long-term nuclear waste disposal. This site was selected for a number of reasons that highlight the problems of disposing of nuclear waste:

The area has a dry climate. Yucca Mountain receives only about 7.5 inches (19 centimeters) of rainfall each year. Most of the rain runs off or evaporates. The rainfall that remains moves through the rock at a rate of only about .5 inch (1.27 centimeters) per year.

Yucca Mountain is stable geologically. Studies have shown that Yucca Mountain has not changed much for at least one million years. The earth surrounding the mountain does not shift because of volcanoes or earthquakes. Because the waste would be 1,000 feet (305 meters) below the surface, any earthquakes that did take place would likely not allow any of the material to leak out. This is because earthquakes are most intense at the Earth's surface.

The Yucca Mountain site has a deep water table. The water table, the level at which underground water is reached, is about 2,000 feet (610 meters) below the surface. The nuclear waste would be stored about 1,000 feet (305 meters) below the surface. Therefore, the water would never reach the waste. If by some chance it ever did, the water that flows under Yucca Mountain continues to flow underground into Death Valley, a forbidding desert. None of this water is used to supply water to nearby cities. Further, the Yucca Mountain site is in an enclosed water basin. This means that the area is completely surrounded by higher land. This in turn means that water flows downward and stays put. It does not spill into aquifers (water-bearing rock and sand) that supply drinking water.

The area is in a remote location. No one lives on Yucca Mountain, and the nearest people are 15 miles (24 kilometers) away. Most of the land around Yucca Mountain, about 1,375 square miles (3,561 square kilometers), has been taken over by the federal government. It is also on the edge of sites that were once used to test nuclear weapons, sites on which no one wants to live or work. If that area is added in, the unpopulated area is 5,470 square miles (14,167 kilometers).

Finally, access to the Yucca Mountain site is highly restricted. The U.S. Air Force maintains training sites and gunnery ranges in the area. The area is dense with security personnel and procedures, so it would be nearly impossible for anyone to disturb the site. Further, geologists have determined that the site has no valuable minerals, oil, precious metals, or other assets. Therefore, geologists believe that, even thousands of years from now, no one would have any reason to dig the site up.

Terrorists could steal plutonium or highly enriched uranium, either from the plants themselves of from uranium enrichment facilities. It takes only about 18 pounds (8 kilograms) of plutonium or 55 pounds (25 kilograms) of highly enriched uranium to build a nuclear weapon. But in the nuclear industry, these materials are moved about by the ton, and accurate records are not always kept. Policy makers believe that a sophisticated terrorist group could steal these materials and make a nuclear bomb. The materials could also be used to construct so-called "dirty bombs," or what experts call "radiation dispersal devices." These are bombs made of conventional explosives such as dynamite that are packed with nuclear materials, even nuclear waste. The explosion would disperse, or distribute, the radioactive materials around a wide area. The result would be public panic and an area contaminated with radiation.

Policy makers are also concerned about security at nuclear facilities. After September 11, training exercises were carried out at nuclear plants to see how well the plants' personnel could resist a terrorist attack. Military personnel disguised as terrorists attempted to gain access to these plants. Some experts claim that at nearly one-half of U.S. nuclear power plants, armed guards were not able to stop these mock attacks.

A final concern is nuclear proliferation. Proliferation means "spreading," and the concern is that nations can develop nuclear poweror claim toand convert their nuclear capabilities into weapons. In 2005 many nations of the world, including the United States, were opposing nuclear development programs in Communist North Korea and Iran. While these countries insisted that their programs were for peaceful purposes, worries persisted that they were trying to develop nuclear weapons.

ENVIRONMENTAL IMPACT

The chief benefit to the environment of nuclear power plants is that they do not emit (give off) harmful gases, such as carbon dioxide and sulfur dioxide. In this way they differ from conventional power plants, which emit these gases primarily because they burn coal, a fossil fuel. If the energy generated by nuclear power plants worldwide were instead generated by burning coal, the amount of additional carbon dioxide released into the atmosphere would be about 1,600 million tons. Moreover, burning coal releases toxic heavy metals, including arsenic, cadmium, lead, and mercury. Nuclear energy prevents release into the atmosphere of about 90,000 tons of these metals each year. France's heavy reliance on nuclear power has lowered that country's air pollution from electrical generation by 80 to 90 percent.

By not emitting these gases, nuclear energy does not contribute to environmental problems such as air pollution, smog, and the "greenhouse effect." The greenhouse effect refers to the ability of some gases, such as carbon dioxide, to accumulate in the air. The theory is that in doing so, they act like a greenhouse, trapping the sun's heat. In turn, many scientists believe that this trapped heat is increasing average temperatures around the world. This increase is referred to as "global warming." Global warming is blamed for the melting of the polar ice, raising sea levels and endangering coastal cities. (Not all scientists agree that this is happening.) Further, by not emitting pollutants, nuclear power plants do not contribute to acid rain. Acid rain is any form of precipitation that is more acidic than normal because the water has absorbed acidic pollutants from the air. Acid rain can harm crops and forests. It can also contribute to the deterioration of buildings and public monuments, which dissolve because of the acid in precipitation.

Nuclear power plants also do not harm surrounding bodies of water. A myth that some people believe is that nuclear plants discharge water into nearby lakes and streams that is either radioactive or extremely hot. This is not true. The water released from a nuclear plant never comes into contact with the radiation. Further, if the water is too hot to be discharged, it is cooled either in a cooling pond or in cooling towers before release.

Supporters of nuclear power point out that some other alternative forms of energy do not have the same low impact on the environment, especially hydroelectric dams. While such dams have the benefit of not emitting harmful gases or pollutants, the dams have a major impact on the surrounding environment. By turning rivers into huge lakes, they disrupt vegetation and wildlife. Many dams have displaced (driven out) large numbers of people. Further, the reservoirs behind hydroelectric dams emit their own form of pollution. As the water level of the reservoir falls, the wet ground that surrounds it supports the growth of vegetation. As the water rises, this vegetation is covered and rots. The rotting vegetation emits methane gas, a pollutant. In addition, hydroelectric dams have an adverse effect on fish because they disrupt breeding and spawning grounds.

Nuclear power plants do not have harmful effects on wildlife. In fact, they often can have beneficial effects. For example, when cooled water is released from the plant, the water often contributes to the formation of wetlands. These wetlands can become nesting grounds and provide habitat for birds, fish, and other animals. Some companies that build and run nuclear plants even develop wildlife preserves and parks in the surrounding area, where plants grow abundantly in the moist soil.

Even species that are endangered (that is, in danger of becoming extinct) have found new life around nuclear plants. Some of these species thrive nearby, including such endangered species as bald eagles, red-cockaded woodpeckers, peregrine falcons, osprey, and the beach tiger beetle. The areas around nuclear plants are also home to such nonendangered species as wild turkeys, sea lions, bluebirds, kestrels, wood ducks, and pheasant.

Again, supporters of nuclear power point out that other forms of alternative energy do not have the same benefits. They agree that solar power and wind power are cleaner forms of energy, but they require huge "farms" of solar panels or windmills to produce significant amounts of electricity. Some argue that wind farms hurt an area's bird populations because the birds become almost hypnotized by the turning blades and fly right into them, where they are killed. By reducing an area's bird populations, the rodents that birds eat can multiply freely and cause rodent infestations.

Nuclear power protects land and animal habitats. Per unit of electricity, nuclear power plants take up far less land than other types of power-generating stations. For example, assume a plant that produces 1,000 megawatts of power (a megawatt is a million watts, so a thousand megawatts is 1 billion watts). To produce the same amount of power, a solar "farm" would need 35,000 acres of solar panels. A wind farm would require 135,000 acres devoted to windmills. In contrast, a typical nuclear power plant takes up only about 500 acres of land.

Further, the fuel nuclear power plants use, uranium, is very energy dense. This means that a pound of the fuel produces far more energy than a pound of coal. For example, one metric ton of uranium, or about 2,200 pounds (998 kilograms), will power a 1,000-megawatt nuclear power plant for two weeks. This fuel would come from about nine metric tons of mined uranium oxide. The same amount of energy from coal would require about 160,000 metric tons, or almost 353 million pounds. Thus, mining nuclear fuel has much less impact on the environment.

With regard to energy output, some nuclear power opponents say that these figures are misleading. They point out that conventional fuels like coal have to be burned to process uranium for use as fuel. They are correct, but the amount of conventional energy that has to be burned to do so is about 2 percent of the amount of energy the uranium will produce.

ECONOMIC IMPACT

In examining the cost of nuclear energy, many factors have to be taken into account. Some of these are obvious, such as construction costs and the cost of mining uranium. Others are more hidden and include taxes, licensing fees, interest payments on debt, and the like. Thus, any examination of the economic costs and benefits of nuclear energy involves complex calculations.

The first cost comparison involves the fuel itself. Uranium has to be mined, converted, enriched, and loaded into fuel rods. Coal has to be mined, but it can be used as is. On the other hand, the cost of transporting nuclear fuel is low because of its energy density. The cost of transporting coal is high because large volumes have to be shipped.

Per unit of energy, the cost of a nuclear power plant is generally higher than that of a conventional power plant. Nuclear power plants have to be built to the highest standards. Many of their systems are redundant, or repetitive, for safety reasons. On the other hand, coal-fired plants have additional costs because of requirements that they have pollution-control devices, such as scrubbers that remove particles from their emissions. Debt also increases the cost of nuclear plants. Because building these plants is so expensive, power companies have to borrow large sums of money, and they have to pay interest on that debt. Thus, high interest payments have added to their costs.

Nuclear power plants have higher maintenance costs than do conventional power plants. For example, corrosion and cracking are common problems in the water pipes in boiling water reactors. These components have to be replaced at great cost. In the meantime, the reactor is shut down. It is not producing energy, but workers still have to be paid and debt still has to be financed.

Both conventional and nuclear power plants have normal day-to-day costs. Nuclear facilities require highly trained technicians, engineers, safety inspectors, health workers, and the like, increasing labor costs. Conventional plants are relatively simple to operate, so they do not require as many highly trained workers. However, they require a larger labor force because of the amount of labor involved in running the plant's operations.

Nuclear plants face other charges as well. The license fee for a nuclear reactor is almost $3 million. The license for nuclear fuel use is over $2.5 million. Many nuclear plants pay $15 to $20 million in local property taxes. In addition, the Nuclear Regulatory Commission requires nuclear plant operators to take on expenses for other specialized needs, including, for example, radiographers who measure radiation in the plant. Producing nuclear energy does not come cheap.

On top of all these expenses, the nuclear industry spends many dollars for nuclear waste disposal. Coal-fired plants have only to dispose of ash. Further, the cost of decommissioning a nuclear power plant is high, often 4 percent of the initial cost of construction. A coal-fired plant that is put out of commission essentially just has to be knocked down and carted away. Yet most costs are comparable. The end result is that nuclear power is slightly more expensive than coal.

SOCIETAL IMPACT

The societal impact of nuclear power tends to be a matter more of perceptions and public sentiment than facts. Opinions about nuclear power are likely to depend on opinions about science. On the one hand, many people place a great deal of faith in science. They believe that science can solve many of the world's ills. Science, for example, can increase crop yields in poorer nations. It can reduce and eventually eliminate many diseases. And it can provide for the energy needs of the six billion people who live on Eartha number that is likely to grow significantly as the twenty-first century progresses. Scientists, with their specialized knowledge, have become almost like magicians who solve the world's problems.

As the sheer volume of scientific information grows each year, however, the public feels disconnected from scientists and their magic. Few people know how a toaster works, let alone something as complex as a nuclear power plant. Further, they believe that while science can solve problems, it has also caused problems. In their view, the Earth and its resources have been exploited in the name of science. The atmosphere and bodies of water have been polluted because of scientific and technological advancement. Some of the people who feel this way yearn for a simpler time, when people (in their view) lived in harmony with the natural world. They were attuned to the cycles of the natural world and accepted them rather than trying to conquer them through science.

Nuclear energy stands at the center of this dilemma. Supporters of nuclear energy point to its clear benefits. It provides large amounts of power. It does not release pollution into the atmosphere. It does not consume resources whose supply will eventually run out. It does not make countries such as the United States dependent on foreign sources of fuel. It has an exemplary safety record, and improvements in the design of nuclear power plants make them safer than ever. Perhaps most importantly, nuclear power is the best hope for developing nations such as India and China. These and other countries are attempting to find a place for their large populations among the developed nations of the world. To do so, they need energy.

This point of view is not shared by all people. Many environmentalists believe that nuclear power plants are a disaster waiting to happen. Their views are sometimes supported by the mass media, which tends to focus on bad news rather than good. A documentary prepared by the Public Broadcasting Service (PBS) is a case in point. The documentary was titled "Meltdown at Three Mile Island." This title is dramatic, but it is false. No "meltdown" occurred at Three Mile Island.

BARRIERS TO IMPLEMENTATION OR ACCEPTANCE

The popular culture adds to the climate of distrust and emotional debate surrounding nuclear energy. Movies routinely depict scientists as "mad," as people bent on making scientific discoveries no matter what effects those discoveries might have on the human community. Cable-television science fiction channels routinely run movies about creatures that have been mutated into killer beasts because of science, especially nuclear science. At best, the stereotype of the scientist is one of an unappealing, slightly eccentric person. In this climate, the mysteries of nuclear power become an easy target for people's fears and uncertainties about the future.

During the first years of the twenty-first century, nuclear energy development was very much on hold, particularly in Western nations such as those in North America and Europe, as well as Australia. Public sentiment in the West favors other alternatives, such as solar, wind, and hydrogen. Less developed nations, though, do not have the luxury of picking and choosing, and many are going ahead with plans for nuclear power plants.

For More Information

Books

Angelo, Joseph A. Nuclear Technology. Westport, CT: Greenwood Press, 2004.

Domenici, Peter V. A Brighter Tomorrow: Fulfilling the Promise of Nuclear Energy. Lanham, MD: Rowman and Littlefield, 2004.

Heaberlin, Scott W. A Case for Nuclear-Generated Electricity: (Or Why I Think Nuclear Power Is Cool and Why It Is Important That You Think So Too). Columbus, OH: Battelle Press, 2003.

Kaku, Michio, and Jennifer Trainer, eds. Nuclear Power: Both Sides. New York: Norton, 1983.

Lusted, Marcia, and Greg Lusted. A Nuclear Power Plant. San Diego, CA: Lucent Books, 2004.

Morris, Robert C. The Environmental Case for Nuclear Power. St. Paul, MN: Paragon House, 2000.

Seaborg, Glenn T. Peaceful Uses of Nuclear Energy. Honolulu, HI: University Press of the Pacific, 2005.

Web sites

"The Discovery of Fission." Center for History of Physics. http://www.aip.org/history/mod/fission/fission1/01.html (accessed on December 17, 2005).

"Nuclear TerrorismHow to Prevent It." Nuclear Control Institute. http://www.nci.org/nuketerror.htm (accessed on December 17, 2005).

"Safety of Nuclear Power." Uranium Information Centre, Ltd. http://www.uic.com.au/nip14.htm (accessed on December 17, 2005).

"What Is Uranium? How Does It Work?" World Nuclear Association. http://www.world-nuclear.org/education/uran.htm (accessed on December 17, 2005).

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Nuclear Energy

chapter 5
NUCLEAR ENERGY

Nuclear energy is used in the United States to generate electricity and to power some navy ships. In the decades since the first commercial nuclear reactor went into operation in 1956, the nuclear power industry has had a difficult time persuading the American public of the safety of its enterprise. In the early 1970s most Americans favored the use of nuclear power because it appeared to provide cleaner, more efficient, energy than fossil fuels, and it could help reduce U.S. dependence on foreign energy sources. But by the early 2000s many people in the United States—and, indeed, around the world—opposed building additional nuclear power plants. The 1979 disaster at Three Mile Island in Pennsylvania and the 1986 catastrophe at Chernobyl in the former Soviet Union greatly increased public concerns about the safety of nuclear power, as have reports of design flaws, cracks, and leaks in other reactors. Furthermore, the safe disposal of radioactive waste, which is a by-product of nuclear energy, has proven difficult.

Supporters of nuclear power believe that it is as safe as any other form of energy production if monitored correctly. They point to growing concerns about fossil fuel use, including global warming and acid rain, as well as damage caused by mining and transporting fossil fuels. In fact, this growing concern over fossil fuels has led a small number of environmentalists who had previously opposed nuclear power to reconsider their position. Nonetheless, environmental, safety, and economic concerns have restrained growth in the nuclear industry since the mid-1970s. Unwillingness to commission new nuclear plants is evident in Figure 5.1, which shows a general leveling off of nuclear energy's share of electricity production from 1988 through 2003 at about 20%.

HOW NUCLEAR ENERGY WORKS

In a nuclear power plant, fuel (uranium in the United States) in the reactor generates a nuclear reaction (fission) that produces heat. In a pressurized water reactor (see Figure

FIGURE 5.1

5.2), the heat from the reaction is carried away by water under high pressure, which heats a second water stream, producing steam. The steam runs through a turbine (similar to a jet engine), making it and the attached electrical generator spin, which produces electricity. The steam is then cooled and recirculated. The large cooling towers associated with nuclear plants are used to cool the steam after it has run through the turbines. A boiling water reactor works much the same way, except that the water surrounding the core boils and directly produces the steam, which is then piped to the turbine generator.

FIGURE 5.2

The key problems in operating a nuclear power reactor include finding material (uranium 235) that will sustain a chain reaction, maintaining the reaction at a level that yields heat but does not escalate out of control and explode, and coping with the radiation produced by the chain reaction.

Radioactivity

Radioactivity is the spontaneous emission of energy and/or high-energy particles from the nucleus of an atom. One type of radioactivity is produced naturally and is emitted by radioactive isotopes (or radioisotopes), such as radioactive carbon (carbon 14) and radioactive hydrogen (H-3, or tritium). The energy and high-energy particles that radioactive isotopes emit include alpha rays, beta rays, and gamma rays.

Isotopes are atoms of an element that have the usual number of protons but different numbers of neutrons in their nuclei. For example, twelve protons and twelve neutrons comprise the nucleus of the element carbon. One isotope of carbon, C-14, has twelve protons and fourteen neutrons in its nucleus.

Radioisotopes (such as C-14) are unstable isotopes and their nuclei decay, or break apart, at a steady rate. Decaying radioisotopes produce other isotopes as they emit energy and/or high-energy particles. If the newly formed nuclei are radioactive as well, they emit radiation and change into other nuclei. The final products in this chain are stable, nonradioactive nuclei.

Radioisotopes reach our bodies daily, emitted from sources in outer space, and from rocks and soil on earth. Radioisotopes are also used in medicine and provide useful diagnostic tools. Figure 5.3 shows the sources of radiation.

FIGURE 5.3

As shown in Figure 5.3, radon is the largest source of radiation to which humans are exposed. This gas is formed in rocks and soil from the radioactive decay of radium. Most prevalent in the northern half of the United States, radon can enter cracks in basement walls and remain trapped there. Prolonged exposure to high levels of radioactive radon is thought to lead to lung cancer.

Decades after the discovery of radiation at the turn of the century by Antoine Henri Becquerel, Marie Curie, and Pierre Curie, other scientists determined that they could unleash energy by "artificially" breaking apart atomic nuclei. Such a process is called nuclear fission. Scientists learned that they could produce the most energy by bombarding the nuclei of an isotope of uranium called uranium 235 (U-235). The fission of U-235 releases several neutrons, which can then penetrate other U-235 nuclei. In this way the fission of a single U-235 atom could begin a cascading chain of nuclear reactions, as shown in Figure 5.4. If this series of reactions is regulated to occur slowly, as it is in nuclear power plants, the energy emitted can be captured for a variety of uses, such as generating electricity. If this series of reactions is allowed to occur all at once, as in a nuclear (atomic) bomb, the energy emitted is explosive. (Plutonium 239 can also be used to generate a chain reaction similar to that of U-235.)

Mining Nuclear Fuel

In the United States U-235, found in the form of ore, is used as nuclear fuel. The majority of uranium in the United States is found in two states: Wyoming and New Mexico. Ore that contains uranium is first located by geological methods such as drilling. Uranium-bearing ores are mined by methods similar to those used for other metal ores. However, uranium mining has the unique danger

FIGURE 5.4

of exposure to radioactivity. Uranium atoms split by themselves at a slow rate, causing radioactive substances such as radon to accumulate slowly in the deposits.

After it is mined, uranium must be concentrated, because uranium ore generally contains only 0.1% uranium metal by weight. To concentrate the uranium, it goes through a process called milling. The nuclear fuel cycle, which is shown in Figure 5.5, begins with the milling of uranium ore. In milling the ore is first crushed, and then various chemicals are poured slowly through the crushed ore to dis-solve out the uranium. The uranium is then precipitated from this chemical solution. The resulting material, called yellowcake because of its color, is 85% pure uranium by weight. But this uranium is 99.3% nonfissionable U-238 and only 0.7% fissionable U-235. Other processes result in enriched uranium, which is uranium that has a higher percentage of fissionable uranium than does yellowcake.

To produce enriched uranium, yellowcake is converted into uranium hexafluoride gas (UF6). This gas is loaded into cylinders, which are sent to a gaseous diffusion plant, shown in Figure 5.5, where uranium is made into reactor fuel (enriched). The enriched uranium is converted into oxide powder (UO2), which is made into fingertip-sized fuel pellets. The small pellets are less than one-half inch in diameter, but each one can produce as much energy as 120 gallons of oil. The pellets are stacked in tubes about twelve feet long, called rods. Many rods are bundled together in assemblies, and hundreds of these assemblies make up the core of a nuclear reactor.

DOMESTIC NUCLEAR ENERGY PRODUCTION

The percentage of U.S. electricity supplied by nuclear power grew considerably during the 1970s and 1980s before leveling off in the 1990s. In 1973 nuclear power supplied only 4.5% of the total electricity generated in the United States. By 2003 nuclear power's 19.8% share of electricity production was down only slightly from the 2001 all-time high of 20.6%. In 2002 nuclear power plant operations provided an all-time high of nuclear electricity net generation of 780.1 billion kilowatt-hours.

The increase in production of electricity in nuclear power plants was achieved largely through an increase in average capacity factor. The capacity factor is the proportion of electricity produced to what could have been produced at full-power operation. In 2002 the capacity factor was at an all-time high of 90.3%. In 2003 the capacity factor was 88.2%. Better training for operators, longer operating cycles between refueling, and control-system improvements contributed to increased plant performance.

In 2003 and 2004, 104 nuclear reactors were in operation (see Figure 5.6 and Figure 5.7) in thirty-one states. In 2003 these 104 reactors had a total net generation of 763.7 billion kilowatt-hours of energy. Most of these reactors

FIGURE 5.5

are located east of the Mississippi River, where the demand for electricity is high. The number of plants operating is lower than the 135 reactors that were either planned, in construction, or in operation in 1974.

Since 1978 no new nuclear power plants have been ordered, and many have closed. (See Table 5.1.) Several factors have contributed to the slowdown in U.S. nuclear reactor construction. Overall costs have increased as a result of more expensive financing, partly influenced by longer delays for licensing. Expenses have also increased because of regulations that were instituted as a result of the Three Mile Island incident. Operating costs have been higher than expected as well. Originally, it was projected that plants could run almost 90% of the time, with brief pauses for refueling, but for many years this was not the case.

OUTLOOK FOR DOMESTIC NUCLEAR ENERGY

In its Annual Energy Outlook 2004 (2004), the Energy Information Administration (EIA) predicted that the capacity of nuclear power plants will be maintained as they age through 2025. Thus, electricity generation by these plants is projected to increase slightly from 2002 to 2025, but its contribution to U.S. electricity production will decline as electricity generation by coal, natural gas, and renewables increases.

No nuclear units are projected to be retired between 2002 and 2025, nor are any new nuclear units expected to become operable during that time span because natural gas and coal-fired plants are projected to be more economical. However, the Nuclear Regulatory Commission (NRC) approved eighteen applications for power uprates for plants in 2002 and another nine were approved or pending as of 2003. (A power uprate is an increase in the power output of a nuclear power plant, which is accomplished by adding a more highly enriched uranium fuel to

FIGURE 5.6

the current fuel. The plant must be able to operate safely at the higher power level.)

INTERNATIONAL PRODUCTION

According to the Annual Energy Review 2003, in 2002 nuclear power provided about 17% of the world's electricity and 6.6% of total energy. Although the United States is the largest producer of nuclear power, it trails

FIGURE 5.7

other Western countries in the proportion of national electrical production generated by nuclear power. That is primarily because oil, natural gas, and coal have been more accessible in the United States than in other countries.

In 2002 the United States led the world in nuclear power generation with 780.1 billion kilowatt-hours, followed by France's 414.9 billion and Japan's 295.1 billion. (See Table 5.2.) These three countries together generated 58% of the world's nuclear electric power. France had by far the highest proportion (approximately 78%) of its electrical power produced by nuclear energy, followed by Belgium (59%), Sweden (46%), and Switzerland (41%). Japan produces 28% of its electricity by nuclear power generation, and the United States only 20%.

In its Information Digest 2004–2005, the Nuclear Regulatory Commission reported that as of December 31, 2003, there were 438 nuclear power plants in operation worldwide and fifty-four were under construction, on order, or had their construction halted, including eight in India, eight in South Korea, six in Russia, five in the Ukraine, five in Japan, and four in Romania.

Worldwide, the EIA projected in its International Energy Outlook 2004 that nuclear generating capacity will increase slightly overall, from 353 gigawatts in 2001 to 385 gigawatts in 2025. The increase will peak in 2015 with a generating capacity of 407 gigawatts. Totals for individual countries will increase for some and decrease for others. Some countries whose capacities are projected to increase from 2001 to 2025 are:

  • Canada, from ten gigawatts in 2001, increasing to fifteen gigawatts in 2020, and decreasing to twelve gigawatts in 2025

TABLE 5.1

Nuclear generating units, 1953–2003
Year Orders1 Cancelled orders2 Construction permits3 Low-power operating licenses4 Full-power operating licenses5 Shutdowns6 Operable units7
1Placement of an order by a utility or government agency for a nuclear steam supply system.
2Cancellation by utilities of ordered units. Includes WNP 1; the licensee intends to request that the construction permit be cancelled. Does not include three units (Bellefonte 1 and 2 and Watts Bar 2) where construction has been stopped indefinitely.
3Issuance by regulatory authority of a permit, or equivalent permission, to begin construction. Numbers reflect permits issued in a given year, not extant permits.
4Issuance by regulatory authority of license, or equivalent permission, to conduct testing but not to operate at full power.
5Issuance by regulatory authority of full-power operating license, or equivalent permission. Units generally did not begin immediate operation.
6Ceased operation permanently.
7Total of nuclear generating units holding full-power licenses, or equivalent permission to operate, at the end of the year. Although Browns Ferry 1 was shut down in 1985, the unit has remained fully licensed and thus has continued to be counted as operable during the shutdown; in May 2002, the Tennessee Valley Authority announced its intention to have the unit resume operation in 2007.
8Under new regulations beginning in 1997, the terms "Low-power operating licenses" and "Full-power operating licenses" are no longer applicable; while no new licenses have been granted under the new regulations, applications were made in 2003 for three "Early site permits."
— = Not applicable.
Web Page: For related information, see http://www.eia.doe.gov/fuelnuclear.html.
source: "Table 9.1. Nuclear Generating Units, 1953–2003," in Annual Energy Review 2003, U.S. Department of Energy, Energy Information Administration, Office of Energy Markets and End Use, September 7, 2004, http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf (accessed September 28, 2004)
19531000000
19540000000
19553010000
19561030000
19572011101
19584000001
19594031102
19601071103
19610000003
19622017609
196340132011
196400323113
196570100013
1966200512114
19672901433215
19681602300213
196990744017
19701401043020
1971210452022
1972387866127
1973420141215042
1974289231415255
1975413932057
197631977163
19774101544067
19782131334170
197906200169
1980015052071
198109034075
1982018064178
198306033081
198406076087
198502079096
1986020750101
1987000682107
1988030120109
1989000342111
1990010121112
1991000001111
1992000002109
1993000110110
1994010001109
1995020100109
1996000011109
199700008082107
1998000003104
1999000000104
2000000000104
2001000000104
2002000000104
2003000000104
Total 259 124 177 132 132 28

TABLE 5.2

World net nuclear electric power generation, 1980, 1990, and 2002
(Billion kilowatthours)
Nuclear electric power Total
Region and country 1980 1990 2002P 1980 1990 2002P
R = Revised.
P = Preliminary.
— = Not applicable.
(s) = Less than 0.05 billion kilowatthours.
Note: Totals may not equal sum of components due to independent rounding.
Web Page: For related information, see http://www.eia.doe.gov/international.
source: "Table 11.16. World Net Generation of Electricity by Type, 1980, 1990, and 2002 (Billion Kilowatthours)," in Annual Energy Review 2003, U.S. Department of Energy, Energy Information Administration, Office of Energy Markets and End Use, September 7, 2004, http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf (accessed September 28, 2004)
North America 287.0 648.9 860.3 2,721.6 3,623.9 4,592.7
Canada35.969.271.0367.9468.6548.9
Mexico0.02.89.363.6116.6203.6
United States251.1576.9780.12,289.63,038.03,839.3
Other0.00.00.00.50.70.9
Central and South America 2.2 9.0 19.2 308.2 R497.0 789.7
Argentina2.27.05.441.848.381.4
Brazil0.01.913.8138.3219.6339.0
Paraguay0.00.00.00.827.048.4
Venezuela0.00.00.032.057.687.0
Other0.00.00.095.3R144.5233.9
Western Europe 219.2 707.5 881.7 1,844.5 2,351.7 2,918.4
Belgium11.940.645.050.866.576.6
Finland6.618.321.238.751.871.6
France63.4298.4414.9250.8397.6528.6
Germany55.6145.1156.8469.9526.0548.3
Italy2.10.00.0176.4202.1261.6
Netherlands3.93.33.762.967.690.6
Norway0.00.00.082.9120.4125.9
Spain5.251.659.9109.2143.9229.0
Sweden25.364.865.494.3141.5142.8
Switzerland12.922.425.946.453.063.5
Turkey0.00.00.023.355.2123.3
United Kingdom32.358.783.6265.1295.2360.8
Other0.04.45.3173.8230.8295.9
Eastern Europe and former U.S.S.R 83.2 251.3 297.1 1,604.1 1,976.6 1,619.9
Czech Republic17.871.8
Kazakhstan0.055.4
Poland0.00.00.0114.7128.5133.8
Romania0.00.05.163.960.653.6
Russia134.1850.6
Ukraine73.4167.3
Other83.2251.366.71,425.61,787.5287.4
Middle East 0.0 0.0 0.0 92.4 228.9 490.0
Iran0.00.00.021.355.9129.0
Saudi Arabia0.00.00.020.564.9138.2
Other0.00.00.050.7108.1222.8
Africa 0.0 8.4 12.0 189.2 307.5 453.9
Egypt0.00.00.018.341.481.3
South Africa0.08.412.093.1156.0202.6
Other0.00.00.077.8110.1170.0
Asia and Oceania 92.7 279.9 489.3 1,280.5 R2,354.7 4,425.9
Australia0.00.00.087.7146.4210.3
China0.00.023.5285.5590.31,575.1
India3.05.617.8119.3275.5547.2
Indonesia0.00.00.013.546.599.3
Japan78.6192.2295.1549.1822.11,044.0
South Korea3.350.2113.134.6100.4287.6
Taiwan7.831.638.042.083.3158.5
Thailand0.00.00.013.643.7102.4
Other(s)0.41.8135.3R246.4401.4
World 684.4 1,905.0 2,559.6 8,040.5 R11,340.2 15,290.5
  • Japan, from forty-three gigawatts to fifty-seven gigawatts in 2020, and down to fifty-four gigawatts in 2025
  • China, from two gigawatts in 2001 to twenty-one gigawatts in 2025
  • India, from three to nine gigawatts
  • United States, from ninety-eight to 103 gigawatts
  • France, from sixty-three to seventy gigawatts

Some countries whose capacities are projected to decrease from 2001 to 2025 are:

  • Germany, from twenty-one to zero gigawatts
  • The United Kingdom, from twelve to four gigawatts

Some countries are planning to cut capacity radically or phase out nuclear power altogether. Sweden has legislated a nuclear phase-out by 2010 (although it is not clear that this is an attainable goal, since nearly half of Sweden's electricity comes from nuclear power). The Netherlands and Germany have strong conservation policies and well-organized antinuclear movements. The Netherlands is projected to phase out nuclear power by 2020 and Germany by 2025.

International Agreement on Safety

In September 1994 forty nations, including the United States, signed the International Convention on Nuclear Safety, an agreement that requires them to shut down nuclear power plants if necessary safety measures cannot be guaranteed. The agreement applies to land-based civil nuclear power plants and seeks to avert accidents like the 1986 explosion at Chernobyl in the former Soviet Union, the world's worst nuclear disaster to date. Ukraine, which inherited the Chernobyl plant after the collapse of the Soviet Union, signed the agreement. Signers must submit reports on atomic installations and, if necessary, make improvements to upgrade safety at the sites. Neighboring countries may call for an urgent study if they are concerned about a reactor's safety and the potential fallout that could affect their own population or crops.

POWER PLANT AGING

Like other types of power plants, nuclear power plants have a lifespan after which they must be retired because the cost of running them becomes too high. The generation of nuclear power plants currently operating was designed to last about thirty years. Some plants showed serious levels of deterioration after as few as fifteen years. However, some have lasted well beyond thirty-year expectations. Whenever a power plant—whether coal, natural gas, or nuclear—is retired, it must be demolished and cleaned up so that the site can be used again.

Decommissioning Nuclear Power Plants

Eventually, the more than 400 nuclear plants now operating worldwide will need to be retired. There are three methods of retiring, or decommissioning, a reactor: safe enclosure (mothballing), entombment, and immediate dismantling.

Safe enclosure involves removing the fuel from the plant, monitoring any radioactive contamination (which is usually very low or nonexistent), and guarding the structure to prevent anyone from entering until eventual dismantling and decontamination activities occur. Entombment, which was used at Chernobyl, involves permanently encasing the structure in a long-lived material such as concrete. This procedure allows the radioactive material to remain safely on-site but at one location. Immediate dismantling involves decontaminating and tearing down the facility within a few months or years. This process is initially more expensive than the other options but removes the long-term costs of monitoring both the structure and the radiation levels. It also frees the site for other uses, including even the construction of another nuclear power plant. Nuclear power officials are also seeking alternative uses for nuclear shells, including the conversion of old nuclear plants to gas-fired plants.

Paying for the closing, decontamination, or dismantling of nuclear plants has become an issue of intense public debate. The early closing of several plants owing to safety concerns and poor economic performance has raised the question of how the costs of decommissioning can be covered. Industry reports contend that the cost of decommissioning retired plants and handling radioactive wastes will continue to escalate, causing serious financial problems for electric utilities. In addition to coal plants, new technologies, such as wind turbines and geothermal energy, are less expensive than nuclear energy plants when all factors are considered.

A NEW GENERATION OF NUCLEAR PLANTS?

In January 2000 the United States entered into a collaboration with international partners on nuclear energy. Formally chartered in 2001, the Generation IV International Forum (GIF) is a group of leading nuclear nations that agree that nuclear energy is important to future world energy security and economic prosperity. These countries are dedicated to joint development of the "next generation" of nuclear energy systems. Members of GIF are the United States, Argentina, Brazil, Canada, France, Japan, the Republic of Korea, South Africa, Switzerland, and the United Kingdom.

The GIF countries have selected six nuclear power technologies to develop for the future. These "Generation IV" nuclear energy systems would follow the three other periods of nuclear reactor development: (a) Generation I experimental reactors developed in the 1950s and 1960s; (b) Generation II large, central-station nuclear power reactors, such as the 104 plants still operating in the United States, built in the 1970s and 1980s; and (c) Generation III advanced light-water reactors built in the 1990s, primarily in East Asia, to meet that region's expanding electricity needs.

In 2003 GIF examined more than one hundred reactor concepts and identified nineteen as potentially viable. One new concept, the advanced high-temperature reactor (AHTR), may reduce electricity production costs and may be able to produce hydrogen. GIF research and development began in 2004.

NUCLEAR SAFETY PROBLEMS

Problems have plagued the nuclear industry almost from the beginning. Some plant-site selections have been considered questionable, especially those near earthquake fault lines. Several major accidents have occurred worldwide since the late 1970s.

In the United States

three mile island. On March 28, 1979, the Three Mile Island nuclear facility near Harrisburg, Pennsylvania, was the site of the worst nuclear accident in American history. Information released several years after the accident revealed that the plant came much closer to meltdown than either the NRC or the industry had previously indicated. Temperatures inside the reactor were first said to have been 3,500 degrees Fahrenheit but are now known to have reached at least 4,800 degrees. The temperature needed to melt uranium dioxide fuel is 5,080 degrees Fahrenheit. When meltdown occurs, an uncontrolled explosion may result, unlike the controlled nuclear reaction of normal operation.

The emergency core cooling system at Three Mile Island was designed to dump water on the hot core and spray water into the reactor building to stop the production of steam. During the accident, however, the valves leading to the emergency water pumps closed. Another valve was stuck in the open position, drawing water away from the core, which then became partially uncovered and began to melt. The emergency core cooling system then began drawing water out of the basement supply and reusing it, contaminating the reactor pump, although limiting the radiation contamination to the interior of the building.

Although safety systems at the Three Mile Island facility performed well and the radiation leak was relatively small, the Three Mile incident was sensationalized in the media. Antinuclear proponents urged residents to evacuate, adding to stress levels and panic. In the end this nuclear accident resulted in no deaths or injuries to plant workers or members of the nearby community. On average, area residents were exposed to less radiation than that of a chest X-ray. Nevertheless, the Three Mile Island incident raised concerns about nuclear safety, which resulted in safety enhancements in the nuclear power industry and at the NRC. Antinuclear sentiment was fueled as well, heightening Americans' criticism of nuclear power as an energy source.

The nuclear reactor in Unit 2 at Three Mile Island has been in monitored storage since it underwent cleanup. Operation of the reactor in Unit 1 resumed in 1985.

peach bottom. In 1987 the NRC shut down the Peach Bottom nuclear plant in Delta, Pennsylvania, because control-room operators were found sleeping on duty. This was the first plant shut-down solely because of operator violations and misconduct.

In the Former Soviet Union

chernobyl. On April 26, 1986, the most serious nuclear accident ever occurred at Chernobyl, a four-reactor nuclear plant complex located in the former Soviet Union (now Ukraine) near Kiev. At least thirty-one people died and hundreds were injured when one of the four reactors exploded during a badly-run test of the reactor. Everyone in the vicinity was exposed to radiation, and radioactive particles were released into the atmosphere. About 500 people were hospitalized, and medical experts estimate that 6,000 to 24,000 cancer-related deaths have occurred over the intervening years as a result of the released radiation.

The cleanup was one of the biggest projects of its kind ever undertaken. Helicopters dropped 5,000 tons of limestone, sand, clay, lead, and boron on the smoldering reactor to stop the radiation leakage and reduce the heat. Workers built a giant steel and cement sarcophagus (stone coffin) to enshrine the remains of the reactor and contain the radioactive waste. Approximately 135,000 people were evacuated from a 300-square-mile area around the power station. Topsoil had to be removed in a nineteen-mile area and buried as nuclear waste. Buildings were washed down and the newly contaminated water and soil were carted away and buried. Agricultural products from areas nearby were declared unmarketable throughout Europe. Many of the 600,000 people involved in the immediate cleanup have suffered long-term effects of radiation exposure.

Some people at Chernobyl received 400 rems of radiation immediately following the explosion. (A rem is a standard measure of the whole-body dose of radiation. Under normal conditions, a person receives about one-tenth of a rem annually.) With a dose of twenty-five rems, a person's blood begins to change. The DNA is damaged, preventing the bone marrow from producing red and white blood cells. Sickness starts at 100 rems and severe sickness at 200 rems. Death of half the population occurs at 400 rems, and death within a week can be expected for anyone exposed to 600 rems. One estimate is that 17.5 million people, including 2.5 million children under seven years old, have had some significant exposure to radiation from Chernobyl.

In 1995 the United Nations reported that the prevalence of illnesses of all kinds was 30% above normal in the Ukraine; incidences of depression, alcoholism, and divorce were on the rise. Although the Chernobyl reactor is in the Ukraine, the neighboring nation of Belarus (with a population of 10 million people) suffered more human and ecological damage from fallout because of the prevailing winds. Thyroid cancers were 285 times pre-Chernobyl levels in Belarus in 1995, especially among children. Belarus's cabinet minister claimed at that time that a quarter of his country's national income was being spent on alleviating the effects of the disaster. As many as 375,000 people in Belarus, Ukraine, and Russia were displaced because of the accident. Contaminated forests spread radioactivity through fires, and seepage from the reactor has polluted waterways as far away as the Black Sea, some 350 miles away.

In April 1996 a fire in the woods near the Chernobyl reactor once more alarmed observers, who feared further danger to the entombed reactor and the release of radioactivity from soils and vegetation in the area. In addition, the sarcophagus built to contain the damaged reactor is reported to be crumbling. However, the Ukraine, which suffers from 40% unemployment and other enormous economic woes, claims it needs the power from the remaining reactor and that completely shutting down Chernobyl would cost too much.

Some high-technology companies have developed robots to clean up hazardous sites such as Chernobyl. Such efforts would, however, produce yet another problem: what to do with the radioactive waste once the Chernobyl sarcophagus is entered and cleaned up.

TYPES OF RADIOACTIVE WASTE

Working in a laboratory in Chicago, Illinois, in 1942, Italian physicist Enrico Fermi assembled enough uranium to cause a nuclear fission reaction. His discovery transformed both warfare and energy production, but the experiment also produced a small packet of radioactive waste materials that will remain dangerous for hundreds of thousands of years. That "first" radioactive waste lies buried under a foot of concrete and two feet of dirt on a hillside in Illinois.

Radioactive waste material is produced at all stages of the nuclear fuel cycle, from the initial mining of the uranium to the final disposal of the spent fuel from the reactor. (See Figure 5.5.) "Radioactive waste" is a term that encompasses a broad range of material with widely varying characteristics. Some is barely radioactive and safe to handle, while other types are intensely hot in terms of both temperature and radioactivity. Some waste decays to safe levels of radioactivity in a matter of days or weeks, while other types will remain dangerous for thousands of years. The U.S. Department of Energy (DOE) and the NRC define the major types of radioactive waste.

Uranium Mill Tailings

Uranium mill tailings are sand-like wastes produced in uranium refining operations. Although they emit low levels of radiation, their large volumes (10–15 million tons annually) pose a hazard, particularly from radon emissions and groundwater contamination. Since it was not until the early 1970s that the dangers of uranium mill tailings were realized, many miners and residents in the western United States had unsafe exposure to them. Cancer incidences are high among miners who worked prior to the 1970s.

Low-level Waste

Low-level waste, which contains varying lesser levels of radioactivity, includes trash (such as wiping rags, swabs, and syringes), contaminated clothing (such as shoe covers and protective gloves), and hardware (such as luminous dials, filters, and tools). This waste comes from nuclear reactors, industrial users, government users (but not nuclear weapons sites), research universities, and medical facilities. In general, low-level waste decays relatively quickly (in ten to one hundred years).

High-level Waste

Spent nuclear fuel (used reactor fuel) is high-level radioactive waste. Uranium fuel can be used for twelve to eighteen months, and then it is no longer as efficient in splitting its atoms and producing heat, which ultimately is used to generate electricity. Therefore, it must be removed from the reactor and replaced with fresh fuel. Some of the spent fuel is reprocessed to recover the usable uranium and plutonium, but the radioactive material that remains is dangerous for thousands of years.

Transuranic (TRU) Wastes

Transuranic (TRU) wastes are eleven human-made radioactive elements with atomic numbers greater than that of uranium (ninety-two) and therefore beyond ("trans-") uranium ("-uranic") on the periodic chart of the elements. Their half-lives—the time it takes for half the radioisotopes present in a sample to decay to nonradioactive elements—are thousands of years. They are found in trash produced mainly by nuclear weapons plants and are therefore part of the nuclear waste problem but not directly the concern of nuclear power utilities.

Mixed Waste

Mixed waste is high-level, low-level, or TRU waste that also contains hazardous nonradioactive waste. Such waste poses serious institutional problems, because the radioactive portion is regulated by the DOE or NRC under the Atomic Energy Act (AEA; PL 83–703), while the Environmental Protection Agency regulates the nonradioactive elements under the Resource Conservation and Recovery Act (RCRA; PL 95–510).

RADIOACTIVE WASTE DISPOSAL

Disposing of radioactive waste is unquestionably one of the major problems associated with the development of nuclear power; radioactive waste is also a by-product of nuclear weapons plants, hospitals, and scientific research. Although federal policy is based on the assumption that radioactive waste can be disposed of safely, new storage and disposal facilities for all types of radioactive waste have frequently been delayed or blocked by concerns about safety, health, and the environment.

The highly toxic wastes must be isolated from the environment until the radioactivity decays to a safe level. In the case of plutonium, for example, the half-life is 26,000 years. At that rate, it will take at least 100,000 years before radioactive plutonium is no longer dangerous. Any facilities built to store such materials must last at least that long.

Regulation of Radioactive Waste Disposal

The Nuclear Regulatory Commission, other federal agencies, and the states regulate radioactive materials. As of 2004, the NRC had entered into agreements regarding radioactive waste with 33 states, which are called Agreement States. These states, under their agreements with the NRC, regulate the management, storage, and disposal of certain nuclear waste within their states.

Disposal of Uranium Mill Tailings

Mill tailings are usually deposited in large piles next to the mill that processed the ore. In 1978 Congress passed the Uranium Mill Tailing Radiation Control Act (PL95–604). This law requires mill owners to follow Environmental Protection Agency (EPA) standards for cleanup of uranium and thorium after milling operations have permanently closed. They must cover the mill tailings to control the release of radon gas; the cover must effectively control radon releases for 1,000 years. Figure 5.8 shows the locations of uranium mill tailings disposal sites. The sites are located in the western United States because deposits of uranium ore are more plentiful there.

Disposal of Low-level Waste

Low-level waste is classified according to its potential hazards. Commercial sites that dispose of these wastes must be licensed by either the NRC or Agreement States. In 2004 three low-level waste facilities were operational in the United States. These facilities accept a broad range of low-level radioactive waste and are located in Barnwell, South Carolina, and Richland, Washington. In addition, Envirocare of Utah accepts large amounts of mill tailings and low-level waste, such as contaminated soil or debris from demolished buildings and from facilities that have shut down. Four low-level radioactive waste facilities have been closed: West Valley, New York (closed 1975); More-head/Maxey

FIGURE 5.8

Flats, Kentucky (closed 1977); Sheffield, Illinois (closed 1978); and Beatty, Nevada (closed 1993).

The design of a low-level waste facility is shown in Figure 5.9. Wastes are buried in shallow underground sites in the specially designed canisters in which they are shipped as shown in the diagram. Underground storage may or may not include protection by concrete vaults.

The Low-level Radioactive Waste Policy Amendments Act of 1985 (PL 99–240) encouraged states to enter into compacts, which are legal agreements among states for low-level radioactive waste disposal. Figure 5.10 shows these compacts. Although each compact is responsible for the development of disposal capacity for the low-level waste generated within the compact, new disposal sites have yet to be built. As Figure 5.10 shows, two of the three operational low-level sites are located in the Northwest Compact and one is in the Southeast Compact. Facilities located in compacts with no current low-level waste disposal sites must petition the compact to export their low-level radioactive waste to one of the three operating disposal sites.

Disposal of High-level Waste

A major step toward shifting the responsibility for disposal of high-level radioactive wastes (spent fuel) from the nuclear power industry to the federal government was taken in 1982, when Congress passed the Nuclear Waste Policy Act (PL 97–425). It provided the first comprehensive national policy and detailed timetable for the management

FIGURE 5.9

and disposal of high-level nuclear waste and authorized construction of the first high-level nuclear waste repository. A 1987 amendment to the Nuclear Waste Policy Act directed investigation of Yucca Mountain in Nevada as a potential site. In 2004 no long-term, high-level permanent waste disposal repository for spent fuel existed. While

FIGURE 5.10

waiting for the development of the Yucca Mountain site, spent fuel was being stored at away-from-reactor storage facilities, such as the General Electric Company facility in Morris, Illinois, or at the nuclear power plants that generated the waste. (See Figure 5.7 for the locations of operating nuclear reactors in the United States.)

On July 9, 2002, the U.S. Senate joined the U.S. House of Representatives in approving the Yucca Mountain site. The State of Nevada, however, challenged the constitutionality of this resolution. Nevertheless, in 2004, federal courts dismissed all challenges to the site selection of Yucca Mountain but did call into question the legality of the 10,000-year standard for the facility set by the Environmental Protection Agency because the EPA did not accept the National Academy of Sciences recommendation of a higher standard of perhaps 300,000 years. While the agency works on a new standard, Congress could decide to allow the old one to stay in place. Congress approved $2 million for the state's work on the project and $8 million for local governments for fiscal year 2005, an increase from the state's $1 million and local government's $4 million received for fiscal year 2004. The DOE must still submit its license application for the proposed Yucca Mountain nuclear repository. It will take about five years to construct the facility, which is already more than a decade behind schedule.

Figure 5.11 shows the location of the proposed radioactive waste disposal facility at Yucca Mountain. The proposed repository would look like a large mining complex. It would have facilities on the surface for handling and packaging nuclear waste and a large mine about 1,000 feet underground. Here, plans call for the waste to be placed in sealed metal canisters arranged vertically in the floor of underground tunnels. Above-ground facilities would cover approximately 400 acres and be surrounded by a three-mile buffer zone. Underground, about 1,400 acres would be mined, consisting of tunnels leading to the areas where waste containers would be placed and service areas near the shafts and ramps that provide access from the surface. This type of "deep geologic" disposal is widely considered by governments, scientists, and engineers to be the best option for isolating highly radioactive waste.

The repository would be designed to contain radioactive material by using layers of human-made and natural barriers. Regulations require that a repository isolate waste until the radiation decays to a level that is about the same as that from a natural underground uranium deposit. This decay time was originally estimated at be about 10,000 years, but the National Academy of Sciences has more recently recommended a higher standard of about 300,000 years.

After the repository has been filled to capacity, regulations require the DOE to keep the facility open and to monitor it for at least fifty years from the fill date. This will allow experts to monitor conditions inside the repository and retrieve spent fuel if necessary. Eventually, the repository shafts will be filled with rock and earth and sealed. At the ground level, facilities will be removed, and, as much as possible, the DOE will take steps to return the site to its original condition.

Scientists assume that over thousands of years, some of the human-made barriers in a repository will break down. Once that happens, natural barriers will be counted on to stop or slow the movement of radiation particles. The most

FIGURE 5.11

TABLE 5.3

Total commercial spent nuclear fuel discharges, 1968–2002
Number of assemblies
Reactor type Stored at reactor sites Stored at away-from-reactor facilities Total
MTU = Metric tonnes of uranium.
Notes: A number of assemblies discharged prior to 1972, which were reprocessed, are not included in this table (no data is available for assemblies reprocessed before 1972). Totals may not equal sum of components because of independent rounding.
source: "Table 1. Total U.S. Commercial Spent Nuclear Fuel Discharges, 1968–2002," in Energy Information Administration Spent Nuclear Fuel Data, Detailed United States as of December 31, 2002, U.S. Department of Energy, Energy Information Administration, October 1, 2004, http://www.eia.doe.gov/cneafr/nuclear/spent_fuel/ussnfdata.html (accessed November 18, 2004)
Boiling-water reactor90,3982,95793,355
Pressurized-water reactor69,80049170,291
High-temperature gas cooled reactor1,4647442,208
Total 161,662 4,192 165,854
Metric tonnes of uranium (MTU)
Boiling-water reactor16,153.6055416,707.60
Pressurized-water reactor30,099.00192.630,291.60
High-temperature gas cooled reactor15.48.824.2
Total 46,268.00 755.4 47,023.40

likely way for particles to reach humans and the environment would be through water, which is why the low water tables at Yucca Mountain are so crucial. Yucca Mountain also has certain chemical properties that act as another barrier to the movement of radioactive particles. Minerals in the rock called zeolites would stick to the particles and slow their movement throughout the environment.

The long delay in providing disposal sites for spent nuclear fuel, coupled with the accelerated pace at which nuclear plants are being retired, has created a crisis in the industry. Several aging plants are being maintained at a cost of $20 million a year for each reactor simply because there is no place to send the waste once the plants are decommissioned. Table 5.3 shows that as of 2002 more than 47,000 metric tons of nuclear uranium waste were sitting in spent fuel pools at the 104 operating and nineteen permanently closed nuclear power plants. When a nuclear plant shuts down, the nuclear waste and the radioactive equipment stay on the premises because there is no place to put them. As a result, every nuclear power plant in the United States has become a temporary nuclear waste disposal site. Plants that close must wait until a repository opens to be decommissioned or dismantled.

Disposal of Transuranic Waste

The first disposal facility licensed to dispose of transuranic waste opened on March 26, 1999. The Waste Isolation Pilot Plant (WIPP) is located in the desert in southeastern New Mexico. WIPP facilities include disposal rooms mined 2,150 feet underground in a 2,000-foot-thick salt formation that has been stable for more than 200 million years.

Disposal of Mixed Waste

As mentioned previously, mixed waste is jointly regulated by the Environmental Protection Agency, which regulates the hazardous waste component of mixed waste, and the Nuclear Regulatory Commission and the Department of Energy, which regulate the radioactive component of mixed waste. There are a variety of commercial facilities in the United States, including Envirocare (see "Disposal of Low-level Waste"), that accept mixed waste.

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Nuclear Power

Nuclear power


When nuclear reactions were first discovered in the 1930s, many scientists doubted they would ever have any practical application. But the successful initiation of the first controlled reaction at the University of Chicago in 1942 quickly changed their views.

In the first controlled nuclear reaction, scientists discovered a source of energy greater than anyone had previously imagined possible. They discovered that the nuclei of uranium isotopes could be split, thus releasing tremendous energy. The reaction occurred when the nuclei of certain isotopes of uranium were struck and split by neutrons. This is now known as nuclear fission , and the fission reaction results in the formation of three types of products: energy, neutrons, and smaller nuclei about half the size of the original uranium nucleus.

Neutrons are actually produced in a fission reaction, and this fact is critical for energy production. The release of neutrons in a fission reaction means that the particles required to initiate fission are also a product of the reaction. Once initiated in a block of uranium, fission occurs over and over again, in a chain reaction . Calculations done during these early discoveries showed that the amount of energy released in each fission reaction is many times greater than that released by the chemical reactions that occur during a conventional chemical explosion.

The possibility to release such high energies with nuclear reactions was used in the development of the atomic bomb. After the dropping of this bomb brought World War II to an end, scientists began researching the harnessing of nuclear energy for other applications, primarily the generation of electricity. In developing the first nuclear weapons , scientists only needed to find a way to initiate nuclear fissionthere was no need to control it once it had begun. In developing the peacetime application of nuclear power however, the primary challenge was to develop a mechanism for keeping the reaction under control once it had begun so that the energy released could be managed and used. This is the main purpose of nuclear power plantscontrolling and converting the energy produced by nuclear reactions.

There are many types of nuclear power plants , but all plants have a reactor core and every core consists of three elements. First, the fuel rods; these are long, narrow, cylindrical tubes that hold small pellets of some fissionable material. At present only two such materials are in practical use, uranium-235 and plutonium-239. The uranium used for nuclear fission is known as enriched uranium, because it is actually a mixture of uranium-235 with uranium-238. Uranium-238 is not fissile and the required chain reaction will not occur if the fraction of uranium-235 present is not at least 3%.

The second component of a reactor core is the moderator. Only slow-moving neutrons are capable of initiating nuclear fission, but the neutrons produced as a result of nuclear fission are fast-moving. These neutrons move too fast to initiate other reactions, thus moderators are used to slow them down. Two of the most common moderators are graphite (pure carbon ) and water.

The third component of a reactor core is the control rods. In operating a nuclear power plant safely and efficiently, it is of the utmost importance to have exactly the right amount of neutrons in the reactor core. If there are too few, the chain reaction comes to an end and energy ceases to be produced. If there are too many, fission occurs too quickly, too much energy is released all at once, and the rate of reaction increases until it can no longer be controlled or contained. Control rods decrease the number of neutrons in the core because they are made of a material that has a strong tendency to absorb neutrons. Cadmium and boron are materials that are both commonly used. The rods are mounted on pulleys allowing them to be raised or lowered into the reactor core as need may be. When the rods are fully inserted, most of the neutrons in the core are absorbed and relatively few are available to initiate a chain reaction. As the rods are withdrawn from the core, more and more neutrons are available to initiate fission reactions. The reactions reach a point where the number of neutrons produced in the core is almost exactly equal to the number being used to start fission reactions, and it is then that a controlled chain reaction occurs.

The heat energy produced in a reactor core is used to boil water and make steam, which is then used to operate a turbine and generate electricity. The various types of nuclear power plants differ primarily in the way in which heat from the core is used to do this. The most direct approach is to surround the core with a huge tank of water, some of which can be boiled directly by heat from the core. One problem with boiling-water reactors is that the steam produced can be contaminated with radioactive materials. Special precautions must be taken with these reactors to prevent contaminated steam from being released into the environment . A second type of nuclear reactor makes use of a heat exchanger. Water around the reactor core is heated and pumped to a heat exchange unit, where this water is used to boil water in an external system. The steam produced in this exchange is then used to operate the turbine and generator.

There is also a type of nuclear reactor known as a breeder, or fast-spectrum reactor because it not only produces energy but also generates more fuel in the form of plutonium-239. In conventional reactors, water is used as a coolant as well as a moderator, but in breeder reactors the coolant used is sodium. Neutrons have to be moving quickly to produce plutonium , and sodium does not moderate their speed as much as water does. Another design, the CANDU reactor, (acronym for CANada Deuterium Uranium) uses deuterium oxide (heavy water) as moderator and natural uranium as fuel. With the uranium fuel surrounded by heavy water, chain reaction fission takes place, releasing energy in the form of heat. The heat is transferred to a second heavy water system pumped at high pressure through the tubes to steam generators, from which the heat is transferred to ordinary water which boils to become the steam that drives the turbine generator.

Nuclear power plants could never explode with the power of an atomic bomb, because the quantity of uranium-235 required is never present in the reactor core. However, they do pose a number of well-known safety hazards. From the very beginning of the development of nuclear reactors, safety was an important consideration as scientists and engineers tried to anticipate the dangers associated with nuclear reactions and radioactive materials. Thus, control rods were developed to prevent the fission reactions from generating too much heat. The reactor and its cooling system are always enclosed in a containment shell made of thick sheets of steel to prevent the escape of radioactive materials. Nuclear power plants are highly complex facilities, with back-up systems for increased safety which are themselves supported by other back-up systems. But the components of these systems age, and human errors can and do occur; safety measures do not always function the way there were designed.

On December 2, 1957, the first nuclear power plant opened in Shippingport, Pennsylvania, and to many the nuclear age seemed to have begun. Over the next two decades, more than 50 plants were commissioned, with dozens more ordered. But safety problems plagued the industry. An experimental reactor in Idaho Falls, Idaho, had already experienced a partial meltdown as a result of operator error in 1955. In October 1957, just months before the Shippingport plant came on line, a production reactor near Liverpool, England, caught fire, releasing radiation over Great Britain and northern Europe.

The most critical event in the history of nuclear power in the United States was the accident at the Three Mile Island nuclear reactor near Harrisburg, Pennsylvania. In March 1979, fission reactions in the reactor core went out of control, generating huge amounts of heat, and a meltdown resulted. Fuel rods and the control rods were melted; the cooling water was turned to steam and the containment structure itself was threatened. No new plants have been ordered in the United States since this accident, and 65 plants on order at that time were cancelled. The explosion at the Chernobyl reactor near Kiev, Ukraine, dealt a second blow to the industry.

Even without these accidents, another problem with nuclear power would remain. This is the problem of spent radioactive wastes. About a third of the 10 million fuel pellets used in any reactor core must be removed each year because they have been so contaminated with fission by-products that they no longer function efficiently. These highly radioactive pellets must be disposed of in a safe fashion, but 50 years after the first controlled reaction, no method has yet been discovered to address this issue. Today, these wastes are most commonly stored on a temporary basis at or near the power plant itself. Many have argued that further development of nuclear power should not even be considered until better methods for radioactive waste management have been developed.

The International Nuclear Safety Center (INSC), which operates under the guidance of the Director of International Nuclear Safety and Cooperation in the U.S. Department of Energy (DOE), has the mission of improving nuclear power reactor safety worldwide. The INSC is dedicated to developing improved nuclear safety technology and promoting the open exchange of nuclear safety information among nations, sponsoring scientific research activities as collaborations between the U.S. and its international partners. Safety issues are addressed at several levels, including: risk assessment , containment, structural integrity of reactors, assessment of their seismic reliability, equipment operability, fire protection, and reactor safeguards.

The security of nuclear facilities has also been a point of growing concern. In 1991, the NRC instituted an Operational Safeguards Response Evaluation (OSRE) program, which evaluated the ability of nuclear facility security personnel to withstand a staged commando-style attack by intruders. Unfortunately, six of the 11 evaluations performed in 2000 and 2001 resulted in the "attackers" being able to penetrate security and simulate damage to reactor equipment.

In the post-September 11 terrorist attack environment, the vulnerability of America's 104 nuclear power facilities are a critical national security concern. All nuclear facilities were placed on high alert immediately following the attacks, and in early 2002 the Nuclear Regulatory Commission (NRC) issued interim confidential security orders for all licensees to comply with. In addition, decommissioned nuclear plants and spent fuel storage facilities were also required to implement the security orders. The NRC also conducted a thorough review of its Internet web site, taking the site offline temporarily to analyze content and remove all documents deemed sensitive to national security. In April 2002, the NRC announced the establishment of a dedicated department for plant security, the Office of Nuclear Security and Incident Response.

The future role of nuclear power in energy production throughout the world is uncertain. But the current absence of nuclear power plant development in the United States should not be taken as indicative of future trends, as well as trends in the rest of world. France, for example, obtains more than half of its electricity from nuclear power, despite the safety problems. And many believe that nuclear power should be an important part of energy production in the United States as well. Proponents of nuclear power argue that its dangers have been greatly exaggerated in this country. The risks, they argue, must be compared with the health and environmental hazards of other fuels, particularly fossil fuels .

In 1999, the U.S. Department of Energy announced a new initiative called Generation IV. Designed to generate interest and scientific research in nuclear power advances, the program set out the following goals for the next generation (i.e., generation IV) of nuclear power plants: 1) highly economical; 2) enhanced safety; 3) sustainable with minimal waste; and 4) commercially viable by 2025. Ten countries, including the United States, United Kingdom, Canada, South Africa, and Japan, were participating in the Generation IV International Forum (GIF) as of early 2002. One of the most promising prototypes reactor designers have come up with is the gas-cooled pebble-bed reactor, which uses a non-reactive helium coolant and operates more efficiently and at less cost than current water-cooled systems.

For some, hope for the future of nuclear power rests with the development of nuclear fusion . A nuclear power plant based on a fusion reaction would amount to a controlled version of a hydrogen bomb, just as conventional nuclear plants are equivalent to a controlled version of an atomic bomb. But the problem of managing the reaction is far more difficult with fusion than it is with fission, and scientists have been working on this issue unsuccessfully for more than 40 years. Some believe that a fusion power plant could become a reality in the next century, but many now doubt that such a plant will ever be feasible.

[David E. Newton and Paula Anne Ford-Martin ]


RESOURCES

BOOKS

Cheney, Glenn A. Journey to Chernobyl: Encounters in a Radioactive Zone. Chicago: Academy Chicago Pub, 1995.

Garwin, Richard L. and Georges Charpak. Megawatts and Megatons: A Turning Point in the Nuclear Age. New York: Knopf, 2001.

Hodgson, Peter. Nuclear Power, Energy, and the Environment. London: World Scientific Publishing, 1999.

Wilpert, Bernard, et al., eds. Safety Culture in Nuclear Power Organizations. London: Taylor & Francis, 2001.

PERIODICALS

Lake, James et al. "Next-Generation Nuclear Power." Scientific American 286, no. 1 (January 2002): 72(8).

OTHER

Union of Concerned Scientists. Briefing: Nuclear Reactor Security. [cited July 2002]. <http://www.ucsusa.org/energy/br_safenplants.html>.

U.S. Department of Energy, Office of Nuclear Energy, Science, and Technology. Generation IV: The Future of Nuclear Power. [cited July 2002]. <http://gen-iv.ne.doe.gov>.

ORGANIZATIONS

Sandia National Laboratories: Energy and Critical Infrastructure, PO Box 5800, Albuquerque, NM USA 87185 (505) 284-5200, <http://www.sandia.gov>.


U.S. Nuclear Regulatory Commission, Office of Public Affairs (OPA), Washington, DC USA 20555 (301) 415-8200, Toll Free: (800) 368-5642, Email: [email protected], <http://http://www.nrc.gov>.

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Nuclear Power

Nuclear Power

The nuclear power plant

Types of nuclear power plant

Safety concerns

Nuclear waste management

History

Nuclear fusion

The future of nuclear power

Resources

Nuclear power is any method of doing work that makes use of nuclear fission or nuclear fusion reactions. In its broadest sense, the term refers to both the uncontrolled release of nuclear energy, as in fission or fusion weapons, and to the controlled release of energy, as in nuclear power plants. Most commonly, however, the expression nuclear power is reserved for the latter. Approximately 430 nuclear reactors devoted to the manufacture of electricity are operating worldwide.

The worlds first exposure to nuclear power came with the detonation of two fission (atomic) bombs over the Japanese cities of Hiroshima and Nagasaki in 1945, events that coincided with the end of World War II. (It has long been assumed by many historians and members of the general public that these atomic bombings were necessary to produce a Japanese surrender and to forestall a United States invasion of Japan; this belief has been disputed by some historians in recent years.) A number of scientists and laypersons perceived an optimistic aspect of these terrible events; they hoped that the power of nuclear energy could be harnessed for human good. Those hopes have been realized, but to only a modest degree. Starting in the 1970s, intense political opposition to nuclear power arose in many nations, including the U.S. Some technical problems associated with the use of nuclear power have never been satisfactorily solved, although proponents of this technology argue that none are insurmountable. After three decades of progress in the development of controlled nuclear power, interest in this energy source has leveled off and, in many nations, declined. Indeed, strong popular opposition to nuclear power exists in many countries today, and nuclear power has become a locus of political struggle, with citizens groups (supported by some scientists) ranged, typically, against industry and government experts. Nuclear advocates see nuclear opponents as irrationally fearing nuclear technology; nuclear opponents see nuclear advocates as irresponsibly advocating use of unreliable nuclear technology. The nuclearpower issue remains a highly contentious one in many nations.

The nuclear power plant

A nuclear power plant is a system in which some of the energy released by nuclear fission is used to generate electricity. Every such plant contains four fundamental elements: reactor, coolant system, electricalpower generating unit, and safety system.

The source of energy in a nuclear reactor is a fission reaction in which neutrons collide with nuclei of uranium235 or plutonium239 (the fuel), causing them to split apart. The products of a fission reaction include not only energy but also new elements (known as fission products) and free neutrons. A constant and reliable flow of neutrons is insured in the reactor by a moderator, which slows down the speed of neutrons, and by control rods, which limit the number of neutrons available in the reactor and, hence, the rate at which fission can occur. In a nuclear weapon, the fission chain reaction, once triggered, proceeds at an exponentially increasing rate, resulting in an explosion; in a nuclear reactor, it proceeds at a steady, controlled rate. Most commercial nuclear power plants are incapable of undergoing an explosive nuclear chain reaction, even should their safety systems fail; this is not true of all research reactors (e.g., some breeder reactors).

Energy produced in the reactor is carried away by means of a coolant such as pressurized water, liquid sodium, or carbon dioxide gas. The circulating coolant absorbs heat in the reactor; once outside the reactor, it is allowed to boil or the heat it contains is used to boil water in a secondary loop. Steam produced in either of these ways is then piped into the electrical generating unit, where it turns the blades of a turbine. The turbine, in turn, turns a generator that produces electrical energy.

The high cost of constructing a modern nuclear power plantthree to four billion dollars, in the U.S.reflects in part the wide range of safety features needed to protect against various possible mishaps, especially those which could release to the environment any of the plants inventory of radioactive substances. (Small specialpurpose reactors, such as those used to power nuclear submarines or aircraft carriers, have different costs and technical features from the large, landbased reactors used to supply electrical grids.) Some of those features are incorporated into the reactor core itself. For example, all of the fuel in a reactor is sealed in a protective coating made of a zirconium alloy. The protective coating, called a cladding, helps retain heat and radioactivity within the fuel, preventing it from escaping into the plant itself.

Every nuclear plant is also required to have an elaborate safety system to protect against the most serious potential problem of all, loss of coolant. If such an accident were to occur, the reactor core might melt itself down, possibly breaching the structures which contain it and releasing radioactive materials to the rest of the plant and, perhaps, to the outside environment. To prevent such an accident, the pipes carrying the coolant to and from the reactor are required to be very thick and strong. In addition, backup supplies of the coolant must be available to replace losses in case of a leak.

On another level, the whole plant itself (in much of the world, including Europe and the U.S.) is required to be encased within a domeshaped containment structure made of steelreinforced concrete several feet thick. The containment structure is designed to prevent the release of radioactive materials in case of an accident within the reactor. The containment also serves against as a barrier against efforts to deliberately damage the reactor from outside, as by firing shoulderlaunched missiles at the reactor or crashing a hijacked airplane into it.

Another safety feature is a system of highefficiency filters through which all air leaving the building must pass. These filters are designed to trap microscopic particles of radioactive materials that might otherwise be vented to the atmosphere. Other specialized devices and systems have also been developed for dealing with other kinds of accidents in various parts of the power plant.

Types of nuclear power plant

Nuclear power plants differ from each other primarily in the methods they use for transferring heat produced in the reactor to the electricity generating unit. Perhaps the simplest design of all is the boiling water reactor plant (BWR), in which coolant water surrounding the reactor is allowed to boil and form steam. This steam is then piped directly to turbines, which produce rotary mechanical power that turns electrical generators. A very different type of plant is one that was popular in Great Britain for many years; this design that carbon dioxide as a coolant. In this type of plant, carbon dioxide gas passes through the reactor core, absorbs heat produced by fission reactions, and is piped into a secondary system where it gives up some of its energy to water, which begins to boil. This steam is then used to power a turbine and generator.

Safety concerns

In spite of all the systems developed by nuclear engineers, the general public has long had serious concerns about the use of such plants as sources of electrical power. In France, for example, where more than half of the electrical power supply comes from nuclear power plants, public support for nuclear power has declined in recent years; France has now placed a moratorium on the construction of new plants. Germany, which relies on nuclear power for approximately 30% of its electricity, has decided to phase out all of its nuclear power plants as quickly as it can obtain replacement power from other sources. In the U.S., enthusiasm for nuclear power in the 1950s and 1960s faded in the 1970s, giving way to widespreadbut often unscientific or illfoundedpublic unease about nuclear dangers, a vigorous antitechnology and antinuclear activist movement, and investor concern over the high monetary cost of nuclear power; no new nuclear power plants have been ordered in the U.S. for over 20 years. The nuclearpower industry remains strongest in Asia, where approximately 25 new plants are now under construction.

One concern about nuclear power plants, of course, is an echo of the worlds first exposure to nuclear power, the atomic bomb blasts. Many people fear that a nuclear power plant may go out of control and explode like a nuclear weapon. In spite of experts insistence that such an event is impossible, a few major disasters have perpetuated the fear of nuclear power plants exploding or failing catastrophically in some other mode. Although commercial nuclear power plants cannot explode, they have a demonstrated potential to pass out of the control of their operators, with unpredictable consequences. By far the most serious of those events was the explosion that occurred at the Chernobyl nuclear power plant near Kiev in the Ukraine in 1986.

On April 16 of that year, one of the four powergenerating units in the Chernobyl complex exploded, blowing the top off the containment building. (The explosion was caused by hydrogen gas released by the overheating core; it was not a nuclear explosion.) Hundreds of thousands of nearby residents were exposed to dangerous levels of radiation and were evacuated from the area. Radioactive clouds released by the explosion were detected downwind in Scandinavia and western Europe. More than a decade later, the remains of the Chernobyl reactor remain far too radioactive for anyone to spend more than a few minutes near the former reactor core. The Soviet government had, of course, always insisted that such a disaster was impossible. In the U.S., the most famous nuclear incident to date is the accident at the Three Mile Island nuclear plant in 1979. The reactor suffered a partial meltdown that was contained by the giant, pillshaped steel vessel containing the core; some radioactive gas was released to the environment, and a hydrogen explosion raised pressures inside the containment dome to within a few pounds per square inch of the domes design pressure. Again, experts had reassured the public that the chances against such an event were literally astronomicalcomparable to those of a giant meteor striking a major city.

Critics of nuclear power also worry about the amount of radioactivity released by nuclear power plants on a daytoday basis. This concern is probably of less importance than is the possibility of a major disaster; studies have shown that nuclear power plants are so well shielded that the amount of radiation to which nearby residents are exposed is no more than that of a person living many miles away. Nevertheless, some epidemiological evidence hints that the small amounts of radioactive material released during routine operation may have detectable medical effects on nearby populations. These claims are, of course, intensely disputed.

In any case, safety concerns in the United States have been serious enough to essentially bring the construction of new plants to a halt in the last decade. Licensing procedures are now so complex and so expensive that few industries are interested in working their way through the bureaucratic maze to construct new plants. However, it should also be noted that orders for new nuclear power plants in the U.S. had practically ceased in the late 1970s, years before the Chernobyl or Three Mile Island accidents or the regulatory response to them. Some analysts argue that the stagnation of the nuclearpower industry should be attributed primarily to economics, rather than to political opposition.

Nuclear waste management

Perhaps the single most troubling issue for the nuclear power industry is waste management. Nuclear wastes can be classified into two general categories, lowlevel wastes and high-level wastes. The former consist of materials that release a relatively modest level of radiation and/or that will soon decay to a level where they no longer present a threat to humans and the environment. Storing these materials in underground or underwater reservoirs for a few years or in some other system is usually a satisfactory way of handling these materials.

High-level wastes are a different matter. After a period of time, the fuel rods in a reactor are no longer able to sustain a chain reaction and must be removed. These rods are still highly radioactive, however, and present a serious threat to human life and the environment that can be expected to last for tens of thousands of years. These rods and any materials derived from them (as, for example, during chemical dismantling of the rods to extract their plutonium for the production of nuclear weapons or for use as a nuclear fuel), are considered high-level wastes.

For more than two decades, the United States government has been attempting to develop a plan for the storage of high-level nuclear wastes. At one time, the plan was to bury the wastes in a salt mine near Lyons, Kansas. Objections from residents of the area and other concerned citizens made that plan infeasible. More recently, the government decided to construct a huge crypt in the middle of Yucca Mountain in Nevada for the burial of high-level wastes. The government insists that Yucca Mountain is safe and will eventually become the longterm storage site for the nations high-level radioactive wastes. Until the site is put into full operation, however (if it is), the wastes slated for burial in it are held in temporary storage on the grounds nuclear power plants throughout the United States.

History

The first nuclear reactor was built during World War II as part of the Manhattan Project to build an atomic bomb. This reactor was constructed under the direction of Italian physicist Enrico Fermi (19011954) in a large room beneath the squash courts at the University of Chicago. Until the day on December 2, 1942, when the Chicago reactor was first put into operation, scientists had relied entirely on mathematical calculations to determine the effectiveness of nuclear fission as an energy source; thus, the scientists who constructed the first reactor were taking an extraordinary chance.

That reactor consisted of alternating layers of uranium and uranium oxide with graphite (carbon) as a moderator. Cadmium control rods were used to control the concentration of neutrons in the reactor. Since the various parts of the reactor were constructed by piling materials on top of each other, the unit was at first known as an atomic pile.

Nuclear fusion

Many scientists believe that the ultimate solution to the worlds energy problems may be in the harnessing of nuclear fusion. A fusion reaction is one in which two small atomic nuclei combine with each other to form one larger nucleus. For example, two hydrogen nuclei may combine with each other to form the nucleus of an atom known as deuterium, or heavy hydrogen. Fusion reactions are responsible for the production of energy in stars. Most commonly, four hydrogen atoms fuse in a series of reactions to form a single helium atom. An important byproduct of these reactions is the release of an enormous amount of energy. By weight, a fusion reaction releases many times more energy than does a fission reaction.

The world was introduced to the concept of fusion reactions in the 1950s when first the United States and then the Soviet Union exploded fusion (hydrogen) bombs. The energy released in the explosion of each such bomb was more than 1,000 times greater than the energy released in the explosion of a single fission bomb such as that used by the U.S. to destroy the city of Hiroshima.

KEY TERMS

Cladding A material that covers the fuel elements in a nuclear reactor in order to prevent the loss of heat and radioactive materials from the fuel.

Containment Any system developed for preventing the release of radioactive materials from a nuclear power plant to the outside world.

Coolant Any material used in a nuclear power plant to transfer the heat produced in the reactor core to another unit in which electricity is generated.

Generator A device for converting kinetic energy (the energy of movement) into electrical energy.

Neutron A subatomic particle that carries no electrical charge and that has a mass of zero.

Nuclear fission A reaction in which a larger atomic nucleus breaks apart into two roughly equal, smaller nuclei.

Nuclear fusion A reaction in which two small nuclei combine with each other to form one larger nucleus.

Nuclear pile The name given to the earliest form of a nuclear reactor.

Turbine A device consisting of a series of baffles mounted on a wheel around a central shaft used to convert the energy of a moving fluid into the energy of mechanical rotation.

As with fission, scientists and nonscientists alike expressed hope that fusion reactions could someday be harnessed as a source of energy for everyday needs. This line of research has been much less successful, however, than research on fission power plants. In essence, the problem has been to find a way of producing, in a controlled, sustainable fashion, the very high temperatures (millions of degrees Celsius) needed to sustain fusion. Optimistic reports of progress on a fusion power plant appear in the press from time to time, but some authorities now doubt that fusion power will ever be an economic reality.

The future of nuclear power

Proponents of nuclear power argue that a fresh round of powerplant construction should be undertaken to meet growing electricity demand. Coalfired plants presently produce most of the worlds electricity, but release air pollution and greenhouse gases; nuclear power, its advocates argue, does not release these substances. Given the threat of global climate change, it follows that it is of utmost importance to build more nuclear power plants. Opponents of nuclear power respond that greater reductions in air pollution and greenhousegas emissions could be achieved by spending the same money on non-nuclear technologies (i.e., efficiency improvements and renewable energy sources such as solar power). They also argue that a massive increase in the number of nuclear power plants bring increased risks for nuclear accidents and for proliferation of nuclear weapons to states that do not as yet have them. Globally, nuclear power is approximately stagnant as of 2006; wind power is being deployed more rapidly than nuclear power, and at a fraction the cost per kilowatthour delivered. Whether it is about to undergo the renaissance urged by its advocates or the accelerated phaseout urged by its opponents may not be apparent for some years.

See also Accelerators; Atomic models; Bioterrorism.

Resources

BOOKS

Caldicott, Helen. Nuclear Power is Not the Answer. New York: New Press, 2006.

Ramsey, Charles B. Commercial Nuclear Power: Assuring Safety for the Future. Charleston, SC: BookSurge Publishing, 2006.

Richard, L., and Georges Charpak. Megawatts and Megatons: The Future of Nuclear Power. University of Chicago Press, 2002.

PERIODICALS

Ahearne, J.F. Intergenerational issues regarding nuclear power and nuclear waste. Risk Analysis 20 (2001): 763770.

Hoffert, Martin, et al. Advanced Technology Paths to Global Climate Stability: Energy for a Greenhouse Planet. Science vol. 298, no. 5595 (Nov. 1, 2002): 981987.

David E. Newton

Larry Gilman

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Nuclear Power

Nuclear Power

Introduction

Nuclear power is the generation of electricity from the breakdown of unstable atoms, especially atoms of uranium and plutonium. Nuclear power plants produce large amounts of electricity, but, in operation, no carbon dioxide. A nuclear power plant thus does not contribute to the greenhouse effect on a daily operational basis.

Nuclear electricity was first produced in useful quantities in 1954, and hundreds of plants have since been built worldwide. Nuclear power has been stagnant for several decades in some countries, such as the United State, and successful in others, notably France. In some countries, it has been politically controversial due to public concerns about its safety. There have also been international concerns about the use of materials from nuclear power plants to produce nuclear weapons, as U.S. officials and others have alleged Iran is doing as of 2007.

In the early 2000s, many governments, including those of Russia and of the United States, were advocating the construction of a new wave of nuclear power plants, citing global climate change as the reason for such construction. A few environmentalists, though not most, had recently agreed that nuclear power was necessary to reduce climate change. The proposal to revive nuclear power to mitigate greenhouse warming has many critics, however, who argue that nuclear power is expensive, slow to deploy, and inherently unsafe because of its radioactive wastes and its potential for accidents, terrorist attacks, and nuclear weapons proliferation.

Historical Background and Scientific Foundations

What Is Nuclear Power?

The structure of the atom—a small, dense nucleus surrounded by a cloud of electrons—was not understood until 1911, when British physicist Ernest Rutherford (1871-1937) and coworkers found that the subatomic particles called alpha particles, when fired at a thin film of gold, would occasionally bounce right back at their source as if they had struck a wall. This showed that most of the mass of the gold atoms must be concentrated in a small, dense core.

During the following 15 years, scientists discovered that atomic nuclei contain two types of particles, namely protons and neutrons. The proton has a positive electrical charge and the neutron has no charge. The chemical characteristics of each atom are determined by how many protons it contains, since an atom tends to attract to itself as many electrons (which are negatively charged) as will balance out the positive charges of its protons. The tendency of protons to attract electrons is the basis of chemical bonding; forming and breaking the electrical bonds between atomic nuclei and electrons stores and releases chemical energy. All energy released by burning fuels such as gasoline or hydrogen is from electrical bonds.

Another kind of energy resides in the atom in the bonds between protons and neutrons in nuclei. These bonds are much stronger than the bonds between protons and electrons, since they are created by a force (the nuclear force) that acts at shorter range and is far more powerful than the electrical force. Making and breaking nuclear bonds can consume or release energy. When nuclei come together to form a larger nucleus, the process is called fusion; when nuclei split to release free particles, photons (light particles), and smaller nuclei, the process is called fission. Atoms that undergo spontaneous fission are said to be radioactive.

Nuclear fusion releases all the heat produced by the sun and other stars. Nuclear fission heats the interior of Earth and is the process by which all existing nuclear power plants produce energy, although some scientists hope to harness fusion for energy production in the distant future. Since wind, waves, green plants, and sunlight are all powered by the sun (fusion) and geo-thermal heat comes from radioactive elements in Earth's core and mantle (fission), all forms of renewable energy are ultimately nuclear in origin. Nuclear fission and fusion are also used in nuclear weapons.

In a typical nuclear power plant, large, unstable atoms—most often atoms of uranium 235, whose nuclei contain 92 protons and 143 neutrons—are concentrated in a large device called a reactor. Atoms of uranium 235, like some other elements, fission spontaneously at unpredictable times. When a uranium 235 atom fissions, it releases a neutron at high speed like a subatomic bullet. If this neutron strikes another uranium nucleus, that nucleus will also fission. This reaction releases two neutrons. If there are enough uranium atoms nearby, one or both of these neutrons may strike one and cause it, too, to fission prematurely. This process continues, with neutrons from fissioned atoms causing others to fission, creating what is called a chain reaction.

A chain reaction that involves a great many atoms in a short time produces an explosion. One that levels out and causes atoms to fission in a steady flow is called a controlled chain reaction. Controlled chain reactions are the basis of nuclear power. In a nuclear reactor, the energy released by trillions of disintegrating uranium atoms (or atoms of other elements, such as thorium or plutonium) is captured by surrounding material as heat. This heat is used to boil water, and the steam from the boiling water is used to drive turbines that turn generators that produce electricity.

The reason that the reaction in a nuclear reactor can be controlled, while that in a nuclear fission bomb is not, is that in a reactor the atoms of uranium 235 are not highly concentrated. They are diluted, instead, by atoms that do not fission so easily and which therefore cannot sustain a chain reaction. Uranium 238 (92 protons, 146 neutrons) is the usual dilutant in reactor fuel. In the United States, most reactors are fueled by pellets of uranium oxide (UO2), a black, metallic substance whose uranium consists of 3–5% uranium 235. The remainder is uranium 238. This low-enriched uranium, as it is called, is richer in uranium 235 than natural uranium ore (.7% uranium 235 and 97.3% uranium 238), but has too little uranium 235 to be used as a bomb material or to explode accidentally.

WORDS TO KNOW

BIOMASS: The sum total of living and once-living matter contained within a given geographic area. Plant and animal materials that are used as fuel sources.

ELECTRICAL BOND: Nontechnical term for the bonds that hold chemical compounds together. Such bonds (ionic or covalent) are all electrical in the sense that they depend on the attraction between positive electrical charges in atomic nuclei and negative electrical charges carried by electrons in orbitals surrounding nuclei.

FISSION: Nuclear fission is a process in which the nucleus of an atom splits, usually into two daughter nuclei, with the transformation of tremendous levels of nuclear energy into heat and light.

GREENHOUSE GASES: Gases that cause Earth to retain more thermal energy by absorbing infrared light emitted by Earth's surface. The most important greenhouse gases are water vapor, carbon dioxide, methane, nitrous oxide, and various artificial chemicals such as chlorofluorocarbons. All but the latter are naturally occurring, but human activity over the last several centuries has significantly increased the amounts of carbon dioxide, methane, and nitrous oxide in Earth's atmosphere, causing global warming and global climate change.

HALF-LIFE: The time it takes for half of the original atoms of a radioactive element to be transformed into the daughter product.

KILOWATT-HOUR: Amount of energy corresponding to a power flow of 1 kilowatt (1,000 watts) sustained for 1 hour. Often used as a unit of electricity consumption. A 100-watt light bulb left on for 10 hours consumes 1 kilowatt-hour (kWh). The average U.S. household purchases about 10,000 kWh of electricity per year.

NUCLEAR FUSION: The process by which two light atomic nuclei combine to form one heavier atomic nucleus. As an example, a proton (the nucleus of a hydrogen atom) and a neutron will, under the proper circumstances, combine to form a deuteron (the nucleus of an atom of “heavy” hydrogen). In general, the mass of the heavier product nucleus is less than the total mass of the two lighter nuclei. Nuclear fusion is the initial driving process of nucleosynthesis.

RENEWABLE ENERGY: Energy obtained from sources that are renewed at once, or fairly rapidly, by natural or managed processes that can be expected to continue indefinitely. Wind, sun, wood, crops, and waves can all be sources of renewable energy.

The nuclear chain reactions that produce nuclear energy do not produce greenhouse gases. This is the reason for advocating nuclear power as a way to mitigate greenhouse warming. Nuclear power can be used, its proponents say, instead of coal and natural gas to produce electricity. Coal is polluting; mining it is destructive; and it produces large amounts of carbon dioxide. Natural gas is expensive.

However, nuclear fission reactions do produce other wastes. As uranium atoms break down, atoms of other elements appear, called daughter isotopes. These, too, are unstable. Some fission quickly and others slowly. The speed with which the atoms of a given isotope (variety of an element) break down is characterized by that isotope's half-life, the time it takes, on average, for half the atoms of a certain isotope to fission spontaneously. The half-life of uranium 235, for example, is 700 million years; the half-life of plutonium 239, a breakdown product of uranium 235 that can also be used as a nuclear fuel or bomb material, is 24,100 years. Some isotopes have half-lives measured in minutes. The mixture of radioactive isotopes that accumulates in reactor fuel as the power-generating chain reaction progresses is not useful as fuel, so periodically the fuel pellets must be removed and replaced with fresh ones. The used pellets contain unused uranium 235, plutonium 239, and many other elements. This mixture, which is both chemically toxic and radioactive, is often referred to as nuclear waste.

Nuclear power generation produces nuclear waste instead of carbon dioxide. Supporters of nuclear power as a way to mitigate greenhouse warming contend that nuclear waste can be safely managed, either by some kind of reprocessing, by burial for hundreds of thousands of years beneath deserts, or both. Opponents argue that reprocessing is dangerous and expensive and that no burial scheme can be guaranteed to isolate nuclear waste from the environment for the hundreds of thousands of years needed for its radioactivity to disappear.

As of 2007, there were about 440 nuclear power plants operating in the world in 30 countries, mostly in North America and Western Europe. They produced approximately 16% of the world's electricity (6.5% of total energy demand, including non-electrical energy), varying from 80% in Lithuania (the highest), to about 20% in the United States, to 0% in many other countries. Hydroelectric power provides about the same amount of electricity worldwide. The United States, with 103 working reactors, is the world's largest producer of nuclear electricity. As of 2007, 32 nuclear plants were under construction, half of which arre in Asia. Of the last 31 nuclear reactors to begin operating up to that time, 22 were also in Asia.

History of Nuclear Power Generation

Nuclear energy was first exploited for the creation of nuclear weapons. The first such weapon was tested by the United States in 1945, and was used to destroy two Japanese cities to bring an end to World War II. The Soviet Union achieved weapons capability in 1949, the United Kingdom soon after, and France and China in the 1960s. In 1953, U.S. President Dwight Eisenhower (1890-1969) announced the “Atoms for Peace” program, whereby the United States would spread nuclear reactor technology around the world. Reactors, fissionable materials, and nuclear know-how were given away by the United States to numerous developing countries, including India, that renounced any intention to build nuclear weapons. (India became a nuclear weapons power in 1974 using nuclear material from Atoms for Peace.)

Starting in the 1950s, the United States and other countries embarked on ambitious schemes of nuclear power plant construction. In many countries, the plants were entirely owned and operated by governments, as in France and the Soviet Union. In the United States, they were purchased by utility companies with support from government tax breaks and legal guarantees against liability. Widespread public concern about nuclear power only appeared in the United States and some other countries starting in the 1970s, but nuclear power's woes were primarily economic, not political. Orders for new U.S. plants had ceased before the 1979 near-melt-down at the Three Mile Island plant in Pennsylvania; U.S. utilities had found that energy growth was slower than projected, especially after the OPEC oil embargo of 1973, and that nuclear power plants were more expensive than projected.

In the Soviet Union, nuclear plant construction proceeded under government command but was severely set back by the meltdown and explosion at the Chernobyl nuclear plant in 1986, which spread radioactive fallout over much of northern Europe and Scandinavia. In the United States, as of 2007, no new order for a nuclear plant made since 1973 had remained unconcealed. This appeared likely to change soon, however, as a result of renewed government, industry, and utility support for nuclear power.

In the early 2000s, under the presidential administration of George W. Bush, U.S. government support for nuclear power increased. The nuclear industry now plans to build 28 new reactors in the United States at a cost of about $4 to $5 billion apiece. In 2007, the Clean Energy Act of 2007, passed by both the House and Senate, contained a provision allowing the Department of Energy to give unlimited loan guarantees for any form of power generation it deems “clean.” This includes nuclear power plants under 2005 legislation because nuclear power does not emit greenhouse gases. The loan guarantees would mean that utilities could borrow money from banks to build new nuclear power plants, and that if the utilities could not pay back the loans, the federal government would do so for them. These guarantees can cover up to 80% of the cost of any single project. Although other energy sources, such as solar power and biomass, may also receive the guarantees, nuclear power is likely to receive the bulk of them because the industry is poised to begin a large number of expensive projects.

Impacts and Issues

The Case for Nuclear Power

Both government and industry sources appeal to the need to slow greenhouse warming of global climate as a primary reason to renew and accelerate the building of nuclear power plants worldwide. Advocates include international bodies tasked with the promotion of nuclear power, including the International Energy Agency, which in 2006 called for the construction of 200 new power plants over the next 24 years, and the International Atomic Energy Agency (IAEA), which in 2004 warned that without expanded nuclear construction the share of world electricity generated by nuclear power would drop from 16% to 12% by 2030. The IAEA recommended expansion of nuclear generating capacity by 2.5 times to 2030 to provide 27% of total electricity production. The UN's Intergovernmental Panel on Climate Change (IPCC) stated in its 2007 report that nuclear power “could make an increasing contribution to carbon-free electricity and heat in the future.”

Past problems with safety, reliability, waste, and high costs have been or will soon be solved, say nuclear proponents. According to Yuri Sokolov, the IAEA's deputy director general for nuclear energy: “In the longer term, new innovative designs, with shorter construction times and significantly lower capital costs could help promote a new era of nuclear power.”

According to the IAEA, nuclear power emits almost no greenhouse gases. From mining of uranium ore to disposal of nuclear waste, including construction of reactors and other facilities, the IAEA states that nuclear power emits .07-.21 ounces (2-6 g) of carbon per kilowatt-hour of electricity generated. (A kilowatt-hour is the amount of energy required for one hour by a device that consumes a thousand watts of electricity: e.g., ten 100-watt light bulbs burning for one hour consume a kilowatt-hour of electricity.) This is about as much carbon as is released during the manufacture of machinery associated with wind power and photovoltaic solar electricity. Japan and India have officially named nuclear power as part of their strategies to reduce greenhouse-gas emissions. And according to the IAEA in 2005, “in the U.S.A. and some other countries …nuclear is now the cheapest way to produce electricity.”

The Case against Nuclear Power

Opponents of the proposed increase in nuclear power plants argue that quick action is needed to reduce greenhouse gases, but nuclear power plants take approximately 10 years to build. According to the Nuclear Energy Institute's 2007 position statement, “the new nuclear power projects now in the early stages of development will not enter service until the 2015-2020 period.” In contrast, increased efficiency and renewable energy sources such as wind turbines and solar cells can be installed in months.

Opponents also argue that nuclear power is too expensive. For example, the IAEA's claim that “nuclear is now the cheapest way to produce electricity” only takes nuclear's operating costs into account, not construction, decommissioning, and waste-disposal costs, and compares nuclear power only to coal and natural gas, not to renewable sources like wind. When comparing all costs for each power source divided by all the electricity it will make over its lifetime, new nuclear costs 7 cents per kilowatt-hour in the United States (according to a 2003 study by the Massachusetts Institute of Technology) and new wind power costs about half as much.

Moreover, opponents argue, the cheapest way to keep carbon out of the air is not to generate new power at all, but to use less power by increasing end-use efficiency. According to a 2005 paper by Amory Lovins, a leading proponent of greenhouse mitigation through efficiency and small-scale power generation, each dollar spent on nuclear power actually worsens global warming because thesamemoney couldhavekepttwice as much carbon out of the air if spent on wind and up to 10 times as much if spent on efficiency. “In this sense of ‘opportunity cost’—any investment foregoes other outcomes that could have been bought with the same money—nuclear power is far more carbon-intensive than a coal plant.”

Nuclear opponents also argue that nuclear power is dangerous, spreading know-how that can be used by nations to build nuclear weapons (as Iran is presently accused of seeking to do); providing terrorists with tempting targets; and burdening future generations with radioactive wastes that can be buried but which may not stay buried for the tens of thousands of years required.

See Also Coal; Energy Contributions; Energy Efficiency; Wind Power.

BIBLIOGRAPHY

Books

Metz, B., et al, eds. Climate Change 2007: Mitigation of Climate Change: Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. New York: Cambridge University Press, 2007.

Periodicals

Andrews, Edmund L., and Matthew L. Wald. “Energy Bill Aids Expansion of Atomic Power.” The New York Times (July 31, 2007).

Beck, Peter W. “Nuclear Energy in the Twenty-First Century: Examination of a Contentious Subject.” Annual Review of Energy and the Environment 24 (1999): 113-137.

Falksohn, Rüdiger. “New Reactors Across the Globe: A Nuclear Power Renaissance.” The New York Times (January 16, 2007).

Web Sites

Berry, Stephen, Amory Lovins, and Peter Bradford. “Nuclear Power and Climate Change.” Bulletin of the Atomic Scientists Online, March 2007-September 2007. <http://thebulletin.org/roundtable/nuclear-power-climate-change> (accessed October 28, 2007).

“The Future of Nuclear Power.” Massachusetts Institute of Technology, 2003. <http://web.mit.edu/nuclearpower> (accessed October 28, 2007).

Lovins, Amory. “Nuclear Power: Economics and Climate-Protection Potential.” Rocky Mountain Institute, September 11, 2005. <http://www.rmi.org/images/PDFs/Energy/E05-14_NukePwrEcon.pdf> (accessed October 28, 2007).

“Nuclear Energy Institute Position on Climate Change.” Nuclear Energy Institute, October 2007. <http://nei.org/keyissues/protectingtheenvironment/policybriefs/neipositiononclimatechange> (accessed October 28, 2007).

“Nuclear Energy, No Solution to Climate Change.” Greenpeace, June 22, 2007. <http://www.greenpeace.org/raw/content/usa/press-center/reports4/nuclear-energy-no-solution-to.pdf> (accessed October 28, 2007).

“Nuclear Power and Climate Change.” Agence pour l'énergie nucléaire (Nuclear Energy Agency). <http://www.nea.fr/html/ndd/climate/climate.pdf> (accessed October 28, 2007).

“Nuclear Power and Global Warming.” Union of Concerned Scientists, March 2007. <http://www.ucsusa.org/global_warming/solutions/nuclear-power-and-climate.html> (accessed October 28, 2007).

“Nuclear Power for Greenhouse Gas Mitigation.” International Atomic Energy Agency, November 2000. <http://www.iaea.org/Publications/Booklets/GreenhouseGas/greenhousegas.pdf> (accessed October 28, 2007).

Larry Gilman

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Nuclear Power

Nuclear Power

Introduction

Nuclear power is energy from controlled reactions involving the nuclei (dense, tiny centers) of atoms. Nuclear power plants are large industrial facilities fueled by radioactive metals such as uranium 235 and plutonium. Uranium 235 is obtained by refining natural ores, while plutonium is an artificial element created by exposing a common but otherwise mostly useless form of uranium (uranium 238) to radiation, usually in nuclear power plants. Most nuclear power plants are fueled by uranium 235.

In a nuclear power plant, nuclear fuel is concentrated in a structure called a nuclear reactor. In the reactor, radiation from disintegrating fuel atoms is made to impinge on other fuel atoms. This triggers further disintegrations, leading to a sustained reaction that releases a flow of energy. This energy is harvested as heat, which in a typical plant is used to boil water to make steam to spin turbines that turn electric generators.

As of 2008, about 16% of the world electricity supply was produced by nuclear power plants, including 19% of U.S. supply. As most energy is consumed in forms other than electricity, especially heat and vehicular power, the nuclear contribution to world energy supply was smaller than its contribution to world electricity supply (less than 7%). There is ongoing global debate about whether building a new wave of nuclear power plants is necessary to mitigate global climate change while meeting global energy needs.

Historical Background and Scientific Foundations

The first application of nuclear fission was not to power production but was used in war—the U.S. destruction of the Japanese cities of Hiroshima and Nagasaki in August 1945 during World War II (1939–1945), which caused about 274,000 civilian deaths. Electricity from a nuclear reactor was first fed to a power grid (system of wires distributing power) in the Soviet Union in 1954.

When nuclear power first became practical, it was presented to the public as a miracle of science, promising future electricity “too cheap to meter” (in the words of the chairman of the U.S. Atomic Energy Commission, 1954). It was widely greeted by the American public on these terms. However, by the 1970s nuclear power was widely argued in the United States and Europe to entail an unacceptable threat of long-lived radioactive pollution released by disastrous accidents at nuclear power plants or waste-storage facilities. These fears were strengthened by a near-disaster at the Three Mile Island nuclear plant in Pennsylvania in 1979 and a full-fledged disaster at the Chernobyl power plant in the Ukraine (then a member state of the Soviet Union) in 1986, which spread radioactivity over much of Europe and killed thousands.

However, construction of nuclear power plants had already stalled in the United States (the world’s largest generator of nuclear electricity) before these accidents happened. As of early 2008, no new nuclear power plants had been licensed in the United States since 1978. Nuclear construction halted not because of public opposition to nuclear power but because the cost of nuclear power plants had turned out to be too high for power companies to afford.

All energy sources except the tides are ultimately nuclear in origin. The sun’s radiant energy derives from nuclear reactions in its core, and sunlight drives biological growth, winds, and precipitation. Nuclear reactions inside Earth supply the heat of geothermal energy. However, in reactors the nuclear reactions are concentrated on Earth’s surface. This creates both opportunity and danger for human-controlled nuclear reactions: The high power density of a nuclear reactor makes it possible to harvest a massive, continuous flow of energy in a nuclear power plant, but this flow is dangerous to the planet itself. Also, nuclear materials and reactions similar to those used in power generation are used to make nuclear weapons. In 2008, there was international concern over whether nuclear material had been diverted from the Iranian nuclear power program to a secret nuclear-weapons program, although the International Atomic Energy Agency of the United Nations had not found any proof of such diversion. Concern over Iran’s nuclear behavior highlights the close link between nuclear power-generating technology and bomb-building technology.

The burning of a conventional fuel such as gasoline is a chemical, not a nuclear reaction, and involves only the electrons surrounding the nucleus. A nuclear reaction changes the nucleus itself, making it into a new element or a different isotope of the same element. Thus, after fuel metal has been exposed to radiation in a nuclear reactor for some months, many of its atoms have been changed into other elements. Most of these atoms are, like the original fuel, radioactive, that is, tend to break apart spontaneously and emit fast-moving subatomic particles and high-energy electromagnetic waves (gamma rays). These particles and rays are dangerous to life because they disrupt chemical reactions in cells. At high doses, radiation kills cells directly: At low doses, it can cause cancer in multicellular organisms (such as people) by altering DNA.

As the reaction products (altered atoms) in nuclear fuel accumulate, the fuel does not work as well in the reactor. Eventually this spent fuel must be removed. Spent or used-up fuel from a reactor is a form of high-level radioactive waste, that is, material that emits intense radioactivity. Some of the radioactive substances in this waste, such as plutonium, remain dangerously radioactive for hundreds of thousands of years.

Impacts and Issues

Both supporters and opponents of nuclear power agree that high-level radioactive waste must be isolated from the environment lest it injure human beings and other creatures. They disagree, however, on whether this goal can be dependably met both for the short term (tens of years, while nuclear waste is stored inside nuclear power plants or in above-ground storage facilities) or the long term (tens to hundreds of thousands of years, the lifetime of high-level radioactive waste). Supporters of nuclear power argue that nuclear power plants will only rarely release their radioactive materials to the environment, as happened in the Chernobyl accident of 1986, and that deep burial in rock layers will isolate nuclear waste for the long term. Opponents of nuclear power argue that nuclear power plants and storage facilities can and have failed, quoting pre-Three Mile Island reassur-

WORDS TO KNOW

ATOMIC NUCLEUS: The small, dense, positively charged central region of an atom, composed of protons and neutrons.

FISSION: A process in which the nucleus of an atom splits, usually into two daughter nuclei, with the transformation of tremendous levels of nuclear energy into heat and light.

GREENHOUSE GAS: A gas whose accumulation in the atmosphere increases heat retention.

ISOTOPE: A form of a chemical element distinguished by the number of neutrons in its nucleus.

NUCLEAR WASTE: Material left over from nuclear processes that is often radioactive or contaminated by radioactive elements.

OPPORTUNITY COST: The total cost incurred by choosing one option over another.

RADIOACTIVE: Containing an element that decays, emitting radiation.

ances from pro-nuclear experts that nothing could possibly go wrong, and note that nuclear facilities may be deliberately targeted by terrorists or military enemies. They also argue that there is no way to be sufficiently confident that any waste-storage scheme, even deep burial, will be effective for hundreds of thousands of years.

Starting in the 1990s, advocates of nuclear power have turned the environmentalists’ anti-nuclear arguments on their head, urging that nuclear power, far from being an environmental threat, is the only way to generate enough electricity for modern society without worsening global warming. This argument is based on the fact that the nuclear reactions that release energy in a nuclear power plant, unlike the chemical reactions that release energy in a coal- or gas-fired power plant, do not release carbon dioxide or other greenhouse gases. An operating nuclear power plant is therefore, considered in isolation, greenhouse-neutral.

In 2005, U.S. President George W. Bush advocated massive government grants for a new round of nuclear power plants on the grounds that nuclear plants are “environmentally friendly.” In 2005, the World Nuclear Association, a nuclear industry advocacy group, recommended that between then and the end of the century, the global number of nuclear power plants be increased over tenfold, from 441 to 5,000, in order to combat global warming while meeting increased electricity demands in developing countries. The editors of the New York Times opined in 2006, “Not so many years ago, nuclear energy was a hobgoblin to environmentalists, who feared the potential for catastrophic accidents and long-term radiation contamination. But this is a new era… Suddenly nuclear power is looking better.”

Critics of nuclear power—and a very small percentage of environmentalists, despite some media claims, have switched to supporting nuclear power—respond that (1) the nuclear power cycle as a whole, including mining, refining of fuel, building plants, disposing of waste, and taking old plants apart, is in fact a significant emitter of greenhouse gases; (2) even if nuclear power were greenhouse-neutral, it is so expensive compared to other available ways of reducing greenhouse-gas emissions that money spent on nuclear power actually increases greenhouse emissions by hogging limited funds; (3) and nuclear power plants take too long to build (at least 5 years) to be part of a rapid response to climate change.

For example, prominent antinuclear energy expert Amory Lovins wrote in 2005 that the higher cost of nuclear power “per unit of CO2 displaced,” compared to efficiency, wind power, cogeneration (making electricity and useful heat together instead of discarding heat from electric plants as waste), and other renewables, “means that every dollar invested in nuclear expansion will worsen climate change by buying less solution per dollar…. In this sense of ‘opportunity cost’… nuclear power is far more carbon-intensive than a coal plant.” Lovins also argued that nuclear power plants have been rejected by market forces, so that all nuclear power plants proposed today would depend on government grants. Nuclear power advocates respond that non-nuclear alternative energy sources simply cannot produce enough energy to power modern industrial society. This debate continues. In 2005, the U.S. government allocated $6 billion in benefits for new nuclear reactors, but as of 2008, construction had not yet commenced on any new U.S. reactor.

Primary Source Connection

There are vehement arguments for and against nuclear power. The main advantage of nuclear power plants is that they do not cause atmospheric pollution. No smokestacks are needed because nothing is being burned. Nuclear power plants do not contribute to potential global warming and help countries lower their carbon footprint. For example, France initiated a large-scale nuclear program after the Arab oil embargo in 1973 and has been able to reduce its acid rain and carbon dioxide emissions by more than 40%. Shipments of fuel are also minimal and so the hazards of coal transportation and oil spills are avoided.

As with other forms of producing electricity, nuclear power generation can, however, have serious and unintended environmental impacts. The main objections to nuclear power plants are the fear of possible accidents, the unresolved problem of nuclear waste storage, and the possibility of plutonium diversion for weapons production by a terrorist group. The issue of waste storage becomes particularly emotional because leakage from a waste depository could contaminate groundwater.

Despite increased safety measures, as the following article shows, the fear of accidents remains a potent deterrent toward widespread development of nuclear power facilities.

ACCIDENTS DIM HOPES FOR GREEN NUCLEAR OPTION

The recent earthquake in Japan and accidents at two German power plants raise questions on the safety of nuclear energy as a cleaner alternative.

As concern about global warming has swelled in recent years, so has renewed interest in nuclear energy. The main reason: Nuclear plants produce no carbon dioxide or other greenhouse gases tied to climate change, at least not directly.

New reactor designs make plants safer than those operating in the days of the accidents at Chernobyl and Three Mile Island decades ago, advocates say. And there’s no group of OPEC countries in unstable parts of the world controlling the main raw material—uranium.

But that was before an earthquake in Japan this week rattled the Kashiwazaki nuclear power plant. The plant’s operator “said it had found more than 50 problems at the plant caused by Monday’s earthquake,” The New York Times reported, adding:

While most of the problems were minor, the largest included 100 drums of radioactive waste that had fallen over, causing the lids on some of the drums to open, the company said. The company said that the earthquake also caused a small fire at the plant, the world’s largest by amount of electricity produced, and the leakage of 317 gallons of water containing trace levels of radioactive materials into the nearby Sea of Japan.

Meanwhile, accidents at two German nuclear reactors last month prompted German Environment Minister Sigmar Gabriel to call for the early shutdown of all older reactors there, reports Bloomberg News.

Concern about the safety of Germany’s 17 reactors has grown after a fire at Vattenfall’s Kruemmel site June 28 and a network fault at its Brunsbuettel plant on the same day. Der Spiegel online adds:

It took the fire department hours to extinguish the blaze. Even worse, the plant operator’s claim that a fire in the transformer had no effect on the reactor itself proved to be a lie.

In short, the incident made clear that nuclear energy is by no means the modern, well-organized, high-tech sector portrayed until recently by politicians and industry advocates. Indeed, the frequency of problems occurring at Germany’s aging reactors is on the rise. Just as old cars succumb to rust, nuclear power plants built in the 1970s and ‘80s are undergoing a natural aging process.

IN CONTEXT: NUCLEAR POWER INSPIRES PASSIONATE DEBATE

Environmental activists are not always united, especially on matters such as the benefits vs. costs of nuclear energy, which alternative energy sources provide the greatest potential relief from the pollution caused by the use of fossil fuels (e.g., petroleum, coal, natural gas), how to best mitigate the environmental impacts of large hydroelectric dams, etc.

Nuclear power, for example, remains in a gray zone—in some ways cleaner for the environment, yet with the potential to poison Earth for generations beyond any benefit it offers. Regardless, for many years now it has been a significant part of electricity production in some countries. France, for example, obtains 78% of its electricity from nuclear power. The use of nuclear power, however, remains a lightning rod for protest and extent of its use, or indeed whether it should be used at all, often leads to fractious debate and passionate protest.

On Wednesday, the chief executive of Vattenfall Europe AG stepped down. Klaus Rauscher was the second manager to depart this week amid mounting criticism for the utility’s handling of a fire at a nuclear plant in northern Germany, reports the AP.

‘When it comes to security at nuclear power plants, I can only say, that when it comes to the information policy, this really has not been acceptable and therefore my sympathy for the industry is limited,’ Chancellor Angela Merkel said.

Merkel, a physicist by training, normally favors nuclear power, but the June 28 fire at the Kruemmel plant, near Hamburg, has put the industry in a bad light.

Still, nuclear power has won some powerful allies in the environmental community, writes E Magazine editor Jim Motavalli on the web site AlterNet.

He quotes Fred Krupp, president of Environmental Defense, as saying, “We should all keep an open mind about nuclear power.” Jared Diamond, best-selling author of “Collapse,” adds, “To deal with our energy problems we need everything available to us, including nuclear power,” which, he says, should be “done carefully, like they do in France, where there have been no accidents.”

Stewart Brand, who founded The Whole Earth Catalog and Whole Earth Review, concludes, “The only technology ready to fill the gap and stop the carbon dioxide loading of the atmosphere is nuclear power.”

Environmentalists continue to push for more benign sources—wind, biomass, geothermal, and solar, as well as greater conservation—to power the world.

But The Washington Post reports that “Most of the technologies that could reduce greenhouse gases are not only expensive but would need to be embraced on a global scale.” The article continues:

Many projections for 2030 include as many as 1 million wind turbines worldwide; enough solar panels to cover half of New Jersey, massive reforestation; a major retooling of the global auto industry; as many as 400 power plants fitted with pricey equipment to capture carbon dioxide and store it underground; and, most controversial, perhaps 350 new nuclear plants around the world.

That kind of nuclear expansion in the US seems unlikely. The country hasn’t licensed a new plant in more than 30 years, and the devilish political and scientific subject of radioactive waste disposal has yet to be fully addressed.

But that hasn’t stopped other countries from pushing ahead. Russia “hopes to export as many as 60 nuclear power plants in the next two decades,” The Christian Science Monitor reported this week, including what would be “the first-ever floating atomic power station” at sea.

But noting an estimate from the Massachusetts Institute of Technology, The Salt Lake Tribune in Utah reports that “at least 1,000 new nuclear plants would be needed worldwide in the next 50 years to make a dent in global warming.”

Brad Knickerbocker

Kickerbocker, Brad. “Accidents Dim Hopes for Green Nuclear Option.” Christian Science Monitor (July 19, 2007).

See Also Carbon Dioxide (CO2) Emissions; Climate Change; Global Warming; Nuclear Test Ban Treaties; Radioactive Waste

BIBLIOGRAPHY

Periodicals

“The Greening of Nuclear Power.” New York Times (May 13, 2006).

Hoffert, M., et al. “Advanced Technology Paths to Global Climate Stability: Energy for a Greenhouse Planet.” Science. 298 (2002): 981-987.

Marshall, Eliot. “Is the Friendly Atom Poised for a Comeback?” Science 309 (2005): 1168–1169.

Web Sites

Rocky Mountain Institute. “Nuclear Power: Economics and Climate-Change Potential.” https://www.rmi.org/images/PDFs/Energy/E05-08_NukePwrEcon.pdf (accessed April 15, 2008).

Larry Gilman

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Nuclear Power

Nuclear Power

Overview

Nuclear power is a valuable and controversial source of energy in many nations around the world. Originally heralded as a reliable source of clean, safe power, two accidents raised concerns about the wisdom of continued reliance on nuclear power. However, with a limited store of fossil fuels, concerns about greenhouse gas emissions, drawbacks in alternative power sources, and the limited natural resources of many nations, nuclear power is likely to remain an important source of power for many years.

Background

The first nuclear reactor of which there is a record began operation about two billion years ago in a sandstone bed in what is now Gabon, in the western part of Africa. This natural reactor operated intermittently for tens of millions of years, unheralded and unknown until discovered by French scientists in the 1970s. It is not known if the Oklo reactor (named after the part of Gabon where it lies) was unique in the world or if other natural nuclear reactors operated at other times, but there is no doubt that this body of uranium ore did indeed operate as a nuclear reactor when algae was the most advanced life on earth.

Research into nuclear fission began in the 1930s, when Lise Meitner (1878-1968) and Otto Hahn (1879-1968) first showed that uranium atoms could be made to break apart, or fission, when struck by a neutron. At about the same time, Leo Szilard (1898-1964), a Hungarian-born American physicist realized how a nuclear chain reaction could be made to be self-sustaining, producing power. These ideas and many more came together during the Manhattan Project when Enrico Fermi (1901-1954) led the effort to design and build the world's first artificial nuclear reactor at the University of Chicago. In a short period of time, more nuclear reactors were constructed to help make plutonium for atomic weapons.

After the Second World War, nuclear reactors were used primarily for research and plutonium production at first. However, nuclear fission is much more efficient than burning fossil fuels, thus the development of nuclear reactors for power generation was seemingly inevitable. The first use of nuclear power for peacetime energy production occurred on a small scale in the Soviet Union in 1954. England followed in 1956, and the United States in 1957. The Nautilus, the world's first nuclear submarine began operation in 1954, inaugurating Naval nuclear power.

Since then, the use of nuclear power has continued to grow worldwide, in spite of highly publicized accidents at Three Mile Island, Chernobyl, and in Japan. However, this growth has not been without controversy, as various groups argue over the risks that nuclear power generation may entail. Opposed to nuclear power are those who feel that the resultant waste cannot be safely disposed of and that every nuclear reactor is a potential disaster. On the other side of this debate are those who point out that nuclear power has cost far fewer lives than any other form of widely used power generation, that radioactive waste can be safely disposed of, and that we are less sensitive the possible ill effects of radiation than popular opinion might believe. However, this debate remains unresolved and is likely to continue for some time.

Impact

Power production is perhaps the most visible function served by nuclear reactors, in both civilian and military use. But nuclear reactors are also used to manufacture radioactive isotopes for medical treatment and scientific research, and to manufacture plutonium and tritium for nuclear weapons. They are used in scientific research in branches of engineering, geology, biology, and other fields, and some are used to make drinking water out of seawater. The use of nuclear power has generated widespread debate, as noted above, about the role of science and technology in society. In addition, for many reasons the use of nuclear energy for power production has become almost inextricably linked with nuclear weapons. Although this is no more appropriate than linking the petroleum industry with fire bombings, the linkage persists, coloring any debate about nuclear energy.

Power Generation and Desalinization

A nuclear reactor and its cooling towers is perhaps the most recognizable symbol used by environmentalists to represent technology run amok. However, in spite of these objections, it must be admitted that nuclear reactors provide, and will continue to provide an important source of power to the world. France, Japan, Belgium, the United States, and other countries all depend on nuclear power to some extent. This use of nuclear power has contributed to lower use of fossil fuels and reduced emissions of many pollutants in the atmosphere and water. In addition to the civilian use of nuclear power, several nations use nuclear reactors to provide a reliable source of power for naval vessels, which eliminates their dependence on refueling and, in the case of submarines, their ties to the ocean's surface.

Nuclear reactors can also be used to desalinate seawater for use as drinking water or for irrigation. This is done routinely in nuclear-powered naval vessels, all of which generate steam using nuclear power and then use the steam to boil seawater. The steam is pure water that is then condensed and used for drinking, cooking, or other uses. In a similar manner, large nuclear power plants can be used to produce many millions of liters of fresh water per day in places such as the Middle East, where deserts stretch to the edge of the sea.

Isotope Manufacture for Scientific, Medical, or Military Use

All chemical elements have a given number of protons that give them their unique chemical properties. Most elements can contain varying numbers of neutrons, giving them different atomic weights. For example, uranium 238 has 92 protons and 146 neutrons, while uranium 235 has 92 protons and only 143 neutrons. Atoms of an element with different numbers of neutrons are called nuclides or isotopes. Some elements, such as uranium, naturally occur with several isotopes, while other, such as technetium or promethium, do not even occur in nature. It was recognized early in the twentieth century that radiation might be successfully used in research or for medical treatments. After World War II, scientists realized that nuclear reactors could be used to manufacture radioactive isotopes of elements that could be used for scientific research or to diagnose or treat disease. Today, radioactive isotopes of sulfur, hydrogen, carbon, iodine, and phosphorus are routinely used in research, and isotopes of technetium, iodine, gallium, thallium, palladium, and others are routinely used in medical care. Some isotopes, such as iodine 131, can be given to patients to treat cancer or to help image diseased organs. Others, such as radioactive gold, can be inserted into a tumor to irradiate and kill it. Many of these isotopes are generated in nuclear reactors designed and built specifically for this purpose. Recently, particle accelerators have been used to fabricate these radionuclides, too. Nuclear reactors are also used, of course, in the manufacture of isotopes of plutonium and hydrogen for nuclear weapons. It is a peculiar irony that the same process can be used to make isotopes for either war or medicine. To date, however, the number of medical reactors is greater than that of reactors used for military isotope production.

Environmental and Health Concerns

Much of the debate over nuclear energy centers on the environmental effects of continued use of nuclear power. In related arguments, many feel that the risks of using large sources of radiation are simply too great. The response from industry professionals is that radiation is a tool and, like many other tools, it must be treated with respect but not with fear. However, "radiation phobia" has stirred public interest like few other subjects. This fear is reflected in the case of magnetic resonance imaging (MRI), a diagnostic medical apparatus originally called nuclear magnetic resonance imaging (NMR). Since so many people are frightened by anything containing the word "nuclear," a name change was made.

Although radiation professionals disagree with the arguments and fears that are used to justify anti-nuclear power rhetoric, these arguments have been generally effective, regardless of their factual accuracy or validity. One of the largest battlegrounds in this controversy is in the arena of health effects. Some feel that exposure to any amount of radiation is harmful and should be avoided, while others point out that we live in a background radiation field that is higher in some places than others, raising the possibility that some radiation exposure may not cause harm. This group also notes that all living organisms have mutation repair mechanisms that are quite adept at repairing radiation damage, further suggesting that exposure to some levels of radiation may be safe. This is, in fact, a major scientific controversy that remains unresolved. Only time will tell which side of this controversy is correct.

These arguments have successfully hampered efforts to construct repositories for both low- and high-level radioactive wastes in the United States, and have caused some governments to decide to phase out the use of nuclear power altogether. In part, this success may be traced to the continuing association of nuclear power and nuclear weapons in the mind of the general public. However, in many cases, the anti-nuclear power activists have simply been better organized and more vocal than their opponents, winning their arguments almost by default. In any event, this argument is likely to continue for some time, as the long design life and high cost of nuclear power plants makes them unlikely to be shut down on short notice.

P. ANDREW KARAM

Further Reading

Knief, Ronald. Nuclear Engineering: Theory and Technology of Commercial Nuclear Power. New York: Hemisphere Publishing Corporation, 1992.

Murray, Raymond. Understanding Radioactive Waste. Edited by Judith A. Powell. Columbus: Battelle Press, 1994.

Nero, Anthony V. A Guidebook to Nuclear Reactors. Berkeley: University of California Press, 1979.


THE COLD FUSION DEBACLE

In 1989 two relatively unknown scientists in Utah announced that they had discovered a way to generate energy using hydrogen fusion in a small and simple setup that fit on a benchtop. Called "cold fusion" because it did not require the very high temperatures of conventional fusion research, it took the world by surprise.

The promise of fusion power is that it is a nearly limitless source of energy, such as that which powers the Sun. For several decades scientists and engineers have been inching steadily closer to the goal of "ignition," the point at which a fusion reaction will sustain itself long enough to produce more energy than it consumes. Until ignition is reached, fusion will not be a viable source of energy for humanity. Current thinking is that, to reach ignition, temperatures of millions of degrees are needed. To reach these temperatures, facilities have been built costing tens and hundreds of millions of dollars. Many researchers feel that commercial fusion power may be a reality by 2050 or so, but nobody is at all certain because of the great theoretical and engineering difficulties yet to be overcome.

Cold fusion held the promise of changing this paradigm, perhaps making fusion power available within a decade. For several weeks researchers around the world tried to replicate the Utah experiment. To verify fusion is taking place, one would need to see production of both heat and neutrons. Some experiments seemed to show neutron generation but no heat, while others showed the opposite. Finally, after several months, the overwhelming scientific consensus was that cold fusion had not been discovered.


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Nuclear Power

Nuclear power

Nuclear power is any method of doing work that makes use of nuclear fission or nuclear fusion reactions. In its broadest sense, the term refers to both the uncontrolled release of nuclear energy , as in fission or fusion weapons, and to the controlled release of energy, as in nuclear power plants. Most commonly, however, the expression "nuclear power" is reserved for the latter. Approximately 430 nuclear reactors devoted to the manufacture of electricity are operating worldwide.

The world's first exposure to nuclear power came with the detonation of two fission (atomic) bombs over the Japanese cities of Hiroshima and Nagasaki in 1945, events that coincided with the end of World War II. (It has long been assumed by many historians and members of the general public that these atomic bombings were necessary to produce a Japanese surrender and to forestall a United States invasion of Japan; this belief has been disputed by some historians in recent years.) A number of scientists and laypersons perceived an optimistic aspect of these terrible events; they hoped that the power of nuclear energy could be harnessed for human good. Those hopes have been realized, but to only a modest degree. Starting in the 1970s, intense political opposition to nuclear power arose in many nations, including the U.S. Some technical problems associated with the use of nuclear power have never been satisfactorily solved, although proponents of this technology argue that none are insurmountable. After three decades of progress in the development of controlled nuclear power, interest in this energy source has leveled off and, in many nations, declined. Indeed, strong popular opposition to nuclear power exists in many countries today, and nuclear power has become a locus of political struggle, with citizens' groups (supported by some scientists) ranged, typically, against industry and government experts. Nuclear advocates see nuclear opponents as irrationally fearing nuclear technology; nuclear opponents see nuclear advocates as irresponsibly advocating use of unreliable nuclear technology. The nuclear-power issue remains a highly contentious one in many nations.


The nuclear power plant

A nuclear power plant is a system in which some of the energy released by nuclear fission is used to generate electricity. Every such plant contains four fundamental elements: reactor, coolant system, electrical-power generating unit, and safety system.

The source of energy in a nuclear reactor is a fission reaction in which neutrons collide with nuclei of uranium-235 or plutonium-239 (the fuel), causing them to split apart. The products of a fission reaction include not only energy but also new elements (known as fission products) and free neutrons. A constant and reliable flow of neutrons is insured in the reactor by a moderator, which slows down the speed of neutrons, and by control rods, which limit the number of neutrons available in the reactor and, hence, the rate at which fission can occur. In a nuclear weapon, the fission chain reaction, once triggered, proceeds at an exponentially increasing rate, resulting in an explosion; in a nuclear reactor, it proceeds at a steady, controlled rate. Most commercial nuclear power plants are incapable of undergoing an explosive nuclear chain reaction, even should their safety systems fail; this is not true of all research reactors (e.g., some breeder reactors).

Energy produced in the reactor is carried away by means of a coolant such as pressurized water , liquid sodium , or carbon dioxide gas. The circulating coolant absorbs heat in the reactor; once outside the reactor, it is allowed to boil or the heat it contains is used to boil water in a secondary loop. Steam produced in either of these ways is then piped into the electrical generating unit, where it turns the blades of a turbine . The turbine, in turn, turns a generator that produces electrical energy.

The high cost of constructing a modern nuclear power plant—three to four billion dollars, in the U.S.—reflects in part the wide range of safety features needed to protect against various possible mishaps, especially those which could release to the environment any of the plant's inventory of radioactive substances. (Small special-purpose reactors, such as those used to power nuclear submarines or aircraft carriers, have different costs and technical features from the large, land-based reactors used to supply electrical grids.) Some of those features are incorporated into the reactor core itself. For example, all of the fuel in a reactor is sealed in a protective coating made of a zirconium alloy . The protective coating, called a cladding, helps retain heat and radioactivity within the fuel, preventing it from escaping into the plant itself.

Every nuclear plant is also required to have an elaborate safety system to protect against the most serious potential problem of all, loss of coolant. If such an accident were to occur, the reactor core might melt itself down, possibly breaching the structures which contain it and releasing radioactive materials to the rest of the plant and, perhaps, to the outside environment. To prevent such an accident, the pipes carrying the coolant to and from the reactor are required to be very thick and strong. In addition, back-up supplies of the coolant must be available to replace losses in case of a leak.

On another level, the whole plant itself (in much of the world, including Europe and the U.S.) is required to be encased within a dome-shaped containment structure made of steel-reinforced concrete several feet thick. The containment structure is designed to prevent the release of radioactive materials in case of an accident within the reactor. The containment also serves against as a barrier against efforts to deliberately damage the reactor from outside, as by firing shoulder-launched missiles at the reactor or crashing a hijacked airplane into it.

Another safety feature is a system of high-efficiency filters through which all air leaving the building must pass. These filters are designed to trap microscopic particles of radioactive materials that might otherwise be vented to the atmosphere. Other specialized devices and systems have also been developed for dealing with other kinds of accidents in various parts of the power plant.


Types of nuclear power plant

Nuclear power plants differ from each other primarily in the methods they use for transferring heat produced in the reactor to the electricity generating unit. Perhaps the simplest design of all is the boiling water reactor plant (BWR), in which coolant water surrounding the reactor is allowed to boil and form steam. This steam is then piped directly to turbines, which produce rotary mechanical power that turns electrical generators. A very different type of plant is one that was popular in Great Britain for many years; this design that carbon dioxide as a coolant. In this type of plant, carbon dioxide gas passes through the reactor core, absorbs heat produced by fission reactions, and is piped into a secondary system where it gives up some of its energy to water, which begins to boil. This steam is then used to power a turbine and generator.


Safety concerns

In spite of all the systems developed by nuclear engineers, the general public has long had serious concerns about the use of such plants as sources of electrical power. In France, for example, where more than half of the electrical power supply comes from nuclear power plants, public support for nuclear power has declined in recent years; France has now placed a moratorium on the construction of new plants. Germany, which relies on nuclear power for approximately 30% of its electricity, has decided to phase out all of its nuclear power plants as quickly as it can obtain replacement power from other sources. In the U.S., enthusiasm for nuclear power in the 1950s and 1960s faded in the 1970s, giving way to widespread—but often unscientific or ill-founded—public unease about nuclear dangers, a vigorous antitechnology and antinuclear activist movement, and investor concern over the high monetary cost of nuclear power; no new nuclear power plants have been ordered in the U.S. for over 20 years. The nuclear-power industry remains strongest in Asia , where approximately 25 new plants are now under construction.

One concern about nuclear power plants, of course, is an echo of the world's first exposure to nuclear power, the atomic bomb blasts. Many people fear that a nuclear power plant may go out of control and explode like a nuclear weapon. In spite of experts' insistence that such an event is impossible, a few major disasters have perpetuated the fear of nuclear power plants exploding or failing catastrophically in some other mode. Although commercial nuclear power plants cannot explode, they have a demonstrated potential to pass out of the control of their operators, with unpredictable consequences. By far the most serious of those events was the explosion that occurred at the Chernobyl nuclear power plant near Kiev in the Ukraine in 1986.

On April 16 of that year, one of the four power-generating units in the Chernobyl complex exploded, blowing the top off the containment building. (The explosion was caused by hydrogen gas released by the overheating core; it was not a nuclear explosion.) Hundreds of thousands of nearby residents were exposed to dangerous levels of radiation and were evacuated from the area. Radioactive clouds released by the explosion were detected downwind in Scandinavia and western Europe. More than a decade later, the remains of the Chernobyl reactor remain far too radioactive for anyone to spend more than a few minutes near the former reactor core. The Soviet government had, of course, always insisted that such a disaster was impossible. In the U.S., the most famous nuclear incident to date is the accident at the Three Mile Island nuclear plant in 1979. The reactor suffered a partial meltdown that was contained by the giant, pill-shaped steel vessel containing the core; some radioactive gas was released to the environment, and a hydrogen explosion raised pressures inside the containment dome to within a few pounds per square inch of the dome's design pressure . Again, experts had reassured the public that the chances against such an event were literally astronomical—comparable to those of a giant meteor striking a major city.

Critics of nuclear power also worry about the amount of radioactivity released by nuclear power plants on a day-to-day basis. This concern is probably of less importance than is the possibility of a major disaster; studies have shown that nuclear power plants are so well shielded that the amount of radiation to which nearby residents are exposed is no more than that of a person living many miles away. Nevertheless, some epidemiological evidence hints that the small amounts of radioactive material released during routine operation may have detectable medical effects on nearby populations. These claims are, of course, intensely disputed.

In any case, safety concerns in the United States have been serious enough to essentially bring the construction of new plants to a halt in the last decade. Licensing procedures are now so complex and so expensive that few industries are interested in working their way through the bureaucratic maze to construct new plants. However, it should also be noted that orders for new nuclear power plants in the U.S. had practically ceased in the late 1970s, years before the Chernobyl or Three Mile Island accidents or the regulatory response to them. Some analysts argue that the stagnation of the nuclear-power industry should be attributed primarily to economics, rather than to political opposition.


Nuclear waste management

Perhaps the single most troubling issue for the nuclear power industry is waste management . Nuclear wastes can be classified into two general categories, low-level wastes and high-level wastes. The former consist of materials that release a relatively modest level of radiation and/or that will soon decay to a level where they no longer present a threat to humans and the environment. Storing these materials in underground or underwater reservoirs for a few years or in some other system is usually a satisfactory way of handling these materials.

High-level wastes are a different matter. After a period of time, the fuel rods in a reactor are no longer able to sustain a chain reaction and must be removed. These rods are still highly radioactive, however, and present a serious threat to human life and the environment that can be expected to last for tens of thousands of years. These rods and any materials derived from them (as, for example, during chemical dismantling of the rods to extract their plutonium for the production of nuclear weapons or for use as a nuclear fuel), are considered high-level wastes.

For more than two decades, the United States government has been attempting to develop a plan for the storage of high-level nuclear wastes. At one time, the plan was to bury the wastes in a salt mine near Lyons, Kansas. Objections from residents of the area and other concerned citizens made that plan infeasible. More recently, the government decided to construct a huge crypt in the middle of Yucca Mountain in Nevada for the burial of high-level wastes. The government insists that Yucca Mountain is safe and will eventually become the long-term storage site for the nation's high-level radioactive wastes. Until the site is put into full operation, however (if it is), the wastes slated for burial in it are held in "temporary" storage on the grounds nuclear power plants throughout the United States.


History

The first nuclear reactor was built during World War II as part of the Manhattan Project to build an atomic bomb. This reactor was constructed under the direction of Italian physicist Enrico Fermi (1901–1954) in a large room beneath the squash courts at the University of Chicago. Until the day on December 2, 1942, when the Chicago reactor was first put into operation, scientists had relied entirely on mathematical calculations to determine the effectiveness of nuclear fission as an energy source; thus, the scientists who constructed the first reactor were taking an extraordinary chance.

That reactor consisted of alternating layers of uranium and uranium oxide with graphite (carbon) as a moderator. Cadmium control rods were used to control the concentration of neutrons in the reactor. Since the various parts of the reactor were constructed by piling materials on top of each other, the unit was at first known as an "atomic pile."


Nuclear fusion

Many scientists believe that the ultimate solution to the world's energy problems may be in the harnessing of nuclear fusion . A fusion reaction is one in which two small atomic nuclei combine with each other to form one larger nucleus. For example, two hydrogen nuclei may combine with each other to form the nucleus of an atom known as deuterium , or heavy hydrogen. Fusion reactions are responsible for the production of energy in stars. Most commonly, four hydrogen atoms fuse in a series of reactions to form a single helium atom. An important byproduct of these reactions is the release of an enormous amount of energy. By weight, a fusion reaction releases many times more energy than does a fission reaction.

The world was introduced to the concept of fusion reactions in the 1950s when first the United States and then the Soviet Union exploded fusion (hydrogen) bombs. The energy released in the explosion of each such bomb was more than 1,000 times greater than the energy released in the explosion of a single fission bomb such as that used by the U.S. to destroy the city of Hiroshima.

As with fission, scientists and nonscientists alike expressed hope that fusion reactions could someday be harnessed as a source of energy for everyday needs. This line of research has been much less successful, however, than research on fission power plants. In essence, the problem has been to find a way of producing, in a controlled, sustainable fashion, the very high temperatures (millions of degrees Celsius) needed to sustain fusion. Optimistic reports of progress on a fusion power plant appear in the press from time to time, but some authorities now doubt that fusion power will ever be an economic reality.


The future of nuclear power

Proponents of nuclear power argue that a fresh round of power-plant construction should be undertaken to meet growing electricity demand. Coal-fired plants presently produce most of the world's electricity, but release air pollution and greenhouse gases; nuclear power, its advocates argue, does not release these substances. Given the threat of global climate change, it follows that it is of utmost importance to build more nuclear power plants. Opponents of nuclear power respond that greater reductions in air pollution and greenhouse-gas emissions could be achieved by spending the same money on non-nuclear technologies (i.e., efficiency improvements and renewable energy sources such as solar power). They also argue that a massive increase in the number of nuclear power plants bring increased risks for nuclear accidents and for proliferation of nuclear weapons to states that do not as yet have them. Globally, nuclear power is approximately stagnant as of 2003. Whether it is about to undergo the renaissance urged by its advocates or the accelerated phaseout urged by its opponents may not be apparent for some years.

See also Accelerators; Atomic models; Bioterrorism.

Resources

books

Glasstone, Samuel, and Alexander Sesonske. Nuclear ReactorEngineering. 4th ed., 2 vols. New York: Chapman and Hall, 1994.

Richard, L., and Georges Charpak. Megawatts and Megatons:The Future of Nuclear Power. Chicago: University of Chicago Press (Trd), 2002.

World Spaceflight News. 21st Century Complete Guide to Nuclear Power: Encyclopedic Coverage of Power Plants, Reactors, Fuel Processing, NRC and Department of Energy Regulations, Radioactive Waste, New Plant Designs, plusCleanup and Environmental Restoration at Nuclear Weapons Production Sites (Four CD-ROM Set) Progressive Management, 2002.

periodicals

Ahearne, J.F. "Intergenerational issues regarding nuclear power and nuclear waste." Risk Analysis 20 (2001):763-770.

Hoffert, Martin, et al. "Advanced Technology Paths to Global Climate Stability: Energy for a Greenhouse Planet." Science Vol. 298, No. 5595 (Nov. 1, 2002): 981-987.


David E. Newton
Larry Gilman

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cladding

—A material that covers the fuel elements in a nuclear reactor in order to prevent the loss of heat and radioactive materials from the fuel.

Containment

—Any system developed for preventing the release of radioactive materials from a nuclear power plant to the outside world.

Coolant

—Any material used in a nuclear power plant to transfer the heat produced in the reactor core to another unit in which electricity is generated.

Generator

—A device for converting kinetic energy (the energy of movement) into electrical energy.

Neutron

—A subatomic particle that carries no electrical charge and that has a mass of zero.

Nuclear fission

—A reaction in which a larger atomic nucleus breaks apart into two roughly equal, smaller nuclei.

Nuclear fusion

—A reaction in which two small nuclei combine with each other to form one larger nucleus.

Nuclear pile

—The name given to the earliest form of a nuclear reactor.

Turbine

—A device consisting of a series of baffles mounted on a wheel around a central shaft used to convert the energy of a moving fluid into the energy of mechanical rotation.

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