KINDS OF NUCLEAR WASTE
Nuclear waste is radioactive material that has no immediate use. In the United States nuclear waste generally is divided into two main categories: high-level nuclear waste (HLW) and low-level radioactive waste (LLW). Two less common categories are tailings from uranium mining and milling, and a special category derived from particular aspects of nuclear weapons production and defense-related activities. This latter, less commonly discussed, category is called defense wastes and, because of its makeup, is sometimes called transuranic wastes; it makes up about half of the HLW in the United States. This article focuses on HLW and LLW from nuclear power reactors.
HLW comprises most of the radioactivity associated with nuclear waste. Because that designation can cover radioactive waste from more than one source, the term spent nuclear fuel (SNF) will be used to discuss HLW originating from commercial nuclear reactors. LLW comprises nearly 90 percent of the volume of nuclear waste but little of the radioactivity. Nuclear power reactors produce SNF and most of the nation's LLW, although there are approximately 20,000 different sources of LLW. The name SNF is a bit of a misnomer because it implies that there is no useful material left in the fuel, when in fact some fissionable material is left in it.
CONCERN FOR RADIOACTIVE WASTES
Nuclear waste is a concern due to the levels of radioactivity in it, especially in HLW. Relative to the wastes associated with other major methods of power production, the volumes are small. The concern is for the amount of radioactivity and the time of its duration. The time of radioactivity duration is measured in half-lives (the time required for half of the atoms of a given substance to disintegrate, at which time it becomes the new starting amount with which to begin the count again). Generally LLW not only has lower levels of radioactivity, it also has very low concentrations of long-lived radioactive substances. There are short-lived and long-lived substances in nuclear waste, with half-lives varying from seconds to thousands of years.
In the United States the federal government has taken responsibility for HLW, for both SNF and defense wastes, and for mill and mine tailings. Remediation of the effects of such tailings is well under way. Each state or groups of states (compacts) are responsible for the safe isolation of their own LLW. Three departments of the federal government have prime responsibility for matters related to nuclear waste: Department of Energy (DOE) and its predecessor agencies, which created most of the defense wastes; the Nuclear Regulatory Commission (NRC); and the Environmental Protection Agency (EPA). Regulations regarding care of nuclear wastes are also set by individual state agencies, especially for the LLW.
The federal government not only has responsibility for the safe isolation of SNF but also taxes on the generation of electric power to cover the cost of waste isolation at the rate of one mil/kWh ($0.001/kWh). Although the nuclear waste fund has been folded into the general federal budget, it comes from a special levy that can be changed to accommodate the needs of SNF handling. The office that manages this fund and that is responsible for SNF is in the U.S. DOE and is called the Office of Civilian Waste Management (OCRWM).
ORIGINS OF THE RADIOACTIVITY IN SPENT NUCLEAR FUEL
The nuclear waste generated from production arises when uranium atoms in the fuel split. Nuclear power reactors are fueled with assemblies of rods containing pellets, each about the size of a pencil eraser. About 3 percent of the uranium in these pellets is the fissionable isotope, or form, of uranium, U-235. This is the rarer of the two naturally occurring isotopes of uranium. In nature, the U-235 isotope is found in less than 1 percent of uranium ore—usually 0.5 to 0.7 percent of that ore. After uranium ore is mined and processed, the isotopes are separated, in a process called uranium enrichment. This is not a simple task and is mostly done by a gaseous diffusion plant. Usually the process is stopped when the mixture is about 3 to 3.5 percent of the fissionable form in the mix. (The majority uranium, U-238, is radioactive in its own right, emitting a short-range alpha particle, but it is not fissionable. When the fissionable isotope is extracted from uranium, the remaining material is called depleted uranium and has its own other uses, which will be addressed below.) The exact makeup of the reactor fuel varies some what but is mostly in the form of uranium dioxide, with the uranium being about 3 percent fissionable U-235.
There are three main products in the fissioning of uranium-235: tremendous amounts of energy, neutrons that perpetuate the chain reaction, and two new atoms. The splitting is such that eventually every element found on the periodic chart of the elements is made, especially in the flux of speeding neutrons that induced and perpetuated the fission. Every isotope of every element can be found in the waste. Many of the new isotopes produced are highly unstable—that is, they are radioactive. Many decay in seconds, but some exist in their unstable form much longer, eventually decaying into stable isotopes, though often with intermediates that are also radioactive. This results in radioactive decay chains. These chains of radioactive decay mean that SNF will be radioactive for a long time. It has been estimated that it will be approximately 7,000 years before the level of radioactivity in SNF drops to that of natural radioactivity, that of Earth itself. Since some parts of Earth will be radioactive forever, it can be said that SNF will be radioactive forever. In practice, one must decide what levels of radioactivity to call dangerous. That debate influences decisions about nuclear waste isolation. The debate about what is "safe" is not part of this particular topic. The amended version of the Nuclear Waste Policy Act (NWPA) calls for the safe isolation of HLW from the human environment for 10,000 years.
Besides fission products, the various forms of known but newly formed elements in the spent nuclear fuel, there is a small but significant amount of fissionable, or fissile, material in the SNF. This is quite important. There is some unused, unfissioned U-235 that has become too dilute to use. Like natural uranium ores in which chain reactions do not occur, the fuel will not sustain a chain reaction. But new fissile material also has been made in the intense neutron irradiation. Elements are made that are heavier than naturally occurring uranium, and because of their location on the Periodic Chart are referred to as transuranics. There are isotopes of plutonium and uranium made that can fission. None is present in concentrations that are great enough for a self-sustained chain reaction, but they do represent new fuel. The concentrations of U-239, Pu-239, Pu-240, Pu-241, and some short-lived intermediates are 1–2 percent of the SNF. Some of these are fissile material. Breeder nuclear reactors can be designed and run to produce significant amounts of these isotopes. "The SNF from a breeder reactor is rich in newly produced fissionable isotopes but it must undergo extensive reprocessing to become new reactor fuel. That reprocessing will adjust the concentration of fissionable isotopes and eliminate some of the fission products that tend to quench fission process."
HANDLING OF SNF
Workers wearing gloves can handle nuclear fuel that is being freshly installed into a nuclear reactor. This fuel assembly becomes dangerously and highly radioactive SNF after a short time in an operating nuclear reactor. Upon removal from a reactor (after about 18 months), a spent fuel assembly is now HLW and is far too "hot" thermally and radiologically to handle directly. It is removed remotely with a crane and stored in a bay of cooling water beside the reactor.
HLW still looks like a fuel assembly, a collection of long, skinny rods, each filled with fuel pellets, held in a rack that allows water to pass through and pick up thermal energy. The assembly is kept underwater to cool and also to shield the workers from the longer-range gamma radiation. The water also contains corrosion-inhibiting chemicals as well as chemicals to absorb the few neutrons emitted from lingering atoms of U-235 and other fissile material. Generally a ten-year cooling-off period allows that much of the heat to be emitted and the radioisotopes with short half-lives to have undergone decay. For power plants with limited pool storage there are two choices when the cooling pools are filled: rod consolidation and dry cask storage.
Rod consolidation can permit space saving by dismantling the fuel assembly racks. The rods are still maintained underwater. Rod consolidation is not a routine practice due to issues of heat dissipation and criticality, the possibility of a chain reaction continuing. Dry cask storage is the more common approach for the oldest fuel assemblies and calls for removal of the fuel assemblies from the cooling pool. Designs of the casks vary in detail, but they usually accommodate several spent fuel assemblies in a sealed steel container that is enclosed in a concrete box and/or metal canister. Usually these containers are stored and monitored at the plant site. As with all major operations at nuclear power plants in the United States, hearings before the NRC and the public are conducted on temporary SNF storage. Almost all dry cask storage occurs at the power plant site, where monitoring of the containers can be routine.
ULTIMATE ISOLATION OR REPROCESSING OF SNF
The ultimate disposition of HLW or SNF is a matter of significant importance and is controversial for some. In the United States all HLW, including SNF, has always been a federal responsibility, beginning with the Atoms for Peace Program in the 1950s. A study done by the National Academy of Sciences in 1957 indicated that nuclear waste disposal would not provide insurmountable technical problems and recommended deep geological isolation. Every country that has nuclear power plants has considered the safe isolation or disposal of HLW and has concluded that deep geologic isolation is the safest method. In the United States eight options, including deep-ocean-trench burial, space launches, Antarctica burial, and transformation into materials with shorter half-lives have all been studied. The media into which the HLW is to be isolated varies widely from country to country and include granite, salt beds, and tuffaceous material, welded volcanic ash, most commonly called tuff. United States attention is focused on Yucca Mountain, at the western edge of the Nevada Test Site, the location of above-and below-ground nuclear weapons testing in the past. It is a mountain of tuff.
YUCCA MOUNTAIN, NEVADA
The amended version of the NWPA has determined that only Yucca Mountain is to be characterized as a possible geologic repository for SNF and possibly some defense waste. It is approximately 100 miles northwest of Las Vegas, Nevada. The planned location of the SNF is approximately 1,000 feet above any groundwater and about the same distance below the surface. Characterization studies of the viability of Yucca Mountain are under way and have been since the early 1990s. The NWPA also prohibits studies of granite as a host rock. (Canada is considering SNF isolation in granite. Most of the eastern half of the United States is on granite.) Both private and governmental leaders—most concerned about tourism—in the state of Nevada are resisting the Yucca Mountain characterization studies. Furthermore, although the majority of scientists studying the mountain find no clear problems, a few find fault with the studies ad the site as a possible repository. The most difficult part of the studies involves predictions about the behavior of the tuff environment for 10,000 years and beyond. The fact that Yucca Mountain is in a region of ancient volcanic activity complicates the assessments. Most attention is devoted to water movement through the tuff and the vulnerability of the underlying earth to undergo any significant "stretching" in the foreseeable future. The Yucca Mountain project has a website listed in the bibliography for this article, with photos and links to scientific data being accumulated as well as links to opposition points of view.
Yucca Mountain, if it becomes the site for the isolation of SNF, will be laced with tunnels, waste in storage casks and monitoring equipment. A waiting period is planned while better isolation alternatives are sought. If Yucca Mountain is not used, it is to be refilled with the tuff material removed earlier. In the United States the SNF that would be isolated in Yucca Mountain would be waste that has not been reprocessed; it would be material that has come out of nuclear reactors and has been cooled at the plant site.
Since the amount of fissile material in the fuel assemblies is only about 3 percent of the uranium present, it is obvious that there cannot be a large amount of radioactive material in the SNF after fission. The neutron flux produces some newly radioactive material in the form of uranium and plutonium isotopes. The amount of this other newly radioactive material is small compared to the volume of the fuel assembly. These facts prompt some to argue that SNF should be chemically processed and the various components separated into nonradioactive material, material that will be radioactive for a long time, and material that could be refabricated into new reactor fuel. Reprocessing the fuel to isolate the plutonium is seen as a reason not to proceed with this technology in the United States.
Congress has decided that reprocessing will not be practiced in this country so that we will not be in the plutonium production business. This seems like a safe thing to do since this action will minimize terrorism threats. Reprocessing generates chemi cal wastes but greatly reduces the volume of the highly radioactive waste. It also isolates plutonium and unused fuel for possible use as new fuel. Reprocessing means that the volume of material calling for long-term isolation is reduced by one-third what it would have been before reprocessing.
THE VOLUME OF SNF
If one just concentrates on the radioactive material in SNF, the volume is very small, especially compared to waste from other power production practices. However, one can only discuss the separated radioactive material if it has undergone extensive reprocessing. If SNF is to be isolated, as in a place such as Yucca Mountain, with perhaps 70 miles of tunnels, the volume is that of the interior of this minor mountain. Isolation of up to 100,000 metric tons of SNF in Yucca Mountain means that for the United States, approximately all the SNF made to date and that expected in the operating lifetime of all current reactors can be put there. Approximately 2,000 metric tons of SNF are produced each year in the United States. Waste volume and placement depend on the amount of compaction and consolidation at the sites. The plans for the Yucca Mountain present a realistic and understandable picture of the volume of SNF.
A useful perspective may be seen about the amount of SNF by comparing it to the volume of other waste streams associated with power production. More than half of the electricity made in the United States comes from coal burning, where each large power plant generates bottom and fly ash in volumes measured in acre-feet annually. Each of these plants generates its own small mountain of ash. The gaseous wastes from coal burning and from methane and oil burning result in tons of carbon dioxide daily. This carbon dioxide is an infrared active gas and is thought by many to be contributing to global warming and climate change phenomena. The wastes associated with nuclear power are small in comparison, this is not surprising, considering the tremendous power in the nucleus of an atom.
LOW-LEVEL RADIOACTIVE WASTE
The other major category of nuclear waste, LLW, is generally that which is neither HLW nor the transuranic part of defense waste. Generally, LLW is generated in private and public labs, hospitals, and commercial enterprises and can involve lab clothing, paper, packing material and radioactive isotopes used in medical procedures, both diagnostic and therapeutic. Significant amounts of LLW are associated with defense wastes, but mostly are isolated at U.S. DOE facilities. Many pharmaceutical products require extensive use of radioactive tracers. Academic sources are minor. The major sources of LLW in volume and amount of radioactivity are nuclear power plants. Aside from the decommissioning of nuclear power plants, the volume of LLW is decreasing every year. This is because new technologies have become available to separate the radioactive material from that which is not radioactive. Also, generators of LLW are being more selective in the work that they do so that they generate less LLW each year. These changes have become about partly because the cost of isolating LLW has increased.
The LLW from nuclear power plants contains ion exchange resins as well as clothing, tools, and chemicals. Ion exchange resins, which comprise the majority of this LLW, are used to filter the water circulated in nuclear power plants. The ion exchange resins isolate and trap dissolved materials, much of which can be radioactive. Approximately three-fourths of commercially or privately generated LLW is in the form of the contaminated plastic beads that make up ion exchange resins.
The NRC categorizes LLW into Class A, B, or C. The wastes in Classes A and B contain materials that decay to safe levels in about 100 years. Class C wastes will require about 500 years to reach safe levels and contain mostly ion-exchange resins and filters. (There is a minor amount of LLW referred to as beyond class C material.) The majority of LLW is dry and is stored in cardboard or wooden crates. Some are in metal drums. LLW is most likely given shallow burial, compared to the deep geological isolation required for HLW. A difficult issues in LLW disposed involves a small amount of "mixed waste," where the radiological material is mixed with chemically or biologically hazardous substances. The contaminated chemicals may require special handling, since hazardous chemical wastes do not decay as do radioactive materials. In addition, a small amount of LLW consists of animal carcasses or waste and also needs special handling. Currently there are three commercial sites handling LLW for most of the states and compacts. The largest volume of LLW will come with the decommissioning and dismantling of nuclear power plants. In 1995 nearly 700,000 cubic feet of LLW were handled at commercial sites in the United States.
LLW is placed in sturdy, sealed containers. At the isolation site these containers are first put in concrete and/or metal vaults or bunkers and then buried in shallow trenches before being covered with backfill. Some of these are then paved over to prevent rainwater from entering the waste.
The LLW Forum coordinates information and regulations among and between the various state compacts and states. It maintains a website that is overseen by the Idaho Operations Office, which is part of the National Engineering Lab in Idaho. Although LLW is a responsibility of each compact, or of state for the LLW generated in that state, the regulations governing it are those of the U.S. DOE, the NRC, and the EPA. The regulations governing its isolation allow individual states to set additional requirements for handling the material. After being established, any particular compact can refuse to receive the LLW from other states.
OTHER RADIOACTIVE-WASTE SITES
The Waste Isolation Pilot Plant (WIPP) is in an excavated salt cavern in southern New Mexico, twenty-seven miles from Carlsbad. The WIPP site is 2,000 yards underground, and defense waste is being placed. There are plans to place there about 6 million cubic feet of material there containing fewer than five million curies of radio activity.
The most technically difficult category of HLW is that belonging to the U.S. DOE at its major plutonium production facilities in Hanford, Washington, and at the Savannah River facility near Aiken, South Carolina. Just sampling the material for characterization presents problems since much of it consists of radioactive acidic liquids. The rest of it in sludge form, and some is solid. A plant for the vitrification of that part of the material that can be made into glass bars is in operation at the Savannah River facility. The vitrification process encases the waste in glass "logs" to immobilize it and make it easier to handle. A conservative estimate is that it will take decades to clean up these facilities.
NUCLEAR WASTE IN OTHER COUNTRIES
The United States has the most radioactive nuclear waste and the most complicated array of waste types. Reprocessing of SNF is also practiced in some countries. Although costly, this practice reduces the volume of HLW requiring deep geologic disposal. (In the wide variety of elements in the fission products making up SNF, some are toxic heavy metals.) Reprocessing and the general lack of economy of scale in many other countries help to explain why there is less activity or progress related to HLW isolation elsewhere. Interim monitored retrievable storage is generally the focus of activity abroad. Different philosophies and cultures also mean that a wide variety of approaches to the problem are found. Some feel that the generation deriving the benefits of nuclear power is the one responsible for a solution. Others say that succeeding generations may have better technology or ideas about this problem than current generations: Current generations should not do anything permanent, committing future generations to the solutions seen by people living today. Among the technology that wold drastically reduce the cost of cleanup of waste sites robotics.
All the countries that produce nuclear waste have chosen the same alternative for the ultimate disposition of HLW, deep geological isolation, and they did so independently of one another. The United States has the most radioactive nuclear waste and the most complicated array of waste types of any "nuclear" country. Only in the United States can one find the same economy of scale for waste handling. Thus, it leads the world in most activities aimed at safe isolation. In France, Japan, and Great Britain, however, reprocessing is routinely practiced. Those countries reprocess HLW for many other countries. As mentioned above, reprocessing is not currently allowed in the United States.
France and Germany, local protests have dramatically slowed the choice of a final isolation site. As a result, interim storage is widely practiced in other countries. In Sweden, the waste is mixed in molten copper. The radioactive waste is immobilized in copper logs that are easily handled and stored in large underground caverns until a more permanent isolation is chosen. While most feel that those making the waste have the primary responsibility for its isolation, in Sweden they do not wish to commit future generations to solutions that might be vitrified; the glass "logs" are in concrete bunkers.
In the former U.S.S.R. vast areas of the country are contaminated by poor handling of nuclear waste, especially from that associated with the manufacturer of weapons. Some radioactive waste, especially from nuclear submarines has been isolated at the bottom of the Baltic Sea by the former Russian Navy.
Transportation of HLW is among the most immediate concerns for the general public. Most experts agree that nuclear wastes, especially SNF, are being kept in places not intended for long-term storage and they acknowledge that the problem must be addressed. There is general agreement that SNF should be kept far from population centers (where the electricity is generated and used) and should be kept in a dry place, since water the most likely medium for its movement into the human environment. Movement of SNF is necessary, most likely by rail or roadway. Groups of U.S. DOE and state regulators are working together, continually revising transportation plans and designing and testing transportation casks. Some wish to see a combined transportation and burial cask, while others want very different qualities in each sort of cask. Planners build on past experience handling and transporting radiological materials. Extensive experience was gained when the first commercial nuclear power plant, at Shippingport, Pennsylvania, was decommissioned in 1989 and the reactor vessel was moved to Hanford, Washington, where it is buried.
Despite the challenges, many see nuclear waste issues as being mostly political and social. There is a growing awareness that technical answers alone will not solve the political and social concerns. Some consider nuclear waste issues small in comparison to the volume and challenges associated with other kinds of wastes, whether generated by power plants or other human activities.
Donald H. Williams
American Nuclear Society. <http://ans.org>.
American Nuclear Society. (annual). High Level Radioactive Waste Management: Proceedings for the International Topical Meeting of the American Nuclear Society and the American Society of Civil Engineers. Chicago: American Nuclear Society.
Murray, R. L. (1994). Understanding Radioactive Waste, 4th ed. Columbus, OH: Battelle Press.
Physics Today. (1998). 50(6).
Radwaste Magazine: Progress in Radioactive Waste Management and Facility Remediation. (monthly).
Savage, D., ed. (1995). The Scientific and Regulatory Basis for the Geological Disposal of Radioactive Waste. New York: Wiley & Sons.
Study Committee Home Page. <http://www.studycommittee.org>.
U.S. Department of Energy. (1996) "Integrated Data Base Report 1995: U.S. Spent Nuclear Fuel and Radioactive Waste Inventories, Projections and Characteristics, DOE/RW-0006, Revision 12." Washington, DC: Author.
U.S. Department of Energy: Office of Civilian Radioactive Waste Management. The Yucca Mountain Project. <http://www.ymp.gov>.
U.S. Environmental Protection Agency. Yucca Mountain Home Page. <http://www.epa.gov.radiation/yucca>.
Disposal of nuclear waste has been a contentious issue both in the United States and elsewhere in the world. Difficult questions are involved, including: (1) where should one put the waste? (2) How long must such waste be stored before it does not pose a hazard to society? (3) What confidence can be placed in estimates of long-term confinement, and how great are the uncertainties? Because of the differing views on these topics and their complexity, their treatment here will necessarily be limited.
The focus here will be high-level radioactive waste produced at nuclear power plants. Excluded is any discussion of defense-related radioactive waste, or low-level radioactive waste generated from nuclear power, medical applications, industrial applications, and research. The basic issues for these other types of waste are related to and can be informed by the present analysis. There are, as well, books and lengthy articles providing more comprehensive treatments, which are included in the references.
Nuclear Waste Itself
In the United States there are two types of radioactive waste produced at nuclear reactors: low-level waste (LLW) and high-level waste (HLW). While low-level nuclear waste represents most of the waste volume, high-level waste represents most of the radioactivity. For this reason HLW presents the major problem.
High-level waste in the United States (and also Sweden and Finland) comprises the used nuclear fuel elements, called spent fuel. In France, Great Britain, and Japan, where fuel is reprocessed to remove unused uranium fuel and plutonium (which represents 95 percent of the material in spent fuel), HLW primarily includes fission products and long-lived radioactive materials called actinides. (Russia and China are developing reprocessing capability, and Germany, the Netherlands, Switzerland, and Belgium reprocess their spent fuel elsewhere.) These are incorporated into radiation-resistant glass to produce blocks that can be placed into a temporary storage facility or a permanent underground facility. In the United States there is no reprocessing, so the HLW is in the form of solid fuel elements that contain all the products mentioned above.
High-Level Waste Disposal Facilities
In the early twenty-first century, all spent fuel in the United States was stored on the sites of the nuclear power reactors because no long-term storage facilities were available. This included sixty-four reactor sites in thirty-one states. When spent fuel is initially removed from the reactor it generates considerable heat from radioactive decay so that initial storage is in pools of water. After the spent fuel has been stored for a minimum of five years it can be moved to specially designed steel and concrete above-ground casks, approved by the Nuclear Regulatory Commission (NRC), that rely on air cooling to remove the heat. No accidents with spent fuel elements have occurred in which radiation has been released to the public. The HLW generated at a reactor in forty or more years of operation can be stored on-site, indicating that the volume of HLW generated at each reactor is quite low. Indeed, as Kristin S. Shrader-Frechette (1993) has argued at length, aboveground monitored retrieval storage may be a defensible option.
Political Processes for High-Level Radioactive Waste Disposal
The U.S. Department of Energy (DoE) has the ultimate responsibility for permanent disposal of high-level waste in the United States. Based on a strong consensus of international expert opinion, the best place for permanent storage of HLW is in a geologic repository deep underground in an environment that is both geologically stable and exceptionally dry. The Nuclear Waste Policy Act (NWPA) of 1982 chartered the DoE with the responsibility to develop a permanent geological repository for HLW. The NWPA also charged the Environmental Protection Agency (EPA) with the responsibility for developing environmental standards and the NRC with responsibility for evaluating whether the repository design submitted by the DoE meets these standards.
Initially three potential sites were identified for detailed study as possible repositories. The law was amended in 1987, however, to focus on a single site at Yucca Mountain in Nevada. Through these amendments, Congress also established an independent advisory group of experts, the U.S. Nuclear Waste Technical Review Board (NWTRB), to evaluate the technical and scientific validity of the DoE's efforts to develop a repository. The NWTRB issues annual reports to Congress and the secretary of energy with their evaluations.
Under the DoE plan, solid nuclear waste would be placed in extremely durable containers—called waste packages—that would be put into deep underground tunnels in dry, stable, volcanic rock. The safety concern is that, over time, enough water would come in contact with the waste to cause the release of radioactive elements and the transport of these materials to the water table. The proposed Yucca Mountain repository is about 1,000 feet below the land surface and 1,000 feet above the water table.
In 2002, after fifteen years of study, the DoE issued reports concluding that the Yucca Mountain site was suitable for a geologic repository for HLW. The DoE that year submitted to the president a recommendation for approval to proceed with the development of the Yucca Mountain repository. The NWTRB did not make a judgment regarding this recommendation because acceptability involves public policy issues that are beyond the board's mandate. The board did note that no scientific or technical factor had been identified that would eliminate Yucca Mountain as a permanent repository site, but also that there were gaps in data and basic understanding that result in important uncertainties in performance estimates. In essence, although sophisticated models have been used to predict whether the waste can be safely stored to meet EPA and NRC criteria, there remain uncertainties in the accuracy of the models and in the predictions. How much certainty is required to make a decision? And are the criteria for leak rates or confinement times the appropriate ones to use? These critical issues are difficult for experts to evaluate and for the public to understand. In the end, a political decision on acceptability is required.
Notwithstanding the concerns indicated above, President George W. Bush approved the recommendation and sent it to Congress, which then voted to approve it as well. The DoE's goal is to begin storing spent fuel beginning in 2010. A minimum of fifty years has been specified for studies of the repository performance before it can be closed. The DoE then has to apply to the NRC for a license to close the repository. During this time the repository will be monitored to enhance the understanding of the processes taking place in the repository, to determine if the behavior is in agreement with predictions of the models, and to correct any problems that are identified.
The approvals to proceed with the repository at Yucca Mountain were highly controversial. The citizens and government of Nevada have strongly opposed the repository, regardless of whether the site is suitable. They contend that the benefits of nuclear power are primarily obtained elsewhere in the nation, but Nevada is expected to accept the risks for any kind of problem or accident related to handling or disposing of spent fuel at the repository. Because this is a national issue it is probably inevitable that there would be a conflict between federal and state interests. In December 2001 Nevada filed suit in federal court against the decision to proceed based on several technical and legal issues. In July 2004 the U.S. Court of Appeals ruled that the U.S. Environmental Protection Agency (EPA) illegally set its radiation release standards for groundwater for the proposed high-level radioactive waste dump. Two months later, the Nevada attorney general initiated a new lawsuit, claiming the DOE lacked the authority to make many of the decisions required to continue the project.
Some opponents of Yucca Mountain repository argued that outstanding scientific questions remained that should be answered before one could be reasonably confident that the safety criteria can be met. They called for further research and a resolution of some of the technical uncertainties. Antinuclear groups, such as Greenpeace, expressed opposition to any solution to the waste problem, including Yucca Mountain. This strikes at the core issue of acceptable risk and how the United States, as a society, is to deal with wastes. Not doing anything is simply a different kind of solution and may not be the best one for society. Furthermore, the waste is a by-product of a technology that was introduced for the benefit of society, in this case to produce electricity without the environmental problems of fossil fuels. Ultimately to gain the benefit it is necessary to address and solve the waste problem. But can one find a solution in which all the stakeholders are satisfied? Certainly Nevada and its citizens were not satisfied. Whether the Yucca Mountain decision achieves fairness and acceptability will continue to be debated by groups with differing opinions.
Another issue that affects public acceptability is whether spent fuel can be shipped safely to the site or whether such shipments pose an unacceptable hazard. What about accidents or terrorist attacks? The transport of spent fuel would occur on railway cars or in trucks in specially designed casks. These casks, designed to meet requirements of both the NRC and the U.S. Department of Transportation, are tested to demonstrate they can withstand crashes, fire, water immersion, and puncture. A truck carrying such a cask was crashed at 80 miles per hour into a concrete barrier. Although the cask was damaged it did not leak. Moreover, shipments of spent fuel are not new. From the early 1960s to the early 2000s, about 3,000 such shipments covered more than 2.7 million kilometers (1.7 million miles) of U.S. roads and railways without any radioactive material being released as a result of an accident. Regarding terrorist acts, there are factors that make such shipments undesirable targets. The casks are massive and weigh many tons; and the trucks and trains that carry them are guarded and tracked via satellite communication. Even a shoulder-mounted rocket would be unlikely to crack the cask, and if it did little radioactivity would be released to the environment because the fuel is solid. The implication by anti–Yucca Mountain groups that the transported fuel represents a serious hazard is not supported by experience or analyses.
The plutonium that is in the spent fuel presents a different type of issue. Reprocessing reduces the volume of waste by about 75 percent and slashes the amount of time that the waste needs to be stored; reprocessed HLW will return to the radioactivity levels of mined ore within a couple thousand years, whereas spent fuel requires considerably longer because of the plutonium. Furthermore, the plutonium that is recovered through reprocessing is incorporated into fuel, thus reducing the total inventory of plutonium. But reprocessing also carries risks of proliferation, because reprocessed plutonium might be diverted or stolen to produce nuclear weapons. Initially the United States was committed to reprocessing, but in the late 1970s President Jimmy Carter decided not to proceed with reprocessing in the hope that other nations would follow the U.S. example. This would have limited the opportunity to clan-destinely obtain plutonium that was produced in nuclear power reactors. Carter's effort proved unsuccessful because neither the Europeans nor the Japanese showed any interest in following suit. Independent of the security argument over reprocessing there is no economic incentive in the United States to revive reprocessing unless the price of uranium fuel rises significantly.
High-Level Waste in Other Countries
High-level waste disposal is required for every country that has nuclear power. Active research programs for deep geologic storage are under way in many countries, including Sweden, Finland, Germany, France, Switzerland, Great Britain, Russia, and China. Only Finland has committed politically to a specific disposal site. Other nations are carrying out research at one or more sites and have yet to complete the selection process. In December 2003 the European Union decided to evaluate the possibility of regional repositories, primarily to assist smaller countries. Based on the experience in the United States and in many of the above nations, it may be a difficult and contentious process before a final decision is reached.
While critical issues have been decided in creating the Yucca Mountain repository there are many outstanding issues still to be resolved. Scientific studies that support critical engineering design decisions are still needed. The issuance of an NRC license, which will include extensive public hearings and most likely legal challenges, is also ahead. Furthermore, numerous construction activities must be completed. With expected appeals, it will be a daunting task for the Yucca Mountain repository to be ready to receive spent fuel by 2010.
Finally, creating a permanent repository will be a very expensive undertaking. As of September 2002, the fund to pay for design, development, and ultimate storage of spent fuel has accumulated $23 billion and grows by $1 billion per year because of the Congressionally mandated 0.1 cent per kilowatt-hour charge on nuclear-generated power.
Nevertheless, the full cost to society of safely disposing of nuclear waste must factor in the damages avoided or benefits because of the noncarbon emissions from nuclear power. In other words, depending upon how the damages to the environment from fossil fuel plants are valued, the cost of disposing of nuclear waste may be a real bargain.
Future generations will judge whether the nation acted responsibly and appropriately in its decision regarding the disposal of spent fuel at an HLW repository at Yucca Mountain. If the decision is reversed, long-term monitoring would be needed to assure that this repository has solved a problem and not created a new one.
EDWARD H. KLEVANS DARRYL L. FARBER
Carter, Luther J. (1987). Nuclear Imperatives and Public Trust: Dealing with Radioactive Waste. Washington, DC: Resources for the Future.
Murray, Raymond L. (2003). Understanding Radioactive Waste, 5th edition, ed. Kristin L. Manke. Columbus, OH: Battelle Press.
Organisation for Economic Co-operation and Development. Nuclear Energy Agency. (1995). The Environmental and Ethical Basis of Geological Disposal of Long-Lived Radioactive Wastes. Paris: Author. Also available from http://www.nea.fr/html/rwm/reports/1995/geodisp.html.
"Office of Civilian Radioactive Waste Management." U.S. Department of Energy. Available from http://www.ocrwm.doe.gov/. Includes information on the Yucca Mountain Project, including reports relating to the recommendation submitted to President George W. Bush.
"Radioactive Wastes." World Nuclear Association. Available from http://www.world-nuclear.org/info/inf60.htm.
"RadWaste.org." Herne Data Systems. Available from http://radwaste.org/. General website with a great deal of information on radioactive waste.
U.S. Nuclear Waste Technical Review Board. "Report to the Secretary of Energy and the Congress." Available from http://www.nwtrb.gov/reports/reports.html. Report from March 2003 summarizing the board's activities during 2002.
Nuclear Waste Policy Act (1982)
Nuclear Waste Policy Act (1982)
Joseph P. Tomain
Regulation of nuclear power was transferred from military to civilian control with the passage of the Atomic Energy Act of 1954. Although the dangers of radioactivity were known before the act, it was not until the passage of the Nuclear Waste Policy Act (NWPA) (P.L. 97-425, 96 Stat. 2201) that the back end of the fuel cycle was addressed.
HAZARDS OF NUCLEAR WASTE
The central problem of nuclear waste derives from the facts that radioactivity may last for many thousands of years and must be contained so it no longer presents a significant risk to human health or to the environment. Nuclear waste is generated from many sources. The mining and milling process generates radioactive debris known as mill tailings, which constitute a low-level source of radioactivity. Mill tailings are addressed in the Uranium Mill Tailings and Radiation Control Act of 1978. Radioactive materials are also generated from medical and industrial uses. Certain low-level wastes are addressed in the Low-Level Radioactive Waste Policy Amendments Act of 1985. By far the largest source of radioactive waste results from the generation of electricity by commercial nuclear reactors, which produce tens of thousands of tons of spent nuclear fuel. The primary problem at commercial nuclear power sites is that temporary storage facilities for spent fuel are full and require expansion until a permanent disposal site is completed. In addition, thousands of tons of nuclear waste are generated through military uses.
The NWPA requires the Department of Energy (DOE) to dispose of nuclear waste safely and with environmentally acceptable methods in a geologic formation with the intent to bury designated waste at underground disposal sites. The National Academy of Sciences began looking for disposal sites in the mid-1950s. Preliminary screening identified four large potentially promising regions of either salt domes or bedded salt mines. These formations offer relatively safe space for nuclear waste because they restrict the flow of water that can spread radioactivity.
In 1970 the Atomic Energy Commission identified specific disposal sites, and in the late 1970s, the National Waste Terminal Storage Program helped develop the technology necessary for repository licensing, construction, operation, and closure. In 1980 the Department of Energy, after engaging in an environmental impact statement process, selected mined geologic repositories as the preferred storage space for spent commercial nuclear fuel. All of those efforts culminated in the Nuclear Waste Policy Act of 1982.
PROVISIONS OF THE NWPA
Although the federal government has the primary responsibility for permanent disposal of such waste, the costs of disposal are intended to be the responsibility of generators and owners of the waste and spent fuel. The act also recognizes an important role for public and state participation. The reason for the broad participation of other sovereigns is because repositories must be located somewhere and choosing a site is, as correctly predicted, controversial. Thus, the statute involves the secretary of energy, the president, Congress, the states, Native American tribes, and the general public in the site selection process.
In 1983 the Department of Energy located nine sites in six states as potential repository sites. Based on initial studies, the president approved three sites in Hannaford, Washington; Defsmith County, Texas; and Yucca Mountain, Nevada. In 1987 Congress amended the Nuclear Waste Policy Act, directing the Department of Energy to study only Yucca Mountain, which is now the designated site awaiting NRC approval. The selection of Yucca Mountain has not been without controversy. In Nevada v. Watkins the United States Court of Appeals for the Ninth Circuit rejected the state's challenge of legislative authority for this decision. Pursuant to NWPA, Nevada exercised a veto over site selection, and that veto was overridden in both houses of Congress.
CHALLENGES TO THE ACT
Since the passage of the NWPA, the siting program has faced a number of challenges, including legislative mandates, regulatory modification, fluctuating funding levels, and the evolving and often conflicting needs and expectations of various and diverse interest groups. The challenges from scientists, citizens, legislators, and governors all complicated the process, generating increased Congressional dissatisfaction.
The identification and scheduling of disposal sites have not been finalized as of the date of this writing. In 1997 Congress directed the DOE to complete a "viability assessment" of the Yucca Mountain site. The viability assessment was codified into law by the Energy and Water Development Appropriations Act, which directed that no later than September 3, 1998, the secretary of energy provide to the president and Congress a viability assessment of the Yucca Mountain site. The viability assessment must include:
- preliminary design concept of the repository and waste package
- total system performance assessment describing the probable behavior of the repository relative to overall system performance
- plan and cost estimate for remaining work required to retain a license
- an estimate of costs to construct and operate the repository
The NWPA envisioned that site selection would be completed in 1998 and that a facility would then be available to accept waste. That date, of course, has passed. The site characterization process and the politics involved have become increasingly complex. In 1987 the DOE announced an opening date in 2003, a date that also was not met. In 1989 a further delay was announced by the Department of Energy to 2010.
In December 1998 the DOE submitted its assessment to the president and Congress. The viability assessment indicated that the site required further study, although it supported a recommendation of the site to the president. The Department of Energy now seeks final authorization from the Nuclear Regulatory Commission to develop the site as a repository. Consequently, Yucca Mountain is currently earmarked for receipt of waste upon Nuclear Regulatory Commission approval.
Nuclear wastes are currently located in 129 sites in thirty-nine different states, which include seventy-two commercial nuclear reactor sites, a commercial storage site, forty-three research sites, and ten Department of Energy sites. Once the major disposal site is finalized, the secretary of energy is authorized to enter into contracts with owners and generators of spent nuclear fuel for storage. In addition, transportation plans must be undertaken in an environmentally safe and sound manner. Although the commercial nuclear power market has been stagnant for nearly two decades, nuclear waste disposal issues continue to be an important part of the nation's energy planning.
See also: Atomic Energy Acts; Hazardous Materials Transportation Act.
Bosselman, Fred, Jim Rossi, and Jacqueline Lang Weaver. Energy, Economics and the Environment. New York: Foundation Press, 2000.
Carter, Luther J. Nuclear Imperatives and Public Trust: Dealing with Radioactive Waste. Washington, DC: Resources for the Future, Inc., 1987.
Tomain, Joseph P. Nuclear Power Transformation. Bloomington: Indiana University Press, 1987.
Union of Concerned Scientists. Safety Second: The NRC and America's Nuclear Power Plant. Bloomington: Indiana University Press, 1987.
Zillman, Donald N. "Nuclear Power." In Energy Law and Policy for the 21st Century, ed. The Energy Law Group. Denver, CO: Rocky Mountain Mineral Law Foundation, 2000.
Nuclear waste has many sources that are grouped into two broad categories. The first category is nuclear fuel-cycle waste, which consists of any waste arising from the separation and processing of uranium to fabricate nuclear fuel, from nuclear reactors used for any purpose, and from any sub-sequent uses of radioactive materials contained in nuclear fuel or produced in a reactor. Uses of nuclear reactors include generation of electricity; production of plutonium for use in nuclear weapons; production of radioisotopes for use in medicine, industry, or commerce; and research and development. The different types of nuclear fuel-cycle waste include the following:
- High-level radioactive waste arises mainly when spent nuclear fuel from a reactor is chemically reprocessed to remove plutonium for use in nuclear weapons. This highly hazardous waste contains high concentrations of radioactive fission products, such as strontium-90, iodine-131, and cesium-137, and long-lived radionuclides heavier than uranium, such as plutonium and americium.
- Spent nuclear fuel, which resembles high-level waste, is waste if it is not chemically reprocessed. Spent fuel from nuclear power reactors in the United States is not reprocessed at the present time, but reprocessing is carried out in other countries.
- Transuranic waste arises mainly when plutonium removed from spent fuel is used in fabricating nuclear weapons. This waste mostly contains plutonium and other heavy radionuclides, such as americium, in lower concentrations than in high-level waste or spent fuel, although there are exceptions.
- Mill tailings are the very large volumes of residues containing naturally occurring radionuclides that arise mainly when uranium is chemically separated from ores for use in nuclear fuel. The radiation hazard of mill tailings is due mainly to the elevated levels of radium and high emanation rates of radon gas.
- Low-level radioactive waste includes any nuclear fuel-cycle waste other than high-level waste, spent fuel, transuranic waste, and mill tailings. Low-level waste arises in many activities, including operations at nuclear facilities; uses of reactorproduced radioisotopes in medicine, industry, or commerce; cleanup of radioactively contaminated sites; and research and development. Most low-level waste contains relatively low concentrations of radionuclides, but some wastes can be as hazardous as high-level waste or spent fuel.
The second broad category includes any nuclear waste other than the nuclear fuel-cycle wastes described above. Nuclear waste in this category thus includes naturally occurring or acceleratorproduced radioactive material (NARM). Waste containing naturally occurring radioactive material, such as potassium-40, uranium, thorium, or radium, does not include mill tailings. Important wastes of this type include spent radium sources, waste from removal of radionuclides from drinking water, residues from processing of various ores or minerals and other industrial activities, coal ash from electricity generation, and phosphate waste from fertilizer production. Accelerator-produced waste includes accelerator targets any waste arising in the production of medical radioisotopes in accelerators (such as cyclotrons), and subsequent uses of these radioisotopes. Accelerator-produced waste contains mainly short-lived radionuclides and often resembles low-level radioactive waste. In general, NARM waste, especially waste containing naturally occurring radioactive material, has received less attention than nuclear fuel-cycle waste.
David C. Kocher
(see also: Not In My Backyard [NIMBY]; Nuclear Power; Risk Assessment, Risk Management )
nu·cle·ar waste • n. radioactive waste material, for example from the use or reprocessing of nuclear fuel.
nuclear waste: see radioactive waste.