Thresher Disaster

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THRESHER DISASTER. Launched in July 1960 and commissioned in August 1961, the USS Thresher was the lead boat for a revolutionary class of "hunter-killer attack" submarines designed to destroy Soviet ballistic missile submarines. A strong steel hull, although thinner than that of most submarines, permitted the Thresher to withstand greater damage and operate significantly deeper than its counterparts. Its advanced design incorporated a reduced-profile conning tower to increase maneuverability while providing maximum stealth and a highly sensitive, bow-mounted sonar array to detect the enemy at greater distances. The Thresher's torpedo room was located aft of the conning tower, and the tubes angled upward to utilize SUBROC, or submarine rocket, torpedoes. More importantly, a nuclear reactor provided the submarine its power and extended its operational range. During an exhaustive two-year sea trial period, the Thresher suffered an unanticipated reactor shutdown and a collision with a tugboat in addition to the usual "shakedown" problems. After additional tests, the submarine began a nine-month overhaul in August 1962.

On 9 April 1963, the Thresher returned to sea and initiated a series of routine dives to "test depth," or maximum safe operating depth, estimated at approximately 1,000 feet. On 10 August the crew reported "minor difficulties" at 700 feet and attempted an emergency surface. The Thresher never reappeared, sinking in 8,500 feet of water, with all 129 men aboard killed. The submarine imploded from the extreme pressure at these depths, leaving only small fragments of wreckage to be located or recovered. Tests conducted at the time of the accident (and again in the 1980s) revealed that the nuclear reactor had remained intact and an environmental disaster averted. The ensuing inquiry into the navy's first loss of a nuclear-powered vessel suspected improperly welded brazed joints as leading to Thresher's demise, but the official cause remained unknown. The disaster sobered proponents of a nuclear navy, who subsequently instituted the SUBSAFE program to review nuclear submarine construction and operations to ensure that safety would keep pace with technological innovation.


Duncan, Francis. Rickover and the Nuclear Navy: The Discipline of Technology. Annapolis, Md.: Naval Institute Press, 1990.

Polmar, Norman. Death of the Thresher. Philadelphia: Chilton, 1964.

Rockwell, Theodore. The Rickover Effect: How One Man Made a Difference. Annapolis, Md.: Naval Institute Press, 1992.

Derek W.Frisby

See alsoNavy, United States ; Nuclear Power .