Nuclear Weapons of The United States - Nuclear Weapons Testing

Nuclear Weapons Testing

Main article: Nuclear weapons testing See also: List of nuclear weapons tests of the United States

Between 16 July 1945 and 23 September 1992, the United States maintained a program of vigorous nuclear testing, with the exception of a moratorium between November 1958 and September 1961. A total of (by official count) 1,054 nuclear tests and two nuclear attacks were conducted, with over 100 of them taking place at sites in the Pacific Ocean, over 900 of them at the Nevada Test Site, and ten on miscellaneous sites in the United States (Alaska, Colorado, Mississippi, and New Mexico). Until November 1962, the vast majority of the U.S. tests were atmospheric (that is, above-ground); after the acceptance of the Partial Test Ban Treaty all testing was regulated underground, in order to prevent the dispersion of nuclear fallout.

The U.S. program of atmospheric nuclear testing exposed a number of the population to the hazards of fallout. Estimating exact numbers, and the exact consequences, of people exposed has been medically very difficult, with the exception of the high exposures of Marshallese Islanders and Japanese fisherman in the case of the Castle Bravo incident in 1954. A number of groups of U.S. citizens — especially farmers and inhabitants of cities downwind of the Nevada Test Site and U.S. military workers at various tests — have sued for compensation and recognition of their exposure, many successfully. The passing of the Radiation Exposure Compensation Act of 1990 allowed for a systematic filing of compensation claims in relation to testing as well as those employed at nuclear weapons facilities. As of June 2009 over $1.4 billion dollars total has been given in compensation, with over $660 million going to "downwinders".

A few notable U.S. nuclear tests include:

• The Trinity test on 16 July 1945, was the first-ever test of a nuclear weapon (yield of around 20 kt).
• The Operation Crossroads series in July 1946, was the first postwar test series and one of the largest military operations in U.S. history.
• The Operation Greenhouse shots of May 1951 included the first boosted fission weapon test ("Item") and a scientific test which proved the feasibility of thermonuclear weapons ("George").
• The Ivy Mike shot of 1 November 1952, was the first full test of a Teller-Ulam design "staged" hydrogen bomb, with a yield of 10 megatons. It was not a deployable weapon, however — with its full cryogenic equipment it weighed some 82 tons.
• The Castle Bravo shot of 1 March 1954, was the first test of a deployable (solid fuel) thermonuclear weapon, and also (accidentally) the largest weapon ever tested by the United States (15 megatons). It was also the single largest U.S. radiological accident in connection with nuclear testing. The unanticipated yield, and a change in the weather, resulted in nuclear fallout spreading eastward onto the inhabited Rongelap and Rongerik atolls, which were soon evacuated. Many of the Marshall Islands natives have since suffered from birth defects and have received some compensation from the federal government. A Japanese fishing boat, the Fifth Lucky Dragon, also came into contact with the fallout, which caused many of the crew to grow ill; one eventually died.
• Shot Argus I of Operation Argus, on 27 August 1958, was the first detonation of a nuclear weapon in outer space when a 1.7-kiloton warhead was detonated at 200 kilometers' altitude during a series of high altitude nuclear explosions.
• Shot Frigate Bird of Operation Dominic I on 6 May 1962, was the only U.S. test of an operational ballistic missile with a live nuclear warhead (yield of 600 kilotons), at Christmas Island. In general, missile systems were tested without live warheads and warheads were tested separately for safety concerns. In the early 1960s, however, there mounted technical questions about how the systems would behave under combat conditions (when they were "mated", in military parlance), and this test was meant to dispel these concerns. However, the warhead had to be somewhat modified before its use, and the missile was only a SLBM (and not an ICBM), so by itself it did not satisfy all concerns.
• Shot Sedan of Operation Storax on 6 July 1962 (yield of 104 kilotons), was an attempt at showing the feasibility of using nuclear weapons for "civilian" and "peaceful" purposes as part of Operation Plowshare. In this instance, a 1280-feet-in-diameter and 320-feet-deep crater was created at the Nevada Test Site.