Soviet Nuclear Test Summary
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The Soviet Union became the second nation in the world to detonate a nuclear device on 29 August 1949 (the U.S. had previously exploded eight devices). Between that date, and 24 October 1990 (the date of the last Soviet, or Russian, test) the Soviet Union conducted 715 nuclear tests, by official count. As with the U.S., the term "test" may indicate the near simultaneous detonation of more than one nuclear exposive device, so the actual number of devices exploded is 969 (for comparison, the U.S. has conducted 1056 tests/explosions using at least 1151 devices).
Not included are "hydronuclear tests", what are tests involving fissile material with yields (by design) of less than 1 ton. The Soviet Union conducted about 100 of these tests, with the yields remaining below 100 kg. Explosive device fizzles with yields of less than 1 ton are included however.
The Soviet Union conducted 124 "peaceful nuclear explosions" compared to 35 such tests in the U.S Plowshare program.
From first to last test, the Soviet test program lasted 41 years, 1 month, and 26 days. During this period testing activity was not continuous. A gap of 2 years and 26 days separated the first and second tests, due to the problems experienced in developing the nuclear weapons infrastructure. Four voluntary moratoriums were observed. The first was from November 1958 to August 1961, when the U.S. and the U.K. also abstained form any testing. This moratorium was abrogated on 31 August 1961 by Khruschev, with nuclear testing commencing the next day. This test series was the largest in world history, as measured by explosive yield. The second moratorium lasted from 26 December 1962 to 14 March 1964, while the Atmospheric Test Ban was being negotiated (signed 5 August 1963), and to prepare the test program for large scale underground testing. The third and fourth moratoriums extended from August 1985 to October 1987, and from November 1989 to October 1990, as the Soviet Union under Gorbachev sought to reach accomodation with the U.S. The test program was terminated by a fifth moratorium, which has now been made permanent with the signing of the Comprehensive Test Ban Treaty (CTBT).
For a complete list of all Soviet nuclear tests conducted during the era of atmospheric testing see Soviet Atmospheric Tests