Nuclear weapons tests are experiments carried out to determine the effectiveness, yield and explosive capability of
nuclear weapons. Throughout the twentieth century, most nations that have developed nuclear weapons have tested them. Testing nuclear weapons can yield information about how the weapons work, as well as how the weapons behave under various conditions and how structures behave when subjected to nuclear explosions. Additionally, nuclear testing has often been used as an indicator of scientific and military strength, and many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status by means of a nuclear test.
The first atomic test was detonated by the
United Statesat the Trinity siteon July 16, 1945, with a yield approximately equivalent to 20 kilotons. The first hydrogen bomb, codenamed "Mike", was tested at the Enewetakatoll in the Marshall Islandson November 1 (local date) in 1952, also by the United States. The largest nuclear weapon ever tested was the " Tsar Bomba" of the Soviet Unionat Novaya Zemlyaon October 30, 1961, with an estimated yield of around 50 megatons.
In 1963, all nuclear and many non-nuclear states signed the
Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space. The treaty permitted underground nuclear testing. France continued atmospheric testing until 1974, while China continued up until 1980. The last underground test by the United States was in 1992, the Soviet Union in 1990, the United Kingdom in 1991, and both France and China continued testing until 1996. After adopting the Comprehensive Test Ban Treatyin 1996, all of these states have pledged to discontinue all nuclear testing. Non-signatories Indiaand Pakistanlast tested nuclear weapons in 1998.
The most recent nuclear test was announced by
North Koreaon October 9, 2006. "See 2006 North Korean nuclear testfor more information."
Types of nuclear weapons tests
Nuclear weapons tests have historically been broken into categories (by treaties) reflecting the medium or location of the test: atmospheric, underwater, and underground.
*Atmospheric testing designates explosions which take place in or above the atmosphere. Generally these have occurred as devices detonated on towers, balloons, barges, islands, or dropped from airplanes. A limited number of
high altitude nuclear explosions have also been conducted, generally fired from rockets. Nuclear explosions which are close enough to the ground to draw dirt and debris into their mushroom cloudcan generate large amounts of nuclear falloutdue to irradiation of the debris. High altitude nuclear explosions can generate an electromagnetic pulse, and charged particles resulting from the blast can cross hemispheres to create an auroral display.
*Underwater testing results from nuclear devices being detonated underwater, usually moored to a ship or a barge (which is subsequently destroyed by the explosion). Tests of this nature have usually been conducted to evaluate the effects of nuclear weapons against naval vessels (such as in
Operation Crossroads), or to evaluate potential sea-based nuclear weapons (such as nuclear torpedoes or depth-charges). Underwater tests close to the surface can disperse large amounts of radioactive water and steam, contaminating nearby ships or structures.
*Underground testing refers to nuclear tests which are conducted under the surface of the earth, at varying depths.
Underground nuclear testingmade up the majority of nuclear tests by the United States and the Soviet Union during the Cold War; other forms of nuclear testing were banned by the Limited Test Ban Treatyin 1963. When the explosion is fully contained, underground nuclear testing emits a negligible amount of fallout. However, underground nuclear tests can "vent" to the surface, producing considerable amounts of radioactive debris as a consequence. Underground testing can result in seismicactivity depending on the yield of the nuclear device and the composition of the medium it is detonated in, and generally result in the creation of subsidence craters. [For an overview of the preparations and considerations used in underground nuclear testing, see cite web|url=http://www.globalsecurity.org/wmd/systems/nuke-testing.htm|title="Underground Nuclear Weapons Testing" (Globalsecurity.org)|accessdate=10-19-2006 For a longer and more technical discussion, see cite book|title=The Containment of Underground Nuclear Explosions|url=http://www.nv.doe.gov/library/publications/historical/OTA-ISC-414.pdf|publisher=U.S. Government Printing Office|date=October 1989|location=Washington, D.C.|author=U.S. Congress, Office of Technology Assessment] In 1976, the United States and the USSR agreed to limit the maximum yield of underground tests to 150 kt with the Threshold Test Ban Treaty.
Separately from these designations, nuclear tests are also often categorized by the purpose of the test itself. Tests which are designed to garner information about how (and if) the weapons themselves work are "weapons related" tests, while tests designed to gain information about the effects of the weapons themselves on structures or organisms are known as "weapons effects" tests. Additional types of nuclear tests are possible as well (such as nuclear tests which are also part of
Nuclear-weapons-related testing which purposely results in "no" yield is known as "subcritical testing", referring to the lack of a creation of a
critical massof fissile material. Additionally, there have been simulations of nuclear tests using conventional explosives (such as the Minor ScaleU.S. test in 1985).
The first nuclear weapons test was conducted in Alamogordo, New Mexico, on July 16, 1945, during the
Manhattan Project, and given the codename "Trinity". The test was originally to confirm that the implosion-type nuclear weapon designwas feasible, and to give an idea of what the actual size and effects of a nuclear explosionwould be before they were used in combat against Japan. While the test gave a good approximation of many of the explosion's effects, it did not give an appreciable understanding of nuclear fallout, which was not well understood by the project scientists until well after the atomic bombings of Hiroshima and Nagasaki. The United Statesconducted six nuclear tests before the Soviet Uniondeveloped their first atomic bomb ( Joe 1) and tested it on August 29, 1949. Neither country had very many nuclear weapons to spare at first, and so testing was relatively infrequent (when the U.S. used two weapons for " Operation Crossroads" in 1946, they were detonating over 20% of their current arsenal). However, by the 1950s the United States had established a dedicated test site on its own territory ( Nevada Test Site) and were also using a site in the Marshall Islands( Pacific Proving Grounds) for extensive nuclear testing.
The early tests were used primarily to discern the military effects of nuclear weapons ("Crossroads" had involved the effect of nuclear weapons on a navy, and how they functioned underwater) and to test new weapon designs. During the 1950s these included new hydrogen bomb designs, which were tested in the Pacific, and also new and improved fission weapon designs. The Soviet Union also began testing on a limited scale, primarily in
Kazakhstan. During the later phases of the Cold War, though, both countries developed accelerated testing programs, testing many hundreds of bombs over the last half of the twentieth century.
Nuclear tests can involve many hazards. A number of these were illustrated in the U.S.
Castle Bravotest in 1954. The weapon design tested was a new form of hydrogen bomb, and the scientists underestimated how vigorously some of the weapon materials would react. As a result, the explosion — with a yield of 15 Mt — was over twice what was predicted. Aside from this problem, the weapon also generated a large amount of radioactive nuclear fallout, more than had been anticipated, and a change in the weather pattern caused the fallout to be spread in a direction which had not been cleared in advance. The fallout plume spread high levels of radiation for over a hundred miles, contaminating a number of populated islands in nearby atoll formations (though they were soon evacuated, many of the islands' inhabitants suffered from radiation burns and later from other effects such as increased cancer rate and birth defects), as well as a Japanese fishing boat (" Daigo Fukuryū Maru"). One member of the boat's crew died from radiation sickness after returning to port, and it was feared that the radioactive fish they had been carrying had made it into the Japanese food supply.
Bravo was the worst U.S. nuclear accident, but many of its component problems — unpredictably large yields, changing weather patterns, unexpected fallout contamination of populations and the food supply — occurred during other atmospheric nuclear weapons tests by other countries as well. Concerns over worldwide fallout rates eventually led to the
Partial Test Ban Treatyin 1963, which limited signatories to underground testing. Not all atmospheric tests stopped, however, but because the United States and the Soviet Union in particular stopped testing above ground it cut the number of atmospheric tests down substantially, because about 86% of all nuclear tests were conducted by those two countries. Francecontinued atmospheric testing until 1974, and People's Republic of Chinauntil 1980.
Almost all new nuclear powers have announced their possession of nuclear weapons with a nuclear test. The only acknowledged nuclear power which claims never to have conducted a test was
South Africa(see Vela Incident), which has since dismantled all of its weapons. Israelis widely thought to possess a sizeable nuclear arsenal, though it has never tested. Experts disagree on whether states can have reliable nuclear arsenals — especially ones using advanced warhead designs, such as hydrogen bombs and miniaturized weapons — without testing, though all agree that it is very unlikely to develop significant nuclear innovations without testing. One other approach is to use supercomputers to conduct "virtual" testing, but the value of these simulations without actual test result data is thought to be slim.
Some nuclear testing has been for ostensibly peaceful purposes. These so-called
peaceful nuclear explosionswere used to evaluate whether nuclear explosions could be used for non-military purposes such as digging canals and artificial harbors, or to stimulate oil and gas fields. In most cases the results were too radioactive for use, and the programs proved neither economically sound or politically favorable.
Nuclear testing has also been used for clearly political purposes. The most explicit example of this was the detonation of the largest nuclear bomb ever created, the 50 megaton
Tsar Bomba(with a maximum yield of 100 Mt), by the Soviet Union in 1961. This weapon was too large to be practically used against an enemy target, and it is not thought that any were manufactured except the one detonated in the test.
There have been many attempts to limit the number and size of nuclear tests; the most far-reaching was the
Comprehensive Test Ban Treatyof 1996, which was not ratified by the United States. Nuclear testing has since become a controversial issue in the United States, with a number of politicians saying that future testing might be necessary to maintain the aging warheads from the Cold War. Because nuclear testing is seen as furthering nuclear arms development, many are also opposed to future testing as an acceleration of the arms race.
Nuclear testing by country
The nuclear powers have conducted at least 2,000 nuclear test explosions (numbers are approximated, as some test results have been disputed):
United States: 1,054 tests by official count (involving at least 1,151 devices, 331 atmospheric tests), most at Nevada Test Siteand the Pacific Proving Groundsin the Marshall Islands, with ten other tests taking place at various locations in the United States, including Amchitka Alaska, Colorado, Mississippi, and New Mexico(see Nuclear weapons and the United Statesfor details). [http://nuclearweaponarchive.org/Usa/Tests/index.html]
Soviet Union: 715 tests (involving 969 devices) by official count, [http://nuclearweaponarchive.org/Russia/Sovtestsum.html] most at Semipalatinsk Test Siteand Novaya Zemlya, and a few more at various sites in Russia, Kazakhstan, Turkmenistan, and Ukraine.
France: 210 tests by official count (50 atmospheric, 160 underground [http://www.assemblee-nationale.fr/rap-oecst/essais_nucleaires/i3571.asp] ), 4 atomic atmospheric tests at C.E.S.M.near Reggane, 13 atomic underground tests at C.E.M.O.near In Ekkerin the then-French Algerian Sahara, and nuclear atmospheric tests at Fangataufaand nuclear undersea tests Moruroain French Polynesia. Additional atomic and chemical warfare tests took place in the secret base B2-Namous, near Ben Wenif, other tests involving rockets and missiles at C.I.E.E.S, near Hammaguir, both in the Sahara.
United Kingdom: 45 tests (21 in Australian territory, including 9 in mainland South Australiaat Maralinga and Emu Field, some at Christmas Island in the Pacific Ocean, plus many others in the U.S. as part of joint test series)
* China: 45 tests (23 atmospheric and 22 underground, at
Lop NurNuclear Weapons Test Base, in Malan, Xinjiang)
India: 6 underground tests(including the first one in 1974), at Pokhran.
Pakistan: 6 underground tests, at Ras Koh Hills, Chagai Districtand Kharan Desert, Kharan Districtin Balochistan Province.
North Korea: 1 test at Hwadae-ri.
Additionally, there may have been at least three alleged but unacknowledged nuclear explosions (see list of alleged nuclear tests). Of these, the only one taken seriously as a possible nuclear test is the
Vela Incident, a possible detection of a nuclear explosion in the Indian Oceanin 1979, hypothesized to have been a joint Israeli/ South African test.
From the first nuclear test in 1945 until tests by
Pakistanin 1998, there was never a period of more than 22 months with no nuclear testing. June 1998 to October 2006, when North Korea reported a successful underground nuclear test, was the longest period since 1945 with no acknowledged nuclear tests.
Atomic Testing Museum(in Nevada in the US)
Effects of nuclear explosions
High altitude nuclear explosion
History of nuclear weapons
List of military nuclear accidents(including nuclear weapons accidents)
List of nuclear tests
List of states with nuclear weapons
Live fire exercise
National Technical Means
Nuclear weapons design
Partial Test Ban Treaty
Test Readiness Program
*Gusterson, Hugh. "Nuclear Rites: A Weapons Laboratory at the End of the Cold War." Berkeley, CA: University of California Press, 1996.
*Hacker, Barton C. "Elements of Controversy: The Atomic Energy Commission and Radiation Safety in Nuclear Weapons Testing, 1947-1974." Berkeley, CA: University of California Press, 1994.
*Schwartz, Stephen I. "Atomic Audit: The Costs and Consequences of U.S. Nuclear Weapons." Washington, D.C.: Brookings Institution Press, 1998.
*Weart, Spencer R. "Nuclear Fear: A History of Images." Cambridge, MA: Harvard University Press, 1985.
* Video archive of [http://sonicbomb.com/modules.php?name=Content&pa=showpage&pid=39 US, Soviet, UK, Chines and French Nuclear Testing] at [http://www.sonicbomb.com sonicbomb.com]
* [http://www.pbs.org/wgbh/amex/bomb/maps/index.html Maps of sites tested]
* [http://www.downwinders.org "We're all Downwinders Now"]
* [http://www.aracnet.com/~pdxavets/ Atomic Veterans History Project (United States)]
* [http://www.ga.gov.au/oracle/nukexp_query.html Australian government database of nuclear explosions and tests] Australian
* [http://www.arpansa.gov.au/pubs/reports/sr90pubrep.pdf Australian Nuclear Fallout Strontium 90 survey 1957-58 Child bones] Australian
* [http://www.nhmrc.gov.au/ethics/human/ahec/history/_files/stron90.pdf Australia's program of testing for Strontium 90, between 1957 and 1978, samples of childrens bones taken at autopsy] Australian
* [http://www.anawa.org.au/weapons/monte-bellos.html The Bombing of the Monte Bello Islands] Western Australia
* [http://www.filmaust.com.au/showcase/science/default.asp?content=ss_productionstory Silent Storm - Film about CSIRO scientist Hedley Marston's top-secret fallout experiments] Australian
* [http://www.arpansa.gov.au/RadiationProtection/Factsheets/is_rad.cfm Ionising Radiation and Health] Australian
* [http://www.okgeosurvey1.gov/level2/nuke.cat.index.html Oklahoma Geological Survey Nuclear Explosion Catalog] lists 2,199 explosions by date, country, location, yield etc.
* [http://www.nrdc.org/nuclear/nudb/datab15.asp Table of Known Nuclear Tests Worldwide, from NRDC]
* [http://nuclearweaponarchive.org/Usa/Tests/index.html Gallery of U.S. nuclear tests] (with detailed descriptions of each test series)
* [http://dr.abdulqadeer.8m.net/uk.htm Gallery and short descriptions of UK nuclear tests]
* [http://www.et.byu.edu/~shb34/school/ground-zero.pdf Account of fallout from Nevada Test Site in 1955] (PDF)
* [http://nuclearweaponarchive.org/Russia/Sovtestsum.html Soviet Nuclear Test Summary]
* [http://www.nuclearclaimstribunal.com/ Marshall Islands Nuclear Claims Tribunal]
* [http://www.nuclearfiles.org/menu/key-issues/nuclear-weapons/issues/testing/ Nuclear Testing] at Nuclear Files.org
* [http://video.google.com/videoplay?docid=-7568822525362405530 Film footage of nuclear artillery test]
* [http://www.bikiniatoll.com/whatrad.html What About Radiation on Bikini Atoll?]
Nevada Desert Experience[http://www.nevadadesertexperience.org Nevada Desert Experience]
* [http://www.wslfweb.org Western States Legal Foundation]
* [http://nuclearweaponarchive.org/index.html The Nuclear Weapon Archive]
* [http://www.iaea.org/About/Policy/GC/GC39/GC39Resolutions/English/gc39res-23_en.pdf United Nations Leadup to Comprehensive Nuclear Test Ban Treaty 22 September 1995 General Conference]
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