Nuclear weapons testing

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Nuclear weapons tests are experiments carried out to determine the effectiveness, yield, and explosive capability of nuclear weapons. Throughout the 20th century, most nations that developed nuclear weapons 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 personnel, structures, and equipment behave when subjected to nuclear explosions. 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 nuclear device was detonated as a test by the United States at the Trinity site on July 16, 1945, with a yield approximately equivalent to 20 kilotons of TNT. The first thermonuclear weapon technology test of engineer device, codenamed "Mike", was tested at the Enewetak atoll in the Marshall Islands on November 1, 1952 (local date), also by the United States. The largest nuclear weapon ever tested was the "Tsar Bomba" of the Soviet Union at Novaya Zemlya on October 30, 1961, with the largest yield ever seen (as of January 2016), an estimated 50–58 megatons.

In 1963, three (UK, US, Soviet Union) of the four nuclear states 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, and China continued until 1980. Neither has signed the treaty.[1]

Underground tests in the United States continued until 1992 (its last nuclear test), the Soviet Union until 1990, the United Kingdom until 1991, and both China and France until 1996. In signing the Comprehensive Test Ban Treaty in 1996, these states have pledged to discontinue all nuclear testing. However, as of December 2013, the treaty has not yet entered into force because of failure to be signed/ratified by eight specific countries. Non-signatories India and Pakistan last tested nuclear weapons in 1998.

In January 2013, North Korea had announced that it planned to conduct further tests involving rockets that can carry satellites as well as nuclear warheads "to strike and attack the United States".[2] The most recent nuclear test occurred in January 2016 in North Korea.


Four major types of nuclear testing: 1. atmospheric, 2. underground, 3. exoatmospheric, and 4. underwater

Nuclear weapons tests have historically been divided into four categories reflecting the medium or location of the test.

  • Atmospheric testing designates explosions that take place in the atmosphere. Generally these have occurred as devices detonated on towers, balloons, barges, islands, or dropped from airplanes, and also those which are only buried far enough to intentionally create a surface-breaking crater. Nuclear explosions that are close enough to the ground to draw dirt and debris into their mushroom cloud can generate large amounts of nuclear fallout due to irradiation of the debris. This definition of atmospheric is used in the Limited Test Ban Treaty, which banned this class of testing along with exoatmospheric and underwater.
  • Underground testing refers to nuclear tests conducted under the surface of the earth, at varying depths. Underground nuclear testing made 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 Treaty in 1963. True underground tests are intended to be fully contained and emit a negligible amount of fallout. Unfortunately these nuclear tests do occasionally "vent" to the surface, producing from nearly none to considerable amounts of radioactive debris as a consequence. Underground testing almost by definition result in seismic activity which magnitude depends 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.[3] 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.
    Underground testing also falls into two physical categories: tunnel tests which happen in generally horizontal tunnel "drifts", and shaft tests in vertically drilled holes.
  • Exoatmospheric testing refers to nuclear tests conducted above the atmosphere. The test devices are lifted on rockets. These high altitude nuclear explosions can generate a nuclear electromagnetic pulse (NEMP) when they occur in the ionosphere, and charged particles resulting from the blast can cross hemispheres following geomagnetic lines of force 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 particles in water and steam, contaminating nearby ships or structures, though they generally do not create fallout other than very local to the explosion.

Salvo tests

Another way to classify nuclear tests are by the number of explosions which constitute the test. The treaty definition of a salvo test is:

"In conformity with treaties between the United States and the Soviet Union, a salvo is defined, for multiple explosions for peaceful purposes, as two or more separate explosions where a period of time between successive individual explosions does not exceed 5 seconds and where the burial points of all explosive devices can be connected by segments of straight lines, each of them connecting two burial points, and the total length does not exceed 40 kilometers. For nuclear weapon tests, a salvo is defined as two or more underground nuclear explosions conducted at a test site within an area delineated by a circle having a diameter of two kilometers and conducted within a total period of time of 0.1 second."[4]

The USSR has exploded up to eight devices in a single salvo test; Pakistan's second and last official test exploded four different devices. Almost all lists in the literature are lists of tests; in the lists in Wikipedia, (for example, Operation Cresset has separate items for Cremino and Caerphilly, which together constitute a single test) the lists are of explosions.


Separately from these designations, nuclear tests are also often categorized by the purpose of the test itself.

  • Weapons-related tests are designed to garner information about how (and if) the weapons themselves work. Some serve to develop and validate a specific weapon type. Others test experimental concepts or are physics experiments meant to gain fundamental knowledge of the processes and materials involved in nuclear detonations.
  • Weapons effects tests are designed to gain information about the effects of the weapons on structures, equipment, organisms and the environment. They are mainly used to assess and improve survivability to nuclear explosions in civilian and military contexts, tailor weapons to their targets, and develop the tactics of nuclear warfare.
  • Safety experiments are designed to study the behavior of weapons in simulated accident scenarios. In particular, they are used to verify that a (significant) nuclear detonation cannot happen by accident. They include one-point safety tests and simulations of storage and transportation accidents.
  • Nuclear test detection experiments are designed to improve the capabilities to detect, locate, and identify nuclear detonations, in particular to monitor compliance with test-ban treaties. In the United States these tests are associated with Operation Vela Uniform before the Comprehensive Test Ban Treaty stopped all nuclear testing among signatories.
  • Peaceful nuclear explosions were conducted to investigate non-military applications of nuclear explosives. In the United States these were performed under the umbrella name of Operation Plowshare.

Aside from these technical considerations, tests have been conducted for political and training purposes. Tests also often serve multiple purposes.

Alternatives to full-scale testing

Sub-critical experiment at the Nevada Test Site.

Hydronuclear tests study nuclear materials under the conditions of explosive shock compression. They can create sub-critical conditions, or supercritical conditions with yields ranging from negligible all the way up to a substantial fraction of full weapon yield.[5]

Critical mass experiments determine the quantity of fissile material required for criticality with a variety of fissile material compositions, densities, shapes, and reflectors. They can be sub-critical or super-critical, in which case significant radiation fluxes can be produced. This type of test resulted in several criticality accidents.

Sub-critical (or cold) tests are any type of tests involving nuclear materials and possibly high-explosives (like those mentioned above) that purposely result in no yield. The name refers to the lack of creation of a critical mass of fissile material. They are the only type of tests allowed under the interpretation of the Comprehensive Nuclear-Test-Ban Treaty tacitly agreed to by the major atomic powers.[6][7] Sub-critical tests continue to be performed by the United States, Russia, and the People's Republic of China, at least.[8][9]

Subcritical test executed by the United States include:[10][11][12]

Subcritical Tests
Name Date Time (UT[13]) Location Elevation + Height Notes
A series of 50 tests January 1, 1960 Los Alamos National Lab Test Area 49 35°49′22″N 106°18′08″W / 35.82289°N 106.30216°W / 35.82289; -106.30216 2,183 metres (7,162 ft) - 20 metres (66 ft) Series of 50 tests during US/USSR joint nuclear test ban.[14]
Odyssey NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft)
Trumpet NTS Area U1a-102D 37°00′40″N 116°03′31″W / 37.01099°N 116.05848°W / 37.01099; -116.05848 1,222 metres (4,009 ft) - 190 metres (620 ft)
Kismet March 1, 1995 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 293 metres (961 ft) Kismet was a proof of concept for modern hydronuclear tests; it did not contain any SNM (Special Nuclear Material - Plutonium or Uranium).
Rebound July 2, 1997 10:--:-- NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 293 metres (961 ft) Provided information on the behavior of new plutonium alloys compressed by high pressure shock waves; same as Stagecoach but for the age of the alloys.
Holog September 18, 1997 NTS Area U1a.101A 37°00′37″N 116°03′32″W / 37.01036°N 116.05888°W / 37.01036; -116.05888 1,222 metres (4,009 ft) - 290 metres (950 ft) Holog and Clarinet may have switched locations.
Stagecoach March 25, 1998 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 290 metres (950 ft) Provided information on the behavior of aged (up to 40 years) plutonium alloys compressed by high pressure shock waves.
Bagpipe September 26, 1998 NTS Area U1a.101B 37°00′37″N 116°03′32″W / 37.01021°N 116.05886°W / 37.01021; -116.05886 1,222 metres (4,009 ft) - 290 metres (950 ft)
Cimarron December 11, 1998 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 290 metres (950 ft) Plutonium surface ejecta studies.
Clarinet February 9, 1999 NTS Area U1a.101C 37°00′36″N 116°03′32″W / 37.01003°N 116.05898°W / 37.01003; -116.05898 1,222 metres (4,009 ft) - 290 metres (950 ft) Holog and Clarinet may have switched places on the map.
Oboe September 30, 1999 NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Oboe 2 November 9, 1999 NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Oboe 3 February 3, 2000 NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Thoroughbred March 22, 2000 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 290 metres (950 ft) Plutonium surface ejecta studies, followup to Cimarron.
Oboe 4 April 6, 2000 NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Oboe 5 August 18, 2000 NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Oboe 6 December 14, 2000 NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Oboe 8 September 26, 2001 NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Oboe 7 December 13, 2001 NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Oboe 9 June 7, 2002 21:46:-- NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Mario August 29, 2002 19:00:-- NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 290 metres (950 ft) Plutonium surface studies (optical analysis of spall). Used wrought plutonium from Rocky Flats.
Rocco September 26, 2002 19:00:-- NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 290 metres (950 ft) Plutonium surface studies (optical analysis of spall), followup to Mario. Used cast plutonium from Los Alamos.
Piano September 19, 2003 20:44:-- NTS Area U1a.102C 37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.05877 1,222 metres (4,009 ft) - 290 metres (950 ft)
Armando May 25, 2004 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 290 metres (950 ft) Plutonium spall measurements using x-ray analysis. Video here:
Step Wedge April 1, 2005 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft) April–May 2005, a series of mini-hydronuclear experiments interpreting Armando results.
Unicorn August 31, 2006 01:00:-- NTS Area U6c 36°59′12″N 116°02′38″W / 36.98663°N 116.0439°W / 36.98663; -116.0439 1,222 metres (4,009 ft) - 190 metres (620 ft) "…confirm nuclear performance of the W88 warhead with a newly-manufactured pit." Early pit studies.
Thermos January 1, 2007 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft) Feb-6 thru May 3, 2007, 12 mini-hydronuclear experiments in thermos-sized flasks.
Bacchus September 16, 2010 NTS Area U1a.05? 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft)
Barolo A December 1, 2010 NTS Area U1a.05? 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft)
Barolo B February 2, 2011 NTS Area U1a.05? 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft)
Castor September 1, 2012 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft) Not even a subcrit, contained no plutonium; a dress rehearsal for Pollux.
Pollux December 5, 2012 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft) A subcritical test with a scaled down warhead mockup. A video of this test is here:
Leda June 15, 2014 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft) Like Castor, the plutonium was replaced by a surrogate; this is a dress rehearsal for the later Lydia. The target was a weapons pit mock-up. A video of this test is here:
Lydia ??-??-2015 NTS Area U1a 37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983 1,222 metres (4,009 ft) - 190 metres (620 ft) Expected to be a plutonium subcritical test with a scaled down warhead mockup.

There have also been simulations of the effects of nuclear detonations using conventional explosives (such as the Minor Scale U.S. test in 1985). The explosives might be spiked with radioactive materials to simulate fallout dispersal.


File:Phoenix en route to North Vietnam, 1967.jpg
The Phoenix of Hiroshima (foreground) in Hong Kong Harbor in 1967, was involved in several famous anti-nuclear protest voyages against nuclear testing in the Pacific.
The 18,000 km2 expanse of the Semipalatinsk Test Site (indicated in red), attached to Kurchatov (along the Irtysh river). The site comprised an area the size of Wales.[15]

The first atomic weapons test was conducted near 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 design was feasible, and to give an idea of what the actual size and effects of a nuclear explosion would 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 States conducted six atomic tests before the Soviet Union developed their first atomic bomb (RDS-1) and tested it on August 29, 1949. Neither country had very many atomic 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 was also using a site in the Marshall Islands (Pacific Proving Grounds) for extensive atomic and nuclear testing.

The early tests were used primarily to discern the military effects of atomic weapons (Crossroads had involved the effect of atomic 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 20th century.

In 1954 the Castle Bravo fallout plume spread dangerous levels of radiation over an area over 100 miles long, including inhabited islands.

Atomic and nuclear tests can involve many hazards. Some of these were illustrated in the U.S. Castle Bravo test 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 did the crew of the Japanese fishing boat Daigo Fukuryū Maru. One crewman 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.

Because of concerns about worldwide fallout levels, the Partial Test Ban Treaty was signed in 1963. Above are the per capita thyroid doses (in rads) in the continental United States resulting from all exposure routes from all atmospheric nuclear tests conducted at the Nevada Test Site from 1951–1962.

Castle 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 Treaty in 1963, which limited signatories to underground testing. Not all countries stopped atmospheric testing, but because the United States and the Soviet Union were responsible for roughly 86% of all nuclear tests, their compliance cut the overall level substantially. France continued atmospheric testing until 1974, and China until 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. Israel is widely thought to possess a sizable nuclear arsenal, though it has never tested, unless they were involved in Vela. 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 codes need to be validated against test data.

There have been many attempts to limit the number and size of nuclear tests; the most far-reaching is the Comprehensive Test Ban Treaty of 1996, which has not, as of 2013, been ratified by eight of the "Annex 2 countries" required for it to take effect, including 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 opposed to future testing as an acceleration of the arms race.

In total nuclear test megatonnage, from 1945–92, 520 atmospheric nuclear explosions (including 8 underwater) have been conducted with a total yield of 545 megatons,[16] with a peak occurring in 1961-62, when 340 megatons were detonated in the atmosphere by the United States and Soviet Union.[17] while the estimated number of underground nuclear tests conducted in the period from 1957 to 1992 is 1,352 explosions with a total yield of 90 Mt.[18]

Nuclear testing by country

File:Rael Nuclear use locations world map.png
Over 2,000 nuclear tests have been conducted, in over a dozen different sites around the world. Red Russia/Soviet Union, blue France, light blue United States, violet Britain, black Israel, orange China, yellow India, brown Pakistan, green North Korea and light green (territories exposed to nuclear bombs)
File:Operation Crossroads Baker Edit.jpg
"Baker Shot", part of Operation Crossroads, a nuclear test by the United States at Bikini Atoll in 1946

The nuclear powers have conducted more than 2,000 nuclear test explosions (numbers are approximate, as some test results have been disputed):

There may also 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 Ocean in 1979.

From the first nuclear test in 1945 until tests by Pakistan in 1998, there was never a period of more than 22 months with no nuclear testing. June 1998 to October 2006 was the longest period since 1945 with no acknowledged nuclear tests.

A summary table of all the nuclear testing that has happened since 1945 is here: Worldwide nuclear testing counts and summary.

Graph of nuclear testing

Treaties against testing

There are many proposed anti-nuclear explosion treaties, such as the Partial Nuclear Test Ban Treaty, and the Comprehensive Nuclear Test Ban Treaty. Most of these treaties were passed because scientists in many different countries noticed spikes in radiation levels in civilian areas[citation needed]. Nuclear testing involving humans also contributed to the formation of the treaties, and examples can be seen in the following articles:

The Partial Nuclear Test Ban treaty makes it illegal to detonate any nuclear explosion anywhere except underground, in order to reduce atmospheric fallout. Most countries have signed and ratified the Partial Nuclear Test Ban which went into effect in October 1963. Of the nuclear states, France, China, and North Korea have never signed the Partial Nuclear Test Ban Treaty.[26]

The 1996 Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans all nuclear explosions everywhere, including underground. For that purpose, the Preparatory Commission of the Comprehensive Nuclear-Test-Ban Treaty Organization is building an international monitoring system with 337 facilities located all over the globe. 85% of these facilities are already operational.[27] As of May 2012, the CTBT has been signed by 183 States, of which 157 have also ratified. However, for the Treaty to enter into force it needs to be ratified by 44 specific nuclear technology-holder countries. These "Annex 2 States" participated in the negotiations on the CTBT between 1994 and 1996 and possessed nuclear power or research reactors at that time. The ratification of eight Annex 2 states is still missing: China, Egypt, Iran, Israel and the United States have signed but not ratified the Treaty; India, North Korea and Pakistan have not signed it.[28]

The following is a list of the treaties applicable to nuclear testing:

Name Agreement date In force date In effect today? Notes
Unilateral USSR ban March 31, 1958 March 31, 1958 no USSR unilaterally stops testing provided the West does as well.
Bilateral testing ban August 2, 1958 August 2, 1958 no USA agrees; ban begins on 31 October 1958, 3 November 1958 for the Soviets, and lasts until abrogated by a USSR test on 1 September 1961.
Antarctic Treaty System December 1, 1959 June 23, 1961 yes Bans testing of all kinds in Antarctica.
Partial Nuclear Test Ban Treaty (PTBT) August 5, 1962 October 10, 1963 yes Ban on all but underground testing.
Outer Space Treaty January 27, 1967 October 10, 1967 yes Bans testing on the moon and other celestial bodies.
Treaty of Tlatelolco February 14, 1967 April 22, 1968 yes Bans testing in South America and the Caribbean Sea Islands.
Nuclear Non-proliferation Treaty January 1, 1968 March 5, 1970 yes Bans the proliferation of nuclear technology to non-nuclear nations.
Seabed Arms Control Treaty February 11, 1971 May 18, 1972 yes Bans use of nuclear weapons in international waters.
Strategic Arms Limitation Treaty (SALT I) January 1, 1972 no A five-year ban on installing launchers.
Anti-Ballistic Missile Treaty May 26, 1972 August 3, 1972 no Restricts ABM development; additional protocol added in 1974; abrogated by the USA in 2002.
Agreement on the Prevention of Nuclear War June 22, 1973 June 22, 1973 yes Promises to make all efforts to promote security and peace.
Threshold Test Ban Treaty July 1, 1974 December 11, 1990 yes Prohibits higher than 150 kt for underground testing.
Peaceful Nuclear Explosions Treaty (PNET) January 1, 1976 December 11, 1990 yes Prohibits higher than 150 kt, or 1500kt in aggregate, testing for peaceful purposes.
Moon Treaty January 1, 1979 January 1, 1984 no Bans use and emplacement of nuclear weapons on the moon and other celestial bodies.
Strategic Arms Limitations Treaty (SALT II) June 18, 1979 no Limits strategic arms. Kept but not ratified by the US, abrogated in 1986.
Treaty of Rarotonga August 6, 1985  ? Bans nuclear weapons in South Pacific Ocean and islands. US never ratified.
Intermediate Range Nuclear Forces Treaty (INF) December 8, 1987 June 1, 1988 yes Eliminates Intermediate Range Ballistic Missiles (IRBMs). Implemented by 1 June 1991.
Treaty on Conventional Armed Forces in Europe November 19, 1990 July 17, 1992 yes Bans categories of weapons, including conventional, from Europe. Russia notified signatories of intent to suspend, 14 July 2007.
Strategic Arms Reduction Treaty I (START I) July 31, 1991 December 5, 1994 no 35-40% reduction in ICBMs with verification. Treaty expired 5 December 2009, renewed (see below).
Treaty on Open Skies March 24, 1992 January 1, 2002 yes Allows for unencumbered surveillance over all signatories.
US unilateral testing moratorium October 2, 1992 October 2, 1992 no George. H. W. Bush declares unilateral ban on nuclear testing.[29] Extended several times, not yet abrogated.
Strategic Arms Reduction Treaty (START II) January 3, 1993 January 1, 2002 no Deep reductions in ICBMs. Abrogated by Russia in 2002 in retaliation of US abrogation of ABM Treaty.
Southeast Asian Nuclear-Weapon-Free Zone Treaty (Treaty of Bangkok) December 15, 1995 March 28, 1997 yes Bans nuclear weapons from southeast Asia.
African Nuclear Weapon Free Zone Treaty (Pelindaba Treaty) January 1, 1996 July 16, 2009 yes Bans nuclear weapons in Africa.
Comprehensive Nuclear Test Ban Treaty (CTBT) September 10, 1996 yes (effectively) Bans all nuclear testing, peaceful and otherwise. Strong detection and verification mechanism (CTBTO). US has signed and adheres to the treaty, though has not ratified it.
Treaty on Strategic Offensive Reductions (SORT, Treaty of Moscow) May 24, 2002 June 1, 2003 no Reduces warheads to 1700-2200 in ten years. Expired, replaced by START II.
START I treaty renewal April 8, 2010 January 26, 2011 yes Same provisions as START I.

Compensation for victims

Over 500 atmospheric nuclear weapons tests were conducted at various sites around the world from 1945 to 1980. As public awareness and concern mounted over the possible health hazards associated with exposure to the nuclear fallout, various studies were done to assess the extent of the hazard. A Centers for Disease Control and Prevention/ National Cancer Institute study claims that nuclear fallout might have led to approximately 11,000 excess deaths, most caused by thyroid cancer linked to exposure to iodine-131.[30]

  • United States: As of March 2009, the U.S. is the only nation that compensates nuclear test victims. Since the Radiation Exposure Compensation Act of 1990, more than $1.38 billion in compensation has been approved. The money is going to people who took part in the tests, notably at the Nevada Test Site, and to others exposed to the radiation.[31][32]
  • France: In March 2009, the French Government offered to compensate victims for the first time and legislation is being drafted which would allow payments to people who suffered health problems related to the tests. The payouts would be available to victims' descendants and would include Algerians, who were exposed to nuclear testing in the Sahara in 1960. However, victims say the eligibility requirements for compensation are too narrow.[31]
  • United Kingdom: There is no formal British government compensation program. However, nearly 1,000 veterans of Christmas Island nuclear tests in the 1950s are engaged in legal action against the Ministry of Defense for negligence. They say they suffered health problems and were not warned of potential dangers before the experiments.[31]
  • Russia: Decades later, Russia offered compensation to veterans who were part of the 1954 Totsk test. However, there was no compensation to civilians sickened by the Totsk test. Anti-nuclear groups say there has been no government compensation for other nuclear tests.[31]
  • China: China has undertaken highly secretive atomic tests in remote deserts in a Central Asian border province. Anti-nuclear activists say there is no known government program for compensating victims.[31]

Milestone nuclear explosions

The following list is of milestone nuclear explosions. In addition to the atomic bombings of Hiroshima and Nagasaki, the first nuclear test of a given weapon type for a country is included, and tests which were otherwise notable (such as the largest test ever). All yields (explosive power) are given in their estimated energy equivalents in kilotons of TNT (see TNT equivalent). Putative tests (like Vela Incident) have not been included.

Date Name Yield (kT) Country Significance
1945-07-16 Trinity 18–20 USA First fission device test, first plutonium implosion detonation
1945-08-06 Little Boy 12–18 USA Bombing of Hiroshima, Japan, first detonation of an enriched uranium gun-type device, first use of a nuclear device in military combat.
1945-08-09 Fat Man 18–23 USA Bombing of Nagasaki, Japan, second and last use of a nuclear device in military combat.
1949-08-29 RDS-1 22 USSR First fission weapon test by the USSR
1952-10-03 Hurricane 25 UK First fission weapon test by the UK
1952-11-01 Ivy Mike 10,400 USA First cryogenic fusion fuel "staged" thermonuclear weapon, primarily a test device and not weaponized
1952-11-16 Ivy King 500 USA Largest pure-fission weapon ever tested
1953-08-12 Joe 4 400 USSR First fusion weapon test by the USSR (not "staged")
1954-03-01 Castle Bravo 15,000 USA First dry fusion fuel "staged" thermonuclear weapon; a serious nuclear fallout accident occurred; largest nuclear detonation conducted by United States
1955-11-22 RDS-37 1,600 USSR First "staged" thermonuclear weapon test by the USSR (deployable)
1957-05-31 Orange Herald 720 UK Largest boosted fission weapon ever tested. Intended as a fallback "in megaton range" in case British thermonuclear development failed.
1957-11-08 Grapple X 1,800 UK First (successful) "staged" thermonuclear weapon test by the UK
1960-02-13 Gerboise Bleue 70 France First fission weapon test by France
1961-10-31 Tsar Bomba 50,000 USSR Largest thermonuclear weapon ever tested—scaled down from its initial 100 Mt design by 50%
1964-10-16 596 22 PR China First fission weapon test by the People's Republic of China
1967-06-17 Test No. 6 3,300 PR China First "staged" thermonuclear weapon test by the People's Republic of China
1968-08-24 Canopus 2,600 France First "staged" thermonuclear weapon test by France
1974-05-18 Smiling Buddha 12 India First fission nuclear explosive test by India
1998-05-11 Pokhran-II 60[33] India First potential fusion/boosted weapon test by India; first deployable fission weapon test by India
1998-05-28 Chagai-I 40[34] Pakistan First fission weapon (boosted) test by Pakistan
1998-05-30 Chagai-II 20[34] Pakistan Second fission weapon (boosted) test by Pakistan
2006-10-09 2006 North Korean nuclear test 2-12 North Korea First fission plutonium-based device tested by North Korea
2009-05-25 2009 North Korean nuclear test 1-20 North Korea Successful fission device tested by North Korea
2013-02-16 2013 North Korean nuclear test 9 North Korea
2016-01-06 2016 North Korean nuclear test 14[35] North Korea Most recent nuclear test

"Staging" refers to whether it was a "true" hydrogen bomb of the so-called Teller-Ulam configuration or simply a form of a boosted fission weapon. For a more complete list of nuclear test series, see List of nuclear tests. Some exact yield estimates, such as that of the Tsar Bomba and the tests by India and Pakistan in 1998, are somewhat contested among specialists.

See also


  1. "The Treaty has not been signed by France or by the Peoples Republic of China." U.S. Department of State, Limited Test Ban Treaty.
  2. KIM, HYUNG-JIN (24 January 2013). "N. Korea Warns of Nuke Test, More Rocket Launches". U.S. News and World Report. Retrieved January 24, 2013. 
  3. For an overview of the preparations and considerations used in underground nuclear testing, see ""Underground Nuclear Weapons Testing" (". Retrieved 2006-10-19.  For a longer and more technical discussion, see U.S. Congress, Office of Technology Assessment (October 1989). The Containment of Underground Nuclear Explosions (PDF). Washington, D.C.: U.S. Government Printing Office. 
  4. Yang, Xiaoping; North first3=Carl, Robert; Romney; Richards, Paul R. "Worldwide Nuclear Explosions" (PDF). 
  5. Carey Sublette (9 August 2001), Nuclear Weapons Frequently Asked Questions, section 4.1.9, retrieved 10 April 2011 
  6. Jonathan Medalia (12 March 2008), Comprehensive Nuclear-Test-Ban Treaty: Issues and Arguments (PDF), Congressional Research Service, pp. 20–22, retrieved 9 December 2013 
  7. Medalia, Jonathan (2005-03-11). "Nuclear Weapons: Comprehensive Test Ban Treaty" (PDF) (IB92099). Congressional Record Service. Retrieved 2013-12-09. 
  8. US conducts 'subcritical' nuclear test, 2012-12-07, retrieved 2013-05-28 
  9. Subcritical nuke tests may be resumed at Novaya Zemlya 
  10. Papazian, Ghazar R.; Reinovsky, Robert E.; Beatty, Jerry N. (2003). "The New World of the Nevada Test Site" (PDF). Los Alamos Science (28). Retrieved 2013-12-12. 
  11. Thorn, Robert N.; Westervelt, Donald R. (February 1, 1987). "Hydronuclear Experiments" (PDF). LANL Report LA-10902-MS. Retrieved December 9, 2013. 
  12. Conrad, David C. (July 1, 2000). "Underground explosions are music to their ears". Science and Technology Review. Retrieved December 9, 2013. 
  13. Universal Time at the Nevada National Security Site is 8 hours after local time; UT dates are one day after local date for UT times after 16:00.
  14. "Nevada Test Site: U1a Complex subcritical experiments". DOE Nevada. 2003-02-01. 
  15. Togzhan Kassenova (28 September 2009). "The lasting toll of Semipalatinsk's nuclear testing". Bulletin of the Atomic Scientists. 
  16. Radiological Consequences of Nuclear Testing for the Population of the Former USSR (Input Information, Models, Dose, and Risk Estimates)O. A. Pavlovski. Atmospheric Nuclear Tests NATO ASI Series Volume 35, 1998, pp 219-260
  18. Atmospheric Nuclear Tests NATO ASI Series Volume 35, 1998, pp 219-260 Radiological Consequences of Nuclear Testing for the Population of the Former USSR (Input Information, Models, Dose, and Risk Estimates)O. A. Pavlovski
  19. "United States Nuclear Tests: July 1945 through September 1992" (PDF). Las Vegas, NV: Department of Energy, Nevada Operations Office. 2000-12-01. Retrieved 2013-12-18.  This is usually cited as the "official" US list.
  20. "USSR Nuclear Weapons Tests and Peaceful Nuclear Explosions 1949 through 1990". Sarov, Russia: RFNC-VNIIEF. 1996.  The official Russian list of Soviet tests.
  21. Mikhailov, Editor in Chief, V.N.; Andryushin, L.A.; Voloshin, N.P.; Ilkaev, R.I.; Matushchenko, A.M.; Ryabev, L.D.; Strukov, V.G.; Chernyshev, A.K.; Yudin, Yu.A. "Catalog of Worldwide Nuclear Testing". Retrieved 2013-12-28. An equivalent list available on the internet.
  22. "UK/US Agreement". Archived from the original on 2007-06-07. Retrieved 2010-10-21. 
  23. "N° 3571.- Rapport de MM. Christian Bataille et Henri Revol sur les incidences environnementales et sanitaires des essais nucléaires effectués par la France entre 1960 et 1996 (Office d'évaluation des choix scientifiques et technologiques)". Retrieved 2010-10-21. 
  24. Nuclear Weapons, see also Nuclear Weapons Test List
  26. U.S. Department of State, Limited Test Ban Treaty.
  27. "CTBTO Factsheet: Ending Nuclear Explosions" (PDF). Retrieved 2012-05-23. 
  28. "Status of signature and ratification". Retrieved 2012-05-23. 
  29. "The Status of the Comprehensive Test Ban Treaty: Signatories and Ratifiers". Arms Control Association. March 2014. Retrieved June 29, 2014. 
  30. Exposure of the American Population to Radioactive Fallout from Nuclear Weapons Tests
  31. 31.0 31.1 31.2 31.3 31.4 What governments offer to victims of nuclear tests
  32. Radiation Exposure Compensation System: Claims to Date Summary of Claims Received by 06/11/2009
  33. [2010 test] Kakodkar says Pokhran-II tests fully successful], 24 September 2009
  34. 34.0 34.1 Pakistan Nuclear Weapons. Federation of American Scientists. December 11, 2002
  35. Atomtest in Nordkorea: Kims Möchtegern-Wasserstoffbombe. German Spiegel Magazin. January 6, 2016


  • 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.

External links