Nuclear weapons testing

Nuclear weapons tests are experiments carried out to determine nuclear weapons' effectiveness, yield, and explosive capability. Testing nuclear weapons offers practical information about how the weapons function, how detonations are affected by different conditions, and how personnel, structures, and equipment are affected when subjected to nuclear explosions. However, nuclear testing has often been used as an indicator of scientific and military strength. Many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status through a nuclear test.

The first nuclear device was detonated as a test by the United States at the Trinity site in New Mexico on July 16, 1945, with a yield approximately equivalent to 20 kilotons of TNT. The first thermonuclear weapon technology test of an engineered device, codenamed "Ivy 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, an estimated 50–58 megatons.

In 1963, three (UK, US, Soviet Union) of the then 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 Soviet Union continued until 1990, the United Kingdom until 1991, the United States until 1992 (its last nuclear test), and both China and France until 1996. In signing the Comprehensive Nuclear-Test-Ban Treaty in 1996, these countries have pledged to discontinue all nuclear testing; the treaty has not yet entered into force because of failure to be ratified by eight countries. Non-signatories India and Pakistan last tested nuclear weapons in 1998. North Korea conducted nuclear tests in 2006, 2009, 2013, 2016, and 2017. The most recent confirmed nuclear test occurred in September 2017 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 only buried far enough to intentionally create a surface-breaking crater. The United States, the Soviet Union, and China have all conducted tests involving explosions of missile-launched bombs (See List of nuclear weapons tests#Tests of live warheads on rockets). Nuclear explosions 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, causes seismic activity of a magnitude that depends on the yield of the nuclear device and the composition of the medium in which it is detonated, and generally creates a subsidence crater.[2] 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 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 involves 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 locally to the explosion.

Salvo tests

Another way to classify nuclear tests are by the number of explosions that 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.[3]

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, and can often serve multiple purposes.

Alternatives to full-scale testing

Subcritical experiment at the Nevada National Security Site

Hydronuclear tests study nuclear materials under the conditions of explosive shock compression. They can create subcritical conditions, or supercritical conditions with yields ranging from negligible all the way up to a substantial fraction of full weapon yield.[4]

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 subcritical or supercritical, in which case significant radiation fluxes can be produced. This type of test has resulted in several criticality accidents.

Subcritical (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.[5][6] Subcritical tests continue to be performed by the United States, Russia, and the People's Republic of China, at least.[7][8]

Subcritical test executed by the United States include:[9][10][11]

Subcritical Tests
NameDate Time (UT[a])LocationElevation + HeightNotes
A series of 50 testsJanuary 1, 1960Los Alamos National Lab Test Area 4935°49′22″N 106°18′08″W / 35.82289°N 106.30216°W / 35.82289; -106.302162,183 metres (7,162 ft) and 20 metres (66 ft)Series of 50 tests during US/USSR joint nuclear test ban.[12]
OdysseyNTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 190 metres (620 ft)
TrumpetNTS Area U1a-102D37°00′40″N 116°03′31″W / 37.01099°N 116.05848°W / 37.01099; -116.058481,222 metres (4,009 ft) and 190 metres (620 ft)
KismetMarch 1, 1995NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 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).
ReboundJuly 2, 1997 10:—:—NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 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.
HologSeptember 18, 1997NTS Area U1a.101A37°00′37″N 116°03′32″W / 37.01036°N 116.05888°W / 37.01036; -116.058881,222 metres (4,009 ft) and 290 metres (950 ft)Holog and Clarinet may have switched locations.
StagecoachMarch 25, 1998NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 290 metres (950 ft)Provided information on the behavior of aged (up to 40 years) plutonium alloys compressed by high pressure shock waves.
BagpipeSeptember 26, 1998NTS Area U1a.101B37°00′37″N 116°03′32″W / 37.01021°N 116.05886°W / 37.01021; -116.058861,222 metres (4,009 ft) and 290 metres (950 ft)
CimarronDecember 11, 1998NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 290 metres (950 ft)Plutonium surface ejecta studies.
ClarinetFebruary 9, 1999NTS Area U1a.101C37°00′36″N 116°03′32″W / 37.01003°N 116.05898°W / 37.01003; -116.058981,222 metres (4,009 ft) and 290 metres (950 ft)Holog and Clarinet may have switched places on the map.
OboeSeptember 30, 1999NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
Oboe 2November 9, 1999NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
Oboe 3February 3, 2000NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
ThoroughbredMarch 22, 2000NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 290 metres (950 ft)Plutonium surface ejecta studies, followup to Cimarron.
Oboe 4April 6, 2000NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
Oboe 5August 18, 2000NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
Oboe 6December 14, 2000NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
Oboe 8September 26, 2001NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
Oboe 7December 13, 2001NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
Oboe 9June 7, 2002 21:46:—NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
MarioAugust 29, 2002 19:00:—NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 290 metres (950 ft)Plutonium surface studies (optical analysis of spall). Used wrought plutonium from Rocky Flats.
RoccoSeptember 26, 2002 19:00:—NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 290 metres (950 ft)Plutonium surface studies (optical analysis of spall), followup to Mario. Used cast plutonium from Los Alamos.
PianoSeptember 19, 2003 20:44:—NTS Area U1a.102C37°00′39″N 116°03′32″W / 37.01095°N 116.05877°W / 37.01095; -116.058771,222 metres (4,009 ft) and 290 metres (950 ft)
ArmandoMay 25, 2004NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 290 metres (950 ft)Plutonium spall measurements using x-ray analysis.[b]
Step WedgeApril 1, 2005NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 190 metres (620 ft)April–May 2005, a series of mini-hydronuclear experiments interpreting Armando results.
UnicornAugust 31, 2006 01:00:—NTS Area U6c36°59′12″N 116°02′38″W / 36.98663°N 116.0439°W / 36.98663; -116.04391,222 metres (4,009 ft) and 190 metres (620 ft)"...confirm nuclear performance of the W88 warhead with a newly-manufactured pit." Early pit studies.
ThermosJanuary 1, 2007NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 190 metres (620 ft)February 6 – May 3, 2007, 12 mini-hydronuclear experiments in thermos-sized flasks.
BacchusSeptember 16, 2010NTS Area U1a.05?37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 190 metres (620 ft)
Barolo ADecember 1, 2010NTS Area U1a.05?37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 190 metres (620 ft)
Barolo BFebruary 2, 2011NTS Area U1a.05?37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 190 metres (620 ft)
CastorSeptember 1, 2012NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 190 metres (620 ft)Not even a subcritical, contained no plutonium; a dress rehearsal for Pollux.
PolluxDecember 5, 2012NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 190 metres (620 ft)A subcritical test with a scaled down warhead mockup.[c]
LedaJune 15, 2014NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 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.[d]
Lydia??-??-2015NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.059831,222 metres (4,009 ft) and 190 metres (620 ft)Expected to be a plutonium subcritical test with a scaled down warhead mockup.
VegaDecember 13, 2017Nevada test sitePlutonium subcritical test with a scaled down warhead mockup.[13]
EdizaFebruary 13, 2019NTS Area U1a37°00′41″N 116°03′35″W / 37.01139°N 116.05983°W / 37.01139; -116.05983Plutonium subcritical test designed to confirm supercomputer simulations for stockpile safety.[14]
Nightshade ANovember 2020Nevada test sitePlutonium subcritical test designed to measure ejecta emission.[15][16]


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 6,900-square-mile (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.[17]

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 (160 km) 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 spread in a direction not cleared in advance. The fallout plume spread high levels of radiation for over 100 miles (160 km), 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 to 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.

A tacit moratorium on testing was in effect from 1958 to 1961, and ended with a series of Soviet tests in late 1961, including the Tsar Bomba, the largest nuclear weapon ever tested. The United States responded in 1962 with Operation Dominic, involving dozens of tests, including the explosion of a missile launched from a submarine.

Almost all new nuclear powers have announced their possession of nuclear weapons with a nuclear test. The only acknowledged nuclear power that claims never to have conducted a test was South Africa (although 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 to 1992, 520 atmospheric nuclear explosions (including eight underwater) were conducted with a total yield of 545 megatons,[18] with a peak occurring in 1961–1962, when 340 megatons were detonated in the atmosphere by the United States and Soviet Union,[19] while the estimated number of underground nuclear tests conducted in the period from 1957 to 1992 was 1,352 explosions with a total yield of 90 Mt.[18]


In US context, it was decided during the Manhattan Project that yield measured in tons of TNT equivalent could be imprecise. This comes from the range of experimental values of the energy content of TNT, ranging from 900 to 1,100 calories per gram (3,800 to 4,600 kJ/g). There is also the issue of which ton to use, as short tons, long tons and metric tonnes all have different values. It was therefore decided that one kiloton would be equivalent to 1.0×1012 calories (4.2×1012 kJ).[20]

Nuclear testing by country

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, yellow China, orange India, brown Pakistan, green North Korea and light green (territories exposed to nuclear bombs). The Black dot indicates the location of the Vela Incident.
"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):

  • United States United States: 1,054 tests by official count (involving at least 1,149 devices). 219 were atmospheric tests as defined by the CTBT. These tests include 904 at the Nevada Test Site, 106 at the Pacific Proving Grounds and other locations in the Pacific, 3 in the South Atlantic Ocean, and 17 other tests taking place in Amchitka Alaska, Colorado, Mississippi, New Mexico and Nevada outside the NNSS (see Nuclear weapons and the United States for details). 24 tests are classified as British tests held at the NTS. There were 35 Plowshare detonations and 7 Vela Uniform tests; 88 tests were safety experiments and 4 were transportation/storage tests.[21] Motion pictures were made of the explosions, later used to validate computer simulation predictions of explosions.[22] United States' table data.
  • Soviet Union Soviet Union: 715 tests (involving 969 devices) by official count, plus 13 unnumbered test failures.[23][24] Most were at their Southern Test Area at Semipalatinsk Test Site and the Northern Test Area at Novaya Zemlya. Others include rocket tests and peaceful-use explosions at various sites in Russia, Kazakhstan, Turkmenistan, Uzbekistan and Ukraine. Soviet Union's table data.
  • United Kingdom United Kingdom: 45 tests (21 in Australian territory, including three at the Montebello Islands, nine in mainland South Australia at Maralinga and Emu Field, some at Christmas Island (Kiritimati) in the Pacific Ocean, plus 24 in the United States at the Nevada Test Site as part of joint test series).[25] 43 safety tests (the Vixen series) are not included in that number, though safety experiments by other countries are. The United Kingdom's summary table.
  • France France: 210 tests by official count (50 atmospheric, 160 underground[26]), four atomic atmospheric tests at C.E.S.M. near Reggane, 13 atomic underground tests at C.E.M.O. near In Ekker in the French Algerian Sahara, and nuclear atmospheric and underground tests at and around Fangataufa and Moruroa Atolls in French Polynesia. Four of the In Ekker tests are counted as peaceful use, as they were reported as part of the CET's APEX (Application pacifique des expérimentations nucléaires), and given alternate names. France's summary table.
  • China China: 45 tests (23 atmospheric and 22 underground), at Lop Nur Nuclear Weapons Test Base, in Malan, Xinjiang[27] There are two additional unnumbered failed tests. China's summary table.
  • India India: Six underground explosions (including the first one in 1974), at Pokhran. India's summary table.
  • Pakistan Pakistan: Six underground explosions at Ras Koh Hills and the Chagai District.[28] Pakistan's summary table.
  • North Korea North Korea: North Korea is the only country in the world that still tests nuclear weapons, and their tests have caused escalating tensions between them and the United States. Their most recent nuclear test was on September 3, 2017. North Korea's summary table

There may also have been at least three alleged but unacknowledged nuclear explosions (see list of alleged nuclear tests) including the Vela Incident.

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 existing anti-nuclear explosion treaties, notably the Partial Nuclear Test Ban Treaty and the Comprehensive Nuclear Test Ban Treaty. These treaties were proposed in response to growing international concerns about environmental damage among other risks. Nuclear testing involving humans also contributed to the formation of these treaties. Examples can be seen in the following articles:

  • Desert Rock exercises
  • Totskoye range nuclear tests

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.[29]

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.[30] 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.[31]

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

NameAgreement dateIn force dateIn effect today?Notes
Unilateral USSR banMarch 31, 1958March 31, 1958noUSSR unilaterally stops testing provided the West does as well.
Bilateral testing banAugust 2, 1958August 2, 1958noUSA 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 SystemDecember 1, 1959June 23, 1961yesBans testing of all kinds in Antarctica.
Partial Nuclear Test Ban Treaty (PTBT)August 5, 1962October 10, 1963yesBan on all but underground testing.
Outer Space TreatyJanuary 27, 1967October 10, 1967yesBans testing on the moon and other celestial bodies.
Treaty of TlatelolcoFebruary 14, 1967April 22, 1968yesBans testing in South America and the Caribbean Sea Islands.
Nuclear Non-proliferation TreatyJanuary 1, 1968March 5, 1970yesBans the proliferation of nuclear technology to non-nuclear nations.
Seabed Arms Control TreatyFebruary 11, 1971May 18, 1972yesBans emplacement of nuclear weapons on the ocean floor outside territorial waters.
Strategic Arms Limitation Treaty (SALT I)January 1, 1972noA five-year ban on installing launchers.
Anti-Ballistic Missile TreatyMay 26, 1972August 3, 1972noRestricts ABM development; additional protocol added in 1974; abrogated by the US in 2002.
Agreement on the Prevention of Nuclear WarJune 22, 1973June 22, 1973yesPromises to make all efforts to promote security and peace.
Threshold Test Ban TreatyJuly 1, 1974December 11, 1990yesProhibits higher than 150 kt for underground testing.
Peaceful Nuclear Explosions Treaty (PNET)January 1, 1976December 11, 1990yesProhibits higher than 150 kt, or 1500kt in aggregate, testing for peaceful purposes.
Moon TreatyJanuary 1, 1979January 1, 1984noBans use and emplacement of nuclear weapons on the moon and other celestial bodies.
Strategic Arms Limitations Treaty (SALT II)June 18, 1979noLimits strategic arms. Kept but not ratified by the US, abrogated in 1986.
Treaty of RarotongaAugust 6, 1985?Bans nuclear weapons in South Pacific Ocean and islands. US never ratified.
Intermediate Range Nuclear Forces Treaty (INF)December 8, 1987June 1, 1988noEliminated Intermediate Range Ballistic Missiles (IRBMs). Implemented by 1 June 1991. Both sides alleged the other was in violation of the treaty. Expired following U.S. withdrawal, 2 August 2019.
Treaty on Conventional Armed Forces in EuropeNovember 19, 1990July 17, 1992yesBans 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, 1991December 5, 1994no35-40% reduction in ICBMs with verification. Treaty expired 5 December 2009, renewed (see below).
Treaty on Open SkiesMarch 24, 1992January 1, 2002yesAllows for unencumbered surveillance over all signatories.
US unilateral testing moratoriumOctober 2, 1992October 2, 1992noGeorge. H. W. Bush declares unilateral ban on nuclear testing.[32] Extended several times, not yet abrogated.
Strategic Arms Reduction Treaty (START II)January 3, 1993January 1, 2002noDeep 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, 1995March 28, 1997yesBans nuclear weapons from southeast Asia.
African Nuclear Weapon Free Zone Treaty (Pelindaba Treaty)January 1, 1996July 16, 2009yesBans nuclear weapons in Africa.
Comprehensive Nuclear Test Ban Treaty (CTBT)September 10, 1996yes (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, 2002June 1, 2003noReduces warheads to 1700–2200 in ten years. Expired, replaced by START II.
START I treaty renewalApril 8, 2010January 26, 2011yesSame 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.[33]

  • United States: Prior to March 2009, the U.S. was the only nation to compensate 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.[34][35] As of 2017, the U.S. government refused to for the medical care of troops who associate their health problems with the construction of Runit Dome in the Marshall Islands.[36]
  • 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.[34]
  • 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.[34]
  • 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.[34]
  • 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.[34]

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, as well as tests that 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.

Yield (kt)
(1945-07-16)July 16, 1945Trinity18–20United StatesFirst fission-device test, first plutonium implosion detonation.
(1945-08-06)August 6, 1945Little Boy12–18United StatesBombing of Hiroshima, Japan, first detonation of a uranium gun-type device, first use of a nuclear device in combat.
(1945-08-09)August 9, 1945Fat Man18–23United StatesBombing of Nagasaki, Japan, second detonation of a plutonium implosion device (the first being the Trinity Test), second and last use of a nuclear device in combat.
(1949-08-29)August 29, 1949RDS-122Soviet UnionFirst fission-weapon test by the Soviet Union.
(1952-10-03)October 3, 1952Hurricane25United KingdomFirst fission weapon test by the United Kingdom.
(1952-11-01)November 1, 1952Ivy Mike10,400United StatesFirst "staged" thermonuclear weapon, with cryogenic fusion fuel, primarily a test device and not weaponized.
(1952-11-16)November 16, 1952Ivy King500United StatesLargest pure-fission weapon ever tested.
(1953-08-12)August 12, 1953Joe 4400Soviet UnionFirst fusion-weapon test by the Soviet Union (not "staged").
(1954-03-01)March 1, 1954Castle Bravo15,000United StatesFirst "staged" thermonuclear weapon using dry fusion fuel. A serious nuclear fallout accident occurred. Largest nuclear detonation conducted by United States.
(1955-11-22)November 22, 1955RDS-371,600Soviet UnionFirst "staged" thermonuclear weapon test by the Soviet Union (deployable).
(1957-05-31)May 31, 1957Orange Herald800United KingdomLargest boosted fission weapon ever tested. Intended as a fallback "in megaton range" in case British thermonuclear development failed.
(1957-11-08)November 8, 1957Grapple X1,800United KingdomFirst (successful) "staged" thermonuclear weapon test by the United Kingdom
(1960-02-13)February 13, 1960Gerboise Bleue70FranceFirst fission weapon test by France.
(1961-10-31)October 31, 1961Tsar Bomba50,000Soviet UnionLargest thermonuclear weapon ever tested—scaled down from its initial 100 Mt design by 50%.
(1964-10-16)October 16, 196459622ChinaFirst fission-weapon test by the People's Republic of China.
(1967-06-17)June 17, 1967Test No. 63,300ChinaFirst "staged" thermonuclear weapon test by the People's Republic of China.
(1968-08-24)August 24, 1968Canopus2,600FranceFirst "staged" thermonuclear weapon test by France
(1974-05-18)May 18, 1974Smiling Buddha12IndiaFirst fission nuclear explosive test by India.
(1998-05-11)May 11, 1998Pokhran-II45–50IndiaFirst potential fusion-boosted weapon test by India; first deployable fission weapon test by India.
(1998-05-28)May 28, 1998Chagai-I40PakistanFirst fission weapon (boosted) test by Pakistan[37]
(2006-10-09)October 9, 20062006 nuclear testunder 1North KoreaFirst fission-weapon test by North Korea (plutonium-based).
(2017-09-03)September 3, 20172017 nuclear test200–300North KoreaFirst "staged" thermonuclear weapon test claimed by North Korea.
  • "Staged" refers to whether it was a "true" thermonuclear weapon 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

  • Atmospheric focusing


  1. ^ 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.
  2. ^ A video of the Armando test on YouTube
  3. ^ A video of the Pollux test on YouTube
  4. ^ A video of the Leda test on YouTube


  1. ^ "The Treaty has not been signed by France or by the People's Republic of China." U.S. Department of State, Limited Test Ban Treaty.
  2. ^ 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, seeU.S. Congress, Office of Technology Assessment (October 1989). The Containment of Underground Nuclear Explosions (PDF). Washington, D.C.: U.S. Government Printing Office. Archived from the original (PDF) on 2013-02-27. Retrieved 2018-12-24.
  3. ^ Yang, Xiaoping; North, Robert; Romney, Carl; Richards, Paul R. "Worldwide Nuclear Explosions" (PDF).
  4. ^ Carey Sublette (9 August 2001), Nuclear Weapons Frequently Asked Questions, section 4.1.9, retrieved 10 April 2011
  5. ^ Jonathan Medalia (12 March 2008), Comprehensive Nuclear-Test-Ban Treaty: Issues and Arguments (PDF), Congressional Research Service, pp. 20–22, retrieved 9 December 2013
  6. ^ Medalia, Jonathan (2005-03-11). "Nuclear Weapons: Comprehensive Test Ban Treaty" (PDF). Congressional Record Service. Retrieved 2013-12-09.
  7. ^ "US conducts 'subcritical' nuclear test". 2012-12-07. Retrieved 2013-05-28.
  8. ^ Thomas Nilsen (2 October 2012). "Subcritical nuke tests may be resumed at Novaya Zemlya". Retrieved 2017-07-13.
  9. ^ 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.
  10. ^ Thorn, Robert N.; Westervelt, Donald R. (February 1, 1987). "Hydronuclear Experiments" (PDF). LANL Report LA-10902-MS. Retrieved December 9, 2013.
  11. ^ Conrad, David C. (July 1, 2000). "Underground explosions are music to their ears". Science and Technology Review. Retrieved 9 December 2013.
  12. ^ "Nevada Test Site: U1a Complex subcritical experiments". DOE Nevada. Department of Energy. 2003-02-01. {{cite journal}}: Cite journal requires |journal= (help)
  13. ^ Kishner, Andrew (18 September 2018). "U.S. Sneaks in 'Vega,' Its 28th Subcritical Nuclear Test". Retrieved 30 October 2019.
  14. ^ O'Brien, Nolan (24 May 2019). "Subcritical experiment captures scientific measurements to advance stockpile safety". LLNL. Retrieved 16 January 2021.
  15. ^ "US conducted subcritical nuclear test in November". NHK World-Japan. 16 January 2021. Retrieved 16 January 2021.
  16. ^ Danielson, Jeremy; Bauer, Amy L. (September 2016). Nightshade Prototype Experiments (Silverleaf). Los Alamos National Laboratory (Report). OSTI. doi:10.2172/1338708. OSTI 1338708. Retrieved 16 January 2021.
  17. ^ Togzhan Kassenova (28 September 2009). "The lasting toll of Semipalatinsk's nuclear testing". Bulletin of the Atomic Scientists.
  18. ^ a b Pavlovski, O. A. (1 January 1998). "Radiological Consequences of Nuclear Testing for the Population of the Former USSR (Input Information, Models, Dose, and Risk Estimates)". Atmospheric Nuclear Tests. Springer, Berlin, Heidelberg. pp. 219–260. doi:10.1007/978-3-662-03610-5_17. ISBN 978-3-642-08359-4.
  19. ^ "Radioactive Fallout - Worldwide Effects of Nuclear War - Historical Documents".
  20. ^ The Containment of Underground Explosions (Report). Office of Technology Assessment. 31 October 1989. p. 11. OTA-ISC-414.
  21. ^ "United States Nuclear Tests: July 1945 through September 1992" (PDF). Las Vegas, NV: Department of Energy, Nevada Operations Office. 2000-12-01. Archived from the original (PDF) on 2006-10-12. Retrieved 2013-12-18. This is usually cited as the "official" US list.
  22. ^ Long, Kat. "Blasts from the Past: Old Nuke Test Films Offer New Insights [Video]". Scientific American. Retrieved 2017-04-24.
  23. ^ "USSR Nuclear Weapons Tests and Peaceful Nuclear Explosions 1949 through 1990". Sarov, Russia: RFNC-VNIIEF. 1996. {{cite journal}}: Cite journal requires |journal= (help) The official Russian list of Soviet tests.
  24. ^ 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". Archived from the original on 2013-12-19. Retrieved 2013-12-28. {{cite web}}: |last1= has generic name (help)An equivalent list available on the internet.
  25. ^ "UK/US Agreement". Archived from the original on 2007-06-07. Retrieved 2010-10-21.
  26. ^ "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.
  27. ^ "Nuclear Weapons Test List". Retrieved 22 September 2018.
  28. ^ "Archived copy". Archived from the original on 2012-04-27. Retrieved 2018-12-24.{{cite web}}: CS1 maint: archived copy as title (link)
  29. ^ U.S. Department of State, Limited Test Ban Treaty.
  30. ^ "CTBTO Factsheet: Ending Nuclear Explosions" (PDF). Retrieved 2012-05-23.
  31. ^ "Status of signature and ratification". Retrieved 2012-05-23.
  32. ^ "The Status of the Comprehensive Test Ban Treaty: Signatories and Ratifiers". Arms Control Association. March 2014. Retrieved June 29, 2014.
  33. ^ Council, National Research (11 February 2003). Exposure of the American Population to Radioactive Fallout from Nuclear Weapons Tests: A Review of the CDC-NCI Draft Report on a Feasibility Study of the Health Consequences to the American Population from Nuclear Weapons Tests Conducted by the United States and Other Nations. doi:10.17226/10621. ISBN 9780309087131. PMID 25057651.
  34. ^ a b c d e "International News: Latest Headlines, Video and Photographs from Around the World -- People, Places, Crisis, Conflict, Culture, Change, Analysis and Trends". ABC News.
  35. ^ "Radiation Exposure Compensation System: Claims to Date Summary of Claims Received by 06/11/2009" (PDF).
  36. ^ "Troops Who Cleaned Up Radioactive Islands Can't Get Medical Care". The New York Times. 28 January 2017.
  37. ^ "Pakistan Nuclear Weapons: A Brief History of Pakistan's Nuclear Program". Federation of American Scientists. 11 December 2002. Retrieved 30 October 2019.


  • 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

Media files used on this page

Flag of the United States.svg
Author/Creator: unknown, Licence: PD
Flag of the United Kingdom.svg
Author/Creator: unknown, Licence: PD
Flag of India.svg
Author/Creator: unknown, Licence:
A generic U.S. World War II tank, a derivate of Image:TM-9-374-T25E1-1.jpg, background removed (transparent), hue set to steel blue, reduced size and colors.
Worldwide nuclear testing multilang.svg
Author/Creator: , Licence: CC BY-SA 2.5
Worldwide nuclear explosions (all nuclear testing except for the atomic bombings of Hiroshima and Nagasaki) totals, 1945-1998. Raw data from [1], graph created by Fastfission in Microsoft Excel. (Converted from PNG (Image:Worldwide nuclear testing.png) to SVG (in Polish, Image:Worldwide nuclear testing-pl.svg) by Farmer Jan and converted to English by Hairy Dude.) See this talk page for the dataset, if you want to make your own graph. Technically this is a list of nuclear explosions, which is why there are 3 in 1945 rather than 1. Alleged/putative tests have not been included (i.e. Vela Incident, Ryanggang explosion).
Types of nuclear testing.svg
Four primary types of nuclear testing: 1. atmospheric, 2. underground, 3. upper-atmosphere, 4. underwater.

The illustration is meant to just be schematic about the locations and general characteristics of these types (atmospheric tests created mushroom clouds and fallout; underground tests create seismic activity; upper-atmospheric tests have all sorts of weird ionization and EMP effects but are too high to have much fallout; underwater tests create mushroom clouds with lots of water vapor).

The specific setups of the illustration (a tower shot, an underground instrumentation tower, a rocket, mooring to a ship) are arbitrary but not uncommon in the history of nuclear testing.
Rael Nuclear use locations world map.png
Author/Creator: Palli3000, Licence: CC BY-SA 3.0
Red: Russia/Soviet Union; blue: France; light blue: United States; purple: United Kingdom.

Over 2,000 nuclear explosions have been conducted, in over a dozen different sites around the world.

Yellow China, orange India, brown Pakistan, green North Korea and light green (territories exposed to nuclear bombs). The Black dot indicates the location of the Vela Incident
Sedan Plowshare Crater.jpg
Crater from the 1962 "Sedan" nuclear test as part of Operation Plowshare. The 104 kiloton blast displaced 12 million tons of earth and created a crater 320 feet deep and 1,280 feet wide. (Look to the size of the roads in the bottom-right of the picture, and the observation deck at the lower-right edge of the crater, for a sense of scale)
Operation Crossroads Baker Edit.jpg
The "Baker" explosion, part of Operation Crossroads, a nuclear weapon test by the United States military at Bikini Atoll, Micronesia, on 25 July 1946. The wider, exterior cloud is actually just a condensation cloud caused by the Wilson chamber effect, and was very brief. There was no classic mushroom cloud rising to the stratosphere, but inside the condensation cloud the top of the water geyser formed a mushroom-like head called the cauliflower, which fell back into the lagoon (compare with this image, a photo taken slightly later, after the condensation cloud had cleared). The water released by the explosion was highly radioactive and contaminated many of the ships that were set up near it. Some were otherwise undamaged and sent to Hunter's Point in San Francisco, California, United States, for decontamination. Those which could not be decontaminated were sunk a number of miles off the coast of San Francisco.
Wfm sts overview.png
Author/Creator: unknown, Licence: CC-BY-SA-3.0
US fallout exposure.png
Per capita thyroid doses in the continental United States of Iodine-131 resulting from all exposure routes from all atmospheric nuclear tests conducted at the Nevada Test Site.
Little boy.jpg
Photograph of a mock-up of the Little Boy nuclear weapon dropped on Hiroshima, Japan, in August 1945. This was the first photograph of the Little Boy bomb casing to ever be released by the U.S. government (it was declassified in 1960).
Bravo fallout2.png
Path of nuclear fallout plume after U.S. nuclear weapons test Bravo (yield 15 Mt) on Bikini Atoll. It is the single worst contamination accident in U.S. nuclear history. The test was part of the Operation Castle. The Bravo event was an experimental thermonuclear device surface event. The numbers correspond with estimated total (accumulated) dose contours (rad).
NTS - LLNL subcritical experiment.jpg
Nevada Test Site. LLNL subcritical experiment.
Internationally recognized symbol. Warning sign of Ionizing Radiation.
WMD world map.svg
(c) Wikimedia Commons, User:Andux, User:Vardion, and Simon Eugster, CC-BY-SA-3.0
World map with WMD hazard symbols superimposed on it.
Trinity shot color.jpg
Famous color photograph of the "Trinity" shot, the first nuclear test explosion.