s. Throughout the twentieth century, most nations that have developed nuclear weapons have tested them. Testing nuclear weapons can yield information about how the weapons work, as well as how the weapons behave under various conditions and how structures behave when subjected to nuclear explosions.
1953 Nuclear testing: At the Nevada Test Site, the United States conduct their first and only nuclear artillery test.
1954 Nuclear testing: The Castle Bravo, a 15-megaton hydrogen bomb, is detonated on Bikini Atoll in the Pacific Ocean, resulting in the worst radioactive contamination ever caused by the United States.
1957 First American underground nuclear bomb test.
1961 Nuclear testing: The Soviet Union detonates the hydrogen bomb Tsar Bomba over Novaya Zemlya; at 58 megatons of yield, it is still the largest explosive device ever detonated, nuclear or otherwise.
1964 Cold War: Indian Prime Minister Jawaharlal Nehru appeals to the United States and the Soviet Union to end nuclear testing and to start nuclear disarmament, stating that such an action would "save humanity from the ultimate disaster".
1998 India carries out two nuclear tests at Pokhran, following the three conducted on May 11. The United States and Japan impose economic sanctions on India.
1998 Nuclear testing: Pakistan responds to a series of nuclear tests by India with five of its own, prompting the United States, Japan, and other nations to impose economic sanctions.
s. Throughout the twentieth century, most nations that have developed nuclear weapons have tested them. Testing nuclear weapons can yield information about how the weapons work, as well as how the weapons behave under various conditions and how structures behave when subjected to nuclear explosions. Additionally, nuclear testing has often been used as an indicator of scientific and military strength, and many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status by means of a nuclear test.
The first nuclear weapon 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. The first hydrogen bomb, codenamed "Mike
", was tested at the Enewetak
atoll in the Marshall Islands
on November 1 (local date) in 1952, 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 an estimated yield of around 50 megatons
In 1963, all nuclear and many non-nuclear states signed the Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space
. The treaty permitted underground nuclear testing
. France continued atmospheric testing until 1974, China continued up until 1980.
Underground tests in the United States continued until 1992 (its last nuclear testing), the Soviet Union in 1990, the United Kingdom in 1991, and both China and France in 1996. After signing the Comprehensive Test Ban Treaty
in 1996 (which has as of 2011 not yet entered into force), all of these states have pledged to discontinue all nuclear testing. Non-signatories India
last tested nuclear weapons in 1998.
The most recent nuclear test
was announced by North Korea
on May 25, 2009.
- Atmospheric testing designates explosions that take place in the atmosphereEarth's atmosphereThe atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
. Generally these have occurred as devices detonated on towers, balloons, barges, islands, or dropped from airplanes. Nuclear explosions that are close enough to the ground to draw dirt and debris into their mushroom cloudMushroom cloudA mushroom cloud is a distinctive pyrocumulus mushroom-shaped cloud of condensed water vapor or debris resulting from a very large explosion. They are most commonly associated with nuclear explosions, but any sufficiently large blast will produce the same sort of effect. They can be caused by...
can generate large amounts of nuclear falloutNuclear falloutFallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and shock wave have passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes...
due to irradiationIrradiationIrradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiation exposure to...
of the debris.
- Underground testing refers to nuclear tests that are conducted under the surface of the earth, at varying depths. Underground nuclear testingUnderground nuclear testingUnderground nuclear testing refers to test detonations of nuclear weapons that are performed underground. When the device being tested is buried at sufficient depth, the explosion may be contained, with no release of radioactive materials to the atmosphere....
made up the majority of nuclear tests by the United States and the Soviet Union during the Cold WarCold WarThe Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
; other forms of nuclear testing were banned by the Limited Test Ban Treaty in 1963. When the explosion is fully contained, underground nuclear testing emits a negligible amount of fallout. However, underground nuclear tests can "vent" to the surface, producing considerable amounts of radioactive debris as a consequence. Underground testing can result in seismic activity depending on the yieldNuclear weapon yieldThe explosive yield of a nuclear weapon is the amount of energy discharged when a nuclear weapon is detonated, expressed usually in the equivalent mass of trinitrotoluene , either in kilotons or megatons , but sometimes also in terajoules...
of the nuclear device and the composition of the medium it is detonated in, and generally result in the creation of subsidence craterSubsidence craterA subsidence crater is a hole or depression left on the surface of an area which has had an underground explosion. Many such craters are present at the Nevada Test Site, which is no longer in use for nuclear testing....
s. 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 TreatyThreshold Test Ban TreatyThe Treaty on the Limitation of Underground Nuclear Weapon Tests, also known as the Threshold Test Ban Treaty , was signed in July 1974 by the USA and the USSR...
- Exoatmospheric testing refers to nuclear tests conducted above the atmosphere. The test devices are lifted on rockets. These high altitude nuclear explosionHigh altitude nuclear explosionHigh-altitude nuclear explosions have historically been nuclear explosions which take place above altitudes of 30 km, still inside the Earth's atmosphere. Such explosions have been tests of nuclear weapons, used to determine the effects of the blast and radiation in the exoatmospheric...
s can generate an electromagnetic pulseElectromagnetic pulseAn electromagnetic pulse is a burst of electromagnetic radiation. The abrupt pulse of electromagnetic radiation usually results from certain types of high energy explosions, especially a nuclear explosion, or from a suddenly fluctuating magnetic field...
(EMP), and charged particles resulting from the blast can cross hemispheres to create an auroral display.
- Underwater testing results from nuclear devices being detonated underwaterUnderwater explosionAn underwater explosion, also known as an UNDEX, is an explosion beneath the surface of water. The type of explosion may be chemical or nuclear...
, 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 CrossroadsOperation CrossroadsOperation Crossroads was a series of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. It was the first test of a nuclear weapon after the Trinity nuclear test in July 1945...
), or to evaluate potential sea-based nuclear weapons (such as nuclear torpedoes or depth-charges). Underwater tests close to the surface can disperse large amounts of radioactive water and steam, contaminating nearby ships or structures.
PurposeSeparately 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.
- Peaceful nuclear explosionsPeaceful nuclear explosionsPeaceful nuclear explosions are nuclear explosions conducted for non-military purposes, such as activities related to economic development including the creation of canals...
are conducted to investigate non-military applications of nuclear explosives.
Aside from these technical considerations, tests have been conducted for political and training purposes. Tests also often serve multiple purposes.
Alternatives to full-scale testingHydronuclear 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.
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 accident
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 refer to the lack of creation of a critical mass
of fissile material. They are the only type of tests allowed under the Comprehensive Nuclear-Test-Ban Treaty.
Additionally, there have 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.
, 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 an atomic 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 twentieth century.
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 well as a Japanese fishing boat (Daigo Fukuryū Maru
). One member of the boat's crew died from radiation sickness after returning to port, and it was feared that the radioactive fish they had been carrying had made it into the Japanese food supply.
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 People's Republic of China
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 sizeable 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 supercomputer
s to conduct "virtual" testing, but codes need to be validated against test data.
were used to evaluate whether nuclear explosions could be used for non-military purposes such as digging canals and artificial harbors, or to stimulate oil and gas fields. The tests were eventually abandoned for economic, political, and environmental reasons.
Nuclear testing has also been used for clearly political purposes. The most explicit example of this was the detonation of the largest nuclear bomb ever created, the 50 megaton Tsar Bomba
, by the Soviet Union in 1961. This weapon was too large to be practically used against an enemy target, and it is not thought that any were manufactured except the one detonated in the test.
There have been many attempts to limit the number and size of nuclear tests; the most far-reaching was the Comprehensive Test Ban Treaty
of 1996, which was not ratified by the United States. Nuclear testing has since become a controversial issue in the United States, with a number of politicians saying that future testing might be necessary to maintain the aging warheads from the Cold War
. Because nuclear testing is seen as furthering nuclear arms development, many are also opposed to future testing as an acceleration of the arms race.
Nuclear testing by countryThe nuclear powers have conducted more than 2,000 nuclear test explosions (numbers are approximated, as some test results have been disputed):
: 1,054 tests by official count (involving at least 1,151 devices, 331 atmospheric tests), most at Nevada Test Site
and the Pacific Proving Grounds
in the Marshall Islands
, with 10 other tests taking place at various locations in the United States, including Amchitka
, and New Mexico
(see Nuclear weapons and the United States
for details). Soviet Union
: 715 tests (involving 969 devices) by official count, most at Semipalatinsk Test Site
and Novaya Zemlya
, and a few more at various sites in Russia
, and Ukraine
: 210 tests by official count (50 atmospheric, 160 underground), 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 then-French Algeria
, and nuclear atmospheric tests at Fangataufa
and nuclear undersea tests Moruroa
in French Polynesia
. Additional atomic and chemical warfare tests took place in the secret base B2-Namous, near Ben Wenif, other tests involving rockets and missiles at C.I.E.E.S, near Hammaguir
, both in the Sahara. United Kingdom
: 45 tests (21 in Australia
n territory, including nine in mainland South Australia
and Emu Field, some at Christmas Island
in the Pacific Ocean
, plus many others in the United States as part of joint test series) China
: 45 tests (23 atmospheric and 22 underground, at Lop Nur
Nuclear Weapons Test Base, in Malan
: Six underground tests (including the first one in 1974), at Pokhran
: Six underground tests, at Ras Koh Hills, Chagai District
and Kharan Desert
, Kharan District
in Balochistan Province. North Korea
: two tests at Hwadae-ri
Additionally, there may have been at least three alleged but unacknowledged nuclear explosions (see list of alleged nuclear tests). Of these, the only one taken seriously as a possible nuclear test is the Vela Incident
, a possible detection of a nuclear explosion in the Indian Ocean
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.
Compensation for victimsOver 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
- United States: As of March 2009, the U.S. is the only nation that compensates nuclear test victims. Since the Radiation Exposure Compensation ActRadiation Exposure Compensation ActThe United States Radiation Exposure Compensation Act is a federal statute providing for the monetary compensation of people, including atomic veterans, who contracted cancer and a number of other specified diseases as a direct result of their exposure to atmospheric nuclear testing undertaken by...
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 SiteNevada Test SiteThe Nevada National Security Site , previously the Nevada Test Site , is a United States Department of Energy reservation located in southeastern Nye County, Nevada, about northwest of the city of Las Vegas...
, and to others exposed to the radiation.
- 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.
- Britain: There is no formal British government compensation program. However, nearly 1,000 veterans of Christmas Island nuclear tests in the 1950s are planning to sue the Ministry of Defense for negligence. They say they suffered health problems and were not warned of potential dangers before the experiments.
- 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.
- 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.
Partial Test Ban Treaty
The treaty banning nuclear weapon tests in the atmosphere, in outer space and under water, often abbreviated as the Partial Test Ban Treaty , Limited Test Ban Treaty , or Nuclear Test Ban Treaty is a treaty prohibiting all test detonations of nuclear weapons...
Project Gnome was the first nuclear test of the Plowshare program and was the first continental nuclear weapon test since Trinity to be conducted outside of the Nevada Test Site...
Test Readiness Program
The Test Readiness Program was a United States Government program established in 1963 to maintain the necessary technologies and infrastructure for the atmospheric testing of nuclear weapons, should the treaty which prohibited such testing be abrogated....
An underwater explosion, also known as an UNDEX, is an explosion beneath the surface of water. The type of explosion may be chemical or nuclear...
Trinity and Beyond
Trinity and Beyond: The Atomic Bomb Movie is a 1995 American documentary film directed by Peter Kuran and narrated by William Shatner. Using restored archive footage, the film traces the development of nuclear weapons and their testing, from America's Trinity test of 1945 to the first Chinese...
(documentary about nuclear weapon testing)
- Video archive of US, Soviet, UK, Chines and French Nuclear Testing at sonicbomb.com
- Maps of sites tested
- "We're all Downwinders Now"
- Terrible Beauty: A-Bomb Tests - slideshow by Life magazine
- Atomic Veterans History Project (United States)
- Australian government database of nuclear explosions and tests Australian
- Australian Nuclear Fallout Strontium 90 survey 1957-58 Child bones Australian
- Australia's program of testing for Strontium 90, between 1957 and 1978, samples of childrens bones taken at autopsy Australian
- The Bombing of the Monte Bello Islands Western Australia
- Silent Storm - Film about CSIRO scientist Hedley Marston's top-secret fallout experiments Australian
- Ionising Radiation and Health Australian
- Oklahoma Geological Survey Nuclear Explosion Catalog lists 2,199 explosions by date, country, location, yield etc.
- Table of Known Nuclear Tests Worldwide, from NRDC
- Gallery of U.S. nuclear tests (with detailed descriptions of each test series)
- Gallery and short descriptions of UK nuclear tests
- Account of fallout from Nevada Test Site in 1955 (PDF)
- Soviet Nuclear Test Summary
- Marshall Islands Nuclear Claims Tribunal
- Nuclear Testing at Nuclear Files.org
- Film footage of nuclear artillery test
- What About Radiation on Bikini Atoll?
- Nevada Desert Experience
- Western States Legal Foundation
- The Nuclear Weapon Archive
- United Nations Leadup to Comprehensive Nuclear Test Ban Treaty 22 September 1995 General Conference
- Time-lapse map of the 2053 confirmed nuclear explosions since 1945
- Annotated bibliography for nuclear weapons testing from the Alsos Digital Library for Nuclear Issues
- Atomic Bomb website and nuclear weapon testing articles