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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 Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...
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 Eight sovereign states have publicly announced successful detonation of nuclear weapons. Five are considered to be nuclear-weapon states (NWS) under the terms of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). In order of acquisit ...
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 Trinity was the code name of the first detonation of a nuclear weapon. It was conducted by the United States Army at 5:29 a.m. on July 16, 1945, as part of the Manhattan Project. The test was conducted in the Jornada del Muerto desert abo ...
in
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...
on July 16, 1945, with a yield approximately equivalent to 20
kiloton TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a ...
s of
TNT Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...
. The first
thermonuclear weapon A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lo ...
technology test of an engineered device, codenamed "
Ivy Mike Ivy Mike was the codename given to the first full-scale test of a thermonuclear device, in which part of the explosive yield comes from nuclear fusion. Ivy Mike was detonated on November 1, 1952, by the United States on the island of Elugelab ...
", was tested at the
Enewetak Atoll Enewetak Atoll (; also spelled Eniwetok Atoll or sometimes Eniewetok; mh, Ānewetak, , or , ; known to the Japanese as Brown Atoll or Brown Island; ja, ブラウン環礁) is a large coral atoll of 40 islands in the Pacific Ocean and with it ...
in the
Marshall Islands The Marshall Islands ( mh, Ṃajeḷ), officially the Republic of the Marshall Islands ( mh, Aolepān Aorōkin Ṃajeḷ),'' () is an independent island country and microstate near the Equator in the Pacific Ocean, slightly west of the Inte ...
on November 1, 1952 (local date), also by the United States. The largest nuclear weapon ever tested was the "
Tsar Bomba The Tsar Bomba () ( code name: ''Ivan'' or ''Vanya''), also known by the alphanumerical designation "AN602", was a thermonuclear aerial bomb, and the most powerful nuclear weapon ever created and tested. Overall, the Soviet physicist Andrei ...
" of the
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...
at
Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ) is an archipelago in northern Russia. It is situated in the Arctic Ocean, in the extreme northeast of Europe, with Cape Flissingsky, on the northern island, ...
on October 30, 1961, with the largest yield ever seen, an estimated 50–58
megatons TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a ...
. 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 Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, pred ...
. The treaty permitted
underground nuclear testing Underground nuclear testing is the test detonation of nuclear weapons that is performed underground. When the device being tested is buried at sufficient depth, the nuclear explosion may be contained, with no release of radioactive materials to ...
.
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
continued atmospheric testing until 1974, and
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
continued until 1980. Neither has signed the treaty. Underground tests conducted by the Soviet Union continued until 1990, the United Kingdom until 1991, the United States until 1992, and both China and France until 1996. In signing the
Comprehensive Nuclear-Test-Ban Treaty The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a multilateral treaty to ban nuclear weapons test explosions and any other nuclear explosions, for both civilian and military purposes, in all environments. It was adopted by the United Nati ...
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 India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
and
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
last tested nuclear weapons in 1998.
North Korea North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korean Peninsula and shares borders with China and Russia to the north, at the Yalu (Amnok) and T ...
conducted nuclear tests in 2006, 2009, 2013, 2016, and 2017. The most recent confirmed nuclear test in September 2017 in North Korea.


Types

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 An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A ...
. Generally these have occurred as devices detonated on
towers A tower is a tall structure, taller than it is wide, often by a significant factor. Towers are distinguished from masts by their lack of guy-wires and are therefore, along with tall buildings, self-supporting structures. Towers are specific ...
, balloons, barges, or 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 A mushroom cloud is a distinctive mushroom-shaped flammagenitus cloud of debris, smoke and usually condensed water vapor resulting from a large explosion. The effect is most commonly associated with a nuclear explosion, but any sufficiently ener ...
can generate large amounts of
nuclear fallout Nuclear fallout 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 the shock wave has passed. It commonly refers to the radioac ...
due to
irradiation Irradiation 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 ...
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 Underground nuclear testing is the test detonation of nuclear weapons that is performed underground. When the device being tested is buried at sufficient depth, the nuclear explosion may be contained, with no release of radioactive materials to ...
made up the majority of nuclear tests by the United States and the Soviet Union during the
Cold War The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because t ...
; 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 Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...
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 __NOTOC__ A subsidence crater is a hole or depression left on the surface of an area which has had an underground (usually nuclear) explosion. Many such craters are commonly present at bomb testing areas; one notable example is the Nevada Test 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 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 A nuclear electromagnetic pulse (nuclear EMP or NEMP) is a burst of electromagnetic radiation created by a nuclear explosion. The resulting rapidly varying electric and magnetic fields may couple with electrical and electronic systems to produce ...
(NEMP) when they occur in the
ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...
, 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 Operation Crossroads was a pair of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. They were the first nuclear weapon tests since Trinity in July 1945, and the first detonations of nuclear devices since the ...
), 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 is 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.
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 The United States's Cresset nuclear test series was a group of 22 nuclear test Nuclear weapons tests are experiments carried out to determine nuclear weapons' effectiveness, yield, and explosive capability. Testing nuclear weapons offers ...
'' has separate items for ''Cremino'' and ''Caerphilly'', which together constitute a single test), the lists are of explosions.


Purpose

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 Vela Uniform was an element of Project Vela conducted jointly by the United States Department of Energy and the Advanced Research Projects Agency. Its purpose was to develop seismic methods for detecting underground nuclear testing, and it involved ...
before the
Comprehensive Test Ban Treaty The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a multilateral treaty to ban nuclear weapons test explosions and any other nuclear explosions, for both civilian and military purposes, in all environments. It was adopted by the United Nat ...
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 Project Plowshare was the overall United States program for the development of techniques to use nuclear explosives for peaceful construction purposes. The program was organized in June 1957 as part of the worldwide Atoms for Peace efforts. As ...
. 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

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. 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 accident A criticality accident is an accidental uncontrolled nuclear fission chain reaction. It is sometimes referred to as a critical excursion, critical power excursion, or divergent chain reaction. Any such event involves the unintended accumulation ...
s. Subcritical (or cold) tests are any type of tests involving nuclear materials and possibly
high explosives An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
(like those mentioned above) that purposely result in no yield. The name refers to the lack of creation of a
critical mass In nuclear engineering, a critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties (specifically, its nuclear fi ...
of fissile material. They are the only type of tests allowed under the interpretation of the
Comprehensive Nuclear-Test-Ban Treaty The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a multilateral treaty to ban nuclear weapons test explosions and any other nuclear explosions, for both civilian and military purposes, in all environments. It was adopted by the United Nati ...
tacitly agreed to by the major atomic powers. Subcritical tests continue to be performed by the United States, Russia, and the People's Republic of China, at least. Subcritical tests executed by the United States include:


History

The first atomic weapons test was conducted near Alamogordo, New Mexico, on July 16, 1945, during the
Manhattan Project The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project w ...
, and given the codename "
Trinity The Christian doctrine of the Trinity (, from 'threefold') is the central dogma concerning the nature of God in most Christian churches, which defines one God existing in three coequal, coeternal, consubstantial divine persons: God th ...
". The test was originally to confirm that the implosion-type
nuclear weapon design Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types: * pure fission weapons, the simplest and least technically ...
was feasible, and to give an idea of what the actual size and effects of a
nuclear explosion A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, ...
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 Nuclear fallout 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 the shock wave has passed. It commonly refers to the radioac ...
, which was not well understood by the project scientists until well after the
atomic bombings of Hiroshima and Nagasaki The United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August 1945, respectively. The two bombings killed between 129,000 and 226,000 people, most of whom were civilians, and remain the onl ...
. The United States conducted six atomic tests before the Soviet Union developed their first atomic bomb (
RDS-1 The RDS-1 (russian: РДС-1), also known as Izdeliye 501 (device 501) and First Lightning (), was the nuclear bomb used in the Soviet Union's first nuclear weapon test. The United States assigned it the code-name Joe-1, in reference to Joseph ...
) 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 Operation Crossroads was a pair of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. They were the first nuclear weapon tests since Trinity in July 1945, and the first detonations of nuclear devices since the ...
'' 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 The Nevada National Security Site (N2S2 or NNSS), known as the Nevada Test Site (NTS) until 2010, is a United States Department of Energy (DOE) reservation located in southeastern Nye County, Nevada, about 65 miles (105 km) northwest of the ...
) and was also using a site in the
Marshall Islands The Marshall Islands ( mh, Ṃajeḷ), officially the Republic of the Marshall Islands ( mh, Aolepān Aorōkin Ṃajeḷ),'' () is an independent island country and microstate near the Equator in the Pacific Ocean, slightly west of the Inte ...
( 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 Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
. During the later phases of the
Cold War The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because t ...
, though, both countries developed accelerated testing programs, testing many hundreds of bombs over the last half of the 20th century. Atomic and nuclear tests can involve many hazards. Some of these were illustrated in the U.S.
Castle Bravo Castle Bravo was the first in a series of high-yield thermonuclear weapon design tests conducted by the United States at Bikini Atoll, Marshall Islands, as part of '' Operation Castle''. Detonated on March 1, 1954, the device was the most powerful ...
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 Nuclear fallout 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 the shock wave has passed. It commonly refers to the radioac ...
, 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 , 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 was a Japanese tuna fishing boat with a crew of 23 men which was contaminated by nuclear fallout from the United States Castle Bravo thermonuclear weapon test at Bikini Atoll on March 1, 1954. The crew suffered acute radiation syndrome (A ...
''. 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. Castle Bravo was the worst U.S. nuclear accident, but many of its component problems—unpredictably large yields, changing weather patterns, unexpected fallout
contamination Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc. Types of 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 The Partial Test Ban Treaty (PTBT) is the abbreviated name of the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, which prohibited all test detonations of nuclear weapons except for those conducted ...
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 Tsar Bomba () ( code name: ''Ivan'' or ''Vanya''), also known by the alphanumerical designation "AN602", was a thermonuclear aerial bomb, and the most powerful nuclear weapon ever created and tested. Overall, the Soviet physicist Andrei ...
, the largest nuclear weapon ever tested. The United States responded in 1962 with
Operation Dominic Operation Dominic was a series of 31 nuclear test explosions with a total yield conducted in 1962 by the United States in the Pacific. This test series was scheduled quickly, in order to respond in kind to the Soviet resumption of testing af ...
, 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 The Vela incident was an unidentified double flash of light detected by an American Vela Hotel satellite on 22 September 1979 near the South African territory of Prince Edward Islands in the Indian Ocean, roughly midway between Africa and Antar ...
), which has since dismantled all of its weapons.
Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
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
supercomputer A supercomputer is a computer with a high level of performance as compared to a general-purpose computer. The performance of a supercomputer is commonly measured in floating-point operations per second ( FLOPS) instead of million instructio ...
s 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 The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a multilateral treaty to ban nuclear weapons test explosions and any other nuclear explosions, for both civilian and military purposes, in all environments. It was adopted by the United Nat ...
of 1996, which has not, , 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 The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because t ...
. 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, with a peak occurring in 1961–1962, when 340 megatons were detonated in the atmosphere by the United States and
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...
, 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. Image:Trinity shot color.jpg, The first atomic test, "
Trinity The Christian doctrine of the Trinity (, from 'threefold') is the central dogma concerning the nature of God in most Christian churches, which defines one God existing in three coequal, coeternal, consubstantial divine persons: God th ...
", took place on July 16, 1945. Image:Sedan Plowshare Crater.jpg, The Sedan test of 1962 was an experiment by the United States in using nuclear weapons to excavate large amounts of earth.


Yield

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 . 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 .


Nuclear testing by country

The nuclear powers have conducted more than 2,000 nuclear test explosions (numbers are approximate, as some test results have been disputed): * United States: 1,054 tests by official count (involving at least 1,149 devices). 219 were atmospheric tests as defined by the
CTBT The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a multilateral treaty to ban nuclear weapons test explosions and any other nuclear explosions, for both civilian and military purposes, in all environments. It was adopted by the United Nation ...
. These tests include 904 at the
Nevada Test Site The Nevada National Security Site (N2S2 or NNSS), known as the Nevada Test Site (NTS) until 2010, is a United States Department of Energy (DOE) reservation located in southeastern Nye County, Nevada, about 65 miles (105 km) northwest of the ...
, 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 Amchitka (; ale, Amchixtax̂; russian: Амчитка) is a volcanic, tectonically unstable and uninhabited island in the Rat Islands group of the Aleutian Islands in southwest Alaska. It is part of the Alaska Maritime National Wildlife Ref ...
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
,
Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the ...
,
Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...
,
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...
and
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
outside the NNSS (see
Nuclear weapons and the United States The United States was the first country to manufacture nuclear weapons and is the only country to have used them in combat, with the bombings of Hiroshima and Nagasaki in World War II. Before and during the Cold War, it conducted 1,054 nucle ...
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. Motion pictures were made of the explosions, later used to validate computer simulation predictions of explosions. '' United States' table data''. * Soviet Union: 715 tests (involving 969 devices) by official count, plus 13 unnumbered test failures. Most were at their Southern Test Area at
Semipalatinsk Test Site The Semipalatinsk Test Site ( Russian: Семипалатинск-21; Semipalatinsk-21), also known as "The Polygon", was the primary testing venue for the Soviet Union's nuclear weapons. It is located on the steppe in northeast Kazakhstan (then ...
and the Northern Test Area at
Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ) is an archipelago in northern Russia. It is situated in the Arctic Ocean, in the extreme northeast of Europe, with Cape Flissingsky, on the northern island, ...
. Others include rocket tests and peaceful-use explosions at various sites in
Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
,
Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
,
Turkmenistan Turkmenistan ( or ; tk, Türkmenistan / Түркменистан, ) is a country located in Central Asia, bordered by Kazakhstan to the northwest, Uzbekistan to the north, east and northeast, Afghanistan to the southeast, Iran to the s ...
,
Uzbekistan Uzbekistan (, ; uz, Ozbekiston, italic=yes / , ; russian: Узбекистан), officially the Republic of Uzbekistan ( uz, Ozbekiston Respublikasi, italic=yes / ; russian: Республика Узбекистан), is a doubly landlocked co ...
and
Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inva ...
. '' Soviet Union's table data''. * United Kingdom: 45 tests, of which 12 were in
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
n territory, including three at the
Montebello Islands The Montebello Islands, also rendered as the Monte Bello Islands, are an archipelago of around 174 small islands (about 92 of which are named) lying north of Barrow Island and off the Pilbara coast of north-western Australia. The islands ...
and nine in mainland
South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest o ...
at
Maralinga Maralinga, in the remote western areas of South Australia, was the site, measuring about in area, of British nuclear tests in the mid-1950s. In January 1985 native title was granted to the Maralinga Tjarutja, a southern Pitjantjatjara Aborig ...
and Emu Field, 9 at
Christmas Island (Kiritimati) Kiritimati (also known as Christmas Island) is a Pacific Ocean atoll in the northern Line Islands. It is part of the Republic of Kiribati. The name is derived from the English word "Christmas" written in Gilbertese according to its phonology, ...
in the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...
, plus 24 in the United States at the Nevada Test Site 1958 US–UK Mutual Defence Agreement, as part of joint test series). 43 safety tests (the ''Vixen'' series) are not included in that number, though safety experiments by other countries are. ''Nuclear weapons and the United Kingdom, The United Kingdom's summary table''. * France: 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 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 and weapons of mass destruction, France's summary table''. * China: 45 tests (23 atmospheric and 22 underground), at Lop Nur Nuclear Weapons Test Base, in Malan, Xinjiang, Malan, Xinjiang There are two additional unnumbered failed tests. ''China's nuclear test series, China's summary table''. * India: Six underground explosions (including the first one in 1974), at Pokhran. ''India's nuclear testing series, India's summary table''. * Pakistan: Six underground explosions at Ras Koh Hills and the Chagai District. ''Pakistan's nuclear testing series, Pakistan's summary table''. * North Korea: North Korea is the only country in the world that still tests nuclear weapons, and their tests have caused 2017 North Korea crisis, escalating tensions between them and the United States. Their most recent nuclear test was on 2017 North Korean nuclear test, September 3, 2017. ''North Korea's nuclear testing series, North Korea's summary table'' There may also have been at least three alleged but unacknowledged nuclear explosions (see List of nuclear tests#Alleged tests, list of alleged nuclear tests) including the
Vela Incident The Vela incident was an unidentified double flash of light detected by an American Vela Hotel satellite on 22 September 1979 near the South African territory of Prince Edward Islands in the Indian Ocean, roughly midway between Africa and Antar ...
. 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.


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, 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. The 1996 Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans all nuclear explosions everywhere, including underground. For that purpose, the Comprehensive Nuclear-Test-Ban Treaty Organization Preparatory Commission, 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. , 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. The following is a list of the treaties applicable to nuclear testing:


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 Nuclear fallout 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 the shock wave has passed. It commonly refers to the radioac ...
, 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: 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 The Nevada National Security Site (N2S2 or NNSS), known as the Nevada Test Site (NTS) until 2010, is a United States Department of Energy (DOE) reservation located in southeastern Nye County, Nevada, about 65 miles (105 km) northwest of the ...
, and to others exposed to the radiation. As of 2017, the U.S. government refused to pay for the medical care of troops who associate their health problems with the construction of Runit Dome in the Marshall Islands. * 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. * United Kingdom: There is no formal British government compensation program. However, nearly 1,000 veterans of Christmas Island (Kiritimati)#Nuclear bomb tests, 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. * Russia: Decades later, Russia offered compensation to veterans who were part of the Totskoye nuclear exercise, 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.


Milestone nuclear explosions

The following list is of milestone nuclear explosions. In addition to the
atomic bombings of Hiroshima and Nagasaki The United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August 1945, respectively. The two bombings killed between 129,000 and 226,000 people, most of whom were civilians, and remain the onl ...
, 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 trinitrotoluene, TNT (see TNT equivalent). List of nuclear tests#Alleged tests, Putative tests (like
Vela Incident The Vela incident was an unidentified double flash of light detected by an American Vela Hotel satellite on 22 September 1979 near the South African territory of Prince Edward Islands in the Indian Ocean, roughly midway between Africa and Antar ...
) have not been included. ;Note * "Staged" refers to whether it was a "true"
thermonuclear weapon A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lo ...
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 The Tsar Bomba () ( code name: ''Ivan'' or ''Vanya''), also known by the alphanumerical designation "AN602", was a thermonuclear aerial bomb, and the most powerful nuclear weapon ever created and tested. Overall, the Soviet physicist Andrei ...
and the tests by India and Pakistan in 1998, are somewhat contested among specialists.


See also

* Atmospheric focusing * Atomic Testing Museum (in Nevada in the US) * High-altitude nuclear explosion * Historical nuclear weapons stockpiles and nuclear tests by country * History of nuclear weapons * International Day against Nuclear Tests * ''How to Photograph an Atomic Bomb'' * List of military nuclear accidents (including nuclear weapons accidents) * List of nuclear weapons tests of the United States * List of states with nuclear weapons * Live fire exercise * National Technical Means * :Nuclear test sites, Nuclear test sites * Nuclear weapons design * Project Gnome * Rope trick effect * Subsidence crater * Test Readiness Program * ''Trinity and Beyond'' (documentary about nuclear weapon testing)


Explanatory notes


Citations


General and cited references

* 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


Federation of American Scientists

Preparatory Commission for the Comprehensive Nuclear-Test-Ban-Treaty Organization



NuclearFiles.org


*
Bulletin of the Atomic Scientists

Alsos Digital Library for Nuclear Issues

Atomic Bomb website and nuclear weapon testing articles

The Woodrow Wilson Center's Nuclear Proliferation International History Project
{{DEFAULTSORT:Nuclear Weapons Testing Nuclear weapons testing, Nuclear weapons, Testing