|Weapons of mass destruction|
Nuclear weapons tests are experiments carried out to determine the effectiveness, yield, and explosive capability of nuclear weapons. Throughout the twentieth century, most nations that developed nuclear weapons tested them. Testing nuclear weapons can yield information about how the weapons work, as well as how the weapons behave under various conditions and how personnel, structures, and equipment behave when subjected to nuclear explosions. Nuclear testing has often been used as an indicator of scientific and military strength, and many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status by means of a nuclear test.
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or from a combination of fission and fusion reactions. Both bomb types release large quantities of energy from relatively small amounts of matter. The first test of a fission ("atomic") bomb released an amount of energy approximately equal to 20,000 tons of TNT (84 TJ). The first thermonuclear ("hydrogen") bomb test released energy approximately equal to 10 million tons of TNT (42 PJ). A thermonuclear weapon weighing little more than 2,400 pounds (1,100 kg) can release energy equal to more than 1.2 million tons of TNT (5.0 PJ). A nuclear device no larger than traditional bombs can devastate an entire city by blast, fire, and radiation. Since they are weapons of mass destruction, the proliferation of nuclear weapons is a focus of international relations policy.
The first nuclear device was detonated as a test by the United States at the Trinity site on July 16, 1945, with a yield approximately equivalent to 20 kilotons of TNT. The first thermonuclear weapon technology test of 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.
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The "ton of TNT" is a unit of energy defined by that convention to be 4.184 gigajoules, which is the approximate energy released in the detonation of a metric ton of TNT. In other words, for each gram of TNT exploded, 4,184 joules of energy are released.
A thermonuclear weapon, or fusion weapon, is a second-generation nuclear weapon design which affords vastly greater destructive power than first-generation atomic bombs. Modern fusion weapons consist essentially of two main components: a nuclear fission primary stage and a separate nuclear fusion secondary stage containing thermonuclear fuel: the heavy hydrogen isotopes deuterium and tritium, or in modern weapons lithium deuteride. For this reason, thermonuclear weapons are often colloquially called hydrogen bombs or H-bombs.
Ivy Mike was the codename given to the first test of a full-scale thermonuclear device, in which part of the explosive yield comes from nuclear fusion. It was detonated on November 1, 1952 by the United States on the island of Elugelab in Enewetak Atoll, in the Pacific Ocean, as part of Operation Ivy. It was the first full test of the Teller–Ulam design, a staged fusion device.
In 1963, three (UK, US, Soviet Union) of the four nuclear states and many non-nuclear states signed the Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space. The treaty permitted underground nuclear testing. France continued atmospheric testing until 1974, and China continued until 1980. Neither has signed the treaty.
Outer space, or just space, is the expanse that exists beyond the Earth and between celestial bodies. Outer space is not completely empty—it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature, as set by the background radiation from the Big Bang, is 2.7 kelvins. The plasma between galaxies accounts for about half of the baryonic (ordinary) matter in the universe; it has a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins; local concentrations of this plasma have condensed into stars and galaxies. Studies indicate that 90% of the mass in most galaxies is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces. Observations suggest that the majority of the mass-energy in the observable universe is a poorly understood vacuum energy of space, which astronomers label dark energy. Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space.
Underground tests in the United States continued until 1992 (its last nuclear test), the Soviet Union until 1990, the United Kingdom until 1991, and both China and France until 1996. In signing the Comprehensive Nuclear-Test-Ban Treaty in 1996, these states 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 [update] in September 2017 in North Korea.
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a multilateral treaty that bans all nuclear explosions, for both civilian and military purposes, in all environments. It was adopted by the United Nations General Assembly on 10 September 1996, but has not entered into force, as eight specific states have not ratified the treaty.
The Republic of India has developed and possesses weapons of mass destruction in the form of nuclear weapons. Though India has not made any official statements about the size of its nuclear arsenal, recent estimates suggest that India has 110 nuclear weapons — consistent with earlier estimates that it had produced enough weapons-grade plutonium for up to 75–110 nuclear weapons. In 1999, India was estimated to have 800 kg of separated reactor-grade plutonium, with a total amount of 8,300 kg of civilian plutonium, enough for approximately 1,000 nuclear weapons.
Pakistan is one of nine states to possess nuclear weapons. Pakistan began development of nuclear weapons in January 1972 under Prime Minister Zulfikar Ali Bhutto, who delegated the program to the Chairman of the Pakistan Atomic Energy Commission (PAEC) Munir Ahmad Khan with a commitment to having the bomb ready by the end of 1976. Since PAEC, consisting of over twenty laboratories and projects under nuclear engineer Munir Ahmad Khan, was falling behind schedule and having considerable difficulty producing fissile material, Abdul Qadeer Khan was brought from Europe by Bhutto at the end of 1974. As pointed out by Houston Wood, Professor of Mechanical & Aerospace Engineering, University of Virginia, Charlottesville, in his article on gas centrifuges, "The most difficult step in building a nuclear weapon is the production of fissile material"; as such, this work in producing fissile material as head of the Kahuta Project was pivotal to Pakistan developing the capability to detonate a nuclear bomb by the end of 1984.
Nuclear weapons tests have historically been divided into four categories reflecting the medium or location of the test.
The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention, and reducing temperature extremes between day and night.
A mushroom cloud is a distinctive pyrocumulus mushroom-shaped 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 energetic detonation or deflagration will produce the same effect. They can be caused by powerful conventional weapons, like thermobaric weapons, including the ATBIP and GBU-43/B Massive Ordnance Air Blast. Some volcanic eruptions and impact events can produce natural mushroom clouds.
Nuclear fallout, or 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 have passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes. The amount and spread of fallout is a product of the size of the weapon and the altitude at which it is detonated. Fallout may get entrained with the products of a pyrocumulus cloud and fall as black rain.
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.
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.
Aside from these technical considerations, tests have been conducted for political and training purposes, and can often serve multiple purposes.
Hydronuclear tests study nuclear materials under the conditions of explosive shock compression. They can create sub-critical conditions, or supercritical conditions with yields ranging from negligible all the way up to a substantial fraction of full weapon yield.
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 has resulted in several criticality accidents.
Sub-critical (or cold) tests are any type of tests involving nuclear materials and possibly high-explosives (like those mentioned above) that purposely result in no yield. The name refers to the lack of creation of a critical mass of fissile material. They are the only type of tests allowed under the interpretation of the Comprehensive Nuclear-Test-Ban Treaty tacitly agreed to by the major atomic powers.Sub-critical tests continue to be performed by the United States, Russia, and the People's Republic of China, at least.
Subcritical test executed by the United States include:
|Name||Date Time (UT )||Location||Elevation + Height||Notes|
|A series of 50 tests||January 1, 1960||Los Alamos National Lab Test Area 49||2,183 metres (7,162 ft) - 20 metres (66 ft)||Series of 50 tests during US/USSR joint nuclear test ban.|
|Odyssey||NTS Area U1a||1,222 metres (4,009 ft) - 190 metres (620 ft)|
|Trumpet||NTS Area U1a-102D||1,222 metres (4,009 ft) - 190 metres (620 ft)|
|Kismet||March 1, 1995||NTS Area U1a||1,222 metres (4,009 ft) - 293 metres (961 ft)||Kismet was a proof of concept for modern hydronuclear tests; it did not contain any SNM (Special Nuclear Material - Plutonium or Uranium).|
|Rebound||July 2, 1997 10:--:--||NTS Area U1a||1,222 metres (4,009 ft) - 293 metres (961 ft)||Provided information on the behavior of new plutonium alloys compressed by high pressure shock waves; same as Stagecoach but for the age of the alloys.|
|Holog||September 18, 1997||NTS Area U1a.101A||1,222 metres (4,009 ft) - 290 metres (950 ft)||Holog and Clarinet may have switched locations.|
|Stagecoach||March 25, 1998||NTS Area U1a||1,222 metres (4,009 ft) - 290 metres (950 ft)||Provided information on the behavior of aged (up to 40 years) plutonium alloys compressed by high pressure shock waves.|
|Bagpipe||September 26, 1998||NTS Area U1a.101B||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Cimarron||December 11, 1998||NTS Area U1a||1,222 metres (4,009 ft) - 290 metres (950 ft)||Plutonium surface ejecta studies.|
|Clarinet||February 9, 1999||NTS Area U1a.101C||1,222 metres (4,009 ft) - 290 metres (950 ft)||Holog and Clarinet may have switched places on the map.|
|Oboe||September 30, 1999||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Oboe 2||November 9, 1999||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Oboe 3||February 3, 2000||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Thoroughbred||March 22, 2000||NTS Area U1a||1,222 metres (4,009 ft) - 290 metres (950 ft)||Plutonium surface ejecta studies, followup to Cimarron.|
|Oboe 4||April 6, 2000||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Oboe 5||August 18, 2000||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Oboe 6||December 14, 2000||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Oboe 8||September 26, 2001||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Oboe 7||December 13, 2001||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Oboe 9||June 7, 2002 21:46:--||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Mario||August 29, 2002 19:00:--||NTS Area U1a||1,222 metres (4,009 ft) - 290 metres (950 ft)||Plutonium surface studies (optical analysis of spall). Used wrought plutonium from Rocky Flats.|
|Rocco||September 26, 2002 19:00:--||NTS Area U1a||1,222 metres (4,009 ft) - 290 metres (950 ft)||Plutonium surface studies (optical analysis of spall), followup to Mario. Used cast plutonium from Los Alamos.|
|Piano||September 19, 2003 20:44:--||NTS Area U1a.102C||1,222 metres (4,009 ft) - 290 metres (950 ft)|
|Armando||May 25, 2004||NTS Area U1a||1,222 metres (4,009 ft) - 290 metres (950 ft)||Plutonium spall measurements using x-ray analysis.|
|Step Wedge||April 1, 2005||NTS Area U1a||1,222 metres (4,009 ft) - 190 metres (620 ft)||April–May 2005, a series of mini-hydronuclear experiments interpreting Armando results.|
|Unicorn||August 31, 2006 01:00:--||NTS Area U6c||1,222 metres (4,009 ft) - 190 metres (620 ft)||"…confirm nuclear performance of the W88 warhead with a newly-manufactured pit." Early pit studies.|
|Thermos||January 1, 2007||NTS Area U1a||1,222 metres (4,009 ft) - 190 metres (620 ft)||Feb-6 thru May 3, 2007, 12 mini-hydronuclear experiments in thermos-sized flasks.|
|Bacchus||September 16, 2010||NTS Area U1a.05?||1,222 metres (4,009 ft) - 190 metres (620 ft)|
|Barolo A||December 1, 2010||NTS Area U1a.05?||1,222 metres (4,009 ft) - 190 metres (620 ft)|
|Barolo B||February 2, 2011||NTS Area U1a.05?||1,222 metres (4,009 ft) - 190 metres (620 ft)|
|Castor||September 1, 2012||NTS Area U1a||1,222 metres (4,009 ft) - 190 metres (620 ft)||Not even a subcrit, contained no plutonium; a dress rehearsal for Pollux.|
|Pollux||December 5, 2012||NTS Area U1a||1,222 metres (4,009 ft) - 190 metres (620 ft)||A subcritical test with a scaled down warhead mockup.|
|Leda||June 15, 2014||NTS Area U1a||1,222 metres (4,009 ft) - 190 metres (620 ft)||Like Castor, the plutonium was replaced by a surrogate; this is a dress rehearsal for the later Lydia. The target was a weapons pit mock-up.|
|Lydia||??-??-2015||NTS Area U1a||1,222 metres (4,009 ft) - 190 metres (620 ft)||Expected to be a plutonium subcritical test with a scaled down warhead mockup.[ citation needed ]|
There have also been simulations of the effects of nuclear detonations using conventional explosives (such as the Minor Scale U.S. test in 1985). The explosives might be spiked with radioactive materials to simulate fallout dispersal.
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.
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.
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 [update] , 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) have been 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. while the estimated number of underground nuclear tests conducted in the period from 1957 to 1992 is 1,352 explosions with a total yield of 90 Mt.
The nuclear powers have conducted more than 2,000 nuclear test explosions (numbers are approximate, as some test results have been disputed):
There may also have been at least three alleged but unacknowledged nuclear explosions (see list of alleged nuclear tests) 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.
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:
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 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. As of May 2012 [update] , 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:
|Name||Agreement date||In force date||In effect today?||Notes|
|Unilateral USSR ban||March 31, 1958||March 31, 1958||no||USSR unilaterally stops testing provided the West does as well.|
|Bilateral testing ban||August 2, 1958||August 2, 1958||no||USA agrees; ban begins on 31 October 1958, 3 November 1958 for the Soviets, and lasts until abrogated by a USSR test on 1 September 1961.|
|Antarctic Treaty System||December 1, 1959||June 23, 1961||yes||Bans testing of all kinds in Antarctica.|
|Partial Nuclear Test Ban Treaty (PTBT)||August 5, 1962||October 10, 1963||yes||Ban on all but underground testing.|
|Outer Space Treaty||January 27, 1967||October 10, 1967||yes||Bans testing on the moon and other celestial bodies.|
|Treaty of Tlatelolco||February 14, 1967||April 22, 1968||yes||Bans testing in South America and the Caribbean Sea Islands.|
|Nuclear Non-proliferation Treaty||January 1, 1968||March 5, 1970||yes||Bans the proliferation of nuclear technology to non-nuclear nations.|
|Seabed Arms Control Treaty||February 11, 1971||May 18, 1972||yes||Bans emplacement of nuclear weapons on the ocean floor outside territorial waters.|
|Strategic Arms Limitation Treaty (SALT I)||January 1, 1972||no||A five-year ban on installing launchers.|
|Anti-Ballistic Missile Treaty||May 26, 1972||August 3, 1972||no||Restricts ABM development; additional protocol added in 1974; abrogated by the USA in 2002.|
|Agreement on the Prevention of Nuclear War||June 22, 1973||June 22, 1973||yes||Promises to make all efforts to promote security and peace.|
|Threshold Test Ban Treaty||July 1, 1974||December 11, 1990||yes||Prohibits higher than 150 kt for underground testing.|
|Peaceful Nuclear Explosions Treaty (PNET)||January 1, 1976||December 11, 1990||yes||Prohibits higher than 150 kt, or 1500kt in aggregate, testing for peaceful purposes.|
|Moon Treaty||January 1, 1979||January 1, 1984||no||Bans use and emplacement of nuclear weapons on the moon and other celestial bodies.|
|Strategic Arms Limitations Treaty (SALT II)||June 18, 1979||no||Limits strategic arms. Kept but not ratified by the US, abrogated in 1986.|
|Treaty of Rarotonga||August 6, 1985||?||Bans nuclear weapons in South Pacific Ocean and islands. US never ratified.|
|Intermediate Range Nuclear Forces Treaty (INF)||December 8, 1987||June 1, 1988||yes||Eliminates Intermediate Range Ballistic Missiles (IRBMs). Implemented by 1 June 1991. Both sides allege the other is in violation of the treaty.|
|Treaty on Conventional Armed Forces in Europe||November 19, 1990||July 17, 1992||yes||Bans categories of weapons, including conventional, from Europe. Russia notified signatories of intent to suspend, 14 July 2007.|
|Strategic Arms Reduction Treaty I (START I)||July 31, 1991||December 5, 1994||no||35-40% reduction in ICBMs with verification. Treaty expired 5 December 2009, renewed (see below).|
|Treaty on Open Skies||March 24, 1992||January 1, 2002||yes||Allows for unencumbered surveillance over all signatories.|
|US unilateral testing moratorium||October 2, 1992||October 2, 1992||no||George. H. W. Bush declares unilateral ban on nuclear testing. Extended several times, not yet abrogated.|
|Strategic Arms Reduction Treaty (START II)||January 3, 1993||January 1, 2002||no||Deep reductions in ICBMs. Abrogated by Russia in 2002 in retaliation of US abrogation of ABM Treaty.|
|Southeast Asian Nuclear-Weapon-Free Zone Treaty (Treaty of Bangkok)||December 15, 1995||March 28, 1997||yes||Bans nuclear weapons from southeast Asia.|
|African Nuclear Weapon Free Zone Treaty (Pelindaba Treaty)||January 1, 1996||July 16, 2009||yes||Bans nuclear weapons in Africa.|
|Comprehensive Nuclear Test Ban Treaty (CTBT)||September 10, 1996||yes (effectively)||Bans all nuclear testing, peaceful and otherwise. Strong detection and verification mechanism (CTBTO). US has signed and adheres to the treaty, though has not ratified it.|
|Treaty on Strategic Offensive Reductions (SORT, Treaty of Moscow)||May 24, 2002||June 1, 2003||no||Reduces warheads to 1700-2200 in ten years. Expired, replaced by START II.|
|START I treaty renewal||April 8, 2010||January 26, 2011||yes||Same provisions as START I.|
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.
The following list is of milestone nuclear explosions. In addition to the atomic bombings of Hiroshima and Nagasaki, the first nuclear test of a given weapon type for a country is included, and tests which were otherwise notable (such as the largest test ever). All yields (explosive power) are given in their estimated energy equivalents in kilotons of TNT (see TNT equivalent). Putative tests (like Vela Incident) have not been included.
|1945-07-16||Trinity||18–20||USA||First fission device test, first plutonium implosion detonation|
|1945-08-06||Little Boy||12–18||USA||Bombing of Hiroshima, Japan, first detonation of a uranium gun-type device, first use of a nuclear device in combat.|
|1945-08-09||Fat Man||18–23||USA||Bombing 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||RDS-1||22||USSR||First fission weapon test by the USSR|
|1952-10-03||Hurricane||25||UK||First fission weapon test by the UK|
|1952-11-01||Ivy Mike||10,400||USA||First cryogenic fusion fuel "staged" thermonuclear weapon, primarily a test device and not weaponized|
|1952-11-16||Ivy King||500||USA||Largest pure-fission weapon ever tested|
|1953-08-12||Joe 4||400||USSR||First fusion weapon test by the USSR (not "staged")|
|1954-03-01||Castle Bravo||15,000||USA||First dry fusion fuel "staged" thermonuclear weapon; a serious nuclear fallout accident occurred; largest nuclear detonation conducted by United States|
|1955-11-22||RDS-37||1,600||USSR||First "staged" thermonuclear weapon test by the USSR (deployable)|
|1957-05-31||Orange Herald||720||UK||Largest boosted fission weapon ever tested. Intended as a fallback "in megaton range" in case British thermonuclear development failed.|
|1957-11-08||Grapple X||1,800||UK||First (successful) "staged" thermonuclear weapon test by the UK|
|1960-02-13||Gerboise Bleue||70||France||First fission weapon test by France|
|1961-10-31||Tsar Bomba||50,000||USSR||Largest thermonuclear weapon ever tested—scaled down from its initial 100 Mt design by 50%|
|1964-10-16||596||22||PR China||First fission weapon test by the People's Republic of China|
|1967-06-17||Test No. 6||3,300||PR China||First "staged" thermonuclear weapon test by the People's Republic of China|
|1968-08-24||Canopus||2,600||France||First "staged" thermonuclear weapon test by France|
|1974-05-18||Smiling Buddha||12||India||First fission nuclear explosive test by India|
|1998-05-11||Pokhran-II||45-50||India||First potential fusion/boosted weapon test by India; first deployable fission weapon test by India|
|1998-05-28||Chagai-I||40||Pakistan||First fission weapon (boosted) test by Pakistan|
|2006-10-09||2006 North Korean nuclear test||under 1||North Korea||First fission weapon test by North Korea (plutonium-based)|
|2017-09-03||2017 North Korean nuclear test||200-300||North Korea||First "staged" thermonuclear weapon test claimed by North Korea|
"Staging" refers to whether it was a "true" hydrogen bomb of the so-called Teller-Ulam configuration or simply a form of a boosted fission weapon. For a more complete list of nuclear test series, see List of nuclear tests. Some exact yield estimates, such as that of the Tsar Bomba and the tests by India and Pakistan in 1998, are somewhat contested among specialists.
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 underground. It is also abbreviated as the Limited Test Ban Treaty (LTBT) and Nuclear Test Ban Treaty (NTBT), though the latter may also refer to the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which succeeded the PTBT for ratifying parties.
The Nevada National Security Site, previously the Nevada Test Site (NTS), is a United States Department of Energy reservation located in southeastern Nye County, Nevada, about 65 miles (105 km) northwest of the city of Las Vegas. Formerly known as the Nevada Proving Grounds, the site was established on January 11, 1951 for the testing of nuclear devices, covering approximately 1,360 square miles (3,500 km2) of desert and mountainous terrain. Nuclear weapons testing at the Nevada Test Site began with a 1-kiloton-of-TNT (4.2 TJ) bomb dropped on Frenchman Flat on January 27, 1951. Many of the iconic images of the nuclear era come from the NTS. NNSS is operated by Mission Support and Test Services, LLC.
Project Plowshare was the overall United States program for the development of techniques to use nuclear explosives for peaceful construction purposes. As part of the program, 31 nuclear warheads were detonated in 27 separate tests. Plowshare was the US portion of what are called Peaceful Nuclear Explosions (PNE); a similar Soviet program was carried out under the name Nuclear Explosions for the National Economy.
Operation Greenhouse was the fifth American nuclear test series, the second conducted in 1951 and the first to test principles that would lead to developing thermonuclear weapons. Conducted at the new Pacific Proving Ground, specifically on islands of the Enewetak Atoll, all of the devices were mounted in large steel towers, to simulate air bursts. This series of nuclear weapons tests was preceded by Operation Ranger and succeeded by Operation Buster-Jangle.
Operation Teapot was a series of fourteen nuclear test explosions conducted at the Nevada Test Site in the first half of 1955. It was preceded by Operation Castle, and followed by Operation Wigwam. Wigwam was, administratively, a part of Teapot, but it is usually treated as a class of its own. The aims of the operation were to establish military tactics for ground forces on a nuclear battlefield and to improve the nuclear weapons used for strategic delivery.
Operation Wigwam involved a single test of the Mark 90 Betty nuclear bomb. It was conducted between Operation Teapot and Project 56 on May 14, 1955, about 500 miles (800 km) southwest of San Diego, California. 6,800 personnel aboard 30 ships were involved in Wigwam. The purpose of Wigwam was to determine the vulnerability of submarines to deeply detonated nuclear weapons, and to evaluate the feasibility of using such weapons in a combat situation. The task force commander, Admiral John Sylvester, was embarked on the task force flagship USS Mount McKinley. WIGWAM was the first atomic test in the deep ocean, and it remains the only test that has been conducted in water deeper than 1000 ft.
Operation Hardtack I was a series of 35 nuclear tests conducted by the United States from April 28 to August 18 in 1958 at the Pacific Proving Grounds. At the time of testing, the Operation Hardtack I test series included more nuclear detonations than the total of all prior nuclear explosions in the Pacific Ocean. These tests followed the Project 58/58A series, which occurred from 1957 December 6 to 1958, March 14, and preceded the Operation Argus series, which took place in 1958 from August 27 to September 6.
Chagan (Чага́н) was a Soviet underground nuclear test conducted at the Semipalatinsk Test Site on January 15, 1965.
The Pacific Proving Grounds was the name given by the United States government to a number of sites in the Marshall Islands and a few other sites in the Pacific Ocean at which it conducted nuclear testing between 1946 and 1962. The U.S. tested a nuclear weapon on Bikini Atoll on June 30, 1946. This was followed by Baker on July 24, 1946.
Peaceful nuclear explosions (PNEs) are nuclear explosions conducted for non-military purposes. Proposed uses include excavation for the building of canals and harbours, electrical generation, the use of nuclear explosions to drive spacecraft, and as a form of wide-area fracking. PNEs were an area of some research from the late 1950s into the 1980s, primarily in the United States and Soviet Union.
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, though to date all fusion-based weapons have used a fission device to initiate fusion, and a pure fusion weapon remains a hypothetical device.
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 explosion may be contained, with no release of radioactive materials to the atmosphere.
Operation Charioteer was a series of 16 nuclear tests conducted by the United States in 1985-1986 at the Nevada Test Site. These tests followed the Operation Grenadier series and preceded the Operation Musketeer series.
The United States's Fulcrum nuclear test series was a group of 21 nuclear tests conducted in 1976-1977. These tests followed the Operation Anvil series and preceded the Operation Cresset series.
Yucca Flat is a closed desert drainage basin, one of four major nuclear test regions within the Nevada Test Site (NTS), and is divided into nine test sections: Areas 1 through 4 and 6 through 10. Yucca Flat is located at the eastern edge of NTS, about ten miles (16 km) north of Frenchman Flat, and 65 miles (105 km) from Las Vegas, Nevada. Yucca Flat was the site for 739 nuclear tests – nearly four of every five tests carried out at the NTS.
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