Preparation for an underground nuclear test at the
Nevada Test Site in the 1980s. Visible in the photograph are the test monitoring equipment, as well as the subsidence craters created by previous underground nuclear tests.
A nuclear test explosion is an experiment involving the detonation of a nuclear warhead.
Motivations for testing generally are broken into the categories:
- "weapons related" (verifying that a weapon works, or examining exactly how it works)
- "weapons effects" (how weapons behave under various conditions, and how structures behave when subjected to weapons).
Often, though, testing has also been a demonstration of the possessing nation's military and scientific strength.
Nuclear weapons tests are generally classified as being either "atmospheric" (in or above the atmosphere), "underground," or "underwater." Of these, underground testing contained in deep shafts poses the least health risk in terms of fallout. Atmospheric testing which comes in contact with the ground or other materials poses the highest risk. Nuclear weapons have been tested by dropping them from planes (an "airdrop"), from the tops of towers, hoisted from balloons, on barges at sea, attached to the bottom of ships, and even shot into outer space by rockets (for the latter see below).
The first atomic test was detonated 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, 1952, also by the United States. The largest nuclear weapon ever tested was the "Tsar Bomba" of the Soviet Union at Novaya Zemlya, 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 tests. France continued atmospheric testing until 1974, while China continued up until 1980. The last underground test by the United States was in 1992, the Soviet Union in 1990, the United Kingdom in 1991, and both France and China continued testing up until 1996. After adopting the Comprehensive Test Ban Treaty in 1996, all of these states have pledged to discontinue all nuclear testing. Non-signatories India and Pakistan both last tested nuclear weapons in 1998.
History
The first nuclear test, "
Trinity", took place on July 16, 1945.
The first nuclear test was conducted by the United States 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 the scientists and military officers 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 only six nuclear tests before the Soviet Union developed their first atomic bomb (Joe 1) and tested it on August 29, 1949. Neither country had very many nuclear weapons to spare at first, and so testing was relatively limited (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 were also using a site in the Marshall Islands (Pacific Proving Grounds) for extensive nuclear testing.
The early tests were used primarily to discern the military effects of nuclear weapons (Crossroads had involved the effect of nuclear 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.
Nuclear tests can involve many hazards. A number of these were best 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 of 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 ahead of time. The fallout plume spread high levels of radiation for over a hundred miles, contaminating a number of populated islands in nearby atoll formations (the populations had to be evacuated, and many suffered from radiation burns and later from other effects such as increased cancer rate and birth defects), as well as a Japanese fishing boat. One member of the fishing boat died from radiation sickness after returning to port, and it was feared that the radioactive fish they had been carrying had made it into the Japanese food supply.
Because of concerns about worldwide fallout levels, the
Partial Test Ban Treaty was signed in 1963. Above are the per capita
thyroid doses in the continental United States resulting from all exposure routes from all atmospheric nuclear tests conducted at the
Nevada Test Site from 1951-1962.
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 lead to the Partial Test Ban Treaty in 1963, which limited signatories to only underground testing. Not all atmospheric tests stopped, however, but because the United States and the Soviet Union in particular stopped testing aboveground it cut the number of atmospheric tests down substantially, since around 86% of all nuclear tests were conducted by those two countries. France continued atmospheric testing until 1974, and People's Republic of China until 1980.
Almost all new nuclear powers have announced their possession of nuclear weapons with a nuclear test. The only acknowledged nuclear power which claims to have never conducted a test was South Africa (who has since claimed to have dismantled all of their weapons). The state of Israel is widely thought by intelligence agencies to possess a sizeable nuclear arsenal, though it has never tested. 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 the value of these simulations without actual test result data is thought to be slim.
The
Sedan test of 1962 was an experiment by the United States in using nuclear weapons to excavate large amounts of earth.
Some nuclear testing has been for "peaceful" purposes. These so-called peaceful nuclear explosions 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. In most cases the results were too radioactive for use, and the programs proved neither economically sound or politically favorable.
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 Mt Tsar Bomba, by the Soviet Union in 1961. This weapon was far too large to be practically used against an enemy target, and it is not thought that any were actually developed except the one which was detonated. The weapon was used by the USSR as a show of Soviet strength and force, rather than to be developed as an actual weapon or for specifically scientific purposes.
There have been many attempts to limit the number and size of nuclear testing; the most far-reached was the Comprehensive Test Ban Treaty of 1996, which was not ratified by the United States. The last worldwide nuclear tests were in 1998. 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.
Milestone nuclear explosions
The following list is of milestone nuclear explosions. In addition to the atomic bombings of Hiroshima and Nagasaki, the first nuclear test of a given weapon type for a country is included, and tests which were otherwise notable (such as the largest test ever). All yields (explosive power) are given in their estimated energy equivalents in kilotons of TNT (see megaton).
| Date |
Name |
Yield (kt) |
Country |
Significance |
| Jul 16 1945 |
Trinity |
19 |
 USA |
First fission weapon test |
| Aug 6 1945 |
Little Boy |
15 |
USA |
Bombing of Hiroshima, Japan |
| Aug 9 1945 |
Fat Man |
21 |
USA |
Bombing of Nagasaki, Japan |
| Aug 29 1949 |
Joe 1 |
22 |
 USSR |
First fission weapon test by the USSR |
| Oct 3 1952 |
Hurricane |
25 |
 UK |
First fission weapon test by the UK |
| Nov 1 1952 |
Ivy Mike |
10,200 |
USA |
First "staged" thermonuclear weapon test (not deployable) |
| Aug 12 1953 |
Joe 4 |
400 |
USSR |
First fusion weapon test by the USSR (not "staged", but deployable) |
| Mar 1 1954 |
Castle Bravo |
15,000 |
USA |
First deployable "staged" thermonuclear weapon; fallout accident |
| Nov 22 1955 |
RDS-37 |
1,600 |
USSR |
First "staged" thermonuclear weapon test by the USSR (deployable) |
| Nov 8 1957 |
Grapple X |
1,800 |
UK |
First (successful) "staged" thermonuclear weapon test by the UK |
| Feb 13 1960 |
Gerboise Blue |
60 |
 France |
First fission weapon test by France |
| Oct 31 1961 |
Tsar Bomba |
57,000 |
USSR |
Largest thermonuclear weapon ever tested |
| Oct 16 1964 |
596 |
22 |
 China |
First fission weapon test by China |
| Jun 17 1967 |
Test No. 6 |
3,300 |
China |
First "staged" thermonuclear weapon test by China |
| Aug 24 1968 |
Canopus |
2,600 |
France |
First "staged" thermonuclear test by France |
| May 18 1974 |
Smiling Buddha |
12 |
 India |
First fission "peaceful nuclear explosive" test by India |
| May 11 1998 |
Shakti I |
43 |
India |
First potential fusion/boosted weapon test by India
(exact yields disputed, between 25kt and 45kt) |
| May 13 1998 |
Shakti II |
12 |
India |
First fission "weapon" test by India |
| May 28 1998 |
Chagai-I |
9 |
 Pakistan |
First fission weapon test by Pakistan |
"Deployable" refers to whether the device tested could be hypothetically used in actual combat (in contrast with a proof-of-concept device). "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.
Nuclear testing by country
- Main article: List of nuclear tests
Locations of where nuclear weapons have been tested or used
The nuclear powers have conducted at least 2,000 nuclear test explosions (numbers are approximated, as some test results have been disputed):
- United States: 1,050 tests (involving 1,125 devices,331 atmospheric tests), most at Nevada Test Site and the Pacific Proving Grounds in the Marshall Islands, with ten other tests taking place at various locations in the United States, including Alaska, Colorado, Mississippi, and New Mexico.
- Soviet Union: between 715 and 969 tests, most at Semipalatinsk Test Site and Novaya Zemlya, and a few more at various sites in Russia, Kazakhstan, Turkmenistan, and Ukraine.
- France: 210 tests, mostly at Reggane and Ekker in Algeria, and Fangataufa and Moruroa in French Polynesia.
- United Kingdom: 45 tests (21 in Australian territory, including 9 in mainland South Australia at Maralinga and Emu Field, many others in the U.S. as part of joint test series)
- China: 45 tests (23 atmospheric and 22 underground, all conducted at Lop Nur Nuclear Weapons Test Base, in Malan, Xinjiang)
- India: between 5 and 6 tests, at Pokhran.
- Pakistan: between 3 and 6 tests, at Chagai Hills.
Additionally, there may have been at least three alleged/disputed/unacknowledged nuclear explosions (see below).
From the first nuclear test in 1945 until the latest tests by Pakistan in 1998, there was never a period of more than 22 months with no nuclear testing. Therefore, the period from June of 1998 to the present has been, by far, the longest period since 1945 with no acknowledged nuclear tests.
Alleged tests
There have been a number of significant alleged/disputed/unacknowledged accounts of countries testing nuclear explosives. Their status is either not certain or entirely disputed by most mainstream experts.
Japan
There is a disputed report about the Japanese atomic program being able to test a nuclear weapon in Korea on August 12, 1945, a few days after the atomic bombings of Hiroshima and Nagasaki on August 6 and 9, and three days before the Japanese surrender on August 15, but this is seen as being highly unlikely by mainstream historians. See Japanese atomic program for more information.
Israel/South Africa
In what is known as the Vela Incident, Israel and/or South Africa may have detonated a nuclear device on September 22, 1979 in the Indian Ocean, according to satellite data. It is not certain whether there was actually a test, also it is not known who would have been responsible for it. See Vela Incident for more information.
North Korea
On September 9, 2004 it was reported by South Korean media that there had been a large explosion at the Chinese/North Korean border. This explosion left a crater visible by satellite and precipitated a large (2 mile diameter) mushroom cloud. The United States and South Korea quickly downplayed this, explaining it away as a forest fire which had nothing to do with the DPRK's nuclear weapons program. See Ryanggang explosion for more information.
Germany
Hitlers Bombe, a book published in German by the historian Rainer Karlsch in 2005, has alleged that there is evidence that Nazi Germany performed some sort of test of a "nuclear device" (a hybrid fusion device unlike any modern nuclear weapons) in March 1945, though the evidence for this has not yet been fully evaluated, and has been doubted by many historians.
Rocket-propelled warheads
The Frigate Bird explosion seen through the periscope of
USS Carbonero (SS-337)
Missiles and nuclear warheads have usually been tested separately. The only US live test of an operational missile was the following:
- Frigate Bird - on May 6, 1962, a UGM-27 Polaris A-1 missile with a live 600 kt W47 warhead was launched from the USS Ethan Allen (SSBN-608); it flew 1900 km, re-entered the atmosphere, and detonated at an altitude of 3.4 km over the South Pacific. The test was part of Operation Dominic I. Planned as a method to dispel doubts about whether the USA's nuclear missiles would actually function in practice, it had less effect than was hoped, as the stockpile warhead was substantially modified prior to testing, and the missile tested was a relatively low-flying SLBM and not a high-flying ICBM.
Other live tests with the nuclear explosive delivered by rocket by the USA include:
- Operation Argus - three tests
- On August 1, 1958, Redstone rocket #CC50 launched nuclear test Teak that detonated at an altitude of 77.8-km. On August 12, 1958, Redstone #CC51 launched nuclear test Orange to a detonation altitude of 43 km. Both were part of Operation Hardtack and had a yield of 3.75 Mt
- On July 9, 1962, Thor missile 195 launched a Mk4 reentry vehicle containing a W49 thermonuclear warhead to an altitude of 248 miles (400 km). The warhead detonated with a yield of 1.45 Mt. This was the Starfish Prime event of nuclear test operation Dominic-Fishbowl
- In the same series in 1962: Checkmate, Bluegill, Kingfish, and Tightrope
The Soviet Union tested a number of nuclear explosives on rockets as part of their development of a localised anti-ballistic missile system in the 1960s.
See also
References
- History
- 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
The content of this page is retrieved from http://en.wikipedia.org/wiki/Nuclear_testing under GFDL
