Editing Nuclear weapons testing (section)

==History==
{{Main|Timeline of nuclear weapons development}}
[[File:Phoenix en route to North Vietnam, 1967.jpg|thumb|right|The ''[[Phoenix of Hiroshima]]'' (foreground) in Hong Kong Harbor in 1967, was involved in several famous [[anti-nuclear]] protest voyages against nuclear testing in the Pacific.]] 
[[File:Wfm sts overview.png|thumb|The {{convert|18000|km2||adj=on|order=flip}} expanse of the [[Semipalatinsk Test Site]] (indicated in red), attached to [[Kurchatov, Kazakhstan|Kurchatov]] (along the [[Irtysh river]]). The site comprised an area [[the size of Wales]].<ref>{{cite web |url=http://www.thebulletin.org/web-edition/features/the-lasting-toll-of-semipalatinsks-nuclear-testing |title=The lasting toll of Semipalatinsk's nuclear testing |author=Togzhan Kassenova |date=28 September 2009 |work=Bulletin of the Atomic Scientists }}</ref>]]
{| class="wikitable sortable mw-collapsible"
|+Notable nuclear explosions
!Significance
!Country
!Name
!Date
!Yield
|-
|First plutonium test
| rowspan="2" |{{Flag|United States|1912}}
| rowspan="2" |[[Trinity (nuclear test)|Trinity]]
| rowspan="2" |July 16, 1945
| rowspan="2" |25 kt
|-
|First implosion test
|-
|First uranium bomb
| rowspan="2" |{{Flag|United States|1912}}
| rowspan="2" |[[Atomic bombings of Hiroshima and Nagasaki|Atomic bombing of Hiroshima]]
| rowspan="2" |August 6, 1945
| rowspan="2" |15 kt
|-
|First gun-type bomb
|-
|First [[Fusion boosting|thermonuclear boosting]]
|{{Flag|United States|1912}}
|[[Greenhouse George]]
|May 8, 1951
|225 kt
|-
|First underground test
|{{Flag|United States|1912}}
|[[Operation Buster–Jangle|Buster–Jangle Uncle]]
|November 29, 1951
|1.2 kt
|-
|First [[Teller-Ulam design|Teller-Ulam]] test
| rowspan="2" |{{Flag|United States|1912}}
| rowspan="2" |[[Ivy Mike]]
| rowspan="2" |November 1, 1952
| rowspan="2" |10.4 Mt
|-
|First cryogenic deuterium test
|-
|First deliverable thermonuclear test
| rowspan="2" |{{Flag|Soviet Union}}
| rowspan="2" |[[RDS-6s]]
| rowspan="2" |August 12, 1953
| rowspan="2" |400 kt
|-
|First solid-fuelled thermonuclear test
|-
|First exoatmospheric test
|{{Flag|United States|1912}}
|[[Operation Argus|Argus I]]
|August 27, 1958
|1.7 kt
|-
|Most recent atmospheric test
|{{Flag|China}}
|[[List of nuclear weapons tests of China|1980 Chinese nuclear test]]
|October 16, 1980
|1 Mt
|-
|Most recent test
|{{Flag|North Korea}}
|[[2017 North Korean nuclear test]]
|September 3, 2017
|50-300 kt
|}
The first atomic weapons test was conducted near Alamogordo, New Mexico, on July 16, 1945, during the [[Manhattan Project]], and given the codename "[[Trinity test|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 [[Effects of nuclear explosions|nuclear explosion]] would be before they were used in combat against Japan. The test gave a good approximation of many of the explosion's effects, but 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 US used two weapons for ''[[Operation Crossroads]]'' in 1946, they were detonating over 20% of their current arsenal). 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]], both countries developed accelerated testing programs, testing many hundreds of bombs over the last half of the 20th century.

[[File:Bravo fallout2.png|left|thumb|In 1954 the [[Castle Bravo]] fallout plume spread dangerous levels of radiation over an area over {{convert|100|mi|||}} long, including inhabited islands.]]

Atomic and nuclear tests can involve many hazards. Some of these were illustrated in the US [[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 [[nuclear weapons yield|yield]] of 15 [[TNT equivalent|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 {{convert|100|mi|||}}, contaminating 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.

[[File:US fallout exposure.png|right|thumb|Because of concerns about worldwide fallout levels, the [[Partial Test Ban Treaty]] was signed in 1963. Above are the per capita [[thyroid]] doses (in [[Rad (unit)|rads]]) in the continental United States resulting from all exposure routes from all atmospheric nuclear tests conducted at the [[Nevada Test Site]] from 1951 to 1962.]]

Castle Bravo was the worst US nuclear accident, but many of its component problems—unpredictably large yields, changing weather patterns, unexpected fallout [[radioactive contamination|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 [[supercomputer]]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]] of 1996, which has not, {{as of|2013|lc=y}}, been ratified by eight of the "[[Comprehensive Test Ban Treaty#Status|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 [[List of nuclear weapons tests|total nuclear test megatonnage]], from 1945 to 1992, 520 atmospheric nuclear explosions (including eight underwater) were conducted with a total yield of 545 [[TNT equivalent|megaton]]s,<ref name="auto">{{cite book|title=Atmospheric Nuclear Tests|first=O. A.|last=Pavlovski|date=1 January 1998|publisher=Springer, Berlin, Heidelberg|pages=219–260|doi=10.1007/978-3-662-03610-5_17|chapter = Radiological Consequences of Nuclear Testing for the Population of the Former USSR (Input Information, Models, Dose, and Risk Estimates)|isbn = 978-3-642-08359-4}}</ref> with a peak occurring in 1961–1962, when 340 megatons were detonated in the atmosphere by the United States and [[Soviet Union]],<ref>{{cite web|url=http://www.atomicarchive.com/Docs/Effects/wenw_chp2.shtml|title=Radioactive Fallout - Worldwide Effects of Nuclear War - Historical Documents |website=Atomciarchive.com}}</ref> 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.<ref name="auto"/>

<gallery mode=packed heights=180>
Image: Trinity shot color.jpg|The first atomic test, "[[Trinity test|Trinity]]", took place on July 16, 1945.
Image: Sedan Plowshare Crater.jpg|The [[Sedan (nuclear test)|Sedan]] test of 1962 was an experiment by the United States in using nuclear weapons to excavate large amounts of earth.
File:330-PS-3256 (45898 AC) (17204655228).jpg|[[Kytoon]] balloons were used on Indian Springs Air Force Base, Nevada, April 20, 1952, to get exact weather information during atomic test periods.
</gallery>