Nuclear explosion
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A nuclear explosion occurs as a result of the rapid release of energy from an intentionally high-speed nuclear reaction. The driving reaction may be nuclear fission, nuclear fusion or a multistage 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.
Atmospheric nuclear explosions are associated with "mushroom clouds" although mushroom clouds can occur with large chemical explosions and it is possible to have an air burst nuclear explosion without these clouds. Atmospheric nuclear explosions produce large amounts of radiation and radioactive debris.
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[edit] History
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.
The primary application to date has been military (i.e. nuclear weapons). However, there are other potential applications, which have not yet been explored, or have been considered but abandoned. They include:
- Nuclear pulse propulsion, including using a nuclear explosion as asteroid deflection strategy.
- Power generation; see PACER
- Peaceful nuclear explosions
[edit] 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 |
|---|---|---|---|---|
| 16 Jul 1945 | Trinity | 19 |  USA |
First fission device test, first plutonium implosion detonation |
| 6 Aug 1945 | Little Boy | 15 | USA |
Bombing of Hiroshima, Japan, first detonation of an enriched uranium gun-type device |
| 9 Aug 1945 | Fat Man | 21 | USA |
Bombing of Nagasaki, Japan |
| 29 Aug 1949 | RDS-1 | 22 |  USSR |
First fission weapon test by the USSR |
| 3 Oct 1952 | Hurricane | 25 |  UK |
First fission weapon test by the UK |
| 1 Nov 1952 | Ivy Mike | 10,400 | USA |
First "staged" thermonuclear weapon test (not deployable) |
| 12 Aug 1953 | Joe 4 | 400 | USSR |
First fusion weapon test by the USSR (not "staged", but deployable) |
| 1 Mar 1954 | Castle Bravo | 15,000 | USA |
First deployable "staged" thermonuclear weapon; fallout accident where some people were radiation-poisoned |
| 22 Nov 1955 | RDS-37 | 1,600 | USSR |
First "staged" thermonuclear weapon test by the USSR (deployable) |
| 8 Nov 1957 | Grapple X | 1,800 | UK |
First (successful) "staged" thermonuclear weapon test by the UK |
| 13 Feb 1960 | Gerboise Bleue | 70 |  France |
First fission weapon test by France |
| 31 Oct 1961 | Tsar Bomba | 50,000 | USSR |
Largest thermonuclear weapon ever tested |
| 16 Oct 1964 | 596 | 22 |  PR China |
First fission weapon test by the People's Republic of China |
| 17 Jun 1967 | Test No. 6 | 3,300 | PR China |
First "staged" thermonuclear weapon test by the People's Republic of China |
| 24 Aug 1968 | Canopus | 2,600 | France |
First "staged" thermonuclear test by France |
| 18 May 1974 | Smiling Buddha | 12 |  India |
First fission nuclear explosive test by India |
| 11 May 1998 | Shakti I | 43 | India |
First potential fusion/boosted weapon test by India (exact yields disputed, between 25kt and 45kt) |
| 11 May 1998 | Shakti II | 12 | India |
First deployable fission weapon test by India |
| 28 May 1998 | Chagai-I | 9-12 |  Pakistan |
First fission weapon test by Pakistan. |
| 9 Oct 2006 | Hwadae-ri | <1 |  North Korea |
First fission device tested by North Korea; resulted as a fizzle |
"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.
[edit] Peaceful nuclear explosions
Peaceful nuclear explosions (PNEs) are nuclear explosions conducted for non-military purposes, such as activities related to economic development including the creation of canals. During the 1960s and 1970s, both the United States and the Soviet Union conducted a number of PNEs. Six of the explosions by the Soviet Union are considered to have been of an applied nature, not just tests.
Subsequently the United States and the Soviet Union halted their programs. Definitions and limits are covered in the Peaceful Nuclear Explosions Treaty of 1976.
[edit] Nuclear weapons
In the history of warfare, two nuclear weapons have been detonated — both by the United States, during the closing days of World War II. The first event occurred on the morning of 6 August 1945, when the United States dropped a uranium gun-type device code-named "Little Boy" on the Japanese city of Hiroshima. The second event occurred three days later when, again, the United States dropped a plutonium implosion-type device code-named "Fat Man" on the city of Nagasaki. These bombings resulted in the immediate deaths of around 120,000 people and even more over time. The use of these weapons was and remains controversial. (See Atomic bombings of Hiroshima and Nagasaki for a full discussion).
[edit] Nuclear testing
Nuclear tests are experiments carried out to determine the effectiveness, yield and explosive capability of nuclear weapons. Throughout the twentieth century, most nations that have developed nuclear weapons have staged tests of them. Testing nuclear weapons can yield information about how the weapons work, as well as how the weapons behave under various conditions and how structures behave when subjected to nuclear explosions. Additionally, nuclear testing has often been used as an indicator of scientific and military strength, and many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status by means of a nuclear test.
[edit] Effects of nuclear explosions
The dominant effects of a nuclear weapon (the blast and thermal radiation) are the same physical damage mechanisms as conventional explosives, but the energy produced by a nuclear explosive is millions of times more per gram and the temperatures reached are in the tens of megakelvins.
