Nuclear explosions

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, 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. It is possible to have an air-burst nuclear explosion without these clouds. Nuclear explosions produce radiation and radioactive debris.

Any nuclear explosion (or nuclear war) would have wide-ranging, long-term, catastrophic effects, that could threaten the survival of humankind. Radioactive contamination would cause genetic mutations and cancer across many generations.

The first nuclear explosion occurred on July 16, 1945 at 5:50 am on the Trinity Test Site near Alamogordo, New Mexico in the United States, an area now known as the White Sands Missile Range. The event involved the full-scale testing of an implosion-type fission atomic bomb. In a memorandum to the U.S. Secretary of War, General Leslie Groves describes the yield as equivalent to 15,000 to 20,000 tons of TNT. Following this test, a uranium-gun type nuclear bomb (Little Boy) was dropped on the Japanese city of Hiroshima on August 6, 1945, with a blast yield of 15 kilotons; and a plutonium implosion-type bomb (Fat Man) on Nagasaki on August 9, 1945, with a blast yield of 21 kilotons. In the years following World War II, eight countries have conducted nuclear tests with 2475 devices fired in 2120 tests.

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