This page shows a simulation of the 15000 kt nuclear bomb (15000 kt) detonated over Namu Island, Bikini Atoll, Marshall Islands (1954). The map displays the estimated fireball, the zones of heavy, moderate and light blast damage, thermal radiation and ionizing radiation. Click «What does that mean?» for a detailed legend, or run your own detonation on the main page.
Castle Bravo, 1 March 1954
Castle Bravo was the first deliverable hydrogen bomb the United States tested, fired from a barge-like platform on a reef off Namu Island in Bikini Atoll. It was expected to yield about 6 megatons; it produced 15. The designers had assumed that lithium-7 in the dry fuel was inert, but under fast-neutron bombardment it bred extra tritium, and the device ran away to two and a half times its design yield — the largest explosion the United States ever set off.
The result was the worst radiological accident in US testing history. The fireball swallowed the reef and dug a crater 2 km across; fallout the consistency of snow fell on the inhabited atolls of Rongelap and Utirik and on the Japanese fishing boat Daigo Fukuryū Maru, whose crew suffered acute radiation sickness and one of whom died. The incident made fallout a household word and gave the push for the test-ban movement.
The rings here are for an airburst of 15 megatons: total destruction to about 5.4 km, collapsed houses to roughly 11 km, third-degree burns to about 34 km, broken windows to about 29 km. Compare with the Soviet answer, the 50-megaton Tsar Bomba, or read about the atmospheric testing era.
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