This Day in History: Hydrogen bomb, Bravo, detonated on Bikini Atoll.

03-01-2013 • Andrew Petcher

In 1954 the United States began serious nuclear testing in the Pacific Ocean on the island of Bikini Atoll and they carried out the detonation of a massive bomb codenamed Castle Bravo. This was the first test of a practical hydrogen bomb and the largest nuclear explosion ever set off by the United States. In fact, a bit like a ten year old with a box of fireworks and some matches, they really had little idea what they were doing and when it was detonated it proved much more powerful than the boffins had predicted, and created unexpected widespread radioactive contamination which has prevented people from ever returning to the island.

Castle Bravo was the most powerful nuclear device ever detonated by the United States, with a yield of fifteen Megatons. That yield, far exceeding the expected yield of four to six megatons which, combined with other factors, led to the most significant accidental radiological contamination ever caused by the United States. In terms of TNT tonnage equivalence, Castle Bravo was about one thousand, two hundred times more powerful than each of the atomic bombs which were dropped on Hiroshima and Nagasaki during World War II.