"The second series of tests in 1954 was codenamed
Operation Castle. The first detonation was
Castle Bravo, which tested a new design utilizing a dry-fuel
thermonuclear bomb. It was detonated at dawn on March 1, 1954. Scientists miscalculated: the 15
Mt of TNT nuclear explosion far exceeded the expected yield of 4–8 Mt of TNT (6 predicted).
[5] This was about 1,000 times more powerful than either of the atomic bombs dropped on
Hiroshima and Nagasaki during World War II."