Castle Bravo
Castle Bravo was the first in a series of high-yield thermonuclear weapon design tests conducted by the United States at Bikini Atoll, Marshall Islands, as part of "Operation Castle". Detonated on March 1, 1954, the device was the most powerful nuclear device detonated by the United States and its first lithium deuteride fueled thermonuclear weapon. Castle Bravo's yield was 15 megatons of TNT, 2.5 times the predicted 6.0 megatons, due to unforeseen additional reactions involving Li, which led to the unexpected radioactive contamination of areas to the east of Bikini Atoll.
Castle Bravo
The detonation took place at 06:45 on March 1, 1954, local time (18:45 on February 28 GMT).
When Bravo was detonated, within one second it formed a fireball almost across. This fireball was visible on Kwajalein atoll over away. The explosion left a crater in diameter and in depth. The mushroom cloud reached a height of and a diameter of in about a minute, a height of and in diameter in less than 10 minutes and was expanding at more than . As a result of the blast, the cloud contaminated more than of the surrounding Pacific Ocean, including some of the surrounding small islands like Rongerik, Rongelap, and Utirik.