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.
Daigo Fukuryū Maru
The "Daigo Fukuryū Maru" encountered the fallout from the U.S. Castle Bravo nuclear test at Bikini Atoll, near the Marshall Islands, on March 1, 1954. When the test was held, the "Daigo Fukuryū Maru" was catching fish outside the danger zone that the U.S. government had declared in advance. However, the test was more than twice as powerful as predicted, and changes in weather patterns blew nuclear fallout, in the form of a fine ash, outside the danger zone. On that day, the sky in the west lit up like a sunset. Seven minutes later, the sound of the explosion arrived, with fallout reaching the ship two hours later. The fishermen attempted to escape from the area, but they took time to retrieve fishing gear from the sea, exposing themselves to radioactive fallout for several hours.