On March 1, 1954, the United States detonated a thermonuclear device at Bikini Atoll during Operation Castle. Scientists made a catastrophic miscalculation in the lithium-7 reaction, causing the blast to be 15 megatons, three times more powerful than expected. The explosion vaporized entire islands and sent a plume of radioactive debris into the atmosphere. About 80 miles away, the Japanese fishing boat Daigo Fukuryū Maru, or Lucky Dragon No. 5, was caught in the path of the fallout. The 23 crew