On March 1 , 1954 , the largest-ever U.S. nuclear test explosion , the 15-megaton Bravo shot of Operation Castle at Bikini Atoll , delivered a promptly lethal dose of fission-product fallout to more than of Pacific Ocean surface . Radiation injuries to Marshall Islanders and Japanese fishermen made that fact public and revealed the role of fission in hydrogen bombs
Bravo
Castle Bravo
Nuclear weapon design