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.
Human radiation experiments
In the Marshall Island, indigenous residents and crewmembers of the fishing boat "Lucky Dragon No. 5" were exposed to the high yields of radioactive testing during the Castle Bravo explosions conducted at Bikini Atoll. Researchers subsequently exploited this ostensibly "unexpected" turn of events by conducting research on the onset of effects from radiation poisoning as part of Project 4.1, raising ethical questions as to both the specific incident and the broader phenomenon of testing in populated areas.