SECTION 2 BACKGROUNDAND AVAILABLE DATA 2.1 BACKGROUND C Shot Bravo: was detonated on Bikini Atoll at 0645 hours (local time) on 1 March 1954. The ‘total yield of the thermonuclear explosion was approximately 15-megatons TNT equivalent. The nuclear device was mounted on a barge in shallow water, about seven feet above the surface of a coral reef. The radioactive fallout from Shot Bravo contaminated an area extending from about 20 statute miles upwind to over 330 miles downwind and varying in width to over 60 miles. Included within the area of major contamination were Bikini Atoll and three downwind atolls: Ailinginae Atoll, Rongelap Atoll, and Rongerik Atoll (References 1, 2). Among these atolls, Marshallese were present on Ailinginae and Rongelap, and American servicemen only on Rongerik. Twenty-eight servicemen (25 Air Force personnel and 3 Army personnel) operated a weather station on Rongerik Atoll, about 150 miles east of Bikini. At approximately 1407 hours (almost 7% hours after the Bravo detonation) the deposition of fallout on Rongerik was detected by a low-level gamma radiation monitoring instrument and subsequently observed visually. At 1500 hours, a message was sent to Joint Task Force (JTF) Headquarters on Enewetak Atoll (Reference 3) notifying them of the fallout on Rongerik. Approxi- mately one-half hour later, a reply came back from Enewetak instructing the military personnel on Rongerik to put on long-sleeved shirts, trousers, hats, and GI shoes, and to remain inside as much as possible, consistent with their normal work routine. At about 2330 hours, another message was received directing all personnel to cease operations and moveinside permanent buildings. At 1245 hours on 2 March 1954, eight men, the first eight on the alphabetical detachment roster, were evacuated from Rongerik to Kwajalein Atoll by airplane; the remaining twenty men were evacuated by airplane at approximately (Reference 3). 1800 hours