SECTION 2
BACKGROUND AND AVAILABLE DATA
2.1

BACKGROUND
Shot Bravo was detonated on Bikini Atoll at 0645 hours (local time) on | 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 move inside 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 1800 hours
(Reference 3).

Select target paragraph3