Page:Operation Crossroads 1946.pdf/65

 RADIOLOGICAL SAFETY PREPARATIONS FOR BAKER

Because BAKER was the first underwater detonation of a nuclear weapon, neither the participating scientists nor the task force leadership could predict with certainty how the lagoon water would react to and modify the explosion cloud. Spread of radioactive contamination and creation of damaging waves were major concerns. Simulation using conventional explosive charges was one approach to estimate the effects. In one effort to predict the spread of radioactivity, 1,000-lb charges of TNT were detonated and the results extrapolated upward to the expected 20-KT yield of the BAKER device (Reference B.0.15, pp. 13 through 16).

During the period March to May 1946, several organizations under the supervision of a professor from the University of California carried out experiments for the task force on wave action in shallow water (Reference C.0.18; Reference C.0.12.3, p. 6). In 1946, computer simulations were still in the future, but various scientists applied their slide rules and scientific imagination to the forecasting problem. One study analyzed the possibilities largely on the basis of the height to which the column of contaminated water might rise. A rise of only 10,000 feet (3.1 km) would present the greatest hazard because most of the contamination would fall on the target ships or back into the lagoon. Rebounding some target ships within 1,000 yards (9.1 meters) of the detonation might be dangerous for weeks because of the contamination deposited from the water column (Reference C.0.19, pp. 5 and 9).

In an early overview of the operation, CJTF 1 offered the opinion that following BAKER (Reference B.0.16, p. 7):


 * It will be undoubtedly be some weeks before the lagoon and target ships are again habitable. During this period, some of the task force ships may be sent to anchor at Kwajalein. If it should turn out that the target ships will not be habitable for months, other arrangements will be made.

On 18 June, an appendix was added to the Operation Plan that gave a description of the underwater detonation's expected effects (Reference B.0.1, pp. E-X-1 through E-X-17 and E-IX-1 through E-IX-4). The ball of fire or steam caused by the detonation was predicted to rise to an altitude of from 10,000 to 60,000 feet (3.1 to 18.2 km). The most likely altitude was predicted to be 30,000 feet (9.1 km) (Reference B.0.1, p. E-IX-1, Change No. 6). However, a postoperation document indicates that planning was based on a prediction of maximum altitude of 15,000 feet (4.6 km) (Reference C.9.206, p. VII-(C)-18).

The appendix further predicted that a plume of water might rise, extend for several thousand feet above the surface, and then fall back into the lagoon. Radioactive material would be deposited initially in the lagoon within boundaries represented by a cylinder several hundred yards in diameter and extending from the surface to the bottom of the lagoon. The trail of water and steam following the ball of fire would be heavily contaminated. Distribution of radioactivity in the water was anticipated to be more widespread than following ABLE and would persist for a longer period. Target ships within 1,500 yards (1.4 km) of the explosion would be seriously contaminated. Downwind serious contamination would occur beyond 1,500 yards (1.4 km). It was expected that

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