Page:Operation Crossroads 1946.pdf/22



CHAPTER 1

OVERVIEW

INTRODUCTION

After the atomic bomb attacks on Japan had abruptly ended World War II, many military leaders felt that military science was at a crossroads. The officer who commanded the first postwar nuclear test series commented that "warfare, perhaps civilization itself, had been brought to a turning point by this revolutionary weapon" (Reference C.12.1, Cap. Plate XI). With this in mind, he therefore had the nuclear test operation designated CROSSROADS. Operation CROSSROADS was at that time the largest U.S. peacetime military operation ever conducted. It involved 42,000 personnel, 251 ships, and 156 aircraft.

This series consisted of two detonations at Bikini Atoll in the Marshall Islands during the summer of 1946. These were:


 * ABLE (1 July 1946, 0900) -- an airdrop detonated at an altitude of 520 feet (158 meters)


 * BAKER (25 July 1946, 0835) -- an underwater shot 90 feet (27 meters) below the surface

An additional deep underwater detonation, Test CHARLIE, was planned but was not conducted.

This report documents the participation of War and Navy Department personnel who were active in the test series. Its purpose is to bring together available information about the atmospheric nuclear test series pertinent to the exposure of both uniformed and civilian personnel to radiation. The report lists the organization represented and describes their activities. It discusses the potential radiation exposure of personnel. Finally, it presents the exposures of participating personnel recorded by film badges and scientifically based estimates of radiation doses for participating units.

The weapons used used in the CROSSROADS tests were of the same design as the one that had been dropped on Nagasaki, Japan. Each had a yield of 23 KT (the equivalent of 23,000 tons of TNT). This weapon type had been developed by the U.S. Army's Manhattan Engineer District during the war, primarily at the District's laboratory at Los Alamos, New Mexico, with research support from laboratories at the University of Chicago and Oak Ridge, Tennessee, and material production from Hanford, Washington. Under the terms of the Atomic Energy Act of 1946, the Manhattan Engineer District was dissolved at the end

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