Operation Castle
1954
Fact Sheet
Public Affairs Office
Washington, D. C. 20305
1 September 1981
2. Avoidance of inadvertent contamination of populated islands or transient shipping. The program established an organization to provide radiological safety (radsafe) expertise and services to the separate components of the task force who were responsible for personnel safety within their commands. Personnel were trained in radiological safety and standards governing maximum permissible exposures (MPE) were established. Film badges were provided to a large portion of the participating personnel. Persons likely to be exposed to radiation were badged as well as a representative group of the remainder. An extensive weather forecasting group was established in order to predict wind directions and areas of potential fallout. Personnel were evacuated from danger areas before each detonation and reentry to contaminated areas was restricted to the personnel required to retrieve important data. The amount of radiation exposure for these personnel was monitored.
TEST OPERATIONS AND EXPOSURES
The first event of this series, designated BRAVO, had a yield of 15 MT and was the largest device ever detonated in atmospheric nuclear testing by the U.S. Government. Significantly exceeding its expected yield, BRAVO, detonated at Bikini Atoll, released large quantities of radioactive materials into the atmosphere, which were caught up in winds that spread the particles over a much larger area than anticipated. This resulted in the widely publicized contamination of the Japanese Fishing Boat, Daigo Fukuryu Maru (Fortunate Dragon No. 5, as well as groups of Marshall Islanders. Acute radiation effects were observed among these people.
A limited number of JTF 7 personnel received radiation exposures considerably in excess of the initially established CASTLE MPE. This operational limit was established at 3.9 roentgens (R) gamma within any 13-week period of the operation. In particular, three members of the U.S. Navy Bikini Boat Pool had heavily exposed badges with readings from 85 to 95 R and 28 Army and Air Force personnel were assigned exposures based on film badges worn by four of these individuals that read as high as 78 R. A group of 29 of these individuals was later evacuated to Tripler Hospital in Hawaii for medical observation. The results of these medical observations were reported as "essentially negative negative" or "generally negative."
Fact Sheet continued page 4
Operation Castle