Castle Series, 1954

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CASTLE SERIES, 1954 Technical Report 7. AUTHOR(.) 8- CONTRACT OR GRANT NUMBER(.: PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK9. AREA WORK UNIT NUMBERS P. 0. Drawer QQ (816 State Street) Santa Barbara, California 93102 II. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Defense Nuclear Agency 13. NUMBERCF PAGES Approved for public release; distribution unlimited. 17, DISTRIBUTION STATEMENT (of Ih. ab.U.cl nmnd In Block 20, Ifd l fl eml 1- Repolt) This work sponsored by the Defense Nuclear Agency under RDT&E RMSS Code Nuclear Testing Enewetak, Bikini Nuclear Test Personnel Reviaw (NTPR) CASTLE, BRAVO, ROMEO, KOON, UNION, YANKEE, NECTAR For sale by the National Technical Pacific Proving Ground CASTLE was an atmospheric nuclear weapons test series held in the Marshall Islands at Enewetak and Bikini atolls in 1954. personnel i n CASTLE with an emphasis on operations and radiological safety. This is a report of DOD SECURITY CLASSIFICATIOW OF TMIS PAGE (hC m l . Entered) I

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CASTLE was a six-detonation nuclear weapon test series (see table) held at the Atomic Energy COmdSSiOn'S (AEC) Pacific Proving Ground (PPG) atolls in the northwestern Marshall Islands in the Central Pacific Ocean. The PPG consisted principally of Enewetak* and Bikini Date Nme Location Magnitude 27 March ROMEO Bikini ; barge in BRAVO crater 11 MT 7April KOON Bikini ; surface of Eneman Island 110 KT 26 April UNION Bikini ; barge i n lagoon of fI roi j Island 6.9 MT 5 May YANKEE Bikini ; barge in UNION crater 13.5 MT 14 May NECTAR Enewetak; barge i n MIKEb crater 1.69 MT aOne kiloton equals the approximate energy release of the explosion of one thousand tons of TNT; one megaton equals the approximate energy release of the explosion of one million tons of TNT. 10.4-MT IVY series detonation in 1952. The CASTLE series was held to test large-yield thermonuclear, or hyGREENHOUSE, GEORGE experimental shot in 1951 and the IVY, M I K E shot of 1952. MIKE was the first device that generated a substantial explosive energy from the fusion, or joining, of hydrogen atoms. These explosive Work on this class of devices had progressed through the The spelling of Marshall Island place names has changed in recent years in order to more accurately render the sounds of the Marshall Island names using English spelling.

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devices were developed by the AEC, the civiiian agency authorized to perform this activity by the Atomic Energy Act of 1946. The devices were tested at the PPG by a joint military and civilian organization, designated as Joint Task Force 7 (JTF 7 ) . This was a military organization in form, but was populated by military, civil service, and contractor personnel of the Department of Defense (DOD) and AEC. The commander of this force was the appointed representative of the AEC and reported also to the Joint Chiefs of Staff (JCS) and the Commander in Chief, Pacific (CINCPAC). The peak W D numerical strength at CASTLE was approximately as follows: Numerous technical experiments were carried out in conjunction with each of the six detonations. These experiments measured the power and efficiency of the devices and attempted to gauge the military effects of individuals whose duty stations were at the AEC design laboratories, as units performing separate experiments, and as units performing various port group at Bikini, where its ships provided living space for personnel who were evacuated from the islands for the first test and then could not return to live there because of the potential radiation exposure. DOD personnel participated in this test operation as The CASTLE operations placed almost all of the Navy s u p An extensive radiological safety program was instituted whose objec1. Maintenance of personnel radiation exposure at the lowest possible level consistent with medical knowledge of radiation effects and the importance Of the 2 . Avoidance of inadvertent contamination of populated islands OK transient shipping.

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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 provided to a large portion of the participating personnel. 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. sonnel was monitored. The amount of radiation exposure for these perTEST 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 contamination and exposure of s m e individuals either stationed or residing on distant atolls or aboard various vessels. Acute radiation effects were observed among some of these people. A limited number of JTF 7 personnel received radiation exposures conThis opera-siderably in excess of the initially established CASTLE MPE. tional 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 had film badge exposures that read as sequently, follow-up on 29 of them was done at Tripler Hospital in Hawaii. All these men were medically evaluated at Rwajalein.

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The results of these medical observations were reported as "essentially BRAVO fallout on some Navy ships a150 resulted in additional personnel who had exposures approaching or exceeding the CASTLE MPE of 3.9 R. allow for operational completion of the remaining CASTLE shots, it became necessary to issue a number of waiver authorizations permitting exposures of as much as 7.8 R. In a limited number of cases, even this level was As a result of BRAVO, 21 individuals on the USS Philip (DDE-498) and 16 on the USS Bairoko (CVE-115) sustained small skin lesions resembling burns that were definitely classified as beta burns. nel received radiological contamination while on the weather deck 3r stationed near ventilation blowers. These all healed without complications. The USS Patapsco (AOG-l), a Navy gasoline tanker, which was approximately 180-195 nautical miles (333-360 kilometers) northeast of BRAVO'S ground zero at the time of detonation, received fallout as it returned to Pearl individual was on deck 24 hours a day with the ship retaining 100 percent of all fallout radioactivity and using the highest reading from radiation surveys, For an individual who spent only 8 hours a day on deck and 16 hours a day inside, and assuming that the storm conditions washed off 50 percent of the activity en route, the estimated dose is 3.3 R. Exposure estimates as high as 18 R are possible, assuming an The other five CASTLE detonations, though extremely important as weapon tests, did not produce significant, unexpected personnel radiation While small numbers of personnel at CASTLE did receive exposures in excess of imposed standards, by far the largest portion did not. In fact, the radiation exposure for JTF 7 personnel at CASTLE averaged about The recorded CASTLE exposures are summarized in the table on the i

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No. of High Persons Dose Zeroa 0.001- 1.001- 3.001- 5.001- Over Recorded Service Badged Unavail Exposure 1.000 3.000 5.000 10.00 10.0 ( R ) 'Zero doses were not recorded in the Consolidated List of CASTLE Radiological Exposures for many units. bPercent o f total service personnel i n each group. 'Three unbadged Army personnel on Rongerik Island originally were assigned a dose of dThe high value comes from badges worn by Air Force personnel on Rongerik. The U . S . 98 R , which was taken from a badge mounted on a tent pole. Air Force has assigned an estimated total dose o f 86 R to each member of its Rongerik