Defense Threat Reduction Agency Defense Threat Reduction Information Analysis Center 1680 Texas Street SE Kirtland AFB, NM 87117-5669 DTRIAC SR-12-001 CASTLE BRAVO: FIFTY YEARS OF LEGEND AND LORE A Guide to Off-Site Radiation Exposures January 2013 Distribution A: Approved for public release; distribution is unlimited. Trade Names Statement: The use of trade names in this document does not constitute an official endorsement or approval of the use of such commercial hardware or software. This document may not be cited for purposes of advertisement. REPORT Authored by: Thomas Kunkle Los Alamos National Laboratory, Los Alamos, New Mexico and Byron Ristvet Defense Threat Reduction Agency, Albuquerque, New Mexico SPECIAL Form Approved OMB No. 0704-0188 REPORT DOCUMENTATION PAGE Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From-To) 31 January 2013 Special Report 1954 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Castle Bravo: Fifty Years of Legend and Lore DTRA-02-03-D-0002 A Guide to Off-Site Radiation Exposures 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR (S) 5d. PROJECT NUMBER Thomas Kunkle Los Alamos National Laboratory 5e. TASK NUMBER Byron Ristvet Defense Threat Reduction Agency, J9CXT 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER Defense Threat Reduction Agency DTRIAC SR-12-001 Defense Threat Reduction Information Analysis Center LA-UR-04-1400 1680 Texas St. SE, Building 20676 Kirtland AFB, NM 87117-5669 9. SPONSORING/MONITORING AGENCY NAME(S) AND 10. SPONSOR/MONITOR’S ACRONYM(S) ADDRESS(ES) Defense Threat Reduction Agency 11. SPONSOR/MONITOR’S REPORT No. 8725 John J. Kingman Road Fort Belvoir, VA 22060-6201 12. DISTRIBUTION/AVAILABILITY STATEMENT Distribution A: Approved for public release; distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT This report is a narrative history and guide to primary historical references concerning the CASTLE BRAVO nuclear test of 1 March 1954. Detonated at Bikini Atoll in the Marshall Islands, BRAVO was the largest-yield American nuclear explosion. Also, it was the only American nuclear test to result in prompt harm to civilian populations. Radioactive fallout arrived within hours on several nearby populated islands, necessitating emergency evacuations of Rongerik, Rongelap, and Utirik atolls, and resulting in radiation overexposures to approximately 665 island residents. This report focuses on the circumstances that resulted in radioactive contamination of the inhabited atolls. No attempt is made to address, in any detail, the larger issue of the effects of BRAVO on and around the shot site at Bikini Atoll. 15. SUBJECT TERMS CASTLE BRAVO, SR-12-001, legend, lore, nuclear test, radioactive fallout, radiation exposure, contamination, evacuation, Bikini Atoll, Eniwetok, Enewetak, Rongerik, Rongelap, Utirik, Marshall Islands, House Committee Hearing, Joint Task Force, Pacific Proving Ground, weather, winds, sampling 16. SECURITY CLASSIFICATION OF: 17. LIMITATION 18. NUMBER 19a. NAME OF OF ABSTRACT OF PAGES RESPONSIBLE PERSON: Byron Ristvet SAR 195 a. REPORT b. ABSTRACT c. THIS PAGE 19b. TELEPHONE NUMBER (include area code) UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED 505-846-8680 Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18 January 2013 CASTLE BRAVO: Fifty Years of Legend and Lore DTRIAC SR-12-001 LA-UR-04-1400 CASTLE BRAVO: Fifty Years of Legend and Lore A Guide to Off-Site Radiation Exposures DTRIAC item 22-C-93 Figure 0–1. Utirik Island village seen from a raft bringing radiation safety monitors to shore, 3 March 1954 By Thomas Kunkle Los Alamos National Laboratory, Los Alamos, New Mexico and Byron Ristvet Defense Threat Reduction Agency, Albuquerque, New Mexico CASTLE BRAVO: Fifty Years of Legend and Lore iii January 2013 CASTLE BRAVO: Fifty Years of Legend and Lore Table of Contents REPORT DOCUMENTATION PAGE ............................................................................. ii CASTLE BRAVO: Fifty Years of Legend and Lore .................................................... iii Acknowledgments......................................................................................................... x 1.0 Introduction ......................................................................................................... 1 1.1 The Marshall Islands and the Pacific Proving Ground ............................. 4 2.0 Weather ............................................................................................................. 36 2.1 Winds and Fallout .................................................................................. 38 2.2 The Pate-Palmer Report ........................................................................ 42 3.0 Fallout Predictions ........................................................................................... 48 3.1 The BRAVO Fallout Pattern ................................................................... 58 3.2 Lower Level Wind Effects ...................................................................... 69 3.3 A Shift of the Winds ............................................................................... 76 3.4 Yield Effects ........................................................................................... 77 3.5 Testing Techniques ............................................................................... 80 3.6 Device Considerations ........................................................................... 86 3.7 The Danger Area ................................................................................... 87 4.0 Radioactive Contamination ............................................................................. 89 4.1 Airborne Radiological Surveys ............................................................... 90 4.2 The HASL Fixed Instrument Network .................................................... 93 4.3 Soil and Water Sampling ....................................................................... 93 4.4 Summary of Radiation Exposures ......................................................... 96 4.5 Radioactive Contamination from Operation IVY .................................... 99 4.6 The Nationwide Radiological Study ..................................................... 100 4.7 Comments on the Operation CASTLE Radiation Exposure Records .. 102 5.0 Evacuation of the Off-Site Atolls ................................................................... 105 5.1 Rongerik .............................................................................................. 112 5.2 Rongelap ............................................................................................. 114 5.3 Utirik .................................................................................................... 121 5.4 Ailuk ..................................................................................................... 126 5.5 The Fortunate Dragon ......................................................................... 127 5.6 The Project 4.1 Medical Research Studies .......................................... 130 5.7 Evacuation Planning ............................................................................ 135 5.8 Record Keeping ................................................................................... 136 6.0 The House Committee Hearing ..................................................................... 141 6.1 Comments on the Statement by Mr. Merril Eisenbud .......................... 142 6.2 Comments on the Statement by Mr. Jonathan Weisgall ...................... 145 6.3 Comments on the Statement by Mr. David M. Weiman ....................... 148 Table of Contents v January 2013 CASTLE BRAVO: Fifty Years of Legend and Lore 6.4 Comments on the Statements by Dr. Steve Simon and Dr. Thomas Hamilton ........................................................................... 149 6.5 The Lulejian Report ............................................................................. 157 Appendix A Units and Measures ........................................................................... 159 Appendix B Acronyms and Conversions ............................................................. 160 List of Acronyms ............................................................................................... 160 Conversion Table ............................................................................................. 162 References ................................................................................................................. 164 Distribution List ........................................................................................................