Analysis of Radiation Exposure for Naval Personnel at Operation Castle

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ANALYSIS OF RADIATION EXPOSURE FOR NAVAL PERSONNEL AT OPERATION CASTLE Science Applications International Corporation CONTRACT No. ONA O01=83=COO039 distribution is unlhnitod. DEFENSE NUCLEAR AGENCY

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Destroythis report when it is no longerneeded, Donot return PLEASE NOTIFY THE DEFENSE NUCLEAR AGENCY, ADDRESS IS INCORRECT,IF YOU WISH IT DELETED IS NO LONGEREMPLOYEDBYYOURORGANIZATION.

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Ia, REPORT SECURITY CLASSIFICATION I lb. RESTRICTIVE MARKINGS 2a SECURITY CWSSIFICATION AuTHORl~ I 3 DISTRIBUTION /AVAlLA61Ll TY OF REPORT X/A since i:nclassified Approved for public release; 2b.DECLASSIFICATION IDOWNGWOING SCHEDULE distribution is unlimited. 4 PERFORMING ORGANIZATION REPORT NUM6ER($) 5. MONITORING ORGANIZATION REpORTNUMSER($) SCIENCE APPLICATIONS (/f4pp/icable) Director INTEFLVATIONAL CORPORATION Defense Nuclear Agency M. NAMEOFFUNDING/SPONSORING 8b. OFFICE SYMBOL 9. PROCUREMEIUT INSTRUMENT IDENTIFICATION NUMBER PROGRAM PROJECT TASK NO. NO. ACCESSION NO. ANALYSIS OF RADIATION EXPOSURE FOR NAVAL PERSONNEL AT OPERATION CASTLE Technical Report FROM 830101 T0840131 This work was sponsored by the Defense Nuclear Agency under RDT&E RMSS Code FIELD I GROUP I SUE-GROUP Operation CASTLE 6 18 Radiation Exposure Assessment 6 21 I Nuclear Test Personnel Review (NTPR) Film badge doses are reconstructed for sixteen ships and the residence islands of Enewetak and Kwajalein ‘Atolls resulting-from the six nuclear detonations comprising %eration CASTLE (Harcil-May 1954). Fallout from Shots BRAVO and ROMEO was the major source of contamination on most of the ships and islands. Varying amounts of fallout from Shots UNION, YANKEE, and P?ECTAR contributed somewhat to the total doses @f the shipboard and island-based personnel; no fallout was experienced as a result of Shot “KOON. Shipboard personnel received additional exposure from hulls and salt water piping systems that had become contaminated from operating in the radioactive waters of Bikini Lagoon. From the reconstructed radiation environments, both topside and below, an equivalent film badge dose is calculated and compared to actual dosimetry data. Agreement. is very good during badged periods when the ships received significant fallout. When topside intensities! )0F0RM1473,84 MAR 83 APR edt!on may be used unt!l lnhaustod. s RIW All othor edttlons W. obsoloto.

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Joint Task Force Seven Oceanic Nuclear Tests were not documented, generally late in the oPeration ‘hen intensity levels were low, agreement is not as good. Calculated ship contamination doses of significance are in excellent agreement with limited available dosimetry data. ca~cu~ated average doses for shipboard personnel ‘~~t~~O~r~wl~~{eO~~~~~L~~~ the crew of the USS LST-825 to a high of 3.56 rem Average doses on the residence islands of Enewetak and Kwajalein Atolls are 1.09 rem and 0.32 rem, respectively. CURITYCLASSIFICATIONOF THIS PAGE

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LIST OF ILLUSTRATIONS LIST OF TABLES SHIP OPERATIONS AND RADIATION ENVIRONMENTS Uss BELLE GROVE (LSD-2)

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TABLE OF CONTENTS (Concluded) 3.2 CALCULATED PERSONNEL FILM BADGE DOSES Enewetak Atoll Dose Calculations Kwajalein Atoll Dose Calculations USS APACHE Dose Calculations USS t3AIROK0 Dose Calculations USS BELLE GROVE Dose Calculations USS CURTISS Dose Calculations USS ESTES Dose Calculations USNS FRED C. AINSWORTH Dose Ca USS GYPSY Dose Calculations USS LST-551 Dose Calculations USS LST-762 Dose Calculations USS LST-825 Dose Calculations USS 1ST-975 Dose Calculations USS NICHOLAS Dose Calculations USS PHILIP Dose Calculations USS RENSHAW Dose Calculations USS SIOUX Dose Calculations 5 FILM BADGE DOSIMETRY 6 CONCLUS1ONS AND TOTAL DOSE SUMMARY 7 LIST OF. REFERENCES .

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Northern Marshall Islands Bikini Atoll, Operation CASTLE shot locations Enewetak Atoll, Operation CASTLE shot location Operation CASTLE dose reconstruction methodology Locations of various TG 7.3 ships at the time of Shot BRAVO Average intensity below deck on the USS CURTISS due to ship Parry and Enewetak Island intensity following Shot Parry and Enewetak Island intensity following Shot Parry and Enewetak Island intensity following Shot Kwajalein Atoll intensity following Shot BRAVO Kwajalein Atoll intensity following Shot ROMEO Kwajalein Atoll intensity following Shot YANKEE USS APACHE topside intensity following Shot BRAVO USS APACHE topside intensity following Shot ROMEO USS 13AIROK0 topside intensity following Shot BRAVO USS BAIROKO topside intensity following Shot ROMEO USS BELLE GROVE topside intensity following Shot BRAVO USS BELLE GROVE topside intensity following Shot ROMEO USS CURTISS topside intensity foilowing Shot 13RAV0 USS EPPERSON topside intensity following Shot ROMEO USS ESTES topside intensity following Shot BRAVO USS ESTES topside intensity following Shot ROMEO

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USNS FRED C. AINSWORTH topside intensity following Shot BRAVO USNS FRED C. AINSWORTH topside intensity following Shot ROMEO USS GYPSY topside intensity following Shot BRAVO USS LST-551 topside intensity following Shot ROMEO USS LST-762 topside intensity following Shot YANKEE USS LST-975 topside intensity following Shot YANKEE USS NICHOLAS topside intensity following Shot ROMEO USS NICHOLAS topside intensity following Shot UNION USS PHILIP topside intensity following Shot BRAVO USS PHILIP topside intensity following Shot ROMEO USS RENSHAW topside intensity following Shot ROMEO USS S1OUX topside intensity following Shot BRAVO USS S1OUX topside intensity following Shot ROMEO Sea water intensity measured from the USS S1OUX following Shot YANKEE Crew activity time-line for the USS APACHE, 1-2 March 1954 Results of radiological surveys onboard the YAG-40 following Shot ROMEO and Shot YANKEE USS ESTES-Comparison of dosimetry data with calculated doses USS PHILIP-Comparison of dosimetry data with calculated doses USS SIOUX-Comparison of dosimetry data with calculated doses “

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LIST OF TABLES Operation CASTLE shot data Atolls and ships for which dose reconstructions Daily integrated intensity, residence islands of Enewetak Atoll Daily integrated intensity, Kwajalein Atoll Daily integrated intensity, USS APACHE Daily integrated intensity, USS BAIROKO Daily integrated intensity, USS BELLE GROVE Daily integrated intensity, USS CURTISS Daily integrated intensity, USS EPPERSON Daily integrated intensity, USS ESTES Daily integrated intensity, USNS FRED C. AINSWORTH Daily integrated intensity, USS GYPSY Daily integrated intensity, USS LST-551 Daily integrated intensity, USS LST-762 Daily integrated intensity, USS LST-825 Daily integrated intensity, USS LST-975. Daily integrated intensity, USS NICHOLAS Daily integrated intensity, USS! PHILIP Daily integrated intensity, USS RENSHAW Daily integrated intensity, USS SIOUX

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LIST OF TABLES (Concluded) of Enewetak Atoll film badge dose, residence islands film badge dose, Kwajalein Atoll film badge dose, USS APACHE film badge dose, USS BAIROKO Calculated personne) film badge dose, USS BELLE GROVE Calculated personnel film badge dose, USS CURTISS Calculated personnel film badge dose, USS EPPERSON Calculated personnel film badge dose, USS ESTES Calculated personnel film badge dose, USNS FRED C. AINSWORTH Calculated personnel film badge dose, USS GYPSY Calculated personnel film badge dose, USS LST-551 Calculated personnel film badge dose, Calculated personnel film badge dose, Calculated personnel film badge dose, Calculated personnel film badge dose, Calculated personnel fil?n badge dose, Calculated personnel film badge dose, Calculated personnel film badge dose, Summary of calculated mean doses

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Operation CASTLE was a series of atmospheric nuclear tests conducted by the Atomic Energy Commission (AEC) at the Pacific Proving Grounds (PPG) during the Spring of 1954. Radiological safety procedures included the issuance of film badges to approximately 10 percent of the personnel throughout the operation and to individuals during periods of potentially significant radiation exposure. Cohort badging, i.e., one badge worn by one individual in a group, was the primary means of determining individual exposures. Recorded dosimetry data and medical record data for personnel aboard most of the ships involved in the operation are sufficient to accurately determine their radiation exposure. There were, however , sixteen ships involved (either directly or indirectly) for which available dosimetry data are insufficient to assess the’ exposures of crew members assigned to them. Consequently, where film badge coverage is incomplete, it is necessary to reconstruct the radiation dose. This report describes the operation, the radiological situation, and the time-space relationships of each ship with respect to the radiological environment. The results are “portrayed as equivalent fiim badge doses for the crews of each of the 16 vessels of Because some personnel of the naval contingent were assigned to the residence islands of Enewetak and Kwajalein Atolls, the radiation environments on both atolls are also reconstructed. Plans had also called for the use of the residence islands of Bikini Atoll (Eneman and Eneu Islands), but heavy contamination following the first shot (BRAVO) required a conversion from land-based to ship-based operations. Personnel could go ashore on Bikini only for short periods of time and then, only when accompanied by a trained rad-safe monitor (Reference 1). Film badges were generallY issued to personnel going ashore and exposures are documented. Because of this, the reconstruction of the Bikini radiation environments are not addressed in this report. There were six shots in the CASTLE test series: BRAVO, ROMEO, KOON, UNION, YANKEE, and NECTAR. The first five were detonated on Bikini Atoll and

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Shot NECTAR was detonated on Enewetak. Figure 1-1 depicts the locations of Bikini and Enewetak with respect to the other atolls comprising the northern Marshall Islands. Figures 1-2 and 1-3 show the main features of Bikini and Enewetak, respectively, and the locations of the CASTLE detonations. The pertinent details of each test are summarized in Table 1-1 (Reference 2). Table 1-1. Operation CASTLE shot data. Shot Name Local Date (time) Yield Location BRAVO 1 Mar 54 (0645) 15 Mt Bikini ROMEO 27 Mar 54 (0630) llMt Bikini KOON 7 Apr 54 (0620) 110 Kt Bikini UNION 26 Apr 54 (0605) 6.9 Mt Bikini YANKEE 5 May 54 (0610) 13.5 Mt Bikini NECTAR 14 May 54 (0620) 1.69 Mt IVY MIKE Crater, The devices were tested by a joint military and civilian, organization designated as Joint Task Force Seven (J TF-7). Although military in form, it was comprised of military, civil service, and contractor personnel. 3TF-7 was organized into five main task groups with Task Group 7.3 being the naval contingent. Most of the approximately 6000 personnel assigned to TG 7.3 were aboard the various task group ships; however, approximately 650 were stationed on Enewetak and Kwajalein Atolls. Table I -2 is a summary of the atolls and ships for which dose reconstructions are specifically addressed in this report. AISO tabulated are the approximate number of personnel assigned to each. The procedures developed in previous dose reconstruction efforts have been adapted to the shipboard radiological environments of Operation CASTLE (References

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Table 1-2. Atolls and ships for which dose reconstructions are applicable. Enewetak Atoll (Enewetak, Parry, and Japtan Islands) 241 uss BELLE GROVE (LSD-2)

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3, 4, 5 and 6). Figure 1-4 depicts the steps taken in calculating personnel film badge doses. These steps are pursued to a level of detail governed by the availability of data. Sufficient data were recorded at the time and enough have survived to understand the ship and land operations and to characterize the radiation environment. Individual ship deck logs serve as an authoritative source of ship position and activity. Radiation intensity data and crew activity scenarios are applied to reconstruct the time-dependent radiation environment for an average crewman on each of the sixteen ships of interest. Characterization of the radiation environment starts with the determination of on-deck intensities from radiological survey data. The periodic shipboard surveys, in conjunction with fallout time-of-arrival data and nearby island surveys, serve to define the topside intensity as a function of time. At times following the last reported shipboard survey, a power law function determined from Bikini Atoll radiological data is utilized. Despite significant differences in decay rate between ship and shore because of early-time washdown, decontamination, and weathering, late-time decay, mostly from insoluble particles adhering to shipdeck or soil, is taken to be the same. As ships operated in the contaminated waters of Bikini Lagoon, their hulls and salt water piping systems accumulated radioactive materials, thus increasing the radiation exposure to crew members while below deck. The radiation environment due to ship contamination is derived from a previously-developed ship contamination model (Reference 6). Specific data regarding the development of the time-dependent radiation environments are presented in Section 2. Shipboard radiation surveys indicated a considerable variation in topside intensities because of ship geometry, redistribution of fallout during washdown and decontamination, and nonuniform adherence of fallout particles to ship materials. If only an average survey reading was reported, this value is used. In those cases where readings were taken at many predetermined positions on the ship’s exposed surfaces, they represent the topside radiation field. The ship’s crew is presumed to have been located at random positions when on deck; thus, the mean survey readings, appropriately decayed, are used to determine the mean intensities encountered by the crew when on deck. The distribution of survey readings suggests a distribution in radiation exposure to the crew. Uncertainties associated with mean survey readings

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topside, as well as those associated with various parameters in the ship contamination model, are addressed in the uncertainty analysis. The analysis of radiation exposure to the crew also requires estimation of radiation intensities below deck (due to fallout) and the apportionment in time of crew activities below and on deck. A ship-shielding factor is defined as the ratio of intensity below to the mean intensity topside. This factor, previously determined for each type of ship of interest in References 3, 4, 5 and 6, is roughly 0.1 and is nearly constant over the usual crew locations within a ship. Variations in this value, due primarily to different main deck thicknesses, are treated as an uncertainty in Section 4. Specific durations of topside exposure are given in ship logs for shot day (rarely thereafter) when the radiological situation altered the normal pattern of duties. For other days, and when unspecified, the topside intervals are taken to be 0800-1200, 1330-1700, and 1800-2000 hours, which amount to 40 percent of a day. The mean film badge dose to the crew is obtained from time integration of intensity for all intervals below (including the shielding factor) and on deck; a conversion factor is used to account for body shielding by the badge wearer (Reference 7). To facilitate the calculation, the daily fractional topside duration, rather than each specified interval, is used on the third and subsequent days after burst, when the lower intensity lessens the need for such precision in timing. Because the specified intervals are nearly centered around midday, this approximation is suitable by the third day. Day-by-day and cumulative film badge doses to the average crewman of each ship are calculated and presented in Section 3. Calculations are continued through 31 May 1954 when the roll”+p phase was drawing to an end. An uncertainty analysis of the dose calculations is provided in Section 4. In Section 5, the available dosimetry records are analyzed and compared with th~ calculated doses. Conclusions and a total dose summary are presented in Section 6.

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SHIP OPERATIONS AND RADIATION ENVIRONMENTS This section describes the movements of the TG 7.3 ships at the Pacific Proving Grounds during Operation CASTLE and correlates these movements with the radiation environment following the six detonations in the test series. Ship movements arq reconstructed primarily from data contained in the deck logs of the sixteen ships of interest (References 8 and 9). The shipboard radiation environments resulting from radioactive fallout are reconstructed based …