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. DNA 001-83-C-0039 DEFENSE NUCLEAR AGENCY

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REPORT DOCUMENTATION PAGE OM8 No. 07044188 ?a,SECURITY CLASSIFICATION AUTHORIW 3 DlSTR18UT10N/AVAILABILITY OF REPORT X/A since t:nclassiiied Approved for public release; distribution is unlimited. ! PERFORMING ORGANIZATION REPORT NUMBER(S) 5. MONITORING ORGANIZATION REPORT NUM8ER($) $a.NAME OF PERFORMING ORGANIZATION 6b. OFFICE SYMEOL 7a. NAMEOF MONITORING ORGANIZATION SCIEXCE APPLICATIONS Director INTEF.YATIOXALCORPOMTION 1 Defense Nuclear Agency la, NAME OF FUNDINGJSPONSORING 8b. OFFICE SYM90L 9 PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ANALYSIS OF RADIATION EXPOSURE FOR NAVAL PERSONNEL AT OPERATION CASTLE 3a TYPE OF REPORT 13b. TIME COVERED 14 DATE OF REPORT (Year, Month, LW 15. PAGE COUNT Technical Report FQOM 830101 T0840131 This work was sponsored by the Defense Nuclear Agency under RDT&E RXSS Code 7 COSATI COOES 18 SU6JECT TERMS (Continue onreverse~f necesswy and Klentlfy by bkxk number) FIELD GROUP SUE-GROUP Operation CASTLE 6 18 Radiation Exposure Assessment 6 21 Nuclear Test Personnel Review (NTPR) Film badge doses are reconstructed for sixteen ships and the residence islands of Enewetak and Kwajalein Atolls resulting from the six nuclear detonations comprising @eration Q~STLE (Xarcil-:[ay1954). Fallout from Shots BRAVO and ROMEO was the major source of contamination on most of the ships and islands. varying amounts of fallout from Shots UNION, YiMKEE, ~fld NECT.LR contributed somewhat to the total doses of the shipboard and island-based personnel; no fallout was experienced as a result of Shot KOON. Shipboard personnel received additional exposure from hulls and salt water piping systems that had become contaminated from operating in the radioactive waters of Bikini Lagoon. From the reconstructed radiation environments, both topside and below> an equivalent film badge dose is calcul~ted and compared to actual dosimetry data. Agreemen$ is very good during badged periods when the ships received significant fallout. When topside intensities 20 DlSTR18UT10N/AVAlLA81LlWOF ASSTP.A~ 21 ABSTRACT SECURITY CLASSIFICATION DDF0RM1473, 84MAR 83 APR ldltfon maybe used unt!l exhausted. SECIJRITY CLASSIFl~TION OF THIS PAGE All othef edmom lre obsolete. UNCLASSIFIED

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Joint Task Force Seven Oceanic Nuclear Tests were not documented, generally late in the operation when intensity levels were low, agreement is not as good. Calculated ship contamination doses of significance are in excellent agreement with limited available dosimetry data. Calculated average doses for shipboard personnel range from a low of 0.19 rem for the crew of the USS LST-825 to a high of 3.56 rem for the crew of the USS PHILIP. Average doses on the residence islands of Enewetak and Kwajalein Atolls are 1.09 rem ~~ and 0.32 rem, respectively.

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TABLE OF CONTENTS LIST OF ILLUSTRATIONS 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 3.2.1 Enewetak Atoll Dose Calculations 3.2.2 Kwajalein Atoll Dose Calculations 3.2.3 USS APACHE Dose Calculations 3.2.4 USS t3AIROK0 Dose Calculations 3.2.5 USS 13ELLE GROVE Dose Calculations 3.2.6 USS CURTISS Dose Calculations 3.2.7 USS EPPERSON Dose Calculations 3.2.8 USS ESTES Dose Calculations 3.2.9 USNS FRED C. AINSWORTH Dose Calculations 3.2.10 USS GYPSY Dose Calculations 3.2.11 USS LST-551 Dose Calculations 3.2.12 USS LST-762 Dose Calculations 3.2.13 USS LST-825 Dose Calculations 3.2.14 USS LST-975 Dose Calculations 3.2.15 USS NICHOLAS Dose Calculations 3.2.16 USS PHILIP Dose Calculations 3.2.17 USS RENSHAW Dose Calculations 3.2.18 USS S1OUX Dose Calculations 5 FILM BADGE DOSIMETRY 6 CONCLUSIONS AND TOTAL 7 LIST OF REFERENCES

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LIST OF ILLUSTRATIONS Northern Marshall Islands Bikini Atoll, Operation CASTLE shot [ocations 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 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 due to ship 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 following Shot BRAVO 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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LIST OF ILLUSTRATIONS (Concluded) 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 SIOUX topside intensity following Shot BRAVO USS S1OUX topside intensity following Shot ROMEO Sea water intensity measured from the USS SIOUX 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 are applicable Daily integrated intensity, residence islands of Enewetak Atoll Daily integrated intensity, Kwajalein Atoll Daily integrated intensity, USS APACHE Daily integrated intensity, USS 13AIROK0 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-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 i3AIROK0 film badge dose, USS BELLE GROVE film badge dose, USS CURTISS film badge dose, USS EPPERSON film badge dose, USS ESTES film badge dose, USNS FRED C. AINSWORTH film badge dose, USS GYPSY film badge dose, USS LST-551 film badge dose, USS LST-762 film badge dose, USS 1ST-825 film badge dose, USS LST-975 film badge dose, USS NICHOLAS film badge dose, USS PHILIP film badge dose, USS RENSHAW film badge dose, USS SIOUX 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 fQm badge coverage is incomplete, it is necessary to reconstruct the radiation dose. T*his 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 film 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 each test are summarized in Table 1-1 CASTLE detonations. The pertinent details of 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 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 (3TF-7). Although military in form, it was colm~rised of military, civil service, and contractor personnel. ITF-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 1-2 is a summary of the atolls and ships for which dose reconstructions are specifically addressed in this report. Also 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 reconstmctions are applicable. Enewetak Atoll (Enewetak, Parry, and Japtan Islands) 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 bet~en ship and shore because of early-time washdown, decontamination, and weathering, late-time decay, mostly fram 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 timedependent 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 non-uniform adherence of fallout particles to ship materials. If only an-average survey r-eading 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% 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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CNIT Operations contamination (,AFTER-ACTloN (DECK LOGS) MODEL REPORTS) Figure 1-4. operation CASTLE dose reconstruction methodology.

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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 other days, and when unspecified, the topside intervals are taken to 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 of duties. For 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-up phase was drawing to an end. An uncertainty analysis of the dose- calculations is provided in Section 4. In Section 5, the availabIe dosimetry records are analyzed and compared with the 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 …