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Appendix A Examples of Dose Reconstruction Memoranda from Sample Cases Reviewed by Committee
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MEMORANDUM 23 December 1995 To: DNA-DFRA/NTPR (CDR M. Ey) From: SAIC (E. Ortlieb) Subject: Radiation Dose Assessment Operation Castle (1954) BACKGROUND (References 1, 2) Operation Castle comprised six nuclear weapon tests conducted at the Pacific Proving Ground (PPG) between 1 March and 14 May 1954. The PPG, located in the Central Pacific Ocean area, consisted of the land areas, lagoons, and water areas within three miles of two Marshall Islands atolls, Enewetak and Bikini. Bikini Atoll is about 2200 nautical miles southwest of Hawaii, and Enewetak Atoll is about 195 nautical miles west of Bikini Atoll. The principal objective of Operation Castle was to test high-yield thermonuclear devices. All but the last were detonated at Bikini. UNIT AND PERSONAL ACTIVITIES (References 1 through 4) First Lieutenant was the Officer in Charge (OIC) of the Traffic Analysis Section of the Communication Security Detachment (Comm Sec Det), 8600 Administrative Area Unit, at Operation Castle. He arrived at Enewetak with the unit on 17 December 1953 by air transport from Travis AFB, California, and departed the PPG from Enewetak on board USNS FRED C. AINSWORTH (TAP 181) on 14 May 1954. The veteran was detached for return to his home station when AINSWORTH arrived in San Francisco on 27 May 1954. While at PPG, unit personnel were stationed at various times on Enewetak, Bikini, and USS ESTES (AGC 12). Reference 4 includes a statement by the veteran indicating that he was on temporary duty (TDY) from Enewetak to Bikini until March 1954, “…or the big shot,” and that at some time during the operation he was aboard a “communication” ship. These recollections are consistent with CASTLE documentation. As of 1 March 1954, 24 of the 34 unit personnel, including the veteran, were stationed at Enewetak Atoll (as per communication from CO, Comm Sec Det, to Rad Safe Officer, 18 March; in Reference 4); the 10 at Bikini had evacuated for Shot BRAVO aboard ESTES on the previous day. As Bikini was too radiologically contaminated by BRAVO to permit remanning, the detachment remained aboard until the unit departed the pro. Reference 3 states that the personnel of the unit were rotated frequently between Enewetak and ESTES but that a rank and MOS balance was retained. There is no direct evidence available of the veteran’s rotation, but there was another lieutenant with his MOS.
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EXTERNAL DOSE ASSESSMENT Available Dosimetry: Film badge dosimetry records indicate that the veteran was to have been issued badge #14689, apparently on 29 March 1954 (two days after Shot ROMEO). If issued, there was no recorded return date or exposure reading. There are no other film badge records for the veteran; however, his personal dosimetry card shows assessed doses of 0.075 rem from Shot BRAVO and 0.500 rem from Shot ROMEO (periods not specified). These assignments indicate his presence on Enewetak for most, if not all, of March. Radiation Environments: (Reference 2) The veteran could have been exposed to fallout from the detonations indicated below: Site Shot Date Peak Intensities (mR/hr) Time (H+ hours) Enewetak BRAVO 1 Mar 54 10 16 Enewetak ROMEO 27 Mar 54 8.5 77.5 ESTES ROMEO 12 42 While in ESTES, the veteran also would have been exposed to residual radiation from Shot BRAVO; and while in AINSWORTH, from both BRAVO and ROMEO. Neither Enewetak nor ESTES was exposed to fallout from subsequent shots prior to the veteran’s departure. AINSWORTH departed PPG early on 14 May and did not receive any radioactive fallout from the last shot of the series (NECTAR, detonated at Enewetak). Daily doses to generic personnel on Enewetak and ESTES are calculated in Reference 2. After the arrival of ROMEO fallout, the Enewetak daily doses are somewhat greater than those in ESTES. Given that the veteran’s my to ESTES was for an unknown interval, apparently after ROMEO, his dose is high-sided by a reconstruction based on his continuous presence on Enewetak until departing in AINSWORTH. Exposure to Initial Gamma and Neutron: Personnel at Enewetak Atoll were too distant from any CASTLE shots at Bikini Atoll to have received any measurable initial neutron or gamma dose (Reference 5). Similarly, there was no exposure to initial radiation while aboard ESTES or AINSWORTH. The reconstructed doses from Reference 2 are zero for the period prior to Shot BRAVO (for both Enewetak aM Bikini); 0.288 rem at Enewetak. from 1 March to 26 March; 0.715 rem at Enewetak. from 27 March until 14 May; and 0.030 rem aboard AINSWORTH until detachment on 27 May 1954. Note that the reconstructed doses for Enewetak, are greater than the above CASTLE assessed doses associated with BRAVO and ROMEO (whatever their coverage dates may have been).
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INTERNAL DOSE ASSESSMENT The (50-year) committed dose equivalent to the colon (lower large intestine) is calculated using the methodologies presented in References 6 and 7. A nominal breathing rate of 1.2 m3/hr, a characteristic resuspension factor of l0−5m−1. and particle size of 20 μm activity median aerodynamic diameter are applied for the calculations. The bulk of resultant dose was from inhalation of descending fallout from Shots BRAVO (0.07 rem) and ROMEO (0.59 rem). Additional accumulations resulted from inhalation of resuspended fallout particles on Enewetak from BRAVO (0.03 rem) and ROMEO (0.06 rem), and in AINSWORTH (0.00 rem). The total committed dose equivalent to the colon is 0.8 rem. TOTAL DOSE SUMMARY External Dose: Neutron: Inclusive Dates at PPG Dose (rem) Method 17 Dec 53 – 14 May 54 0.000 Reconstruction Gamma: Inclusive Dates Dose (rem) Method 17 Dec 53 – 28 Feb 54 0.000 Reconstruction 1 Mar 54 – 14 May 54 1.00 Reconstruction 15–27 May 54 0.030 Reconstruction Total 1.1 (Upper bound of 1.3) Internal Dose: The total committed dose equivalent to the colon is 0.8 rem. References 1. “CASTLE Series—1954,” DNA 6035F, Defense Nuclear Agency, 1 April 1982. 2. “Analysis of Radiation Exposure for Naval Personnel at Operation CASTLE,” DNA-TR-84-6, Defense Nuclear Agency, 28 February 1984. 3. “Unit Final Report for Operation CASTLE,” Communication Security Detachment, 8600 AAU, APO 187, 8 May 1954. 4. Documents located in the veteran’s NTPR files. 5. “Neutron Exposure for DOD Nuclear Test Personnel,” DNA-TR-84-405, Defense Nuclear Agency, 15 August 1985. 6. “FIIDOS—A Computer Code for the Computation of Fallout Inhalation and Ingestion to Organs,” DNA-TR-84-405, Defense Nuclear Agency, 15 August 1985. 7. “Low Level lnternal Dose Screen—Oceanic Tests, Nuclear Test Personnel Review,” DNA-TR-88-260, Defense Nuclear Agency, October 1991.
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DTRA-NSSN 1767 RADIATION DOSE ASSESSMENT Operation GREENHOUSE (1951) Background Information Operation GREENHOUSE was a series of four nuclear weapons tests conducted at Enewetak Atoll, Marshall Islands, from 8 April to 25 May 1951. Enewetak Atoll is about 2370 nautical miles (nmi) southwest of Hawaii. All four shots were tower bursts. The shots were detonated on the northeast islands of Enewetak Atoll, at a minimal of 8 nmi from the southeast islands, Enewetak and Parry, on which most land-based support personnel were located. Additional personnel were based at Kwajalein Atoll, about 370 nmi southeast of Enewetak. Fallout from all shots except GEORGE impacted the southeast islands of Enewetak Atoll. No fallout from GREENHOUSE shots was detected at Kwajalein. The shot times, dates, locations, and yields in kilotons (kT) are identified in Table 1. (References It 2) Table 1. Nuclear shot and geographic data, Operation GREENHOUSE. Shot Local Time/Date (1951) Enewetak Atoll Locations Yield (kT) DOG 0634/ 8 Apr Runit Island 81 EASY 0627/ 21 Apr Enjebi Island 47 GEORGE 0930/ 9 May Eleleron Island 225 ITEM 0617/ 25 May Enjebi Island 45.5 Unit and Personal Activities During GREENHOUSE, the veteran was a Corporal and an Apprentice Auto Mechanic assigned to the 3200th Drone Squadron, based at Eglin Air Force Base, Florida. From 27 February through 18 June 1951, he was on temporary duty with Task Unit (TU) 3.4.1 (Headquarters and Headquarters Squadron) at Enewetak Atoll. TU 3.4.1 operated the airbase on Enewetak Island, including the base operations facilities and maintenance and supply support for aircraft. The task unit also had a detachment on Kwajalein Atoll to provide maintenance and supply support to aircraft landing at this location. The veteran could have been alternately assigned to duty on Enewetak Island and Kwajalein Atoll during his GREENHOUSE tour, but no records were located that placed him at Kwajalein. As an auto mechanic, he would not have been involved in drone decontamination or other maintenance activities that were the responsibility of TU 3.4.2 (Experimental Aircraft). (References 1,3,4) There are no indications that the veteran was involved in any activity that may have resulted in radiation exposures related to GREENHOUSE other than those documented herein.
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External Dose Assessment Dosimetry: No film badge record was found for the veteran (References 3, 5). Exposure Scenarios: The veteran was potentially exposed to the following sources of radiation: Initial gamma and neutron radiation. Residual fallout at Enewetak Island. Reconstructed Dose Initial Radiation: Because of his location at Enewetak Island and its distance from the detonations, the veteran received no doses from initial gamma and neutron radiation (References 6-8). Residual Fallout at Enewetak Island: The veteran was exposed to radioactive fallout during GREENHOUSE while billeted and working on Enewetak Island. Table 2 identifies the peak intensity measured in roentgens per hour (R/hr) and the time of this peak intensity following each shot. Table 2. Peak intensities on Enewetak Island after GREENHOUSE shots. Shot Peak Intensity (R/hr) Time of Peak after Shot (hr) DOG 0.04 6.4 EASY 0.001 24 GEORGE 0.0 No fallout ITEM 0.118 13.7 From Table 2, it is apparent that most of the dose accrued by personnel at Enewetak Island was due to fallout from ITEM. Doses received during the veteran’s dates of duty on Enewetak are summed over time using the radiation decay that followed each peak intensity (References 1, 9-12). The veteran is assumed to have been exposed outdoors for 60 percent of his time while on Enewetak and exposed indoors with 50-percent shielding for 40 percent of his time. A reconstruction based on the above parameters results in a 3.76 rem dose during the period of time the veteran was at Enewetak (References 9-12). His gamma radiation dose is summarized below. External Dose Summary Neutron: 0.00 rem. Gamma Inclusive Dates (1951) Dose (rem) Method 2 Feb – 7 Apr 0.00 No exposure potential 8 Apr - 18 Jun 3.76 Reconstruction (Enewetak Island) Total 3.8 (upper bound 4.4)* *Based on uncertainty factors for reconstructed doses (References 9, 11).
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Internal Dose Assessment The methodology of References 13 and 14, together with the FIIDOS code (Reference 15), provides a means of calculating the internal dose to a given organ or tissue, based on existing intensity measurements, film badge readings, or dose reconstructions. For internal exposures, airborne radioactive particles are assumed to be fully respirable with an Activity Median Aerodynamic Diameter of 1 micrometer (Reference 16). Based on radiochemistry data for Shots DOG, EASY, and ITEM, and the aforementioned intensity measurements, the veteran’s (50-year) committed dose equivalent to spinal nerve tissue from the inhalation of descending nuclear debris in the fallout on Enewetak Island is less than 0.01 rem. For the inhalation of resuspended fallout, a resuspension factor of 10−5m−1 is applied to the assumed 60 percent of the time spent outdoors, resulting in less than 0.01 rem to spinal nervous tissue. Internal Dose Summary: The veteran’s total committed dose equivalent to spinal nervous tissue is less than 0.1 rem. References 1. “Operation GREENHOUSE, 1951” DNA 6034F, Defense Nuclear Agency, 15 June 1983. 2. “United States Nuclear Tests, July 1945 through September 1992,” U.S. Department of Energy, DOE/NV-209 (Rev. 14), December 1994. 3. Veteran’s Nuclear Test Personnel Review (NTPR) file: service record, monitoring reports, and medical records. 4. “Operation GREENHOUSE, Communications Technical Report, 1951,” WT-45, Joint Task Force 3, 1951. 5. Microfiche records of film badge readings. 6. “Neutron Exposure for DoD Nuclear Test Personnel,” DNA-TR-84-405, Defense Nuclear Agency, 15 August 1985. 7. “DoD Nuclear Test Personnel Not Exposed to Neutron Radiation,” SAIC Memorandum to DNA-DFRA/NTPR, 7 September 1995. 8. The Effects of Nuclear Weapons, third edition, compiled and edited by Samuel Glasstone and Philip J. Dolan, United States Department of Defense and Department of Energy, 1977. 9. “Analysis of Radiation Exposure for Naval Personnel at Operation GREENHOUSE,” DNA-TR-82-15, Defense Nuclear Agency, 30 July 1982.
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10. “Daily Dose Tables for GREENHOUSE Residence Islands,” SAIC Memorandum to DNA-RAEM/NTPR, 8 March 1994. 11. “Analysis of Radiation Exposure for Personnel on the Residence Islands of Enewetak Atoll after Operation GREENHOUSE, 1951-1952,” DNA-TR-85-390, Defense Nuclear Agency, 20 April 1987. 12. “Calculated Daily Doses for Personnel on the Residence Islands of Enewetak Atoll, April-June 1951,” SAIC memorandum, 22 June 1987. 13. “Low Level Internal Dose Screen - OCEANIC Tests,” DNA-TR-88-260, Defense Nuclear Agency, October 1991. 14. “Low-Level Internal Dose Screen - CONUS Tests,” DNA-TR-85-317, Defense Nuclear Agency, 22 December 1986. 15. “FIIDOS - A Computer Code for the Computation of Fallout Inhalation and Ingestion Dose to Organs, Computer User’s Guide,” DNA-TR-84-375, Defense Nuclear Agency, 12 December 1985. 16. “Limits for Intakes of Radionuclides by Workers,” Publication No. 30, International Commission on Radiological Protection, Pergamon Press, New York, July 1978.
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