ses ‘ On oy Dats: 78 . few irate baci ot. 1999 FOLOER Enrwelat EOX No, 5 695 June-July Js lands i. “ z.< = Z © QO XSW Internal Oistribution 8 ” wre 2. = wenn = > a Zz o8) = =) Q © A Reviewed by = + zy Di JK Soldat oe = . bert W. J. Bair/R. 0. Gil | Project Number © t ‘ From B. A. Napier Subject’ ENEWETOK DOSE ASSESSMENT REVIEW oo ok, JuLt 1 12 ve. BAR ne - EC Watson File/LB 409837 R I have reviewed the methodology and results of calculations performed by Lawrence Livermore Laboratory for future inhabitants of Enewetok Atoll. In general, I concur with their methods and conclusions. However, I have some questions and suggestions for the next draft of the LLL document. T used slightly mocified versions of our computer codes PABLM and iMAXI to calculate 30- and 50-year accumulated doses and maximum annual doses. I also used the code DACRIN to try to duplicate some inhalation dose results. I needed to modify the first two codes in order to accommodate the specific diet of the Harshall Islands. The codes PABLM and MAX] basically incorporate the recommendcations of ICRP-2, and DACRIN uses the ICRP Task Group on Lung Dynamics model. I took plant concentration to soil concentration ratio data from the LLL document where available, and assumed conservative values elsewhere. The doses calculated are for an adult male only. I did not have time to modify the codes further for children and women. I.did reduce the masses of al] organs by a uniform 15°) to account for the smaller size of Marshall Islanders from the XS 2 Her Ua OMY NN L cottection Marshal ( O 106 To July 9, 1979 otf Of Re on Pacific Northwest Laboratories pae . standard man. I attempted to incorporate as many of the Livermore assumptions as I could, to try to follow their exposure scenarios. All ingestion doses therefore allow an €0-year period initially during which no radionuclides are ingested. I did calculate external irradiation doses based on soil concentrations, even though this was really not necessary since the reported values were based on actual measurements. results. I was able to come comfortingly close ‘+10%) to their Livermore reports only contributions from ©°Co and ?3’Cs + 0. Our program indicated a small calculated contribution from !°2Eu, but never more than a few percent. Since it has a short halflife, it is probably not worth worrying about. There is not sufficient data presented in the LLL rough draft to predict doses from isotopes of plutonium, even though they do present dose results. I believe they may have predicted plutonium concentrations based on a Pu/Am ratio, but no confirmations of this appears in the report. There is not sufficient data presented in the LLL report to predict inhalation doses from any radionuclide. No resuspension data is given for the inhalation pathway. I have used a resuspension factor of 10-’m-!, based on work by Anspaugh, and allowed only the top centimeter of soil to be available for resuspension. Since the inhalation doses vary directly with resuspension, these are somewhat arbitrary values. Though the initia] inhalation doses are relatively small, at long times they will come to be the controlling pathway. The remaining radio- nuclides (actinides) contribute mainly via the inhalation pathway.