74 - RADIOLOGICAL CLEANUP OF ENEWETAK ATOLL average exposure rate was defined for each island. When an average Tate was needed for a group of islands, it was obtained by weighting individu) island rates according to the area of eachisland in the group. The exposur, rates were converted to absorbed dose based on assumed duration of exposure. Inhalation dose estimates were determined using the Internationa Commission on Radiological Protection (ICRP) lung model. Intakes tg this model were derived from concentrations of plutonium in soil and ay assumed air-mass loading. (Average concentrations for plutonium in Soil of islands/group of islands were used.) This method was considereg preferable to using the survey air sample data, which were representative only of a very short period of time. Had actual air sample data been useg inhalation dose estimates would have been several orders of magnitude lower than reported. Ingestion dose estimates were based on an assumeddiet (including loca marine andterrestrial food and imported food) and measuredorderived concentrations of radionuclides in components of the diet. Significant radionuclides for ingestion dose were determined to be cesium-137 ang strontium-90. A concentration for these nuclides was determinedfor the average fish of the atoll, for use in estimating doses via the marine food pathway. The concentration of the significant radionuclides in terrestrial) foods was estimated primarily by correlation between concentrations of radionuclides in soil and in indicator plants or animals. The survey report included estimates of annual dose rate and accumulated dose over extended periods of time for the various living patterns. The effect on possible dose due to cleanup modifications; e.g., covering contaminated soil with clean soil, plowing soil to mix contaminated surface layers with cleaner subsurface layers, was assessed. The report ranked dose pathways in the following order of decreasing dose: ingestion of terrestrial food; external gamma exposure;ingestion ofmarine food; and inhalation of contaminated air. The most significant contribution to dose via the terrestrial food chain was determined to be strontium-90 in pandanus, breadfruit, and coconut.55 The Enewetak Radiological Survey provided a data base and general concepts for radiological cleanup. Considerable effort was still required, however, to evaluate and adapt the data for actual cleanup operations. AEC TASK GROUP REPORT: JULY 1973-JUNE 1974 In July 1973, an AEC Task Group was appointed by the Director, Division of Operational Safety of the AEC, to review NVO-140 and to prepare cleanup and rehabilitation recommendations. Members of the eeee