Appendix II Enewetak Radiological Survey Report Summary of Findings Chapter W. Nervik, Lawrence Livermore Labcratory, Livermore, California CURRENT RADIOLOGICAL CONDITION OF THE ATOLL INTRODUCTION External Gamma Radiation Levels It has been the purpose of this survey Three independent techniques were to gain a sufficient understanding of the total radiological environment of Enewetak used to measure external gamma radia- Atoll to permit judgments as to whether tion levels on the Atoll: or not all or any part of the Atoll can e LiF and CaFo thermoluminescent safely be reinhabited and, if so, what dosimeters (TLDs) were exposed preliminary steps toward cleanup should for 33 months on seven of the be taken and what post-rehabilitation con- northern islands. straints must be imposed, e Enewetak Atoll has an extremely - Atomic survey instrument was broad range of radiological conditions in a small land mass. made at each soil-sampling loca- To gain an under-~ tion on each island. standing of the details of this range of @ conditions, it has been necessary to obtain An aerial survey with Nal detectors - = WAD and analyze a very large number of sam- a eee he eee maw nee Verbs Yves thn bAte awtionn Vsewne ~ surface area of every island. ples from all components of the environment, A measurement using a Baird- All three techniques yield results To gain an equivalent understand- ing of the implications of this range of which agree to within about 10%. 137 conditions for rehabilitation of the and 8065 Cs contribute most of the total Enewetak people, it has been necessary external gamma radiation, with the to postulate population distributions, life remainder due to small amounts of other fraught with uncertainties under the best 125 155 Sb, Eu, gamma emitters such as and 241 Am. The amount of 60 Co rela- of circumstances, but particularly so for tive to 13766 varies throughout the Atoll, the current, rapidly changing Marshallese with a range of values from about 0,5 on culture. JANET to greater than 14 on JAMES. styles, and dietary habits — an endeavor This section is a summary of the data Average values for each isotope on each obtained from the Survey, the postulates island are given in Table 214, used, and the population dose assessments erence, a map of the Atoll is shown in derived from data plus postulates. Fig. 146, The For ref- Southern islands (SAM to KEITH) are reader is cautioned against expecting or using a ''simple' description of the radio- characterized by low and more or less logical condition of Enewetak Atoll, be- uniformly distributed gamma-radiation cause no single value of any component of levels over the area cf each island. the radiological condition is applicable to exposure levels increase, the entire Atoll without being misleading. ients become severe, with beaches II-1 As exposure grad-