Appendix II Enewetak Radiological Survey Report Summary of Findings Chapter W. Nervik, Lawrence Livermore Laboratory, 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. A measurement using a Bairdmade at each soil-sampling loca- To gain an under- tion on each island. standing of the details of this range of e conditions, it has been necessary to obtain An aerial survey with Nal detectors was conducted over the entire and analyze a very large number of sam- surface area of every island. pies from all components of the environment, All three techniques yield results To gain an equivalent understand- which agree to within about 10%. nd 137 ing of the implications of this range of conditions for rehabilitation of the a 606, 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 styles, and dietary habits — an endeavor gamma emitters such as 125¢), 1995p ’ fraught with uncertainties under the best and 241 Am, of circumstances, but particularly so for tive to the current, rapidly changing Marshallese with a range of values from about 0.5 on culture, JANET to greater than 14 on JAMES, This section is a summary of the data 13 The amount of 80K rela- "Cs varies throughout the Atoll, 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 of each island, the radiological condition is applicable to exposure levels increase, exposure grad- the entire Atoll without being misleading. ients become severe, with beaches II-1 As