155 Eu, and Lam were expected to contribute at most a few percent to the total exposure rates. This pCi/g and 0.06 pCi/g. AS expected, the profile samples showed a wide . range of activity distributions as was confirmed by Ge(Li) gamma a function of depth on the two spectral analyses of several islands. hundred soil samples collected on are difficult to: make, the activities both islands during the June 1975 on Bikini Island usually decreased survey. with depth in the first few centi- The detailed results of Even though generalizations the soil survey will be published meters with a relaxation length of in a subsequent report. about 5 em (the depth at which the In summary, the soil survey included the random activity is et, or 37% of the surface collection of two types of soil activity). samples on each island: activities were relatively low and and profile. surface Each surface sample On Eneu Island, the uniform throughout the full range consisted of two 15~-cm-deep cores. of depths sampled. Profile samples were obtained fron. data in conjunction with the data of the sidewall of a trench dug for the purpose. median 137, On Bikini Island the and 600, activities exhibited by the 15-cm-deep core samples were 41 pCi/g and 0.74 pCi/g, Using these Beck et al. vo we estimated the average 137 Cs and 606, contributions to the total gamma-ray exposure rates over the two islands to be 94% and 6%, respectively. These percentages respectively; while on Eneu Island, were assumed to be valid over the the corresponding values were 2.5 remaining islands of the atoll.- External Dose Estimation In addition to the gamma-ray reasonable selection of possible exposure rates, we need to consider conditions that would cover the range the expected living patterns of the of doses that could be received by future inhabitants in order to any sizeable segment of the popula- evaluate the external dose problem. tion. Of course, many uncertainties are experiences during the Enewetak inherent in the prediction of future living patterns. However, _ Survey” These were based upon our 1 : as well as on discussions with personnel from the Trust the following cases, shown in Territory of the Pacific Islands. Table 1, have been chosen as a Suggestions have also been solicited -14-