155 Eu, and pCi/g and 0.06 pCi/g. Tam were expected to As expected, contribute at most a few percent the profile samples showed a wide to the total exposure rates. range of activity distributions as This 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 cm (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 On Eneu Island, the uniform throughout the full range Each surface sample consisted of two 15-cm-deep cores. of depths sampled. Profile samples were obtained from data in conjunction with the data of the sidewall of a trench dug for Beck et al.,* we estimated the the purpose. average 137 Cs and 60 Co contributions On Bikini Island the ‘median 13766 and 690, activities Using these to the total gamma-ray exposure rates exhibited by the 15-cm-deep core over the two islands to be 94% and samples were 41 pCi/g and 0.74 pCi/g, 6%, respectively. respectively; while on Eneu Island, were assumed to be valid over the the corresponding values were 2.5 remaining islands of the atoll. These percentages 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 1 survey as well as on discussions inherent in the prediction of future living patterns. _ However, These were based upon our 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-