Ne eres —_ Clearing Experiment - Bikini O-1" 1-2" 2-3" 3-4" 4-5" 5-6" 89% 81% 88% 85% 81% 74% 1% 1% 2% 5% 5% 6% 9% 6% B% 9% 15% *Very low energy y-ray emitters such as are not included in the total activity. **Includes contributions from *°°Rh, when present. L5 4% 10% 5% 6% 5% 6% | ® Bu ~°2™pn, and 2414 m and *°’ Bi The percentages for each isotope are relatively unchanging with depth. Since the standard deviation in the concentration measurements is sometimes guite large (see Table 2), this suggests our second assumption is also reasonable. The percentage of the total exposure rate due to each of these isotopes was calculated for each of these sites using the average percentage concentration over all depths and compared with the field spectrometer data with excellent agreement. These results are given in Section III in the discussion of the Bikini Island data. The data from the analyses of all the soil samples obtained on the other islands of the atoll were then used in a similar manner to estimate the percentage of the average total exposure rate ehh around the site due to each isotope in the soil. During the 1964 Bikini Atoll survey a number of soil samples had also been obtained and analyzed by the University of Washington. None of these samples were from exactly the same locations as the 1967 samples; however, this calculation Ripperaf of percentage of total exposure rate due to each emitter was also done for these data. The results in general were consistent with the 1967 results. the primary contributor in 1964, -~12- On islands where *°’Cs was it still is in 1967. On