TV. SUMMARY AND CONCLUSIONS An intensive external radiation survey of Bikini Atoll was carried out during April and May of 1967. Total exposure rates were found to vary considerably from island to island and from site to site on a given island. Levels measured over soil ranged from less than 10 ur/hr to over 500 ur/hr. (External gamma radiation levels in the United States due to naturally occurring emitters in the soil range from 0 to about 20 ur/hr.) On Bikini and Eneu Islands the major contributor by far to the total exposure rate was found to be **’cs with minor but significant contributions from f° Co and **®sb. On Nam and other islands closer to blast sites €°co was the main contributor with important contributions from **°sb, *°®™Rh, and sometimes *°"Cs. Other isotopes, including 2°" Bi, *5S mu, *F* Bu, °F Zn, *°8Rh, *°? Rh, *4* Ge, and ***am, were also detected occasionally as was *°* Pu. The range of radiation levels on each island are summarized below. SUMMARY OF RADIATION LEVELS - GAMMA EXPOSURE RATES Gir/hr) Exposure Rate Range Island Bikini 10-120 Weathered Areas Close-to-Shore Tsland Center Hot Spots 16-30 20-40 50-80 80-120+ Eneu Nam Outer Edge Island Center N.E. Corner Major Contributors *8 705 2-10 +37 Gg 10~330 10-30 =°Co, +87 G5 15-150 110-330 Bokantuak, Iomelan, Rojkere, Eonjebi 3-10 - 40 ~ *