ae . IV. 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 oe RO 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 wr/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 8° Co On Nam and other islands closer to blast sites and **®sb. °°Co was the main contributor with important contributions from **° sb, 1°2@™Mpn, and sometimes **"Cs. Other isoto es, including 2°" Bi, *© 5 Bu, *S? hu, = 5 on, 1°SRh, +°Rh, 4 Ce, 239 P and #47 am, were aiso detected occasionally as was u. The range of radiation levels on each island are summarized below. SUMMARY OF RADIATION LEVELS - GAMMA EXPOSURE RATES Gir/hr) Island Exposure Rate Range Bikini 10-120 Weathered Areas 16-30 Close-to-Shore 20-40 Island Center Hot Spots 50-80 80-120+ Eneu 2-10 Nam 10-330 Outer Edge ne Island Center N.E. Corner Bokantuak, Iomelan, Rojkere, Eonjebi LO-30 Major Contributors *87 Gs *87 as °°co, **’cs 15-150 110-330 3-10 —~ 40 - *