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 over soil ranged from less than 10 pr/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 pr/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 and **®sb. On Nam and other islands closer to blast sites ®°co was the main contributor with important contributions from +25 cp, 1°2Mpnh, and sometimes *°"Cs. Other. isotopes, including *°’Bi, **°nu, **?Eu, °®gn, *°*Rh, *°*Rh, ***Ce, and ***am, were also detected occasionally. The range of radiation levels on each island are summarized below. SUMMARY OF RADIATION LEVELS — GAMMA EXPOSURE RATES (jr/hr) Exposure Rate Isiand Bikini Weathered Areas Contributors} 10-120 *37 a5 16-30 Close-to-Shore Island Center Hot Spots 20-40 50-80 80-120+ Outer Edge Island Center 10-30 15-150 Eneu Nam N.E. 2-10 10-330 Corner Bokantuak, Rojkere, 3-10 Eonjebi - 40 - eee eee *37Cs °°co, *37es 110-330 Iomelan, Me roam Major Range pe ee eg ee eg ee = * ey alo ea