"8 OFFICIAL USE ONLY in this report will be directed to environment levels on Bikini and Eneu, the islands being rehabilitated by DOI. Comparison of External Radiation Survey Results Table I of this report is a summary of external radiation levels for Bikini and Eneu. These data indicate that the 1967 values for Bikini and Eneu were essentially correct. It is suggested that the values for 19659 are not different enough to warrant recalculating external exposures and that Dr. Gustafson's values in Table III of Attachment 1. and Table VIII of Attachment 2 still apply. The estimates in the column labeled "Modified" in Table III of Attachment 1 are obtained by assuming that the village area or areas around homes are covered with a layer of clean coral gravel 1 to 2 inches in depth. A further reduction in.external dose may be expected by a factor of two to ten for that exposure received during time spent indoors since homes are to be constructed from concrete blocks made from local materials. This reduction may be optimized by selecting sand and aggregate for making concrete from locations in the Atoll having the lowest levels of radioactivity. The external exposure estimates in Table VIII of Attachment 2 are based on the assyumpticn that 2 inches of clean coral gravel cover the ground around housing. However, a shielding factor for concrete block OFFICIAL USE ONLY a prmvmer oy te are tn Hate woes ie om sre! we , itd vat women te