Phase IV The only island included in this phase is Yvonne, which to our knowledge is the most contaminated island in the atoll. Field surveys will be conducted with the FIDLER and the Baird-Atomic scintillator in order to supplement data obtained during previous surveys, The ob- jective here will be to obtain survey data on at least as small a grid pattern as is obtained for the other islands. Similarly, a number of soil samples will be collected in selected locations for purposes of evaluating the extent of cleanup required to rehabilitate the island, The extent to which additional data can be obtained by the survey group which speak to either the radiological hazard on Runit or to the engineering aspects of the cleanup operaticn is not clear at this time. The kind and amount of such additional data will be determined in the field by the survey team. Thermoluminescent Dosimetry Program Since the energy response of the Baird-Atomic NaI scintillator is nonlinear, the measurements made by this instrument may not be a true measure of the external dose rate produced by the gamma emitting radionuclides deposited in the soil. To overcome this deficiency we plan to incorporate a thermoluminescent dosimetry (TLD) program which will provide a correlation between the NaI scintillator measurements and the actual dose rate measured by the TLDs. This program will utilize a combination of LiF and CaF, : Dy TLD packets. Approximately 40 packets will be placed at selected locations in such a manner that a broad range of dose rates from 2 p R/hr will be measured for the correlation study. uw R/hr to 200 In order to eliminate exposure during transit time, the dosimeters will be annealed at Eniwetok Island just prior to their placement in the field. exposed for one month or more in the field, After having been the TLD packets will be re- covered and read out at Eniwetok Island. IV. ATR, BIOTA, and POTABLE WATER SURVEY The objectives of the terrestrial air, biota, and potable water sampling program are: a) To collect representative samples of edible plants and animals for radionuclide analysis and subsequent estimation of food-chain transfer of radionuclides to future inhabitants. -~18-