nara: YS wrns tae Ldeee fodgeTS intaehe ae ed deters eh eneet ets ery, t te em electrometer with a digital readout. Bikini and Eneu Islands of the Bikini The instrument exhibits a flat energy Atoll. response over all gamma-ray energies integrated with previous programs to of interest to this survey. avoid duplication of effort. It is This sampling program was The capable of measuring exposure rates actual number of samples taken and from approximately 1 to 200 uR/hr with theix specific collection sites were an accuracy of about 5%. determined by expected activity levels, Thus, the data from this instrument were used as home-construction plans, agricultural a reference for measurements by other plans, and the number of locations of techniques. recent soil samples collected by other Exposure rates at 1 m above the programs. ground were measured with the Nal scintillator at approximately 2500 Methods and Measurements locations on a 30-m rectangular grid Two. types of soil samples were col- on Bikini Island and at about 120 lected for analysis: locations on a 120-m grid on Eneu surface-core sample of 60-cm Island. and a profile collection based upon The ionization chamber was a 15-cm deep, area, primarily used for measurements within sidewall sampling in a trench in which the central section of Bikini Island samples of 100-cm* area were collected with additional measurements made at at 15-cm-depth increments to a depth selected areas. of 90 cm. Thus, from this pro- gram a very comprehensive picture of To plan the survey, Bikini Island was divided into the north, the gamma-ray exposure rates at both central, and south sections along the islands is available. respective second baseline roads. Thermolumines- cent dosimeters (TLDs) provided a Eneu was divided by the airstrip into third technique for evaluating the the north and south sections. external dose. approximate numbers of surface and A complete report on The the external gamma measurements and profile samples collected within these resulting dose assessment has been sections are given in Table l. published.” Note that a major fraction of Soil Survey the surface samples were collected The soil sampling program was designed to identify the primary within the central section of Bikini ’ Island. This was because of the radionuclides contributing to the higher and more variable gamma- external gamma exposure and to deter- exposure rates in this area and the mine the geographical distribution of fact that a major fraction of the these radionuclides in the soil on returning Bikinians are likely bd 5009954