\ lectremeter “ith a digitai veadout. (b fikint The instrument exnibits a Zlat This sampling program was enere- integrated vith previous troerams to of avoid duplicarion or erfor t: this survev. It is th capable of measuring exposure rates rom approximately 1 to 200 UR/hr with an accuracy cz about 5%. Thus, the actual numb r or o interest samples ia response over 2il gamma-ray energies ~_s ~ne <sken end their specific collection sites vere determined bv expected activity leveis, data from this instrument were used a8 home-construction plans, a reference =sr measurements by other dlans, and the number of locations of techniques. recent soil samples Exposure rates at 1 m above the agricuitural collected bv other programs. ground were measured with the Nal scintillator it approximately -500 Methods and Measurements locations on 4 30-m rectanguiar gric Two types of soil sampies were col- on Bikini Island and at about 120 lected for analysis: locations on a 120-m grid on Eneu suriface-core sample of 60-cm- area, Island. and a profile collection based upon The ionization chamber was a 15-cm deep, primarily used for measurements within sidewall sampling in a trench in which the central section of Bikini Island samples of 100-em? area were collected with additional measurements made arc at 15-cm-depth increments to a depth selected areas. of 90 cm. Thus, from this pro- To plan the survey, 3ikini gram a very comprehensive picture of Island was divided into the north, the gamma-ray exposure rates at both central, islands is available. respective second baseline roads. cent dosimeters Thermolumines- (TLDs) provided a and south sections along the 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.” Soil Survey The soil sampling program was Note that a major fraction of the surface samples were collected within the central section of Bikini designed to identify the primary Island. This was because or 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