Appendix 14 Gamma Radiation Measurements on Bikini Island, 1974 External gamma exposure rate measurements were made by N. A. Greenhouse and V. A. Nelson in the village area on Bikini Island during December 1974. The measurements were made with a Reuter-Stokes environmental radiation monitor, model RSS-lll, which uses a pressurized ion chamber as a detector. The response of this instrument is relatively independent of gamma-ray energy (£5%) for incident photons from about 0.2 to 4 MeV. (The largest contribu- tor to the gamma background at Bikini is 137¢g with a gamma energy of 0.667 MeV.) The results, which include cosmic-ray background (~4 uR/hr; 35 mR/yr), are given in the table below. Measurements made through the interior of Bikini Island along the "center baseline" road indicated gamma exposure rates from 3 to 6 times as high as the village averages. A detailed survey of the interior is planned for early 1975. Location Gamma exposure rate Vl m above floor or ground, uR/hr Annual gamma exposure, mk Inside Back yard Inside Back yard House #4 7.8 13.2 68 116 House #20 8.0 7.7 70 67 House #28 9.3 15.5 81 136 House #40 «943 15.5 81 136 75 114 Average C51 - 154 = ‘