. Both pronethium (aud its progenitors) and uranium have higher temperatures of condensation than the case for strontium and its progenitors. Thus, the fractionaticn observed for strontium and uraniun are understandable, while promethium might be an example of one sample not being representative. The radioactivity of interest at Eniwetok Atoll is, however, primarily local fallout rather then the cloud properties detailed above. * 2 ¥ ¥ f ‘the local fallout is largely from larger particles. A semiempirical model (Freiling, 1970) for land-surface explosions takes this into account in predicting the local fallout compared to world- wide and intermediate-distance fallout. (The local fraction is con- sidered to be from particles greater than 50-microns in diameter, the : intermediate fraction from 25- to 50-microns particles, and the worldwide fraction from less than 25-micron particles.) The percentage of the total radioactivity of a particular radionuclude that deposits in local fallout from these land surface bursts is estimated to be “— * Radionuclides Percentage in Local Fallout cesium-137 and strontium-89 10 strontium-90 15 barium-140 and lanthanum-140 25 tellerium-132 25 zincronium-90, niobium-89, molybdium-99 and plutonium-239 DATO! eB oe on sen eee 65 a eee Cre +