[INPUT DATA Surface meteorological observations were avaliaole from some atolls anc from the U.S.S. Curtiss which cruised south of Bikini; however, since the larger particles fall rapialy from the debris cloud to the surface and spend little time near the surface, not many surface reports were used. Of far greater importance are the upper air wind observations taken at four sites near Bikini atoll. Other significant input data consisted of a flat topography, cell sizes of 34 km (east-west) by 17 km (morth-—south}, and 1 km in the vertical, stem and cap cebris cloud geometries at stabilization time, souree rates for both gross fission products and selected individual nuclides, and particle size spectrum parameters. CALCULATIONS Gross Fission Products The time-integrated external dose oattern (in rads) due to gross fission oroduects from detonation time to evacuation time of Rogelap atoll (51 hours) ure snown in Fig. 1. The numbers next to Ailinginae, Rongerik, and Utirik atolls are integrated values up to the time peoole were evacuated from those atolls. For comparison, the value of total dose, Note that estimated by Dunning’! and Strauss“! are given in Table 1. the agreement is very good for Rongelap and Ailinginae atolls. However, calculations for Rongerik and Utirik are at odds with earlier estimates. The code ealculaticns for Rongerik are higher, while those for Utirik are lower. This variation appears to be in part a problem of "tuning"; also a possible variation in wind directions and speeds at late times when the onlv wind observations were from the U.S.S. Curtis, south of Bikini (some distance from the atolls of concern) may be an explanation.