distance versus time of arrival or distance versus time of duration yielded an estimated fallout arrival of 17 hours post detonation at Utirik Island and a fallout cessation time of 36 hours post detonation. These new values for ar- rival and cessation times were estimated based on the fact that people at Utirik Island were 570 km from the BRAVO detonation site. The derived values for fall~ out arrival and cessation times at Utirik Island departed somewhat from the original estimates of Sondhaus. . Based on Eq. 2 and the new fallout arrival and cessation time estimates, granule diameter data for Utirik Island were determined. Using the assumption that the activity of a granule was proportional to the 3.5 power of the radius (La65), an activity versus granule diameter distribution was estimated for Utirik Island (see Fig. 5). The number of granules in each gran~ ule size class was based on Bikini Ash (Su56). The activity median diameter for fallout at Utirik Island was about 14.5 microns. fallout was not visible to the eye at Utirik. This agreed with the fact that The cumulative per cent of total activity deposited on the surface of Utirix Island (see Fig. 6) was estimated from Fig. 5 and Eq. 2. An adjustment for decay of each granule size class from the onset of fallout to the time of surface deposition was not made in order to generate Figs. 2, 4 and 6. The activity referred to in these figures was the ac- tivity which would have existed at the onset of fallout at each location. Cor- rection for decay leads to a slightly steeper rise (1~5%) in the cumulative per cent activity versus hours post BRAVO detonation at each location. Eighteen Rongelap people went to Sifo Island, Ailiginae Atoll to fish and make copra (Sh57). They left Rongelap Island prior to or about the time of the BRAVO detonation (Sh57). These people who went to Sifo Island, a few hours transit time away from Rongelap, were located about 150 km from the 13