(a) The native atolls in the southeast quadrant, particularly those in-the northern portion of the quadrant, were in a less favorable position for high yields than previously supposed, the degree of favorability dopending upon the yield, initial wind conditions, shot site (barge, land, air) conditions, and the proximity of the air particle trajectories to a west-east Line, , (b) Shot decisions should be reached only after consider~ ing the impact of an air particle trajectory analysis over a period of tine and space sufficient for significant fall-out to occur. Initially, C.STLE planning factors in this regard were twenty-four hours amd 500 nautical miles as the upper limits beyond which no significant hasard should exist, ‘for the hasardous phase of fall-out, the significant portion considered was the RET plot. (using ground sero winds) anc the forecast air particle trajectories for the first twelve hours, Subsequent to BRAVO the RiDEX was augmented by a new technique developed to plot the fall-out pattern over a period of twenty-four hours using the forecast air particle trajectory analysis revised progressivel as the forecast cloud: segments moved cut of the vicinity of ground zero (See TabD), © tere ee (ce) Of the contamination arriving ot the native atolls in the southeast quadrant, some fell on the islands, whereas seme umtoubtedly remained in the moving air mass passing cover the idiants, This phencmens appeared, from various observations, to be more persistent in time and space for barge shots than for land shots, (ad) Since the mean free path of gamma in air is something on the order of 2,000 feet, an appreciable slice of the air mass is involved in "shining" on the islends. This contribution, estimated to account for as mich as 50 percent of the dose rate experienced by the inhabitents during 30