otner shots having the sam order of mgnitude arrived at al). sampling stations during the first hour after the detonation. Extrapolation of the beta activity indicated rates as high as 1.3x1014 d/min,1 to 6 minutes after the detonation. Cumilative residual activity levels, which are calculated values reflecting the activity arriving during an interval as well as the decay of residual activity deposited in previous intervals,are also shown in Figures 3.5 to 3.17. The cumulative activity levels indicate that if personnel were in such areas of fallout at later times, they would generally not be subject to an activity level and also a doso rate greater than that which existed at the beginning of falloute These results are considered to exclude the small percentage of activity with energies below 0.4 Mev; also, all activity detected is considered a primary beta particle. Tha results also do not in~ clude gamma activity in the fallout; it can be assumed that such gamza activity will be roughly proportional to the beta activity. In general, most of the activity had arrived at a given station within 3 to 6 hours after the detonation, with small amounts continuing to arrive up to at least 12 hr after the detonation. Any fallout occurring at a station 12 hr after a detonation is, in general, not reflected in the IFC activity results. It is known, for example, that light fallout occurred on the Obce-Tare chain the night after Shot 2. It is possible that such fallout may have ar= rived elsewhere at the atoll both after Shot 2 and after the other shots; however, such fallout at late times should generally be minor. There is a possibility that some of the activity collected during tne later time intervals had reached the ground during earlier times and was redistributed by the wind. It is also possible that the shock wave from a detonation wuld also raise fallout from earlier shots off the ground. This fallout could then be redistributed by the wind. Such an effect was quite possible on the Dog=George chain after Shot 2 and possible at both other Shot 2 stations and after Shot 4 at all stations. It is believed that this effect from Shot 3 is remte because of the low yield of the device which would produce correspond= ingly low shock waves. Shots 1 and 6 locations and sampling stations were in essentially uncontaminated locationa. 30402 Cloud Action Based upon Cloud Photography and Wind Vectors Project 9.1 photography indicated that the Shot 1 cloud ex- panded horizontally very rapidly during the first few minutes after the detonation; it was 7.2 miles in diameter 1 min after the shot and 70 miles in diameter 10 min after the shot .13/ Such rapid expansion may be the reason that fallout was observed so soon after the detona- tion. The fallout intensity was greatest at the downwind stations on the north and east sides of the shot atoll. As would be expected from observing the wind vectors for Shot 1 (Appendix B), fallout was much less intense at the cross-wind stations. The clouds and/or stems from Shots 2, 4 and 6 spread almost as rapidly as the Shot 1 cloud, 13/ but the wind vectors existing dur~ ing Shots 2 ami 6 (Appendix B) precluded the“possibility of much sig50