PF 3.3.2 Shot 1. The data gathered by the Bikini Atoll surveys and collectors were supplemented by surveys performed on the atolls that were unexpectedly contaminated. The major portion of the pattern, which occurred over the open ocean, was not documented. However, an analysis of the wind structure during the iallout period was performed; this TABLE 3.1 AREAS OF AVERAGE RESIDUAL GAMMA ACTIVITY Shot 1 Aros Average Residual Gamma Activity* mi? r/or at H+ Lor 2,040 3,000 2,680 2500 3,869 1,600 6,030 750 12,900 300 *See WT-915, Appendix F. analysis, combined with the available data points, produced the pattern exhibited in Figure 3.5. The time of arrival of fallout at the Bikini Atoll stations was between 15 and 45 minutes after detonation. Statements from persons accidentally exposed on downwindatolls indicated an arrival time of 8 hours on Rongerik Atoll (at a distance of 126 nautical miles) and of about 18 hours at Uterik Atoll (300 nautical miles). The data from two measure- “Meas amar “TOU oeee = a mz ‘VGN ATOLL CQurnens ator, ee vis cocoma @ Tamas CTL. 006 LALA MATICAL ES oo -s 2 Oo © © © OH Figure 3.5 Reconstructed complete fallout pattern, Shot 1, (r/hr at H + 1 hour). ments of residual gamma versus time at nearby stations are presented in Figure 3.6. The decay exponents estimated from these graphs are between 1.1 and 1.4 for Station 220.12, and 0.81 for Station 220.08. (Decay exponent is defined as x in the relation for exposure rate I =I, ¢™*, where t is the time. ) Table 3.1 presents the data on contour areas. ws From this, a rough activity-balance ff oO