| 0018933 fallout. On the reef shot it appears that the sampling planes were just entering the base of the cloud at the 55,000 foot level since there is a sudden jump in the R-values at this point. The material collected at lower altitudes is depleted in both Sr?° ana csl37 and is not greatly different in composition from the fallout at 1000 feet. It is also noted that the enrichment factors for both nuclides go through a maximum with time for the samples from the light and variable stratum. This might be interpreted as indicating a concentration on particles of some size . intermediate between the early and late fallout from this region, Somewhat similar data for the Mo?99-to-Kr 88 and Kr 88 2 to- Kr 85 ratios for the first four hours following detonation are given in Table 3,4, Mo?? to Kr®8 ratios are also shown graphically in Figure 3,4. The At the lower altitudes the Mo’? is enriched and the Kr 8 depleted with respect to Kr85, 3.1.2 Fallout Data, The radiochemical data on the fallout samples may he used to obtain results for the distribution of Sr° 90 and C8137 which are complementary to those found from the cloud analyses. The fraction of the total Mo?? formed in the explosion which has left the cloud is found by difference from the numbers given in Table 3.2. Multiplication of these figures by the sr?° and Cs!37 R.values for the fallout and division 78 ; SAN BRUNO ERE 78