tein - = UNCLASSIE He p pridences of Atmospheric Storage in Fal-out Data ST In Figure 13 are plotted the mean daily fallout, during the latter half of 1953, st 2h etations operated in various parts of the world. data ought to be found in Tabis 13. The individual the rate of fallout in late June is largely from UPSHOT-XNOTHOLE. The will be noted that the sharp deciine which began in mid-Septenber apgears to rise in late August is doe to the test series then in progress in USSR. se continuing in late December. sharp It Further studies will be required in order to satisfactorily identify] the test series that contribute to this lay level deposition. As noted Barlier, the recent debris is considerably enriched in both isotopes of stromian and the gredmal accretion of these isotopes during the coming month is iikely te be larger in amount than the strontium that has been depogi ted up to the present time. Estimate of the Total Deposition of Debris from MIKE The Rand SUNSHINE group has estimated that lese than 1% of MIKE debFis could be accounted for during the period November 1 to December 31, 1952.7 Our estimate, derived independently, is about Lf. The discrepancy is understandable in view of the arbitrary decisions that mst be made in polating the data over large ocean areas vhere no measurements werd Snternade. From January 1 to March 1, 1953, we can account for an additional ¢.4&% (O.01L&%per week). In the following months, the debris was dominatad by the OPSHOT-KNOTHOLE and USSR series, and differentiation of MIKE dbbris was not possible by our metbods of sampling and analysis. 4 for fallout activity equivalent to a depesition of 0.35% of the reaid. 1 activity from MIXE. This is of the order of 0.1% per week and as noted frou igure 13 the decline in activity appears to be continuing. We cdnnot at this time aay that the activity currently observed is dus to MIKE and not from more recent detonations in this country or abroad. Howeper, if we do assign it to MIKE, we conclude that at most we can account Por only an additional fraction of a percent of the debris from this detonation. Estimate of Fature Pallout, Based on Atmospheric Samples Based on the few data available, we would estimate the activity af the atmc- sphere up te 100,000 feet to be of the order of .0 d/min/m) (.082 d/ain/ft2). Approximately 10% of this activity appears to be Sr°9, Tf all of thia activity is to be deposited on the sarth's surface in a time which short in Telation to the half life of Sr?0, the deposition would be of order of 20 d/min/sq. ft. This is an amount which is equivalent to the 979 deposited by all detonations up to the mresent in mst of the United Ststds. yz =" eo. oe Bam: vl ReaRig gece . ~ Be a ,- During the period of Movember 16 to December 13, 1953, we accoun - - 37 - 10570549 oo — 00131986 040 7