DOE$650.2,TAD - Bea Te VT EGS G # eae! TIE Dine. 4G Wilboe, SMA4-173 23 Novenbes19 49OYDick 412-89 Ved KOOGLEbi2 ovenbe -3) ; LiAfye ‘hd Carroll Wilson Atomic Energy Commission --» a= CONFIRMED To BE DOE/OFFIC UNCLASSIFIED ~ mmmanetL. KOLBAYaDOSS FICATION eS DATE:ling, 1903 Constitution Avenue Washington, D. ¢, Dear Mr, Wilson: The initial report on Project Gabriel by Dr. Nicholas M, Smith, Jr., dated May 21, 1949, the revised cony dated November 12, 1949 and a Top Becret letter from Drs. Latimer and Hamilton dated October 4, 1949, are BEST COPY AVAILABLE transmitted herewith. These reports have been checked by Drs. Teller and associates at Los Alamos, D& Latimer and Dr. Hamilton, Dr, K. 2. Morgan and Dr. G. Failla. Mr, Deal of our office has acted effectively as liaison officer | and has aided in the calculations. These reports as evaluated by the individuals mentioned and myself may be summarized as follows: material. (A) Limitation on numhets of bombs, 1. Plutonium and strontium” ments of importance. 0 By effects of ingested plus yttium”” 90 are the ele- 2. The particle size resulting from an explosion ranges from a few nicra in diameter downward with a higher proportion of the very fine particles as the cloud gets farther away from the point of burst. 5. 3%. The debris from a single air burst is expected to settle out almos|/entirely in a path of 700 to 800 miles. Assuming that the cloud is 500 miles wide, the average density of material deposited per square mile normalized to 1 gram of original bomb debris is 3 x 107 grans per square mile. 4, . Owing to the prevalent atratospheric winds, bombs detonated on the West Coast would largely thus effect only the arid moun- tain regions: bombs detonated in the Middle West would also involve the East Coast; and Bast Coast bombs would essentially be ineffective as regards fall-out due to deposition of the bulk of material in the ocean. 5. If one assumes a local fall-out area to measure DO’ ARCHIVES I