llc - a of 4 ae , @ im ~5= y f vraft letter to Military Liaison Committee: 1. The Comission has determined that data in the attached table on total strontium-90 produced in U. 5S. nuclear weapons operations will not reveal weapon design information. 2. However, it would be possible to derive, using an average fission yield for Sr-90, an approximate_total fission yield for each test operation in terms of detonationswithtotal energy yields of less than 1 megaton and those with total. energy yields of greater than 1 megaton. The total fission yield for all operations thus derived from the data in the attached table is approximately 46 megatons. This is more accurate than the 50 megaton fission yield figure presented in the Joint Committee on Atomic Energy Hearings of June 5-7, 1957 on "The Nature of Radioactive Fallout and its Effects on Man", «° 3. The Commission believes that the release of the information on strontium-70 production in U. S. nuclear detonations as presented in the attached table will permit a more accurate evaluation by the scientific public of the radioactive hazards from world-wide fallout on strontium-90. 4. Since the data in the attached table will reveal more accurate information on the total fission yield of each U. S. nuclear weapons operation than has previously been published, we would appreciate the Department of Defense comments and/or concurrence on the possible publication of this information. Attachment: As stated above.