S 7e Ge i (i. Spontaneous fission rates of Pu-2),0 and U-2%. Mr, Strauss had asked for GAC help on the classification of these matters. Dr. von Neumann asked whether the fact that the Russians probably know something is reason for declassification. Dr, Libby replied that as long as there is doubt we do not declassify. Dr. Sayth added that we weigh the advantages of declassification, The advantaces ef classification were discussed. Dr. Libby pointed out thet the Russians discovered spontaneous fission, the degree of conservatiam of te Senior Responsible Reviewers was discassed. Dr. Wiener expressed the opinion that in the thermomelear field, they had not been en the conservative side, Dr. Rabi said he felt the GAC sl.ould make no recommendation. He felt it extremely unlikely tiat the Russians could make plutoniwu without knowing about the spontaneous fission. He sould see no likely importance to Uo236. Mr. Strauss asked wiat were the advantages of declassification. Dr, Rabi replied thet the scientific tradition; and, Dr. hima said, supporting the senior reviewers were the advantages. Dr. Wigner said he had eoncluded tiat there was very little danger in the declassification of either matters, 8. The usual amenities were exchanged. DISTRIBUTION : MOQEME M, SUCKLRT Commi ssioner Mr, Strauss Dr. Sayth Mr, Murray oe t My, Willies SEST AVAILABLE COPY, DOE ARCHIVES 61