-h5~ and U-~-233, which is intermediate between Pu-239 and U-235 » can't do anything funny in a bomb, There was some. discussion, contributed to by Dr. Hall and Dr, Impurity Froman, about the neutron background, | Impurity specifications ‘would Specificabe about 5 times more rigorous than for production grade U-235. tions for U-233 On * the basis of U-233 in hand, which had been purified by the standard production processes, it appeared that the specifications could readily be met. Even if the impurity 73¥58 were 30.tinesthose specified, Dr. Rabi asked what wouta be the effects }yea by year if the program were started in the inmediate future, Mr. Quinn replied thats next January one Savannah reactor would be put on 0-233 production, nine months later a second, and then a. third, Oporatitons “would contirix with three reactors on U-233 and two on low 2/T plutonium, as controllec by the ‘separations capacity, _ /. 7 ~ Two years from now the thermonuclear requirement will be met by either schedule A or schedule B, and high g/T Pu. The main differences are in U-235 The present steps would be to approve duPcnt ‘planning and to commit $35 million late in the fiscal year for plant modifications and construction, The duPont peop7e anticipate no great diffi- culties. Dr, Rabi asked how upsetting it wouldbe if one had to reverse the program later. Mr. Quinn indicated the main thing would be the conversion of the Purex plant back to its original functions. Thorium Dr, Rabi asked about the supply of thorium ores. - Mr. Quinn in- ‘Supply “dicated that the emount now available-is sufficient for three years; DOEARCHIVES EF.