PS Cr Ce eeeenes te The initial loading requires approximately 150 kg of U-235 at 15% 1 enrichment. If loaded with plutonium about 90 kg are needed, alloyed with U-238. The first charge which uses plutonium will probably be a combination of Pu and U~-235. The design objective 4s 2% burn-up on a 135-day cycle, with a maximum fuel temperature of 1200°F, “| of Maximum sodium coolant temperature is 500°F, “| The current schedule for EBR-II is as follows: Mock-up built by end of 195k. Calculations and experiment to July 1955, at which time the Architect-Engineer comes in and plant design starts. Building construction begins at Arco April 1956. Reactor ready for initial operations January 1958, Fast exponential experiments are being pushed concurrently and Argonne “4 = _..... is. building a critical assembly. rn aT Rat BeRLoe Se ee In assessing the Fast Breeder program and possibilities, we were impressed by the difficulties and uncertainties ahead. The promise of true breeding inherent in this approach to commerical power justifies strong development effort, and we approve the Argonne program although we feel that its current schedule may be overly optimistic. The Fast Breeder offers Little hope for early success in making competitive power ~- rather, it seems to be a long- range prospect for the time when other nuclear power plants are short of fissionable material and may be looking for the most efficient uses for the plutonium which they produce, This conservative view should by no means obscure recognition of the great advances in the reactor art resulting from Argonne's past and continuing enthusiasm for the Fast Breeder.