Co, om “7~ me up through the holes and also between the hexagon faces, There is some encouraging information on fuel elements which indicates that a burn-up of 4000 megawatt days per ton is already attainable. NAA's Shte one ot predictions on economics generally assume 6000 to 7000 — they believe that such burn-ups are approaching an economic asymptote, Vee wee We agree that the sodium-graphite reactor is in a relatively advanced stage of development. The 20 MW pilot plant is apparently big enough to answer questions of engineering feasibility and of the probable economics of a large commercial unit » and the development program which NAA hopes to prosecute on it seems generally sound, The present commitments for financing development ' work for the SRE design and especially during its subsequent operation seem somewhat inadequate and might well be increased, - - _~-,We-see-no_sound technical reason for now telescoping a larger version of So gD eee pa the Sodium-Graphite reactor on the present 20 MW experiment. However, if another large demonstration reactor should be deemed essential at this time, we believe that the Sodium-Graphite approach is the most suitable candidate today. It would incorporate large-scale sodium technology in a commerical power enterprise. It is predicated on a considerable background of reactor experience and detailed design studies and should, therefore, present fewer highly questionable unknowns than most other possible competitors. In our judgement it is technically the most instructive approach which could result in an operating plant within the next five years. eee OS meATTY Be e po Ba ae