PTA OIC2 On the other hand, there are healthy indications that the capability of the aircraft reactor team at ORNL 1s improving. It was especially heartening to learn that a picked group of experienced engineers from the K-25 plant has no bee me recently joined the project. The infusion of this group may well step up the pace, contribute practical resourcefulness and decision, and hasten the effective blending of ORNL and P&W efforts. In our judgement this program is in a critical state where every effort should be made to determine quickly whether the Fluid Fuel approach is a reasonable gamble to pay off in an operable propulsion system for aircraft within the next eight years. Oak Ridge, aided by P&W, should be the most competent group to establish the foundation for this appraisal. We suggest that a thorough review, directed tewards a decision to continue or to modify the approach, be held in about six months. By this time, the augmented staff at ORNL should be familiar with the critical problems and the prospects of sey tw ew at to ae eredoeSe “solvingthemandthe P&W people should be well integrated into the project. Furthermore, the call for such an appraisal in the near future would itself hasten the unification of various elements towards an agreed objective. Heterogeneous Sodium-Cooled Reactor Nuclear Development Associates has made a paper study of a sodium-cooled aircraft reactor using fuel pins of the SIR type, in a 43-inch beryllium right cylinder and with a central beryllium island. Their design uses very high velocities for the sodium coolant and assumes 5% burn-up on a 250-hour oycle. A heterogeneous reactor looks reasonable as an embodiment of the liquid sodium cycle in an aircraft reactor and it may be desirable to initiate active development in the near future. ae