This manual provides a list of the quantities of plutonium and plutonium isotope formation. Other isotopes whose concentrations are important and included in this report are U-236 buildup, U-235 burnout, U burnout, Np-237 build-up, GVR (the Gas Volume Ratio) in coproduct target elements and equivalent gram of plutonium. These conversion tables have been calculated on the IBM 7090 digital computer using a program entitled ``FLEX-3.`` The results of the computer solutions have not been normalized to conversion observed by Chemical Processing Department measurement since none are yet available. Conversion ratios for four types of N-Reactor fuel have been evaluated, they are: (1).947 percent U-235 normal fuel loading; (2)1.25 percent U-235 ``spike`` enrichment; (3)1.25 percent U-235 outer, Li-Al inner -- coproduct fuel; (4)1.96 percent U-235 outer, Li-Al inner -- coproduct fuel.

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A Helios-propelled vehicle would make use of a containment vessel--perhaps 30 feet in diameter--in which small nuclear explosive charges would be placed, together with a few hundred pounds of hydrogen. Firing of a charge would result in bringing the mixture of charge residue and hydrogen to a high temperature--say 5000 or 6000/sup 0/K--and subsequent release through a nozzle would provide propulsive thrust. This process would be repeated several thousand times, at intervals likely to be 10 seconds or longer. High impulsive acceleration loads would be moderated by a system of shock absorbers between the engine and vehicle. The paper summarizes characteristic features of the concept, especially with reference to system optimization studies and analysis of heat transfer to the engine structure.