Effect of Alloying on the Critical Mass of a Plutonium Spherical Fast Reactor

The effect of alloying on the amount of plutonium required in forming a critical mass of each alloy has been expressed in terms of an inventory requirement ratio, R_I. This quantity was obtained for twenty-seven potential alloying elements at three compositional levels. The effectiveness of using Vegard’s law to estimate the density of the alloys was appraised by comparing the estimated densities and R_I values of nine intermetallic compounds with their x-ray densities and the R_I values computed from them. The parametric variation of R_I with f_T, the number of excess neutrons per collision was also studied.