Effects of Fuel Enrichment on the Physics Characteristics of Plutonium-Fueled Light Water High Converter Reactors

Investigations have been carried out for three additional cores of the phase 1 experimental program on light water high converter reactor test lattices in the PROTEUS facility. An 8% (average) fissile plutonium tight-pitch lattice with a fuel/moderator volumetric ratio of 2.0 was considered, ,4s for the earlier reported 6% (average) fissile plutonium test lattice, H₂O, Dowtherm, and air were the moderator states investigated. Significant enrichment-dependent trends have been identified in the comparisons of calculated and experimental results for the wet (moderated) cases, particularly for the important reaction rate ratio of ²³⁸U capture to ²³⁹Pu fission. These are then reflected in the comparison of moderator voidage characteristics, expressed in terms of individual components of the k_∞ void coefficient.