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.