Lattices of Plutonium-Enriched Rods in Light Water—Part I: Experimental Results

Abstract

Results of experiments conducted in the Critical Approach Facility are presented for a total of 48 lattices of plutonium-enriched rods. Five kinds of UO₂-PuO₂ rods ranging in PuO₂ enrichment from 1.5 to 4.0 wt%, and three kinds of Al-Pu rods ranging in plutonium enrichment from 1.8 to 5.0 wt%, were used in the experiments. The lattices covered a broad range of water-to-rod volume ratios. Parameters reported for each lattice are: the number of rods required for a critical loading, the relaxation length measured in an exponential loading, the critical buckling, and reflector savings. For five of the lattices results are also reported of the worth of central absorber rods of boron and hafnium. The results of approach-to-critical experiments were verified by comparing them with the results of critical measurements conducted in three lattices.