Critical mass analysis for {sup 235}U and {sup 239}Pu systems moderated and reflected by D{sub 2}O

Abstract

Criticality dimensions for highly enriched {sup 235}U(93.5) and {sup 239}Pu(95.5) systems mixed with D{sub 2}O were studied. The objective of this work is to investigate the minimum critical mass and concentration of uranium and plutonium systems in a reflector-moderated arrangement. The present work demonstrates the critical instability of these systems that are moderated and reflected by D{sub 2}O and expands in previous unpublished work. These calculations were performed in a spherical geometry with the DANTS codes using the Hansen-Roach cross section library. Densities examined ranged from normal to very small, and are assumed to be uniform throughout the core. These spherical systems are reflected by 100 cm of D{sub 2}O.