Californium-252 production at the High Flux Isotope Reactor - II: Comparison between the highly enriched uranium and a proposed low-enriched uranium core

This is the second paper on a ²⁵²Cf production study performed in support of efforts to convert the High Flux Isotope Reactor (HFIR) from highly enriched uranium (HEU) to low-enriched uranium (LEU) fuel. The first paper primarily focuses on validating computational tools and nuclear data. This companion paper evaluates another critical aspect: the ²⁵²Cf production capability with a proposed LEU core. HFIR must maintain its world-class performance and missions following conversion and because ²⁵²Cf is a vital, multipurpose neutron-emitting radioisotope, the ability to efficiently produce ²⁵²Cf must be preserved. In this study, the HFIRCON transport and depletion tool, several nuclear data libraries, and Campaign 78 data were used to compute ²⁵²Cf production, sensitivity, and safety metrics. Results indicate the ²⁵²Cf production and production rates are slightly higher with a 95 MW_th LEU core compared with those obtained with the 85 MW_th HEU core. Additionally, the target peak fission rate densities, discharge cumulative fission densities, and heat deposition rates with the LEU core are within a few percent of those calculated with the HEU core. The findings suggest HFIR’s ²⁵²Cf production capability can be effectively maintained with an LEU core without adversely affecting the safety metrics.