Static and Dynamic Neutronics Analysis of a Bimodal Gaseous Core Reactor System for Space Power

Gaseous core reactor (GCR) neutronics and energetics research efforts at the University of Florida (UF) have indicated that the gaseous core class of nuclear reactors have attractive features for space electric power and propulsion applications compared to conventional solid-fueled nuclear reactor systems. The high temperature of the working fluid of GCR's, which can be considerably higher than the surrounding structure, is advantageous to both power cycle efficiency and heat rejection in space. The gaseous nature of the fuel gives the added advantage of rapid startup capabilities and the simple core structure geometry helps minimize the thermal shock and thermal stress especially during rapid startup. One of the GCR concepts investigated at INSPI is a bimodal gaseous core reactor (BGCR) which consists of a large, central cylindrical high (burst) power gaseous core reactor (BPGCR) chamber surrounded by an annular ring of cylindrical, low power pulsed gaseous core reactor (PGCR) chambers embedded in Be or BeO moderator/reflector. Static and dynamic neutronic behavior of the BGCR power system has been examined for various core and moderator region dimensions and for various fuel loadings. Optimization of region dimensions and core loadings on, the basis of static and dynamic neutronic performance for the BGCR has been completed.