THORIUM FUEL UTILIZATION IN THE BWR:LATTICE PHYSICS ANALYSIS OF REACTIVITY COEFFICIENTS

摘要

Although there has been considerable research into the Thorium fuel cycle for Light Water Reactors, the reactivity coefficients have not been studied extensively. The work reported here is a systems level lattice analysis in order to provide an assessment of Thorium performance in a Boiling Water Reactor. Several Thorium fuel assemblies were designed in an oxide fuel matirx with one of three fissile materials: 20 wt% enriched U-235 oxide, reactor grade Plutonium, and U-233, which was assumed to be reprocessed. Results indicate that it is possible to achieve comparable burnup behavior and pin powers with Thorium fuel compared to Uranium oxide fuels. However, significant differences were observed in the reactivity coefficients for each fuel type. Each of the Thorium fuels had either too negative or slightly positive Coolant Void Reactivity (CVR) coefficients, and the control rod worth and the Doppler coefficients were more negative in all cases. A second stage of the analysis was performed which considered changes in the fuel geometry and some improvements were achievable in the reactivity coefficient performance.