Assessment of the material attractiveness and reactivity feedback coefficients of various fuel cycles for the Canadian concept of Super-Critical Water Reactors

The attractiveness for weapons usage of the proposed fuel cycle for the PT-SCWR was evaluated in this study using the Figure-of-Merit methodology. It was compared to the attractiveness of other fuel cycles namely, Low Enriched Uranium (LEU), U/Th, Re-enriched Reprocessed Uranium (RepU), and Pu/Th/U. The optimal content of natural uranium, which can be added to Pu/Th to render the produced U-233 unattractive, was found to be 9%. A ranking system to compare the attractiveness of the various fuel cycles is proposed. RepU was found to be the most proliferation resistant fuel cycle for the first 100 years,while, the least proliferation resistant fuel cycle was the originally proposed Pu/Th one. The reactivity feedback coefficients were calculated for all proposed fuel cycles. All studied reactivity coefficients have the same sign implying that all the fuel cycles will behave neutronically in a similar way. The Pu/Th/U fuel was found to have the most negative value of the Coolant Void Reactivity which will help to restore the core to a safe status faster in case of a loss-of-coolant accident. The fuel and moderator temperature coefficients did not show significant differences between the fuels studied.