Target fuels for plutonium and minor actinide transmutation in pressurized water reactors

Abstract

The average nuclear power plant produces twenty metric tons of used nuclear fuel per year, containing approximately 95wt% uranium, 1wt% plutonium, and 4wt% fission products and transuranic elements. Fast reactors are a preferred option for the transmutation of plutonium and minor actinides; however, an optimistic deployment time of at least 20years indicates a need for a nearer-term solution. This study considers a method for plutonium and minor actinide transmutation in existing light water reactors and evaluates a variety of transmutation fuels to provide a common basis for comparison and to determine if any single target fuel provides superior transmutation properties. A model developed using the NEWT module in the SCALE 6.1 code package provided performance data for the burnup of the target fuel rods in the present study. The target fuels (MOX, PuO2, Pu3Si2, PuN, PuUZrH, PuZrH, PuZrHTh, and PuZrO2) are evaluated over a 1400 Effective Full Power Days (EFPD) interval to ensure each assembly remained critical over the entire burnup period. The MOX (5wt% PuO2), Pu0.31ZrH1.6Th1.08, and PuZrO2MgO (8wt% Pu) fuels result in the highest rate of plutonium transmutation with the lowest rate of curium-244 production. This study selected eleven different burnable absorbers (B4C, CdO, Dy2O3, Er2O3, Eu2O3, Gd2O3, HfO2, In2O3, Lu2O3, Sm2O3, and TaC) for evaluation as spectral shift absorber coatings on the outside of the fuel pellets to determine if an absorber coating can improve the transmutation properties of the target fuels. The PuZrO2MgO (8wt% Pu) target fuel with a coating of Lu2O3 resulted in the highest rate of plutonium transmutation with the greatest reduction in curium-244 production.