Costs for Manufacturing Thorium-Uranium Dioxide Fuels for Light Water Reactors

The results of a 2-yr effort to determine the capability of U.S. fuel manufacturers to economically manufacture thorium-uranium dioxide (ThO₂-UO₂) fuel in plants that have previously only manufactured UO₂ fuel with <5% ²³⁵U enrichment are presented. It was determined that there were no fundamental obstacles to converting the current plants that manufacture a uranium-oxide-only fuel to a mixed thorium-uranium dioxide fuel. However, the differential costs for manufacturing a 75% ThO₂-25% UO₂ fuel, with the uranium enriched with 20% ²³⁵U, as compared to a 100% UO₂ fuel, was between $269 and $291/kg of metal oxide fuel, depending on the manufacturing method used to convert the uranium and thorium feeds to the dioxide powders. More than 90% of this cost was associated with the increased cost of the uranium feed and the addition of the thorium feed. If a 70% ThO₂-30% UO₂ fuel were used, the differential costs would increase to between $519 and $542/kg of metal oxide fuel, of which >95% is associated with the uranium and thorium feed materials.