Partial Loading of Thorium-Plutonium Fuel in a Pressurized Water Reactor

This research focuses on the utilization of thorium-plutonium fuel in pressurized water reactors (PWRs). The reference PWR selected in this research was the Westinghouse AP1000. Thorium-plutonium mixed-oxide (MOX) fuel assemblies partially replaced the uranium oxide fuel assemblies to reduce uranium demand. The cases studied contained 36, 48, 60, 72, and 84 thorium-plutonium MOX fuel assemblies, with the rest of the 193 fuel assemblies loaded with UO₂ fuel. The core cycle length, the amount of plutonium incinerated, the amount of generated ²³³U in the spent fuel, and the conversion ratios were determined using MCNP6. For the different cases, safety parameters such as the power peaking factor and delayed neutron fraction (β_eff) were evaluated. The study showed that using thorium-plutonium MOX can achieve good peaking power factors with delayed neutron fractions within the safety limits. Also a conversion factor of about 10% was achieved.