Feasibility Study of Thorium-Plutonium Mixed Oxide Assembly In Light Water Reactors.

Area of Science:

• Nuclear Engineering
• Reactor Physics
• Materials Science

Background:

• Thorium-plutonium mixed oxide ((Th,Pu)OX) is an alternative nuclear fuel.
• Current research focuses on optimizing thorium fuel integration for enhanced reactor performance.

Purpose of the Study:

• To evaluate the impact of thorium introduction methods on neutron parameters in light water reactors.
• To assess the benefits of thorium fuel, including extended cycle length and plutonium stockpile reduction.

Main Methods:

• Modeling three fuel assemblies using MCNPX: reference uranium oxide, (Th,Pu)OX, and homogenized thorium-plutonium oxide.
• Comparing effective multiplication factor, isotopic inventories, B-10 depletion, and power distribution at various burnup levels.

Main Results:

• (Th,Pu)OX fuel exhibits similar multiplication factor evolution to UOX fuel, despite a lower initial K-eff.
• Improved power flattening is observed in (Th,Pu)OX fuel assemblies.
• Significant reduction in Pu-239 mass observed by end-of-life for both (Th,Pu)OX configurations.

Conclusions:

• Thorium-based fuels offer advantages in reactor operation, including power flattening and potential for reduced plutonium content.
• (Th,Pu)OX fuel demonstrates favorable characteristics for light water reactors, with strategies like burnable poisons to manage power peaking.