Review of Canadian Experience with the Fabrication of Thoria-Based Fuels for Advanced Reactors and Fuel Cycles for Long-Term Nuclear Energy Sustainability and Security

Advanced fuels and fuel cycles are important for the current and next generation of advanced reactors, small modular reactors, and micro-reactors, in order to maximize the utilization of fissile and fertile nuclear fuel resources, and also to minimize the mass and volume of radioactive waste to be placed into long-term storage. Thorium-based fuels are a potentially attractive option for both advanced fuels and fuel cycles, with Canada having gained extensive experience over more than 50 years of how to fabricate thorium-based fuels.

This paper provides an overview of Canada's experience in the fabrication of thorium-based fuels (mainly ThO₂, (Th,U)O₂ and (Th,Pu)O₂) at Canadian Nuclear Laboratories (CNL), formerly Atomic Energy of Canada Limited (AECL), Chalk River Laboratories (CRL). Thoria (ThO₂) fuel pellet fabrication uses processes and equipment similar to that of uranium dioxide (UO₂) fuel pellet fabrication. However, since thorium lacks a fissile isotope, most ThO₂ pellet fabrication processes must include a step to add a fissile component, such as enriched UO₂, plutonium dioxide (PuO₂), or U-233 in the form of ²³³UO₂. Along with a review of the fuel fabrication effort that has taken place at AECL-CRL / CNL, the potential impact that AECL-CRL / CNL's extensive experience with thoria fabrication could have on the future Canadian nuclear energy landscape is also discussed.