Nuclear fuel company Clean Core says its thorium fuel cracks, swells less than uranium fuel

Clean Core, a Chicago-based nuclear fuel company, revealed that its advanced thorium-based fuel, ANEEL (Advanced Nuclear Energy for Enriched Life), exhibited significantly less cracking, fuel restructuring, and swelling compared to conventional uranium dioxide (UO₂) fuel during post-irradiation examinations at the Idaho National Laboratory’s Materials and Fuels Complex.

ANEEL is a combination of thorium and high-assay low-enriched uranium (HALEU), a form of uranium with a higher concentration of uranium-235 than conventional low-enriched reactor fuel. The company is developing this fuel for pressurized heavy-water reactors (PHWRs). The research findings come from post-irradiation examinations of a medium-burnup batch of ANEEL fuel pellets after irradiation in INL’s Advanced Test Reactor.

The ANEEL pellets achieved a burnup of over 45 gigawatt-days per metric tonne of uranium (GWd/MTU), indicating the amount of energy extracted from the fuel during irradiation. Additionally, the fuel pellets demonstrated favorable thermal-mechanical behavior under irradiation, with a volumetric power density of around 1,500 W/cm³ and a neutron flux of approximately 5 × 10¹⁴ n/cm²·s.

Following irradiation, the fuel rodlets were transferred to INL’s Hot Fuel Examination Facility for non-destructive and destructive examinations. The results indicate a lack of gross fragmentation or adverse fuel-cladding or pellet-pellet interaction, as well as limited fuel restructuring and swelling, which provide encouraging evidence of favorable thermal-mechanical behavior under irradiation.