Clean Core Thorium Energy advances thorium fuel testing for Candu reactors

Clean Core Thorium Energy has taken its ANEEL thorium and HALEU fuel closer to the reactor door by signing an agreement with Canadian Nuclear Laboratories to manufacture demonstration irradiation bundles at Chalk River, Ontario. The bundles are meant for pressurized heavy water reactors and Candu units, giving the program a real path into a deployed reactor class instead of a paper design.

That matters because ANEEL is being pitched as a drop-in replacement for the natural-uranium bundles already used in heavy-water systems. Clean Core says the fuel keeps the same external dimensions and configuration, which is the key promise for utilities that want advanced fuel without major reactor hardware changes. If the fuel performs as intended, the payoff could be lower lifecycle operating costs, smaller waste volumes, better accident tolerance and stronger proliferation resistance while still using existing reactor infrastructure.

Canadian Nuclear Laboratories will do more than help shape the bundle design. Under the agreement, CNL will lead development, qualification and manufacturing under Canadian Standards Association requirements, a step that moves the fuel deeper into the licensing and acceptance process. The company and CNL first established a framework for that work in 2023, when they signed a strategic partnership MOU covering research, development and licensing support for ANEEL.

The next major proving ground is in the United States. The demonstration bundles are slated for testing in Idaho National Laboratory’s Advanced Test Reactor, where the program is targeting burnup above 60 gigawatt-days per metric ton of uranium. That test campaign is the point where ANEEL stops being a claim and starts generating the in-reactor data that regulators, utilities and fuel buyers will care about.

Regulatory work has already begun. Clean Core said in 2024 that it had completed the first phase of the Canadian Nuclear Safety Commission’s pre-licensing review, and Idaho National Laboratory later described the fuel as a thorium-uranium form for CANDU and PHWRs that could reduce waste, improve safety and lower costs. INL also said that, once qualified, ANEEL could reach roughly 6 to 8 times the burnup of traditional natural-uranium fuel. Clean Core’s earlier expectation that ANEEL assemblies could enter commercial Candu reactors by the end of 2025 now reads as a marker of how aggressive the rollout has been, even as the real commercialization work shifts to manufacturing, irradiation testing and qualification.