ANEEL, a new nuclear fuel made by combining thorium and enriched uranium, has successfully completed a multiyear irradiation test at the Advanced Test Reactor in the US. Developed by Clean Core Thorium Energy (CCTE), the fuel achieved more than 60 GWd/MTU of burnup, exceeding the typical discharge burnup of conventional nuclear reactors by more than eight times. 

Nuclear energy is poised for a major comeback as countries seek to meet rising energy demands while reducing carbon emissions. Since conventional nuclear power plants take years to build, startups have also been looking at smaller, modular reactors, which can be built quickly and at scale. 

Chicago-headquartered CCTE, though, is taking a different approach, aiming to repurpose existing nuclear reactors with an entirely new fuel technology, ANEEL. Thorium is considered a better nuclear fuel alternative because it is abundant and produces less radioactive waste than uranium. CCTE’s ANEEL aims to deliver the advantages of both thorium and uranium while extending the operational life of existing reactors, such as pressurized heavy water reactors (PHWRs). 

Irradiation test for ANEEL

The Advanced Test Reactor at the Idaho National Laboratory in the US provides a test bed for new fuel technologies. The ATR can generate compact, high-flux irradiation conditions at an accelerated pace to simulate extended reactor operation to evaluate fuel behavior. 

In May 2024, 12 ANEEL rodlets were loaded into the ATR to reach target burnup rates of 20, 40, and 60 GWd/MTU. Last year, eight of these rodlets completed the first two burnup targets, and the last set is now approaching the highest burnup target. This is designed to generate real-world performance data for the fuel under reactor conditions. 

Following a short cooling period, the rodlets are then transferred to INL’s Materials and Fuels Complex (MFC) for post-irradiation examination (PIE). The eight rodlets removed last year are currently undergoing PIE, which also provides details on the fuel microstructure and performance at high burnup levels. 

What happens next? 

The PIE results obtained so far have shown that ANEEL fuel performs well, maintaining structural integrity and favorable fission gas retention throughout irradiation. 

“Surpassing 60 GWd/MTU of burnup in the Advanced Test Reactor marks an important milestone for the ANEEL fuel program,” said Mehul Shah, CEO of Clean Core Thorium Energy, in a press release. 

“This irradiation campaign provides meaningful performance data and demonstrates that thorium-HALEU fuel can achieve burnup levels comparable to those seen in PWR fuels while offering improved fuel utilization, enhanced safety characteristics, inherent proliferation resistance, and meaningful reductions in long-lived nuclear spent fuel radioisotopes.”

ANEEL fuel retains the geometry of existing fuels, such as 19- and 37-element designs used in PHWR and Canadian Deuterium Uranium (CANDU) reactors. This facilitates integration into existing reactors without any modifications to core design or systems. 

“Our objective has been to introduce thorium into the nuclear fuel cycle in a practical way using existing reactors, and this milestone represents a significant step toward that goal,” added Shah in the press release. 

With PIE underway for its rodlets, CCTE is working on its next milestone – demonstration of ANEEL fuel in a commercial power reactor, which will pave the way for its commercial entry. CCTE will work with INL and other industrial partners as it looks to power more nuclear reactors in the future.