CCTE’s ANEEL fuel successfully reached more than 60 GWd/MTU of burnup in the INL’s Advanced Test Reactor, marking the completion of a multiple year irradiation test and validating the potential of the thorium-HALEU fuel cycle 

ANEEL fuel rodlets undergoing Post Irradiation Examination at INL’s Hot Fuel Examination Facility

CHICAGO, May 05, 2026 (GLOBE NEWSWIRE) -- Clean Core Thorium Energy (CCTE) announced today a major milestone for advanced fuels: its patented ANEEL fuel has completed its high burnup irradiation test in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL). The final set of irradiation capsules have achieved more than 60 GWd/MTU of burnup, representing more than eight times the typical discharge burnup of traditional pressurized heavy water reactors (PHWRs) and Canada Deuterium Uranium (CANDU) reactors. This testing highlights the potential of ANEEL fuel to dramatically improve fuel utilization in existing reactor fleets and paves the way for near term commercialization.

The significance of higher burnups derived from ANEEL fuel translates to several operational benefits when integrated with the existing reactor design: reduced nuclear spent fuel volumes, improved reactor economics, enhanced safety performance and improved proliferation resistance. The irradiation results build on decades of global research into thorium fuel cycles to improve fuel utilisation and resource efficiency in existing heavy-water reactor fleets without reactor modifications.

The ATR irradiation campaign involved twelve ANEEL fuel rodlets that were loaded into the reactor in May 2024 and designed to reach three burnup targets: 20, 40, and 60 GWd/MTU. Eight rodlets exceeded the first two burnup targets last year and are currently undergoing post-irradiation examination (PIE) at INL’s Materials and Fuels Complex (MFC). Less than two years after irradiation began, the remaining four rodlets have now reached the highest burnup target, over 60 GWd/MTU, and will be transferred to MFC following a short cooling period. The irradiation campaign represents an important step in generating real-world performance data for ANEEL fuel under reactor conditions. Results obtained during PIE will provide detailed insight into fuel behaviour, microstructure, and performance at high burnup levels.

Due to its compact, high-flux nature, irradiation conditions in the ATR are typically more aggressive than in a PHWR. This allows fuel behaviour to be evaluated under accelerated conditions that simulate extended reactor operation. PIE results obtained to date are consistent with findings reported in the literature and suggest that ANEEL fuel performs well, with some test rodlets exhibiting superior fission gas retention compared to traditional UO₂ fuel. Initial observations also show that ANEEL fuel maintains structural integrity and favorable fission gas retention behaviour throughout irradiation.

Radiography image of several irradiated capsules showing fuel integrity

'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. “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. 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.”

“This final portion of the irradiation experiment has been several years in the making and I congratulate Clean Core on their major accomplishment. This has been an exciting project to support, and I’m eager to see what can be learned from the upcoming high burnup sample PIE results.” said Kelley Walker, principal investigator for the CCTE irradiation campaign at INL.

With the ATR irradiation complete and post-irradiation examination underway, CCTE is already planning its next milestone: a demonstration irradiation in a commercial power reactor that will move ANEEL fuel from proven test concept to commercial reality. The company will continue to work with INL and industry partners in support of a cleaner, more efficient global nuclear fleet.

About ANEEL Fuel

ANEEL is the CCTE’s patented nuclear fuel technology combining thorium with enriched uranium. The fuel retains the same external geometry as existing fuel for PHWR and CANDU reactors, including 19- and 37-element designs. This allows for integration into current reactor fleets without modifications to reactor systems or core design. ANEEL is designed to achieve higher burnup and improved fuel utilisation, with the potential to reduce spent fuel volumes per unit of energy generated and strengthen proliferation resistance.

About Clean Core Thorium Energy 

Clean Core Thorium Energy is a nuclear fuel company exploring thorium-driven nuclear innovations. Clean Core’s patented nuclear fuel technology (called the ANEEL fuel) is comprised of thorium and enriched uranium (LEU+ to HALEU), which is capable of improving the safety and cost-efficiency of pressurized heavy-water reactors. The ANEEL fuel is a novel solution to safety, waste, and proliferation concerns in today’s nuclear plants. 

Learn more at https://cleancore.energy/. Follow us on social media: LinkedIn and X.

About Idaho National Laboratory

Battelle Energy Alliance manages INL for the U.S. Department of Energy’s Office of Nuclear Energy. INL is the nation’s centre for nuclear energy research and development, and also performs research in each of DOE’s strategic goal areas: energy, national security, science and the environment. For more information, visit www.inl.gov. Follow us on social media: Facebook, Instagram, LinkedIn and X.

Contact:

Milan Shah
Chief Operating Officer
info@cleancore.energy

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