ANEEL – its name is taken from Advanced Nuclear Energy for Enriched Life – has been developed for use in pressurised heavy water reactors (PHWRs) and Candu reactors. Clean Core Thorium Energy says it can offer significantly improved performance with existing proven heavy water reactor systems by leveraging thorium’s “inherently superior” nuclear, thermal and physical properties while retaining the same external dimensions and configuration design as in currently used natural uranium fuel bundles. The fuel retains the same external geometry as existing fuel for PHWR and Candu reactors, including 19- and 37-element designs. It can be used to replace current fuel bundles, without any significant modifications to the reactor, to reduce life-cycle operating costs and waste volumes, increase safety and accident tolerance, and result in additional proliferation resistance, the company claims.
The Advanced Test Reactor 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 Idaho National Laboratory’s (INL’s) Materials and Fuels Complex. Less than two years after irradiation began, the remaining four rodlets have now reached the highest burnup target, over 60 GWd/MTU – representing more than eight times the typical discharge burnup of traditional PHWRs and Candu reactors – and will be transferred to the Materials and Fuels Complex following a short cooling period.
“The irradiation campaign represents an important step in generating real-world performance data for ANEEL fuel under reactor conditions,” Clean Core Thorium Energy said. “Results obtained during PIE will provide detailed insight into fuel behaviour, microstructure, and performance at high burnup levels.”
It added: “This testing highlights the potential of ANEEL fuel to dramatically improve fuel utilisation in existing reactor fleets and paves the way for near term commercialisation.”
The company noted that post-irradiation examination 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 with traditional UO2 fuel. Initial observations also show that ANEEL fuel maintains structural integrity and favourable fission gas retention behaviour throughout irradiation.
“Surpassing 60 GWd/MTU of burnup in the Advanced Test Reactor marks an important milestone for the ANEEL fuel programme,” said Clean Core Thorium Energy CEO Mehul Shah. “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 utilisation, 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.”
Kelley Walker, principal investigator for the irradiation campaign at INL, added: “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.”
Last month, Clean Core Thorium Energy signed an agreement with Canadian Nuclear Laboratories (CNL) for the manufacture of demonstration irradiation bundles of its patented ANEEL thorium and high-assay low-enriched uranium (HALEU) fuel. Demonstration irradiation bundles are full-scale ANEEL fuel bundles matching actual reactor fuel bundles designed for interface and irradiation testing. Manufactured by Canadian Nuclear Laboratories at the Chalk River Laboratories, these bundles will enable Clean Core Thorium Energy to conduct demonstration irradiation which will provide practical, in-reactor data to support future qualification and potential deployment of ANEEL fuel in Candu reactors and other PHWRs. The demonstration fuel bundles are to undergo irradiation testing at INL’s Advanced Test Reactor, targeting burnup levels exceeding 60 GWd/MTU.
Clean Core Thorium Energy said it 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”.
