5 min readNew DelhiJul 14, 2026 07:45 AM IST
First published on: Jul 14, 2026 at 07:44 AM IST
Chicago-based nuclear fuel company Clean Core Thorium Energy (CCTE) has refuted concerns over the use of its advanced nuclear fuel, ANEEL, in existing pressurised heavy water reactors (PHWRs). The company claimed that the thorium-based fuel improves key reactor safety characteristics and can be deployed without requiring modifications to reactor designs or control systems.
In a paper published in the journal Nuclear Engineering and Design, researchers from Clean Core, the Massachusetts Institute of Technology, Toronto-based Innovative Nuclear Solutions, and San Diego-based Structural Integrity Associates challenged the findings of an earlier study by scientists at the Bhabha Atomic Research Centre (BARC). The BARC paper had argued that deploying ANEEL in India’s existing PHWR fleet would require reactor redesigns and could increase safety risks under accident conditions.
The paper also claimed the advanced nuclear fuel has the potential to generate around six times more energy than conventional natural uranium fuel.
CCTE, only the second American company to have secured an export license from the US Department of Energy to sell nuclear technology to India in nearly two decades, has developed the patented thorium-based fuel called ANEEL (Advanced Nuclear Energy for Enriched Life), which combines thorium with high-assay low-enriched uranium (HALEU) for use in PHWRs.
According to the company, ANEEL can be deployed in India’s PHWR fleet, which accounts for the majority of the country’s operational nuclear reactors. In December 2024, state-owned NTPC Ltd and CCTE had announced a strategic partnership to explore the development and deployment of ANEEL for existing nuclear stations in India, subject to regulatory clearances. Apart from exploring the development and deployment of ANEEL fuel in India, the two companies also intend to collaborate for exploring the possible indigenisation of its manufacturing with local supply chain development, establishing supply chain for HALEU, and supply of Uranium to India with sovereign guarantee.
Concerns over safety, cost and reactor redesign
In January, a paper published in the journal Current Science authored by scientists at BARC had flagged concerns about using ANEEL fuel in the country’s existing PHWRs. It concluded that thorium-HALEU fuel was “far from a drop-in option” and that existing reactors were unsuitable without substantial changes.
The CCTE paper, however, refuted this and described ANEEL as a “plug-and-play” replacement for natural uranium fuel bundles, saying it retains the same external dimensions and geometry as conventional fuel and modifications are limited to internal pin geometry and fuel composition.
The paper also refuted the need for reactor redesign. While the earlier BARC study estimated that the effectiveness of reactor shutdown systems would decline by around 26%, necessitating a redesign of the Primary Shutdown System to maintain adequate safety margins, the CCTE paper estimates a smaller reduction of up to 16%. It concludes that the existing shutdown system retains sufficient margin, with an estimated worth of 70 mk against a safety requirement of 50 mk, and therefore argues that redesigning existing reactors is unnecessary.
Another key issue flagged by the paper authored by BARC scientist is coolant void reactivity (CVR), a key reactor safety parameter. It argued that using thorium-HALEU fuel would make coolant void reactivity more positive, raising safety concerns. However, CCTE paper refutes this safety concern, claiming its ANEEL fuel reduces the safety risk. In a “loss-of-coolant” accident where the reactor’s cooling water disappears, standard uranium fuel causes a dangerous power surge measured at 16.4 mk. According to CCTE, ANEEL fuel reduces this surge to 13.3 mk, making the reactor more stable and easier to control during an emergency
It attributes this improvement to the fuel’s heterogeneous ring-wise design and the use of burnable absorbers.
The paper also addressed the concerns over high front-end cost of HALEU-Th fuel, saying it will be offset by the fuel’s lifecycle through lower uranium consumption, higher energy output and significantly reduced spent fuel management and disposal costs.
ANEEL completes irradiation test
Amid the ongoing debate over its feasibility, the fuel remains in the pre-licensing and final testing stage and is not yet ready for commercial deployment. In May, the fuel completed its high burnup irradiation test in an Advanced Test Reactor (ATR) at Idaho National Laboratory (INL). The company said the final set of irradiation capsules have achieved more than 60 GWd/MTU of ‘burnup’ — a measure of how much energy is extracted from nuclear fuel that is typically expressed in gigawatt-days per metric tonne of heavy metal or GWd/MTU.
CCTE is now planning its next milestone: a demonstration irradiation in a commercial power reactor that will move ANEEL fuel from proven test concept to commercial reality.
In April, CCTE and Canadian Nuclear Laboratories (CNL) announced an agreement to manufacture demonstration irradiation bundles of ANEEL advanced nuclear fuel.
Demonstration irradiation (DI) bundles are prototypic ANEEL fuel bundles matching actual reactor fuel bundles designed for interface and irradiation testing. Manufactured by CNL at the Chalk River Laboratories in Canada, these bundles will enable Clean Core to conduct demonstration irradiation which will provide practical, in-reactor data for to support future qualification and potential deployment of ANEEL fuel in CANDU reactors — Canadian-developed PHWRs — and other PHWRs.
The company claimed that the thorium-based fuel improves key reactor safety characteristics and can be deployed without requiring modifications to reactor designs or control systems. (Source: File) 
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