US nuclear fuel company counters BARC’s safety concerns over thorium fuel for reactors: More details inside

Chicago-based nuclear fuel company has denied the concerns over the use of ANEEL (Advanced Nuclear Energy for Enriched Life), an advanced nuclear fuel, in existing pressurised heavy water reactors (PHWRs). The company known as Clean Core Thorium Energy (CCTE) claimed that the thorium-based fuel improves significant reactor safety characteristics and can be positioned without the need for modifications to reactor designs or control systems.

In a report 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 countered the discovery of a previous study by scientists at the Bhabha Atomic Research Centre (BARC). Research on the BARC paper had challenged that deploying ANEEL in the existing PHWR fleet of India would require reactor redesigns and would likely increase safety risks under accident conditions.

The paper stated that the advanced nuclear fuel produces nearly six times more energy than conventional natural uranium fuel. CCTE is the second American company to have secured an export license from the US Department of Energy for supplying nuclear technology to India in nearly 20 years, and has developed the patented thorium-based fuel called ANEEL. The fuel combines thorium with high-assay low-enriched uranium (HALEU) for use in Pressurised Heavy Water Reactors (PHWRs).

CCTE said ANEEL is compatible with India's fleet of PHWRs, which make up the majority of the country's operational nuclear reactors. In December 2024, state-run NTPC Ltd partnered with the company to explore the development and deployment of ANEEL fuel at existing nuclear power plants in India, subject to regulatory approvals.

However, a paper published in Current Science in January by scientists from the Bhabha Atomic Research Centre (BARC) raised concerns about introducing ANEEL into India's existing PHWRs. The researchers concluded that the thorium-HALEU fuel was not a straightforward replacement for natural uranium and that significant modifications to existing reactors would be necessary before it could be used.

Responding to these concerns, CCTE maintained that ANEEL is a "plug-and-play" alternative to conventional natural uranium fuel bundles. The company argued that the fuel retains the same external dimensions and overall geometry as existing fuel assemblies, with changes confined only to the internal pin design and fuel composition.

Effectiveness of the reactor's shutdown system

CCTE's paper also countered the argument that the existing nuclear reactors of India would require major redesigns to use its ANEEL thorium-based fuel. While an earlier study by BARC scientists estimated that the effectiveness of the reactor's shutdown system would fall by about 26 per cent, requiring modifications to maintain safety margins, CCTE estimated a much smaller decline of up to 16 per cent.

According to the company, the current Primary Shutdown System would still retain an estimated safety margin of 70 mk, well above the required 50 mk, making any redesign unnecessary. The paper also disputed concerns over coolant void reactivity (CVR), an important reactor safety parameter. BARC had argued that thorium-HALEU fuel could increase CVR, raising safety risks during a loss-of-coolant accident.

However, CCTE claimed ANEEL actually improves reactor safety by reducing the potential power surge from 16.4 mk with conventional uranium fuel to 13.3 mk. It attributed this to the fuel's ring-wise design and burnable absorbers. Although HALEU-thorium fuel has a higher upfront cost, CCTE argued this would be offset over time through lower uranium consumption, greater energy generation and reduced spent fuel management costs.