First fuel produced for molten salt reactor experiment

The Molten Chloride Reactor Experiment (MCRE) project - a public-private collaboration between Southern Company, TerraPower, CORE POWER, and the US Department of Energy (DOE) - is planned to be the first reactor experiment hosted at the Laboratory for Operation and Testing in the United States (LOTUS) test bed being built at the lab by the DOE's National Reactor Innovation Center. It uses liquid salt as the fuel and the coolant, allowing for high operating temperatures to efficiently produce heat or electricity.

The Molten Chloride Reactor Experiment will need 72 to 75 batches of fuel salt to enable it to go critical - giving Idaho National Laboratory (INL) its largest fuel production challenge in 30 years, according to the DOE Office of Nuclear Energy. The fuel salt production process began in 2020, but early attempts yielded far below the goal of 90% conversion of uranium metal into uranium chloride and production of 18 kg of fuel salt per batch. But a breakthrough in 2024 - when the team developed a new step to improve uranium utilisation - eventually led to the achievement of 95% conversion and full-batch production. They have since demonstrated they can produce a batch in as little as one day, according to INL.

The first fuel salt production batch was delivered at the end of September, with four further batches to be produced by March 2026, supporting a key national goal to advance nuclear energy outlined in an executive order issued earlier this year by President Donald Trump, the lab said.

"This is the first time in history that chloride-based molten salt fuel has been produced for a fast reactor," said Bill Phillips, INL's technical lead for salt synthesis. "It's a major milestone for American innovation and a clear signal of our national commitment to advanced nuclear energy."

The US Department of Energy released a final environmental assessment and draft finding of no significant impact for the design, construction, and operation of the MCRE, to be built at INL by Southern Company, in 2023.

Results from the Molten Chloride Reactor Experiment will help inform the commercial deployment of TerraPower and Southern Company's Molten Chloride Fast Reactor that could be deployed in the 2030s. But it also has significant implications for the maritime industry, according to Don Wood, senior technical advisor for MCRE. "Molten salt reactors could provide ships with highly efficient, low-maintenance nuclear power, reducing emissions and enabling long-range, uninterrupted travel. The technology could spark the rise of a new nuclear sector - one that is mobile, scalable and globally transformative," he said.