The Molten Chloride Reactor Experiment (MCRE) at INL is set to evaluate a revolutionary nuclear reactor design using molten chloride salt combined with uranium as both a fuel and coolant. The experiment aims to assess the safety and physics of a molten chloride fast reactor, which Southern Company and TerraPower plan to construct.
This advanced reactor design presents significant advantages, including higher operating temperatures for enhanced efficiency, reduced waste production, and inherent safety features enabled by the liquid fuel structure.
"It's like baking a cake," explained Bill Phillips, technical lead for MCRE. The challenge lay in maximizing efficiency, ensuring over 90% of uranium metal was converted into usable fuel salt. "Nobody has ever made this amount of uranium chloride before," Phillips emphasized. "We had to develop the process from scratch."
The journey began in 2020 at INL's Materials and Fuels Complex, where Phillips and his team designed and refined the necessary equipment and processes for salt synthesis.
Nick Smith, MCRE project director, recalled early struggles. "We initially lost too much uranium metal, making it impossible to produce enough fuel salt for the reactor to achieve criticality," he noted. "After years of rigorous testing and refinement, we finally discovered the precise process needed to achieve the optimal yield."
"We used food-inspired names to describe our methods, like angel cake or stone soup," said Phillips. "Even coffee-making techniques like a French press helped us conceptualize our approach."
Given the high value and cost of enriched uranium, the team initially worked with depleted uranium, allowing them to test and refine processes without wasting valuable resources.
"When I joined, we were only producing a few ounces of fuel at a time," said Jacob Yingling, a research scientist leading fuel salt technology development. "Scaling up was a major challenge. Now, we can produce over a dozen pounds of reactor fuel in a single batch."
INL is also advancing additional molten salt reactor capabilities, including a characterization facility and irradiation experiments. In 2023, Phillips successfully synthesized and irradiated enriched uranium-fueled molten chloride salt in the Molten Salt Research Temperature Controlled Irradiation experiment, providing valuable data on fuel behavior in commercial reactors.
Further enhancing research efficiency, the newly operational Molten Salt Flow Loop Test Bed enables real-time monitoring and analysis of molten salt fuel.
"We're almost at the moment where we can bake the cake," said Phillips. The team has refined all processes and is now prepared for full-scale fuel production.
The next objective is to produce five batches of enriched fuel salt by October 2025. MCRE is expected to become operational by 2028, aligning with the Laboratory for Operation and Testing in the United States (LOTUS) test bed, where MCRE will be the first reactor experiment.
"We're driven by what molten chloride reactors can achieve that other energy technologies can't," Yingling remarked. "Everyone involved in MCRE is committed to bringing this groundbreaking technology to life."
Related Links
Idaho National Laboratory
Nuclear Power News - Nuclear Science, Nuclear Technology
Powering The World in the 21st Century at Energy-Daily.com
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