DOE approves cost-shared funding to speed up molten chloride reactor test

The US Department of Energy has approved cost-shared funding for an accelerated final stage of the Molten Chloride Reactor Experiment (MCRE) under its Advanced Reactor Demonstration Program, Southern Company said on October 14, 2026. The funding supports work by Southern Company, Idaho National Laboratory and CORE POWER, and MCRE is now expected to reach first criticality as early as 2027. The release puts no dollar figure on the funding.

DOE's December 2025 schedule had MCRE running in 2028; the partners now expect first criticality as early as 2027. In a December 3, 2025 article, DOE's Office of Nuclear Energy said the experiment was anticipated to run in 2028 for about six months in INL's LOTUS test bed. Going critical will take 72 to 75 batches of fuel salt, DOE said, INL's largest fuel production effort since Experimental Breeder Reactor-II.

MCRE is designed to be the world's first fast-spectrum molten chloride salt reactor experiment to reach criticality, with its fuel dissolved in liquid chloride salt. Its product is data. INL's Jess Gehin says it will measure how the reactor behaves during sustained fission, "data that until now, has come from models alone." The release lists extracting more value from used nuclear fuel and maritime propulsion among the technology's possible futures, then rules both out for this machine in its notes to editors: MCRE "will not use spent fuel, demonstrate a closed fuel cycle or test a marine reactor."

The two documents frame the commercial payoff differently. The October release names CORE POWER, a maritime nuclear developer, alongside Southern Company and INL, and does not mention TerraPower. CORE POWER's chief executive, Mikal Bøe, says the company first committed to building MCRE in 2020 and names civil maritime nuclear propulsion of large commercial ships as one market the work could open. DOE's December 2025 article still says MCRE's results will help inform the Molten Chloride Fast Reactor that TerraPower and Southern Company could deploy in the 2030s, with potential land and maritime uses.