Idaho National Laboratory is receiving $7 million from the Department of Energy’s ARPA-E to irradiate and study fuel made from molten plutonium chloride salts, a test that lab leaders say nobody has run before. The project, called IMPACT for Irradiation of Molten Plutonium Actinide Chloride Fuels and Testing, is one of eight selected under a $50 million program aimed at recycled nuclear materials. Work begins in 2027 and runs for three years.
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Jess Gehin, INL’s associate laboratory director for nuclear science and technology, said it will be the first time any such experiment has been done. He added that the reactor and fuel technology remains early-stage but has high potential, and said it could produce up to 100 times more energy.
HORNIG and the eight ARPA-E projects
The money comes from a program with the unwieldy name High-performance Optimized Recycled Nuclear Isotopes for Gen IV Reactors, abbreviated HORNIG. ARPA-E’s announcement of the selections says eight projects share up to a combined $50 million to advance next-generation nuclear fuels. INL’s $7 million is 14 percent of that ceiling, against 12.5 percent for an even split of eight. The agency page does not name the other seven projects or give an announcement date, so the comparison stops there.
East Idaho News reported that the IMPACT award was announced early on Monday, November 2, and that the aim is to test chloride fuel salts containing recycled transuranic elements, the heavy radioactive elements left in used fuel, for use in molten salt reactors. The word recycled is the point: the fuel would be made from material that is currently managed as waste.
Hot cells, glovebox work and the MSTEC facility
The experiments take place at INL’s Materials and Fuels Complex in a facility called MSTEC, short for Molten Salt Thermophysical Examination Capability. Researchers handle the salts inside hot cell boxes using robotic arms or through gloveboxes, because plutonium-bearing material cannot be touched directly. The team plans to examine the salt before, during and after its time in a reactor to see whether it meets temperature, burnup and safety requirements.
Experiment manager Matthew Arrowood said the project is meant to show how the salt changes over time inside a reactor. Calvin Downey, the experiment design engineer, said the team wants the MSTEC data to be as useful as possible to its industry partners. The data will feed into models of advanced test reactors, and the new facility can fabricate transuranic-based fuel in a much smaller footprint than older approaches. About 15 people will work on it.
INL’s own materials describe molten salt reactors as advanced reactors that use low-pressure, high-temperature fluoride or chloride salts as liquid fuels and coolants. A short INL fact sheet on the technology frames them as part of the search for dependable, low-emission power, and a 2023 DOE presentation cited in the East Idaho News story lists better safety, lower-cost components and more efficient energy generation as possible advantages.
Argonne, Moltex Energy USA, Southern Company and the schedule
The lab is not working alone. Argonne National Laboratory, Moltex Energy USA and Southern Company are named partners on the project. Moltex’s website says the company is working through approvals in Canada toward its first reactor for NB Power and that its U.S. arm joined an ARPA-E-funded recycled fuel project in November. It also reports that Nuclea Energy will acquire the Moltex advanced nuclear technology platform, an ownership change announced in August, so the industrial partner’s corporate footing is shifting while the test is being planned.
Toni Karlsson, an industrial relationship manager at the lab, said work starts in 2027 and lasts three years, with a possible extension beyond 2030. Karlsson described the purpose of the national labs as helping industry get past what it cannot do alone. The lab itself, which calls itself the nation’s nuclear energy laboratory on its homepage, has spent the summer hosting first criticality for three other advanced reactors, so the fuel work sits beside a busy hardware program.
Moltex’s role gives the test a commercial reference point. The company says it reprocesses waste from existing nuclear plants and uses it to generate more energy, and its website names a fuel recycling concept in a June 2026 news item. A plutonium chloride salt made from recycled material is the kind of product such a business would need to qualify, which explains why a reactor developer sits next to two national laboratories and a utility on the partner list.
The Southern Company seat matters for a different reason. Utilities decide whether a fuel cycle ever gets bought, so their presence on a three-year test suggests the project is meant to produce numbers a power-plant owner can read: temperature limits, burnup and safety margins, the three requirements the researchers will check the salt against.
The outcome that matters arrives after 2030. A successful run would give reactor designers measured data on how plutonium chloride salt behaves under irradiation. A failed or ambiguous run would still be the first measurement of its kind, and would tell developers which assumptions in their models need to change.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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