High-assay low-enriched uranium (HALEU) is the fuel of choice for many advanced reactor developers, including Advanced Reactor Concepts, which is designing the ARC-100, a sodium-cooled fast reactor. Developers face a potential supply problem, however: The United States has no clear path to build the commercial HALEU production facilities that would be needed to fuel a fleet of advanced reactors. A letter of intent signed by ARC and Centrus Energy, announced on April 28, calls for cooperation on the deployment of a commercial supply of HALEU and could lead to a HALEU purchase agreement for ARC-100 deployments in the late 2020s.

Advanced reactor cores are being designed for higher efficiencies and longer lifetimes, but to get there, they need high-assay low-enriched uranium (HALEU).

Enriched to between 5 and 19.75 percent fissile U-235, HALEU is packed with nuclear potential. It can be used as a feedstock for the demonstration of new fuel designs, from uranium alloys to ceramic pellets and liquid fuels. Those fuels can enable advanced reactor and microreactor demonstrations. Operating light-water reactors could potentially transition to HALEU uranium oxide fuels for extended operating cycles and improved plant economics.