HALEU is a critical fuel feedstock for the next generation of nuclear reactors. Conventional light-water reactors use low-enriched uranium (LEU) at 3-5% U-235 concentration. Many advanced reactor and SMR designs — including those from X-energy, TerraPower, Kairos Power, Oklo, and others — require uranium enriched to between 5% and 20% U-235 to achieve higher temperatures, longer fuel cycles, and more compact core designs. This intermediate enrichment level is called high-assay low-enriched uranium.
The HALEU supply chain is one of the most pressing bottlenecks for the advanced nuclear industry. Until recently, Russia was the only commercial source of HALEU through its subsidiary TENEX. The U.S. government has responded with significant investments to build domestic HALEU production capacity: Centrus Energy began producing small quantities of HALEU at its Piketon, Ohio facility in late 2023, becoming the first American producer. The Department of Energy has allocated billions of dollars to scale up HALEU supply, and additional enrichment capacity is being developed by Urenco and others.
The geopolitical dimension adds urgency. Russia's invasion of Ukraine prompted Western nations to accelerate efforts to eliminate dependence on Russian nuclear fuel. Legislation banning Russian uranium imports has been enacted in multiple countries. Building sufficient HALEU production capacity to fuel the growing pipeline of advanced reactors remains a multi-year, multi-billion-dollar challenge that many consider the single biggest constraint on SMR deployment timelines. For deeper coverage, see DeepTechIntel's nuclear section.