High-Assay Low-Enriched Uranium (HALEU)

High-Assay Low-Enriched Uranium (HALEU) is uranium enriched so that the concentration of the fissile isotope uranium-235 is greater than 5% but below 20%. This is higher than the enrichment level typically used in today’s commercial light-water reactors, which generally use fuel enriched to below 5% uranium-235. HALEU is expected to be used by many advanced reactor designs, including some small modular reactors and microreactors, because its higher energy density can enable smaller reactor cores, longer operating cycles and improved fuel utilization. However, expanding HALEU use requires dedicated enrichment, conversion, transport and fuel fabrication infrastructure, making supply availability a key constraint for the deployment of advanced nuclear technologies.