LEU+ (5-10% Enrichment)

LEU+ is an informal industry designation for uranium enriched to between 5% and 10% U-235, positioned between conventional low-enriched uranium (LEU, below 5%) and the broader HALEU category (5-20%). While technically HALEU by the formal definition (any enrichment between 5% and 20%), LEU+ has emerged as a distinct commercial category because it can be produced by existing centrifuge enrichment facilities with relatively modest modifications, whereas enrichment to 10-20% U-235 requires additional cascades, enhanced criticality safety measures, and more extensive facility licensing. LEU+ represents a pragmatic stepping stone that delivers some of the performance benefits of higher enrichment while leveraging existing enrichment infrastructure.

The most significant regulatory milestone for LEU+ was the NRC's authorization of Urenco USA in September 2025 to enrich uranium up to 10% at its facility in Eunice, New Mexico. This made Urenco the first Western commercial enricher licensed to produce LEU+ material, with initial production beginning in 2025 and first deliveries to fuel fabricators planned for 2026. Urenco is simultaneously adding 2.5 million SWU of new enrichment capacity, including 700,000 SWU at the U.S. site by 2027. For reactor developers whose designs can function with enrichment in the 5-10% range rather than requiring the full 19.75% HALEU, LEU+ dramatically simplifies the fuel supply chain and reduces fuel costs, as LEU+ requires roughly half the SWU per kilogram compared to near-20% HALEU.

Several advanced reactor concepts can potentially operate with LEU+ fuel, accepting some performance trade-offs (shorter fuel cycles or larger core volumes) compared to their HALEU-optimized configurations. The availability of LEU+ from established enrichers like Urenco provides a bridge fuel strategy that could accelerate initial deployments while the full-scale HALEU production infrastructure, including Centrus Energy's expanded cascade at Piketon, Orano's planned U.S. facility, and Urenco's planned Capenhurst HALEU facility, comes online in the late 2020s and early 2030s. This stratified approach to enrichment availability, with LEU available now, LEU+ coming online in 2025-2026, and full HALEU at scale by 2030, allows the advanced reactor industry to begin operations and build regulatory and construction experience while the highest-enrichment fuel supply catches up to demand.