What is Low-Enriched Uranium?

Uranium enriched to less than 5% uranium-235 concentration, the standard fuel form for conventional commercial nuclear power reactors and several SMR designs.

What category does Low-Enriched Uranium belong to?

Low-Enriched Uranium is a fuel-technology concept in nuclear energy and SMR technology.

Low-Enriched Uranium — Nuclear & SMR Glossary

Low-Enriched Uranium (LEU) is uranium that has been enriched to a U-235 concentration below 5%, the internationally recognized threshold below which the material is considered unsuitable for weapons use without further enrichment. Standard commercial reactor fuel is typically enriched to 3.5-5% U-235, and LEU has fueled the global nuclear fleet since the technology's commercialization. LEU is produced by the established enrichment industry, with multiple qualified fuel fabricators worldwide capable of converting enriched UF6 into finished fuel assemblies. The supply chain for LEU is mature, diversified, and well-regulated, with decades of continuous commercial operation.

For the SMR market, the distinction between LEU-fueled and HALEU-fueled designs is a major differentiator in deployment readiness and fuel supply risk. Several leading SMR designs use standard LEU fuel: NuScale's VOYGR (the only NRC-certified SMR design), GE-Hitachi's BWRX-300 (under construction at Darlington, Ontario), Rolls-Royce SMR (in UK GDA Step 3), Holtec's SMR-300, Westinghouse's AP300, China's Linglong One, and South Korea's i-SMR and SMART100. These designs can source fuel from existing suppliers including Westinghouse, Framatome, and Global Nuclear Fuel without waiting for the HALEU production scale-up that constrains advanced reactor timelines. This fuel availability advantage is one reason that light-water LEU-fueled SMRs are leading the near-term deployment race.

LEU fuel is fabricated in well-established forms: uranium dioxide (UO2) ceramic pellets stacked in zirconium alloy cladding tubes for PWRs and BWRs. The global LEU supply chain includes uranium mining (Cameco, Kazatomprom, Uranium Energy Corp, Denison Mines), conversion (facilities in the U.S., Canada, France, and UK), enrichment (Urenco, Orano, Centrus, and previously TENEX), and fuel fabrication (Westinghouse Columbia, Framatome Richland, Global Nuclear Fuel Wilmington). Even with the 2024 ban on Russian enriched uranium imports, the LEU market has sufficient Western capacity to support existing fleet needs and the initial wave of LEU-fueled SMR deployments, though enrichment capacity expansion is underway to provide long-term margin. The simplicity and availability of the LEU fuel cycle is a tangible commercial advantage that advanced reactor developers must weigh against the performance benefits of higher enrichment.