lowenriched

Low-enriched uranium (LEU) is uranium whose fissile isotope U-235 has been enriched to less than 20% abundance. In civilian nuclear power, LEU is typically enriched to about 3-5% U-235. In contrast, highly enriched uranium (HEU) contains 20% or more U-235 and can be further enriched toward weapon-grade levels.

Most commercial LEU comes from natural uranium that has undergone enrichment, usually by gas centrifugation. The feedstock is hexafluoride gas UF6; enrichment concentrates U-235 by spinning the gas to different masses; the resulting product is LEU UF6, converted to UO2 fuel pellets for reactors. The typical fuel assemblies consist of uranium dioxide pellets in zirconium alloy cladding, arranged in fuel rods.

Uses and limitations: LEU powers the majority of commercial nuclear reactors worldwide, especially light-water reactors. Some research reactors and certain propulsion reactors also use LEU or are transitioning from HEU to LEU for non-proliferation reasons. LEU is less suitable for weapons due to lower U-235 content, though it remains a proliferation concern if enrichment capacity is used to add significant fissile material.

Regulation and safeguards: LEU production and use are subject to international safeguards under the Nuclear Non-Proliferation Treaty and IAEA inspections to verify declared fuel cycles and prevent diversion. Countries maintain enrichment programs under safeguards and export controls to discourage diversion to weapons programs.

Economics and supply: LEU requires significant processing and infrastructure, including mining, conversion, enrichment, and fuel fabrication. Global supply is concentrated among a few countries with enrichment facilities, and disruptions can affect reactor fuel availability. Ongoing efforts focus on safe, secure, and nonproliferation-aligned enrichment standards.