HWBRIEF
HALEU is uranium enriched to 5–20% uranium 235, used in compact reactors; the 23 July allotments back NASA's late 2028 SR 1 Freedom nuclear reactor powered spacecraft and Radiant's 2028 Kaleidos portable microreactor delivery to Buckley Space Force
The US Department of Energy on 23 July set aside high-assay low-enriched uranium (HALEU) for two projects: NASA's planned SR-1 Freedom nuclear-powered interplanetary spacecraft, slated for launch in late 2028, and Radiant's portable Kaleidos high-temperature gas microreactor, headed to Buckley Space Force Base in Colorado with delivery set for 2028. NASA is a first-time recipient under the HALEU allocation scheme; Radiant had a prior allocation for Kaleidos, a small, transportable reactor design.
HALEU is enriched to 5–20% uranium-235, compared with the ≤5% in standard low-enriched uranium used across the existing US commercial fleet. The Department of Energy set up the HALEU Availability Program in 2020 to close a domestic supply gap that had been holding back advanced reactor deployment.
The allocations are conditional. The DOE notes HALEU is not currently commercially available from US domestic suppliers, so the timing of actual fuel delivery depends on that supply chain maturing in time. SR-1 Freedom is designed to weigh about 12,000 kilograms, generate 20 kilowatts of electric power via a closed Brayton cycle, and carry a SkyFall payload of three Mars helicopters evolved from NASA's Ingenuity; those specifications are design targets, not flight-proven numbers. Prior reporting has put a roughly $2 billion price tag on the broader nuclear Mars architecture.