US-based nuclear fuel company Centrus Energy and advanced reactor start-up Radiant have signed a definitive, multi-year contract to secure a domestic supply of high-assay, low-enriched uranium (HALEU) for Radiant’s planned fleet of Kaleidos microreactors. Fuel deliveries from Centrus Energy are expected to begin before the end of the decade.
The contract includes prepayments from Radiant to Centrus. These funds directly back the expansion of domestic enrichment capacity. Centrus will manufacture the fuel using US-origin technology and supply chains. This qualification allows the fuel to support national security deployments alongside commercial use. Centrus’s AC100 centrifuge design is the only deployment-ready US origin technology available for unobligated enrichment today.
The fuel is enriched to between 5% and 20% uranium-235, offering higher energy density required by next-generation designs. The Kaleidos microreactor is a high-temperature gas-cooled reactor utilising TRISO (TRi-structural ISOtropic) particle fuel, helium coolant, and prismatic graphite blocks. The 3 MWt/1 MWe reactor is designed as a transportable, plug-in ready system housed within a single shipping container.
Advanced nuclear developers face a significant bottleneck in securing HALEU. By striking this deal well ahead of commercial operations, Radiant aims to avoid deployment delays. Meanwhile, Centrus will expand its active customer backlog and solidify its role as the premier domestic supplier for advanced fission markets.
“The contract with Radiant marks another important step in building the domestic fuel supply chain needed to support the next generation of nuclear energy,” said Amir Vexler, Centrus President & CEO. “By expanding our work to include innovative microreactor developers like Radiant, we are strengthening the US-based fuel supply network. This will help ensure that emerging nuclear technologies have access to the reliable fuel they need to reach commercialisation and meet growing demand for clean, secure, and dependable energy.”
Radiant Chief Nuclear Officer Dr Rita Baranwal noted: “You can’t deploy nuclear reactors without fuel, so we have approached our fuel supply the same way we have approached the reactor: build it in parallel, and don’t depend on any single path. This agreement gives Kaleidos a continued source of HALEU for commercial and national security applications and removes one of the biggest constraints facing advanced nuclear deployment. We’re securing the fuel supply chain alongside the reactor so that when Kaleidos is ready to deploy at scale, the infrastructure behind it is ready too.”
In April 2025 Radiant was one of five companies selected by DOE to receive HALEU to meet their near-term fuel needs. The following August, Radiant was one of 10 companies selected to receive support under DOE’s Reactor Pilot Program. The same month, Radiant signed an agreement with the Defense Innovation Unit (DIU) and the Department of the Air Force to deliver a first-of-a-kind (FOAK) microreactor to Buckley Space Force Base in 2028.
In July, Radiant received its first tranche of TRISO test fuel at the National Reactor Innovation Center’s Demonstration of Microreactor Experiments (DOME) facility located at the Idaho National Laboratory (INL) where the full-scale test reactor is executing a five-phase testing campaign. This culminates in a minimum 150-hour continuous full-power run without operator intervention to demonstrate passive safety and commercial readiness. The fuel was supplied by Standard Nuclear, fabricated using HALEU supplied by DOE under its Fuel Line Pilot Program.
The following month, Radiant signed a long-term fuel supply agreement with Standard Nuclear to provide (TRISO fuel fabrication to support the deployment of Kaleidos microreactors to government and commercial customers through the early 2030s. Standard Nuclear will supply multiple tonnes of TRISO fuel manufactured to the specifications of Kaleidos to be delivered by 2031. Radiant’s Part 70 licence application for its reactor production facility in Oak Ridge, Tennessee, is undergoing an accelerated review by the Nuclear Regulatory Commission (NRC).
Commercial HALEU enrichment takes place at the Centrus American Centrifuge Plant ACP in Piketon, Ohio – the first US-owned, enrichment facility to start production in decades. Centrus designs and manufactures its proprietary centrifuges at its Technology & Manufacturing Center in Oak Ridge, Tennessee. In early 2026, Centrus launched a major facility expansion to transition into a high-rate commercial manufacturing plant. New centrifuges produced in Tennessee are scheduled to come online at the ACP by 2029, significantly scaling up the output of US-origin HALEU.
