Antares Secures U.S.-Origin HALEU Supply in Multi-Year Centrus Contract

Centrus Energy (LEU ) and Antares Nuclear announced on September 17, 2026 the signing of a definitive multi-year contract for Centrus to supply Antares with High-Assay Low-Enriched Uranium (HALEU), with deliveries commencing before the end of the decade, according to the companies’ joint news release. The release states that the contract ensures a reliable, domestic source of HALEU to support Antares’ advanced reactor projects, including for space and national security missions. The agreement includes prepayments from Antares to support the expanded HALEU capacity and adds another HALEU customer to Centrus’ backlog. The companies did not disclose a contract value, delivery volumes, or pricing.

“This contract is another sign that demand for HALEU is real and it is accelerating, and Centrus is in prime position to meet this need,” said Amir Vexler, President and CEO of Centrus. Vexler said binding orders from Antares and other customers are supporting the company’s expansion to commercial-scale production, an expansion he said is now well underway.

“Fuel supply is one of the practical questions every advanced reactor developer has to answer,” said Jordan Bramble, CEO and Co-Founder of Antares. “This contract gives Antares a reliable, U.S.-origin source of HALEU for the reactors we’re deploying for a wide variety of defense and space customers.”

Unobligated Production for National Security Missions

Centrus says it is pioneering U.S. HALEU production at its American Centrifuge Plant in Piketon, Ohio, which it describes as the only licensed HALEU production facility in the western world. In 2025, Centrus launched a multi-billion-dollar expansion that includes large-scale production of HALEU as well as Low-Enriched Uranium (LEU).

According to the release, the agreement reflects the role both companies can play in meeting U.S. national security requirements. Because Centrus’ enrichment technology and manufacturing supply chain are U.S.-origin, the arrangement can provide Antares with fuel that could be used for a variety of national security applications. Centrus states that its AC100 centrifuge design is the only deployment-ready enrichment technology capable of “unobligated” enrichment, meaning it can be used for U.S. national security missions.

The Antares contract follows another definitive multi-year HALEU supply agreement that Centrus announced with Radiant on September 9, 2026, covering the fuel needed to deploy multiple Kaleidos microreactors. Under that agreement, Centrus will begin delivering HALEU before the end of the decade, with prepayments from Radiant supporting Centrus’ domestic commercial enrichment capacity program. The enrichment Centrus provides to Radiant will likewise be “unobligated” and usable for national security applications, according to that announcement.

Antares Defense and Space Reactor Programs

Antares is developing compact microreactors for critical missions on Earth and in space. In 2026, the company was selected for the U.S. Army’s Janus Program at Fort Bragg, North Carolina; the Air Force’s Advanced Nuclear Power for Installations program at Joint Base San Antonio, Texas; and a Space Force Strategic Breakthrough award to demonstrate a space reactor.

On September 11, 2026, Antares announced its selection by the Office of the Assistant Secretary of the Air Force for Space Acquisition and Integration for a $161 million Strategic Breakthrough award to advance nuclear power for space, which the company described as the largest current Department of War award in space nuclear power. Under the program, Antares will perform a nuclear ground demonstration of its R1-S reactor and integrate it with a spacecraft for flight certification ahead of launch. The company will also power an operational ground-to-space asset with Mark-1, its electricity-producing reactor, which is scheduled for testing in 2027.

Antares’ Mark-0 microreactor achieved initial criticality on June 4, 2026 at Idaho National Laboratory under Department of Energy authorization, which the company said made it the first private company to bring an advanced reactor to criticality under the DOE Reactor Pilot Program. The Mark-1 reactor is scheduled to operate for more than six months in 2027, integrated with Antares’ nitrogen closed Brayton cycle power conversion system.

Antares’ updates index dates the Army Janus agreement at Fort Bragg to August 26, 2026 and the Joint Base San Antonio selection under the Department of the Air Force’s ANPI initiative to April 22, 2026. The index also records a $470 million Series C raise on July 27, 2026, a long-term HALEU supply agreement with Urenco on May 21, 2026, and a multi-year TRISO fuel supply agreement with Standard Nuclear (STDN ) on August 27, 2026.

On the Antares website, the company describes its R1 microreactor as purpose-designed modular power for defense-critical assets, rated at 100 kWe to 1 MWe for more than six years. The design uses TRISO coated particle fuel in a prismatic graphite core, with sodium heat pipes that Antares says enable redundant, high-temperature, entirely passive heat transfer, and a recuperated nitrogen closed Brayton cycle for power conversion. The company states that in 2025 it completed its Conceptual Design Review on an accelerated timeline, became the first U.S. microreactor to receive a HALEU allocation and begin fuel fabrication, and opened Antares Prime, a 322,000-square-foot vertically integrated research and development facility. Its published roadmap calls for operating a full-power, electricity-producing advanced reactor in 2027 and preparing for customer deployments beginning in 2028.