Antares is developing modular, transportable reactors, fuelled using TRISO (tri-structural isotropic) HALEU fuel. The company’s Antares 0 achieved criticality in June, becoming the first reactor under the Department of Energy’s Reactor Pilot Program to achieve criticality by the deadline of 4 July set in 2025 by US President Donald Trump. The fuel for the criticality demonstration was provided by BWX Technologies, Inc.
“Fuel supply is one of the practical questions every advanced reactor developer has to answer,” said Antares co-founder and CEO Jordan Bramble. “This contract gives Antares a reliable, US-origin source of HALEU for the reactors we’re deploying for a wide variety of defence and space customers.”
Centrus is already producing HALEU at its American Centrifuge Plant in Piketon, Ohio, and last year launched a multi-billion-dollar expansion including large-scale production of HALEU as well as the low-enriched uranium used in today’s operating nuclear power plants.
The contract is a sign that demand for HALEU is real and is accelerating, Centrus President and CEO Amir Vexler said. “Binding orders from Antares and others are supporting our expansion to commercial-scale production – an expansion that is now well under way.”
In August, Antares was one of five microreactor developers selected by the US Department of the Army for deployment at five Department of War installations, under the Janus programme – the next-generation nuclear power programme – which, under an Executive Order signed by Trump in May 2025, aims for operation of an Army-regulated nuclear reactor at a domestic military installation no later than 30 September 2028. Antares is to construct and operate nuclear microreactor power at Fort Bragg, North Carolina, under the programme. It has also been selected for deployment at Joint Base San Antonio, Texas, under the US Air Force’s Advanced Nuclear Power for Installations programme, and is a recipient of a US Space Force Strategic Breakthrough award to demonstrate a space reactor.
Certain nuclear applications in the USA, particularly those related to national security missions, require a supply of so-called unobligated enriched uranium: uranium that is free of peaceful use obligations that apply to uranium and certain technologies imported into the US under international agreements. Centrus’s enrichment technology and manufacturing supply chain are of US origin, and its AC100 centrifuge design is the only deployment-ready enrichment technology capable of ‘unobligated’ enrichment, so the arrangement can provide Antares with fuel that could be used for a variety of national security applications.
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Urenco’s Magnus Mori and Antares’ Tom Mancinelli pictured at World Nuclear Symposium (Image: World Nuclear Association)
Earlier this year, Antares signed a multi-year contract for the supply of HALEU with Urenco, to be produced at Urenco’s HALEU enrichment facility in the UK. That facility, at the Capenhurst site in north-west England, is already being built with funding support from the UK government and is scheduled to come online in 2031.
A diversity of supply sources is important to avoid over-reliance on single suppliers, Antares Head of Federal Strategy and Policy Tom Mancinelli said at a side event at World Nuclear Symposium 2026 last week.
“Certainly we recognise how important it is that strategic inputs like fuel don’t have any dependencies or vulnerabilities to foreign suppliers who could immediately cut something off,” Mancinelli said in the event’s Knowledge Zone. “It’s simple to me. It comes down to supply and demand and where we have, in the case of Urenco, a demonstrated track record in enrichment – I welcome that sort of partnership, including if it’s coming from Capenhurst or from (Urenco USA’s enrichment plant in) New Mexico. We want to see an increase in supply from trusted Western partners who share our values, and so we think Urenco is a great fit for Antares.”
