California-based nuclear technology start-up Antares has signed a binding multi-year fuel supply agreement (FSA) with OakRidge-based start-up Standard Nuclear. This strategic partnership establishes a secure, domestic supply chain for advanced nuclear fuel, enabling Antares to transition its microreactors from early-stage demonstrations to active deployments across the defence and space sectors.
Standard Nuclear will deliver 1-8 metric tonnes of uranium (MTU) of TRI-structural ISOtropic (TRISO) fuel over the contract period ending in 2035. Standard Nuclear stands as the only US company operating industrial-scale, licensed TRISO fuel fabrication facilities. The agreement builds on development work the companies have conducted together since 2025, including fuel specification, manufacturability, and production-path alignment.
Backed by more than $600m in funding, Antares, founded in 2023, has quickly accelerated its technology timeline. In June Antares achieved initial criticality of its Mark-0 microreactor demonstrator under the Department of Energy (DOE) Reactor Pilot Program. It aims to begin producing electricity from its advanced reactor design in 2027 and to begin first production deployments directly to US military installations in 2028.
The fuel arrangement addresses a critical bottleneck in the US advanced nuclear sector by anchoring the supply chain completely onshore. The agreement directly supports Antares’ growing government backlog, which has reached an estimated $1bn in contract value. Key federal programmes driving this demand include:
- The Army’s Janus Program, which aims to deploy dozens of resilient, off-grid microreactors to protect defence-critical infrastructure from grid vulnerabilities and liquid-fuel supply disruptions.
- The Air Force’s Advanced Nuclear Power Initiative (ANPI), where Antares is partnered to power Joint Base San Antonio.
- Space Force initiatives, engineering specialised, compact power units to maintain persistent space operations
“Antares exists to deliver nuclear power exactly where and when it is needed most, whether supporting stateside military installations, enabling persistent space operations, or powering mission-critical infrastructure far from the grid,” said Jordan Bramble, CEO and Co-founder of Antares. “Securing a long-term, industrial-scale supply of TRISO fuel from Standard Nuclear is a foundational step in moving our microreactors from demonstration to deployments. This partnership gives us the fuel certainty required to meet the strategic energy demands of our customers with the reliability and performance those missions require.”
“Antares is building reactors for some of the most demanding environments on earth and in space, and Standard Nuclear is proud to support Antares for their strategic energy applications,” said Kurt Terrani, CEO of Standard Nuclear. “We are working to scale our TRISO production capacity across identical facilities and continue to adhere to our customers’ needs. Now, as our customers move from demonstration toward commercial deployment, we are building the supply chain that advanced reactors need to meet their commercial needs and our nation’s energy and national security.”
Standard Nuclear is currently the only US company operating industrial-scale, fully licensed fabrication facilities capable of manufacturing TRISO fuel at its facilities located on the site of the legacy K-25 gaseous diffusion enrichment project in Oak Ridge. The company was formed around the fuel-manufacturing assets of Ultra Safe Nuclear Corporation (USNC) following its late 2024 bankruptcy. Standard Nuclear is led by CEO Kurt Terrani, a former fellow at Oak Ridge National Laboratory.
Beyond Antares, Standard Nuclear forms the backbone of the entire US advanced reactor market. The company has established major binding supply agreements with other microreactor firms (such as Radiant Industries) and operates a joint venture with French engineering company Framatome to deploy a commercial-scale high-assay low-enriched uranium (HALEU) TRISO production line by 2027.
HALEU, enriched to between 5% and 19.75% uranium-235, is the foundational feedstock required to make TRISO fuel. Because commercial, domestic HALEU enrichment capacity is virtually non-existent in the US, it represents the single greatest supply chain bottleneck for the entire next-generation nuclear industry.
Historically, the Russian state-owned firm Tenex (a subsidiary of Rosatom) was the only commercial vendor in the world supplying HALEU on an industrial scale. The 2024 US import ban cut off this pipeline for American companies, forcing a scramble for domestic alternatives. China National Nuclear Corporation also possesses the state-backed infrastructure to enrich HALEU at scale. However, this supply is entirely consumed domestically by its own reactor construction pipeline.
These severe constraints surrounding HALEU impact the timelines of both Antares Nuclear and Standard Nuclear In the short term, both companies have successfully decoupled their immediate demonstration timelines from commercial supply shortages by leveraging US federal stockpiles. The DOE HALEU Availability Program allocated dedicated batches of HALEU feedstock directly to both Antares and Standard Nuclear.
Because of these direct federal allocations, the constraints did not stall early milestones. Standard Nuclear successfully processed DOE-allotted HALEU to deliver its first commercial reactor core. Meanwhile, Antares secured enough early-stage material to fuel its Mark-0 demonstrator to initial criticality.
However, as Antares attempts to transition from single-unit demonstrations to utility-scale electricity generation (2027) and domestic military deployments (2028), the commercial availability of HALEU becomes highly critical. Standard Nuclear’s current facilities (like the SN-0 line in Oak Ridge) can process up to 0.5 metric tonnes of uranium annually. However, without a consistent, scaled stream of gaseous HALEU feedstock from enrichers, its industrial TRISO lines risk running below maximum capacity.
To prepare for commercial volume, Standard Nuclear partnered in a joint venture with Framatome in Richland, Washington. While the Nuclear Regulatory Commission recently approved an expansion to handle material up to 10% enrichment, full-scale commercial HALEU (up to 19.75%) requires ongoing licensing modifications and transport container approvals, capping throughput velocity until late 2027.
Antares’s agreement to procure up to 8 MTUs of TRISO fuel by 2035 is heavily back-weighted. Because of current HALEU scarcities, the firm commitment is initially locked at just 1 MTU, with the remaining 7 MTUs structured as flexible purchase options. If domestic HALEU enrichment fails to scale by 2028, Antares’s ability to execute those options and fulfil its $1bn defence backlog could face regulatory and resource delays.
To permanently overcome Western fuel constraints and secure their post-2030 target deployments, the companies have aligned their manufacturing trajectories with new allied enrichment infrastructure. To insulate its long-term deployment timeline, Antares signed a definitive enrichment services agreement with global supplier Urenco, which is expanding its capabilities, including breaking ground on its facility in Eunice, New Mexico. It is also constructing a dedicated HALEU enrichment plant in the UK, scheduled to go live in 2031. This timeline matches the back half of the Antares-Standard fuel agreement. The plan is that, by the time Antares needs to draw on the remaining 7 MTUs of TRISO fuel for mass military and space deployments, the raw HALEU feedstock will transition from limited government stockpiles to Urenco’s commercial enrichment lines, which Standard Nuclear will then fabricate into finished TRISO pellets. It remains to be seen whether these targets will be met.
