Army selects Antares to build and operate Fort Bragg microreactors in $2.2B Janus program

Why it matters

Fort Bragg puts Antares' defense-first strategy into the Army's milestone-funded Janus program. Payments are contingent on vendors meeting specified technical goals, and the Army is targeting operation of its first installation reactor in 2028.

Antares, the nuclear microreactor maker co-founded by Jordan Bramble (@jordanbramble), has been selected by the U.S. Army and Defense Innovation Unit to build, own and operate nuclear microreactors at Fort Bragg, North Carolina, Bramble told Axios.

The award gives Bramble the customer Antares was designed around. His route into nuclear energy ran through software, government and restaurants: Bramble studied systems engineering and operations research at George Mason University, worked at Opower and Cava, built data infrastructure for login.gov at the White House and U.S. Digital Service, and later co-founded Local Kitchens, according to his professional biography.

Bramble and Julia DeWahl founded Antares in 2023 around a narrower thesis than many advanced nuclear developers: begin with defense missions where reliable power carries a premium and dependence on civilian grids or fuel deliveries creates an operational risk. DeWahl, who previously worked on Starlink at SpaceX, now serves on Antares' board.

"We need to be able to sustain our most critical operations without the grid, without a civilian supply chain," Bramble told Axios.

Fort Bragg hosts the XVIII Airborne Corps and Army special operations commands, along with tens of thousands of military personnel and civilian workers. Army officials have said Janus reactors will support critical loads while installations retain their connections to the commercial grid.

A defense-first founder gets his intended customer

Antares' Fort Bragg agreement is part of the Army's Janus program, which selected five reactor vendors for five initial sites. BWXT Advanced Technologies received Fort Campbell, General Atomics Electromagnetic Systems received Fort Hood, Radiant received Fort Benning, and Westinghouse Government Services received Fort Drum.

The Army has committed up to $2.2 billion across the five agreements from fiscal 2027 through 2031 and expects the program, combined with private capital, to support more than 20 reactors across military installations. Contractors will receive milestone payments after meeting defined technical goals. They will retain ownership and responsibility for operating the prototypes.

That structure transfers a meaningful portion of the execution risk to Antares and its peers. A reactor developer cannot collect the full value of an award by producing studies and schedules. Janus payments depend on specified hardware and technical milestones, while the Army is targeting operation of its first installation reactor in 2028.

Antares has not disclosed the value of its Fort Bragg agreement. Bramble said the company has contract value "on the order of $1B" across its Army, Air Force and Space Force work. That figure covers several programs and represents claimed contract value; Antares has not reported it as recognized revenue.

The Air Force and DIU have also paired Antares with Joint Base San Antonio under the Advanced Nuclear Power for Installations initiative. The official JBSA project page describes the base as a potential site, rather than a finalized deployment.

Antares' government work spans multiple reactor programs, though the final quantity, output and delivery schedule for Fort Bragg remain undisclosed. Axios reported that the Army expects Antares to deliver reactors in what the service calls "three packs."

Antares enters Janus with a large private balance sheet. RuntimeWire reported in July that Antares raised a $470 million Series C, comprising $370 million in equity and $100 million in debt. Paradigm and Caffeinated Capital co-led the financing, with Point72 Ventures, Shine Capital and Industrious Ventures participating.

The financing was explicitly raised to move Antares from reactor experiments into electricity-producing systems. Bramble said at the time that Antares intended to invest alongside government funding, giving Janus access to private capital while giving Antares a federal customer prepared to pay for energy resilience instead of the cheapest available kilowatt-hour.

Criticality was the first gate

Antares has cleared one technical milestone that separates it from the many reactor developers still working primarily through simulations and component tests. Its Mark-0 reactor achieved criticality at Idaho National Laboratory on June 4th under the Department of Energy's Reactor Pilot Program.

Criticality means the reactor sustained a controlled fission chain reaction. It did not mean Antares generated electricity. As RuntimeWire reported after the test, Mark-0 was configured as a zero-power experiment. A Department of Energy environmental document says it lacked heat-removal and power-conversion systems and was not expected to produce measurable thermal or electrical output.

The test nevertheless gave Antares physical data on its reactor core, control system and TRISO fuel. The Energy Department identified Mark-0 as the first reactor to reach criticality under its Reactor Pilot Program.

Antares has said its Mark-1 design is intended to produce electricity in 2027. Initial customer deployments are targeted for 2028. Those targets remain Antares' schedule rather than completed milestones, and the gap between Mark-0 and a continuously operating power plant contains the hardest engineering work: extracting heat, converting it into electricity, managing the system autonomously and maintaining it for years.

Antares describes its R1 design as a factory-produced, sodium heat-pipe-cooled reactor using TRISO fuel and a closed nitrogen Brayton cycle. Antares lists an output range of 100 kilowatts to 1 megawatt and an operating period of more than six years between refueling. The Army has not said whether the Fort Bragg configuration will match those specifications.

Janus will test the distinction in public. The Army is buying sustained operation at an active installation, where a reactor must integrate with an existing microgrid, meet security requirements and remain available when civilian infrastructure fails. Antares' June experiment proved that its core physics worked. Fort Bragg requires Antares to turn that core into a utility.

The military market leaves the hard parts intact

Bramble's defense-first strategy gives Antares an unusually committed initial buyer. The military values years of onsite power, limited refueling and reduced dependence on diesel supply chains. Those requirements can support early reactors before advanced nuclear reaches the economics needed for ordinary commercial electricity markets.

The strategy also concentrates Antares' near-term fortunes around government timelines, milestone reviews and site approvals. Fort Bragg will require work on construction, grid integration, security, decommissioning and fuel disposal. The final waste disposition pathway remains an open question.

A market beyond military installations carries another regulatory test. The Nuclear Regulatory Commission is developing proposed Part 57, a licensing framework intended for commercial nuclear power reactors including microreactors. The resulting rules will affect whether Antares can turn a defense production line into a repeatable commercial business.

For Bramble, Fort Bragg is the clearest validation yet of the choice to build around defense from Antares' first day. The selection moves Antares from a controlled reactor experiment toward a customer site operating under a government timetable. Its next proof point arrives in 2027, when Antares plans to show that the reactor can produce useful electricity. Janus will determine whether it can keep producing that electricity when the Army needs it.