US Army picks five vendors for Janus microreactors

The United States Army has selected five vendors and five military installations for its Janus microreactor program, backed by up to $2.2 billion through fiscal 2031. Janus will test whether advanced reactors can deliver dependable power at bases, not merely reach criticality.

Key facts

• The Army selected five vendors for five initial installations.
• The program carries approximately $2.2 billion in planned government funding for fiscal 2027-2031, plus vendor capital.
• The Army expects more than 20 microreactors across Department of War installations if private-sector funding is included.
• The five sites are Fort Bragg, Fort Campbell, Fort Hood, Fort Benning and Fort Drum.
• The Army is pursuing a September 2028 target for operation of a first Army-regulated reactor on a military installation.

What happened

The Department of the Army said August 26 that Janus had selected Antares Nuclear for Fort Bragg, North Carolina; BWXT Advanced Technologies for Fort Campbell, Kentucky; General Atomics Electromagnetic Systems for Fort Hood, Texas; Radiant Industries for Fort Benning, Georgia; and Westinghouse Government Services for Fort Drum, New York. The agreements were developed with the Department of War Innovation Unit, formerly the Defense Innovation Unit.

The Army described the awards as Other Transactions Authority-based agreements. That matters. The announcement is a procurement and development commitment, not evidence that five licensed reactors are ready to operate. Funding will be released through a milestone-based model, with vendors expected to hit technical goals before receiving government payments.

The Army says the government contribution could reach approximately $2.2 billion over fiscal years 2027 through 2031. Each contractor is also expected to contribute capital. The planned reactors will be contractor-owned and operated, while the Army works with serving utilities and privatized utility providers on site integration.

The announcement also sets a wider ambition: more than 20 microreactors could eventually be built and operated across Department of War installations when private funding is counted. The five named locations are the initial group, not the complete program footprint.

Why it matters

Military bases are a demanding test for small reactors. They need power that can remain available through grid disruptions, but a reactor installed on a base still has to satisfy nuclear safety requirements, security rules, fuel logistics and local utility constraints. Janus is trying to move advanced-reactor development beyond a short test run and toward sustained service.

That distinction is visible in the Army's own description of the program. Officials said they are looking for systems that can operate with high capacity factors for years, rather than technologies that can turn on briefly for a demonstration. In plain terms, the Army wants a power plant, not a science-fair milestone.

The selected designs also cover different technical approaches. World Nuclear News reported that Antares is pairing its sodium heat-pipe microreactor with TRISO fuel containing high-assay low-enriched uranium. BWXT's 20 MWe BANR is a high-temperature gas reactor using TRISO fuel. General Atomics' Tactical Energy System is a liquid-metal-cooled design with a baseline output of approximately 5 MWe, potentially scalable to about 20 MWe.

Radiant's Kaleidos is a transportable 1 MWe microreactor, while Westinghouse's eVinci uses heat pipes and is designed for continuous power for up to eight years without refuelling, according to the company description carried by World Nuclear News. Those output levels are not interchangeable. A base with a large industrial load will need a different system from a remote site that wants a compact, transportable unit.

Background

Janus follows two other federal efforts. The Department of Energy's Project Pele is developing and demonstrating a transportable microreactor for defense applications. DOE's Reactor Pilot Program is supporting first-of-a-kind advanced reactor demonstrations. The Army says Janus is intended to take the next step by tying private vendors to specific installations and operating requirements.

The program also connects to a White House deadline. Executive Order 14299 directed the government to pursue operation of an advanced nuclear reactor on a domestic military installation no later than September 30, 2028. The order and the Army announcement establish a target, not a completed licensing pathway or guaranteed commercial service date.

The practical hurdles are substantial. The companies must finish design work, qualify fuel and components, complete site-specific safety analyses, secure approvals and coordinate with utilities. The Army plans to regulate the reactors under its own authority, but that does not remove the need to demonstrate safety, protect nuclear material or manage waste and spent fuel.

NNN's SMR hub explains why reactor size alone does not determine deployment risk. The Kaleidos shipment to Idaho shows the kind of staged testing needed before a transportable design can support a customer schedule. NNN's coverage of the DOME microreactor test bed tracks the national-laboratory infrastructure now being used to collect operating evidence.

What's next

The next milestones are contractual and technical: vendor-specific designs, site studies, utility agreements, fuel plans and the first payments tied to completed goals. The Army will also announce additional service installations later, according to its release.

The date to watch is September 30, 2028, but the more revealing signal will come earlier. Janus will have to show that at least one selected design can move from development into construction and regulated operation without losing the reliability and cost discipline the program is supposed to prove. Until then, five awards mean five serious development tracks, not five operating reactors.