Antares raises $370M Series C to field nuclear microreactors for US military bases
What's the deal? Antares Nuclear has raised $470 million in a Series C round to field microreactors small enough to power US military bases. The round breaks down as $370 million in equity and $100 million in debt, and was co-led by Paradigm and longtime backer Caffeinated Capital, with Point72 VenturesDealroom has a profile for this one. Try Dealroom →, Series B lead Shine CapitalDealroom has a profile for this one. Try Dealroom →, and Industrious VenturesDealroom has a profile for this one. Try Dealroom → also participating.
What's the endgame? The California startup, founded in 2023 by Jordan Bramble and Julia DeWahl, is developing its Mark-1 reactor to deliver up to 1 MW of power reliably for six-plus years without refueling — enough to keep a remote installation running off-grid without relying on vulnerable fuel supply chains.
Why now? In June 2026, Antares' Mark-0 reactor achieved criticality at Idaho National Laboratory under the Department of Energy's Reactor Pilot Program — the first privately developed non-light-water reactor to reach criticality in the United States in more than four decades, and the first of the program's cohort to get there.
The money trail: Antares had raised roughly $134 million before this round, including a $96 million Series B in December 2025 ($71 million in equity led by Shine Capital plus $25 million in debt) and a $30 million Series A in 2024. The Series C funds the path to a commercial, electricity-producing Mark-1 reactor at Idaho National Laboratory in 2027, with initial deployments to defense customers in 2028.
The customers: Antares has secured relationships with the US Department of Defense, the Department of Energy, NASADealroom has a profile for this one. Try Dealroom →, the Air Force, and the Space Force. In April 2026 the Air Force tapped it to deploy a prototype microreactor at Joint Base San Antonio under the Advanced Nuclear Power for Installations initiative. It operates a vertically integrated facility in Torrance, California.
The signal: The round ranks in the 98.6th percentile of all-time US deep tech Series C deals, a signal of how much capital is flowing into small-scale nuclear. Antares is targeting operational deployments on military bases by 2028 — among the earliest advanced reactor companies aiming for that milestone.
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