Antares Nuclear, Inc. (formerly Antares Industries, Inc.) is a Torrance, California-based startup building factory-produced fission microreactors for defense, space, and undersea missions. Its R1 design delivers 100 kWe to 1 MWe for 6+ years without refueling - enough for roughly 750 homes - using TRISO coated-particle fuel in a prismatic graphite core, sodium heat pipes for passive heat transfer, and a closed nitrogen Brayton cycle for power conversion. Founded in 2023 by CEO Jordan Bramble (previously White House OMB) and co-founder Julia DeWahl (previously Starlink business operations at SpaceX, now a director rather than an operating executive), the company took its Mark-0 reactor critical at Idaho National Laboratory on 4 June 2026 under the DOE Reactor Pilot Program, the first privately developed non-light-water reactor to achieve criticality in the United States in more than four decades and the first novel reactor to go critical at INL in over 50 years. Weeks later it raised a $470M Series C ($370M equity plus $100M debt) co-led by Paradigm and Caffeinated Capital, bringing total capital raised to roughly $604M across seed ($8M, 2023), Series A ($30M, 2024), Series B ($96M, 2025), and Series C. Antares was the first U.S. microreactor program to receive a HALEU allocation and holds a long-term HALEU supply agreement with Urenco. In April 2026 the Department of the Air Force and Defense Innovation Unit named it one of three Advanced Nuclear Power for Installations finalists and paired it with Joint Base San Antonio, Texas (Radiant drew Buckley Space Force Base, Colorado and Westinghouse Government Services drew Malmstrom Air Force Base, Montana); ANPI aims to have at least one advanced reactor operating on an Air Force installation by 2030, while Executive Order 14299 directs a reactor at a domestic military installation by 30 September 2028. Its engineering bench includes Chief Nuclear Officer Rian Bahran and Chief Engineer Mark Massie, working out of a 322,000 sq-ft headquarters facility, Antares Prime, with additional sites in Idaho Falls, Idaho and Aiken, South Carolina. No post-money valuation has been disclosed at any round.

Company Profile

Founders & Key People

Investors

Products

• R1 microreactor (100 kWe to 1 MWe, 6+ year core life, ~750-home equivalent)
• Mark-0 demonstration reactor (Idaho National Laboratory, critical 2026-06-04)
• Mark-1 electricity-producing prototype (targeted 2027)
• TRISO coated-particle fuel in a prismatic graphite core
• Sodium heat pipes and high-temperature thermal management
• Closed nitrogen Brayton-cycle power conversion
• Graphite/boron-carbide control drums with independent actuators

Competitors

nuclearenergydeep-techmicroreactordefensespaceTRISOHALEU

Private-company numbers are not real-time. Reflects publicly disclosed valuations from press releases, news reports, and tender offers as of recent date. Refreshed quarterly.