TLDR
- Antares Nuclear raised $470 million in Series C funding, split between $370 million equity and $100 million debt
- The round was co-led by Paradigm and Caffeinated Capital, with Point72 Ventures and others participating
- Antares achieved a self-sustaining fission reaction in June 2024, the first privately developed non-light-water reactor to do so in the US in over 40 years
- The company plans to deploy its first reactors to US Air Force installations by 2028
- Its Mark-1 reactor, which will generate electricity, is expected to be ready in 2027
California-based nuclear startup Antares Nuclear has raised $470 million to build small reactors for US military bases. The funding round was co-led by venture capital firms Paradigm and Caffeinated Capital.
California startup Antares Nuclear raised $470 million to advance plans to build tiny reactors aimed at supplying power to US military bases https://t.co/w5nw7IE3Im
— Bloomberg (@business) July 27, 2026
The raise includes $370 million in equity and $100 million in debt. Other investors in the round include Point72 Ventures, Shine Capital, and Industrious Ventures.
Antares was founded in 2023 and operates facilities in Torrance, California; Idaho Falls, Idaho; and Aiken, South Carolina. The company designs microreactors intended to run safely and without refueling for years at a time.
Last month, Antares reached a key technical milestone. Its Mark-0 reactor achieved criticality at Idaho National Laboratory, meaning it sustained a self-sustaining nuclear fission chain reaction.
That made it the first privately developed non-light-water reactor to reach that stage in the US in more than 40 years. The test produced a small amount of energy but did not generate electricity.
Mark-1 Reactor on Track for 2027
The next step is the Mark-1 reactor, which is designed to produce electricity. Antares expects it to be ready in 2027.
Initial deployments are planned for US Air Force installations in 2028. Antares has secured firm contracts to build reactors under the Pentagon’s Advanced Nuclear Power for Installations initiative.
A Trump executive order signed last year set a deadline of September 30, 2028, for the Pentagon to begin operating a reactor at a domestic military base. Antares is one of the companies working to meet that target.
Antares is also part of a US Energy Department program focused on speeding up nuclear power deployment. The technology, while advancing, has not yet been proven at commercial scale, and no microreactors are currently in service in the US.
Energy Demand Driving Nuclear Investment
A growing number of nuclear startups are racing to bring small reactors to market. Energy demand has been rising sharply, in part due to the growth of artificial intelligence infrastructure.
Nuclear companies are pitching their technology as a clean and reliable way to meet that demand. Microreactors are seen as a flexible option for remote or high-security locations like military bases.
Antares says its systems are designed to operate autonomously without on-site refueling. The company is now focused on moving from lab demonstration to fielded power systems.
With $470 million in fresh capital and a clear deployment timeline, Antares is among the better-funded startups in the microreactor space. Its next major test will be the Mark-1 system expected next year.
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