Atomic Frontlines: Antares Scores $470M to Build Micro Nuclear Reactors for the Military

Nuclear startup Antares Nuclear raised $470 million to build small modular reactors for United States military bases. Paradigm and Caffeinated Capital led the Series C funding round, with participation from Industrious Ventures, Point72 Ventures, and Shine Capital. The financing package includes $370 million in equity along with $100 million in debt, bringing total funding for Antares to $604 million.

Antares designs small modular reactors capable of generating between 100 kilowatts and 1 megawatt of electricity. A single one-megawatt unit produces enough continuous power to run up to 750 homes. These compact micro-reactors use TRISO fuel, which encases uranium inside protective layers of carbon and ceramic. The billiard-ball-sized fuel spheres can withstand extreme heat without melting. Operators cool the system using gases like helium or molten salts rather than traditional high-pressure water loops.

The company achieved critical milestone progress on June 4 when its demonstration reactor, named the Mark-0, reached criticality at the Idaho National Laboratory. Antares now stands as one of three finalists in the Pentagon Advanced Nuclear Power for Installations program. That government initiative tests small modular reactors on Air Force bases in Colorado and Montana. Antares aims to bring its first electricity-producing reactor online next year, with full military deployments planned for 2028.

Investor interest in nuclear fission continues to soar across the tech sector. Artificial intelligence data centers require massive amounts of continuous power, driving demand for clean, reliable baseload electricity. Other nuclear ventures have secured massive checks recently. X-energy raised $1 billion through an IPO, while startups like Radiant Energy, Standard Nuclear, and Last Energy each closed massive funding rounds over recent months.

Despite heavy investor backing, advanced nuclear startups face significant operational challenges before reaching commercial scale. The industry lacks a mature domestic supply chain for specialized reactor components and enriched fuel. Manufacturing reactors in factory settings can cut construction costs eventually, but building out production facilities takes years of capital and testing.

Early small modular reactors will also carry high power generation costs when entering commercial service in the early 2030s. Financial analysis from Lazard estimates early reactor power costs at roughly $214 per megawatt-hour. That price point makes nuclear power more expensive than almost every other electricity source except peak-demand gas turbines.

Because early commercial rates remain high, Antares focused its strategy on government contracts. The military values energy security, grid independence, and continuous power at remote forward bases far more than low per-kilowatt rates. Securing stable defense contracts gives Antares reliable revenue while engineers work to scale production, streamline manufacturing, and lower energy costs for future commercial customers.