Antares Secures $470M Funding to Develop Advanced Nuclear Reactors for US Defense Applications

Nuclear Power Startup Antares Nuclear Raises $470 Million for Small Reactors

Nuclear power startup Antares Nuclear announced on Monday that it has secured $470 million in funding to develop small reactors for U.S. military bases.

The Series C round, which was spearheaded by Paradigm and Caffeinated Capital and included contributions from Industrious Ventures, Point72 Ventures, and Shine Capital, highlights the increasing interest from investors in advanced nuclear startups. This interest has been fueled by the growing demand for new sources of power, particularly in light of the AI data center building boom. The Series C round consisted of $370 million in equity and $100 million in debt.

Antares has been working on a small modular reactor (SMR) capable of generating between 100 kilowatts and 1 megawatt of electricity, which is sufficient to power up to 750 homes.

Similar to many other advanced nuclear startups, Antares’ reactor utilizes TRISO fuel, a technology that encases uranium in carbon and ceramic shells. TRISO fuel has long been regarded as a safer alternative to traditional nuclear fuel. The small spheres of TRISO fuel can be cooled using gases like helium or molten salts, with the coating designed to prevent the fuel from melting in high-temperature reactors.

Antares recently achieved a significant milestone when its demonstration reactor, the Mark-0, reached criticality on June 4 at the Idaho National Laboratory.

The company is one of the finalists in the Pentagon’s Advanced Nuclear Power for Installations program, which aims to test SMRs on Air Force bases in Colorado and Montana. Antares plans to have its first electricity-producing reactor operational next year, with deployments at U.S. military installations scheduled for 2028.

Investor interest in nuclear power, particularly in fission, has been on the rise due to the surge in electricity demand driven by data center construction and the broader electrification of the economy. Several companies, including X-energy, Radiant Energy, Standard Nuclear, and Last Energy, have secured significant funding rounds in recent months.

Antares previously closed a $96 million Series B round in December, bringing its total funding to $604 million based on data from PitchBook.

Despite the enthusiasm from investors, advanced nuclear startups face challenges in commercialization, such as an underdeveloped supply chain in the U.S. and difficulties in scaling production. While many SMR startups highlight the benefits of mass manufacturing for cost reduction, these benefits typically take years to materialize, with no startup reaching that stage yet.

The first SMRs expected to come into service in the early 2030s may not be cost-competitive with most new power plants. According to Lazard, new SMRs could cost around $214 per megawatt hour, making them more expensive than all but the priciest gas turbines.

Antares has not disclosed its pricing strategy, but given market conditions, the decision to target contracts with the U.S. military, known for being less price-sensitive, makes sense.