Antares lines up $96 million to advance microreactor rollout

by Clarence Oxford
Los Angeles CA (SPX) Dec 12, 2025

Antares has raised $96 million in Series B financing to support development and deployment of its compact nuclear microreactors for defense and space customers. The round, led by Shine Capital with participation from Alt Capital, Caffeinated, FiftyThree Stations, Industrious and other investors, includes $71 million in new equity and $25 million in debt earmarked for equipment purchases, factory build-out and uranium procurement.

Antares CEO Jordan Bramble said the new capital will support the company's plans to deliver nuclear power systems for U.S. government partners. "This funding marks a major milestone for Antares," Bramble said. "We're months away from our first reactor demonstration, which will validate our control systems and neutronics models, develop our testing facility, and fabricate our fuel ahead of our upcoming full scale electricity producing prototype in 2027. We've raised the capital we need to mobilize to provide resilient energy for our partners at the Department of War (DoW) and NASA."

Founded just over two years ago, Antares has raised more than $130 million to date and is developing a 145,000-square-foot manufacturing complex in Torrance, California, designed to produce up to 10 microreactor units a year. The company has also secured contracts with the U.S. Air Force, U.S. Space Force, the Defense Innovation Unit (DIU) and NASA to advance technology maturation and demonstration.

Antares operates across sites in Torrance, California; Idaho Falls, Idaho; and Aiken, South Carolina, and currently employs about 60 staff. The company plans a low-power test reactor demonstration before July 4, 2026, followed by a first-of-a-kind electricity-producing demonstration unit in 2027, with production reactors targeted for deployment from 2028.

Shine Capital general partner Alex Hartz said Antares could become the first nuclear startup this century to bring a new fission reactor online. "No nuclear startup has turned on a fission reactor this century. Antares is poised to achieve this milestone in 2026, thanks to their design and licensing maturity, fuel supply chain, and swift progress in demonstrating the performance of its underlying components in partnership with Idaho National Lab and NASA. Antares' reactor will uniquely address needs across defense, space, and critical industries while also serving as a platform for scale-up to higher power."

During the summer, Antares and NASA conducted an electrically heated demonstration of the reactor system at Marshall Space Flight Center in Huntsville, Alabama, to evaluate thermal and operational behavior without nuclear fuel. In April, DIU selected Antares under the Advanced Nuclear Power for Installations program to supply nuclear power to Department of War installations.

In August, Antares received an allocation of High-Assay Low-Enriched Uranium fuel feedstock from the U.S. Department of Energy, a key step in securing fuel for advanced reactors. The company was also chosen for DOE's new reactor pilot program, which is intended to provide a faster pathway for demonstration and licensing.

In October, the U.S. Army launched JANUS, a program of record for advanced nuclear energy that targets reactors from kilowatt scale up to 20 MWe for defense applications. With the new funding, Antares plans to compete under JANUS to provide resilient power for critical Pentagon infrastructure and will also propose a system for NASA's Fission Surface Power program, which aims to deploy 100 kWe of nuclear power on the lunar surface by 2030.