Antares collects $96M for small nuclear reactor development

Antares, a nuclear power startup that designs small modular reactors, has fetched $96 million in Series B capital from investors to support the continued development of its technology.

Founded in 2023, the 60-employee company is pushing to build a factory in California that can build 10 scalable nuclear reactors per year. Antares is designing its R1 microreactor to produce between 100 kilowatts and 1 megawatt of electricity for both government and commercial application.

Shine Capital led the round announced Tuesday that also included participation from Alt Capital, Caffeinated, FiftyThree Stations and Industrious. The $96 million round consists of $71 million in new equity and $25 million in debt for capital expenditures, such as the factory buildout.

“This capital will be deployed toward hardware, subsystem testing, fuel fabrication, manufacturing, and the infrastructure required to turn on a reactor and lay the foundation for even more progress to come,” Antares’ chief executive Jordan Bramble wrote in a letter on the round. “We believe that you cannot decouple the design and build phase into a linear process, they must be iterative.”

Antares is aiming to conduct its first reactor demonstration before July 4 in order to prepare for a similar exercise involving an electricity producing unit the following year. That second demonstration is called Mark-0 and will occur at the Energy Department’s Idaho National Laboratory, one year ahead of the planned Mark-1 prototype.

The company touts having secured contracts with the Air Force, Space Force, Defense Innovation Unit and NASA to continue iterating the reactor technology.

For NASA, Antares worked under a Space Act Agreement during the summer to develop an electrically-heated and pipe-cooled prototype for the Marshall Space Flight Center.

Antares is also interested in NASA’s Fission Power Surface program, through which the agency wants to develop a reactor that can produce at least 100 kilowatts on the Moon’s surface.

In April, DIU selected Antares for a program to provide nuclear power for U.S. military installations. Then in August, the Energy Department provided a fuel feedstock to Antares and picked the company as one of 11 participants in a pathway program focused on new reactor demonstration and licensing.

“No nuclear startup has turned on a fission reactor this century,” said Alex Hartz, general partner at Shine Capital. “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.”