Radiant Industries Inc., a pioneering startup developing portable, mass-produced nuclear microreactors, said Wednesday it has raised more than $300 million in a late-stage funding round.

Draper Associates and Boost VC led the Series D round, and additional existing investors also joined the company’s newest capital raise, coming six months after its Series C.

As artificial intelligence continues to drive ever-increasing demand for power generation, data centers and large campuses are drawing on a broader mix of energy sources. Nuclear reactors offer a distinct advantage: They are always-on systems, meaning that even if the local power grid fails, they continue producing energy. This makes them an alternative to expensive diesel backup generators.

“Micro-scaled nuclear, mass produced for the first time ever, can transform how the public thinks about nuclear energy,” said Radiant founder and Chief Executive Doug Bernauer.

When Radiant says “micro-scaled,” the company is referring to semi-trailer-truck-sized reactors. Though the scaffolding and housing may appear large, they’re extremely small when compared with traditional nuclear facilities.

The reactors themselves are factory-built and readily transportable, making them mobile enough to be hauled wherever power is needed.

“This funding enables us to build our factory and keep to our DOME schedule, where we will achieve self-sustained chain reaction on a reactor designed by, built by, fueled by and operated by Radiant alongside our partners at the Idaho National Lab,” Bernauer added.

DOME is Idaho National Laboratory’s Demonstration of Microreactor Experiments facility; Radiant plans to furnish and activate its first reactor there next year. The Kaleidos Demonstration Unit will be tested at DOME in the summer of 2026, making it the first reactor designed in the United States to be tested at INL’s facility.

The company designed its reactors to provide power coverage for critical infrastructure and disaster response, where power may not always be reliable. Remote facilities, defense operations and other infrastructure could benefit from always-on power generation that can be delivered by truck.

“Radiant is a leader in the American nuclear startup space, designing reactors essential to our prosperity and security,” said Rachel Slaybaugh, partner at DCVC and a former program director at the Department of Energy’s ARPA-E, where she created the nuclear fission program.

The company has already secured a deal with Equinix Inc., a global data center and interconnection provider, to purchase 20 reactors. The company has also signed delivery contracts with the U.S. military.

Radiant announced that it will begin building and mass-producing its portable reactors in Oak Ridge, Tennessee. The factory, called R-50, is a nod to the site’s historical role in the Manhattan Project, which conducted secret nuclear production during World War II. The S-50 Project focused on producing enriched uranium; in today’s terms, R-50 reflects Radiant’s goal of delivering 50 reactors per year.

Large enterprises have increasingly invested in nuclear power, including small and modular reactors, to provide ancillary, always-on energy for data center campuses. Amazon.com Inc., Microsoft Corp. and Google LLC have all pursued nuclear power to support their facilities. Microsoft, in particular, is set to benefit from the reopening of the Three Mile Island nuclear plant by Constellation Energy Generation LLC, which will supply power to the company’s nearby data centers.

Even President Trump is trying to get into the game, in a deal announced today. His social media company Trump Media and Technology Group said it’s merging with TAE Technologies, a  company pursuing fusion power, whose viability is still uncertain.

Image: Radiant Industries