Posted on December 17, 2025
New round lets Radiant scale commercialization efforts after next year’s first reactor test.
EL SEGUNDO, CA – December 17th, 2025 – Radiant, a pioneer in portable, mass-produced nuclear microreactors, today announced that it has raised more than $300 million in a new round of funding.
This latest capital raise, coming just six months since closing its Series C, and put together in just a few weeks, will support the scaling of commercialization efforts as Radiant prepares to break ground early next year on its recently announced R-50 factory in Oak Ridge, Tennessee.
This new round, led by Draper Associates and Boost VC, also includes additional financial commitments from current investors, reinforcing their continued confidence in Radiant’s positioning in the microreactor space.
Micro-scaled nuclear, mass produced for the first time ever, can transform how the public thinks about nuclear energy.
said Doug Bernauer, CEO and Founder of Radiant. “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.”
Radiant continues to meet milestone after milestone as they remain on track for next year’s startup of its first reactor – the Kaleidos Demonstration Unit (KDU), at Idaho National Laboratory’s Demonstration of Microreactor Experiments (DOME) facility.
Radiant’s factory-built, transportable nuclear generators are designed to provide always-on power for defense, disaster response, remote industry, and critical infrastructure- applications where traditional energy systems fall short.
Radiant has delivered on their promises every step of the way,” said Tim Draper, Founder and Managing Partner of Draper Associates. “Portable nuclear power is going to provide the bulk of our incremental energy in the years to come and Radiant is executing with purpose not just towards turning on their first reactor, but building them at scale in months, not years.”
“Nuclear is the most important opportunity of our lifetime, and no team is as focused on execution as Radiant,” said Adam Draper, Partner at Boost VC. “They are a force of nature, hitting every milestone on – or ahead – of time.”
“Radiant is delivering a new class of portable, micro-scale nuclear reactors that can provide reliable energy to places where traditional generation simply isn’t feasible,” said Mina Faltas, Founder and Chief Investment Officer at Washington Harbour Partners. “By moving a critical capability from development to real-world deployment, Radiant is building a resilient solution to energy gaps for warfighters operating on the edge. We’re proud to back a team building infrastructure that strengthens U.S. energy resilience and mission readiness.”
“This is what the West and its allies needs, and this is the type of team we back,” said Colin Anderson, Founding Partner, Friends & Family Capital and ex-CFO, Palantir. “The Radiant team has repeatedly delivered new capabilities, met schedule requirements, and kept costs competitive. The focus is on energy resiliency that moves beyond prototypes to produce measurable operational effects.”
“In an industry fueled by more hype than HALEU, Radiant stands out as the exception,” said David Ulevitch, General Partner, Andreessen Horowitz. “The team’s ruthless focus on execution and bringing their mission to life through commercial success separate them from the rest of the pack.”
“We back sharp management teams with the rare ability to deliver at scale,” said Grant Hosking, Managing Partner at Align Ventures. “Radiant stands apart as the most compelling and execution-ready platform we’ve seen in next-generation energy infrastructure.”
“Radiant is a leader in the American nuclear startup space, designing reactors essential to our prosperity and security,” said Rachel Slaybaugh, Partner at DCVC; former Program Director at the Department of Energy’s ARPA-E, where she created the nuclear fission program. “Radiant’s superb leadership team is laser-focused on execution and regulatory certainty. DCVC is proud of Radiant’s continued success.”
As part of this latest capital raise, Radiant also received additional investment from Founders Fund, ARK Venture Fund, Chevron Technology Ventures, and others.
Today’s news is a capstone on what has been a massive year for Radiant. Here are just a few of the company’s wins since closing their last round of funding less than six months ago:Strengthened leadership through key hires: Radiant has brought on board some of the best and brightest from inside and outside the nuclear industry, including: Dr. Rita Baranwal, the former Assistant Secretary for Nuclear Energy, as Chief Nuclear Officer; Dr. Mike Starrett, as Chief Revenue Officer; and almost a dozen VP and Director hires across engineering, manufacturing, and supply chain organizations.
Selected by the U.S. Department of Energy to test at INL: Radiant was selected to conduct the first test of its Kaleidos microreactor, with testing scheduled to begin in Summer of 2026 – making it the first new U.S. reactor design to be tested at INL’s new DOME facility.
Quick progress on the regulatory front: From submission and approval of its Nuclear Safety Design Agreement (NSDA) to acceptance for review of its DOE Authorization Request for Kaleidos (DARK) to meet the intent of the Preliminary Documented Safety Analysis (PDSA), Radiant has made steady progress on the regulatory front to stay on track for this summer’s first test at INL.
Agreement designed to deliver nuclear microreactor to U.S. military base: Radiant signed the first-ever deal for mass-manufactured nuclear microreactors on a U.S. military base with the Defense Innovation Unit (DIU) and the Department of the Air Force.
Selection for New Reactor Pilot Program: Radiant was selected to join the President’s Nuclear Reactor Pilot Program, with the goal of being one of the first to utilize the Department of Energy’s streamlined approval process for deployment of new reactors.
Deal for 20 Kaleidos microreactors with Equinix: Radiant signed a deal – with deposits – with the world leader in digital infrastructure to purchase 20 reactors.
First company to sign a contract with DOE for HALEU fuel: Radiant became the first reactor company to sign a contract with the U.S. DOE for High-Assay Low-Enriched Uranium (HALEU) fuel for next year’s test at INL.
First binding commercial contract for HALEU enrichment: Radiant signed a deal – the first binding commercial contract by a U.S. advanced reactor developer for Western commercial HALEU enrichment services – with Urenco at a ceremony at the U.S. embassy in London.
Radiant factory announced in Tennessee: Radiant announced that they will be building the world’s first factory to mass-produce portable nuclear reactors in a spot where the nuclear industry began: Oak Ridge, Tennessee. The factory, called R-50, is a nod to the historical name of the site and the ambitious mission for it to scale production to 50 reactors per year within a few years of the beginning of production in 2028.
First reactor assembly begins: With delivery of the pressure vessel and the first order of nuclear-grade, American-made graphite extruded in over a decade, Radiant began assembly on its first nuclear reactor ahead of startup next summer at INL’s DOME facility.
For more information on Radiant and the Kaleidos generator, visit www.radiantnuclear.com.
About Radiant
Radiant is building the world’s first mass-produced nuclear generators that can go anywhere they’re needed, whenever they’re needed, and without constant refueling. The company’s first generator, Kaleidos, is a 1 MW failsafe nuclear microreactor. Founded in 2020, Radiant plans to test its first reactor in 2026, with initial customer deployments beginning in 2028. Radiant’s mission is to mass produce the most economical and reliable portable reactors in the world.
Contact
For media inquiries, contact Ray Wert at [email protected]