Radiant, a company developing factory-built, transportable nuclear microreactors, has raised more than $300 million in a new funding round to expand commercialization efforts and support construction of its planned R-50 manufacturing facility in Oak Ridge, Tennessee. The company said the raise was completed just six months after its Series C and was assembled in a matter of weeks.
The round was led by Draper Associates and Boost VC, with additional financial commitments from existing backers. Radiant also cited participation from Founders Fund, ARK Venture Fund, Chevron Technology Ventures, and other investors. The company positioned the financing as a key step toward scaling production of its Kaleidos nuclear generator, a 1 MW “failsafe” microreactor designed for always-on power in defense, disaster response, remote industry, and critical infrastructure settings.
Radiant said it remains on track to start up its first reactor, the Kaleidos Demonstration Unit, next year at Idaho National Laboratory’s Demonstration of Microreactor Experiments facility. The company highlighted the DOME program as a significant validation milestone. It said the new capital will help it maintain its schedule toward achieving a self-sustained chain reaction at the site alongside INL partners.
Beyond the demonstration plan, Radiant framed 2025 as a milestone-heavy year across talent, contracting, fuel supply, and regulatory progress. The company said it has added senior leadership, including former U.S. Department of Energy Assistant Secretary for Nuclear Energy Dr. Rita Baranwal as Chief Nuclear Officer and Dr. Mike Starrett as Chief Revenue Officer, as well as additional VP- and director-level hires across engineering, manufacturing, and supply chain.
Radiant also pointed to a series of commercial and government-related agreements it says support its path from test to deployment. These include selection by the U.S. Department of Energy to conduct the first Kaleidos test at INL beginning in summer 2026, an agreement with the Defense Innovation Unit and the Department of the Air Force tied to delivering a microreactor to a U.S. military base, selection for the President’s Nuclear Reactor Pilot Program, and a deal with Equinix for 20 Kaleidos units that the company said includes deposits.
On fuel and supply chain readiness, Radiant said it became the first reactor company to sign a contract with the U.S. DOE for High-Assay Low-Enriched Uranium for next year’s test at INL. It also announced what it described as the first binding commercial contract by a U.S. advanced reactor developer for Western commercial HALEU enrichment services, signed with Urenco. The company added that it has begun assembly activities for its first reactor following delivery of the pressure vessel and receipt of nuclear-grade, U.S.-made graphite.
Radiant said initial customer deployments are expected to begin in 2028, aligning with the company’s broader plan to ramp manufacturing at its planned Oak Ridge facility and scale production to 50 reactors per year within a few years of the start of production.
KEY QUOTES:
“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.”
Doug Bernauer, CEO and Founder, Radiant
“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.”
Tim Draper, Founder and Managing Partner, Draper Associates
“Nuclear is the most important opportunity of our lifetime, and no team is as focused on execution as Radiant.”
Adam Draper, Partner, Boost VC
“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.”
Mina Faltas, Founder and Chief Investment Officer, Washington Harbour Partners
“The Radiant team has repeatedly delivered new capabilities, met schedule requirements, and kept costs competitive.”
Colin Anderson, Founding Partner, Friends & Family Capital; ex-CFO, Palantir
“The team’s ruthless focus on execution and bringing their mission to life through commercial success separate them from the rest of the pack.”
David Ulevitch, General Partner, Andreessen Horowitz
“Radiant stands apart as the most compelling and execution-ready platform we’ve seen in next-generation energy infrastructure.”
Grant Hosking, Managing Partner, Align Ventures
“Radiant’s superb leadership team is laser-focused on execution and regulatory certainty.”
Rachel Slaybaugh, Partner, DCVC; former Program Director at DOE ARPA-E
