Radiant raises $300 million+ Series D toward portable nuclear energy at scale

The provision of long-lasting, affordable, reliable, and zero-carbon electricity in remote locations — whether for defense, disaster response, remote industries and communities, or critical infra­struc­ture — is a pernicious and increas­ingly acute problem faced by the electricity market. An excellent solution to that problem comes in the form of portable, 1‑MWe microre­ac­tors made by DCVC Climate portfolio company Radiant, whose Series C we led. We’re therefore very excited by today’s announce­ment (see Bloomberg coverage here) of Radiant’s $300M+ Series D (in which we partic­i­pated), which values the company at over $1.8 billion, a significant step up from the most recent fundraise.

In the past six months, the company has hit key milestones required for mass commer­cial­iza­tion. It announced that its Kaleidos reactor will, in Spring 2026, be the first reactor design to be tested at Idaho National Laboratory’s new Demon­stra­tion of Microre­actor Experiments (DOME) test bed. The series of tests will be conducted on the full-size, actual reactor design they are going to sell, generating rafts of data and operating experience and making it the first full-scale advanced reactor demon­strated in the U.S. On the regulatory front, the company is moving quickly, gaining key approvals and filing further submissions. Commer­cially, it has signed the first-ever deal for mass-manu­fac­tured nuclear reactors on a military base. The company joined the President’s Nuclear Reactor Pilot Program, part of the government’s effort to streamline reactor approval. It signed a deal to provide data-center giant Equinix with 20 reactors, and signed both the first contract with the Department of Energy for HALEU fuel and the first commercial contract for HALEU enrichment. All the while, the company has made key hires as it eyes the ground­breaking of its R‑50 factory in Oak Ridge, Tennessee. 

Radiant is a leader in the American nuclear startup space, designing reactors essential to our prosperity and security. Its superb leadership team is laser-focused on execution and regulatory certainty — as its outstanding results show. We applaud its team for marrying high ambition with high account­ability and high trans­parency, and for showing the way toward a new era of nuclear power that allows firm, clean power to get where it needs to get quickly.