Radiant Raises $300 Million to Mass Produce 1 MW Nuclear Microreactors

Nuclear technology startup Radiant has raised more than $300 million in a new funding round to scale its commercialisation efforts and begin construction of its first factory in Oak Ridge, Tennessee, targeting production of 50 nuclear microreactors per year. The funding comes six months after the company raised $165 million in a Series C round.

Founded in 2020, California-based Radiant is developing Kaleidos, a 1 MW microreactor designed as a zero-emissions alternative to diesel generators for applications including remote communities, emergency responders and military installations. Kaleidos was selected by the US Department of Energy to be tested at the Idaho National Laboratory's Demonstration of Microreactor Experiments (DOME) facility, with testing scheduled for Summer 2026. The company aims to begin initial customer deployments in 2028 and to scale factory production to 50 reactors per year, breaking ground on the Oak Ridge facility early next year.

Radiant's microreactor approach targets a market segment that solar and wind energy cannot reliably serve, including remote off-grid locations, disaster response scenarios and defence applications requiring compact, continuously available power. The commercial viability of mass-produced microreactors, if demonstrated, could open new pathways for decarbonising remote power supply and reducing global reliance on diesel generation, which contributes significantly to GHG emissions in off-grid settings. For India, which has hundreds of millions of people relying on diesel backup power and remote communities without reliable grid access, microreactor technology could represent a longer-term decarbonisation option subject to regulatory and cost developments.

The new funding round was led by Draper Associates and Boost VC, with additional investment from Founders Fund, ARK Venture Fund, Chevron Technology Ventures and others. Radiant CEO Doug Bernauer said the funding will enable the company to build its factory and keep to its DOME test schedule, where the aim is to achieve a self-sustained chain reaction on a reactor designed, built, fuelled and operated by Radiant alongside Idaho National Lab partners. The company's progress over the coming two years, including the DOE DOME test results and factory construction milestones, will be closely watched by the wider nuclear energy sector.

Key figure — $300 million raised