The company has just raised US$300 million to scale its commercialization efforts ahead of laying the foundation for its reactor factory in Oak Ridge, Tennessee, in 2026. That facility is expected to roll 50 Kaleidos microreactors off its assembly lines each year, ahead of shipments to customers in 2028.

The latest funding closely follows a $165-million Series C round in May. With that, Radiant has now racked up more than half a billion dollars to compete in the race to deliver a compact reactor.

That's a whole lot more than the $1.2 million it had picked up back in 2021 when we first came across its concept. Its fission reactors use TRISO fuel – ceramic-coated uranium particles that don't melt down – along with helium cooling systems for safe, stable operation. Digital twins of the reactors enable greater control, performance modulation to suit fluctuating energy demands, and performance and temperature distribution monitoring in real-time.

Radiant says its semi trailer-sized reactors arrive fully assembled, fueled, and tested wherever they need to be deployed as replacements for diesel generators; once dropped off from a delivery truck, it can begin producing power the next day, along with 1.9 MW of thermal power for industrial heating applications. A fleet monitoring system allows for daisy chaining hundreds of units together. And when its fuel is depleted after five years of use, the entire container can be shipped back for refueling.

The reactors are suitable for use on army bases, remote communities, disaster areas, and energy-hungry data centers. In fact, Radiant signed an agreement in August to deliver one to a US military base in 2028; it also inked a deal with Equinix, which operates data centers, to supply dozens of reactors for its facilities.

The Kaleidos will see a fueled test using high-assay low-enriched uranium next year, making it the first new commercial reactor design to be trialed in the US in over 50 years. Only four other firms in the country are cleared to use this fuel, so Radiant is in pretty exclusive company.

To that end, the startup is set to put together a Kaleidos demo unit for testing at Idaho National Laboratory's Demonstration of Microreactor Experiments (DOME) research facility in the city of Idaho Falls.

While $525 million seems like more than enough money to figure out how to mass produce small reactors, it's worth noting that Radiant is up against formidable well-funded rivals in this venture across the country, including Last Energy and Antares Nuclear. The race to meet the US Department of Energy Reactor Pilot Program's deadline of having a reactor achieving criticality by July 4 next year is on.