Another day, another nine-figure round for a nuclear startup.
Radiant Nuclear said today that it has raised more than $300 million, just one day after Last Energy said it had raised $100 million. Three weeks ago, X-energy raised $700 million, and in August, Aalo Atomics raised $100 million. Heck, Radiant itself raised $165 million just six months ago.
Given the string of investments, it seems reasonable to ask whether the nuclear world is in a bubble. Investment in the technology has tracked closely with the data center boom. AI requires tremendous amounts of electricity, and tech companies and data center developers have been rushing to secure supplies from sources ranging from nuclear fission to supersonic jet engines.
As long as tech companies’ power demands continue to grow, interest in nuclear is likely to remain strong. But there might be a winnowing of the field in the next year or two if startups don’t deliver on their promises, many of which revolve around starting their first reactor next year.
Some startups might be able to buy some time after that. First-of-a-kind reactors can be built by hand, but many nuclear startups are predicated on the idea that mass manufacturing will make fission cost-competitive. They might succeed at reaching criticality but stumble when they try to replicate their designs.
None of this is to say that Radiant will fall into that category; it may very well succeed. Rather, the company just happens to be the latest in a long list of nuclear startups that have announced eye-popping fundraises in the last few months. Anytime a market gets that frothy, the B-word is bound to pop up.
The new round was led by Draper Associates and Boost VC with participation from Ark Venture Fund, Chevron Technology Ventures, Friends & Family Capital, Founders Fund, and others. It values Radiant at more than $1.8 billion. Previous investors include Andreessen Horowitz, DCVC, Giant Ventures, and Union Square Ventures.
Radiant is developing a microreactor capable of generating 1 megawatt of electricity that can be delivered via semi. It will be cooled by helium and will have enough TRISO fuel — carbon and ceramic-coated beads of graphite and uranium that are designed to be more resistant to meltdowns — to last five months between refueling.
The startup is aiming to replace diesel generators at commercial and military sites. Customers will be able to buy the units outright or subscribe to a power-purchase agreement. When the reactor’s 20-year lifetime is up, the company will haul it away.
Like many nuclear startups, Radiant is targeting data centers as some of its first customers. The company signed a deal with data center developer Equinix in August to supply 20 of its reactors.
First, Radiant is building a demonstration reactor at the Idaho National Lab, which it hopes to begin testing in the summer of 2026. Many nuclear startups are on a similar timeline, one set by the Trump administration’s goal of three reactors achieving criticality — the moment when a nuclear reaction is self-sustaining — by July 4, 2026.
Radiant is one of 11 companies selected for that program, which doesn’t provide government grants or loans but instead speeds approval timelines.
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