Another day, another nuclear startup scores another nine-figure round.
Radiant Nuclear announced today that it has raised more than $300 million, just one day after Last Energy announced 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 series of investments, it seems natural to wonder if the nuclear world is in a bubble. Investment in this technology has gone hand in hand with the data center boom. AI requires vast amounts of electricity, and tech companies and data center developers are scrambling to secure supply from a variety of sources, from nuclear fission to supersonic jet engines.
As long as high-tech companies’ demand for electricity continues to grow, interest in nuclear power is likely to remain strong. But if startups don’t deliver on their promises, there could be a shake-up in the sector over the next year or two, much of which revolves around starting up the first reactors next year.
Some startups may be able to buy time after that. The world’s first nuclear reactor could be built by hand, but many nuclear startups are based on the idea that mass production will make nuclear fission more cost-competitive. You may succeed in reaching a critical point, but you may stumble when trying to replicate your design.
This doesn’t mean Radiant falls into that category. It may be quite successful. Rather, it just happens to be the latest in a long list of nuclear startups to announce impressive funding in recent months. When the market heats up, the B word always comes 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. The company 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 that can generate 1 megawatt of power that can be delivered via semi. It will be cooled with helium and carry enough TRISO fuel (carbon- and ceramic-coated beads of graphite and uranium designed to make it more resistant to meltdown) to last five years before refueling.
The startup aims to replace diesel generators in commercial and military facilities. Customers can purchase units directly or enter into a power purchase agreement. The company plans to retire the reactor when it reaches its 20-year service life.
Like many nuclear startups, Radiant is targeting data centers as some of its first customers. In August, the company signed a contract with data center developer Equinix to supply 20 nuclear reactors.
First, Radiant is building a demonstration reactor at the Idaho National Laboratory and hopes to begin testing in the summer of 2026. Many nuclear startups are on a similar timeline, set by the Trump administration’s goal for three nuclear reactors to reach criticality (the moment a nuclear reaction becomes self-sustaining) by July 4, 2026.
Radiant is one of 11 companies selected for the program, which does not offer government grants or loans, but instead accelerates approval timelines.
Correction 1:20pm ET: Radiant’s reactors will be refueled once every five years, not every few months as previously stated.
