Radiant Nuclear raises $300 million for its 1-megawatt semi-scale reactor

Another day, another nine-figure round for a nuclear startup.

Radioactive nuclear Today it said it had raised more than $300 million alone One day After Last Energy said it raised $100 million. Three weeks agoX-energy raised $700 million, and In AugustAalo Atomics raised $100 million. Heck, Radiant itself raised $165 million Just six months ago.

Given the flurry of investments, it seems reasonable to wonder whether the nuclear world is living in a bubble. Investment in technology has closely kept pace with the data center boom. Artificial intelligence requires huge amounts of electricity, and technology companies and data center developers have scrambled to secure supplies from sources ranging from nuclear fission to supersonic jet engines.

As long as demand for energy by technology companies continues to grow, interest in nuclear energy is likely to remain strong. But the field could be winnowed out 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 may be able to buy some time after that. The first reactors of their kind can be built by hand, but many nuclear startups are banking on the idea that mass manufacturing will make fission cost competitive. They may succeed in achieving significance but stumble when they try to replicate their designs.

None of this means that Radiant will fall into this category; It may work very well. Instead, the company happens to be the latest in a long list of nuclear startups to have announced eye-popping fundraising in the past few months. Anytime the market gets frothy, the B-word is bound to come 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. Radiant is valued at more than $1.8 billion. Previous investors include Andreessen Horowitz, DCVC, Giant Ventures and Union Square Ventures.

Radiant is developing a small reactor capable of generating 1 megawatt of electricity that can be delivered via semi-electric plants. It will be cooled with helium, and will contain enough TRISO fuel — carbon-ceramic-coated graphite-uranium pellets, designed to be more resistant to melting — to last five months between refuelings.

The startup aims to replace diesel generators at commercial and military sites. Customers will be able to purchase units outright or sign up for a power purchase agreement. When the reactor’s 20-year life is up, the company will move 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 an experimental reactor at Idaho National Laboratory, 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 achieving three reactors to criticality — the moment when a nuclear reaction becomes self-sustaining — by July 4, 2026.

Radiant is one of 11 companies selected for the program, which does not provide government grants or loans but instead speeds up approval timelines.