Radiant Nuclear Raises Over $300 Million Amid Booming Nuclear Startup Investment

Radiant Nuclear announced today that it has raised more than $300 million, just one day after Last Energy reported raising $100 million. This follows a series of significant investments in the nuclear sector, including X-energy's $700 million raise three weeks ago and Aalo Atomics' $100 million in August. Even Radiant itself raised $165 million just six months ago.

Given this string of funding rounds, it's worth questioning whether the nuclear industry is experiencing a bubble. Investment in nuclear technology has closely mirrored the data centre boom. With AI requiring vast amounts of electricity, tech companies and data centre developers have been rushing to secure power from various sources, including nuclear fission and even supersonic jet engines.

As long as the demand for power from tech companies continues to rise, interest in nuclear energy is expected to remain strong. However, the market could thin in the next year or two if these startups fail to meet their ambitious goals, many of which include launching their first reactors within the following year.

Some startups may manage to delay challenges by relying on early-stage, hand-built reactors, but many of these companies are betting on mass manufacturing to make fission cost-competitive. While reaching criticality—the point at which a nuclear reaction is self-sustaining—is a key milestone, many struggle to replicate their designs at scale.

This doesn't mean Radiant won't succeed — the company could very well reach its goals. Still, it's part of a long list of nuclear startups that have announced eye-catching fundraisers in recent months, leading some to wonder if the industry is getting too frothy. In markets like these, the "B-word" (bubble) is bound to be mentioned.

Radiant's latest funding 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 funding values Radiant at over $1.8 billion. The company's previous investors include Andreessen Horowitz, DCVC, Giant Ventures, and Union Square Ventures.

Radiant is a work-developing microreactor capable of generating 1 megawatt of electricity, which can be delivered via a semi-truck. The reactor will be cooled by helium and equipped with sufficient TRISO fuel, carbon and ceramic-coated graphite, and uranium beads, designed to withstand meltdowns and last for five years before refuelling.

The startup aims to replace diesel generators at commercial and military sites. Customers will have the option to purchase the units outright or enter into a power-purchase agreement. Once the reactor's 20-year lifespan expires, Radiant will handle the unit's removal.

Like many other nuclear startups, Radiant is targeting data centres as one of its first customer segments. The company signed a deal in August with data centre developer Equinix to supply 20 of its reactors.

Radiant is currently constructing a demonstration reactor at the Idaho National Lab, with plans to begin testing in the summer of 2026. Many nuclear startups are on a similar timeline, which was set by the Trump administration's goal of having three reactors achieve criticality by July 4, 2026. Radiant is one of 11 companies selected for this program, which accelerates approval timelines without providing grants or loans.

Correction (1:20 pm ET): Radiant's reactor will be refuelled once every five years, not every month as previously stated.