Nuclear startup Deep Fission goes public in a curious SPAC

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Nuclear fuel rods sit ready for insertion into a reactor.Image Credits:XH4D / Getty Images

1:08 PM PDT · September 8, 2025

Nuclear startup Deep Fission announced Monday that it has gone public in a reverse merger, netting the company $30 million.

No, it’s not 2021.

The startup is proposing to build small, cylindrical nuclear power plants and lower them into 30-inch diameter holes drilled one mile down into the Earth. By burying the reactors, the company hopes to solve several problems that plague current reactors, including concerns over meltdowns and potential terrorist attacks.

Deep Fission’s 15-megawatt reactors are cooled using pressurized water, the same type found in nuclear submarines and many existing power plants.

Earlier this year, Deep Fission inked a deal with data center developer Endeavor to build 2 gigawatts of underground reactors. 

As recently as April, the startup had been attempting to raise a $15 million seed round. In August, Deep Fission and nine other nuclear fission startups were selected to be a part of the Department of Energy’s Reactor Pilot Program, essentially a streamlined permitting process.

Under the terms of the reverse merger with four-year-old Surfside Acquisition Inc., the offering was priced at $3 per share, below the customary $10 that other SPACs target. The new entity will retain the Deep Fission name, and though its shares aren’t yet trading, it says it intends to quote on the OTCQB.

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The circumstances around the SPAC — the share price, the selected equity market, and the timing of the transaction — suggest that Deep Fission wasn’t able to raise cash from new or existing shareholders, who first capitalized the company with a $4 million check last year. 

The proceeds of the merger give the startup a bit more runway than its ill-fated seed round would have, but it also imposes SEC reporting costs for what is likely a small company operating in a very expensive sector. Deep Fission is hoping to start its first reactor by July 2026.

Tim De Chant is a senior climate reporter at TechCrunch. He has written for a wide range of publications, including Wired magazine, the Chicago Tribune, Ars Technica, The Wire China, and NOVA Next, where he was founding editor.

De Chant is also a lecturer in MIT’s Graduate Program in Science Writing, and he was awarded a Knight Science Journalism Fellowship at MIT in 2018, during which time he studied climate technologies and explored new business models for journalism. He received his PhD in environmental science, policy, and management from the University of California, Berkeley, and his BA degree in environmental studies, English, and biology from St. Olaf College.

You can contact or verify outreach from Tim by emailing tim.dechant@techcrunch.com.

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