Nuclear startup Deep Fission unveils second go-public attempt, raising fresh questions
Deep Fission, a US small modular nuclear reactor (SMR) startup, has announced its second attempt to go public. According to a TechCrunch analysis, the plan will proceed through a SPAC (special-purpose acquisition company) structure, valuing the company at approximately $800 million.
Deep Fission made its first public-listing attempt in 2024 but shelved the plan after technical issues with the SEC review process and unfavourable market conditions, opting to continue with private financing instead. The company closed a $120 million Series C round in early 2026.
The company's technical concept differs from conventional SMR approaches. The Deep Fission reactor operates as a pressurised water reactor inside a well bored one mile underground. The company argues that this approach offers advantages in both safety and cost. The reactor's output is designed for 15 megawatts of electricity.
On the US Nuclear Regulatory Commission (NRC) certification path, the company is still at the pre-design review stage. The NRC's process for approving new SMR designs typically takes 5 to 7 years. Deep Fission plans to bring its first commercial reactor online in 2029; sector analysts regard the timeline as optimistic.
TechCrunch reporter Tim De Chant outlines the key questions raised by the listing plan: 'The company has neither a certified reactor design nor operating revenue. The entire valuation rests on assumptions about the size of the SMR market over the next 10 years.'
For the SMR market, the International Energy Agency (IEA) 2024 report suggests a potential global market of $70 to $100 billion by 2035, but contingent on a significant increase in the number of reactors entering commercial service. There are currently four commercially operating SMRs worldwide: two in Russia, one in China and one in Canada (Ontario).
Deep Fission co-founder and CEO Liz Muller, in a response to TechCrunch, said: 'A SPAC structure offers the fastest path to capital-market access; in a market environment where the traditional IPO process takes a long time, this is a practical choice.' Muller emphasised that the company had received broad support from Khosla Ventures and Y Combinator in its previous Series C round.
Competition in the US SMR sector is intensifying. NuScale Power went public in 2022 but its shares fell 88 per cent after main customer UAMPS (Utah Associated Municipal Power Systems) cancelled the project in 2023. Other startups such as X-Energy, Oklo and TerraPower compete with different design approaches.
Wedbush Securities analyst Daniel Ives, quoted in the article, said: 'The long-term potential of the SMR sector is clear, but investors should be cautious about short-term listing valuations; the NuScale experience has been a memory affecting investor sentiment in the sector over the past three years.'
Deep Fission's announced SPAC merger partner is Northern Star Investment IV. The merger is expected to close in October 2026, contingent on the SEC process proceeding without delays. For investors, detailed analysis will become available after Northern Star and Deep Fission file their S-4 documents. This article is general information; independent financial advice is recommended for investment decisions.