Deep Fission, a US-based advanced nuclear energy company placing small modular reactors in boreholes underground, has raised $30m (€25m) in a heavily oversubscribed private placement as it begins efforts to build a pilot reactor with the goal of completion in 2026.

Deep Fission also announced it has gone public through a reverse merger transaction with Surfside Acquisition. As a result of the deal, Surfside Acquisition, a special purpose acquisition company, has merged with the operational company. The new entity will retain the name of Deep Fission.

This development comes after the US Department of Energy (DOE) recently selected California-based Deep Fission to participate in president Donald Trump’s advanced reactor pilot programme, a DOE initiative launched in 2025 following Trump’s executive order to speed up the testing and development of advanced nuclear reactor technologies.