US nuclear firm to build 15 MW reactors a mile underground by 2026

Deep Fission, a US nuclear startup, has secured $30 million through a reverse merger with Surfside Acquisition Inc. to develop and deploy 15-megawatt mini nuclear reactors buried a mile underground. These reactors, designed to fit into 30-inch diameter boreholes, use pressurized water cooling and leverage proven technologies from nuclear submarines and traditional plants. By situating the reactors deep in bedrock, the company aims to enhance safety through natural shielding, reduce surface footprint, and protect against external threats. The design incorporates elements from nuclear, oil and gas, and geothermal industries, using off-the-shelf parts and low-enriched uranium to simplify supply chains. Deep Fission projects electricity costs of 5 to 7 cents per kilowatt-hour for its commercial systems. The company plans to complete its first pilot reactor by July 2026, supported by a Department of Energy (DOE) Reactor Pilot Program that aims to streamline permitting and accelerate deployment. Deep Fission has also signed a deal