TerraPower

TerraPower was founded in 2006 (incorporated 2008) in Bellevue, Washington by Bill Gates, Nathan Myhrvold (former Microsoft CTO), and John Gilleland, a nuclear physicist. Gates, who had become deeply interested in the physics and potential of advanced nuclear reactors through conversations with nuclear scientists, co-founded the company on the belief that nuclear energy was the most viable path to abundant, affordable, carbon-free baseload power, but that the industry had stagnated because it never innovated beyond the Generation II light-water reactor designs of the 1970s. TerraPower was explicitly created to fund, develop, and commercialize next-generation reactor concepts that government and industry alone had not pursued at commercial scale. Chris Levesque, who joined in 2015, serves as President and CEO. Gates serves as board chairman.

TerraPower’s flagship product is the Natrium system — a 345 MWe sodium-cooled fast reactor integrated with a 1 GWh molten salt energy storage system, allowing it to dispatch up to 500 MWe for more than five hours when grid demand peaks. Unlike water-cooled reactors, sodium operates at atmospheric pressure and at temperatures far above water’s boiling point, enabling higher thermal efficiency and eliminating the risks of pressurized water leakage. The molten salt storage integration is unique among advanced reactor designs and makes Natrium capable of “load following” — ramping up and down to complement intermittent solar and wind on the same grid. The fuel is high-assay low-enriched uranium (HALEU), enriched to approximately 19% — higher than conventional reactor fuel but below the threshold for nuclear weapons.

TerraPower received up to $2 billion in cost-shared funding from the DOE’s Advanced Reactor Demonstration Program. It also received $830 million in private investment in a 2022 round led by Gates and SK Group (South Korea), bringing total capital raised to over $1 billion. In March 2026, TerraPower received the NRC construction permit for Kemmerer Unit 1 — the first commercial-scale advanced non-light-water reactor to receive such a permit in US history, and the first NRC construction permit of any kind issued since 2016.

TerraPower broke ground on the Kemmerer, Wyoming site in June 2024, adjacent to the retiring Naughton coal plant. The Natrium plant is expected to be operational by the early 2030s. Meta has signed an agreement for up to 8 Natrium reactors, and the project is widely seen as the most advanced large-scale advanced reactor program in the US. TerraPower is also co-developing a Molten Chloride Fast Reactor (MCFR) with Southern Company and the DOE.