TerraPower was founded in 2008 by Bill Gates and a team of nuclear scientists with a singular mission: prove that advanced nuclear energy could be safe, affordable, and deployable at scale. Headquartered in Bellevue, Washington, the company is developing the Natrium reactor — a 345 MWe sodium-cooled fast reactor paired with molten salt energy storage that allows it to flex output like a battery. In March 2026, TerraPower became the first company in US history to receive a construction permit for a non-light water advanced reactor, for their Kemmerer, Wyoming site on the footprint of a retiring coal plant. The project is backed by the DOE Advanced Reactor Demonstration Program, SK Group ($250M), and Bill Gates through Cascade Investment. TerraPower is also developing a molten chloride fast reactor and a medical isotope production program through TerraPower Isotopes. Construction target: first power by 2030.