TerraPower develops Natrium sodium‑cooled reactors that operate at a steady state and store heat in molten sodium to enable dispatchable output when demand rises. The Natrium design intentionally uses excess sodium to heat and store energy, allowing steam turbines to draw from the stored heat rather than ramping the reactor. A completed Natrium reactor is designed to generate 345 megawatts, and its thermal storage system is designed to produce up to 500 megawatts for more than five hours. The company shifted from an earlier reactor design to pursue Natrium and began building its first commercial plant in Wyoming in June 2024, though it does not yet have reactor approval and expects permits sometime next year. TerraPower claims it can complete a reactor within three years after the first batch of concrete is poured, but the Associated Press reported project costs could reach $4 billion, roughly half of which might be shouldered by the Department of Energy. A new $650 million funding round will support construction of the first commercial power plant. TerraPower develops advanced nuclear energy technologies and nuclear medicine solutions, including the Natrium™ demonstration plant and the TerraPower Isotopes (TPI) program. The company is constructing the Natrium demo plant at a retiring coal facility in Wyoming and is supported by the U.S. Department of Energy’s Advanced Reactor Demonstration Program (ARDP). Part of the ARDP award requires a 50% match of project costs, up to $2 billion, and TerraPower says the new funding will support current implementation efforts. TPI is advancing next-generation isotopes and has unique access to Actinium-225 for pharmaceutical development. TerraPower emphasizes global deployment of its technologies and collaborations between public and private sectors. The company will remain privately held. TerraPower, a Seattle-based spinout of Intellectual Ventures (founded by Nathan Myhrvold), is developing traveling-wave reactors that generate electricity using much smaller amounts of enriched uranium combined with recycled uranium from existing plants. The company says its recycling reactors could run on their own byproducts for many more years than current reactors, potentially reducing hazardous waste and long-distance fuel shipments. The technology is not yet commercialized and the company describes the recent funding as a stepping stone toward a working commercial reactor. TerraPower aims to have a demonstration-scale reactor up and running within about 10 years. Its long-term, manufacturing-heavy ambitions run counter to recent cleantech investing trends that favor capital-efficient plays. The company has attracted high-profile backers and interest from potential partners such as Toshiba.

Total raised

$1.4B

Funding rounds

3

Latest round

Equity

Latest activity

Jun 2025