Natrium sodium-cooled pilot plant receives first major US licensing approval.
The US Nuclear Regulatory Commission (NRC) has authorised its staff to issue a construction permit for TerraPower advanced nuclear reactor plant near Kemmerer in the state of Wyoming.
The NRC said in a statement that the permit will allow TerraPower subsidiary US SFR Owner to begin building Kemmerer power station Unit 1, which uses the company’s proprietary Natrium 345-MW sodium-cooled reactor technology.
According to the NRC, the decision marks the first approval for construction of a commercial nuclear reactor in the US in nearly a decade and the first for a non-light-water reactor in more than 40 years.
NRC chairman Ho Nieh said the decision reflects the regulator’s commitment to delivering timely and predictable decisions based on independent safety reviews.
The commission authorised its Office of Nuclear Reactor Regulation to issue the permit after concluding that the agency’s technical and environmental reviews were sufficient to support the necessary regulatory findings.
TerraPower applied in March 2024 to build the plant near the retired Naughton coal plant in Kemmerer. The NRC accepted the application for review in May 2024.
The company, founded by Bill Gates, is developing the Natrium technology which combines a 345-MW sodium-cooled fast reactor with a molten salt-based storage system, capable of increasing output to 500 MW during peak demand.
TerraPower's president and chief executive, Chris Levesque called the decision “a historic day for the US’ nuclear industry.”
The company said the NRC had initially set a 27-month review schedule but streamlined the process in 2025, citing a complete application, the company’s “responsiveness” to regulator questions, the “dedication of NRC staff”, congressional support through the Nuclear Energy Innovation and Modernisation Act and executive orders issued by Donald Trump supporting nuclear energy.
According to the company, the review was completed in about 18 months.
The NRC published its final environmental impact statement for the project in October 2025 and a safety evaluation in December 2025.
However, the NRC said before the plant can begin operation, TerraPower must submit a separate operating licence application that would require further NRC approval.
TerraPower began non-nuclear construction activities at the Kemmerer site in July 2024.
The project is being developed under the US Department of Energy’s Advanced Reactor Demonstration Programme (ARDP), a public-private partnership aimed at accelerating deployment of next-generation nuclear technologies.
The DOE has a seven-year, $2bn (€1.7bn) agreement to fund the project, while TerraPower is matching this investment dollar-for-dollar for a total cost estimated at about $4bn. The agreement was signed in 2021.
