The Nuclear Regulatory Commission issued a construction permit on March 9, 2026, for TerraPower’s Natrium advanced reactor project at the Kemmerer Power Station Unit 1 site in Kemmerer, Wyoming. The approval marks the first time the agency has granted a construction permit for a commercial non-light-water power reactor. The permit follows an application submitted by TerraPower in March 2024 and accepted by the NRC in May 2024, which was the first docketing of a commercial non-light-water reactor application in more than 40 years.
What it means
The site is located near an existing coal-fired power plant. The Natrium reactor is a 345-megawatt electric sodium-cooled fast reactor equipped with a molten salt energy storage system, capable of boosting output to 500 megawatts. The NRC completed its safety review of the Kemmerer project in December 2025, finishing ahead of schedule and 11 percent under budget.
TerraPower broke ground on non-nuclear construction at the site in June 2024. The project is one of two supported by the U.S. Department of Energy through the Advanced Reactor Demonstration Program, receiving cost-shared funding for reactor design, licensing, fuel development and qualification, and the construction of two supporting facilities for fabricating fuel and testing sodium coolant technology. Once operational, Natrium will be the first commercial reactor in Wyoming. TerraPower must submit a separate operating license application to the NRC before the facility can begin operations. Project completion is expected in 2030.
Key facts
- NRC issued construction permit for Kemmerer Power Station Unit 1 on March 9, 2026.
- First NRC construction permit for a commercial non-light-water power reactor.
- TerraPower submitted application in March 2024; NRC accepted it in May 2024.
- NRC safety review completed in December 2025, ahead of schedule and 11 percent under budget.
- Non-nuclear construction broke ground in June 2024.
- Natrium reactor capacity: 345 megawatts electric; boostable to 500 megawatts with molten salt storage.
- Supported by DOE Advanced Reactor Demonstration Program with funding for design, licensing, fuel and two supporting facilities.
- Expected project completion: 2030.
Source: U.S. Nuclear Regulatory Commission news release