The US Nuclear Regulatory Commission issued a construction permit for TerraPower’s Kemmerer Power Station Unit 1 in Wyoming on 9 March 2026.
The decision allows construction of the nuclear portion of the project. It does not authorize the plant to operate. TerraPower will need to apply separately for an operating licence before loading fuel or running the reactor.
What is being built
The NRC describes the project as a demonstration of TerraPower and GE Hitachi’s Natrium sodium fast-reactor technology. The proposed reactor has an electrical output of 345 megawatts and is paired with an energy-storage system designed to increase output temporarily.
The project is supported by the US Department of Energy’s Advanced Reactor Demonstration Program and is planned for a site near an existing coal-fired power station in Lincoln County.
Why the permit matters
The construction permit is an important regulatory milestone for advanced nuclear technology in the United States. It will test whether a commercial sodium-cooled design can progress from demonstration funding to construction and, eventually, licensed operation.
Its contribution to future electricity supply will depend on construction progress, costs, later operating approval and the performance of the completed plant. Those questions cannot be answered by the construction permit alone.
