The U.S. Nuclear Regulatory Commission (NRC) has officially issued a construction permit for TerraPower’s first Natrium reactor, known as Kemmerer Unit 1, to be built in Wyoming. This milestone marks a significant moment in nuclear energy development, as it is the first advanced, commercial-scale nuclear power plant to gain such approval in the United States.
Chris Levesque, President and CEO of TerraPower, emphasized the importance of the decision, stating, "Today is a historic day for the United States’ nuclear industry. We are beyond proud to receive a positive vote from the Nuclear Regulatory Commissioners to grant us our construction permit for Kemmerer Unit One."
The Natrium system combines a 345 MW sodium-cooled fast reactor with a molten salt-based thermal energy storage system. This innovative design, developed by TerraPower in collaboration with GE Vernova Hitachi Nuclear Energy, aims to provide enhanced reliability and flexibility. During times of high demand, the storage system can temporarily boost the plant’s output to 500 MW without disrupting the reactor’s base 345 MW capacity.
The plant's compact design is another key feature, requiring less space per unit of power compared to traditional nuclear reactors. TerraPower has allocated a total of 44 acres for the site, with 16 acres dedicated to the reactor's "nuclear island" component.
TerraPower initially filed its application for the Kemmerer Unit 1 construction permit in March 2024. Although the NRC originally planned a 27-month review process, the agency completed its evaluation in just 18 months. This accelerated timeline was attributed to a comprehensive application, swift responses to regulatory inquiries, and strong legislative backing.
According to the NRC, this is the first commercial reactor construction approval in nearly a decade and the first approval for a non-light water reactor in more than 40 years. "NRC staff finished their technical review of this new design in less than 18 months", the agency noted in a statement. The permit specifically authorizes nuclear construction activities, with a separate operating license required before the facility can commence operations.
The NRC issued its safety evaluation for the project in December 2025, followed by the final environmental impact statement in October 2025. Construction at the site is expected to begin in the coming weeks, with details on the specific timeline yet to be disclosed.
The Kemmerer Unit 1 project is part of the U.S. Department of Energy’s Advanced Reactor Demonstration Program, which seeks to fast-track next-generation nuclear technologies through public-private partnerships. If completed on schedule by 2030, this facility will become the first utility-scale advanced nuclear power plant in the country.
The project also reflects broader trends in energy infrastructure development, particularly as electricity demand surges. A ConstructConnect report highlighted a record $25.2 billion in U.S. data center construction starts in January 2026 alone, with an additional 65 projects worth $92.1 billion potentially starting in the next six months. To support this rapid expansion, U.S. developers plan to add 86 gigawatts of new utility-scale generating capacity to the grid in 2026.
For the construction industry, TerraPower’s approval signals new opportunities in mobilization, procurement, and long-term energy sector projects. With construction professionals anticipating robust bidding pipelines, the Kemmerer project serves as a key example of innovation meeting energy demands to support economic growth.
As TerraPower moves forward with Kemmerer Unit 1, the project represents a vital step toward diversifying the U.S. energy landscape, combining advanced nuclear technology with flexible power generation. If delivered as planned, the facility will showcase the potential of next-generation reactors to contribute to a sustainable energy future while meeting the country’s growing power needs.
