First sodium-cooled Natrium nuclear reactor receives construction permit in the US

The US nuclear regulator has issued a construction permit for the Natrium advanced nuclear reactor project at the Kemmerer power plant. The 345 MW sodium-cooled fast reactor uses a molten salt energy storage system, allowing it to increase output to as much as 500 MW for several hours. TerraPower began preparatory work two years ago and can now begin official construction. The unit is expected to enter service in 2030.

US company TerraPower announced that it had received a construction permit for its Natrium nuclear reactor from the Nuclear Regulatory Commission (NRC). The first commercial sodium-cooled fast reactor will be built at the Kemmerer site in the state of Wyoming. The reactor, with an electrical capacity of 345 MW, features a molten salt-based energy storage system and can temporarily increase its output to as much as 500 MW.

“Today is a historic day for the US nuclear industry. We are incredibly proud to have received a positive decision from the nuclear commissioners granting a construction permit for the first unit at the Kemmerer power plant. This is the first modern, commercial-scale nuclear power plant to receive this permit,” said TerraPower CEO Chris Levesque.

TerraPower applied for a construction permit in March 2024, and the NRC began its formal review in May 2024. Construction crews began preparatory work in June 2024, and nothing now stands in the way of official construction. The Kemmerer project is part of the US Department of Energy’s Advanced Reactor Demonstration Program.

“We have spent thousands of hours of work to achieve this significant milestone. We plan to begin construction of the power plant in the coming weeks and look forward to bringing the first sodium reactor and energy storage system to market,” Levesque added.

Advanced nuclear reactor to enter service within 5 years

Sodium-cooled fast reactors are classified as so-called Generation IV nuclear reactors. TerraPower, founded and chaired by Bill Gates, is developing the Natrium project in partnership with GE Hitachi. The company is also targeting markets beyond its home country with its reactor design, which it submitted to the Generic Design Assessment (GDA) in the UK in February this year.

“This is a historic step forward for advanced nuclear energy in the United States and reflects our commitment to making timely and predictable decisions based on rigorous, independent safety reviews,” said NRC Chairman Ho Nieh.

TerraPower expects to complete Kemmerer 1 in 2030, making it the first advanced nuclear power plant at utility scale in the United States. The plant’s start-up is conditional on obtaining an operating licence from the NRC.