The Nuclear Regulatory Commission approved TerraPower's construction permit for Kemmerer Unit 1 on March 4, 2026, issuing the first commercial non-light-water reactor construction permit in more than 40 years and the first commercial-scale reactor permit in nearly a decade. TerraPower broke ground on the Natrium power plant in Kemmerer, Wyoming on April 24, 2026.
The Natrium reactor is a 345-MWe sodium fast reactor paired with a molten salt thermal storage system that can boost output to 500 MWe for more than five hours when the grid needs peak power. The design separates the reactor facility and the energy generation facility into two distinct islands, a configuration intended to reduce regulatory burden and accelerate construction.
The NRC completed its review five months ahead of the original timeline. The permit is the first to use a fully risk-informed, performance-based licensing basis for a power reactor, applying the Licensing Modernization Project methodology endorsed by the NRC in 2020. NRC Chair Ho Nieh called the approval a historic step forward for advanced nuclear energy and said it reflects improvements in the efficiency of the agency's review process.
TerraPower CEO Chris Levesque said the company plans to reach commercial operation around 2030. The Kemmerer project is backed by the Department of Energy's Advanced Reactor Demonstration Program, which committed $3.2 billion across TerraPower and X-energy to accelerate commercial advanced reactor deployment.
Learn more about content strategy for energy sector