The NRC unanimously voted to issue a construction permit to TerraPower's subsidiary US SFR Owner on March 4, 2026 — the first commercial non-light-water reactor construction permit in more than 40 years and the first commercial reactor construction permit in nearly a decade. TerraPower submitted its Part 50 application in March 2024 (docketed May 2024). The NRC completed its safety review in December 2025, eight months ahead of its initial August 2026 target and 11% under budget. TerraPower began nuclear-related construction on April 24, 2026. TerraPower CEO Chris Levesque: "This is a historic day for the United States' nuclear industry." The Natrium is a 345 MWe sodium-cooled fast reactor with a molten salt energy storage system enabling flexible output of up to 500 MWe. Site: Kemmerer Power Station, Kemmerer, Wyoming, adjacent to the retiring Naughton coal plant.