TerraPower Breaks Ground on Natrium Reactor Project in Kemmerer, Wyoming

TerraPower's $4 billion Natrium project in Kemmerer, Wyoming crossed from paperwork into dirt last week, with the company launching major excavation activities following the NRC's landmark March 4 construction permit, the first ever granted to a commercial advanced reactor in the United States.

The permit, issued to TerraPower's subsidiary US SFR Owner under the NRC's 10 CFR Part 50 framework, authorized nuclear-related construction activities on the Lincoln County site. TerraPower leadership announced that "major earth-moving will start in days" after the authorization cleared, pointing to months of preparatory, non-nuclear support facility work that gave the construction team practical site experience before full-scale excavation began.

The plant at the center of it all is a 345-megawatt sodium-cooled fast reactor paired with a molten-salt energy storage system. That combination is what separates Natrium from every operating commercial reactor in the country: liquid sodium handles heat transfer rather than water, enabling a passive cooling configuration. The molten-salt storage component can absorb and discharge energy to temporarily boost output to around 500 megawatts, decoupling generation from instantaneous demand in a way no light-water reactor can. The NRC's construction permit reflects genuine regulatory adaptation; this is the first commercial Generation IV design to clear that threshold in U.S. history.

TerraPower president and CEO Chris Levesque framed the moment directly at the groundbreaking ceremony. "The Natrium reactor is more than a design, it's a plant coming to life that will support both the clean energy transition and our historic energy communities," he said, adding that the technology would deliver "dispatchable carbon-free energy, gigawatt-scale energy storage, and long-term jobs to the Lincoln County community."

That last point carries particular weight in Kemmerer. The project sits on land previously occupied by a coal-generation facility, and TerraPower has built workforce continuity into its community strategy from the start. The company worked with IBEW to transition coal plant workers into nuclear construction and operations roles, a coal-to-nuclear handoff drawing national attention as a potential template for energy community transition. Regular town halls and coordination with local officials are also part of the engagement model, reflecting the sensitivity of siting a first-of-kind advanced reactor on a former fossil fuel footprint.

The permit arriving in March 2026 came roughly three months behind the NRC's revised end-of-2025 target, though the commission still completed its safety review five months ahead of its original schedule. The overall project completion has shifted to 2030, three years later than the timeline the Department of Energy established when it awarded the project funding under the Advanced Reactor Demonstration program. That $2 billion federal contribution, authorized through the Bipartisan Infrastructure Law, anchors the $4 billion total cost.

What the transition from permitting to active excavation actually signals is schedule credibility: long-lead component orders for sodium systems, intermediate heat exchangers, and molten-salt storage infrastructure are now converging with a construction sequence that has real dirt moving behind it. None of those procurement categories exist in the conventional LWR supply chain, and what TerraPower builds at Kemmerer will set the pace for how the industry scales whatever comes next.