TerraPower Begins Full Construction on First US Utility-Scale Advanced Nuclear Reactor in Wyoming

On April 23, 2026, TerraPower officially commenced full nuclear construction on its Kemmerer Unit 1 plant in Wyoming, marking a watershed moment for the American energy sector.[1][3][4]

The milestone transitions the estimated $4 billion project from early site preparation into full-scale plant assembly. It is on track to become the first utility-scale advanced nuclear power plant in the United States, and the first commercial non-light water reactor approved for construction in more than 40 years.[2][3]

The groundbreaking follows a remarkably swift regulatory process. The U.S. Nuclear Regulatory Commission (NRC) issued the construction permit in early March 2026, completing its safety and environmental review in just 18 months following a streamlined mandatory hearing process.[1][3]

TerraPower, co-founded by Bill Gates, had already begun non-nuclear construction on the greenfield site in June 2024. However, the NRC's approval allowed the engineering, procurement, and construction partner, Bechtel, to begin work on the nuclear island itself.[1][2][3][4]

At the heart of the Kemmerer facility is the Natrium reactor, a 345-megawatt (MW) sodium-cooled fast reactor developed jointly by TerraPower and GE Vernova Hitachi Nuclear Energy. Unlike traditional reactors that use water under high pressure to cool the core, the Natrium design uses liquid sodium, which can absorb immense amounts of heat at normal atmospheric pressure.[1][3][5][7]

What sets the Natrium plant apart from legacy nuclear facilities is its integrated molten salt-based energy storage system. Similar to technology used in concentrated solar power plants, the system captures fission heat and stores it in vats of molten salt.[1][4][7]

This thermal battery allows the plant to decouple its reactor operations from its electrical output. While the reactor runs continuously at a steady thermal output, the storage system can temporarily boost the plant's electrical generation to 500 MW when grid demand peaks.[1][4][7]

At maximum output, the facility can generate enough electricity to power roughly 400,000 homes. This "load following" capability makes the Natrium reactor uniquely suited to complement intermittent renewable energy sources, ramping up power when solar and wind generation drops.[1][3][5][6]

The strategic location of Kemmerer Unit 1 highlights a growing trend in the energy transition: coal-to-nuclear conversion. The advanced reactor is being built adjacent to PacifiCorp's retiring Naughton coal-fired power plant.[2][3]

By siting the reactor near a retiring fossil fuel facility, TerraPower can leverage existing grid transmission infrastructure and water rights, significantly reducing the capital costs associated with greenfield development.[5]

The location also provides an economic lifeline to a historic energy community. The project is expected to require a workforce of roughly 1,600 construction workers and will eventually employ about 250 full-time staff once operational, allowing local coal workers to transition their skills into the nuclear sector.[2][5][6]

The federal government views the Kemmerer project as a critical test of American nuclear competitiveness. The U.S. Department of Energy's Advanced Reactor Demonstration Program (ARDP) is heavily backing the facility, pledging nearly $2 billion to support its licensing, construction, and demonstration.[2][5]

"We're not just breaking new ground on a first-of-a-kind nuclear plant in Wyoming; we're building the next generation of America's energy infrastructure," TerraPower CEO Chris Levesque said, describing the Wyoming site as a commercial blueprint for a global fleet.[1][4]

The demand for firm, carbon-free baseload power is accelerating rapidly, driven largely by the massive energy requirements of artificial intelligence data centers. TerraPower is already commercializing the technology beyond Wyoming, having secured an agreement with Meta to deploy up to eight Natrium plants by 2035.[4][6]

Despite the momentum, the advanced nuclear sector still faces supply chain hurdles. The Natrium reactor requires high-assay low-enriched uranium (HALEU), a specialized fuel that currently lacks a robust domestic supply chain, though TerraPower has signed agreements with domestic producers like Centrus Energy to close the gap.[7]

With a target completion date of 2030, the Kemmerer project will serve as the ultimate proving ground. If successful, it will demonstrate that advanced reactor designs can move beyond pilot-scale concepts into repeatable, commercial delivery—a threshold the U.S. nuclear industry has struggled to cross for decades.[1][2][3]