Construction has officially begun on TerraPower’s Kemmerer Unit 1 in Wyoming, marking a key step in the company’s push to build what it describes as the United States’ first utility-scale advanced nuclear power plant.

The Natrium-based facility follows regulatory clearance and years of site preparation.

The project comes after the U.S. Nuclear Regulatory Commission issued a construction permit for the plant.

TerraPower said early site work had already started in 2024, but this phase represents the formal start of full-scale construction activity at the site.

The Kemmerer facility is designed around TerraPower’s Natrium reactor concept, which combines a sodium-cooled fast reactor with an integrated energy storage system.

The company says the design is aimed at providing flexible power output for grid demand.

According to the company, the project is being developed under the U.S. Department of Energy’s Advanced Reactor Demonstration Program, a public-private initiative supporting next-generation nuclear systems.

Wyoming energy push

Wyoming officials framed the development as part of the state’s long energy history and its role in uranium production and power generation.

“This is the moment our industry has been working toward for a generation. 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,” said Chris Levesque, president and CEO of TerraPower.

“The Natrium plant will deliver reliable and dispatchable power to the grid and Kemmerer Unit 1 will serve as a commercial blueprint to mobilize a fleet of Natrium plants across the country and around the world.”

“The start of construction on TerraPower’s Natrium plant in Kemmerer marks a major milestone not just for Wyoming, but for the future of American energy,” said Wyoming Governor Mark Gordon.

“Wyoming has long powered this country, and today we are leading again, this time in next-generation nuclear technology.”

Workforce build begins

TerraPower said around 1,600 construction workers will be mobilized during peak building activity, with about 250 permanent jobs expected once the plant becomes operational.

The Natrium system includes a 345-megawatt sodium-cooled reactor paired with molten salt-based energy storage.

The storage system is designed to allow the plant to increase output to 500 megawatts during peak demand periods.

The project has support from federal agencies and industry partners involved in nuclear development and construction.

“The United States needs more reliable baseload power now,” said U.S. Senator John Barrasso.

“As the country’s number one producer of uranium, Wyoming is the perfect place to build TerraPower’s advanced nuclear reactor.”

“Today’s construction milestone is a testament to the Department of Energy’s investment in American innovation,” said Dr. Rian Bahran, Deputy Assistant Secretary for the U.S. Department of Energy’s Office of Nuclear Energy.

“The Natrium reactor shows that when government and private industry work together, we can build a bright future for our country powered by nuclear.”

TerraPower said the Kemmerer plant is expected to serve as a reference model for future Natrium deployments in the U.S. and abroad.

The company has also referenced commercial partnerships aimed at expanding deployment timelines into the next decade.

The Kemmerer Unit 1 project remains under active construction, with full operational timelines yet to be finalized.