A Historic Construction Permit After Decades of Waiting

On March 4, 2026, the Nuclear Regulatory Commission announced the first commercial reactor construction approval issued in the United States in nearly a decade—and the first permit ever granted for a commercial non-light-water reactor in more than 40 years. The permit is for TerraPower's Kemmerer Power Station Unit 1, a 345-megawatt sodium-cooled fast reactor sited near a retiring coal plant in Kemmerer, Wyoming.

The NRC completed its technical review in just 18 months after accepting TerraPower's application in May 2024—well ahead of the initial 27-month schedule. The commission found the review adequate to make the necessary safety and environmental findings, authorizing its Office of Nuclear Reactor Regulation to issue the permit.

TerraPower formally broke ground on non-nuclear support facilities at the Kemmerer site in June 2024. The issuance of the construction permit clears the path for full nuclear construction to begin.

Construction Officially Begins in April 2026

On April 23, 2026, TerraPower announced the official start of construction on Kemmerer Unit 1. The company mobilized a workforce of roughly 1,600 workers for the project, which is expected to be completed and operational by 2030.

Bechtel serves as the engineering, procurement, and construction (EPC) partner. In a statement released the same day, Bechtel confirmed it had begun mobilizing teams and transitioning into field execution at the Kemmerer Unit 1 site. Bechtel noted its teams had completed early works at the site over the prior year, including a Test and Fill Facility and a Kemmerer Training Center.

Once operational, the plant will employ approximately 250 full-time workers on a permanent basis. Wyoming Governor Mark Gordon called it "a major milestone not just for Wyoming, but for the future of American energy."

What Makes the Natrium Reactor Different

The Kemmerer plant is not a conventional reactor. The Natrium technology—a TerraPower and GE Vernova Hitachi Nuclear Energy design—uses liquid sodium rather than water as its coolant. That fundamental change enables higher operating temperatures and greater thermodynamic efficiency compared to traditional light-water reactors.

The plant's design includes an integrated molten salt-based energy storage system that can temporarily boost output from 345 megawatts to 500 megawatts when grid demand peaks. According to the American Nuclear Society, that storage flexibility allows the reactor to provide steady baseload power while also acting as a dispatchable resource during high-demand periods—a capability that no other licensed commercial reactor design currently offers in the U.S.

At 500 MW of peak output, the plant could power roughly 400,000 homes.

Federal Partnership and the Advanced Reactor Demonstration Program

Kemmerer Unit 1 is being developed through the U.S. Department of Energy's Advanced Reactor Demonstration Program (ARDP), a public-private partnership created to accelerate the deployment of advanced nuclear designs. The DOE confirmed the construction permit milestone on May 8, 2026, describing it as the first commercial reactor construction permit issued for a non-light-water design in the nation's history.

Dr. Rian Bahran, Deputy Assistant Secretary for the DOE's Office of Nuclear Energy, said in a statement: "The Natrium reactor shows that when government and private industry work together, we can build a bright future for our country powered by nuclear."

A Pipeline Beyond Kemmerer

The Kemmerer project is not a standalone demonstration. TerraPower has signed an agreement with Meta to provide up to eight Natrium plants by 2035, with the first two units targeted for delivery as early as 2032. That commercial pipeline gives the Natrium design a trajectory toward serial construction—a scale that the U.S. advanced nuclear industry has not previously achieved.

Separately, Holtec International submitted a partial construction permit application to the NRC on December 31, 2025, for two SMR-300 small modular reactors—named Pioneer 1 and Pioneer 2—at its Palisades Energy Center in Covert, Michigan. The NRC accepted the application for review in February 2026, with a schedule to issue safety evaluations and an environmental impact statement by March 2027. Holtec has targeted the early 2030s for commissioning those units.

The activity at both sites reflects a broader shift in the U.S. nuclear sector—from a decade of stalled projects and cost overruns on conventional large reactors, toward a new generation of smaller, factory-informed designs seeking to demonstrate that nuclear construction in America can be planned, permitted, and executed on schedule.

What This Means for the Construction Industry

Advanced nuclear construction requires a distinct combination of skills: precision civil and structural work, specialized mechanical and piping systems, rigorous quality assurance programs, and workforce training tailored to nuclear safety standards. The Kemmerer project is generating immediate demand for those capabilities in Wyoming and across Bechtel's supply chain.

For the broader construction sector, the significance extends beyond a single project. If Kemmerer Unit 1 is built on schedule and on budget, it establishes a replicable model for deploying advanced reactors at scale. A validated construction sequence, an experienced workforce, and a proven regulatory pathway would all reduce the risk and cost of subsequent units—a pattern the industry badly needs after the cost overruns that plagued the conventional Vogtle nuclear expansion in Georgia.

Owners and general contractors who track large-scale energy infrastructure will want to watch Kemmerer's progress closely. It is shaping up as one of the most consequential construction projects of the decade.

Sources

• Nuclear Regulatory Commission – NRC Issues First Commercial Reactor Construction Approval in 10 Years (March 4, 2026)
• TerraPower – TerraPower Commences Construction on America's First Utility-Scale Advanced Nuclear Power Plant (April 23, 2026)
• Bechtel – Bechtel and TerraPower Begin Construction at Natrium Kemmerer Unit 1 (April 23, 2026)
• American Nuclear Society – TerraPower begins construction on Natrium power plant in Kemmerer (April 24, 2026)
• U.S. Department of Energy – NRC Issues Construction Permit for TerraPower's Natrium Advanced Reactor (May 8, 2026)
• NRC – Advanced Reactor Highlights 2026