Kemmerer, Wyoming, is a town of about 2,600 people that has run on coal for generations. The nearby Naughton power plant, operated by PacifiCorp, is winding down. What is rising in its place is something no American community has seen in half a century: a brand-new nuclear reactor, approved for construction by federal regulators nine months ahead of schedule.
The Nuclear Regulatory Commission issued construction permit CPAR-1 to TerraPower’s subsidiary, US SFR Owner, LLC, for the Kemmerer Power Station Unit 1. It is the first standalone commercial nuclear construction permit the NRC has granted since the 1970s, a milestone that signals advanced reactor technology is finally crossing from paper designs into poured concrete.
What the permit actually authorizes
The construction permit allows TerraPower to build a 345-megawatt-electric sodium-cooled fast reactor in Lincoln County, Wyoming. Paired with an integrated molten salt energy storage system, the plant’s output can surge to 500 megawatts electric during periods of peak demand, according to the Department of Energy’s Office of Nuclear Energy.
At 500 MWe and a capacity factor typical of nuclear baseload plants (around 85 to 90 percent), the reactor would generate roughly 3.7 to 3.9 billion kilowatt-hours per year. Using the U.S. Energy Information Administration’s average household consumption of about 10,500 kWh annually, that translates to enough electricity for approximately 350,000 to 375,000 homes. Stretch the capacity factor to the upper range that newer designs target, and the figure approaches 400,000. The “nearly half a million” framing used by project boosters assumes optimistic but not impossible operating conditions.
The reactor’s thermal power level is 840 MWt, as listed on the NRC’s project page. The technology falls under the DOE’s Advanced Reactor Demonstration Program, a federal initiative created to push non-traditional reactor designs from demonstration to deployment.
How the NRC moved faster than expected
TerraPower filed its construction permit application on March 28, 2024. The NRC accepted it for review two months later. Staff completed their safety evaluation in roughly 18 months, finishing nine months ahead of the original projected timeline and, according to public statements by NRC leadership, under the review’s budgeted cost.
The agency’s final environmental impact statement, cataloged as NUREG-2268, analyzed land use, water resources, ecological effects, and socioeconomic impacts in Lincoln County. It recommended issuance of the permit. The Commission then adopted the staff’s safety and environmental findings in a formal order, clearing the way for CPAR-1.
That speed matters beyond Kemmerer. The NRC has faced criticism for years that its licensing process is too slow and too expensive to support a new generation of reactors. If the 18-month review becomes a template rather than an outlier, it could reshape the economics of advanced nuclear for every developer watching from the sidelines.
Why Kemmerer, and why now
The site selection was not random. Kemmerer sits next to retiring coal infrastructure, including transmission lines, a trained energy workforce, and a community that understands what it means to host a power plant. PacifiCorp, the regional utility that operates the Naughton plant, has been identified in public reporting as the expected offtaker for the Natrium reactor’s output, though a formal power purchase agreement has not been disclosed in available regulatory filings.
For Lincoln County, the project represents a direct economic bridge. Coal plant closures across the Mountain West have hollowed out tax bases and eliminated high-paying jobs. TerraPower has projected hundreds of construction jobs and long-term operational positions, though independent verification of those employment numbers is limited. Wyoming’s state government, including former Governor Mark Gordon, has publicly supported the project as a test case for whether advanced nuclear can replace fossil fuel generation without gutting rural economies.
The obstacles between permit and power
A construction permit is not an operating license. TerraPower must still submit a separate application to the NRC before the reactor can load fuel and generate electricity. That review will involve its own safety and environmental analysis, public comment periods, and potential hearing requests from intervening parties. Design changes, updated seismic or flooding data, or new regulatory requirements could extend the process.
The most concrete supply-chain risk involves fuel. The Natrium reactor requires high-assay low-enriched uranium, or HALEU, a fuel type enriched to between 5 and 20 percent uranium-235. As of early 2026, no U.S. facility produces HALEU at commercial scale. Centrus Energy’s demonstration plant in Piketon, Ohio, has manufactured small quantities under a DOE contract, but scaling that output to meet TerraPower’s needs on a timeline consistent with a 2030 or 2031 startup remains an open question. If HALEU production lags, the operational date slips regardless of how fast construction moves.
Cost transparency is another gap. Reporting from the Associated Press and other outlets references billions of dollars in estimated construction spending, but neither TerraPower nor the DOE has published a detailed budget breakdown. Without that data, it is difficult to compare the Natrium project’s economics against competing clean-energy options, particularly utility-scale solar paired with battery storage, which has seen steep cost declines. For Wyoming ratepayers who may ultimately absorb some portion of the plant’s costs, the absence of public figures is a meaningful blind spot.
What 2031 actually means
TerraPower leadership, including CEO Chris Levesque, has pointed to 2030 or 2031 as the target for commercial operation. That timeline assumes construction proceeds without major delays, the operating license review moves at a pace comparable to the construction permit review, and HALEU fuel is available when needed. Each of those assumptions carries real risk.
Still, the nine-month acceleration on the construction permit is a tangible data point, not a projection. If the NRC sustains that pace through the operating license phase, the 2031 window becomes plausible rather than aspirational. The agency’s willingness to complete the review ahead of schedule suggests institutional momentum that did not exist for advanced reactors even five years ago.
For the broader U.S. energy landscape, the Kemmerer permit is less about one reactor and more about whether the regulatory pathway for advanced nuclear actually works at speed. Dozens of other developers, from X-energy to Kairos Power, are watching to see if TerraPower’s experience is repeatable. If it is, the construction permit issued to a small Wyoming town in 2026 could mark the beginning of a wave. If it is not, Kemmerer becomes an expensive one-off, and the next generation of American nuclear power stays stuck in the approval queue.
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*This article was researched with the help of AI, with human editors creating the final content.
