In the small southwestern Wyoming town of Kemmerer, population roughly 2,600, heavy equipment is already moving dirt at a site where a coal-fired power plant once anchored the local economy. The Nuclear Regulatory Commission has issued a construction permit for TerraPower’s Natrium reactor, making it the first new commercial nuclear plant approved for construction in the United States in decades. And the federal review that got it there finished nine months ahead of schedule and 11 percent under budget.
Site preparation work, separately authorized by the Department of Energy, is already underway. Full construction could begin within weeks, according to reporting from the Associated Press, which cited company and federal officials. If the project stays on track, it will serve as the most consequential real-world test yet of whether advanced nuclear technology can move from blueprint to functioning power plant.
A regulatory milestone with real numbers behind it
The NRC’s final safety evaluation found no issues that would prevent issuing the construction permit for the Natrium sodium-cooled fast reactor. The agency’s ADVANCE Act licensing page confirms the review wrapped up nine months early and 11 percent under its planned budget, a result the NRC highlights as evidence that congressional reforms to streamline nuclear licensing are producing measurable results.
The original review timeline had been set at roughly 18 months. Finishing nine months early means the staff completed its technical assessment in approximately half that window while still reporting cost savings against the planning baseline. Neither the NRC nor the DOE has published the total dollar cost of the review, so the 11 percent figure cannot yet be evaluated in absolute terms. But as a percentage improvement on a federal regulatory process long criticized for delays and cost overruns, the number is significant.
This is the first traditional construction permit the NRC has issued for a commercial power reactor in roughly half a century. The last comparable approvals came in the 1970s. (Vogtle Units 3 and 4 in Georgia, which began generating power in 2023 and 2024, were authorized under a different regulatory pathway: combined construction and operating licenses issued in 2012.)
What is the Natrium reactor, and why does it matter?
TerraPower, the nuclear energy company founded by Bill Gates in 2008, designed the Natrium reactor as a departure from the large, water-cooled plants that have dominated the U.S. nuclear fleet for decades. The Natrium system uses liquid sodium as its coolant instead of water, which allows it to operate at higher temperatures and lower pressures. That design choice eliminates some of the safety risks associated with high-pressure water systems and opens the door to more efficient electricity generation.
One of the reactor’s most distinctive features is its integrated molten salt energy storage system, which can bank heat and then ramp electricity output up or down depending on grid demand. That flexibility is designed to complement wind and solar generation, filling in when renewable output drops rather than running at a fixed output around the clock. The base reactor would produce about 345 megawatts of electricity, with the storage system capable of boosting output to 500 megawatts during peak demand periods.
The Kemmerer project is part of the DOE’s Advanced Reactor Demonstration Program, which means it is receiving substantial federal funding. This is a government-backed demonstration, not a purely commercial venture, a distinction that matters when evaluating whether the project’s timeline and costs can be replicated by future private-sector builds.
Early site work is not waiting
The DOE completed a separate environmental assessment for the Kemmerer site and issued a Finding of No Significant Impact, authorizing federally funded site preparation and preconstruction activities. That clearance allowed earthmoving and infrastructure upgrades to begin at the former Naughton coal plant site before the NRC’s construction permit was formally in hand.
The practical result: by the time the NRC granted the construction permit, TerraPower had already been preparing the ground and upgrading on-site utilities for months. The AP reported that major construction could follow within weeks of the permit’s issuance, though no primary federal filing specifies an exact start date for structural work on the reactor itself.
What still has to happen
A construction permit is not permission to operate. Before the Natrium reactor can load fuel or connect to the grid, TerraPower will need a separate operating license from the NRC, a process that involves its own safety reviews, public hearings, and potentially years of additional regulatory work. Any design changes that emerge during construction, along with evolving safety standards, could influence that outcome.
The project also faces a fuel supply challenge. The Natrium reactor requires high-assay low-enriched uranium, or HALEU, a fuel type that is not yet produced at commercial scale in the United States. Building a domestic HALEU supply chain is a separate federal and industrial effort that will need to deliver on its own timeline for the Kemmerer reactor to operate as planned.
Then there is the shadow of Vogtle. The two new reactors at Plant Vogtle in Georgia, the only nuclear units built in the U.S. in a generation, came online years behind schedule and billions of dollars over budget. That experience has shaped public and investor skepticism about new nuclear construction. TerraPower and its supporters argue that the Natrium design is simpler and smaller than Vogtle’s massive pressurized water reactors, which should make it easier to build on time. Whether that argument holds up will be determined by what happens on the ground in Kemmerer over the next several years.
What Kemmerer is watching for
For the people who live near the construction site, the changes are already tangible. Construction jobs, infrastructure investment, and economic activity are arriving at a location where coal employment has been declining. The Kemmerer area has been preparing for this transition, and local officials have expressed support for the project as a source of long-term employment and tax revenue.
But the community’s interest extends beyond the construction phase. Residents will be watching for how the project manages safety, how it trains and hires local workers, and whether the finished reactor delivers the clean energy and economic stability its backers have promised. The speed of the NRC’s safety review is a meaningful signal about federal regulatory capacity. It is not, on its own, a guarantee that the reactor will perform as designed, stay on budget, or transform the region’s economy. That verdict will take years to reach, and it will be written in Kemmerer, not in Washington.
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*This article was researched with the help of AI, with human editors creating the final content.
