This story is part of our Quick Hits series. This series will bring you breaking news and short updates from throughout the state.
Editor’s Note: This story was updated Dec. 2, 2025 to include newly released statements from the Union of Concerned Scientists.
The nuclear power plant project in southwest Wyoming has cleared one of the last hurdles in securing a federal construction permit.
The permit is key to building out TerraPower’s project. The company, which is backed by Microsoft founder Bill Gates, hopes to prove out a first-of-its-kind technology in the sagebrush desert a few miles outside of Kemmerer. If successful, it promises to generate additional electricity for the region while emitting less emissions than alternative energy sources or older nuclear plant technologies.
So far, the federal government has deemed it safe, albeit in a sped up process. The Nuclear Regulatory Commission (NRC) sent out a Dec. 1 press release saying staff finished the final safety evaluation for the project “a month ahead of our already accelerated schedule” as part of a Pres. Trump executive order.
In the latest update, staff found “no safety aspects that would preclude issuing the construction permit.”
However, the Union of Concerned Scientists (UCS) has its doubts. They think there are safety issues and the permit process shouldn’t have been sped up.
“Make no mistake, this type of reactor has major safety flaws compared to conventional nuclear reactors that comprise the operating fleet,” said Edwin Lyman, UCS director of nuclear power safety, in a press release. “Its liquid sodium coolant can catch fire, and the reactor has inherent instabilities that could lead to a rapid and uncontrolled increase in power, causing damage to the reactor’s hot and highly radioactive nuclear fuel.”
The proposed technology unique to Terrapower is called Natrium. If it works as promised, the plant will be sodium cooled, which the company says is safer compared to the traditional nuclear plant cooling method of water that requires much higher pressure. Natrium also uses a new type of energy storage system, which would allow the plant to “quickly ramp up when demand peaks.”
NRC staff said in their report they “did not come to a final determination of the adequacy and acceptability of functional containment performance due to the preliminary nature of the design and analysis” and that they would confirm this once the operating license is issued for the plant. TerraPower has said it plans to be operational by 2030.
The comment from the NRC also concerns Lyman because “even if the NRC determines later that the functional containment is inadequate, it would be utterly impractical to retrofit the design and build a physical containment after construction has begun.”
Before the construction permit will be issued to TerraPower, NRC staff will provide its safety review to the commission in the coming weeks.
“The Commission will determine whether the staff’s review supports the findings necessary to issue the permit,” according to the press release. “Following its deliberations, the Commission will vote on whether to direct the staff to issue the permit.”
If approved, the NRC said the plant will require a separate operating license to be up and running.
TerraPower initially submitted the request for the construction permit in March 2024. It announced it chose Kemmerer as the test site in late 2021, breaking ground on non-nuclear aspects of the project last year.
