Wyoming’s First Advanced Natrium Reactor Clears Major Safety Hurdle Early

Wyoming’s flagship advanced nuclear project just crossed a big milestone — ahead of schedule, World Nuclear News reports.

The US Nuclear Regulatory Commission (NRC) has finished its final safety evaluation for TerraPower’s Kemmerer Power Station Unit 1, a next-generation Natrium reactor planned near Kemmerer in Lincoln County. The review wrapped up one month earlier than the agency’s already accelerated timeline.

The evaluation is the NRC staff’s deep technical review of TerraPower’s construction permit application. The Kemmerer plant is designed to demonstrate Natrium technology, a sodium-cooled fast reactor paired with a molten salt energy storage system that lets the plant ramp power up and down to match grid demand — something traditional nuclear plants don’t usually do.

The NRC started formally reviewing TerraPower’s application in May 2024. The initial target for finishing the safety review was August 2026, but regulators later decided to speed things up and aimed to complete it by the end of 2025. They beat that goal, too.

This project is also breaking new ground on the regulatory side. It’s the first time the NRC has used a fully risk-informed, performance-based approach (RIPB) to set the licensing basis for a commercial power reactor — essentially focusing more on actual risk and outcomes than box-checking.

The NRC’s Advisory Committee on Reactor Safeguards independently reviewed the safety-related parts of the application and sent its findings to the Commission in mid-November. The bottom line from the staff’s safety evaluation: there are no safety issues that would block issuing a construction permit.

“We’ve finished our technical work on the Kemmerer review a month ahead of our already accelerated schedule, as we aim to make licensing decisions for new, advanced reactors in no more than 18 months,” said Jeremy Groom, acting director of the NRC’s Office of Nuclear Reactor Regulation.

On the environmental side, the NRC already wrapped up its Environmental Impact Statement in October, covering how the proposed plant might affect the surrounding area.

Now the process moves into its final licensing phase:

• The NRC Commission will review the staff’s work and decide whether it supports the findings needed to issue a construction permit.
• The commissioners will then vote on whether to direct staff to issue that permit.

TerraPower President and CEO Chris Levesque called the moment “momentous” for the company, its partners and the Natrium design, saying the safety evaluation reflects years of intensive review and close work with the NRC.

If the Commission signs off, the permit will only authorize construction, not operation. TerraPower’s subsidiary, US SFR Owner, LLC, will have to submit a separate operating license application before the reactor can actually run.

Meanwhile, non-nuclear construction work at the site is already underway.

The Kemmerer project is the first Natrium plant being developed under the US Department of Energy’s Advanced Reactor Demonstration Program, using technology co-developed by TerraPower and GE Vernova Hitachi Nuclear Energy — and it’s quickly becoming a bellwether for how fast advanced reactors can move from drawing board to reality in the US.