US regulator accelerates review of Natrium permit

Thursday, 3 July 2025

Natrium technology features a 345 MWe sodium-cooled fast reactor using high-assay low-enriched uranium fuel, with a molten salt-based energy storage system that can boost the system’s output to 500 MWe for more than five and a half hours when needed. TerraPower plans to build the Natrium demonstration plant near a retiring coal facility at Kemmerer in Wyoming.

TerraPower was the first developer to submit a construction permit application for a commercial advanced reactor to the NRC in March 2024.

In February this year, the NRC acknowledged it was ahead of schedule on safety review and said it expected to complete its review of TerraPower's application by June 2026, two months earlier than originally expected. In May, the regulator exempted the energy production and energy storage portion of the plant from its review, paving the way for construction on half the Natrium plant to begin this year.

The NRC has now said that it has "set a more aggressive schedule and aims to complete its review by the end of 2025".

It noted: "Frequent and productive engagements with TerraPower, along with other efficiency gains, mean the NRC could complete reviews by 31 December 2025, six months ahead of the current schedule. The accelerated timeline depends on a continued commitment from TerraPower to resolve the remaining issues in a timely manner."

TerraPower said that its regulatory strategy has been "built on providing thorough technical content and robust engagement opportunities to discuss the Natrium technology and design with regulators".

"This acknowledgement by the NRC that our application can be completed more quickly than originally anticipated is a testament to the incredible work by our Natrium team and the support for advanced reactors at the federal level," said TerraPower President and CEO Chris Levesque. "President Trump has been instrumental in both founding the Advanced Reactor Demonstration Program and supporting rapid deployment of advanced reactors. Streamlining reviews is a commonsense solution that will accelerate permitting schedules; and proves that we can bring safe, well-vetted American technologies to market faster and compete on the global stage."

A ground-breaking ceremony held in June last year marked the start of non-nuclear construction at the Kemmerer site. Nuclear construction will begin after the application is approved. TerraPower envisages commercial operation of the plant starting in 2031.

The NRC noted that if it issues the construction permit for the Kemmerer plant, TerraPower would need to submit a separate application for a licence to operate it.