NRC approves TerraPower construction permit

Today, the Nuclear Regulatory Commission announced that it has approved TerraPower'sconstruction permit application for Kemmerer Unit 1, the company's first deployment of Natrium, its flagship sodium fast reactor.

This approval is a significant milestone on three fronts. For TerraPower, it represents anotherstep forward in demonstratingits technology. For the Department of Energy, it reflects progress(despite delays) forthe Advanced Reactor Demonstration Program(ARDP). For the NRC, it is the first approval granted toa commercial reactor in nearly adecade-and the first approval of a commercial non-light water reactor in more than 40 years.

A brief timeline: In August 2020, TerraPowerand GE Hitachi Nuclear Energy introduced theirjointly designed Natrium reactor, a 345-MWe sodium fast reactorpaired with a molten salt thermal storage system capable of boostingthe system's output to 500 MWe for more than five-and-a-half hours. The Natrium design alsoseparates thereactor facility andthe energy generation facility into two islands, aiming to reduce regulatory burden and speed construction.

In October 2020, the DOE selected Natrium (along with X-energy'sXe-100) for the ARDP. The DOE planned to invest $3.2 billionin the projects, ultimately aimingto get both reactors up and running within seven years.

In June 2021, TerraPower-withPacifiCorpas a partner-announcedaplan to site its demonstration reactor project at an unspecifiedretiring coal plant in Wyoming.

In November 2021, the company officially selected Kemmerer as its preferred site. Kemmerer is near Naughton power plant, a 448-MWe coal-fired facility thatis on track to be fully converted to a natural gas plant by 2026.

In March2024, after extensive, years-long preapplication work, TerraPowersubmitted its Part 50 construction permit application to the NRC. The NRC formally accepted the applicationin May 2024and aimed to complete its review by August 2026.

In January 2025, the Wyoming Industrial Siting Councilgranted approval to the Kemmerer projectfor allconstruction and operational activities outside NRC jurisdiction.

InJuly 2025, the NRC-making steady progress on its review-shortened its timeline for construction permit approval, aiming to make a decisionby the end of 2025, a goal it ultimately missedby three months. Still, the NRC completed its review five months ahead of its originaltimeline. More broadly, the overall project remainsdelayed, with completion targeted for 2030-three years beyond the original target set by the DOE.

The bigger picture: Now supplied with the necessary state and federal permitting, itis full steamahead for the Kemmerer project. In a press release, TerraPowerpresident and CEO Chris Levesque said that the company plans to start construction in a matter of weeks.

NRC Chair Ho Nieh said, "This is a historic step forward for advanced nuclear energy in the United States and reflects our commitment to delivering timely, predictable decisions grounded in a rigorous and independent safety review."

The NRC also emphasized that in order to operatethe completed facility, TerraPower'swholly owned subsidiary US SFR Owner will need to submita separatePart 50operating license application that itself would be subject to NRC approval.

The Kemmerer project is the fourth non-LWR reactor to receive a construction permit in recent years. These are theothersthat have received construction permits:

1. Kairos Power'sHermes, which was issued its permit in December 2023.Hermes is a 35-MWt fluoride salt-cooled, high-temperature reactor.

1. Abilene Christian University's Molten Salt Research Reactor, which was issued its permit in September 2024.The MSRRis rated at 1 MWt.

1. Kairos Power's Hermes 2, which was issued its permit in November2024. Hermes 2 broadly shares the design specifications of Hermes, butwould be larger and would demonstrateelectricity generation.

Unlike these reactors, the Natrium reactor at the core of the Kemmerer project is commercial scale. Thelast commercial-scale reactor approved by the NRC was Turkey Point-7 in 2018-though that approval came in the form of a Part 52 combined license (COL) for construction and operation rather than a construction permitalone.

A word on RIPB: Aside from these milestones, TerraPower'sapplication is the first to use a fully risk-informed, performance-based (RIPB) licensing basis for a power reactor, according to the NRC. TerraPower'sapplication used the Licensing Modernization Project (LMP) methodology, which is described in NEI 18-04. RIPB and LMP methods both aim to reduce regulatory burdens, increase flexibility,and aid the licensing ofnon-LWR reactor designs. The LMP methodologywas endorsed by the NRC in 2020.

"Completing a complex advanced reactor licensing review significantly ahead of schedule reflects improvements in the efficiency of the NRC's review process while maintaining the agency's rigorous safety and environmental standards," said Adam Stein, director of nuclear energy innovation at the Breakthrough Institute."Touching on the importance of RIPB, he added, "Predictable, risk-informed licensing processes are essential if the United States is to expand nuclear energy capacity at the pace required to meet national goals."