The archive · Space, Robots, Defence · Strategic decision · 2006–2026
TerraPower wins first US advanced-reactor construction permit; Natrium targets 2030
Gates' sodium-cooled fast reactor plus molten-salt storage cleared NRC in 18 months — first US permit for a commercial non-light-water plant in 40+ years.
TerraPower
What the business is
TerraPower develops and builds the Natrium, a 345 MW sodium-cooled fast reactor with molten-salt storage that can peak at 500 MW, selling dispatchable carbon-free power to the grid.
Starting capital：Backed by Bill Gates and early investors; DOE Advanced Reactor Demonstration Program cost-shared funding for design, licensing, fuel qualification, and two support facilities (per energy.gov).
How it started
Gates founded TerraPower in 2006; after years of traveling-wave-reactor R&D, DOE's ARDP picked Natrium (with GE-Hitachi) as one of two US demonstration projects. In March 2024 TerraPower filed the first construction-permit application for a commercial advanced reactor, targeting Kemmerer, Wyoming.
What happened
NRC docketed the application in May 2024 — the first commercial non-light-water docket in over 40 years. Non-nuclear sitework began June 2024; the final environmental impact statement landed in October 2025 and the safety evaluation in December 2025. NRC commissioners voted the construction permit on March 4, 2026, after an 18-month review that DOE says finished ahead of schedule and 11% under budget.
How it ended up
Construction is starting at Kemmerer Unit 1; DOE and TerraPower target completion in 2030 as America's first commercial-scale advanced plant. A separate operating-license application to the NRC still lies ahead.
Background
TerraPower's bet was that America's regulatory bottleneck, not reactor physics, was the real barrier to advanced nuclear. Since no US commercial non-light-water plant had been permitted in four decades, the company made the construction permit itself the first product milestone: sodium-cooled fast reactor, molten-salt energy storage, and a site next to a retiring Wyoming coal plant.
The wedge was dispatchability. A base-load reactor cannot chase solar and wind, so Natrium pairs a 345 MW reactor with a molten-salt tank that boosts output to 500 MW for over five hours. That flexibility, plus coal-to-nuclear jobs for Kemmerer, sold the community, PacifiCorp, and DOE's ARDP program.
Execution followed: application filed March 2024, docketed May 2024, non-nuclear ground broken June 2024, and on March 4, 2026 the NRC commissioners voted the permit after an 18-month review. Construction now heads toward a 2030 completion target, with an operating-license application and fuel qualification still ahead.
The permit does not mean the bet is won — Natrium must still be built on time and on budget, and TerraPower must prove a sodium-cooled plant can operate commercially. But it has already reset the industry's baseline: the first mover defined what a complete advanced-reactor application looks like.
What has to be true
- Licensing was the actual bottleneck: no US commercial non-light-water plant had been permitted in 40 years, so TerraPower made the permit itself the milestone.
- The molten-salt tank turns a must-run reactor into dispatchable power, the wedge that sold utilities, Wyoming, and DOE.
- Coal-to-nuclear reuse of Kemmerer's site gave the project a community and grid hook no greenfield plant could match.
- A complete application plus early regulator engagement beat lobbying: NRC review finished in 18 months, ahead of schedule and 11% under budget.
What can be applied
Filing first with a complete application compressed NRC review from 27 to 18 months, converting licensing risk into a schedule — a template every later advanced-reactor developer must now follow.
Aftermath
As of 2026-09-02, TerraPower holds the permit and has started building Kemmerer Unit 1 — roughly 1,600 workers at peak, five years of construction, commercial operation targeted 2030. Still ahead: the NRC operating-license application and fuel qualification. The Natrium design is being exported as well: TerraPower applied for a UK generic design assessment in October 2025, accepted in February 2026, so the US first-mover position is becoming a global licensing template.
Sources
- NRC Approves the Natrium® Reactor Construction Permit
- NRC Issues Construction Permit for TerraPower's Natrium Advanced Reactor
- TerraPower Begins Construction on Advanced Nuclear Project in Wyoming
- TerraPower Submits Construction Permit Application to the U.S. Nuclear Regulatory Commission for the Natrium Reactor Demonstration Project
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