The paperwork is done. The money isn’t. On Sept. 29 the Nuclear Regulatory Commission issued the Tennessee Valley Authority a construction permit for a 300-megawatt small modular reactor at its Clinch River site in Oak Ridge, Tenn., the first SMR construction permit the agency has granted for a commercial power reactor in the U.S.
The unit is a GE Vernova Hitachi BWRX-300, a water-cooled boiling water reactor with passive safety systems. The NRC says its review took 14 months from the formal start in July 2025, four months ahead of schedule.
What the small modular reactor permit does and doesn’t allow
A construction permit lets TVA build safety-related structures. It doesn’t let TVA load fuel. That needs a separate operating license, and TVA hasn’t filed for one. The site already had an early site permit, issued in 2019, and the NRC held a public hearing on the construction application in Oak Ridge in August.
“Four months ahead of schedule is what the new NRC looks like,” Chairman Ho Nieh said in the agency’s release. That’s a pointed line from a regulator that was long criticized for review times measured in years. It’s also worth reading carefully: the speed is the NRC’s, and the next step is TVA’s.
TVA’s cost question
TVA hasn’t announced a construction start date or a cost estimate. In its own statement, as reported by T&D World, the utility said it’s negotiating with industry partners on cost sharing and financial accountability, and that it wants to make sure Valley ratepayers don’t carry the costs of first-of-a-kind technology.
That’s the real signal for builders. In January 2025 TVA lined up Bechtel, Sargent & Lundy and GE Hitachi as its SMR partners, according to the American Nuclear Society. Those firms now know they have a permitted site. What they don’t have yet is a contract structure that says who eats an overrun on the first unit, and that’s the question that stalled large reactor projects for a generation. Exchange’s Clinch River Unit 1 project listing tracks the team, and our July report covered the federal money behind TVA and Holtec.
Why carbon-free firm power is the pitch
The case for Clinch River is that it’s dispatchable generation with no smokestack, sized small enough to build in a factory-plus-field model rather than as a one-off megaproject. Ontario Power Generation is already testing that argument with the same design. The Canadian regulator issued a licence to construct a BWRX-300 at Darlington in April 2025, construction is underway, and OPG applied for an operating licence in March 2026, according to GE Vernova.
That gives TVA something no U.S. nuclear owner has had in decades: a reference plant of the same design being built a year or more ahead. If Darlington’s costs and schedule hold, TVA’s partners will have numbers to price against. If they don’t, TVA will know before it pours concrete.
GE Vernova says a second U.S. customer filed its own BWRX-300 construction permit application in September. The permit TVA just got is the template that filing will be reviewed against.