First U.S. Small Reactor Permit

Oak Ridge — The U.S. Nuclear Regulatory Commission on 29 September issued the Tennessee Valley Authority a construction permit for Clinch River Unit 1 — a GE Vernova Hitachi Nuclear Energy BWRX-300 small modular reactor at TVA’s Clinch River Nuclear Site near Oak Ridge, Tennessee — making TVA the first U.S. utility cleared to build that reactor design.

A construction permit is federal permission to build the plant as reviewed. It is not a license to load fuel or generate power. TVA still needs a separate NRC operating license before the reactor could run, and TVA’s board still must approve a final commitment to build. No construction start date has been announced.

What an SMR is — and what this permit changes

Small modular reactors, or SMRs, are advanced nuclear plants designed to make up to about 300 megawatts of electricity — roughly one-third the output of a typical large reactor. Major pieces can be built in factories and shipped to the site, which manufacturers say can cut construction time and complexity. The BWRX-300 is a boiling-water SMR design from GE Vernova Hitachi.

Jeremy Bowen, director of the NRC’s Office of Advanced Reactors, said at the signing that the permit “certifies that the NRC has conducted an independent and rigorous review, and we are certifying that the design is safe to construct.” He underscored: “This is a construction permit. It allows TVA to begin construction of the facility in accordance with the design that we’ve reviewed.” Commission action does not authorize operation.

TVA Interim President and CEO Mike Skaggs called the permit “foundational for America’s nuclear future” and said TVA is proud to partner with the NRC, GE Vernova Hitachi and the Administration to explore new nuclear while serving the Tennessee Valley. Chief Nuclear Officer Matt Rasmussen thanked the NRC for engagement that, TVA says, helped issue the permit ahead of schedule. TVA’s release called Clinch River only the second advanced-reactor construction permit ever issued in the United States, and the first for the BWRX-300 design.

What TVA has — and has not — done

Engineering News-Record reported that nuclear construction has not begun. TVA spokesperson Scott Fiedler said the utility has not authorized new construction packages, long-lead procurement or expanded contractor scopes after the permit. Some site work was already allowed: the NRC approved a December 2024 exemption for reactor-building excavation and an initial ground-support system, and preconstruction work outside NRC jurisdiction has included clearing, grading, support buildings, roads and utilities. TVA says it has cleared about 150 acres, built a new five-lane bridge, improved roads and installed on-site power and water.

TVA’s board has authorized $350 million for Clinch River development — $200 million in 2022 plus $150 million in August 2024 for continued design — but still must green-light a final build. The U.S. Energy Department selected TVA in December 2025 for up to $400 million in cost-shared federal funding to advance the project. Bechtel, Sargent & Lundy and GE Vernova Hitachi are under contract for planning and design, with potential roles in procurement, construction and commissioning. Skaggs said TVA’s priority is ensuring Valley customers do not shoulder first-of-a-kind costs alone, and that securing market off-takers for the power matters to deployment.

Canada is already pouring

The same BWRX-300 design is already under construction in Canada. Ontario Power Generation received Canadian approval in April 2025 to build the first BWRX-300 at Darlington and applied in March 2026 for authorization to operate it. That leaves TVA with the first U.S. construction permit for the design, while Canada holds the lead on actual building and toward operation.

Tennessee Governor Bill Lee and members of the state’s congressional delegation hailed the NRC action as a nuclear-leadership milestone for East Tennessee. For the rest of the country, the takeaway is narrower and clearer: a U.S. regulator has now cleared this SMR design for construction at a named site — a gate that had not opened before — even though shovels for nuclear-grade work and a final TVA board “go” are still ahead.