The U.S. Nuclear Regulatory Commission issued the Tennessee Valley Authority a construction permit on Sept. 29 for a small modular reactor at its Clinch River site near Oak Ridge, Tenn., clearing a major federal hurdle for the project.
The permit allows TVA to build a 300 MW GE Vernova Hitachi Nuclear Energy BWRX-300, the first US project to use the reactor design, but TVA has not made a final commitment to build the unit.
“The issuance of the construction permit certifies that the NRC has conducted an independent and rigorous review, and we are certifying that the design is safe to build,” Jeremy Bowen, director of the NRC’s Office of Advanced Reactors, said at a signing event.
TVA has advanced Clinch River in phases, with funding for each phase subject to management and board approval, and has not announced a construction date. TVA President and CEO Mike Skaggs said securing customers for generation will also be important for deployment.
“The awardee of the market for each of these units is very important for this, you know, to be fulfilled,” Skaggs said. He added that the deployment would also support electricity demand and economic development in the Tennessee Valley.
TVA spokesman Scott Fiedler told ENR that nuclear construction has not begun and that the utility has not authorized new construction packages, long-term contracting or expanded contractor scope after the permit was issued. The TVA board has yet to approve a final construction commitment.
What does permission change?
“This is a building permit,” Bowen said. “It allows TVA to begin construction of the facility in accordance with the design we have reviewed.”
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The Commission’s action does not authorize TVA to operate the reactor. The utility company will need an independent operating license before it can load fuel and operate it.
Nuclear Regulatory Commission Office of Advanced Reactors Director Jeremy Bowen, seated right, signs the construction permit for TVA’s 300 MW BWRX-300 small modular reactor at the Clinch River site in Tennessee.
Photo courtesy of Tennessee Valley Authority
The 2019 Clinch River Initial Site Permit requires TVA to conduct detailed geologic mapping as excavations are opened for safety-related structures, evaluate geologic features encountered during excavation, and notify the commission when excavations are available for agency review. Additional geotechnical investigations at the excavation level are also required.
Some work was allowed on the site prior to the building permit. The commission approved a TVA waiver in December 2024 that allowed excavation of the reactor building and installation of an initial ground support system. Preconstruction work outside the agency’s jurisdiction includes clearing, grading, support buildings, roads and utilities.
TVA says it has cleared 150 acres, built a new five-lane bridge, improved roads and installed power and water at the site. Nuclear construction has not begun and the company has not announced a construction start date.
Bechtel, Sargent & Lundy and GE Hitachi are under contract to plan and design the unit and potentially acquire, build and commission it. TVA says the issuance of permits has not resulted in new construction packages, long-term acquisitions or expanded contractor scopes.
What TVA still has to decide
The TVA board has authorized $350 million for the Clinch River project. The council initially approved $200 million in 2022 and added $150 million in August 2024 for continued work and design development. TVA says the council has yet to approve the final commitment to build the SMR.
Construction progress on Ontario Power Generation’s BWRX-300 Small Modular Reactor at the Darlington New Nuclear Project in Ontario. TVA plans to use the same GE Vernova Hitachi reactor design for its Clinch River project.
Photo courtesy of Ontario Power Generation
The U.S. Department of Energy selected TVA in December 2025 for up to $400 million in federal cost-share funding to advance the Clinch River reactor and help accelerate subsequent deployments of the BWRX-300.
DOE identified Scot Forge, North American Forgemasters, BWX Technologies and Aecon as national nuclear supply chain partners.
TVA also did not reaffirm a commercial operation goal for 2032. Fiedler says the utility is continuing negotiations with industry partners about cost sharing and financial responsibility during design and construction before committing to final timelines. He declined to elaborate on the negotiations, citing business confidentiality.
The same reactor design is already under construction in Canada. Ontario Power Generation received Canadian approval in April 2025 to build the first BWRX-300 at its new Darlington nuclear project in Ontario and applied for authorization to operate the unit in March 2026.
This leaves TVA with a construction permit for the first U.S. BWRX-300, but Canada with an advantage in building and operating one. TVA’s next step depends on completing industry negotiations and getting council approval for a final commitment to build.
