License for the first commercial small modular reactor in the United States.

American Nuclear Regulatory Commission (NRC) has approved the construction permit for the Tennessee Valley Authority (TVA) to build a small modular nuclear reactor at the Clinch River site in Roane County, Tennessee. This decision opens the way for the construction of the United States' first commercial SMR.

Regulatory review of the application was completed in 14 months — about four months ahead of the scheduled deadline, marking the second major approval for new reactors issued by the NRC this year.

“Four months before the deadline — that's how the new NRC looks,” said NRC Chairman Ho K. Nieh. “Today's Clinch River decision proves that the new NRC can make rigorous and credible safety decisions that enable the advancement of large American nuclear projects.”

Technology and key insights from the safety evaluation

Otherwise, at the Clinch River site, the plan is to construct a BWRX-300 reactor, with a nominal electric power of 300 megawatts (MWe) (thermal power 870 MWt), developed by GE Vernova Hitachi. The reactor is of the Boiling Water Reactor (BWR) type.

From the NRC's accompanying extensive safety evaluation (SER), some key technical and organizational specifics of the project are highlighted: unlike traditional light-water reactors that require “forced” circulation by pumps, the BWRX-300 relies on natural circulation to remove heat from the core during normal operation and in emergencies, thanks to the height of the reactor vessel and the “chimney” inside it. Because of this, safety functions depend exclusively on passive physical and thermodynamic principles (hence: “passive safety”), and in the event of a severe accident, stopping the reactor, removing residual heat, and isolating the containment operate without the need for external power supply, diesel generators, or operator intervention in the first 72 hours, using the Isolation Condenser System (ICS) and passive containment cooling.

Additionally, the reactor building and the steel-composite containment vessel will be located predominantly below ground level, increasing the facility's resilience to external impacts.

The planned completion of Clinch River Unit 1 construction is projected for fiscal year 2032, while the start of commercial operation is expected in 2033. The main contractor for procurement and construction will be Bechtel North American Power Corporation, while the specific site engineering design is handled by Sargent & Lundy.

Historical context and next steps

TVA had already received an Early Site Permit (ESP) back in 2019. Before fuel loading and the official start of operation, TVA will need to submit an application and obtain a separate Operating License from the NRC, under which the final Safety Analysis Report (FSAR) will be thoroughly analyzed.

The Clinch River site spans about 935 acres and has historically been known for originally being designated for the highly advanced Clinch River Breeder Reactor project – which was canceled in the 1970s.

S.A.