The Tennessee Valley Authority returned one of its reactors at the Sequoyah Nuclear Plant in the Chattanooga suburbs to service Thursday morning after an unplanned two-day outage.
The federal utility put the Unit 1 reactor back online at 8:45 a.m., TVA spokesperson Scott Fiedler said in a text. It is still addressing issues with a water pump on the Unit 2 reactor, which should be back online soon, Fiedler said.
Operators at the plant manually tripped the Unit 1 reactor early Tuesday to address a malfunction in a non-nuclear system leading to low water levels in a steam generator, according to TVA reports to the U.S. Nuclear Regulatory Commission.
(READ MORE: Natural gas eclipses nuclear as TVA outages persist)
Operators manually tripped the Unit 2 reactor a few hours later to address a different non-nuclear system malfunction. The Unit 2 reactor tripped unexpectedly in July 2024, prompting a rewinding of the main generator, which cost the utility $107 million as of March 31.
Nuclear reactors are highly complex pieces of machinery with a huge benefit: Under normal operating circumstances, they can run for 18 months straight, providing electricity for millions of homes.
Sequoyah in Soddy-Daisy is powerful enough to keep the lights on for 1.3 million homes at once, roughly equivalent to the output of Hoover Dam. Its reactors came online in 1981 and 1982.
TVA’s seven nuclear reactors at three plants come offline on a rotating schedule for planned uranium refueling outages, but all three plants have experienced unplanned outages over the past year.
The nation’s largest public power provider normally relies on its nuclear plants for around 40% of its electricity. In the second quarter of its fiscal year, from Jan. 1 to March 31, the plants contributed 27% of TVA’s electricity.
LIFE EXTENSIONS
Leaders at the Knoxville-based utility, which employs around 3,000 people at its Chattanooga hub, have pinned the outages on electrical equipment that’s aging out. TVA plans to invest $6 billion in a life extension program for its nuclear plants.
The utility will seek license extensions for the plants with the ultimate goal of operating them for 80 years or longer. The U.S. Nuclear Regulatory Commission allows reactors to operate 40 years through their initial license, which can be extended in 20-year increments.
Several TVA reactor operating licenses will need to be extended over the next decade.
TVA secured extensions for all three reactors at the Browns Ferry Nuclear Plant in Alabama. That facility celebrated 50 years as the utility’s single most powerful plant in 2024. Those licenses expire in 2033, 2034 and 2036, and TVA is seeking to secure another 20-year extension.
The first reactor at the Watts Bar Nuclear Plant in Rhea County came online in 1996, and its initial license expires in 2036. The second Watts Bar reactor, which was the first new U.S. reactor of the 21st century when it came online in 2016, is licensed to operate until 2056.
Sequoyah Unit 1 is licensed to operate through 2040 and Sequoyah Unit 2 through 2041 after getting extensions.
TVA’s nuclear program once planned 17 reactors, but most were canceled or halted construction in the 1980s due to cost overruns and faulty projections of power demand.
The utility has turned its new nuclear efforts to small modular reactors, becoming the first U.S. utility to apply for a construction permit for the compact design in May.
The federal utility is developing a 300-megawatt design by GE Hitachi Nuclear Energy at its TVA’s Clinch River site in Oak Ridge, but TVA leaders have not ruled out building another large-scale nuclear plant in the future as demand for energy grows.
Contact Daniel Dassow at ddassow@timesfreepress.com or 423-757-6318.