TVA completes its largest planned gas plant outage ever at John Sevier

The recently completed fall planned outage at TVA's John Sevier Combined Cycle Gas plant near Rogersville is the largest fall outage in TVA's gas fleet history.

It was also the latest in a series of actions to help ensure safe, reliable, low-cost power across the Valley during the cold winter months ahead.

John Sevier Combined Cycle (JSCC), a 3 on 1 gas combined cycle plant, returned to service Dec. 4, after successful execution of its annual fall outage that began Oct. 1.

It was the most extensive fall outage to date of any plant in TVA's combined cycle fleet, said Dustin Watson, JSCC plant manager.

"This is the largest outage at JSCC since the plant began commercial operation in 2012 to replace the coal plant," Watson said. "This also is the largest work scope ever for any TVA combined cycle plant. We left no component untouched in overhauling this plant to make sure it provides reliable power this winter and for years to come."

The long list of JSCC outage activities included upgrades, refurbishments, routine and major maintenance on all three combustion turbines, one steam turbine, and their associated generators. In addition, a major steam turbine controls upgrades, replacement of all steam blending valves, reliability maintenance, winterization, and more were performed during the outage.

Power Operations collaborated with TVA's Power Service Shops, who worked hard to support the project both in the shop and at the site to make it a successful outage.

"This project was extensive in scope and scale," said Bob Jones, senior manager, Turbine Generator Field Services, Power Service Shops. "The work was well-planned, executed with precision, and completed on schedule to help ensure a smooth-running power generation plant for years to come."

TVA has scheduled 69 total planned outages in the gas fleet this Fall, all completed except for three still in progress and three planned to start by mid-December. Other notable planned gas outages recently completed or currently underway include:

Lagoon Creek CTs main gas pressure regulator valves replaced

Colbert CTs 3&4 main generator step-up transformer, the critical link between the power station and the transmission network, often runs day and night at full load under extreme thermal loading, replaced

Gallatin CTs common power refurbishment projects (in progress)

Magnolia combined cycle Unit 3 controls upgrade and steam turbine generator field rewind (in progress)

In addition to investments in its generation and transmission assets, TVA's diverse portfolio is also a critical part of its cold weather reliability commitment.

That commitment paid off in February 2021 when bitter cold left millions in Texas, Arkansas, Oklahoma and Mississippi without power and caused six days of rolling blackouts. Under those same frigid conditions, TVA's service area had only one weather-related outage over 16,300 miles of transmission lines, which was restored in 45 minutes.

"Severe weather requires preparation, planning, resources, and most of all, a skilled and dedicated workforce," said David Bowling, vice president, Gas and Hydro. "We are more dedicated than ever to the continuous improvement of our gas fleet to maintain flexibility, reliability and capacity year-round, no matter what the weather is doing.

"Natural gas is a bridge that will help ensure reliability as TVA transitions towards the Energy System of the Future."