The Megawatt Mission

Winter Readiness Crews Sweat the Small Stuff

A bitter breeze ruffles Norm Flake’s vest as his safety-toe boots clang up the steel stairway headed to the top of Unit 1.

It’s cold up here.

Among all of Tennessee Valley Authority’s 51 gas, hydro and coal plants across seven states, John Sevier Combined Cycle Plant in the Appalachian foothills of Hawkins County, Tennessee, has been ranked as the No. 1 coldest.

On this day, the temperature at John Sevier is 42 degrees Fahrenheit. The wind chill makes it feel more like 34.

As Flake makes his rounds on a walkway more than 80 feet above the ground, Mike Shenal flags him down.

Shenal points to an array of narrow water pipes blanketed in gray material.

These pipes need more insulation, he says.

“That’s a good find,” Flake responds.

As TVA’s program manager for seasonal readiness, Flake loves getting reports like Shenal’s. If there’s anything that can be done – even a seemingly tiny detail – to better prepare the plant for extreme cold weather, Flake wants to know about it.

It's all about making sure TVA's megawatts are reliable and resilient when temperatures plunge and demand spikes.

The best way to continue meeting customer demand? Keep the megawatts online.

"And that's our mission," Flake said.

Heat trace technician Mike Shenal, right, makes a recommendation to TVA seasonal readiness program manager Norm Flake.

Down to 0 Degrees

Throughout the day, Flake checks in on Shenal’s team of eight heat-trace specialists, who are going over John Sevier with a fine-tooth comb.

Heat trace circuits are electrical wires strung alongside pipes, valves and other sensitive equipment to prevent freezing. There are more than 30 miles of heat trace – over 15,000 wires – just at TVA’s gas plants.

Heat trace is one of the first lines of defense when TVA plant operators like Harold Jobe and Phillip Burnett are working around the clock to keep John Sevier’s 871 megawatts of power online – even at 0 degrees Fahrenheit or below.

“The most important thing is that we can stay on when we are needed the most,” Jobe, a combined cycle operations technician, said.

Heat trace technician Malachi Kendrick works on one of the 12 heat trace control cabinets at John Sevier Combined Cycle Plant in Hawkins County, Tennessee.

CT Scans and MRIs

Last winter, TVA carried out more than 2,600 repairs of heat trace wires and insulation across its system.

But this year’s efforts take the program to a whole new level.

There are more than 1,000 heat trace wires at John Sevier, and the heat trace team is taking multiple readings on each of them – the amps or strength of the electrical current, the voltage, the resistance and the condition of the insulation. They’re also fine-tuning detailed maps of circuits that power the heat trace.

It takes several weeks to conduct the in-depth checkup and create a map of the plant’s 12 refrigerator-size heat trace cabinets, each with about 60 breakers.

And when the team finishes at John Sevier, they’ll move on to four of TVA’s other large combined cycle plants.

“This year we're looking at heat trace in a whole different way,” Flake said. “We're starting to look at circuit health. It has a lifespan. How far down on that lifespan are we?

“If you think in terms of going to the doctor, last year we went to see, ‘Hey, are your bones broken? Any head injuries?’ We looked at it from the surface,” Flake said.

“This year, it's like we're doing CT scans and MRIs.”

Heat trace technician Eric Rodriguez jots down electrical readings from a heat trace circuit.

Long-Term Projects

In FY 2024, TVA invested $430 million to harden its system and enhance the reliability and resilience of its gas, hydro and coal generating fleet.

The results were excellent, Flake said. TVA’s system met record-high demand peaks during the prolonged deep freeze of Winter Storm Heather in January 2024.

But Flake and his colleagues aren’t resting on their laurels.

They’ve completed 417 preventive maintenance work orders to prepare for this winter.

At the same time, they’re investing in long-term projects to further harden TVA’s system:

• Proactively scheduling replacement of aging heat trace lines and insulation in the coming years.
• Developing a system of smart panels to monitor freeze protection systems in real time, so plant operators in the control room have early warning of potential problems.
• Replacing temporary shelters that protect cold-sensitive equipment with solid-wall enclosures.
• Refining and practicing plant-by-plant cold weather plans.
• Identifying additional high-priority cold-weather upgrades, such as modernizing control air dryers that keep water out of hoses, valves and other critical components.

From left, Flake, heat trace operation manager John Barbaria and heat trace technician Jorge Longoria work alongside the large pipes carrying steam to and from the turbine at John Sevier.

Getting Ahead of the Game

At John Sevier, plant operator Jobe said the heat trace crew’s work this winter is invaluable.

“They’re giving me a heads-up, and then I'm following up to get ahead of the game and make sure those circuits don’t trip when it’s cold – because that’s not the time to try to troubleshoot,” Jobe said.

Howie Rose, TVA manager for business continuity, could not agree more. Better preparation enhances resilience and reliability – and it’s also safer for employees.

“If it’s icing and snowing, you really want to minimize the need to be up there climbing around,” Rose said.

One key long-term upgrade – installing smart panels – will put critical data at plant operators’ fingertips, ensuring they can make well-informed decisions.

“If we give operators enough information in time to react, they will be able to ensure the reliability of the asset,” said Larry Sparks, whose team is implementing the program. “We're able to deliver power even in the most severe of conditions.”

TVA’s winter readiness program is really not much different than what he does as a homeowner to prepare for cold weather, Sparks said.

“I’ve got to make sure the heater’s working. I’ve got to make sure the insulation's in place. I’ve got to make sure all the cracks and openings get closed up.

“That's what effectively we're doing for the plants. We're ensuring that those systems are all at the highest level of reliability.”

Plant manager Kate Bowling reviews the cold weather plan for John Sevier with Flake. Each of TVA’s 51 gas, hydro and coal plants has its own plan.

Useful Discoveries

John Sevier plant manager Kate Bowling said the deep dive on heat trace has provided many useful discoveries, such as how to best configure systems to protect against sudden temperature drops.

“This is our third year working systematically on the heat trace,” she said. “The continued focus has been extremely beneficial. We're making continuous improvements, and lessons learned here we're sharing with the overall Valley.”

And, Bowling said, the benefit spreads beyond TVA.

“It's not just an investment in TVA or an investment in John Sevier. It's an investment in our communities. They depend on us.”

Photo Gallery

Flake makes his rounds to help prepare the John Sevier plant to deliver power at 0 degrees Fahrenheit and below.

Longoria enters data into an app.

The black heater and red heat trace wires in this transmitter box prevent sensitive measuring equipment and tubes from freezing.

At top, heat trace crews use blue tape to temporarily record thousands of electrical readings that will feed into a detailed assessment of the system. At bottom, rubber sheaths and insulating fabric cover heat trace lines, protecting pipes, tubes and cables from freezing.

John Sevier can generate 871 megawatts of power, enough to supply more than 500,000 homes.

Kendrick, right, checks in with TVA emergency management specialist Patrick Glinn.

Flake inspects equipment shielded by a heated windbreak structure. TVA is replacing temporary enclosures with solid-wall enclosures.

There are more than 100 heated transmitter boxes like these protecting critical equipment at John Sevier.

Barbaria and Kendrick are part of the eight-person expert heat trace crew doing an in-depth assessment of five large TVA gas plants this winter.

PHOTO AT TOP OF PAGE: Flake and seasonal readiness crews go over TVA’s generating plants with a detailed winter preparedness checklist.