Federal regulators have given Sequoyah Nuclear Plant a "white" safety finding -- the first level of safety concerns that triggers stepped up federal inspections.
Sequoyah, near Soddy-Daisy and 20 miles from downtown Chattanooga, received notice of the finding in a November letter from the Nuclear Regulatory Commission after the plant's Unit 1 reactor had its fourth unplanned "scram" -- or shutdown -- in less than a year.
"This was due to two trips [unplanned automatic shutdowns] in the fourth quarter of 2010, one trip in the second quarter of 2011 and one trip in the third quarter of 2011," wrote Richard P. Croteau, NRC's director of the division of reactor projects.
A fifth shutdown occurred in the reactor after the plant had moved into the white rating, TVA spokesman Ray Golden acknowledged.
White signifies the lowest level of safety concerns, NRC spokesman Joey Ledford said. Red is the highest and in between is yellow.
Neither NRC nor TVA notified the public about Sequoyah's white rating, officials said, but the letter is on file in NRC's online documents database.
TVA officials insist the plant is safe and continues to operate.
"The plant is built to be very safe and, while we are disappointed, we want people to understand that at no point was their safety or employees' safety a problem," Golden said. "We are committed to finding the root cause [of so many unplanned shutdowns] and to making the plant safer. It's a continuing learning process."
Sequoyah is the second TVA plant to have triggered NRC's color-coded safety findings.
The Browns Ferry Nuclear Plant, located 70 miles southwest of Chattanooga in Athens, Ala., received a red finding from the NRC in May. The "red, or high safety significance," finding -- the most severe ranking the Nuclear Regulatory Commission gives to problems uncovered -- is only the fifth issued nationwide in the past decade, according to NRC spokesmen.
Reactors with no highlighted problems in six categories are rated as green and, of the nation's 104 commercial reactors, only about 10 have white, yellow or red indicators. Browns Ferry is the only one currently with a red finding.
Ledford said the NRC guideline is that a reactor can have three unplanned shutdowns in 7,000 operating hours.
"With [Sequoyah's] fourth one, they crossed the green-to-white threshold," he said, adding that NRC now plans a special weeklong inspection, probably in February at the plant.
"Right now, there is no indication the scrams are related, but TVA will be looking at the root causes and we will look at all of that," he said.
"We're not pleased with that [having two plants with safety issues], but we are working on it," Golden said. "Hopefully soon we'll have one back in the green space. But the bottom line for the public is this: We know we operate for their trust."
Sandy Kurtz, an anti-nuclear TVA critic in Chattanooga, was not pleased to learn of the new safety concerns at Sequoyah.
"It's good to know that the safety mechanisms [of shutdowns] kicked in, but the concern is why did they have so many in a short time," she said.
Yvonne Derrickson, who has lived near the Sequoyah plant for 25 years, said the news worries her.
"I am concerned," she said. "Even though there hasn't been an accident, when there is an accident, it's devastating. I'm hoping we can find alternative energy sources."
Daniel Cobb, a retiree who for 16 years has lived about a mile from Sequoyah, said he is "perfectly comfortable" living close to the plant, but he expects "somebody will have to buckle down and fix it."
"A lot of people I know get upset about it, [living near a nuclear plant]. But the fact is, where I live right now and where you are -- you'd probably live 40 seconds longer than I would if something happened," he said.