America's newest nuclear reactor shut down only four days after it was declared complete and commercially viable, but the reactor returned to full power this week following a 9-day outage.
The Tennessee Valley Authority shut down its newest unit at the Watts Bar Nuclear Plant on Oct. 23 after discovering a potential problem in one of the main bank transformers in the switch yard at the Spring City, Tenn. plant, TVA spokesman Jim Hopson said Wednesday.
The transformer problem was discovered only four days after TVA celebrated Watts Bar Unit 2 as the first U.S. commercial nuclear plant added to America's electric grid in more than 20 years.
TVA idled the Unit 2 reactor until the transformer problem was repaired and TVA was again able to dispatch the 1,150 megawatts of electricity that the new reactor generates at full power.
"This was not an issue with the nuclear plant itself, but our monitors detected a possible problem developing in one of the transformers for Unit 2," Hopson said. "Whenever our equipment monitors detect these type of problems in a transformer, we take the appropriate measures to ensure the equipment is working as designed. It's a lot easier to make these repairs before a more significant problem might develop."
The transformer problem last week came only a month after a fire in another main bank transformer also forced Watts Bar Unit 2 to shut down during startup testing in September. Hopson said the incidents have not affected or involved the nuclear generation at the plant, just how the power is dispatched in the switch yard at Watts Bar.
The transformer problem was not classified as an incident of major safety significance which had to be reported to federal regulators and TVA did not announce the latest shut down of Unit 2 at Watts Bar. TVA does not routinely indicate whether its power plants are operating or not to avoid unnecessary pricing changes in power purchasing markets that might be influenced by such announcements.
"This was an unfortunate event, but we followed our procedures and our nuclear unit itself is operating just fine," Hopson said.
TVA began to amortize the nearly $5 billion debt on the Unit 2 reactor last month. TVA spends more than $600,000 a day in interest and operating expenses on Watts Bar Unit 2 whether or not the federal utility gets any power from the reactor.
Replacing the lost generation from the idled reactor during autumn months is not difficult or particularly expensive since power demand is far below the peak levels usually reached either on hot summer days or cold winter mornings.
Contact Dave Flessner at email@example.com or at 423-757-6340.
Updated at 11:04 p.m. with additional information.