Both reactors at TVA's newest nuclear power plant are shut down after plant operators idled one unit for routine refueling Saturday and shut down the other unit Monday after detecting problems in the pumps on the non-nuclear part of the plant.
The shutdown of the two 1,150-megawatt reactors has cut enough power to supply 1.3 million homes in the Tennessee Valley.
TVA still has plenty of power capacity from its other power plants, especially with this week's mild springtime temperatures. But the shutdown costs TVA more than $1 million a day to replace the lost generation.
The shutdown of the Unit 1 reactor for refueling has brought an extra 800 temporary contract workers and TVA employees to the plant near Spring City, Tenn., for the next month to perform maintenance work and refuel the Unit 1 reactor. Nuclear plants are typically refueled about every 18 months and plant operators use such outages to replace parts, inspect equipment and perform other maintenance tasks that can't be done when the unit is operating.
Two days after TVA shut down the oldest reactor and began the refueling work Saturday, the newest reactor at Watts Bar also was shut down Monday morning after plant operators detected problems in the pumps that supply water to the steam generators in the turbine building outside of the nuclear reactor for Unit 2.
"As a conservative action when they discovered the pump problems [on the non-nuclear part of Unit 2], the operators took the unit offline," TVA spokesman Jim Hopson said. "They are working through the situation with the pumps right now and they will try to get the unit back online as soon as possible. It's certainly not any situation that has any safety consequences to the public or the plant."
TVA had several such unplanned outages on the Unit 2 reactor last year after it began generating power for the first time. While the Unit 1 reactor was reaching full power last summer, a transformer yard fire on Aug. 30 forced TVA to take the plant off line for four weeks to replace the damaged transformer.
But since the Unit 2 reactor became a commercial unit and began consistent power generation in October, the unit has operated continuously without any major problems, Hopson said.
TVA spent more than 40 years building, maintaining and reactivating construction on the newest Watts Bar reactor before finishing the Westinghouse pressurized-water reactor last year.
The Unit 1 reactor, a twin to the unit that started power production last year, began generating power in 1996 — more than two decades after construction began on that unit.
Prior to Saturday's shut down of Unit 1 at Watts Bar, TVA estimates the oldest unit at Watts Bar had generated 13.2 billion kilowatthours of electricity since the reactor was last refueled a year and a half ago.
During the refueling outage over the next month, more than 10,000 work activities are planned on the Unit 1 reactor, including loading new fuel assemblies, performing rotary blade replacements on two of the four Unit 1's turbines and installing additional Unit 1 enhancements.
"Our work during this outage will position Watts Bar Unit 1 to continue generating low-cost, carbon-free nuclear energy to reliably power daily life across the Tennessee Valley for the next 18 months," Watts Bar Site Director Paul Simmons said in a statement Monday.
Contact Dave Flessner at email@example.com or at 423-757-6340.
This story was updated March 21 at 6:15 p.m.