For the second time this week, TVA's newest nuclear reactors tripped Thursday because of an equipment problem on the non-nuclear side of the plant.
TVA spokesman Jim Hopson said today that the Unit 2 reactor at the Watts Bar Nuclear Plant shut down shortly after midnight on Thursday due to a problem in the plant condenser, which converts the steam used to drive the turbine back into water for recirculation in the plant.
Both units of Watts Bar are now shut down while TVA refuels Unit 1 and looks to assess and correct the equipment problem that caused the shut down on Unit 2.
Watts Bar operators shut down Unit 2 on Monday morning due to problems in the pumps on the turbine system. condenser problem. But only 30 minutes after TVA had corrected those problems and brought Unit 2 power back up and online, the reactor unexpectedly tripped again.
"As operators were slowly returning the unit to service late Wednesday, the turbine automatically shut down around 12:15 a.m. Thursday," Hopson said. "The reactor was then safely taken offline and there were no public or nuclear safety concerns at the time."
Hopson said TVA is currently evaluating the turbine system to determine the cause of the shutdown and identify necessary repairs.
The two unplanned trips at Unit 2 at Watts Bar don't appear to be related and because the reactor is still so new the number of unplanned outages at the plant has not resulted in any extra regulatory review or oversight and the incidents were not considered to be classified as significant events, NRC spokesman Roger Hannah said today.
The Unit 2 reactor operated only about 1,600 hours last year after it was started up following more than four decades of construction and design work.
The Unit 1 reactor, which began producing power in 1996, was taken offline last Saturday for a routine refueling outage and maintenance work.
When both of the reactors at Watts Bar are operating, TVA generates 2,300 megawatts of electricity, or enough power to supply about 1.3 million homes.