America's newest nuclear reactor was shut down over the weekend for refueling and maintenance to allow the Tennessee Valley Authority to bring the plant back into sustained operation for the colder winter months ahead.
The Unit 2 reactor at Watts Bar has operated at full power only about two- thirds of the time in its first year of operation since achieving commercial status in October 2016 as the first new nuclear plant to be added to the U.S. electric grid in the 21st century.
The unit automatically shut down in March when the support beams failed on one of the plant's condensers, which help convert the steam generated within the reactor back into water for recirculation in the closed loop system. TVA spent more than four months repairing the condenser on the non-nuclear side of the plant before restarting the unit again on Aug. 1.
But the 1,200-megawatt reactor, which is one of two at the Spring City, Tenn., plant, did generate more than 6.2 billion kilowatt- hours of electricity over the past year, according to TVA.
"Our work during this outage will position Watts Bar Unit 2 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 Vice President Paul Simmons said in a statement Monday. "This outage puts Unit 2 on a routine 18-month refueling cycle that aligns with the other seven nuclear units in our TVA fleet. Our goal is a year-and-a-half of safe, around-the-clock, full-power generation from the nation's newest nuclear unit."
TVA does its maintenance outage on its power plants, to the extent possible, during the spring and fall months to have as many units as possible generating power during peak demand periods in the cold months of the winter and in the hottest days of the summer.
TVA initially began limited power generation at Watts Bar Unit 2 in the spring of 2016, but the reactor didn't reach sustainable, full-power generation until October when it was declared a commercial unit and TVA brought the unit into the utility's rate base.
TVA spokesman Jim Hopson said the initial startup problems once the reactor became critical — and the condenser rupture five months after the unit achieved full power — were both problems on the non-nuclear portion of the plant. Hopson said the nuclear reactor "has worked flawlessly," but the Watts Bar Unit 2 had problems with a transformer fire in the switchyard last year and a ruptured condenser in the turbine building earlier this year.
"Since the first day we turned the reactor on, we've had no problems with the reactor or any associated systems, with the reactors," Hopson said. "The challenges that we've had with the unit since it came online, even for testing, have all been related to the power production or transmission part of the plant."
During the refueling outage over the next few weeks, an additional 1,000 TVA and contract employees are supplementing the site's regular staff. More than 12,000 work activities are planned during the outage, including loading new fuel assemblies, performing inspections of the unit's reactor equipment and steam generators, maintenance of plant equipment and additional equipment upgrades.
The refueling outage comes as TVA prepares to meet Thursday with regulators about the culture of work at the Watts Bar Nuclear Plant.
The Nuclear Regulatory Commission has scheduled a public meeting with TVA at 6 p.m. Thursday in Athens, Tenn., to discuss progress TVA has made in addressing regulatory concerns about whether managers were suppressing safety concerns from being voiced by workers at Watts Bar.
The meeting is scheduled at the Comfort Inn, 2811 Decatur Pike, in Athens.
In March, 2016, the NRC staff issued a letter to TVA indicating some of TVA's operating employees may not have felt comfortable raising safety concerns at the plant. The NRC said TVA managers outside the control room had a "chilling effect" on the plant's work environment,
At full production, Watts Bar's two reactors are capable of producing enough power for 1.3 million homes.
Contact Dave Flessner at firstname.lastname@example.org or at 423-757-6340.
This story was updated Oct. 30 at 10:10 p.m.