The Tennessee Valley Authority slowed the 1,123-megawatt Watts Bar 1 reactor in Tennessee early today, snapping a seven-day advance for nuclear output in the Southeast.
Generation nationwide declined by 0.6 percent to 90,632 megawatts, or 89 percent of capacity, according to U.S. Nuclear Regulatory Commission data compiled by Bloomberg. Output was 6.4 percent less than a year earlier with eight of 104 nuclear reactors offline.
Tennessee Valley reduced the Watts Bar 1 unit, located about 55 miles (88 kilometers) southwest of Knoxville, to 20 percent of capacity from full power to conduct maintenance on a feed water valve on the non-nuclear portion of the plant, according to Ray Golden, a company spokesman based in Knoxville.
“The repair has been completed and the plant is conducting post maintenance testing,” Golden said in an e-mail.
The Watts Bar decline led production lower by 2.3 percent to 27,987 megawatts in the Southeast, known as the NRC’s Region 2, according to commission data compiled by Bloomberg. That’s the lowest level since Dec. 23 and the first decline in a week.
NextEra Energy Inc.’s 1,295-megawatt Seabrook 1 reactor, the largest nuclear unit in the NRC’s Northeast, or Region 1, cut power to 56 percent of capacity from 100 percent yesterday.
“We’re down temporarily while we do maintenance on the secondary side of the plant,” Alan Griffith, a company spokesman based at the plant, said in a phone interview. “As soon as we complete the work we will be at full power. This is what we consider routine scheduled maintenance.”
The unit, situated about 13 miles south of Portsmouth, New Hampshire, led the decline in the Northeast, where nuclear generation fell by 0.3 percent to 24,193 megawatts.
Susquehanna 2, a PPL Corp. plant with the capacity to generate 1,140 megawatts in Pennsylvania, ran at 86 percent of power from 44 percent yesterday. The unit began increasing output Dec. 28 after an electrical connection caused an automatic shutdown, according to a company statement.
“We are still in the process of going through the various checks and tests on that unit as it returns to full power,” Joe Scopelliti, a spokesman based at the plant, said in an e-mail responding to questions.
Grand Gulf Scram
Entergy Corp.’s 1,297-megawatt Grand Gulf 1 reactor in Mississippi operated at 1 percent of power early today after automatically shutting Dec. 29 because of a turbine trip, according to an event notification on the commission’s website.
As of Dec. 29, the unit was “in hot shutdown with decay heat removal to the condenser and the electrical line-up is in a normal configuration,” the report showed. “The cause of the turbine/generator trip is under investigation.”
A protective relay may have malfunctioned, shutting the plant down when there was not disturbance in operating conditions, said Mike Bowling, a company spokesman based in Jackson, Mississippi.
Reactor maintenance shutdowns, usually undertaken in the U.S. spring or fall when energy use is lowest, may increase consumption of natural gas and coal to generate electricity. The average refueling down time was 43 days in 2011, according to the Nuclear Energy Institute.