Three nuclear power units that were online prior to Thanksgiving, two in the Southeast and one in the Northeast, were offline on Nov. 28, according to Nuclear Regulatory Commission data.
The Tennessee Valley Authority has started a scheduled refueling and maintenance outage at Sequoyah Unit 1; Southern Co. has seen one of its reactors in Alabama experience an unplanned outage and the Exelon Nine Mile Point Unit 2 in Upstate New York has also gone offline.
After generating more than 12.3 billion kilowatt hours of carbon-free energy over the past 18 months, the TVA Sequoyah Unit 1 in in Soddy Daisy, Tennessee began a scheduled refueling and maintenance outage on Saturday, Nov. 26.
An additional 700 TVA and contract employees are supplementing the site’s regular staff during the scheduled outage. About 10,000 work activities are planned, including loading new fuel assemblies, performing inspections of reactor components, maintenance of plant equipment and installing unit enhancements, TVA said in a news release.
The 1,100 MW Sequoyah Unit 1 is one of seven operational TVA nuclear reactors that supply nearly one-third of all electricity used by more than 9 million people.
Meanwhile, Southern’s Alabama Power utility saw Farley Unit 1 in Houston County, Alabama experience an unplanned outage on Nov. 27.
"At 0026 [CST] on November 27, 2016, Farley Unit 1 was manually tripped from 100 percent reactor power due to voltage swings suspected to be caused by the Auto Voltage Regulator. All control rods fully inserted and Auxiliary Feedwater (AFW) auto-started as expected,” according to an event notification report filed with NRC.
The cause of the main generator voltage oscillations is under investigation.
The trip was uncomplicated at the roughly 875 MW Farley 1. All safety equipment is available, if needed. Unit 2 was unaffected by the event and remains at 100 percent power.
Nine Mile Point 2 was listed at zero power early Nov. 28 after being listed at 100 percent power as recently as Nov. 23. Nine Mile Point Unit 1 was still listed at 100 percent power on Nov. 28. Unit 2 is the larger of the two reactors at the Oswego County, New York site, listed at more than 1,100 MW.
Nine Mile Point Nuclear Station Unit 2 was manually shut down Nov. 24 at 1:36 p.m. for technicians to repair one of the unit’s two reactor recirculation pumps. The recirculation pumps send water back through the reactor and are used to help regulate power. Technicians are working to repair and test the pump prior to returning the unit to service, Exelon said in a Nov. 24 news release.