The Entergy (NYSE:ETR) River Bend nuclear plant in Louisiana went offline unexpectedly on Nov. 27, which is the day after Thanksgiving that has come be known as ‘Black Friday’ for shoppers.
The facility was still listed at zero power by the Nuclear Regulatory Commission (NRC) early Nov. 30.
At about 4:30 a.m. CST on Nov. 27, an automatic reactor scram occurred following the trip of the main generator, according to an event report filed online with NRC. “The generator trip was apparently caused by a partial loss of offsite power, which resulted from a differential ground on the north bus of the local 230 kV switchyard,” according to the report.
The event report goes on to add:
“The reactor is being taken to cold shutdown pending an investigation of the event. The loss of power also resulted in a partial loss of normal service water cooling to the plant, and emergency service water cooling automatically initiated per design.”
“At the time of event, the reactor protection system was aligned to the backup power supply, which was momentarily lost. This resulted in multiple system isolations including reactor water clean-up, and outboard balance of plant isolations. These isolations were initiated due to loss of offsite power, and all responded as designed,” according to the event report.
“The isolation resulted in a loss of the running decay heat removal pump for the spent fuel pool. The standby pump is available for service and being aligned for service. The plant is currently stable in hot shutdown. Transmission and distribution personnel are currently investigating the ground in the 230-kV switchyard.”
River Bend is a single-unit boiling water reactor (BWR) with a generating capacity of roughly 1,000 MW. It is located in St. Francisville, La. The nuclear plant, which went online in the mid-1980s, is run by Entergy’s regulated Louisiana utilities. River Bend also experienced an unplanned outage in June.
Entergy conducted a regularly-scheduled refueling and maintenance outage at River Bend earlier this year.