Just a few months after the Nuclear Regulatory Commission (NRC) performed a supplemental inspection at the Lacey, NJ-based Oyster Creek Nuclear Generating Station, the plant shut down again on Sunday.
Oyster Creek automatically shut down at 2:14 p.m. because of an electrical issue in a system that controls steam pressure, said Exelon spokesperson Suzanne D’Ambrosio.
“All systems operated as designed during the reactor’s shutdown,“ D‘Ambrosio said in a statement. “Staff will troubleshoot and make necessary repairs to the pressure control system while the plant is shut down. The plant will return to service after operators make repairs to the system.
Oyster Creek was already under additional NRC oversight in 2014 because of a “White” (low to moderate safety significance) performance indicator that stemmed from four unplanned shutdowns, or scrams, in 2013 and 2014.
The NRC ’s performance indicator for unplanned scrams for each 7,000 hours of operation changes from green to white if a nuclear plant has more than three unplanned shutdowns. Oyster Creek crossed the green/white threshold July 11, 2014, when the plant had a fourth unplanned shutdown, the NRC said.
The NRC conducted a supplemental team inspection at Oyster Creek from Dec. 8 through Dec. 11.
The NRC found Exelon had performed an adequate root cause evaluation for the four unplanned shutdowns and a collective root cause evaluation for all of the events, said Ho K. Nieh, Director of the NRC’s Reactor Projects Division in a March 4 letter to Bryan Hanson, Exelon’s president and chief nuclear officer.
The NRC inspectors remained satisfied with Exelon’s corrective actions to address the causes of the scrams and closed out the white performance indictor and returned it to green, according to the letter.
The NRC has not reached a final decision on two apparent violations for the plant: A preliminary “White” inspection finding involved emergency diesel generator maintenance and a preliminary “Yellow” (substantial safety significance) inspection finding involving the plant’s electromagnetic relief valves. The final determinations on those apparent violations could result in changes to the NRC’s level of oversight at Oyster Creek, Nieh said in the letter to Hanson.
Oyster Creek is the oldest nuclear plant in the United States. It went online Dec. 23, 1969.