The Pilgrim Nuclear Power Plant in Massachusetts, limping toward retirement in 2019, suffered yet another unplanned shutdown on September 6 after operators were forced to power down the reactor because of high water levels in the core.
According to the Nuclear Regulatory Commission (NRC) event report, “operators initiated a manual reactor scram due to high reactor water level resulting from feedwater level control oscillation.” The plant is currently in hot shutdown while the event is under investigation.
NRC spokesman Neil Sheehan told local media that water level issues were apparently caused by a malfunction in the feedwater control valve. Pilgrim owner Entergy Corp. said the event caused no risk to the public.
String of Problems for Pilgrim
The aging 685-MW boiling-water reactor north of Boston has struggled with a variety of problems over the past few years, several of which have caused unplanned shutdowns and NRC investigation findings (Figure).
Pilgrim has been hit with four Green findings (the lowest level) through the first half of 2016. Yet that is an improvement from the second half of 2015, when it received seven Green findings and one White finding. Those problems led the NRC to move Pilgrim into the Repetitive Degraded Cornerstone Column, indicating multiple problems in meeting one of the NRC’s plant performance criteria. Arkansas Nuclear One—also owned by Entergy—is the only other plant in the Repetitive Degraded Cornerstone Column.
Main Steam Valve Issues
Many of the problems appear to stem from issues with the plant’s main steam isolation valves (MSIVs). Failure of one such valve and problems with identifying and correcting the cause were the reason for the NRC’s White finding in March 2015. Another shutdown in August 2015 was also the result of a failed MSIV; that event led to a Green finding last December.
Most recently, Pilgrim was again forced to power down on August 18 after a MSIV failed during testing. The plant was shut down for four days for repairs.
Entergy announced in October 2015 that Pilgrim would retire by 2019 because of poor market conditions, reduced revenues, and increased operational costs
—Thomas W. Overton, JD is a POWER associate editor (@thomas_overton, @POWERmagazine).