Entergy had to shut down one of three cooling systems at its beleaguered Pilgrim Nuclear Power Station on Monday after the plant experienced excessive vibrations within the system, the Nuclear Regulatory Commission said Tuesday.
The power provider identified the issue during a required quarterly test at the 44-year-old Massachusetts facility, which the NRC in 2015 downgraded to Column 4 of its Action Matrix, the lowest safety rating a plant can have while remaining in operation. The facility is due to close in 2019.
The vibrations were reported within Pilgrim’s high-pressure coolant injection (HPCI) system, which can be used to cool the reactor should it experience a sudden shutdown. The other two cooling systems are the low-pressure coolant injection (LPCI) and residual heat removal (RHR) systems, which ensure the reactor can be safely shut down if one or more of the systems fails. Entergy has 14 days to restore the HPCI system, or it must shut the reactor down.
“Our Resident Inspectors at Pilgrim will continue to follow up on the company’s troubleshooting and any repairs,” NRC spokesman Neil Sheehan said by email Tuesday. “The Limiting Condition of Operation requires the company to fix the problem within 14 days or shut down until it is remedied. However, we would expect the problem to be addressed as soon as possible.”
The facility has recorded several unplanned shutdowns and safety issues with relief valves since 2013. The most recent unplanned shutdown occurred in September, when complications with a fluctuating feedwater regulating valve led to excessive water levels in the plant’s reactor vessel. Over the past year, the NRC has conducted two of three increased oversight inspections at the plant, resulting from the safety downgrade. The third and most comprehensive inspection is scheduled to begin Nov. 28.
