PLYMOUTH -- Operators of the Pilgrim nuclear power plant found themselves again dealing with issues related to the reactor’s pressure-relief system during the six-day shutdown caused by partial loss of offsite electricity during the Jan. 4 storm.
A leaking pilot safety relief valve – one of four that sense excess pressure and release it into the cooling pool at the base of the reactor – was replaced while the plant was offline and maintenance was being done.
Pilgrim spokesman Patrick O’Brien said the faulty part was replaced with a spare.
“As part of our preparation for outages, we identify and acquire parts needed in advance, should we not already have those in our warehouse,” he said.
The leaking valve was not related to the shutdown, but malfunctioning safety relief valves have been a chronic problem at the plant.
Issues with the relief valve system and Pilgrim operators’ failure to adequately address them were major contributors to the 2015 decision by the federal Nuclear Regulatory Commission to downgrade the Plymouth plant to Column 4, one step above mandatory shutdown.
A blizzard on Jan. 27 of that year caused a forced shutdown of the reactor. The station’s response was complicated by a number of equipment snafus, including a failure of one of the relief valves to open as operators initiated systems to disperse pressure from the reactor as it cooled.
A subsequent engineering evaluation determined that two of the four safety relief valves had been in “a degraded state” for as long as a year.
The Nuclear Regulatory Commission cited Pilgrim, saying its operators had failed to meet the federal objective “of ensuring the availability, reliability and capability of systems that respond to initiating events to prevent undesirable consequences.”
Similar problems with the safety relief valves had occurred twice in the first two months of 2013. On Jan. 20 of that year, a steam leak in one of the valves forced the shutting down of the reactor. The valve was replaced with a refurbished valve.
Two weeks later, the same valve was found to be leaking, so operators adjusted and monitored it. Workers replaced the valve with a new one during a storm-related outage on Feb. 8.
One Pilgrim watchdog wasn’t surprised by news that a faulty safety relief valve was found during the reactor’s latest shutdown.
“To my mind, a thread has been lack of maintenance,” said Mary Lampert of Duxbury, president of the Pilgrim Watch group. “It seems to be the one thing the public and the NRC agree upon.”
The safety relief valves at Pilgrim are a brand used at some of the other boiling-water reactors in the U.S. and have a history of problems.
“It does not take a sane genius, or even a sane really smart person, to figure out it’s a lemon,” Lampert said. “When Pilgrim’s safety components are lemons – time to call it quits.”
David Lochbaum, director of the Nuclear Safety Program for the Union of Concerned Scientists, noted that more than 1,000 incident reports have been filed with the Nuclear Regulatory Commission by licensees since 2010, and 41 of them were related to safety relief valve problems.
Lochbaum said Pilgrim filed four such reports, tying it with Hope Creek in New Jersey and Browns Ferry Unit 1 in Alabama for the greatest number.
“So Pilgrim has experienced more than its share of safety relief valve problems,” he said. “Pilgrim is underperforming similar reactors, but it is not uniquely bad.”
Christine Legere may be reached at clegere@capecodonline.com.