Pilgrim Nuclear Power Station in Plymouth shut down over the weekend after operators discovered a problem with feedwater valves. The station wound down Friday evening, and completely shut down just before 12:30 am Saturday, Nuclear Regulatory Commission (NRC) spokesman Neil Sheehan said.
“Feedwater is water that is pumped into the reactor vessel, boiled by the nuclear fissioning process, converted to steam, and piped to the turbine to spin it and generate electricity,” Sheehan wrote in an email. “The feedwater regulating valves control the amount of water being pumped into the reactor vessel, and in turn affect power output levels.”
“They are not considered part of the key safety systems,” Pilgrim spokesman Patrick O’Brien wrote. “The pneumatic controllers that operate the valves have been replaced to correct the issue.”
As of Tuesday, the station remained offline; it’s the third such instance since the start of the year.
Pilgrim shut down on March 6 because of a leak in the feedwater heater — “same system but different issue altogether,” Sheehan said.
Plant operators initiated a scram, an emergency shutdown, on Jan. 4 after a 345,000-volt transmission line went offline due to a broken lightning arrestor in Sandwich, he said.
Pilgrim languishes in the NRC’s Multiple/Repetitive Degraded Cornerstone column, the stage just before nuclear regulators impose a mandatory shutdown in the interest of public safety. Of the nation’s 99 operational reactors, only the two at Arkansas Nuclear One in Russellville, Ark., are rated as unfavorably as Pilgrim by the NRC. Pilgrim and Arkansas Nuclear One share the same owner, New Orleans–based Entergy Corp.
When Pilgrim will start generating again is deemed economically sensitive information that won’t be disclosed to the public, O’Brien said.
Pilgrim remains on track to close by the end of May next year, Sheehan said.