Pilgrim Station: Another scram
PLYMOUTH — Depending on your perspective, Monday’s shut down of the Pilgrim Nuclear Power Station was either another example of the plant’s “defense in depth” safety or additional evidence of its vulnerability.
The press release from Pilgrim arrived just after 10 a.m. Tuesday morning, Oct. 15, and referenced a successful scram (sudden shutdown) of the reactor at 9:21 p.m. the previous evening. According to Pilgrim spokesman Carol Wightman, “Pilgrim Station automatically shut down due to the loss of one of the two 345-kV lines that provides offsite power to the plant.”
“Last week,” Wightman explained, “NStar removed the second 345-kV line from service for planned maintenance. As designed, the plant’s emergency diesel generators immediately started and are safely powering the plant.”
The cause of the shut down is not immediately apparent from the release.
“While Pilgrim is shut down, we will take advantage of this time to perform maintenance that cannot be done while the plant is operating,” was all that Wightman added. “The plant will return to service following NStar’s restoration of offsite power and the completion of maintenance.”
Asked directly about the cause of the shut down, Wightman referred the question to NStar.
NStar spokesman Michael Durand was not hesitant to acknowledge the facts, as he knew them to that point. First, however, he provided a little background.
“In a coordinated effort between NStar, National Grid and Pilgrim Station’s operators,” Durand explained, “we had taken one of those two lines out of service for a type of routine maintenance traditionally done at this time of year.”
NStar does that work at this time of year, Durand noted, because there is less demand for electricity.
That line being out of service, however, was not the cause of the scram.
“A pole that we set this past May, as part of a substation upgrade in Carver, broke last night,” Durand said. “The cause of break was not readily apparent, but we are investigating.”
The primary focus at this time is to repair the line, Durand added.
“The pole breaking led to the transmission line coming out of service,” Durand said, which left the plant without any outside power.
At no time, Wightman told the Old Colony, did the event have any impact on the health and safety of the public or Pilgrim’s employees.
“We have multiple ways (know as Defense in Depth) to power the safety systems at Pilgrim,” Wightman said, ”including, but not limited to, three diesel generators.”
Customers on the New England grid were not impacted by the event, Durand said, “which was seen as a momentary flicker by customers across Eastern Massachusetts.”
Durand said they expected the repairs to be complete and Pilgrim to be reconnected by Tuesday evening.
Durand also said that while the line is out of service other equipment on the regional grid is easily handling the current demand for electricity.
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