NRC 2nd Quarter Inspection Report Finds New Safety Concern at Pilgrim

COURTESY PILGRIM NUCLEAR POWER STATION

COURTESY PILGRIM NUCLEAR POWER STATION

PLYMOUTH – The Nuclear Regulatory Commission released their second quarter inspection report for the Pilgrim Nuclear Power Station in Plymouth, pointing to a new safety concern.

The report contains one NRC-identified “Green” inspection finding and one Entergy-identified “Green” violation.

“Green” represents a very low safety significance.

The NRC-identified finding is associated with an inadequate design verification for two circulating-water traveling screens.

The screens, which were replaced during the plant’s latest refueling and maintenance outage in May, are used to filter out foreign material from water pumped into the plant for cooling purposes.

It caused the shear pins in the two traveling screens to prematurely fail during a large seaweed intrusion event on May 5, which led to a 50 percent rapid reduction in reactor power.

NRC inspectors determined that the most significant contributing cause for the finding was that Entergy did not implement appropriate measures to ensure a thorough review of the design specification verses the supply vendor’s fabrication documentation.

Half-inch shear pins were installed rather than the 11/16ths-inch pins that should have been put in place.

The half-inch pins had a maximum shear strength of 3,877 pounds while the 11/16ths-inch pins have a maximum shear strength of 8,050 pounds.

Entergy has installed the correct shear pins since the event, has revised its system drawings to clearly depict the required size pins and is performing an apparent cause evaluation.

The inspection report also documents completion of the NRC’s review of the initial interim actions taken by Entergy in response to Pilgrim entering Column 4 of their Action Matrix.

The inspectors determined that all interim actions were fully implemented by late January 2016.

The NRC has completed the Phase “A” and “B” inspections of their heightened oversight process for Pilgrim.

The Commission will schedule Phase “C” after Entergy notifies them of its readiness.

That Phase will take place later this year or early next year.

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