Event Notification Report for January 11, 2024

PART 21 - EATON-CUTLER HAMMER RELAY ON EMERGENCY DIESEL FAILED

The following information was provided by the licensee via email and phone call:

"On January 9, 2024, VC Summer Nuclear Station (VCSNS) determined a manufacturing defect affecting a control power circuit monitor (CP1) relay on its 'B' emergency diesel generator (EDG) was reportable under Part 21.

"On November 12, 2021, the 'B' EDG was rendered inoperable when its CP1 relay de-energized due to mechanical binding of the magnet carrier assembly. The binding was caused by a manufacturing defect that allowed heat-induced shrinkage to reduce the clearance between the magnet carrier and adjacent coil housing and base, preventing it from moving freely. VCSNS replaced the effected relay and restored operability of its 'B' EDG.

"Manufacturer/Model: Eaton-Cutler Hammer D26MRD30A1

"A written notification in accordance with 10 CFR 21.21(d)(3)(ii) will be provided within 30 days. The NRC Senior Resident Inspector has been notified."

The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:

The plant has notified the manufacturer. It is not known if any other plants are affected by this defect.

PART 21 - GOULD FIELD FLASH RELAY ON EMERGENCY DIESEL FAILED

The following information was provided by the licensee via email and phone call:

"On January 9, 2024, VC Summer Nuclear Station (VCSNS) determined a manufacturing defect affecting a field flash contactor (K2) relay on its 'B' emergency diesel generator (EDG) was reportable under Part 21.

"During testing on May 5, 2021, the 'B' EDG was rendered inoperable when its K2 relay coil switch exhibited intermittent binding due to insufficient clearances of the switch actuator from the protective case and plastic switch molding. The inadequate clearances resulted in accelerated loss of graphite lubrication at these locations, which led to mechanical binding. VCSNS replaced the effected relay and restored operability of its 'B' EDG.

"Manufacturer/Model: Gould F10NOCLD1 DC coil switch

"A written notification in accordance with 10 CFR 21.21(d)(3)(ii) will be provided within 30 days. The NRC Senior Resident Inspector has been notified."

The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:

The licensee did not notify the intellectual property owner because the manufacturer is no longer operating or in business. They are not aware of other plants that utilize this coil switch.