Event Notification Report for September 13, 2021

EN Revision Imported Date: 9/13/2021

EN Revision Text: HIGH PRESSURE CORE SPRAY INOPERABLE

At 0033 CDT on September 9, 2021, Grand Gulf Nuclear Station (GGNS) was operating at 70 percent power when the High Pressure Core Spray (HPCS) was declared inoperable. The inoperability determination was made due to control room annunciations. In accordance with GGNS Technical Specification 3.5.1.B.1, the Reactor Core Isolation Cooling system was verified to be operable. Troubleshooting is in progress.

This event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(D) as an event or condition which could have prevented the fulfillment of a safety function.

The NRC Resident Inspector has been notified.

EN Revision Imported Date: 9/13/2021

EN Revision Text: PART 21 REPORT - NONCONFORMING RELAY LED TO FAILURES OF BATTERY CHARGERS

The following is a synopsis of information received via E-mail:

Component Description:
AMETEK Part Number 07-740108-00, K306 relay, used in the float/equalize circuit of AMETEK Battery Chargers. The relay is a solid-state timer manufactured by Omron with manufacturer part number H3CR-A-AC100-240/DC100125.

Problem You Could See:
AMETEK was notified of a condition of a nonconforming K306 relay that led to failures of battery chargers. AEP DC Cook reported a single failure of a K306 Float/Equalize timer relay in a controlled environment where the relay failed to transfer from float to equalize and caused the DC output to fail. Transferring the battery charger to equalize mode is always a manual operation and the float/equalize function is typically used after an outage or a discharge test in order to bring the batteries back to full charge. Before performing a discharge test, the charger should be put in equalize mode. AMETEK was not able to evaluate this specific instance of failure, but it was determined the circuit does not meet the minimum contact current rating. As a result, the operation of the relay may be unreliable and the charger may experience a loss of output when equalize is initiated, failing to charge the batteries. The failed relay was installed in 2017 and was original to the equipment.

Effect on System Performance:
If the charger fails to transfer between float and equalize, the equalize light may turn on, the charger output will fail, voltage will drop below float voltage or to 0, and there will be no charging capabilities. An alarm will indicate Low DC voltage in the event the charger does not transfer between float and equalize. The charger will restart after the AC input breaker is cycled Off and On. The relay should be replaced if the charger output is lost. Other alarm(s) may be included with the design:
- Battery Discharge Alarm
- Low Current Alarm
The battery will charge with float voltage, but will take longer than with equalize voltage (~8-24 hours after charging current stabilizes).

The safety impact is a loss of battery charger output after an event where the float/equalize button is utilized and does not retransfer to equalize for charging. If the charger fails to transfer and the output is lost prior to a safety event, the battery may not be at full capacity for a shutdown. Each utility will need to evaluate the application of the battery charger and the battery it is charging.

Affected Entities:
Alabama Power Company; Arkansas Nuclear One; Atomic Energy of Canada; Constellation Energy; Consumer's Power, Palisades; Dominion - Kewaunee; Dominion Energy; Dominion Inc.; Duke Energy; Duke Power Co.; EM Test (Switzerland) GMBH; Engine Systems; Ergytech Inc.; Exelon; Exelon Generation Co.; First Energy; Formosa Nextech Co.; Framatome Technologies; Georgia Power; Indiana Michigan Power Co.; Millstone Nuclear Power Station; Niagara Mohawk; NPP Krsko; Progress Energy; TVA; TVA Watts Bar; Ulysses - Taiwan Power; and Ulysses System Development.

Ametek Contact: Ametek Solidstate Controls Client Services group, 1-800-222-9079 or 614-846-7500, extension 1.

OFFSITE NOTIFICATION DUE TO CONTRACTOR FATALITY

"This is a four-hour notification, non-emergency for a notification of another government agency. This event is being reported under 10 CFR 50.72(b)(2)(xi) and 10 CFR 72.75(b)(2).

"At 1055 EDT on 9/10/21, an employee of a site contractor that was performing work under a contract and in possession of the immediate area where the work was being performed, was involved in a material handling accident in the owner controlled area at Three Mile Island. Londonderry Township EMS and Fire responded to render assistance to the individual. Upon arrival to the site, medical personnel declared the individual deceased.

"The fatality was work related and the individual was outside of the Radiological Controlled Area."

DEGRADED CONDITION IDENTIFIED WHILE UNIT SHUTDOWN

"On September 12, 2021, at 1728 EDT, with Unit 1 in Mode 5 (Cold Shutdown) while performing inspections of the North Anna Power Station Unit 1 reactor vessel head flange area, a weld leak was identified on the reactor vessel flange leak-off line that connects to the flange between the inner and outer head o-rings. Entered TRM 3.4.6 Condition B for ASME Code Class 1,2, and 3 components. With known leakage past the inner head o-ring, this condition is reported since the fault in the tubing is considered pressure boundary [Reactor Coolant System] leakage.

"This event is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(A) for any event or condition that results in the condition of the nuclear power plant, including its principle safety barriers, being seriously degraded."

The NRC Resident has been notified.