05000324/LER-2016-002

LER-2016-002, High Pressure Coolant Injection System Inoperable due to Failed Relay Coil

Brunswick Steam Electric Plant (Bsep), Unit 2
Event date:	07-05-2016
Report date:	08-29-2016
Reporting criterion:	10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
3242016002R00 - NRC Website

LER 16-002-00 for Brunswick Steam Electric Plant (BSEP), Units 1 and 2, Regarding Emergency Diesel Generator 3 Inoperable Due to Failure to Auto-Start

ML16132A076
Person / Time
Site:	Brunswick
Issue date:	05/02/2016
From:	Gideon W R Duke Energy Progress
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BSEP 16-0030 LER 16-002-00
Download: ML16132A076 (9)

comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

Brunswick Steam Electric Plant (BSEP), 002 05000-324 2016 - 00 Energy Industry Identification System (EIIS) codes are identified in the text as [XX].

Background

Initial Conditions At the time of this event, Unit 2 was in Mode 1 at approximately 100 percent of rated thermal power. The Reactor Core Isolation Cooling (RCIC) system [BN], Automatic Depressurization System (ADS), Low Pressure Coolant Injection (LPCI) system [BO], and Core Spray (CS) system [BM] were operable at the time of the event.

Reportability Criteria This condition is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D), as an event or condition that could have prevented the fulfillment of the safety function of a system that is needed to mitigate the consequences of an accident. The NRC was initially notified of this event on July 5, 2016 (i.e., Event Number 52064).

Event Description

On July 5, 2016, at 1640 Eastern Daylight Time (EDT), the Unit 2 High Pressure Coolant Injection (HPCI) system [BJ] was declared inoperable after the control room received annunciator 2-A-1 (3-3), "HPCI Aux Oil Pump Motor Overload." Upon further investigation, it was determined that the HPCI Auxiliary Oil Pump motor overload alarm relay (i.e., 2-2XDA-B11-74) had failed and blown the associated control circuit fuse (i.e., 2-2XDA-B11-2FU). The HPCI Auxiliary Oil Pump provides hydraulic pressure required to open the HPCI Turbine Stop Valve and the HPCI Turbine Control Valve during initial HPCI startup. With failure of the relay, the HPCI Auxiliary Oil Pump was incapable of starting; rendering the HPCI system inoperable.

Operability of the HPCI system was restored on July 6, 2016, at 1050 EDT.

Event Cause The cause of the Unit 2 HPCI inoperability was determined to be age related failure of HPCI Auxiliary Oil Pump motor overload alarm relay (i.e., 2-2XDA-B11-74) coil.

The failed relay is normally energized and was original plant equipment. The equipment reliability classification was "Important" as opposed to "Critical." Based on this classification, preventive maintenance had not been performed to replace the Unit 2 relay.

The Unit 1 HPCI Auxiliary Oil Pump motor overload alarm relay was last replaced in January 1995.

comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

Brunswick Steam Electric Plant (BSEP), 05000-324

3. LER NUMBER

002 2016 00 Safety Assessment The safety significance of this event was minimal. The RCIC system, ADS, LPCI system, and CS system were all operable at the time of the event. The HPCI system was restored to operable status within the 14-day Technical Specification Completion Time.

Corrective Actions

Any changes to the corrective actions and schedules noted below will be made in accordance with the site's corrective action program.

The following corrective actions have been completed or are planned.

• Operability of the HPCI system was restored on July 6, 2016, at 1050 EDT.

• Preventive Maintenance tasks to replace the Unit 1 and Unit 2 HPCI Auxiliary Oil Pump motor overload relays, on an appropriate frequency, will be created. This is currently scheduled to be completed by November 4, 2016.

• The equipment reliability classifications for the Unit 1 and Unit 2 HPCI Auxiliary Oil Pump motor overload relays will be changed to "Critical." This is currently scheduled to be completed by November 11, 2016.

• A review of control wiring diagrams for Mitigating Systems Performance Index (MSPI) monitored components will be performed to identify components with "Important" equipment reliability classification. This review will either document classification is correct or change to critical if appropriate and implement appropriate preventive maintenance strategies. This is currently scheduled to be completed by December 15, 2016.

Previous Similar Events

A review of LERs and condition reports for the past five years identified the following previous similar occurrences.

• LER 1-2015-001, Revision 1, dated December 21, 2015, reported inoperability of the Unit 1 HPCI system due to a faulty magnetic motor contactor coil (i.e., M-coil) within the HPCI turbine auxiliary oil pump motor contactor 1-1XDA-B11-M. The failure of the coil was determined to be most likely long term thermal cycling. The coil was replaced and the HPCI system was returned to operable status on February 20, 2015. Based on the age of the M-coil, a one-time replacement is expected to prevent recurrence of this failure through the end of licensed operation for BSEP. Therefore, no periodic replacement was recommended. Corrective actions associated with this LER were component level/function level and, therefore, would not be expected to prevent recurrence of HPCI system inoperability.

comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to NEOB-10202, (3150.0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

Brunswick Steam Electric Plant (BSEP), 002 05000-324 2016 - 00

• LER 1-2012-004, dated June 29, 2012, reported HPCI system inoperability due to the erratic HPCI governor operation caused by a failed ramp generator signal converter (RGSC) operational amplifier. The root cause of the RGSC failure is the lack of a replacement preventive maintenance (PM) task for the RGSC. The corrective action to prevent recurrence for this event was to establish the appropriate PM for periodic replacement of the RGSC on both units' HPCI systems. Corrective actions associated with this LER were component level/function level and, therefore, would not be expected to prevent recurrence of HPCI system inoperability.

Commitments No regulatory commitments are contained in this report.