05000311/LER-2016-001

LER-2016-001, AFW Loop Response Time Exceeded Technical Specifications

Salem Generating Station - Unit 2
Event date:	04-20-2015
Report date:	03-21-2016
3112016001R00 - NRC Website

LER 16-001-00 for Salem, Unit 2, Regarding AFW Loop Response Time Exceeded Technical Specifications

ML16081A369
Person / Time
Site:	Salem
Issue date:	03/21/2016
From:	Carr E Public Service Enterprise Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LR-N16-0068 LER 16-001-00
Download: ML16081A369 (6)

the Desk Officer, Office d Information and Regulatory Affairs, NEOB-1 0202, (3150-01 04), 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.

Salem Generating Station — Unit 2 05000311

PLANT AND SYSTEM IDENTIFICATION

Westinghouse-Pressurized Water Reactor {PWR/4} Auxiliary Feedwater System/Pump Flow Control Valves {BA/FCV) *Energy Industry Identification System (EllS) codes and component function identifier codes appear as {SS/COO}.

IDENTIFICATION OF OCCURRENCE

Event Date: 04/20/2015 Discovery Date: 01/19/2016

CONDITIONS PRIOR TO OCCURRENCE

Salem Unit 2 was in Mode 1 at 100 percent rated thermal power (RTP).

DESCRIPTION OF OCCURRRENCE

On January 19, 2016, while reviewing outage data, plant staff recognized that anomalous data collected in October 2015, for the 21 Auxiliary Feed Pump time response loop resulted in failure to meet a surveillance, rendering that channel of Auxiliary Feedwater automatic actuation inoperable. In November 2015, the isolation valve for the pressure override defeat pressure transmitter was found closed. The pressure transmitter provides an input into the 21 AFW Pump run-out protection circuit. With the isolation valve closed, it would take longer to sense pump discharge head and consequently the opening of the auxiliary feed pump flow control valves {BA/FCV} would be slower than normal. The AFW flow control valves will not open until adequate pump discharge head is sensed by the pressure transmitter. This condition resulted in 21 Auxiliary Feedwater Pump loop time response greater than Technical Specification (TS) acceptance criteria. The failed channel was not recognized and the TS action was not taken, resulting in a condition prohibited by TS. The investigation revealed that the condition most likely existed since April 20, 2015, when maintenance activities were performed on the auxiliary feedwater pump discharge pressure transmitter. This condition resulted in 21 Auxiliary Feedwater Pump loop time response greater than the acceptance criteria required by surveillance 4.3.2.1.3. The isolation valve was opened and the surveillance was performed satisfactorily.

Timeline 04/20/15 2PA3450, 21 Auxiliary Feed Pump Discharge Pressure Transmitter, calibration done 10/18/15 Operations performed time response testing on 21 Auxiliary Feedwater (AFW) loop 11/18/15 I&C technicians documented unsatisfactory time response for 21 AFW loop 11/20/15 Instrument isolation valve for 2PA3450 found closed 01/19/16 Plant staff review of outage data identified failed surveillance and need to review condition for reportability the Desk Officer, Office of Information and Regulatory Affairs, 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.

CONTINUATION SHEET

2. DOCKET 6. LER NUMBER Operations began time response testing in advance of the scheduled refueling outage while still in MODE 1. When 21 AFW loop was tested, the long response time of the flow control valves for the two loops associated with the pump were noticed, but not documented or investigated for impact on operability.

When I&C began to collate time response data from the outage testing, they recognized the failure to meet the acceptance criteria for 21 AFW loop time response. The isolation valve for the discharge pressure transmitter was found closed. The isolation valve was opened, and the loop response time testing was completed with satisfactory results.

The investigation for the mispositioned pressure transmitter isolation valve did not definitively conclude that the maintenance activities of April 20, 2015, created the condition, but no other procedures operate the isolation valve. All other AFW surveillances were completed satisfactorily during the period from April through October. The dynamic system response and the pressure override function are only tested by the time response surveillance ; the other AFW surveillances would not reveal the mispositioned pressure transmitter isolation valve.

The impact of the mispositioned valve was not recognized until a review of outage data was performed on January 19, 2016.

This event is being recorded in accordance with 10CFR50.73 (a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications.

CAUSE OF EVENT

The most likely cause of this event was the failure to return the auxiliary feedwater pump discharge pressure transmitter instrument isolation valve to the open position following transmitter calibration.

SAFETY CONSEQUENCES AND IMPLICATIONS

The Auxiliary Feedwater (AFW) System serves as a backup system for supplying feedwater to the secondary side of the steam generators at times when the Main Feedwater System is not available. The AFW System is relied upon to prevent core damage and system overpressurization.

An engineering review concluded that while the AFW loop response time test results did not meet the procedural acceptance criteria, the accident analysis assumptions remained valid. The ATWS (Anticipated Transient Without Scram) was determined to be the limiting accident, and the loop response times were still bounded by the existing analyses. There were no safety consequences as a result of this event the Desk Officer, Office of Information and Regulatory Affairs, 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.

CONTINUATION SHEET

2. DOCKET 6. LER NUMBER

SAFETY SYSTEM FUNCTIONAL FAILURE

This condition did not result a safety system functional failure as defined in NEI 99-02, Regulatory Assessment Performance Indicator Guidelines.

PREVIOUS EVENTS

A review of previous events for the past three years identified no similar events.

CORRECTIVE ACTIONS

The pressure transmitter isolation valve was re-opened and the time response surveillance for 21 Auxiliary Pump flow control was performed with satisfactory results.

COMMITMENTS

There are no regulatory commitments contained in this LER.