05000333/LER-2021-002, Automatic High Pressure Coolant Injection (HPCI) System Function Prevented by Control Circuit Relay Failure

Automatic High Pressure Coolant Injection (HPCI) System Function Prevented by Control Circuit Relay Failure

ML22014A173
Person / Time
Site:	FitzPatrick
Issue date:	01/14/2022
From:	Timothy Peter Exelon Generation Co LLC
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
JAFP-22-0001 LER 2021-002-00
Download: ML22014A173 (4)

LER-2021-002, Automatic High Pressure Coolant Injection (HPCI) System Function Prevented by Control Circuit Relay Failure

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function
3332021002R00 - NRC Website

text

Exelon Generation James A. FltzPatrick NPP P.O. Box 110 Lycoming. NY 13093

Timothy C. Peter Site Vice President-JAF

JAFP-22-0001 January 14, 2022

United States Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001

James A. FitzPatrick Nuclear Power Plant Renewed Facility Operating License No. DPR-059 NRC Docket No. 50-333

Subject: LER: 2021-002, Automatic High Pressure Coolant Injection (HPCI)

System Function Prevented by Control Circuit Relay Failure

Dear Sir or Madam:

This report is being submitted pursuant to 10 CFR 50.73(a)(2)(v)(D).

There are no new regulatory commitments contained in this report.

Questions concerning this report may be addressed to Mr. Richard Sullivan, Regulatory Assurance Manager, at (315) 349-6562.

Since1 ~

4':t. Peter Site Vice President

TCP/RS/mh

Enclosure : LER: 2021-002, Automatic High Pressure Coolant Injection (HPCI)

System Function Prevented by Control Circuit Relay Failure

cc: USNRC, Region I Administrator USNRC, Project Manager USNRC, Resident Inspector INPO Records Center (IRIS)

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2023 (08-2020)

James A. FitzPatrick Nuclear Power Plant 05000333 1 OF 3

4. Title Automatic High Pressure Coolant Injection (HPCI) System Functio n Prevented by Control Circuit Relay Failure

5. Event Date 6. LER Number 7. Report Date 8. Other Facilities Involved Revision Facility Name Docket Number Month Day Year Year Sequential Number No. Month Day Year N/A N/A

Facility Name Docket Number 11 18 2021 2021 - 002 - 00   N/A N/A

9. Operating Mode 10. Power Level 1 100 No Yes (If yes, complete 15. Expected Submission date)

Abstract (Limit to 1560 spaces, i.e., approximately 15 single-spaced typewritten lines)

On November 18, 2021, during a simulated actuation test of High Pressure Coolant Injection (HPCI),

23MOV-19, HPCI Pump Discharge to Reactor Inboard Isolation Valv e, failed to open. This was caused by a failure of the valves control logic circuit relay 23A-K54 to a ctuate. An investigation identified contacts 3-7 were intermittently not closing. The failure of the contacts to clos e was due to binding between the associated spring leave and the contact carrier channel sidewall. The binding was due to dimensional issues that caused chaffing on the sidewall of the contact carrier channel. This chaffing w orsened over time until binding started to occur intermittently within 23A-K54.

The condition of this relay could have prevented the automatic actuation of HPCI and is reportable per 10 CFR 50.73(a)(2)(v)(D). Manual actuation of HPCI remained unaffected by this condition; therefore, the system remained available.

Relay 23A-K54 was replaced and HPCI was restored to Operable on November 19, 2021.

NRC FORM 366 (08-2020)

Background

The High Pressure Coolant Injection (HPCI) System [EIIS Identif ier: BJ] at James A. FitzPatrick Nuclear Power Plant (JAF) is a part of the Emergency Core Cooling System (ECC S); HPCI provides and maintains an adequate coolant inventory inside the Reactor Pressure Vessel [ RPV] to prevent damage to the reactor core under postulated accident scenarios. The system is comprised of various components which include pumps, valves, piping, and instrumentation. The HPCI System is require d to actuate automatically to perform their design functions but it may be initiated manually. Automa tic initiation occurs for conditions of Reactor Vessel Water Level - Low Low (Level 2) or Drywell Pressure - High (Level 8).

The Technical Specification (TS) Surveillance Requirement (SR) 3.5.1.10 ensures HPCI actuates on an actual or simulated automatic initiation signal by verifying initiatio n logic will cause the system to operate as designed, including actuation of the system throughout its emer gency operating sequence, automatic pump startup and actuation of all automatic valves to their required positions. This Surveillance also verifies that the HPCI System will automatically restart on an RPV low water leve l signal received subsequent to an RPV high water level trip.

HPCI Pump Discharge to Reactor Inboard Isolation Valve 23MOV-19 is one of the valves that is required to open in order for the system to perform its function.

Event Description

On November 18, 2021, planned testing was performed in accordan ce with ST-4E, HPCI and SGT Logic System Functional and Simulated Automatic Actuation Test, for S R 3.5.1.10. During the high drywell pressure operation test 23MOV-19 was confirmed to open satisfactorily. D uring the subsequent RPV low water level operation test 23MOV-19 failed to open.

It was determined that the valve failed to change position due to the valves control logic circuit relay, 23A-K54. Troubleshooting determined a high resistance connectio n between contacts 3-7. Manual cycling of the contacts showed that the contacts were intermittently not c losing with a visible air gap.

The intermittent failure of 23A-K54 to actuate is a condition w hich could have prevented fulfillment of the safety function for the HPCI system. This condition was reporte d in accordance with 10 CFR 50.72(b)(3)(v)(D) via ENS 55593.

Event Analysis

A failure analysis of 23A-K54 was performed. All contact surfac es appeared to be in very good condition.

There was no evidence of arcing, pitting, contamination, corros ion, or tarnishing.

The condition observed during the event was able to be duplicat ed on 4 of 20 trials. Contacts 3-7 resistance were measured high and an air gap was visible between the matin g surfaces. Contacts 3-7 are typically open because the relay is normally energized (fail safe) and closes to open injection valve 23MOV-19. When the contacts did not close the valve did not open. On the instances when Contacts 3-7 was open when expected to be closed the associated spring leave moved during relay pic kup and bound in a position that caused the intermittent issue.

The spring leave channels were examined and dimensions were col lected for the channel associated with contacts 3-7 and compared to the neighboring channel. The channel for contacts 3-7 is approximately 2.5 to NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2023 (08-2020)

James A. FitzPatrick Nuclear Power Plant 05000 - 333 NUMBER N0.

2021 - 002 - 00 4.5 mils more narrow than the other channel, which would explai n the tighter fit and potential for binding. In addition, chaffing was evident on the sidewall of the channel f or contacts 3-7.

The binding was due to dimensional issues that caused chaffing on the sidewall of the contact carrier channel. This chaffing worsened over time until binding started to occur intermittently within 23A-K54.

However, there is no firm evidence that the chaffing would have caused binding or prevented the fulfillment of a safety function prior to time of discovery.

The condition of this relay could have prevented the automatic actuation of HPCI, reportable per 10 CFR 50.73(a)(2)(v)(D). Manual actuation of HPCI remained unaffected by this condition; therefore, the system remained available.

Cause

The failure of 23MOV-19 to open was caused by binding in relay 23A-K54 contacts 3-7. Dimensional issues in the contact spring channel led to tighter fit and intermitte nt binding.

Similar Events

Condition Report: CR-JAF-2011-05502 dated October 28, 2011: eva luation of General Electric Hatchi (GEH)

Part 21 report SC-11-09. The report identified a defect in the same relay model 12HGA11A52F. For FitzPatrick, installed relays were acceptable for continued ope ration based on physical inspection and testing. The component described by this LER was not part of th e population of components identified by SC-11-09 in 2011.

FAILED COMPONENT IDENTIFICATION:

Manufacturer: General Electric Manufacturer Model Number: 12HGA11A52F Manufacturer Code: G080 Component Code: RLY FitzPatrick Component ID: 23A-K54

Corrective Actions

Completed Actions Relay 23A-K54 was replaced and HPCI was restored to Operable st atus Planned Actions An extent of condition review will be conducted

Safety Significance

Nuclear safety - There were no actual consequences caused by this condition. The potential consequence during a postulated accident scenario is when HPCI cycles and t he relay may chaff and bind as described in this LER, if 23MOV-19 automatically actuates multiple times. Th is risk is minimized because manual operation of HPCI remained unaffected by this condition. In addition, pla nt operators are trained to control HPCI in order to maintain vessel inventory and minimize HPCI cycling during e vents.

References Issue Report - IR 04461845, 23MOV-19 HPCI Injection Valve did n ot Function during ST-4E, dated November 18, 2021