ML18036A515

LER 92-001-00:on 920125,valve Logic Channel a Failed Resulting in Actuation of Engineered Safety Features.Caused by Thermal Aging of Type CR-120 Relay Coil.Failed Relay Coil replaced.W/920214 Ltr

ML18036A515
Person / Time
Site:	Browns Ferry
Issue date:	02/14/1992
From:	Ridgell E, Zeringue O TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-001, LER-92-1, NUDOCS 9202190129
Download: ML18036A515 (16)

Text

ACCELERATED DIS BUTION DEMONST TION SYSTEM

,1 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDE)

ACCESSION NBR:9202190129 DOC.DATE: 92/02/14 NOTARIZED: NO DOCKET FA'CIL:50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 AUTH. NAME AUTHOR AFFILIATION RIDGELL,E.M. Tennessee Valley Authority ZERINGUE,O.J. Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 92-001-00:on 920125,valve logic channel A failed resulting in actuation of Engineered Safety Features. Caused D by thermal aging of a type CR-120 relay co>.l.Replacing GE type CR-120 relay coils in normally energized.W/920214 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR J ENCL / SIZE:

TITLE: 50.73/50.9 Licensee Event:Report (LER), Incident Rpt, etc.

NOTES A RECIPIENT COPIES RECIPIENT COPIES D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL SANDERS,M. 1 1 HEBDON,F 1 1 D WILLIAMS,J. 1 1 INTERNAL: ACNW 2 2 ACRS AEOD/DOA 1 1 AEOD/DS P/TPAB AEOD/ROAB/DSP 2 2 NRR/DET/ECMB 9H NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB NRR/DREP/PRPB11 2 2 NRR/DST/SELB SD NRR/DST/SICBSH3 1 1 NRR/DS /;S:PLB Dl NRR/DST/SRXB SE 1 1 RE 02 RES/DSIR/EIB 1 1 RG FIL Ol EXTERNAL EG&G BRYCE I J ~ H 3 3 L ST LOBBY WARD NRC PDR 1 1 NSIC MURPHY,G.A NSIC POORE,W. 1 1 NUDOCS FULL,TXT D

D D

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Tennessee Vatley Authority, Post Otfice Box 2000. Decatur.'Alabanta 35609 O. J. 'Ike'eringue Vice President, Browns Ferry Operations FEB $ ,4 1992 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

TVA BROWNS FERRY NUCLEAR PLANT (BFN) UNIT 3 DOCKET NO. 50-296 FACILITY OPERATING LICENSE DPR-67 LICENSEE EVENT REPORT LER-50-296/92001 The enclosed report provides details concerning an unplanned Engineered Safety Feature actuation caused by a failed relay. This report is submitted in accordance with 10 CFR 50.73(a)(2)(iv).

Sincerely, J. Zeri e.

Enclosure cc: See page 2 9202190129 920214 ADOCK 05000296 PDR 5 PDR 2 EPz rjr

ii <5 U.S. Nuclear Regulatory Commission

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FEB i4 >ssc cc (Enclosure )

INPO Records Center

,Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia. 30339 Paul Krippner American Nuclear Insurers The Exchange, Suite 245 270 Farmington Avenue Farmington, Connecticut 06032 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35609-2000 Regional Administrator U.S.. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 2900 Atlanta, Georgia 30323 Thierry 'M. Ross, Project Manager U.S. Nuclear Regulatory Commission One Mhite Flint, North 11555 Rockville Pike Rockville, Maryland 20852

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NRC Form 366 (6-89)

FACILITY NAME (1)

U.S LEAR REGULATORY COWISSION LICENSEE EVENT REPORT (LER) l Approved OHB No. 3150-0104 Expires 4/30/92 IDOCKET NUMBER (2) I wn r TITLE (4)

R P T I I I I I SEQUENTIAL I REVISION I I I I FACILITY NAMES IDOCKET NUMBER(S)

I I I I I I I I I I OPERATING I ITHIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5:

MODE I I wi I20.402(b) i20.405(c) I~I50.73(a)(2)(iv) l73 71(b)

POWER I l l20 405(a)(l)(i) F50.36(c)( 1) (50.73(a)(2)(v) (73.71(c)

LEVEL I )20.405(a)( l)(ii) F50.36(c)(2) [50.73(a)(2)(vii) [OTHER (Specify in

)20.405(a)( 1)(iii) I l50.73(a)(2)(i) [50.73(a)(2)(viii)(A) ) Abstract below and in

)20.405(a)( 1)(iv) [50.73(a)(2)(ii) ]50.73(a)(2)(viii)(B) t Text, NRC Form 366A) 4 NAME

( AREA CODE HP T HP N NT I I I IREPORTABLEI I I I IREPORTABLEI N P Y TH I I I I I I I I I p 0 4 EXPECTED I SUBHI S SION l I I m P T 0 B N T ABSTRACT (Limit to 1400 spaces, i .e., approximately fifteen single-space typewritten lines) ( 16)

On January 25, 1992 at 0720 CST, a Unit 3 relay coil, General Electric (GE) type CR-120, associated with Primary Containment Atmosphere Control Valve Logic Channel A failed resulting in actuation of Engineered Safety Features.

The root cause of this event has been attributed to an end-of-life failure caused by the thermal aging of a GE type CR-120 relay coil.

Immediate corrective actions included replacing the failed relay coil.

Additional corrective actions include replacing the GE type CR-120 relay coils in normally energized, safety-related circuits prior to the restart of Units 1 and 3 and prior to startup of Unit 2 following the Cycle 6 refueling outage. In addition, relay coils in this application whose failure could potentially lead to a Unit 2 plant shutdown were committed to be replaced by March 30, 1992.

NRC Form 366(6-89)

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NRC Form 366A (6-89)

U.S. EAR REGULATORY COHHISSION LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION t Approved OHB No. 3150-0104 Expires 4/30/92 FACILITY NAHE (1) IOOCKET NUHBER (2)

I tSEQUENTIAL ) (REVISION/

Browns Ferry Unit 3 I I I I I TEXT (If more space is required, use additional NRC Form 366A's) ( 17)

I PLANT CONDITIONS Unit 2 was at 60 percent power operations and had just completed rod swap operations. Units 1 and 3 were shutdown and defueled.

I I. DESCRIPTION OF EVENT A. ~~~t:

On January 25, 1992 at 0720 CST,, a Unit 3 relay coil, General Electric (GE) type CR-120, associated with Primary Containment Atmosphere Control Valve Logic Channel A [JM] failed resulting in actuation of Engineered Safety Features (ESF) [JE].

The ESF actuations, a partial Primary Containment Isolation System (PCIS) group 6 isolation, included isolation of the Unit 3 reactor building and the refuel floor [NG], and actuation of the B and C trains of the Standby Gas Treatment System (SBGT) [WF] and the B train of the Control Room Emergency Ventilation (CREV) [VI] system.

As a result of the ESF actuations, TVA reports this event in accordance with 10 CFR 50.73(a)(2)(iv) as an event or condition that resulted in manual or automatic actuation of any ESF.

t t t t t t t t th B.

~t:

n 1 None.

C.

January 25, 1992 at 0720 CST GE type CR-120 relay coil failed resulting in ESF actuations.

1100 CST TVA provided four-hour non-emergency report to NRC as required by 10 CFR 50.72(b)(2)(ii).

1400 CST The failed relay coil was replaced and the ESF isolation signal was reset.

NRC Form 366(6-89)

iI NRC Form 366A U.S. NUCLEAR REGULATORY CONNISSION Approved ONB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE E43A'EPORT (LER)

TEXT CONTINUATION FACILITY NANE (1) IOOCKET NUNBER (2)

I I I I SE()UENTIAL I IREVISIONI I l I I Browns Ferry Uni t 3 I N 9

TEXT (If more space 'is required, use additional NRC Form 366A's) (17)

D. t None.

E. th This event was immediately known to the control room operator upon receiving indication of an isolation of the Unit 3 reactor and refuel zones.

Operations personnel verified the Unit 3 reactor and refuel 'floor isolations had occurred and dispatched personnel to the Unit 3 Auxiliary Instrument Room to investigate the event.

G t t Failure of the Unit 3, Logic Channel A, Primary Containment Atmospheric Control Valve relay coil resulted in a partial Unit 3 Group 6 PCIS actuation. The PCIS actuations included isolation of the Unit 3 Reactor building and the refuel floor, and actuation of the B and C trains of the SBGT system and the B train of the CREV system.

III. CAUSE OF THE EVENT A t The immediate cause of this event was the random failure of a GE type CR-120 relay coil.

B- RII~~aum-The root cause of this event has been attributed to an end-of-life failure caused by the thermal aging of a GE type CR-120 relay coils which resulted in a partial Unit 3 Group 6 PCIS actuation. Industry data indicated that the service life for GE, type CR-120 relay coils in normally energized applications is approximately 15-20 years. The BFN relay coils in this application are now approaching an average service life of approximately 15 years.

C. t t None.

NRC Form 366(6-89)

jgi i5 NRC Form 366A U.S. NUCLEAR REGULATORY COHHISSION Approved OHB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAHE (,1) IOOCKET NUHBER (2) N 8 I / SEQUENTIAL / / REVISION I Browns Ferry Uni t 3 I I I I I TEXT (If more space is required, use additional NRC Form 366A's) (17)

IV ANALYSIS OF THE EVENT The PCIS isolates various systems related to the primary containment when accident conditions are sensed to limit inventory loss from the reactor vessel and to prevent the release of radioactive materials in excess of specified limits.

The PCIS logic is designed such that actuations/isolations occur on a 'loss of logic power. The failure of the relay coil resulted in a loss of logic power and plant systems responded as expected and were placed in their safe configurations.

All safety related plant components responded as expected during this event. The safety of the plant, its personnel', and the public was not compromised.

V CORRECTIVE 'ACTIONS t v Immediate corrective actions included the replacement of the failed relay coil. In addition, the PCIS signal was reset and the affected plant equipment was realigned.

B'. t v t t Additional corrective actions include replacing the GE CR-120 relay coils used in normally energized, safety related applications in Units 1 and 3 prior to the restart of each respective unit, and in Unit 2 prior to startup following the Cycle 6 refueling outage.

In addition, BFN has evaluated the affected relays in Unit 2 to determine those relays whose failure have a potential for resulting in a Unit 2 plant shutdown. This evaluation showed that twelve relays associated with isolation of the main steam tunnel cooling system met this criteria. At this time, six of the twelve, relay coils have been replaced. The remaining relays will be replaced prior to March 30, 1992.

The corrective actions discussed above were previously committed to by TVA in LERs 260/91001, 260/91005, and 260/91016. No additional commitments are being made in this LER.

NRC Form 366(6-89)

1 iO ll

NRC Form 366A U.S. LEAR REGULATORY COMMISSION Approved OMB No. 3150-0104 (6-09) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) iDOCKET NUMBER (2)

I /SEQUENTIAL / /REVISION/

Browns Ferry Unit 3 I Y I I I I TEXT (If more space is required, use additional NRC Form 366A's) (17)

VI ADDITIONAL INFORMATION None.

B.

Several previous LER events have occurred due to a failure of GE type CR-120 relays. These events include the following LERs: 259/85011, 259/85024, 260/86013, 296/87006, 260/91001, 260/91005, and 260/91016.

As discussed above, LER 260/91001, 260/91005, and 260/91016 committed to replace the normally energized, safety-related relay coils in Units 1 and 3 prior to the restart of each respective unit, and in Unit 2 prior to startup following the Cycle 6 refueling outage. In addition,, relay coils in applications which have a high potential for causing a Unit 2 plant shutdown were committed to be replaced by March 30, 1992.

VII. COMMITMENTS No additional commitments are being made in this LER.

Energy Industry Identification System (EIIS) codes are identified in the text as [XX].

NRC Form 366(6-89)

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