ML18036A666

LER 92-002-00:on 920324,ESF Actuation Occurred Resulting from Random Relay Failure.Caused by Unexpected Radom Failure of GE CR-120 Relay.Failed Relay Replaced & Plant Sys Returned to Normal configuration.W/920422 Ltr

ML18036A666
Person / Time
Site:	Browns Ferry
Issue date:	04/22/1992
From:	Ridgell E, Zeringue O TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-002-03, LER-92-2-3, NUDOCS 9204280408
Download: ML18036A666 (14)

Text

ACCELERATED DIUBUTION DEMONSTRATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9204280408 DOC.DATE: 92/04/22 NOTARIZED: NO DOCKET 4 FACIL: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 92-002-00:on 920324,ESF actuation occurred resultinq from random relay failure. Caused by unexpected radom fax.lure of GE CR-120 relay. Failed relay replaced & plant sys returned to normal configuration.W/920422 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVEDI LTR 3 ENCL TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

( SIZE: &

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME =

LTTR ENCL SANDERS,M. 1 1 HEBDON,F 1 1 WILLIAMS,J. 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1' AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB8H3 1 1 DST/ LB8D1 1 1 NRR/DST/SRXB 8E 1 1 EG 02 1 1 RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL EG&G BRYCE E J ~ H 3 3 L ST LOBBY WARD 1 1 NRC PDR , 1 1 I NS C MURPHY E G ~ A 1 1 NSIC POORE,W. 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE iVASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 32 ENCL 32

4k 4l Tennessee Valley Authority, Post Otfice Box 2000. Deca!ur.'Alabama 35609 APR 22 1992 O. J. 'Ike Zeringue Vice President. Browns Ferry Operations U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

TVA BROWNS FERRY NUCLEAR PLANT (BFN) UNIT 2 DOCKET NO. 50-296 FACILITY OPERATING LICENSE DPR-68 LICENSEE EVENT REPORT LER-50-296/92002 The enclosed report provides detai.ls concerning an engineered safety features actuation resulting from a random relay failure. This report is submitted in accordance with 10 CFR 50.73(a)(2)(iv).

Sincerely,

>u' i J. Zering Enclosure cc: 'see page 2

'tt204280408 920422 PDR ADOCK 05000296 S PDR gE-22 I/r

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U.S. Nuclear Regulatory Commission APR 2'2 892 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, P.O. 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 U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Mary'land 20852

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NRC Form 366 U... LEAR REGULATORY COWISSION Approved OHB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT. (LER)

FACILITY NAHE (1) IDOCKET NUHBER (2) I w F TITLE (4) 1 F V T

( SE()UENZIAL J I REVISION[ I IDOCKET NUHBER(S)

I I I I I I I I I I I 42 29 2 OPERATING )THIS REPORT IS SUBHITTED PURSUANT TO THE RE()UIREHENTS OF 10 CFR g:

HODE ) k r 1'i 1

)20.402(b) i20.405(c) ])( [50.73(a)(2)(iv) i73.71(b)

POHER I )20.405(a)( 1)(i) I I50 36(c)(1) I I50.73(a)(2)(v) ]73.71(c)

LEVEL ] (20.405(a)( l)(ii) i50.36(c)(2) ]50.73(a)(2)(vii) [OTHER (Specify in

[20.405(a)( l)(iii) [50.73(a)(2)(i)'50.73(a)(2)(ii)

(50.73(a)(2)(viii)(A) Abstract below and in

)20.405(a)( 1)(iv) )50.73(a)(2)(viii)(B) Text, NRC Form 366A)

.4 v N F TH R 1 NAHE T N t AREA CODE 1H. i P N F H HPN TF R 0 BD NT I I IREPORTABLEI I I I I iREPORTABLE/

A Y T T NPRD HP N NT HAN F T T 0 I I I I I I I I I I I I I I PP T RP TD 14 I EXPECTED I NT AY Y I I SUBHISSION I I I m 1 XP 0 N ABSTRACT (L'imit to 1400 spaces, i.e., approximately fifteen single-space typewritten lines) (16)

On March 24, 1992, at 0222 CST, an unexpected engineered safety features (ESF) actuation occurred resulting in a partial Unit 3, Group 6, actuation of the primary containment isolation system (PCIS).

The root cause of this event was an unexpected,- random failure of a General Electric CR-120 relay. During this event, the relay began 'chattering'hi:ch resulted in the PCIS actuations. Investigations were unable to determine the specific failure mechanism which resulted in the relay chatter.

The failed relay was replaced and the plant systems were returned to their normal configuration. In addition, TVA's investigations into this failure included examination of the relay and of plant activities during the time of this event.

These investigations were unable to determine the precise cause of the relay failure. Therefore, no further corrective actions are planned.

NRC Form 366(6-89)

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r 'NRC Form 366A U.S. . CLEAR 'REGULATORY CONNISSION Approved ONB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

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

I' I I i SEqUENTIAL f J REVISION( I 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 100 percent power operations and Units 1 and 3 were shutdown and defueled.

II. DESCRIPTION OF EVENT A. J~ILt:

On March 24, 1992, at 0222 CST, an unexpected engineered safety features (ESF) actuation occurred resulting in a partial Unit 3, Group 6, actuation of the primary containment isolation system (PCIS) [JM]. This event was a result of the unexpected, random failure of a General Electric (GE),

CR-120 relay.

In this event, the PCIS actuation resulted in isolation of the refuel zone ventilation system [VG], actuation of the B and C trains of the standby gas treatment system (SBGT) [BH], and. actuation of the B train of the control room emergency ventilation, system (CREV) [VI].

As a result of the PCIS actuation, TVA reports this event in accordance with 10 CFR 50.73(a)(2)('iv) as an event or condition that resulted in manual'r automatic actuation of any engineered safety feature.

B. t t th None.

C t f March 24, 1992 at 0222 CST Relay failure resulting in PCIS partial Group 6 actuation.

0543 CST TVA provided four-hour non-emergency report to NRC required'y 10 CFR 50.73(a)(2)(iv).

2225 CST Relay was replaced, the isolation signal was reset, and plant equipment was returned to its normal configuration.

D. th None.

NRC Form 366(6-89)

Oi i>

I

NRC Fora 366A U. S. LEAR REGULATORY COHHISSION Approved OHB No. 3150-0104 (6-89) Expires 4/30/92, LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) IDOCKET NUHBER (2)

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

E. t This event was immediately known to the control operator upon receiving indication of the PCIS actuation.

F.

Operations verified the PCIS actuation occurred as indicated.

G.

All expected PCIS actuations occurred as designed. These actuations included isolation of the refuel zone ventilation system, actuation of the B and C trains of the SBGT system, and actuation of the B train of the CREV system.

III- CAUSE OF THE EVENT The immediate cause of this event was a relay failure.

B- R~IILtMmme-The root cause of this event was an unexpected, random failure of a GE CR-120 relay.- During this event, the relay began 'chattering'hich resulted'n the PCIS actuations, previously discussed. Investigations were unabl'e to determine the specific failure mechanism which resulted in the relay chatter.

C. t t None.

IV. AMLYSIS OF THE EVENT The PCIS isolates various systems related to the primary containment when accident conditions are sensed. This isolation is designed to limit inventory loss from the reactor vessel and to prevent the release of radioactive materials in excess of'pecified limits.

The PCIS logic is designed such that actuations/isolations occur on loss of logic power. The failure of the relay resulted in a loss of logic power and the subsequent PCIS actuations.

NRC Form 366(6-89)

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ji

liRC Form 366A U.S. CLEAR REGULATORY CONHISSION Approved OHB No. 3160-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NANE (1) IDOCKET NUNBER (2) N B I iSEqUENTIAL [ iREVISIONt Browns Ferry Uni t 3 I A I I I I F

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

In this event, all safety-related plant components operate as expected following the PCIS actuation. The safety of the plant, its personnel, and the. public was not compromised.

V. CORRBCTIVE ACTIOÃS The failed relay was replaced and the plant systems were returned to their normal configuration. In addition, TVA's investigations into this failure inclu'ded examination of the relay and of plant activities during the time of this event. These investigations were unable to determine the precise cause of the relay failure. Therefore, no further corrective actions are planned.

B. tv t t P v t R None.

VI. ADDITIOML INFORMATION A.

GE Type CR-120 Relay.

B. v Several previous LER events have occurred due to 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, 260/91016, and 296/92001. In each of these previous events the failure mechanism involved a shorting of the relay coil due to end of life conditions.

The events discussed above are not similar to the present event since the relay coil did not fail. In fact, this relay coil was replaced in January 1992 and no degradation of the relay was noted at this time. As discussed previously, testing of the relay could not determined a failure mechanism for the present event.

VII. CORRI'JMENTS None.

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

NRC Form 366(6-89)

4i ii-