ML18036A267

LER 91-009-01:on 910412,outboard MSIVs Closed During Performance of Surveillnace Instruction.Caused by Personnel Error & Design of Containment Isolation Sys.Design Change Implemented to Monitor MSIVs continuously.W/910626 Ltr

ML18036A267
Person / Time
Site:	Browns Ferry
Issue date:	06/26/1991
From:	Morrison G, Zeringue O TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-009, LER-91-9, NUDOCS 9107020359
Download: ML18036A267 (14)

Text

ACCELERATED DISTRIBUTION DEMONS~TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9107020359 DOC.DATE: 91/06/26 NOTARIZED: NO DOCKET FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 AUTH. NAME AUTHOR AFFILIATION MORRISON,G.M. Tennessee Valley Authority ZERINGUE,O.J. Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION R

SUBJECT:

LER 91-009-01:on 910412,outboard MSIVs closed during performance of surveillnace instruction. Caused by personnel D error & design of containment isolation sys.Design change implemented to monitor MSIVs continuously.W/910626 ltr.

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

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

NOTES:

RECIPIENT COPIES RECIPIENT COPIES D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL KREBS,M. 1 1 HEBDON,F 1 1 D ROSS,T. 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1

.AEOD/ROAB/DSP 2 2 NRR/DET/ECMB 9H 1 1 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 NRR/DST/SRXB 8E RES/DSIR/EIB 1

1 1

1 1

1 RGN2 NR~RJMQTSKB3.D1 REG-ELLE ~0~2 FILE 01 1

1 1

1 1

1 EXTERNAL: EG&G BRYCE,J.H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHYFG A 1 1 NSIC POOREFW 1 1 NUDOCS FULL TXT 1 1 D

D NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION 33 REQUIRED'OTAL NUMBER OF COPIES REQUIRED: LTTR 33 ENCL

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Tennessee Vat!ey Autnoray, post Office Box 2000. Decatur, Alabama 35609 O. J. 'Ike'eringue Vice President. Browns Ferry Operations JUN S6 8>>

U'.S. Nuclear .Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

'2 DOCKET NO. 50-260 TVA .BROWNS FERRY NUCLEAR PLANT (BFN) UNIT FACILITY OPERATING LICENSE DPR-52 REPORTABLE OCCURRENCE REPORT BFRO-50-260/91009, .SUPPLENENT 1 The, enclosed supplemental report provides details concerning a main steam isolation valve closure during surveillance testing. This report is submitted in accordance with 10 CFR 50.73(a')(2)(iv).

Very truly yours, TENNESSEE VALLEY AUTHORITY J., eringue Enclosure cc: see page 2 On59 9o5f 1 062+

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ik U.S. Nuclear Regulatory Commission JUN 2 6 1991 cc (Enclosure):

INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 NRC Resident Inspector, BFN Regional Administration U.S., Nuclear Regulatory Commission Office of Inspection and Enforcement 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, Maryland 20852

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NRC Form 366 U.S. EAR REGULATORY COHHISSION Approved OHB No. 3150-0104 (6-09) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

FACILITY NAHE (1) iDOCKET NUHBER (2) w Frr i TITLE (4) Inadvertent Hain Steam Isolation Valve Closure During Surveillance Testing V NT DAY N H R P T 0 VE I I I I I SEQUENTIAL I I REVI SION I I I I FACILITY NAHES IDOCKET NUHBER(S)

AY Y Y AR 2 6 l9 I I I I I I I I I I O 6 1

OPERATING iTHIS REPORT IS SUBHITTED PURSUANT TO THE REgUIREHENTS OF 10 CFR g:

HODE I I r I20.402(b) IZ0.405(c) Iz l50.73(a)(2)(iv) 173.71(b)

POMER I (20.405(a)( 1)(i ) F50.36(c)(1) F50.73(a)(2)(v) l73 71(c)

LEVEL I )20.405(a)( 1)(ii) i50.36(c)(2) )50.73(a)(2)(vii) )OTHER (Specify in 1 (20.405(a)( l)(iii) I I50 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) ( Text, NRC Form 366A)

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) AREA CODE IREPORTABLEI I I I IREPORTABLEI I I I A YTH P ANFAT T I I I I I I I I PP HENTA P T E P 4 FILM I SUBHISS ION I I I Y f m 1 P T T ABSTRACT (Limit to 1400 spaces, i.e., approximately fifteen single-space typewritten lines) (16)

On April 12, 1991, at 0034 hours3.935185e-4 days <br />0.00944 hours <br />5.621693e-5 weeks <br />1.2937e-5 months <br />, the outboard main steam isolation valves (MSIVs) closed during the performance of a Surveillance Instruction (SI). Prior to the beginning of the surveillance test a relay associated with the MSIV isolation logic had been removed and was scheduled for replacement. The removal of the relay placed the MSIVs in a 1-out-of-2 isolation signal condition. In accordance with the SI, a reactor vessel water level transmitter was isolated at the manifold, and the transmitter high side began to depressurize through valve packing leaks. This simulated a low-low-low reactor water level signal which completed the isolation logic to close the outboard MSIVs.

The root cause of this event was personnel error. The personnel involved with the evaluation of the impact of the missing relay failed to adequately assess its effect on the MSIV isolation logic.

Immediate corrective actions were taken to terminate the surveillance test and to return the reactor water level transmitter to service. Licensed Operations personnel, Maintenance foremen, Maintenance planners, and .System Engineering personnel will be required to review this event. A design change will be implemented to provide a means to monitor MSIV pilot solenoid circuit continuity.

NRC Form 366(6-89)

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NRC Form 366A U. S. AR REGULATORY COMMISSION Approved OMB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

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

I I i SEQUENTIAL 'i i REVISION /

I Y I I I I Br w rr TEXT (If more space is required, use additional NRC Form 366A's) ( 17)

On April 12, 1991 at 0034 hours3.935185e-4 days <br />0.00944 hours <br />5.621693e-5 weeks <br />1.2937e-5 months <br />, an unplanned Engineered Safety Feature (ESF) actuation occurred when the outboard .main steam isolation valves (MSIVs) closed during the performance of a surveillance test. The isolation logic for each MSIV has an AC and a DC pilot solenoid valve which must be de-energized to complete the logic to close the valve. Two independent events combined to complete the isolation logic. The first was the removal of a MSIV logic relay for replacement. This resulted in the loss of power to the MSIV DC pilot solenoids, and hence a half isolation signal. The second event occurred when a reactor vessel water level transmitter was isolated during the performance of a surveillance test. The high side of the transmitter depressurized through packing leaks simulating a low-low-low reactor vessel water level. This condition de-energized the AC pilot solenoids and completed the isolation logic to close the outboard MSIVs.

Prior to the beginning of the surveillance test, a MSIV isolation logic relay had been removed and was scheduled for replacement. A clearance established for the repair of this relay had required the removal of several control power fuses. To support an unrelated hydrostatic test, it was decided to restore the MSIV position indicating lights which had been removed from service when the clearance for the replacement of the relay was implemented. The clearance was lifted, and the fuses were replaced. The effect of the missing relay was to de-energize the DC pilot solenoid circuit. With the DC pilot solenoids de-energized only the AC pilot solenoids remained to maintain the MSIVs in an open position. Although the initial impact evaluation associated with the clearance for the relay replacement recognized that the DC power to the outboard MSIVs would, be de-energized, the personnel involved with the evaluation of the lifting of the clearance and the replacement of the fuses failed to adequately consider the effect of the missing relay.

Subsequently, during the performance of a surveillance test a reactor vessel water level transmitter was removed from service by isolating its high and low sides at the manifold and opening the equalizing valve across the transmitter.

When the transmitter was isolated, valve packing leaks allowed the high side to depressurize simulating a drop in vessel water level. When this low-low-low reactor water level signal was introduced into the train B outboard MSIV logic, the AC pilot solenoids were de-energized. The loss of the AC solenoids with the DC solenoids already de-energized resulted in the completion of the isolation logic and closure of the outboard MSIVs.

Unit 2 was in cold shutdown condition. Units 1 and 3 were shutdown and defueled at the time of this event. No fuel handling or operations over spent fuel were in progress during this event. Actuations of the ESF systems are reportable in accordance with 10 CFR 59.73(a)(2)(iv).

NRC Form 366(6-89)

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

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

I I I I SEQUENTIAL I IREVISIONI I I I I I I I I I Br w TEXT (If more space is required, use additional NRC Form 366A's) (17)

The root cause of this event was personnel error. The personnel involved with the evaluation of the fuse replacement along with the personnel responsible for lifting the clearance failed to adequately assess the impact of the missing relay on the MSIV isolation logic.

Contributing to the cause of this event is the design of the containment isolation system which failed to indicate the presence of the one-out-of-two isolation signal to Operations personnel.

L E T Plant systems and components responded as designed for the conditions present at the time of this 'event.

There were no safety consequences as a result of this event. The outboard MSIVs were not operable or required for plant safety at the time of the event.

RE The administrative control program for performing wirelifts was reviewed to ensure that these controls are sufficient. This review revealed that the existing controls adequately address the issue.

Licensed Operations personnel, Maintenance foremen, Maintenance planners, and System Engineering personnel will be required to review this event to stress the importance of considering related aspects of temporary configurations when evaluating work activities for impact on plant equipment. This review will be completed by August 23, 1991.

A design change will be implemented to provide a means to monitor MSIV pilot solenoid circuit continuity. This design change will be completed prior to Unit 2, cycle 7 operation.

Several events (259/88030, 259/88042, 259/90015, 260/88005, and 260/88010) involving unplanned ESF actuations have occurred which were caused by improper review of work activities. In December 1988, TVA implemented a program requiring a formal documented evaluation of the impact of work activities on plant equipment. Since that time, only one event (259/90015) has occuxred which was caused by the performance of an inadequate impact evaluation.

NRC Form 366(6-89)

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NRC 'Form 3 A U.S. AR REGULATORY CONHISSION Approved ONB No. 3150-0104.

(6-89) Expires 4/30/92 LICENSEE'EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NANE (1) IOOCKET NUNBER (2) 8 I I I, I SEQUENTIAL I I REVISIONI I I I I

'I I I I I 8 w TEXT (If more space is required, use additional NRC Form 366A's). (17)

Licensed Operations personnel, Maintenance foremen, Maintenance planners, and System Engineering personnel will review this event by August 23, 1991.

A design change will be implemented to provide a means to monitor MSIV pilot solenoid circuit continuity. This design change will be completed~ prior to Unit 2, cycle 7 operation.

Energy Industry Identification System (EIIS) codes are identified in the text as

[xx].

NRC Form 366(6-89)

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