ML18038B497

LER 95-004-00:on 951007,unplanned ESF Actuation Occurred Following Transfer of 480 Volt Shutdown Board 3A to Alternate Supply.Caused by Personnel Error.Rps Restored & Sys Returned to normal.W/951102 Ltr

ML18038B497
Person / Time
Site:	Browns Ferry
Issue date:	11/02/1995
From:	Machon R, Wetzel S TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-95-004-03, LER-95-4-3, NUDOCS 9511060280
Download: ML18038B497 (14)

Text

PRIORITY 3.

tACCELERATED RZDS PROCESSZNS)

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9511060280 DOC.'DATE: 95/11/02 NOTARIZED: NO g FACIL:50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296. p AUTH. NAME WETZEL,S.A.

MACHON', R.'D RECIP.NAME AUTHOR Tennessee Tennessee RECIPIENT AFFILIATION'OCKET AFFILIATION Valley Authority Valley Authority

SUBJECT:

LER 95-004-00:on 951007,unplanned ESF actuation occurred following transfer of 480 volt shutdown board 3A to 0

. alternate supply. Caused by, personnel error.RPS restored sys returned to normal.W/951102 DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR TITLE: 50.73/50.9 Licensee Event Report (LER),

NOTES ltr.

! ENCL j SIZE:

Incident Rpt, etc.

I&

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-3-PD 1 1 WILLIAMS,J- 1 1 INTERNAL: ACRS 1 1 AEOD ', B 2 2

,AEOD/SPD/RRAB 1 1 CENTE 1 1 NRR/DE/ECGB 1 1 NRR/DE/EELB 1 1 NRR/DE/EMEB 1, 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 D NRR/DSSA/SPLB 1 1 NRR/DSSA/SPSB/B 1 1 NRR/DSSA/SRXB 1 1 ~ RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: L ST LOBBY 1 1 LITCO BRYCE,J H 2 2 1, NOACPOOREEW 1 1 WARD'OAC MURPHY,G.A 1 1 NRC PDR 1 NUDOCS FULL TXT 1 1 N

NOTE TO ALL "RIDS" RECZPIENTS:

PLEASE HELP US TO 'REDUCE WASTE! CONTACT THE DOCUMENT CONTROL

'DESK, ROOM OWFN 5DS (415-2083) TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR, DOCUMENTS YOU DONiT NEED FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

ik a Tennessee Valley Authonty, Post ONice Box 2000. Decatu'.. Alabama 35609.2000 R. D. (Rick) Machon Veo President; Browns Ferry Nuclear Plant November 2, 1995

'U.S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Washington, .D.C. 20555

Dear .Sir:

BROWNS PERRY NUCLEAR PLANT',{BFN) - UNITS 1 2 AND 3 DOCKET NOS ~ 50 259~ 50 260'ND 50 296 FACILITY OPERATING'ICENSE DPR-33~ 52~ AND 68 -,LICENSEE .EVENT REPORT 50-296/95004 The enclosed report provides details concerning an unplanned Engineered Safety Feature (ESF) actuation that occurred following transfer 'of 480V Shutdown Board 3A to its alternate supply. Thi.'s report is submitted in accordance with 10 CFR 50.'73(a)(2)'(iv) as an event or .condition that resulted in an automatic actuation of an ESF.

Sincerely,,

.R. D. M hon Enclosure cc: See page 2 v <ggaC~xq

'st511060280 'st511'02 PDR ADOCK 050002tt6 S PDR

U.S. Nuclear Regulatory Commission, Page 2 November 2, 1995 Enclosure cc (Enclosure):

INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339.

Paul Krippner American Nuclear Insurers Town Center, Suite 300S 29 South Main Street West Hartford, Connecticut 06107 NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw, Road Athens, Alabama. 35611 Regional Administrator U.S. Nuclear Regulatory Commission Region 101 II Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. J. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland'0852

I Il

NRC FORH 366 U.S." INCLEAR REGULATORY CNSII SS IOH APPROVED BY (Ã8 NO 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COMPLY MITH THIS INFORHATIOH COLLECTIOM REQUEST: 50.0 HRS ~

LZC~~ SEE EVENT REPORT (LER) FORNARD COHHENTS REGARDING BURDEN ESTIHATE TO THE INFORHATIOH AND RECORDS HANAGEHENT BRANCH (HNBB,7714)', U;S. NUCLEAR REGULATORY COHHISSIOM, (See reverse for required number of digits/characters for each block) MASHINGTOM, DC 20555-0001 AND TO THE PAPERIJORK REDUCTION PROJECT (3110-0104), OFFICE OF MANAGEMENT AND BUDGET MASMIMGTON DC 20503.

FACILITY Nba (1) DOCKET ILNSER (2) PAGE (3)

Browne Ferr Nuclear Plant BFN Unit 3 05000296 1 OF 4 TITLE (4)Unplanned Engineered Safety Feature (ESF) Actuation Following Transfer of 480V Shutdown Board 3A To its Alternate Supply EVENT DATE 5 LER NINKER 6 REP(NIT DATE 7 OTHER FACILITIES INVOLVED 8 SEQUENTIAL REVISION FACILITY NAHE N/A DOCKET NUMBER MONTH 'DAY YEAR YEAR MONTH DAY TEAR NUHBER MUHBER FACILITY NAHE N/A DOCKET NUHBER 10 07 95 95 004 00 11 02

%%RATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CF R  : Check one or mar e 11 INX)E (9) N 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b)

PQKR 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c) 000 50.36(c)(2) 50.73(a)(2)(vii) 'THER LEVEL (10) 20.405(a)(1)(ii) 20.405(a)(1)(iii) 50.73(a)(2)(i)(B) 50.73(a)(2)(viii)(A) (Specify in 20.405(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) Abstractand in Text, bolos 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) NRC Form 366A LICENSEE CONTACT FOR THIS LER 12 NAME TELEPHONE NUMBER (Include Area Code)

Stewart A. Wetzel, Acting Compliance Manager (205) 729-7556 lXNPLETE ONE LINE FOR EACH CQ0%NENT FAILURE DESCRIBED IN THIS REP(NIT 13 REPORTABLE REPORTABLE CAUSE SYSTEH COMPONENT HANUFACTURER CAUSE SYSTEH COHPONENT MANUFACTURER TO NPRDS TO NPRDS I+p'ji SUPPLEMENTAL REP(NIT EXPECTED 14 EXPECTED HONTH DAY YEAR YES SUBHI SS I(NI (lf yes, carptete EXPECTED SUBHISSIOH DATE).

X NO DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typeNritten Lines) (16)

On October 7, 1995, at 1217 hours0.0141 days <br />0.338 hours <br />0.00201 weeks <br />4.630685e-4 months <br /> during diesel generator (DG) testing, an operator received an undervoltage/transfer alarm on 480V Shutdown Board 3A. Subsequently, the operator transferred power for the board from its normal supply to its alternate supply (4kV Shutdown Board 3EB). However, the alternate supply had experienced a loss of voltage due to a DG output breaker trip. This loss of power to the 480V Shutdown Board Protection System Bus 3A to de-energize resulting in a half scram. This initiated caused'eactor other ESFs, including the standby gas treatment system, control'oom emergency ventilation system, and primary containment isolation. At the time of this event, Unit 3 was shutdown and defueled. Unit 2 was operating at 100 percent power and Unit 1 was shutdown and in a long-term outage. The root cause of this event was personnel error. In accordance with procedural requirements, the operator should have verified power was lost prior to transferring power. Appropriate personnel corrective actions have been taken with the operator. In addition, appropriate operations personnel have been sensitized to the need to verify indications before transferring the board. This report is submitted in accordance with 10 CFR 50.73(a)(2)(iv) as an event or condition that resulted in automatic actuation of an ESF.

HRC FORH ( )

NRC F(mN 366A U.S WCLEAR REGULATORY CQNIISSION APPROVED SY (NNI NO 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPOHSE TO COHPLY MITH THIS INFORHATIOH COLLECTION REQUEST 50.0 HRS. FORMARD COHHENTS REGARDIHG BURDEN ESTIHATE TO THE INFORNATIOH AND RECORDS HANAGEHEHT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY CONHISSIOH ~

LICENSEE EVENT REPORT MASHINGTOH, DC 20555-0001, AND TO THE PAPERMORK REDUCTION TEXT CONTINUATZON PROJECT (3150-0104), OFFICE OF IIANAGENEHT AND BUDGET,

'MASHINGTOH DC 20503 FACILITY SL% (1) DOCKET IRNmER (2) LER NLNBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION NUHBER2 2 Browns Ferry Unit 3 05000296 95 NUHBER'04 00 2 of 4 TEXT If more s ce is r ired use additional co ies of NRC Form 366A (17)

PLANT CONDZTZONS At the time this event occurred, Unit 3 and Unit 1 were shutdown and defueled. Unit 2 was operating at 100 percent power.

II ~ DESCRIPTION OP EVENT Ao Events On October 7, 1995, at approximately 1217 hours0.0141 days <br />0.338 hours <br />0.00201 weeks <br />4.630685e-4 months <br /> Central Daylight Time (CDT), the diesel generator (DG) output breaker unexpectedly tripped during DG testing. This caused the undervoltage/transfer alarm for 480V Shutdown Board 3A to alarm and deenergized 4kV Shutdown Board 3EB. Subsecpxently, an operator (utility, licensed) transferred power for 480V Shutdown Board 3A from its normal supply to its alternate supply (4kV Shutdown Board 3EB). However, the alternate supply a loss of voltage due to the DG output breaker trip. had'xperienced This loss of power to the 480V Shutdown Board caused Reactor Protection System (RPS) [JCJ] Bus 3A to de-energize resulting in a half scram.. This also resulted in primary containment isolation [JM) system groups 2, 3, 6, and 8 isolations, and standby gas treatment system [BH] and control room emergency ventilation system [VZ) actuations.

At 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> CDT, the RPS was restored and systems were returned ko normal status. This event is reportable in accordance with 10 CFR 50.73 (a)(2)(iv) as an event or condition that resulted in an unplanned actuation of an engineered safety feature (ESF).

Bo Ino erable Structures Com nents or S stems that Contributed to the Events None.

Co Dates and A roximate Times of Ma'or Occurrences!

October 7, 1995 at 1217 hours0.0141 days <br />0.338 hours <br />0.00201 weeks <br />4.630685e-4 months <br /> CDT Power to Shutdown Board 3A transferred from normal supply to alternate supply at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> CDT RPS restored and systems returned to normal D~ Other S stems or Seconda Functions Affecteds None.

0 MRC F(RÃ 366A U.S. WCLEAR REGULATORY CQBIISS ION APPROVED BY (MS NO- 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY IIITH THIS INFORHATION COLLECTION REQUEST: 50.0 HRS. FORIIARD COHHENTS REGARDING BURDEN EST IHATE TO THE INFORHAT ION AND RECORDS HAMAGEHENT BRANCH (HNBB 7714), U.S. KUCLEAR REGULATORY COHHISSIOM, LICENSEE EVENT REPORT MASHINGTON, DC 20555-0001, AND~ TO THE PAPERlJORK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF HANAGEHENT AMD BUDGET, KASHIKGTON DC 20503 FACILITY Kh% (1) DOCKET MISER (2) LER M lSER (6) PAGE (3)

YEAR SEQUENTIAL REVI SI OK MUHBER3 3 'KUHBER Browns Ferry Unit 3 05000296 95 004 00 3 of 4 TEXT I f more s ce is r I ed use eddi ionei co ies of MRC Form 366A (17)

ED Method of Discove I This condition was discovered when the Unit Operator received the half scram on RPS Bus 3A, which initiated the ESFa.

Po erator ActionsI The RPS was restored and systems were returned to normal.

Go Safet 8 stem Res nsess Safety systems responded as designed for this type of event.

ZZZ ~ CAUSE OF THE EVENT A. Immediate Causei The immediate cause of this event was transferring power for 480V Shutdown Board '3A from an energized source to a deenergized source.

BE Root Causes The root cause of this event was personnel error. In accordance with procedural requirements, the operator should have verified the electrical board was in fact deenergized and then verify that power was available on the alternate supply prior to transferring power.

IV+ ANALYSIS OP THE EVENT The systems affected during this event are designed to shut down the reactor, contain and process any radioactive releases, and to fulfill their safety functions upon loss of initiation logic power. The systems responded correctly to the loss of power; therefore, plant safety was not adversely affected'he plant's safe shutdown capabilities would not have been diminished had the unit been in power operation. Accordingly, this event did not affect the health and safety of plant personnel or the public.

Ve CORRECTIVE ACTIONS A. Immediate Corrective Actionsi The RPS was restored and systems were returned to normal.

0 NRC F(RN 366A U.S. WCLEAR REGIRATORY C(MMIISSION APPROVED BY (MMI MO 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY MITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORMARD COMMENTS REGARDING BURDEN EST IKATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (KNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, LICENSEE EVENT, REPORT llASH INGTON, DC 20555-000'I, AND TO THE PAPERIJORK REDUCT IOM TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF KAMAGEKENT AND BUDGET, NASHINGTON DC 20503 FACILITY NJUK (1) DocKET IRNmER (2) LER NINBER (6) PAGE (3)

SEQUENTIAL REVISION NUKBER4 4 NUMBER Browne Ferry Unit 3 05000296 95 004 00 4of4 TEXT If more s ce is r ired use additional co ies of NRC Form 3 66A (17)

B. Corrective Actions to Prevent Recurrencec Appropriate personnel corrective actions have been taken with the operator. In addition, appropriate operations personnel have been sensitized to the need to.assess plant conditions through multiple indications prior to responding to an event.

Additionally, during the upcoming cycle of licensed operator training (the cycle following annual exams), TVA plans to review this event with the operators and emphasize proper transfer of the shutdown boards.'Z

~ ADDITIONAL ZNFORNATZON A. Failed Com nentsI None.

evious LE a n Similar EventsI There have been several LERs written to document unplanned ESFs caused by 'the transfer of power from 480V Shutdown Boards to their alternate source of power (LERs 260/85009, 260/88008, and 296/90002). Each instance was a non<<transient transfer performed locally at the shutdown board to support maintenance or recovery from maintenance. None of these transfers were performed in the control room. In each of the LERs, the operator failed to verify the voltage supply to the alternate source before transferring power. The corrective actions to prevent recurrence involved counseling the operators on the proper transfer of power to shutdown boards, and stressing the need for attention to detail.

VZI. COMMITMENTS None.

This ls not a regulatory commitment.

Energy Industry Identification System (EIIS) system and component codes are identified in the text with brackets (e.g., [XX)).

il 7 l