ML18038B334

LER 95-001-00:on 950615,under-voltage Condition Occurred on Shutdown Boards,Automatically Starting Edgs.Caused by Loss of Athens 161 Kv Line.Edgs Placed in Standby & Power Restored to buses.W/950711 Ltr

ML18038B334
Person / Time
Site:	Browns Ferry
Issue date:	07/11/1995
From:	Machon R, Jay Wallace TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-95-001-03, LER-95-1-3, NUDOCS 9507170024
Download: ML18038B334 (16)

Text

~ PRIORITY 1y tACCELERATED RIDS PROCESSING)

'REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9507170024 DOC.DATE: 95/07/11 NOTARIZED: NO DOCKET g FACIL:50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 E AUTH. NAME AUTHOR AFFILIATION WALLACE,J.E'. Tennessee Valley Authority MACHON,R.D. Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 95-001-00:on 950615,under-voltage condition occurred on shutdown boards, automatically starting EDGs.Caused by loss of Athens 161 kV line.EDGs placed in standby & power restored to buses.W/950711 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

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

NOTES 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 EOD~P-D/RA.B 2 2 AEOD/SPD/RRAB 1 1 LE CE R~ 1 1 NRR/DE/ECGB 1 1 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DIS P/PI PB 1 1 NRR/DOPS/OECB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 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 WARD 1 1 LITCO BRYCE,J H 2 2 NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN 5D8 (415-2083) TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T 'NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

Te;lessee /a'eq ~.."s", "-"s; ~" =e =".~ "-="", ew:.. ~"a-a "=o e 2 "CC R. D. iRick> Machon V e~.es "e" ~ "v "s=~/i "oa.-"a" July 11, 1995 U.S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

BROWNS FERRY NUCLEAR'LANT (BFN) - UNITS 1~,2I AND 3 - DOCKET NOS ~ 50 259~ 50 260I AND 50 296 FACILITY OPERATING LICENSE DPR-33I 52~ AND 68 LICENSEE EVENT REPORT 50-296/95001 The enclosed report provides details concerning an event on June 15, 1995, in which the Unit 3 A and B diesel generators auto-started as a result of an under-voltage condition. Thi.s was a direct result of an airplane severing the, Athens 161kV phase C transmission line.

This report is subm'itted in accordance with 10 CFR 50.73 (a)(2).(iv) as a condition that resulted in the automatic actuation of an engineered safety feature.

Sincerely, R. D. M on Site Vi e President Enclosure cc: See page 2 9507170024 9507i}

PDR ADQCK 05000296 8 PAR

U.S. Nuclear Regulatory Commission Page 2 July 11, 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 Route 12, Box 637 Athens, Alabama 35611 Regional Administrator U. S. Nuclear Regulatory Commission Region 1'01 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 20852

/

4I 0

U.S. Nuclear Regulatory Commission Page 3 July 11, 1995 PS SAW JEW:MTN Enclosure cc (Enclosure):

C. W. Beasley, PAB 1B-BFN P. P. Carier, BR 4G-C L. S. Clardy, CFC 1D-BFN C. T. Dexter, BFT 3A-BFN

0. D. Kingsley, LP 6A-C J. P. Maciejewski, LP 3B-C J. Scott Martin, PMC 1D-BFN T. J. McGrath, LP 3B-C M. 0. Medford, LP 3B-C G. D. Pierce, PEB 1B-BFN E. Preston, POB 2C-BFN C. M. Root, CFC 1D-BFN R. H. Shell, 0&PS 4C-SQN T. D. Shriver, PAB 1A-BFN H. L. Williams, EDB 1A-BFN

0. J. Zeringue, LP 3B-C RIMS, WT 3B-K a:Uers5500l.jew

l MRC FGRM 366 U.S NUCLEAR REGULATORY COMMISSION APPROVED BY CNB NO 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS IHFORMATIOH COLLECTION REQUEST: 50.0 HRS.

LZCENSEE EVENT REPORT (LER) FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH

<MMBB 7714), U.ST NUCLEAR REGULATORY for required nunber of digits/characters for each block) COMMISSION, WASHINGTON, DC 20555-0001 AHD TO (See reverse THE PAPERWORK REDUCTION PROJECT (3130-0104),

OFFICE OF MANAGEMENT AND BUDGET, WASHINGTOH, DC 20503.

FACILITY NAME (1) DOCKET NQ(BER (2) PAGE (3)

Browns Ferr Nuclear Plant BFN Unit 3 05000296 1 OF 4 TITLE (4) Loss of a 161Kv line caused the actuation of the Engineered Safety Feature (ESF) system.

EVENT DATE (5) LER MIMIBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED 8)

SEQUENTIAL REVISION FACILITY NAME HA DOCKET NUMBER MONTH DAY YEAR YEAR MONTH DAY YEAR NUMBER NUMBER FACILITY NAME NA DOCKET NUMBER 06 15 95 95 001 00 07 11 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO'THE REQUIREMENTS OF 10 CFR: (Check one or mor e 11 M(X)E (9) N 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b) 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

POWER 000 50.36(c)(2) 50.73(a)(2)(vii)

LEVEL (10) 20.405(a)(1)(ii) OTHER 20.405(a)(1)(iii) 50.73(a)(2)(i)(B) 50 '3(a)(2)(viii)(A) (Specify in 50.73(a)(2)(ii) 50.73(a)(2)(vlii)(B) Abstract below 20.405(a)(1)(iv) and in Text, 20.405<a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) NRC Form 366A LICENSEE COHTACT FOR THIS LER (12)

NAME TELEPHOHE NUMBER (Include Area Code)

James E. Wallace, Compliance Licensing Engineer (205)729-7874 C(NPLETE ONE LIME FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

REPORTABLE REPORTABLE CAUSE SYSTEM COMPONENT MAHUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TO HPRDS TO NPRDS SUPPLEMENTAL REPORT EXPECTED (14) MOM'IH DAY YEAR EXPECTED YES SUBMISSION

)( NO DATE (15)

(If yes, complete EXPECTED SUBMISSION DATE).

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

On June 15, 1995, at 1129 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.295845e-4 months <br />, the 3A and 3B Emergency Diesel Generators automatically started when an under-voltage condition occurred on the 3EA and 3EB 4kV shutdown boards.

This under-voltage condition caused the loss of the 3A reactor protection system further resulting in the auto-starts of the standby gas. treatment and control room emergency ventilation systems. At the time of this event, Unit 3 was defueled and inanda Unit long term Main Bank transformer outage. Unit 2 was operating at 100 percent power, 1 was shutdown and defueled. The event occurred when an airplane cut the Athens 16lkV phase C transmission line. Corrective actions were taken to restore the plant systems to standby readiness'o additional corrective actionsa will, be taken. This event is reportable in condition that resulted in an automatic accordance with 10 CFR 50.73 (a)(2)(iv) as actuation of the ESF system.

NRC FORM ( )

0 NRC FORll 366A U.S NUCLEAR REGULATORY CON(I SSI ON APPROVED BY (H(B MO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS ~ FORWARD COMMENTS REGARDIHG BURDEN ESTIMATE TO THE INFORMATION AHD RECORDS MANAGEMENT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION/

'LICENSEE EVENT REPORT WASHINGTON, DC 20555.0001, AND TO THE PAPERWORK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF HANAGEHEHT AND BUDGET, WASHINGTON DC 20503 FACILITY NAME (1) DOCKET NIH(BER (2) LER MWBER (6) , PAGE (3)

YEAR SEQUENT I AL REVISION NUMBER NUMBER Browns Ferry Unit 3 05000296 95 001 00 2 of 4 TEXT If more s ace is r uired use additionaI co ies of NRC Form 366A (17)

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

DESCRIPTION OF EVENT Event On June 15, 1995, at 1129 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.295845e-4 months <br />, Unit 3 experienced a loss of offsite power to common station service transformer A [EB),

which was being supplied by the Athens 161kV [FK) transmission line. This condition. occurred when an airplane severed the Athens 161kV phase C transmission line.

As designed, the start buses 1A and 2A transferred to an alternate power source (Trinity 161kV line), and attempted to reconnect to the Athens line. However, because the fault on the Athens line had not cleared, the alternate feeder breaker [BKR) was locked out resulting in an under-voltage condition on start buses 1A and 2A.

When the under-voltage condition occurred, the 3EA and 3EB 4kV shutdown boards [EB) de-energized. As a result, the 3A and 3B Emergency Diesel Generators (EDGs) [EK) started and tied to the 4kV shutdown boards. The 3A reactor protection system (RPS)

[JC) de-energized and caused the Unit 3 reactor zone ventilation

[VB] and refueling zone ventilation [VA] systems to isolate; and the standby gas treatment (SGT) system [BH), and control room emergency ventilation (CREV)'VZ) train A to initiate. The emergency equipment cooling water [BI] pumps started to supply cooling water to the EDGs. All systems responded as expected.

At 1207 hours0.014 days <br />0.335 hours <br />0.002 weeks <br />4.592635e-4 months <br />, start bus 1A was manually transferred .to an alternate power supply to re-energize the 4kV 3A unit board, which re-energized the 3EA and 3EB 4kV shutdown boards. At 1245 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.737225e-4 months <br />, Unit 3 EDGs were returned to standby readiness since the Trinity 16lkV transmission line,was supplying power to Unit 3.

At 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, SGT was secured, and at 1305 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.965525e-4 months <br />, CREV train A was secured.

This event is reportable in accordance with 10 CFR 50.73 (a)(2)(iv) as a condition that resulted in an automatic actuation of an ESF system.

B~ Ino erable Structures Com onents or S stems that Contributed to the Event:

None.

Ih NRC FORli 366A U.S. NUCLEAR REGULATORY CCHHISSION APPRMD BY NB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY llITH THIS INFORHATION COLLECT IOH REQUEST: 50.0 HRS ~ FORlJARD COMMENTS REGARDING BURDEN ESTIMATE TO tHE INFORMATION AND RECORDS MANAGEMENT BRANCK (HNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION/

LICENSEE EVENT REPORT llASNINGTON, DC 20555-0001, AND TO THE PAPERNORK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, IIASHINGTON DC 20503 FACILITY NAME (1) DOCKET NUMBER (2) LER NLIUIER (6) PAGE (3)

YEAR SEQUENTIAL REVISION NUMBER NUMBER Browns Ferry Unit 3 05000296 95 001 00 3 of 4 TEXT If more s ace is r uired use additionat co ies of NRC Form 366A (17)

C~ Dates and A roximate Times of Ma'or Occurrences:

June 15, 1995 at 1129 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.295845e-4 months <br /> CDT An airplane severed phase C of the Athens 161kV transmission line, EDGs started and tied to boards at 1207 hours0.014 days <br />0.335 hours <br />0.002 weeks <br />4.592635e-4 months <br /> CDT TVA manually transferred 1A start bus to its alternate power supply (Trinity 161kV) to re-energize the Unit 3 4kV 3A unit board at 1245 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.737225e-4 months <br /> CDT Unit 3 EDGs were returned to standby readiness at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> CDT SGT system secured at 1305 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.965525e-4 months <br /> CDT CREV train A secured at 1412 hours0.0163 days <br />0.392 hours <br />0.00233 weeks <br />5.37266e-4 months <br /> CDT TVA provided a 10 CFR 50.72(b)(2)(ii) notification to NRC Operations Center D~ Other S stems or Secondar Functions Affected:

None.

E. Method of Discover This condition was discovered when the control room Operations personnel [licensed, utility) received alarms and indicators that start buses 1A and 2A were de-energized and the EDGs had auto-started.

F. 0 erator Actions:

Operations personnel responded to the event in accordance with approved procedures. Start buses 1A and 2A were repowered when they were manually placed on, their alternate feeder breakers.

G. Safet S stem Res onsesl All safety systems responded as designed for this type of event.

CAUSE OF THE EVENT Immediate Cause:

The immediate cause of the event was the loss of the Athens 161kV line that created an under-voltage condition.

0 NRC FORM 366A U.S. NUCLEAR REGULATORY CQOIISSION APPROVED BY OMB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY IJITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORllARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS HANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, LICENSEE EVENT REPORT .WASHINGTON, DC 20555-0001, AND TO THE PAPERlQRK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, NASHINGTOH DC 20503 FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEOUENTIAL REVISION NUHBER NUMBER Browns Ferry Unit 3 05000296 95 001 00 4 of 4 TEXT If more s ce is r uired use additional co ies of NRC Form 366A (17)

B. Root Cause:

This event occurred when the Athens 161kV line was inadvertently severed by an airplane.

IV ~ ANALYSIS OF THE EVENT In this event, plant safety systems and associated components performed as designed. Operations personnel immediately identified the cause of the ESF actuation and took appropriate corrective actions to restore the plant systems to standby readiness. Therefore, this event did not affect the health and safety of plant personnel and the public.

Had Unit 3 been at full power operation providing power to the grid, these ESF actuations would not have occurred. Namely, at full power operation, Unit 3 is aligned to its Unit Station Transformer, and the Athens 161kV transmission line is not aligned to supply power to the 4kV shutdown boards.

V. CORRECTIVE ACTIONS A. Immediate Corrective Actions:

Operations personnel restored power to the 1A and 2A start buses and subsequently placed the EDGs in standby readiness. A problem evaluation report (BFPER 950725) was generated to document this event. Systems were returned to a standby readiness condition.

B. Corrective Actions to Prevent Recurrence:

None.

VI+ ADDITIONAL INFORMATION A~ Failed Com onents:

None.

B~ Previous LERs on Similar Events:

None.

VII. COMMITMENTS None.

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

'l