ML17228A444

LER 94-002-00:on 940113,inadvertent Load Shed of 1A3 4160 Volt Bus Occurred.Caused by Procedural Inadequacy. Electrical Maint Tested 2x-2 Relay & Proved Relay to Be Functioning Correctly at Time of testing.W/940208 Ltr

ML17228A444
Person / Time
Site:	Saint Lucie
Issue date:	02/08/1994
From:	Sager D, Williams J FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-94-032, L-94-32, LER-94-002, LER-94-2, NUDOCS 9402180076
Download: ML17228A444 (11)

Text

ACCELERATED DISTRIBUTION DEMONSTRATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9402180076 DOC.DATE: 94/02/08 NOTARIZED: NO DOCKET FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power & Light Co. 05000335 AUTH. NAME AUTHOR AFFILIATION WILLIAMS,J.R. Florida Power & Light Co.

SAGER,D.A. Florida Power & Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 94-002-00:on 940113,inadvertant load shed of 1A3 4160 volt bus occurred. Caused by procedural inadequacy. D Electrical maint tested 2x-2 relay & proved relay to be functioning correctly at time of testing.W/940208 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR 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 PD2-2 LA 1 1 PD2-2 PD 1 1 D NORRIS,J 1 1 INTERNAL: ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRIL/RPEB 1 1 NRR/DRSS/PRPB 2 2 yJ3SSjh./S PLB 1 1 NRR/DSSA/SRXB 1 1 REG FILE 02 1 1 RES/DSIR/EIB N2 "' ILE 01 1 1 1 1 EXTERNAL: EG&G BRYCE,J.H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POORE,W. 1 1 NUDOCS FULL TXT 1 1 D

A D

D NOTE TO ALL "RIDS" RECIPIENTS:

S 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 30 ENCL 30

P.. Box 128, Ft. Pierce, FL 34954.0128 February 8, 1994 L-94-032 10 CFR 50.73 U. S. Nuclear Regulatory Commission ~

Attn: Document Control Desk Washington, D. C. 20555 Re: St. Lucie Unit 1 Docket No. 50-335 Reportable Event: 94-002 Date of Event: January 13, 199'4 The attached Licensee. Event Report is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event."

Very truly yours, D. A. ger Vice sident St. Lucie Plant DAS/JNH/kw Attachment cc: Stewart D. Ebneter, Regional Administrator, USNRC Region II Senior Resident Inspector, USNRC, St. Lucie Plant DAS/PSL N1057-94 9402180076 94020S PDR ADOCK 05000335 S PDR an FPL Group company

l

~

FPL FOCTIITI'IO OI U.S. NUCLEAR REGULATORY COMMISSIO TII%EIIEOOINT NO TINITIIA NRC Fom',366 ENNIEC:IOCIIT

(&e3I EST AAATT0 IAATXN IEN IE TTONTE TO CCNNTT WITH TIAC NECICAATCNCCEITC IION 1 LICENS EVENT REPORT (LER) IECAECT: TOT ITES fCRIIAIOCOGNATIC IECAIINIOIAATTENECTNAATE TO TIE IECCIIC Afe IEICTITC NAIIACTANNI OIAIICNTNCNEIla IANAEANIEONATONE WAN NICIOI.OC T0$ 5L ITIC TO THE tATEIINCNNfECVCTETI TIEIE CT TTIICIIIOCIICE CE NANACEIENTAIOOOCET. TIANNICTOCOC TNCT FACILITYNAME (1) DOCKET NUMBER (2) PAGE 3 St. Lucie Unit 1

'TLE 050003351 0 4

( ) Inadvertant load shed of the 1A3 4160 volt bus due to procedural inadequacy.

EVENT DATE (5) LER NUMBER (6) REPORT DA IE (7) OTHER FACILITIES INVOLVED(8)

MONTH DAY YEAR YEAR S IAL DAY YEAR FACILITYNAMES DOCKET NUMBER(S)

N/A 0.1139494 0 0 2 0 0 0 2 0 8 9 4 N/A 05000 THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR:

OPERATING Check one or more of the followin (11)

MODE (9) 20.402(b) 20.405(c) X 50.73(a)(2)(iv) 73.71(b)

POWER LEVEL 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

(10) 1 0 0 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER (Specify in Abstract 20.405(a)(1 )(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) below and in Text 20.405(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) NRC Form 366A) 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER 12 NAME TELEP ONE NUMBER AREACODE James R. Williams, Shift Technical Advisor 4 0 7 4 6 5 - 3 5 5 0 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13 CAUSE SYSTEM COMPONENT MANUFAC- TURER REPORTABLE CAUSE SYSTEM COMPONENT MANUFAC- REPORTABLE TO NPRDS fURER TO NPRDS I I I SUPPLEMENTAL REPORT EXPECTED 14 EXPECTED MONTH DAY YEAR SUBMISSION YES (ffyes, complete EXPECTED SUBMISSION DATE) NO DATE (15)

ABSTRACT (Limit to f400 spaces.i.e. approximately fifteen single-space typewritten lines) (16)

On January 13,1994 Unit 1 was in mode 1 at 100% power. A surveillance test on the undetvoltage relays for the 1A3 safety related bus was being performed. When the utility non-licensed operator initiated the test for the 27-1 relay, therelaydidnotoperate. Per TechnicaISpecification3.3.2.1.,theinoperablerelaymustbe'placed in the trip position within one hour. At 0134 hours0.00155 days <br />0.0372 hours <br />2.215608e-4 weeks <br />5.0987e-5 months <br />, as per the surveillance procedure, the relay was placed in the trip position by utility maintenance personnel and an invalid undervoltage actuation signal was initiated. The safety related 1A3 4160 volt.bus load shed, the 1A Emergency Diesel Generator started and load sequenced onto the bus. The plant remained in a stable condition throughout the event. Normal off-site power was restored to the 1A3 bus and the 1A Emergency Diesel Generator was secured at 0225 hours0.0026 days <br />0.0625 hours <br />3.720238e-4 weeks <br />8.56125e-5 months <br />.

The root cause of the event was due to a procedural inadequacy in that the procedure did not specify valid initial test conditions prior to assessing the undervoltage relay functionality. A contributing factor was that the 2X-2 relay was subsequently proven to be in the trip position prior to the surveillance. With the 2X-2 relay in the trip position prior to the test, the test circuit is rendered inoperable. This is why the 27-1 relay did not operate during the test. When the 2X-1 relay was placed in the trip position the trip logic was satisfied, and an invalid undetvoltage actuation signal was initiated.

Corrective actions for the event are: 1) Electrical Maintenance tested the 2X-2 relay and proved the relay to be functioning correctly at the time of testing, 2) The relay will be replaced during the next refueling outage opportunity and root cause analysis will be performed, 3) Operations implemented a change to test the undervoltage relay test circuit on a daily basis which will detect any undervoltage relays in the trip position, 4)

Revise the surveillance procedure to provide instructions on how to confirm relay status prior to and after testing.

FPL Facsimile of NRC Form 366 (6-89)

FPL FaCalmlO OT U.S. kUCLEAR REGULATORY COMMISSION APPHQIED QLO NCL 01 00 0\ 01 kRC FaTT1 366 LAPSES, L0000 (EPTI)

LICENSEE EVENT REPORT (LER) ES TIAAT ED SLIIIEHPE II IHSPONAE TQ CQNPL 0 WITH TITS StaSAADON CCLLECHQH IEASE ST I 000 TATS TOHWHE0 CCLHH NT 0 IHCAHDPHT IMEEN ESTHAATE TO TTE IECaeS AIEIIEPOIITS HAHACEAEHTDIIAHCHTt $10LLLE IAHLEHIIHAAAATaITESHHSHOL TEXT CONTINUATION WAST HISTQN, DC ILAILNAITO TIN tHE RWaW IHDVCTIQNPHON C I TT I 00 0 1 ALLCPS ICE CP NAHACEIHNTAIO SLOOET. WASIWOTCPL DC TOICL FACILITY'NAME(1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR EQUENTIAL REVISIO St. Lucie Unit 1 NUMBER NUMBER 05000313594 0 0 2 0 0 0 2 0 4 TEXT (Ifmore spaceis required, use additional NRC Form 366A's) (17)

On January 13,1994 Unit 1 was in mode 1 at 100% power. Administrative Procedure 1-001025A, Data Sheet 38 surveillance "Functional Test Of Degraded Grid Voltage" was being performed:

When the utility non-licensed operator initiated the test for the 27-1 relay on the safety related 1A3 4150 volt bus the relay did not operate. The procedure directs that in the case of a relay failing to operate, the relay must be placed in the tripped position within one hour in accordance with Technical Specification 3.3.2.1. Data Sheet 38 states to either jumper the 2X-1 or to lift the leads on the 2X-1 relay and bolt them together to place the 27-1 relay in trip. The option of bolting the leads together was selected due to the physical layout of the relay. When the leads on the 2X-1 relay were connected together an invalid undervoltage trip signaI was initiated at 0134 hours0.00155 days <br />0.0372 hours <br />2.215608e-4 weeks <br />5.0987e-5 months <br />. The 1A3 4160 volt bus load shed and the 1A Emergency Diesel Generator (EDG)(EIIS:EK) started and load

., sequenced onto the bus. The utility licensed operators immediately assessed the situation, verified the plant was in a stable condition and entered Off Normal Operating Procedure 1-0910054 "Loss Of A Safety Related AC Bus". During the assessment of plant status, the utility licensed operators discovered the 1A Intake Cooling Water (ICW)(EIIS:Bl) pump and the 1A Component Cooling Water-(CCW)(EIIS:CC) pump were not running. Both pumps were manually started by the utility licensed operators.

At this point, the decision was made. to return the wiring on the 2X-1 relay to the original configuration and to place a jumper on the 2X-1 to facilitate trouble shooting. All targets on the undetvoltage relays were reset. With all indications normal, the utility licensed operators then proceeded to restore normal power to the 1A3 41 60 volt bus. The tie breakers to the 1A2 41 60 voltbuswereclosed,the EDGunloadedanditsoutputbreakeropened. Whenthe EDGoutput breaker was opened, the 1A3 41 60 volt bus load shed again and the EDG toad sequenced onto the bus. The cause of the second load shed was due to the 2X-2 relay remaining in the trip position.

After the second load shed, the 2X-2 relay reset and performed as anticipated. Plant status was again assessed by the utility licensed operators and verified to be stable. The 1A ICW pump and the 1A CCW pump both load sequenced correctly onto the EDG. The undervoltage relays were reset and off-site power was restored to the 1A3 4160 volt bus. This time all equipment functioned as anticipated and the EDG was secured at 0225 hours0.0026 days <br />0.0625 hours <br />3.720238e-4 weeks <br />8.56125e-5 months <br />.

The root cause of this event was a surveillance procedure inadequacy which did not specify valid initial test conditions prior to assessing relay functionality. A contributing factor to the event was that the 2X-2 relay was subsequently proven to be in the trip position prior to the event. With the 2X-2 relay already in the trip position, the 2 out of 2 logic for the undetvoitage trip signal was satisfied when the 2X-1 relay was placed in the trip position. With any of the 2X relays in the trip position the test circuit is rendered inoperable. This is why the 27-1 relay did not operate when the utility non-licensed operator first initiated the test. The test circuit being inoperable does not effect the operation of the undervoltage relays.

FPL Facsimile of NRC Form 366 (6-69)

II FPL FDCSITTSIO at U.S. NUCLEAR REGULATORY COMMISSION APPNOYEOOe Na SiICCI SI NRC Forn SE6 ESPY'OCYT rt'p89)

E0TIAATEo OfNOEN PE II fKSIYPEW TO COAPE YYNTll TINS PPEYWAllON CCEIECTYSN LICENSEE EVENT REPORT (LER) TNaN CT: 000 If@, TCIIWATES INNNNNI0INOANOWC TAfcEN ECDNATE To no IECooa AtOTEfEYITCIAANACEIENTOIIANCHIPTCCSISOIAJCIEAIIIKIAAATCIIYA04NSSESE TEXT CONTINUATION WAONASTCYI.DC tOSYS AIET TOOO PAPETNESW fEOUCTION PNCIECT TS1SOAISYJ Cf ffCE Cf NANACENENTAIETTSNCET.WASTNICTIYEDCt05CL FACILITYNAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR EQUENTIAL REVISIO NUMBER NUMBER St. Lucie Unit 1 0

TEXT (Ifmore spaceis required, use additional NRC Form 366A's) (17) 500 0335 9 4- 0 0 2 0 0 0304 This event is reportabie under 10 CFR 50.73.a.2. iv as "any event or condition that resulted in manual or automatic actuation of any engineered safety feature, including the Reactor Protection System (RPS).N Only one train of safety related components was temporarily de-energized during the event. The 1A EDG started and loaded onto the safety related bus as designed. The redundant safety related train was available for service and the plant remained in a stable condition throughout the entire event. Thus, the health and safety of the public were not affected at any time during. the event.

The cause of the 1A ICW and 1A CCW pumps not restarting during the initial load shed was due to the actual manipulation of the leads in the undervoltage trip circuit. If the trip signal is initiated and then reset within 250 milliseconds, the restart signal for these pumps is defeated. During an actual undervoltage condition the trip signal is not reset for approximately 10 seconds. The pumps were verified to restart per design for a valid undervoltage condition.

The design of the undervoltage relaying system is different in Unit 2, therefore this event is not applicable to Unit 2.

1) Electrical Maintenance tested the 2X-2 relay and proved the relay to be functioning correctly at the time of testing. At this point, the jumper was removed from the 2X-1 relay which restored the normal 2 out of 2 logic. The cause of why the 2X-2 relay was in the trip position prior to the event is unknown.

2) Electrical Maintenance will replace the 2X-2 relay during the next refueling outage opportunity and a root cause investigation analysis will be performed.

3) Operations implemented a change to test the operability of the undervoltage relay test circuit on a daily basis. This test will detect any undervoltage relays which are in the trip position. This test will remain in effect until the relay is replaced.

4) Electrical Maintenance will assist Operations in the revision to the undervoltage relay test procedure prior to the next scheduled surveillance to provide instructions on how to test the status of the test circuit prior to the actual surveillance being performed and as part of test restoration.

The 2X-2 relay proved to be functioning correctly during subsequent testing. The reason for the 2X-2 relay being in the trip position prior to the event is unknown. The 2X-2 relay is not being considered tailed at this time.

FPL Facsimile of NRC Form 366 (6-89)

~

F PL FSCSl ITTTS d U.S. NUCLEAR REGULATORY COMMISION APPNOITD OAO Ma $ 1 $ 001 tl NRC Fom 366 STPSNa A%It LICENSEE EVENT REPORT (LER) fSTIAATID utMMNPT IT ISSPOMSC TO IMSMLTPATH TITS I INCITATIONCOutC TIOM IMOIMST:$ 00 TITS fCIIWAICICCASMMTS IMCANCPMT IMTXN SDMATC TO DC ISCCITTS 0

TEXT CONTINUATION No ISPONTSNANACC IMMICNAMCNIP ISaua IAMSTMTINOAATDNT WANMIOTOM.DC tOIIa HO TO Tl E 0 JILT IMMÃSIIMCVCTIDMPACISCT T$ 1 I00 ltl$ Cf ITCC CP NANACTINN T AM$ OATCC T. WANSIC TCPA DC SMCa FACILITYNAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR EQUENTIAL REVISIO St. Lucie Unit 1 NUMBER NUMBER 0 500 03135 9 4 0 0 2 0 0 0 4 0 4 TEXT (lfmore spaceis required, use additional NRC Form 366A's) (17)

A previous similiar evert was recorded in LER 3B9-92-03-00 "Inadvertant Actuation of the 28-Emergency Diesel Generator due to Design Error" in that the 283 bus load shed and the Diesel generator loaded onto the bus during undervoltage relay testing. This test circuitry design is difterent than the test circuit used on Unit 1.

FPL Facsimile of NRC Form 366 (6-89)

0 -1 i