ML17228A373

LER 93-008-00:on 931102,manual Reactor Trip Initiated Due to High Gas Temps in Main Generator.Caused by Procedural Deficiency.Turbine Lube Oil Cooling Sys Configuration verified.W/931201 Ltr

ML17228A373
Person / Time
Site:	Saint Lucie
Issue date:	12/01/1993
From:	Sager D, Young R FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-93-298, LER-93-008-01, LER-93-8-1, NUDOCS 9312100179
Download: ML17228A373 (10)

Text

ACCELERATED DI RIBUTION DEMONST TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS) i.CCESSION NBR:9312100179 DOC.DATE: 93/12/Ol NOTARIZED: NO DOCKET ~

FACIL:50-389 St. Lucie Plant, Unit 2, Florida Power 6 Light Co. 05000389 AUTH. NAME AUTHOR AFFILIATION YOUNG,R.J. Florida Power 6 Light Co.

SAGER,D.A. Florida Power 6 Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 93-008-00:on 931102,manual reactor trip initiated due to high gas temps in main generator. Caused by procedural deficiency. Turbine lube oil cooling sys configuration D verified.W/931201 ltr.

DISTRIBUTION CODE:'E22T COPIES RECEIVED LTR 'ENCL, SIZE:

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

NOTES:

A RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID D CODE/NAME LTTR ENCL PD2-2 LA 1 1 PD2-2 PD 1 1 NORRIS,J 1 1 D INTERNAL: ACRS 2 2 AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DS P 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 EG NRR~~SA/SPLB F~+ FILE 02 01 1

1 1

1 1

1 NRR/DSSA/SRXB RES/DSIR/EIB 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 NUDOCS FULL TXT 1 1 R D

D D

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOivl 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

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P.O. Box 128, Ft. Pierce, FL 34954-0128 December 1, 1993 L-93-298 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re: St. Lucie Unit 2 Docket No. 50-389 Reportable Event: 93-008 Date of Event: November 2, 1993 Manual Reactor Tri due to Hi h Gas Tem eratures in the Main Generator Caused b a Procedural Deficienc 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. er Vice P sident St. Luc3.e Plant DAS/JWH/kw Attachment cc: Stewart D. Ebneter, Regional Administrator, USNRC Region Senior Resident Inspector, USNRC, St. Lucie Plant II DAS/PSL 11024-93 (j QrQ A 9312100179 931201 PDR ADQCK 05000389 S PDR an FPt. Group company

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FPL-Focslrttlo ol NRC Form X6 FACILITY NAME (1) 4 LICENSEE EVENT REPORT (LER)

St. Lucie Unit 2 NUClEAR REGUlATORY COMMISSION AIEROIIO QWI Nrk $ 1104'ill 0AANER 0000 t EST MATC0 8IAKC0 TER IESAQNTE To CQNAET WITN TITS 00OISMTTQN OIATECTIQN RIOT IEQTTWS IIO IEACRTS NANACEIRNTSAANCN I04000 TIS.

004000000 WAR f

DOCKET NUMBER (2) 050003891 NESCIENT IRCSEST: I04 IRT ICRWAITTCQNNTNTS IEONENNO RJTTEN ESTNIATE TO TIC IEOAATCRT

. DC tONR NET To THE 0AIERWCRK INDUCRON 0ROE CT ERI041010 Cf CE Cf NANAOElENTMATTllÃRT,WASHNOTC70 DC TTN00 0 3

'~ (") Manual Reactor Trip Due To High Gas Temperatures In The Main Generator Caused By A Procedural Deficiency EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED(8)

MOITrIH DAY YEAR YEAR S IAL R DAY YEAR FACILITYNAMES DOCKET NUMBER(S)

N/A 05 000 1 1 0 2 9393 0 0 8 0 0 0 1 9 3 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) 0 4 5 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 andin 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 AREA CODE Robert J. Young, Shift Technical Advisor COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13 4 0 7 465-3550 REPORTABLE CAUSE SYSTEM COMPONENT TO NPRDS CAUSE SYSTEM COMPONENT MANUFAC- 'fURER REPORTABLE TO NPRDS I I I SUPPLEMENTAL REPORT EXPECTED 14 EXPECTED MONTH DAY YEAR SUBMISSION YFS (Ifyes, complete EXPECTED SUBMISSION DATE) NO DATE (15)

ABSTRACT (Limit to 1400 spaces. i e. approximately fifteen single-space typewritten lines) (16)

On November 2, 1993, St Lucie Unit 2 was in Mode 1, operating at 45% power. At 0443 hours0.00513 days <br />0.123 hours <br />7.324735e-4 weeks <br />1.685615e-4 months <br /> the control room annunciator for the main generator hydrogen system panel actuated. Utility licensed operators checked the hydrogen gas temperatures and saw that the average cold gas temperature was increasing. Before any attempts to reduce the hydrogen gas temperatures could be initiated, the average cold gas temperature reached the limit in the off-normal procedure. At 0447 hours0.00517 days <br />0.124 hours <br />7.390873e-4 weeks <br />1.700835e-4 months <br />, in accordance with Off-Normal Operating Procedure 2-200030 "Main Generator", a manual reactor and turbine trip were initiated. '

were performed as was stabilized in Mode 3, Hot Standby.

The root cause for the increase in the main generator hydrogen gas temperatures was due to the operation of the turbine cooling water system with two turbine lube oil coolers lined up to receive turbine cooling water flow and only one turbine cooling water pump available. The turbine cooling water operating procedure permits the isolation of one lube oil cooler that is not in use to maximize flow to those cooling systems in sewice. Based on plant conditions at 45 %, utility licensed operators decided to maintain both turbine lube oil coolers in service.

Corrective Actions for this event: 1) Plant personnel verified that the turbine lube oil cooling system configuration was the cause for the event by reproducing system conditions just prior to the trip. 2) Utility operators isolated a turbine lube oil cooler. 3) The generator vendor verified that the hydrogen gas temperatures experienced during this event would not adversely affect the main generator. 4) I8 C verified that the turbine cooling water and component cooling water temperature control valves were operating properly. 5) The plant operating procedure will be enhanced to clarify requirements for operation of the turbine cooling water system.

FPL Facsimile of NRC Form 366 (6-89)

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FPL Facalmlle Ol U.S. NUCLEAR REGULATORY COMMISSCN AFFRCFFCOOIO NCA 0N0010l NRC FomT 366 CTF0e00 IDIOT (6 89) I0 OOANC0 00 TN h00 0000IATION OOUCCOON LICENSEE EVENT REPORT (LER) COTAAATCO 000TOCN FC R ICOFONTC IRCCR 0'h 000 F000 ICTTFFNTT OCNN+NT 0 IKOARONO TAACNN CCRNATC TO Tle Ie000000 FACT IOFORT 4 NANAOCAC NT 0 RANCH II'000j. TAO. IAJCLCAR INOAATORF TEXT CONTINUATION wAONIOTON.OO 0000C AFO Tone 0AFoNRTw INTAcnDNFRDROT TTII00l0OOIIIOC OF NANAOCleNT NCI OIAFOCT, WANINO TOFT OO TONCL FACILITYNAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR g EQUENTIAL NUMBER g REVISION NUMBER St. Lucie Unit 2 0 500 0389 9 3 0 0 8 0 0 0 2 0 3 TEXT (Ifmore spaceis required, use additional NRC Form 366A's) (17)

On November 2, 1993, St. Lucie Unit 2 was in Mode 1 and operating at 45% power in order to allow unit operation until the end of the fuel cycle in February 1994 for a scheduled refueling outage. At 0443 hours0.00513 days <br />0.123 hours <br />7.324735e-4 weeks <br />1.685615e-4 months <br /> the control room annunciator for the main generator hydrogen system panel (EIIS:TK) actuated. Utility licensed operators checked the hydrogen gas temperatures and saw that the average cold gas temperature was increasing. Utilityoperators were dispatched to check the main generator hydrogen cooling system and the turbine lube oil cooling system (EIIS:TD), as these are the largest loads on the turbine cooling water system (EIIS:KB). No anomalies were noted in the hydrogen cooling system. However, the operator at the turbine lube oil coolers noted that turbine cooling water flow to the oil coolers was twice what had been noted earlier. Before any attempts to reduce the hydrogen gas temperatures could be initiated, the average cold gas temperature reached the limit in the off-normal operating procedure. In accordance with Off-Normal Operating Procedure 2-2200030 "Main Generator" a manual reactor and turbine trip was initiated. QiZZfIIld uncomplicated reactor trip with all safety functions being met. Four sets of safety function status checks were performed in accordance with Emergency Operating Procedure EOP-2, Qaag~lfjii QKmary, and the unit was stabilized in Mode 3, Hot Standby. Hydrogen gas temperatures returned to nominal values following the reactor and turbine trip.

The root cause for the temperature increase of the hydrogen gas in the main generator was due to the operation of the turbine cooling water (TCW) system with two turbine lube oil coolers lined up to receive TCW flow and only one TCW pump available. The Operating Procedure 2-0330020 "Turbine Cooling Water System Normal Operation" permits the isolation of TCW to the lube oil cooler that is not in use to maximize TCW flow to those cooling systems in service. While the unit power was reduced, various secondary side components were removed from service to allow preventive maintenance or overhaul. Based on plant conditions utility licensed operators decided to maintain TCW to both of the turbine lube oil coolers.

This event is reportable under 10CFR 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".

The Assistant Nuclear Plant Supervisor directed Licensed Operators to manually trip the reactor and turbine in accordance with Off-Normal Operating Procedure 2-2200030 "Main Generator" due to the high hydrogen gas temperatures in the main generator that could lead to equipment damage. The hydrogen cooling system's function is to remove heat produced during operation of the main generator. The plant response to this event is bounded by Section 15.2.1.2 of the St. Lucie Unit 2 FUSAR which assumes a decreased heat removal by the secondary system due to the isolation of the turbine at 102% power. The actual plant response was more conservative than described in the analysis for the following reasons: 1) The unit was at a reduced power, 45%. 2) The reactor and turbine were manually tripped. 3) Neither steam generator had water level decrease below 40%

narrow range. Therefore, the capability of the steam generators to act as a primary heat sink was not in jeopardy. The health and safety of the public was not affected by this event.

FPL Facsimile of NRC Form 366 (6-69)

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FPL Facslm1ool U.S. kUCLEAR REGULATORY COMMISSIOk NfffTTTTKDCATT Nck ST Tc 4 T DT kRC Form S68 (ITSQ)

I fTTTTNO TOOT T LICENSEE EVENT REPORT (LER) TDTTAATTOTATTOCN TNCINDTT TOO ffTL ffIT fccfoNTC To cowcf M I Wl TTNTNcorNAATIONCCTTECHION f

TOTTWATT>CONANNT INOATTTNTOTATNTTN DTNurc To TTO INCCTTTO TEXT CONTINUATION ATAT fcfoNTO swum ACNT DTTANCN Tf ffcr. TAO ATCATATTTNTNAATCNT WATTTNOTCN.ocfrrTTAATATToTTCOCTTWcfcrfcoucTTONTTToccforrccrcfACTTTCC Cf TwucCNTNT AAATTANCCT. WANNTOTCAADC TTNTTL FACILITYNAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR EQUENTIAL REVISION St. Lucie Unit 2 NUMBER NUMBER 0500038993 TEXT (Ifmore spaceis required, use additional NRC Form 366A's) 0 0 8 0 0 0 3 0 3 (17)

1) Utilitylicensed operators performed a manual reactor and turbine trip in accordance with Off-Normal Procedure 2-2200030 "Main Generator".

2) Plant personnel verified that the turbine lube oil cooling system configuration was the cause of the event by reproducing system conditions similar to those conditions just prior to the trip and verifying TCW system response.

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3) The generator vendor verified that the hydrogen gas temperatures experienced during this event would not adversely affect the main generator.

4) IBC verified that the temperature control valves in the TCW and the component cooling water systems were operating properly.

5) Utilityoperators isolated a turbine lube oil cooler as permitted by the Operating Procedure 2-0330020 "Turbine Cooling Water System Normal Operation".

6) Operating Procedure 1 8 2-0330020 "Turbine Cooling Water System Normal Operation" will be enhanced to clarify requirements for operation of the TCW system.

There were no component failures involved with this event This is the first event in which increasing main generator gas temperatures necessitated a manual unit trip.

FPL Facsimile of NRC Form 366 (6-89)

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