ML17349A457

LER 92-007-00:on 920929,AFW Actuation Occurred.Caused by Loss of Suction Pressure to Main Feedwater Pump.Procedures Re Condensate Polisher Sys revised.W/921029 Ltr

ML17349A457
Person / Time
Site:	Turkey Point
Issue date:	10/29/1992
From:	Knorr J, Plunkett T FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-92-294, LER-92-007-01, LER-92-7-1, NUDOCS 9211030321
Download: ML17349A457 (12)

Text

zccsi.~~~riD DiSraiD~YiOw DZ~OXSra~vrOx SvSrzivr REGULAT(e INFORMATION DZSTRIBUTIONOZSTEM (RZDS)

ACCESSION NBR:9211030321 DOC.DATE: '92/10/29 NOTARIZED::NO DOCKET FACIL:50-251 Turkey Point Plant, Unit 4, Florida Power and Light C 05000251

-AUTH.NAME AUTHOR Florida Power 6 Light Co.

'AFFILIATION'NORR,J.E.

PLUNKETT,T.F., Florida Power 6 Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 92-007-00:on 920929,AFW actuation occurred. Caused by loss of suction pressure to main feedwater pump. Procedures re condensate polisher sys revised.W/921029 ltr.

DISTRIBUTION CODE: ZE22T COPIES RECEIVED:LTR t ENCL / SIZE:

TITLE: 50'.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:NRR RAGHAVANFL 05000251 /

A RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2. LA 1 1 PD2-2 PD 1 1 AULUCK,R 1 1 INTERNAL: ACNW 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB'RR/DET/EMEB 1 1 AEOD/ROAB/DSP 2 2 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB ~

1 1 NRR/DREP/PRPBll 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB8H3 1 1 NRR JPST/SPLB8Dl 1 1 NRR/DST/SRXB 8E 1 1 02 1 1 RES/DSZR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL EG&G BRYCEFJ AH 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHYFG.A 1 1 NSIC POORE,W. 1 '1 NUDOCS FULL TXT 1 1 NOTES: 1 1 A

NOTE TO ALL RIDS" RECIPIENTS:

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

ROOM Pl-37'(EXT. 504-2065) 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

i)

.0. Box 029100, Miami, FL, 33102-9100 FPL 08T 2 b 1992 L-92-294 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Nashington, D. C. 20555 Gentlemen:

Re: Turkey Point Unit 4 Docket No. 50-251 Reportable Event: 92-007-00 Automatic Auxiliary Feedwater Start on Main Feedwater The attached Licensee Event Report 251-92-007-00 is being provided in accordance with 10 CFR 50.73 (a) (2) (iv) .

If there are any questions please contact us.

Very truly yours, T. F.

President Plunkett'ice Turkey Point Nuclear TFP/JEK/3k enclosure cc: Stewart D. Ebneter, Regional Administrator, Regi'on II, USNRC Ross C. Butcher, Senior Resident Inspectors USNRCr Turkey Point Plant 636'.921029 9'211030321 05000251 PDR S

ADQCK an FPL Group company PDR

/flu'

Ii Ck LZCENSEE EVENT REPORT (LER}

DOCKET NUMBER l2) PAGE l3)

FACILITY NAME l1)

TURKEY POINT UNIT 4 05000251 1 or 4 TITLE l4) Automatic Auxiliary Feedwater Start on Main Feedwater Pump Trip EVENT DATE l5) LER NUMBERl6) RPT DATE l7) OT)leR FACZLITIES INV l8)

DAY YR YR 'SEQ6 Rl MON ,

YR FACILITY NAMES DOCKET 6 lS) 29 92 92 007 ,00 10 29 92 TURKEY POINT UNIT 3 05000250 09 OPERATING MODE lP) THIS REPORT IS SUBMITTED PURSUANT TO THE RE UIREMENTS OF 10 CFR 10 CFR 50.73 a 2 iv poNeR Levee llo) 2t LICENSEE CONTACT FOR THIS LER (12)

James E. Knorr, Licensing Engineer TELEPHONE NUMBER 305-246-6757 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED ZN THIS REPORT l13)

CAUSe SYSTEM COMPONENT MANUFACTURER NPRDS2 CAUSE SYSTEM MANUFACTURER NPRDS2 COMPONENT BA 33 E081 SUPPLEMENTAL REPORT EXPECTED l14) No X Yes 0 rxpecTeD SUBMISSION DATE l15)

DAY YEAR llf yes, cmaplete EXPECTep SUBMISSION DATE)

ABsTRAcT l16) On September 2 9,. 1 9 92, Turkey Point Unit 4 was in Mode 2 at 2%

reactor power. At 1450 EST, during the performance of a condensate polisher backwash, an automatic auxiliary feedwater (AFW) actuation occurred. During the backwash evolution, the inlet valve (CV-4-6351D), on the 4D condensate polisher, opened causing the main feedwater pump suction pressure to drop.

The pressure drop occurred because the open inlet valve (CV-4-6351D) allowed the main feedwater pump suction pressure to be. relieved through the 4D polisher vent valve (CV-4-6353D) to the backwash receiver tank which is kept at atmospheric pressure. The reduced suction pressure on the 4A main feedwater pump caused a pump trip. This pump trip resulted in the automatic start of the in-service auxiliary feedwater pumps and isolation of steam generator blowdown. At 1520 EST the 'A'tandby feedwater pump was started to supply feedwater to the steam generators and the auxiliary feedwater pumps were placed in standby. Other than the automatic start of the auxiliary feedwater pumps no manual or automatic reactor protection system or engineered safety feature actuations occurred or were required.

The NRC was originally notified of this event in accordance with 10 CFR 50.72 (b) (2) (ii) .

0 0 LICENSEE ENT REPORT (LER) TEXT ONTINUATION FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 92-007-00 02 oF 04 I. EVENT DESCRIPTION On September 29I 1992'urkey Point Unit 4 was in Mode 2 at 2%

reactor power. At 1450 EST, during the performance of a condensate polisher backwash, an automatic auxiliary feedwater (AFW) actuation occurred. During the backwash evolution, the inlet valve (CV 6351D) (EIIS-SF,,IEEE-V), on the 4D condensate polisher (EIIS-SF,IEEE-DM)I opened causing the main, feedwater pump suction pressure to drop.

This main feedwater pump suction pressure drop occurred because .the open inlet valve (CV-4-6351D) allowed'the pressure to be relieved through the 4D polisher vent valve (EIIS-SF,IEEE-V) (CV-4-6353D) to the backwash receiver tank (EIIS-SF,IEEE-TK) which is kept at atmospheric pressure. As a result of this pressure drop, the following expected actions occurred. The reduced suction pressure on the 4A main feedwater pump (EIIS-SJ,IEEE-P) caused a pump trip. This pump trip resulted in the automatic start of the A and C in-service auxiliary feedwater pumps (the B AFW pump was out of service for post maintenance testing) (EIIS-BA,IEEE-P) and. isolation of steam generator blowdown (EIIS-SB). At 1520 EST the AFW system was returned to the, standby condition. Other than the automatic start of the auxiliary feedwater pumps no manual or automatic reactor protection system or. engineered safety feature .actuations occurred or were required.

The NRC was notified of this event in accordance with 10 CFR 50.72 (b) (2) (ii) at 1845 EDT, September 29, 1991.

II. EVENT CAUSE a ~ Immediate Cause The immediate cause of the automatic start of the AFW pumps was the trip of the 4A main feedwater pump upon loss of. suction pressure.

b. The loss of suction pressure to the main feedwater pump was caused by the diversion of condensate flow to the "D" polisher vessel, through the open inlet valve (CV-4-6351D) and out. the vessel vent valve (CV-4-6353D).to the backwash receiver. The root cause for this flow path to be established was the malfunction of a limit switch on CV-4-6351D. This failure resulted in a logic fault allowing the diversion of the condensate flow. During subsequent inspection of other valves in this non-safety related system, some valves and limit switches in need of preventative maintenance were identified.

The maintenance work has been planned and prioritized. The control system for the condensate polisher appeared to function properly.

il 41 4 U

1 t ~

LICENSEE EVENT REPORT (LER) TEXT <ONTINURTION FACILITY NAME KET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 92-007-00 03 oF 04 XIX. EVENT SAFETY ANALYSIS The condensate polisher (demineralizer) system is a non-safety related system used to improve the purity of condensate water for use in the steam generators by removal of dissolved and suspended solids from the condensate water. In this event, suction pressure was reduced resulting in a trip of the operating 4A main feedwater pump.

The trip of the main feedwater pump and the subsequent loss of the main feedwater supply is a previously analyzed event. As a result of these analyses, plant procedures were developed to provide operator guidance in response to such a transient. The procedures and plant

'design assure that the plant is stabilized in a safe condition in accordance with the plant Technical Specifications. For this event, steam generator water levels were maintained within design operating levels by the automatic start of the auxiliary feedwater system. A standby feed water pump was subsequently started and the auxiliary feedwater pumps were secured and returned to their standby condition in accordance with plant procedures.

During the event, the 'B'uxiliary feedwater pump was out of service for required post maintenance testing prior to return to service.

Other than the automatic start of the auxiliary feedwater pumps no manual or automatic reactor protection system or engineered safety feature actuations occurred or were required. Engineered safety features were designed to prevent by anticipation or by reducing the severity through quick automatic response, events that could affect the health and safety of the public.

Based upon the above, the health and safety of plant personnel and the general public were not compromised 'as a result of the loss of main feedwater and automatic start of the auxiliary feedwater systems.

XV. CORRECTIVE ACTIONS a ~ Immediate Corrective Action The 'A'tandby feedwater pump was started and used to supply feedwater to the steam generators. This feedwater supply allowed the auxiliary feedwater pumps to be placed in standby.

b. Corrective Actions to Prevent Recurrence

1. The condensate polisher system valves and operators were walked down in detail to determine needed component repairs or replacement. Appropriate work orders for identified needs were written. Work required to return the system to operation was completed.

2. Procedure OP-7001.3, Condensate Polishing System Powdex Vessel Operation, was revised to require manual control of inlet and outlet valves to prevent inadvertent opening of the vessel inlet or outlet valves. Further investigation may require other appropriate corrective actions.

li LXCENSEE IVIT REPORT (LER) TEXT lTTINUATXON

-FACZLITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 92-007-00 03 or 04 ZZZ. EVENT SAFETY ANALYSIS The condensate polisher (demineralizer) system is a non-safety.

related system used to improve the purity 'of condensate water for use in the steam generators by removal of dissolved and,suspended solids from the condensate water. In this event, suction pressure was reduced resulting in a trip of the operating 4A main feedwater pump.

The trip of the main feedwater pump and the subsequent loss of the main feedwater supply is a previously analyzed event. As a result of these analyses, plant procedures were developed to provide operator guidance in response to such a transient. The procedures and plant design assure that the plant is stabilized in a safe co'ndition in accordance with the plant Technical Specifications. For this event, steam generator water levels were maintained within design operating levels by the automatic start of the auxiliary feedwater system. A standby feed water pump was subsequently started and the auxiliary feedwater pumps were secured and returned to thei;r standby condition in accordance with plant procedures.

During the event, the 'B'uxiliary feedwater pump was out of service for required'ost maintenance testing pri'or to return to service.

Other than the automatic start of the auxiliary feedwater pumps no manual or automatic reactor protection system or engineered safety feature actuations occurred or were required. Engineered safety features were designed to prevent by anticipation or by reducing the severity through quick automatic response, events that could affect the health and safety'of the public.

4 Based upon the above, the health and safety of plant personnel and the general public,were not comprom'ised as a result of the loss of main feedwater and automatic start of the, auxiliary feedwater systems.

IV. CORRECTIVE ACTIONS a ~ Immediate Corrective Action The 'A'tandby feedwater pump was started and used to supply feedwater to the steam generators. This feedwater the auxiliary feedwater pumps to be* placed in standby.

supply'llowed

b. Corrective Actions to Prevent Recurrence

1. The condensate polisher system valves and operators were walked down in detail to determine needed component repairs or replacement. Appropriate wo'rk orders for identified needs were written. Work required to return the system to operati'on was completed.

2. Procedure OP-7001.3, Condensate Polishing System Powdex Vessel Operation, was revised to require .manual control of inlet and outlet valves to prevent inadvertent opening of the vessel inlet or outlet valves. Further investigation may require other appropriate corrective actions.

0