ML17342B060

LER 87-026-00:on 871121,component Cooling Water (CCW) Pump 4B Autostarted During CCW Pump 4C Return to Svc.Caused by Insufficient Margin Between Operating & Setpoint Pressures.Increased Margin initiated.W/871218 Ltr

ML17342B060
Person / Time
Site:	Turkey Point
Issue date:	12/18/1987
From:	Salamon G, Woody C FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
L-87-521, LER-87-026-01, LER-87-26-1, NUDOCS 8712290086
Download: ML17342B060 (9)

Text

I ACCELERATED PoTRIBUTION DEMONS'%STION SYSTEM REGULATORY INFORMATION -DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8712290086 DOC.DATE: 87/12/18 NOTARIZED- NO DOCKET g FACIL:50-251 Turkey Point Plant, Unit 4, Florida Power and Light C 05000251 AUTH. NAME AUTHOR AFFILIATION SALAMON,G. =

Florida Power & Light Co.

WOODY,C.O. Florida Power & Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 87-026-00:on 871121,component cooling water pump 4B auto-start due, to unanticipated drop in header pressure.

W/8 ltr.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR i ENCL t SIZE:0 TITLE: 50.73 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR' ENCL.

PD2-2 LA 1 1 PD2-2 PD 1 McDONALD,D 1 1 A INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 AEOD/DOA 1 1 AEOD/DSP/NAS 1 1 AEOD/DS P/ROAB 2 2 AEOD/DSP/TPAB 1 1 ARM/DCTS/DAB 1 1 DEDRO ~

1 1 NRR/DEST/ADS 1 0 NRR/DEST/CEB 1 1 NRR/DEST/ELB 1 1 NRR/DEST/ICSB 1 1 NRR/DEST/MEB 1 1 NRR/DEST/MTB 1 1 NRR/DEST/PS B 1 1 NRR/DEST/RSB 1 1 NRR/DEST/SGB 1 1 NRR/DLPQ/HFB 1 1 NRR/DLPQ/QAB 1 1 NRR/DOEA/EAB 1 1 NRR/DREP/RAB 1 1 NRR/DREP/RPB 2 2 NE+/DRM SIB 1 1 NRR/PMAS/ILRB 1 1 G 02 1 1 RES DEPY GI 1 1 RES TELFORD,J 1 1 RES/DE/EIB 1 1 RGN2 FILE 01 1 1 1 EXTERNAL: EG&G GROH,M 5 5 FORD 'BLDG HOY,A 1 1 H ST LOBBY WARD 1 1 LPDR 1 1 R' NRC PDR 1 1 NSIC HARRIS,J 1 1 NSIC MAYS,G 1 1 A ~

TOTAL NUMBER OF COPIES REQUIRED: LTTR 46 ENCL 45

• r NRC Form 344 UA. NUCLEAR AECULATORY COMMISSION (9431 APPROVKO OMS NO. 31500)OC EXPIAKS: 4/31/ES LICENSEE EVENT REPORT ILER)

FACILITY NAME (ll DOCKET NUM&SR (2(

Turkey Point Unit 4 p 5 p p p 2 5 1 q oF

"'"(" omponen oo sng a er ump u o- ar P In Header Pressure When CCW Pump 4C Was Returned to Service EVENT DATE (5) LE R NUM& E R (4) REPORT DATE (7) OTHER FACILITIES INVOLVED (4)

MONTH OAY YEAR YEAR P+r,' E 0 U E HT I A I. IIEVISIOH MONTH DAY YEAR FACILITYNAMES DOCKET NUM&ERIS) v/UMSEII NUMSEA 0 5 0 0 0 2 1 8 7 8 7 2 6 0 0 1 2 1 8 8 7 0 5 0 0 0 OPEAATINQ THIS REtORT IS SU&MITTED PURSUANT T0 THE AEOUIRKMENTS OF 10 CFR (): /Cnrcc mr or more o/ tnr /otlovrint/ Ill MODE (SI 20A02(5) 20.405(cl 50.734)(2)(lvl 7$ .7((5)

POWER 20AOS( ~ I(1 l(0 50.34(c) (1) 50.7$ (e) (2(lvl 7$ .71(cl LEVEL (10) p p 20 ASS(el(I I (5 I 50.34(ell2) 50.7$ 4)(2)(v&) OTHER /SprCI/yin AOttrrCI ortovrent/in Tert. IYAC Form 20AOS(e Ill I (rE) 50.7 3(e) (2) I I) 50 73( ~ ) (2)(nil) (AI 366AI 20A04 Ie) (1)(Iv) 40.73( ~ l(2)IE) 50.73(el(2)(vIQHS) 20AOS(e) (l)(vl 50,73(el(2) IIIII 50.73(e I (2) 4)

LICENSEE CONTACT FOR THIS LER 112)

NAME TELEPHONE NUMSEA ARKA CODE Gabe Salamon, Compliance Engineer 305 246 -65 60 COMtLETK ONE LINE FOR EACH COMPONENT FAILURE DKSCRISED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFAG CAUSE SYSTKM COMPONENT'ANUPAC.

TURER TURER SUtPLEMENTAL REPORT EXPECTED (lel MONTH DAY YEAR EXPECTED SU&MISSION DATE IISI YES /I/ yrt, comp/etc EXPECTED SI/SMISSIOI/ DATE/

X ASSTRACT ((imit to IrOO tprcrt, /.r., rporo/nmrtrty AIMrn tint/oMrcr typevrrinrn Irnre/ ll&l On November 21, 1987, at 1030, with Unit 4 in mode 5, Component Cooling Water (CCW) pump 4B auto-started. At the time of this event, the 4C CCW pump was being returned to service, and a pressure test of the pump was be performed. In preparation for this test the suction isolation valve was opened, and the empty pump and piping between the isolation valves was filled. This rapid fill resulted in a 7X drop in the CCW Surge Tank level, a drop in header pressure below 75 psig, and the auto-start of the 4B CCW pump. Following the completion of the filling operation the header pressure quickly returned to normal . Just prior to this event, on November 19, 1987, Turkey Point changed from 2 pump to 1 pump operation during shutdown conditions. The causes of the event were insufficient consideration of the decreased margin between the new operating pressure and the auto-start setpoint under single pump operation and insufficient instructions to the operators valving in the 4C pump on the proper techniques for filling and venting empty piping. Efforts to lower the CCW discharge pressure setpoint further have been initiated. The Training Department will evaluate this event for incorporation into future operator training on the proper methods to fill and vent empty piping.

8 DR Allocl,. K 87i2l 8 05pppg~i DCa NRC Form 344 IS 531

r U.S. NUCLEAR REGULATORY COMMISSION NRC Form 388A lPS3)

LICENSEE EVEM'EI"ORT (LER) TEXT COMTIMUATION APPROVED OMS NO 3IEOWI(M EXPIRFS: 8/3(/88 r

FACILITY NAME (ll DOCKET NUMSER (3) LER NUMBER (8) PACE (3)

()g'I SEQUENTIAL rIEvrsloN YEAR r(p NVMooll Turkey Point Unit 4 o so oo251 87 02 6 0 002 OF 0 3 TEXT ///moro Nroco */or/rworL ooo /r/Or/o/ BRC (rorrn 38SA8/ (17)

On November 21, 1987, at 1030, with Unit 4 in mode 5, Component Cooling Water (CCW) (EIIS:CC) pump 4B auto-started upon sensing a header pressure less than the 75 psig setpoint . CCW pump 4A continued to operate during this event .

At the time of this event the 4C CCW pump was being returned to service following an overhaul. Prior to taking pump 4C out of service (OOS), valves 4-701C, the manual pump suction isolation valve, and 4-703C, the manual discharge isolation valve, were closed. Upon reinstallation of the pump, a pressure test to assure that no leaks were present was initiated . The suction isolation valve was opened, and the empty pump and piping between valves 4-701C and 4-703C were filled with water. This rapid fill resulted in a 7X drop in the CCW Surge Tank level and a drop in header pressure below 75 psig. Upon the pressure dropping below the setpoint, the logic for the auto-start, of the 4B pump was completed starting the pump. Header pressure quickly returned to normal.

CAUSE OP EVENT The causes of the event were as follows:

1) insufficient consideration was given to the increased potential for the inadvertent auto-start of an additional CCW pump during 1 pump operation with a fill and vent of a portion of the CCW system in progress.

2) insufficient guidance on the fill and vent of the empty piping was provided to the operators performing the valving in of the 4C pump.

Until November 19, 1987, Turkey Point had been operating with 2 CCW pumps concurrently when cooling the unit using the Residual Heat Removal (RHR) System.

In order to decrease long term CCW heat exchanger tube degradation and pump wear concerns, a determination was made to operate with 1 CCW pump during RHR cooling.

Two of the consequences of operating with 1 CCW pump were that the normal operating CCW system pressure was lower by approximately 10 psig, and the developed pump head dropped faster with increasing flow due to the increased slope of the pump curve at the new operating point. Normal RHR 2 pump system operating pressure was90-100 psig, depending on system alignment, and the setpoint for the auto-start of an additional pump was 78.5 +/- 5 psig. When single pump operation was recommended, it was realized that inadvertent CCW pump auto-starts were more likely, and as a result, the setpoint was lowered to 75 +/- 1.5 psig. This change in the setpoint was not sufficient to compensate 'for the decrease in the normal system pressure coupled with the rapid fill of the empty 4C pump piping.

The operators opening valve 4-701C realized that there was a potential for an auto-start of the 4B pump. They were also under the impression that, as the valve was a large manual gate valve which takes 5 or more minutes to open fully, the valve NRC FORM 388A (883)

/(RC Form 344A US. NUCLEAR REGULATORY COMMISSION (S~u)

LICENSEE EVENT REPORT (LER) TEXT CONTIN TION APPROVED OMS NO, 3150M(04 EXPIRES: 8/31/48

/r DOCKET NUMSER (1)

FACILITY NAME (1) LER NUMBER (4) ~ AOE (3) yEAR s/ro 55ovENTIAL NVM44/l:.."Q rr5vr5loN NVM 5R Turkey Point Unit 4 8 7 0'2 6 00 0 3 o s o o o oF TEXT ///rrrore 5/>>oe /I /e)/rerL rrre er/r/r(r'or>>l /I/RC /rorm 34(/AS/ (17) could not be opened fast enough to cause header pressure to drop sufficiently for an auto-start to occur. The fact the flow would actually increase rapidly as a gate valve is opened was not considered . The swiftly increasing flow caused a temporary drop in header pressure below 75 psig.

ANALYSIS OF EVENT The FSAR states in Section 6 that the CCW system is used to cool the recirculation fluid during the residual heat removal recirculation phase. One of the three component cooling pumps is required to,provide the core and containment cooling function during recirculation. During this event, the A pump .was operating, and the B pump auto-started as designed. Based on the above, the health and safety of the public were not affected.

CORRECTIVE ACTIONS

1) Efforts to lower the CCW discharge pressure setpoint further in order to achieve a greater margin between operating and setpoint pressures have been initiated.

2) The Training Department will evaluate this event for incorporation into future operator training on the proper methods to fill and vent empty piping.

ADDITIONAL DETAILS Similar occurrences: LER s 251-87-02 and 251-87-11 reported previous CCW autostarts, however, neither of these auto-starts was due to the root causes identified in this LER.

NRC FORM 344A

$ 43)

P. X 14000, JUNO BEACH, FL 3340B.0420 npgEMBER 1 8 1987 L-87-521 10 CFR 50 '3 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555

'I Gentlemen:

Re: Turkey Point Unit 4 Docket No. 50-251 Reportable Event: 87-26 Date of Event: November 21, 1987 Component Cooling Water (CCW) Pump 4B Auto-Start Due to Unanticipated Drop In Header Pressure When CCW Pum 4C Was Returned to Service The attached Licensee Event Report (LER) is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.

Very truly yours, J+c~M-C. O. W y Execut'ice President COW/SDF/gp Attachment cc: Dr. J. Nelson Grace, Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Plant SDF/018. LER ,pP an FPL Group company

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