ML20005G166

LER 89-045-00:on 891212,Div I Standby Svc Water Pumps Received Automatic Start Signal Due to Spurious Low Svc Water Pressure Signal When Normal Svc Water Pump Secured. Signal Cleared & Sys Restored to Normal lineup.W/900110 Ltr

ML20005G166
Person / Time
Site:	River Bend
Issue date:	01/10/1990
From:	Booker J, England L GULF STATES UTILITIES CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-045, LER-89-45, RBG-32076, NUDOCS 9001180228
Download: ML20005G166 (4)

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GULF STATES UTILITIES COMPANY SN(P blNp $teTiON PDST OfifCf l' M 220 LI If AN:IfdlLLI. LOJG8ANA 70?7b Asal A (()D( bN 0% fM4 lb16 lit bl January 10, 1990 RBG- 32076 File Nos. G9.5, G9.25.1.3 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Gentlemen:

River Bend Station - Unit 1 Docket No. 50-458 Please find enclosed Licensee Event Report No.89-045 for River Bend Station - Unit 1. This report is being submitted pursuant to 10CFR50.73.

Sincerely, bb ,

p g J. E. Booker Manager River Bend Oversight River Bend Nuclear Group to fgJ kp l JEB/TFP/RGW/DCH/JEV/pg ec: U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000  :

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NRC Resident Inspector P.O. Box 1051 St. Francisville, LA 70775 INP0 Records Center l 1100 Circle 75 Parkway l Atlanta, GA 30339-3064 l

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On December 12. 1989 at 1205 with the unit operating at 100 percent power in Operational Condition 1. the Division I standby service water pumps received an automatic start signal due to a spurious low service water pressure signal when the normal service water pump ISWP-PIA was secured. The signal was cleared and Division I standby service water system was restored to a normal lineup. This event is reported per 10CFR50.73 (a) (2) (iv) as an event that resulted in an engineered safety feature (ESF) actuation.

This event resulted in the automatic initiation of both of the Division I standby service water (SSW) pumps which were not required since two of the normal service water pumps were operating. The SSW t

initiation performed as designed and therefore had no effect on the j health and safety of the public.  !

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REPORTED CONDITION ]

1 On December 12, 1989 at 1205 with the unit operating at 100 percent  ;

power in Operational Condition 1, the Division I standby service water pumps (*P*) received an automatic start signal due to a spurious low .

service water pressure signal when the normal service water pump ISWP-PIA (*P*) was standby service secured.

water The si system (*BI*)gnalwas was cleared restored to aand normalDivision lineup.I '

This event is reported per 10CFR50.73 (a) (2) (iv) as an event that resulted in an engineered safety feature (ESF) actuation.

13]ESIIGATIO3 )

Instrumention and Controls (I&C) personnel were performing a preventive maintenance task (PS?8890) to check the calibration of the normal service water supply pressure instrument, ISWP-PS121. The normal service water pumps, ISWP-PIB and ISWP-PIC were in operation '

during this calibration. The normal service water pump, ISWP-PIA was locked out to prevent it from automatically starting. Upon completion of the procedure, ISWP-PIA was taken out of lockout, which caused the pump to automatically start. The system pressure with three normal.

service water pumps in operation was approximately 115 PSIG. The operating crew judged that it was not necessary to lock out the standby service water system when securing ISWP-PIA since the

, actuation setpoint of the standby service water (SSW) system is 76 PSIG, approximately 40 PSIG below the system pressure at that time.

When ISWP-PIA was secured, a spurious low service water pressure signal was received by the Division I standby service water system which caused the automatic start of both SSW pumps, per design. The ,

low pressure " seal in" was reset immediately and the standby service i water system was restored to a normal lineup. The lowest pressure visually observed during this event was approximately 100 PSIG.

Although this is well above the 76 PSIG needed to automatically start the standby service water system, apparently a short term pressure oscillation caused the initiation of the SSW pumps.

A similar event was reported in LER 87-031. In this case STP-200-0603, " Division III Remote Shutdown System Control Circuit 1 Operability Test" was in progress. A low service water pressure ,

signal followed the securing of standby service water pump, ISWP*P20.

This pump restarted upon returning control to the main control room i due to the " sealed in" low pressure start signal. The corrective action included the revision of the STP to include reset of all divisions of SSW low pressure initiation logic prior to returning the -

transfer switch to the normal position and upgrading the procedure to ensure that all " seal in" initiation signals for the SSW system are ,

reset prior to returning equipment control to the main' control room. i g.... . . . . o..... . ...

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& n - . - s. mc = manwim i CORRECTIVE ACTION The procedure $0P-0018 " Normal Service Water System" has been revised to incorporate steps on how to reset an automatic start signal when

" sealed in" on the normal service water pumps prior to taking a pump out of lock out. The applicable preventive maintenance task will be revised by January 31, 1990 to refer the operator to SOP-0018 upon completion to assure that the automatic initiation signal on the normal service water pumps will be reset per the procedure. In '

addition, a design modification (modification request (MR) 86-1542) is being considered to provide a time delay into the automatic initiation logic for the standby service water system in order to eliminate the problem.

_ SAFETY ASSESSMENT This event resulted in the automatic initiation of'both of the '

Division I standby service water (SSW) pumps which were not required since two of the normal service water pumps were operating. The SSW initiation performed as designed and therefore had no effect on the health and safety of the public.

NOTE: Energy Industry Identification System Codes are identified in the text as (*XX*).

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