05000298/LER-1994-001, :on 940119,HPCI Pump Min Flow Bypass Valve Unexpectedly Opened During Surviellance Testing While Pump Discharge Valve Being Opened Due to Actuation of Pump Discharge Pressure Switch.Valve Closed

:on 940119,HPCI Pump Min Flow Bypass Valve Unexpectedly Opened During Surviellance Testing While Pump Discharge Valve Being Opened Due to Actuation of Pump Discharge Pressure Switch.Valve Closed

ML20063K681
Person / Time
Site:	Cooper
Issue date:	02/18/1994
From:	Gardner R, Reeves D NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CNSS948060, LER-94-001, LER-94-1, NUDOCS 9403020028
Download: ML20063K681 (5)

LER-1994-001, on 940119,HPCI Pump Min Flow Bypass Valve Unexpectedly Opened During Surviellance Testing While Pump Discharge Valve Being Opened Due to Actuation of Pump Discharge Pressure Switch.Valve Closed

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation
2981994001R00 - NRC Website

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COOPER NUCLEAR STATION j

Nebraska Public Power District

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CNSS948060 1

1 February 18, 1994 l

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U.S. Nuclear Regulatory Commission Document Control Desk j

1-Washington, D.C.

20555

Dear Sir:

Cooper Nuclear Station Licensee Event Report 94-001, is forwarded as an 3

attachment to this letter.

f Sincerely, huyl peg R. L. Gardner

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Plant Manager RLG/nc Attachment i

cc:

L. J. Callan G. R. Horn j

J. M. Meacham i

R. E. Wilbur V. L. Wolstenholm D. A. Whitman INPO Records Center i

NRC Resident Inspector l

R. J. Singer CNS Training CNS Quality Assurance CNS Regulatory Compliance Specialist 220127

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NQC Form 384 U.S. NUCLECM GEOULQTORY COMMIS$10N aPPROVf D OMB NO 3M0 0104 LICENSEE EVENT REPORT (LER)

EXPIRES 8/3900 FACILITY NAME (11 DOCKET NUMBER (21 FAGE 638 Cooner Nuclear Station 0 l5l0l0l01219 18 1 lOFl 014 UrYe'dhectedOpeningoftheHighPressureCoolant Injection Pump Minimum Flow Valve, an ESF Cnsp on e n t.. Durine Surveillance Test ine Due t o Ac t uat ion of the Pump Discharte Pressure Switch EVENT DATE 161 LER NUMBER 16)

REPORT DATE (7)

OTHER FACILITIES INVOLVED ISI MONTH DAY YEAR YEAR SEQ AL g is MONTH DAY YEAR P ACILITY N AMES DOCKET NUMBER (S) p 0l5[0[0l0) l l O l1 9l4 0 l0 0 l2 1 lB 9l4 0 l5l0 l0 1 0; [ l 1 9 9

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THIS REPORT 88 $USMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 9: tchec4 ene or more of rae folio ympf 1111 OPE R ATING MODE (S)

N 20.402(mi

20. 0stei 60.72i.H2io i 73.rismi 2

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60.73i.H2H.at OTHER rspectfy /s Abstract 20 406tsH1Hd4 60.73teH2Hij 60.73(sH2HvisiHA)

J66Al 20.406ieH1Hivl 60.73teH2 Hill 60.73tsH2HvillHB) 20.406(sHt Hvi 60.734aH2Hui) 60.73teH2Hal LICENSEE CONTACT FOR THl3 LER (12)

NAME TELEPHONE NUMBER ARE A CODE Donald L.

Reeves. Jr.

4 p 12 8 l 215 l -13 l 81111 COMPLETE ONE LINE FOR EACH COMPONENT F AILURE DESCRiaED IN THis REPORT (13)

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SYSTEM COMPONENT

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On January 19, 1994, at approximately 2:15 am, with the plant in full power operation, HPCI-MOV-M025, the High Pressure Coolant Injection (HPCI) pump minimum flow bypass valve, unexpectedly opened during surveillance testing while the pump discharge valve was being opened. An initial assessment indicated that the cause of the actuation was due to pressure fluctuations caused by the pressure maintenance system. HPCI-MOV-M025 was closed, system parameters were verified to be normal, and the surveillance test was continued without any further problems.

An engineering evaluation concluded that operation of the valve could occur when HPCI-MOV-M020, the pump discharge valve is re-opened.

Discussions with Control Room Operators revealed that occasionally, the valve had automatically opened during past valve operability tests.

Such actuation (s) had not been reported due to lack of understanding of the extent of ESF component level reporting requirements. However, due to increased emphasis on a questioning attitude and attention to detail, this actuation was documented as a discrepancy and subsequently determined to be

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reportable.

The root cause of the problem is design, since unnecessary actuations of the minimum flow valve should not occur.

A procedure change was made to the HPCI valve operability surveillance test to ensure operator awareness that automatic operation of the minimum flow valve could occur when HPCI-MOV-M020 is re-opened. A similar change has been made to the RCIC surveillance test.

An evaluation of the HPCI and RCIC Pump Discharge Pressure switch configurations and setpoints will be made and changes implemented, if practical, to eliminate the unnecessary cycling of the minimum flow valves. To ensure operator awareness of reporting requirements, licensed Operators will be apprised of ESF component level reporting requirements.

"s"e*3I"" "*

l

.U.S. NUCLEAR REGULATORY CODMISSION APPROVED BY OMB No. 3150-0104 (5 92)

EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING BURDEN ESilMATE TO LICENSEE EVENT REPORT (LER)

THE INFORMATION AND RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MNsB m 4), u.s. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555 0001, AND TO THE PAPERWORK REDUCTION ~ PROJECT (3150 0104),

OFFICE OF l

MANAGEMENT AND BUDGET d ASHINGTON. DC 20503.

I FACILITY NAME (1)

DOCKET NtNBER (2)

LFR M IBER (6?

PA& (3)

SEQUENTIAL REVISION YEAR COOPER NUCLEAR STATION 05000298 94 00 2 OF 2 001 --

TEXT fif more space is reavired, use additional copies of NRC Form 366A) (17) l A.

Event Description

On January 19, 1994, at approximately 2:15 am, HPCI-MOV-M025, the High l

Pressure Coolant Injection (HPCI) pump minimum flow bypass valve, unexpectedly l

opened during surveillance testing when HPCI-MOV-M020, the pump discharge valve, was being opened. HPCI-MOV-M025 automatically opens if HPCI System Flow is <485 gpm and either a HPCI Initiation signal is received or pump discharge pressure is >125 psig. An initial assessment indicated that the most likely cause of the unexpected actuation was due to pressure fluctuations i

caused by the pressure maintenance system. HPCI-MOV-M025 was closed, system parameters were verified to be normal, and the surveillance test was continued without any further problems.

B.

Plant Status The plant was in operation at full power, conducting monthly surveillance testing of the HPCI System Motor Operated Valves (MOVs).

C.

Dasis for Report The unexpected, autorcatic actuation of HPCI-MOV-M025, an ESF component, during surveillance testing on January 19, is reportable in accordance with 10CFR50.73(a)(2)(iv).

Thfs condition was determined to be reportable at approximately 1:15 pm on January 20, the day af ter test performance, following a review of the surveillance test.

D.

Cause

An engineering evaluation concluded that operation of the minimum flow valve could occur when HPCI-MOV-M020, the normally open pump discharge valve, is re-opened after being closed during the valve operability surveillance test.

In order to cycle the HPCI Injection valve, HPCI-MOV M019, HPCI MOV-M020 is closed first, then HPCI-MOV-M019 is cycled open and closed.

Pressure measurements taken on January 21 revealed that upon closure of the pump discharge valve, pressure between it and the injection valve increased from 70 psig to 100 psig as the valve was driven into its seat.

Cycling the injection valve resulted in increasing the pressure between the valves to 150 psig; an immediate increase from 100 to 140 psig upon valve operation in the open direction and an increase of 10 more psig as the valve was driven into its seat.

Due to the fact that there was no gradual upward trend in pressure when the injection valve was open, engineering concluded that the injection check valve, HPCI-CV-29CV, was essentially leak tight. Upon actuation of HPCI-MOV-M020 to the open position, a pressure wave was created which was of sufficient magnitude to cause the HPCI Pump High Pressure Discharge switch, HPCI-PS-85, to actuate at 125 psig. Actuation of this switch caused HPCI-MOV-M025 to automatically open.

MC FORM 366A (5 92)

- ~ - - -

WC FORM

• 3664 U.S. NUCLEAR REGULATORY CGO4ISS10N APPROVED BY G W No. 3150-0104 (5 C2)

EXPIRES 5/31/95 l

ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH j

THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

j FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO LICENSEE EVENT REPORT (LER)

THE INFORMATION AND RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555 0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150 0104),

OFFICE OF MANAGEMENT AND BUDGET WASHINGTON, DC 20503.

FACILITY NAM (1)

DOCKET M BER p)

HR M k (6?

NW SEQUENTIAL REVISION YEAR NUMBER NUMBER COOPER NUCLEAR STATION 05000298 94 00 3 OF 3

-- 0 01 --

TEXT (If more space is reautred. use additional cooles of NRC Form 366A) (IT)i Discussions with Control Roem Operators revealed that the minimum flow valve had occasionally opened aut.omatically during past MOV operability tests.

Such actuation (s) had not been reported due to lack of understanding of the essential ESF component level reporting requirements. However, due to increased emphasis on a questioning attitude and attention to detail, this actuation was documented as a discrepancy and subsequently determined to be reportable. The root cause of the problem is design, since unnecessary actuations of the minimum flow valve should not occur.

E.

Safety Sinnificance HPCI-MOV-M025 is provided for pump protection. Upon system initiation, the valve opens and remains open until system flow reaches 800 gpm, at which point the valve automatically closes.

The valve will reopen at 485 gpm on decreasing flow.

Flow through the minimum flow line is returned to the Suppression Pool.

Following the unexpected actuation of the valve to the open position, the licensed Control Room Operator reclosed the valve. The valve operated properly and remained closed. The surveillance test was resumed and operation of the minimum flow valve was checked in later steps of the test procedure.

Its operation was determined to be satisfactory.

Consequently, the unexpected actuation of the valve would not have affected system operability.

F.

Safety Implications l

Due to the fact that valve operability was determined to be satisfactory, this event was of little safety consequence. Had valve operability been affected, the most significant initial plant condition would have been full power operation, i

G.

Corrective Action

As discussed in Section D, Cause, an engineering evaluation of the event revealed that while actuation of the minimum flow valve may not occur every time HPCI-MOV-M020 is reopened during the surveillance test, data taken during the investigation indicates that it should not be unexpected because a pressure increase may be created that is approximately the setpoint of the pressure switch.

Engineering also advised that due to the similarity of the l

logic circuitry for the Reactor Core Isolation Cooling (RCIC) minimum flow l

N3C FORM 366A (5-92) r l

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4 MltC FC2M 366A U.S. NUCLEAR REGJLATORY COBOIISSIC APPRoWED BY 01W No. 3150-0104 (5 g2)

EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THl3 INFORMATION COLLECTION REQUEST: 50.0 HRS.

+

FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO LICENSEE EVENT REPORT (LER)

THE INFoRMATION AND RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MN88 7714), U.S. NUCLEAR REGUtATORY COMMIS$10N, 4

WASHINGTON, DC 20555 0001 AND To THE PAFERWORK REDUCTION PROJECT (31EO0104),

OFFICE OF l

i MANAGEMENT AND BU0CET. WASHINGTON. DC 20503.

FACILITY NAME (1)

DOCKET MIAIBER (2)

LER NLOWER (6l' PAGE (4)

SEQUENTIAL REVISION YEAR COOPER NUCLEAR STATION 05000298 94 00 4 OF 4

-- 0 01 --

i l

TEXT (if more space is reautred, use additional copies of NRC Form 366A) (17)valve, its actuation during valve operability surveillance testing also should

~

l not be unexpected. Discussions with Control Room Operators revealed that minimum flow valve actuations had occurred in the past but had not been considered test discrepancies since the basis for their operation was understood.

To ensure operator awareness of the potential actuation, a procedure change was made to the HPCI valve operability surveillance test, indicating that automatic operation of the minimum flow valve could occur when HPCI-MOV M020 was re-opened. A similar change has been made to the RCIC valve operability surveillance test. An evaluation of the HPCI and RCIC Pump Discharge Pressure switch configurations and setpoints will be performed.

If practical, charges will be implemented to eliminate the occasional unnecessary cycling of tha minimum flow valves.

Additionally, to ensure operator awareness of reporting requirements, licensed Operators will be apprised of ESF component level reporting requirements and i

that unplanned ESF component actuations are subject to the notification and reporting requirements prescribed in 10CFR50.72 and 10CFR50.73.

H.

Similar Events

None N3C FORM 366A (5 92)