ML17285A914

LER 89-043-00:on 891121,HPCS Min Flow Valve Apparently Would Not Open Properly to Maintain Flow Through Pump When Sys Flow Was Secured.Caused by Equipment Failure.Failure Analysis to Be Performed Upon disassembly.W/891220 Ltr

ML17285A914
Person / Time
Site:	Columbia
Issue date:	12/20/1989
From:	Davison W, Powers C WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-043, LER-89-43, NUDOCS 9001020250
Download: ML17285A914 (9)

Text

ACCELERATED DISTRIBUTION DEMONSTIMTION SYRIA REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9001020250 DOC.DATE: 89/12/20 NOTARIZED: NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe. 05000397 AUTH. NAME AUTHOR AFFILIATION DAVISON,W.S. Washington Public Power Supply System POWERS,C.M. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 89-043-00:on 891120,inoperability of high pressure core spray steam caused by equipment failure.

W/8 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

'IZE NOTES:

RECIPIENT COPIES RECIPIENT 'OPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 SAMWORTH,R 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 ACRS WYLIE 1 1 AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DSP 2 2 DEDRO 1 1 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB9H3 1 1 NRR/DET/ESGB 8D 1 1 NRR/DLPQ/LHFB11 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB11 1 1 NRR/DREP/PRPBll 2 "2 NRR/DST/SELB 8D 1 - 1 NRR/DST/SICB 7E 1 1 NRR/DST/SPLB8D1 1 1 RRQD SRXB 8E 1 1 NUDOCS-ABSTRACT 1 1 EG 02 1 1 RES/DSIR/EIB 1 . 1 RGN5 FILE 01 1 1 EXTERNAL: EG&G WILLIAMS,S 4 4 L ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHY,G.A 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTEl CONTACT THE DOCUMENT CONTROL DESK, ROOM 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 38 ENCL 38

WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George fVashington Way ~ Richland, IVashington 99352 December'0, 1989 Docket No. 50-397 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NUCLEAR PLANT NO. 2 LICENSEE EVENT REPORT NO.89-043

Dear Sir:

Transmitted herewith is Licensee Event Report No.89-043 for the WNP-2 Plant.

This report is submitted in response to the report requirements of 10CFR50.73 and discusses the i tems of reportability, corrective action taken, and action-taken to preclude recurrence.

Very truly yours, 9AA .~.

C. M. Powers (tu'D 927M)

WNP-2 Plant Manager Cl4':1 g Enclosure Licensee Event Report No.89-043 cc: Mr. John B. Martin, NRC - Region V Mr. C. J . Bosted, NRC Site (M/D 901A)

INPO Records Center - Atlanta, GA Ms. Dottie Sherman, ANI Mr. D. L. Williams, BPA (fl/D .399) 7~E2 ~

l

NRC FOAM 360 V.S. NUCLEAR REGULATORY COMMISSION (669) APPROVED OMB NO. 31504104 EXPIRES: 4130I92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (F630), U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104). OFF ICE OF MANAGEMENTANO BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET MUMBER (2) PAGE 3 Washington Nuclear Plant - Unit 2 0 5 0 0 03 97>oF05 TITLE (4)

INOPERABILITY OF THE HIGH PRESSURE CORE SPRAY SYSTEM CAUSED BY EQUIPMENT FAILURE EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (6)

MONTH DAY YEAR YEAR SEQVENTIAL err'REVISION MONTH OAY YEAR FACILITYNAMES DOCKET NUMBER(S)

NUMBER 'C<9 NUMBER 0 5 0 0 0 2 8 9 9 0 4 0 0 2 0 9 0 5 0 0 0 THIS REPORT IS SUBMITTED PURSUANT T 0 THE RLQUIREMENTS OF 10 CFR ()I /Check one or more OI the Iollowinpi (11 OPERATING (9) 'ODE 20.402(b) 20.405(el 50.73(e l(2) Iiv) 73.71(B)

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LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE W. S. Davison, Compliance Engineer 509 37 7- 50 1 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IM THIS REPORT (13) EX 2726 CAUSE SYSTEM COMPONENT MANUFAC- MANUFAC EPORTABI.E TURER CAUSE SYSTEM COMPONENT TVREA TO NPADS

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B G VA 391 NO SUPPLEMENTAL REPORT EXPECTED (I ~ I MONTH OAY YEAR EXPECTED SUBMISSION DATE IISI YES IIIyeL comoiere EXPECTED S(IBMISSIOII DATEI X ABSTRACT ILimrt to (400 rotter I e., eporoeime rely IrReen tinpre torte ryoewritren linNI (16)

At 0524 hours on November 21, 1989, during performance of the High Pressure Core Spray (HPCS) system operabi1 i ty survei1 1 ance test, the HPCS minimum fl ow val ve (HPCS-V-12) apparently would not open properly to maintain minimum flow through the pump when sys tern flow was secured. The HPCS system was immedi ately decl ared inoperable and troubleshooting was initiated by the Plant operations staff. Initial troubleshooting showed that HPCS-V-12 was not mal functioning. The problem was isolated to HPCS-V-23, the test return valve to the suppression pool. It was found to be approximately ten percent open. This allowed sufficient flow to cause HPCS-V-12 to close. The LCO Action'equirement of technical specification 3.5.1 was imposed until the return of the HPCS system to operable status.

At 2150 hours0.0249 days <br />0.597 hours <br />0.00355 weeks <br />8.18075e-4 months <br /> that evening, as a result of continued. troubleshooting efforts, the test return valve to the Suppression Pool (HPCS-V-23), was found to be approximately 10 percent open, even though it was indicating closed in the control room. After attempts to manually close the valve failed, the manual block valve for the test return line (HPCS-V-64) was closed to isolate the faulty valve. At 2230 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.48515e-4 months <br />, after successful completion of the system operability surveillance, the HPCS system was declared operable.

The preliminary cause of this event is equipment failure in that HPCS-V-23, the test return line isolation to the Suppression Pool, was not able to be closed by motor operator or by hand to prevent undesired diversion of system flow from the injection NRC Form 366 (6691

NRC FORM 366A U.S NUCLEAR REGULATORY COMMISSION II (669) APPROVED 0M B NO. 3)500104 EXPIRES; 4/30/92

'ICENSEE EVEN PORT (LER) ESTI INFOR BURDEN PER RESPONSE TO COMPLY WTH THIS TION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P.530), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31504)104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503, FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEOVENTIAL REVISION YEAR g4 NUMSER NVMSER Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 8 9 043 0 0 0 2oF 0 5 TEXT /// more Speoe /4 rer/rrded, oee edd4/one///RC Form 36&4 3/ (IT)

II Abstract (contd. )

path. A. failure analysis of HPCS-V-23 will be performed after completion of disassembly and repair of the valve. There is no safety significance associated with this event. Because HPCS is a Hsingle train" system, its inoperability is reportable, even though at all times during the event the requirements of the WNP-2 Technical Specifications were complied with to maintain the plant within its design basis. The actions of the plant operators were prompt and correct. This event posed no threat=to the health and safety of the'ublic or plant personnel.

Plant Conditions a) Power Level - 100%

b) Plant trode - 1 Event Descri tion At 0524 hours0.00606 days <br />0.146 hours <br />8.664021e-4 weeks <br />1.99382e-4 months <br /> on November 21, 1989, during performance of the High Pressure Core Spray (HPCS) system operability surveillance test, the HPCS minimum flow valve (HPCS-V-12) apparently would not'pen to properly maintain minimum flow through the HPCS pump (HPCS-P-1) when system flow was secured. The HPCS system was immediately declared inoperable ana troubleshooting was initiated by the Plant operations staff. Initial troubleshooting was not able to discover the exact reason for the fault. Observed symptoms suggested that the flow indicating switch (HPCS-FIS-6) for the system flow input to the minimum flow valve control circuit might be faulty. At

.0910 hours0.0105 days <br />0.253 hours <br />0.0015 weeks <br />3.46255e-4 months <br /> the NRC Bethesda Operations Center was notified that the HPCS system was inoperable under the requirements of 10CFR50.72(b)(2)(iii) as a non-emergency four hour reportable event.

At approximately 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, troubleshooting of the HPCS system showed that the minimum flow valve (HPCS-V-12) functioned correctly and that 'the system was able to meet the design requirements for flow through the Condensate Storage Tank (CST) test return line (CST to CST flowpath). At 2150 hours0.0249 days <br />0.597 hours <br />0.00355 weeks <br />8.18075e-4 months <br /> that evening, as a result of continued troubleshooting efforts, the test return valve to the Suppression Pool (HPCS-V-23), was found to be approximately 10 percent open. The valve, in fact, indicated closed in the control room. After attempts to close the valve with the motor operator and manual operator failed, the manual block valve for the test return line (HPCS-V-64) was closed .to isolate the faulty valve from the remainder of the system. At 2230 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.48515e-4 months <br />, after successful completion of the system operability surveillance, the HPCS system was declared operable.

Immediate Corrective Action Plant operators responded in a timely manner to follow the requirements of plant procedures and technical specifications. They initially identified the condition, applied the restrictions of the LCO Action requirement of technical specification 3.5.1 and then followed up with appropriate action to obtain resolution. Initially, the problem manifested itself as failure of the minimum flow valve to open when system flow was apparently secured. In fact, flow through the pump was just above NRC Form 366A (64)9II

NRC FOAM 366A U.S. NUCLEAR REGULATORY COMMISSION (64(9( APPAOVED OMB NO, 31600(04 EXPIRES: 4/30/92 ESTI BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVEN PORT (LER) INFOA TION COLLECTION REOUEST: 50AI HRS. FORWARD COMMENTS REGARDING BUADEN ESTIMATE TO THE RECOADS TEXT CONTINUATION AND REPOATS MANAGEMENT BRANCH (F430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3'I500104I. OFFICE dF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME ((I DOCKET NUMBER (2l LER NUMBER (6) PAGE (3I YEAR SEOUENTIAL REVISION NUMBER NUMBER Mashin ton Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 4 3 0 0 3 o" 05 TEXT /// moro 4/Moo /4 ror/uirod. oro oddr'0'orro/NRC Form 366A2/ (IT) the required value for minimum flow, most probably due to the pathway provided by HPCS-V-23 not being completely closed. Flow was just sufficient to pick up flow switch HPCS-FIS-6, thus preventing the minimum flow valve from opening. Subsequent troubleshooting verified that the minimum flow valve, HPCS-V-12, and its associated flow indicating switch and controls were operating correctly. .The problem was then localized to the failure of HPCS-V-23 to completely close after it was discovered that the motor operator had stopped at the 90 percent closed position as a result of torque switch actuation.

Further Evaluation and Corrective Action A. Further Evaluation

1. This event is being reported per the requirement of 10CFR50.73(a)(2 )(v) as a "condition that alone could have prevented the fulfillment of the safety function of structures or systems that are needed to: (A) Shut down the reactor and maintain it in a safe shutdown condition; (B) Remove residual heat; (C ) Control the release of radioactive material; or (D) IIitigate the consequences of an accident." The inoperability of the HPCS system is a unique event at WNP-2. Unlike the other Emergency Core Cooling Systems, HPCS system inoperability is reportable even though all requirements of technical specification LCO action statements are being complied with.

This is so because it is a "single trai nH Emergency Core Cooling System and, as suet(, is reportable any time it is unable to perform its safety function when it is required to be able to do so by plant conditions.

2. The preliminary cause of this event is equipment failure in that HPCS-V-23, the test return line isolation to the Suppression Pool, was not able to be closed to prevent undesired diversion of system flow. The valve was initially unable to be closed either with the motor operator or by hand. The root cause of this event has not yet been determined due to the need to disassemble HPCS-V-23 in order to complete the investigation.

Technical evaluation by plant staff and communication with the valve

• manufacturer, Anchor-Darling Company, indicate that the cause of the failure could be vibration induced loosening of the disk nut. This type of failure would allow the valve disk to become misaligned with the disk guides/valve seat area and possibly result in the failure of the valve to attain the completely closed position. Similar failures of this type of valve have apparently occurred at other plants which exhibited the same types of symptoms. Any new substantive information which develops as a result of cor(rpletion of the failure analysis and root cause effort will be reported in a supplemental LER.

B. Further Corrective Action

1. The failure analysis and determination of the root cause of the HPCS-V-23 failure will be performed after completion of disassembly and repair of the valve.

NRC Form 366A (64(9I

NRC FORM 366A US. NUCLEAR REGULATORY COMMISSION (64)9) APPROVED 0MB NO. 31600104 EXPIRES) 4/30/92 ESTI BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVEN PORT ILER) INFORMATION COLLECTIDN REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P 530), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3)500104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON. DC 20503.

FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (6) PAGE 13)

YEAR )(I,II SEQUENTIAL NUMSSR ) cP REVISION NUMBER Washington Nuclear Plant - Unit 2 0 s ,0 0 0 3 9 7 8 9 043 0 0 0 4 OF 0 5 TEXT fff moro Sprco i4 reqIrfrod, Irso oddi tionol NRC Form 36643) (17)

Safety Si nificance There is no safety significance associated with this event. Preliminary evaluation

, of the failure shows that, with HPCS-Y-23 in approximately the 90 percent closed position, the HPCS system would have very closely approached its required design minimum flow rate (6350 gpm into the reactor vessel) under accident conditions.

Thus, the system, in i ts sl ightly degraded condition, woul d have contributed significantly to the successful response to' small diameter LOCA had it been called upon to do so. Also, failure of the HPCS system is within the bounds of the ECCS single failure criteria assumed in the FSAR safety analyses and does not prevent the ECCS from performing its safety function in response to a DBA.

At all times during the event, the requirements of the WNP-2 Technical Specifications (Section 3.5. 1) were complied with. The LCO action for this section requires ensuring the operability of the redundant ECCS Divisions 1 and 2 and the Reactor Core Isolation Cooling system while the HPCS system is inoperable (a maximum of 14 days is allowed). The entire period of inoperability was less than one day.

The actions of the plant operators were prompt and correct to ensure the plant was maintained within the bounds of the technical specifications and therefore within the bounds of the operational safety analysis.'ince no safety significance is associated with this event, it posed no threat to the health and safety of the public or plant personnel.

Similiar Events There were three instances of HPCS system inoperability that were evaluated as similar to this LER. LER 84-030 "Unscheduled Lockout of the High Pressure Core Spray Diesel Generator (HPCS DG)N documented an event during which a technician inadvertently locked out the HPCS Diesel Generator during surveillance activity by incorrect placement of an electrical j umper. The corrective action consisted of revising the procedure to add a caution note and to designate the proper contacts to be jumperea.

LER 85-022 UHPCS System Inoperable" documented an event during which plant personnel inadvertently disconnected system initiation logic while repairing two sheared off HPCS initiation status lamp sockets. Corrective action consisted of notifying plant operations,'aintenance and technical personnel to place additional reliance on electrical wiring diagrams, connection diagrams and approved vendor manuals when appropriate.

LER 89-030 "High Pressure Core Spray System Inoperable Caused by Suppression Pool Pump Suction Yalve Failure Due to Motor Operator Manufacturing Error" documented an event, during which the HPCS system was declared inoperable due to failure of the suppression pool pump suction valve motor operator during performance of the operability surveillance. The corrective actions associated with this LER consisted of: checking other valve motor operators during the next refueling outage, revising the plant maintenance procedures to add instructions for inspection of the motor operators, adding precautions to plant procedures regarding disposition of valves found difficult to operate, and initiation of a 10CFR21 report.

NRC Form 366A (569)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (64) 9) APPROVED OMB NO. 31504))04 EXPIRES; 4/30/92 LICENSEE EVEN PORT ILERI ESTI~ BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REOUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P630). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31504')04), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEOVENTIAL re> REYISION NUMBER h'+~ NUMBER Washington Nuclear Pl ant - Unit 2 0 s 0 0 0 3 9 7. 8 9 043 0 0 0 SoF 0 5 TEXT N more erseee /S rehleh'red, ose edCheone///RC Form 3664'4/ (ll)

EI IS Information Text Reference EIIS Reference

~Sstem ~corn onent HPCS System BG HPCS-V-12 BG V HPCS-V-23 BG V HPCS-P-1 BG P HPCS-FIS-6 BG FIS Suppression Pool BT HPCS-V-64 BG V ECCS Division 1 BM ECCS Division 2 BM RCIC System BM Condensate Storage Tank KA TK NRC Form 366A (64)9)

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