ML17285B110

LER 90-004-00:on 900208,HPCS Diesel Generator Declared Inoperable for Performance of Corrective Maint to Investigate Previous Trip of Output Circuit Breaker Which Occurred on 900204.New Droop Switch installed.W/900309 Ltr

ML17285B110
Person / Time
Site:	Columbia
Issue date:	03/09/1990
From:	Davison W, Powers C WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-004, LER-90-4, NUDOCS 9003220086
Download: ML17285B110 (8)

Text

ACCELERATED DISTRIBUTION DEMON'~TINCTION SYSTEM

~ . O REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9003220086 DOC.DATE: 90/03/09 NOTARIZED: NO DOCKET PT 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 90-004-00:on 900208,inoperability of HPCS sys caused by equipment failure. ltr.

W/9 DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 SAMWORTH,R 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 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/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB 7E 1 1 NR PLB8D1 1 1 NRR/DST/SRXB 8E 1 1 REG FILE 02 1 1 RES/DSIR/EIB ' 1 FILE 01 1 1 EXTERNAL: EGGG 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" RECIPIENIS:

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ai WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 99352 Harch 9, 1990 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.90-004

Dear Sir:

Transmitted herewith is Licensee Event Report No.90-004 For the WNP-2 Plant.

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

Very truly yours, Q1@Gcu 4td C. H. Powers (H/0 927M)

WNP-2 Plant Manager WSD:lr

Enclosure:

Licensee Event Report No.90-004 cc: Hr. John B. Hartin, NRC Region V Hr. C. J. Bosted, NRC Site (H/0 901A)

INPO Records Center Atlanta, GA Hs. Dottie Sherman, ANI Hr. D. L. Williams, BPA (H/D 399)

)0 9003220086 900309 PDR ADOCK 05000397 8 PDC I

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO,31504104 (64)9)

EXPIRES: 4/30/92 BURDEN PER RESPONSE TO COMPLY WTH THIS

'STIMATED INFORMATION COLLECTION REOUESTt 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (Ppe30), U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PRO/ECT (31500104), OFFICE OF MANAGEMENTANO BUDGET. WASHINGTON, DC 20503 DOCKET NUMBER l2) PA E FACILITY NAME (1)

Washington Nuclear Plant - Unit 2 0 s 0 0 0 39 >oF05 nopera ) i ress r . r Equipment Failure - Failed Diesel Generator Governor Mode Switch EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (6)

MONTH DAY YEAR YEAR P)r.'BDUBNTtAL "rA RcvrsrON OAY YEAR FACILITYNAMES DOCKET NUMBER(SI NUMBER ':AS NUMBER 0 5 0 0 0 02 89 0 9 0 00 4 000 3 0 9 9 0 0 5 0 0 0 THIS REPORT IS SUBMITTED PURSUANT T 0 THE RLOUIREMENTS OF 10 CFR (): /Check one or more of the follows'np/ (11 OPERATING MODE (9) 20.402(B) 20A05(c) 50.73(e)(1)(ivl 73.7101)

POWER 20.405 (c l(1) ill 50.36(el)1) 50.73( ~ ) l2) Iv) 73.71(c)

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MANUFAG EPORTABLE MANUFAC EPORTABLE 5$

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SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED SUBMISSION DATE (15)

YES /lf yer, complete EXPECTED St/84//SSIDII DATE/ NO ABSTRACT It.lmit to /400 tpeceA /.e., epproeimeteiy fifteen tlnpie rpece typewritten liner/ (16)

On February 8, 1990, at 0518 hours0.006 days <br />0.144 hours <br />8.564815e-4 weeks <br />1.97099e-4 months <br />, the High Pressure Core Spray (HPCS) Diesel Generator was declared inoperable for performance of corrective maintenance to investigate a previous trip of the output circuit breaker which occurred on February 4, 1990. The HPCS System was then declared inoperable and the LCO Action requirements of WNP-2 Technical Specification sections 3/4. 5.1 "Emergency Core Cool-ing Systems" and 3/4.8. 1.1 "Electrical Power Systems" were entered. Troubleshooting of the speed governor was performed -to investigate the previous trip of the output circuit breaker. During troubleshooting, the "droop switch" for the diesel engine speed governor was discovered to be faulty and to require replacement. On February 10, 1990, at 0032 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />, after completion of a temporary modification to bypass the droop switch and post repair surveillance testing, the HPCS Diesel Generator and the HPCS System were declared operable. A new droop switch will be purchased and installed in the HPCS Diesel Generator governor control circuitry. No safety significance is associated with this event, it posed no threat to the health and safety of the public or plant personnel.

NRC Form 366 (669)

NRC FORM SeeA (64)9) t LICENSEE EVENT REPORT ILER)

TEXT CONTINUATION US NUCLEAR REGULATORY COMMISSION E

APPROVED OMB NO. 3(504)I04 EXPIRES; 4/30/92 IMATED BUADEN PEA RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPOATS MANAGEMENT BRANCH (P4)30). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) I.ER NUMBER (6) PAGE 13)

YEAR @P.

SSOVENTIAL +jg

'?J nsvIsloN Bn NVMBBn NUM 0 5 0 0 0 OF N lea P TEXT (Ilmom BPece Ie PN)o(eNL IIee JdIOonei NRC FomI 3664'4) () Tl Plant Conditions a) Plant Mode - 1 (Power Operation) b) Power Level - 93%

Event Descri tion On February 4, 1990, at 0117 hours0.00135 days <br />0.0325 hours <br />1.934524e-4 weeks <br />4.45185e-5 months <br />, the High Pressure Core Spray (HPCS) System Diesel Generator output circuit breaker 4-DG3 tripped during performance of the Technical Specification operability surveillance test. When the generator was synchronized with the Division Three 4160 volt emergency electrical bus (SM-4), the generator rapidly loaded to greater than-3000 KW. Efforts by Plant Operators to control the electrical load were followed by a trip of circuit breaker 4-DG3. At 0225 hours0.0026 days <br />0.0625 hours <br />3.720238e-4 weeks <br />8.56125e-5 months <br />, after resetting the 4-DG3 reverse power trip protective relay and completing an evaluation of the circumstances associated with the trip, the operability surveillance was successfully completed without incident. After discussion with Plant technical and maintenance personnel, a troubleshooting plan to investigate for possible equipment fault was written and initiated.

On February 8, 1990, at 0518 hours0.006 days <br />0.144 hours <br />8.564815e-4 weeks <br />1.97099e-4 months <br />, the High Pressure Core Spray (HPCS) Diesel Generator was declared inoperable for performance of corrective maintenance in the form of troubleshooting the electronic governor system. The HPCS System was then declared inoperable and the LCO Action requirements of WNP-2 Technical Specification sections 3/4.5.1 "Emergency Core Cooling Systems" and 3/4.8.1.1 "Electrical Power Systems" were entered and complied with. At 1209 hours0.014 days <br />0.336 hours <br />0.002 weeks <br />4.600245e-4 months <br />, as a result of troubleshooting efforts, an equipment failure was identified. The "droop switch" for the diesel speed governor was discovered to be faulty and to require replacement. The failure of this switch would cause the observed governor response and render the operator actions to control synchronized loading ineffective.

Immediate Corrective Action Repair planning efforts were immediately started by Plant maintenance and technical staff personnel. Temporary repair was accomplished by bypassing the speed governor mode selector (droop switch) such that the Diesel Generator will be continuously maintained in the droop mode of operation. On February 1 0, 1990, at 0032 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />, after completion of post repair surveillance testing, the HPCS Diesel Generator and the HPCS System were declared operable.

NRC Form 366A (669)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31500104 (64)9) E XP IR E S: 4/30/92 ESTIMATED BURDEN PFR RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LERI INFORMATION 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, OC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31504104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, OC 20503.

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

SEQUENTIAL REVISION NUMSER NUM ER Washington Nuclear Plant - Unit 2 0 s 0 0 0 3 9 7 9 0 0 0 4 0 0 03 OF 0 5 TEXT ///moro Epoco /1 r)I)used, Irro 4//I/ooo/HRC Forrrr 3//SAB/ (17)

Further Evaluation and Corrective Action A. Further Evaluation Since the HPCS System is considered to be a single-train system that performs a safety function, inoperability of the system is reportable per the requirements of 10CFR50. 72(b)(2)(iii) and 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 ... shut down the reactor and maintain it in a safe shutdown condition ... or mitigate the accident."

consequences of an 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 classified as a Hsingle-trai Emergency Core Cooling System.

nR As such, its inoperability is reportable any time it is required to be able to perform its safety function by plant conditions.

2. There were no structures, components or systems that were inoperable at the start of this event that contributed to the event.

3. The cause of the reverse power trip of the 4-DG3 circuit breaker was equipment failure in the form of a faulty speed governor mode selector switch (droop switch) which caused electrical load instability while the unit was synchronized with the utility grid. This resulted in the inoperability of the HPCS Diesel Generator for troubleshooting and the inoperability of the HPCS System during the repair task.

4~ An engineering evaluation was performed which verified that the nominal reduction in generator output, while operating in the droop mode on an isolated bus, was acceptable.

5. The reverse power trip of the HPCS DG was evaluated as a non-valid failure per NRC Regulatory Guide 1.108, since this function is bypassed during accident conditions and is part of the generator synchronizing circuitry.

B. Fur ther Corrective Action A new droop switch will be procured and installed in the HPCS Diesel Generator governor control circuitry to restore the design configuration of the diesel engine speed governor control circuitry to normal.

NRC Form 366A (689)

NRC FORM 366A US. NUCLEAR REGULATORY COMMISSION APPAOVED OMB NO. 3)600104 (64)9)

EXPIRES: 4/30/92 ATED BUADEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVE REPORT (LER) INFORMATION COLLECTION REOUESTI 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECOADS TEXT CONTINUATION AND REPOATS MANAGEMENT BRANCH IP430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1ME PAPERWORK REDUCTION PROJECT (31504104). OFFICE OF MANAGEMENT AND 6UDG ET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER l2) LER NUMBER (6) PAGE (3)

SEOVENTIAL gY+i REVISION NVMSSR 44 NVMSSR Washin ton Nuclear TEXT ///msm 4/JPPP H IPSSPN/, PPP 4//PPRS/HRC Plant - Unit

%%dmI 356A'4/ ()7) 2 0500039790 0 0 4 0 0 04 OF 0 5 Safet Si nificance This event has no safety significance. At all times during'he event, the requirements of the WNP-2 Technical Specifications were complied with. The operability of the redundant ECCS Divisions 1 and 2 and the Reactor Core Isolation Cooling (RCIC) System were assured while the HPCS system was inoperable (a maximum of 14 days is allowed). The entire period of inoperability was less than two days.

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. Since no safety significance is associated with this event, public or plant personnel.

it posed no threat to the health and safety of the Similar Events There were four instances of HPCS system inoperability that were evaluated as,

'ER

" similar to this LER.84-030, "Unscheduled Lockout of, the High Pressure Core Spray Diesel Generator (HPCS-DG)", documented an event during which a technician inadvertently locked out the HPCS Diesel Generator during surveillance activity by incorrect placement of an electrical jumper. The corrective action consisted of revising the procedure to add a caution note and to designate the proper contacts to be jumpered.

LER 85-022, RHPCS 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, maintenance 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 Su~pression Pool Pump Suction Valve 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.

LER 89-043, " Inoperability of the High Pressur e Core Spray System Caused by Equipment Failure", documented an event during which the test return valve to the suppression pool, HPCS-V-23, was found to be unable to close beyond the ten percent open position causing apparent malfunction of the minimum flow valve, HPCS-V-12.

The corrective actions associated with this LER consisted of completion of failure analysis and determination of the root cause of the HPCS-V-23 failure after repair of the valve.

N AC Form 366A (669)

NRC FORM 366A (64())

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LICENSEE EVENT REPORT HLER)

TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO, 31504104 EXPIRES: r/30/92 ES I...ATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REOUESTI 50A) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON. DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31504104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

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

SSOUSNTIAL REVISION YEAR NUMSSR NUMSSR Washin ton Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 9 0 0 0 4 00 05 OF 0 5 TEXT /// mar sooro /r nqo9rd, II'I/d/0'one//YRC Form 3664'r/ (12)

EIIS Information Text Reference EIIS Reference p

HPCS Diesel Generator EB DG High Pressure Core Spray System BG Circuit Breaker 4-DG3 EB 52 SM-4 EB Electronic Governor EB 65 Droop Switch EB SEL RCIC BN Status Lamp Sockets BG IL Suppression Pool Pump Suction Valve Motor Operator BG MO HPCS-V-23 BG V HPCS-V-12 BG V NRC Form 366A (689)