ML17279A621

LER 87-025-01:on 870808,ESF Isolations & Actuations Occurred.Caused by Spurious Trip of Breaker Due to Oxide Formation on Coil Plunger End of Undervoltage Relay Coil. Breakers replaced.W/871120 Ltr

ML17279A621
Person / Time
Site:	Columbia
Issue date:	11/20/1987
From:	Powers C, Washington S WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
LER-87-025, LER-87-25, NUDOCS 8711250222
Download: ML17279A621 (11)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR 871 1250222 DOC. DATE: 87/11/20 NOTARIZED: NO DOCKET 0 FAC IL: 50-3'P7 WPPSS Nuclear Progecti Unit 2i Washington Public Poee 05000397 AUTH. NAME AUTHOR AFFILIATION WASHINGTON' L. -

Washing ton Pub lie Poeer Supp lg System POWERS'. M. Washington Public Power Supply System REC IP. NAME RECIPIENT AFFILIATION

SUBJECT:

LER 87-025-01: on 870808 ESF isolations 5 actuations occurred. Caused bg spurious trip of breaker due to oxide formation on coil p lunger end of undervoltage relay coil.

Breakers replaced. W/871120 ltr.

DISTRIBUTION CODE: IE22D COPIES RECEIVED: LTR J ENCL J SIZE:

TITLE: 50. 73 Licensee Event Report (LER) i Incident Rpti etc.

NOTES:

REC IP IENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 SAMWORTHi R 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 AEOD/DOA 1 1 AEOD/DSP/NAS 1 1 AEOD/DSP/ROAB 2 2 AEOD/DSP/TPAB 1 1 ARM/DCTS/DAB 1 1 DEDRO 1 1 NRR/DEST/ADS 1 0 NRR/DEBT/CEB 1 1 NRR/DEST/ELB 1 1 NRR/DEBT/ I CSB 1 1 NRR/DEST/MEB 1 1 NRR/DEST/MTB 1 1 NRR/DEST/PSB 1 1 NRR/DEST/RSB 1 1 NRR/DEST/SQB 1 1 NRR/DLPG/HFB 1 1 NRR/DLPG/GAB NRR/DOE*/EAB 1 1 NRR/DREP/RAB 1 NRR/DREP/RPB 2 2

$ 4% IB 1 NRR/PMAS/ILRB 1 1 REQ FILE 02 1 RES DEPY QI 1 TELFORDi J 1 RES/DE/EIB 1 1 RGN5 FILE 01 1 1 EXTERNAL: EGSQ GROHi M 5 5 H ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 NSIC HARRIS> J 1 1 . NSIC MAYSi Q 1 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR . 45 ENCL 44

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NRC Form 388 U.S. NUCLEAA REGULATOAY COMMISSION (BSS)

APPROVED OMB NO. 3)600104 EXPIRES: 8/31/88 LICENSEE EVENT REPORT (LER)

FACILITY NAME (1) DOCKET NUMBER (2) PACE 3 Washin ton Nuclear Plant - Unit 2 0 5 0 0 0 397 ioF 04 TITLE(" Engineere a ety ea ure so a ions an c ua ions ause y Reactor (7rotection System Equipment Failure EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACIUTIES INVOLVED (8)

MONTH OAY YEAR YEAR SEOUSNTIAI. grg REVISION MONTH OAY YEAR FACILITYNAMES DOCKET NUMBER(3)

NUMBER 0 5 0 0 0 080 88 7 8 7 0 2 5 0 1 1 120 87 0 5 0 0 0 OPERATINO THIS REPORT IS SUBMITTED PURSUANT T 0 THE REQUIREMENTS OF 10 cFR (I; (Coach one or more of the follorylnei (11 MODE (Sl 20A02(b) 60.73(al(2) (lv) 73.71(b) 1 20AOS(c)

POWER 20AOS( ~ )(1)(l) 50.34 (c) (1) 50.73(al(2) (v) 73.71(cl LEVEL 20.405( ~ ) (I ) (QI 50.34(c) (2) 50.73(a) (2)(vR) OTHER ISpecify In Abstract below end In year, HRC Form 20.405( ~ l(1) (ill) 50.73(al(2) (I) 50.73(al(2)(v(ll) (AI 3SSAI 20A05(a l(1) (Iv) 50.73( ~ )(2)(8) 50.73(a)(2)(viill(B)

SS:::"",tA%:,~:.:. r ~'4 20.405( ~ l(1 l(v) 50.73(a l(2)(lii) 50.73(a H2)(x)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE S.L. Washington, Compliance Engineer 50 93 77- 208 0 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFAC.

TURER REPORTABLE TO NPROS rp P

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~ CAUSE SYSTEM COMPONENT MANUFAC TUREA TO NPRDS r BKR G08 0 Y P'%" s'c'%&

SUPPLEMENTAL REPORT EXPECTED (14) MONTH OAY 'YEAR EXPECTED SU 8 MlSS ION DATE 05)

YES Ilfyes, complete EXPECTED SVBMISSIOH DATE) NO ABSTRACT ILlmlt to 1400 rpeter, I e., approximately fifteen slnele g>>ce typewritten lineS (14)

On August 8, lg87 the plant was at 85$ power and on a gradual power ascension when, at 1855 hours0.0215 days <br />0.515 hours <br />0.00307 weeks <br />7.058275e-4 months <br />, a spurious trip of the Reactor Protection System {RPS) Electrical Protection Assembly (EPA) 3A Breaker caused a loss of power to RPS Bus A. The 'loss of power on R(3S Bus A caused a half-scram in RPS Division A and multiple Engineered Safety Feature (ESF) isolations and actuations.

The loss of'PS A power causes an Outboard Nuclear Steam Supply Shutoff System (NSSSS) isolation of Groups 1 (Main Steam Line Drains only), 2, 4 (two drain valves f only) 5, (7, and 7. NSSSS Group 7 isolates the Reactor Water Cleanup System {RWCU). J In addition, the loss of RPS A power causes a NSSSS Group 3 (Primary and Secondary Containment Ventilation and Purge Systems) and a partial Group 4 (Miscellaneous Balance of Plant) isolation and Standby Gas Treatment (SGT) System and Control Room l Emergency Filtration System actuation.

Plant operators switched R)7S Bus A to its alternate power supply and restored all systems to their pre-event lineup within 20 minutes.

The cause of the event was a spurious trip of the RPS-EPA-3A Breaker.

87'g50222 7g iQO PDR ADOCK S~O~~g7 0 PDR S

NRC Form 348

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NRC form 3aaA U.S. NUCLEAR REOULATORY COMMISSION (9431 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVEO OMB NO, 3(SOW(04 EXPIRES: B/3(lee FACILITY NAME 111 COCKET NUMBER (31 LER NUMBER Lel SaaUENTIAL RavrsloN NUMaarl NUM aR Washington Nuclear Plant TExT PI moro aooco (I roaM'rora rroo Abstract (continued)

~ - Unit Hec forrrr 3seiel (IT) 2 o s o o o 8 7 0 2 01 02 OF 0 4 The cause is attributed to oxide formation on the coil plunger end of the breaker undervoltage relay coil. This oxide formation reduced the magnetic force which holds the coil of the undervoltage relay in its set (activated) position. The root cause is oxide build up thought to be caused by overheating due to excessive design voltage on the coil.

The EPA Breakers will be periodically replaced until the oxide formation prob 1 em i s reso 1 ved.

There is no safety significance associated with this event as no actual'Plant condition requiring the Engineered Safety Feature isolations and actuations existed, and all isolations and actuations occurred as designed. Further, the ESF isolations and actuations had no adverse affect on Plant operation and,all systems were restored to their pre-event lineup within 20 minutes.

Plant Conditions a) Power Level - 85K b) Plant trode - 1 (Power Operation)

Event Descri tion On Auqust 8, 1987 the plant was at 85'A power and on a gradual power ascension

'when, at 1855 hours, a spurious trip of the Reactor Protection System (RPS)

Electrical Protection .Assembly (EPA) 3A Breaker caused a loss of power to RPS Bus A. The loss of power on RPS Bus A caused a half-scram in RPS Division A and multiple Enqineered Safety Feature (ESF) actuations.

The loss of RPS A power caused a NSSSS Containment Outboard Isolation. The outboard isolations occurred for NSSSS Group 1 (Hain Steam Line drains only),

Group 2 (Reactor Water Sample Valves), partial Group 4 (Miscellaneous Balance of P'lant, two drain valves), Group 5 (Residual Heat Removal (RHR) and Traversing In-Core Probe (TIP) Systems), Group 6 (RHR Shutdown Cooling), and Group 7 (Reactor Mater Cleanup). The RWCU System was in operation at the time of the event and was tripped off by the event.

In addition, the loss of RPS A power causes a NSSSS Group 3 (Primary and Secondary Containment Ventilation and Purge System) and partial Group 4 (Miscellaneous Balance of Plant, 6 valves) isolation. The NSSSS Group 3 and partial Group 4 isolation is caused by loss of power to the Reactor Building Exhaust Plenum Process Radiation Monitors, a non-NSSSS ESF trip signal. All required Group 3 and Group 4 actions occurred as designed including the automatic start of the Standby Gas Treatment System and the Control Room Emergency Filtration System and a Reactor Building HVAC Isolation .

NIIC FORM SaaA o U.S OPO, (Bee.o.e3i SeeM SS (9e3(

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NRC Form 3ddA U.S. NUCLEAR REGULATORY COMMISSION (94(3I LICENSEE EVENT REPORT ILER) TEXT CONTINUATION APPROVEO OMS NO. 3150&104 EXPIRES: 8/31/88 FACILITY NAME (11 LER NUMSER (51 SEGVCNZ/AL r. C( REV/SION NUM 44 F:Si'VM 44 Washington Nuclear Plant - Unit 2 o s o o o 39 787 0 2 5 0 1 0 3 oF 0 4 TfxT ///mort tpoct /4 ttr/rktrL VFF oc//oo'ort/ FvRc Form 39A'4/((TI Plant Operators responded by switching RPS-Bus A to its alternate power supply and by restoring all systems to their pre-event lineup within 20 minutes.

Plant Engineers and Electricians performed a ser ies of diagnostic tests to determine the cause of the breaker trip. The cause could not be determined.

The tests verified the incoming voltage and frequency were within allowable tolerances and that the logic board outputs were correct. The circuit breaker was reclosed with no problems; however, because of recurring problems with these breakers it was decided to replace the breaker with a new model breaker.

The failed RPS-EPA Breaker was manufactured by General Electric Company and the part number is TFJ226175WLN. RPS Bus A power was returned to the preferred source RPS-HG-lA through the new RPS-EPA-3A Breaker at 1421 hours0.0164 days <br />0.395 hours <br />0.00235 weeks <br />5.406905e-4 months <br /> on August 9, 1987.

The cause of the spurious EPA breaker trips (and the failure of the breaker to reclose after a trip) is attributed to oxide formation on the coil plunger end of the undervoltage relay coil. This oxide formation reduced the magnetic force which holds the coil of the undervoltage relay in its set (activated) position to the extent that spurious trips occurred and/or the coil would not hold when reset. The root cause is oxide buildup thought to be caused by

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overheating due to excessive design voltage on the coil. The coil voltage is controlled by a logic card in the EPA Breaker.

Immediate Corrective Action Plant Operators switched RPS Bus A power to its alternate power supply and all Plant. systems were restored to their pre-event lineup within 20 minutes .

Further Evaluation and Corrective Action As part of the root cause investigation Plant Electricians installed a line disturbance analyzer to monitor the l.ine input to the RPS-EPA-3A Breaker .

Points monitored included power supply current, voltage, and frequency; neutral to ground potential; and radio frequency interference. The line was monitored for twenty days during which no abnormal indications were observed.

The three remaining old model EPA breakers were replaced with new model breakers. There are six EPA breakers in the Plant and, prior to this event, three had been replaced with the new model. To date, the plant has not

. experienced any spurious actuations with the new breakers.

The Supply System sent two EPA breakers and a logic card to the breaker manu acturer (General Electric) for analysis and root cause determination. The Supply System has received final reports from General Electric. In addition, Plant Engineers discussed EPA breaker problems with other BWR utilities. The Plant Technical Staff is preparing a report on EPA breaker problems.

The EPA Breakers will be periodically replaced (approximately every three years) unti 1 the oxide formation problem is resolved.

N/IC FORM 3444 *U.S GPO,1985.0.524 538/455 (94(3I

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NRC Form 3ddA U.S. NUCLEAR REGULATORY COMMISSION (W3)

LICENSEE EVENT REPORT ILER) TEXT CONTINUATION APPROVEO OMS NO. 3(SONICS EXPIRES: S/31/88 FACILITY NAME (II COCKET NUMSER (2I LFR NUMBER (8) PACE (3I YEAR SEOVEHZIAL REVISION NUM E R ..e.( NVM@ER Washington Nuclear Plant - Unit 2 o s o o o 0 2 5 01 04 OF TEXT /I/ moro Epooo (s drrr'rorf, vw akA5ond IY/IC Arm 388ASI ( st(

Safet Si nificance There is no safety significance associated with this event because no Plant" condition requiring the ESF isolations and actuations existed and al'l ESF isolations and actuations occurred as designed. The ESF isolations and actuations had no adverse affect on Plant Operations, and all Systems were restored to their pre-event lineup within 20 minutes. The recurring problems caused by spurious trips of the EPA breakers is not adverse to Plant safety because these trips do not prevent the Reactor Protection System from performing its safety function. This event posed no threat to the safety of the public or Plant personnel.

Similar Events86-008 and 87-019 EIIS Information Text Reference EIIS Reference System Component Reactor Protection System (RPS) JC Reactor Protection System Electrical Protection Assembly (RPS-EPA-3A) JC BKR RPS-Bus-A JC BU Nuclear Steam Supply Shutoff System (NSSSS) BD Standby Gas Treatment (SGT) System BH Residual Heat Removal (RHR) System BD Reactor Water Cleanup (RWCU) System CE Traversing In-Core Probe (TIP) System IG Reactor Building Exhaust Plenum Process Radiation Monitor IL Reactor Building HVAC VA Control Room Emergency Filtration System VH NAC FOAM SEEA o U 8 GPO.S 988 082d 538/485 (9831

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ii WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 99352 Docket No. 50-397 November 20, 1987 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NUCLEAR PLANT NO. 2 LICENSEE EVENT REPORT NO. 87-025-01

Dear Sir:

Transmitted herewith is Licensee Event Report No. 87-025-01 for the WNP-2 Plant. This report is submitted in response to the report requirements of 10C~R50.73 and.discusses the items of reportability, corrective action taken, and action taken to preclude recurrence. V Very truly yours, C. . Powers (H/D 9?7H)

WNP-2 Plant Hanager CHP:ac

Enclosure:

Licensee Event Report No. 87-025-01 cc: Hr. John B. Hartin, NRC - Region V Hr. C. J. Bosted, NRC Site (H/D 901A)

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

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