ML17261B082

LER 90-008-00:on 900524,determined That Five of Eight Degraded Voltage Relays on 480-volt Safeguard Buses Calibr Outside of Tech Spec Limits.Caused by Use of Wrong Setpoint.Relays Recalibr & Returned to svc.W/900625 Ltr

ML17261B082
Person / Time
Site:	Ginna
Issue date:	06/25/1990
From:	Backus W, Mecredy R ROCHESTER GAS & ELECTRIC CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-008, LER-90-8, NUDOCS 9007050121
Download: ML17261B082 (12)

Text

ACCELERATED lg>TRJBUTION DEMONSATION SYSTEM REGULATORY INFORMATION 'DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9007050121 DOC.DATE: 90/06/25 NOTARIZED: NO DOCKET FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION BACKUS,W.H. Rochester Gas & Electric Corp.

MECREDY,R.C. Rochester Gas & Electric Corp.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 90-008-00:on 900524,safeguards buses degraded voltage relays miscalibrated de to procedure inadequacy.

W/9 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

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

NOTES:License Exp date in accordance vith 10CFR2,2.109(9/19/72). 05000244 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD1-3 LA 1 1 PD1-3 PD 1 1 JOHNSON,A 1 1 INTERNAL ACNW 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP. 2 2 DEDRO 1 1 . NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB9H3 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 NOR/DST/SICB 7E 1 1 B8D1 1 1 NRR/DST/SRXB 8E 1 1 EG ILE 02 1 1 RES/DSIR/EIB 1 1 RG 1 FILE 01 1 1 EXTERNAL EG&G STUART g V A 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 D

NOTE TO ALL "RIDS" RECIPIENTS:

D PLEASE HELP US TO REDUCE lVASTE! CONTACI'HE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 34 ENCL 34 P+

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ROCHESTER GAS AND ELECTRIC CORPORATION ~ 89 EAST AVENUE, ROCHESTER, N.K 14649 0001 I

TELCPHO4C isei coot 7ie 546 2700 June 25, 1990 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Subject:

LER 90-008, Safeguards Buses Degraded Voltage Relays Miscalibrated Due To Procedure Inadequacy Causes a Condition Prohibited By Plant Technical Specifications R. E.. Ginna Nuclear Power Plant Docket No. 50-244 In accordance with 10 CPR 50;73, Licensee. Event Report System, Item (a)(2)(i)(B), which requires a report of "any operation prohibited by the plant's Technical Specifications", the attached Licensee Event Report LER 90-008 is hereby submitted.

This event has in no way affected the public's health and safety.

Very truly yours, Robert C. Mec edy Division Mana er Nuclear Production XC: U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 xc: Ginna USNRC Senior Resident Inspector

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Safeguards Buses Degraded Voltage Re ys z.sca x ra e o ure Inad ac Causes A Condxtion Prohibited By Plant Technical Specifications IVCNT OATCISI LIA NVasOCA ill AltOAT OATS m OTlllA t ACILI TI IS NrvOLVIO ISI

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SVttLIISINTAL1ltOAT IAtlCTIO II% ssONTN CAY YIAA IatlCTIO Lvlas i lllo1 OA'TI II II TCI lit ~. SitCCTCO SVSSSISS O>> OArCI O LSSTA*CT Iassvr ss I%XI rtsr>>, I a, stsrassrrs>>rt rrrrss Nstssstsrs rttsrrsrrss assss llll at with the reactor at approximately full24,power, On May 1990 1604 EDST 984 an evaluation of undervoltage relay test data revealed that five (5) of the eight (8) Degraded Voltage Relays on 480 volt 'afeguard buses were calibrated such that relay actuation would not occur within the limits of Technical Specifi-cations.

As this was a setpoint problem with the degraded voltage relays, no immediate plant or operator responses were necessary.

The underlying cause of the event was attributed to the wrong setpoint and setpoint tolerance being specified in a calibration procedure.

Immediate corrective action was to calibrate the Degraded Voltage Relays to a setpoint on the conservative side of the tolerance.

Subsequent to the calibration, the degraded voltage relays were tested satisfactorily and returned to service.

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NAC Sodom 444A U,4. NUCLCAA ATOULATOAYCOMMI94ION I945I LICENSEE EVENT REPORT ILER) TEXT CONTINUATION ASSAOYTO OM4 NO 1I50&10I 5)ISIA4$ 4I5I/45 SACILITY NAM4 Ill OOCKTT NUM44A ITI LTA NUM44A 19I ~ AO4 I4I 94OUTNTIAL ATVCKIN NUM NUM R.E. Ginna Nuclear Power Plant o s o o o 24 490 008 0 0 02 op0 TEXT (IS mar MSSS N natured. sM OdOeenV NIIC fenn 445AYI Iltl PRE-EVENT PLANT CONDITIONS The unit was at approximately 98% reactor power. The Results and Test Department and an Electrical Engineering representative were observing the Relay Department performing protective relay calibration procedure PR-1.1 (480 Volt Undervoltage And Ground Alarm Scheme For Buses 14, 16, 17 and 18.)

II. DESCRIPTION OF EVENT A. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES:

o Modification installation in 1982: Event date o May 24, 1990, 1115 EDST: Discovery date and time of the first of five relays found-below the limit of Technical Specifications.

o May 24, 1990, 1604 EDST: All affected relays recalibrated, tested satisfactorily and restored to service.

B. EVENT:

On May 24, 1990 at 1604 EDST, with the reactor at approximately. 98% full power PR-l.l was completed.

Evaluation of the PR-l.l data revealed that five (5) of the eight (8) Degraded Voltage Relays on 480 volt safeguards buses 14, 16, 17, and 18 had been calibrated such that relay actuation would not occur within the limits of Technical Specifications, page 2.3-10, Figure 2.3-1. The relays affected were as follows: relays 27/14 on Bus 14, 27B/16 on Bus 16, 27/17 and 27B/17 on Bus 17 and 27/18 on Bus 18. This determination occur-red after evaluation and analysis of test data and Technical Specification reiui:rements as follows:

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SAC ILITY NAMK 111 OOCKST NUMSSA ITI LSII NUMSKII I ~ I tAOS ISI SAA SIOUSHTcAL 4 A9 V IQ H HUM NVCC 9 A TSICT R.E. Ginna Nuclear Power Plant lllmCn NMCC ~ CCevnd, Wc aAkxnt NAC f<<rn AKI'llI ITI osooo2440 08 000 30FO 8 0 The current. 480 volt safeguards bus undervoltage system was first put in service in 1982. Setpoints were specified by Corporate Electrical Engineering, and these'etpoints (with tolerances established by the Relay and Test Department) were used to calibrate these relays over the past eight years.

0 On April 4, 1990 the normal annual calibration was performed on the 480 volt safeguards buses Degraded Voltage Relays, per PR-l.l. This procedure checks and calibrates the dropout voltage of the relays.

The procedure specified a + 54 calibration toler-ance on the dropout setpoint with a "desired" specified setpoint of 103.5 volts. All Degraded Voltage Relays were calibrated to these specifica-tions. Because of the + tolerance allowed by the procedure some of the relays were calibrated to less than the "desired" 103.5 volts which was considered acceptable.

0 On April 12, 1990 the normal post calibration test was performed on the 480 volt safeguards buses Degraded Voltage Relays per periodic test procedure PT-9.1 (Undervoltage Protection - 480 Volt Safeguard Buses). This procedure checks the reset voltage of the relays and also the dropout response time, but does not check the dropout voltage. All Degraded Voltage Relays were found to be within the specifications of the procedure.

0 Prior to April 26, 1990 a review of the calibration data from April 4, 1990 and a review of plant Technical Specifications was performed by the ISI/IST Coordinator and an Electrical Engineering representative. Following this review, these in-dividuals requested that all Degraded Voltage

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'svolorr NMM SA R.E. Ginna Nuclear Power Plant 0 5 0 0 0 2 4 4 90 008 00 04 oF0 SEXY llfrrroro Aooco N rooMrof. ooo ANoooenor HIIC forrrr ~'IIIIII Relays that were found at or below 103.5 volts be adjusted to greater than 103.5 volts. The greater than 103.5 volts was requested to ensure that all relays were within the Technical Specification limit of 103.5 volts prior to entering the plant mode for which these relays are required to be operable. Five Degraded Voltage Relays were adjusted on April 26, 1990.

On May 11, 1990 the normal monthly PT-9. 1 was performed on all 480 volt sa feguards buses Degraded Voltage Relays. This test was witnessed by an Electrical Engineering representative. After review of the test data, the Electrical Engineering representative expressed a concern that, based on the test reset data, 'actual dropout voltage of 5 of the Degraded Voltage Relays may be below the Technical Specification 103.5 volt limit.

On May 24, 1990 PR-l.l was reperformed on the 5 Degraded Voltage Relays to verify their dropout voltage setpoint. At 1115 EDST, the dropout voltage of the first relay was checked and found below the Technical Specification limit of 103.5 volts. Subsequently, the dropout voltages of the other 4 relays were also found below the Technical Specification limit of 103.5 volts. The affected relays were recalibrated to greater than 103.5 volts and PT-9.1 was performed on each relay as it was restored to service following calibration.

All relays subsequently tested satisfactorily.

0 On May 29, 1990 PT-9.1 was reperformed on all 480 volt safeguards buses Degraded Voltage Relays to check for possible setpoint drift. All relays tested satisfactorily.

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None.

D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None.

E. METHOD OF DISCOVERY:

The event was made apparent during the performance of PR-l.l on May 24, 1990.

F. OPERATOR ACTION:

As this was a setpoint problem with the Degraded Voltage Relays, no immediate'perator action was necessary.

G. SAFETY SYSTEM RESPONSES:

None.

III. CAUSE OF EVENT A. IMMEDIATE CAUSE:

The immediate cause of the event was due to 5 of 8 Degraded Voltage Relays on 480 volt safeguard buses 14, 16, 17, and 18 being calibrated such that relay actuation would not occur within the limits of Technical Specifi-cations.

B. ROOT CAUSE:

The root cause of the event discovered on May 24, 1990, was attributed to the calibration conditions that existed on April 26, 1990, during the previous calibra-tion of the five Degraded Voltage Relays. The underlying NAC 501M 555k

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$ 451 U.d. NVCLEAII AEOULATOIIYCOMMISSION LICENSEE EVENT REPORT ILERI TEXT CONTINUATION AttllOVEO OMS NO SI50&IOC EAtllIES 5/5 II55 tACILITYNAME III OOCKET NVMEEII LTI LEII NVMOEII Idl tAOE ISI 5CQIICNTIAL ACVICIQN NVM CA NIIM C A R.E. Ginna Nuclear Power Plant TEXT litreree Mece ~ reee>>AC. eee erAM>>r>>I NIIC terIA SELC Ol IITI o so oo244 90 0 08 0 0 0 60FO 8 cause of finding setpoints below limits (in the past) is now evident and is due to the wrong setpoint and setpoint tolerance being specified in a calibration procedure. The calibration procedure for the safeguard bus Degraded Voltage Relays (PR-1.1) specified an acceptance criteria of 103.5 volts + 5%. Ginna Technical Specification figure 2.3-1 requires the 'Degraded Voltage Relays to actuate when the relay voltages drop to 103.5 volts (AC) which corresponds to 414 volts on the 480 volt safeguard bus. The relay setpoint of 103.5 volts was determined by RG&E Corporate Engineering and provided to Relay. and Test Department for use in the calibration of these relays. However, no definitive tolerance band was provided with the desired setpoint.

Normal vendor recommended tolerances were applied upon development of the calibration procedure. This resulted in the actual setpoint of these relays to be acceptable when left below the required minimum dropout voltage of 103.5 volts.

IV. ANALYSIS OF EVENT This event is reportable in accordance with 10 CFR 50.73, Licensee Event, Report System, item (a)(2)(i)(B)t which requires a report of, "any operation prohibited by the plant's Technical Specifications." The 5 out of 8 Degraded Voltage Relays being calibrated such that relay actuation would not occur within the limits of Technical Specifications was an operation prohibited by the plant Technical Specifica-tions.

An assessment was performed considering both the safety consequences and implications of this event with the following results and conclusions:

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There were no operational or safety consequences or implica-tions attributed to the 5 of 8 Degraded Voltage Relays on 480 volt safeguard buses 14, 16, 17, and 18 being calibrated such that relay actuation would not occur within the limits of Technical Specifications because of designe'd relay redundancy and required operator actions.

Each safeguard bus is provided with two Degraded Voltage Relays and two loss of voltage relays. Any one of these relays will start the corresponding emergency diesel genera-tor. Two out of two of either the Degraded Voltage Relays or the Loss of Voltage Relays will strip the safeguards bus and close the diesel tie breaker onto the safeguards bus. The miscalibration of the Degraded Voltage Relays would not have prevented the diesel generator from supplying emergency power to the safeguards bus upon a loss of voltage.

Ginna abnormal operating procedure AP-ELEC.2, (Safe'guards Buses Low Voltage or System Low Frequency), requires both emergency diesel generators to be started manually safeguards bus voltage falls below 420 volts. In addition, if any if any safeguards bus voltage decreases to 414 volts, the operator is directed to transfer all safeguard bus power supplies to the emergency diesel generators. Since Technical Specifica-tion Figure 2.3-1 allows approximately 20 minutes of continued operation at the lowest miscalibrated relay setpoint, ample time was allotted for operators to perform required action of AP-ELEC.2.

Based health on the above, it and safety was assured at can be concluded that all times.

the public's V. CORRECTIVE ACTION A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:

o The affected relays were recalibrated to greater than the 103.5 volts Technical Specification limit, tested satisfactorily and restored to service.

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R M SA R.E. Ginna Nuclear Power Plant 24 490 00 8 0 0 08 Dp0 8 TEXT Ilt~MS' ~. uSs ~IYIICa ~'S>IITI o 5 o o o B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

o The test conditions that existed on April 26, 1990, will be evaluated. As a result of this evaluation, it is expected that improvements will be recommended.

Any relays calibrated after April 25, 1990, will be identified. The results of these calibrations will be reviewed for generic concerns with test conditions.

0 An analysis will be .performed to obtain the optimum setpoint and setpoint tolerance 'for the Degraded Voltage -Relays.

0 Calibration procedure PR-1.1 will be revised to incorporate these new setpoints and setpoint tolerances.

A new methodology for testing these relays will be incorporated into Periodic Test procedure PT-9.1.

VI. ADDITIONAL INFORMATION A. AFFECTED COMPONENTS:

The Degraded Voltage Relays are a Model 211B1175D Type ITE-27 relay manufactured by ITE Corporation.

B. PREVIOUS LER'S ON SIMILAR EVENTS:

A similar LER event historical search was conducted with the following results: no documentation of similar LER events with the same root cause at Ginna Station could be identified.

C. SPECIAL COMMENTS:

None. ~

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