ML17328A564

LER 88-003-06:on 880111,investigation Revealed That 4 Kv Bus Loss of Voltage & Degraded Voltage Relays Found Beyond Tech Specs Allowable Values.No Cause Noted.Each Relay Adjusted Upon Discovery & Change Request submitted.W/900206 Ltr

ML17328A564
Person / Time
Site:	Cook
Issue date:	02/06/1990
From:	Beilman T, Blind A INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-88-003, LER-88-3, NUDOCS 9002150099
Download: ML17328A564 (6)

Text

ACCELERATED DI+UBUTION DEMONS'HQTION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9002150099 DOC.DATE: 90/02/06 NOTARIZED: NO DOCKET FACIL:50-316 Donald C. Cook Nuclear Power Plant, Unit 2, Indiana & 05000316 AUTH. NAME AUTHOR AFFILIATION BEILMAN,T.P. Indiana Michigan Power Co. (formerly Indiana & Michigan Ele BLIND,A.A. Indiana Michigan Power Co. (formerly Indiana & Michigan Ele RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 88-003-06:on 880111,repetitive violation of ESF instrumentation LCO for operation tolerences.

W/8 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 PD3-1 LA 1 1 PD3-1 PD 1 1 GIITTER,J. 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/LHFBll 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 NRR/DSTQSPLB8Dl 1 1 NRR/DST/SRXB 8E 1 1 PEG FI 02 1 1 RES/DSIR/EIB 1 1 IYcHs PIL~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'iG A 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LIS1S FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 37 ENCL 37

Indiana Michigan Power Company Cook Nuciear Piant P,O. Box 458 Bndgman. tv)i 49106 616 465 5901 INDIANA fAICHIGAR PWER February 6, 1990 United States Nuclear Regulatory Commission Document Control Desk Rockville, Maryland 20852 Operating License DPR-74 Docket No. 50-316 Document, Control Manager:

In accordance with the criteria established by 10 CFR 50.73 entitled Licensee Event Re ortin System, the following report is being submitted:

88-003-06 Sincerely,

.A. Blind lant Manager AAB:clw Attachment cc: D.H. Williams, Jr.

A.B. Davis, Region III M.P. Alexich P.A. Barrett J.E. Borggren R.F. Kroeger NRC Resident Inspector J.G. Giitter, NRC R.C. Callen G. Charnoff, Esp.

Dottie Sherman, ANI Library D. Hahn INPO PNSRC S.J. Brewer/B.P. Lauzau

~0021500@+ g0020g ADOCK 0500031'~

S pbr.

NRC Form 355 U.S. NUCLEAR REGULATORY COMMISSION (94)3)

APPROVED OMS NO. 31504104 LICENSEE EVENT REPORT tLER) EXPIRES: 0/31/00 FACILITY NAME (I) DOCKET NUMBER (2) PAGE 3i D. C. COOK NUCLEAR PLANT UNIT 2 REPETITIVE VIOLATION OF ESF INSTRUMENT 0 M 05000316>pp04 OPERATION TOLERANCES DUE TO HIGHLY RESTRICTIVE ALLOWABLE VALUFS EVENT DATE(SI LER NUMBER (SI REPORT DATE (7) OTHER FACILI'TIES INVOI VEO IS)

NVtAL Oiin REVISION MONTH DAY YEAR YEAR gjYi BBQUS NUMBER>>'~zS NUMBER MONTH DAY YEAR FACILITYNAMES DOCKET NUMBERISI D.C. COOK - UNIT 1 0 5 0 0 0 0 1 03 06 0 2 0 6 9 0 0 5 0 0 0 OPERATING THIS REPORT IS SUBMITTED PURSUANT T 0 THE REQUIREMENTS OF 10 CFR ()t (Cnrce onr or moir oi tnr tollovn'not (Ill MODE (9)

] 20.402(B) 20.405(cl 50,73(el(2) (iv) 73.7'I (III POWE R 20.405( ~ l(1)(i) 50.35 (c) (I I 50.73(e)(2)(r) 73.71(c)

LEVEL (10) 0 8 0 20.405(e l(1) (0) 50.30(c)(2I 50,73( ~ ll2) Iriil DTHER (specify in Apt tirct Ortorr rnd in Trit, HRC Foim 20.405( ~ ) (I ) (ii)l 50.73(e l(2)(II 50.73(el(2) (riiil(AI 3SEAl 20A05(e ) (I ) (Irl 50.73( ~ I I2) I ii) 50,73(e) (2)(viiil(S) 20.405( ~ I (I I (v) 50.73(e) l2)(ii)l 50.73 (el (2) (e)

LICENSEE CONTACT FOR THIS I.ER (12I T. P. BEILMAN TELEPHONE NUMBER AREA CODE MAINTENANCE DEPARTMENT SUPERINTENDENT COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13) 616 465 -59 01 CAUSE SYSTEM COMPONENT MANUFAC.

TURER REPORTABLE

$ )if~i CAUSE SYSTEM COMPONENT MANUFAC TURER EPORTASI.E TO NPRDS iltNIIIII,I3%~k:

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SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED SUBMISSION (il yrt. compirtr EXPECTEO DATE (15)

YES Sueet)SS)ori DATE) NO ASSTRACT ILimit to tr00 tprcrt, i.r., rpproeimetrly iiitrrn tlnplr.toter typewritten linn) (15)

This revision's being submitted to reflect an update on the results of the increased frequency (monthly) calibration checks performed to date.

On March 11, 1988 an equipment trend investigation was being performed on 4KV Bus Loss of Voltage relays and the 4KV Bus Degraded Voltage relays (EIIS/EK-27) . The 'as found 'ondition of these relays during past calibration checks has generally been found to be beyond the Technical Specification (T.S.) allowable values. Each relay was adjusted to within allowable values at the time it was discovered out of specificat'ion. All relays were functional and would have performed the ESF function, although at a slightly different voltage than specified in T.S.

An engineering review has determined a plus or minus 3 percent tolerance (as opposed to the current 0.5 percent) to be acceptable for the Loss of Voltage application. The Degraded Voltage application will accept a plus or minus 1.5 percent tolerance and will require installation of more accurate undervoltage relays (De'sign Change currently underway). A T.S.

change request has been submitted. As stated in the original LER, we have increased the calibration frequency from every eighteen months to monthly.

NRC Form 355 (94)3)

NRC Form 366A U.S, NUCLEAR REGULATORY COMMISSION (0(L)l ~

LICENSEE EVENT REPORT (LERI TEXT CONTINUATION APPROVEO OMB NO. 3150&104 EXPIRES: 8/31/88 FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (31 YEAR Sf GUS NTIAL REVISION f

NUMB R NUMff R

- UNIT D. C. COOK NUCLEAR PLANT TEXT /4/1<<<<o rpocr /I I/o/olor/ Irw ~ HRC %%drrrr 368A'r/ (17) 2 31 68 8 0 0 OF This revision is being submitted to reflect an update on the results of the increased frequency (monthly) calibration checks performed to date.

Conditions Prior To Occurrence Unit 1 and Unit 2 were operating at 90 percent and 80 percent reactor thermal power,, respectively, throughout the event. There were no inoperative structures, components, or systems that contributed to this event.

Descri tion of Event On March ll, 1988, an equipment trend investigation was being performed on the 4KV Bus Loss of Voltage relays (EIIS/EK-27) and the 4KV Bus Degraded Voltage relays (EIIS/EK-27). The setpoints for these relays have been found to be outside of, the Technical Specification (T.S.) allowable values (T.S. 3.3.2.1 Table 3.3-4, items 8a and 8b). Of 144 individual calibrations on the loss of voltage relays over a seven year period, 68 were found to be outside of the T.S. tolerances. Of the 66 individual calibrations performed on the degraded voltage relays over a seven year period, 41 were found to be outside of the T.S. tolerances. The amount of deviation from the allowable setpoint band was limited and distribution among the relays was random, indicating no particular relay to be defective. A survey of other utilities which use this type of relay revealed that the performance of our relays is consistent with their experience and within manufacturer's specifications. Each relay was read)usted to within allowable values at the time it was discovered out of specification.

The Loss of Voltage relays are installed to sense a loss of offsite or normal auxiliary power to the ESS 4KV buses. Once the loss of voltage has been sensed and after a two-second time delay, these relays in a 2/3 phases logic initiate load shedding and emergency diesel generator starting. The Degraded Bus Voltage relays are installed to sense degraded reserve power feed to the ESS 4KV buses and , on a 2/3 phases logic with a two-minute time delay, trip open the reserve feed breakers and start the emergency diesel generators. Once the emergency diesel generator has restored bus voltage to normal, safety loads are sequenced on to the safety buses. The Technical Specifications for Units 1 and 2 have existing setpoints of 80 percent (+.5 X, -1.0%) for the Loss of Voltage and 90 percent (+1.0%, .5X) for the Degraded Grid detection. The tolerance on these setpoints are closer than t'e relays can obtain, and more importantly, closer than normal voltage, initiating load shedding, and diesel starting.

NRC FORM 366A <<U.S/GPO:(9684.624 538/f 55 (963)

NRC Form 38BA U.S. NUCLEAR REGULATORY COMMISSION (583)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATIO APPROVED OMB NO, 3150&)04 EXPIRES: 8/31/88 FACILITYNAME (I) DOCK ET NUMBE R (2) LER NUMBER (6) PAGE 13)

YEAR SEGVENT/AL /IEVISK/4 NVVSPR 4VVSSO DONALD C. COOK NUCLEAR PLANT - UNIT 2 0 0 3 0 603 <Fo TEXT //P//rao Nroco k so///for/ I/po at///Oon/o/NRC Forrrr 3(/SAS/ (IT)

Cause of the Event Calibration history shows a performance record in line with undervoltage relays used at other plants. We have reviewed the application of undervoltage relays for this function with other utilities and various relay manufacturers.

We have concluded that the undervoltage relays are being properly applied in this mode as a conventional protective relay. This use would not normally involve having an acceptance band. Many utilities consulted had no Technical Specification required tolerances for this function and others had broader allowance values which more closely reflect the manufacturer's expected performance tolerances.

Anal sis of Event American Electric Power's System voltage studies have been performed and indicate that the worst case voltage on the ESS buses at the Cook Nuclear Plant would be 87.3 percent. We do not expect the FSS bus voltage to drop to a lower voltage than this unless a complete plant blackout condition occurred. Under a blackout condition, the ESS bus voltage would quickly drop well below the 80 percent undervoltage relay setpoint and initiate load shedding and diesel start. The only function of the 80 percent voltage relays is to sense a total loss of ESS bus voltage. Therefore, the setpoint deviations we'e experienced translate into a different line voltage and time than the Technical Specification calls for, but the time involved for this additional voltage. drop is insignificant.

The function of the degraded bus relays are to disconnect the plant from the grid for a sustained degraded condition, i.e., less than 90 percent voltage for at least two minutes. They are armed only when the plant is fed from offsite power. Plant normal configuration is to be fed from the generator auxiliary transformers except for short periods during startup and shutdown. Therefore, these relays are not normally active during unit operation.

Again, relating to our system studies, we do not believe the slight out of tolerance to be a safety problem for the degraded bus relays. Our studies indicate that the lowest possible offsite voltage to our buses would be 93.3 percent except for the short period during Reactor Coolant Pump (RCP) starting, which is less than one minute. During RCP starting, the bus voltage can dip to 87.3 percent, however, we are protected from an unnecessary trip by the two-minute time delay on this circuit.

NRC FORM SOOA o U.B,GPO:1888.0 824538/455 (04)3)

NRC Foe/R 366A U.S. NUCLEAR REOULATORY COMMISSION (04)3)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVEO OMB NO. 3150-0104 EXP/RES: 8/31/88 FACILITY NAME 11) OOCKET NUMBER 12) LER NUMBER 16) PACE 13)

YEAR (ivy SEOUENTIAL +.+~'EVISION XSI NUMBER DONALD C. COOK NUCLEAR PLANT - UNIT 2

)%% NUMBER 0 5 0 0 0 3 1 6 0 0 3 0 6 0 40F 0 4 TlÃT//Pmo/4 4//ooo/4 FEo/Io/f, Uoo 4/4/ooo/NRC Fom/ 3654'4/ )IT)

An engineering review has determined a plus or minus 3 percent tolerance (as opposed to the current 0.5 percent) to be acceptable for the Loss of Voltage application. Most of the calibration history data is within 3 percent of the required setpoint. The few exceptions are considered. normal random failures.

The Degraded Voltage application will accept a plus or minus 1.5 percent tolerance. This value is suitable for the installation of more accurate undervoltage relays.

Based on the above, it health and safety of the public as a result of has been concluded that there is no jeopardy to the this event.

Corrective Action The relays were recalibrated to within the allowable values at the time of discovery during the calibration. In addition, all of the relays'ere recalibrated from April 7-9, 1988. Out of the 36 relays for Units 1 and 2, eleven were found out of specification. Unit 1's were last calibrated in July 1987 and Unit 2's were calibrated in February 1988. An engineering review has determined a plus or minus 3 percent tolerance to be acceptable for the Loss of Voltage application and a plus or minus 1.5 percent tolerance for the Degraded Voltage application. A Technical Specification change request h as been submitted. In addition, a Design Change regarding the replacement of the currently installed Degraded Voltage relays with more accurate relays is scheduled to be completed at the next refueling outages for both units.

As stated in the original LER, we have increased the calibration frequency from every eighteen months to monthly until the trend indicates a different frequency is )ustified.

Monthly calibration checks have yielded the following results to date:

4KV Loss of Voltage - 429 calibrations 11.0 percent 47 failures 4KV Degraded Voltage 210 calibrations 18.6 percent 39 failures Failed Com onent Identification None.

Previous Similar Events LER 316/81-015 LER 316/82-108 LER 315/81-017 LER 315/83-069 LER 315/82-051 LFR 315/83-094 LER 315/82-059 LER 316/82-100 NRC FORM 366A o U.S GPO:1888.0.824 538/455 I84)3)