ML17326B413

LER 88-003-01:on 880311,limiting Condition for Operation for ESF Instrumentation Violated.Caused by Highly Restrictive Allowable Values.Tech Spec Change Request Will Be Submitted in Near future.W/880729 Ltr

ML17326B413
Person / Time
Site:	Cook
Issue date:	07/29/1988
From:	Beilman T, Will Smith INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
LER-88-003, LER-88-3, NUDOCS 8808110218
Download: ML17326B413 (6)

Text

t ACCESSION NBR:8808110218 DOC.DATE: 88/07/29 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.

SMITH,W.G. Indiana Michigan Power Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 88-003-01:on 880311,limiting conditions for operation for ESF instrumentation violated.

W/8 DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73 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 STANG,J 1 1 INTERNAL: ACRS MICHELSON ACRS MOELLER 2 2 AEOD/DOA AEOD/DSP/NAS 1 1 AEOD/DSP/ROAB AEOD/DSP/TPAB 1 1 ARM/DCTS/DAB DEDRO 1 1 NRR/DEST/ADS 7E NRR/DEST/CEB. 8H 1 1 NRR/DEST/ESB 8D NRR/DEST/ICSB 7 1 1 NRR/DEST/MEB 9H NRR/DEST/MTB 9H l. 1 NRR/DEST/PSB 8D NRR/DEST/RSB 8E 1 1 NRR/DEST/SGB 8D NRR/DLPQ/HFB 10 NRR/DLPQ/QAB NRR/DREP/RAB 10 10 NRR/DOEA/EAB NRR/DREP/RPB 10 ll 1 1

2 1

1 2

NRRj)RLS IB 9A NUDOCS-ABSTRACT 1 1 FILE 02 RES TELFORD,J 1 1 D IR DEPY RES/DSIR/EIB 1 1 RES/DSR DEPY RGN3 FILE 01 1 1 EXTERNAL EGGG WILLIAMSg S FORD BLDG HOY,A 1 1 H ST LOBBY WARD LPDR~ 1 1 NRC PDR NSIC HARRISiJ 1 1 NSIC MAYS,G TOTAL NUMBER OF COPIES REQUIRED: LTTR 46 ENCL 45

'.IRC Form 344 US. NUCLEAR REOULATORY COMMISSION (943)

APPROVED OMS NO. 3150410e LICENSEE EVENT REPORT {LER) EXPIRES: 4I31ISS FACILITY NAME (I) DOCKET NUMBER (2) PA E D. C. COOK NUCLEAR PLANT UNIT 2 p s p p p 3 1 6 1 QFO REPETITIVE VIOLATION OF ESF INSTRUMENTATION LIMITING CONDITIONS FOR OPERATION TOLERANCES DUE TO HIGHLY RESTRICTIVE ALLOWABLE VALUES EVENT DATE (5) LER NUMBER IS) REPORT DATE (7) OTHER FACILITIES INVOLVED (4)

MONTH OAY YEAR YEAR ~+g'EOUENTIAL IIEvrerON OAY YEAR FACILITYNAMES DOCKET NUMBER(s)

NVMBEri NUMBER MONTH D. C. COOK UNIT 1 0 5 0 0 0 3 1 5 03 11 8 8 8 8 0 0 3 0 1 07 298 8 0 5 0 0 0 OPERATINO THIS REPORT 1$ SUBMITTED PURSUANT T 0 THE REQUIREMENTS OF 10 CFR $ ; (Cheep one ot mote of the foiforllnpl (ll MODE IBI 20.e02(B) 20A05(cl 50,73(el(2) (Irl 73.71 FBI POWER 20.405(el(1)(il 50.34(e) (1) 50.7 3(e l(2 I (r) 73.71(cl LEVEL (10) 20.e05(e l(1((BI 50.34(cl(2) 50.73(e)(2) (rill DTHER Ispeclfy In Aortrect

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LICENSEE CONTACT FOR 'THIS LER (12)

T. P. BEILMAN TELEPHONE NUMBER AREA CODE INSTRUMENTATION AND CONTROL DEPARTMENT SUPERINTENDENT COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 113) 616 465 - 90 I

" 'mp":e@on CAUSE SYSTEM COMPONENT MANUFAC EPORTASLE MANUFAC- EPORTASLE CAUSE SYSTEM COMPONENT 1'URER TO NPROS

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SUPPLEMENTAL REPORT EXPECTED IIei MONTH DAY YEAR EXPECTED SUSMISSION DATE I I 5)

YES llfyer, comprere EXPECTED SVBMISSIOH OA TEI NO ASSTRACT (Limir to lc00 rpecer, I e., eppfoeimerely fifteen rinpte.rpece typerrnrNn lined (14)

This revision is being submitted to reflect the results of the increased frequency calibration checks performed to date.

On March ll, 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 cali-bration checks has generally been found to be beyond the Technical Specification (T.S.) allowable values. Each relay vas adjusted to within allowable values at the time it was discovered out of specifica-tion. All relays vere 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 two applications. A Technical Specification change request will be submitted in the near future. As stated in the original LER, ve have increased the calibration frequency from every eighteen months to monthly.

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NRC Form 345 In nhl

NRC Form 3SSA U.S. NUCLEAR REGULATORY COMMISSION (9431 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVED OMB NO. 3150&104 EXPIRES: 8/31/88 FACILITY KAME ill COCKET NUMBER 12) LER NUMBER (6) PACE l31 SEOVSNTIAL D. C. COOK NUCLEAR PLANT UNIT 2 YEAR NVMSSR REVISION NUMBER 0 0 o 31 68 8 003 0 1 0 2 QF0 4 TEXT //mao sPocP 11 rmF4PSI/, I/PP //I/O44/A'RC Fr/mr 3//SA3/ 1 IT/

This revision is being submitted to reflect the results of the increased frequency 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 11, 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 readjusted 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 res'erve 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 Unit 1 and 2 have existing setpoints of 80 percent (+.5X, -1.0Z) for the Loss of Voltage and 90 percent (+1.0Z, .5X) for the Degraded Grid detection. The tolerance on these setpoints are closer than the relays can obtain, and more importantly, closer than required for performing their intended function, i.e., sensing loss of normal voltage, initiating load shedding, and diesel starting.

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o NRC Form 3BBA U.S. NUCLEAR REOULATORY COMMISSION (883)

LICENSEE EVENT REPORT ILER) TEXT CONTINUATION APPROVEO OMB NO 3150W104 EXPIRES: 8/3)/88 FACILITY NAME (I) OOCKET NUMBER (21 LER NUMBER (Bl PACE (3) pArC i~); AevlsloN YEAA hlYO) SEQUENTIAL NuMBBA NVMBBA D. C. COOK NUCLEAR PLANT UNIT 2 0 5~ 0 0 0 3 I 8 8 0 0 01 03 OF 0 '4 TEXT(/mreo<<>>co Jeroeo)BIE r>>o RRI)Or>>INRC%%drm 30%43) (17)

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 The Event American Electric Power's System voltage studies have been performed and indicate that the worst case voltage on the ESS buses at the the Cook Nuclear Plant would be 87.3 percent. We do not expect the ESS 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 un-necessary trip by the two-minute time delay on this circuit.

A plus or minus 3 percent tolerance (as opposed to the current 0.5 percent) has been determined to be acceptable by engineering review. Most of the calibration history data is within 3 percent of the required setpoint.

The few exceptions are considered normal random failures.

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NRC Form 388A U.S. NUCLEAR REGULATORY COMMISSION (S43l LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVEO OMB NO. 3150M104 EXPIRES: 8/31/88 FACILITY NAME (Il OOCKET NUMBER (2I I.ER NUMBER (SI I'AGE I3)

YEAR SEQUENTIAL AEYIS/ON Nr/MBE/I NUMSEA D. C. COOK NUCLEAR PLANT UNIT 2 316 88 003 0 1 0 4 0F 04 TEXT /8'mme apace /s /l//kror/ Irw edi&onsl NRC %%dr/ 38843/ (IT)

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

Corrective Action Equivalent relays with less drift have not been identified as available in the industry. The relays were recalibrated to within the allowable values at the time of discovery during the calibration. In addition, all of the relays were 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 applications where these relays are being used. A Technical Specification change request will be submitted in the near future. 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 justified.

Monthly calibration checks have yielded the following results to date:

4KV Loss of Voltage 48 calibrations 6 failures 4KV Degraded Voltage 24 calibrations 8 failures Failed Com onent Identification None.

Previous Similar Events LER 316/81-015 LER 315/81-017 LER 315/82-051 LER 315/82-059 LER 316/82-100 LER 316/82-108 LER 315/83<<069 LER 315/83-094

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Indiana Michigan Po~r(or Company Cook ihuclear Piant P.O. Box 458

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Bndgman, iMI 49106 6I6>>65 5901 July 29, 88 United States Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Operating License DPR-58 Docket No. 50-316 Document Control Manager:

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

88-003-01 Sincerely, W. G. Smith, J Plant Manager WGS:clw Attachment cc: D. H. Williams, Jr.

A. B. Davis, Region III M. P. Alexich P. A. Barrett J. E. Borggren R. F. Eroeger NRC Resident Inspector J. F. Stang, NRC R. C. Callen G. Charnoff, Esq.

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