05000315/LER-1998-040, :on 980831,ESF Actuation & Start of EDGs 1 Cd & 2 Cd,Occurred.Caused by Equipment Failure.Cable Fault Was Located & Failed Section Cut Out & Cable Spliced.With

:on 980831,ESF Actuation & Start of EDGs 1 Cd & 2 Cd,Occurred.Caused by Equipment Failure.Cable Fault Was Located & Failed Section Cut Out & Cable Spliced.With

ML17335A251
Person / Time
Site:	Cook
Issue date:	09/30/1998
From:	Finissi M, Sampson J INDIANA MICHIGAN POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-98-040, LER-98-40, NUDOCS 9810020421
Download: ML17335A251 (7)

LER-1998-040, on 980831,ESF Actuation & Start of EDGs 1 Cd & 2 Cd,Occurred.Caused by Equipment Failure.Cable Fault Was Located & Failed Section Cut Out & Cable Spliced.With

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
3151998040R00 - NRC Website

text

CATEGORY 1

'REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9810020421 DOC.DATE: 98/09/30 NOTARIZED: NO DOCKET FACIL:50-315 Donald C.

Cook Nuclear Power Plant, Unit 1, Indiana M

05000315 AUTH.NAME AUTHOR AFFILIATION FINISSI,M.

Indiana Michigan Power Co.

SAMPSON,J.R.

Indiana Michigan Power Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 98-040-00:on 980831,ESF actuation 6 start of EDGs 1

CD '

CD, occurred. Caused by equipment failure. Cable fault was located 6 failed section cut out 8 cable spliced. With 980930 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

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

NOTES:

RECIPIENT 1D CODE/NAME PD3-3 PD INTERNAL: AEOD S RAB NRR DE/EELB NRR/DRCH/HICB NRR/DRCH/HQMB NRR/DSSA/SPLB RGN3 FILE 01 EXTERNAL: L ST LOBBY WARD NOAC POORE,W.

NRC PDR COPIES LTTR ENCL 1

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RECIPIENT ID CODE/NAME STANG, J AEOD/SPD/RRAB NRR/DE/ECGB NRR/DE/EMEB NRR/DRCH/HOHB NRR/DRPM/PECB RES/DET/EIB LITCO BRYCE,J H NOAC QUEENER,DS NUDOCS FULL TXT COPIES LTTR ENCL 1

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N NOTE TO ALL "RZDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANZZATZONi CONTACT THE DOCUMENT CONTROL DESK (DCD)

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Indiana Michigan ~

Power Company Cooktkdoar As%

One Cook Rare Briinn.Ml49106 616 465 5601 Z

INDIANA NICHIGAN POWER September 30, 1998 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Operating License DPR-58 Docket No. 50-315 Document Control Manager:

In accordance with the criteria established by 10 CFR 50.73 entitled Licensee Event 98-040-00 Sincerely, gk iQQy J. R. Sampson Site Vice President

/mbd" Attachment J.

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Caldwell (Acting), Region III R. P.

Powers P. A.

Barrett J.

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Kingseed R.

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Hahn Records Center, INPO NRC Resident Inspector 9Si002042i 980930 PDR ADOCK 050003lS S

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1

NRC Form 366

, (4-95)

U.S. NUCLEAR REGULATORYCOMMISSION LICENSEE EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

APPROYEO BYOMB NO. M504105 EXPIRES 04I50J55 ESTIMATED BVROEN PER

RESPONSE

TO COMPLY WITH THIS MANDATORY INFCRMATIONCOLLECTCN REOVEST: 50.0 HRS. REPORTED lESSONS IEARNEO ARE NCORPOMTED elTO THE JCENSSNKT PROCESS ANO FED BACK TO INOVSTRY. FORWARD COMMENTS REGARONO BVROEN ESTSIATE TO THE INFCRMATIONAIe RECORDS MANAGDIENTBRANCH IT4 FSTI, V.S. NVClEAR REGIRATORY COMISSSION, WASISNGTON.

OC 505550001, ANO TO THE PAPERWORK REDVCTION PROJECT (5150010I). OFFICE OF MANAGEMENTANO BVOGET.WASISNGTON. OC 50505 FACIUTYNAME(1)

, TITLE(S)

Cook Nuclear Plant Unit 1 DOCKET NUMBER (1) 50-315 PAGE (5) 1 of4 ESF Actuation and Start of Emergency Diesel Generators 1 CD and 2CD Due to Faulted Underground Cable EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILITIESINVOLVED(6)

MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REVISION NUMBER MONTH DAY YEAR A

I NAM Cook - Unit 2 A ILI NUM 50-316 08 31 OPERATING MODE (9)

POWER LEVEL(10) 98 98 040 00 09 30 98 00 THIS REPORT IS SUBMITTEDPURSUANT TO THE REQUIREMENTS OF 10 CFR (I: (Check one or 20.2201 (b) 20.2203(a)(1) 20.2203(a)(2)(i) 20.2203(a)(2)(v) 20.2203(a)(3)(i) 20.2203(a)(3)(ii) 50.73(a)(2)(i) 50.73(a)(2)(ii) 50.73(a)(2)(iii) more) (11) 50.73(a)(2)(viii) 50.73(a)(2)(x) 73.71 20.2203(a)(2)(ii) 20.2203(a)(2)(iii) 20.2203(a)(2)(iv) 20.2203(a)(4) 50.36(c)(1) 50.36(c)(2)

LICENSEE CONTACT FOR THIS LER (12) 50.73(a)(2)(iv) 50.73(a)(2)(v) 50.73(a)(2)(vii)

OTHER SI Ireol lowor irINRC Form 366A Mr. Mike Finissi, Electrical System Engineering Manager TELEPHONE NUMBER(11KSJde Aree Code) 616/465-5901, x2830 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPROS

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE To NPROS SUPPLEMENTAL REPORT EXPECTED (14)

YES (IfYes, complete EXPECTED SUBMISSION DATE).

X NO EXPECTED SUBMISSION DATE (15)

N H Abstract (Limitto 1400 spaces, I.e., approximately 15 single-spaced typewritten lines) (16)

On August 31, 1998, at 1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br /> EDT with Units 1 and 2 in Cold Shutdown, one bus of reserve power was lost to both units due to the failure of a station service transformer.

The Unit 1 CD Emergency Diesel Generator (EDG) and the Unit 2 CD EDG both started and picked up load. At 1830 hours0.0212 days <br />0.508 hours <br />0.00303 weeks <br />6.96315e-4 months <br /> EDT this event was reported in accordance with 10CFR50.72(b)(2)(ii), as an actuation of an Engineered Safety Feature.

This LER is therefore reported in accordance with 10CFR50.73(a)(2)(iv)

~ any event that resulted in an automatic actuation of any Engineered Safety Feature.

The root cause of this event was equipment failure. The failure of a 12kV underground cable due to age degradation caused the failure of the station service transformer.

The failed cable section was replaced, as was the failed transformer.

The 12kV cable will be replaced and a setting change to improve the coordination of the fuse/differential relay has been proposed.

The safety significance of this event was evaluated and found to be minimal. Allactions expected to occur upon a loss of power to a bus occurred as expected, including load shed and start of the CD EDGs on both units. The health and safety of the public were never jeopardized.

NRC FORM 366 (4-95)(4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATlON U.S. NUCLEAR REGULATORYCOMMISSION FACILITYNAME(1)

Cook Nuclear Plant Unit 1 DOCKET NUMBER(2) 50-315 YEAR 98 LER NUMBER (6)

SEQUENTIAL NUMBER 040 REVISION NUMBER 00 PAGE (3) 2of4 TEXT (Ifmoro space is required, use additional copies ofNRC Form (366A) (17)

Conditions Prior to Event

Unit 1 was in Mode 5, Cold Shutdown Unit 2 was in Mode 5, Cold Shutdown Descri tlon of Event On August 31, 1998, at 1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br />, the Phase 1-to-2 preferred source station service transformer faulted internally, placing a phase-to-phase fault on the 34.5kV feed to the CD reserve auxiliary transformers.

The 34.5kV lead bus differential relays, 87-TCDLD (phase 1 8 phase 2), located in the Unit 1 control room, detected this fault. Phases 1 and 2 of these relays operated to trip the 87X-T101CD and 87X-T201CD HEA lockout relays, which tripped breaker 12CD, de-energizing Reserve AuxiliaryTransformers 101CD and 201CD, and tripped the reserve feed 4kV breakers on buses 1C, 1D, 2C, and 2D. Because of the loss of voltage on the safety busses supplied from these busses, the CD Emergency Diesel Generators (EDGs) in both units started and loaded.

The loss of power to the CD busses resulted in a very brief loss of the operating Residual Heat Removal (RHR) pump in each unit. Upon auto start of the EDGs, the operators manually started the pumps and placed RHR back in service.

Cause of Event

The cause of this event was equipment failure. The failure of a 12kV underground cable due to age degradation was identified as the initiating action of this event, causing the transformer failure.

The 500KVA34.5/12kV transformer that faulted had its top blown offfrom the pressure generated by the internal fault. The two 34.5kV fuses feeding it were blown, as was the 12kV fuse protecting the phase 1 cable supplying Station Service Center ¹2. Because of the blown fuse, the cable was tested and found faulty. The fault was located and identified as a dielectric failure due to age degradation.

Anal sis of Event This event was reported via the ENS on August 31, 1998 at 1830 hours0.0212 days <br />0.508 hours <br />0.00303 weeks <br />6.96315e-4 months <br /> EDT in accordance with 10CFR50.72(b)(2)(ii), as an actuation of an Engineered Safety Feature. This LER is therefore reported in accordance with 10CFR50.73(a)(2)(iv),

any event that resulted in an automatic actuation of any Engineered Safety Feature.

The automatic responses to this event were correct and in accordance with plant design.

Upon operation of the undervoltage relays on the Train A safety busses on each unit, load shed and start of the Unit 1 and Unit 2 CD EDG occurred.

The EDGs picked up load as designed, re-supplying power to the CD busses on each unit. A summary of operations that outlines the expected and actual sequence of events is provided on the next page.

The trip of the operating Residual Heat Removal (RHR) pump for both units did not result in an increase in reactor coolant system temperature in either unit. The pumps were restarted by the operators and RHR restored.

When this event occurred, one of the Unit 2 AB battery chargers exhibited lower than normal output voltage. The redundant battery charger was put in service and battery voltages were returned to normal. The investigation of the problem is being carried out separately.(4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION FACILITYNAME(1)

Cook Nuclear Plant Unit 1 DOCKET NUMBER(2) 50-315 YEAR LER NUMBER(6)

SEQUENTIAL NUMBER REVISION NUMBER PAGE (3) 3of4 TEXT (ifmore space is required, use eddiiionel copies ofNRC Form (366A) (17)

ANALYSISOf EVENT (cont'd) 98 040

,00 When this event was reported via the ENS, it was mentioned that a Unit 1 Non-Essential Service Water pump load shed signal would not reset.

It could not be determined why the signal would not reset at that particular time, as the signal was tater reset by the next Operations shift.

Summary of Operations Expected Actual Fault detected by Lead Differential Relays Operation of T101CD and T201CD Lockout relays Tripping of 34kV CB 12CD Tripping of 4kV CBs 1C4, 1D3, 2C4 8 2D3 Operation of Undervoltage relays on Train A Safety busses on both units Load shed and Emergency Diesel Generators CD start on both units.

Auto loading of Train A safety busses-Unit 1

Auto loading of Train A safety busses-Unit 2 As expected As expected As expected As expected As expected As expected As expected; Auto start of East Component Cooling Water pump, East Essential Service Water pump,

,North Non-Essential Service Water pump As expected: Auto start of the East Component Cooling pump, East Essential Service Water pump, North Non-Essential Service Water pump The responses of the equipment and plant were evaluated for safety significance. Allactions expected to occur upon a loss of power to a single bus occurred as expected, including load shed and start of the CD EDGs on both units. The safety significance of this event is minimal and the health and safety of the public were never jeopardized.

Corrective Actions

The cable fault was located and the failed section was cut out, and the cable spliced. An adjacent cable had damage to its covering due to the failure and was also repaired.

The failed transformer was removed, and replaced with an on site spare.

The 12kV cables used for power distribution in the switchyards willbe replaced with cable having a higher voltage rating and better insulation material. The existing cable is rated 15kV; the replacement cable will be at least 19.9kV. The existing cable's insulation was made of polyethylene, with a life expectancy of 30 years.

Experience has found that the polyethylene cable typically has lasted about 25 years.

The expected life of the new cable is 40 years.

This cable is made of tree-retardant crosslinked polyethylene insulation and has a jacket to keep moisture out.

Other applications using the old style cable were considered for possible replacement.

However, it was determined that the only other application of this cable is for roadway lighting outside the protected area.

This cable willnot be replaced.

a r(4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION FACILITYNAME(1)

Cook Nuclear Plant Unit 1 OOCKETNUMBER(2) 50-315 YEAR 98 LER NUMBER (6)

SEQUENTIAL NUMBER 040 REVISION NUMBER 00 PAGE (3) 4of4 TEXT (Ifmore spsce is required, use eddi'tionel copies ofNRC Form (366A) (17)

CORRECTIVE ACTIONS (cont'd)

A setting change to improve the coordination of the fuse/differential relay has been proposed.

This would increase the pick-up point and operating time of the relay to allow the 34.5kV fuses to blow and clear the fault before the relay willpick up. This will require revision of the appropriate calculation and initiation of a relay set-point change.

Once the calculation is completed and reviewed, the possibility of a set-point change willbe evaluated.

Ifappropriate, a new relay setting sheet willbe issued.

An engineering review of the benefit of removing the station service from the CD reserve feed, and of the 34kV station design willbe performed.

Failed Com onent Identification Not Applicable

Previous Similar Events

None