ML18022A986

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LER 96-012-00:on 960724,SIII Inverter Was Taken OOS for Repair.Caused by Faulty ferro-resonant Transformer within Inverters Internal Circuitry.Repairs & Load Testing for Siii Were completed.W/960826 Ltr
ML18022A986
Person / Time
Site: Harris Duke Energy icon.png
Issue date: 08/26/1996
From: Donahue J, Verrilli M
CAROLINA POWER & LIGHT CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HNP-96-142, LER-96-012, LER-96-12, NUDOCS 9609030388
Download: ML18022A986 (7)
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Text

CATEGORY 1 REGULATORY INFORMATION DISTRIBUTION SYSTEM

~ (RIDS)

ACCESSION NBR:9609030388 DOC.DATE: 96/08/26 NOTARIZED: NO DOCKET FACIL:50-400 Shearon Harris Nuclear Power Plant, Unit 1, Carolina 05000400

-AUTH. NAME AUTHOR AFFILIATION VERRILLZ,M. Carolina Power 6 Light Co.

DONAHUE,J.W. Carolina Power '& Light Co.

RECZP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 96-012-00:on 960724,SIII inverter was taken OOS for repair.W/plant in mode 1 at 100% power. Caused by faulty fer.ro-resonant transformer within inverter's.Repairs a load testing for SIZZ inverter were completed.W/960826 ltr.

DISTRIBUTION CODE: ZE22T COPIES RECEIVED:LTR ENCL SIZE:

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

NOTES:Application for permit renewal filed. 05000400 G 0

RECIPIENT COPIES RECIPIENT COPIES ZD CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-1 PD 1 1 LE,N 1 1 INTERNAL: ACRS 1 1 AEOD S AB 2 2 AEOD/SPD/RRAB 1 1 1 1 NRR/DE/ECGB 1 1 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 D RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 N

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN 5D-5(EXT. 415-2083) TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 26 ENCL 26

Carolina Power 8 Light Company Harris Nuclear Plant PO 8ox )65 New Hill NC 27562 AUG 2 6 1996 U.S. Nuclear Regulatory Commission Serial: HNP-96-142 ATTN: NRC Document Control Desk 10CFR50.73 Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT UNIT 1 DOCKET NO. 50-400 LICENSE NO. NPF-63 LICENSEE EVENT REPORT 96-012-00 Sir or Madam:

In accordance with Title 10 to the Code of Federal Regulations, the enclosed Licensee Event Report is submitted. This report describes a Technical Specification 3.0.3 entry that occurred on July 25, 1996.

Sincerely, J. W. Donahue Director of Site Operations Harris Plant MV Enclosure c: Mr. J. B. Brady (HNP Senior NRC Resident)

Mr. S. D. Ebneter (NRC Regional Administrator, RegionII)

Mr. N. B. Le (NRC Project Manager- NRR) 9609030388 960826 PDR ADOCK 05000400 S PDR State Road H34 New Hill NC

II I NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 (4 95) EXPIRES 04/30/96 ESt(MATEO BURDEN PER RESPONSE'O COMPLY WITH THIS MANDATORY UIFORMATIDN COllECTION REDDEST: 500 HRS, REPORTED LESSONS lEARNEO ARE LXCENSEE EVENT REPORT (LER) U(CORPDRATEO INTO THE UCENSING PROCESS ANO FEO BACK TO U(OUSTRT.

fORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE (NFORMATION ANO RECORDS MANAGEMENt BRANCH IT.6 F33L US. NUClEAR REGUUITORT COMMISSION.

(See reverse for required number of WASHU(GTON, OC 20555000). AND TO THE PAPERWORK REDUCTION PROJECT (3150.

digits/characters for each block) 0104L Off(CE OF MANAGEMEN'r AND BUDGET, WASHINGTON, OC 205(KL FACILITY NAME (I) DOCKET NUMBER (2) PAGE (3)

Harris Nuclear Plant Unit-1 50-400 1 OF 2 TITLE (4)

Technical Specification entry when transferring the SIII Instrument Bus back to the'inverter with RWST level transmitter LT-993 out of service.

EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (6)

FACIUTY NAME DOCKET NUMBER SEOUENTIAL REVISION MONTH OAY YEAR MONTH OAY YEAR NULlBER NUMBER 05000 FACILITYNAME DOCKET NUMBER 25 96 96 012 0 8 26 96 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR BI (Check one or moro) (11) iMiODE (9) 20.2201(b) 20.2203(a)(2)(v) )( 50.73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a) (1) 20.2203(a)(3)(i) 50. 73(a) (2) (ii) 50.73(a)(2)(x)

LEVEL (10) 100% 20.2203(a)(3) (ii) 50.73(a)(2)(iii) 73.71 20.2203(a)(2)(i) 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv) OTHER 20.2203(a) (2) (iii) 50.36(c)(1) 50.73(a)(2)(v) Specify in Abstract below or in NRC Form 366A 20.2203(a)(2)(iv) 50.36(c) (2) 50.73(a) (2) (vii)

LICENSEE CONTACT FOR THIS LER (12)

TELEPHONE NUMBER (Incrude Area Code)

Michael Verrl)(i Sr. Analyst - Licensing (919) 362-2303 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

REPORTABLE REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TO NPROS TO NPROS ED INVT W121 JE LT ,8080 Y SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH OAY YEAR YES SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE). X NO DATE (15)

ABSTRACT (Limit to 1400 spaces, i.a., approximately 15 single.spaced typewritten lines) (16)

At approximately 2158 hours0.025 days <br />0.599 hours <br />0.00357 weeks <br />8.21119e-4 months <br /> on July 24, 1996, with the plant in i>lode at 100% power, the SIII Inverter was taken out of 1

service for repair and at approximately 2219, the SIII instrument bus was aligned to the alternate power supply. Technical Specifications require the instrument bus to be re-energized from its associated inverter connected to its associated DC power supply within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or commence plant shutdown. At approximately 0009 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> on July 25, 1996, Refueling Water Storage Tank (RWST) Level Transmitter LT-993 was declared inoperable due to spiking observed by control room personnel. Estimated time to restore LT-993 exceeded the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> requirement to reconnect the SIII instrument bus to the SIII Inverter. Due to these conditions, Technical Specification 3.0.3 was entered at approximately 1623 hours0.0188 days <br />0.451 hours <br />0.00268 weeks <br />6.175515e-4 months <br /> when the SIII instrument bus was de-energized for 12 minutes to transfer it back to its normal source (SIII Inverter), coincident with LT-993 being inoperable. Entry into Technical Specification 3.0.3 was required since RWST Level Transmitter LT-993 is a channel IV instrument and, during the 12 minute transfer period, channel III RWST level transmitter LT-992 was disabled by de-energizing the SIII instrument bus, thereby removing two of the four RWST level transmitters from service.

Technical Specification 3.0.3 was exited at approximately 1635 upon completion of the instrument bus power supply transfer process.

The above scenario and the need to enter Technical Specification 3.0.3 was identified, discussed in advance and evaluated by plant management and the Plant Nuclear Safety Comminee. The decision to allow a one-time, short duration Technical Specification 3.0.3 entry to transfer the SIII instrument bus to its normal power source was based on the following: (1) technical specifications allow two out of four RWST level transmitters to be bypassed for up to two hours for surveillance testing, thereby bounding the condition, and (2) transferring the SIII instrument bus back to the SIII Invcrter places the 120 Volt Engineered Safety Feature Uninteruptable AC System in its preferred, design configuration which provides the most reliable instrument bus power supply source, and (3) this evolution did not present an adverse impact to plant safety.

N )

NRC FORM 366A U.S. NUC(EAR REOU(ATORT COMMISSION (4 BQ LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACI(ITT NAME (ll OOCNET lER NUMBER (6) PACE (3)

SEOUENTIAL R(V SION TEAR NUMBER NUMBER Shearon Harris Nuclear Plant ~ Unit N1 50400 2 OF 2 96 - 012 - 00 TEXT Pr msuu spusu is suuui ssr usu uditrmml supms ul At))C Fmm 36QS (I 7)

EVENT DESCRIPTION:

At approximately 2158 hours0.025 days <br />0.599 hours <br />0.00357 weeks <br />8.21119e-4 months <br /> on July 24, 1996, with the plant in Mode 1 at 100% power, the 7.5 KVA SIII Instrument Inverter (EIIS Code: ED-INVT) was taken out of service to allow for repairs and at approximately 2219, the SIII instrument bus (1DP-1A-SIII) was aligned to the alternate AC power supply (120 Volt Power Panel 1A311-SA). The SIII Inverter had recently experienced an approximate 50% degraded output voltage condition which was caused by a faulty ferro-resonant transformer. Post maintenance load testing of the SIII Inverter, following replacement of the bad transformer, was completed at approximately 1225 hours0.0142 days <br />0.34 hours <br />0.00203 weeks <br />4.661125e-4 months <br /> on July 25, 1996. Harris Nuclear Plant Technical Specification 3.8.3.1 (Electrical Power Systems - Onsite Power Distribution) Action c requires the instrument bus to be re-energized from its associated inverter connected to its associated DC power supply within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or commence plant shutdown.

At approximately 0009 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> on July 25, 1996, Refueling Water Storage Tank (RWST) level transmitter LT-993 (EIIS Code: JE-LT) was observed to be declared inoperable due to spiking observed by control room personnel. To return LT-993 to service, the transmitter and power supply card would need to be replaced and time estimates to complete these actions indicated that the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> requirement to reconnect the SIII instrument bus to the SIII Inverter would be exceeded.

Due to these conditions, Technical Specification 3.0.3 was entered at approximately 1623 hours0.0188 days <br />0.451 hours <br />0.00268 weeks <br />6.175515e-4 months <br /> when the SIII instrument bus was de-energized for 12 minutes to transfer it back to its normal source (SIII Inverter), coincident with LT-993 being inoperable.'ntry into Technical Specification 3.0.3 was required since RWST level transmitter LT-993 is a channel IV instrument and during the 12 minute transfer period, channel III RWST level transmitter LT-992 was disabled by de-energizing the SIII instrument bus, thereby removing two of the four RWST level transmitters from service. Technical Specification 3.0.3 was exited at approximately 1635 upon completion of the instrument bus power supply transfer process.

The above scenario and the need to enter Technical Specification 3.0.3 was identified, discussed in advance and evaluated by plant management and the Plant Nuclear Safety Committee. The decision to allow a one-time, short duration Technical Specification 3.0.3 entry to transfer the SIII instrument bus to its normal power source was based on the following: (1) technical specifications allow two out of four RWST level transmitters to be bypassed for up to two hours for surveillance testing, thereby bounding the condition, and (2) transferring the SIII instrument bus back to the SIII Inverter places the 120 Volt Engineered Safety Feature (ESF) Uninteruptable AC System in its preferred, design configuration which provides the most reliable instrument bus power supply source, and (3) this evolution did not present an adverse impact to plant safety.

CAUSE:

The failure of the SIII Inverter was attributed to a faulty ferro-resonant transformer within the inverter's internal circuitry.

The cause of the RWST Level Transmitter, LT-993 was caused by either a bad power supply circuit board card or a malfunction within the level transmitter itself. The Technical Specification 3.0.3 entry was reviewed and approved in advance by plant management and the Plant Nuclear Safety Committee.

SAFETY SIGNIFICANCE:

There were no safety consequences as a result of this event. The short duration Technical Specification 3.0.3 entry to transfer the SIII instrument bus back to the SIII Inverter presented no adverse impact to plant safety based on the fact that technical specifications allow two out of four RWST level transmitters to be bypassed for up to two hours for surveillance testing, thereby bounding the condition. Transferring the SIII instrument bus back to the SIII Inverter places the 120 Volt ESF Uninteruptable AC System in its preferred, design configuration which provides the most reliable source of power to the instrument bus. This event is being reported per 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by technical specifications.

PREVIOUS SIMILAR EVENTS:

There have been no other Technical Specification 3.0.3 entries to re-align the 120 Volt ESF Uninterruptable AC System.

CORRECTIVE ACTIONS COMPLETED:

1. Repairs and load testing for the SIII Inverter were completed at approximately 1225 hours0.0142 days <br />0.34 hours <br />0.00203 weeks <br />4.661125e-4 months <br /> on July 25, 1996.
2. Replacement of the LT-993 RWST level transmitter and power supply card and subsequent post-maintenance acceptance testing were completed at approximately 2050 hours0.0237 days <br />0.569 hours <br />0.00339 weeks <br />7.80025e-4 months <br /> on July 26, 1996.

RM 3 A (4-95)

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