ML17290A251

LER 93-014-00:on 930325,five Electrical Lighting Circuits Associated W/Primary Containment Found Not Turned Off During Plant Operation.Caused by Less than Adequate Design Analysis Change.Plant Procedure PPM 1.3.4 changed.W/930423 Ltr

ML17290A251
Person / Time
Site:	Columbia
Issue date:	04/23/1993
From:	Fies C, Parrish J WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-93-093, GO2-93-93, LER-93-014, LER-93-14, NUDOCS 9304290026
Download: ML17290A251 (7)

Text

ACCELERATED DOCUMEYT DISTRIBUTION SYSTEM RESUL)RY INFORMATION DISTRIBUT SYSTEM (RIDE)

ACCESSION NBR:9304290026 DOC.DATE: 93/04/23 NOTARIZED: NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION FIES,C.L. Washington Public Power Supply System-PARRISH,J.V. Washington Public Power Supply System R RECIP.NAME RECIPIENT AFF'ILIATION

SUBJECT:

LER 93-014-00:on 930325,identified five electrical lighting circuits associ.'ated w/primary containment not turned off 6 did not have adequate overcurrent protection. Caused by less adequate design analysis.TS a FSAR changed.W/930423 ltr. S 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 D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL ONDD LA 1 1 ONDD PD 1 1 CLXFFORD,J 1 1 D INTERNAL: ACNW 2 . 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRIL/RPEB 1 1 NRR/DRSS/PRPB 2 2 RR+)S/SPLB 1 1 NRR/DSSA/SRXB 1 1 REG FILE 02 1 1 RES/DSIR/EXB 1 1 RGNS FILE 01 1 1 EXTERNAL'G&G BRYCE F J ~ H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POORE,W. 1 1 NUDOCS FULL TXT 1 1 A

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PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESV, ROOM Pl-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T HEED!

A FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUZRED: LTTR 32 ENCL 32,

WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 99352 April'23, 1993 G02-93-093 Docket No. 50-397 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NUCLEAR PLANT WNP-2, OPERATING LICENSE NPF-21 LICENSEE EVENT REPORT NO.93-014 Transmitted herewith is Licensee Event Report No.93-014 for the WNP-2 Plant. This report is submitted in response to the report requirements of 10CFR50.73 and discusses the items of reportability, corrective action taken, and action taken to preclude recurrence.

Sincerely, J. V. Parrish Assistant Managing Director, Operations JVP/CLF/jd Enclosure Mr. J. B. Martin, NRC - Region V Mr. R. Barr, NRC Resident Inspector (Mail Drop 901A, 2 Copies)

INPO Records Center - Atlanta, GA Mr. D. L. Williams, BPA (Mail Drop 399) 930429002b 930423 PDR ADOCK 05000397 S PDR

LICENSEE HtT REPORT (LER)

AGILITY NAHE (1) DOCKET NUHB R ( ) PAGE (3)

Washin ton Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 I OF ITLE (4)

INADEQUATEBACKUP OVERCURRENT PROTECTION FOR CONTAINMENTPENETRATIONS EVENT DATE (5) LER NUHBER 6 REPORT DATE (7) OTHER FACILITIES INVOLVED (6)

HDNTH DAY YEAR YEAR SEQUENTIAL EV IS ION HONTH DAY YEAR FACILITY NAHES CKE HUHB R (5)

NUHBER UMBER 5 0 0 3 2 5 9 3 9 3 0 1 4 0 0 0 4 2 3 9 3 50 PERATING HIS REPORT IS SUBHITTED PURSUANT TO THE REQUIREHENTS OF 10 CFR 5: (Check one or more of the following) (11 ODE (9) I OWER LEVEL 0.402(b) 0.405(C) 0.73(a)(2)(iv) 77.71(b)

(io) 0.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.73(c) 0.405(a)(1)(ii) 50.36(c)(2) 0.73(a)(2)(vii) THER (Specify in Abstract 20.405(a)(1)(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) elow and in Text, NRC 20.405(a) (1) ( iv) 50.73(8)(2)(ii) 50.73(a)(2)(viii)(B) orm 366A) 0.405(a)(1)(v) 0.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER (12)

TELEPHOHE NUHBER C. L. Fies, Licensing Engineer REA CODE 0 9 7 7 - 4 1 4 7 COHPLETE OHE LINE FOR EACH COHPOHEHT FAILURE DESCRIBED IH THIS REPORT (13)

CAUSE SYSTEH COHPOHEHT HAHUFACTURER EPORTABLE CAUSE SYSTEH COHPDHEHT HAHUFACTURER EPORTABLE 0 HPRDS TO HPRDS SUPPLEHEHTAL REPORT EXPECTED (14) EXPECTED SUBHISSIOH HOHTH DAY YEAR ATE (15)

YES (If yes, complete EXPECTED SUBHISSIOH DATE) HO TRACT neI On March 25, 1993, an Electrical Engineer found five electrical lighting circuits associated with Primary Containment that were not turned off during plant operation and did not have adequate backup overcurrent protection. This condition could cause failure of the impacted Primary Containment electrical penetrations. This problem was discovered as part of an Electrical Calculation Improvement Program being carried out by Engineering at WNP-2. All circuits entering Primary Containment must be properly protected with primary and secondary overcurrent protection or shut off procedurally during power operation. It was found that procedures did not address shutting off five circuits that feed 120 volt receptacles within containment. The backup protection to these circuits was found to be too large to protect the containment penetrations.

Immediate action was taken by opening the breakers feeding the five involved electrical circuits.

The root cause of this event was a less than adequate design analysis change prepared using inaccurate and incomplete documentation.

Further corrective action was taken by changing Plant Procedure PPM 1.3.4, Operating Data and Logs, to require the impacted circuit breakers be verified in the tripped condition at least once per day when the plant is in modes 1, 2, or 3. In addition, the Technical Specifications and the FSAR are being changed to reflect the condition of the circuits.

The event posed no threat to the health and safety of either the public or plant personnel.

LICENSEE EVENT REPOR.ER)

TEXT CONTINUATION AGILITY KAHE (1) DOCKET KUHBER (2) LER KUHBER (8) AGE (3) ear umber ev. Ko.

Washington Nuclear Plant -,Unit 2 0 5 0 0 0 3 9 7 3 14 .-

0 2 F 5 ITLE (4)"

INADEOUATE. BACKUP OVERCURRENT PROTECTION FOR CONTAINMENT PENETRATIONS PI n ii n Power Level - 99%

PlantMode -1

'ven D ri i n On March 25, 1993, an Electrical Engineer found five electrical lighting circuits that were not required by procedure to be shutoff during power operation. With the associated breakers closed and with inadequate backup overcurrent protection an overcurrent condition in conjunction with the single failure of the primary overcurrent protection device could cause failure of the involved Primary Containment electrical penetrations. This problem was discovered as part of an Electrical Calculation Improvement Program being carried out by Engineering at WNP-2. The original calculation (Calculation Number 02.03.12) provided to the Supply System by the architectural engineer was being updated to verify compliance with Regulatory Guide 1.63, Electric Penetration Assemblies in Containment Structures for Nuclear Power Plants, by checking the overcurrent protection of each wire. During the update of this calculation, it was found that the following lighting circuits for the Primary Containment were not procedurally controlled and did not have adequate backup overcurrent protection for their penetrations.

Circuit No. 19 & 21 of Lighting Panel E-LP-3DAC Circuit No. 16 & 17 of Lighting Panel E-LP-6BAC Circuit No. 19 of Lighting Panel E-LP-6BAB Imm iae rr iv Aci action was taken by opening the breakers feeding the five involved electrical circuits which n'ompensatory feed 120 volt outlets in Primary Containment.

u h rEvl ionR n rr iv A i n A. Further Evaluation

1. This event is being reported per the requirements of 10CFR50.73(a)(2)(ii)(B) as condition that was outside the design basis of the plant.... The event was also called in

"... a to the NRC Operations Center as required by 10CFR50.72(b)(1)(ii)(B).

I ICENSEE EVENT REPORQLER)

TEXT CONTINUATION AGILITY NAHE (1) OOCKET NUHBER (2) LER NUHBER (8) AGE (3) ear umber ev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 3 014 00 3 F 5 1TLE (4)

INADEQUATE BACKUP OVERCURRENT PROTECTION FOR CONTAINMENT PENETRATIONS

2. Interviews with engineering personnel disclosed that in the late 1970s the Three Mile Island Accident raised a concern about ignition sources in the Primary Containment. As part of this concern, potential ignition sources were evaluated in the containment including lighting circuits. It was determined that all lighting in the containment would be deenergized and procedurally controlled in modes 1 through 3. In February 1982, the original draft of the Technical Specifications added Section 3,8.4.1 that listed two Lighting Panels supplying circuits'nside Primary Containment. The interviews identified that the circuits described in this LER should have been part of that amendment.

3. A review of the WNP-2 electrical penetrations to verify compliance to Regulatory Guide 1.63 was performed in 1981. The result of this review was documented in the Supply System response to FSAR question 040.034. Tables associated with the response to this question list approximately 300 line items where penetration conductors, circuit data, and

~

both primary and secondary overcurrent devices are listed.

4. The evaluation performed in 1981 made incorrect assumptions and contained errors associated with the plotting of the I't characteristics for the No, 10 AWG conductors for the Westinghouse supplied penetrations. The most significant of the incorrect assumptions was that all breakers from various manufacturers have similar characteristics. Although the characteristics may be similar between manufacturers, there were enough differences to lead to improper conclusions. In addition, the curves developed as part of calculation 02.03.12 consistently reflect a higher current carrying capability than the curves provided by Westinghouse for the electrical penetrations. This resulted in the identification of the five circuits with inadequate backup overcurrent protection. Primary overcurrent protection devices are properly sized.

5. This event was discovered as part of the Electrical Engineering Calculation Improvement Program. Because this effort is not complete it may generate additional reportable items.

These will be reported as revisions to this LER.

6. There were no structures, components, or systems that were inoperable prior to the start of this event that contributed to the event.

Ra~am The root cause of this event was a less than adequate design analysis change prepared using inaccurate and incomplete documentation prior to plant operation. This led to the approval and installation of a design that was not in compliance with regulatory requirements.

LICENSEE EVENT REPOR.ER)

TEXT CONTINUATION AGILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (8) AGE (3) ear umber ev. No.

Washington Nucleaz Plant - Unit 2 0 5 0 0 0 3 9 7 3 1 4 4 F 5 ITLE (4)

INADEQUATE BACKUP OVERCURRENT PROTECTION FOR CONTAINMENT PENETRATIONS C. hr rr A i Plant Procedure PPM 1.3.4, Operating Data and Logs, was changed to require breakers for LP-3D-A-C circuits 19 and 21, LP-6B-A-C circuits 16 and 17, and LP-6B-A-B circuit 19 be verified in the tripped condition at least once per day when the plant is in modes 1, 2, or 3.

2. Technical Specification 3.8.4.1, AC Circuits Inside Piimary Containment will be modified.

The additional circuit breakers that required deenergization will be added or Generic Letter 91-08 will be used to remove this list of equipment from the Technical Specifications.

This request to revise the Technical Specification will be made by September 30, 1993.

The response to FSAR Question 040.034" will be modified to eliminate the circuits that do not have adequate redundant overcurrent protection. This will be completed by October 29, 1993.

4. Electrical distribution system calculations are currently being reviewed and updated on an ongoing basis under the Calculation Improvement Program. The condition described in this report involved an update of the calculation on Primary Containment Electrical Penetration Short Circuit Capability. Update of this calculation is expected to be complete by October 29, 1993.

fe i nifi The circuits associated with this event feed electrical receptacles inside Primary Containment. During power operation the Primary Containment is normally inerted and no equipment is operated from these .

receptacles. The receptacles are mainly used during refueling outages when Primary Containment is not required. The circuit breakers feeding these circuits protect the penetration if a fault occurs. There is a low probability of having high fault currents at the time Primary Containment is needed (Loss of Coolant Accident conditions) combined with the failure of the primary overcurrent protection device. It is concluded there is no safety significance associated with this event.

imil r Ev n There have been no similar events involving adequacy of overcurrent protection of electrical penetrations.

There have been other reportable events associated with electrical calculations. LERs89-034 and 92-027 were written on inadequate coordination of undervoltage protection on 480 volt Motor Control Centers.

LER 91-033 discussed inadequate fuse coordination on the 250 volt DC system. LER 93-003 documented inadequate coordination of primary undervoltage on the 4.16 kV vital buses.

LICENSEE EVENT REPOFLER)

TEXT.CONTINUATION FACILITY NAME (I) OOCKET NUMBER (2) LER NUMBER (8) AGE (3) ear umber ev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 3 I 4 0 ~

5 F 5 ITLE (4)

INADEIOUATE BACKUP OVERCURRENT PROTECTION FOR CONTAINMENT PENETRATIONS II Infrm i n T x R feren E~Ef

~pm Q~m~nen Primary Containment BD Lighting Panel E-LP-3DAC 'C LP Lighting Panel E-LP-6BAC EC LP Lighting Panel E-LP-6BAB EC LP