ML17286A749

LER 91-009-00:on 910417,ESF Actuation & RWCU Isolation Occurred When Electricians Cut Wires to Plug of Wind Direction Recorder,Causing Voltage Drop.Caused by Equipment Installation Error.Wires reversed.W/910510 Ltr

ML17286A749
Person / Time
Site:	Columbia
Issue date:	05/10/1991
From:	John Baker, Sorensen G WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-91-094, LER-91-009, NUDOCS 9105150334
Download: ML17286A749 (8)

Text

ACCELERATED E1'RIBUTION DEMONS'ATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION,NBR:9105150334 DOC.DATE: 91/05/10 NOTARIZED: NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION SORENSEN,G.C. Washington Public Power Supply System BAKER,J.W.'ashington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 91-009-00:on 910417,ESF actuation & RWCU isolation occurred when electricians cut wires to plug of wind direction recorder, causing voltage drop. Caused by equipment D installation error. Wires reversed.W/910510 ltr.

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

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR I ENCL SIZE: S NOTES:

RECIPIENT COPIES RECIPIENT COPIES D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 . 1 D ENG,P.L. 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/ECMB 9H '1 1 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFBll 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB SD 1 1 NRR/DST/SICB 7E 1 1 NRR/DS /SPLBSD+ 1 1 NRR/DST/SRXB SE 1 1 RE/ 02/ 1 1 RES/DSIR/EIB 1 1 RGN~=HLE 01 1 1 EXTERNAL: EG&G BRYCE,J.H 3 3 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 R pv'o D

(os'gg o s7/E D

D NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOiVI Pl-37 (EXT. 20079) TO ELliVIINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES. REQUIRED: LTTR 33 ENCL 33

WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George 11'ashinglon Way ~ Richland, 1Vashinglon 99352 Docket No. 50-397 Hay 10, 1991 G02 91-094 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NUCLEAR PLANT NO. 2 LICENSEE EVENT REPORT NO.91-009

Dear Sir:

Transmitted herewith is Licensee Event Report No.91-009 for the WNP-2 Plant.

This report is submitted in response to the report requirements of 10CFR50.73 and discusses the items of reportabi lity, corrective action taken, and action taken to preclude recurrence.

Very truly yours, J. . Baker (N/D 927N)

MNP-2 Plant Nanager JWB:ac

Enclosure:

Licensee Event Report No.91-009 cc: Hr. John B, Hartin, NRC Region V Hr. C. Sorensdn', NRC Resident Inspector (H/0 901A)

INPO Records Center Atlanta, GA Hs. Dottie Sherman, ANI Hr. D. L. Williams, BPA (N/0 399)

Resident Inspector walk over copy NRC

/~vs (0'i]P 92051503""4 910 10 PDR ADOCK 0 000. 97 F'f:rR

NRC FORV. 366 V.S. NUCLEAR REGULATORY COMMISSION (64)9) APPROVED 0MB NO. 31504)104 EXPIRES: 4130192 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFOAMATION COLLECTION AEQUESTI 500 HRS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TQ THE AECORDS AND REPORTS MANAGEMENT BRANCH (P630). V.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT l31500104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) PA E 3 0 5 0 0 0 1 OF TITLE (4)

REACTOR WATER CLEANUP SYSTEM (RWCU) CONTAINMENT ISOLATION-ESF EVENT DATE (5) LER NUMBER (6I REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR  %+4 SEOUENTIAL REVISKsN FACILITYNAMES DOCKET NUMBER(SI NUMBER NUM8ER MQNTH OAY YEAR 0 5 0 0 0 0 5 0 0 0 THIS REPOAT IS SUBMITTED PURSUANT T 0 THE RLQUIREMENTS OF 10 CF R (I; IChcck onc or morc Of thc followinPI 111 OPERATING MODE (9) 20.402(8) 20.405(c) 50.73(c)(2)(iv) 73.71(8 I POWER 20 405( ~ I(1 l(0 50.36(el(1) 50.73(c)12)(v) 73.71(c)

LEVEL (10) 20.405 ( ~ I (1) (il) 50.36(cl(2) 50.73(cl(2l(riil OTHER ISpscily in Apstrsst oclow cnd ln Test, IYIIC Form 20.406(c(II I(ilil 50.7 3( ~ I (2 I (i) 50.73(c) (2)(rlill(AI 36$ AI 20.405(c) Ill(iv) 50.73(c) (2) lii) 60.73( ~ ) (2) (viil)(BI 20.40S ( ~ ) 11)( v) 60,73(c) (2)(iii) 50,73( ~ ) (2) (x I LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFAC. MANUFAC.

TUAER TUREA e;jyogc>P~SQ!'">5 y g4@@-~]

SUPPLEMENTAL REPORT EXPECTED (14) MONTH OAY YEAR EXPECTED SU 8 M I SS IO N Ilf yrt, complcts DATE (15)

YES EXPECTED SVSM/SSIDN DA TEI NO ABSTRACT ILimII to f400 spsccs, Icspprorimctrly fiftrrn sinplc sorer typcwnncn fined Ild)

On April 17, 1991 at 1251 hours0.0145 days <br />0.348 hours <br />0.00207 weeks <br />4.760055e-4 months <br />, with the plant shut down for the annual refueling outage, an Engineered Safety Feature (ESF) actuation occurred. This ESF actuation was part of a Nuclear Steam Supply Shutoff System (NS~) Group 7 isolation and involved the closure of a single valve in the Reactor Water Cleanup System (RWCU).

The isolation occurred when contractor electricians cut the wires to the plug of a wind direction recorder which was to be replaced. Although the fuse in this circuit had been pulled, an electrically hot wire to the plug still existed. The momentary grounding of the recorder power supply caused a voltage drop on other circuits in the same electrical panel, which caused a false RWCU high flow differential trip.

As an immediate corrective action, plant operators reopened the RWCU isolation valve, restarted the RWCU pump and restored the system to service.

The root cause of this event was equipment installation error which resulted in the NEUTRAL and HOT wires being switched in a junction box.

This event presented no threat to the health and safety of plant personnel or the public.

NRC Form 365 (609)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (64)9) APPROVED 0MB NO. 3) 500) 04 EXPIR ESI 4/30/92 ESTIMATED BURDEN PER AESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION AEOUESTI 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP-530). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT I3)504)104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME I)) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEQUENTIAL REVISION NVMeER NUMeeR Washin ton Nuclear TEXT /// more 4P444 ir rer)rrr)ed, Plant - Unit Irre odd(o'orre//YRC Form 3664'4/ ()7) 2 0 5 0 0 0 3 7 9 1 0 9 0OF04 Plant Condi.tions Power level - 0%

Plant mode - 5 (Refueling)

Event On April 17; 1991 at 1251 hours0.0145 days <br />0.348 hours <br />0.00207 weeks <br />4.760055e-4 months <br />, with the plant shut down for the annual refueling outage, an Engineered Safety Feature (ESF) actuation occurred. This ESF actuation was part of a Nuclear Steam Supply Shutoff System (NS4) Group 7 isolation and involved the closure of a single containment isolation valve in the Reactor Mater Cleanup System (RWCU). Contractor electricians, working under an approved plant Maintenance Work Request, were in the process of replacing the control room recorder which provides meteorological tower wind direction information. The fuse to the recorder had been removed and tagged under a plant clearance order. As part of the authorized work, the plug from the power panel to the recorder was to be changed out to match the new recorder. The electricians observed a small arc when the plug wi res were cut, immediately stopped any further work on the panel and notified the control room supervisor. The momentary electrical transient caused by cutting an energized wire to the plug resulted in a voltage dip in other systems powered from the same electrical panel, which created a false RWCU high flow differential trip.

This caused the outboard isolation valve (RWCU-V-4) in the RWCU to close and tripped the RWCU pump (RWCU-P-lA ).

Immediate Corrective Action At 1255 hours0.0145 days <br />0.349 hours <br />0.00208 weeks <br />4.775275e-4 months <br />, Plant operators opened RWCU-V-4 and restarted RWCU-P-lA, returning the system to service.

Further Evaluation and Corrective Action A. Further Evaluation

1. This event is being reported as an event that resulted in the automatic actuation of an Engineered Safety Feature under the requirements of 10CFR50.73 (a)(2)(iv). This event was previously reported on the Emergency Notification System as a four hour reportable event at 1452 hours0.0168 days <br />0.403 hours <br />0.0024 weeks <br />5.52486e-4 months <br /> on April 17, 1991.

2. The root cause of this event was determined to be equipment installation error, which resulted in the NEUTRAL and HOT leads being reversed in the junction box (JB-TCU-4. 1) between the breaker (power panel 7A-A) and the control room panel (board L). A contributing cause was less than adequate work practices, in that common practice did not include checking each wire to ground to assure the absence of voltage prior to cutting the wires.

NAC Form 366A (649)

F NRC FORM 366A US. NUCLEAR AECULATORYCOMMISSION V)4)9) APPROVED OMB NO,31500104 EXPIA ES: 4/30/92 ESTIMATED BURDEN PER AESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUESTI 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P.530), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1'HE PAPERWORK REDUCTION PROJECT (31504)104). OFFICE OF MANAGEMENTAN&BUDGET,WASHINGTON.DC 20503.

FACILI'TY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PACE (3)

YEAR SEOVENTIAL RE V ISIO N NVMQEA NVMSEA 0 5 0 0 0 OF TEXT /// more 4/>>oe re rer/oiraf, use eddic>>r>>l//RC Form 3664'4) l)2)

3. The ESF actuation was due, to an electrical transient caused by cutting the wires on the plug from the power panel to the wind direction recorder (MET-WDR-4). A clearance order for the work on the recorder had pulled and tagged the correct fuse (FBL1-F01) to the circuit, but the fuse was in fact in the neutral line of the circuit and the plug remained electrically Hhot". The source of the problem was found to be a wiring error in Junction Box JB-TCU-4.1 such that the HOT and NEUTRAL wires had been crossed. This error apparently had existed since prior to initial plant startup. The...electrical transient created by the momentary grounding of the power to the recorder plug caused a voltage dip at the panel (PP-7A-A).

4. Further investigation found that the wires had been pulled from the power panel (PP-7A-A) to the junction box (JB-TCU-4) during Plant construction on October 15, 1979. At this time, the wi'res should have been marked with the proper color coded markers. In 1982, the wires were remarked with "Duramark Mire Markers." There are no records of other, work having been done on this circuit or the equipment which would have resulted in "crossing the wires or checking the voltages on either the HOT or NEUTRAL circuits before this event occurred. It appears that this error has existed since 1979.

It is indeterminate as to why the crossed wiring was not found during initial Plant construction and subsequent startup testing. Documentation for the installation of the wiring in October 1979 shows that although

()uality Control (gC ) should have approved the installation, this step apparently was missed for this installation as there was no gC signoff on the electrical contractor's installation documentation. The work in 1982 which added new wire markers was signed off by (}C as required. However, this work did not require or include checking for correct installation, only correct marking. Current procedures require gC signoff on such work and should prevent a recurrence of this error.

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

B. Further Corrective Action A maintenance work request was written on 18 April 1991 to reverse the HOT and NEUTRAL wires in junction box JB-TCU-4.1 and assure that the wires are correctly marked.

2. The Plant electrical maintenance supervisor issued an Interoffice Memorandum to all maintenance workers informing them that prior to determing, lifting, cutting or unplugging, to include as standard practice the verifying of all wires for a potential (load), NEUTRAL and GROUND incl uded.

NRC Form 366A (64)9)

NRC FORM 366A U.S, NUCLEAR REGULATORY COMMISSION (64)9) APPROVED OMB NO. 31500)04 EXPIRES; 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUEST: 60.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (F430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555. AND TO 1HE PAPERWORK REDUCTION PROJECT (31504)104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (21 PAGE (3)

LER NUMBER (61 YEAR :IBQ sEGUENTIAL NUM ER 4j:

OX'.

RfvlsloN NUMBER Washin ton Nuclear Plant - Unit TEXT /lfmore epeoe /4 rer)oired, oee eddr)ione/NRC Form 36643/ (12) 2 0 6 0 0 0 3 7 9 1 009 0 0 0 4 OF 0 4

3. Contractor electrical supervision has informed their craft of the same precaution noted in 2 above.

4. Each control room maintenance work request work package will include the precaution contained in 2 above.

Sa fety Si ni fi c ance The RWCU and NS4 systems functioned to initiate isolation per the design requirements. The purpose of the cleanup system is to maintain reactor water purity and short outages of the RWCU system have no impact on Plant operations. There is no safety significance to this event as personnel or the public.

it posed no threat to the safety of Plant Similar Events There have been a number of other LERs, including LER 89-033 and 88-025, dealing with RWCU differential flow isolations. None of these, however, were associated with a wiring error.

EIIS Information Text Reference EIIS Reference System ~Com onent Reactor Water Cleanup System (RWCU) CE Nuclear Supply Shutoff System (NS4)

RWCU Yal ve 4 (RWCU-V-4)

RWCU Pump lA (RWCU-P-lA) CE Wind Direction Recorder (I/IET-WDR-4)

Power Panel (PP-7A-A) EC PDM NRC Form 366A (64)B)