ML17286A839

LER 91-010-00:on 910422,potential Inability to Isolate Primary Containment Noted Due to Wiring Separation Error. Caused by Inadequate Work Instructions.Sgt Drawings Revised & MSLC Separation Problems corrected.W/910522 Ltr

ML17286A839
Person / Time
Site:	Columbia
Issue date:	05/22/1991
From:	John Baker, Reis M WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-91-106, LER-91-010, LER-91-10, NUDOCS 9105310156
Download: ML17286A839 (7)

Text

ACCELERATED DI BUTION DEMONST TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9105310156 DOC.DATE: 91/05/22 NOTARIZED: NO DOCKET g FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION REIS,M.P. Washington Public Power Supply System BAKER,J.W. Washington Public Power Supply Syst: em RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 91-010-00:on 910422,potentially inability to isolate primary containment occurred due to wiring separation error. D Caused by inadequate work instructions.SGT drawings revised 6 MSLC separation problems corrected.W/910522 ltr.

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 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/LHFB11 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/SICBSH3 1 1 ~~SPLBSD1 1 1 NRR/DST/SRXB SE 1 1 REG FILE 02 1 1 RES/DSIR/EIB 1 1 GN LE 01 1 1 EXTERNAL EGGG BRYCE I J H

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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

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D NOTE TO ALL "RIDS" RECIPIENTS:

S PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISCI'RIBUTION LISIS 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. Bov 968 ~ 3000 George t1'ashhg~to>> l1'ay ~ Riehla>>d, 11'ashhq>to>> 9935 Docket No. 50-397 May 22, 1991 G02-91-106 Document Control Desk U.S. Nuclear Regulatory Commission Washington, O.C. 20555

Subject:

NUCLEAR PLANT NO. 2 LICENSEE EVENT REPORT NO.91-010

Dear Sir:

Transmitted herewith is Licensee Event Report No.91-010 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, H7 J. W. Baker (H/0 927M)

WNP-2 Plant Hanager JWB:ac

Enclosure:

Licensee Event Report No.91-010 t

cc: Hr. John B. Hartin, NRC Region V Hr. C. Sorensen, NRC Resident Inspector (H/0 901A)

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

NRC Resident Inspector walk over copy 0f5Q f10 pi053$ADOCK t:>50003%7 PDF( PDR

NRC FOAM 366 U.S. NUCLEAR REGULATORY COMMISSION (54)9) APPAOVEO OMB NO. 3(504)104 EXPIRES: 4/30I92 ESTIMATED BVADEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION AEOUEST: 50.0 HAS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS ANO REPOATS MANAGEMENT BRANCH (F030), U.S. NUCLEAR AEGULATOAYCOMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET,WASHINGTON, DC 20503.

1l(ll FACILITY NAME (11 DOCKET NUMBER 12) PAGE 3l Washington Nuclear Plant - Unit 2 0 5 o o o 39 7 q oF05 TITLE (4)

SEPARATION ERROR CAUSED BY INADEQUATE WORK INSTRUCTIONS EVENT DATE (5) LFR NUMBER (6I REPORT DATE 17) OTHER FACILITIES INVOLVED (5)

MONTH DAY YEAR YEAA SEOVENTIAL K'R: R r. VISION MONTH OAY YEAA FACILITYNAMES DOCKET NUMBERISI NUMBER NUMBER 0 5 0 0 0 0 4 2 2 91 9 1 ill 1 0 0 0 0 5 29 1 0 5 0 0 0 OPERATING 20.405(el( IS SUBMITTED PUASVANT T 0 THE ALOUIREMENTS OF 10 CF R ()I (Check onr or mo THIS REPORT e of mr fottovnngl Ill MODE (9) 20.402(S) 20.405(cl 60,73(el(2) I(s) 73.71(S)

POWE R 60.35(c)ll) 60.73( ~ )(2)(vl 73.71(cl LEYEL (10) .

0 0 0 20.40$ (~ I (I) (il) 60.35 (c) (2) 50.73( ~ l(21(vQI OTHER ISprcily in Apsrrecr Or to vs r svf in Tr r r. SVRC Form 20.405( ~ ) Alii 50.73(e)12) (I) 60.73(el(2)(rIII)(A) 36SAI 20A05( ~ ) (I Illv) 60.73( ~ ) (2) lg) 50.73(e) (21(rill l(B) 20AOS(el(1) Iv) 50.73(el(2)(ill) 60.73( ~ l(2) (r)

LICENSEE CONTACT FOR THIS LER 1121 NAME TELEPHONE NUMBER AREA CODE M. P. Reis, Compliance Engineer 50 37 7- 385 COMPLETE ONE LINE FOA EACH COMPONENT FAILURE OESCAISED IN THIS REPOAT 113)

MANUFAC EPOATABLE

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CAUSE SYSTEM COMPONENT CAUSE SYSTEM COMPONENT TUAER TURER TO NPAOS LAN sNRoy . Xn

~j+g py SUPPLEMENTAL REPORT EXPECTED (141 MONTH OAY YEAR EXPECTED SUBMISSION DATE (ISI YES Illyrs, complete EXPECTED $ (IBcrlSSIOsy DATEI NO ABBTRAcT ILlmlt to le00 sprees. I r., rppsosimetrly lilrern single spree rypewnrren linesl 115)

On March 8, 1991, during the performance of Single Failure Analysis studies, Design Engineering personnel discovered a wiring separation error affecting the containment isolation valves for the Reactor Recirculation (RRC) flow control valve hydraulic supply. On April 22, 1991, after evaluation of the nature and extent of the identified problems, it was concluded that a "smart short" could prevent primary This is a condition which containment isolation of up to four, 1N diameter lines.

alone could have prevented the safety function of the RRC hydraulic isolation valves.

Accessible areas through which the affected circuits run were immediately included on an hourly fire tour.

r This condition was caused by inadequate work instructions issued by the Architect Engineer during initial plant construction.

RRC wiring errors will be corrected during the ongoing R6 refueling outage.

No safety significance is attributed to this condition. Routine surveillance has shown these valves to be highly reliable and the probability of the valves actually affecting the containment function is extremely low. Accordingly, this event did not affect the health and safety of either the public or plant personnel.

NRC Form 366 (54)9)

NAC FORM 386A V.S. NUCLEAR 4EGVLATOAYCOMMISSION (668) APPROVEO OMS NO, 3 )504106 EXPIRES: 6/30/02 ESTIMATED BURDEN PEA RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUESTI 60.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECOAOS TEXT CONTINUATION ANO 4EPOATS MANAGEMENT BRANCH IP430). U.S. NUCLEAR 4 EGVLATO4Y COMMISSION, WASHINGTON, OC 20555, ANO TO THE PAPERWORK AEOUCTION PROJECT )31504)04), OFFICE OF MANAGEMENTANO BUDGET. WASHINGTON. DC 20503.

FACILITY NAME II) DOCKE'T NUMBER )2) LEA NUMBER IS) PAGE ISI SEOUENTIAL REVISION YEAR gg NUMSEII NUMOER Washin ton Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 9 1 010 0 00 2oFO 5 TEXT lrlmore Jrreoe /r rer)v/)ed. vee odd/door/HRC /orm 366A'J/ l)T)

Plant Conditions Plant Mode Refueling Plant Level - 5%

Event Descri tion On March 8, 1991, during the performance of Single Failure Analysis studies, Design Engineering personnel discovered a wiring separation error affecting the containment isolation valves for the Reactor Recirculation Cooling (RRC) flow control valve hydraulic supply. On April 22, 1991, after evaluation by Technical and Engineering personnel of the nature and extent of the identified problems, a "smart short" could prevent isolation of up to four 14 diameter hydraulic lines.

it was concluded that While performing a single failure analysis for the Standby Gas Treatment (SGT) system, Supply System engineers found what appeared to be a violation of "Separation within Division" design specifications. It was later determined that actual SGT field configuration was correct and that confusing notes on the SGT drawings led the engineers to believe there was a problem. Based on the SGT discrepancies, engineering investigated the other two systems which have similar intra-divisional separation criteria. That investigation revealed that proper separation was not maintained for certain components in the Main Steam Leakage Control (MSLC) system, in addition to the RRC hydraulic valves.

Engineering analysis concluded that the MSLC wiring concerns would not result in loss of system or containment isolation function.

Immediate Corrective Action Upon initial reporting of the problem, an hourly fire tour was initiated for accessible areas in which the wires were not properly separated.

Further Evaluation and 'Corrective Action A. Further Evaluation

l. This condition is reported under the requirements of 10CFR50.73(a)(2)(v), a condition that alone could have prevented the fulfillment of the safety function of a structure needed to control the release of radioactive material.

In addition, the condition was determined to be reportable under 10CFR50.72(b)(1)(iii)(C). The NRC Operations Center was notified at 0907 hours0.0105 days <br />0.252 hours <br />0.0015 weeks <br />3.451135e-4 months <br /> on April 22, 1991.

2. No other systems, structures or components were inoperable which contributed to this condition.

NRC Form 386A I640)

( ~ NRC FORM 266A U.S. NUCLEAR REGULATORY COMMISSION (689) APPROVEO 0MB NO. S)504I04 E X P I R E6 I'6/20/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION RFOUEST: 50,0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP-520), U.S. NUCLEAR RFGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUC'TION PRO/ECT (215041(M). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20502.

F AC I LIT Y NAME I I ) DOCKET NUMBER (1) LER NUMBER (6) PAGE LT)

YEAR iqg9 SEOUENTIAL '~P IIEVOION

'6 NUM864 . NUMBER Washin ton Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 010 0 0 0 3o0 5 TEXT //f mon opoco/o movkod, ooo odd/dono//VRC Form 266A's/ ILT)

3. The root cause for this condition is Procedures Less Than Adequate/Work Instructions Inadequate. The RRC wiring separation problem has existed since initial plant construction. Engineering direction issued by the Architect Engineer to correct initial intra-divisional separation errors were not consistently carried over into the work instructions. Deficiencies noted on work instructions for intra-divisional separation include: drawing notes required separation for one end of a cable but not the other; field routing instructions (conduit routing instruction, cable pull slips) were not specific as to separation requirements; installation of fire-proofing material (Siltemp) was not specified in some instructions and in others was a drawing note rather than a specific installation instruction.

4~ Certain plant systems have special tequirements for wiring separation within a division (intra-divisional separation). System operational reliability requires'edundant components within a train or subsystem to be energized from the same power source rather than from independent power sources. However, to protect against a single failure compromising redundant components, the wiring to intra-divisionally separated components cannot be routed together.

One system requiring intra-divisional separation is the hydraulic control system (HY) for, the two RRC Flow Control Valves [RRC-FCV-60A(B) j. The hydraulic source is located outside of Primary Containment. Each FCV has four hydraulic lines associated with it, for a total of eight hydraulic lines which penetrate Primary Containment. Each hydraulic line has two isolation valves, both of which are located outside of the Primary Containment. To ensure that loss of a single power source would not affect both FCVs, the isolation valves associated with RRC-FCV-60A are all powered from critical Division I and those associated with RRC-FCV- 60B from Division II. As a result, the wiring for the redundant isolation valves cannot be run in the same conduit or cable sections.

During Single Failure Analysis studies, Design Engineering personnel discovered control wiring separation errors which affect the hydraulic line isolation valves. A 'single failure (e.g. a "smart short") could potentially preclude isolation of the hydraulic lines for one FCV. Since the isolation valves associated with RRC-FCV-60A and RRC-FCV-60B are powered from different divisions, a single failure would not compromise both sets of isolation valves.

Further investigation focused on the hydraulic piping inside containment. This investigation revealed that, while the pipes would withstand seismic loading, there was no assurance that the piping would survive other postulated accident loadings (jet impingement, pipe whip, etc). Consequently that a single failure could prevent the containment isolation function and it was determined potentially allow release of radionuclides to the reactor building during accident conditions.

NRC Form 266A (6 69)

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NRC FORM SBBA US. NUCLEAR REGULATORY COMMISSION API'ROVED OMB NO. S)50010S 1580)

EXPIRES: siSOI02 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P.520). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT 12)500)04). OFFICE OF MANAGEMENTANO BUDGET,WASHINGTON, OC 20502.

FACILITY NAME I I) DOCKET'UMBER 121 LER NUMBER (5) PAGE IS) sEQUENTIAL gP)o Asvu)10M NUMBER "N NUMBESS Mashin ton Nuclear Plant Unit 2 0 5 0 0 0 3 979 1 010 0 0 0 5 OF 0 5 TExT N moro ssssso is sooted. u>> atchuonssisRc Foms 058A's) I)2)

Safet Si nificance This event is of no safety significance. There was no actual demand for containment isolation and the valves were found to be fully,functional when tested during the R6 refueling outage. PRA methodology indicates that the probability of a containment bypass event is less than 10E-8.

Similar Events Several LERs associated with wiring separation errors have been written (85-023 series,89-032 and 89-039). These addressed a variety of issues related to inadequate separation between redundant class IE divisions, inadequate fusing (single fuse rather than double), and routing of failsafe cables in non-failsafe raceways. However, none of these involved intra-divisional separation concerns.

Since the deficiencies presented in this LER predate the corrective actions i n the similar LERs, the improved sensitivity to separation criteria gained from similar LERs would not have prevented the existing problems.

EIIS Information EI IS Reference Text Reference d ~ddd RRC AD HY AD SGT BH MSLC SB RRC-FVC-60A(B) AD FCV HY-V-XX (16 valves total) AD NRC Form 255A 1580)