ML20058J862

Summary of 901005 Meeting W/Util in Rockville,Md Re Cable Conduit Testing Program.Viewgraphs & Attendee List Encl

ML20058J862
Person / Time
Site:	Sequoyah
Issue date:	11/27/1990
From:	Donohew J Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 9012060006
Download: ML20058J862 (22)

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NUCLEAR REGULATORY COMMISSION

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November 27, 1990 o

' Decket !!cs. 50-327 and 50-328

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1 LICENSEE: -Tennessee Va11(y Authority (TVA) ftCILITY: Sequoyah Nuclear Plar.t. Units 1 and 2 i

SUMMARY

OF THE OCTOBER 5,1990 MEE11NG Oh SEQUOYAP. CABLE /CONDUlT -

l 1LSTING PROGRAM F0k SAFETY-RELATED CABLE Dr. Friday,f Peactor Projects - RegictOctober 5,1990, a treeting was held at the headqu N vision o 1/11.-Office of Nuc kar Reactor Regulation (NRR) NRC, in Rockvillt, Paryland. The sneeting was between the i;FC staff and TVA's represer.tatives.

It wac held at the request of NPR to discuss the cbble/ conduit testing prograre for safety related cables at

-Sequcyah.. Enclosure 1 is the list of individuals who attended the n.eetir.g and is the handout presented by TVA during the nieeting. The following is a sunnary of the significar,t iteres discussed and the actions, if any, taken Cr pr0 posed.

This necting was the second n.eeting held on the Sequcyah cable / conduit testing progran.-for sefcty-related cables since the staff discovered that the 1987 calcoleticn which detettiir4d tht.15 "wcrst case" cor.duits wes ursigned and TVA actnckledged there were errors in.this calculation. This n.eeting was the' third reeting held on the acceptability cf-the Sequoyah safety-related cables inside containnent since' the significant' rabh pullby daria0e four.d at Watts Bar U, nit 2 in 1909.- The previous steetings ure held on May 31 and July 23, 1990. The reetirg sur.o.eries ~were issued en July 5 and August 20,'1990, respectively.

The histoty of these issues.was giver. in;these previous meeting sunnaries.-

- r The agenda for'the neetil-g is on the second page of Enclosure 2.

In'its presentation. TVA-explained the results of its recalculation of the " worst case" cor duits at Sequcyah'. TVA stated that it had completed all phases of the recalculations, ranked the conduits in accordance with the ranking criteria, developed isoneetric.s for the " worst case" conduits..and did side well bearing. pressure (SWBP). calculations for these conduits. The details cre on pages 4-8 of Enclosure 2.

The two phases for the recalculation are given in Enclosure 3, which is~ Page 10 from the TVA handout for the meeting of July 23, 1990.

TVA presented the recalculated 21 " worst case" Sequcyah conduits on pages 9 and 10 of Er. closure 2.

Page 10 shows the relationship of these " worst case" Sequoyah conduits with the 13 " worst case" conduits for Browns Ferry. Two of these:21 "wot si case" Sequoyah conduits and ten of tbc Brcwns Ferry (chduits t

9012060006 901127 PDR ADOCK 05000327.

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N s have been previously tested (the tested conduits are marked with a "T").

TVA stated that the " worst case" Browns Ferry conduit (i.e.,(24810 percent allow able SWBP) and the " worst case" Sequoyah Unit 2 conduit i.e., 655 percent allowableSWBP)werenotvalidbecausetheSWBPcalculationswerebasedon several cables being pulled over only one cable in the conduit. The calcula-tions overestimate the actual SWBP and the potential for damage to cables in the conduit for these conduits because it would be assumed in the calculations that the several cables would all be pulled over the one cable in the conduit.

TVA summarized its presentation on the SWBF calculations with the following statements:

(1) There are only 21 out of approximately 9500 conduits at Sequoyah with SWBP above 85 percent of allowable values, (2) seven out of the top 3? Sequoyah conduits have been tested; (3) the Sequoyah Unit 2 conduits generally have lower SWBP than those in Unit 1; (4) all Sequoyah conduits but two Unit 1 conduits are bounded by the conduit testing at Browns Ferry (when the number i Browns Ferry conduit is discounted because the SWBP calculation are not considered to be accurate); and (5) two of the 21 " worst case" Sequoyah conduits have been tested.

TVA proposed to test the two " worst case" Sequoyah Unit I conduits (i.e., the ccnduits with 3816 percent and 3255 percent allowable SWBP) in the Unit 1 Cycle 5 refueling outage.

These are the two Sequoyah conduits not bounded by Browns Ferry testing (when the Number 1 Browns Ferry conduit is discounted

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bccause the SWBP calculation is inaccurate). They are described on Page 13 of Enclosure 2.

The testing of one conduit would be a wet test and the testing l

of the other, because it contains shielded cable, would be a dry test. TVA I

stated that there is no need to test the highest SWBP Unit 2 conduits because (1) the SBWP values for Unit 2 conduits are generally lower than for Unit 1; (2) five of. the top 11 Unit 2 conduits have been tested; (3) the top Unit 2 conduit may have an inaccurate SWBP value; and (4) the Browns Ferry tests and the additional Sequoyah Unit 1 tests will bound the Sequoyah Unit 2 conduits.

TVA concluded its presentation with the results of its re-review of the vertical cable and jamming calculations for the Sequoyah conduits. This work was in calculations done in 1987 which were also unsigned. TVA stated that it regenerated the original work and reached the same conclusions.

Therefore, it considers that these issues remain closed.

l At the end of the meeting, TVA requested the staff's concurrence that only the two " worst case" Sequoyah Unit I conduits needed to be tested. The testing would be done before completion of the Unit 1 Cycle 5 refueling outage, which is scheduled for the fall of 1991. The staff caucused and requested that TVA (1) also test the third " worst case" Sequoyah Unit 1 conduit because this l

l conduit is bounded by only one " worst case" Browns Ferry conduit which has been tested, (2) derronstrate that parachute cord, which was used at Watts Bar, was not used to pull cables at Sequoyah by inspecting a number of pull boxes of the l

" worst case" conduits in both units for the cord, and (3) submit its conduit l '

testing program in a letter which the staff will review and issue an evaluation report. The staff stated that it agreed that no additional Unit 2 conduits needed to be tested if it were demonstrated that parachute cord was not used to pull cable at Sequoyah. TVA stated that it has never identified that parachute cord was used at Sequoyah. With this, the meeting ended.

3 In t letter dated October 23, 1990, TVA subt;itted its pr oposed cable testing prograra; a copy of the letter, minus the TVA tendout in Enclosure 2, is included in this riceting surmary (Enclosure 4).

N..

Jac< i. Dono Jr., Senior Project l'anager Project Directc ate 11 4 Division of Reactor Projects - 1/11 Office of Noc kar Febetor Regulation

Enclosures:

1.

Attendance List 2.

TVA 11andout 3.

Fage 10 From July 23, 1990 Peetin9 TVA !!andout

-4 Letter dated October 23, 1990 r,inus Enclosure 1 to the letter ccw/ enclosures:

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Pr. Marvin Runyon, Chairc:an Mr. Joseph Bynum, Acting Site Director Tennesset Valley Authority Sequoyah Nuclear Plant ET 12A 7A Tennessee Valley Authority 400 West Surrit Hill Drive P. O. Box 2000 Knoxville, Tennessee 37902 Soddy Daisy, Tennessee 37379 Mr. Edward G. Vallace Ms. Marci Cooper Manager, Nuclear Licensing Site Licensing Manager and Regulatory Affairs Sequoyah Nuclear Plant Tennessee Vallt) Authority P. O. Box 2000 EN 1578 Lecteut Place Soddy Daisy, Tennessee 37379 Chattancesa, Tennessc( 37402-2801 Mr. Jchn D. Uatert, tirector County Judge Tennessee Vc11cy ALthcrity Perilton Courty Courthouse ET 12A 9A Chattancoga, Tennessee 3740?.

400 Kest Surrit Pill Prive Kncxville, Tennessee 37902 Regional Administrator, r,cgion II U.S. huclear Pctulatory Commiss'en Mr. W. F. Villis 101 Marietta Street, N.W.

Chief Operating Officer Atlanta, Georgia 30223 ET 120 165 400 Pest Sun.r..it hill Drive Fr. Paul E. Harmon Knoxville, Tenncssee 3790?

Senior Resident Inspector Sequoyah Nuclear Plant Ger.eral Ccunsel U.S. Nuclear Petulatory Commission Tennessee Yelley Authority 2600 Igou Ferry Road 400 West Surt.'it Hill Drive Soddy Petty, Tennessee 3737S ET llB 33F Knoxville, Tennessee 37902 Mr. Michael H. Pobley, Director, Division of Radiological Health Mr. Dvight Nunn T.E.R.R.A. Building, 6th Floor Vice President, Nuclear Pro,iccts 150 9th Avenue Forth Tennessee Vallcy Authority Nashvills, Tennessee 37219-5404 6N 38A Lockout Pltte 1101 Market Street Tennessee Valle) Authority Chattarcoga, Tennessee 37402-2801 Rockville Office 11921 Rockville Fike Dr. Mart O. Medford Suite 402 Vice Fresident, Nuclear Assurance, Rockville, Paryland 20852 Licensing and fuels Tennessee Vality Authority CN 38A Loctout Place Chattancesa, Tennessee 37402-2801

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ENCLOSURE 2 i

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IVA/NR0 EETING SEQU0YMNUCLEARPLANT 0ABLETESIPROGRERESOLUTION m

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SEQU0YABNUCLEARPIM CABLETESIPROGRDIRESOLUTION I,

INIR0DUCIION J. R. BYEl II BACKGR0tB AND RE0ENT ACTIVIIIES PERf0ED BY P.G.IRt@El IyA -

III, IDENIIFICATION Of WORSI CASE PUllBY POPULATION, K. W. BROWN SCREENINGf0NLAANDSCREENING/RMINGRESULIS lIV. RESOLUIION Of PUllBY CONCERNS P, G IRtTEL V. VERIICAL CABLE AND J ElING CALCULATIONS-P.G.IRUDEL VI, CONCLUSIONS J.R.BYEl 4

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CABLETESTPROGRAMRES0WIION I,

lhTRODUCTION PURPOSEOFMEETINGISTOOBIAINNR00050URRBCEWITHSQN0ABLETESI PROGRAM (OIP)RES0WIION TVA OMIIIED 10 IMPLEMBI IBE 0ABLE TESI PROGRAM RES0WIION PIM 10 FURTHER VERIFY THE INTEGRITY OF SAFETY RELATED CABLES A OP!RABILIIYDEIIRMINATION00N0DDEDTHATIBEPROBABILITYOFDMGEIS-LOW,PROBABILITYIBAIDAMAGEWOULDHAVEBEDIDBIIFIEDISBIGH,AND SAFEIYCONSEQUENCESOFPOIEhTIALDAMAGEARELOW f

PROGRid IMPLEBIATION HAS REINFORCED EARLIER 00N0250NS IESIING0FUNII200NDUIISWOUDN0IADDITIONALLYINCREASE00hTIDENCE LEVEL CONFIRMATORYTESIINGONUNIT1DURINGUNIT10Y0lE50UIAGEISPROPOSED 10TOTALLYCLOSEOUIISSUE-

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.,. 1 CABLEIESTPROGRAMRESOLUTION II,'ACTIVITIESPERF0MDBYIVA BASECA10009DATASAMPLED-NEEDFORDATAVERIFICATION PHASEIANDPEASEIICOMPLETED RNEDPERTEECRITERIA f

DEVELOPED IS0s AND PERF0MD S'M CALC i

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CABLEIESTPROGRAMRESOLUTION II. BACKGROUND-L CONCERN SQN AFFECIED BY WAIIS BAR PROBIES UNISSUED0A10ULATIONS ERRORS.INCALCUI.AIIONSQNCSS009 a

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JULY 23MEEIINGWIIBRESOLUTIONS

- SCREEN CONDUIIS BY R N ING

- NEW R N BY SWBP

- ISSUE JAMMING N VERIICAL SUPP0RIED CABLE CALCULATIONS

- EVALUAIE APPROPRIATE ACTIONS 1

- -QA INV0lVF3ENI

.y MULTIPHASEAPPR0ACH OPEkABILITY DEIERMINATION IN PLACE AND ACCEPIED

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I CABLEIESIPROGU.1RES0!UIl0N 1

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III, IDENIIFICATION Of WORSI CASE PUllBY POPULATION-(AUGUSISUBMIITAL)

IDENIIFY10IALPOPULATIONOfIE002UIIS(APPR0XIMATELY9500)

IDDIITY00EUIIS00NIAININGSEVUORMORECABLIS(803)

USINGFIELDSKEICHESORDESIGNDRAWINGIDEh7IFY00EUIIS FEETLONG(269)l 0BIAIN FIELD SKEICHES FOR IB0$E 00EUIIS TO DEIEMIE LENGIB AND TOTAL BEES BEIVEEN Pull POINIS INPUI CABLE AND 00EUII CONFIGURATION DATA INIO DATABASE PERf02SCREENINGOALCULATIONS WALD0WN TOP 30 00EUIIS 10 OBIAIN DETAllED IS0EIRIO 3

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CABLEIISIPROGRAMRESOLUTION III.' SCREENIE CALOULATION FORMULA L*K*We*f*p*exp(K*A*We*n)=SCREENINGFACIOR R

WERE:-

L = 00EUII SEGE LENGIH (FEET)

K = 00EFFICIENI 0F FRICIION We=WEIGHTCORRECTIONFACIOR F = 00 001I FILL PERCEh7 AGE P-=PUllBYFRACIION R=002UIIBEDRADIUS(FEET)

A=10TALBEESINASEGMEhT(RADIANS) a = CONFIGURATION 00W ERSION FACIOR 7

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III. SCREENING /RAEING RESULTS 26900EUITSEVALUAEDBYSCREENINGTONLA IS0EIRIOS devil 0 PED F0!, TOP 30 CONDUIIS AND SB?s CALCULATED /00RRELATION NOT ADEQUAE WA!.00WNS AE CALOULATIONS EXPAEED TOIAl' 0F 93 IS0ERICS OBIAIED IN0LUDING TOP 60 AND 00EUI WITH GREATER THAN 330 DEGREES BETEEN Pull POINTS EXCEPI OE

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SEP OALOUIATIONS PERFORMED FOR 93 s

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CABLE IESI ?ROGRAM RESOLUTION i III, SCREENIN0/R! MING RESULTS (CONTINUED)

N EXP SWl? f, V-LIVEL REMARKS 1,

IPM2136 I-3816 V2 2,

150266 S-3255 V3 3,

1PM1192 II 1563 V2 4,

2?M2140 I 655 V2 02 ( 6 OVER 1) 5, M02796 A 381 V4 6.MC1728B(TESIID) 349 V3 U2 7.

1PM2080 1 275-V2 8,.M02606A 185 V3 U2 9,

IV6636 A 182 V3 Ul/02 < = 2 4 10LIPL4342A.

158 V3 11, IPM2132 I 134 V2 12, 2PM2084 I 131 V2 U2

'13, IPM2087 II 131

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-14, IV801'A 112-V3 15, IPM2107 II-108 V2 a

16, IPS359 IV-106 V2 17, 2PM2087.II 104

.V2 U2(21/1) 18,1PL3117 A 103 V4 19, 1PM4704 A 99 V2 20, IPM2111 II 98 V2 21.M01751A(TESTED) 84-V3 U2 SEVEN OF THE TOP 32 WERE TESTED IN THE ORIGINAL PROGRAM e..

i FIVE OF THE TOP ELEVEN 00NDUIIS CONIAINING U2 0 ABLES WERE IN IHE ORIGINAL PROGRAM (#2, #7 AND #9-11) p

$ ONE BL OF 24 DESIGNATED U2 INSTALLED SUB6EQUENT TO WORST

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CAB 11IISI PROGRAM RES0DJIl0N l.

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It RES0tDIl0N 07 PU11BY 00 NOMS l

L BRes IERRY AND SEQU0m PER0ENI All0ntLE SEP IER l

1 ALLOWABLE SWBP BROWS TERRY l

SEQUOYAR WIT 1

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$1QUOYAH WIT 2 26810 T 3816 3255-3, 4

2250 T 1563 6

828 T

-- 7 765 T 655 8

9 643 T

_10 612 7 3,

11 72 364 7 3a9 T

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-16 182 182 17 18-

-160 7 158

-19 l'

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_ 24 725 110

_26 109 108 106

__ 28 104 29 103 30 99

>31 32

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• 0ne cable out of 24 designated U2 installed subsequent to worst case pullby T is equivalent to the word " TESTED."

\\O TOTAL P.17

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l CA3tEIESTPROGRAMRESOLUTION IV RESOLUTION 0F PUllBY CONCERNS GENERAL LIMITEDNUMBEROfSDPCALCSHIGH BROWNSFERRYANDSEQU0YAHRESULISINTERSPERSED SEQUOYAH UNII 2 GENERALLY LOWER SWBP Iht3 WII 1 00NflRMSSEQU0YAH00NflGURATIONHASLINIIEDSUSCEP FORDAMAGE

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(# 6, 21, 24, 26, 28, 31, ad 32)

ALL BUI 2 SEQU0YAH CONDUIIS B0WDED BY BROWNS FERRY IESIING HIGHCONFIDENCEANYDAMAGEDISC0VERED Ii

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0AllETESTPROGRAMRESOLUTION IV. RESOLUTION OF PULLBY 0050EES WIT 2 WII 2 SEPS SIGNIFICANILY L0ER IN WIT 1-5OfTOP11WII200NDUIISPREVIOUSLYIESIED f

NO PRACTICAL PHPOSE TO TESI THE HIGHESI WII 2 CONDUIT

- 6 0VER 1 PUllBY n

- NOI THE HIGHEST B0MED BY SEVERAL BROWNS TERRY TESTS v

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-- SIMII.AR TO A TESTED SEQUOM WII 2 CONDUIT i

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CABLEIESTPROGRAMRESOLUTION IV. RESOLUTION OF PULLBY CONCEBS UNII1 SEQU0YAH UNII 1 B0UNDED BY BROWS FERRY IESTING WIIB IWO EXCEPIIONS(00EUIT1PM2136IANDISG266S)

CONDUII1PM2136I

- 00NIAINS 18 CABLES THAT ARE PARI 0F INSTR E NIATION LOOPS THATIIEPRIMARYSYSTEMIEPERAIURE,PRESSUREANDFLOW INDICATION 10IEEREACIORPROIECTIONSYSIEM CONDUIIISG266S

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- 00NIAINS 7 0 ABLES ASSOCIATED WITH CONTROL AND INDICATION 0FDEVICESAffECTINGOPERATION0FIBESIEAM-DRIVEN ALIILIARYFEEDWATERPM SAFEIY SIGNIFICANCE OF POIENIIAL DAMAGE o

- LPM 21361-f

- N0 POSI LOCA HARSH PIPE BREAK ENVIR0 M NIS REQUIREDPR01ECTIVEFUNCIIONS'000VR.QUICKLY

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- N0 POSI LOCA HARSH PIPE BRIAK Eh71RO M NT l

- IN EVfR OF HARSH Eh71ROMNT DEVICE NOT REQUIRED u

L OPERABILITY DETERMINATION HAS BEEN UPDATED SEQU0YAH WILI!IEST 'IV0 UNIT 100NDUIIS IN U105 0UIAGE 10 010SEISSUE

- IPM2136 I - DRY IEST--00NIAINS SHIELDED SIGNAL CABLEk l~3 ISG266S

- WEI IESI L

l CAllE IESI PROGRD1 RESOLUIION

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V. VERIICAL CABLE AND JDNING cal 0ULATIONS VERIICAL CABLE CALCULATION.

TVA HAS REGENERATED THE UE&C WORl( AND REACBED THE SAME CONCLUSIONS J0!!NG CALCUIION IVA FAS REGENERATED BE ORIGINAL WORl( HAT NARR0VED IBE POPULAIiON TO 48 CONDUIIS AND REACHED THE SME GENERAL CONCLUSION TVA HAS REGENERATED THE WORK 10 REDUCE IEE POPUlffl0N 1015l IESTED00NDUIISBYAPPLYINGIBEFIVEINDICAIEDCRITERIA IEE POPULATION AVAIIRLE FOR TESI SLIGHILY DIffERIM mg CONCLUSIONISTHATIBEMATCHISADEQUAIE l

h ISSUESCONSIDEREDCLOSED l

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CABLEIESTPROGRAMRESOLUTION l

E VI. 00N0LUSIONS a

MULIIPLE REEVALUATIONS N E BEEN P G TORMED EIENSIVEQAOVBVIEWDURINGMREEVALUATIONS I

N0 PROGRA M. TIO CABLE INSIALLATION PROBLEMS IDENTIFIED ISSUEOLOSEDFOR. UNIT 2 I

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SEQUOYAII NUCLEAR PLANT SCHEDULE FOR CABLE PROGRAM DISPOSITION PIIASE LI 6 TO - 8. WEEKS 'FOR COMPLETION OBTAIN FIELD SKETCHES ~. AND CABLE DATA (APPROXIMATELY 260 CONDUITS)

PERFORM SCREENING CALC (APPROXIMATELY 560 CONDUITS)

IDENTIFY'-THOSE THAT ARE INACCESSIBLE DUE TO ALARA CONSIDERATIONS WALKDOWN AND COMPLETE ISOMETRICS FOR TOP RANKED ACCESSIBLE CONDUITS PREPARE AND ISSUE SIDEWALL BEAMING PRESSURE CALCULATIONS i

i FOR ACCESSIBLE: CONDUITS COMPARE SQN SWBP VALUES TO BFN'S TES D CONDUITS l

PHASE H - SCHEDULE-TO COMPLETE REMAINING CONDUITS UNIT 2 - CYCLE 4 REFUELING OUTAGE (BEGIN SEPTEMBER 1990)5 UNIT 1 - NEXT AVAILABLE OUTAGE OF SUFFICIENT DURATION E

(NO LATER THAN C-YCLE 5 REFUELING. OUTAGE:

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ENCLOSURE 4 TENNESSEE VALLEY AUTHORITY CHATTANOOGA, TENNESSEE 374ol 6N 3BA Lookout Place 00T 281990 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C.

20555 Centlement In the Matter of

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Docket Nos. 50-327 Tennessee Valley Authority

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50-328 SEQUOYAH NUCLEAR PLANT (SQN) - UNITS 1 and 2 - CABLE TEST PROGRAM (CTP)

RESOLUTION PLAN (TAC NO. 77129/77130)

References:

1.

TVA letter to NRC dated August 17, 1990 "Sequoyah Nuclear, Plant (SQN) Units 1 and 2 - Cable Test Program (CTP)

Resolution Plan (TAC No. 77129/77130)"

2.

TVA letter to NRC dated July 27, 1990 "Sequoyah Nuclear Plant (SQN) - Condition Adverse to Quality Report (CAQR)

SQP900305 - Operability Determination" The purpose of this letter is to describe the actions taken and define the actions r'emaining to resolve the SQN CTP. These efforts are intended to allow final closure of CTP concerns at SQN.

TVA and NRC met on October 5, 1990, in Rockville, Maryland, to discuss the results of'the.CTP' resolution plan submitted in Reference 1.

contains the meeting presentation material that provided the results of TVA's efforts and our proposal to achieve final resolution of SQN CTP issues. The presentation. included background information that necessitated TVA's development and implementation of.a new ranking process for SQN. The activities performed by TVA were described and details of the screening formula and ranking calculations.were provided. The results of the pullby, jamming, and vertical supported cable calculation efforts were presented and TVA:provided a plan for final resolution of these issues.

The results of the pullby calculation indicated that<two SQN conduits were not bou'nded reasonably by previous SQN or Browns-Ferry Nuclear Plant (BFN) testing and one conduit was marginally bounded. The other SQN conduits were y

adequately bounded by previous testing and were significantly lower in percent allowable sidewall bearing pressure (SWBP) such that no additional actions would be required.

In general, the results showed a small population of conduits with high SWBP and a range of values similar.to those seen at BFN.

This supports a conclusion that.-SQN conduits have configurations with limited susceptibility for pullby damage.

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, U.S. Nuclear Regulatory Commission 00T 231986 In addition, seven of the top 32 SQN conduits had been previously tested, which provides confidence that cable damage would have been discovered. With the highest Unit 2 conduit falling well below the top three, TVA proposed and it was agreed that no additional testing would be needed for Unit 2 conduits.

For Unit 1, TVA agreed to test the top three ranked conduits at the Unit 1 Cycle 5 refueling outage or earlier if a forced Unit 1 outage provided anticipated sufficient duration. A forced outage of at least 14 days in Mode 5 would be required to provide suf ficient duration for this testing effort. The testing for the first and third highest ranked conduits 1PM21361 and IPM1192II, will be performed dry because'they include shielded cable and the test for the second highest ranked conduit, ISG266S, will be performed wet, in accordance with previous agreements.

NRC's concern regarding the potential for use of parachute cords during cable installation, similar to the practice at Watts Bar Nuclear Plant (WBN),

resulted in an additional commitment. To provide further assurance that this practice has not been employed at SQN, TVA inspected the SQN conduits that exceeded 100 percent allowable SWBP for presence of parachute cords. On October 14,~1990 TVA completed this inspection-of the 18 affected conduits and verified no parachute co'rds present. However, three anomalies not related to parachute cord were found and will be dispositioned through the condition adverse to quality (CAQ) process. A description of the anomalies is provided in Enclosure 3.

For the jamming and vertical supported cable calculations, TVA indicated that the corrected results have not invalidated the original test program and that the same or equivalent conduits were.terLed. TVA considers the jamming and vertical supported cabite issues at SQN resolved with no further actions required.

A revised operability-determination based on the results of the new pullby ranking calculation, which supersedes the determination submitd by Reference 2, is included as Enclosure-2.

A summary statement of the commitment contained in this submittal is provided in Enclosure 4.

Please direct questions concerning't'is issue to Marcia A. Cooper at (615) 843-6422.

Very truly yours, TENNESSEE VALLEY AUTHORITY f

Vark O. Medford, Vice President Nuclear Assurance, Licensing

& Fucis Enclosures cc: See page 3

-3 U.S. Nuclear kegulatory Commission 00T 281990 cc a. Enclosures):

Ms. S. C. Black Deputy Director Project Directorate II-4 U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. J. N. Donchew Project Panager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 NRC Resident Inspector Sequoyah Nuclear Plai.t 2600 Igou Perry Road Soddy Daisy, Tennessee 37379 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 m

i

a ENCLOSL*RE 1 TVA/NR0MIEIING L

SEQU0YABNUCLEARPIBI 1.

CABLEIESIPROGRAMRESOLUTION f

0010BER5,1990 I

N i----------

m

e ENCLOSURE 2 SEQU0fAH NUCLEAR PLANT (SON)

CONDITION ADVERSE TO QUALITY REPORT (CAOR) 50P900305 R0 OPERABILITY DETERMINATION Discussion Deficiencies were identified with the application of the criteria used in ranking conduits that were tested to address pullby concerns during restart at SON.

These problems were documented in CAOR 50P900305 R0. Continued 1

operation of SON in light of the deficiencies is justified by the following.

1.

Probability of Occurrence at SON Watts Bar Nuclear Plant (WBN) had specific employee concerns related to cable installation. SQN did not have any substantiated cable installation employee concerns. Subsequently, SON conducted extensivs rev)9ds of the cable racewai systems and the attributes that contribute

/

to the possibility that_ undetected cable damage during installation could

)

occur. Thest prerestart reviews, involving cable pull data retrieval and conduit walkdowns, were undertaken as a part of the SQN cable test program (CTP) and included the issues of pullbys, jamming, and silicone-rubber cables supported in vertical conduits by conduit bodies j

at the top of the run, in addition, as a postrestart commitment, other 10 CFR 50.49 cables in vertical conduits were evaluated for compliance with the National Electrical Code requirements and provided support as required.

As a prelude to the SON eff orts to address the WBN contares, NRC consultants visited SON, conducted interviews, and walked down areas of the plant. While they concluded that there were deficiencies in the instructions for cable pulling activities from 1973 to 1979, they did not find that the conduit configurations differed significantly from other.

nuclear plants of SON's vintage.

Recent comparisons of conduit configurations have shown that SON's installations closely resemble those at Browns Ferry Nuclear Plant (BFN). The short runs with many pull points translate into ' easy pulls".

To provide additional information about the similarity between SON and BFN, calculation 50N-CSS-033, ' Calculation for Analysis of Cable Pullby Concerns' (CACPC) was prepared and issued.

In order to produce CACPC, SON conductec' additional walkdowns of more than 250 conduits for physical configuration.

l l l October 18, 1990 C901E L

)

i As expected, the CACPC results have proven that the SQN calculated sidewall bearing pressure (SWBP) values (percent allowable) are bounded i

by those resu' ting t'.om the BFN pullby analysis. However, because the SWBP value for the worst-case conduit at BFN appears to be extremely conservative, it is concluded that the top two SON conduits may not be bounded by the BFN tests, this is discussed further in Section 2.

Both TVA and the industry have rmgnized that the potential for cable damage during a pullby operd ion increases with conduit fill. During reviews conducted at WBN for the issue of pullbys, the presence of a large quantity of overfilled conduits resulted in the identification of this as a significant factor.

In contrast, review of SQN data du'ing the pullby analysis ef fort has shown that relatively few conduits are overfilled and, therefore, the potential for undetected pullby daluge is correspondingly reduced.

Two other significant dif ferences were noted between SQN and WBN which can be expected to have resulted in less potential for cable damage during pullbys at SQN.

First, conduit configurations P.t SQN are regarded as being of lesser compMxity than comparable conduits at WBN. This observation is consistent with those reported in the Technical Evaluation reports prepared for the two plants.

Since forces encountered within a conduit during a pullby are a direct function of configuration SQN pullbys can, therefore, be expected to have M en of lesser severity.

Second, in contrast to WBN, previous SQN rt

,s have indicated that nylon ' parachute

• cords have not been used be performing pullbys. The use of this cord was determined to be one of the primary causes of pullby damage at WBN. The absence of t'.is cord at SQN was recently further confirmed by inspection of the top 18 conduits as determined by the CACPC.

TVA concludes that there was not then, nor is there now, any evidence that SQN has any safety-reltted cables installed that were damaged by the pulling practices.

1 2.

Probability of Damage Discovery at SQN Even though there was no evidence of damaged cables at SQN, a population of conduits and cables was identified to conduct high-voltage tests for the purpose of detecting damage caused by pullbys, janning, and silicone rubber insulated vertical cables supported by conduit bodies near the top of the conduit run. Over 900 conductors were successfully tested at voltages ranging from 4.8 kilovolt (kV) to 10.8 kV dc. The SQN CtP represents one of the most comprehensive in-situ test programs ever undertaken in the industry.

~~

October 18, 1990 2901E

e SQN's CTP selecQion criteria was biased t00ard material damage susceptibility.

Hcwever, even though disciepancies have been discove. M in the unissued calculation to document the application of the selection criteria, TVA has confirmed by reapplication of the selection criteria that seven of the original 15 tested pullby :onduits remain in the worst-case or higher-risk category.

The remaining eight conduits could, therefore, be considered to be randomly selected.

The successful testing of these conduits still provides a high degree-of confidence that if a programmatic problem with the installation practices at SQN existed it i

would likely have been found.

The CACPC performed a screening of the SQN conduits in order to determine the worst-case population. This process was based on a method thk:

approximates the SWBP formulas.

SWBP calculations were performed for tne l

top 60 conduits from this screening process.

In addition, conduits from existing SWBP calculations were merged with the 60 conduits from this screening, resulting in a total of 93 conduits ranked in order of percent allowable SWBP.

The results of the ranking show that all conduits except for the top five are bounded by conduits previously tested at SQN. The remaining five conduits are bounded by the SWBP values from the BFN cable test program.

However, as previously mentioned, it appears that the SWBP value for the worst-case conduit at BFN is overly conservative.

Therefore, the top two' SQN conduits may not actually be bounded by the BFN tests.

The top two conduits (IPM2136I and ISG2665) contain cables associated with the Rearter Protection System and the Turbine Driven Auxiliary Feedwater l

Pump (TDAFWP) controls, respectively.

They are both located in the L

Auxiliary Building. With regard to IPM21361, the environm(nt was classified as " harsh", only for the scenario of an RHR suction line break while in Mode 4 (hot shutdown). A review cf the environmental conditions for that conduit has shown that a maximum temperature peak of 198 degrees (F) occurs 800 seconds after an RHR line break and decreases linearly to 104 degrees at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In this situation, the plant is already shutdown and the consequences of the potential failure of associated RPS cables is l

considered minimal.

There is no significant pressure increase in,the area I

around this conduit, so the only possible moisture intrusion into the conduit would be a result of condensation.

Thus, there is little likelihood of cable failure during the postulated event and if a failure did occur, the consequences would be minimal.

For ISG2665, the environment is considered harsh with a maximum temperature of 110 degrees only in the event of a steam supply line break to the TDAFWP.

In this event, the affected end device is already inoperable.

L l L October 18, 1990 2901E l

C 1

In January 1989, SON implemented a Cable Monitoring Program to document and trend problems.

These problems include age-related failures that would surf ace if the cable was installed improperly. To date, no cables have been identified as incapable of performing their safety-related function by this program. Additionally, many maintenance and modification activities and Quality Control inspections have been performed since the initial concern and no installation damage to cables or operational failures of cables attributed to installation practices have been identified.

1 TVA's overall confidence in the integrity of SON cables has increased.

The large number of review and test activities have not found cable installation problems. The overall favorable information about the SQN conduit configurations, and results of both the SQN and 8FN CTPs are the basis for this increased confidence.

3.

Consequences of Undiscovered Cable Damage in the unlikely event that a SON safety-related cable was damaged during installation, the consequences of that damage can be evaluated by the two types of failure mechanisms that might occur.

The first type is the ran* dom failure.

For the purposes of this discussion, and based on the operating experience at SQN, this type of j

f ailure is limited to age-related damage due to improperly installed cables. This f ailure is sitigated by the fact that the redundant circuit for the failed cable is expected to perform the safety-related function that might be lost by the cable failure.

The effects of a random failure are inconsequential because of the redundancy, diversity, and defense in depth af forded by the standard design requirements.

For example, the effects of a faulted cable inside containment are mitigated by the diverse and redundant penetration overcurrent protection design (fuse and breaker combination). The ef fects on emergency safeguards actuation are mitigated by the redundant and diverse design of the reactor protection system (e.g 2/3 and 2/4 logic combinations in conjunction with diverse. parameters-L sensing containment pressure and pressurizer pressure).

.The second type of failure is the comon mode failure. This type of cable f ailure is primarily related to environrental conditions (water, steam, and humidity) created by an accident. ?-or the purposes of this discussion, the environmental conditions will be separated into those inside containment and those outside containment.

~4 ~

October 18, 1990 2901E

-+.

+.

+

4 v._,. - ~..

. - ~ -

For the cables inside containment, there are several factors that support the adequacy of the installed safety-related cables. Because the containment equipment is typically a ternination point for conduits and cables (as opposed to a distribution point), there are relatively fewer pullbys in.the conduit systems there. The straight line space limitations inside containment result in shorter conduit runs and more cable pull points than in more spacious areas.

I Redundant safety-related equipment is physically separated and compartmented by concrete walls and barriers inside containment to provide i

protection against events that creatu dynamic environmental effects. The conduits and cables that supply this equipment derive some benefits f rom this line of protection. As a result, the comon mode failure from undetected cable damage is unlikely.

Other Category I areas outside contr.inment include the auxiliary building (AB) and the control building.(CB). The harsh areas of the AB are primarily transition areas for safety-related cables (and the vast majority of them are in cable trays).

However, the harsh environments are less severe and not as prolonged as those inside containment. The primary safety function required for events that produce these environments is the ability to achieve and maintain safe shutdown conditions. This function is also the focus of Appendix R evaluations. As such, separation, compartmentalization, and fire wrap all provide a. measure of protection from environmental effects. Conduits are also sealed to prevent water intrusion from flooding and flood propagation between rooms and floors.

The sealing also provides a measure of protection against water or moisture intrusion. As a result, the comon mode failure from undetected cable damage is unlikely.

In the power, control, and signal cable distribution areas of the CB, as well as the AB, where a large number of pullbys occur, the environment is considered mild or of less severity and is, therefore, not impacted by adverse ef fects of an accident that would create a potential comon mode failure mechanism from undetected cable damage.

[:

T 1

1

, October 18, 1990 2901E om.-

,v

. -, -.. ~. - - -

Conclusion The probability of cable damage during installation is low. Substantial evidence f rom a variety of sources establishes that the SON conduits are typical of its vintage of nucitar plant and that there are no programatic cable installation problems.

Inspections performed on the top 18 conduits that have the highest potential for dif ficult pullbys (Reference SQN-CSS-033) f urther confimed that parachute cord type pull ropes were not used at SQN during pullby activities. Also, no installation damage resulting from pullbys has been detected.

The SON CTP results provide a high degree of confidence that cable damage in material susceptible cable would have been detected. The BFN and SON CTP test results in conjunction with the SWBP calculations performed for SQN give a high degree of assurance that the forces developed during pullbys were not large enough to cause cable damage. The physical nature of the SQN conduit confiourations also support this conclusion.

The potential consequences due to the random failure from undetected cable damage is inconsequential because of the redundance, diversity, and defense in depth afforded by standard design requirements. Comon mode f ailures f rom undetected cable damage are highly unlikely. The most severe environments (inside containmer.t) that might trigger the conrnon mode f ailu'es are in locations where pullbys (and hence damage from pullbys) were least likely to occur. On the other hand, pullbys were most likely to occur in areas outside primary containment that are mild or of greatly reduced severity and unlikely to initiate comon mode f ailures, in addition, the separation and protection features incorporated for other programs (e.g., fire protection, moderate energy line breat flooding, and hig's energy like break protection) provide additional protection f rom environmental ef fects.

These features further lessen the likelihood of comon mode f ailure.

As a result, there is a high degree of confidence that the SQN safety-related cabler will perform their intended functions.

b g k.

lo/l8 /qo Prepared by ] N L>

.. w Date lo//8/to

/

Reviewed by h

d.

Date r -

/0/is,/90 f

. October 16, 1990 2901E

4 ENCLOSURE 2 s

SEQUOYAH NUCLEAR PLANT (SON)

CONDITION ADVERSE TO QUALITY REPORT (CAQR) SQP900305 R0 OPERABILITY DETERMINATION Discussion Deficiencies were identified with the application of the criteria used in ranking conduits that were tested to address pullby concerns during restart at SON. These problems were documented in CAOR SQP900305 R0.

Continued operation of SQN in light of the deficiencies is justified by the following.

1.

Probability of Occurrence at SQN Watts Bar Nuclear Plant (WBN) had specific em: 1cyee concerns related to i

cable installation. SON did not have any substantiated cable installation employee concerns. Subsequently, SON conducted extensive reviews of the cable raceway systems and the attributes that contribute to the possibility that undetected cable damage during installation could occur.

These prerestart reviews, involving cable pull data retrieval and conduit walkdowns, were undertaken as a part of the SQN cable test program (CTP) and included the issues of pullbys, jamming, and silicone-rubber cables sepoorted in vertical conduits by conduit bodies at the top of the run.

In addition, as a postrestart commitment, other 10 CFR 50.49 cables in vertical conduits were evaluated for compliance with the National Electrical Code requirements and provided support as required.

As a prelude to the SON ef forts to address the WBN concerns, NRC consultants visited SQN, conducted interviews, and walked down areas of the plant. While they concluded that there were deficiencies in the instructions for cable pulling activities f rom 1973 to 1979, they did not find that the conduit configurations dif fered significantly from other nuclear plants of $0W's vintage.

Recent comparisons of conduit-configurations have shewn that SON's installations closely resemble those at Browns Ferry Nuclear Plant (BFN). The short runs with many pull points translate into ' easy pulls'.

To provide additional information about the stejlarity between SQN and BFN, calculation SON-CSS-033, ' Calculation for Acalysis of Cable Pullby Concerns' (CACPC) was prepared and issued.

In oroer to produce CACPC, SON conducted additional walkdowns of more than 250 conduits for physical configuration.

~~

October 18, 1990 2901E

As expected, the CACPC results have proven that the SQN calculated sidewall bearing pressure (SWBP) values (percent allowable) are bounded by those resulting from the BFN pullby analysis. However, because the SWBP value for the worst-case conduit at BFN appears to be extremely conservative, it is concluded "at the top two SQN conduits may not be l

bounded by the BFN tests. Th..

discussed further in Section 2.

Both TVA and the industry have recognized that the potential for cable damage during a pullby operation increases with conduit fill. During reviews conducted at WBN for the issue of pullbys, the presence of a large quantity of overfilled conduits resulted in the identification of this as a significant factor.

In contrast, review of SQN data during the pullby analysis ef fort has shown that relatively few conduits are overfilled and, therefore, the potential for undetected pullby damage is correspondingly reduced.

Two other significant dif ferences were noted between SQN and WBN which can be expected to have resulted in less potential for cable damage during pullbys at SQN.

First, conduit configurations at SQN are regarded as being of lesser complexity than comparable conduits at WBN. This observation is consistent with those reported in the Technical Evaluation Reports preparea for the two plants. Since forces encountered within a conduit during a pullby are a direct function of configuration, SQN pullbys can, therefore, be expected to have been of lesser severity.

(

Second, in contrast to WBN, previous SQN reviews have indicated that nylon ' parachute" cords have not been used in performing pullbys. The use of this cord was determined to be one of the primary causes of pullby damage at WBN.

The absence of this cord at SQN was recently further confirmed by inspection of the top 18 conduits as determined by the CACPC.

l TVA concludes that there was not then, nor is there now, any evidence that SQN has any safety-related cables installed that were damaged by the l

pulling practices.

2.

Probability of Damage Discovery at SQN i.

Even though there was no evidence of damaged cables at SQN, a population l.

of conduits and cables was identified to conduct high-voltage tests for L

the purpose of detecting damage caused by pullbys, jaming, and silicone rubber insulated vertical cables supported by conduit bodies near the top of the conduit run. Over 900 conductors were successful?v tested at voltages ranging f rom 4.8 kilovolt (kV) to 10.8 kV dc. 'Ae SQN CTP i

represents one of the most comprehensive in-situ test programs ever undertaken in the industry.

p

~~

October 18, 1990 2901E na

..,,. - - ~ - -,

~.,------v.-

,,, ~

. - ~ - -

,+o SON's CTP selection criteria cas biased tocaed material damage susceptibility.

However, even though discrepancies have been discovered in the unissued calculation to document the appilcation of the selection criteria, TVA has confirmed by reapplication of the selection criteria that seven of the original 15 tested pullby conduits remain in the l

worst-case or higher-risk category.

The remaining eight conduits could, 1

therefore, be considered to be randomly selected.

The successful testing 1

of these conduits still provides a high degree of confidence that if a programmatic problem with the installation practices at SQN existed it would likely have been found.

The CACPC performed a screening of the SQN conduits in order to determine the worst-case population. This process was based on k method that approximates the SWBP formulas.

SWBP calculations were performed for the top 60 conduits from this screening proces;. In addition, conduits from existing SWBP calculations were merged with the 60 conduits from this

]

screening, resulting in a total of 93 conduits ranked in order of percent allowable SWBP.

The results of the ranking show that all conduits except for the top five are bounded by conduits previously tested at SQN.

The remaining five conduits are bounded by the SWBP values from the BFN cable test program.

However, as previously mentioned, it appears that the SWBP value for'the worst-case conduit at BFN is overly conservative.

Therefore3 the top two SQN conduits may not actually be bounded by the BFN tests.

Ttj top two conduits (IPM21361 and ISG2665) contain cables associated with the Reactor Protection System and the Turbir.e Driven Auxiliary Feedwater Pump (TDAFWP) controls, respectively. They are both located in the Auxiliary Building. With regard to IPM2136I, the environment was classified as " harsh", only for the scenarlo of an RHR suction line break' while in Mode 4 (hot shutdown). A review of the environmental conditions for that conduit has shown that a marimum temperature peak of 198 degrees (F) occurs 800 seconds after an RHR line break and decreases linearly to 104 degrees at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In this situation, the plant is already shutdown and the consequences of the potential failure of associated RPS cables is considered minimal.

There is no significant pressure increase in the area around this conduit, so the only possible moisture intrusion into the conduit would be a result of condensation.

Thus, there is little likelihood of cable failure during the postulated event and if a failure did occur, the consequences would be minimal.

For ISG2665, the environment is considered harsh with a maximum temperature of 110 degrees-only in the event of a steam supply line break to the TDAFWP.

In this event, the affected end device is already inoperable, l

l

October 18, 1990 2901E

In January 1989 SON implemented a Cable Monitoring Program to document and trend problems. These problems include age-related failures that would surface if the cable was installed improperly. To date, no cables have been identified as incapable of performing their safety-related function by this program. Additionally, many maintenance and modification activities and Quality Control inspections have been performed since the initial concern and no installation damage to cables or operational failures of cables attributed to installation practices have been identified.

TVA's overall confidence in the integrity of SQN cables has increased.

.The large number of review and. test activities have not found cable installation problems. The overall favorable information about the SQN conduit configurations, and results of both the SON and 8FN CTPs are the basis for this increased confidence.

3.

Consequences of Undiscovered Cable Damage In the unlikely event that a SQN safety-related cable was damaged during installation, the consequences of that damage can be evaluated by the two types of failure mechanisms.that might occur.

The first type is the raridom f ailure.

For the purposes of this discussion, and based on the operating experience at SQN, this type of failure is limited to age-related damage due to improperly installed cables. This failure is mitigated by the fact that the redundant circuit for the failed cable is expected to perform the safety-related function that might be lost by the cable failure. The effects of a random failure are inconsequential because of the redundancy, diversity, and defense in depth afforded by the standard design requirements.

For example, the ef fects of a faulted cable inside containment are mitigated by the diverse and redundant penetration overcurrent protection design (fuse and breaker combination).. The ef fects on emergency safeguards actuation are mitigated by1 the redundant and diverse design of the reactor protection system (e.g 2/3 and 2/4 logic combinations in conjunction with diverse parameters' sensing containment pressure and pressurizer pressure).

The second type of failure is the common mode failure. This type of cable f ailure is primarily related to environmental conditions (water, ! Ham, and humidity) created by an accident.

For t5e purposes of this discussion, the environmental conditions will be separated into those inside containment and those outside containment.

d~

October 18, 1990 2901E

,~s+

For the cables inside containment, there are several factors that support the adequacy of the installed safety-related cables. Because the containment equipment is typically a termination point for conduits and cables (as opposed to a distribution point), there are relatively fewer pullbys in the conduit systems there. The straight line space limitations inside containment result in shorter conduit runs and more cable pull points than in more spacious areas.

Redundant safety-related equipment is physically separated and compartmented by concrete walls and barriers inside containment to provide protection against events that create dynamic environmental effects. The conduits and cables that supply this equipment derive some benefits from this line of protection. As a result, the common mode f ailure f rom undetected cable damage is unlikely.

]

Other Category I areas outside containment include the auxiliary building (AB) and the control building (CB). The harsh areas of the AB are primarily transition areas for safety-related cables-(and the vast majority of them are in cable trays).

However, the harsh environments are less severe and not as prolonged as those inside containment. The primary safety function required for events.that produce these environments is the ability to achieve and maintain safe shutdown conditions. This function is also the focus of Appendix R evaluations. As such, separation, 1

compartmentalization, and fire wrap all provide a measure of protection from environmental effects. Conduits are also sealed to prevent water intrusion from flooding and floco propagation between rooms and floors.

The sealing also provides a measure of protection against water or moisture intrusion. As a result, the common mode failure from undetected cable damage is unlikely.

In the power, control, and signal cable distribution areas of the CB, as well as the AB, where a large number of pullbys occur, the environment is considered mild or of less severity and is, therefore, not impacted by adverse effects of an accident that would create a potential common mode f ailure mechanism f rom undetected cable damage.

+

t October 18, 1990 2901E

. - ~ - _

I Conclusion The probability of cable damage during installation is low. Substantial evidence f rom a variety of sources establishes that the SQN conduit's are typical of its vintage of nuclear plant and that there are no programatic caole installation problems.

Inspections performed on the top 18 conduits that have the highest potential for difficult pullbys (Reference SQN-CSS-033) f urti.?r confimed that parachute cord type pull ropes were not used at SQN during pullhv activities. Also, no installation damage resulting from pullbys has been detec Md.

The SQN CTP results provide a high degree of confidence that cable damage in material susreptible cable would have been P,tected. The BFN and SQN CTP test results in conjunction with the SWBP calcu%tions perfomed for SQN give a hign degree of assurance that the forces developed during pullbyc were not large enough to cause cable damage. The physical nature of the SQN conduit configurations also support this conclusion.

The potential consequences ciue to the random failure from undetected cable damage is inconsequential because of the redundance, diversity, and defense in depth af forded by standard cesign requirements. Comon mode f ailures f rom undetected cable dcmage are highly unlikely. The most severe environments (inside containment) that.might trigger the comon mode failures are in locations where pullbys (and hence damage from pullbys) were least likely to occur. On the other hand, pullbys were most likely to occur in areas outside primary containment that are mild or of greatly reduced severity and unlikely to initiate comon mode failures.

In addition, the separation and protection features incorporated f or other programs (e.g., fire protection, moderate energy line break ficoding, and high energy like break protection) provide additional protection from environmental effects.

These features further lessen the likelihood of comon mode f ailure.

As a result, there is a high degree of confidence that the SQN safety-related cables will perf orm their intended functions.

Prepared by Date 10

/

/

Reviewed by I,

d Oate j p/'!E 9a

/

+

October 18, 1990 2901E

e o ENCLOSURE 3 i

i During the walkdown of the 18 top ranked pullby conduits as defined by SQN-CSS-033, three anomalies were discovered. A description of these anomalies is as follows:

Conduit Number Description of Condition MC1728B A two-conductor (#14 AWG) cable was found abandoned and not tagged. Disposition for this condition will be documented under CAQR SQP900410.

MC2796A Upon inspection of Junction Box (JB) 2352, it was verified that only four cables were routed through i

this conduit.

This was the number five ranked conduit per SQN-CSS-033. The Conduit and Cable Routing System (CCRS) showed that 'his conal t contained nine cables.

A field inspectim of JB 2352 was performed which determined the n aler of cables in each conduit, cable type, and number of coiductors.

Five of the seventy-four cable types contained in JB 2352 were obtained by comparison to similar kno,a cables since markings on the outer jacket could not be read. As a result of this inspection it was determined that conduit number MC2798A contained 13 cables. CCRS information revealed that this conduit was scheduled to contain eight cables. By evaluation of cable types Engineering concluded that the five cables routed in MC279BA were those actually scheduled to be installed in MC2796A. A sensitivity analysis was performed and documented on an engineering judgement paper on MC2798A to evaluate the impact of SWBP ranking of the top four conduits._ By using the existing.QA pull records, new pull groups were established.

These pull groups were then evaluated and the values obtained were found to be significantly lower than those conduits proposed for testing.

In addition, this evaluation also revealed that MC2798A contains no parachute chord, fill was less than 40 percent, and that ampactty considerations were not of' concern since these cables supply motor-operated valves which have short operating times. CAQR SQPf00423 will document these findings.

2PH208711 During the inspection at an "LB" :ondulet, there were some cables that exceeded the minimum bend radius. October 18, 1990 2901E

o....

i o s ENCLOSURE 3 i

However, this will be dispositioned in accordance with TVA's submittal to NRC dated January 23, 1989 (L44 890123 803). regarding rework of existing bend radius violations.

i l

t s

i l

l c

_2 October 18, 1990 2901E

w. a.

s t

a

• ENCLOSURE 4 LIST OF COMMIWINTS

+

ITA will high potential test the top three ranked Unit 2 pullby conduits:

1PM21361 (dry), ISG266S (wet), and 1PM1192II (dry)' during the Unit 1 Cycle

$ refueling outage, or earlier, in the event of a forced outage in Mode 5 or lower c' w?'!.clent duration.

4 I

h t