ML20056B410

Summary of 900723 Meeting W/Util in Rockville,Md Re Plant Cable/Conduit Testing Program for safety-related Cable.List of Attendees,Tva & NRR Handouts & Transcript of Meeting Encl

ML20056B410
Person / Time
Site:	Sequoyah
Issue date:	08/20/1990
From:	Donohew J Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20056B411	List: ML20056B410 ML20056B412
References
NUDOCS 9008280250
Download: ML20056B410 (29)

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,3 '_ [N%ofgi UNITED STATES 8, NUCLEAR REGULATORY COMMISSION g WASHINGTON, D. C. 20555 k.....);E AUG 2 019e

' Docket Nos. 50-327 and 50-328 i

LIC NSEE: Tennessee Valley Authority (TVA)

FACILITY: Sequoyah Nuclear Plant, Units 1 and 2 )

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SUMMARY

OF THE JULY 23, 1990 MEETING ON SEQUOYAH CABLE / CONDUIT i TESTING PROGRAM FOR SAFETY-RELATED CABLE 1

On Monday, July 23, 1990, a meeting was held at the headquarters of the Civision of Reactor Projects - Region 1/11, Office of Nuclear Reactor j Regulation (NRR), NRC, in Rockville, Maryland. The meeting was between the NRR staff and TVA's representatives. It was held at the request of HRR to ,

discuss the cable / conduit testing program for safety-related cables at  !

Sequoyah. Enclosure 1 is the list of individuals who attended the meeting, Enclosure 2 is the handout presented by TVA in the meeting, and Enclosure 3 f is the handout presented by NRR in the meeting. The following is a summary of {

the significant items discussed and the actions, if any, taken or proposed.

The Sequoyah cable testing program was first developed in 1987 to address j the staff's concerns about potential cable damage during cable installation in '

conduits from three situations: (1)cablepullbys,(2)cablejamming,and (3) vertical cable supported by 90-degree condulett High potential tests were conducted in 1987 on 15 " worst case" conduits selected by agreed-upon criteria. The staff's review of this cable testing program was part of its l

review of the restart of Sequoyah from its extended shutdown from 1985 to 1988 '

and is discussed in Section 3.12, Cable Installation, of NUREG-1232, Volume 2, on the Sequoyah Nuclear Performance Plan. This Safety Evaluation Report was issued by the staff's letter dated May 18, 1988 as part of its approval for Sequoyah Unit 2 to restart. In Section 3.12, the staff concluded that the Sequoyah cable testing program was acceptable for the restart of Sequoyah Units 1 and 2.

In 1989, significant cable pullby damage was discovered at Watts Bar. By telephone in December 1989, the staff requested that TVA evaluate the condition of the safety-related cables at Sequoyah in terms of the cable damage discovered at Watts Bar. This evaluation was submitted in the TVA letter dated March 28, 1990. TVA concluded in its letter th: t the previous conclusions drawn from the 1987 cable testing program regarding the integrity of safety-related cables at Sequoyah are still valid. A meeting was held with TVA on May 31, 1990 to discuss the TVA letter dated March 28, 1990. The i meeting sunmary was issued by the staff on July 5,1990. '

After the May 31, 1990 meeting, the staff decided to conduct an inspection at the Sequoyah site on June 19 to 21,1990 and review the calculations on cable sidewall bearing pressure (SWBP) for ten conduits which were not available  ;

buring the May 31, 1990 meeting. This is discussed in the meeting sunmary 1 03022 900e280250 900820 DR 1 ADOCK 050 7

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2 dated July 5,1990. In the inspection, the staff requested the 1987 calcula-tion which determined *J.e 15 " worst case" conduits and found it was unsigned.

On Monday, July 16, 1990, TVA informed the staff that the 1987 calculation had errors in it.

By telephone on July 17, 1990, the staff requested that TVA (1) submit a justification for continued o the day (i.e., July 17,1990)peration for both Sequoyah units by the end ofand.(2)i the errors in the 1987 calculation. This meeting was held on Monday, July 23, 1990 and is summarized herein.

The agreed upon agenda for the meeting is given on page 1 of Enclosure 2.

The TVA presentation of the bacxground to this meeting is given on page 2. The 1987 " worst case" conduit selection criteria is discussed on aage 3. The categories of the ranked conduits and the relationship to eac1 criterion in the conduit selection criteria is given on page 4 The original 1987 ranking of i the conduits is presented on page 5.

l TVA stated that greater than 7000 conduits were reviewed in 1987. The 7000- I plus conduits were reduced to 770 conduits by selection criterion 1 in that l

they contained seven or more cables. The 1987 results of ranking the conduits I were 12 conduits in the " worst case" Category A. Category A were conduits that supposedly met all six conduit selection critera. These are 12 of the 15 conduits tested by TVA in 1987.

Another figure displaying the 1987 ranking of the conduits at Sequoyah is  !

Enclosure 4. This is Page 9 of the TVA handout from the May 31, 1990 meeting. '

TVA then presented its assessnent of the 1987 calculation which ranked the '

conduits at Sequoyah. This is discussed on pages 6 to 8 of Enclosure 2. TVA took a random sample of 59 conduits and the 40 top ranked conduits and recalcu- '

lated the ranking of these conduits based on the 1987 criteria. Page 8 shows

! the significant errors in the 1987 calculation, the new conduit ranking, and the change to the 1987 ranking for the appmximately 99 recalculated and 671 l

non-recalculated conduits. The number of tested conduits for each conduit category is also shown.

The changes to the 1987 ranking reflect conduits being primarily switched from higher " worst case" categories to lower categories. The " worst case" Cate- '

gory A is reduced from twelve to four conduits and all of these conduits were tested in 1987. Category D was significantly reduced from 327 conduits to 290 i conduits and Category E, the lowest category, was significantly increased from s

366 conduits to 407 conduits. However, without the recalculation of the remaining 671 conduits, there is the possibility that there may be Category A ccoduits which were previously identified in 1987 in the lower categories.

TVA then presented its current actions to resolve the issue of the errors in the 1987 " worst case" conduit selection calculation. This is pages 9 and 10 of Enclosure 2. TVA has committed to the following: (1) verify the conduit data in the 1987 calculation; (2) perform screening calculations similar to the approach by Browns Ferry in its cable testing program, which takes into

! account the 1989 Watts Bar pullby damage; (3) perform initial ranking of the conduits; (4) obtain detailed isometrics of the top-ranked conduits for SWBP l

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.- 3 calculations; (5) perform SWBP calculations; and (6) compare Sequoyah SWBP results to the SWBP for the Browns Ferry tested conduits. TVA stated it is reconsidering its 1987 consnitment to test 15 conduits of the 20 " worst-case" conduits at Sequoyah and will be looking at the testing which has been done at Browns Ferry to determine if it envelopes the " worst case" conduits at

. Sequoyah. This conduit testing was not available in 1987 when TVA made its consnitment. The staff stated that TVA must consider the problems still being identified with cable installation practices at Browns Ferry in its decision to use the results of conduits tested at Browns Ferry.

The program to determine the " worst case" conduits at Sequoyah will be in two phases based on the accessibility of conduits during the power operation of the two Sequoyah units. This is page 10 of Enclosure 2. Unit 1 has recently restarted from its Cycle 4 refueling outage; its next refueling outage is scheduled for the Fall of 1991. Unit 2 will be shutting down for its Cycle 4 refueling outage in September 1990. The top-ranked inaccessible conduits would be walked down in the next refueling outage for each unit. TVA stated that it believed that less than 20 percent of the conduits would be inaccessible. The estimated schedule to rank the accessible conduits and determine the " worst case" conduits in that group was about 8 weeks from the date of this meeting or t late September 1990.

TVAthenpresenteditsqualityassurance(QA)programtodeterminetheroot cause why the unsigned 1987 " worst case" conduit selection calculation was not reviewed and approved. The QA organization at Sequoyah will be verifying the current TVA actions discussed above and determining the root cause for the unsigned calculation. This is discussed on page 11 of Enclosure 2. The estitaated schedule to complete their report is September 7,1990.

'"T ended its presentation with the conclusions given on page 12 of l Enclosure 2. TVA stated that its review identified substantial problems l

with the 1987 conduit selection calculation. It stated that it is currently l re-evaluating the " worst-case" conduits at Sequoyah and would docket the plan j to resolve the staff's concerns in early August 1990. It further stated that l It was pursuing this plan to expeditiously resolve the cable / conduit issues at Sequoyah. [TVA submitted its plan in its letter dated August 17,1990.]

The staff provided comments on the justification for continued operation of l the Sequoyah plant that is in TVA's letter July 17, 1990. The staff stated that TVA should discuss the potential consequences of " worst case" conduits that may exist at Sequoyah but have not been tested. Enclosure 3 is a list of observations made by the staff in its evaluation of the TVA letter dated July 17, 1990. TVA committed to revise its justification for continued opera-tion for Sequoyah and submit it by Friday, July 27, 1990. Enclosure 5 is a copy of the revised justification for continued operation of Sequoyah, which l

was submitted by TVA letter dated July 27, 1990.

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4 This ended the ineeting. The meeting was transcribed and a copy of the transcription is available for public inspection at the Comission's Public Document Room, Gelman Building, 2120 L Street,'N.W., Washington, D.C., and at the Chattanooga-Hamilton County Dicentennial Library,1001 Broad Street, Chattanooga, Ltd. Suite 300, Tennessee 37402, 1612 K Street, t!.W.,or it may be purchased Washington, from Ann. Riley)& Associates, D.C. (202/293-3950 enior Project flanager Project Directorate 11-4

('DivisionofReactorProjects-1/II Office of Nuclear Reactor Regulation

Enclosures:

1. Attendance List 2., TVA Handout

3. NRP, Handout 4 Page 9 from May 31, 1990 Meeting Handout

5. Copy of TVA Letter dated July 27, 1990

6. Transcript of Heeting for NRC and Local PDR DISTRIBUTION Docket File NRC &' Local PDRs T. Murley F. Iliraglia J. Partlow A. Thadani S. Varga G. Lainas F. Hebdon S. Newberry E. Marinos J. Donohew PD II-4 Reading OGC E. Jordan ACRS (10)

R. Borchardt cc: Licensee / Applicant & Service List JD w :SNewbgf :FHeTddn  :

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l cc: l Mr. Marvin Runyon, Chairman Mr. Joseph Bynum, Acting Site Director Ter.nessee Valley Authority Sequoyah Nuclear Plant ET 12A 7A Tennessee Valley Authority 400 West Summit Hill Drive P. O. Box 2000 Knoxville, Tennessee 37902 Soddy Daisy, Tennessee 37379 l 1

Director Mr. Mark J. Bur:ynski Tennessee Valley Authority Site Licensing Manager ET 12A 11A Sequoyah Nuclear Plant 400 West Summit Hill Drive P. O. Box 2000 Knoxville, Tennessee 37902 . Soddy Daisy, Tennessee 37379 Mr. John B. Waters, Director County Judge Tennessee Valley Authority Hamilton County Courthouse ET 12A 9A Chattanooga, Tennessee 37402 400 West Summit Hill Drive Knoxville, Tennessee 37902 Regional Administrator, Region II U.S. Nuclear Regulatory Commission Nr. W. F. Willis 101 Marietta Street, N.W.

Chief Operating Officer Atlanta, Georgia 30323 ET 12B 16B 400 West Summit Hill Drive Mr. Paul E. Harmon Kncxv111c, Tennessee 37902 Senior Resident Inspector Sequoyah Nuclear Plant General Counsel U.S. Nuclear Regulatory Commission Tennessee Valley Authority 2600 Igou Ferry Road 400 West Summit Hill Drive Soddy Daisy, Tennessee 37379 ET 118 33H l Knoxville, Tennessee 37902 Mr. Michael H. Mobley, Director

!- Division of Radiological Health Mr. Dwight Nunn T.E.R.R.A. Building, 6th Floor Vice President, Nuclear Engineering 150 9th Avenue North Tennessee Valley Authority Nashville, Tennessee 37219-5404 6N 3SA Lookout Place 1101 Market Street Tennessee Valley Authority l Chattanooga, Tennessee 37402-2801 Rockville Office 11921 Rockville Pike Dr. Mark 0. Medford Suite 402 Vice President and Nuclear Rockville, Maryland 20852 Technical Director Tennessee Valley Authority Mr. Oliver D. Kingsley, Jr.

6N 38A Lookout Place Senior Vice President, Nuclear Power Chattanooga, Tennessee 37402-2801 Tennessee Valley Authority 6N 35A Lcokout Place Nr. Edward G. Wallace 1101 Market Street Manager, Nuclear Licensing Chattanooga, Tennessee 37402-2801 and Regulatory Affairs Tennessee Valley Authority SN 1578 Lookout Place l Chattanooga, Tennessee 37402-2801

, i ENCLOSURE 1-ATTENDEES AT MEETING OF JULY 23, 1990

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Name Affiliation J. Donohew NRC S. Newberry NRC E. Marinos NRC l H. Garg NRC i S. Black _ NRC l A. Thadani NRC

.B. Wilson NRC J. Brady NRC B. Hayes- NRC R. Price NRC G. Lainas NRC D. Murphy NRC M. Burzynski TVA i B. Kimsey TVA J. Bynum TVA K. Brown TVA R. Lumpkin TVA M. Medford TVA P. Trudel TVA T. Ippolito TVA '

Affiliation TVA - Tennessee Valley Authority '

NRC - Nuclear Regulatory Commission l

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} t SEQUOYAH NUCLEAR PLANT -

CABLE TEST PROGRAM INTRODUCTION AND BACKGROUND - M. J. BURZYNSKI I

r EVALUATION OF CALCULATION - K. W. BROWN CURRENT PLAN TO RESOLVE ISSUES , - K. W. BROWN REVIEW TO FIND ROOT CAUSE - R. L. LUMPKIN PURPOSE OF MEETING IS TO REVIEW RECENT FINDINGS REGARDING 1987 RANKING CALCULATION AND PRESENT CURRENT PLAN FOR RESOLUTION E l 5

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. -r SEQUOYAH NUCLEAR PLANT  !

INTRODUCTION TVA AND NRC HAVE BEEN HAVING DISCUSSIONS REGARDING THE IMPACT OF THE WBN CABLE DAMAGE AND SQN CABLE TEST PROGRAM TVA AND NRC MET IN ROCKVILLE ON THE SUBJECT ON l, MAY 31,1990 NRC CONDUCTED AN AUDIT OF THE RELATED INFROMATION AT .SQN ON JUNE 19-20, 1990 i l'

IN ADDITION NRC WAS INFORMED THAT' THE CABLE SELECTION l

CALCULATION FOR PULLBY TESTS WAS NOT ISSUED AS A RESULT OF THE AUDIT TVA AGREED TO PURSUE ISSUANCE OF TIIE CALCULATION AND AN ASSESSMENT WAS MADE OF THE WORK TO DE DONE i AS A RESULT OF AN ALLEGATION TVA SAMPLED THE SELECTION  !

CALCULATION RESULTS AND IDENTIFIED THAT DISCREPANCIES .

EXISTED TVA HAS IDENTIFIED THAT FURTHER WORK IS NEEDED WI*'H t RESPECT TO THE CABLE TEST PRQGRAM AND HAS ALSO INITIATED ACTION TO EVALUATE THE ROOT CAUSE 4

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SEQUOYAH NUCLEAR PLANT 1987 CONDUIT SELECTION CRITERIA

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1. SEVEN OR MORE CABLES IN THE CONDUIT i

2. AT LEAST TWO PULLBYS

3. h AT LEAST THREE PVC JACKETED CABLES IN THE CONDUIT BEFORE -

THE FINAL PULLBY

4. AT LEAST TWO PULLBYS BEFORE AUGUST 1984

5. TOTAL LENGTH AND DEGREES OF BENDS BETWEEN PULL FOINTS EXCEEDS OR COMES CLOSEST TO EXCEEDING TVA'S INSTALLATION SPEC DEFINITION OF AN "EAE 1 ' PULL" l G. CONDUIT CONTAINS TWO CONDLETS

7. (TIE BREAKERS)

a. AT LEAST TWO PULLBYS PhE-AUGUST 1984 VITH AT LEAST TWO CABLES WITH CPE OR CSPE JACKETS

b. MECHANICAL ASSISTANCE WAS REQUIRED

e. LENGTH BETWEEN POTENTIAL LUBRICATION POINTS EXCEEDS INSTALLATION SPEC DEFINITION OF AN " EASY PULL"

d. BENDS LOCATED NEAR THE PULLING END OF THE CONDUIT

e. CONFIGURATION WOULD NOT ALLOW LUBING AT PULL POINT r

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SEQUOYAH NUCLEAR PLANT CATEGORY / CRITERIA RELATIONSHIP CATEGORY CRITERIA MET CRITERIA "NOT" MET A -

1 THROUGH 6 B -

1 THROUGH 5 6 -

C -

1 THROUGH 4 AND 6 5 D -

1 THROUGH 4 5 OR 6 E* -

1 2 OR 3'OR 4

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• NO EVALUATION AGAINST CRITERIA 5 AND 6 NO ISOMETRIC DRAWN

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SEQUOYAH NUCLEAR PLANT ..

ORIGINAL CONDUIT RANKING NO. CONDUITS

• 400 !

300 -

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200 -

100 - '

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CAT A CAT B CAT C CAT D CAT E E TOTALS 12 10' 55 327 366 TOTAL SAFETY RELATED CONDUITS > 7000 n

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f SEQUOYAH NUCLEAR PLANT t

CALCULATION - ASSESSMENT I

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,j REVIEW INITIATED TO ASSESS ACTIONS REQUIRED TO ISSUE CALC JUNE 1990 f

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.i RANDOM SAMPLE. TO ASSESS CAIE INTEGRITY JULY 1990 i i f

- 59 CONDUITS SELECTED AT RANDOM  !

- ERRORS IDENTIFIED I

- MIS ' ' DATA  !

t REVIEW OF CALC TOP 40

- ADDITIONAL ERRORS

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CONCLUSIONS J

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SEQUOAYH NUCLEAR PLANT- *N

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CALCULATION SQN-CSS-009 FORMAT ' f CALCULATION BODY (PREPARED AND CHEQKED) $

PURPOSE

.I ASSUMPTIONS j

DESIGN INPUT . DATA j METHODOLOGY l RESULTS I CONCLUSIONS ATTACHMENTS A THROUGH F (PREPARED AND CHECKED)

WORKSHEETS ISOMETRICS SUMMARIES APPENDICIES (ALL PREPARED AND CHECKED EXCEPT 3 AND 6)-

1. CABLE SCHEDULE PRINTOUTS

2. LIST OF CONDUITS WITH 7 OR MORE CABLES

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3. CHECKLIST OF PULLBY CRITERIA APPLICATION j

4. PULLBY SKETCHES, PULL DATES AND JACKET TYPES '

5. JAMMING SKETCHES

6. VERTICAL SUPPORT APPLICATION CHECKLIST 7 VERTICAL SUPPORT WALKDOWN DATA_

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li CATEGORY DEF1!GT1026 -

. A- MEETE CIETRmA 1 TEBOUCE 8

. m - usETs CarTasEA 1 Tupouca s ecEs war unrr Curramow e SEQUOYAII NUCLEAR PLANT CAlfUIATION REVIEW

SUMMARY

. C- marts CarTama 1 TupeecM 4 AF9 8 nous per west CuTumow s NO. CONDUITS 500 ' * *~"'**'****"'"*

noss wer usuT CsertfEA 8 AN5 4

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400 - . E- NEETE CmTtm0N 1

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FAfts TO MEff CRITERIA 2 OR S OS 4 300 - NO ETA 15ATWW e REFCRMtB FOR OtmWEA S OB 4 4

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CAT A CAT B CAT C CAT D CAT E CATEGOET CBAleCES 1987 UE&C 12 10 55 327 366 7/90 REVIEW 4 10 59 290 407 go, TESTED 4 3 4 4 0 A posse a To CAT C 4 TO CAT s 5 1 FROM CAT S 1 TO Cat C 1987 UE&C 7/90 REVIEW e , ,,,, c,7 , , ,, c,7 ,

1 FRON CAT B TOTAL CONDtT. TS W/7 OR MORE CABIES - 770 g a yn0M CAT A 42 TO CAT I 1 Face C T a 1 Te CAT s 1 FROM CAT C 1 TO CAT C 1 F90M CAT E E 42 F90W CAT D 1 TO CAT B

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SEQUOYAH NUCLEAR. PLANT ~~~'!

CURPENT ACTIONS TO RESOLVE ISSUES -

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VERIFY BY SAMPLING OF SQN-CSS-009 CABLE PULL DATES, MARK NUMBERS, AND NUMBER OF PULLBYS ARE ADEQUATE FOR USE IN ]'

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IN NEW SIDEWALL BEARING PRESSURE CALCULATIONS

. PERFORM SCREENING CALCULATION SIMILAR TO BFN APPROACH <

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PERFORM INITIAL .. RANKING OF CONDUITS t OBTAIN IS0 METRICS OF TOP RANKED CONDUITS PERFORM SIDEWALL BEARING PRESSURE CALCULATIONS t

i COMPARE SQN RESULTS TO BFN TESTED CONDUITS j e

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SEQUOYAH NUCLEAR PLANT ',

SCIIEDULE FOR CABLE PROGRAM DISPOSITION -

PHASE I - 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 i CONSIDERATIONS

• WALKDOWN AND COMPLETE ISOMETRICS FOR TOP RANKED ACCESSIBLE CONDUITS f

PREPARE AND ISSUE SIDEWALL BEARING PRESSURE CALCULATIONS  !

FOR ACCESSIBLE CONDUITS --

4 COMPARE SQN SWBP VALUES TO BFN'S TESTED CONDUITS PHASE II - SCHEDULE TO COMPLETE REMAINING CONDUITS UNIT 2 - CYCLE 4 REFUELING OUTAGE (BEGIN SEPTEMBER 1990)

UNIT 1 - NEXT AVAILABLE OUTAGE OF SUFFICIENT DURATION (NO LATER THAN GYCLE 5 REFUELING OUTAGE; SCHEDULED FOR 4TH QUARTER OF 1991)

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- i QA INVOLVEMENT i

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MAINTAIN ONGOING QA VERIFICATION OF THE . CURRENT ACTIONS TO RESOLVE THE ISSUES h

DETERMINE ROOT CAUSE OF WHY THE SPECIFIC CABLE SELECTION  ;

CALCULATION WAS NOT REVIEWED AND APPROVED

- INTERVIEWS

- PAST PROGRAM REVIEW i

- CURRENT PROGRAM REVIEW i

- EVALUATION TO DETERMINE ISOLATED OR GENERIC ISSUE i

A SCHEDULE FOR LOOKBACK '

- TARGET FOR REPORT ISSUANCE - SEPTEMBER 7,1990 j r

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CONCLUSIONS-i i

j TVA'S REVIEW IDENTIFIED SUBSTANTIAL PROBLEMS WITH THE i SELECTION CALCULATION 1

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TVA~ IS RE-EVALUATING THE SQN CABLES UTILIZING; .

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- SCREENING CALCULATIONS SIMILAR 'TO BFN I

- DETAILED SWBP CALCULATIONS OF THE TOP RANKED CONDUITS l

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l TVA IS PURSUING THIS APPROACH TO EXPEDITE RESOLUTION OF i:

THE CABLE ISSUES i :.

TVA WILL DOCKET THE REVISED PLAN IN EARLY AUGUST 1990 Y

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ENCLOSURE 3 J

l SQN JC EVALUATION l.

CoverLetter(July 17, 1990 1.- Overfilled conduits: '

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Cable damage at Watts Bar not limited to overfilled conduits.

In fact, the RPS cables first identified with damage were not in overfilled conduits.

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2. Nylon (parachute cord) pull ropes:

Parachute cords were not the only source of cable damage at -

Watts Bar. SWBP calculations have demonstrated that pull tensions significantly higher then those delivered by the parachute cord ,

were applied during installation, as recognized by TVA staff (Messrs. J. Hutson, K. Brown) and documented.

3. Long conduit runs with numerous bends:

Sequoyah has not demonstrated that conduit runs are not similar to Watts Bar by the mere fact that accurate isometrics do not exist ,

for sucn comparison.

4. SWBP values at SQN below Browns Ferry:

This is inconclusive because the SQN compared conduits to Browns Ferry are not confirmed to be the " worst-case" group. Furthermore, cable damage at Watts Bar occured at lower SWBP values.

5. No cable failures from instellation damage:

Not conclusive because recent tests at Browns Ferry have discovered cable damage which had not been evident during normal plant operation for longer periods than Sequoyah.

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i ENCLOSUREJ JC0

1. It was TVA's conclusion following independent evaluation by INPO and L other consultants that cable pulling practices at both sites were.similar l by virtue of the fact that Installation Standard G-38 was equally applied. l

2. It is unclear whether the tested cables were representative of the

" worst-case" group and furthermore, the recent cable damage discovered at Brewns Ferry does not support the accuracy of dry hi-pot tests.

3. Say$ as item 4 from cover lecter. l

4. Safeasitem5fromcoverletter. Furthermore, the program cited only

. applies to medium voltage cables and not to cablesin question.

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, i ENCLOSURE 4 ORIGINAL SEQUOYAH. CABLE TEST PROGRAM (CTP) SE$,ECTIONCRITERIA

1. SEVEN OR'MORE CABLES

2. TWO OR MORE PULLBYS '

3. THREE OR MORE PVC JACKETED CABLES BEFORE 1.AST PULLBY

4. TWO PULLBYS BEFORE USE OF POLYWATER AS LUBRICANT (8/84)

5. LENGTH AND DEGREE OF BENDS MEETS OR EXCEEDS G38

6. TWO OR MORE CONDULETF MET SELECTION CRITERION (SC) 1 MET SC 1, 2, 3, &4 MET SC 1, 2, 3, 4, &6 '

MET SC 1 - 4 & S i

MET SC 1 - 6 l

(10) (18) '

(366) 0 12 22 t

40 404 77o NUMBER OF CONDUITS L

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4 TENNESSEE VALLEY AUTHORITY

'5N 157B Lookout Place 4 July 27, 1990 t

e U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 ,

Gentlemen: '

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 328 SEQUOYAH NUCLEAR PLANT (SQN) - CONDITION ADVERSE TO QUALITY REPORT (CAQR)

SQP900305 - OPERABILITY DETERMINATION ,

References:

1. TVA letter to NRC dated July 17, 1990 "Sequoyah Nuclear Plant (SQN) Units 1 and 2 - Condition Adverse to Quality -

L (CAQR) SQP900305 Revision 0 - Operability Determination"-

L l 2. TVA letter to NRC dated March 28, 1990 "Sequoyah Nuclear L Plant (SQN) - Reevaluation of Cable testing Program - Watts Bar Nuclear Plant (WBN) Pullby Damage" TVA and NRC met on July 23, 1990, in Rockville, Maryland, to discuss the

- problems recently identified by TVA with the ranking c'lculation a used to select conduits to be tested for pullby damage. TVA identified that there

.were errors in the implementation of the ranking criteria that affected the final ranking of the conduits. In conjunction with this activity TVA provided an opers.bility determination of SQN by reference 1. This determination and.the information provided by reference 2 were also discussed during the meeting. . ,

At the conclusion of the meeting TVA agreed to supplement the operability determination provided by reference 1 with the additional information presented at the meeting. 'The revised operability determination is included as enclosure 1 to this letter. This revision includes additional supporting evidence for our conclusion that the probability of cable damage from installation practices is low and that the probability is high that any significant cable damage from poor installation practices would have been ,

detected. In addition, the potential consequences of undetected cable damage

- were evaluated. In summary, there is a high degree of confidence that the SQN safety-related cables will perform their intended function.

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An Equal Opportunity r .;yer

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U.S. Nuclear Regulatory Commission In the meeting TVA discussed the corrective action plan and tentative schedule for resolution of the cable test program discrepancies identified. As noted in the meeting. TVA will provide a complete program plan description and schedule by August 17, 1990. The program plan includes a two part evaluation of the SQN safety-related conduits that may have experienced significant forces during pullby operation. Phase I involves the conduits that are-accessible during power operation; Phase II' involves inaccessible conduits.

.The operability determination will remain in effect uncil the completion of the Phase I activities. Successful resolution of Phase I will provide further compelling evidence on the adequacy of SQN cable and render Phase II a confirmatory effort. TVA intends to keep NRC fully informed of the Phase I activities and will submit a Phase I report within 30 days of completion of the Phase I efforts. Further details on reporting will be included in the program plan submittal.

The commitment made in this letter is included as enclosure 2.

Please direct questions concerning this issue to Marcia A. Cooper at (615) 843-6422.

Very truly yours, TENNESSEE VALLEY AUTHORITY '

E. G. lace Manager Nuclear Licensing and Regulatory Affairs Enclosures

! cc: See page 3 l

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U.S. Nuclear Regulatory Commission cc (Enclosures):

Ms. S. C. Black, Deputy Director Project Directorate II-4 U.S. Nuclear Regulatory Commission One White Flint, North ,

11555 Rockville Pike l Rockville, Maryland 20852 l

.. I Mr. J. N. Donohew Project Manager  ;

U.S. Nuclear Regulatory Commission l

One White Flint, North' '

11555 Rockville Pike Rockville, Maryland 20852 NRC Resident Inspector  !

Sequoyah Nuclear Plant t 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commis'sion Region II 101 Marietta Street, NW, Suite 2900 '

Atlanta, Gcorgia 30323 i

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, , J ENCLOSURE 1 SEQUCYAH NUCLEAR PLANT (SQN)

CONDITION ADVERSE TO QUALITY REPORT (CAQR) SQP900305 R0 C?ERABILITY 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 SQN. These problems were documented in CAQR SQP900305 RO. 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 employee concerns related to cable installation. SQN did not have any substantiated cable installation employee concerns. The WBN concerns were investigated at SQN because.at the time there were the questions whether the configurations an( the cable pulling methods for both plants were similar. Subsequently, SQN conducted extensive reviews of the cable raceway systems and the attributes that contribute to the possibility that 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 supported 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. No programmatic problems related to cable installation practices have been identified at SQN during the extensive' cable work associated with all the restart efforte and recent refueling outages.

As a prelude to the SQN efforts 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 from 1973 to 1979, they did not find that the conduit configurations differed significantly from other nuclear plants of SQN's vintage. Recent comparisons of conduit configurations have shown that SQN's installations more closely ;e.3mble those at Browns Ferry Nuclear Plant (BFN). The short runs wi'.n many iull points translate into " easy pulls." This conduit information is also supported by the comparison of the current SQN-calculater sidewall bearing pressure (SWBP) values to the BFN values for their condt.its selected for testing. The SQN conduits evaluated represent some of the most severe SQN configurations, as identified by either criteria 5 of the SQN CTP or the BFN screening criteria method. As such, TVA has a high confidence that the SWBP values for the conduits and cables successfully tested at BFN fully bound the current SWBP values for SQN.

These reviews and evaluations lead to the conclusion that SQN conduit

configurations are not the same as WBN and SQN does not exhibit the same l programmatic problems that have been discovered and documented at WBN.

The problems identified at WBN are in the areas of conduit configuration (long runs with excessive bends between pull points) and cable pulling i

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• e practices (nylon parachute cords). The conduit configurations depart from  !

the requirements of the IVA General Construction Specifications and industry good practices. The SQN CTP Conduit Selection Criterion 5 focuses on the conduits that exceed the TVA General Construction Specifications definition of an easy pull for lengths of conduits and number of bends between pull points. A review of field sketches for over 350 safety-related conduits that contain at least seven cables and have at least two pullbys reveal that only a small number-(14) of that population exceed.TVA's definition of an easy-pull. In additive, seven of those conduits were direct current (de) high-voltage tested.L Since the major factors in SWBP calculations are the lengths of conduit and the degrees of bends between pull points. TVA concludes that SQN has a smaller probability of having conduits with excessive SWBP than WBN. Also, no evidence exists that nylon parachute cords were utilised at SQN.

While SQN has not fully resolved the issue of conduit overfill, a review of 181 conduits evaluated at SQN using the BFN screening methodology revealed only one conduit that was overfilled (40 percent allowable.

42 percent calculated). In contrast the WBN pullby corrective action plan >

included direct consideration for overfill in the screening process because of problems identified there with overfill. The industry has only recently recogrized the significance of conduit fill as a risk factor when performing pula,ys. Lower fills increase the potential for obtaining a clear path during the pullby operation. The raceway fill at SQN ensures that fewer pullbys occurred, and that those that did would be small and with less potential for pullby damage.

Because of these facts. 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 cable pulling practices.

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 l

the purpose of detecting damage caused by pullbys, jamming, 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 de. The three wet-tested pullby conduita remain in the population with a higher potential for pullby damage. It is also important to note that the test anomaly with the American Insulated Wire Company (AIW) silicone-rubber cable (which was not discernable to the naked eye) was detected with a dry high-potential test. This fact also highlights the importance of material susceptibilities. The SQN CTP represents the most comprehensive in-situ test program ever undertaken in the industry.

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SQN's CTP selection criteria was biased toward material damage susceptibility. However, even though discrepancies have been discovered in the unissued caleclation to document ~tha application of the selection criteria, TVA has confirmed that seven of the original 15 tested pullby conduits 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 would likely have been found.- In addition, the AIW silicone rubber cables inside containment were replaced at SQN and the PN-type cable was not used at SQN in 10 CFR 50.49 applications.

Fifty-five SQN conduits were'also evaluated for SWBP. Fifteen were the tested conduits from the material susceptible population.and 40 were the highest ranked by the BFN screening criteria from the remainder of the population with seven or more cables. Overall, these conduits represent some of the " worst-case" from a configuration (and force) perspective.

The SWBPs were bounded by the BFN wet-tested conduits. Therefore, it is reasonable to conclude that the forces developed in these conduits are not great enough to cause cable damage. It is also reasonable to conclude that these tests bound all SQN conduits because of the similarity between the.SQN and BFN conduit configurations, the comparable sample of SWBP calculations performed for SQN, and the other favorable conduit attributes previously described. Based on the similarities in the conduit c nfigurations between the two plants, it is expected that the SQN

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calculated SWBP values for the future conduit calculations will remain bounded by the BFN results. '

t-l In January 1989, SQN 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 esbles l have been identified as incapable of performing their safety-related l function by this program. Additionally, many maintenance and modification i

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 prcctices 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 SQN and BFN CTPs are the basis for this increased confidence.

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3. Consequences of Undiscovered Cable Damage l 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 l types of failure mechanisms that might occur.

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.The first' type is the random failure. 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 fai^ure'is mitigated by the fact that the redundant circuit for the failed cable is expected to perform the safety-related function L that might be lost by the cable failure. The effects of a random failure i are inconsequential because of the redundancy, diversity, and defense in i l' depth afforded by the standard design requirements. For example, the  ;

effects of a: faulted cable inside containment during a loss of coolant i l accident on containment integrity are mitigated by the diverse and  !

lI redundant penetration overcurrent protection design (fuse and breaker i l- combination). . The effects on emergency safeguerds actuation are mitigated  ;

by the redundant and diverse design of the reactor protection system (e.g I

2/3 and 2/4 logic con binations 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 failure is primarily related to environmental conditions (water, steam, and humidity) created by an accident. For the purposes of this l

discussion, the environmental conditions will be seperated into those inside containment and those outside containment. i For the cables inside containment, there are several factors that support the adequacy of the installed safety-related cables. Because the containment eq2ipment 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. In particular, of the top ranked conduits from the SQN SWBP screening activitie~s, 2 conduits were inside containment. 10 were in the secondary containment (annulus) area, and 30 were in the control and auxiliary buildings.

Redundant safety-related equipment is physically separated and compartmented by concrete walls and barriers inside containment to previde 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 failure from undetected cable damage is unlikely.

1 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 L safety function required for events th3t 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 u

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. 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 wates 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 AB, as well as the CB, where a large number of pullbys occur, the environment is considered mild and is therefore not impacted by adverse effects of an accident that would create a potential consoon mode failure awchanism from undetected cable damage.

Conclusion The probability of cabic damage during installation is low. Substantial evidence from a variety of sources establishes that the SQN conduits are typical of its vintage of nuclear plant and that there are no programmatic cable installation problems.

The probability that significant cable damage would have been identified is high. The SQN CTP results provide a high degree of confidence that cable damage in material susceptible cable would have been detected. The BFN CTP 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 nature of the SQN conduit configurations 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. Consnon mode failures from undetected cable damage are highly unlikely. The most severe environments (inside containment) that might trigger the common 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 that are strictly mild environments and unlikely to initiate common mode failures. In

, addition, the separation and protection f9atures incorporated for other programs (e.g., fire protection, moderate energy line break flooding, and high energy like break protection) provide additional protection from environmental effects. These features further lessen the likelihood of consnon mode failure.

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

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o ENCLOSURE 2 TVA will provide a complete program plan description and schedule by August 17, 190.

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ENCLOSURE 6 OFFICIAL TRANSCRIPT OF PROCEEDINGS MEETING ON SEQUOYAH NUCLEAR PLANT CABLE TESTING PROGRAM Available to the public at the Conmission's Public Document Room, Gelman Building, 2120 L Street, N.W.,

Washington, D.C., and at.the Chattanooga-Hamilton County Bicentennial Library, 1001 Broad Street, Chattanooga, Tennessee 37402, or may be purchased from Ann Riley &

Associates, Ltd., Suite 300, 1612 K Street, N.W.,

Wash!.igton D.C. (202-293-3950).

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s e = l 4 1 This ended the meeting. The meetir.g was transcribed and a copy of the transcription is available for public inspection at the Comission's Public Docurnent Room, Gelman Building, 2120 L Street, N.W., Washington, D.C., and at the Chattanooga-Hamilton County Bicentennial Library,1001 teoad Street, Chattar.coga, Ltd. Suite 300, 1612 Tennessee K Street,37402, or it may beD.C.

N.W., Washington, purchased (202/293from 39MAnn . Riley)& Associate 1

b enior Project Manager

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Project Directorate II-4 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation

1. Attendance List

2. TVA Handout

3. NRR Handout

4. Page 9 from May 31, 1990 Mceting Handout l

5. Copy of TVA Letter dated July 27,1990 i

6. Transcr!pt of Meeting for NRC and Local PDR DISTRIBUTION Decket File NRC & Local PDRs T. Murley F. Iliraglia

• J. Partlow A. Thadani

5. Varga G. Lainas F. Hebdon S. Norberry E. Marinos J. Donohew PD II-4 Reading OGC E. Jordan ACRS(10)

R. Borchardt ec: Licensee / Applicant & Service List

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Docket flos. 50-327 and 50-328 LICEllSEE: Tennessee Valley Authority (TVA)

FACILITY: Sequoyah f4uclear Plant, Units 1 and 2

SUBJECT:

Slt'ItARY Of THE JULY 23, 1990 l'EETitlG ON SEQUOYAH CABLE / CONDUIT TESTit4G PROGRAli FOR SAFETY-RELATED CABLE On !?ct cay, July 23, 1990, a neeting was bcid at the headquarters of the Divisicr. of Etactor Frojects - Region 1/11, Office of !?uclear Reactor Fegulation (l:PR),1:00, in Rockvillt , l'aryland. The inecting was between the lif R staff and TVA's representatives. It was held at the rt-quest of tlER to ,

ciscuss the cable / conduit testing progran for safety-related cables at '

Sec;uoych. Enclosure 1 is the list of ir.dividuals who attended the icetting, Enclosurt 2 is the bar,dout presented by TVA in the teeting, and Enclosure 3 is the handcut presented by liLR in the recting. The folicwing is a surrary of the sigt.ificer,t itet:s discussed nd the actions, if any, taken or proposed.

The Stquoyah ctble te sting progran, wes first developed in 1987 to address the staff's concerns about potential cat le damage during cable installaticr. in ccr.duits fron three situations: (1) cable pullbys, (2) cable jaming, and (3) vcrtical cable supported by 90-c'cgree coridulets. High potential ttsts were conducted in 1907 on IE " worst case" ccr.duits selected by agreed-upon critu ie. Th( staff's review of this cable testing program was pcrt of its rt. view of the rt start of Sequoyah frcra its extended shutdown from 1985 to 19EE and is c'iscusscci in Secticin 2.12, Cabic Insta11atior , of flVREG-1232, Volutte 2, on the Sequoyah i:ucletr Performance Plan. This Safety Evoluction Report was isstad ty the stiff's letter dated I:ay 18, 1980 as part of its approval for i Sequoyah l' nit 2 to restart. In Section 3.12, ite staff concluded that the  ;

Sequoyeh cable testing program was acceptable for the restart of Sequcyah Units I cnd 2.

In 19P9, significant cable pullby darrage was discovered at Watts Bar. By telephone in Decerrkr 1969, the staff requested that TVA evaluate the condition of the safety-related cables et Sequoyah in terns of the cable dan. age discovered at Watts Bar. This evaluttion was submitted in the TVA letter dated l' arch 20, 1990. TVA concluded in its letter that the previous conclusicns drawn f rom the 1987 cable testing progran, regarding the integrity of safety-rclated cables et Sequoyah are still valid. A meeting was held with TVA cn l'.ay 31, 1990 10 discuss the TVA letter dated flarch 28, 1990. The neeting sutrity was istutd by the staff on July 5,1990.

Af ter the t'cy 31, 1990 teeting, the staff decided to conduct an inspection at the Scquoyah site or June 19 to 21,1990 and review the calculations on cabic sidcwcil betring pressure (SLLP) for ten cerduits which were net available during the l'ty 31, 1990 iteet i ng . This is discussed in the rreting sumrrary

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dated July 5, 1990. In the inspection, the staff requested the 1987 calcula-tion which determined the 15 " worst case" conduits and found it was unsigned.

On Monday, July 16, 1990, TVA infomed the staff that the 1987 calculation had '

errors in it.

By telephone on July 17,1990, the staff requested that TVA (1) submit a justification for continued o the day (i.e., July 17,1990)peration for both Sequoyah units by the end ofand (2 the errors in the 1987 calculation. This meeting was held on Monday, July 23, 1990 and is sumarized herein.

The agreed upon agenda for the meeting is given on page 1 of Enclosure 2.

The TVA presentation of the ba:kground to this meeting is given on page 2. The 1987 " worst case" conduit selection criteria is discussed on ange 3. The categories of the ranked conduits and the relationship to eac1 criterion in the conduit selection criteria is given on page 4 The original 1987 ranking of the conduits is presented en page 5.

TVA stated that greater than 7000 conduits were reviewed in 1987. The 7000-plus cer.duits were reduced to 770 conduits by selection criterion 1 in that they contained seven or more cables. The 1987 results of ranking the conduits were 12 conduits in the " worst case" Category A. Category A were conduits that supposedly met eli six conduit selection critera. These are 12 of the 15 cor.duits tested by TVA in 1987.

Another figure displaying the 1987 ranking of the conduits at Sequoyah is Enclosure 4 This is Page 9 of the TVA handout from the May 31, 1990 meeting.

TVA then presented its assesstnent of the 1987 calculation which ranked the corduits at Sequoyah. This is discussed on pages 6 to 8 of Enclosure 2. TVA took a rendon sarnple of 59 conduits and the 40 top ranked conduits and recalcu-lated the ranking of these conduits based on the 1987 criteria. Page 8 shows the significent errors in the 1987 calculation, the new conduit ranking, and the change to the 1987 ranking for the approximately 99 recalculated and 671 non-rtcalculated conduits. The number of tetted conduits for each conduit category is also shown.

The charges to the 1987 ranking reflect conduits being primarily switched from

, higher

• worst case" categories to lower categories. The " worst case" Cate-gory A is reduced from twelve to four conduits and all of these conduits were tested in 1987. Category D was significantly reduced from 327 conduits to 290 conduits and Category E, the lowest category, was significantly increased from 366 conduits to 407 conduits. However, without the recalculation of the remaining 671 conduits there is the possibility that there may be Category A ccnduits which were pre,viously identified in 1987 in the lower categories.

TVA ther, presentved its current actions to resolve the issue of the errors in the 1987 " worst case" conduit selection calculation. This is pages 9 and 10 of Enclosure 2. TVA has committed to the following: (1) verify the conduit data in the 1987 calculation; (2) perform screening calculations similar to the approach by Browns Ferry in its cable testing program, which takes into account the 1989 Watts Bar pullby damage; (3) perform initial ranking of the conduits;(4)obtaindetailedisometricsofthetop-rankedconduitsforSWBP

3 calculations; (5) perform SWBP calculations; and (6) compare Sequoyah SWBp results to the SWBp for the Browns Ferry tested conduits. TVA stated it is reconsidering its 1987 comitment to test 15 conduits of the 20 " worst-case" conduits at Sequoyah and will be looking at the testing which has been done at Browns Ferry to determine if it envelopes the " worst case conduits at Sequoyah.

This conduit testing was not available in 1987 when TVA made its comitment.

identified with cable installation practices at Browns Ferry in its decis

• to use thc results of conduits tested at Browns Ferry.

1 The program to determine' the " worst case" conduits at Sequoyah will be in two phases based on the accessibility of conduits during the power operation of the two Sequoyah units. This is page 10 of Enclosure 2.

Unit I has recently restarted from its Cycle 4 refueling outage; its next refueling outage is scheduled for the Fall of 1991.

refueling outage in September 1990. Unit The 2top-ranked will be shutting down for inaccessible its Cycle conduits 4 would be walked down in the next refueling outage for each unit. TVA stated that it believed that less than 20 percent of the conduits would be inaccessible. The estim6ted schedule to rank the accessible conduits and determine the " worst ,

case" conduits1990.

late September in that group was about 8 weeks from the date of this meeting or TVA teen presented its quality assurance (QA) program to determine the root cause Mhy the unsigned 1987

• worst case" conduit selection calculation was not revicwec' and approved.

The QA organization at Sequoyah will be verifying the current TVA actions discussed above and determining the root cause for the unsigned calculation. This is discussed on page 11 of Enclosure 2.

The estimated schedule to complete their report is September 7,1990.

TVA ended its presentation with the conclusions given on page 12 of Enclosure ?. TVA stated that its review identified substantial problems with the 1987 conduit selection calculation. It stated that it is currently re-evaluating the " worst-case" conduits at Sequoyah and would docket the plan to resolve the staff's concerns in early August 1990. It further stated that it was pursuing this plan to expeditiously resolve the cable / conduit issues at Sequoyah.

[TVAsubmitteditsplaninitsletterdatedAugust 17,1990.]

The staff provided comments on the justification for continued operation of the Sequoyah plant that is in TVA's letter July 17, 1990. The staff stated that TVA should discuss the potential consequences of " worst case" conduits that may exist at Sequoyah but have not been tested. Enclosure 3 is a list of observations made by the staff in its evaluation of the TVA letter dated July 17,1990. TVA committed to revise its justification for continued opera-tion for Sequoyah and submit it by Friday, July 27, 1990. Enclosure 5 is a copy of the revised justification for continued operation of Sequoyah, which was submitted by TVA letter dated July 27, 1990.

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This ended the meetino. The meeting was transcribed and a copy of the trerscription is ava'dable for public inspection at the Comission's Public Document Room, Gelman Building, 2120 L Street, N.W., Washington, D.C., and at the Chattanooga-Hamilton County Bicentennial Library,1001 Broad Street, Chattanooga, Ltd. Suite 300,1612Tennesset K Street, N.W. 37402, or itD.C.

, Washington, may be purchased (202/293-3950 . from Ann Riley)&

Y d Jack N. Donohew, SenionProject Manager Project Directorate II-4 IDivision of Reactor Projects - 7/II Office of Nuclear Reactor Regulation

1. Attendance List

2. TVA Handout

3. NRR Handout

4. Page 9 from May 31, 1990 Meeting Handout

5. Copy of TVA Letter dated July 27,1990

6. Transcript of Meeting for NRC and Local FDR Ps

cc:

Mr. Marvin Runyon, Chaiman Mr. Joseph Bynum, Acting Site Director Ter.r.essee Valley Authority Sequoyah Nuclear Plant ET 12A 7A Tennessee Valley Authority 400 West Summit Hill Drive P. O. Box 2000 Knoxville, Tennessee 37902 Soddy Daisy, Tennessee 37379 Director Mr. Mark J. Burzynski Tennessee Valley Authority Site Licensing Manager ET 12A 11A Sequoyah Nuclear Plant 400 West Surrnit Hill Drive P. O. Box 2000 Knoxville, Tennessee 37902 -

Soddy Daisy, Tennessee 37379 Mr. John P. Waters, Director County Judge Tennessee Valley Authority Hamilton County Courthouse ET IPA 9A Chattanooga, Tennessee 37402 400 West Summit Hill Drive Knoxville, Tennessee 37902 Regional Administrator, Region 11 U.S. Nuclear Regulatory Commission tir. W. F. Willis 101 Marietta Street, N.W.

Chief Operating Officer Atlanta, Georgia 30323 ET 12B 16B 400 West Sumit Hill Drive Mr. Paul E. Hamon Encxville, Tenuc'see 37902

, Senior Resident Inspector Sequoyah Nuclear Plant General Counsel U.S. Nuclear Regulatory Commission Tennessee Valley Authority 2600 Igou Ferry Road 400 West Summit Hill Drive Soddy Daisy, Tennessee 37379 ET 11B 33H Knoxville, Tennessee 37902 l'r. Michael H. Mobley, Director Division of Radiologic 1 Health fir. Dwight Nunn T.E.R.R.A. Building, 6 tis Floor Vice President, Nuclear Engineering 150 9th Avenue North Tennessee Valley Authority Nashville, Tennessee 37219-5404 6N 3SA Lookout Place 1101 Market Street Tennessee Valley Authority Chatteroopa Tennessee 37402-2801 Rockville Office 11921 Rockville Pike Dr. Mark 0. Medford Suite 402 Vice President and Nuclear Rockville, Maryland 20852 Technical Director Tennessee Valley Authority Mr. Oliver D. Kingsley, Jr.

6N 38A Lookout Place Senior Vice President, Nuclear Power Chattanooga, Tennessee 37402-2801 Tennessee Valley Authority 6N 38A Lookout Place tir. Edward G. Wallace 1101 Market Street fianager, Nuclear Licensing Chattanooga, Tennessee 37402-2801 and Regulatory Aff airs Tennessee Valley Authority SN 157B Lookout Place Chattanooga, Tennessee 37402-2801 1

ENCLOSURE 1 ATTENDEES AT HEETING OT JULY 23, 1990 Name Affiliation J. Donohew NRC S. Newberry NRC E. Marinos NRC H. Garg NRC S. Black NRC A. Thedani NRC' B. Wilson NRC J. Brady NRC B. Hayes NRC R. Price NRC G. Lainas NRC D. Murphy NRC M. Burzynski TVA B. Kimsey TVA J. Bynum TVA K. Brown TVA R. Lumpkin TVA P. Medford TVA P. Trudel TVA T. Ippolito TVA A,ffiliation TVA - Tennessee Valley Authority

• f RC - Nuclear Regulatory Commission

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SEQUOYAII NUCLEAR PLANT CAELE TEST PROGRAM INTRODUCTION AND BACKGROUND - M. J. BURZYNSKI EVALUATION OF CALCULATION - K. W. BROWN CURRENT PLAN TO RESOLVE ISSUES - K. W. BROWN REVIEW TO FIND ROOT CAUSE - R. L. LUMPKIN PURPOSE OF MEETING IS TO REVIEW RECENT FINDINGS REGARDING 1987 RANKING CALCULATION AND PRESENT CURRENT PLAN FOR RESOLUTION 9

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SEQUOYAII NUCLEAR PLANT INTRODUCTION TVA AND NRC IIAVE BEEN IIAVING DISCUSSIONS REGARDING TIIE IMPACT OF TIIE WBN CABLE DAMAGE AND SQN CABLE TEST PROGRAM TVA AND NRC MET IN ROCKVILLE ON TIIE SUBJECT ON MAY 31,1990 NRC CONDUCTED AN AUDIT OF TIIE RELATED INFROMATION AT SQN ON JUNE 19-20, 1990 IN ADDITION NRC WAS INFORMED TIIAT TIIE CABLE SELECTION CALCULATION FOR PULLOY TESTS WAS NOT ISSUED AS A RESULT OF TIIE AUDIT TVA AGREED TO PURSUE. ISSUANCE OF TIIE CALCULATION AND AN ASSESSMENT WAS MADE OF TIIE WORK TO BE DONE i l

l AS A RESULT OF AN ALLEGATION TVA SAMPLED THE SELECTION CALCULATION RESULTS AND IDENTIFIED TIIAT DISCREPANCIES EXISTED

- TVA IIAS IDENTIFIED TIIAT FURTilER WORK IS NEEDED WITII RESPECT TO TILE CABLE TEST PR() GRAM AND IIAS ALSO INITIATED ACTION TO EVALUATE TIIE ROOT CAUSE L .

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SEQUOYAII NUCLEAR PLANT 1987 CONDUIT SELECTION CRITERIA

1. SEVEN OR MORE CABLES IN TIIE CONDUlT

2. AT LEAST TWO PULLBYS

3. AT LEAST TilREE PVC JACKETED CABLES IN TIIE CONDUIT BEFORE TIIE FINAL PULLBY

4. AT LEAST TWO PULLBYS BEFORE AUGUST 1984

5. TOTAL LENGTH AND DEGREES OF BENDS BETWEEN PULL POINTS EXCEEDS OR COMES CLOSEST TO EXCEEDING TVA'S INSTALLATION SPEC DEFINITION OF AN " EASY PULL" G. CONDUIT COMTAINS TWO CONDULETS

7. (TIE BREAKERS)

a. AT LEAST TWO PULLBYS PRE-AUGUST 1984 WITII AT LEAST TWO CABLES WITII CPE OR CSPE JACKETS

b. MECHANICAL ASSISTANCE WAS REQUIRED c.

LENGTII BETWEEN POTENTIAL LUBRICATION POINTS EXCEEDS INSTALLATION SPEC DEFINITION OF AN " EASY PULL"

d. BENDS LOCATED NEAR Tile PULLING END OF Tile CONDUIT

c. CONFIGURATION WOULD NOT ALLOW LUBING AT PULL POINT 3

l SEQUOYAII NUCLEAR PLANT CATEGORY / CRITERIA RELATIONSIIIP l

CATEGORY CRITERIA MET CRITERIA "NOT" MET i

A -

1 TIIROUGli 6 B -

1 TIIROUGII 5 6 C -

1 TIIROUGII 4 AND 6 5 D -

1 TIIROUGII 4 5 OR 6 E* -

1 2 OR 3 OR 4

• NO EVALUATION AGAINST CRITERIA 5 AND 6 NO ISOMETRIC DRAWN

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I SEQUOYAH NUCLEAR PLANT ORIGINAL CONDUIT RANKING NO. CONDUITS i

400 !

i l 300 -

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200 -

~

l 100 -

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O- l CAT A

. A.7 CAT B CAT C CAT D CAT E

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1 TOTALS 12 10 ' 55 327 366 TOTAL SAFETY RELATED CONDUITS > 7000 i

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SEQUOYAH NUCLEAR PLANT CALCULATION ASSESSMENT

- REVIEW INITIATED TO ASSESS ACTIONS REQUIRED TO ISSUE CALC JUNE 1990 RANDOM SAMPLE TO ASSESS CALC INTEGRITY JULY 1990

- 59 CONDUITS SELECTED AT RANDOM

- ERRORS IDENTIFIED

- MISSING DATA

- REVIEW OF CALC TOP 40

- ADDITIONAL ERRORS

- CONCLUSIONS

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SEQUOAYH NUCLEAR PLANT CALCULATION SQN-CSS-000 FORMAT CALCULATION DODY (PREPARED AND CIIECKED)

PURPOSE ASSUMPTIONS DESIGN INPUT DATA METIIODOLOGY RESULTS CONCLUSIONS ATTACIIMENTS A TIIROUGII F (PREPARED AND CIIECKED)

WORKSIIEETS IS0 METRICS SUMMARIES t

i APPENDICIES (ALL PREPARED AND CIIECKED EXCEPT 3 AND 6)

1. CABLE SCIIEDULE PRINTOUTS

2. LIST OF CONDUITS WITII 7 OR MORE CABLES

3. CIIECKLIST OF PULLBY CRITERIA APPLICATION

4. PULLBY SKETCIIES, PULL DATES AND JACKET TYPES

5. JAMMING SKETCIIES G. VERTICAL SUPPORT APPLICATION CIIECKLIST

7. VERTICAL SUPPORT WALKDOWN DATA 7

CATECORY DEFINIT 1026 a - MEETS esWTEMa 1 TMDOUCat 4

. 5- #fETs CNTtsEn 1 TMDCTCH s acts wc? mest cseressow e SEQUOYAll NUCLEAR PLANT CAlfUIATION REVIEW

SUMMARY

. C - meets csuTesus t Tsocecw a aws e oors per meet csurtMon s NO.CONDUff3 500 , . e - weets cuma 1 wooeca e eoes per mesT csstassa e aus e

. t- seats cuoreseen t Paris To meet o7ssna a os s os a 300 - , so svassaTen reasopues roe Corsema e en e 100 -

0 ' '

[- 4 O

CAT A CAT B CAT C CAT D CAT E CA'ECCItY CHAMCES 1967 UE&C 12 10 55 327 366 7/90 REVIEW 4 10 59 290 407 c,,

TES" LED 4 3 4 4 0 a pops e To of C 4 TO Cat 3

' 5 FDMsGTS 1TOGTC 1987 UE&C C 7/90 REVIEW e ,,,,,c,,, , ,, c,, ,

a room Caf e 7011L CONDt1TS T/7 OR tIORE CABIES - 776 , , ,30es OT a 43 TO Cat t a reens Caf a a to Cat s 1 enes CAT C 1 TO CAT C tITseM CAT E I E A2 reens CAT 3 1 TO OT S e

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, _ _ _ _ _ _ _ _ _ _ _ _ _ _ , u_ - -.--x-_ _ _- -----__

c SEQU0YAII NUCLEAR PLANT CURRENT ACTIONS TO RESOLVE ISSUES VERIFY BY SAMPLING OF SQN-CSS-009 CABLE PULL DATES, MARK NUMBERS, AND NUMBER OF PULLB1 'RE ADEQUATE FOR USE IN IN NEW SIDEWALL BEARING PRESSUhi ..,LCULATIONS PERFORM SCREENING CALCULATION SIMILAR TO BFN APPROACII PERFORM INITIAL RANKING OF CONDUITS OBTAIN IS0 METRICS OF TOP RANKED CONDUITS PERFORM SIDEWALL BEARING PRESSURE CALCULATIONS COMPARE SQN RESULTS TO BFN TESTED CONDUITS l

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SEQUOYAH NUCLEAR PLANT SCIIEDULE FOR CABLE PROGRAM DISPOSITION q PIIASE I - G TO 8 WEEKS FOR COMPLETION OBTAIN FIELD SKETCIIES AND CABLE DATA ~

(APPROXIMATELY 260 CONDUITS)

- PERFORM SCREENING CALC (APPROXIMATELY 560 CONDUITS)

IDENTIFY TIIOSE TIIAT ARE INACCESSIBLE DUE ' TO ALARA CONSIDERATIONS WALKDOWN AND COMPLETE IS0 METRICS FOR TOP RANKED ACCESSIBLE CONDUITS PREPARE AND ISSUE SIDEWALL BEARING PRESSURE CALCULATIONS FOR ACCESSIBLE CONDUITS COMPARE SQN SWBP VALUES TO BFN'S TESTED CONDUITS

PIIASE II - SCIIEDULE TO COMPLETE REMAINING CONDUITS UNIT 2 - CYCLE 4 REFUELING OUTAGE (BEGIN SEPTEMBER 1990)

UNIT 1 - NEXT AVAILABLE OUTAGE OF SUFFICIENT DURATION (NO LATER TIIAN CYCLE 5 REFUELING OUTAGE:

SCIIEDULED FOR 4TII QUARTER OF 1991)

IO

SEQUOYAH NUCLEAR PLANT QA INVOLVEMENT MAINTAIN ONGOING QA VERIFICATION OF TIIE CURRENT ACTIONS TO RESOLVE TIIE ISSUES DET8RMINE ROOT CAUSE OF WIIY TIIE SPECIFIC CABLE SELECTION CALCULATION WAS NOT REVIEWED AND APPROVED

- INTERVIEWS

- PAST PROGRAM REVIEW

- CURRENT PROGRAM REVIEW

- EVALUATION TO DETERMINE ISOLATED OR GENERIC ISSUE SCIIEDULE FOR LOOKBACK

- TARGET FOR REPORT ISSUANCE - SEPTEMBER 7,1990 e

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SEQUOYAH NUCLEAR PLANT CONCLUSIONS TVA'S REVIEW IDENTIFIED SUBSTANTIAL PROBLEMS WITil TIIE SELECTION CALCULATION TVA IS RE-EVALUATING TIIE SQN CABLES UTILIZING:

- SCREENING CALCULATIONS SIMILAR TO BFN

- DETAILED SWBP CALCULATIONS OF TIIE TOP RANKED CONDUITS TVA IS PURSUING TIIIS APPROACII TO EXPEDITE RESOLUTION OF TIIE CABLE ISSUES i

i TVA WILL DOCKET THE REVISED PLAN IN EARLY AUGUST 1990 12.

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ENCLOSURE 3 i

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nw SQN JC EVALUATIO!!} .

CoverLetter(July 17, 1990 l l

1. Overfilled conduits:

Cable damage at Watts Bar not limited to overfilled conduits.

In fact, the RPS cables first identified with damage were not in overfilled conduits.

2. Nylon (parachute cord) pull ropes: ,

Parachute cords were not the only source of cable damage at -

Watts Bar. SWBP calculations have demonstrated that pull tensions significantly higher then those delivered by the parachute cord ,

were applied during installation, as recognized by TVA staff (Messrs. J. Hutson, K. Brown) and documented.

3. Long conduit runs with numerous bends:

Sequoyah has not demonstrated that conduit runs are not similar to Watts Bar by the mere fact that accurate isometrics do not exist '

for such comparison.

4. SWBP values at SQN below Browns Ferry:

This is inconclusive because the SQN compared conduits to Browns Ferry are not confirmed to be the " worst-case" group. Furthermore, cable damage at Watts Bar occured at lower SWBP values.

5. No cable failures from inste11ation damage:

Not conclusive because recent tests at Browns Ferry have discovered cable damage which had not been evident during normal plant operation for. longer periods than Seauoyah.

'. ENCLOSUREjg JC0

1. It was TVA's conclusion following independent evaluation by INPO and ,(

other consultants that cable pulling practices at both sites were.similar by virtue of the fact that Installation Standard G-38 was equally applied.

2. It is unclear whether the tested cables were representative of the

" worst-case" group and furthermore, the recent cable damage discovered at Browns Ferry does not support the accuracy of dry hi-pot tests.

3. Saf$ as item 4 from cover letter.

4. SaEeasitem5fromcoverletter. Furthermore, the program cited only applies to medium voltage cables and not to cablesin question.

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ENCLOSURE 4

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ORIGINA', SEQUOYAH CABLE TEST PROGRAM (CTP) SELECTION CRITERIA

1. SEVEN OR MORE CABLE 3

2. TWO OR MORE PULLBYS

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3.

THREE OR MORE PVC JACKETED CABLES BEFORE LAST PULLBY

4. TWO PULLBYS BEFORE USE OF POLYWATER AS LUBRICANT (8/84)

S. LENGTH AND DEGREE OF BENDS MEETS OR EXCEEDS G38

6. TWO OR MORE CONDULETU" '

4 MET SELECTION CRITERION (SC) 1 MET SC 1, 2, 3, &4 MET SC 1, 2, 3, 4, &6 '

MET SC 1 -

4&5 .

MET SC 1 - 6 1

(10) (18)

(366) 0 12 22 40 404 770 NUMBER OF CONDUITS l

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4 TENNESSEE VALLEY AUTHORITY

$N 157B Lookout Place 3 July 27, 1990 U.S. Nuclear Regulatory Comission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUC1. EAR PLANT (SQN) - CONDITION ALVERSE TO QUALITY REPORT (CAQR)

SQP900305 - OPERABILITY DETERMINATION

References:

1. TVA letter to NRC dated July 17, 1990, "Sequoyah Nuclear Plant (SQN) Units 1 and 2 - Condition Adverse to Quality (CAQR) SQP900305 Revision 0 - Operability Determination" -

. TVA letter to NRC dated March 28, 1990, "Sequoyoh Nuclear Plant (SQN) - Reevaluation of Cable testing Program - Watts Bar Nuclear Plant (WBN) Pullby Damage" TVA and NRC met on July 23, 1990, in Rockville, Maryland, to discuss the problems recently identified by TVA with the ranking calculation used to  !

select conduits to be tested for pullby damage. TVA identified that there were errors in the implementation of the ranking criteria that affected the -

final ranking of the conduits. In conjunction with this activity. TVA provided an operability determination of SQN by reference 1. This determination and the information pro 4'ed by reference 2 were also discussed during the meeting.  ;

At the conclusion of the meeting 'IVA agreed to supplement the operability l determination provided by reference 1 with the additional information presented at the meeting. The revised operability determination is included as enclosure 1 to this letter. This revision includes additional supporting evidence for our conclusion that the probability of cable damage from inetallation practices is low and_that the probability is high that any significant cable damage from poor installation practices would have been detected. In addition, the potential consequences of undetected cable damage were evaluated. In summary, there is a high degree of confidence that the SQN safety-related cables will perform their intended function.

i 900 SOP 6;f.3 P00727 '

l p tig ADOC.ec. 03OO93p

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A An rn oMDmarhuutulgow#em _ -_ , 3

U.D. Nuclear Regulatory Commission In the meeting TVA discussed the corrective action plan and tentative schedule for resolution o' the cable test program discrepancies identified. As noted in the meeting, TVA will provide a complete program plan description and schedule by August 17, 1990. The program plan includes a two part evaluation of the SQN sa'ety-related conduits that may have experienced significant forces during pullby operatien. Phase I involves the conduits that are accessible during power operation; Phase II involves inaccessible conduits.

The operability determination will remain in effect until the completion of the Phase I activities. Successful resolution of Phase I will provide further compelling evidence on the adequacy of SQN cable and render Phase II a confirmatory effort. TVA intends to keep NRC fully informed of the Phase I activities and will submit a Phase I report within 30 days of completion of the Phase I efforts. Further details on reporting will be included in the program plan submittal.

The commitment made in this letter is included as enclosure 2.

Please direct questions concerning this issue to Marcia A. Cooper at (615) 843-6422.

Very truly yours.

TENNESSEE VALLEY AUTHORITY '

y E. G. kM lace. Manager Nuclear Licensing and Regulatory Affairs Enclosures cc: See page 3 l

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U.S. Nuclear Regulatory Commission .

I cc (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. Donohew Project Manager U.S. Nuclear Regulatory Commission One k*hite Flint, North 11555 Rockville Pike Rockville, Maryland 20852 NBC Resident Inspector Seouoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy Tennessee 37379 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission ReBion II 101 Marietta Street, NW, Suite 2900 '

Atlanta, Jeorgia 30323 l

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, ENCLOSURE 1 SEQUOYAH NUCLEAR PLANT (SQN)

CONDITION ADVERSE TO QUA?.ITY REPORT (CAQR) SQP900305 R0 OPERABILITY DETERMINATIOC Discussion Deficiencies were identified with the application of the criteria used in ranking conduits that were tested to address pullby concerns during restart at SQN. These' problems were documented in CAQR SQP900305 RO. 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 employee concerns related 'o cable insta* ' rtion. SQN did not have any substantiated cable installation employee co wtec. The WBN concerns were investigated at SQN because.at the time theis were the questions whether the configurations and the cable pulling methods for both plants were similar. Subsequently, SQN conducted extensive reviews a the cable raceway systems and the attributes that contribute to the pc sibility that cable damage during installation could occur. These prerestart reviews, involving cable pull data retrieval and condait 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 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. No programmatic problems related to cable installation practices have been identified at SQN during the extensive cable work associated with all the restart efforts and recent refueling outages.

As a prelude to the SQN efforts 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 from 1973 to 1979, they did not find that the conduit configurations differed significantly from other nuclear plants of SQN's vintage. Recent comparisons of conduit configurations have shown that SQN's installations more closely resemble those at Browns Ferry Nuclear Plant (BFN). The short runs with many pull points translate into " easy pulls." This conduit information is also supported by the comparison of the current SQN-calculated sidewall bearing pressure (SWBP) values to the BFN values for their conduits selected for testing. The SQN conduits evaluated represent some.of the most severe SQN configurations, as identified by either criteria 5 of the SQN CTP or th.e BFN screening criteria method. As such, TVA has a high confidence that the SWBP values for the conduits and cables successfully tested at BFN fully bound the current SWBP values for SQN.

These reviews and evaluations lead to the conclusion that SQN conduit configurations are not the same as WBN and SQN does not exhibit the same programmatic problems that have been discovered and documented at WBN.

The problems identified at WBN are in the areas of conduit configuration (long runs with excessive bends between pull points) and cable pulling l

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practices (nylon parachute cords). The conduit configurations depart from the requirements of the TVA General Construction Specifications and industry good practices.- The SQN CTP Conduit Selection Criterion 5 focuses on the conduits that exceed the TVA General Construction Specifications definition of an easy pull for lengths of conduits and number of bends between pull points. A review of field sketches for over 350 safety-related conduits that contain at least seven cables and have at least two pullbys reveal that only a small number (14) of that population exceed TVA's definition of an easy-pull. In addition, seven of those conduits were direct current (de) high-voltage tested. Since the major factors in SWBP calculation are the lengths of conduit and the degrees of bends between pull points. TVA concludes that SQN has a smaller probability of having conduits with excessive SWBP than WBN. Also, no evidence exists that nylon parachute cords were utilized at SQN.

While SQN has.not fully resolved the issue of conduit overfill, a review of 181 conduits evaluated at SQN using the BFN screening methodology revealed only one conduit that was overfilled (40 percent allowable, 42 percent calculated). In contrast the WBN pullby corrective action plan included direct consideration for overfill in the screening process because of problems identified there with overfill.- The industry has only recently recognized the significance of conduit fill as a risk factor when performing pullbys. Lower fills increase the potential for obtaining a '

clear path during the pullby operation. The raceway fill at SQN ensures ',

that fewer pullbys occurred, and that those that did would be small and with less potential for pullby damage. .

Because of these f acts, 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 cable pulling practices.

2. Probability of Damage Discovery at SQN Even the.. .

4 sas no evidence of damaged cables at SQN, a population of condult. cd cables was identified to conduct high-voltage tests for the purr se o. detecting damage caused by pullbys, jamming, and silicone rubber .vileted ve- ical cables supported by conduit bodies near the top of the c. mit r vr'900 conductors were successfully tested at vol tage ; -de --- ,.8 kilovolt (kV) to 10.8 kV dc. -The three i vet-tes- 'o ,

' tits remain in the population with a higher potents -4 /1, Ty . mage. It is also important to note that the test anomal, t . 1,

• ic .can Insulated Wire Company (AIW) silicone-rubber cabic ( * "= + ,t dis ernable to the naked eye) was detected with a dry high-potentie. t -s t . This fact also highlights the importance of material susceptibilitic.. The SQN OTP represents the most comprehensive in-situ test prograT. ever undertaker in the industry.

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SQN's CTP selection criteria was biased toward material damage 3 susceptibility. However, even though discrepancies have been discovered '

in the unissued calculation to document the application of the selection criteria, TVA has confirmed that seven of the original 15 tested pullby conduits remain in the worst-case or higher-risk category. The remaining eight conduits could, therefore, be cor.sidered 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 would likely have been found. In addition, the AIW silicone rubber cables inside containment were replaced at SQN and the PN-type cable was not used tt JNN in 10 CFR 50.49 applications.

Fif ty-fdve and condid ts were also evaluated for SWBP. Fifteen were the tested craduit! from the material susceptible population and 40 were the higke<#. r3Hhtd by the BFN screening criteria from the remainder of the populatiot. with seven or m;43 cables. Overall, these conduits represent some of the " worst-case" -f rom a c0nf f guration (and force) perspective.

The SWBPs were bounded by the BFN wet-tested conduits. Therefore, it is reasonable to conclude that the forces developed in thste conduits are not great enough to cause cable damage. It is also reasonabb to conclude that these tests bound all SQN conduits because of.the similarity between the SQN and BFN conduit configurations, the' comparable sample of SWBP calculations performed for SQN, and the other favorable conduit attributes p,reviously described. Based on the similarities in the conduit c nfigurations between the twn plants, it is expected that the SQN calculated SWBP values for the future conduit calculations will remain bounded by the BFN results. '

i In January 1989, SQN 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 l have been identified as incapable of petforming their safety-related l' function by this-program. Additionally, many maintenance and modification i activities and Quality Control inspections have been performed since the L

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 aber; the SQN conduit configurations, and results of both the SQN and BFN CTfs 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.

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The first type is the randem failure. For the purposes of this l 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 effects of a faulted cable inside containment during a loss of coolant accident on containment integrity are mitigated by the diverse and redundant penetration overcurrent protection design (fuse and breaker combination). . The ef fects on emergency safeguards actuai. ion 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 sensing containment pressure and pressurizer pressure).

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

For the cables inside containment, there are several factors that support the adequacy of the installed safety-related cables. Because the containment eq !pment 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. In particular, of the top ranked conduits from the SQN SWBP screening activities, 2 conduits were inside containment, 10 were in the secondary containment (annulus) area, and 30 were in the control and auxiliary buildings.

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 failure from 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, 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 common mode failure from undetected cable damage is unlikely.

In the power, control, and signal cable e.stribution areas of the AB, as well as the CB, where a large . number of pullbys occur, the environment is considered mild and is therefore not impacted by adverse effects of an accident that would create a potential common mode failure mechanism from undetected cable damage.

Conclusion The probability of cable damage during installation is low. Substantial evidence from a variety of sources establishes that the SQN conduits are typical of its vintage of nuclear plant and that there are no programmatic cable installation problems. '

The probability that significant cable damage would have been identified is high. The SQN CTP results provide a high degree of conf 2dence that cable damage in material susceptible cable would have been detected. The BFN CTP 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 nature of the SQN conduit configurations 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. Common mode failures from undetected cable damage are highly unlikely. The most severe environments (inside containment) that might trigger the common 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 that are strictly mild environments and unlikely to initiate common mode failures. In '

addition, the separation and protection features incorporated for other programs (e.g., fire protection, moderate energy line break flooding, and high energy like break protection) provide additional protection from environmental effects. These features further lessen the likelihood of common mode failure.

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

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ENCLOSURE 2 TVA will17, August provide 19f0. a complete program plan description and schedule by i

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ENCLOSURE 6 OFFICIAL TRANSCRIPT OF PROCEEDINGS MEETING ON SEQUOYAH NUCLEAR PLANT CABLE TESTING PROGRAM i l'

Available to the public at the Commission's Public Document Room, Gelman Building, '2120 L Street, N.W. ,

Washington, D.C., and at the Chattanooga-Hamilton County Bicentennial Library, 2001 Broad Street, Chattanooga, Tennessee 37402, or may be purchased from Ann Riley &

Associates, Ltd., Suite 300, 1612 K Street, N.W.,

Washington D.C. (202-293-3950).

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