ML18032A714

Rev O to Cable Ampacity Program Plan,Browns Ferry Nuclear Plant. Related Documentation Encl

ML18032A714
Person / Time
Site:	Browns Ferry
Issue date:	01/13/1988
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML18032A713	List: ML18032A712 ML18032A714
References
PROC-880113, NUDOCS 8801290184
Download: ML18032A714 (17)

Text

CABLE AYPACITY PROGRAM PLAN BRQ'JNS FERRY NUCLEAR PLANT REVISION 0 Ijr'/rg prepare Approved by:

ineer ite Director ra IE Assista to the Dir tr of Nucl ar Engineering r cF b'g Director Division of Nuclear Engineering 880i290l84 880125 tT PDR ADOCK 05000259 P- PDRJ ID 93/EL167

AMPACITY EVALUATION PROGRAM PLAN AMPACITY EVALUATION PROGRAM PLAN TABLE OF CONZENTS

1.0 INTRODUCTION

2.0 OB JECTIVE 3.0 SCOPE

4.0 DESCRIPTION

OF PROGRAM 4.1 IDENTIFY CABLES REQUIRING EVALUATION 4 o2 IMPLEMENTATION OF SAMPLIFG PLAN 4.3 VERIFICATION OF CABLE INSTALLED CONFIGURATION 4.4 EVALUATE CABLES AND CONDUCT 100't REVIEW IN AREAS OF COMMON CAUSE DEFICIENCIES 4.5 PERFORMANCE OF CALCULATIONS 4 ~6 DETERMINATION OF EXPENDED AND REMAINItG LIFE 4.7 CABLE REPLACEMENT 4.8 CABLE INSTALLATION RESTRICTIONS 4.9 TEST PROGRAMS 4.10 PROGRAM INTERFACES 5.0 PROGRAM IMPLEMENTATION 6.0 PROGRAM DOCUMENTATION

7.0 CONCLUSION

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AMPACITY EVALUATION PROGRAM PLAN 1.0 IÃZRODUCTION An INPO finding on.Bellefonte Nuclear Plant concerning the lack of design calculations to show the adequacy of cable ampacities resulted in a Problem Identification Report (pIR) GENEEB8605 to all TVA nuclear plants. As a result, it was determined that TVA design standards DS-E12.1 .1 through DS-E12.1.4 were

'ncomplete and did not properly account for the effects of cable environment and cable installation configuration on cable ampacity. Since these standards were used for the initial design of cable installations at Browns Ferry Nuclear (BFN), the potential exists for undersizing of safety related cable in BFN. A new electrical design standard (DS-E12.6.3) based on various industry standards and test reports was subsequently developed which applies to cables installed in BFN. A program to determine the extent of nonconformance to the current standard, which meet or exceeds the Sequoyah Nuclear Plant'(SQN) ampacity program (See Attachment 1), has been developed and is being implemented at BFN.

2.0 OB JECTIVE The objective is to fully substantiate a remaining two (2) year (next scheduled outage) or more continued operation of all auxiliary and control power safety related cables after equating any lack of previous cable sizing conservatism with a loss of operating life. Cables not having a remainirg life of two (2) years operation after restart will be replaced prior to Unit 2 restart. Those cables with a remaining operatirg life exceeding two=(2) years will be scheduled for replacement prior to expending their determined remaining life.

3.0 SCOPE The scope is to verify the adequacy of safety related auxiliary and control power cables in voltage levels V3, V4, and V5, (as defined by DS-E12.6.3) designed prior to the issuance of DS-E12.6.3 RO. The evaluation shall be accomplished by applying sir@le or multi-sampling plan based upon the Nuclear Construction Issues Group (NCIG) sampling plan which has been accepted for, visual reinspection of welds.

4.0 DESCRIPTION

OF PROGRAM The program plan is to 1) identify cables requiring evaluation 2) implement a sampling plan 3) verify installed cable configuration 4) evaluate cables and conduct 100% review in areas of common cause deficiencies 5) perform calculations 6) determine cable life expended and remaining operating life 7) schedule cable replacements based on cable remaining life, 8) impose cable installation restrictions 9) implement test programs and, 10) implement program interfaces.

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III 4.1 IDENTIFY CABLES REQUIRI& EVALUATION Cables requiring evaluation are voltage level V3, V4, and V5 safety related cables and non-safety related cables routed with safety related cables. All safety related cables will be identified by the BFN Q-List which is considered to be the minimum set of structure, systems, and components necessary to prevent or mitigate the consequences of Final Safety Analysis Report (FSAR),

Chapter 14, design basis events and to safely shut down the plant following such events. Environmentally qualified cables w'll be identified by the BFN 10CFR50.49 list.

4.2 IMPLEMENTATION OF SAMPLING PLAN A NCIG sampling plan using inspection lots similar to +N's nine (9) inspection lots for the V3, V4, and V5 cables will be implemented at BFN. Sample size and allowable discrepant items will be for a 95% confidence and a 95% reliability level. For purposes of determining whether a 100% review of the inspection lot is required, a discrepant item (or failure) is considered to be a cable whose 40 year design life allowable ampacity (which takes into consideration the derating effects of tray covers and/or bottoms, flame retardant coatings, Appendix R fire wraps, and ambient) is less than the required actual load with margin to account for reduced voltage, service factor, etc..

4.3 VERIFICATION OF CABLE INPZALLED CONFIGURATION For determining ampacity for cables which are being evaluated in the sampling program, cable routes through raceway and the cable limiting temperature factors must be known. Route and installation conf'guration of safety related cable, i.e., conduit and tray fill, cable tray covers and bottoms, thickness of flame retardant coatings, fire wrap, fire stops, pressure seals, and environment (mild or harsh), will be determined from the BFN As-Constructed Cable and Conduit Schedule drawings (CCS) and field walkdowns. As trays are walked-down, information identifying conduits entering and leaving trays along with any cables which leave tray via air is compared against the CCS to confirm the CCS accuracy. If no discrepancy is found the cable route given in the schedule is considered to be correct and verified by review. If there is a discrepancy between the cable schedule and the walkdown data further investigation is conducted to resolve the discrepancy. In most of those instances signal tracing of cables will be required to determine the cable route. Drawing discrepancies will be initiated to document and update the cable schedule.

4,4 EVALUATE CABLES AND CONDUCT 100% REVIEV IN AREAS OF COMMON CAUSE DEFICIENCIES Based upon SQN's results, it is anticipated that upon completion of the sampling program at BFN there will be no failures in V3 voltage level cables in tray or conduit and minimum failures in V4 and V5 voltage level cables in conduit. However, common cause deficiencies are expected in V4 and V5 tray inspection lots of the sampling program which would therefore require 100%

review of cables in V4 and VS tray. Hence, 100% walkdown and cable evaluation will be performed of the cables in these inspection lots. It is anticipated that failures may exist for 10CFR50.49 cables in V4 and V5 conduit which may also require 100% review.

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4 ~5 PERFORMANCE OF CALCULATIONS Cables will be evaluated by calculations progressively performed in three phases designated as Phase I, Phase II and Phase III as follows:

Phase I evaluates cables conservatively using design standard DS-E12.6.3 Rev 1.

Phase II takes a closer look at the conservative design criteria given in DS-E12 load

.6.3 and permits higher cable ampacity when actual cable depth of current and load multipliers are considered. Phase II fill, also determines operating temperature of the cable.

Phase III includes a more detailed review of the equipment loads for those cables which may not pass Phase I and Phase II. Operating modes of the cable load cycling (e.g. normal, shutdown and test modes) and load cycling (e.g.

loads 'sharing a raceway) are considered.

4.6 DETERMINATION OF EXPENDED AND REMAINING LIFE Cables which are identified as not having a 40 year design life based upon actual load current and cable installation configuration will be further analyzed to determine their expended and remainirg life. In this analysis, the duration time of each cable's maximum operating temperature (both in its loaded and non-loaded state) is determined based upon the installed configuration, its duty cycle loading (i.e. intermittent or continuous) and the duty cycle of cables surrounding it (i.e. if in tray, tray diversity loading). Determination of operating temperature will include the effects of tray cover removal, reduction of conservative load type multiplier, and use of actual running load in lieu of equipment rating. Once the operating temperature and duration time is known, cable expected life can be determined by utilizing the Arrhenuis methodology commonly applied in calculating life values for cable insulation materials encountered throughout the nuclear industry. This methodology features the use of empirical test data to form the basis for each cable life prediction. For example, a cable that has an expected life of 40 years when operating at rated temperature of 90 degrees centigrade will have an expected life, depending on the insulation type and physical characteristics, of approximately 20 years when operating at 100 degree centigrade. However, for environmentally qualified (EQ) cable, verification that operation at a higher temperature does not void the qualification, is required, and will be performed.

4.7 CABLE REPLACEMENT Those cables that do not have two (2) years remaining operating life after restart will be replaced prior to the restart of BFN Unit 2. For those cables having greater than two (2) years remaining operating life, a schedule will be developed for replacement as required. Cable replacement will be in accordance with BFN design criteria BFN-50-758 "Power, Control, and Signal Cables for use in Class I Structures".

4.8 CABLE INSTALLATION RES'IRICTIONS TVA will assure the cable installation configuration used in the cable evaluations are not altered by additional cables, tray covers, flamemastic, fire wrap etc without assessing the impact to cables.

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4.9 TEST PROGRAMS To provide additional information for the ampacity analysis, Flamemastic (cable fire retardant coating) derating test and tests to increase the presently reduced temperature ratings of 10CFR 50.49 cable are planned. These results may better define ampacity deration conservatism when used in determining allowable ampacity for cable.

4.10 PROGRAM IHZERFACES Coordination with other BFN design review programs such as voltage drop analysis, cable short circuit and coordination analysis, Appendix R analysis and Environmental Qualification (EQ) program .and any other program which may be dependent on cable temperature, will be performed to assure those analyses are not invalidated.

5.0 PROGRAM IMPLEMENTATION:

TVA Division of Nuclear Engineering (DNE) will perform the ampacity evaluation of cables and will provide Design Modification Changes for replacement cables.

Evaluation, design and modification will be performed in accordance with TVA procedures and practices. Key TVA personnel including DNE cable specialist/designee involved in the +N ampacity calculation evaluation will assure consistency between the BFN ard SQN programs. For this effort, DNE cable specialist designee is Bryan Reagan.

6.0 PROGRAM DOCUMENTATION The sampling program for V3, V4, and V5 voltage level safety related cables will be performed by approved project. instructions and calculations.

Calculations will be performed and documented in accordance with TVA's Nuclear Engineering Procedure (NEP) 3.1. All walkdown data will be of a QA level that it may be used as input to calculations. Cables not sized in accordance with DS-E12.6.3 will be identified on Conditions Adverse to Quality Reports (CAQR).

Cables not having a remaining life of 2 years after restart will be replaced prior to restart. Those having an operating life greater than 2 years will be identified and scheduled for replacement as part of BFN maintenance program for Class lE equipment. All cables which are found acceptable for 2 years or more, but which are not sized in accordance with DS-E12 .6.3 will be identified on an exception request to design criteria BFN-50-758. Program completion will be documented by installation of replacement cables, approval of design criteria exception requests, and closure of existing BFN CAQR's regarding the ampacity issue. I The BFN Nuclear Performance Plan (NPP) and Final Safety Analysis Report (FSAR) will be revised to reflect the program described herein.

7.0 CONCLUSION

The BFN Ampacity Evaluation Program will implement an evaluation program similar to SQN. In addition to SQN, a conduit and cable schedule verification and 100% Flamemastic thickness walkdown verification program will be used to determine V4, and V5 voltage level allowable ampacity values of cable in tray.

Cable failure and replacement will be determined by cable remaining life.

Cables determined to have a remaining operating life of less than two (2) years after restart will be replaced prior to BFN Unit 2 restart.

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. AMPACITY EVALUA PROGRAM PI AN ATTAC&iENT 1

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.';"-,::-.Memorandum TENNESSEE VALLEYAUTHORITY B43 '86 100(~ 909 TO: 'r',";i:..

Those listed

, ',.-PROD  : M:. S. Raughley, Chief Electrical Engineer, M8 C126 C Ol! Re~sia

SUBJECT:

ALL NUCLEAR PLANTS -

86>>O3rO3Z9 CORRECTIVE ACTION AND SAPLING PROGRAM FOR ELECTRIC!lL

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CABLE klfPACITY tj This memorandum supersedes the September 8, 1986, memorandum from .-

M. S. Raughley to Those listed (B43 860909 902) in order to provide additional diroction for the handling of defective units, further define V3-level control povor cablos, and provide multiplying factors for trays and fire vrap materials.

Tho purpose of this memorandum is to provide direction on the performance of corroctivo action and the establishment of a sampling program to determine'he adoquacy of olectrical cables with respect to their ampacity rating. This is mandatod by deficiencies in Design Standards H12.1.3.'- E12.l.h vhich vere idontifiod in Problem Identification Report PIRGENEEB8605 These design standards havo boon suporseded and all inadequacies corrected by the recent issuance of DS-E12.6.3 "Ampacity Tables for Auxiliary and Control pover Cables (0 "15 e 000V) ~"

In addition to the actions specified heroin for confirming the adequacy of the

~ith respect to anpacity, each project's Equipment Qualification section must address the impact of the nev design standard on its efforts. This is-necessary if tho project has doratod the cable's qualified conduc or

- :in" temperature below its insulation tem"e. . ~tur= using such computer programs as "CABCALC" or "CACTAC." The affected parameters include tho specified allowable ampacity in conduit and tray, the derating effects of tray covors, and bottoms, and fire vrap, and the assumed conductor temperature when tho conductor is deenergized. Each project should discuss and coordinate its offorts in this area with tho cable specialist.

Prior to proceeding with implementation of the actions noted herein each pro5oct must confirm tho adequacy cf the ol)cuing:

1. The specific cable number and cable typo msrk number for all auxiliary and control power Class 1E qables, and non-Class lE cables routed with Class 1K cables must bo known. These must appear in DS-E12.6.3 with an ampacity rating for the installed raceway configuration.

2. Tho exact installed routing of the cables identified in item 1 must be knowa.

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'" 3. For V4- ind V5-level the percent fill 'I for the trays, and the number of conducto'rs in the conduits in vhich the cables identified in item 1 ercj":-!';-..

routed must be known. The effect of cables vhich ere.abandoned in..the." .'..'..

v<i raceway but are not indicated in present cable schedules must be accounted for.

4. The existence and location of cable coatings, cable tray covers and -'...:.=.

bottoms and Appendix R fire vraps must be known.

5 r In order'to demonstrate the adequacy of the auxiliary and control power cables l with respect to ampacity each project shall establish a sampling program. The

\ guidelines vill be developed and the sampling, performed in accordance with Nilitary Standard

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105D dated April 29, 1963.

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The sampling program developed by each project based on 9 inspection lots or batches. The inspection lots f'r each project are as follovs (refer to Design Standard E12.6.3 ior the definition of the various voltage levels):

1. V3 level cables routed in tray.

2. V3 level cables routed in conduit vithout hppondix R fire vrap.

3. V3 levol cables routed in conduit vith Appendix R fire wrap.

4. V4 level cables routed in tray vithout tray covers, bottoms or Appendix R fire vrap.

5. V4 level cables routed in trey vith tray covers and/or bottoms and/or Appendix R fire wrap.

6. VS lovel cables routed in tray without tray covers, bottoms or Appendix R fire vrap.

7. V5 level cables routed in tray with tray covers, and/or bottoms and/or Appendix L R fire wraps.

8. V4 and V5 level cables routed in conduit without Appendix R fire wrap.

9. V4 end V5 level cables routed in conduit with Appendix R fire wrap.

For each nf the inspection lots shown the project shall determine the total number of units (Class lE cables or non-Class lE cables routed with Class lE cables) in that lot. Each such cable should be counted only once end included in the inspection lot reflecting tho most limiting raceway configuration for ampacity in which it is routed.

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.'",aptly The order of raceway configurations by service level from most limiting to least..limiting are as follovs:

I. U3-level 1 ~ h. Inspection lot I B. Inspection lot 3 C. Inspection lot 2

2. V4-level A-. - Inspection lot 5 B. Inspection lot 9 C. Inspection lot 4 D. Inspection lot 8

3. V5-level

h. Inspection lot 7 B. Inspection lot 9 C. Inspection lot 8 D. Inspection lot 6 Therefore, as an example, cables routed in V4 or V5 level trays vith tray covers and/or bottoms and/or Appendix R fire -ap shall not bo counted spain in other inspoction lots even if they are additionally routed in such.

After the total number of units in each inspection lot is determined the sample size code letter shall be selected fr-m the Military Specification 105D Table I for General Inspection Leve) I . F"'wing selection of the code letter the rrample size is specified in Table IV-A. The accept'.able quality level is 4.0.

Having ostablirrhed the first sample size-the project shall randomly select cables from the inspection lot. Each cable shall have the allowable ampacity determined, conaidering, its actual installed configuration, in accordance with Design Standard E12.6,3. This ampacity vill be compared against tho actual load ampacity including appropriate multiplying factors to determine the acceptabil'ity of the installed cable vith respect to ampacity.

If tho initial sampling irrdicates an acceptable quality level within the respective inspection lot, no further samp)ina irr required. If the number of defective units in the initial sampling is above the specified allovable limit additional sample lots shall be selected and the adequacy of the cables determined. Refer to Section 10.1.2 of the Military Specification for sped ific direction. Thi's process shall corrtinue until an acceptable quality level is achieved in accordance with the Military'pecification or until

)ot is reg~.:od. All cables within a re5octod lot vill have to have their adequacy with rospect to ampacity determined individually.

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'ctober 7y 1986 I hLL NU EhR PLhNTS - CORRECTIVH'hCTION hND ShNPLING PROGRhN FOR ELECTRICAL ChBLE hCITY.

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'TSI Fire Mra Naterial Plant Descri tion/httachment BFN -'1-Hr Conduit <2" 0,91 BFN - l-Hr Conduit >2". 0.925..:. " ":""

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3-Hr Conduit <2" '.88 ':

MBN 3-Hr Conduit >2" ,0. 90 SQN Panels to Construct- 0.87 1-Hr trays (V4 only)

SQN Panels to Construct 0.79 3-Hr trays (V4 only) 3N Fire Mra lfaterial Plant Deecri tion'/httachment Multi lier lf-2Dh Conduit - 5 Layers of 0.625 Wrapping, MBN N-20h Cable Tray - 4 Layers of 0.40 Mrapping CS-195/N-20h Cable Tray Rigid Panels 0.41 Thf.s information vill also be substanti"te" ~ DrtE calculation to be issued by EEB Central Staff and vill be incorporated into the nert revision of Hlectrical Design Standard DS-E12.6.3.

Resolution of the concerns on cable ampacity has been tied to plant restart/fuel load. Implementation of the actions specified in this memorandum should be scheduled by each. project accordingly.

l M. S. Reuse y J. D. Collins, P-205 SB-Kf G~ T Hal 1 n DNE ~ DSC hn quoyah D. F. Faulkner, h7-BFN E. 0. Massey, 7-193 SB-K

. Qgg TNS:RB cc: RIES SL 26 C-K J. P. Staple ton, DNE, hl0 Brovns Ferry E. R. Hoesly, 9-113 SB-K D. M. Milson, DNE, DSC-E, Sequoyah R. M. Cantrell, M12 h8 C-K Kanti Gandhi, IOB-C102 MBN Principally Prepared By: T. N. Snea, Extens.on 2672 n

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An SCR must bo vritten to corer all defectire units nd the mode of failure for those units shall be explained and documented. A determination must be made as to the possible generic implications of any failure.. If the failure '..

can be shown to be duo to an isolatod cause, no further 'reviev in this regard .

is necessary. 'If the cause of failure could apply to a particular subset oi cables, further reviev, vhich may include additional sampling of'-the cables in that group is required to determine the extent of the problem. ~ 4

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i For the purposes of this sampling program, contxol pover cables are those cables routed in a V3-level racevay whose load current for the particular conductor size could pxoduce sufficient heat to varrant consideration. As V3-lovel cables axe, by definition, limited to less than 30 amperes this consideration is restricted to conductor size No. 8 JNG and smaller.

Therefore, a control pover cable is defined as a No. 8, 10, 12, or, lh AMG conductor installed in a V3 raceway with a load current greater than indi'cated belov except No. 10, 12, or 14 AUG conductors whose load current does not 1 i '

exceed 15 amps and vhose load operation does not exceed a total of 20 minutes i' in any 5-hour interval.

Cables vhich meet the exception or vhose load currents are belov those indicated do not varrant fuxther consideration of ampacity and ax'e nct considered control power cables. Those cables vhich exceed these limitations must have the specific allowable ampacity of the cable selected verified for ader,uacy for the load curient and installation configuration.

Conductor Size hMG is a control power cable, load current exceeds am eres if the lh 6 12 8 10 12 8 22 This ini~rmation will be substantiated by a DNE calculation to be issued by.

EEB Central Staff.

For the purposes of this sampling, prog,ram, the multiplying factors indicated below are applicable for the configurations listed:

Cable Tra s Onl Confi uration Nulti lier Sheet metal corer 0.75 Sheet metal bottom 0.8l Shoot metal top and bottom 0.60