ML20215N323

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Forwards Interim Response to Recipient Re Cable Pulling Questions.Itemized Responses for 12 of 16 Questions Encl.Final Responses for Questions 2-5 Pending on Completion of Addl Evaluations.Employee Concerns Also Encl
ML20215N323
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 10/31/1986
From: Gridley R
TENNESSEE VALLEY AUTHORITY
To: Youngblood B
Office of Nuclear Reactor Regulation
Shared Package
ML20215N324 List:
References
NUDOCS 8611050239
Download: ML20215N323 (15)
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TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 37401 SN 1578 Lookout Place OCT 31988

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Director of Nuclear Reactor Regulation Attn: Mr. B. J. Youngblood, Project Director.

PWR Project Directorate No. 4 Division of Pressurized Water Reactors

.4 (PWR) Licensing-A U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Youngblood:

In the Matter of the ) Docket Nos. 50-327

' Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT (SQN) - CABLE PULLING QUESTIONS Enclosed is TVA's interim response to your-letter to S. A. White dated August 29, 1986. Enclosure 1 contains TVA's final answers to 12 of your 16 questions. As indicated in enclosure 1, TVA's final response to questions 2 through 5 is pending completion of some additional engineering evaluations.

Als'o as requested in your letter, enclosure 2 is a list of related SQN

-employee concerns. As you will note, there are a number of concerns which question the adequacy of the cable pulling program. These concerns are being evaluated by the TVA Employee Concerns Special Program (ECSP). If concern evaluations identify problems with either the specified recuirements or the implementation of these requirements, corrective actions may be required which affect the program requirements as idertified in the enclosed response. The ECSP reports will be provided to you for your information when completed.

Please note that the ECSP findings on many of thae issues have been transmitted to NRC in a September 17, 1986 letter.from J. A. Mcdonald,-TVA, to H. R. Denton, NRC.

As a result of the preliminary safety concerns expressed by your reviewers on 4 September 24, 1986 at SQN, enclosure 3 is a memorandum dated 0ctober 14, 1986 from TVA's Chief Electrical Engineer. This memorandum should resolve these concerns.

Allof'kheenclosedinformationshouldprovidean-adequatebasisfor resolution of many of your concerns. We hope this interim response allows you to complete most of the related SER in a timely manner. We will provide-complete responses to the outstanding questions as soon as possible.

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8611050239 861031 PDR ADOCK 05000327 .h(>

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An Equal opportunity Employer

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Director of Nuclear Reactor Regulation ChDT 31Ings Your staff has been kept informed of the status of-this response. If you have any questions regarding this matter,-please get in touch with M. K. Brandon at (615).751-8076.

Very truly yours, TENNESSEE V LEY AUTHORITY

. rid ey Manager Nuclear Safe y & Licensing Enclosures cc (Enclosures):

U.S. Nuclear Regulatory Commission.

Region II Attn: Dr. J. Nelson Grace, Regional Administrator 101 Marietta Street, NW, Suite 2900

-Atlanta, Georgia 30323 i

Mr. Gary Zech, Director TVA Projects U.S.: Nuclear Regulatory Commir, ion Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. Carl Stable Sequoyah Project Manager U.S. Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, Maryland 20814 1

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ITEM l Provide the procedure number and title of the procedure used by the electricians that governs cable pulling at Sequoyah Nuclear Plant (SQN). .(If this procedure has not been provided to. NRC,. provide a copy of all pertinent revisions.)

RESPONSE

General Construction Specification No. G-3, " Installing Electrical Conduit Systems and Fabricated Conduit Boxes," and General Construction Specification No. G-4,_" Installing Insulated Cables Rated Up to 15,000 Volts Inclusive," and Construction Specification N2E-860 " Installing Electrical Conduit Systems and Conduit Boxes," governed cable pulling at SQN during the early phases of construction. General Construction Specifications No. G-38 and G-40 entitled,

" Installing Cables Rated Up To 15,000 Volts" and " Installing Electrical Conduit Systems and Conduit Boxes," respectively, are the procedures which governed the cable pulling at SQN during the remaining construction phase.

G-3 was superseded by'N2E-860 on November 6, 1973 which in turn was later superseded by G-40 on August 6, 1975 and.G-4 was superseded by G-38 on July 25,1973. . All revisions of these procedures with the exception of revisions 0 and 1 of G-38 and N2E-860 have been previously-provided. This action is documented in R. L. Gridley's July 25, 1986 letter to B. J.

Youngblood. Revisions 0 and 1 of G-38 and N2E-860 are attached.

Post construction cable pulling modifications are governed by Modification and Addition Instructions (H&AI). The relevant M&AIs'at SQN are M&AI-04,

" Control, Power, and Signal Cables;" M&AI-06, " Installation of Conduit and -

Junction Boxes;" and M&AI-07, " Cable Terminations, Splicing, and Repairing of Damaged Cables." M&AI-04 has been previously provided as documented in the referenced July 25, 1986 letter. All revisions of M&AI-06 and -07 are attached.

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XTEM 2~

Have.the worst-case conduits for tough cable pulls been determined for SQN?

If so, supply isometric drawings., pull cards, and work orders for the worst-case pulls (i.e., those which exceed tension or sidewall bearing pressure limits) and for the.next worst-case conduits. Conduits in harsh and mild areas should be included in the determination of worst case.

RESPONSE' A preliminary set of 16 worst-case conduits had been selected. The selection of these 16 worst-case conduits was made by a designer who had been involved with the design of most of the conduits in the Auxiliary Building. His selection was made from conduit and grounding drawings using his judgment as to which conduits he suspected to be worst-case based on number of bends, long runs, changes in elevation, etc.

Isometrics and sidewall ~ bearing pressure calculations for these 16 have been informally provided to your reviewers for purposes of discussion only.

Because of some concerns about the assumptions used in the preliminary selection, evaluation, and calculations regarding the worst-case conduits, TVA has opted to broaden the scope of its worst-case determination at SQN. The evaluation at SQN will be in accordance with the guidance provided by TVA's Chief Electrical Engineer in his June 23, 1986 memorandum (attached). TVA's revised evaluation will consider these original 16 conduits as well as additional potential worst-case conduits. The final worst-case conduits will be selected from this larger group. -

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ITEM 4 For each conduit deemsd to be worst-case or next to worst-case, provide the calculated pull tensions and sidewall bearing pressure for each pull directicn.

RESPONSE

The calculated pull tensions and sidewall bearing pressure for each pull direction will be provided for the cables in the worst-case conduits in our final response.

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ITEM 5 Describe, in detail, the criteria and process of elimination used in determining the worst-case conduits with regard to cable pulling. Include such information as the lengths of conduit considered too short to be of concern, the assumptions used in scoping the worst-case conditions, and the methods used-to determine the worst-case conduits.

RESPONSE

This information will'be provided in our. final response.

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XTEM 6-Discuss the extent to.which the following were considered in determination of

-the worst-case cable pulling situa,tions:

A. Pull-by in which new cable was pulled past cable already in a conduit.

B. Differences in cable construction, jacket materials, and diameters when one type of cable was pulled by another in a conduit C. Differences in cable construction, jacket materials, and diameters when mixes of cable types were included in a multiple pull.

D. For 3 and 4 cable pulls, were jam ratios evaluated for determining worst-case pulls?

RESPONSE

The criteria listed in items "a" through "d" were not considered in the determination of the worst-case conduits.

The concern of cable " pull-bys" was considered on a generic basis by TVA when preparing its sidewall pressure evaluation program. As it is normal practice to route only one circuit in power-level conduits, pull-bys occur generally in instrumentation and control level conduits only. Typical conductor sizes routed in such conduits are No. 8 - No. 16 AWG. The results of TVA's cable sidewall bearing pressure tests indicate that for such conductor sizes, the limiting parameter for installation is not sidewall pressure but rather conductor strength. Additional information concerning cable pull-bys is provided as enclosure 3 to the letter transmitting this report to NRC.. -

An NRC review team conducted an interview on September 23, 1986 with TVA construction employees knowledgable of cable pulling practices at SQN. As indicated then, the construction' employees knew their business well, good construction practices were used, appropriately sized manila break ropes were provided and used on known tough pulls, c vie amounts of cable lubricant were used, and_the work was done in the presen..e af quality control (QC) inspectors. Work was stopped if a problem developed during a pull and a construction engineer was called to evaluate the situation before continuing.

The above practices were followed to avoid cable damage during pulls. ,

The relationship of jam radio to sizing of conduit is explained by an excerpt -

from Installation Practices for Cable Raceway Systems, the Okonite Company, 1982, which states: " Jam Ratio is defined for three single conductors of equal diameter as the ratio of the conduit ID to the single conductor cable OD. The reason for concern with the jam ratio is that damage could occur to one or more of the conductors due to their jamming in the pipe. Jamming cannot occur when D/d > 3.0 and normally does not occur when D/d < 2.8."

Neither TVA nor do others in the industry, normally calculate the jam ratio as part of the design process.

Again as the NRC review team heard from the electricians at SQN. it was normal construction practice that should the cable jam during cable pulling, either due to the jam ratio or some other factor, cable pulling for that pull would stop and be investigated before continuing.

ITEM 7 Describe the types of lubricants used, and the method of application during cable pulling. To the extent possible, describe the periods during plant construction in which different types of lubricants were used and the types of cable with which they are used.

RESPONSE

The different types of lubricants used and the procedures which approved them for use at SON during construction are General Construction Specification Nos. G-4 and G-38.

General Construction Specification No. G-4 was in force from the beginning of-construction at SQN until July 25, 1973. No. G-4 contains the following

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requirements regarding cable lubricants.

1. Lubricants for pulling cable having an outer covering consisting of a rubber-like jacket are recommended as follows: (1) dust with mica or soapstone,-(2) water, (3) Wire Lube or Yellow 77 (Ideal Products Company), (4) talc, (5) soapstone and water, and (6) soap and water.

Soap should be_a low-alkali-type such as Ivory soap flakes. Under no circumstances shall soap be used when installing cable in aluminum condult.

2. . Lubricants for pulling cable having asbestos-braid covering are recommended as follows: (1) soapstone, (2) talc, and (3) soapstone-and-water thick paste--use very little water &nd smear -

the paste lightly on the cable.

General Construction Specification No. G-38 was and is in force from July 25, 1973 to the present. The first two versions of No. G-38 had the same list of approved cable lubricates. Revision 2, dated August 3, 1978, added Bishop No.

45 Cable Pulling Lubricant and Y-er Eas. Revision 3, dated September 27, 1982, deleted Wire Lube or Yellow 77 and added Polywater Lubricants "A" and "G" and Slip-X 300 to the list of approved cable lubricants. Revision 4, dated March 25,.1984, added a clause which allows use of other lubricants not on the list provided that they are approved by the cable vendor. Revision 5, dated February 13, 1985, added Polywater "J" and revision 6, dated September 15, 1985, added CRC wire-pulling lubricant with teflon as an - '

acceptable cable lubricant.

The following information was obtained from a TVA employee who was a QC inspector at SQN during the period from July 26, 1977 to May 20, 1985. It is believed to be reliab'le information which accurately depicts the use and method of application of cable lubricants during the construction of SQN.

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This inspector was certified in the use of SQN Cable. Pulling Inspection Instruction (II-28) in November.1977. He trained for one week (40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br />) with other inspectors in the field watching cable pulls and went through a classroom training course on inspecting cable pulls before taking and passing a written certification exam. Frcm November 1977 to May 1985, he averaged approximately one cable pull inspection per day. He witnessed a myriad of cable pulls at SQN during construction including all insulation types, voltage levels, control, power,-signal, single conductors, multiconductors, and

- nuclear instrumentation system cables. Locations of the cable pulls which he inspected include the ERCH pumping station, diesel generator buildings, auxiliary building, control building, turbine building, and both reactor buildings. . His observation, based on the inspections, is that the majority of the time only two types of lubricants were used. On rubber- and plastic-type (CPJJ etc.) insulated cables, Yellow 77 was used. On asbestos-braid-type (SROAJ) i nsulated cables, Ivory Flakes or ground soapstone was.used. After September-27, 1982, when Revision 3 of G-38 became effective, Polywater G replaced Yellow 77 in general use.at SQN. The method of application of lubricants, in most cases, was specified by the manufacturer and, in general.

- applied very liberally by. hand to the cable jacket, swabbed in.the conduit before, and/or dumped into the conduit during pulling.

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ITEM 8 Is there a record indicating that lubricants were used during cable pulls?

RESPONSE ..

The records do not specifically-indicate where lubricants were used.

Reasonable assurance that adequate amounts of lubricants were used was obtained during interviews conducted by the NRC review team on September 23, 1986 with TVA Construction personnel knowledgable of cable pulling practices at SQN. This same information is reiterated in TVA's response to Item 7.

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. ITEM 9 With regard ~to bending of cable beyono the minimum allowable bend radli:

A. Describe efforts presently underway to resolve the issue.

B. Describe any inspections that have been performed on cable with bend radil

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problems to determine if areas adjacent to the bend's are subject to stress or deformation that could increase with age.

RESPONSE

A. During the period of February 28 through April 15, 1985, TVA's Nuclear Safety Review Staff (NSRS) conducted an investigation on Watts Bar Nuclear Plant (HBN) in regard to the adequacy of cable installation and inspection. A major thrust of this inquiry was the establishment of and adherence to cable bend radius criteria.

The NSRS report (I85-06-WBN) of this-investigation, which details a comprehensive review of the cable bend radius issue from 1979 through 1985, identifies various areaslof potential inadequacies. The findings of

~this report have been reviewed for applicability to SQN. TVA's Electrical Engineering Branch (EE8) has used this report, in addition to the manufacturers' requirements, to form the basis for-its evaluation. Each of the areas of potential concern is being resolved into elements for further analysis. In each case, the actual bend radius to which a cable has or could have been subjected is determined. This is accomplished for each Class IE safety-related caule to which the concern applies.

Subsequently, a determination is made of the effects, both short- and -

long-term, on the integrity of the cable and its ability to perform its safety-related function as a result of being subjected to the reduced bend radius. This determination is based on consultations with and recommendations from the cable manufacturers, a review of the cable materials and constructions involved, the particular application of the cable at TVA, and a review of TVA and industry environmental qualification testing as it relates to cable bend radius. In particular, EEB has identified the elongation stress, to which a cable is subjected as the result of a bend, as the critical parameter in determining acceptability.

The evaluation of the concerns indicates that the minimum bend to which cables could have been subjected is that of one times.Its overall' diameter. The resulting elongation stress has been calculated and * '

compared with the cable's corresponding capability following its postulated accident scenario. This information is compiled from the environmental qualification test reports. Preliminary conclusions of the study indicate that this worst-case bend does not reduce the cable's available elongat' ion properties below that required for it to perform its safety related function.

The effects of a potential bend on shielded cables is being evaluated separately. Accordingly, an inspection program is being established per items 2 and 3 of the memorandum dated September 2, 1986 from the TVA Chief Electrical Engineer (attached). Finally, recommendations will be l formulated which, if necessary, may include cable testing, surveillance inspections or rework, or replacement of the cable in question.

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A final report providing comprehensive detailed analyses of each concern, including evaluation results, conclusions and recommendations will be

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issued in the near future.

8. As stated in the response'to 1 tem A above, TVA is presently determining any areas which may be of concern with respect to the performance of the cable. TVA is performing a' limited number of individual, specific inspections on installed shielded class lE cables for conformance to manfucaturer's requirements.

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ITEM 11 Are the cables that could have been abused during pulling located in harsh

. environment areas 1such that they may be subjected to such conditions as high moisture, flooding, steam,' or high temperature conditions during normal or accident periods?

RESPONSE

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Only conduits wnich contain 10 CFR 50.49 cables are being considered in SQN's effort determining the worst-case conduits. Therefore, it is likely that at-least portions of these conduits are routed through harsh environment areas.

In accordance with 10 CFR 50.49 criteria, some of the above conditions could exist in these areas. It should be noted that in addition to the conservative design guidance and good installation practices at SQN, Class lE pulls were witnessed by the QC inspectors in accordance with the controllir.g procedure'.

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ITEM 12 What in-situ testing has been done to the cables on a routine basis or subsequent to the generation of the ccacerns related to cable abuse?

RESPONSE

After a cable is pulled, a continuity check is performed as part of the termination process. Megger and high potential testing is conducted on medium voltage (6900V) n.otor circuits, and megger testing is conducted on 100HP and greater low voltage (480V) motor circuits. As specified in Maintenance

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Instruction.(MI) 10.20 (attached), periodic testing is performed for medium voltage motor circuits and 100HP and greater low voltage motor circuits.

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