ML20081M693

Interim Deficiency Rept,Items E-20 & E-29 Re Adequacy of Cable Tray & Conduit Support Welding & Cable Tray Support Threaded Nelson Studs.Initially Reported on 820503 & 0928. Concurrence Requested for Procedural Development

ML20081M693
Person / Time
Site:	Zimmer
Issue date:	11/08/1983
From:	Williams J CINCINNATI GAS & ELECTRIC CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, E-20, E-29, LOZ-83-0180, LOZ-83-180, LSO-83-180, NUDOCS 8311170340
Download: ML20081M693 (6)

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YHE CINCINNATI GAS & ELECTRIC COMPANY

[.~I .k CINCINNATI, OHIO 45201 November 8, 1983 LOZ-83-0180 J. WILLIAME Jfit stNton wCE Pass 40ENT NUCLEM OPtmAh0NS Docket No. 50-358 Mr. J.G. Keppler, Regional Administrator U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137

Dear Mr. Keppler:

RE: WM. H. ZIP 9tER NUCLEAR POWER STATION - UNIT 1 EVALUATION OF CABLE TRAY AND CONDUIT SUPPORT

~ WELDING ALONG WITH THE ADEQUACY OF THREADED NELSON STUDS USED ON CABLE TRAY SUPPORTS (10CFR50.55(e), ITEMS E-20 & E-29)

W.O.~57300, JOB E-5590,' FILE'#503 This letter submits an evaluation plan for your review and identifies rework for which CGEE intends to request relaxation of

-the NRC November 12, 1982 " Order to Show cause and Order.

Immediately suspending Construction" (CLI-82-33) in accordance with'Section IV.B(3). This letter also constitutes an interim report for the subject conditions which were initially reported to the Commission on May 3, 1982.(Item E-20) and September 28, 1982 (Item E-29) as potentially reportable deficiencies under the requirement,s of 10CFR50.55(e).

On August.11, 1983,.a meeting was held at the Wm. H. Zimmer site between the Nuclear Regulatory Commission (NRC) and The Cincinnati Gas & Electric Company (CGEE) . The NRC was represented by Messrs. L. Kintner, C. Scheibelhut, D. Keating, and W. Christianson. During this meeting, CG&E's program for evaluating cable tray and conduit support welding along with the adequacy of_ threaded Nelson Studs used on cable tray supports was presented. The proposed program is summarized below and activities for which' relaxation will be requested are identified.

Program details are provided in Attachment A to this letter.

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8311170340 831108 PDR ADOCK 05000358 hDV14 4

Mr. J.G. Keppler Regional Administrator November 8, 1983 LOZ-83-0180 Page 2 EVALUATION OF CABLE TRAY AND CONDUIT SUPPORT WELDING (E-20)

ALONG WITH THE ADEQUACY OF THREADED NELSON STUDS USED ON CABLE TRAY SUPPORTS (E-29) l The E-20 program addresses the concerns that hot-dip galvanizing or spray-on galvanox coating on welds may hinder reinspection efforts, and that the original inspection was not 100% complete. Sample destructive tests will be utilized i to obtain existing weld strength since removal of the hot dip galvanizing is difficult and may present additional problems.

The capacity of existing welds with minor weld diacontinuities shall be verified in order to minimize

rework. Except for the use of sampling, this program is in conformance with the design and construction requirements described in the FSAR. The results of this program will be used during the 100% reinspection of cable tray and conduit support for contiguration and location.

The E-29 sampling program addresses the concerns related to the adequacy of the threaded Nelson Studs, and provides an evaluation of base metal discontinuities caused by the removal of a stud used for temporary support of a locating template.

The program presented on August 11, 1983 for Nelson Studs and described in " Attachment A" differs from the commitments discussed in our previous interim report on Item E-29 (LOZ-83-0018). Those differences are as follows:

1. Sampling will be used to verify hanger foot connection adequacy instead of torque testing individual studs for each connection.

2. The size limitation was removed from the acceptance criteria for base metal discontinuities.

CG&E intends to request relaxation of the Show Cause Order in order to conduct the following safety related work associated with the proposed programs:

1. The Item E-20 progra:n requires disassembly of support hangers to provide destructive L -

Mr. J.G..KepplerL ~

Regional Administrator-November 8, 1983 LOZ-83-0180 Page 31 test samples. Reassembly with new hangers is also requested.

2. Item E-29 program requires the dismantling of cable tray supports-to evaluate base metal discontinuties.

We are planning to perform this evaluation and rework under the organization described in CGEE's Course of Action and in

.accordance with the approved procedures developed for use during the implementation of the Plan for the Verification of the Quality of Construction (PVQC) and Continuation of Construction Plan (CCP) . The programs developed in response to your letter of October 4, 1983 will be utilized, as appropriate, in the implementation of this work.

We request your concurrence in this plan so that we can effectively do the necessary procedure development'and planning.

We trust this letter will also be found acceptable as an interim report under 50.55 (e) for Items E-20 and E-29.

Very truly yours, THE CINCINNATI GAS &-ELECTRIC COMPANY l

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j. . ILL AMS, JI SENIOR VICE P IDENT l

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cc: NRC Office of Inspection & Enforcement

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Washington, D.C. 20555 L NRC Resident Site Supervisor ATTN: W.M. Hill NRC Zimmer Project Inspector, Region III l ATTN: E. R. Schweibinz

R LOZ-83-0180 ATTACHMENT'A

- Evaluating ~ Cable tray ~ and Conduit ' Support ' Welding Along With ' the Adequacy of Threaded Nelson Studs Used on Cable Tray Supports ics were initially reported to the commission on 5/3/82 These and 9/28top /82 respectively, as potentially reportable deficiencies under 10CFR50.55(e), Items E-20 and E-29.

l The E-20 program addresses the' concerns that hot-dip galvanizing I or spray-on galvanox coating on' welds may hinder reinspection 1 efforts and that the original inspection was not 100% complete. l This program also supports the resolution of problems with materials,. welder identification, welder qualification and weld procedure qualifications. Destructive tests will be utilized to obtain existing weld strength since removal of the hot-dip' galvanizing is difficult and may present additional concerns.

The capacity of existing welds with minor weld discontinuities shall be verified in order to minimize rework.

-This program utilizes a sampling plan which is based on MIL-STD-414.- The allowable weld strength shall be determined with a 95/95 (Confidence / Reliability) factor. The number of supports, not. individual welds, are used to determine the total sample

population. .The sample size shall be consistent with the Level V requirement of. MIL-STD-414 - (more samples than normal inspection level).

A visual inspection, to AWS D 1.1, shall be performed on all welds of the sample cable tray and conduit support hangers. The samples with spray on galvanox coatings will be wire brushed until the. coating is removed prior to inspection, while the hot-l dip galvanizing will not be removed for reasons described above.

o Welds found acceptable through visual inspection will not be I

subjected to the shear strength test. . Samples of unacceptable welds will be subjected to such tests. Weld deficiencies not I meeting' the visual inspection criteria shall be documented on L NR's.- Traceable identification will be provided for the l' unacceptable welds. Whether the unacceptable weld is hot-dip 1 galvanized, galvanox coated, shielded metal arc or gas metal arc welded will be documented to the extent possible.

Unacceptable welds identified by the visual inspection shall be reviewed and test samples shall be randomly selected. The selected samples shall be cut out from the existing hangers and J ~ subjected to shear strength testing to determine the allowable weld strength. MIL-STD-414 shall be used to verify that the weld

, strength determined corresponds to a 95/95 (Confidence / Reliability) factor. The allowable weld stresses

~ shall be established utilizing safety factors in the original design ~ codes.

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LOz 83-0180'

- "ATTACHMElfr A" Page 2 .l Allowable weld stresses established.from the shear strength testing shall be used to evaluate the capacities of connections containing welds with discontinuities in the original hanger i sample. Welds with discontinuities shall be considered ecceptable if all connections'in the hangers are evaluated Mnd found to have adeqcate capacity. If this-program is successful, all accessible welds.will be' visually reinspected to verify weld size, length, and that no. cracks exist. All inspection activities shall be documented. Connections which do not have adequate capacity shall either be reworked in accordance with site approved procedures or the applicable hanger shall be replaced.

The following exceptions to industry standards described in

'the PSAR are taken in regard to the Cable Tray and Conduit Support Welding Reinspection Program:

FSAR'Section 3.13.10.1.1 Welded Connections

. Exception to AWS Structural Welding Code D1.1-1972r Strength testing of sample support connections is used to establish acceptance of connection welds with discontinuities.

FSAR Section 3.13.10.2 Inspection'of'Weldsents Exception to AWS Structural Welding Code D1.1-1972r Modified acceptance criteria is used for support weld acceptance, based.on strength testing of sample support connections.

The FSAR will be revised to document the above AWS Code exceptions.

The E-29 sampling program resolves concerns relating to the.

adequacy of the threaded Nelson studs and provides an evaluation of the base metal discontinuities caused by the removal of a stud used for temporary support of a locating' template. This sampling plan is based on MIL-STD-105D and the sample being large enough to-result in a 95/95 (confidence / Reliability) factor. The capacity of the^ supports will be_the attribute tested rather than the capacity .of . individual studs . This program is in conformance with-all design and construction requirements described in the FSAR. The program outline is as follows:

(1) ' Test torgtdng Nelson studs to the values specified in AWS D 1.1, Section 7.6.

LOZ~83-0180 "ATYACHMENT A" Page 3

-(2) Evaluate cable tray support adequacy based on torque test'results from Step 1.

(3) Dismantling cable tray. supports and evaluating base metal discontinuities by visual inspection. Base metal cracks are not acceptable.

All inspection activities will be documented and will be in accordance with site approved procedures. This program shall be appropriately integrated into the reinspection activities of the Item E-20 program.

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