ML19257D566

Forwards Revision to Response to IE Bulletin 79-02,Revision 2,re Pipe Support Base Plate Designs.Will Account for Base Plate Flexibility in Calculations of Bolt Loads by Using Conservative Hand Calculation Method

ML19257D566
Person / Time
Site:	Cherokee
Issue date:	01/07/1980
From:	Dail L DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
IEB-79-02, IEB-79-2, NUDOCS 8002050002
Download: ML19257D566 (4)

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Mr, J. P. O'Reilly, Director U S. Nuclear Regulatory Commission 101 Marietta St reet , Sui te 3100 Atlanta, Georgia 30303 Re: Cherokee Nuclear Station Docket Nos. 50-i91, 492, & 493 _-

IE Bulletin 79-02, Rev. 2 Duke Files: CK-1196.02, CK-1415.00, CK-1412.ll-1

Dear Mr. O'Reilly:

Enclosed f or your use is Revision 1 of Duke Pcc..er's response to IE Eulletin 79-02. This revises the response to IE Bulletin 79-02, Revision I, con-tained in my letters of July 5,1979 ind August 15, 1979.

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CHEROKEE NUCLEAR STATION Pasponses to USNRC IE Bulletin 79-02, Revision 2 Original: July 5,1979 Revision 1: January 7, 1980 Cherokee Nuclear Station is in the early stages of construction and no pipe supports have been installed to date. The following is a sumary, by item, of the extent and manner in which Duke Power Company intends to satisfy Actions 1 through 9 of IE Bulletin 79-02, Revision 2.

Response 1: Duke Power Company will account for base plate flexibility in the calculation of expansion anchor bolt loads for all Seismic Category I pipe support base plates using eithee a conservative hand calculation method which has been verified by non-linear finite element analysis or a specific nori-linear finite element analysis for a particular base plate. The models and boundary conditions, including appropriate lead-displacement character-istics of the anchors, used for the finite elenent analyses are t:ased on Duke studies and on work perfonned by Telrdyne Engineer-ing Services which was sponsored by a group of thirteen (13) utilities formed to respond to generic iters et ir Bulletin 79-02.

Re<nonse 2: The ninimum factors of safety, betwccn the expansion anchor de-sign load and the enchor ultimate capacity determined from static load tests, used in Duke Power Company design of pipe supports are as follows:

Normal Conditions -

4 Upset Conditions -

3 Faulted Conditions - 2 These factors of safety are for wedge type and sleeve type ex-pansion anchors which are the only types of anchors which will be used at Cherokee Nuclear Station for Nuclear Safety Related applications.

Expansion anchor installations for Seismic Category I piping supports are restricted to nonnal weight structural concrete of various noni nal strengths. Expansion anchor ultinate load capacities are based on nanufacturer's test results and recom-mendations for normal weight concrete and installed concrete strengths.

Cherokee 5eismic Category I expansion anchor designs will pro-1871 Ob3~'~

perly account for shear-tension interaction, minimum edge distances and bol t spacing in acc ordante with manufacturer's test results and reccomendations.

Pesponse _3_: Duke Power Company designs pipe supports to resist all applicable loadings including seismic loads, hydro test loads, normal oper-ating loads, thercal loads, etc. A support is designed for a static or quasi-static load resulting from the rost critical com-bination of tha applicable loadings. The safety factors used for the expansion anchors will be as specified in Response 2. Duke Power Company co-sponsored tests performed by Teledyne Engineer-ing Services to demonstrate that the anchors procured for use at Chernkee Nuclear Station will perform adequately under both low cycle /high amplitude loading (seismic) and high cycle / low ampli-tude loading (operating loads). The final test report was gen-erically submitted to USNRC for all Duke Power Company Nuclear Stations as described in Mr. L. C. Dail's (Duke) letter to Mr.

J. P. O'Reilly (USNRC, RII) dated August 15, 1979 regarding Chero-Lee Nuclear Station.

Response 4: All expansion anchors used in Nuclear Safety Pelated applications will be either wedge type or sleeve type. The anchors will be inspected for proper installatico in accordance with Duke Power Company's Quality Assurance Percedure M-52, " Concrete Expansion Anchor Ins talla tion !nspection' This procedure will assure thM expansion anchors are properly installed in acc ordance with the na nufac turer 's reconnenda tic os .

Procedure M-52 criteria includes, but is not limited to, inspec-tion of expansion anchor size, type, perpendicularity, torque, cmbednent depth, spacing, distance to free concrete edge and unauthorized modification of the anchor. Plate bol t hole over-sizing is not specifically inspected for the following reasons:

1. Duke Poser Company Quality Assurance Procedures prohibit de-viations from design drawings and specifications without written authorization and approval by the Design Engineering Departrent.

2. Cherokee Nuclear Station will qualify each concrete expan-sion anchor operator by installation test and verbal exam-ination on proper installation procedure.

As an additional precaution, Duke Pcwer Company is currently re-vising Procedure M-S2 to include visual inspection of connections for evidence of plate bolt hole oversizing. This inspection will be documented for each Nuclear Safety Related pipe support.

In order to address the question of the relationship of cyclic 2 1871 064

load carrying capacity to installation procedure (anchor pre-load), the tests referre1 to in Response 3, rerformed by Tele-dyne Engineering Services, and sponsored by the group of thirteen (13) utilities, have been perforned on anchors installed in ac-cordance with r 'nufacturer's recomr:endea installation procedures and have no more preload than is provided by the use of these pro-cedures. Based on Duke's unders tanding of the behavior of expan-sion anchors and on cyclic testing which has been performed, Duke Power Company is confident that the anchors ,till perform adequately.

Response 5: Nuclear Safety Related/seisnic pipe supports are prohibited from being attached to block (masonry) walls using concrete expansion anchors.

Respcnse 6: A linited number of Nuclear Safety Related/seisnic pipe supports installed with concrete expansien anchors do utilize structural shapes instead of base plates. These hangers are included in actions perforn.ed to satisfy the requirements of IE Bulletin 79-02.

Ke s19As_e_ 7_: Cherokee Nuclear Station is currently under construction, theref ore Bulletin Iten 7 is not applicable.

Response 8: Cherobe Nuclear Station is urrently under cont truction, therefore Bulletin Iten B is rot applicable.

lesponse 9: Those pipe supports wnich have not been inctalled are included in actions perfonned to meet the requirements of IE Bulletin 79-02 as outlined in Responses 1 the ough 6.

Revision 2 of Action Iten 2 of the Bulletin requests verification by Duke Power Company that a uni form factor of safety was applied fur all load combinations in the design of expansion anchors for Cherokee Nuclear Station. The expansion anchor design factors of safety utilized are outlined in Response 2 and are graded based on the normal, upset and faulteJ load combination. The gradation approach is consistent with design practices for other types of structures subject to the same load conbinations.

There are no previously unreported instances in which Duke Fower Conpany did not meet the revised (R2) sections of Action Item 4 prior to i ts issuance.

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