ML19308C651

Forwards Revision 1 of Util Response to IE Bulletin 79-02, Revision 2, Pipe Support Base Plate Designs Using Concrete Expansion Anchor Bolts. Util Will Account for Base Plate Flexibility in Expansion Anchor Bolt Load Calculations

ML19308C651
Person / Time
Site:	Catawba
Issue date:	01/07/1980
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
IEB-79-02, IEB-79-2, NUDOCS 8002010052
Download: ML19308C651 (4)

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Mr. J. P. O'Reilly, Director U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, CA 30303 Re: RII:JPO 50-413 and 50-414

Dear Mr. O'Reilly:

Attached is Revision 1 of Duke Power Company's response to IE Bulletin 79-02. This response is submitted pursuant to Revision 2 of IE Bulletin 79-02, transmitted by your letter of November 8, 1979. Our revised response addresses Bulletin Items 5, 6, 7, 8 and 9 which were new additions to the Bulletin and revises Responses 3 and 4 to reflect current status.

Ve . truly your , .

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William O. Parker, ROS/sch Attachment 4

cc: Mr. W. P. Ang, Region II Division of Reactor Construction Inspection Office of Inspection and Enforcement

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$ CATAWBA NUCLEAR STATION Responses to USNRC IE Bulletin 79-02, Revision 2 ,

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Original: July 5, 1979 -

Revision 1 : January 7, 1980

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Catawba Huclear Station is in the early stages of construction. As of this date, less than 800 supports have been erected and only a portion of these have been erected using expansion anchors. The following is a summary, by item, of the extent and manner in which Duke Power Company intends to satisfy Actions 1 through 9 of the 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 Cate-gory I pipe support base plates using either a conservative hand calculation method which has been verified by non-linear finite element analysis or a specific non-linear finite element analysis for a particular base plate. The models and boundary conditions, including appropriate load-displacement character-istics of the anchors, used for the finite element analyses are based on Duke studies and on work performed by Teledyne Engineer-ing Services which was sponsored by a group of thirteen (13) utilities formed to respond to generic items of IE Bulletin 79-02.

All expansion anchor suport plates designed prior to implement-ing these analysis methods are being re-analyzed accordingly and will be modified if required to comply with allowable anchor bolt loadings.

Response 2: The minimum factors of safety, between the extansion anchor de-sign load and the anchor 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 expansion anchors which are the only type of anchors used at

- Catawba Nuclear Station for Nuclear Safety Related applications._

. Expansion anchor installations f'o r Seismic Category I piping supports are restricted to normal weight structural concrete of varying nominal strengths. Expansion anchor ultimate load capacities are based on manufacturer's test results and recom-mendations for nonnal weight concrete and installed concrete strengths.

Catawba Seismic Category I expansion anchor designs properly account for shear-tension interaction, minimum edge distances

b and bolt spacing in accordance with manufacturer's test results and recommendations.

Response 3: -Duke Power Company designs pipe supports to resist all applicable

loadings including seismic loads, hydro test loads, normal operat-

. ing loads, thernal loads, etc. A support is designed. for a static or quasi-static load resulting from the most critical _

combination of the applicable loadings. The safety factors used for the expansion anchors are as specified in Response 2. Duke Power Company co-sponsored tests performed by Teledyne Engineering Services to demonstrate that expansion anchors installed at Catawba Nuclear Station will perform adequately under both low cycle /high amplitude loading (seismic) and high cycle / low amplitude loading (operating loads). The final test report was generically 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)datedAugust 15, 1979 regarding Catawba Nuclear Station.

Response 4: All expansion anchors used in Nuclear Safety Related applications are either wedge type or sleeve type. These anchors are in-spected for proper installation in accordance with Duke Power Company's Quality Assurance Procedure M-52, " Concrete Expansion Anchor Installation Inspection". This procedure assures that the anchors are properly installed in accordance with the manufacturer's recommendations.

Procedure M-52 criteria includes, but is not limited to, in-spection of expansion anchor size, type, perpendicularity, torque, embedment depth, spacing, distance to free concrete edge and un-authorized modification of the anchor. Plate bolt hole over-sizing is not specifically inspected for the following reasons:

1. Duke Power Company Quality Assurance Procedures prohibit deviations from design drawings and specifications without written authorization and approval by the Design Engineering Department.

2. Catawba Nuclear Station qualifies each concrete expansion anchor operator by installation test and verbal examination on proper installation procedure.

As an additional precaution, Duke Power Company is currently revising Procedure M-52 to include visual inspection of con-nections for evidence of plate bolt hole oversizing. This in-spection is documented for each Nuclear Safety Related pipe sup-port. l

.In order to address the question of the relationship of cyclic load carrying capacity to installation procedure (anchor pre-load), the tests referred to in Response 3, performed by Teledyne Engineering Services and sponsored by the group of thirteen (13) utilities, have been performed on anchors installed in accordance with manufacturer's recommended installation pro-cedures and have no more preload than is provided by the use of these procedures. Based on Duke's understanding of the 2

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behavior of expansion anchors and on cyclic testing which has been performed, Duke Power Company is confident that the anchors

,}will perform adequately.

Response 5: Nuclear Safety Related/ seismic pipe supports are prohibited from

'being attached to block (masonry) walls using concrete expansion anchors. -

7 R6sponse 6: A limited number of Nuclear Safety Related/ seismic pipe support's installed with concrete expansion anchors do utilize structural shapes instead of base plates. These hangers are included in actions performed to satisfy the requirements of IE Bulletin 79-02.

Response 7: Catawba Nuclear Station is currently under construction, therefore Bulletin Item 7 is not applicable.

Response 8: Catawba Nuclear Station is currently under construction, therefore Bulletin Item 8 is not applicable Response 9: Those pipe supports which have not been installed are included in actions performed to meet the requirements of IE Bulletin 79-02 as outlined in Responses 1 through 6.

Revision 2 of Item 2 of the Bulletin requests verification by Duke Power Company that a uniform factor of safety was applied for all load combinations in the design of expansion anchors for Catawba Nuclear Station. The expansion anchor design factors of safety utilizcJ are outlined in Response 2 and are graded based on the normal, upset and faulted load combination. The gradation approach is consistent with design practices for other types of structures subject to the same load combinations.

There are no previously unreported instances in which Duke Power Company did not meet the revised (R2) sections of Item 4 prior to its issuance.

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