ML20083G922
| ML20083G922 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 12/15/1983 |
| From: | Tucker H DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-SSINS-6820 IEB-79-02, IEB-79-2, NUDOCS 8401060471 | |
| Download: ML20083G922 (5) | |
Text
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.e DUKE POWER GOMPANY P.O. H O X (Kll8 0 CHAFLOTTE, N.C. 28242 HALILTUCKER Tetzenoxe vua paraserwe (704) 373-4531
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December 15, 1983 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Re: RII:JPO 50-413 and 50-414
Dear Mr. O'Reilly:
Please find attached a final response to IE Bulletin 79-02, Revision 2 for Catawba Nuclear Station, Units 1 and 2.
This response Is a summary by item of the extent and manner in which Duke Power Company intends to satisfy Actions 1 through 9 of the bulletin.
Very truly yours, dr
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Hal B. Tucker LTP/php Attachment cc: NRC Resident. Inspector Catawba Nuclear Station Mr. kobert Guild, Esq.
Attorney-at-Law P. O. Box 12097 Charleston, South Carolina 29412 Palmetto Alliance 2135 Devine Street Columbia, Sou;h Carolina 29205
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e CATAWBA NUCLEAR STATION Responses to USNRC IE Bulletin 79-02, Fevision 2 Original: July 5, 1979 Revision 1: January 7, 1980 Revision 2: November 28, 1983 Catawba Nuclear Station is in the later stages of construction of Unit 1.
Unit 2 is in the middle stage of Construction. 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 accounts for base plate flexibility in the calculation of expansion anchor loads for all scismic Category 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 ana-lysis for a particular base plate. The models and boundary conditions, including appropriate load-displacement charac-teristics of the anchors, used for the finite element analyses are based on Duke studies and on work performed by Teledyne Engineering Services which was sponsored by a group of thir-teen (13) utilities formed to respond to generic items of IE Bulletin 79-02.
All expansion anchor support plates designed prior to implementing these analysis methods were re-analyzed accordingly and modified if required to comply with allowable expansion anchor loadings.
Response 2: The minimum factors of safety between the expansion anchor design load and the anchor ultimate capacity determined from static load tests used in design of seismic Category I pipe supports are as follows:
For supports originated prior to November 1, 1980
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Using straight line shear / tension in raction formula.
u ed For supports originated on or after November 1, 1980
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Option to use less conservative shear / tension interaction formula F lted These factors of safety are for wedge type and sleeve type ex-pansion anchors which are the only type of anchors used at Catawba Nuclear Station for seismic Category I pipe support application s.
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Expansion anchor installations for 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 recommendations for normal weight concrete and installed con-crete strengths.
Catawba seismic Category I expansion anchor designs properly account for shear-tension interaction, minimum edge distances and bolt spacing in accordance with manufacturer's test results andreefmmendations.
Duke Power Company has completed an evaulation of minimum safety factors for expansion anchors used for seismic Category I pipe supports at Catawba Nuclear Station. The intent of this evaulation was to verify with 95% confidence that less than 5%
of the expansion anchors for supports in any piping system fail to meet the minimum safety factor of 4 for all conditions. This statistical approach is similar to that taken for Duke's McGuire Nuclear Station in response to the same I & E Bulletin. The results of the evaluation for Catawba clearly indicate that the statistical condition stated above is satisfied.
The evaluation consisted of a review of all 48 piping systems supported with seismic Category I pipe supports. Statistically, achieving the desired confidence limit / failure percentage re-quired review of 59 randomly selected supports for each system.
Twenty-five systems contained less than 59 supports with expan-sion anchors, therefore all supports in these systems were re-viewed and all of these supports had a minimum safety factor of 4 for all conditions. The remaining 23 systems contained more than 59 supports with expansion anchors. Fifty-nine randomly selected supports in each of these systems were reviewed. Only one support was found to have an unchor with a safety factor less than 4 for any load condition. This support was redesigned to achieve a minimum safety factor of 4 for all conditions. Addi-tionally, the remainder of the supports for that system (FW) were reviewed (totaling 94) and found to have tinimum safety factors of 4 for all conditions.
In all, 1,894 supports were reviewed.
This review was made on Unit 1 supports existing as of October 1982.
Since that time, many Unit I seismic Category I pipe supports have been added, all designed to a safety factor of 4 for all conditions. All Unit 2 seismic Category I pipe supports will be designed with a minimum safety factor of 4 for all condicions.
In summary, Duke Power Company is statistically 95% confident that less than 5% of all seismic Category I expansion anchor designs for any system in Catawba fail to meet a minimum safety factor of 4 for all conditions.
Furthermore, it is believed that this condition will exist throughout the operating life of the plant. __.
I Response 3: Duke Power Company designs pipe supports to resist all applicable loadings including seismic loads, hydro test loads, normal opera-ting loads, thermal loads, etc.
A support is designed for a static or quasi-static load resulting from the most critical l
combination of the applicable loadings. The safety factors l
used for the expansion anchors are as specified in Response 2.
I 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 Stations as described in Mr. L. C. Dail's (Duke) letter to Mr. J. P. O'Reilly (USNRC, RII) dated August 15, 1979 regarding Catawba Nuclear Station.
Response 4: All expansion anchors used in seismic Category I 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 manu-facturer'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. This procedure also re-quires inspection for evidence of plate bolt hole oversizing (i.e. cupped washers, visibly excessive hole diameters). As additional precautions the following apply:
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.
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 in-stalled in accordance with manufacturer's recommended in-stallation procedures and have no more preload than is pro,
vided by the use of these procedures.
Based on Duke's under-standing of the behavior of expansion anchors and on cyclic testing which has been performed, Duke Power Company is confi-dent that the anchors will perform adequately. _ - - _ _ - _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Response 5: Seismic Category I pipe supports are prohibited from being attached to block (masonry) walls using concrete expansion anchors.
Response 6: A limited number of seismic Category I pipe supports 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, there-fore Bulletin Item 7 is not applicable.
Response 8: Catawba Nuclear Station is currently under construction, there-fore 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 fac-tors of safety utilized are outlined in Response 2.
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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