ML20210U277

Forwards Revised Pages 1/3 & 2/3 to SER Open Item 15 Re Arbitrary Intermediate Pipe Breaks.Info to Be Used as Interim Design Criteria Until NRC Criteria Issued.Util Will Inform NRC of Necessary Design Criteria Revs

ML20210U277
Person / Time
Site:	Vogtle
Issue date:	09/30/1986
From:	Bailey J GEORGIA POWER CO.
To:	Youngblood B Office of Nuclear Reactor Regulation
References
GN-1090, NUDOCS 8610090471
Download: ML20210U277 (4)

Text

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• Georgia Pow:r Company Route 2, Box 299A Waynesboro, Georgia 30830 Telephone 404 554-9961 404 724-8114 Southern Company Services, Inc.

Post Office Box 2625 Birmingham, Alabama 35202 Telephone 205 870-6011 September 30, 1986 Director of Nuclear Regulation File: X7BC35 Attention: Mr. B. J. Youngblood Log: GN-1090 PWR Project Directorate #4 Division of PWR Licensing A U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Reference:

1) NRC letter dated July 2, 1986, to Georgia Power Company

2) GPC letter dated August 4, 1986, to NRC NRC DOCKET NUMBERS 50-424 and 5-425 CONSTRUCTION PERMIT NUMBERS CPPR-108 AND CPPR-109 V0GTLE ELECTRIC GENERATING PLANT - UNITS 1 AND 2 SER OPEN ITEM 15: ARBITRARY INTERMEDIATE PIPE BREAKS

Dear Mr. Denton:

Enclosed is revised pages 1/3 and 2/3 to Attachment 3 in Reference 2 above. As discussed with members of your staff, the information on these pages will be used by the Vogtle Project as interim design criteria until the NRC issues their criteria on this subject. When the NRC issues their criteria, Georgia Power Company will evaluate this information as it is applicable to the Vogtle Design and will inform the NRC of our intent to revise our design criteria if necessary.

Should you have any questions, please inquire.

Yours truly, l

J. A. Bailey Project Licensing Manager JAB /wkl Enclosure cc: See page two

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SER Open Item 15: Arbitrary Intermediate Pipe Breaks File: X7BC35 Log: GN-1090 September 30, 1986 Page two cc: R. E. Conway R. A. Thomas J. E. Joiner, Esquire B. W. Churchill, Esquire M. A. Miller (2)

B. Jones, Esquire G. Bockhold, Jr.

NRC Regional Administrator NRC Resident Inspector D. Feig R. W. McManus L. T. Gucwa j Vogtle Project Files 1

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Attachment 3 I. The Interim Criteria for Evaluating the Effects of Welded Attachments Within 5 Piping Diameters of Arbitrary Intermediate Break Locations (AIBL) for High Energy ASME Class 2 & 3 and B31.1 Piping in Safety Related Structures A. For ASME Class 2 and 3 and B31.1 high energy piping intermediate breaks (excluding AIBL) where applicable, shall be postulated in accordance with the criteria of HEB 3-1 where the combined equation 9 and 10 stresses exceed the threshold of 0.8 of the combined equation 9 and 10 allowables.

B. If less than the minimum intermediate breaks have been postulated, then the W/A in the vicinity of the next highest stress location (in the event that one intermediate break is postulated), or the two highest stress locations (in the event that no intermediate breaks are postulated) will be reviewed to determine if breaks need to be postulated. The following criteria shall be adopted:

1. Pipe break (s) shall not be considered if:

a. No W/A is within 5 nominal piping diameters of the highest stress location (s) on high energy main steam and main feedwater systems.

b. No W/A is within 3% of the highest stress location (s) on remaining high energy piping systems other than main steam and main feedwater systems.

R = The mean pipe radius based on 1/2 nominal pipe diameter and thickness.

t = The pipe nominal thickness.

2. If condition 1 (a) above is not met for high energy main steam and main feedwater systems, a weak link analysis of the W/A support structure shall be made using the method described in Attachment 2. Pipe break (s) will not be postulated if this analysis shows that the pipe wall at the W/A to pipe interface is not the weak link.

3. For all high energy piping systems, if condition 1 (a) or 1 (b) above is not met, additional intermediate pipe breaks shall be postulated if the combi ed stress (dissipated local (Fig.1) plus general) within 3 Rt of the high stress location exceeds the threshold of 0.8 of the combined equation 9 and 10 allowables.

1/3

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i NOTE: Equations 9 & 10, whose combined results are compared against a threshold value of 0.8 times the combined equation 9  ;

& 10 allowable, to postulate, break locations, do not consider '

the effect of local stresses due to welded attachments.

In Appendix XIII of the ASME B&PV code,Section III, when l the effects of welded attachments are considered an increase in the allowable stress is permitted. For example, the equation 9 allowable for general piping stress is 1.2 SH whereas the allowable stress per Appendix XIII, when considering the local primary effects of welded attachments, is 1.65 Sm for upset conditions. It can therefore, be concluded that use of the threshold value of 0.8 times the combined equation 9 & 10 allowables to postulate pipe breaks when local effects of welded attachments are considered is conservative.

II. Method of Implementation of the Proposed Criteria

1. As-built pipe support and piping isometric drawings shall be used to determine the distance between the edge of the welded attachment and the edge of the break location.

2. Design Criteria DC-1017 and DC-1018 shall be revised along with the FSAR to describe the criteria for addressing welded attachments in the vicinity of intermediate high stress locations below the pipe break threshold.

3. The criteria shall be implemented each time a piping stress calculation is revised due to a significant change in pipe size, wall thickness, routing or loading conditions.

4. Documentation of break locations will continue to be reflected in the FSAR.

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