ML20239A612

Forwards Request for Addl Info on Elimination of Postulated Pressurizer Surge Line Ruptures as Design Basis,In Response to Util 870715 & 0819 Submittals

ML20239A612
Person / Time
Site:	Vogtle
Issue date:	09/09/1987
From:	Mark Miller Office of Nuclear Reactor Regulation
To:	James O'Reilly GEORGIA POWER CO.
References
NUDOCS 8709170528
Download: ML20239A612 (1)

Text

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Docket-No.: .50-425 l

'Mr. James.P. O'Reilly.

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Senior Vice President - Nuclear Operations Georgia-. Power Company P. O. Box 4545 Atlanta, Georgia 30830-

Subject:

Request for Additional Information on Dynamic Effects of Postulated Pressurizer Surge Line Pipe Ruptures from Design Basis for Vogtle-Unit 2 By letter dated July 15, 1987, Georgia Power Company (GPC) submitted the

-technical basis for the elimination;of the dynamic effects of. postulated pipe ruptures in the pressurizer. surge line of Vogtle Unit 2 in Westing-house report WCAP-11531. On the basis of its review of this' report, the.

staff requested additional information by letter dated August 6,1987.

In response, .GPC submitted Addendum 1 to WCAP-11531 by letter dated -

August 19, 1987. The staff has reviewed GPC's submittals and finds that insufficient additional information was provided for the flaw stability evaluations. A request for additional infonnation is enclosed.

Sincerely,

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Melanie A. Miller, Project Manager Project Directorate 11-3 Division of Reactor Projects, I/II '

Enclosure:

As stated cc: See next page DISTRIBUTION:

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Mr. J. P. O'Reilly Georgia Power Company Vogtle Electric Generating Plant cc: )

Mr. L. T. Gucwa Resident Inspector Chief Nuclear Engineer Nuclear Regulatory Comission I' Georgia Power Company P. O. Box 572 P.O. Box 4545 Waynesboro, Georgia 30830  !

Atlanta, Georgia 30302 1 Mr. Ruble A. Thomas Depoish Kirkland, III, Counsel Vice President - Licensing Office of the C6nsumers' Utility 3 Vogtle Project Council' l Georgia Power Company / Suite 225 Southern Company Services, Inc. 32 Peachtree Street, N.W.

P.O. Box 2625 Atlanta, Georgia 30303 I Birmingham, Alabama 35202 J James E. Joiner  !

Mr. Paul D. Rice Troutman, Sanders, Lockerman, Vice President & Project General Manager & Ashmore q Georgia Power Company Candler Building Post Office Box 299A, Route 2 127 Peachtree Street, N.E.

Waynesboro, Georgia 30830 Atlanta, Georgia 30303 ),

Danny Feig Mr. J. A. Bailey 1130 Alta Avenue Project Licensing Manager Atlanta, Georgia 30307 Southern Company Services Inc.

P.O. Box 2625 Carol Stangler Birmingham, Alabama 35202 .

Georgians Against Nuclear Energy 425 Euclid Terrace ,

4 Ernest L. Blake, Jr. Atlanta, Georgia 30307  !

Bruce W. Churchill, Esq.

Shaw, Pittman, Potts and Trowbridge 2300 N Street, N. W. <

Washington, D. C. 20037 {

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Mr. G. Bockhold, Jr.

Vogtle Plant Manager Georgia Power Company l Route 2, Box 299-A l Waynesboro, Georgia 30830 Regional Administrator, Region II l U.S. Nuclear Regulatory Comission i 101 Marietta Street, N.W. , Suite 2900 '

l Atlanta, Georgia 30323 Mr. R. E. Conway Senior Vice President and Project Director Georgia Power Company Rt. 2, P. O. Box 299A Waynesboro, Georgia 30830 5

ENCLOSURE ,

REQUEST FOR ADDITIONAL INFORMATION ON ELIMINATION OF POSTULATED PRESSURIZER SURGE LINE RUPTURESe i AS A DESIGN BASIS g i

GEORGIA POWER COMPANY ,

V0GTLE ELECTRIC GENERATING PLANT UNIT 2 DOCKET NO. 50-425 )

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l By letter dated July 15, 1987, Georgia Power Company (the applicant) submitted I the technical basis for the elimination of the dynamic effects of postulated  !

pipe ruptures in the pressurizer surge line of Vogtle Unit 2 in Westinghouse i report WCAP-11531. By letter dated August 19, 1987, the applicant submitted Addendum 1 to WCAP-11531 in response to the staff's request for additional information in a letter dated August 6,1987. The staff has reviewed the submittals and finds that insufficient additional information was provided for the flaw stability evaluations.

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On pages 2 through 4 of Addendum 1 to WCAP-11531, the applicant discussed the j fracture toughness properties of welds. The applicant used the fracture I toughness data from the literature in Figure 4-4 of WCAP-11531 in the flaw l stability analyses. The applicant contended that the "9.5T" submerged arc ,

l weld (SAW) specimen data in Figure 4-4 of WCAP-11531 provided a lower bound 1 l for the shielded metal arc welds (SMAW) in the surge line of Vogtle Unit '2. I l However, the applicant did not provide sufficient justification 'or the i I

application of the single set of SAW data from the literature. The literature i data used in the fracture stability analysis must provide a reasonable lower

. bound for the welds at Vogtle Unit 2.

1 i l Comparing the applicant's referenced fracture toughness data with those I submitted by another applicant, the staff finds that the data in Figure 4-4 of WCAP-11531 are not lower-bound values for SAW, or even for SMAW. The staff is aware that the planform size of the test specimen affects the toughness data.

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However, the toughtess values for small crack growth should be less affected by the planform size than those for large crack growth. The staff compared ,

the toughness data in Figure 4-4 of WCAP-11531 with lower-bound toughness values submitted by another applicant and found that the fracture toughness "J" values for the referenced "9.5T" SAW specimen were approximately 35%

larger than the lower-bound values for SMAW for small crack growth. Since the applicant did not provide sufficient justification for the application of the data in Figure 4-4 of WCAP-11531, the staff finds that if the "9.5T" specimen data are to be used in the fracture stability analyses of SMAW, the "J" values l

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should be reduced by greater than 35% to ensure that the estimated fracture toughness "J" resistence curve would be a reasonable lower bound for Vogtle Unit 2. Thus, a 40% reduction in the "J" values of the "9.5T" specimen data in Figure 4-4 of WCAD-11531 would be acceptable to the staff. Furthermore, this method of extrapolation of the "J" resistance curve should be limited to a crack growth of less than 0.5 inch. Unlest the applicant provides adequatt justification by referencing a sufficiently arge number of data from the literature, this reduced "J" resistance curve should be used for SMAW.

On page 6 of Addendum 1 to WCAP-11537, the applicant contended that the margin of 1.4 on the loads should not be applied because of the method of load combination. However, it is the s'.aff!s current position that the margin of 1.4 and the method of load combina Ron1 described in NUREG-1061, Volume 3 are required. Thus, the margin of 1,,4 on the loads must be applied.

The applicant should reevaluate the flaw stability tearing modulus (J-T) analyses using the'redeced "J" resistance curve. If significant crack growth is predicted, the effects of crack growth should be considered in an incremental crack growth analysis. The applicant should demonstrate the stability of a through-wall flaw at least twice the size of the leakage-size flaw under combined normal and safe shutdown earthquake (SSE) loads. Also, the applicant should demonstrate the stability of the leakage-size flew if the loads are increased to at least 1.4 times the combination of normal and SSE loads.

As an alternative to performing a J-T tlaw stability analysis as discussed above, the applicant may perform a limit _ load analysis. However, the applied loads must be increased by a factor corre'sponding to the type of the flux weld. The "Z-factor" correction for flux welds is the basis for developing allowable flaw sizes for austenitic steel piping in Article IWB-3640 of the e' Winter 1985 Addendum of Section XI of the ASME Code. Specifically, for SMAW, "Z" = 1.15 [ 1.0 + 0.013 ("0D" - 4)-], where "0D" is the outer diameter of the pipe in inches. Also, the lower-bodnd flow stress of the base metal should be used in the limit load analysis. Thus, in performing a limit load analysis,,

the applicant should demonstrate the stability of a through-wall flaw at least twice the size of the leakage-size flaw if the loads are increased to "1" times the combination of normal and SSE loads. Also, the applicant should demonstrate the stability of the leakage-size flaw if the loads are increased to at least 1.4 "Z" times the combination of normal and SSE loads.

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