ML20214M585
| ML20214M585 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 05/22/1987 |
| From: | Youngblood B Office of Nuclear Reactor Regulation |
| To: | James O'Reilly GEORGIA POWER CO. |
| References | |
| NUDOCS 8706010358 | |
| Download: ML20214M585 (3) | |
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50-425 Mr. James P. O'Reilly Senior Vice President - Nuclear Operations Georgia Power Company P.O. Box 4545 Atlanta, Georgia 30302
Dear Mr. O'Reilly:
Subject:
Vogtle Unit 2 Steam Generator Snubber Reduction and Auxiliary Line Break Elimination Program On April 17, 1987, the staff met with representatives from Georgia Power Company (GPC) and Westinghouse to discuss the application of leak-before-break (LBB) technology to auxiliary lines and steam generator snubber reduction for Vogtle Unit 2.
At the meeting, the GPC representatives indicated that a submittal outlining the conceptual proposals on these issues would be provided to the staff by May 1 and requested staff confirmation of that anticipated submittal. The staff also committed to provide clarifying information on certain points raised at the meeting. Hence this letter serves both aforementioned purposes.
The first issue requiring staff clarification concerns material properties.
For the fracture mechanics evaluation, a lower-bound material stress-strain relationship should be used in the crack stability analysis.
The apolication of the lower-bound relationship is consistent with the intent of the ASME Code to account for material data scatter.
For the leakage evaluation, a best estimate stress-strain relationship should be used in the leakage rate analysis. The reason for application of the best estimate relationship is to provide a realistic evaluation of the leakage rate and not to decrease the effective leakage rate margin.
Furthermore, the material properties selected for the LBB analysis should be demonstrated to be representative of the specific plant materials under review.
A second issue requiring clarification is the treatment of branch lines in the LBB analysis.
For geometrically complex fluid system piping, the functional system for which the application of LBB is being requested should be identified. A throughwall flaw should be postulated in each size of pipe comprising the functional system in the LBB analysis. The flaws in each size of pipe need not be postulated simultaneously.
However, a throughwall flaw may not be postulated in the moderate energy portion of piping, i.e., pressure below 275 psig and temperature below 200 F.
The LBB analysis should include the functional piping system from anchor point to anchor point.
If a branch line of another functional system is present for which LBB is not intended to be applied, the branch line may not be included in the LBB analysis. However, if breaks are postulated according to Standard Review Plan Section 3.6.2 for the branch line, the most limiting reaction forces resulting from postulated breaks in the branch line must be included in the LBB analysis for the functional system involved.
B706010358 870522 PDR ADOCK 05000425 A
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MY 2 2 1987 Mr. J. P. O'Reilly
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Following the April 17 meeting, GPC submitted its technical basis for steam generator snubber reduction and application of LBB methodology to selected ASME Class 1 branch lines (pressurizer surge line, two residual heat removal lines, and four accumulator injection lines) by letter dated April 29, 1987.
Specifically, GPC has proposed reduction of Unit 2 steam generator snubbers from 5 to 2 per steam generator and elimination of postulated pipe ruptures, the associated dynamic effects, and the required hardware to mitigate those dynamic effects in the selected branch lines. The staff has reviewed the GPC proposal within the context of the current staff position.
In particular, in heavy component support redesign, improved functional reliability must be demonstrated for any changes made. Structural capacity associated with the original steel and concrete, including struts, columns, pedestals, hangers, trusses and skirts cannot be diminished in the support system of operating plants or plants under construction.
Redesigns will be limited to replacing high strength fastener material and reducing the number and capacity of snubbers. Applicants and licensees undertaking heavy component support redesign, with dynamic effects of pipe rupture eliminated, should use independent design and fabrication verification procedures to the extent possible to minimize design and construction errors. This staff position is the subject of proposed rulemaking on General Design Criterion 4 with final approval estimated for late 1987.
On the basis of the staff's review of GPC's April 29, 1987, submittal, we con-clude the proposal as outlined conforms to the current staff technical position and provides an acceptable basis upon which GPC can complete a detailed tech-nical evaluation for staff review.
Sincerely,
\\9 B.J. Youngblood, Director Project Directorate II-3 Division of Reactor Projects I/II 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 Consnission Georgia Power Company P. O. Box 572 P.O. Box 4545 Waynesboro, Georgia 30830 Atlanta, Georgia 30302 Mr. Ruble A. Thomas Deppish Kirkland, III, Counsel Vice President - Licensing Office of the Consumers' Utility Vogtle Project Council Georgia Power Company /
Suite 225 Southern Company Services, Inc.
32 Peachtree Street, N.W.
P.O. Box 2625 Atlanta, Georgia 30303 Birmingham, Alabama 35202 James E. Joiner Mr. Paul Rice Troutman, Sanders, Lockerman, Vice President & Project General Manager
& Ashmore 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 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 Mr. G. Bockhold, Jr.
Vogtle Plant Manager Georgia Power Company Route 2, Box 299-A Waynesboro, Georgia 30830 Regional Administrator, Region II U.S. Nuclear Regulatory Commission 101 Marietta Street, N.W., Suite 2900 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
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