ML20056G079
| ML20056G079 | |
| Person / Time | |
|---|---|
| Issue date: | 07/01/1993 |
| From: | Richardson J Office of Nuclear Reactor Regulation |
| To: | Tully C BWR OWNERS GROUP, SOUTHERN NUCLEAR OPERATING CO. |
| References | |
| NUDOCS 9309020013 | |
| Download: ML20056G079 (2) | |
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W fr n1 $1 Ms. Cynthia L. Tully, Chairperson BWR Owners' Group Southern Nuclear Operating Company P. O. Box 1295, Bin B052 Birmingham, Al 35201
Dear Ms. Tully:
By letter dated April 30, 1993, the BWR Owners' Group submitted a topical report entitled "BWR Owners' Group Topical Report on Upper Shelf Energy Equivalent Margin Analysis," for staff review and approval.
This report was intended to demonstrate through fracture mechanics analysis that there exists margins of sfety against fracture equivalent to those required by Appendix G of ASME Coob Section III, for those beltline materials having Upper-Shelf Energy values below the screening criterion of 50 ft-lb.
The Materials and Chemical Engineering Branch has completed a preliminary review of this report and is transmitting a reouest for additional information (RAI). To complete our final review on schedule, we request a response to the enclosed RAI within 30 days of receipt.
If you have any questions, please contact Simon Sheng of my staff at 301-504-2708.
Sincerely, Origina!signedtyf James E. Richardson, Director Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
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w ATTACHMENT REQUEST FOR ADDITIONAL INFORMATION 1.
The Topical Report, NED0-32205, indicates that the convective heat transfer coefficient at thp
- inner surface of the vessel was specified as 500 BTU /hr-ft - F in the tensile thermal stresses calculation for Level A and B conditions while the convective heat transfer poefficient used for Level C and D conditions was 10,000 BTU /hr-ft
- F.
Provide justification for using these numbers (Page 5-3 and Page 6-2).
[ 2.
Demonstrate that "the axial flaw K values are expected to envelope the circumferential flaw K values, given the same stress distribution" for the thermal transient condition (Page 6-3).
3.
Demonstrate that using equations 3-1 and 3-3 for an a/t value of 0.1, which is outside its stated applicability range of 0.2 < a/t
< 0.5 under Level C and D conditions, is adequate (Page 6-3).
4.
If some plates designated as 5338-1 or 302B-Mod, such as the third, fifth, eighth, twenty-third, and thirty-first plate in Table 8-2, were classified as 302B due to their high sulfur contents, and the J-R calculations pertinent to 3028 plates were used, will they have the same margin as that shown in figures 8-1 and 8-2 (Page 8-13)?
5.
Provide justification for the following technical decisions made in the submittal: (1) choosing the J models without thickness g
(B ) terms for all J-R curves over that with thickness terms; (2) n choosing the Combined Database Model over the RPV Welds Copper-Fluence Model for non-Linde 80 welds (Page 4-3 to 4-5).
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