ML13330B543
| ML13330B543 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/15/1991 |
| From: | Nandy F SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML13330B545 | List: |
| References | |
| NUDOCS 9108070073 | |
| Download: ML13330B543 (4) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 F. R. NANDY July 15, 1991 TELEPHONE MANAGER, NUCLEAR LICENSING (714) 454-4504 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Thermal Shield Replacement Support Analytical Model San Onofre Nuclear Generating Station, Unit 1 This letter provides an evaluation of the thermal shield support system analytical model taking into consideration the Cycle 11 outage as-found conditions. This evaluation is provided in response to Item (a) from Amendment No. 140 dated December 19, 1990, which provided NRC approval of the thermal shield replacement support design but required resolution of several open items. Provided as an enclosure is the Westinghouse report, WCAP 12981, "Additional Engineering Evaluations for the SONGS 1 Thermal Shield Lower Support Replacement Design", dated June 1991(proprietary).
This report demonstrates that the analytical models and evaluation methods used to qualify the thermal shield supports are conservative. The non-proprietary version is also provided as WCAP 12982.
The design of the replacement thermal shield supports was completed before the thermal shield supports were inspected in the Cycle 11 refueling outage. As part of the design, existing analytical models which predict the vibration of the thermal shield and the resulting loads were refined. These new models were used to qualify the design of the new thermal shield supports to be installed during the outage, and were thought to overpredict the loads by about 20%.
Upon plant shutdown and thermal shield inspection, it was discovered that additional support components had failed since the time of the last inspection. To assure that the refined analytical models developed during the design of replacement thermal shield supports were conservative, we applied the loads generated by these models to the finite element models of the old supports to attempt to predict the failures noted in the as-found condition.
The Westinghouse report shows that the damage and failures predicted by these analyses are more severe than the as-found condition of the supports.
Therefore, the models used to qualify the replacement thermal shield supports are conservative.
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Document Control Desk
-2 Enclosed are:
- 1.
10 copies of WCAP-12981, "Additional Engineering Evaluations for the SONGS-1 Thermal Shield Lower Support Replacement Design" (Proprietary).
- 2.
10 copies of WCAP-12982, "Additional Engineering Evaluations for the SONGS-1 Thermal Shield Lower Support Replacement Design" (Non Proprietary).
Also enclosed are a Westinghouse authorization letter, CAW-91-183, accompanying affidavit, Proprietary Information Notice, and Copyright Notice.
As Item 1 contains information proprietary to Westinghouse Electric Corporation, it is supported by an affidavit signed by Westinghouse, the owner of the information. The affidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b)(4) of Section 2.790 of the Commission's regulations.
Accordingly, it is respectfully requested that the information which is proprietary to Westinghouse be withheld from public disclosure in accordance with 10 CFR Section 2.790 of the Commission's regulations.
Correspondence with respect to the proprietary aspects of the Application for Withholding or the supporting Westinghouse Affidavit should reference CAW-91 183 and should be addressed to R. P. DiPiazza, Manager of Operating Plant Licensing Support, Westinghouse Electric Corporation, P.O. Box 355, Pittsburgh, Pennsylvania 15230-0355.
If you have any questions concerning this matter, please call me.
Very truly yours, Enclosure cc:
George Kalman, NRC Senior Project Manager, San Onofre Unit 1 J. 0. Bradfute, NRC Project Manager, San Onofre Unit 1 J. B. Martin, Regional Administrator, NRC Region V C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2&3
Proprietary Information Notice Transmitted herewith are proprietary and/or non-proprietary versions of documents furnished to the NRC in connection with requests for generic and/or plant-specific review and approval.
In order to conform to the requirements of 10 CFR 2.790 of the Commission's regulations concerning the protection of proprietary information so submitted to the NRC, the information which is proprietary in the proprietary versions is contained within brackets, and where the proprietary information has been deleted in the non-proprietary versions, only the brackets remain (the information that was contained within the brackets in the proprietary versions having been deleted).
The justification for claiming the information so designated as proprietary is indicated in both versions by means of lower case letters (a) through (g) contained within parentheses located as a superscript immediately following the brackets enclosing each item of information being identified as proprietary or in the margin opposite such information. These lower case letters refer to the types of information Westinghouse customarily holds in confidence identified in Sections (4)(ii)(a) through (4)(ii)(g) of the affidavit accompanying this transmittal pursuant to 10 CFR 2.790(b)(1).
Copyright Notice The reports transmitted herewith each bear a Westinghouse copyright notice.
The NRC is permitted to make the number of copies of the information contained in these reports which are necessary for its internal use in connection with generic and plant-specific reviews and approvals as well as the issuance, denial, amendment, transfer, renewal, modification, suspension, revocation, or violation of a license, permit, order, or regulation subject to the requirements of 10 CFR 2.790 regarding restrictions on public disclosure to the extent such information has been identified as proprietary by Westinghouse, copyright protection not withstanding. With respect to the non-proprietary versions of these reports, the NRC is permitted to make the number of copies beyond those necessary for its internal use which are necessary in order to have one copy available for public viewing in the appropriate docket files in the public document room in Washington, DC and in local public document rooms as may be required by NRC regulations if the number of copies submitted is insufficient for this purpose. The NRC is not authorized to make copies for the personal use of members of the public who make use of the NRC public document rooms. Copies made by the NRC must include the copyright notice in all instances and the proprietary notice if the original was identified as proprietary.