ML13317A705
| ML13317A705 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 10/19/1981 |
| From: | Moody W SOUTHERN CALIFORNIA EDISON CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-06, TASK-3-6, TASK-RR NUDOCS 8110220437 | |
| Download: ML13317A705 (3) | |
Text
e9 Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 W. C. MOODY TELEPHONES MANAGER, NUCLEAR LICENSING October 19, 1981 (213) 572-1817 (213) 572-1806 Director, Office of Nuclear Reactor Regulation Attention: D. M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Gentlemen:
Subject:
Docket No. 50-206 SEP Topic 111-6 Seismic Design Considerations San Onofre Nuclear Generating Station Unit 1 In a meeting with the NRC Staff on October 15, 1981, SCE and its consultants discussed the seismic withstand capability of the north turbine building extension. This discussion included a description of the structure and a summary of analyses which were previously submitted to the NRC. In addition, recent analyses of the column anchorages were discussed in detail.
A brief summary of the October 15 meeting agenda and a copy of the meeting handouts are included as Enclosure 1. This enclosure also includes information pertaining to a question raised at the meeting. provides a detailed description of the analysis of the capacity of the column anchorages. This analysis supersedes the analysis which was discussed in our August 11, 1981 and October 6, 1981 letters. Our October 6 letter indicated that we expected the columns to be fully yielded before the full strong axis plastic moment (F Zx) could be developed in the columns. This contention was based upon the limiting effect of weak axis bending.and axial loads. Based upon subsequent dis cussions with the NRC Staff, we decided to review our previous calculations to determine whether or not certain factors that were conservatively neglected in our August 11 and October 6 letters could be accounted for.
As a result of this review, an analysis was performed taking into account the resisting forces applied by the concrete floor slab (located approxi mately two feet above the column base plates).
This analysis conservatively assumes that the columns are capable of developing their full plastic moment.
8110220437 CIO19 PDR ADOCK 05000206 P
D
Mr. D. October 19, 1981 The computed results of this analysis are described in Enclosure 2.
This analysis demonstrates that the column anchorages will remain within their elastic limit even if the columns were capable of developing the full plastic moment.
In addition to the information presented at the October 15 meeting, Enclosure 2 provides information in response to questions raised during the meeting regarding the anchorage capacity. Specifically, the potential for formation of gaps at the column-slab interface and for slab buckling are discussed. It should also be noted that Enclosure 2 includes two differences from information discussed at the October 15 meeting.
- 1.. The computed result of the combined stresses from the strain compatability calculation shown in Table 2 has changed from 0.46 to 0.60. This value reflects the checked calculations. However, this change does not alter the conclusions as reflected in Section II.B of.
.2. The discussion of the potential for formation of a gap at the column-slab interface has been revised to not only discuss relative stiffnesses, but also to discuss the effect of a potential gap on the anchor bolt strength.
In addition, the discussion of stiffnesses is based on values for the footing stiffnesses which more accurately reflect the San Onofre Unit 1 site conditions.
Based on all of the information discussed at the October 15 meeting, as supplemented by the information in Enclosure 2 to this letter, it is concluded that the north turbine building extension is capable of withstanding an earthquake well in excess of O.5g Housner.
Mr. D.
October 19, 1981 If you have any additional questions on this matter, please let me know.
Subscribed on thisf day of
/
1981.
Very truly yours, SOUTHERN CALIFORNIA EDISON COMPANY By W. C. MOODY Manager, Nuclear Licensing Subscribe and swora to before me on this /ffday of ff
,e/
, 1981 Nt Pub ic in and for the County AGNES CRABTREE NOTARY PUBLIC - CALIFORNIA PRINCIPAL OFFICE IN LOS ANGELE COUNTY My Commissin Exp. Aug.27,1982 of Los Angeles, State of California Enclosures