ML13317A878

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Forwards Seismic Design Considerations Rept, Analysis of 2/3-g Housner Reanalysis Design Spectrum for San Onofre Nuclear Operating Station
ML13317A878
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 02/24/1982
From: Baskin K
Southern California Edison Co
To: Crutchfield D
Office of Nuclear Reactor Regulation
Shared Package
ML13310A231 List:
References
TASK-03-06, TASK-3-6, TASK-RR NUDOCS 8202260264
Download: ML13317A878 (2)


Text

Southern California Edison Company P. 0.

BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 K. P. BASKIN TELEPHONE MANAGER OF NUCLEAR ENGINEERING, (213) 572-1401 SAFETY, AND LICENSING February 24, 1982 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 By letter dated May 11, 1981, we indicated our intention to proceed with the seismic reevaluation of San Onofre Unit 1 based on the 0.67g Housner response spectrum. On February 16, 1982, SCE and its consultants met with the NRC Staff to provide the staff with additional information pertaining to the appropriate response spectrum for the San Onofre site. The purpose of this letter is to document that information and to reaffirm our conclusion that the 0.67g Housner response spectrum is appropriately conservative for the seismic reevaluation of San Onofre Unit 1.

The enclosed report presents all recent relevant close-in strong motion data and studies and provides comparisons of those data and studies to the 0.67g Housner reanalysis spectrum. Those comparisons include recent instrumental data, calculated instrumental values, regulatory instrumental spectra, equal probability instrumental spectra, California dam design practice and relevant information for other SEP plants. Based on those comparisons, it is concluded that the reanalysis spectrum exceeds the 84th percentile of comparable actual and calculated earthquake spectra.

Furthermore, the annual probability of exceeding the reanalysis spectrum is on the order of 10-or less. Finally, the seismic criteria for San Onofre Unit 1 are at least as conservative as those for other SEP plants and there is greater confidence in the San Onofre criteria.

Based on the weight of the information presented in the enclosed report, it is concluded that the 0.67g Housner response spectrum is an 8202260264 820224 eDR ADOCK 05000206I PDR

Mr. D. M. Crutchfield

-2 appropriately conservative spectra for the San Onofre site. Therefore, use of this response spectrum for the seismic reevaluation of San Onofre Unit 1 is conservative.

If you have any questions on this matter or require additional information, please let us know.

Very truly yours, Enclosure