ML13324A435
| ML13324A435 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/17/1984 |
| From: | Medford M Southern California Edison Co |
| To: | Paulson W Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13324A436 | List: |
| References | |
| TASK-03-02, TASK-03-04.A, TASK-3-2, TASK-3-4.A, TASK-RR NUDOCS 8409190098 | |
| Download: ML13324A435 (2) | |
Text
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770 M.O. MEDFORD Spebr7 OATELEPHONE MANAGER. NUCLEAR LICENSING September 17, 1984 572-1749 Director, Office of Nuclear Reactor Regulation Attention: Mr. W. A. Paulson, Acting 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 Topics:
111-2, Wind' and Tornado Loadings III-4.A, Tornado Missiles San Onofre Nuclear Generating Station Unit 1 Our letter of February 24, 1984 provided you with a schedule for the submittal of a site-specific tornado hazards analysis for San Onofre Unit 1.
We also gave a brief summary of the plan of action to develop the site-specific tornado hazard. In response to our commitment, enclosed is the report entitled "Tornado Hazard Analysis Relating to SEP Topic 111-2 at San Onofre Unit 1" prepared by Cygna Energy Services.
As stated in the enclosed report, the tornado hazard for San Onofre Unit 1 ranges from 59 mph with an occurrence qrobability of 10-4 per year to 183 mph with an occurrence probability of 10-' per year. It is our plan to utilize the results of the enclosed report to perform an evaluation of San Onofre Unit 1 to demonstrate that there is adequate resistance for smaller tornado loadings and that the risk associated with larger tornado loadings is acceptable. The evaluation will encompass structures and systems identified to be necessary to assure:
(1) The integrity of the reactor coolant pressure boundary, (2) The capability to shutdown the reactor and maintain it in a safe condition, and (3) The capability to prevent accidents which could cause offsite exposure in excess of the guidelines in 10 CFR 100.
The evaluation will determine the scope of modifications necessary at each tornado wind speed identified in the enclosed report. Based upon the results of the evaluation, a design basis tornado event will be determined by a cost/safety benefit methodology. The conclusion will identify a scope of conceptual modifications, and provide the schedule for implementation of any modifications in accordance with the methodology of the Integrated Living Schedule.
6409190098 840917 PDR ADOCK 05000206 P
Mr. W.
September 17, 1984 The completion of the evaluation discussed above is currently scheduled for July 1, 1985. This schedule is contingent upon an October, 1984 startup of San Onofre Unit 1 from the current outage. This is due to the need to utilize the civil/structural engineering personnel, currently working on the seismic return-to-service effort, to assist in the performance of the tornado design evaluation.
If you have any questions regarding the above discussed plan to resolve these SEP topics, please let me know.
Very truly yours, Enclosure