ML13317A807
| ML13317A807 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/11/1982 |
| From: | Baskin K Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8201130309 | |
| Download: ML13317A807 (1) | |
Text
Southern California Edison Company P. O BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 K. P. BASKIN TELEPHONE MANAGER OF NUCLEAR ENGINEERING, January 11 1982 (213) 572-1401 SAFETY, AND LICENSING 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 September 4, 1981 Earthquake Records San Onofre Nuclear Generating Station Unit 1 As you are aware a magnitude 5.1 earthquake occurred in the Southern California area on September 4, 1981.
This event activated the SMA-3 strong motion accelerograph system installed at San Onofre Unit 1 indicating that the trigger threshold of O.Olg had been reached. At the request of members of the NRC Staff, this letter provides copies of the traces from these instruments and the results of our analyses of these traces. Included are the accelerograms (lateral, transverse and vertical) for the six instruments located at grade -10 feet, on the refueling deck, at the top of the sphere, at the loop B reactor coolant pump, at the pressurizer and at the loop B steam generator.
SCE has evaluated these records to determine the significance of this earthquake. As can be seen from the enclosed traces, the seismic motion in the records was barely above background except for the instrument located at the loop B steam generator. This instrument indicated levels on the order of 0.03g in the longitudinal (hydraulic snubber) direction, 0.02g in the vertical direction, and impact motion on the order of O.1g in the transverse (rigid seismic stop) direction.
It is concluded that this response was significantly influenced by the close proximity of the instrument to the seismic stop.
The impacting of the steam generator against the seismic stop, as intended, induces localized high accelerations that are not indicative of the overall response of the steam generator. Therefore, based on our review of these records, SCE has concluded that this earthquake was not significant relative to San Onofre Unit 1.
If you have any questions or require additional information on this matter, please let us know.
Very truly yours, Aacsa kdoi iioo' e- & i'L'
.o
PDRi ADOCK 0500020&
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