ML19345G185
| ML19345G185 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 03/02/1981 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Papay L SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| NUDOCS 8103170002 | |
| Download: ML19345G185 (1) | |
Text
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[p rac,,q'o UNITED STATES
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'j NUCLEAR REGULATORY COMMISSION r.
. c REGION V o '-
1990 N. CAL *!ORNI A BOULEVARD 4/
e SulTE 202, WALNUT CREEK PLAZA
- ,,e a WALNUT CREEK, CALIFORNIA 94506 March 2, 1981 Docket Ncs. 50-206, 50-361, 50-362 k*f*$ 8
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Southern California Edison Company 3
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P. O. Box 800 e
2244 Walnut Grove Avenue g
Rosemead, California 917 0 g
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Attention:
Dr. L. T. Papay, Vice President Advanced Engineering Gentlemen:
The enclosed circular is forwarded for your infonnation.
No written response to this circular is required.
If you have any questions related to this matter, please contact this office.
~incerely, i
W R. H.
1elken Director
Enclosure:
1.
IE Circular No. 81-03 2.
List of IE Information Notice Recently Issued cc w/ enclosures:
J. M. Curran, SCE R. Dietch, SCE
SSINS No.: 6830 Accession No.:
8008220271 IEC 81-03 UNITED STATES NUCLEAR REGUtATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 2, 1981 IE Circular No. 81-03: IN0PERABLE SEISMIC MONITORING INSTRUMENTATION Description of Circumstances:
On November 8,1980, an earthquake occurred off the coast near Eureka, California.
The earthquake was reported to h.ve a magnitude of 7.0 on the Richter Scale at the epicenter, approximately 25 to 75 miles from the Humboldt Bay Power Plant facili ty.
There were 12 separate seismic events above a magnitude of 3.5 that occurred within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the earthquake, the largest event measuring 5.2.
Reported damage to structures included several houses that were moved off supporting poc'.3, various chimneys that were knocked down, one highway overpass that collapsed, and unspecified damage that occurred at two pulp mills.
There were three potentially different sources of plant response data: three sets oT magnetic tape triaxial accelograph recorders; three sets of triaxial film recorders (passive device); and one set of triaxial response spectrum recorders (passivedevice). A review of the records from these instruments indicat.ed the following: the magnetic tape triaxial recorders did not produce useful records due to a degraded low-voltage power supply in the recording systen (previously scheduled for routine servicing one week after the earthquake);
a buildup of dirt and dust appeared to make inoperable six of the nine film recorders (the readings from the other three are considered highly unreliable and were not obtained from the same set of triaxial recorders); the triaxial response spectrum recorder was the only instrument belieyed to produce reliable data.
On January 24, 1980, an earthquake measuring 5.5 on the Richter Scale occurred about 10 miles north of Lawrence Livermore Laboratory (near San Francisco, California).
Numerous aftershocks also occurred with one measuring 5.2 on January 26.
The damage to civil structures was considered minor.
Rancho Seco Nuclear Plant, located approximately 45 miles northeast of the earth-quake area, reported no physical damage, although plant personnel felt slight building motion.
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these earthquakes.
During this
'l system was inoperable because Sn.
For the other instruments, I cable Droblems. Whether the 5
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