ML19350B300
| ML19350B300 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 03/02/1981 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Tallman W PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| References | |
| NUDOCS 8103200228 | |
| Download: ML19350B300 (1) | |
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'o UNITED STATES
[B (g"S, NUCLEAR REGULATORY COMMISSION r.//ve $
REGION I o, Efd / 8, 631 PARK AVENUE
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6 tNG oF PRUSSIA, PENNSYLVANIA 19406
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o NM Docket Nos. 50-443 MAR 2 1981 s
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Public Service Company of New Hampshire
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%.Ic,P%,[yIS ATTN: Mr. W. C. Tallman Chairman and Chief Executive Officer S7 i
1000 Elm Street g'e &
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Manchester, New Hampshire 03105 i
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j (n Gentlemen:
The encloseri IE Circular No. 81-03, " Inoperable Seismic Monitoring Information" is forwarded to you information.
No written response is required.
If ycu desire additional information regarding this matter, please contact this office.
Sincerely, el Boyce H. Grier Director
Enclosures:
1.
IE Circular No. 81-03 2.
List of Recently Issued IE Circulars CONTACT:
S. D. Ebneter (215-337-5266) cc w/encis:
John DeVincentis, Project Manager OM 1910320 9
SSINS No.: 6330 Accession No.:
3005220271 IEC 81-03 UNITED STATES NUCLEAR REGULATORY CO.v3.ISSICN OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 2, 1931 IE Circular No. 81-03: INOPERABLE SEISMIC MONITORING INSTRUMENTATION Description of Circumstances:
On November 8,1980, an earthquake occcred off the coast near Eureka, California.
The earthquake was reported to have a magnitude of 7.0 on the Richter Scale at the epicenter, approximately 25 to 75 miles from the Humboldt Bay Power Plant facility. 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 posts, various chimneys that were knocked down, e:e highway overpass that collapsed, and unspecified damage that occurred at tv.' pulp mills.
There were three potentially different sources of plant response data: three sets of magnetic tape triaxial accelograph recorders; three sets of triaxial filrn recorders (passive device); and one set of triaxial response spectrum recorders (passive device). A review of the records from these instruments indicated the following: the magnetic tape triaxial recorders did not produce useful records due to a degraded low-voltage power supply in the recording syste :
(p-eviously 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 believed to produce reliable data.
On January 24, 1980, an earthquake measuing 5.5 on the Richter Scale occurred about 10 miles north of Lawrence Livermve.Liboratory (near San Francisco, California).
Numerous aftershocks also occurred with one measuring 5.2 on January 26. The d mage 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.
Rancho Seco was shutdown for refueling during these earthquakes. During this period, the electrical seismic. instrumentation system was inoperable because portions of the system were out for calibration.
For the other instruments, pon r was not being supplied due te '
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seismic instrumentation would have U.S. Geological Survey equipment cl DUPLICATE DOCUMENT from a passive recorder showed pea Entire docurent previously entered into systern under:
xNo _S00922 027/
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