ML19350B258
| ML19350B258 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 03/02/1981 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| References | |
| NUDOCS 8103200182 | |
| Download: ML19350B258 (1) | |
Text
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o UNITED STATES 8
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REGION I Q'
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Baltimore Gas and Electric Company l 'J ATTN: Mr. A. E. Lundvall, Jr.
'"', R 131981 m s Vice President, Supply (6 m m s. m. um,cnk * * *
,Qg P. O. Box 1475 Baltimore, Maryland 21203 s
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Gentlemen; The enclosed IE Circular No. 31-03, " Inoperable Seismic Monitoring Information" is forwarded to you informaticr..
No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, l
.g
/' Soyce H. Grier Director
Enclosures:
1.
IE Circular No. 81-03 2.
. List of.Recencly Issued IE Circulars CONTACT:
S. D. E'enater (215-337-5256) cc w/encls:
R. M. Douglas, Manager, Quality Assurance L. B. Russell,. Plant Superintendent-T. Sydnor', General Supervisor, Operations QA R. C. l. Olson, Principal Engineer
-J. A. Tiern=n, Manager, Nuclear Power
.R. E. Denton, General Supervisor, Training.and Technical Services
-8103200ltA
SSZNS No.: 6830 Accession No.:
8008220271 IEC 81-03 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 2, 1981 IE Circular No. 81-03: INOPERABLE SEISMIC MONITORING INSTRUMENTATION Descriotion of Circumstances:
On November 8, 1980, an earthquake occurred 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 iown, one highway overpass that collapsed, and unspecified damage that occurret at two pulp mills.
There were three potentially different sources of plant response data: three sets of magnetic tape triaxial accelograph recorders; three sets of triaxial film 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 system (previously schedaled 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 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 measurir.g 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.
Rancho Secc las 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.
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power was not being supplied due to elec TT seismic instrumentation would have activ U.S. Geological Survey equipment close t'-
DUPLICATE DOCUMENT from a passive recorder showed peak acce entered into system under:
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