ML19350A602
| ML19350A602 | |
| Person / Time | |
|---|---|
| Site: | Hatch, Vogtle  |
| Issue date: | 03/02/1981 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | John Miller GEORGIA POWER CO. |
| References | |
| NUDOCS 8103160560 | |
| Download: ML19350A602 (1) | |
Text
.
s neo<,,o,,
?/
UNITED STATES g' % 7, -
g NUCLEAR REGULATORY COMMISSION
.~ s REGION 11 o
101 MARIETTA ST., N.W.. SUITE 3100 j"
ATLANTA, G EORGIA 30303 c3 j
%y MAR 2191
/
v
\\
In Reply Refer To:
RII:JP0 8
50-321. 50-366 m
oj 6
T
<T(FT24,50-42b gS '
1/
, L.
4
\\
Georgia Power Ccmpany c9 ATTN:
J. H. Miller, Jr.
Executive Vice President 270 Peachtree Street Atlanta, GA 30303 Gentlemen:
The enclosed IE Circular No. 81-03 is forwarded for your information. No written response to this Circular is required. If you have any questions related i
to this matter, please contact this office.
Sincerely, 4
~(~
~
)
l-James P. O'Rei)J Director
Enclosures:
1.
.IE Circular No. 81-03 2.
' List of Recently. issued IE Circulars cc w/ encl:
M. Manry, Plant Manager.
C. E. Belflower, Site QA Supervisor W. A.-Widner,-Vice President and-General Manager-Nuclear Generation K. M. Gillespie,. Construction. Project Manager E. D. Groover, QA Site Supervisor D. E. Dutton, Project General Manager L
8108ieo56D-
- Q
SSINS 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 L
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 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 of magnetic tape triaxial accelograph recorders; three sets o' 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 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 the1only instrument believed to produce reliable data.
[
On January 24, 1980, an earthquake measuring 5.5 on the Richter Scale occurred l
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 l
Seco Nuclear Plant, located approximately 45 miles northeast of the earth-quake area, reported no physical damage,-although plant personnel felt slight builcing motion.
{
Rancho Seco was shutdown for refueling during these earthquakes.
During this l-period, the' electrical seismic' instrumentation.:ystem was inoperable-because
. portions of the system were out-for calibration.
For the other instruments, power was not being supplied due to electrical cable problems. Whether the s
L
. seismic instrumentat on would have activated or not is unclear because the i
~
U.S. Geological Survey equipment.close to the site did not trigger.
Records.
from a passive recorder showed peak accelerations from 1 to 1.5 g and 0.1 g l.
L
{
.n
SSINS 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 Description 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 i
the ep center, 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, 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 of magnetic tape triaxial accelcgraph 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 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 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 i'uclear 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 l
portions of the system were out for calibration.
For the other instruments, l
power was not being supplied due to electrical cable roblems.
Whether the seismi: instrumentation would have a l
U.S. Geological Survey equipment clo..
c
=. -
l from a passive recorder showed peak 5
l DUPLICATE DOCUMENT 3
Entire document previously 4
entered into system under:
h ANO No. of pages:
9 x
_x x