ML19317E778

Summarizes Analysis & Rept of Possible Max Acceleration at Facility from Jocassee Reservoir Induced Seismicity

ML19317E778
Person / Time
Site:	Oconee
Issue date:	09/30/1976
From:	Fogle G, Long L, White R LAW ENGINEERING TESTING CO.
To:	Dail L DUKE POWER CO.
References
NUDOCS 7912180967
Download: ML19317E778 (5)

Text

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f I LAW ENGINEERING TESTING COMPANY Envoronmerstal Sciences. Geotechnical and Construction Serwces 2749 DELK ROAD, S.E./ M ARIETTA, GEORGIA 30067 (404) 9714005 September 30, 1976 Mr. L. C. Dail fp Qff/ g g 7 7 Civil / Environmental Division j ,f p Duke Power Company P. O. Box 2178 gI, g Charlotte, North Carolina 28242 -

Subject:

Possible Maxinum Acceleration at Oconee Nuclear Station from Jocassee Reservoir Induced Seismicity

Dear Mr. Dail:

As authorized on September 21, 1976 by Mr. R. S.

Bhatnagar, LO1 Engineering has completed an analysis and report of the possible maximum acceleration at the Oconee Nuclear Station due to seismicity in the Jocassee Reservoir area.

The maximum possible earthquake for the Lake Jocassee area has been calculated to be Mg = 5.6. .The details of this calculation and a description of the seismicity of the Lake Jocassee area can be found in the summary report of Jocassee flydro-Station Seismic Studies dated September 30, 1976.

This report presents a maximum acceleration value for the Oconee Nuclear Station due to maximum hypothetical earthquake at Lake Jocassee. In order to do this a magnitude versus in-tensity relationship will be presented, intensity attenuation between Lake Jocassee and Oconee Nuclear Station will be es-timated and an appropriate maximum acceleration for the plant will be determined using current intensity versus acceleration relaticnships.

The magnitude versus intensity relationship used in this study is the Gutenburg-Richter relationship, M = 2/3 Io + 1.

Figure 1 shows the relationship along with six earthquakes which serve to demonstrate the applicability of this relation-l ship in the southern Piedmont geologic province. The earth-quakes used are listed on the following page.

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Mr. L. C. Dail September 30, 1976 Page two Epicentral Intensity (Modified Mercalli Earthquake Magnitude Intensity) References Arvonia, Va. 5.75 VII Law Engineering internal December 22, earthquake files, 1875 Earthquake History of Virginia - Hooper, M.G.

and Bollinger, G.A.,

1971.

Union Co.,S.C. 5.45 VII Law Engineering internal January 1, earthquake files, 1913 Earthquake History of Virginia - Hooper, M.G.

and Bollinger, G.A.,

1971.

Lincoln Co., 4.5 V Intensity Survey of Ga., August Lincoln Co., Ga.

2, 1974 Earthquake. Benson, A.F., and Fogle, G.H.,

November 20, 1974.

Seneca, S.C. 3.6 IV Law Engineering internal July 13, 1971 earthquake reference files.

Jocassee, S.C. 3.2 IV Law Engineering internal November 25, earthquake reference 1975 files.

Jocassee, S.C. 2.35 II - III Law Engineering internal January 13, earthquake reference 1976 files.

Using this relationship, the Lake Jocassee area maximum hypothetical earthquake, ML = 5.6, is an epicentral intensity VII MM. It should be noted that both the Union County and Arvonia.

earthquakes have magnitudes similar to the Lake Jocassee hypothesized maximum earthquake and were both of epicentral intensity VII MM.

The intensity, at a distance of 18 km (the distance from Lake Jocassee to the Oconee Nuclear Station), from an epicentral taw anointmus restino commy B

Mr. L. C. Dail September 30, 1976 Page three inhensity VII MM at Jocassee, was found by attenuating the maximum intensity, according to intensity versus distance relations for other Piedmont Province earthquakes (see Figure 2). Two events of comparable magnitude and maximum epicentral intensity were used. These are the Union County, South Carolina earthquake of January 1, 1913 and the Arvonia, Virginia earthquake of December 22, 1875. The average distance in the Piedmont Province for the extent of each intensity contoured was estimated and plotted in Figure 2. The magnitudes of

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these 2 events are within one-quarter magnitude units of the max-imum hypothetical earthquake at Jocassce. Figure 2 indicates an attenuation of one half intensity unit at a distance of 18 km. Therefore, the intensity at 18 km for a maximum intensity VII MM ev.ent of magnitude ML = 5.6 in the Piedmont Province would be VI - VII MM.

Based upon an earthquake intensity of VI - VII MM (6.5) at the surface in the area of Ocone? Nuclear Station, we conclude that the maximum acceleration at the foundations on rock will be about 0.10 g. This value is at least as conservative as current intensity, acceleration relationships (Trifunac and Brady (1975), Neumann (1954), Hershberger (1956), and Gutenberg and Richter (1956)).

If you have any questions, please contact us.

Very truly yours, LAW ENGINEERING TESTING COMPANY fYh()fE NYY R. M. White Senior Geologist

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