ML20064G304
| ML20064G304 | |
| Person / Time | |
|---|---|
| Site: | Marble Hill |
| Issue date: | 11/21/1978 |
| From: | Peterson R PSI ENERGY, INC. A/K/A PUBLIC SERVICE CO. OF INDIANA |
| To: | Schwibinz E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20064G307 | List: |
| References | |
| NUDOCS 7812080202 | |
| Download: ML20064G304 (1) | |
Text
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Mr. Roger S. Boyd, Director Division of Proj ect Manage =ent
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Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Co mission I
Washington, DC 20555
Dear Mr. Boyd:
s In the Matter of the Application of the
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Docket Nos. 50-32]___,,
!ennessee Valley Authority
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' 3DZ328 30-390 50-391 50-438 50-439 Encicsed are 40 copies of TVA's responses to ycur request for additional information on the seismic design bases for the Sequoyah, Watts Ear, and 3ellefonte Nuclear Plants dated October 4, 1973. We strengly believe that this information, together with our reports entitled " Justification of the Seismic Design Criteria Used for the Sequoyab, Watts Sar, and Bellefonte Nuclear Plants, Phase I and II," clearly demonstrate that the seismic design bases used at these facilities are conservative.
Briefly, our Phase I and II reports provided the following information to justify the seismic design bases at the subject plants.
1.
Evaluation of the Giles County earthquake intensity to show that it is conservatively a 3DNII-VIII instead of 10N!1I.
2.
The intensity rating for the Giles County earthquake is soil biased.
historical data of the Giles County earthquake and worldwide data show the intensity is two to three units less on rock than en soil. All subj ect plant sites are rock sites.
3.
The Murphy-O'Brien (CSC) intensity-acceleration relationship is the more appropriate. This results in a =aximum acceleration of 0.15g for a M}f7III.
4 Earthquake ground motion reduces with depth. No etedit is taken for ground motion reduction with depth.
3.
Develo; ent of atte specific SSE respense spectra frca strong
=ction records of appropriate =agnitude and distance. A cange of =agnitudes from 5.3 to 6.3 was used. We believe this tagnitude range to be conservative since the Giles County earthquake is
,g-esti=ated to have been fro: 5.2 to 5.5.
Forty percent of the 0(
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data used was for earthquakes with a magni. ie greater than that esti=ated for the Giles County earthquake. Comparison of the site specific response spectra with the plants' design spectra justify:the plants' seismic design.
6.
Development of site specific SSE response spectra based on paraneters othcr than intensity. This study was performed by our consultants, Weston Geophysical Corporation.
It utilizes data available in the eastern United States along with western United States data. A top of rock acceleration of 0.08 was determined.
The infor=ation enclosed provides additional information on the sensitivity of the site specific SSE response spectra developed frem strong motion records. Also, the probabilities of exceeding the plants' SSE design spectra compared to Phipps Send Nuclear Plant and i
to the site specific response spectra developed using strong motion records are presented along with a probabilistic analysis to justify the 03E.
You indicated in your letter of January 13, 1978, that because of the actual procedures utilized for the subject plants, it =1ght be possible to show that the plants, as designed, are adequate by taking into account. specific site conditions, earthquake sagnitude, and distance to the earthquake source. We believe that-the additional-infor=ation enclosed, along with our Phase I and II reports, addresses these considerations in detail and together do show that the plants, as designed, adequately ensure the health and safety of-the public.
Very truly yours, i
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.s J. E. Gilleland j
,s Assistant Manager of Power Enclosure (10) 1 1 4..,.g
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