ML20024E220
| ML20024E220 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 08/01/1983 |
| From: | Rolonda Jackson Office of Nuclear Reactor Regulation |
| To: | Adensam E Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8308090815 | |
| Download: ML20024E220 (2) | |
Text
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NUCLEAR REGULATORY COMMISSION J
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AUG 011983 1
MEMORANDUM FOR:
Elinor Adensam, Chief f.icensing Branch No. 4, DL FROM:
Robert E. Jackson, Chief Geosciences Branch, DE
SUBJECT:
GEOSCIENCES BRANCH REVIEW 0F V. C. SUMMER SEISMIC CORFIRMATORY PROGRAM We have reviewed the following documents submitted by the Licensees in partial satisfaction of License Condition 2.C (25) of the Virgil C.
Summer Nuclear Station Operating License: Report I (submitted February 1, 1983); Addendum to Report I (March 9, 1983); and Responses to Staff Questions (June 22,1983). A report describing in detail the Licensees' test program and our review is currently being prepared by Dr. Jerry King of the Geosciences Branch. The purpose of this memorandum is to notify the Division of Licensing as soon as.possible of the results of our review.
As discussed in the summary section of Report I and reiterated in the June 22, 1983 transmittal letter, the Licentees' po.;ition is that the
-envelope spectrum obtained_from accelerograms recorded on the USGS accelerograph pad at the Monticello dam abutment is inappropriate to represent ground motion in the nuclear plant structures. On the basis of their test results, the Licensees have concluded that their ACRS commitment to review equipment and components for a magnitude M 4.5 earthquake will cover the review necessary to satisfy the ASLB kicensing.
condition, because the ACRS criterion implies a higher level of ground motion at virtually all frequencies than the appropriately reduced envelope spectra, and is therefore more conservative.
On the basis of our review, we agree that a reduced envelope spectrum may be used to represent the foundation motion of the nuclear plant structures. However, we do not agree that the ACRS criterion is more conservative than the appropriately reduced envelope spectra, for periods less than about.05 seconds (frequencies greater than 20 Hz).
Specifically, we have concluded that the following descriptions of the foundation motion will be acceptable for satisfying the ASLB license condition:
For the Auxiliary Building and other nuclear plant structures founded on rock, the envelope of (1) the response spectrum obtained from the 50th percentile spectral modulus ratios for the USGS accelerograph site
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AUG 011983
-(curve P2 on Figure 3A.1 of the Licensees' Response to Staff Questions) and (2) the average response spectrum obtained from the 50th percentile spectral modulus ratios for the USGS accelerograph site and all monitored free-field sites (the lowest curve on Figures 3A.5 and 3A.8) is an acceptable criterion for satisfaction of the license conditiori.
For the Diesel Generator Building and other nuclear plant structures founded on caissons, an acceptable criterion is the envelope of (1) the response-spectrum obt'ained from the 50th percentile spectral modulus ratios for the USGS giccelerograph site (curve P2 on Figure 3A.2) and (2) the average response spectrum obtained from the 50th percentile spectral modulus ratios for the USGS accelerograph site and all monitored free-field sites (the lowest curve on Figures 3A.6 and 3A.9).
FortheServiceWaterPumphouse(foundedonsoil),anacceptable criterion is the response spectrum obtained from the 50th percentile spectral modulus ratios for all monitored free-field sites (the lowest curves on Figures 3A.7 and 3A.10), modified as follows in the period range of.01 to.035 seconds: at.01 seconds, a multiplicative factor of 1.0 is to be applied to the response spectrum, increasing linearly with period to a factor of 1.6 at.02 seconds, and decreasing linearly with period to a factor of 1.0 at.035' seconds.
k&V SU Robert E. J ckson Chief Geosciences Br'anch, DE cc:
J. Knight T. Novak G. Lear V. Noonan P. T. Kuo S. B.-Kim L. Heller J. Chen J. Hopkins L