ML20039F980
| ML20039F980 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/14/1981 |
| From: | Youngblood B Office of Nuclear Reactor Regulation |
| To: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| References | |
| NUDOCS 8201150058 | |
| Download: ML20039F980 (3) | |
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LB#1 RDG TERA DEisenhut NRC/PDR BJYoungblood L/PDR Docket No.: 50-395 WKane NSIC MRushbrook TIC g
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RVollmer RHartfield, MPA Q/[,,N RMattson Mr. T. C. Nichols, Jr.
s Vice President & Group Executive f
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'69 JKramer Columbia, South Carolina 29218 OIE (3) sigfjgJg South Carolina Electric & Gas Company Post Office Box 764 0 ELD i
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Dear Mr. Nichols:
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Subject:
Request for Additional Information - Virgil C. Sum
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Nuclear Station In 1980 and 1981 earthquake swarms occurred near Mammoth Lakes, California.
The staff recently learned of the existence of a data set for these events which could be used to calculate a site specific spectra for the Sucner site for magnitude 4 to 5 reservoir induced events (RIS). The California Division of Mines and Geology (CDMG), the USGS; and Dr. W. Peppin and H. Somerville now with URS/Bluce and Associates, were seismically monitoring these events.
We had previously asked your representatives to examine magitude 4 to 5 Hamoth Lakes events with source-to-site distances up to 10 km for record-ing sites on rock foundations. Your response was provided in a report
" Description of Seismometric Data Recorded at Hammoth Lakes, California",
submitted November 19, 1981.
In telephone conversations on November 24 and 25 with your representatives, the staff discussed additional calculations needed to complete our review. That information is identified in the enclosure to this letter.
If your require any clarification of these matters please contact the NRC-staff's project canager.
eigiisGfgoed by B. J. Youngblood B. J. Youngblood, Chief Licensing Branch No.1 Division of Licensing
Enclosure:
"The reporting an/or recordkeeping requirements As Stated contained in this letter affect fewer than ten responsents; therefore, OMB clearance is not cc: See next page required under P.L.95-511."
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Mr. T. C. Nichols, Jr.
Vice President & Group Executive Nuclear Operations South Carolina Electric & Gas Company P. O. Box 764 Columbia, South Carolina 29218 cc: Mr. Henry-Cyrus, Senior Vice'. President South Carolina Public Service Authority 223 North Live Oak Drive Moncks Corner, South Carolina 29461 J. B. Knotts, Jr., Esq.
Debevoise_& Ljberman 120017th Stree_t, N. W.
Washington, D. C.
20036 Mr. Mark B. Whitaker, Jr.
Group Manager - Nuclear Engineering & Licensing South Carolina Electric & Gas Company P. O. Box 764 Columbia, South Carolina 29218 Mr. Brett Allen Bursey Route 1, Box 93C Little Mountain, South Carolina 29076 Resident Inspector / Summer NPS c/o U. S. NRC Route 1, Box 64 Jenkinsville, South Carolina 29065 Dr. John Ruoff Post Office Box 96 Jenkinsville, South Carolina 29065 4
ENCLOSURE 7 -.
R5 UEST FOR ADDITIONAL INFORMATION 361.25 A.
Using all appropriate records from the Mammoth Lake sequence between magnitude 4.0 and 5.0 compute site specific response spectra for a nearby magnitude 4.5 event recorded at site conditions most similar to the Summer site.
If appropriate and available include data collected by the USGS and CDMG.
Show all response spectra used and the computed 50th and 84th percentiles at the dampings of interest. Tabulate.apicentral locations, depths and hypocentral distances for 'all records used.
Discuss the applicability of these records to the conditions at the Summer site in terms of depth, hypocentral distances, knowisource parameters and tectonic conditions.
B.
If not already included, discuss the appropriateness of the McGee site and the effect of the everlying soil upon the response spectra.
C.
Examine and if applicable compare response spectra from earthquakes recorded at Monticello with those at Mammoth Lakes in the magnitude and distance range that are most similar.
Include high frequency ground motion (greater than 20 Hz) in this comparison.
Discuss the bearing this comparison has upon the use of Mammoth Lake data to estimate ground motion at Monticello.
D.
Examine and if applicable show site specific spectra at several magnitude ranges to demonstrate the changes in spectral level and shape as a function of increasing event magnitude.
E.
Discuss the use of the low pass filter used and its effect upon higher frequencies and peak ground accelerations.
Show response spectra utilizing different low filters in the 20 to 50 Hz range. Try to include as many high frequencies as possible in the computed site specific spectra.
F.
Examine and if applicable compare computed site specific spectra with spectra of similar event sizes and distances recorded at other site conditions at Mammoth Lakes.
G.
Compare site specific spectra computed from Mammoth Lakes data r
to the applicant's estimated RIS and SSE spectra and discuss the significance of any exceedance in the different frequency ranges.
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