ML20128C313
| ML20128C313 | |
| Person / Time | |
|---|---|
| Site: | Vogtle, 05000426, 05000000, 05000427 |
| Issue date: | 04/22/1974 |
| From: | Harold Denton US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Moore V US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML19292B772 | List:
|
| References | |
| FOIA-84-624 NUDOCS 8505280251 | |
| Download: ML20128C313 (6) | |
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UNITED STATES f]
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ATOMIC ENERGY COMMISSION l
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.tF1 00?S7' V. A. Moore, Assistant Director for LWRs, Group 2, L SER INPUT PLANT NAME: Vogtle Units 1, 2, 3, and 4 LICENSING STAGE: CP DOCKET NUMBER: 50-424, 425, 426 and 427 RESPONSIBLE BRANCH: Lim 2 REQUESTED COMPLETION DATE: 4/22/74 APPLICANTS RESPONSE DATE NECESSARY FOR NEXT ACTION PLANNED ON PROJECT: NA DESCRIPTION OF RESPONSE: NA REVIEW STATUS:
Attached is our input to the Geology and Foundation Engineering sections of the Safety Evaluation Report for the proposed Vogtle Nuclear Power Plant. The seismology input will follow in a few days.
W Harold R. Denton, Assistant Director for Site Safety Directorate of Licensing
Enclosure:
As stated cc: w/o enclosure A. Giambusso W. Mcdonald J. Panzarella SS BCs cc: w/ enclosure S. Hanauer R. Klecker J. Hendrie D. Eisenhut W. Gat: mill J. Carter K. Kniel S. Varga L. Crocker A. Cardone A. Kenneke 8505280251 841015 PDR FOIA SHOLLYB4-624 PDR
p GEOLOGY AND FOUNDATION ENGINEERING V0GTLE SER INPUT DOCKET NO. 50-424, 42,5, 426, 427 2.5 Geology and Seismology The geological and seismological aspects of the proposed Vogtle site have been reviewed by the staff. We have not received a final report from our advisors in the U.S. Geological Survey (USGS) regarding their evaluation of the geology and seismology of the site area.
However, we have received a draft report from U.S.G.S.
It is our conclusion and that of our advisors that the geological and seismological investigations and evalua'tions are acceptable and that the applicants proposed earthquake design bases of 0.12g for the operating basis earthquake and 0.20g for the safe shutdown earthquake represent appropriate conservative values.
2.5.1 Regional _ Geology The site. is located in the Atlantic Coastal Plain Physiographic Province, approximately 26 miles southeast of Augusta, Georgia, on the eastern margin of the Tif ton upland and adjacent to the Savannah River.
The plant will be underlain by Coastal Plain sediments consisting of from 800 to 1000 feet of predominantly clays, sands, limestone, and mari, ranging in age from
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.; Cretaceous to Recent. An apparently downfaulted block of fbi Triassic red beds underlie the Coastal ce-low sediments.
Igneous and metamorphic rocks typical of the Piedmont rocks in turn underlie the Triassic red beds.
Adjacent to -and northwest of the Atlantic Coastal Plain Province is the Piedmont Province. The boundary between the two provinces is known as the Fall Line which.is approximately 25 miles northwest.of the site. Rocks that characterize the Piedmont disappear beneath the Coastal Plain sediments at the Fall Line, but no structurally significant boundary exists.
The deeply buried structural geology beneath the Coastal. Plain, is not well known. Of particular significance to any site in the Southeastern United States is the tectonic feature that-is responsible for the seismic activity in the vicinity of Charleston, South Carolina, including the very large 1886-Charleston earthquake. This activity is believed to be asacciated with a specific structural anomaly that is confined-to the area in the vicinity of Charleston. Evidence, though limited, seems to indicate that the numerous earthquakes that have occurred in the Charleston vicinity are localized along the deepest part of the northwest trending Southeast Georgia Embayment.
The Charleston area is approximately 100 miles east
m southeastoof the site.
The site lies within a northeast trending Triassic Basin approximately 1 mile southeast of-the northeast trending prob'able fault that forms the northern boundary of the Triassic Basin.' We and our U.S.G.S. advisors are of'the opinion th.at any faulting associated with this Triassic Basin does not appear to have been tectonicaJ1y active since Cretaceous time. Furthermore, there are no other
' identifiable faults or other young geologic structures in the area that might be expected to localize seismicity in the inmediate. vicinity. of the site.
i 2.5.3 Site Geology Solutioning of a near surface limestone strata has produced surface depressions throughout the site area. To assure adequate foundation conditions to support the plant structures,
- the applicant will remove all strata including the soluble limestone strata down to firm, hard clay-marl at elevation 130. ' Select sand backfill or lean concrete will be placed from the top of the firm clay-marl bearing strata up to the design elevation of the Category I structures.
There is a dip reversal or flexure in the clay-marl bearing
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_4-strata' illustrated in figure 2.5-10 of the PSAR, which was the j
subject of much-investigation and discussion between the.
' applicant and the staff. The possibility that it was a fault controlled feature, namely the probable northern border fault uif the Triassic Basin,1was considered. Numerous holes were
. drilled to determine-its character. Since the assumed border fault would have to' be down-thrown towards the southeast, the
. fact that the flexure in the earl slopes in the opposite north-westerly direction precludes a genetic relationship.
.2.5.4 Foundation Enaineerina Although a large number-of borings were drilled over a large area during the exploration work, relatively few of. the borings penetrated the clay-marl bearing stratum. -Inasmuch as this formation is in part calcareous and contains many limestone lenses, the distinct possibility' existed that
-undetected solution voids or channels could occur directly beneath the critical.and heavy reactor structures. The only rational method for investigating this possibility was to.
put down more borings and conduct more downhole geophysical and hydraulic pressure tests within the marl bearing stratum aat the specific locations of these nuclear structures.
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-S-The Georgia Power Company performed a substantial amount of additional borings and downhole testing to firm up the essential engineering properties of this bearing stratum.
Twelve additional core borings were drilled at the specific locations of reactor units 1, 2, 3 and 4 and penetrated completely through the marl stratum. Generally, good core recovery (90 to 99 percent) was experienced with these i
borings indicating minimal or no solutioning of the formation. Additional confirmation was secured by hydraulic pressure tests conducted in several of these borings with
.I practically no water loss.
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