ML19309C398
| ML19309C398 | |
| Person / Time | |
|---|---|
| Site: | Phipps Bend  |
| Issue date: | 04/01/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004080553 | |
| Download: ML19309C398 (4) | |
Text
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TENNESSEE VALLEY AUTHCP:TY cur e:c.cc4 re mtsser rent 400 Chestnut Street Tower II April 1, 1980 Mr. liarold R.-Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Denton:
In the Matter of the Application of
)
Docket Nos. STN 50-553 Tennessee Valley Authority
)
STN 50-554 In a March 13, 1980, telephone conversation, Bob Benedict of your staff was notified that an additional fault had been discovered at our Phipps Bend Nuclear Plant in the area of the essential service water pumping station. A conference call was subsequently made to the NRC geologist, Sandra Wastler, on March 14, 1980, to discuss the fault. The enclosure provides a detailed description of this feature.
We do not consider this minor fault to be capable within the meaning of Appendix A to 10 CFR Part 100. '
Very truly yours, TENNESSEE VALLEY AUTHORITY fe' l.$. i '
L. M. Mills, Manager Nuclear Regulation and Safety Enclosure
<<,h 8004080653 y
, m e.~y
l*
PHIPPS BEND NUCLEAR PLANT Fault Zone In Rock Foundation For Essential Service Water Pumping Station Final excavation for the essential service water pumping station has exposed an anticline truncated on both the east and the west limbs by reverse faults. Northwest of the reverse faults is a thrust fault block which resulted from the same tectonic forces that caused the reverse faults. These three faults are designated as Fault Zone 13 on the accompanying map.
The reverse faults truncate the limbs of the anticline and strike parallel to its axis (N48 E).
The fault on the east side of the anticline dips 34 SE, and the fault on the west side of the axis dips 62 NW.
These faults are separated from the anticline by tight weathered fractures.
Strata northwest and southeast of the faults generally have typical strike (N43 E) and dip (36 SE).
The thrust fault strikes N48 E and dips gently to the southeast in the area nearest the anticline. To the northwest the fault plane becomes almost horizontal, for approximately 20 feet, beyond which it dips steeply (89 ) to the northwest. This fault is defined by a weathered fracture which offsets strata having typical strike and dip.
The overburden-rock contact around the perimeter of the excavation shows no of fsetting of Quarternary terrace deposits. The faults of the essential so.vice water pumping station excavation show no evidence which would indicate that they did not occur in the early tectonic develop-ment of the Paleozoic folding and faulting in this area.
These faults, having been stable for 250+ million years, are not considered to be f
l a-capable of producing ground off sets or generating earthquakes. Therefore, we do not classify them as capable faults within the meaning of Appendix A to 10CFR part 100.
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