ML19296B894
| ML19296B894 | |
| Person / Time | |
|---|---|
| Site: | Phipps Bend  |
| Issue date: | 02/19/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8002220340 | |
| Download: ML19296B894 (4) | |
Text
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TENNESSEE VALLEY AUTHORITY CH ATTANOOG A. TENN ESSEE 37401 400 Chestnut Street Tower II February 19, 1980 Mr. Harold 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 October 22, 1979, telephone conversation, Jerry Wills of my staff notified Bob Benedict of your staff that an additional fault had been discovered at our Phipps Bend Nuclear Plant in the unit 2 turbine building area. A conference call was subsequently made to the NRC geologist, Sandra Wastler, on October 23, 1979, to discuss the fault. The enclosure provides a detailed description of this featura.
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
\\~% W L. M. Mills, Manag'er Nuclear Regulation and Safety j
Enclosure C.
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PHIPPS BEND NUCLEAR PIANT Fault Zone In The Rock Foundation For The Unit 2 Turbine Building Continued excavation of the weathered rock in the south end of the Unit 2 turbine building has exposed complex folding and faulting (see attached map A).
This area is defined by a weathered, faulted, contorted rock zone striking approximately N 50 E and dipping from horizontal to vertical, but generally parallel to the regional dip. On the east perimeter of the turbine building excavation, the faults extend under the overburden.
They are exposed again by excavation-300 feet to the east in the CCW trench, from which they can be traced along the excavated rock surface to the CCW pumping station (see attached map B).
This fault zone (designated number 16) is an extension of faults 7, 8 and 9, located in the CCW pumping station foundation. This was reported to NRC in a memorandum from J. E. Gilliland to H. W. Denton, dated April 30,1979 (ftED 790502 521)..
Examination of the overburden-rock contact around the perimeter of the excavation has revealed no offsetting of Quaternary terrace de-posits. The folds and faults in the Unit 2 turbine building excavation show no evidence which would indicate that they did not occur in the early tectonic development of the Paleozoic (250+ million years) folding and faulting in this area. These faults, having been ~ stable for 250 million years are not considered to be 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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