ML19254D794

Confirms 790924 Telcon Re Addl Earth Faults in Area of Unit 1 Pumping Station & Forwards Detailed Description.Three Color Photographs Encl

ML19254D794
Person / Time
Site:	Phipps Bend
Issue date:	10/24/1979
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 7910300155
Download: ML19254D794 (3)

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400 Chestnut Street Tower II October 24, 1979 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 September 24, 1979, telephone conversation, Jerry Wills of my staff notified Bob Benedict of your staff that additional faults had been discovered at our Phipps Bend Nuclear Plant in the area of the unit 1 ESW pumping station. A conference call was subsequently made to the NRC geologist, Sandra Wastler, on September 24, 1979, 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

./%('i ,j ' ll LLL L. M. Mills, Manager Nuclear Regulation and Safety Enclosure '

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st P'IIPPS BEND NUCLEAR PIANT REVERSE AND TRANSVERSE FAULTS IN THE UNIT 1 ESW PUMPING STATION Geologic mapping of foundation bedrock in the Unit 1 ESW pumping station has revealed two reverse faults in the southeast quadrant of the building, and two transverse faults located west of the reverse faults. They are grouped as fault zone 15 and designated R1, R2, T1, and T2 (see attached photos and drawing for locations).

Faults R1 and R2 are reverse faults parallel to the axis of an anticline to the southeast. R1 dips 67* NW. and strikes N. 50 E. R2 dips 76 SE. and strikes N. 50* E. Both fault traces are defined by calcite-healed fractures that extend across the floor of the excavation from the south wall to the east wall of the building.

Transverse faults T1 and T2 are located west and northwest, respec-tively, of R1 and R2. T1 consists of three nearly vertical branches, one striking N. 52 W., and the other two striking N. 10 E The fault traces are defined by calcite-healed fractures that offset bedding from 3 to 7 inches.

T2 is 7J feet north of T1 and exhibits essentially the same characteristics.

All four faults described were formed during the Paleozoic Era and are characteristic of tectonic forces that developed during the formation of the Saltville fault family. These faults, having been stable for 250 my, are not considered to be capable of producing ground offsets or generating earth-quakes. Therefore, we do not classify them as capable faults, within the meaning of Appendix A to 10 CFR Part 100.

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