ML19332A053

Forwards Info Re Addl Faults Discovered at Facility in Area of Essential Svc Water Spray Pond.Photographs & Drawings Available in Central Files

ML19332A053
Person / Time
Site:	Phipps Bend
Issue date:	08/22/1980
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML19332A054	List: ML19332A053 ML19332A056
References
NUDOCS 8009100472
Download: ML19332A053 (3)

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400 Chestnut Street Towe" II August 22,1?80 THIS DOCUMENT CONTAINS POOR QUAUTY PAGES

!'r. Parold R. Denten, Directer Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission

'1ashington, DC 20555

Dear Mr. Denten:

In the .Vatter of the Application of ) Docket Nos. S'rN 50-553 Tennessee Valey Authority ) STN 50-554 In a '4ay o and June 13, 1980, telephone conversatien, notification of discovery of additional faults at our Phipps Bend Nuclear Plant was made to the NRC 2eologist, Dick McMullen and Project Manager, Dino Scaletti. The faults are locatec in the area of the unit 1 ESW soray pond. Enclosed is a detailed description of these features.

We do not consider this minor fault to be capable within the meaning of Appendix A to 10 CFR Part 100.

'fery truly yours, TEN'1ESSEE VALLEY AUTHORITY

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L. M. Mills, Mana er N

Nuclear Regulation and Safety Enclosure 3ool s

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. . 3-t PHIPPS BEND NUCLEAR PLANT Fault Zone in the Rock Foundation for the Number 1 Essential Service Water Spray Pond 1 >

Final excavation for the number i essential service water spray .t pond has exposed a series of' reverse faults in the west quadrants of the pord .- Several transverse faults were also located in.this area and were

, geologically mapped.-

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The main reverse faults are labeled Fault Zone 20, Fault 21, and  ;

, Fault 22 (see. attached photographs). ' Fault Zone 20 intersects the minor axis of the pond 112 feet north of the major axis and intersects the i

major axis 85 feet west of the minor axis (see attached map). The fault zone strikes N. 50' E. and dips 66* SE. The zone consists primarily of [

! two faults essentially parallel in both strike and dip, separated by an area of contorted rock which ranges in width from.2 to 10 foot and extends across the en* ire excavation. Secondary faults of similar .,

strike'and dip are present 40 and 75 feet southeast of the r.ortheast half of the main fault. These faults strike parallel to bedding and terminate into bedding planes within the excavation.

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Faults 21 and 22 intersect the major axis of the pond 35 and 65 '

feet west of the main fault of Zone 20. : The strike is N. 40' E., and the' fault planes dip away from each other. Fault 21 dips 83* SE., and Fault 22 dips-58' NW. Both fault planes are defined by calcite zones,

,' O.5 to.3.0' inch wide, which snow minimal. deformation of adjacent beds. ,

A key horizon,; described as a 1- to'2-foot-thick' bed of limestone nodules ,

'which intersects Fault 22 about 125 feet north of the major axis of the d

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pond, indicates an offset of approximately 10 feet, with the west block

-upthrown over the east block.- Similar evidence (calcite along bedding planes) indicates the same type of movement along Fault 21 but only about 0.5 foot of displacement.

Secondary faulting, primarily transverse, has developed along most of the length of Faults 21 and 22. These secondary transverse faults are essentially vertical and exhibit both right- and left-lateral move-ment, ranging in offset from a few inches to 1 foot. Secondary faults whose extents are limited to the mapped area terminate into near-Vertical joints.

Fault Zone 20, Fault 21, and Fault 22 were traced to their inter-sections with the overlying Quaternary terrace deposits, which showed no evidence of deformation.

This type of faulting has also been descrfbed in a report on Faults 7, 8, and 9, located in the CCW pumping station (April 30, 1979).

These faults were formed by stress relief due to tectonic pressure from the northwest and southeast during formation of the Saltville Fault Family (250 mybp). . These faults, having been stable for approximately 250 million years, are not considered to be capable of producing ground

. offsets or generating earthquakes.- Therefore, we do not classify them as capable faults, witbin the meaning of Appendix A to 10 CFR part 100.

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