ML19341C286

Forwards Info Re Faults 26 & 27 in Foundation Piers 34 & 19 of Unit 1 Cooling Tower,Initially Reported on 810113 & 22. Neither Fault Is Capable within Meaning of App a to 10CFR100

ML19341C286
Person / Time
Site:	Phipps Bend
Issue date:	02/24/1981
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 8103020633
Download: ML19341C286 (6)

Text

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400 Chestnut Street Tower II February 24, 1981 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Dear Mr. Denten:

In the Matter of the Applications of ) STN 50-553 Tennessee Valley Authority ) STN 50-55u During telephone conversations on January 13 and January 22, 1981, Licensing Project Manager Dino Scaletti was notified that two additional faults had been discovered at our Phipps Bead Nuclear Plant. These faults are located in foundation piers Nos. 34 and 19 for cooling tower 1. Conference calls were subsequently made to NRC geclogist Dick McMullan on Janu ry 14 and January 22, 1981, to discuss each fault. The enclosure provides a detailed description of both fault features. We do not censider either fault to be capable within the meaning of Appendix A to 10 CFR Part 100.

During the January 22 telephone conversation, we received verbal approval to delete the immediate fault notification requirement for common or routine faults, but include them in the six-month geologic foundation report. This verbal approval was granted with the understanding that TVA i=mindiately notify the NRC of any unusuti or significant faults encour.tered in the future. The above agreement was again confirmed in is telephone conversation with Dino Scaletti on. February 20, 1981.

Very truly yours, TENNESSEE VALLEY AITrHORITY

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L. M. Mills, Manager Nuclear Regulation and Safety l

Subscribe r sworn to b *

• me this day of .

1981.

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l- Notary Public

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My Commission Expires l

Enclosure anosoADM3 A ~

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l PHIPPS BEND NUCLEAR PLANT

, i Fault 26 in the Rock Foundation for the Unic I Cooling Tower Pier 34 l r

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Drilling of the foundation piers for cooling tower 1 has exposed a thrust fault in the bottom of pier 34 at elevation 1098.7. This is identified as Fault 26 on the attached fault locations map (Exhibit 1).

The fault trace, located at the bearing surf ace of the 60-inch-diameter pier,isdefinedbgaweatheredfracture1/2inchvide,whichstrikes approximately N. 5 E. It dips 35 east and extends across the rock sur-face at the bottom of the hole. Bedding east of the fault plane strikes i N. 380 E. and dips 89 NW., whereas bedding to the west strikes N. 10 E.  ;

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and is vertical (Exhibit 2). Because of the limited arec of exrosed rock, '

the amount'and direction of offset is indeterminable.  !

1 The contact between . top of rock and Quaternary certace deposits his not

been exposed in the cooling tower area, but no indic ,tions of orrsetting

),

or tectenic disturbance are evident in the overburden.

This type of fault has been described in the Phipps Bend Nuclear Plant Preliminary Safety Analysis F. sport, section 2.5.1.1.2-14, and is considered i .by Rodgers (reference 93 PB PSAR) to be abundant in the Saltv111e Fault 1 Family..

-The fault was formed by stress relief due to pressure from the northwest i

-and southeast during the formation of the Saltville Fault Family (250 nybp).

i: This fault, having been stable for approximately 200 million years, is not

. considered to be capable of producing ground otfsets or generating earth-quakes. Therefore, we.do not classify it as a capable fault, within the meaning of Appandix A to 10 CFR part 100.

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, PHIPPS BEND NUCLEAR PLANT Fault 27 in the Rock Foundation for the Unit 1 Cooling Tower Pier 19 Drilling of the foundation piers for cooling tower 1 has exposed a thrust fault in the side wall of pier 19 at elevation 1111.5. It is identified as Fault 27 on the attached locations map (Exhibit 1).

i The fault trace is defined by a clay seam 1/8 inch wide which strikes N. 2 E. and dips 35 ea.a t . Bedding on both sides of the fault is vertical, and drag folds have developed adjacent to the clay seam.

These folds indicate that the lower block moved east relative to the upper block (Exhibit 3). Because of the absence of marker beds, the amount of ovement is indeterminable.

l The contact between top of rock and Quaternary terrace deposits has not been exposed in the cooling tower area, but no indications of offsetting .

or tectonic disturbance are evident in the overburden. J This type of fault has been described in the Phipps Bend Nuclear Plant 4 Preliminary Safety Analysis Report, section 2.5.1.1.2-14, and is con-sidered by Rodgers (reference 93 PB PSAR) to be abundant in the Saltville Fault Family.

The fault was formed by stress relief due to pressure from the northwest and southeast during the formation of the Saltville Fault Family (250 mybp).

This fault, having been stable for approximately 200 million years, is not considered to be capable of producing ground offsets or generating earth-quakes. Therefore, we do not classify it as a capable fault, within the meaning of Appendix'A to 10 CFR part 100.

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