ML19260C102

Forwards Analyses Re Excavation Seal.Analyses Involve Assessment of Strength of Mass Fill of Lean Concrete Vs Natural Rock Structure & Effect on Dynamic Response of safety-related Structures

ML19260C102
Person / Time
Site:	Black Fox
Issue date:	12/12/1979
From:	Ewing T PUBLIC SERVICE CO. OF OKLAHOMA
To:	Varga S Office of Nuclear Reactor Regulation
Shared Package
ML19260C103	List: ML19260C102 ML19260C107
References
6212.125.3500.2, NUDOCS 7912180559
Download: ML19260C102 (3)

Text

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6212 DIN 8-019-76'.

PUBLIC SERVICE COMPANY OF OKLAHOMA A CENTRAL AND SOUTH WEST COMPANY P O BOX 201/ TULSA. OKLAHOMA 74102 / (918) 583-3611 Public Service Company of Oklahoma December 12,1979 Black Fox Station Units 1 and 2 File 6212.125.3500.21L Excavation Seal Unit 2 U.S. NRC Docket No. STN50-556, 50-557 Mr. Steven A. Varga, Assistant Director Division of Project Management Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20002

Dear Mr. Varga:

As promised in our letter of October 19, 1979, we are transmitting herewith, for staff review, analyses we have done regarding the excavation seal on Unit 2 of the Black Fox Station. These analyses involve an assessment of the strength of a mass fill of lean concrete as a foundation material as compared with the natural rock structure and the effect of this relatively thick con-crete fill on the dynamic responses of the safety related structures. The attached material is in the format of the BFS PSAR, Sub ection 3.8.5. We intend to submit this material as a PSAR Amendment in conjunction with a TMI related amendment which will be filed prior to the commencement of the safety hearings.

The purpose of the concrete fill is, of course, to replace the excavated silt-stone with concrete which meets the design basis established for the under-lying competent siltstone during the NRC's Site Suitability Evaluation. The attached analysis demonstrates that the design basis is met and that there will be no soil structure interaction as a result of seismic events and that the impact on the dynamic response of the safety related structures is insigni-ficant.

Since a concrete fill represents a relatively large concrete pour, PS0 will utilize full quality procedures and quality control concrete in this activity even though this work cannot be construed as safety related. This has been done with all of the concrete poured as a part of the excavation seals for Unit 1 and Unit 2. In addition, the computed value of the shear wave velocity for the lean concrete backfill will be verified by actual tests in the field to insure that it is not lower than 3500 fps, ensuring the design basis is met.

This transmittal fulfills our commitment to provide analysis and placement descriptions prior to commencing the mass fill. PS0 believes that the accom-panying analysis demonstrates acceptability of proceeding with completion of 1609 242 mu sorg 'VAs s i i

,G, s CENTRAL AND SOUTH WEST SYSTEM

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Steven A. Varga Page 2 the excavation seal for Unit 2 under the Limited Work Authorization now in effect. We request your prompt review and authorization so we may proceed with this activity.

Very truly yours, k

T.N. Ewing, M er Black Fox Sta on Nuclear Pro' t TNE/VLC/dah attachments ,

cc. BFS Service List 1609 243

BLACK FOX STATION SERVICE LIST Mr. Lawrence Burrell MHB Technical Associates, Inc.

Route 1, Box 197 1723 Hamilton Avenue, Suite K Fairview, OK 73737 San Jose, CA 95125 Andrew T. Dalton Michael I. Miller 1437 So. Main St., Suite 302 Isham, Lincoln & Beale Tulsa, OK 74119 One First National Plaza, Suite 4200 Chicago, IL 60603 L. Dow Davis, William D. Paton, and Colleen Woodhead Mr. Jan A. Norris Counsel for NRC Staff USNRC, Environmental Projects Branch 3 USNRC Phillips Building Washington, D.C. 20555 7920 Norfolk Avenue Bethesda, MD 20014 Mrs. Carrie Dickerson Citizens Action for Safe Energy, Inc. Charles S. Rogers, Asst. Attorney General P. O. Box 924 112 State Capitol Building Claremore, OK 74017 Oklahoma City, OK 73105 Mr. Cecil Thomas Mr. Gerald F. Diddle, Gen. Mgr. USNRC Associated Electric Cooperative Inc. Phillips Building P. O. Box 754 7920 Norfolk Avenue Springfield, MO 65801 Bethesda, MD 20014 Joseph R. Farris, John R. Woodard III Mrs. Ilene Younghein Feldman, Hall, Franden, Reed and 3900 Cashion Place Woodard klahoma City, OK 73112 816 Enterprise Building Tulsa, OK 74103 Mr. Joseph Gallo Isham, Lincoln & Beale 1050 17th Street, N.W.

Washington, D.C.

Mr. William G. Hubacek USNRC, Region IV Office of Inspection and Enforcement 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76012 Mr. Maynard Human, Gen. Mgr.

Western Farmers Electric Cooperative P. O. Box 429 Anadarko, OK 73005 e

1609 244