ML19210C324
| ML19210C324 | |
| Person / Time | |
|---|---|
| Site: | Black Fox |
| Issue date: | 10/19/1979 |
| From: | Ewing T PUBLIC SERVICE CO. OF OKLAHOMA |
| To: | Varga S Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19210C322 | List: |
| References | |
| 6212DIN8-018-48, 6212DIN8-18-48, NUDOCS 7911140074 | |
| Download: ML19210C324 (3) | |
Text
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6212 DIN 8-018-484 rw%-
PUBUC SERVICE COMPANY OF OKLAHOMA I
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A CENTRAL AND SOUTH WEST COMPANY 5
r P O BCX 201 TULSA. OKL AHOM A 74102 < (918. SE3 3f.11 L
Public Service Company of Oklahoma Black Fox Station Units 1 and 2 October 19, 1979 Exca~vation Seal Unit 2 File 6212.125.3500.21L U.S. NRC Docket No. STN 50-556, 50-557 i
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:
This letter updates and confirms several conversations concerning the excavation of Unit 2 which took place between representatives of PS0 and the technical staff of NRR and I&E Region IV during the latter part of July and mid-August of this-year.
During these discussions, we reported the preliminary results of the field testing activities which were completed in the foundation area for Unit 2 structures and the reco :mendations of our Architect-Engineer regarding the nature of the subgrade material found in the Unit 2 excavation area.
Excavation for Unit 2 was authorized under Amendment 2 of the Limited Work Authorization on November 30, 1978. The initial work commenced in December,1972, resumed in April, 1979 after the unusually severe winter forced shutdown and reached the base foundation elevation in mid-June. At that time, field tests showed that a soft, siltstone layer underlaid a large portion of the excavation surface at depths ranging from two to seven feet.
Our Architect-Engineer recommended that the depth of the excavation in the Unit 2 foundation areas be extended to remove the soft siltstone layer. Subsection 2.5.4 of the BFS Pre-liminary Safety Analysis Report predicted such overexcavation below the base foundation elevation and stated that these areas would be backfilled with lean concrete.
As discussed previously with Dr. Cecil 0. Thomas, Licensing Project Manager of NRR and William A. Crossman, Chief, Projects Section, I&E Region IV, the soft, siltstone layer material has now been removed from the excavation area, and a nominal six-inch concrete seal coat has been applied to protect the underlying rock structure from weathering.
In order to bring the entire excavation up to design base foundation elevation, a mass fill of lean concrete will be required. The Unit 2 structures (i.e., the l
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U.' S. Nuclear Regulatory Commission October 19, 1979 Mr. Steven Varga Page Two fuel building, the reactor building, and auxiliary building) would therefore be supported on fill concrete founded directly on the same competent siltstone as Unit 1.
However, in accordance with our oral commitment to Mr. Thomas, we intend to provide the NRC Staff with certain analyses prior to taking this action. These analyses involve an assessment of tho :;trength of the concrete as a foundation material as compared with the natural rock structure and the effect of this relative thick concrete fill on the dynanic response: of the safety-related structures.
During our previous discussions, we expected to supply these analyses within a 30 to 60 day time period for Staff review. Unfcrtunately due to manpower con-straints associated with reviewing the Staff's TMI requirements in preparation for our upcoming hearing, we have fallen behind schedule in providing you with this information.
We will advise you further when the engineering effort on the analyses work is completed.
Very truly yours, T. N. Ewing, Ma r
Black Fox Stat'on Nuclear Project THE:VLC:jk l 2]
cc:
BFS Service List
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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 Pleza, 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 Springfielc, MO 65801 Bethesda, MD 20014 Joseph R. Farris, John R. Woodard III Mrs. Ilene Younghein Feldman, Hall, Franden, Reed and 3900 Cashion Place Woodard Oklahoma 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 j
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