ML20214M772
| ML20214M772 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 05/22/1987 |
| From: | Ainger K COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 3116K, NUDOCS 8706010423 | |
| Download: ML20214M772 (2) | |
Text
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< Address Reply to: Post Office Box 767 N -s Chicago, Illinois 60690 - 0767 FRI0ftITY R7JTIXS First
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May 22, 1987 8
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Mr. A. Bert Davis Regional Administrator U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Byron Station Unit 2 Concrete Surface Defect NRC Docket No. 50-455 Reference (a): April 14, 1987 letter from C.E. Norelius to Cordell Reed
Dear Mr. Davis:
This is in response to reference (a) which requested Commonwealth Edison to investigate a crack in a structure at Byron Station. The information enclosed with reference (a) was forwarded to Sargent & Lundy for their review.
A field examination of this defect was performed by Sargent & Lundy on April 29, 1987. The " crack" is located in the exterior face of the secondary shield wall in the Unit 2 containment building at about azimuth 80' and elevation 395'-9".
It is not located in the turbine building as indicated in reference (a). The " crack" is actually a small horizontal surface defect at each edge of the vertical embedment. The maximum dimensions of the defect on each side of the plate are about 6 inches long by 1/4 inch wide by 1/2 inch deep. The concrete surface immediately adjacent to the defect has been repaired.
A review of Blount's concrete pour records indicated that two separate pours were made: one above and one below the elevation of the defect. Small concrete surface defects at cold joints between concrete pours are not uncommon. Based on Sargent & Lundy's examination, it is evident that this small defect was not completely repaired. This minor surface defect has an insignificant effect on the structural integrity of the secondary shield wall or on the load carrying capability of the embedment plate.
Reference (a) contained an illustration showing that the embedment plate is cracked. Field examination showed that there is a small gap between two sections of the embedment plate located at about elevation 396'-9" and not a crack as indicated in the illustration. The gap is about l' above the small concrete defect discussed above. This gap is of no concern as there are no attachments near the plate edge and strip plates are often cut between studs and butted together at placement.
b 8706010423 870522 PDR ADOCK 05000455 l
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PDR j[Q J
l A. B. Davis 2'-
May 22, 1987 l
Based on our evaluation of the defect, we have concluded the i
condition is acceptable as is.
Please direct any questions regarding this matter to this office.
[
Very truly yours, l'
I K. A. 'inger j
Nucleaa Licensing Administrator 3116K i
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.