ML20137N479
| ML20137N479 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 11/18/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20137N470 | List: |
| References | |
| IEB-80-11, NUDOCS 8512040127 | |
| Download: ML20137N479 (3) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR FsEGULATION RELATED TO MASONRY WALL DESIGN COMMONWEALTH EDISON COMPANY AND IOWA-ILLINOIS GAS ANU ELECTRIC COMPANY QUAD CITIES STATION, UNITS 1 AND 2 DOCKET NOS. 50-254/265
1.0 INTRODUCTION
By letter dated May 8,1980, the NRC issued IE Bulletin 80-11, Masonry Wall Design. By letter dated July 7,1980, Commonwealth Edison Company (CECO, the licensee) responded to IE Bulletin 80-11 for Quad Cities Station Units 1 and 2.
This response was supplemented by letters dated November 30, 1981, January 27, 1982 January 31, 1984, March 29, 1984 and June 25, 1985, on the subject of masonry wall design.
The licensee response to TE Bulletin 80-11 was reviewed by the Franklin Research Center (FRC), a contractor for the NRC, who prepared a Technical Evaluation Report (TER) based on the information provided by the licensee as referenced in the TER, and using criteria and guidance provided by the NRC, as described in the TER, 2.0 EVALUATION The findings of this Safety Evaluation (SE) are based on the attached Technical Evaluation Report (TER) prepared by FRC and additional information i
provided by the licensee letter dated June 25, 1985. The staff has reviewed this TER and concurs with its technical findings except as noted in Item 2 below. The following is our sumary of major technical findings:
1.
The criteria used by the licensee in the re-evaluation of the masonry wall, in general, comply with the staff acceptance criteria. There were two differences between the staff and the licensee's criteria. The first difference pertained to the licensee's use of arching action theory to qualify two unreinforced walls. This issue is further discussed in item 2 below. The second difference pertains to the licensee's allowable value for tension normal to the bed joint for the extreme environmental load conditions (for the walls qualified by the working stress method). The staff criteria specify that the allowable tension nomal to the bed joint for the extreme environmental load condition is obtained by increasing the i
8512040127 851118 PDR ADOCK 05000254 G
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2-allowable tension for the service load conditions by a factor 1.3.
The licensee's criteria specify a factor of 1.67 for this purpose.
However, as discussed on page 5 of the TER, the actual calculated j
tensile stress in all but six walls is less than the allowable value obtained by the application of the staff increase factor of 1.3.
For six walls, the survey of the actual calculations-indicate that the resulting stresses are higher than the staff's allowable stresses by 10% to 21%. However, considering the fact that the licensee's calculations also include the conservative i
measures such as low damping (2% as opposed to 7% allowed by the staff's criteria for safe shutdcwn earthquake), the increase of 10% to 21% in stresses is amply compensated. Therefore, the staff concludes that walls qualified by the licensee's working stress criteria comply with the staff's acceptance criteria, and the qualification of the walls as performed by the licensee is acceptable.
2.
The licensee originally qualified two walls by the use of the arching action theory and the findings reported on pages 14, 15, and 19 of the TER are based on this information. However, by letter dated June 25, 1985, the licensee infonned the staff of its decision to modify these two walls using the criteria discussed in Item 1 and that these modifications will be completed by September 27, 1985. Since the staff has concluded that the licensee's working stress criteria comply with the intent of the staff criteria, the licensee's approach is acceptable and the issue regarding arching action theory is resolved.
3.
The licensee has modified eighteen (in addition to two walls discussed in Item 2) of the safety-related walls in the following fashion:
o Structural steel support have been added to the end.
o Vertical steel members have bean installed along the height
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of the wall.
o Loosely stacked (unmortared) shield blocks have been either removed or mortared.
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A portion of the wall has been removed.
The licensee's approach is found adequate as the modified walls have been shown to have met the staff acceptance criteria.
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3.0 CONCLUSION
Based on the above findings, the staff concludes that, with the licensee's commitments discussed in Item 2 of this SE, the Items 2(b) and 3 of the IE Bulletin 80-11 have been fully implemented at Quad Cities Units 1 and 2 and that there is reasonable assurance that the safety-related masonry walls at Quad Cities Station will withstand the specified design load conditions without impairment of wall integrity or the perfcrmance of required safety functions.
Attachment:
Technical Evaluation Report Principal Contributer:
N. Chokshi Dated: November 18, 1985 t
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