ML20126J470
| ML20126J470 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 04/23/1981 |
| From: | Norelius C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Reed C COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML20126J474 | List: |
| References | |
| NUDOCS 8104290280 | |
| Download: ML20126J470 (2) | |
Text
h / a nog'o UNITED STATES
"'f NUCLEAR REGULATORY COMMISSION n
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- REGION lli F
799 ROOSEVELT ROAD g*
GLEN ELLYN, ILLINOIS 6o137 gd y
J APR 2 31981 M
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Docket No. 50-454
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-Docket No. 50-455 b
9, Commonwealth' Edison Company ATTN:
Mr. Cordell Reed i
Vice President Post Office Box 767 Chicago, IL 60690 Gentlemen:
o Thank you for your letter dated February 26, 1981, regarding cable tray weld quality at the Byron Plant.
We have reviewed this letter and its attachment which documents your statistical approach towards resolving nonconforming cable tray stiffener welds identified, in part, by NCRF-529.
As a result of this review, we have the following questions which require further clarification on your part.
1.
Your " Weld Quality" asso:nption in Attachment "A",
Byron Cable Tray Stiffener Weld Inspection, does not demonstrate an adequate basis to establish that weld size and quality are scceptable. NRC inspectors have observed poor quality welds in installed cable trays. These observations were not docu-i mented because our inspectors understood, based on discussions with your staff, that your inspections had identified these issues.
Since according to statements in your letter weld size and quality had not been documented as nonconforming, we conclude that your analysis and evaluation are incom-plete.
Please provide additional evidence of adequate weld quality based on the inspection history of the aforementioned welds or other considera-tions. Also, please address the discrepant welds on installed cable tray stiffeners observed by NRC inspectors.
2.
Your methodology for establishing a random sample as outlined in Attachment "A"
is not clear.
Please provide a comprehensive description of what was done to establish a random sample.
Include in this description the basis for concluding that your sample is representative of the total population.
l 3.
It appears that the statistical evaluation of the quality of these cable tray stiffener welds constitutes a change from the acceptance and quality criteria outlined in Section 3.8 (Design of Category 1 Structures) Table 3.8-2, Item No. 20 of the FSAR.
Please discuss your intentions and con-siderations regarding compliance with this FSAR design requirement.
4.
Your report concludes that based on sampling methods used, up to 1.3%
defective stiffener welds may exist for safety-related cable trays at Byron THIS DOCUMENT CONTAINS POOR QUALITY PAGES 8104490260
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Units'1-and-.2.
Please provide us additional information'regarding the basis-for assuming that this is.an acceptable level of risk. Also in your response, please. address your plans for corrective action for any specific defective j
welds which are identified in the future, where such welds are a part of the population that was' included in the study.
t Your statement in the February 26, 1981 letter that "The inspectors agreed with t'
our approach and conclusions" represents.an overstatement of our position on this issue. While we agree it is your prerogative to solve the problem.in'any manner of your choosing, we did not indicate that the approach and methodology would be acceptable to NRC without further review.' During the initial conversations.and subsequent meetings, our staff expressed several reservations in this regard, and requested that the subject report be submitted in writing for our review..
In order-for us to continue our review of this matter, we request'.that you provide a written response within 25 days'to this office addressing the questions previously discussed.
Your cooperation with us is appreciated.
Sincerely, f, [ Y)eeE..--
C. E. Norelius, Acting Director Division of Engineering and Technical Inspection cc:
J. S.'Abel, Director of Nuclear Licensing Gunner Sorensen, Site Project Superintendent V. I. Schlosser, Project Manager l
R. E. Querio, Station Superintendent cc w/1tr dtd 2/26/81:
F Central Files i
Reproduction Unit NRC 20b
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PDR Local PDR NSIC TIC Mary Jo Murray, 0ffice of l
Assistant Attorney General Myron M. Cherry.
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