ML20138G046
| ML20138G046 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 04/30/1997 |
| From: | Hosmer J COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20138G051 | List: |
| References | |
| NUDOCS 9705060147 | |
| Download: ML20138G046 (1) | |
Text
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Commonweahh Ednon Company 1-100 Opus Plac Downers Grose. 11.605145 01 April 30,1997 U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Attention:
Document Control Desk
Subject:
Braidwood Nuclear Power Station Unit i NRC Docket Numbers: 50-456 Additional Information Pertaining to Braidwood Unit i Locked Tube Circumferential Indications
Reference:
Meeting dated April 30,1996, between the Nuclear Regulatory Commission and the Commonwealth Edison Company During the Referenced meeting, the Commonwealth Edison Company (Comed) and the Nuclear Regulatory Commission (NRC) discussed the root cause determination evaluation that has been performed which examines the discrepancy between the frequency of the top-of-tubesheet (TTS) circumferential indications i
identified in the Braidwood Unit I locked tubes relative to the in-senice population of tubes. The issues examined in this root cause are those which lead to the initiation, growth and detection of stress corrosion cracking in mill annealed Inconel 600 steam generator tubing, and include. materials, stress, environment, fabrication and growth. The conclusion reached was the tube lock, indepenOnt of configuration, provides l
cnough of an additional axial stress to result in a shorter time to crack initiation than for inservice tubes.
Attached is the root cause determination evaluation report,"Braidwood Unit 1 Locked Tube TTS Circumferential Indication Root Cause Determination Evahiation."
i If you have any questions concerning this correspondence, please contact this office.
Sincere,
Mf9N
(
John B. Hosmer Engineering Vice President Attachment cc:
D. Lynch, Senior Project Manager-NRR G. Dick, Byron,'Braidwood Project Manager-NRR C. Phillips, Senior Resident inspector-Braidwood i
A. B. Beach, Regional Administrator-Rill Office of Nuclear Safety-IDNS h
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