ML12171A530
| ML12171A530 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 09/15/2010 |
| From: | Marilyn Evans, Renee Taylor Office of Nuclear Reactor Regulation |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| Shared Package | |
| ML12171A508 | List: |
| References | |
| RAS 22624, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01 | |
| Download: ML12171A530 (5) | |
Text
NYS000388 Submitted: June 19, 2012 Bilateral Exchange:
Steam Generator Divider Plate Cracking Michele Evans Director, Division of Component Integrity Robert Taylor Chief, Steam Generator Integrity & Chemical Engineering Branch September 15, 2010 1
Divider Plate Tubesheet (TS)
Full Penetration Weld Stub Runner (SR)
Observed Typically 3 Cracking Full Penetration Weld Region 1.50 - 4.00 Divider Plate (DP) (40 - 100 mm)
Source: ML072060144 2
Issue
- Cracking in the divider plate/stub runner has been observed in several French units
- Inspections have not been performed in the U.S.
- Recently started to question whether cracks in the divider plate could grow into the channel head (steam generator shell) or tubesheet cladding
- Cracking of the steam generator shell or the tube-to-tubesheet weld could have safety significance 3
Regulatory Action
- Completed Actions
- Safety significance of cracking in the divider plate assessed by U.S. industry
- Not a significant safety issue
- For license renewal, assessing need for aging management program
- NRC concern relates to lack of information on how prevalent cracks are in divider plates - number, depth, length, etc. - not a concern for Alloy 690 materials
- Additional information requested from applicants regarding the potential for cracks to continue to grow into shell or tube-to-tubesheet welds
- No such cracking has been observed 4
Discussion Topics
- Materials of construction of divider plates (Alloy 600, Alloy 82/182 , Alloy 690, Alloy 52/152)
- Divider plate cracking experience in Japan
- Inspections performed in Japan
- Any on-going activities 5