ML080860110
| ML080860110 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 03/05/2008 |
| From: | Thadani M NRC/NRR/ADRO/DORL/LPLIV |
| To: | Ameren Corp |
| Thadani, M C, NRR/DORL/LP4, 415-1476 | |
| References | |
| TAC MD7372 | |
| Download: ML080860110 (3) | |
Text
From:
Mohan Thadani To:
Internet:smaglio@ameren.om; Internet:telwood@ameren.com Date:
3/5/2008 9:11:21 AM
Subject:
PRELIMINARY RAI FOR STEAM GENERATOR TUBE INSPECTION (TAC No.
MD7372)
Tom/Scott:
Please review the RAI below, and advise on the schedule for Ameren response.
If you need any clarifications, please contact Jack during my absence for clarifications.
Thanks.
Mohan PRELIMINARY REQUEST FOR ADDITIONAL INFORMATION 2007 STEAM GENERATOR TUBE INSPECTIONS CALLAWAY PLANT UNIT 1 DOCKET NUMBER 50-483
- 1.
You indicated that no active degradation was identified in your steam generators during the 15th Refueling Outage steam generator tube inspections; however, you also indicated that you had identified several tubes with wear at the anti-vibration bars. Please clarify your definition of "active degradation mechanism". The staff has found that the industry=s (Electric Power Research Institute's) definition of active degradation in Revision 6 to the Pressurized Water Reactor Steam Generator Examination Guidelines is misleading since tubes could have degradation that is progressing (or present on the tubes) but the degradation could be classified as Anot active@ (refer to ML010320218 and ML012200349). As a result, please confirm that other than wear at the anti-vibration bars, that you did not find any service-induced indications (i.e., those not attributable to manufacturing) during your inspections.
If you did find other indications, please provide the location, orientation, and measured sizes of these indications.
- 2.
Please provide the effective full power months at the time of your first in-service inspection following the replacement of your steam generators.
- 3.
For future reference, please provide the following information regarding the design of your replacement steam generators: the tubesheet thickness (with and without clad), the method used to expand the tubes into the tubesheet and the extent of expansion, the extent to which any tubes were stress relieved following bending, the radius of the smallest radius tubes, the tube support plate thickness (including the flow distribution baffle, if any), the anti-vibration bar cross section (e.g., rectangular) and the depth of
penetration of the anti-vibration bars. In addition, please provide a tubesheet map, sketch of each stream generator showing the tube support naming convention, and clarify the number of tubes in the steam generators since you indicated that you performed a 100% inspection which was indicated to be 5536 tubes, (and other prior documentation from meetings with the Nuclear Regulatory Commission indicates that there are 5872 tubes per steam generator).
- 4.
Regarding the scope of your inspections, discuss whether any plug or secondary side inspections (including foreign object search and retrieval inspections) were performed. If so, discuss the results. If any loose parts or degraded conditions were identified, please discuss the actions taken to ensure acceptable steam generator performance until the next scheduled inspection.
- 5.
Please clarify the following sentence: "Callaway did not perform repairs to any tubes because no tubes exceeded the repair criteria." In particular, confirm that no tube repairs were performed since no tubes exceeded the repair criteria and tube integrity will be maintained until the next steam generator inspection given the flaw sizes that were left in service. The staff notes that sometimes repair may be necessary to ensure tube integrity even though the depth of the flaw does not exceed the tube repair criteria. This depends on plant-specific growth rates and other considerations.
- 6.
Please clarify whether the +Point examinations performed in the periphery at the top of the tubesheet included both the hot-and cold-leg tubes.
- 7.
The staff is aware of at least one chemical excursion that affected the steam generator water chemistry. Please discuss the nature of all chemical excursions that occurred during your first cycle of operation. In addition, discuss the implications of these chemical excursions.
Mail Envelope Properties (47CEAA09.D25 : 23 : 35106)
Subject:
PRELIMINARY RAI FOR STEAM GENERATOR TUBE INSPECTION (TAC No. MD7372)
Creation Date 3/5/2008 9:11:21 AM From:
Mohan Thadani Created By:
MCT@nrc.gov Recipients ameren.com telwood (Internet:telwood@ameren.com)
ameren.om smaglio (Internet:smaglio@ameren.om)
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