ML14321A588
| ML14321A588 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 10/30/2014 |
| From: | Martha Barillas Plant Licensing Branch II |
| To: | Alan Huynh, Andrea Johnson, Karwoski K Division of Engineering |
| Barillas M DORL/LPL2-2 301-415-2760 | |
| References | |
| Download: ML14321A588 (4) | |
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Robinson RF028 SG Tube Inspection Report questions Telecon HQ-OWFN-09B02-12p Tue 11/04/2014 8:30 AM Tue 11/04/2014 9:30 AM Tentative (none)
Not yet responded Barillas, Martha Karwoski, Kenneth; Johnson, Andrew; Huynh, Alan; Barillas, Martha Licensee has requested call to discuss the attached responses to the Robinson RFO 28 SG Tube Inspection Report questions from the staff.
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Steam Generator Tube Inspectio...
1
Response to Draft Request For Additional Information H. B. Robinson Steam Electric Plant, Unit 2 Refueling Outage 28 Steam Generator Tube Inspection Report Below are the responses for the request for additional information:
- 1. Please clarify the scope of your inspections in the U-bend region of the tubes located in rows 1, 2, and 9. For example, were the U-bend regions of the tubes in rows 1 and 2 inspected with a bobbin coil? Were 50% of the row 1 and 2 tubes and 20% of the row 9 tubes inspected with an array probe or were some not inspected as a result of probe availability?
Duke Response:
No. No. Fifty percent (50%) of the tubes in rows 1 and 2 were inspected with either the array probe or the plus point coil. Twenty percent (20%) of the tubes in row 9 were inspected with the array coil.
- 2. Please clarify the scope of the primary bowl cladding inspection. Was just the region around the central, bottom portion of the channel head inspected or were all clad surfaces inspected? Please confirm that no degradation was detected during the primary channel head cladding inspections.
Duke Response:
All clad surfaces were inspected and no degradation was detected during the primary channel head cladding inspections.
- 3. In 2008, low levels of primary-to-secondary leakage were observed in steam generator A. Please discuss whether any indications detected during RFO 28 could be the source of that leakage.
Duke Response:
None of the indication detected in RFO 28 were identified as the source of the referenced leakage.
- 4. On the cold-leg side of the steam generator array probe examinations were performed in a two-tube pattern. Please clarify the two-tube pattern. Were all tubes in the periphery (two tubes deep) inspected?
Duke Response:
Yes.
- 5. Please clarify what technology was being bridged during the rotating probe examinations. Were these examinations performed to accommodate the use of the array probe?
Duke Response:
The technology bridged was the switch from plus point coil to the array probe. Yes.
- 6. Please provide the effective full power years the steam generators had operated for, as of RFO 27 and 28.
Duke Response:
Robinson had operated for 21.8 EFPY at the end of EOC27 and 23.2 EFPY at the end of EOC 28.
- 7. Please clarify the tubes that were plugged. Were all tubes with expansion transitions located more than 1-inch below the top of the tube sheet plugged (i.e., R20C35 and R1C47 in steam generator A, and R11C70 and R25C10 in steam generator B).
Duke Response:
Yes, all tubes with expansion transitions located more than 1-inch below the top of the tube sheet were plugged (R20C35 and R1C47 in steam generator A, and R11C70 and R25C10 in steam generator B).
- 8. Please confirm that all of the indications detected at the tube support plates were a result of interactions with a loose part.
Duke Response:
Yes, all of the indications detected at the tube support plates were a result of interactions with a loose part.
- 9. There appears to be a significant decline in the number of indications reported during RFO 28 when compared to RFO 26, especially when the number of new indications (as reported in the January 30, 2014 letter) is taken into account. Since all tubes with historic bobbin coil indications were inspected, please clarify the reason for this decline. Was the eddy current data quality during RFO 28 as good, or better, than that in RFO 26?
Duke Response:
The eddy current data quality during RFO 28 was as good as that in RFO 26. The decline represents a change in the dispositioning of the indications (i.e., how the indications were coded) and therefore reporting of service induced indications. If the history review indicated that the reportable indication was present in the past and has not changed, and that a rotating coil exam had been performed on the signal in the past, the report code HNC(Historical No Change) was used. If the indication matched the
historic indication, but did not meet the current reporting parameters, the report code INR (Indication Not Reportable) was used. An exception is wear at support structures, which was reported even if under the reporting threshold. HNC or INR are not reported as service induced indications.
Additional Information if needed Duke tried to simplify the review process HNC or HNI replaces the NQS, DFS, DSS, DTS calls used in the past. The S code from past exams and HNI/HNC code we use designate that a Historical Data Evaluation is performed and that the signal has not changed.
In the case of loose part wear (part no longer present) which have also been tracked for year. A diagnostic exam is preformed which includes sizing by either +Pt or Array probe.
When these wear indications have been sized for 3 consecutive outages and they show no growth or change these indications are changed to HNC/HNI. They are still scheduled for bobbin testing each following inspection. The bobbin response is evaluated for change and if change is present will be given an I-code. As the loose part has been removed or moved from the wear location no growth has been identified for multiple outages so we give them and Historical no change response (HNC/HNI)
- 10. Please confirm that a location with an A (e.g., 04A) as reported in the attachment to your April 29, 2014, letter represents an anti-vibration bar.
Duke Response:
Yes, the A represents an anti-vibration bar.
- 11. Please discuss the results of your anti-vibration bar insertion depth study.
Duke Response:
The insertion depth study confirmed that all tubes that should be supported by a particular AVB were confirmed by ECT to have a support structure present.