ULNRC-05981, Enclosure 1 to ULNRC-05981, License Renewal Application, Supplement to Request for Additional Information (RAI) B2.1.20-1
| ML13107A014 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 04/15/2013 |
| From: | Ameren Missouri, Union Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML131070020 | List: |
| References | |
| ULNRC-05981 | |
| Download: ML13107A014 (3) | |
Text
ULNRC-05981 April 15, 2013 Page 1 of 3 CALLAWAY PLANT UNIT 1 LICENSE RENEWAL APPLICATION SUPPLEMENT TO REQUEST FOR ADDITIONAL INFORMATION (RAI) B2.1.20-1
ULNRC-05981 April 15, 2013 Page 2 of 3 RAI B2.1.20-1
Background:
LRA Section B2.1.20 states that there are 19 socket welds in the small-bore piping population.
During the audit, the applicant indicated that a recent recount by the applicant showed that there are in fact 23 Class 1 small-bore socket welds.
Issue:
Based on the applicants previous miscount as well as the staffs experience with reviews of other LRAs for similar PWR facilities, where the typical number of in-scope socket welds are roughly twice the number indicated by the applicant, the staff is concerned that an accurate population of in-scope socket welds may not be fully represented in the applicants LRA.
Request:
Verify and confirm the number of in-scope Class 1 small-bore socket welds in the population of ASME Code Class 1 piping. Based on this review, amend LRA Sections A1.20 and B2.1.20, to indicate the correct population of in-scope socket welds.
Callaway Response Callaway confirms that there are 77 ASME Class 1 small-bore socket welds less than four inches nominal pipe size (NPS) and greater than or equal to one inch NPS in the scope of AMP B2.1.20, One-Time Inspection of ASME Code Class 1 Small-Bore Piping. LRA Sections A1.20 and B2.1.20 have been revised, as shown on LRA Amendment 7 in Enclosure 2, to identify 77 ASME Code Class 1 small-bore socket welds.
Supplemental Response:
Nineteen (19) ASME Class 1 small-bore socket welds less than four inches NPS and greater than or equal to one inch NPS were identified in the original LRA. LRA Amendment 7 submitted in response to RAI B2.1.20-1 revised this number to 77. The reason for the change is that the initial count of 19 was obtained from the Callaway Inservice Inspection (ISI) database. The initial list was developed by filtering components in the ISI database using the fields ASME Category and Item number. For example, one sort used Category B-J, which includes all Class 1 Pressure Retaining Welds in Piping, and another used Item Number B9.40, which corresponds to Class 1 Socket Welds. Callaway staff later identified additional socket welds that had not been identified in this initial sort. This discovery coincided with the AMP Audits, during which Callaway staff communicated during the course of audit interviews that the ASME Class 1 socket weld population was 23 welds, rather than the 19 identified in the original LRA. The staff noted that its recent reviews of other similar PWR facilities have shown the number of reported in-scope socket welds to be roughly twice the number counted by the applicant, suggesting the need for a possible verification. The discovery of these four previously unidentified welds and the OE provided by the staff prompted further investigation. Callaway subsequently determined that some small-bore socket welds were never assigned Category and Item Numbers in the ISI database because they are exempt from ASME Section XI ISI volumetric and surface examinations. Examples include one-inch reactor vessel head vent lines and one inch hot-leg thermowells. These welds are in the database, but since they were never assigned Category and Item Numbers they did not show up in the initial sorts. Construction records and plant
ULNRC-05981 April 15, 2013 Page 3 of 3 drawings were then reviewed to confirm the population of Class 1 small-bore socket welds, and the final number was determined to be 77.
Corresponding Amendment Changes Refer to the Enclosure 2 Summary Table, Amendment 7, LRA changes from RAI Responses, within ULNRC-05892 for a description of LRA changes with this the original response. No changes to the License Renewal Application (LRA) are needed as a result of this supplemental response.