RS-04-144, Clarification to Second Interval Inservice Inspection Program Relief Request 12R-46
| ML042670411 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 09/23/2004 |
| From: | Ainger K Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RS-04-144 | |
| Download: ML042670411 (2) | |
Text
Exelon Generation www.exeloncorp.com 4300 Winfield Road Warrenville, IL 6o555 RS-04-144 September 23, 2004 U.S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and 50-455 Subject :
Clarification to Second Interval Inservice Inspection Program Relief Request 12R-46 References : (1) Letter from K. A. Ainger to U. S. NRC, "Second Interval Inservice Inspection Program Relief Request 12R-46," dated July 22, 2004 "Byron Station has also adopted risk-informed inservice inspection using Code Case N-578-t Use of Code Case N-578-1 eliminates examination categories B-J and C-F."
10 CFR 50.55a (2) Letter from A. J. Mendiola (U. S. NRC) to 0. D. Kingsley (Exelon Generation Company, LLC), "Approval of Relief Request 12R-40 for Application of Risk-Informed Inservice Inspection Program as an Alternative to the ASME Boiler and Pressure Vessel Code Section XI Requirements for (lass 1 and (lass 2 Piping Welds for Byron Station, Units 1 and 2," dated February 5, 2002 At the request of the NRC, Exelon Generation Company, LLC (EGC) is providing a clarification to the Reference 1 submittal. In Section 5.13, "Piping flange components," of the attachment to the submittal, the relief request states in part :
The Byron Station, Unit 1 and Unit 2 risk-informed inservice inspection (RI-ISI) program was developed in accordance with NRC approved Electric Power Research Institute Topical Report TR-1 12657, Revision B-A, "Revised Risk-informed Inservice Inspection Evaluation Procedure," using the Nuclear Energy Institute template methodology. The Byron Station RI-ISI program was subsequently approved for use in Reference 2.
U. S. Nuclear Regulatory Commission September 23, 2004 Page 2 The reference to the American Society of Mechanical Engineers (ASME) Code Case NA578-1, "Risk-informed Requirements for Class 1, 2, and 3 Piping," in the above statement was intended to underscore the fact that with the implementation of the RI-ISI program, the ASME Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," examination categories for Class 1 and Class 2 piping welds were eliminated from the Byron Station Inservice Inspection Program.
It was the pipe welds selected under these categories that determined which piping flange bolting components were to be selected for examination.
In place of these examination categories, the RI-ISI program establishes new risk categories 1, 2, 3, 4, 5, or 6 for piping welds. However, to maintain consistency with established ASME Section XI conventions, the weld categorization scheme of Code Case N-578-1 was adopted. That is, Code Case N-578-1 establishes a "R-A" weld category and weld item numbers R1.10 through R1.20, which allows Byron Station to categorize RI-ISI piping welds in a manner similar to the standard ASME Section XI pipe weld program. This method of categorizing assists in assigning weld examination requirements ; establishing minimum and maximum percentages of credited examinations for each ISI period ; and also provides for a practical way to perform, if required, examination scope expansion.
The statement was not intended to imply that the Byron Station RI-ISI program is based on Code Case N-578-1. EGC recognizes that Code Case N-578-1 is an unapproved code case with limitations as identified in Regulatory Guide 1.193, "ASME Code Cases Not Approved for Use," June 2003.
Should you have any questions concerning this letter, please contact David J.
Chrzanowski at (630) 657-2816.
Respectfully, Kenneth A. Ainger Manager, Licensing