RS-14-249, Results of Detailed Review Performed in Response to Request 1 of NRC RAI B.2.1.7-7 from Set 17, Related to License Renewal Application
| ML14247A195 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 09/04/2014 |
| From: | Gallagher M Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RS-14-249, TAC MF1879, TAC MF1880, TAC MF1881, TAC MF1882 | |
| Download: ML14247A195 (4) | |
Text
Michael P. Gallagher Vice President. License Renewal Exelon Nuclear Exelon Generation 200 Exelon Way Kennett Square, PA 19348 610 765 5958 Office 610 765 5956 Fax www.exeloncorp.com michaelp.gallagher@exeloncorp.com 10 CFR 50 10CFR51 10 CFR 54 RS-14-249 September 4, 2014 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455
Subject:
Results of Detailed Review Performed in Response to Request 1 of NRC RAI B.2.1. 7-7 from Set 17, related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application
References:
- 1. Letter from Michael P. Gallagher, Exelon Generation Company LLC (Exelon},
to NRC Document Control Desk, dated May 29, 2013, "Application for Renewed Operating Licenses."
- 2. Letter from Lindsay R. Robinson, US NRC to Michael P. Gallagher, Exelon ,
dated March 20, 2014, "Request for Additional Information for the Review of the Byron Nuclear Station, Units 1 and 2, and Braidwood Nuclear Station, Units 1 and 2, License Renewal Application, Set 17 (TAC NOS. MF1879, MF1880, MF1881, and MF1882)"
- 3. Letter from Michael P. Gallagher, Exelon, to NRC Document Control Desk, dated April 14, 2014, "Response to NRC Request for Additional Information, Set 17, dated March 20, 2014, related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application" In Reference 1, Exelon Generation Company, LLC (Exelon) submitted the License Renewal Application (LRA) for the Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 (BBS). In Reference 2, the NRC requested additional information to support staff review of the LRA, including a request for information (RAI B.2.1. 7-7) involving the potential for Reactor Vessel Internals components to contain cold worked materials.
September 4, 2014 U.S. Nuclear Regulatory Commission Page 2 In Reference 3, Exelon responded to Request 1 of RAI B.2.1.7-7 indicating that a detailed review would be performed to determine whether any BBS Reactor Vessel Internals components contain any materials that could be a concern due to cold working. Exelon stated that the results of this review would be communicated to the NRC by the end of October, 2014.
The detailed review for BBS has been completed. It is concluded that the plant-specific material fabrication and design were consistent with the MRP-191 basis and that the MRP-227-A sampling inspection aging management requirements, as related to cold work and stress corrosion cracking, are directly applicable to BBS. The Enclosure to this letter provides additional details.
There are no new or revised regulatory commitments contained in this letter.
If you have any questions, please contact Mr. Al Fulvio, Manager, Exelon License Renewal, at 610-765-5936.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on 'f'f' '),((~
Respectfully, Vice President - License Renewal Projects Exelon Generation Company, LLC
Enclosure:
Supplemental Information for Response to RAI B.2.1.7-7, Request 1: Results of Detailed Review Related to Potential for Cold Working of Reactor Vessel Internals Components at BBS cc: Regional Administrator- NRC Region Ill NRC Project Manager (Safety Review), NRR-DLR NRC Project Manager (Environmental Review), NRR-DLR NRC Senior Resident Inspector, Braidwood Station NRC Senior Resident Inspector, Byron Station NRC Project Manager, NRR-DORL-Braidwood and Byron Stations Illinois Emergency Management Agency - Division of Nuclear Safety
RS-14-249 Enclosure Page 1 of 2 Enclosure Supplemental Information for Response to RAI B.2.1.7-7, Request 1:
Results of Detailed Review Related to Potential for Cold Working of Reactor Vessel Internals Components at BBS
RS-14-249 Enclosure Page 2 of 2 Byron and Braidwood Stations, Units 1 and 2 (BBS) contracted with Westinghouse Electric Company LLC (Westinghouse), through the PWR Owners Group, to provide a detailed evaluation of the reactor vessel internals (RVI) for cold worked components.
Westinghouse has evaluated the BBS reactor vessel internal components according to industry guideline MRP 2013-025 [1] and the MRP-191 [2] industry generic component listings and screening criteria (including consideration of cold work as defined in MRP-175 [3], noting the requirements of Section 3.2.3). In addition to consideration of the material fabrication, forming, and finishing process, a general screening definition of a resulting reduction in wall thickness (material stock thickness) of 20 percent was applied as an evaluation limit. It was confirmed that all BBS components, as applicable for design, are included directly in the MRP-191 component lists.
BBS components were categorized according to the following categories for material fabrication and cold work potential:
Categories include:
Cast austenitic stainless steel (CASS) (Category 1)
Hot-formed austenitic stainless steel (Category 2)
Annealed austenitic stainless steel (Category 3)
Fasteners austenitic stainless steel (Category 4)
Cold-formed austenitic stainless steel without subsequent solution annealing (Category 5)
The evaluation, performed consistently with the industry guideline, concluded that the reactor vessel internals Categories 1, 2, and 3 components at BBS contain no cold work 20 percent or greater as a result of material specification and controlled fabrication construction. Material fabrication specifications used for BBS suggest that processes were limiting (e.g., heat treatment), which precluded the introduction of severe (greater than or equal to 20 percent) cold work in some of the Category 4 components. Category 4 components were already assumed to have the potential for cold work in the MRP-191 generic assessments. No Category 5 components with severe cold work were identified for BBS.
The detailed evaluation for BBS concluded that the plant-specific material fabrication and design were consistent with the MRP-191 basis and that the MRP-227-A [4] sampling inspection aging management requirements, as related to cold work and stress corrosion cracking, are directly applicable to BBS.
References:
- 2. Materials Reliability Program: Screening, Categorization, and Ranking of Reactor Internals Components for Westinghouse and Combustion Engineering PWR Design (MRP-191). EPRI, Palo Alto, CA: 2006. 1013234.