ML23137A077
| ML23137A077 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 02/01/2023 |
| From: | Lauren Gibson NRC/NRR/DNRL/NLRP |
| To: | Rhoades D Constellation Energy Generation |
| References | |
| EPID L-2022-RNW-0011, EPID L-2022-RNW-0010 | |
| Download: ML23137A077 (7) | |
Text
February 1, 2023 Mr. David Rhoades Senior Vice President Constellation Energy Generation, LLC President and Chief Nuclear Officer (CNO)
Constellation Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
BRAIDWOOD STATION, UNIT 1, AND BYRON STATION, UNIT 1, AUDIT REPORT REGARDNG THE RESPONSE TO LICENSE RENEWAL COMMITMENT 10 (EPIDS: L-2022-RNW-0010 AND L-2022-RNW-0011)
Dear Rhoades:
By letter dated June 7, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22158A294), Constellation Energy Generation, LLC (CEG),
submitted to the U.S. Nuclear Regulatory Commission (NRC or staff) a response to Commitment 10 of the Braidwood Station, Unit 1 and Byron Station, Unit 1 license renewal safety evaluation report. In December 2015, the NRC published the final Safety Evaluation Report Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2, as NUREG-2190, Volume 1 (ML15350A038) and NUREG-2190, Volume 2 (ML15350A041). In NUREG-2190, Volume 2, Appendix A, Byron Station Units 1 and 2, and Braidwood Station, Units 1 and 2, License Renewal Commitments, Commitment 10 parts 1 and 2 gave the stations three options to fulfill this commitment. Braidwood Unit 1 and Byron Unit 1 selected Option 2 : Analysis, and Option 2: Analysis - Susceptibility, to fulfill Commitment 10 parts 1 and 2, respectively.
The NRC staff completed its audit from October 3, 2022 - November 10, 2022, in accordance with the audit plan (ML22265A013). The audit report is enclosed.
If you have any questions, please contact me by email at Lauren.Gibson@nrc.gov.
Sincerely,
/RA/
Lauren Gibson, Chief License Renewal Projects Branch Division of New and Renewed Licenses Office of Nuclear Reactor Regulation Docket Nos. 50-456 and 50-454
Enclosure:
Audit Report cc w/encl.: Listserv
Pkg: ML23137A068 Letter: ML23137A077 Audit Questions: ML23137A078
- via email NRR-106 OFFICE NRR/DNRL: PM NRR/DNRL: PM NRR/DNRL: LA NAME CTyree MYoo SGreen DATE 01/27/2023 01/31/2023 01/30/2023 OFFICE NRR/DNRL: BC NRR/DNRL: BC NAME SBloom LGibson DATE 01/31/2023 02/01/2023
Enclosure U.S. NUCLEAR REGULATORY COMMISSION AUDIT REPORT OF BYRON STATION, UNIT 1 AND BRAIDWOOD STATION, UNIT 1 STEAM GENERATOR LICENSE RENEWAL RESPONSE TO COMMITMENT 10 October 3, 2022 - November 10, 2022 List of Participants NRC Andy Johnson, Senior Materials Engineer Angela Wu, Project Manager Christopher Tyree, Project Manager David Rudland, Senior Technical Advisor Gregory Makar, Materials Engineer Lauren Gibson, Branch Chief Leslie Terry, Materials Engineer Paul Klein, Senior Materials Engineer Steven Bloom, Branch Chief Vaughn Thomas, Project Manager Constellation Anas Drief Brian Seawright Carl Friant Edward Englert Elliott Keller Gerald Armstrong Lisa Zurawski Patrick Creegan Richard Schliessman Zoe Cox BWXT Derek Hartman Mario Gogic Paul Neubrand Robert MacEacheron Stephen Fluit I.
BACKGROUND By letter dated June 7, 2022 (ML22158A294), Constellation Energy Generation, LLC (CEG),
submitted to the U.S. Nuclear Regulatory Commission (NRC or staff) a response to Commitment 10 of the Braidwood Station, Unit 1 and Byron Station, Unit 1 license renewal safety evaluation report. In December 2015, the NRC published the final Safety Evaluation Report Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2, as NUREG-2190, Volume 1 (ML15350A038) and NUREG-2190, Volume 2 (ML15350A041). In NUREG-2190, Volume 2, Appendix A, Byron Station Units 1 and 2, and Braidwood Station, Units 1 and 2, License Renewal Commitments, Commitment 10 parts 1 and 2 each provide for three options to fulfill this commitment. For Braidwood Unit 1 and Byron Unit 1, the licensee selected Option 2: Analysis, and Option 2: Analysis - Susceptibility, to fulfill Commitment 10 parts 1 and 2, respectively.
I.
AUDIT ACTIVITIES AND DOCUMENTS REVIEWED On October 3 - November 10, 2022, the staff performed an audit to gain a better understanding of how CEGs Steam Generators program will (1) validate that primary water stress corrosion cracking of the divider plate welds to the primary head and tubesheet cladding is not occurring at Braidwood, Unit 1 and Byron, Unit 1, and (2) validate that primary water stress corrosion cracking of the tube-to-tubesheet welds is not occurring at Braidwood, Unit 1 and Byron, Unit 1.
During its audit, the staff interviewed CEG staff and reviewed documentation contained in the June 7, 2022, letter and provided by CEG via the ePortal.
The table below lists documents that were reviewed by the staff and were found relevant to the staffs review. The staff will document its review of this information in its safety evaluation.
Document Title Revision / Date B&W Report 222-7720-SR-1 Exelon Company, Byron & Braidwood Station, Replacement Steam Generator Design Condition Report Revision 4 /
March 2011 B&W Report 222-7720-SR-2 Exelon Company, Byron & Braidwood Stations Replacement Steam Generators, Transient Analysis Report Revision 6 /
March 2011 B&W calc 236R-B02 Byron & Braidwood, Primary Head/Tubesheet/Shell Assembly Level A to D and Fatigue Analysis for MUR Uprate Revision 1 /
September 2010 B&W calc 236R-SR-01 Exelon Byron and Braidwood Stations Unit 1, Replacement Steam Generators, MUR Power Uprate Structural Analysis Report Revision 0 /
December 2010 AREVA 18-1229648-008 Certified Design Specification for Replacement Steam Generator Byron and Braidwood Stations Unit 1 Revision 8 /
September 10 BWXT Calc M2004-B001 Byron/Braidwood Unit 1 Replacement Steam Generator - Model Development for Tubesheet/Primary Head/Divider Plate Assembly Revision 0 /
October 2020 Document Title Revision / Date BWXT Calc M2004-B002 Byron/Braidwood Unit 1 Replacement Steam Generator - Transient Analysis for Tubesheet/Primary Head/Divider Plate Assembly Revision 1 / May 2021 BWXT Calc M2004-B003 Byron/Braidwood Unit 1 Replacement Steam Generator - Flaw Analysis at Divider Plate Triple Point Revision 1 / May 2021 BWXT Calc M2004-B004 Divider Plate Crack Growth Analysis Tool Revision 0 /
December 2020 BWXT Calc M2004-B005 Byron/Braidwood Unit 1 Replacement Steam Generator - Limit Analysis for Tubesheet/Primary Head/Divider Plate Assembly with Postulated Primary Head Flaw Revision 0 /
April 2021 BWXT Report M2004-SR-01 Electric Power Research Institute, Byron/Braidwood Unit 1 - Flaw Tolerance Evaluation at Primary Head/Tubesheet/Divider Plate Triple Point Analysis Report Revision 1 /
October 2021 SGMP-IL-16-02 Changes to Aging Management Guidance for Steam Generator Channel Head Components October 2016 N/A Suzuki, K et al, Application of high strength MnMoNi steel to pressure vessels for nuclear power plant, Nuclear Engineering and Design 206 (2001), 261-2781 2001 1 Paper reviewed because licensee provided as a reference for the upper-shelf fracture toughness value used in their analysis.
II.
AUDIT QUESTIONS PROVIDED TO CEG.
To facilitate audit discussions, the NRC staff provided audit questions to CEG, and they are available in the Agencywide Documents Access and Management System Accession No. ML23030B304.
III.
AUDIT OBSERVATIONS During the audit, the staff made the following observations:
The yield and tensile strength values, and associated temperature dependencies used in the analyses are based on American Society of Mechanical Engineers Code Section III, Division 1, Appendices.
The primary head thickness near the tubesheet juncture is (( )) and the remainder of the primary head thickness is (( )).
The original design-basis analysis document qualified the steam generators at 100 percent power operation (3425 mega-watt thermal (MWt)) and for a 5 percent stretch power uprate (3600.6 MWt). The steam generators were requalified for a 2 percent measurement uncertainty recapture (MUR) power uprate (3672 MWt). Therefore, the flaw tolerance analysis was performed for the 3672 MWt conditions.
The transients for the finite element model were grouped based on whether they were affected or not by the MUR power uprate. Specifically, if the transient was not affected by the MUR, then the heat transfer coefficients (HTCs) from the original analysis were used and if they were affected, then the HTCs were recalculated for the MUR conditions.