ML23212A901
| ML23212A901 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 08/03/2023 |
| From: | Robert Kuntz NRC/NRR/DORL/LPL3 |
| To: | Rhoades D Constellation Energy Generation, Constellation Nuclear |
| References | |
| EPID L-2022-LLA-0173 | |
| Download: ML23212A901 (1) | |
Text
August 3, 2023 Mr. David P. Rhoades Senior Vice President Constellation Energy Generation, LLC President and Chief Nuclear Officer Constellation Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
LASALLE COUNTY STATION, UNITS 1 AND 2 - REGULATORY AUDIT REPORT TO SUPPORT THE REVIEW OF THE AMENDMENTS TO RELOCATION OF THE PRESSURE TEMPERATURE LIMIT CURVES TO THE PRESSURE AND TEMPERATURE LIMITS REPORT (EPID L-2022-LLA-0173)
Dear Mr. Rhoades:
By application dated November 10, 2022 (Agencywide Document Access and Management System (ADAMS) Accession No. ML22332A448) as supplement by letter dated January 10, 2023 (ML23010A227) Constellation Energy Generation, LLC (Constellation) submitted a license amendment request (LAR) for LaSalle County Station, Units 1 and 2 (LaSalle). The amendment requests the relocation of the pressure temperature limit curves from the technical specifications to the pressure and temperature limits report. Due to the complex nature of this material, the U.S. Nuclear Regulatory Commission (NRC) staff conducted an audit for understanding under the Office of Nuclear Reactor Regulation guidance LIC-111, Regulatory Audits. The audit plan was provided on April 15, 2023 (ML23095A189).
The audit was conducted from April 10, 2023, through May 5, 2023, virtually using an online portal and online discussions. The purpose of the audit was to gain understanding, to verify information, and to identify information that will require docketing to support the proposed licensing actions. The enclosure to this letter provides a report of the NRC staffs audit.
D. Rhodes If you have any questions, please contact me by telephone at (301) 415-3733 or by email at Robert.Kuntz@nrc.gov.
Sincerely,
/RA/
Robert F. Kuntz, Senior Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374
Enclosure:
Audit Report cc: Listserv
REGULATORY AUDIT REPORT TO SUPPORT REVIEW OF LICENSE AMENDMENT REQUEST TO UPDATE THE PRESSURE-TEMPERATURE LIMIT CURVES FOR LASALLE COUNTY STATION, UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-374
1.0 BACKGROUND
By letter dated November 10, 2022, (Agencywide Documents and Access Management System (ADAMS) Accession No. ML22332A449), as supplemented by letter January 10, 2023 (ML23010A227), Constellation Energy Generation Company, LLC (CEG or the licensee) submitted a license amendment request (LAR) to modify the LaSalle County Station, (LaSalle) Units 1 and 2, technical specifications (TSs).
Specifically, pursuant to Title 10 of the Code of Federal Regulations, (10 CFR) section 50.90, the LAR proposed to update the pressure-temperature (P-T) limit curves to 54 effective full power years (EPFY) and to relocate the P-T limit curves into a pressure-temperature limits report (PTLR) that would be governed by proposed TS section 5.6.7. The audit was conducted via electronic portal that was established by Constellation.
The Nuclear Regulatory Commission (NRC) staff determined it would be efficient to conduct an audit in order to enable the staff to examine and evaluate information with the intent to gain understanding, verify information, and/or identify information that will require docketing to support the basis of a licensing or regulatory decision. The NRC staff performed an audit from April 12, 2023, through May 5, 2023, including an initial audit kickoff meeting that was conducted with the licensee of April 12, 2023, and a formal audit discussion (breakout) topic session that was conducted with the licensee on April 19, 2023.
The NRC staff performed and completed its audit in accordance with NRR Office Instruction LIC-111, Revision 1, Regulatory Audits (ML19226A274).
2.0 AUDIT TEAM The following NRC staff members participated in the audit:
Robert Kuntz, Project Manager James Medoff, Technical Reviewer Cory Parker, Technical Reviewer Carolyn Fairbanks, Technical Reviewer 3.0 AUDIT
SUMMARY
The audit discussions included the following audit topics for LAR or PTLR contents that would potentially be the subject of a request for additional information (RAI) on the LAR review. Based on its review of the LAR and the results of the audit the NRC staff issued a RAI to Constellation by electronic mail dated June 2, 2023 (ML23153A156). Constellation provided a response to the RAI by letter dated June 30, 2023 (ML23181A149).
3.1 RTNDT Calculations for Reactor Pressure Vessel Beltline Materials.
Regulation 10 CFR Part 50, appendix G, section IV.A, requires that the RTNDT values of ferritic reactor pressure vessel (RPV) beltline materials must account for the effects of neutron irradiation, including the results of the RPV material surveillance program. Table 7 in the LAR provided the 1/4t RTNDT values for the LaSalle Unit 1, RPV beltline materials at 54 EPFY.
The NRC staff observed table 7 in the LAR did not include an RTNDT calculation for LaSalle, Unit 1, RPV middle axial shell weld No. 3-308 BG at 54 EPFY. The licensee provided the 54 EFPY 1/4t RTNDT value for LaSalle, Unit 1, RPV middle axial shell weld No. 3-308 BG in SI Calculation 2001063.305P, Revision 2, that was posted to the audit portal.
Audit Result: The NRC staffs RAI included RAI No. LCS-PTLR-LAR-2 which requested information on the omission of a 54 EFPY 1/4t RTNDT-based line item and value for LaSalle, Unit 1 RPV middle shell axial weld 3-308 BG in Table 7 of the PTLR.
3.2 Dimensional Inputs Used for the Derivation of P-T Limit Points for Type A, B, and C P-T Limit Curves The methods in Boiling Water Reactor Owners Group (BWROG)-TP-11-022-A, Revision 1, Pressure-Temperature Limits Report Methodology for Boiling Water Reactors (ML13277A557) use component-specific design dimension values (e.g., component thickness, component inside and outside radius, and for nozzles, corner radius values) as design inputs for P-T limit calculations.
The NRC staff noted that the LAR did not identify the specific dimensional values used as inputs for the P-T limit calculations applicable to the RPV beltline shell, bottom head, N12 water level instrumentation nozzle, N6 low pressure coolant injection (LPCI) nozzle, or N2 non-beltline feedwater (FW) nozzle regions. The licensee posted SI Calculation Nos. 2001063.301, Revision 0; 2001063.302, Revision 0; and 2001063.305, Revision 2 to the audit portal. The NRC staff confirmed that these documents provide the following dimensional values:
Inside radius (Ri) values and RPV wall thickness (t) values needed for derivation of the Pallow values for the limiting RPV beltline shell and bottom head (including RPV shell plate portions associated with the non-ferritic N12 water level instrumentation nozzles) in SI Calculation No. 2001063.305, Revision 2 For RPV LPCI [low pressure coolant injection] nozzles designed with inner-blend radii analyzed by FEM modeling, component-specific dimensions defined for the nozzle type in Section 4.2 of SI Calculation No.
2001063.302, Revision 0, including (but not limited to) dimensions for the nozzle forging inner diameter and nozzle forging outer diameter (and nozzle forging outer diameter at the safe end location).
The NRC staff observed that neither SI Calculation No. 2001063.301 nor SI Calculation No. 2001063.305, Revision 2, included any component-specific dimension values that were used for derivation of the P-T limit curves for the RPV FW nozzles.
Audit Result: The NRC staffs RAI included RAI No. LSCS-PTLR-LAR-1 requesting information on the component-specific dimension values that were used as inputs for the P-T limit curves that applied to the LaSalle, Unit 1 and 2 FW, nozzles.
3.3 SI Calculational Basis Used to Derive Set of Composite P-T Limit Curves The LAR indicates that the P-T limit curves were calculated in accordance with the methodology in BWROG Report No. BWROG-TP-11-022-A, Revision 1. The LAR indicates that the composite P-T limit curves are based on the calculations provided in SI Calculation No. 2001063.305, Revision 1. The January 10, 2023, supplement to the LAR indicates that the composite P-T limit curves are based on calculations provided in SI Calculation No. 2001063.305, Revision 1. Information in the LAR supplement supersedes information in the LAR.
The NRC staff observed the licensee posted SI Calculation 2001063.305, Revision 2, on the portal. In its review of this calculation, the NRC staff observed that clarification on whether SI Calculation 2001063.305, Revision 1, or SI Calculation 2001063.305, Revision 2, provides the latest P-T limit calculational basis used for development of the composite P-T limit curves provided and included in the LAR and which version of the calculation should be referenced in the body and Reference section of the PTLR that was included in the LAR.
Audit Result: The NRC staffs RAI included RAI No. LSCS-PTLR-LAR-3 to clarify if the non-docketed SI Calculation No. 2001063.305 should be referenced in the PTLR for the set of composite P-T limit curves that were included in the PTLR and whether the current set of P-T limit curves provided in the January 10, 2023, version of PTLR are consistent with the latest version of SI Calculation No. 2001063.305 used for the P-T limit calculations.
4.0 DOCUMENTS REVIEWED The following documents were reviewed by the NRC staff during the audit:
Record Type and Number Title Record Revision or Date1
- 1. Structural Integrity Associates (SI)
Calculation Package No. 2001063.305 LaSalle Units 1 and 2 P-T Curve Calculation for 54 EFPY Revision 2, April 10, 20231
- 2. SI Proprietary Calculation Package No. 2001063.304P Evaluation of Adjusted Reference Temperatures and Reference Temperature Shifts Revision 2, March 31, 20231 Record Type and Number Title Record Revision or Date1
- 3. SI Proprietary Calculation Package No. 2001063.302 Low Pressure Coolant Injection Nozzle Fracture Mechanics Evaluation for Pressure-Temperature Limit Curve Development Revision 0, October 10, 20221
- 4. SI Proprietary Calculation Package No.
2001063.301 Feedwater Nozzle Fracture Mechanics Evaluation for Pressure-Temperature Limit Curve Development Revision 0, October 10, 20221 Notes: 1. Specified date is the date of the SI managerial signoff in approval of the SI calculational record.
5.0 AUDIT CONCLUSION The purpose of the audit was to gain understanding, to verify information, and to identify information that will require docketing to support the proposed licensing action. As a result of the audit and the NRC staffs review of the LAR, the NRC staff issued the RAI dated June 2, 2023.
Date: August 3, 2023
ML23212A901 NRR-106 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DNRL/NVIB/BC NAME RKuntz SRohrer ABurford DATE 7/31/2023 7/31/2023 7/28/2023 OFFICE NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME JWhited RKuntz DATE 8/3/2023 8/3/2023