RS-23-040, Constellation Energy Generation, LLC, Supplemental Information - Proposed Alternatives Related to the Steam Generators
| ML23052A068 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs, Byron, Braidwood, Ginna  |
| Issue date: | 02/21/2023 |
| From: | Reddick D Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RS-23-040 | |
| Download: ML23052A068 (1) | |
Text
200 Exelon Way Kennett Square, PA 19348 www.constellation.com 10 CFR 50.55a RS-23-040 February 21, 2023 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Renewed 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 Renewed Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN-50-455 Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318 R. E. Ginna Nuclear Power Plant Renewed Facility Operating License Nos. DPR-18 NRC Docket Nos. 50-244
Subject:
Supplemental Information - Proposed Alternatives Related to the Steam Generators
References:
- 1) Letter from D. Gudger (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, Proposed Alternative for Examinations of Examination Category C-B Steam Generator Nozzle-to-Shell Welds and Nozzle Inside Radius Sections, dated September 1, 2021 (ML21244A328).
- 2) Email from J. Wiebe (U.S. Nuclear Regulatory Commission) to T. Loomis (Constellation Energy Generation, LLC), Final RAIs 9.1.2021 Constellation Relief Request, dated May 6, 2022 (ML22271A077).
- 3) Letter from D. Gudger (Constellation Energy Generation, LLC) to U.S.
Nuclear Regulatory Commission, Response to Request for Additional Information - Proposed Alternative for Examinations of Examination Category C-B Steam Generator Nozzle-to-Shell Welds and Nozzle Inside Radius Sections, dated May 20, 2022 (ML22140A055).
- 4) Letter from D. Gudger (Exelon Generation Company, LLC) to U.S.
Nuclear Regulatory Commission, Proposed Alternative for Examinations of Examination Categories B-B, B-D, and C-A Steam Generator Pressure Retaining Welds and Full Penetration Welded Nozzles, dated December 14, 2021 (ML21348A078).
Supplemental Information - Proposed Alternatives Related to the Steam Generators February 21, 2023 Page 2
- 5) Email from J. Wiebe (U.S. Nuclear Regulatory Commission) to T. Loomis (Constellation Energy Generation, LLC), Draft RAIs for Requests for Alternatives I4R-17, I4R-23, ISI-05-018, I6R-10 (EPID Nos.: L-2021-LLR-091, L-2021-LLR-092, L-2021-LLR-093, L-2021-LLR-094), dated May 6, 2022 (ML22129A013).
- 6) Letter from D. Gudger (Constellation Energy Generation, LLC) to U.S.
Nuclear Regulatory Commission, Response to Request for Additional Information - Proposed Alternative for Examinations of Examination Categories B-B, B-D, and C-A Steam Generator Pressure Retaining Welds and Full Penetration Welded Nozzles, dated June 17, 2022 (ML22168A005).
- 7) Letter from D. Reddick (Constellation Energy Generation, LLC) to U.S.
Nuclear Regulatory Commission, Supplemental Information - Proposed Alternatives Related to the Steam Generators and Request for Forward Fit Analysis, dated September 20, 2022 (ML22263A440).
Proposed Performance Monitoring Plan In the Referenced letters (References 1 and 4), Constellation Energy Generation, LLC (CEG) submitted proposed alternatives associated with examination of steam generator (SG) welds and components at Braidwood Generating Station (Braidwood), Units 1 and 2, Byron Generating Station (Byron), Units 1 and 2, Calvert Cliffs Nuclear Power Plant (Calvert Cliffs),
Units 1 and 2, and R. E. Ginna Nuclear Power Plant (Ginna). In References 3 and 6, CEG provided RAI responses, including a proposed performance monitoring plan. In Reference 7, CEG provided a revised performance monitoring plan for the Reference 4 proposed alternative.
On January 30, 2023, a public meeting was held between the NRC and CEG to discuss the status of the Reference 1 and 4 submittals. In the public meeting, the NRC inferred that the CEG performance monitoring plan provided to date was insufficient to detect the potential emergence of a novel degradation mechanism in steam generator welds if examinations extended beyond 20 years. The NRC indicated that 20 years between exams was not a requirement and that examinations extending beyond 20 years would be considered with sufficient justification. The NRC stated that a duration of up to 21.5 years between examinations associated with the Reference 1 submittal for Calvert Cliffs Unit 2 Category C-B feedwater nozzle components was acceptable with no performance monitoring requirements. Based upon the information gathered in the January 30, 2023 public meeting, CEG has developed a revised performance monitoring plan for the Reference 1 and 4 proposed alternatives for welds and components extending examinations beyond approximately 20 years. This revised performance monitoring plan supplements the previous responses provided in References 3, 6, and 7 with additional welds selected for examination. The revised performance monitoring plan also supplements the results of the deterministic fracture mechanics (DFM) and probabilistic fracture mechanics (PFM) evaluations of EPRI Reports 3002015906 and 3002014590, which demonstrate that the steam generator welds and components are very flaw tolerant. The performance monitoring plan provided in this letter will validate the continued adequacy of the PFM model and verify that no unexpected degradation mechanisms have developed over time.
Supplemental Information - Proposed Alternatives Related to the Steam Generators February 21, 2023 Page 3 As shown in Table 1 of References 1 and 4, requested deferrals from 23.5 years up to 36 years were requested for various steam generator welds and components associated with Braidwood, Units 1 and 2, Byron, Units 1 and 2, and Calvert Cliffs, Unit 2. The requested deferral for all welds and components associated with Calvert Cliffs, Unit 1, and Ginna are below approximately 20 years (maximum deferral of 21.5 years) between examinations and as such do not require any performance monitoring.
As a performance monitoring plan for Braidwood, Units 1 and 2, Byron, Units 1 and 2, and Calvert Cliffs, Unit 2, CEG will examine all welds and components associated with one steam generator at Braidwood, Unit 1, to the maximum extent possible. The components to be examined are described in the Table below.
Description Number and Type of Exam B-B B2.40 Tubesheet-to-Head Weld 1 Volumetric (UT)
C-A C1.10 Shell Circumferential Weld 2 Volumetric (UT)
C-A C1.20 Head Circumferential Weld 1 Volumetric (UT)
C-A C1.30 Tubesheet-to-Shell Weld 1 Volumetric (UT)
C-B C2.21 Nozzle-to-Shell Weld 1 Volumetric (UT) &
C-B C2.22 Nozzle Inside Radius Section 1 Volumetric (UT)
The proposed performance monitoring plan for Braidwood, Unit 1, will be performed by the end of 2030. This will ensure that no more than 20 years elapses between the performance of an ASME Code,Section XI, examination for any of the welds and components required to be examined at Braidwood, Unit 1. Following completion of the Braidwood, Unit 1 performance monitoring examinations by the end of 2030, none of the CEG units covered by the proposed alternatives will operate for more than 20 years before the end of the current operating license; therefore, no additional performance monitoring examinations are required.
With the proposed CEG performance monitoring plan provided in this letter an examination of all welds and components required to be examined by ASME Code,Section XI, for the Braidwood, Unit 1 steam generators will be performed during the analytically determined safe operating period for Braidwood, Unit 1. This represents a sample of one (1) of five (5) CEG units requiring performance monitoring, examinations extending beyond 20 years, completing an examination of all ASME Code,Section XI, required welds and components during the analytically justified deferral period.
The Braidwood, Unit 1 steam generator welds and components selected for examination as part of the performance monitoring plan are considered representative of the remaining welds and components covered by the proposed alternative (e.g., similar materials, construction methods, service conditions) for steam generators across the various PWR designs. Given the number of examinations and the representative nature of the components selected, the performance monitoring plan is considered adequate to represent the material condition of the other CEG units covered by the proposed alternative.
Performing an examination of all ASME Code,Section XI, welds and components at Braidwood, Unit 1, will provide direct evidence to the presence or extent of any unexpected degradation experienced by these components.
In the unlikely event that any new unacceptable indications (i.e., indications exceeding the acceptance standards of IWB-3500 or IWC-3500, as applicable, that are accepted by Repair/Replacement Activity or analytical evaluation) are identified during the performance
Supplemental Information - Proposed Alternatives Related to the Steam Generators February 21, 2023 Page 4 monitoring plan at Braidwood, Unit 1, the indications will be evaluated as required by ASME Code,Section XI, and the CEG corrective action program. The additional examination and successive inspection requirements of ASME Code,Section XI, also apply. Any new unacceptable indications identified as part of the performance monitoring plan at Braidwood, Unit 1, will result in the same population of welds being examined at Braidwood, Unit 2, Byron, Units 1 and 2, and Calvert Cliffs, Unit 2, during the next regularly scheduled outage.
In addition to the direct evidence provided by the performance monitoring examinations at Braidwood, Unit 1, examination of steam generator welds and components is expected to continue to be performed by other units across the domestic and international PWR fleet. In the United States there are currently 61 operating PWR Units with approximately 200 steam generators in service. To date, we estimate that 29 of the operating PWR Units in the United States have submitted or received approval to implement an alternative based on EPRI Report 3002015906 and/or 3002014590. Thirty-two (32) PWR Units, or 52% of the domestic fleet, are required by regulation to follow the ASME Code,Section XI, steam generator examination requirements for the foreseeable future. Based on the sampling nature of ASME Code,Section XI, this is an additional estimated 32 steam generators worth of examinations that will provide opportunities to detect known degradation mechanisms, as described in Section 6.0 of the EPRI Reports, and will also provide the opportunity to detect any new or unexpected degradation mechanisms that may occur in the future for the subject components. This estimation does not include any performance monitoring that may be required as part of the approval process for the 29 units seeking similar alternatives. If a new degradation mechanism is identified during continued industry examinations, CEG will follow the industry guidance to address the new degradation mechanism.
The absence of any new unacceptable indications in the Braidwood, Unit 1, performance monitoring examinations and the absence of any unexpected degradation across the operating fleet provides validation that the assumptions and methods of the PFM Model used in the EPRI Reports are adequate to predict the future behavior of the subject welds and components. The strong technical basis provided by the results of the PFM Model and EPRI Report, along with the implementation of the proposed performance monitoring plan, including scope expansion criteria, will provide additional assurance that the steam generator welds and components at Braidwood, Units 1 and 2, Byron, Units 1 and 2, and Calvert Cliffs, Unit 2, can operate safely for the remainder of plant life and will continue to provide an acceptable level of quality and safety.
With regards to the Reference 4 proposed alternative, Ginna is requesting approval prior to the upcoming refueling outage (April 2023) to avoid a potential non-compliance with the requirements of ASME Code,Section XI, Paragraph IWC-2411(a), in conjunction with Table IWC-2411-1. Ginna previously extended the first inspection period, as allowed by Paragraph IWA-2430(c)(3), to create an overlap between the first and second inspection periods allowing examinations performed during the 2023 refueling outage to be credited to either the first or second inspection period, but not both. This extension was applied to the Category C-A components and examinations, to allow sufficient time for the NRC to review and approve the Reference 4 alternative so that these examinations could be deferred to the end of the current operating license. Table IWC-2411-1 requires a minimum of 16% of the Category C-A welds to be performed during the first inspection period. Ginna currently has three (3) of the four (4) Category C-A steam generator welds scheduled for examination in the 2023 refueling outage. Ginna also has one (1) Category B-B examination scheduled which is included within the scope of the Reference 4 proposed alternative. The 2023 refueling outage is the last opportunity to credit any examinations to the first inspection period for Category C-A as the rules of IWC-2430(c)(3) do not allow the first period to be
Supplemental Information - Proposed Alternatives Related to the Steam Generators February 21, 2023 Page 5 extended more than one year to incorporate another refueling outage. If the Reference 4 proposed alternative is not approved prior to the 2023 refueling outage, Ginna will be required to perform at least one (1) Category C-A steam generator examination to ensure continued compliance with ASME Section XI, Table IWC-2411-1, for the first inspection period. Performing any of the Category C-A steam generator examinations during the 2023 refueling outage will eliminate the benefit of the Reference 4 proposed alternative for Ginna. Due to common support tasks (scaffold, insulation removal, etc.) and personnel to access and examine the Category B-B and Category C-A steam generator welds, there is little benefit to examining only one Category C-A weld to maintain compliance with Table IWC-2411-1; therefore, all four (4) examinations would likely be performed in order to take full advantage of the common support tasks. It should be noted that none of the Ginna steam generator welds included in the Reference 4 proposed alternative extend beyond 20 years between exams (max 16.9 years); therefore, approval of the proposed alternative prior to upcoming outage at Ginna is necessary in order to realize the full advantage provided through this alternative.
The Attachment contains a regulatory commitment.
If you have any questions or require additional information, please contact Tom Loomis at Thomas.loomis@constellation.com.
Respectfully, Darani M. Reddick Director - Licensing Constellation Energy Generation, LLC
Attachment:
Summary of Commitments cc:
Regional Administrator - NRC Region I Regional Administrator - NRC Region III NRC Senior Resident Inspector - Braidwood Station NRC Senior Resident Inspector - Byron Station NRC Senior Resident Inspector - Calvert Cliffs Nuclear Power Plant NRC Senior Resident Inspector - R. E. Ginna Nuclear Power Plant NRC Project Manager - Braidwood Station NRC Project Manager - Byron Station NRC Project Manager - Calvert Cliffs Nuclear Power Plant NRC Project Manager - R. E. Ginna Nuclear Power Plant Illinois Emergency Management Agency - Division of Nuclear Safety S. Seaman, State of Maryland A. L. Peterson, NYSERDA
- Reddick, Darani M.
Digitally signed by Reddick, Darani M.
Date: 2023.02.21 10:05:00 -05'00'
Supplemental Information - Proposed Alternatives Related to the Steam Generators February 21, 2023 Page 6 bcc:
Sr. Vice President, Northeast Operations Sr. Vice President, Mid-Atlantic Operations Sr. Vice President, Midwest Operations Vice President, Nuclear Security and Licensing Site Vice President, Braidwood Station Site Vice President, Byron Station Site Vice President, Calvert Cliffs Nuclear Power Plant Site Vice President, R. E. Ginna Nuclear Station Director, Organizational Performance & Regulatory - Braidwood Station Director, Organizational Performance & Regulatory - Byron Station Director, Organizational Performance & Regulatory - Calvert Cliffs Director, Organizational Performance & Regulatory - R. E. Ginna Nuclear Power Plant Regulatory Assurance Manager, Braidwood Station Regulatory Assurance Manager, Byron Station Regulatory Assurance Manager, Calvert Cliffs Nuclear Power Plant Regulatory Assurance Manager, R. E. Ginna Nuclear Power Plant Licensing Managers (Calvert Cliffs/Ginna) - KSA Licensing Manager (Braidwood/Byron) - Cantera Commitment Coordinator - East Commitment Coordinator - West Licensing Records - KSA
Summary of Commitments Page 1 Attachment Summary of Commitments The following table identifies commitments made in this document. (Any other actions discussed in the submittal represent intended or planned actions. They are described to the NRC for the NRCs information and are not regulatory commitments.)
COMMITMENT COMMITTED DATE OR OUTAGE COMMITMENT TYPE ONE-TIME ACTION (Yes/No)
Programmatic (Yes/No)
As a performance monitoring plan CEG will examine all welds and components associated with one steam generator at Braidwood Unit 1, to the maximum extent possible.
Any new unacceptable indications identified as part of the performance monitoring plan at Braidwood, Unit 1 will result in the same population of welds being examined at Braidwood, Unit 2, Byron, Units 1 and 2, and Calvert Cliffs, Unit 2 during the next regularly scheduled outage.
The components available for examination are provided in the table below.
The required examinations will be completed by the end of 2030 to ensure that no more than 20 years elapses between the performance of an ASME Code,Section XI, examination for any of the welds and components required to be examined at Braidwood, Unit 1.
Yes No Unit SG Component ID Item Number Description 1
A 1SG-05-SGC-01 B2.40 Primary Head - Tubesheet 1
A 1SG-05-SGC-05 C1.10 Upper Secondary Shell - Shell Cone 1
A 1SG-05-SGC-06 C1.10 Shell Cone - Steam Drum Lower Shell 1
A 1SG-05-SGC-08 C1.20 Steam Drum Upper Shell - Steam Drum Head 1
A 1SG-05-SGC-02 C1.30 Tubesheet - Lower Secondary Shell 1
A 1SG-05-SGN-04 C2.21 Feedwater Nozzle 1
A 1SG-05-SGN-04 (NIR)
C2.22 Feedwater Nozzle Inner Radius 1
B 1SG-06-SGC-01 B2.40 Primary Head - Tubesheet 1
B 1SG-06-SGC-05 C1.10 Upper Secondary Shell - Shell Cone 1
B 1SG-06-SGC-06 C1.10 Shell Cone - Steam Drum Lower Shell 1
B 1SG-06-SGC-08 C1.20 Steam Drum Upper Shell - Steam Drum Head 1
B 1SG-06-SGC-02 C1.30 Tubesheet - Lower Secondary Shell 1
B 1SG-06-SGN-04 C2.21 Feedwater Nozzle 1
B 1SG-06-SGN-04 (NIR)
C2.22 Feedwater Nozzle Inner Radius
Summary of Commitments Page 2 Unit SG Component ID Item Number Description 1
C 1SG-07-SGC-01 B2.40 Primary Head - Tubesheet 1
C 1SG-07-SGC-05 C1.10 Upper Secondary Shell - Shell Cone 1
C 1SG-07-SGC-06 C1.10 Shell Cone - Steam Drum Lower Shell 1
C 1SG-07-SGC-08 C1.20 Steam Drum Upper Shell - Steam Drum Head 1
C 1SG-07-SGC-02 C1.30 Tubesheet - Lower Secondary Shell 1
C 1SG-07-SGN-04 C2.21 Feedwater Nozzle 1
C 1SG-07-SGN-04 (NIR)
C2.22 Feedwater Nozzle Inner Radius 1
D 1SG-08-SGC-01 B2.40 Primary Head - Tubesheet 1
D 1SG-08-SGC-05 C1.10 Upper Secondary Shell - Shell Cone 1
D 1SG-08-SGC-06 C1.10 Shell Cone - Steam Drum Lower Shell 1
D 1SG-08-SGC-08 C1.20 Steam Drum Upper Shell - Steam Drum Head 1
D 1SG-08-SGC-02 C1.30 Tubesheet - Lower Secondary Shell 1
D 1SG-08-SGN-04 C2.21 Feedwater Nozzle 1
D 1SG-08-SGN-04 (NIR)
C2.22 Feedwater Nozzle Inner Radius