NL-24-0406, Response to Request for Additional Information Related to Proposed Alternative GEN-ISI-AL T-2024-003
| ML24320A121 | |
| Person / Time | |
|---|---|
| Site: | Farley, Vogtle  |
| Issue date: | 11/15/2024 |
| From: | Coleman J Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-24-0406 | |
| Download: ML24320A121 (1) | |
Text
._ Southern Nuclear November 15, 2024 Docket Nos.: 50-348 50-424 50-364 50-425 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Regulatory Affairs Joseph M. Farley Nuclear Plant, Units 1 and 2 Vogtle Electric Generating Plant, Units 1 and 2 Response to Request for Additional Information 3535 Colonnade Parkway Birmingham, AL 35243 205 992 5000 NL-24-0406 Related to Proposed Alternative GEN-ISi-AL T-2024-003 Ladies and Gentlemen:
By letter dated July 3, 2024 (Agencywide Document Access and Management System Accession Number ML24185A245) Southern Nuclear Operating Company submitted to the United States Nuclear Regulatory Commission (NRC) a proposed alternative, Alternative GEN-ISi-AL T-2024-003, to the inservice inspection (ISi) requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI regarding the pressurizer (PZR) welds at Joseph M. Farley Nuclear Plant, Units 1 and 2 and Vogtle Electric Generating Plant, Units 1 and 2. The proposed alternative requests to increase the inspection interval of ASME Section XI Table IWB-2500-1 Examination Category B-B for item numbers B2.11 and B2.12, and Examination Category B-B for item number B3.110 from every ISi interval to every other interval.
By email dated October 16, 2024, the US NRC notified SNC that additional information is needed for the staff to perform their review.
The enclosure to this letter provides the SNC Responses to the NRC Request for Additional Information (RAI).
This letter contains no NRC commitments. If you have any questions, please contact Ryan Joyce at 205.992.6468.
U. S. Nuclear Regulatory Commission NL-24-0406 Page 2 Respectfully submitted, Regulatory Affairs Director JMC/jdj/cbg
Enclosure:
Response to Request for Additional Information cc:
Regional Administrator, Region II NRR Project Manager - Farley and Vogtle 1 & 2 Senior Resident Inspector -
Farley and Vogtle 1 & 2 RType: CGA02.001
Joseph M. Farley Nuclear Plant, Units 1 and 2 Vogtle Electric Generating Plant, Units 1 and 2 Response to Request for Additional Information Related to Proposed Alternative GEN-ISi-AL T-2024-003 Enclosure Response to Request for Additional Information
Enclosure to NL-24-0406 Response to Request for Additional Information REQUEST FOR ADDITIONAL INFORMATION (RAI)
By letter dated July 3, 2024, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24185A245), Southern Nuclear Operating Company (SNC, the licensee) submitted a proposed alternative, Alternative GEN-ISi-AL T-2024-003, to the inservice inspection (ISi) requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI regarding the pressurizer (PZR) welds at Joseph M. Farley Nuclear Plant (Farley), Units 1 and 2, and Vogtle Electric Generating Plant (Vogtle ), Units 1 and 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations, Part 50, Section 55a, Paragraph (z)(1) (10 CFR 50.55a(z)(1 )), the licensee is proposing to perform the required volumetric examinations of the subject PZR welds every other ISi interval, rather than the ASME Code Section XI requirement of every ISi interval. SNC referred to the results of the probabilistic fracture mechanics (PFM) analyses in the following Electric Power Research Institute (EPRI) non-proprietary report as the primary basis for proposed alternative:
EPRI Technical Report 3002015905, "Technical Bases for Inspection Requirements for PWR Pressurizer Head, Shell-to-Head, and Nozzle-to-Vessel Welds," 2019 (hereinafter referred to as "EPRI report 15905," ADAMS Accession No.ML21021A271 ).
To complete its review, the Nuclear Regulatory Commission (NRC) staff requests for additional information as shown below.
Regulatory Basis Regulatory Requirement The NRC has established requirements in 10 CFR Part 50 to protect the structural integrity of structures and components in nuclear power plants. Among these requirements are the ISi requirements of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a to ensure that adequate structural integrity of PZRs (including their welds) is maintained through the service life of the vessels. Therefore, the regulatory basis for the following request for additional information (RAI) is related to demonstrating that the proposed alternative ISi requirements would ensure adequate structural integrity of the licensee's PZR welds, and thereby would provide an acceptable level of quality and safety per 10 CFR 50.55a(z)(1 ).
RAl-1 Issue The licensee provides tables listing the affected welds at each unit in Enclosure 1, pages E1-1 through E1-3 of the proposed alternative GEN-ISi-AL T-2024-003. The component ID number provided for the Vogtle Unit 2 PZR Bottom Head to Lower Shell weld, the PZR Upper Shell to Top Head weld, the PZR Lower Shell Long Seam weld, and the PZR Upper Shell Long Seam weld are identified, as 11201-V6-002-W01, 11201-V6-002-W05, 11201-V6-002-W06, 11201-V6-002-W09, respectively. Those component ID numbers are identical to the component ID numbers provided for the Vogtle Unit 1 Upper Head To Upper Shell weld, the Lower shell to Lower Head weld, the Upper Shell Longitudinal Weld, and the Lower Shell Longitudinal Weld.
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Enclosure to NL-24-0406 Response to Request for Additional Information However, they differ from the Component ID numbers given in the table on pages E1-15 and E1-16 where the next scheduled examination for each component at Vogtle, Units 1 and 2, are listed.
Request Clarify the Component ID numbers for the Exam Category B2.11 and B2.12 components or welds at Vogtle, Units 1 and 2, on pages E1-1 to E1-3 and E1-15 and E1-16 and verify the other information provided, specifically the inspection dates, are correct.
SNC Response to RAl-1:
On page E 1-2 of the proposed alternative for the Vogtle Electric Generating Plant Unit 2 Components Affected Table, for ASME Item Nos B2.11 and B2.12, there were unit 2 components that were mislabeled in the original submittal. The correct component IDs and description are included below for Item Nos. B2.11 and B2.12 Vogtle Electric Generating Plant Unit 2 (VEGP2)
ASME ASME Item No.
Component ID Component Description Category B-B B2.11 21201-V6-002-Upper Head to Upper Shell Weld W01 B-B B2.11 21201-V6-002-Lower Shell to Lower Head Weld wos B-B B2.12 21201-V6-002-Upper Shell Longitudinal Weld W06 B-B B2.12 21201-V6-002-Lower Shell Longitudinal Weld W09 B-D B3.110 21201-V6-002-Upper Head to 6" Safety Nozzle Weld W10 B-D B3.110 21201-V6-002-Upper Head to 6" Safety Nozzle Weld W11 B-D B3.110 21201-V6-002-Upper Head to 6" Safety Nozzle Weld W12 B-D B3.110 21201-V6-002-Upper Head to 6" Safety Nozzle Weld W13 B-D B3.110 21201-V6-002-Upper Head to 4" Safety Nozzle Weld W14 B-D B3.110 21201-V6-002-14" Surge Nozzle Weld to Lower Head W16 All other information on pages E1-1 through E1-3 in the original submittal is correct.
Additionally, the information including the inspection dates on pages E1-15 and E1-16 is correct.
RAl-2 Issue The subject alternative is proposed through the end of the sixth ISi interval for Farley, Units 1 and 2. Specifically, the alternative is requested through November 30, 2037, for Farley, Units 1 and 2. The operating license for Farley, Unit 1, expires June 25, 2037. The NRC staff notes that it cannot authorize an alternative request beyond the existing plant license date.
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Enclosure to NL-24-0406 Response to Request for Additional Information Request Confirm the understanding that NRC approval of the alternative can only be authorized until the end of the currently issued license. Revise the submittal, as necessary, to address the inconsistency between the requested duration of the proposed alternative and expiration of the operating license for Farley, Unit 1.
SNC Response to RAl-2:
The Farley Unit 1 operating license is set to expire June 25, 2037. This alternative requests to not perform examinations, as normally scheduled during the 5th interval 3rd period, 6th interval 1st period, and 6th interval 2nd period. Examinations will resume in accordance with the ASME Section XI Code in the 6th interval 3rd period for Farley Unit 1 which begins 12/1/2035 when applying ASME Code Case N-921. Since examinations will resume in the 3rd period of the 6th interval which is prior to the license expiration date, the applicability of this request only extends through the end of the 6th interval 2nd period which ends 11/30/2035, which is prior to the license expiration date even while applying ASME Section XI 1-year grace periods.
Issue On page E 1-12 of the proposed alternative dated July 3, 2024, SNC states that scope expansion will be performed in accordance with the ASME Section XI code of record. This description of the approach to scope expansion lacks detail and may be inconsistent with that approved by the NRC staff in prior similar alternatives. The safety evaluation (SE) dated July 22, 2024 (ML24194A022) which approved the alternative proposed by letter dated November 1, 2023 (ML23305A069), and supplemented by letter dated March 22, 2024 (ML24082A185),
provides an example of on an approach to scope expansion that the NRC staff has previously found to be acceptable.
Request (a) If indications are detected that exceed the acceptance standards of ASME Code,Section XI, IWB-3500, confirm that it will be evaluated as required by ASME Code,Section XI (which includes requirements for successive inspections and additional examinations). Describe and justify other actions (if any) specified in the plant's corrective action program to ensure that the integrity of the component is adequately maintained.
(b) If indications are detected that exceed the acceptance standards of ASME Code,Section XI, IWB-3500, then scope expansion may be appropriate to assess extent of condition.
Furthermore, if industry-wide operating experience indicates that a new or novel degradation mechanism is possible in PZR welds, scope expansion may be appropriate to ensure that no such mechanism is occurring in the subject plants. Discuss and justify the detailed scope expansion plans for these scenarios.
SNC Response to RAl-3(a):
If, during the examinations outlined in the alternative Next Scheduled Examinations (ref.
ML24185A245 pgs. E-13 thru E-16), indications are detected that exceed the applicable ASME Code,Section XI acceptance standards of IWB-3500, then the indications will be addressed as E-3
Enclosure to NL-24-0406 Response to Request for Additional Information required by the ASME Code Section XI code of record at the time of the inspection, and the Southern Nuclear Corrective Action Program. The additional examination requirements of the ASME Code,Section XI, also apply during the current outage. The number of additional exams scheduled as a result of the original exam that exceeded ASME Code acceptance criteria shall be in accordance with IWB-2430. If additional examinations reveal indications exceeding acceptance standards of IWB-3500, the examinations shall be further extended to include all remaining welds/components for that ASME inspection item number. Successive examinations will be performed in accordance with the ASME Section XI code of record.
SNC Response to RAl-3(b):
Any unacceptable indication(s) identified during examinations will result in additional and successive inspection requirements of ASME Code,Section XI IWB-2420 and IWB-2430. The expanded scope shall include the weld/component(s) as required by ASME Code,Section XI.
Additional and successive inspection requirements of ASME Code,Section XI apply for all newly identified unacceptable indications.
If industry-wide operating experience indicates that a new or novel degradation mechanism is possible in PZR welds, the operating experience will be evaluated for applicability in accordance with the corrective action program and the operating experience program, and scope expansion will be performed as applicable, based on the evaluation results.
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