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MONTHYEARML24087A0112024-03-23023 March 2024 NRR E-mail Capture - Draft RAIs for Reactor Coolant Pump (RCP) Relief Request (L-2024-LLR-0022) Project stage: Draft RAI 2024-03-23
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Category:E-Mail
MONTHYEARML24107A9112024-04-15015 April 2024 NRC to Fws, Follow-up on Request for Concurrence for North Anna SLR ML24107A9122024-04-11011 April 2024 Fws to NRC, Follow-up on Request for Concurrence for North Anna SLR ML24087A0102024-03-26026 March 2024 NRR E-mail Capture - Verbal Relief for North Anna Unit 1 - (ASME Code), Section XI, Subsection IWB-2430 ML24087A0112024-03-23023 March 2024 NRR E-mail Capture - Draft RAIs for Reactor Coolant Pump (RCP) Relief Request (L-2024-LLR-0022) ML24107B1562024-02-20020 February 2024 Cherokee Nation E.Toombs Na Removal Request ML23320A1122024-01-18018 January 2024 NRC to Fws, Concurrence with Endangered Species Act Determinations for North Anna Power Station, Units 1 and 2, Subsequent License Renewal, Issuance of Draft Supplemental Environmental Impact Statement, and Opportunity for Public Comment ML23355A2722023-12-21021 December 2023 NRR E-mail Capture - Schedule Revision for Emergency Preparedness Staff Augmentation Times License Amendment Request ML23318A1172023-11-13013 November 2023 NRR E-mail Capture - Formal Issuance of RAIs for North Anna Technical Support Center (TSC) License Amendment Request (LAR) (L-2023-LLA-0006) ML23257A2092023-09-14014 September 2023 NRR E-mail Capture - Formal Issuance of 2nd Round RAIs for Surry Units 1&2 and North Anna Units 1&2 Emergency Plans LAR ML23243A9862023-08-31031 August 2023 NRR E-mail Capture - Draft RAIs for EP Staff Augmentation Times LAR (L-2022-LLA-0166) ML23219A1602023-08-0707 August 2023 003 Radiation Safety Baseline Inspection Information Request ML23171B0522023-06-20020 June 2023 NRR E-mail Capture - RAI for Review of Appendix F to DOM-NAF-2-P (Redacted) ML23075A0232023-03-15015 March 2023 NRR E-mail Capture - RAI - License Amend Req (LAR) to Revise Tech Spec (Ts) 3.6.8 Limiting Condition for Operation to Remove Refueling Water Chemical Addition Tank and Replace the Containment Sump Buffer North Anna, 1 and 2 (L-2022-LLA-0162 ML23067A2162023-03-0707 March 2023 NRR E-mail Capture - RAI for North Anna, 1 & 2, Surry 1 & 2, Millstone, 2 & 3, Request for Approval of App. F Fleet Report DOM-NAF-2-P, Qual of the Framatome ORFEO-GAIA and ORFEO-NMGRID CHF Correlations in the Dominion VIPRE-D Computer Code ML23060A0932023-03-0101 March 2023 NRR E-mail Capture - Formal Issuance of RAIs for Surry/North Anna Emergency Plans LAR ML23059A2282023-02-28028 February 2023 NRR E-mail Capture - Draft RAIs for Containment Buffer Change to Natb (L-2022-LLA-0162) ML23039A1712023-02-0808 February 2023 NRR E-mail Capture - Acceptance Review for Technical Support Center (TSC) Relocation (L-2023-LLA-0006) ML23018A0352023-01-17017 January 2023 NRR E-mail Capture - Acceptance Review for Fleet Report Re Appendix F of DOM-NAF-2-P (L-2022-LLT-0003) ML22342B1472022-12-0808 December 2022 NRR E-mail Capture - Acceptance Review for LAR Re NAPS Post LOCA Buffer Change (L-2022-LLA-0162) ML22335A4842022-12-0101 December 2022 NRR E-mail Capture - Acceptance Review for LAR North Anna Power Station - Units 1 and 2 and Surry Power Station - Units 1 and 2 Emergency Plan Staff Augmentation Times (L-2022-LLA-0166) ML22242A0452022-08-23023 August 2022 NRR E-mail Capture - Dominion GL 04-02 Response Draft RAIs (L-2017-LRC-0000) ML22174A3552022-06-23023 June 2022 NRR E-mail Capture - Acceptance Review for Dominion Fleet LAR to Implement TSTF-554 (L-2022-LLA-0078) ML22104A0252022-04-14014 April 2022 NRR E-mail Capture - Dominion Presentation Slides for April 21, 2022 Public Meeting on Emergency Preparedness Submittal for the North Anna Power Station and the Surry Power Station ML22083A2102022-03-24024 March 2022 NRR E-mail Capture - Draft RAI - Relief Request N2-14-LMT-003 Fourth Ten Year Inservice Inspection Interval ML22032A0962022-02-0101 February 2022 002 Radiation Safety Baseline Inspection Information Request ML22018A0272022-01-18018 January 2022 2022 All RFI Responses - Exercise and Program Inspections - Revl ML22007A2672022-01-0707 January 2022 NRR E-mail Capture - North Anna, Unit 2, ASME Section XI Inservice Inspection Program Relief Request N2-14-LMT-003 Fourth Interval Third Period Limited Examinations (L-2021-LLR-0088) ML21335A0812021-12-0101 December 2021 NRR E-mail Capture - Acceptance Review for OMN-28 Request Alternative to ISTC-3700, Position Verification Testing (L-2021-LLR-0086) ML21334A1922021-11-30030 November 2021 NRR E-mail Capture - Audit Plan for Reactor Core Thermal-Hydraulics Using the VIPRE-D Appendix E Review ML21327A3652021-11-23023 November 2021 NRR E-mail Capture - Draft RAI for TSTF-577 LAR ML21326A1502021-11-22022 November 2021 NRR E-mail Capture - Acceptance Review for Relocation of Unit Staff Requirements to the QAPD LAR (L-2021-LLA-0195) ML21322A0962021-11-18018 November 2021 Final Request for Additional Information Set 5 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Email ML21312A0082021-11-0404 November 2021 Enclosure 2 - NAPS Draft SER Table A.1-1 Markup ML21312A0012021-11-0404 November 2021 Comments on North Anna Draft SER ML21312A0112021-11-0404 November 2021 Enclosure 3 - NAPS Draft SER Section 3 Comments ML21306A3302021-11-0202 November 2021 NRR E-mail Capture - Acceptance Review for TSTF-569 LAR ML21286A7372021-10-13013 October 2021 Additional Element Included in the Implementation Plan for the Surry Fuel Melt Safety Limit (SL) LAR ML21274A0022021-09-30030 September 2021 NRR E-mail Capture - Acceptance Review for TSTF-577 LAR (L-2021-LLA-0158) ML21312A0072021-09-21021 September 2021 Enclosure 1 - E-mail - Enclosure B - NAPS SER App a - Dominion Comments 9-21-2021 ML21312A0032021-09-21021 September 2021 Enclosure 1 - E-mail - Enclosure a - Dominion Table A4.4-1 Clean Version ML21312A0022021-09-21021 September 2021 Enclosure 1 - E-mail - NAPS SLR SER Appendix a for Dominion Review ML21256A0672021-09-13013 September 2021 Final Request for Confirmation of Information Set 2 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Email ML21152A1722021-09-0707 September 2021 NRC to Fws, NRC Issuance of Draft Environmental Impact Statement for North Anna Subsequent License Renewal, Opportunity for Public Comment, and Endangered Species Act Determinations ML21238A0942021-08-25025 August 2021 Draft Request for Additional Information Set Z - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Email ML21225A5512021-08-13013 August 2021 Discussion Point for Public Meeting Regarding Fire Protection Piping Cyclic Loading - Transmittal E-mail ML21195A2442021-07-13013 July 2021 NRR E-mail Capture - Draft RAI Appendix E to Topical Report DOM-NAF-2 Qualification of the Framatome BWU-I CHF Correlation in the Dominion Energy VIPRE-D Computer Code ML21188A1632021-07-0707 July 2021 Final Request for Additional Information Set 4 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Email ML21154A0152021-06-0101 June 2021 NRR E-mail Capture - Acceptance Review for Primary Grade Water LAR (L-2021-LLA-0082) ML21140A3682021-05-20020 May 2021 Response to North Anna Hardship (Temporary Staff Guidance Additional Guidance for FOF Inspections During the PHE) ML21140A3712021-05-19019 May 2021 FOF Discussion 2024-04-15
[Table view] Category:Request for Additional Information (RAI)
MONTHYEARML24087A0112024-03-23023 March 2024 NRR E-mail Capture - Draft RAIs for Reactor Coolant Pump (RCP) Relief Request (L-2024-LLR-0022) ML23318A1172023-11-13013 November 2023 NRR E-mail Capture - Formal Issuance of RAIs for North Anna Technical Support Center (TSC) License Amendment Request (LAR) (L-2023-LLA-0006) ML23257A2092023-09-14014 September 2023 NRR E-mail Capture - Formal Issuance of 2nd Round RAIs for Surry Units 1&2 and North Anna Units 1&2 Emergency Plans LAR ML23243A9862023-08-31031 August 2023 NRR E-mail Capture - Draft RAIs for EP Staff Augmentation Times LAR (L-2022-LLA-0166) ML23219A1602023-08-0707 August 2023 003 Radiation Safety Baseline Inspection Information Request ML23171B0522023-06-20020 June 2023 NRR E-mail Capture - RAI for Review of Appendix F to DOM-NAF-2-P (Redacted) ML23081A5282023-04-26026 April 2023 Request for Additional Information - North Anna Subsequent License Renewal Application Environmental Review ML23075A0232023-03-15015 March 2023 NRR E-mail Capture - RAI - License Amend Req (LAR) to Revise Tech Spec (Ts) 3.6.8 Limiting Condition for Operation to Remove Refueling Water Chemical Addition Tank and Replace the Containment Sump Buffer North Anna, 1 and 2 (L-2022-LLA-0162 ML23060A0932023-03-0101 March 2023 NRR E-mail Capture - Formal Issuance of RAIs for Surry/North Anna Emergency Plans LAR ML23059A2282023-02-28028 February 2023 NRR E-mail Capture - Draft RAIs for Containment Buffer Change to Natb (L-2022-LLA-0162) ML22251A1292022-09-0909 September 2022 Request for Additional Information Related to Response to Generic Letter 2004-04 ML22242A0452022-08-23023 August 2022 NRR E-mail Capture - Dominion GL 04-02 Response Draft RAIs (L-2017-LRC-0000) ML22083A2102022-03-24024 March 2022 NRR E-mail Capture - Draft RAI - Relief Request N2-14-LMT-003 Fourth Ten Year Inservice Inspection Interval ML21327A3652021-11-23023 November 2021 NRR E-mail Capture - Draft RAI for TSTF-577 LAR ML21322A0962021-11-18018 November 2021 Final Request for Additional Information Set 5 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Email ML21322A0992021-11-18018 November 2021 Final Request for Additional Information Set 5 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Enclosure ML21256A0672021-09-13013 September 2021 Final Request for Confirmation of Information Set 2 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Email ML21256A0692021-09-13013 September 2021 Final Request for Confirmation of Information Set 2 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Request for Confirmation of Information ML21238A0942021-08-25025 August 2021 Draft Request for Additional Information Set Z - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Email ML21238A0982021-08-25025 August 2021 Draft Request for Additional Information Set Z - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Enclosure ML21225A5022021-08-13013 August 2021 Request for Additional Information for North Anna Power Station, Units 1 and 2, Surry Power Station, Units 1 and 2, and Millstone Power Station, Units 2 and 3, Appendix E of Fleet Report Com-Naf-2 (EPID:L02021-LLT-0000) Public Version ML21195A2442021-07-13013 July 2021 NRR E-mail Capture - Draft RAI Appendix E to Topical Report DOM-NAF-2 Qualification of the Framatome BWU-I CHF Correlation in the Dominion Energy VIPRE-D Computer Code ML21188A1632021-07-0707 July 2021 Final Request for Additional Information Set 4 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Email ML21188A1652021-07-0707 July 2021 Final Request for Additional Information Set 4 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Enclosure ML21174A1952021-06-23023 June 2021 Safety RAIs - Set Y - Draft - Enclosure ML21166A3512021-06-15015 June 2021 Safety RAIs - Set 4 - Draft ML21123A2972021-05-0303 May 2021 Final Request for Additional Information Set 3 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - E-mail ML21123A2982021-05-0303 May 2021 Final Request for Additional Information Set 3 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Enclosure ML21091A0032021-04-0101 April 2021 Final Request for Additional Information Set 2 - North Anna SLRA Safety Review (EPID No. L-2020-SLR-0000) - Enclosure 1 - RAIs ML21091A0042021-04-0101 April 2021 SLRA Safety Review - Withdrawn Requests for Information (EPID No. L-2020-SLR-0000) - Enclosure 2 ML21076A4622021-03-17017 March 2021 NRR E-mail Capture - Draft RAI for Versatile Internals and Component Program for Reactors Vipre Code Review (L-2021-LLT-0000) ML21075A0032021-03-12012 March 2021 Emergency Preparedness Exercise Inspection Request for Information for - Brunswick, Catawba, North Anna, Oconee, Vogtle 1 & 2 ML21063A5602021-03-0404 March 2021 Final Request for Additional Information Set 1 - North Anna SLRA Safety Review (EPID L-2020-SLR-0000) - Enclosure ML21049A0212021-02-17017 February 2021 Notification of an NRC Fire Protection Team Inspection (FPTI) (NRC Inspection Report 05000338/2021012 and 05000339/2021012) and Request for Information (RFI) ML21028A3902021-01-29029 January 2021 Request for Additional Information - North Anna Subsequent License Renewal Application Environmental Review (EPID Number: L-2020-SLE-0000) (Docket: 50-338 and 50-339) ML21028A4352021-01-28028 January 2021 Notification of Target Set Inspection and Request for Information (NRC Inspection Report No. 05000338/2021404 and 05000339/2021404) ML21012A3412021-01-22022 January 2021 Requests for Confirmation of Information for the Environmental Review of the North Anna Power Station, Units 1 and 2, Subsequent License Renewal Application (EPID Number: L-2020-SLE-0000) (Docket: 50-338 and 50-339) ML21019A4512021-01-19019 January 2021 Notification of Inspection and Request for Information ML20316A0422020-11-10010 November 2020 NRR E-mail Capture - FW: Draft RAI for North Anna Unit 2 Steam Generator Tube Inspection Report (ML19179A075) ML20223A3412020-08-10010 August 2020 003 Radiation Safety Baseline Inspection Information Request ML20218A4282020-08-0505 August 2020 Notification of Inspection and Request for Information ML20125A0762020-05-0101 May 2020 NRR E-mail Capture - Draft RAI Related to Revised Reactor Vessel Material Surveillance Capsule Withdrawal Schedule Dominion Energy Virginia North Anna Power Station Units 1 and 2 (L-2020-LLL-0038) ML20113A5792020-04-21021 April 2020 NRR E-mail Capture - Draft RAI North Anna Fifth 10-year Interval Relief Request (L-2020-LLR-0023) ML19354B6142019-12-20020 December 2019 NRR E-mail Capture - Draft RAI for North Anna Relief Request P-9 ML19317F1042019-11-0707 November 2019 NRR E-mail Capture - Draft RAIs for SB LOCA LAR (Non Prop) ML19191A2512019-07-10010 July 2019 NRR E-mail Capture - Request for Additional Information Open Phase Condition LAR ML19169A0962019-06-17017 June 2019 NRR E-mail Capture - Request for Additional Information Emergency Action Level Scheme Change for Millstone Power Station - Units 1, 2, and 3, North Anna Power Station - Units 1 and 2, and Surry Power Station - Units 1 and 2 ML19162A0052019-06-10010 June 2019 NRR E-mail Capture - Draft RAIs for Dominion EAL Scheme Change ML19108A1902019-04-18018 April 2019 Emergency Preparedness Program Inspection Request for Information ML19060A2432019-03-0101 March 2019 Related to License Amendment Request to Address Open Phase Conditions 2024-03-23
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Text
From: Ed Miller Sent: Saturday, March 23, 2024 2:51 PM To: Shayan.Sinha@dominionenergy.com
Subject:
Draft RAIs for RCP Relief Request (L-2024-LLR-0022)
Attachments: DRAI North Anna N1_I5_NDE-007.docx
Mr. Sinha, Attached is the NRC staffs draft RAI for the subject request. The questions are being transmitted to you to determine 1) If the questions clearly convey the NRC information needs, 2)
Whether the regulatory basis for the questions are clear, and 3) If the information has already been provided in existing docketed correspondence. Additionally, review of the draft question will allow you to determine what response time you can support. After youve had a chance to review, please let me know if you would like to have a clarification call or public meeting to discuss. Thank you.
Ed Miller (301) 415-2481 Hearing Identifier: NRR_DRMA Email Number: 2441
Mail Envelope Properties (SA1PR09MB748726183716D198F45E06F1E9302)
Subject:
Draft RAIs for RCP Relief Request (L-2024-LLR-0022)
Sent Date: 3/23/2024 2:50:30 PM Received Date: 3/23/2024 2:50:00 PM From: Ed Miller
Created By: Ed.Miller@nrc.gov
Recipients:
"Shayan.Sinha@dominionenergy.com" <Shayan.Sinha@dominionenergy.com>
Tracking Status: None
Post Office: SA1PR09MB7487.namprd09.prod.outlook.com
Files Size Date & Time MESSAGE 639 3/23/2024 2:50:00 PM DRAI North Anna N1_I5_NDE-007.docx 37298
Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
DRAFT REQUEST FOR ADDITIONAL INFORMATION ALTERNATIVE REQUEST N1-I5-NDE-007 ALTERNATIVE EXAMINATION OF REACTOR COOLANT PUMP VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION, UNIT 1 DOCKET NO. 50-338 L-2024-LLR-0022
1.0 INTRODUCTION
By letter dated March 22, 2024 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML24082A274), Virginia Electric and Power Company (Dominion Energy Virginia, the licensee) requested relief from the examination requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),
Section XI, Subsection IWB-2430, for North Anna Power Station Unit 1. The proposed alternative would move the inspection of a reactor coolant pump from the Spring 2024 refueling outage to the Fall 2025 refueling outage.
Pursuant to Title 10, Code of Federal Regulations, Part 50, 10 CFR 50.55a(z)(2), the licensee submitted for Nuclear Regulatory Commission (NRC) review and approval Alternative Request N1-I5-NDE-007 for North Anna, Unit 1.
The NRC staff requests the following additional information (RAI) to complete its review of the alternative request.
2.0 REGULATORY EVALUATION
The inservice inspection (ISI) of ASME Code Class 1, 2, and 3 components is to be performed in accordance with Section XI of the ASME Code and applicable editions and addenda as required by 10 CFR 50.55a(g), Preservice and inservice inspection requirements.
Pursuant to 10 CFR 50.55a(g)(4), lnservice inspection standards requirement for operating plants, ASME Code Class 1, 2, and 3 components (including supports) must meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year ISI interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(a)(1)(ii), 18 months prior to the start of the 120-month interval, subject to the conditions listed in 10 CFR 50.55a(b)(2).
Pursuant to 10 CFR 50.55a(z), Alternatives to codes and standards requirements, alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (1) the proposed alternatives would provide an acceptable level of quality and safety, or (2) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 REQUEST FOR ADDITIONAL INFORMATION
- 1. Section 5 of Attachment 1 to the March 22, 2024 submittal states that This request proposes an alternative to performing the additional examination of an RCP casing during the current outage in accordance with IWB-2430(a)(1)(a) to performing the additional examination of an RCP casing during the next refueling outage. The next scheduled pump replacement is currently planned for the next refueling outage, N1R31 (Fall 2025) :
(1) Clarify whether the additional examination will be performed on either 1-RC-P-1B RCP or 1-RC-P-1C RCP for the Fall 2025 refueling outage .
(2) Some parts of the submittal mention the pump refurbishment. Clarify whether pump replacement means the refurbishment of hydraulic parts of the RCP such as impeller, turning vane diffuser, diffuser adapter, and casing.
(3) Discuss whether pump casing will be replaced as part of periodic pump refurbishment.
- 2. Section 6 of Attachment 1 to the March 22, 2024 submittal states that The proposed alternative is requested to complete the additional examination of an RCP casing as required by IWB-2430 during the fall 2025 refueling outage, which is before the end of the current 5th ISI Interval, which ends on April 30, 2029
Clarify the exact duration of the proposed alternative, i.e., whether the proposed alternative is requested for the duration up to the fall 2025 refueling outage or up to the end of the 5th ISI interval.
- 3. By letter dated August 24, 2020 (ML20246G703), the licensee submitted the subsequent license renewal application (SLRA) for North Anna Units 1 and 2. Section 4.7.6 of the SLRA discusses time limited aging analysis of reactor coolant pump inspection respect of ASME Code Case N-481. As a result of the degradation at 1-RC-P-1A RCP:
(1) discuss how the SLRA will be supplemented to include the subject operating experience.
(2) discuss whether Section 4.7.6 in the North Anna SLRA is still valid or it needs to be revised/updated.
- 4. Page 4 of Attachment 2, Engineering Evaluation ETE-NA-2024-0033, last sentence of the first paragraph states that It should also be noted that 1-RC-P-1B and 1-RC-P-1C were removed from their casings in 1982 following the identification of the broken diffuser cap screws on 1-RC-P-1A and none of the cap screws on either pump had failed but were replaced as a precaution IAW with Westinghouse Recommendations :
(1) Discuss what year was the cap screws replaced on 1 -RC-P-1B and 1-RC-P-1C pumps (i.e., were the cap screws replaced in recent years or in 1982?).
(2) If the cap screws were replaced in 1982, discuss the likelihood of failure of the cap screws in 1-RC-P-1B or 1-RC-P-1C pumps prior to the 2025 refueling outage.
- 5. Page 5 of Attachment 2, Engineering Evaluation ETE-NA-2024-0033, states that The interior of the casing, including the areas where all of the indications were found, does not participate in a measurable way in the hydraulic performance of the pump The NRC staff understands that RCPs have vibration limits. Discuss whether excessive vibration at RCP 1-RC-P-1A were detected by the vibration sensor or abnormal occurrence as a result of loose parts during the plant operation.
- 6. Page 5 of Attachment 2, states that if all of the adapter socket head cap screws had failed, significant operation degradation of the reactor coolant pump would not have resulted A loose adapter would initially drop loop flow about 0.2% which is much less than the existing flow margin of approximately 5% above core thermal design flow. In addition, the automatic low flow reactor trip would prevent operation below core thermal design flow
The NRC staff understands that a loose adapter would reduce the reactor coolant system loop flow. If the loop flow is lower than the core thermal design flow, the reactor would trip which would cause the RCP to trip. As such, there is an automatic low flow reactor trip sensor to protect the reactor operation. Also, there is a RCP vibration limit to trip RCPs. Discuss any other defense-in-depth measures that would trip the RCPs to protect RCPs, the reactor vessel, and reactor coolant system components.
- 7. Page 8 of Attachment 2, second paragraph discusses a Leak Before Break (LBB) analysis of the pump casing in WCAP-11517. The licensee demonstrated that a postulated through-wall crack in the pump casing remains stable based on a detailed fracture mechanics evaluation and that a gross failure of the casing is not feasible.
With respect to that, discuss the following:
(1) The size of the through wall crack based on applied loading; (2) The critical crack size of the pump casing; (3) The leakage crack size if different from the through wall crack size; (4) The reactor coolant system leakage detection capabilities (e.g., what is the smallest leak rate the sensors can detect); and (5) Whether the fracture mechanics analysis has satisfied (1) the margin of 2 between the crack size and the critical crack size and (2) margin of 10 for the leakage crack size as compared to the leak rate of the leakage detection system as specified in NRCs Standard Review Plan 3.6.3.
- 8. Page 8 of Attachment 2 discusses WCAP-13045 for the pump casing analysis. The NRC staff noted that WCAP-13045 is valid only for 40-year, not 80-year of plant life. The licensee also referenced WCAP-15555 which applies to the pump casing analysis involving the initial license renewal period up to 60 years of plant life. The licensee has applied to renew its operating licensee up to 80 years for North Anna units. The NRC staff noted that it has approved generic use of topical report PWROG-17033, Revision 1, Update for Subsequent License Renewal: WCAP-13045, Compliance to ASME Code Case N-481 of the Primary Loop Pump Casings of Westinghouse Type Nuclear Steam Supply Systems, for the application of subsequent license renewal up to 80 years (ML19319A188). Based on the licensees conclusion on page 13 of Attachment 2, it appears that 1-RC-P-1A pump casing will not be replaced or repaired for the remaining life of the plant.
(1) Demonstrate by analysis and/or inspection that the degraded casing will maintain its structural integrity to the end of 80-year plant life, i.e., the degraded areas of 1-RC-P-1A pump casing will not grow to challenge the structural integrity of the pump casing.
(2) Discuss whether RCP 1-RC-P-1A is acceptable for use for the 80-year plant life per PWROG-17033, Revision 1.
- 9. Page 10 of Attachment 2 states that the limiting material fracture toughness, JIC = 750 in-lbf/in2. With respect to that:
(1) Discuss the Japplied value based on the actual crack driving force.
(2) Discuss whether the JIC = 750 in-lbf/in2 is applicable to 80 years.
- 10. Pages 11 and 12 of Attachment 2 discuss fracture mechanics analysis of the impression/dent on the pump casing wall. The NRC staff noted that the licensees analysis does not address the possibility of growth of the impression/dent. Discuss whether the impression areas would grow in depth and width to a size to challenge the structural integrity of the pump casing at the end of 80 years of operation.
- 11. Discuss Dominion Energy efforts to address the potential for common -cause failure between pumps in terms of hardware (e.g., procurement material batches, dedication, etc.) and work practices (e.g., procedures, training, common work crews, quality control, etc.). Please include whether there is any additional information or observations of RCPs 1B and 1C that can inform whether a similar condition exists in those pumps.
- 12. The NRC staff noted what appears to be a minor typographic error on the first line on Pages 2 and 3 of the Attachment 1 which states Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(ii). Please confirm whether Proposed Alternative in Accordance with 10 CFR 50.55a(z)(2) was the intended citation.