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MONTHYEARML17060A1632017-02-28028 February 2017 NRR E-mail Capture - Acceptance for Review - ISI Request N1-14-NDE-009 and N2-14-NDE-004 for North Anna Units 1 and 2 (CACs MF9298 and MF9299 - Reactor Vessel Threads in Flange) Project stage: Acceptance Review ML17137A0932017-05-17017 May 2017 Request for Additional Information, Alternative to Reactor Vessel Threads in Flange Examination Requirements Project stage: RAI ML17171A2302017-06-14014 June 2017 Response to Request for Additional Information ASME Section XI Inservice Inspection Program Request for Proposed Alternative N1-I4-009 and N2-I4-NDE-004 Project stage: Response to RAI ML17332A6632017-12-0606 December 2017 Proposed Inservice Inspection Alternatives N1-I4-NDE-009 and N2-I4-NDE-004 (CAC Nos. MF9298 and MF9299; EPID L-2016-LLR-0018) Project stage: Other 2017-02-28
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Category:Letter
MONTHYEARML24283A0392024-10-0909 October 2024 Annual Submittal of Technical Specification Bases Changes Pursuant to Technical Specification 5.5.13.D ML24281A1372024-10-0707 October 2024 ISFSI - Submittal of Cask Registration for Spent Fuel Storage 05000338/LER-2024-001-01, Automatic Reactor Trip Due to Prni High Negative Rate2024-09-24024 September 2024 Automatic Reactor Trip Due to Prni High Negative Rate IR 05000338/20244202024-09-23023 September 2024 Security Baseline Inspection Report 05000338/2024420 and 05000339/2024420, Cover Letter ML24243A0872024-09-20020 September 2024 Response to EPA Comments Regarding the Final Site Specific Supplement to the Generic Eist for License Renewal North Anna Power Station, Units 1 and 2 IR 05000338/20244022024-09-17017 September 2024 Security Baseline Inspection Report 05000338/2024402 and 05000339/2024402 ML24215A2622024-08-28028 August 2024 Transmittal Letter for Subsequent Renewed License IR 05000338/20240052024-08-27027 August 2024 Updated Inspection Plan for North Anna Power Station, Units 1 and 2 (Report 05000338/2024005 and 05000339/2024005) 05000339/LER-2024-001-01, Loss of Generator Field for 2J Eog During 2-PT-82.282024-08-20020 August 2024 Loss of Generator Field for 2J Eog During 2-PT-82.28 ML24234A0742024-08-15015 August 2024 Notification of Deviation from Pressurized Water Reactor Owners Group (PWROG) Letter OG-23-63, NEI 03-08 Needed Guidance: PWR Thermal Shield Flexure Inspection Requirements ML24221A1882024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Monacan Indian Nation ML24221A1932024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Upper Mattaponi Tribe ML24206A0052024-08-0808 August 2024 SLR Final EIS Letter to Achp ML24221A1912024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Rappahannock Tribe, Inc ML24221A1942024-08-0808 August 2024 Tribal Section 106 Letters-North Anna-United Keetoowah Band of Cherokee Indians in Oklahoma ML24221A1842024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Delaware Nation, Oklahoma ML24221A1852024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Delaware Tribe of Indians ML24221A1832024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Chickahominy Indian Tribe-Eastern Division ML24221A1922024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Tuscarora Nation of New York ML24206A0062024-08-0808 August 2024 Notice of Availability of the Final Environmental Impact Statement for the North Anna Nuclear Power Station Unit Numbers 1 and 2 Subsequent License Renewal (Docket Numbers: 50-338 and 50-339) ML24163A3002024-08-0808 August 2024 Request for Relief Request N1-I5-NDE-007 Inservice Inspection Alternative ML24221A1872024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Eastern Shawnee Tribe of Oklahoma ML24221A1862024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Eastern Band of Cherokee Indians ML24221A1812024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Catawba Indian Nation ML24208A0142024-08-0808 August 2024 Tribal Section 106 Letters-North Anna-Absentee-Shawnee Tribe of Indians of Oklahoma ML24221A1822024-08-0808 August 2024 Tribal Section 106 Letters - North Anna - Chickahominy Indian Tribe ML24221A1902024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Pamunkey Indian Tribe ML24221A1892024-08-0808 August 2024 Tribal Section 106 Letters-North Anna - Nansemond Indian Nation ML24241A0692024-08-0606 August 2024 ISFSI, Submittal of Cask Registration for Spent Fuel Storage IR 05000338/20240022024-08-0202 August 2024 Integrated Inspection Report 05000338/2024002 and 05000339/2024002 ML24206A0432024-07-26026 July 2024 Feis - Letter to the Applicant ML24206A0902024-07-24024 July 2024 Owners Activity Report ML24178A2422024-06-25025 June 2024 2023 Annual Report of Emergency Core Cooling System (ECCS) Model, Changes Pursuant to the Requirements of 10 CFR 50.46 ML24177A2792024-06-20020 June 2024 Preparation and Scheduling of Operator Licensing Examinations ML24143A1622024-06-12012 June 2024 – Correction to Issuance of Amendment Nos. 297 and 280 and Surry Units 1 and 2, Correction to Issuance of Amendment Nos. 317 and 317, to Change Emergency Plan Staff Augmentation Times ML24170B0532024-06-10010 June 2024 DOM-NAF-2-P/NP-A, Revision 0.5, Reactor Core Thermal-Hydraulics Using the VIPRE-D Computer Code ML24165A1462024-06-0505 June 2024 Loss of Generator Field for 2J EDG During 2-PT-82.28 IR 05000338/20240102024-05-24024 May 2024 NRC Fire Protection Team Inspection (FPTI) Report 05000338/2024010 and 05000339/2024010 IR 05000338/20240012024-05-10010 May 2024 Integrated Inspection Report 05000338/2024001 and 05000339/2024001 IR 05000338/20244032024-04-30030 April 2024 – Security Baseline Inspection Report 05000338-2024403 and 05000339-2024403 ML24054A0142024-04-22022 April 2024 Issuance of Amendment Nos. 297 and 280, and Surry Power Station Unit Nos. 1 and 2, Issuance of Amendment Nos. 317 and 317, to Change Emergency Plan Staff Augmentation Times ML24110A1502024-04-18018 April 2024 Independent Spent Fuel Storage Installation (ISFSI) - Annual Radioactive Effluent Release Report ML24110A1462024-04-18018 April 2024 Independent Spent Fuel Storage Installation (Sfsi) - Annual Radiological Environmental Operating Report ML24110A1392024-04-18018 April 2024 Annual Environmental Operating Report ML24087A0572024-04-16016 April 2024 Correction to Issuance of Amendment Nos. 296 and 279 ML24088A2692024-03-27027 March 2024 Core Operating Limits Report Cycle 31 Pattern Sos Revision 0 ML24086A4292024-03-25025 March 2024 Response to Request for Additional Information Associated with Alternative Request N1-I5-NDE-007 Request to Deter Additional Required Reactor Coolant Pump Casing Inspection ML24082A2742024-03-22022 March 2024 Request for Approval of Alternative Request N1-I5-NDE-007 to Deter Additional Required Reactor Coolant Pump Casing Inspection ML24086A4682024-03-21021 March 2024 Summary of Facility Changes, Tests and Experiments ML24005A0042024-03-18018 March 2024 Issuance of Amendment Nos. 296 and 279, Regarding Revised Emergency Plan for Relocation of the Technical Support Center 2024-09-24
[Table view] Category:Response to Request for Additional Information (RAI)
MONTHYEARML24086A4292024-03-25025 March 2024 Response to Request for Additional Information Associated with Alternative Request N1-I5-NDE-007 Request to Deter Additional Required Reactor Coolant Pump Casing Inspection ML23346A0972023-12-11011 December 2023 License Amendment Request to Revise the Emergency Plan Relocation of the Technical Support Center - Response to NRC Request for Additional Information ML23208A0922023-07-26026 July 2023 Request for Approval of Appendix F of Fleet Report DOM-NAF-2-P Qualification of Framatome ORFEO-GAIA and OORFE-NMGRID CHF Correlations in the Dominion Energy Vipre-D Computer Code Response ML23136A8832023-05-16016 May 2023 Responses to Request for Additional Information and Request for Confirmation of Information Regarding Environmental Review of Subsequent License Renewal Application L-04-002, Stations - NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors Fleet Response to Request for Additional Information2023-05-0808 May 2023 Stations - NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors Fleet Response to Request for Additional Information ML23103A2752023-04-13013 April 2023 Response to Request for Additional Information Regarding Proposed License Amendment Request for Removal of Refueling Water Chemical Addition Tank and Replacement of Containment Sump Buffer ML23096A2982023-04-0606 April 2023 Units 1 and 2 and Millstone Power Station, Units 2 and 3 - Request for Approval of Appendix F of Fleet Report DOM-NAF-2-P Qualification of the Framatome ORFEO-GAIA and ORFEO-NMGRID CHF Correlations in the Dominion ML23089A3542023-03-30030 March 2023 Response to Request for Additional Information Regarding Proposed License Amendment Request to Revise Emergency Plan Staff Augmentation Times ML22312A4432022-11-0707 November 2022 NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors Fleet Response to RAI ML22115A1752022-04-25025 April 2022 ASME Section XI Inservice Inspection Program - Relief Request N2-14-LMT-004 - Fourth Interval Third Period Limited Examinations - Response to Request for Additional Information ML21350A4082021-12-16016 December 2021 Application to Revise Technical Specifications to Adopt TSTF-577, Revised Frequencies for Steam Genera Tor Tube Inspections, Rev 1, Using the Consolidated Line-Item Improvement Process Response to RAI ML21341B4372021-12-0606 December 2021 (Naps), Units 1 and 2 - Subsequent License Renewal Application Responses to NRC Request for Additional Information Safety Review - Set 5 ML21258A3542021-09-15015 September 2021 (Naps), Units 1 and 2 - Subsequent License Renewal Application (SLRA) Response to NRC Request for Confirmation of Information Set 2 Safety Review ML21259A0852021-09-15015 September 2021 North Ann, and Surry, Units 1 and 2, Millstone, Units 2 and 3, Request for Approval of Appendix E of Fleet Report DOM-NAF-2-A Qualification of the Framatome BWU-I CHF Correlation in the Vipre-D Computer Code Response to Request for Addition ML21210A3962021-07-29029 July 2021 (Naps), Units 1 and 2 - Subsequent License Renewal Application (SLRA) Response to NRC Request for Additional Information Safety Review - Set 4 and Supplement 3 ML21147A2932021-05-27027 May 2021 (Naps), Units 1 and 2 Subsequent License Renewal Application (SLRA) Response to NRC Request for Additional Information Safety Review - Set 3 and Administrative Change to SLRA Table A4.0-1, Item 25 ML21133A2852021-05-13013 May 2021 Stations, Units 1 & 2 and Millstone Power Station, Units 2 and 3 - Request for Approval of Appendix E Fleet Report DOM-NAF-2-A Qualification of the Framatome Bwui CHF Correlation in the Dominion Energy VIPRE-D Computer Code ML21126A3152021-05-0606 May 2021 Proposed License Amendment Request to Battery Surveillance Requirements - Response to Request for Additional Information ML21119A2872021-04-29029 April 2021 (Naps), Unit 1 and 2 - Subsequent License Renewal Application (SLRA) Response to NRC Request for Additional Information Safety Review - Set 2 and Flow Accelerated Corrosion Program Enhancement Completion ML21091A1872021-04-0101 April 2021 Response to NRC Request for Additional Information Regarding Safety Review - Set 1 & Clarification to Aging Management of Fire Protection System Lined Ductile Iron Valves ML21084A1822021-03-24024 March 2021 Subsequent License Renewal Application Response to NRC Requests for Confirmation of Information for the Safety Review - Set 1 ML21056A5572021-02-25025 February 2021 NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors Final Supplemental Response ML21053A4332021-02-22022 February 2021 (Naps), Units 1 and 2 - Subssequent License Renewal Application (SLRA) Environmental Review - Response to NRC Request for Additional Information ML21042B9042021-02-11011 February 2021 Subsequent License Renewal Application, Response to NRC Requests for Confirmation of Information for the Environmental Review ML21033A3022021-01-25025 January 2021 (NAPS) Units 1 and 2 - Subsequent License Renewal Application (SLRA) - Provides Requested Documents in Response to Environmental Audit. Part 1 of 2 ML21022A1752020-12-16016 December 2020 Steam Generator Tube Inspection Report RAI Response ML20296A6672020-10-22022 October 2020 ASME Section XI Inservice Inspection Program Proposed Inservice Inspection Relief Request N1-I4-LMT-003 Response to Request for Additional Information ML20296A7272020-10-22022 October 2020 Stations Units 1 & 2 - Proposed License Amendment Requests Addition of Analytical Methodology to the Core Operating Limits Report for a Small Break LOCA Supplement to the Response to Request for Additional Information ML20268B1872020-09-24024 September 2020 ASME Section XI Inservice Inspection Program, Proposed Inservice Inspection Alternative N1-I5-NDE-002, Response to Request for Additional Information ML20156A2872020-06-0404 June 2020 Inservice Testing Program Plan for Pumps, Valves, and Snubbers Fifth 10-Year Interval Update for Units 1 & 2 Request for Alternatives to Requirements of ASME OM Code - Response to RAI ML20149K6942020-05-28028 May 2020 Response to Request for Additional Information, to Proposed License Amendment Requests Addition of Analytical Methodology to the Core Operating Limits Report for a Small Break Loss of Coolant Accident ML20140A3362020-05-18018 May 2020 Revised Reactor Vessel Materials Surveillance Capsule Withdrawal Schedules - Response to Request for Additional Information ML20021A0052020-01-17017 January 2020 Inservice Testing Program Request for Alternative to Requirements of ASME OM Code Relief Request P-9, Response to Request for Additional Information ML19249B7672019-08-29029 August 2019 Enclosure 1 - Millstone, Units 2 and 3 and ISFSI; North Anna, Units 1 and 2 and ISFSI; and Surry, Units 1 and 2 and ISFSI - Response to EAL Scheme Change RAIs ML19248B7622019-08-22022 August 2019 Supplement to Proposed License Amendment Request - Flood Protection Dike Modification - Response to Onsite Audit Questions ML19225D1302019-08-0808 August 2019 Response to Request for Additional Information (Follow-Up) Regarding Open Phase Protection Per NRC Bulletin 2012-01 - Proposed License Amendment Request ML19196A1102019-07-0909 July 2019 Attachments 2, 3 & 4 - Response to NRC Request for Additional Information and Correction of SBLOCA Analysis Error and Revised Marked-Up/Typed NAPS and SPS Technical Specifications Pages ML19156A2072019-05-24024 May 2019 Response to Request for Additional Information on Proposed License Amendment Request Open Phase Protection Per NRC Bulletin 2012-01 ML19071A1142019-03-0707 March 2019 Response to 03/12/2012 Information Request, Seismic Probabilistic Risk Assessment Supplement for Recommendation 2.1 ML18267A0682018-09-18018 September 2018 Attachment - Response to Request for Clarification on Proposed Consolidated Emergency Operations Facility License Amendment Requests ML18257A2272018-09-14014 September 2018 SPRA (Fukushima 50.54f) Audit (Clarification) Questions - Plant Response ML18169A2262018-06-13013 June 2018 Attachment 1 - Response to Request for Additional Information ML18169A2272018-06-13013 June 2018 Attachment 3 - Proposed NAPS Emergency Plan Changes ML18093A4452018-03-28028 March 2018 Ad 2, Response to 03/12/2012 Information Request Seismic Probabilistic Risk Assessment for Recommendation 2.1 ML18092A0812018-03-26026 March 2018 Supplement to Proposed License Amendment Request to Revise Technical Specifications to Adopt TSTF-522, Revise Ventilation System Surveillance Requirements to Operate for 10 Hours Per Month ML18037A7042018-01-31031 January 2018 Response to Request for Additional Information Regarding Proposed License Amendment Request for Spent Fuel Storage and New Fuel Storage ML17354A1602017-12-14014 December 2017 Response to March 12, 2012 Information Request Spent Fuel Pool Seismic Evaluation for Recommendation 2.1 ML17241A0452017-08-24024 August 2017 Proposed ISI Alternatives NI-14-NDE-010 and N2-14-NDE-005 Reactor Pressure Vessel Nozzle Weld Inspections Response to Request for Additional Information ML17171A2302017-06-14014 June 2017 Response to Request for Additional Information ASME Section XI Inservice Inspection Program Request for Proposed Alternative N1-I4-009 and N2-I4-NDE-004 ML17065A2502017-02-28028 February 2017 & Independent Spent Fuel Storage Installation (ISFSI) - Submittal of Response to Request for Referenced Information Related to RAIs 2-2, 3-5, and 3-8 2024-03-25
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VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 June 14, 2017 U. S. Nuclear Regulatory Commission Serial No.17-211 Attention: Document Control Desk NRA/DEA RO Washington, DC 20555-0001 Docket Nos.: 50-338 50-339 License Nos.: NPF-4 NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ASME SECTION XI INSERVICE INSPECTION PROGRAM REQUEST FOR PROPOSED ALTERNATIVE N1-14-NDE-009 AND N2-14-NDE-004 In a November 30, 2016 letter (Serial No.16-280), Virginia Electric and Power Company submitted a request for Nuclear Regulatory Commission (NRC) approval of inservice inspection (ISi) alternative N1-14-NDE-009 and N2-14-NDE-004. Specifically, Virginia Electric and Power Company requested to eliminate the ASME Category B-G-1, Item 86.40, Pressure retaining bolting greater than 2-inches, Reactor Vessel - Threads in Flange volumetric examination, in accordance with an industry initiative analyzed in Electric Power Research Institute (EPRI) Report #3002007626, "Nondestructive Evaluation: Reactor Pressure Vessel Threads in Flange Examination Requirements,"
March 2016.
In an email dated May 10, 2017, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) related to inservice inspection (ISi) alternative N1-14-NDE-009 and N2-14-NDE-004. The response to the RAI is provided in .
Should you have any questions in regard to this submittal, please contact Ms. Diane E.
Aitken at (804) 273-2694.
Sincerely, i
Mark D. Sartain Vice President - Nuclear Engineering and Fleet Support Commitments made in this letter: None
Serial No.17-211 Docket Nos.: 50-338/339 Response to RAI - Proposed ISi Alternative N1-14-NDE-009 & N2-14-NDE-004 Page 2of2
Attachment:
- 1. Response to Request for Additional Information for Proposed lnservice Alternative N1-14-NDE-009 and Proposed lnservice Alternative N2-14-NDE-004 Commitments made in this letter: None.
cc: U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 Ms. K. R. Cotton-Gross NRC Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 G-9A Rockville, MD 20852-2738 Mr. James R. Hall NRC Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 G-9A Rockville, MD 20852-2738 Mr. J. E. Reasor, Jr.
Old Dominion Electric Cooperative Innsbrook Corporate Center 4201 Dominion Blvd.
Suite 300 Glen Allen, VA 23060 NRC Senior Resident Inspector North Anna Power Station
Serial No.17-211 Docket Nos.: 50-338/339 Page 1 of 4 ATTACHMENT 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION PROPOSED INSERVICE INSPECTION ALTERNATIVE N1-14-NDE-009 PROPOSED INSERVICE INSPECTION ALTERNATIVE N2-14-NDE-004 Virginia Electric and Power Company North Anna Power Station Units 1 and 2
Serial No.17-211 Attachment 1 Response to RAI - Proposed ISi Alternative N1-14-NDE-009 & N2-14-NDE-004 Page 2 of 4 Response to Request for Additional Information (RAil Proposed lnservice Alternative N1-14-NDE-009 Proposed lnservice Alternative N2-14-NDE-004
RAI 1
Section 6 of Attachment 1 to the November 16, 2016, submittal states that the proposed alternative is applicable to the fourth ten-year /SI intervals for NAPS 1 and NAPS 2.
However, the second sentence of the submittal Jetter states: "The request is to eliminate the ASME Category B-G-1 , Item 86.40, Pressure retaining bolting greater than 2-inches, Reactor Vessel - Threads in Flange volumetric examination ... " The NRG staff requests the licensee to confirm that the request is to eliminate the volumetric examination onlv for the fourth ten-vear /SI intervals of NAPS 1 and NAPS 2, as stated in Section 6 of Attachment 1 to the submittal.
RAI RESPONSE:
Proposed inservice inspection (ISi) alternative N1-14-NDE-009 and N2-14-NDE-004 to eliminate the volumetric examination is only for the fourth ten-year ISi intervals of North Anna Power Station (NAPS) Unit 1 and NAPS Unit 2, as stated in Section 6 of to letter dated November 30, 2016 submittal that requested approval of the proposed ISi alternative.
RAl2:
The licensee stated on page 3 of Attachment 1 to the submittal that the bolt/stud preload stress was calculated as detailed in the NAPS 1 and NAPS 2 RPV manual.
The licensee showed on the same page the preload equation and the resulting bolt/stud preload stress of 42,338 pounds per square inch (psi). This preload stress value is based on the bounding values shown in Table 1 of Attachment 1 to the submittal. The NRG staff requests the licensee to confirm that the actual bolt/stud preload stress applied to the NAPS 1 and NAPS 2 RPV bolt/studs is less than or equal to 42,338 psi.
Serial No.17-211 Attachment 1 Response to RAI - Proposed ISi Alternative N1-14-NDE-009 & N2-14-NDE-004 Page 3of4 RAI RESPONSE:
Based on the North Anna Unit 1 and Unit 2 Replacement Reactor Vessel Closure Head Stress and Fatigue Analysis Reports, the preload stress in the Reactor Pressure Vessel (RPV) Head closure studs is calculated to be 37.2 ksi. This preload stress value represents the average tensile stress based on -uniformly tensioned studs and is less than the bounding bolt/stud preload stress of 42.3 ksi, calculated in the EPRI Report used as the basis for the original proposed ISi alternative request.
It is noted that stud elongation tolerances are not specifically addressed in the applicable North Anna stress reports, and that a 10% bolt-up contingency factor is used to calculate the bounding bolt/stud preload stress in the EPRI Report. However, adequate margin for elongation tolerances exist such that if this contingency factor were applied, a stud preload stress of (1.1 )x(37.2 ksi) = 40.9 ksi would result, which is less than the bounding bolt/stud preload stress of 42.3 ksi calculated in the EPRI Report.
RAl3:
Table 2 of Attachment 1 to the submittal shows values of applied stress intensity factor (K1) for two load cases, "Preload" (occurs at the temperature the bolt preload is applied) and "Preload + Heatup +Pressure" (occurs at high or operating temperature). However, the licensee provided a comparison of K1with the allowable value (K1d.Y10) only for the "Preload + Heatup + Pressure" case. K1e is defined to be the material fracture toughness of the RPV flange that contains the bolt hole threads. The NRG staff observes that the "Preload" case could be more limiting than the "Preload + Heatup +
Pressure" case because: (1) it expects the value of K1e to be lower at the temperature the bolt preload is applied, and (2) most of the applied K1 comes from the "Preload" case. Therefore, the NRG staff requests the licensee to provide a comparison of applied K1 with K1d.Y10 for the "Preload" case for the NAPS 1 and NAPS 2 threads in RPVflange.
RAI RESPONSE:
A review of material data for Reactor Vessels at North Anna Units 1 & 2 concluded that the applicable RT NDT for areas of the reactor vessel flange is -22°F. Based on the American Society of Mechanical Engineers (ASME)Section XI 2004 Ed. fracture toughness curves and the station procedural limitations on stud tensioning being performed at a minimum of 60°F, the Plane Strain Fracture Toughness, K1c , for the "Preload" case is given as:
Kie= 33.2+(20.734)e<0*02xcso-<-22>>> = 140.087, ksiv'in
Serial No.17-211 Attachment 1 Response to RAI - Proposed ISi Alternative N1-14-NDE-009 & N2-14-NDE-004 Page 4of4
~ f Per ASME Section IWB-3612, the maximum allowable stress intensity is 44.27 ksi~in (K1 < Kic/~10 = 140/~10). This provides adequate margin to the maximum preload stress intensity factor of 17.4 ksi~in, calculated in EPRI Report 3002007626, "Nondestructive Evaluation: Reactor Pressure* Vessel Threads in Flange Examination Requirements," which was used as the basis for the original alternative request.
\