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Initiation
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MONTHYEARML12285A2652012-10-0101 October 2012 Attachment 4 - MHI Document L5-04GA564 - Tube Wear of Unit-3 RSG, Technical Evaluation Report Project stage: Request ML12285A2672012-10-0101 October 2012 Attachment 4: SG Tube Wear Analysis for Unit-2/3 Project stage: Request ML12285A2662012-10-0101 October 2012 Attachment 4: Appendix-2 Attachment-1, Tube-to-TSP Wear Depth Diagram for Unit-2/3 Project stage: Request ML12285A2642012-10-0101 October 2012 Attachment 3 - Areva Document 51-9180143-001 - SONGS Unit 3 February 2012 Leaker Outage Steam Generator Condition Monitoring Report Project stage: Request ML12285A2682012-10-0202 October 2012 Attachment 6 - Appendix B: SONGS U2C17 - Steam Generator Operational Assessment for Tube-to-Tube Wear Project stage: Request ML12285A2692012-10-0202 October 2012 Attachment 6: Appendix a: Estimates of FEI-Induced Ttw Rates Project stage: Request ML12285A2632012-10-0303 October 2012 Confirmatory Action Letter - Actions to Address Steam Generator Tube Degradation Project stage: Request ML12338A1102012-11-30030 November 2012 Email, Request for Additional Information Southern California Edison'S Response to Nrc'S Confirmatory Action Letter (CAL) 4-12-001 Dated March 27, 2012 Project stage: RAI ML12341A1122012-12-0707 December 2012 Notice of Meeting with Southern California Edison to Discuss Its Response to Nrc'S Confirmatory Action Letter and Return to Service Report for San Onofre Nuclear Generating Station, Unit 2 Project stage: Meeting ML12347A0662012-12-0707 December 2012 Revised Notice of 12/18/12 Meeting with Southern California Edison to Discuss Its Response to Nrc'S Confirmatory Action Letter and Return to Service Report for San Onofre Nuclear Generating Station, Unit 2 Project stage: Meeting ML12345A4272012-12-10010 December 2012 Revised Email, Request for Additional Information Review of Southern California Edison'S Response to Nrc'S 3/27/2012 Confirmatory Action Letter (CAL) 4-12-001 and Return to Service Report Project stage: RAI ML12353A0972012-12-13013 December 2012 LTR-12-0795 - E-mail Don Leichtling Concerns Media Alert - Nuclear News - NRR Forthcoming Meeting with Southern California Edison Company Project stage: Meeting ML12352A3852012-12-18018 December 2012 Licensee Slides for 12/18/12 Public Meeting Project stage: Meeting ML12352A4112012-12-18018 December 2012 NRC Slides for 12/18/12 Meeting with Southern California Edison Project stage: Meeting ML12356A1982012-12-20020 December 2012 Email, Request for Additional Information, Round 3, Review of Southern California Edison'S Response to Nrc'S 3/27/2012 Confirmatory Action Letter (CAL) 4-12-001 and Return to Service Report Project stage: RAI ML13009A3492013-01-0808 January 2013 Response to Request for Additional Information Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13014A2512013-01-0909 January 2013 Response to Request for Additional Information (RAI 30) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13014A2492013-01-0909 January 2013 Response to Request for Additional Information (RAI 15) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13015A0042013-01-10010 January 2013 Response to Request for Additional Information (RAI 16), Regarding Confirmatory Action Letter Response (TAC No. Me 9727) Project stage: Response to RAI ML13022A0882013-01-16016 January 2013 Response to Request for Additional Information (RAI 19) Regarding Confirmatory Action Letter Response (TAC No. Me 9727) Project stage: Response to RAI ML13022A4132013-01-17017 January 2013 Response to Request for Additional Information (RAIs 10 and 17) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13022A4812013-01-18018 January 2013 Response to Request for Additional Information (RAI 13), Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13022A4082013-01-18018 January 2013 Response to Request for Additional Information (RAI 12), Regarding Confirmatory Action Letter Response (TAC No. Me 9727) Project stage: Response to RAI ML13022A4112013-01-21021 January 2013 Response to Request for Additional Information (RAI 11) Regarding Confirmatory Action Letter Response (TAC Me 9727) Project stage: Response to RAI ML13022A4052013-01-21021 January 2013 Response to Request for Additional Information (RAI 28), Regarding Confirmatory Action Letter Response (TAC No. Me 9727) Project stage: Response to RAI ML13028A0982013-01-24024 January 2013 Response to Request for Additional Information (RAI 18) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13028A4752013-01-25025 January 2013 Response to Request for Additional Information (RAI 27) Regarding Confirmatory Action Letter Project stage: Response to RAI ML13028A4742013-01-25025 January 2013 Response to Request for Additional Information (RAIs 5, 7, and 9) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13032A0092013-01-29029 January 2013 Response to Request for Additional Information (RAI 14) Regarding Confirmatory Action Letter Response (TAC No. Me 9727) Project stage: Response to RAI ML13037A1122013-01-31031 January 2013 Response to Request for Additional Information (RAI 29) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13053A3672013-02-0101 February 2013 E-mail, Draft Request for Additional Information Southern California Edison'S Response to Nrc'S Confirmatory Action Letter Project stage: Draft RAI ML13038A0102013-02-0404 February 2013 Response to Request for Additional Information (RAI 8) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13038A0092013-02-0404 February 2013 Response to Request for Additional Information (RAI 6) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13039A2782013-02-0606 February 2013 Response to Request for Additional Information (RAIs 20, 21, 22, 23, 24, 26 & 31), Confirmatory Action Letter Project stage: Response to RAI ML13039A3172013-02-0707 February 2013 Response to Request for Additional Information (RAI 25) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13050A1892013-02-14014 February 2013 Supplemental Document Submittal Regarding Confirmatory Action Letter Response, Concerning Steam Generator Tubes Project stage: Supplement ML13051A1972013-02-15015 February 2013 Enclosure 6, LTR-SGDA-12-36, Rev. 3, Flow-Induced Vibration and Tube Wear Analysis of the San Onofre Nuclear Generating Station Unit 2 Replacement Steam Generators Supporting Restart. Cover Through Page 227 of 415 Project stage: Other ML13051A1992013-02-15015 February 2013 Enclosure 6, LTR-SGDA-12-36, Rev. 3, Flow-Induced Vibration and Tube Wear Analysis of the San Onofre Nuclear Generating Station Unit 2 Replacement Steam Generators Supporting Restart. Page 228 of 415 Through End Project stage: Other ML13046A1232013-02-15015 February 2013 2/27/2013 Notice of Forthcoming Meeting with Southern California Edison Company to Discuss Confirmation Action Letter Project stage: Meeting ML13051A1932013-02-18018 February 2013 Enclosure 5, L5-04GA585, Rev. 2, Analytical Evaluations for Operational Assessment Project stage: Other ML13051A1922013-02-18018 February 2013 Enclosure 4, L5-04GA567, Rev. 6, Evaluation of Stability Ratio for Return to Service Project stage: Other ML13051A1902013-02-18018 February 2013 Supplemental Document Submittal Regarding Confirmatory Action Letter Response to Address Steam Generator Tube Degradation Project stage: Supplement ML13056A0922013-02-20020 February 2013 Email, Draft Request for Additional Information Nos. 38-52, Southern California Edison'S Response to Nrc'S Confirmatory Action Letter Project stage: Draft RAI ML13053A1732013-02-21021 February 2013 Email, Draft Request for Additional Information, Nos. 53-67, Southern California Edison'S Response to Nrc'S Confirmatory Action Letter Project stage: Draft RAI ML13053A1842013-02-21021 February 2013 Draft Request for Additional Information, Nos. 53-67, Southern California Edison'S Response to Nrc'S Confirmatory Action Letter Project stage: Draft RAI ML13058A0262013-02-25025 February 2013 Response to Request for Additional Information (Rals 2, 3, and 4) Regarding Confirmatory Action Letter Response (TAC No. Me 9727) Project stage: Response to RAI ML13056A6012013-02-25025 February 2013 Response to Request for Additional Information (RAI 32) Regarding Confirmatory Action Letter Response Project stage: Response to RAI ML13059A1572013-02-27027 February 2013 Licensee Slides from 2/27/13 Meeting Regarding a Request for Additional Information Project stage: Meeting ML13059A1522013-02-27027 February 2013 NRC Meeting Slides from 2/27/13 Public RAI Meeting Project stage: RAI ML13074A7932013-03-14014 March 2013 Operational Assessment for 100% Power Case Regarding Confirmatory Action Letter Response Project stage: Other 2013-01-25
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MONTHYEARML24240A1692024-09-18018 September 2024 Cy 2023 Summary of Decommissioning Trust Fund Status IR 07200041/20244012024-08-16016 August 2024 San Onofe Nuclear Generating Station, Security Baseline Inspection Report 07200041/2024401 IR 05000361/20240042024-08-0909 August 2024 NRC Inspection Report 05000361/2024004 and 05000362/2024004 ML24191A2472024-07-0202 July 2024 (Songs), Units 1, 2, and 3, and the Independent Spent Fuel Storage Installation - Revision to the ISFSI-Only Emergency Plan and Associated Changes to Emergency Plan Implementing Procedures ML24151A6482024-06-0303 June 2024 Changes in Reactor Decommissioning Branch Project Management Assignments for Some Decommissioning Facilities ML24141A0802024-05-15015 May 2024 (Songs), Units 1, 2 and 3 and Independent Spent Fuel Storage Installation - 2023 Annual Radiological Environmental Operating Report IR 05000361/20240022024-04-0101 April 2024 – NRC Inspection Report 050-00361/2024-002 and 050-00362/2024-002 ML24094A0642024-03-27027 March 2024 Independent Spent Fuel Storage Installation, Decommissioning Funding Status Report 2023 ML24065A0152024-02-28028 February 2024 Generation Station Units 1, 2 and 3, Annual Radioactive Effluent Release Report for Independent Spent Fuel Storage Installation 2023 ML24044A0812024-02-14014 February 2024 LTR-24-0008: NRC Response to Paul Blanch Email Safety of Spent Nuclear Fuel at SONGS ISFSI IR 05000361/20240012024-02-13013 February 2024 NRC Inspection Report 050-00361/2024-001 and 050-00362/2024-001 (1) ML24037A0542024-01-30030 January 2024 (Songs), Units 2 and 3, Submittal of Annual Corporate Financial Reports ML24022A1492024-01-17017 January 2024 Independent Spent Fuel Storage Installation, Revision 4 to the Physical Security Plan ML24017A2432024-01-15015 January 2024 LTR-24-0008 Paul Blanch, E-mails Request for Formal Response to Requests for Meeting to Discuss Safety Issues with NRC Staff IR 05000361/20230062023-11-29029 November 2023 NRC Inspection Report 05000361/2023-006 and 05000362/2023-006 ML23333A0682023-11-22022 November 2023 (SONGS) Units 1, 2, 3 and Independent Spent Fuel Storage Installation - Notification of Change in Nuclear Officer IR 05000361/20230052023-10-11011 October 2023 NRC Inspection Report 05000361/2023005 and 05000362/2023005 ML23276A5942023-09-28028 September 2023 and Independent Spent Fuel Storage Installation - Supplement to Decommissioning Funding Status Reports ML23268A0922023-09-20020 September 2023 Generation Station, Units 1, 2 and 3, and the Independent Spent Fuel Storage Facility (ISFSI) - Re-Registration of Dry Fuel Storage Casks for Amended Certificate of Compliance No. 1040 IR 05000361/20230012023-09-13013 September 2023 NRC Inspection Report 05000361 2023-001 and 05000362 2023-004 ML23240A5372023-08-18018 August 2023 Confirmatory Survey Activities Summary and Results for the Unit 2 and 3 Intake Structures at the San Onofre Nuclear Generating Station San Clemente CA ML23129A1802023-06-14014 June 2023 Cover Letter to State of CA on Draft EA Regarding San Onofre ISFSI Updated DFPs IR 05000361/20230032023-05-31031 May 2023 NRC Inspection Report 05000361/2023003 and 05000362/2023003 IR 05000361/20230022023-05-23023 May 2023 NRC Inspection Report 05000361/2023-002 and 05000362/2023-002 ML23137A1032023-05-11011 May 2023 (Songs), Units 1, 2 and 3, and Independent Spent Fuel Storage Installation - 2022 Annual Radiological Environmental Operating Report ML23123A0932023-04-28028 April 2023 (Songs), Units 1, 2 and 3, Submittal of Annual Radioactive Effluent Release Report - 2022 ML23230A0882023-04-10010 April 2023 Independent Spent Fuel Storage Installation - Decommissioning Quality Assurance Plan ML23094A1272023-03-29029 March 2023 Independent Spent Fuel Storage Installation - 10 CFR 50.82(a)(8)(v and VII) and 10 CFR 72.30(c) Decommissioning Funding Status Report 2021 ML23094A1332023-03-29029 March 2023 Nuclear Property Insurance ML23062A1172023-02-28028 February 2023 Generation Station Units 1, 2 and 3, Annual Radioactive Effluent Release Report for Independent Spent Fuel Storage Installation - 2022 ML22361A1022023-02-24024 February 2023 Reactor Decommissioning Branch Project Management Changes for Some Decommissioning Facilities and Establishment of Backup Project Manager for All Decommissioning Facilities ML23059A2812023-02-22022 February 2023 (Songs), Units 1, 2 and 3, 2022 Annual Turtle Incidental Take Report ML23046A3792023-02-22022 February 2023 NRC Inspection Report 050-00361/2023-001 and 050-00362/2023-001 ML23045A2022023-02-0909 February 2023 Submittal of Annual Corporate Financial Reports for San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 for Fy Ending June 30, 2022 ML22287A1352023-01-0505 January 2023 Issuance of Exemption from Title 10 of the Code of Federal Regulations Part 72.106(B), Independent Spent Fuel Storage Installation Controlled Area Boundary (L-2021-LLE-0056) ML22348A0622023-01-0404 January 2023 NRC to SCE, Transmittal of the National Marine Fisheries Service'S December 12, 2022, Letter of Concurrence for Decommissioning of San Onofre Nuclear Generating Statiion, Units 2 and 3 IR 05000206/20220062022-12-15015 December 2022 NRC Inspection Report 05000206/2022006, 05000361/2022-006, and 05000362/2022-006 ML22347A2122022-12-12012 December 2022 NMFS to NRC, Endangered Species Act Section 7(a)(2) Concurrence Letter for Decommissioning of the San Onofre Nuclear Generating Station ML22340A6652022-12-0505 December 2022 Letter from John Fassell, Chief; Re., State of California Department of Public Health Review and Comments on SONGS Draft Environmental Assessment ML22333A8192022-11-21021 November 2022 Submittal of San Onofre Nuclear Generating Station, Units 2 and 3, Defueled Safety Analysis Report, Revised November 2022 IR 05000361/20220052022-11-17017 November 2022 NRC Inspection Report 05000361/2022-005 and 05000362/2022-005 ML22301A1462022-10-20020 October 2022 Report of Violations of the National Pollutant Discharge Elimination System Permit San Onofre Nuclear Generating Station (Songs), Units 2 and 3 ML22277A0162022-09-29029 September 2022 Independent Spent Fuel Storage Installation Response to Request for Additional Information Regarding Request for Exemption from 10 CFR 72.106(b) IR 05000361/20220042022-09-26026 September 2022 NRC Inspection Report 05000361/2022-004 and 05000362/2022-004 ML22238A0552022-08-29029 August 2022 U.S. Nuclear Regulatory Commission'S Analysis of Southern California Edison'S Decommissioning Funding Status Report for San Onofre Nuclear Generating Station, Units 1, 2, and 3 ML22234A1602022-07-31031 July 2022 Final Report Per 10 CFR Part 21, Degraded Snubber SF1154 Hydraulic Fluid Batch No. 18CLVS431 ML22207B8612022-07-26026 July 2022 NRC (Public) Inspection Report 05000361/2022003; 05000362/2022003 IR 05000361/20220032022-07-26026 July 2022 NRC Inspection Report (Public) 05000361-2022003 and 05000362-2022003 (002) IR 05000361/20220022022-05-12012 May 2022 NRC Inspection Report 05000361/2022-002 and 05000362/2022-002 ML22136A0842022-05-12012 May 2022 Independent Spent Fuel Storage Installation, 2021 Annual Radiological Environmental Operating Report 2024-09-18
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SOUTHERN CALIFORNIAEDISONAn EDISON INTERNATIONAL CompanyRichard I. St. OngeDirector, Nuclear Regulatory Affairs andEmergency PlanningMarch 20, 201310 CFR 50.4U.S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555-0001
Subject:
Docket No. 50-361Response to Request for Additional Information (RAIs 39, 43, 44, 58 and 61)Regarding Confirmatory Action Letter Response(TAC No. ME 9727)San Onofre Nuclear Generating Station, Unit 2
References:
1.Letter from Mr. Elmo E. Collins (USNRC) to Mr. Peter T. Dietrich (SCE), datedMarch 27, 2012, Confirmatory Action Letter 4-12-001, San Onofre NuclearGenerating Station, Units 2 and 3, Commitments to Address Steam GeneratorTube Degradation2. Letter from Mr. Peter T. Dietrich (SCE) to Mr. Elmo E. Collins (USNRC), datedOctober 3, 2012, Confirmatory Action Letter -Actions to Address SteamGenerator Tube Degradation, San Onofre Nuclear Generating Station, Unit 23. Email from Mr. James R. Hall (USNRC) to Mr. Ryan Treadway (SCE), datedFebruary 20, 2013, Request for Additional Information (RAIs 38-52) RegardingResponse to Confirmatory Action Letter, San Onofre Nuclear GeneratingStation, Unit 24. Email from Mr. James R. Hall (USNRC) to Mr. Ryan Treadway (SCE), datedFebruary 21, 2013, Request for Additional Information (RAIs 53-67) RegardingResponse to Confirmatory Action Letter, San Onofre Nuclear GeneratingStation, Unit 2
Dear Sir or Madam,
On March 27, 2012, the Nuclear Regulatory Commission (NRC) issued a Confirmatory ActionLetter (CAL) (Reference 1) to Southern California Edison (SCE) describing actions that the NRCand SCE agreed would be completed to address issues identified in the steam generator tubesof San Onofre Nuclear Generating Station (SONGS) Units 2 and 3. In a letter to the NRC datedOctober 3, 2012 (Reference 2), SCE reported completion of the Unit 2 CAL actions andincluded a Return to Service Report (RTSR) that provided details of their completion.By emails dated February 20, 2013 (Reference 3) and February 21, 2013 (Reference 4), theNRC issued Requests for Additional Information (RAIs) regarding the CAL response.Enclosure 1 of this letter provides the response to RAIs 39, 43, 44, 58 and 61.P.O. Box 128San Clemente, CA 92672 Document Control Desk March 20, 2013There are no new regulatory commitments contained in this letter. If you have any questions orrequire additional information, please call me at (949) 368-6240.Sincerely,
Enclosure:
- 1. Response to RAIs 39, 43, 44, 58 and 61cc: E. E. Collins, Regional Administrator, NRC Region IVJ. R. Hall, NRC Project Manager, SONGS Units 2 and 3G. G. Warnick, NRC Senior Resident Inspector, SONGS Units 2 and 3R. E. Lantz, Branch Chief, Division of Reactor Projects, NRC Region IV ENCLOSURE 1SOUTHERN CALIFORNIA EDISONRESPONSE TO REQUEST FOR ADDITIONAL INFORMATIONREGARDING RESPONSE TO CONFIRMATORY ACTION LETTERDOCKET NO. 50-361TAC NO. ME 9727Response to RAIs 39, 43, 44, 58 and 61 RAI 39In Reference 2, p. 36, Bottom of page, the term P is not defined. Please define the parameter, andexplain (1) how it is formulated, and (2) how it is related to the ATHOS computed nodal void fraction.RESPONSENote: RAI Reference 2 is "Evaluation of Stability Ratio for Return to Service," prepared by MHI,Document No. L5-04GA567, Revision 6.Define the parameter 13As used in RAI Reference 2, P is the homogeneous void fraction defined by the volumetric flowrates of the gas and liquid phases:V9 + VThe correlations used in the stability ratio evaluation depend, in part, on the homogeneous voidfraction. Experiments control void fraction by varying the volumetric flow rate of the two phases,so experimental data are correlated to homogeneous void fraction. Homogeneous void fractiondistribution along the tube length is not an ATHOS output. The homogeneous void fraction iscalculated by using the Smith correlation and nodal void fraction obtained from ATHOS outputas outlined below.1) Explain how 13 is formulatedThe homogeneous void fraction, P, is formulated in terms of quality (x, vapor mass flowfraction). The definition for quality is:,%Mrg + 1711The mass flow rate of each phase is defined as;=h pg -V1Substitute the definition for each mass phase into the expression for quality:X=-Th liui + Pv f V1The liquid volume flow fraction (11 -p)is derived from the homogeneous void fraction:1g +3 V, 1ýPage 2 of 9 Substitute in the quality expression:_' _ +_ , g + fl,PgPg
- _ g _ _Pgg+i~ 1I4 V, Pgfl3+PI-(1/l)Vg + i;' P~g V~+V9 I " Vg+ V,Solve for P3 as a function of quality, x:P 9f =p Pg f X + Pp X -P 'fl XP, "" X + Pg " -P9 " l " X = P" XPI .xP 'x + Pg (- x)2) Explain how P3 is related to the ATHOS computed nodal void fraction aHomogenous void fraction (P) is obtained from local void fraction (a) through the use of theSmith correlation and saturated density for liquid and vapor." ATHOS provides nodal void fraction (a) as a function of position along the tube.* Nodal void fraction (a) is converted to quality (x) by using the Smith correlation:Pa p1 x p1) -)P* Quality is used to calculate homogeneous void fraction (p3):Pi .xP 'X + Pg (1- x)Terminologya: Nodal Void Fractionp9: Vapor Densityfl: Homogeneous Void Fraction (vapor volume fraction)PI: Liquid Densitymg: Vapor Massmi: Liquid MassVg: Vapor VolumeV1: Liquid Volumex : Mixture Quality (vapor mass fraction)e: Entrainment Coefficient (ratio of the mass of liquid flowing in thehomogeneous mixture to the total mass of water flowing)Page 3 of 9 RAI 43In Reference 4, p. 15, Section 6.3, "Assumption," Item (1) "Fluid force," please explain the basisfor the statement, "The turbulent excitation force is evaluated and fluid force caused by FEI isnot taken into account..." It is not clear how the turbulent excitation force is used to determinewhen the friction force is adequate to assume that there is no in-plane motion at the subjectAVB intersection. Please clarify the statement, "When the friction force due to contact force issmaller than the turbulent excitation force at an AVB support point, a tube can slide in the in-plane direction."RESPONSENote: RAI Reference 4 is "Analytical Evaluations for Operational Assessment," prepared byMHI, Document No. L5-04GA585, Revision 2.It is important to note that the analysis in RAI Reference 4, Section 6, was ultimately not used inthe Operational Assessment (OA) contained in Return to Service Report Attachment 6,Appendix B. As explained in the response to RAI 35, an alternate analysis was developed andvalidated based on the observed performance of Unit 3 and Unit 2.Explain the basis for the statement "The turbulent excitation force is evaluated and fluidforce caused by FEI is not taken into account ..."The condition being evaluated is the design condition with no relative motion between the tubeand the AVB. In the design condition FEI is not occurring so the only driving force is fromturbulence.Please clarify the statement, "When the friction force due to contact force is smaller thanthe turbulent excitation force at an AVB support point, a tube can slide in the in-planedirection."The support effectiveness criterion developed in RAI Reference 4, Section 6, assumed only oneAVB support resists all the flow force along the U-bend tube. As long as the static resistingfriction force at an AVB intersection is greater than the driving force due to flow, the tube will notmove in the in-plane direction at the AVB intersection. For this support effectiveness criterion,the AVB intersection was considered to be an active support. As indicated above and asdiscussed in the response to RAI 35, this support effectiveness criterion was not used for theOA contained in Return to Service Report Attachment 6, Appendix B.Page 4 of 9 RAI 44In Reference 4, p. 15, Section 6.3, "Assumption," Item (1) "Fluid force," it is assumed there is noin-plane motion if the stability ratio (SR) is less than 1.0. How has MHI accounted for thepotential that in-plane tube motion may occur at a SR less than 1.0 and how is the analysisresult affected if a smaller value is used for this threshold?RESPONSENote: RAI Reference 4 is "Analytical Evaluations for Operational Assessment," prepared byMHI, Document No. L5-04GA585, Revision 2.RAI Reference 2 is "Evaluation of Stability Ratio for Return to Service," prepared by MHI,Document No. L5-04GA567, Revision 6.RAI Reference 4, p. 15, Section 6.3, "Assumption," Item (1) "Fluid force," does not assume thereis no in-plane tube motion when the SR is less than 1.0. The assumption is that no in-plane FEIoccurs when the SR is less than 1.0. This is consistent with the definition of FEI.How has MHI accounted for the potential that in-plane tube motion may occur at a SRless than 1.0?RAI Reference 4 does not address the potential that in-plane tube motion may occur at a SRless than 1.0. The in-plane motion that occurs at SR less than 1.0 is accounted for in RAIReference 2. The dynamic analysis model described in RAI Reference 2 allows for in-planemotion.How is the analysis result affected if a smaller value is used for this threshold?Stability analysis is performed subsequent to the calculation of required contact force. Thestability ratio threshold has no effect on the contact force analysis result. In the response toRAI 35, we have explained that this derivation of contact force was not used in the OperationalAssessment (OA) contained in Return to Service Report Attachment 6, Appendix B.Page 5 of 9 RAI 58In Reference 3, Appendix 9, Table 6.2-1, which parameters are sampled randomly at eachtube/AVB intersection? Why is this appropriate in lieu of assuming a functional relationship foreach given parameter from tube to tube in a given column of tubes? For parameters (e.g., AVBtwist) assumed to follow a functional relationship from tube to tube in the same column, providethe basis for the assumed relationship. For AVB twist, how does the assumed relationshiprelate to Figure 6.2-2?RESPONSENote: RAI Reference 3 is "Tube Wear of Unit-3 RSG -Technical Evaluation Report." preparedby MHI, Document No. L5-04GA564, Revision 9.Six parameters representing manufacturing variations were considered for the contact forceanalysis: tube ovality (G value), tube pitch, tube flatness, AVB thickness, AVB twist, and AVBflatness.Tube G valueTube pitch(True position of land)Tube FlatnessAVB thicknessI AVB twistAVB FlatnessThe input values were randomly sampled at each tube/AVB intersection for the first fourparameters. AVB twist was randomly sampled at each AVB and then varied at each tubeintersection along the AVB following a functional relationship. AVB flatness was not used incontact force analysis. The basis for using either random sampling or a functional relationshipfor each parameter follows:Page 6 of 9 Tube Ovality (G value):Tube ovality was randomly sampled at each tube/AVB intersection. The random distribution oftube ovality from tube-to-tube was based on actual tube manufacturing data which provide moreaccurate results than assuming a functional relationship.Tube Pitch (TSP hole variation from true position):The contact force model included the effect of tube pitch by using gap elements at TSP holes.The gap size was randomly sampled at each tube-to-TSP intersection at the top TSP from adistribution based on the fabrication tolerance for TSP hole pitch. Therefore, random samplingis more appropriate than assuming a functional relationship.Tube Flatness:Tube flatness was randomly sampled at each tube/AVB intersection from a distribution basedon the fabrication tolerance. Random sampling for this parameter is appropriate because actualflatness varies randomly both from tube-to-tube and along the tube length.AVB Thickness:AVB thickness was randomly sampled at each tube/AVB intersection. As Table 6.2-1 shows,separate AVB thickness distributions were sampled for Unit 2 and Unit 3 based onmeasurement results. Therefore, random sampling is appropriate.AVB Flatness:AVB flatness was not used in the contact force analysis. AVB flatness variations have anegligible effect on contact forces.Page 7 of 9 AVB Twist:AVB twist was randomly sampled as a property of each AVB, then varied systematically alongthe length of the AVB using a functional relationship. AVB twist is generated by bending astraight AVB bar during AVB manufacturing, as shown in the following figure. As a result of thisprocess, an unloaded AVB (i.e., before insertion in the tube bundle) has a uniform twist alongeach straight leg.bendingTwisted TwistedFigure 6.2-2 shows the functional form of the AVB twist factor that represents the variation oftorsional stiffness along the length of an AVB in the contact force model. Since the AVB hasuniform cross section, its torsional stiffness at each tube/AVB intersection along its length isinversely proportional to the distance of the intersection from the nose and retaining barendpoints of the AVB. This is the reason for the characteristic "bathtub" shape of the AVB twistfactor depicted in Figure 6.2-2. For more details regarding the basis for the AVB twist factor,please see the response to RAIs 64 through 66.Page 8 of 9 RAI 61Reference 3, Appendix 9, Attachment 9-3, Figure 4.1.2-3. Discuss the pedigree of the data inthis figure and how it differs from Reference 2, Figure 6-19 and 6-20. Please explain thedifferences between the Reference 3 versus the Reference 2 figures for dings exceeding 0.5volts?RESPONSENote: RAI Reference 3 is "Tube Wear of Unit-3 RSG -Technical Evaluation Report." preparedby MHI, Document No. L5-04GA564, Revision 9.RAI Reference 2 is "SONGS U2C1 7 Steam Generator Operational Assessment for Tube-to-Tube Wear," prepared by Areva NP Inc. Document No. 51-9187230-000, Revision 0.The data plotted in Figure 4.1.2-3 of Appendix 9, Attachment 9-3 in RAI Reference 3 and thosein Figures 6-19 and 6-20 in RAI Reference 2 use the same Pre-Service Inspection Eddy CurrentTesting (ECT) data. The ECT data were obtained under AREVA's 10 CFR 50 Appendix Bprogram for the Pre-Service Inspection and are retained under SONGS Steam GeneratorProgram.The differences between the figures in RAI References 2 and 3 are:" The figures in RAI Reference 2 cover the signals on the U-bend region, which includethe signals on freespan area and those at U-bend AVB locations but do not include thesignals at TSP locations. The plotted data cover the voltage range from 0.5 to 1.5 Volts." The figures in RAI Reference 3 cover the signals on the locations of structures, whichinclude the signals at U-bend AVB locations and those at TSP locations but do notinclude the signals on freespan area. The plotted data cover the full voltage range of thereported ding indications.RAI Reference 2 RAI Reference 3Figures 6-19 Figure 4.1.2-3and 6-20Pre-service ECT Inspection Data Yes YesU-bend Freespan Dings Yes NoTSP Dings No YesAVB Dings < 0.5 Volts No YesAVB Dings 0.5-1.5 Volts Yes YesAVB Dings > 1.5 Volts No YesDespite these differences, the figures support the comparison of the relative numbers of contactsignals in the upper bundle for Units 2 and 3 and demonstrate that contact forces are moresignificant in Unit 2 than in Unit 3.Page 9 of 9