Letter Sequence Response to RAI |
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Initiation
- Request, Request, Request, Request, Request, Request, Request
- Acceptance
- Supplement, Supplement, Supplement, Supplement, Supplement, Supplement
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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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Category:Letter
MONTHYEARML24022A1492024-01-17017 January 2024 Independent Spent Fuel Storage Installation, Revision 4 to the Physical Security Plan 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 ML22122A0402022-04-28028 April 2022 (Songs), Units 1, 2 and 3 - Annual Radioactive Effluent Release Report - 2021 ML22105A5662022-04-0505 April 2022 20053 Letter - OI Closure to Licensee - Wrongdoing Signed ML22081A1692022-03-31031 March 2022 SONGS Application Acceptance Proposed Exemption from Title 10 of the CFR, Part 72.106(b), ISFSI Controlled Boundary IR 05000206/20214022022-03-24024 March 2022 Notice of Violation, NRC Inspection Report 05000206/2021402, 05000361/2021402, 05000362/2021402, and 07200041/2021401; and Investigation Report 4-2021-004- Public- Cover Letter ML22084A0552022-03-23023 March 2022 10 CFR 50.82(a)(8Xv and VII) and 10 CFR 72.30(c) Decommissioning Funding Status Report 2021 San Onofre Nuclear Generating Station Units 1, 2, and 3 and Independent Spent Fuel Storage Installation IR 05000361/20220012022-03-14014 March 2022 NRC Inspection Report 05000361/2022-001; 05000362/2022-001 ML22066B0242022-03-0303 March 2022 (Songs), Units 1, 2, and 3, and the Independent Spent Fuel Storage Installation - Revision 2 to the ISFSI-Only Emergency Plan and Associated Changes to Emergency Plan Implementing Procedures ML22062B0282022-02-28028 February 2022 and Independent Spent Fuel Storage Installation (Isfsi), Response to Request for Supplemental Information Regarding Request for Exemption from 10 CFR 72.106(b) ML22059B0392022-02-25025 February 2022 International, Proprietary Information to Support SCE Exemption ML22060A1132022-02-24024 February 2022 Nuclear Property Insurance ML22060A1152022-02-24024 February 2022 Generation Station Units 1, 2 and 3, Annual Radioactive Effluent Release Report for Independent Spent Fuel Storage Installation - 2021 ML22048B4972022-02-15015 February 2022 (Songs), Units 1, 2 and 3 - 2021 Annual Turtle Incidental Take Report ML22031A1112022-01-26026 January 2022 (Songs), Units 2 and 3 - Annual Corporate Financial Reports 2024-01-17
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SOUTHERN CALIFORNIA Richard 1. St. OngeEDISON° Director, Nuclear Regulatory Affairs andEmergency PlanningAn EDISON INTERNATIONAL CompanyMarch 22, 201310 CFR 50.4U.S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555-0001
Subject:
Docket No. 50-361Response to Request for Additional Information (RAI 18), Revision IRegarding 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. Letter from Mr. James R. Hall (USNRC) to Mr. Peter T. Dietrich (SCE), datedDecember 26, 2012, Request for Additional Information Regarding Responseto Confirmatory Action Letter, San Onofre Nuclear Generating Station, Unit 24. Letter from Mr. Richard J. St. Onge (SCE) to NRC Document Control Desk,dated January 24, 2013, Response to Request for Additional Information(RAI 18) Regarding Confirmatory Action Letter Response, San Onofre NuclearGenerating Station, 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 letter dated December 26, 2012 (Reference 3), the NRC issued Requests for AdditionalInformation (RAIs) regarding the CAL response. SCE provided the response to RAI 18 in aletter dated January 24, 2013 (Reference 4). Enclosure 1 of this letter provides Revision 1 tothe RAI 18 response.P.O. Box 128San Clemente, CA 92672 Document Control Desk March 22, 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,
Enclosures:
- 1. Response to RAI 18, Revision 1cc: 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 RAI 18, Revision 1 RAI 18Reference 1, Section 11.1, page 52 -SCE proposes to upgrade the vibration and loose partsmonitoring system (VLPMS) as a defense-in-depth measure to enhance plant monitoringcapability to facilitate early detection of a steam generator tube leak and ensure immediate andappropriate plant operator and management response.Fluid Elastic Instability (FEI) was identified as a main cause of the tube wear for both the Unit 2and 3 steam generators. The FEI experienced is due to a combination of the conditions ofsteam quality, secondary side fluid velocity in the vicinity of the tube bundle, and steam voidfraction, and the degree of such fluid elastic instability is related to the damping provided byinternal support structures. According to your report, "steam quality directly affects the fluiddensity outside the tube, affecting the level of hydrodynamic pressure that provides the motiveforce for tube vibration. When the energy imparted to the tube from hydrodynamic pressure(density times velocity squared, or pv2) is greater than the energy dissipated through damping,FEI will occur." However, the proposed plant VLPMS enhancement does not appear to directlymonitor steam quality, secondary side fluid velocity, or steam void fraction.Please provide the following information to address the effectiveness of the enhanced VLPMS:a. Describe the specific purpose of using the enhanced VLPMS equipment for monitoringsteam generator performance. For example, is it to be used for monitoring acousticnoise indicative of flow velocity, steam quality, and void fraction, or for the measurementof metallic noise indicative of vibration of tubes against each other or against tubesupport structures? Exactly how will this be done? What is the theory of operation? If itwill be used to monitor an increase in pv2 leading to the onset of FEI, provide adescription of the correlation of the velocity of steam voids through the secondary side ofthe steam generator and the relative changes in characteristics of the signal output fromthe various VLPMS accelerometers. If it is to be used for detecting actual tube vibration,provide a description of the process that will be used for discerning actual tube vibrationnoise from background noise, and the required threshold identification criteria that will beapplied to reach the conclusion that tube vibration is occurring.b. Identify the ranges of amplitudes and frequencies of the acoustic noise signals fromeach accelerometer that are indicative of an approach to the conditions leading to FEI oractual tube vibration, and the reasons for selection of the more sensitive accelerometers.Also, discuss the required response time of the signal processing equipment needed todetect and continuously monitor either fluid velocities within the steam generator or tubeimpact noise, depending on the intended use of the enhanced VLPMS, and the actualresponse time capabilities of the equipment, from sensor through processed signaloutput, that is being proposed for use.c. Discuss the acceptance criteria (e.g., magnitude of signal, plant power level, etc.) thatwill be used to establish the setpoints for the alarms described in Section 11 of yourreport: "The signals from these sensors are compared with preset alarm setpoints."Provide a description of how the alarm setpoints were established, and at what pointduring the start-up of Unit 2 will these alarm setpoints be calibrated into the VLPMS. Ifthe setpoints have not yet been determined, provide a description of your plan fordetermining and implementing these settings.Page 2 of 5
- d. Describe the planned operator actions and any changes to the procedures forresponding to alarms or signals potentially indicative of tube-to-tube contact, includingtime limits for analyzing the signals and taking any necessary action including plantshutdown. Describe the lessons learned that have been drawn from the signals ofpotential metal-to-metal contact experienced in Unit 3 and how these lessons have beenfactored into current procedures.e. A description of how you determined that acoustic noise monitoring and predictive signalprocessing was the best method for monitoring either the onset of FEI or actual tubevibration, including a list of other methods (e.g., time domain reflectivity probescalibrated for steam void propagation monitoring) that had been considered forenhancing steam generator tube monitoring during start-up of Unit 2, and the reasons fortheir rejection.RESPONSE -Revision IThe purpose of the upgraded vibration and loose parts monitoring system (VLPMS) is to provideadditional monitoring capabilities for steam generator (SG) secondary side acoustics. Theupgraded VLPMS is capable of recording secondary side acoustic signals via accelerometersmounted on the external shell of the SGs at locations near the upper tube bundle andtubesheet. The upgraded VLPMS will be used as a backward looking analysis tool insubsequent inspection outages should unexpected wear be discovered. The upgraded VLPMSwill enable SCE to evaluate historical SG secondary side acoustic signal data for events whichmay help with the understanding of the causes of unexpected tube wear. To gain experiencewith the analysis tools during the next cycle, the recorded data will be reviewed on a monthlybasis in accordance with plant procedures.The Unit 2 Return to Service (RTS) report describes the upgrades to the VLPMS in Section 11.1as an additional action to provide monitoring capabilities for secondary side acoustic signals.SCE did not propose the upgrade of the VLPMS as a defense-in-depth measure nor as ameans of monitoring steam quality, secondary side fluid velocity, or steam void fraction.Corrective measures to control these secondary side parameters are addressed in Section 8 ofthe RTS report. The defense-in-depth measures being taken in support of Unit 2 return toservice are described in Section 9 of the RTS report.The theory of operation of the VLPMS data acquisition equipment is provided as follows:The Vibration and Loose Parts Monitoring System (V&LPMS) is a stand-alone systemdesigned to perform loose parts detection and vibration monitoring functions. The loosepart detection function is designed to fulfill the requirements of the loose parts detectionsystem as set forth in Regulatory Guide 1.133. The design objective of the loose partsdetection portion of the V&LPMS is to detect the presence of loose parts in the reactorcoolant system (RCS) and annunciate an alarm in the control room when a loose part isdetected.The system consists of loose parts and vibration sensors, preamplifiers and acomputerized data acquisition and processing system. The sensors and preamplifiersare located inside the containment and the data acquisition and processing equipment ishoused in a cabinet located in the control room cabinet area. The equipment locatedinside containment consists of piezo-electric sensors, preamplifiers and associatedPage 3 of 5 cabling at each of the following natural collection regions of each unit to detect looseparts:* Upper reactor vessel; vessel head on head lift rig stopper" Lower reactor vessel; outside wall* Steam generator E088; outside wall* Steam generator E089; outside wallThe RCS component vibration monitoring, reactor internal vibration monitoring, andvibration data analysis features are on-demand functions. The on-demand featuresprovided with the VLPMS allow the selection of any two loose parts, vibration or reactorinternal vibration channels for vibration monitoring or analysis. The on-demand dataacquisition and analysis features also allow a live channel signal or historical data fromthe historical data file to be selected for time domain and/or frequency domain analysis,displayed, stored and/or printed.The upgrades to the VLPMS consist of:* Relocation of existing VLPMS accelerometers (2 per SG) from the support skirt tolocations above and below the SG tubesheet. These will remain as VLPMS sensors tomeet Regulatory Guide 1.133, "Loose-Part Detection Program for the Primary System ofLight-Water-Cooled Reactors"* Installation of increased sensitivity accelerometers (2 per SG) at locations above andbelow the tubesheet" Installation of increased sensitivity accelerometers (2 per SG) on an 8 inch hand hole onthe side of the SGs to monitor for secondary side noises at the upper tube bundleRelocation of the accelerometers enhances the acoustic monitoring of the SG secondary sideby placing accelerometers closer to the upper tube bundle.The new accelerometers have an increased sensitivity of 25 pC/g compared with 10 pC/g forthe existing accelerometers. The acceptance criteria used to establish the setpoints for thealarms associated with the upgraded VLPMS accelerometers is the same as used with theRegulatory Guide 1.133 accelerometers. After Unit 2 reaches 70% power, background data iscollected and alarm thresholds are established to compensate for high background noise asdiscussed in Regulatory Guide 1.133, section C.1.b, "System Sensitivity."Operator actions for VLPMS alarms are controlled by the VLPMS trouble annunciatoroperations alarm response procedure. Upon an alarm, the VLPMS automatically records datafor all of the VLPMS accelerometer channels. The Control Room Shift Technical Advisor isinstructed by this procedure to immediately notify the system engineer supervisor for any looseparts channel alarms associated with the SGs. The Control Room Operator documents theVLPMS alarm in the site Corrective Action Program (CAP). The CAP requires an operabilitydetermination to be made within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of event discovery. Each loose parts alarmassociated with SGs will be independently reviewed by an offsite vendor.Following identification of tube-to-tube wear (TTW) caused by Fluid Elastic Instability (FEI) inUnit 3 and two indications of TTW in Unit 2, a review of the VLPMS alarms for the previousoperating cycle of both units was performed. No potential metal-to-metal contact alarms wererecorded for Unit 2. Potential metal-to-metal contact alarms were recorded for Unit 3. AnalysisPage 4 of 5 of data from Unit 3 VLPMS events concluded most of the events were the result of RCStemperature changes. A number of events were not directly associated with RCS temperaturechanges and were reviewed by on-site as well as independent off site personnel. Theindependent review concluded these alarms were caused by: "...true metallic impacts and notfalse indications from electrical noise or fluctuations in background noise." The review found theacoustic signals were similar to those that occur when the SGs shift during RCS temperaturetransients. None of the VLPMS alarms were attributed to SG tube vibration.Since the VLPMS is not designed to detect tube to tube contact, the absence of tube vibrationrelated VLPMS alarms is consistent with the capabilities of its design. The approach in theUnit 2 RTS plan is to eliminate the causes of TTW caused by FEI. Reducing power reduces SGsecondary side thermal-hydraulic parameters to values within the industry's experience. Whilethe RTS plan does not require a direct method to measure tube vibration, SCE determined itwas appropriate to upgrade the existing VLPMS as discussed above.Page 5 of 5