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| | number = ML13038A009 | | | number = ML13038A009 |
| | issue date = 02/04/2013 | | | issue date = 02/04/2013 |
| | title = San Onofre Nuclear Generating Station, Unit 2, Response to Request for Additional Information (RAI 6) Regarding Confirmatory Action Letter Response (TAC ME9727) | | | title = Response to Request for Additional Information (RAI 6) Regarding Confirmatory Action Letter Response |
| | author name = St.Onge R J | | | author name = St.Onge R |
| | author affiliation = Southern California Edison Co | | | author affiliation = Southern California Edison Co |
| | addressee name = | | | addressee name = |
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| | document type = Letter | | | document type = Letter |
| | page count = 4 | | | page count = 4 |
| | project = TAC:ME9727, TAC:ME9727 | | | project = TAC:ME9727 |
| | stage = Response to RAI | | | stage = Response to RAI |
| }} | | }} |
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| =Text= | | =Text= |
| {{#Wiki_filter:V SOUTHERN CALIFORNIAEDISONAn EDISON INTERNATIONAL CompanyRichard I. St. OngeDirector, Nuclear Regulatory Affairs andEmergency PlanningFebruary 4, 201310 CFR 50.4U.S. Nuclear Regulatory CommissionATTN: Document Control Desk.Washington, DC 20555-0001Subject:Docket No. 50-361Response to Request for Additional Information (RAI 6)Regarding Confirmatory Action Letter Response(TAC No. ME 9727)San Onofre Nuclear Generating Station, Unit 2References: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 2Dear 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. Enclosure 1 of this letter provides theresponses to RAI 6.P.O. Box 128San Clemente, CA 92672 Document Control Desk-2-February 4, 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 RAl 6cc: 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 6Page 1 of 2 RAI 6Regarding Reference 4, page 4-5, it seems that depths of undetected flaws are assumed to beassociated with POD < 0.05. Why is this conservative? Is there a possibility that someundetected flaws may be associated with higher values of POD?RESPONSEIt is possible that there could exist some undetected wear above the 5% probability of detection(POD) performance level. However, the likelihood of any significant number of undetectedindications with depths that exceed the 5% POD at the beginning of the next operating cycle isvery low. This is based on the conditions following Southern California Edison's (SCE's)enhanced inspections and tube plugging for Unit 2 as discussed below:1) A large sample of tubes in the high-wear region underwent a double inspection, firstwith the bobbin probe followed later with +PointTM. The resulting POD performancewill be better than either technique.2) As discussed in RAI Reference 4, the threshold of detection for the +PointTM isapproximately 5% through wall (TW). Based on Examination TechniqueSpecification Sheet (ETSS) 27902.2 data for +PointTM, all indications above thisthreshold value were detected for the ETSS data set.3) Screening criteria were developed to identify tubes susceptible to tube-to-tube wear(TTW). These tubes were preventively plugged. These preventively plugged tubesare the most likely to have TTW.The use of POD thresholds for TTW and support wear are reasonable and conservative forassessing the mid-cycle operation for Unit 2. To evaluate the sensitivity of this assumption forundetected TTVV, the operational assessment (OA) model in RAI Reference 4 was evaluated fora higher threshold value for the +PointTM probe. This threshold value was conservatively takenas 0.95 instead of 0.05. The 0.95 POD detection limit is used in defining the worst-caseindication at beginning of the operating cycle when performing a deterministic single-tubeanalysis per the industry guidelines. This would effectively double the threshold depth for anundetected TTW indication from about 5% TW to 10% TW in the Unit 2 simulation based onFigure 4-3 of RAI Reference 4. The results from this analysis reduce the allowable inspectioninterval by less than 0.06 years at power. The selection of the threshold detection limit for TTWhas a minor impact on the probability of burst results shown in Figure 5-4 of RAI Reference 4even when a more conservative POD threshold value is assumed.The treatment of undetected tube support wear in the 1350 no degradation detected (NDD)tubes is very conservative. RAI Reference 4 assumes that every tube in this group hasundetected tube wear at both anti-vibration bar (AVB) and tube support plate (TSP) locations.The wear locations are assigned based on the distribution of tube support wear observed for thetube that had detected wear at the end of the previous operating cycle. The model algorithmassigns five active wear locations, on average, in each NDD tube (two minimum, one at AVBand one at TSP). This assumes that the presence of tube/support wear in the NDD tubesduring the mid-cycle will be the same as observed in the worn tubes in the first cycle.Additionally, the likelihood of having multiple NDD indications with significant depths at thebeginning of the next operating cycle is low. The process of assigning wear locations withdepths using a 5% POD threshold for the 1350 NDD tubes will result in a conservative estimateof wear index at the beginning of the next operating cycle.Page 2 of 2 | | {{#Wiki_filter:V SOUTHERN CALIFORNIA Richard I. St. Onge EDISON Director, Nuclear Regulatory Affairs and Emergency Planning An EDISON INTERNATIONAL Company February 4, 2013 10 CFR 50.4 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk. |
| }} | | Washington, DC 20555-0001 |
| | |
| | ==Subject:== |
| | Docket No. 50-361 Response to Request for Additional Information (RAI 6) |
| | 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), dated March 27, 2012, Confirmatory Action Letter 4-12-001, San Onofre Nuclear Generating Station, Units 2 and 3, Commitments to Address Steam Generator Tube Degradation |
| | : 2. Letter from Mr. Peter T. Dietrich (SCE) to Mr. Elmo E. Collins (USNRC), dated October 3, 2012, Confirmatory Action Letter - Actions to Address Steam Generator Tube Degradation, San Onofre Nuclear Generating Station, Unit 2 |
| | : 3. Letter from Mr. James R. Hall (USNRC) to Mr. Peter T. Dietrich (SCE), dated December 26, 2012, Request for Additional Information Regarding Response to Confirmatory Action Letter, San Onofre Nuclear Generating Station, Unit 2 |
| | |
| | ==Dear Sir or Madam,== |
| | |
| | On March 27, 2012, the Nuclear Regulatory Commission (NRC) issued a Confirmatory Action Letter (CAL) (Reference 1) to Southern California Edison (SCE) describing actions that the NRC and SCE agreed would be completed to address issues identified in the steam generator tubes of San Onofre Nuclear Generating Station (SONGS) Units 2 and 3. In a letter to the NRC dated October 3, 2012 (Reference 2), SCE reported completion of the Unit 2 CAL actions and included 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 Additional Information (RAIs) regarding the CAL response. Enclosure 1 of this letter provides the responses to RAI 6. |
| | P.O. Box 128 San Clemente, CA 92672 |
| | |
| | Document Control Desk February 4, 2013 There are no new regulatory commitments contained in this letter. If you have any questions or require additional information, please call me at (949) 368-6240. |
| | Sincerely, |
| | |
| | ==Enclosure:== |
| | : 1. Response to RAl 6 cc: E. E. Collins, Regional Administrator, NRC Region IV J. R. Hall, NRC Project Manager, SONGS Units 2 and 3 G. G. Warnick, NRC Senior Resident Inspector, SONGS Units 2 and 3 R. E. Lantz, Branch Chief, Division of Reactor Projects, NRC Region IV |
| | |
| | ENCLOSURE 1 SOUTHERN CALIFORNIA EDISON RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RESPONSE TO CONFIRMATORY ACTION LETTER DOCKET NO. 50-361 TAC NO. ME 9727 Response to RAI 6 Page 1 of 2 |
| | |
| | ===RAI 6=== |
| | Regarding Reference 4, page 4-5, it seems that depths of undetected flaws are assumed to be associated with POD < 0.05. Why is this conservative? Is there a possibility that some undetected flaws may be associated with higher values of POD? |
| | |
| | ===RESPONSE=== |
| | It is possible that there could exist some undetected wear above the 5% probability of detection (POD) performance level. However, the likelihood of any significant number of undetected indications with depths that exceed the 5% POD at the beginning of the next operating cycle is very low. This is based on the conditions following Southern California Edison's (SCE's) enhanced inspections and tube plugging for Unit 2 as discussed below: |
| | : 1) A large sample of tubes in the high-wear region underwent a double inspection, first with the bobbin probe followed later with +PointTM. The resulting POD performance will be better than either technique. |
| | : 2) As discussed in RAI Reference 4, the threshold of detection for the +PointTM is approximately 5% through wall (TW). Based on Examination Technique Specification Sheet (ETSS) 27902.2 data for +PointTM, all indications above this threshold value were detected for the ETSS data set. |
| | : 3) Screening criteria were developed to identify tubes susceptible to tube-to-tube wear (TTW). These tubes were preventively plugged. These preventively plugged tubes are the most likely to have TTW. |
| | The use of POD thresholds for TTW and support wear are reasonable and conservative for assessing the mid-cycle operation for Unit 2. To evaluate the sensitivity of this assumption for undetected TTVV, the operational assessment (OA) model in RAI Reference 4 was evaluated for a higher threshold value for the +PointTM probe. This threshold value was conservatively taken as 0.95 instead of 0.05. The 0.95 POD detection limit is used in defining the worst-case indication at beginning of the operating cycle when performing a deterministic single-tube analysis per the industry guidelines. This would effectively double the threshold depth for an undetected TTW indication from about 5% TW to 10% TW in the Unit 2 simulation based on Figure 4-3 of RAI Reference 4. The results from this analysis reduce the allowable inspection interval by less than 0.06 years at power. The selection of the threshold detection limit for TTW has a minor impact on the probability of burst results shown in Figure 5-4 of RAI Reference 4 even when a more conservative POD threshold value is assumed. |
| | The treatment of undetected tube support wear in the 1350 no degradation detected (NDD) tubes is very conservative. RAI Reference 4 assumes that every tube in this group has undetected tube wear at both anti-vibration bar (AVB) and tube support plate (TSP) locations. |
| | The wear locations are assigned based on the distribution of tube support wear observed for the tube that had detected wear at the end of the previous operating cycle. The model algorithm assigns five active wear locations, on average, in each NDD tube (two minimum, one at AVB and one at TSP). This assumes that the presence of tube/support wear in the NDD tubes during the mid-cycle will be the same as observed in the worn tubes in the first cycle. |
| | Additionally, the likelihood of having multiple NDD indications with significant depths at the beginning of the next operating cycle is low. The process of assigning wear locations with depths using a 5% POD threshold for the 1350 NDD tubes will result in a conservative estimate of wear index at the beginning of the next operating cycle. |
| | Page 2 of 2}} |
Letter Sequence Response to RAI |
|---|
|
Initiation
- Request, Request, Request, Request, Request, Request, Request
- Acceptance
- Supplement, Supplement, Supplement, Supplement, Supplement, Supplement
|
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
[Table View] |
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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
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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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V SOUTHERN CALIFORNIA Richard I. St. Onge EDISON Director, Nuclear Regulatory Affairs and Emergency Planning An EDISON INTERNATIONAL Company February 4, 2013 10 CFR 50.4 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk.
Washington, DC 20555-0001
Subject:
Docket No. 50-361 Response to Request for Additional Information (RAI 6)
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), dated March 27, 2012, Confirmatory Action Letter 4-12-001, San Onofre Nuclear Generating Station, Units 2 and 3, Commitments to Address Steam Generator Tube Degradation
- 2. Letter from Mr. Peter T. Dietrich (SCE) to Mr. Elmo E. Collins (USNRC), dated October 3, 2012, Confirmatory Action Letter - Actions to Address Steam Generator Tube Degradation, San Onofre Nuclear Generating Station, Unit 2
- 3. Letter from Mr. James R. Hall (USNRC) to Mr. Peter T. Dietrich (SCE), dated December 26, 2012, Request for Additional Information Regarding Response to Confirmatory Action Letter, San Onofre Nuclear Generating Station, Unit 2
Dear Sir or Madam,
On March 27, 2012, the Nuclear Regulatory Commission (NRC) issued a Confirmatory Action Letter (CAL) (Reference 1) to Southern California Edison (SCE) describing actions that the NRC and SCE agreed would be completed to address issues identified in the steam generator tubes of San Onofre Nuclear Generating Station (SONGS) Units 2 and 3. In a letter to the NRC dated October 3, 2012 (Reference 2), SCE reported completion of the Unit 2 CAL actions and included 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 Additional Information (RAIs) regarding the CAL response. Enclosure 1 of this letter provides the responses to RAI 6.
P.O. Box 128 San Clemente, CA 92672
Document Control Desk February 4, 2013 There are no new regulatory commitments contained in this letter. If you have any questions or require additional information, please call me at (949) 368-6240.
Sincerely,
Enclosure:
- 1. Response to RAl 6 cc: E. E. Collins, Regional Administrator, NRC Region IV J. R. Hall, NRC Project Manager, SONGS Units 2 and 3 G. G. Warnick, NRC Senior Resident Inspector, SONGS Units 2 and 3 R. E. Lantz, Branch Chief, Division of Reactor Projects, NRC Region IV
ENCLOSURE 1 SOUTHERN CALIFORNIA EDISON RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RESPONSE TO CONFIRMATORY ACTION LETTER DOCKET NO. 50-361 TAC NO. ME 9727 Response to RAI 6 Page 1 of 2
RAI 6
Regarding Reference 4, page 4-5, it seems that depths of undetected flaws are assumed to be associated with POD < 0.05. Why is this conservative? Is there a possibility that some undetected flaws may be associated with higher values of POD?
RESPONSE
It is possible that there could exist some undetected wear above the 5% probability of detection (POD) performance level. However, the likelihood of any significant number of undetected indications with depths that exceed the 5% POD at the beginning of the next operating cycle is very low. This is based on the conditions following Southern California Edison's (SCE's) enhanced inspections and tube plugging for Unit 2 as discussed below:
- 1) A large sample of tubes in the high-wear region underwent a double inspection, first with the bobbin probe followed later with +PointTM. The resulting POD performance will be better than either technique.
- 2) As discussed in RAI Reference 4, the threshold of detection for the +PointTM is approximately 5% through wall (TW). Based on Examination Technique Specification Sheet (ETSS) 27902.2 data for +PointTM, all indications above this threshold value were detected for the ETSS data set.
- 3) Screening criteria were developed to identify tubes susceptible to tube-to-tube wear (TTW). These tubes were preventively plugged. These preventively plugged tubes are the most likely to have TTW.
The use of POD thresholds for TTW and support wear are reasonable and conservative for assessing the mid-cycle operation for Unit 2. To evaluate the sensitivity of this assumption for undetected TTVV, the operational assessment (OA) model in RAI Reference 4 was evaluated for a higher threshold value for the +PointTM probe. This threshold value was conservatively taken as 0.95 instead of 0.05. The 0.95 POD detection limit is used in defining the worst-case indication at beginning of the operating cycle when performing a deterministic single-tube analysis per the industry guidelines. This would effectively double the threshold depth for an undetected TTW indication from about 5% TW to 10% TW in the Unit 2 simulation based on Figure 4-3 of RAI Reference 4. The results from this analysis reduce the allowable inspection interval by less than 0.06 years at power. The selection of the threshold detection limit for TTW has a minor impact on the probability of burst results shown in Figure 5-4 of RAI Reference 4 even when a more conservative POD threshold value is assumed.
The treatment of undetected tube support wear in the 1350 no degradation detected (NDD) tubes is very conservative. RAI Reference 4 assumes that every tube in this group has undetected tube wear at both anti-vibration bar (AVB) and tube support plate (TSP) locations.
The wear locations are assigned based on the distribution of tube support wear observed for the tube that had detected wear at the end of the previous operating cycle. The model algorithm assigns five active wear locations, on average, in each NDD tube (two minimum, one at AVB and one at TSP). This assumes that the presence of tube/support wear in the NDD tubes during the mid-cycle will be the same as observed in the worn tubes in the first cycle.
Additionally, the likelihood of having multiple NDD indications with significant depths at the beginning of the next operating cycle is low. The process of assigning wear locations with depths using a 5% POD threshold for the 1350 NDD tubes will result in a conservative estimate of wear index at the beginning of the next operating cycle.
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