Letter Sequence Supplement |
---|
|
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] |
|
---|
Category:Letter
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
[Table view] |
Text
SOUTHERN CALIFORNIA Richard 1. St. Onge EDISObNJ Director, Nuclear Regulatory Affairs and L.. ON Emergency Planning An EDISON INTERNATIONAL Company May 20, 2013 10 CFR 50.4 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Docket No. 50-361 Supplement to Response to Request for Additional Information (RAI 70)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 4. Email from Mr. James R. Hall (USNRC) to Mr. Ryan Treadway (SCE), dated March 15, 2013, Request for Additional Information (RAIs 68-72) Regarding Response to Confirmatory Action Letter, San Onofre Nuclear Generating Station, Unit 2 5. Letter from Mr. Richard J. St. Onge (SCE) to Document Control Desk (USNRC), dated April 1, 2013, Response to Request for Additional Information (RAIs 68, 69, 70 and RAI 2 Revision 1) Regarding Confirmatory Action Letter Response, 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 e-mail dated March 15, 2013 (Reference 3), the NRC issued Requests for Additional Information (RAIs) regarding the CAL response.
SCE provided the response to RAIs 68, 69, 70, and RAI 2 Revision 1, in a letter dated April 1, 2013 (Reference 4). Enclosure 1 of this letter provides a supplement to the RAI 70 response.P.O. Box 128 San Clemente, CA 92672 Document Control Desk-2-May 20, 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.
Enclosure:
- 1. Supplement to RAI 70 response cc: A. T. Howell IIl, 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 SUPPLEMENT TO THE RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RESPONSE TO CONFIRMATORY ACTION LETTER DOCKET NO. 50-361 TAC NO. ME 9727 Supplement to RAI 70 Response RAI 70 Reference 1, Response to RAI 2 -It is unclear to the staff how TTW initiation times were calculated (see description on pages 4 and 5 (of 18)). Describe each individual step, in sequential order, to calculating TTVV initiation time for a given tube, for a given trial. Provide (or reference) in figure form all distributions that were sampled.RESPONSE SUPPLEMENT Note: RAI Reference 1 is SCE's "Response to Request for Additional Information (RAIs 2, 3, and 4) Regarding Confirmatory Action Letter Response," dated February 25, 2013. SCE responded to RAI 70 via letter "Request for Additional Information (RAI 70) Regarding Confirmatory Action Letter Response," dated April 1, 2013. This response supplement demonstrates the process explained in the response to RAI 70.Single Trial Calculation of Initiation Time for Tube R92 C84 in 3E-088 The purpose of this discussion is to provide further details into how the initiation time is calculated using a bi-linear wear index model, which represents the tube conditions before and after in-plane instability.
It presents an example calculation in the context of the analytical procedure given in RAI 70 response.
Also discussed is the determination of the anti-vibration bar (AVB) wear rates at tube contact locations.
Figure 1 shows the calculation of tINIT for a single trial. Tube R92 C84 in 3E-088 was chosen to show the calculation procedure.
The analysis variables are shown to aid in the description of the probabilistic solution for TTW initiation time and the numerical calculations.
The important points on the wear index lines are labeled A through E.Governing Equations The equation that defines the initiation time is MP-U -WIR 2 tcYc WIR 1 -WIR 2 Where: EOP is the end of the operating period for Unit 3, and tINIT is the initiation time (Figure 1 Point B)MOP-US is the wear index at EOP from AVB wear in the upper supports (Figure 1 Point D)WIR 1 is the growth rate in the WIAVB-US prior to initiation (slope of Line AB in Figure 1)Page 2 of 10 WIR 2 is the growth rate in the WIAvE-us after initiation (slope of Line BD in Figure 1)tcyc is the length of the operating period (0.926 years at power)Equation 1 is the solution for the intersection of the two lines (AC and ED) and defines the time in the operating period when the change in the upper support wear index slope due to in-plane instability occurs. Point B in Figure 1 represents the calculated initiation time as determined by the model.The growth in the wear indices in the AVB upper supports before in-plane instability (WIR 1) and after in-plane instability (WIR 2) are calculated from the following:
... [WRAB-us]i (2)WIR2 E=1 AN=N r' AIRPOst WIR 2... AVB-[us]i (3)AIPr e adI~s where ....AB-US and rAVBus are the cumulative distribution functions (CDF) for the AVB wear rates derived from wear depth data for tubes without TTW and with TTW. The variable N 1 is the number of AVB upper-support locations in the tube before in-plane instability.
The parameter N 2 is the number of AVB upper-support locations with detected wear in the tube after 0.926 years at power.Analysis Input For Tube R92 C84 in 3E-088, the following input data are known from the Cycle 16 inspection results and used in the simulation to determine Line ED in Figure 1.1) Total number of AVB upper support locations having detected wear after 0.926 years at power is seven, N 2 = 7.2) Wear index due to AVB wear in upper supports after 0.926 years at power, WEOPUS = 82% TW (Figure 1 Point D).The following variables that are treated statistically and used to determine Line AC: 1) Number of AVB upper support locations before in-plane instability (N 1) is randomly picked from Poisson distribution in Figure 2 based on tubes with no TTW.2) AVB wear rates before and after in-plane instability are randomly selected from the distributions in Figure 3.AVB Wear Rates The AVB wear rates for the upper supports (B03 through B10) were determined by dividing the AVB wear depths by the 0.926 years at power. The technical basis for using the full operating interval of 0.926 years at power to establish the AVB wear rates was discussed in the response to RAI 2 with supporting data given in RAI 68. As shown in Figure 4, the AVB upper support Page 3 of 10 wear depths in tubes are not significantly dependent on whether in-plane instability had occurred or not. Final AVB wear depths for tubes with TTW are similar to the final wear depths for tubes without TTW including the upper extreme values. The average wear depth for tubes with TTW is 10.1% TW with a maximum depth of 37% TW. For tubes without TTW, the average depth is 8.9% TW and the maximum is 36% TW. This indicates that the wear rates at individual tube/AVB contact points before in-plane instability are not significantly elevated after TTW has initiated.
It is appropriate to use 0.926 years at power to develop AVB wear rates for conditions prior to in-plane instability (tubes without TTW) since it is reasonable to assume that AVB wear in these tubes began at the start of Cycle 16. Since the AVB depths in tubes with TTW include AVB locations that existed before in-stability, it is also reasonable to assume that these locations make up the upper tail for the distribution of wear rates shown in Figure 4. Given the depth distribution comparison shown in Figure 4, the interval 0.926 years at power was used to determine the CDF for AVB wear rates for conditions following in-plane instability.
The post-initiation curve was used to calculate the wear index rate WIR 2 since this will result in a steeper slope for Line BD and a longer initiation time to be calculated in the simulation.
Procedure to Calculate TTW Initiation Time For the example trial, the following calculations were performed for Tube R92 C84: 1.0 Determination of N 1 1.1 At the start of a trial, the number of AVBs is selected by a random pick from the Poisson distribution developed from the number of affected AVBs observed in tubes without TTW. This CDF is given in Figure 2. Both Unit 3 steam generators have similar distributions and these data were combined to obtain the mean parameter for the Poisson distribution.
1.2 For this trial for Tube R92 C84, a random pick from the CDF in Figure 2 gave four AVBs in the upper supports as having wear commencing at the start of Cycle 16.Therefore, N 1 = 4 which meets the criteria that 0 < N 1 < N 2.2.0 Determination of WIR, 2.1 The wear index growth rate before instability is calculated by summing the individual AVB wear rates from the upper supports using Eq. 2. The AVB wear rates are determined by N 1 random selections from the AVB wear rate distribution in Figure 3 (pre-initiation curve). For N, = 4, the growth in the wear index before tube instability (WIRj) is WIal 4 [Wi Pre WR E= [WAvBUS]i Page 4 of 10 Four random selections from the AVB wear rate CDF in Figure 3, pre-initiation curve gives, WIR 1 = 12.2 + 8.8 + 6.6 + 16.8 = 44.4% TW per years at power The equation for Line AC is WIAVB-US = 44.4 t.3.0 Determination of WIR 2 3.1 The wear index growth rate after instability is calculated by summing the individual AVB wear rates using Eq. 3. The AVB wear rates are determined by N 2 random selections from the AVB wear rate distribution in Figure 3 (post-initiation curve).3.2 Since N 2 = 7 for Tube R92 C84, the growth in the wear index after tube instability (WIR 2) is n7 DPost 1 WIR2 i=1 Ji Seven random selections from the AVB wear rate in Figure 3, post-initiation curve gives WIR 2 = 14.8 + 9.8 + 7.6 + 16.8 + 14.2 + 12.6 + 20.7 == 96.5 %TW per years at power 3.3 The intercept point (Figure 1 Point E) is calculated from the expression PointE ..AVB-us -WIR 2 tcYc = 82%TW -96.5 (0.926) = -7.36 %TW 3.4 Point E for this trial meets the criterion that the intercept is less than zero. This requirement ensures the slope for Line ED is always greater than or equal to the slope for Line AD (WIR 2 > WIRj). If Point E > 0, the AVB growth rates would be re-sampled and WIR 2 recalculated from Eq. 3 to satisfy this constraint.
The equation for Line ED is WIAVB-US = 96.5 t -7.36 Page 5 of 10 4.0 Calculation of Initiation Time From Eq. 1, the initiation time for this trial for Tube R92 C84 is tINIT 82-96.5(0.926)
-7.36 =0.141 years at power 44.4-96.5
-52.1 The above calculation is repeated 1000 times for 1000 trials per tube. The 1000 initiation times (tINIT) are ranked in ascending order and the median value (500th in ranking) is recorded.Page 6 of 10 Variable Initiation-Time Trial For Tube R92 C84 in 3E-088 140 ca 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Operation Time, t (Years at Power)Figure 1 -TTW Initiation-Time Calculation Example for One Trial Page 7 of 10 Unit 3 AVB Distribution for Tubes without TTW 1000 8 0 =Cumulative Distribution 800 700 600 C)500-0 400 300 200 100 00 0 1 2 3 4 5 6 7 8 9 10 11 12 Number of AVBs 1.0 0.9 0.8 U-0.7 0 CF 0.6 .2.0 0.4 0.5 0 0 0.4 >0.3 E 0.2 0.1 0.0 Figure 2 -Distribution of Affected AVBs in Unit 3 for Determining N, Page 8 of 10 Unit 3 AVB Wear Rates U-I.2 C U-C E..6Q°U E C., 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 5 10 15 20 25 30 AVB Wear Rate, %TW per Years at Power 35 40 Figure 3 -Log-Normal AVB Upper Support Wear Rate Distributions for Unit 3 Page 9 of 10 Unit 3 AVB Wear Depths -Upper Supports L-a 0 dU.a 0 E UJ 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 5 10 15 20 25 30 35 40 NDE Depth, (%TW)Figure 4 -Wear Depths for Tube/AVB Contacts at the Upper Supports after 0.926 Years at Power Page 10 of 10