L-2020-064, Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information: Difference between revisions

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{{Adams
{{Adams
| number = ML20098F341
| number = ML20100G832
| issue date = 04/07/2020
| issue date = 04/09/2020
| title = Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information
| title = Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information
| author name = Stamp B
| author name = Stamp B
Line 11: Line 11:
| contact person =  
| contact person =  
| case reference number = L-2020-064
| case reference number = L-2020-064
| document report number = AIIM-200310774-2Q-1(NP), Rev 1
| document type = Letter type:L, Response to Request for Additional Information (RAI)
| package number = ML20098F340
| page count = 6
| document type = Letter type:L, Report, Technical, Response to Request for Additional Information (RAI)
| page count = 75
| project =  
| project =  
| stage = Response to RAI
| stage = Response to RAI
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{{#Wiki_filter:April 7, 2020 L-2020-064 10 CFR 50.90 10 CFR 50.91 10 CFR 2.390 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington D C 20555-0001 RE:      Turkey Point Nuclear Plant, Unit 3 Docket No. 50-250 Renewed Facility Operating License DPR-31 Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information
{{#Wiki_filter:April 9, 2020 L-2020-064 10 CFR 50.90 10 CFR 50.91 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington DC 20555-0001 RE:      Turkey Point Nuclear Plant, Unit 3 Docket No. 50-250 Renewed Facility Operating License DPR-31 Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information


==References:==
==References:==
: 1. Florida Power & Light Company Letter L-2020-053, Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program, dated April 4, 2020
: 1. Florida Power & Light Company Letter L-2020-053, Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program," dated April 4, 2020,
[ML20095J926].
[M L20095J926].
: 2. Florida Power & Light Company Letter L-2020-063, License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information dated April 6, 2020 [ML20097D658].
: 2. Florida Power & Light Company Letter L-2020-064, License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information" dated April 7, 2020, [ML20098F341, ML20098F342J.
Per Reference 1, Florida Power & Light Company (FPL) requested an exigent amendment to Renewed Facility Operating License DPR-31 for Turkey Point Nuclear Plant Unit 3 pursuant to 10 CFR Part 50.90 and 10 CFR Part 50.91(a)(6).
: 3. NRG email "Turkey Point Unit 3 - Request for Additional Information Concerning Deferral of Steam Generator lnservice Inspections (EPID L-2020-LLA-0067)" dated April 9, 2020.
On April 4, 2020, the NRC Staff requested supplemental information to facilitate review of the requested amendment. Per Reference 2, FPL provided the response to the request for additional information. to this letter provides Revision 1 of the proprietary Intertek Report AIM-200310774-2Q-1 submitted by Reference 2. The proprietary report was revised to identify the proprietary information in the report. In addition, as a result of additional reviews, a clarification was made to a statement in Section 6.2 (page 51) of the Intertek Report. The original statement, revised by Revision 1 of the Intertek proprietary report, is also reflected in Section 3.4.3 of the License Amendment Request submitted per Reference 1.
Per Reference 1, Florida Power & Light Company (FPL) requested an exigent amendment to Renewed Facility Operating License DPR-31 for Turkey Point Nuclear Plant Unit 3 pursuant to 10 CFR Part 50.90 and 10 CFR Part 50.91 (a)(6).
The attachment to this letter provides the affected License Amendment Request Section 3.4.3 statement and the updated wording reflecting the clarification. The clarification does not affect the analysis or its conclusions. The information provided in Enclosure 1 to this letter contains information proprietary to Intertek; therefore, it is requested to be withheld from public disclosure in accordance with 10 CFR 2.390. to this letter provides the non-proprietary version of Revision 1 of the Intertek Report AIM-200310774-2Q-1. The supporting affidavit and application for withholding information contained in Intertek Report AIM-200310774-2Q-1 from public disclosure is provided in Enclosure 3 to this letter.
On April 4, 2020, the NRG Staff requested supplemental information to facilitate review of the requested amendment. Per Reference 2, FPL provided the response to the request for additional information.
The information provided by this letter supersedes the information provided by FPL letter L-2020-063, Reference 2 in its entirety.
On April 8, 2020, NRC requested additional information needed to facilitate review of the requested amendment (Reference 3). The attachment to this letter provides the response to the requested information.
The information provided in this letter does not alter the no significant hazards determination previously provided by the original application per FPL letter L-2020-053.
The information provided in this letter does not alter the no significant hazards determination previously provided by the original application per FPL letter L-2020-053.
Florida Power & Light Company 700 Universe Boulevard, Juno Beach, FL 33408
Should you have any questions regarding this submittal, please contact Mr. Robert Hess, Turkey Point Licensing Manager, at (305) 246-4112.
 
Turkey Point Nuclear Plant                                                                  L-2020-064 Docket No. 50-250                                                                            Page 2 of 2 Should you have any questions regarding this submittal, please contact Mr. Robert Hess, Turkey Point Licensing Manager, at (305) 246-4112.
I declare under penalty of perjury that the foregoing is true and correct.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on April 7, 2020.
Executed on April 9, 2020.
Sincerely, Brian Stamp Site Director Turkey Point Nuclear Plant Florida Power & Light Company Attachment
Sincerely,
 
    ;£:~~
==Enclosures:==
BrirulStamp Site Dlrector Turkey Pornt Nuclear Plant Florida Power & Light Company Florida Power & Light Company
: 1. lntertek Report (proprietary) AIM-200310774-20-1 (P), Revision 1, Operational Assessment for Deferring the TP3-31 Steam Generator Tube Examinations for Turkey Point Unit 3 to the TP3-32 Outage in October 2021, April 2020.
: 2. lntertek Report (non-proprietary) AIM-200310774-2Q-1 (NP), Revision 1, Operational Assessment for Deferring the TP3-31 Steam Generator Tube Examinations for Turkey Point Unit 3 to the TP3-32 Outage in October 2021, April 2020.
: 3. lntertek Affidavit for Enclosure to FPL letter L-2020-063 dated April 6, 2020.
cc: USNRC Regional Administrator, Region II USNRC Project Manager, Turkey Point Nuclear Plant USNRC Senior Resident Inspector, Turkey Point Nuclear Plant Ms. Cindy Becker, Florida Department of Health (without Enclosure 1)
 
Turkey Point Nuclear Plant                                                                    L-2020-064 Docket No. 50-250                                                                            Attachment Attachment to L-2020-064 CLARIFICATION ORIGINAL L-2020-053 Enclosure Page 13 of 19 Section 3.4.3 POTENTIAL DEGRADATION MECHANISMS:
(affected paragraph only):
The more limiting mechanisms are the first five in the above list. These mechanisms are existing in other A600TT plants. The last two in the list, axial ODSCC in freespans and PWSCC in small radius U-bends, have not occurred in operating plants. These mechanisms are not formally evaluated but considered to be bounded by axial ODSCC at TSPs.
CLARIFIED The clarification is noted in bold:
The more limiting mechanisms are the first five in the above list. These mechanisms are existing in other A600TT plants. The last two in the list are not considered controlling mechanisms. Axial ODSCC in freespans (without the presence of a ding) has not been observed. These mechanisms are not formally evaluated but considered to be bounded by axial ODSCC at TSPs.
 
Turkey Point Nuclear Plant                                    L-2020-064 Enclosure 2 Docket No. 50-250 Intertek Report (Non-Proprietary) AIM-200310774-2Q-1, (NP) Revision 1 Operational Assessment for Deferring the TP3-31 Steam Generator Tube Examinations for Turkey Point Unit 3 to the TP3-32 Outage in October 2021
 
Operational Assessment for Deferring the TP331 Steam Generator Tube Examinations for Turkey Point Unit 3 to the TP332 Outage in October 2021 FLORIDA POWER & LIGHT COMPANY Attn: Mr. Kester Thompson Florida Power & Light Company 15430 Endeavor Drive Jupiter, FL 33478 kester.thompson@fpl.com REPORT NO AIM2003107742Q1 (NP)
Controlled Document I2 Revision 1 NONPROPRIETARY PREPARED BY William K. Cullen Russell C. Cipolla Brian W. Woodman DATE 05 April 2020
 
List of Revisions Rev.            Date                              Revision Details                        Author 0      03 April 2020      Initial Issue                                          W. K. Cullen R. C. Cipolla B. W. Woodman 1      05 April 2020      Minor editorial changes with brackets added for        W. K. Cullen reference to nonproprietary version.                  R. C. Cipolla B. W. Woodman Issuing Office Intertek AIM 3510 Bassett Street Santa Clara, CA 95054 4087457000 W. K. Cullen            4129515001        william.k.cullen@intertek.com R. C. Cipolla            4086365322        russell.cipolla@intertek.com Disclaimer This report has been prepared for the titled project or named part thereof and should not be relied upon or used for any other project without an independent check being carried out as to its suitability and prior written authority of Intertek being obtained. Intertek accepts no responsibility or liability for the consequences of this document being used for a purpose other than the purposes for which it was commissioned. Any person using or relying on the document for such other purposes agrees and will by such use or reliance be taken to confirm his agreement to indemnify Intertek for all loss or damage resulting therefrom. Intertek accepts no responsibility or liability for this document to any party other than the person by whom it was commissioned.
AIM 2003107742Q1 (NP), Rev. 1                  NON-PROPRIETARY                                    Page 2


CERTIFICATE OF COMPLIANCE We, the undersigned, certify that the Intertek AIM Report AIM 2003107742Q1 (NP), Revision 1, titled Operational Assessment for Deferring the TP331 Steam Generator Tube Examinations for Turkey Point Unit 3 to the TP332 Outage in October 2021, which was procured under Florida Power & Light Company Purchase Order No. 02410017, meets the technical requirements of FPL's Steam Generator Integrity Management Program per the Industry Guidelines, and the quality requirements of the Intertek AIM Quality Assurance Manual, Revision 7.7. This report documents the results of both Phases 1 and 2 of the Florida Power & Light Purchase Order listed above. The findings of the Phase I preliminary study were provided verbally during the project.
Turkey Point Nuclear Plant                                      L-2020-069 Docket No. 50-250                                              Page 2 of 2 Attachment - Response to Request for Additional Information cc: USNRC Regional Administrator, Region II USNRC Project Manager, Turkey Point Nuclear Plant USNRC Senior Resident Inspector, Turkey Point Nuclear Plant Ms. Cindy Becker, Florida Department of Health
4/5/2020 Russell C. Cipolla                                        Date Project Manager 4/5/2020 Evelyn Ryan                                            Date Quality Assurance Manager AIM 2003107742Q1 (NP), Rev. 1              NON-PROPRIETARY                                Page 3


VERIFICATION RECORD SHEET Report No.: AIM 2003107742Q1 (NP)                    Rev.: 1              Date: 05 April 2020 Report
Turkey Point Nuclear Plant                                    L-2020-069 Docket No. 50-250                                            Attachment Attachment to L-2020-069 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION


==Title:==
Turkey Point Nuclear Plant                                                            L-2020-069 Docket No. 50-250                                                                      Attachment Page 1 of 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION CONCERNING DEFERRAL OF STEAM GENERATOR INSERVICE INSPECTION FLORIDA POWER & LIGHT COMPANY TURKEY POINT NUCLEAR GENERATING UNIT NO. 3 DOCKET NO. 50-250
Operational Assessment for Deferring the TP331 Steam Generator Tube Examinations for Turkey Point Unit 3 to TP332 Outage in October 2021 Originated By:
: 1. Enclosure 2 of the supplement (operational assessment or OA) dated April 7, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20098F341) describes the SG OA for the additional requested cycle before SG inspection. Page 25 of the OA outlines the probabilistic model used to evaluate potential mechanisms such as stress corrosion cracking. The OA states:
4/5/2020 Project Engineer                            Date Verified By:
A time-to-flaw-initiation (Weibull) function is applied. The physical processes of flaw initiation, flaw growth and simulated inspections (via use of a POD [probability of detection] function) are modeled for several past and future cycles. Benchmarking of results to the observed information obtained from past inspections provides assurance of the accuracy of predictions over the operating interval to the next inspection.
4/5/2020 Verifier                              Date Approved By:
and it is conservative assume[sic] to assume for the BOC [beginning of cycle] distribution of flaws following the last inspection that at least one SCC [stress corrosion cracking] indication had initiation sometime in the previous operating period and that the initiated indication(s) where not reported. As a general figure of merit, the size of the missed indications will be on the order of the no smaller than 5% POD value for the ECT [eddy current testing] technique used in the previous inspection. This assures a reasonable conservative starting population for the simulation.
4/5/2020 Project Manager                            Date QA Approved By:
For the cracking mechanisms analyzed in the OA, please clarify:
4/5/2020 Quality Assurance Manager                        Date AIM 2003107742Q1 (NP), Rev. 1                NON-PROPRIETARY                                  Page 4
: a. the details of how the missed indication size distribution is selected from the appropriate POD curve including any limits placed on the missed indication size; and FPL Response:
The distribution of sizes of missed indications following the most recent examination is not selected but is generated in the Monte Carlo simulation that replicates the inspection process. Figure 3-4 in the operational assessment shows the Monte Carlo simulation flowchart, where the application of the Weibull initiation, lognormal growth, and the POD models establishes the BOC indication sizes.


Executive Summary Florida Power and Light is planning to request a onecycle extension to the current inspection interval for the Turkey Point Unit 3 (PTN3) steam generators (SGs). This request will defer the TP331 SG tube examinations at endofcycle (EOC) 30 to EOC 31 in October 2021. The objective of this evaluation is to provide the technical justification for deferring the TP331 SG tube examination by one operating cycle.
Turkey Point Nuclear Plant                                                              L-2020-069 Docket No. 50-250                                                                      Attachment Page 2 of 3 For the most recent inspection where no corrosion degradation was observed, it is assumed that at least one crack initiates during the operating period prior to the inspection, and at least two crack initiations are present at the time of the inspection and are not reported during the inspection. This is achieved by adjusting the Weibull model to set the time for first initiation in the prior cycle. Cracks initiated in the prior cycle are allowed to grow using the EPRI default growth rate distribution. As another conservative measure, any cracks that are detected in the simulation are not removed from service but are included in the BOC of missed indications.
The evaluation is based on a revised Operational Assessment (OA) performed in accordance with EPRI Steam Generator Integrity Assessment Guidelines (IAGL). The revised OA supplements the current EOC 28 CM and OA for the March 2017 outage and evaluates the predicted condition of the SGs after three cycles of operation (Cycles 29, 30, and 31).
The BOC size distribution of indications from the analysis is checked to confirm that median depth of the simulated sizes exceeds the lower 5%
Prior examination at EOC 28 (March 2017) identified wear at antivibration bar locations, wear at tube support plate tube intersections, and wear at flow distribution baffle plates as the only existing degradation modes. There was no corrosion degradation observed at EOC 28 or in any prior examinations. The OA evaluation for PTN3 was reevaluated for the existing mechanisms including foreign objects known or postulated to be remaining in the SG secondary side using the same bounding deterministic EPRI IAGL methods. Also, potential mechanisms were evaluated assuming some could become active in the operating period prior to Cycle 28.
POD performance level. In addition, the 95th percentile of the BOC distribution is reviewed for reasonability against the POD curve. This assures the BOC simulated sizes will not be too small such that the analysis is not effective as a measure of performance and not overly adverse such that the analysis unduly predicts failure. This BOC distribution conservatively envelops any actual flaws that may exist under the condition that the mechanism is existing but not observed at the previous inspection.
The results of these analyses demonstrated that extending the inspection interval by one cycle is fully supported by the industry performance standards for tube integrity. The structural integrity performance criterion margin requirement of three times normal operating pressure (3xNOPD) on tube burst will be satisfied at EOC 31 for the existing and potential degradation. Also, the accidentinduced leakage performance criteria for the limiting accident condition will be satisfied for the cumulative leakage requirement for any one SG and for all three SGs for operating period to EOC 31.
: b. how the assumed initiated flaws were benchmarked to missed or detected cracks from plant operating experience.
It has been concluded that given the examination scope implemented at EOC 28, all structural and accident leakage performance criteria in NEI 9706 are predicted to be met through the end of Cycle 31 for the existing and potential degradation mechanisms.
FPL Response:
AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                  Page 5
For the mechanisms judged most challenging to the establishment of satisfaction of the performance criteria at EOC 31, the upper 95th percentile of developed non-detected depths are consistent with observed plant performance from historical look back reviews of indications observed in the outage during which indications were detected. These depths are judged to be conservative compared to the mean probe performance. The parameters for the Weibull initiation function used in the OA were developed from past operating experience of plants that have a history of cracking and form the basis on how each mechanism will evolve over time following first initiation.
 
: 2. In Section 6.6 of the OA, which discusses axial outside diameter stress corrosion cracking at tube support plates, there is a discussion regarding how the analysis conservatively adjusted the POD curve. The discussion states:
Contents Section                                                                                                                      Page Executive Summary ...................................................................................... 5 List of Tables and Figures .............................................................................. 8 1 l Introduction ............................................................................................... 9 2 l Examination Scope and Results ..................................................................................... 10 2.1  Background ............................ .10 2.2  Examination Scope at Last Inspection...................................................................... 10 2.3  Summary of Inspection Results ............................................................................... 10 2.4  Tube Plugging .......................................................................................................... 11 3 l Operational Assessment Methodology.................................................................... 21 3.1 Tube Integrity Requirements ................................................................................... 21 3.2 Performance Acceptance Standards ........................................................................ 21 3.3 Structural Models .................................................................................................... 22 3.3.1 Burst Pressure Relationships for Wear Degradation ............................................ 22 3.3.2 Burst Pressure Relationships for Axial Corrosion Degradation ............................ 23 3.3.3 Burst Pressure Relationships for Circumferential Corrosion Degradation ........... 23 3.4 Leakage Models .................................................................................... 23 3.5 Inspection Interval Analysis .................................................................. 24 3.5.1 Deterministic Analysis ........................................................................................... 24 3.5.2 Probabilistic MultiCycle Analysis ......................................................................... 24 3.6 Measurement Uncertainties ................................................................. 26 4 l Input Variables and Distributions ................................................................ 32 4.1 Tubing Properties .................................................................................................... 32 4.2 Operating Conditions .............................................................................................. 32 4.3 Probability of Detection .......................................................................................... 33 AIM 2003107742Q1 (NP), Rev. 1                        NON-PROPRIETARY                                                      Page 6
[d]ue to the manner in which the models were constructed, the POD curve has little impact on the probability of burst, only the number of indications detected at EOC-31 [end of cycle 31].
 
Section (Contd)                                                                                                            Page 4.4 Degradation Growth Rates ..................................................................................... 34 4.4.1 Wear Degradation................................................................................................. 34 4.4.2 Corrosion Degradation .......................................................................................... 35 4.5 Initiation Function ................................................................................................... 36 5 l Operational Assessment for Existing Mechanisms ....................................... 40 5.1 Assessment Method ................................................................................................ 40 5.2 AntiVibration Bar Wear .......................................................................................... 41 5.3 Wear at Tube Support Plates ................................................................................... 41 5.4 Wear at Flow Distribution Baffle Plates ................................................................... 42 5.5 Foreign Object Evaluation ....................................................................................... 42 5.6 Summary of Operational Assessment Results for Existing Mechanism .................... 43 6 l Operational Assessment for Potential Mechanism ...................................... 50 6.1 Assessment Overview ............................................................................................. 50 6.2 Potential Degradation Mechanisms......................................................................... 50 6.3 Circumferential ODSCC at TTS Expansion Expansions .............................................. 51 6.4 Axial ODSCC at TTS Expansion Transitions ............................................................... 53 6.5 PWSCC at TTS Expansions Transitions...................................................................... 54 6.5.1 Wear Degradation................................................................................................. 54 6.5.2 Corrosion Degradation .......................................................................................... 54 6.6 Axial ODSCC at TSP Intersections ............................................................................. 55 6.6.1 Acute Initiation Model .......................................................................................... 56 6.6.2 Low Slope Initiation Model ................................................................................... 57 6.7 Axial ODSCC at Tube Dings and Dents ..................................................................... 57 6.7.1 Axial ODSCC at Hot/Cold Leg Dings 5 Volts ........................................................ 58 6.7.2 Axial ODSCC at Hot Leg Dings >5 Volts ................................................................ 58 6.7.3 Axial ODSCC at Cold Leg Dents >5 Volts ............................................................... 60 6.8 Other Mechanisms .................................................................................................. 60 6.9 Summary of Operational Assessment Results for Potential Mechanisms ................ 60 7 l Summary and Conclusions ....................................................................... 65 8 l References ............................................................................................. 66 AIM 2003107742Q1 (NP), Rev. 1                      NON-PROPRIETARY                                                      Page 7
 
List of Tables and Figures Title                                                                                                                          Page Table 21    Long Range Inspection Plan - Turkey Point Unit 3 .............................................................. 12 Table 22    Turkey Point Unit 3  Basis for Steam Generator Tube Examinations at EOC 26 ................. 14 Table 23    Turkey Point Unit 3  Basis for Steam Generator Tube Examinations at EOC 28 ................. 16 Table 24    Summary of Detected Wear Indications and Anomalies for PTN3 - March 2017 ............. 19 Table 31    Relationships for Measurement Uncertainty for PTN3 - March 2017 Outage .................. 27 Table 61    Summary of OA Results for Limiting Potential Mechanism ................................................. 62 Figure 21  Schematic Illustration of Turkey Point Steam Generators ................................................... 20 Figure 31  Flaw Models for Wear Degradation ..................................................................................... 28 Figure 32  Flaw Models for SCC Degradations ...................................................................................... 29 Figure 33  Aspects of Monte Carlo Simulation to calculate Probability of Tube Burst ......................... 30 Figure 34  Probabilistic Simulation to Determine WorstCase Degraded Tube - Full Bundle Analysis 31 Figure 41  Comparison of Probability of Detection Functions for Axial ODSCC ................................... 37 Figure 42  Default Crack Growth Rates for A600TT Tubing at 611oF .................................................... 38 Figure 43  Comparison of Various CGR Functions from Operating Data .............................................. 39 Figure 51  Comparison of Wear Rates at AVB Tube Contacts for PTN3 .............................................. 45 Figure 52  Operational Assessment of AntiVibration Bar Wear for PTN3 (March 2017) ................... 46 Figure 53  Operational Assessment of Tube Support Plate Wear for PTN3 (March 2017) ................. 47 Figure 54  Operational Assessment of Tube Support Plate Edge Wear for PTN3 (March 2017) ........ 48 Figure 55  Operational Assessment of Flow Distribution Baffle Wear for PTN3 (March 2017) .......... 49 Figure 61  Length Distributions of All Axial SCC Flaws for the A600TT Fleet ........................................ 63 Figure 62  Axial ODSCC Bobbin Coil POD Curves................................................................................... 64 AIM 2003107742Q1 (NP), Rev. 1                  NON-PROPRIETARY                                                              Page 8
 
1 l Introduction Florida Power and Light is planning to request a onecycle extension to the current inspection interval for the Turkey Point Unit 3 (PTN3) steam generators (SGs). This request will defer the TP331 SG tube examinations at endofcycle (EOC) 30 to EOC 31 in October 2021. The objective of this assessment is to provide the technical justification for deferring the TP331 SG tube examination by one operating cycle and maintaining the requirements in NEI 9706 [1]. The revised OA is performed in accordance with EPRI Steam Generator Integrity Assessment Guidelines (IAGL) described in [2]. The revised OA supplements the current EOC 28 OA for the March 2017 outage [3] and evaluates the predicted condition of the SGs after three cycles of operation (Cycles 29, 30, and 31).
Prior examination at EOC 28 (March 2017) identified wear at antivibration bar (AVB) locations, wear at tube support plate (TSP) tube intersections, and wear at flow distribution baffle plates (FBP) as the only existing degradation modes. There was no corrosion degradation observed at EOC 28 or in any prior examinations. The OA evaluation for PTN3 was reevaluated for the existing mechanisms including foreign objects known or postulated to be remaining in the SG secondary side using the same bounding deterministic IAGL methods. Also, potential mechanisms were evaluated assuming they could become active in the operating period prior to Cycle 28 and may not have been detected, considering the examination scopes from the EOC 26 and EOC 28 tube examinations.
The results of these analyses are presented in Section 5 for the existing degradation mechanisms; Section 6 presents the OA results for the potential mechanisms, for the extended operating period to EOC 31.
AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                  Page 9
 
2 l Current State of Turkey Point Unit 3 Tubes
 
===2.1 Background===
Turkey Point Unit 3 has three Westinghouse Model 44F replacement steam generators that were installed in 1982. Figure 21 is a schematic illustration of the SGs at PTN. The last inspection in March 2017 was the 17th scheduled inservice examination of the replacement steam generators, which constitutes completion of 21 plant operating cycles since replacement.
The long range inspection planning for PTN3 is shown in Table 21. PTN3 has operated for approximately 30 EFPYs without any significant tube integrity issues, with 2cycle inspection intervals successfully implemented in March 2006 following Cycle 20. Similar successful operating experience has been observed for PTN4.
The examination and evaluation of PTN3 steam generators follow the preoutage degradation assessment (DA) plan [4]. Tube examinations are based on industryqualified inspection techniques and tube integrity assessment are performed in accordance with EPRI IAGL [2]. It has been established that the limiting criterion for tube structural integrity for Turkey Point Plants is maintaining the margin of 3.0 against burst under normal steady state full power operation primarytosecondary pressure differential (3xNOPD). There has not been any reported primarytosecondary leakage in any SG during the Cycle 30 operating period [5].
2.2 Examination Scope at Last Inspections As documented in the DA, the inspection plan and scope of examinations are based on existing and potential degradation mechanisms as well as industry guidance and operating experience. The examination scopes and bases for the exams in the prior two examinations at EOC 26 and EOC 28 are given in Table 22 and 23. These tables provide the ECT probes that were used, the scope of the exams including the sampling plan and the expansion of these sample inspections, if required, and the degradation mechanisms of interest, both existing and potential. At these past outages, there were no issues that required expansion of the inspection scope beyond the initial scheduled examinations.
2.3      Summary of Inspection Results Consistent with prior inspections, the EOC 28 examination in March 2017 for PTN3 indicated that the following tube degradation mechanisms were present:
Wear at antivibration bar (AVB) tube contacts Wear at tube support plate (TSP) tube contacts Wear at flow baffle plate (FBP) tube contacts Wear due to foreign objects at TSP edges AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                  Page 10
 
There was no corrosionrelated degradation detected within the defined tubing pressure boundary. This included the 100% sample of all tubes with the +PointTM probe that have been identified as high residual stress (signature and 2sigma) tubes within the tubesheet region, and a 25% sample of high residual stress tubes examined at the FBP and TSP locations on the hotleg and top TSP on the coldleg.
A summary of the inspection findings for EOC 28 is given in Table 24 [3]. The results are summarized by SG and category (location). Most tube wear is associated with contact points with AVBs. Both the total count and the count for the newly reported indications are given. Wear at TSPs and FBPs are much less in numbers.
2.4      Tube Plugging At EOC 28, six tubes were removed from service by plugging: 2 in S/G 3A, 3 in S/G 3B, and 1 in S/G 3C. A summary of the six tubes is given below [3].
Tube Plugging Summary S/G      Tube      Location        Size              Cause                  Repair 2519      05C 0.57    43%TW          TSP Edge Wear              Plugged 3A 3747      AV3 +0.21    35%TW            AVB Wear                  Plugged 746      02C +0.74    12%TW        TSP Edge Wear w/PLP      Plugged/Stabilized 3B      2471      04H 0.58    23%TW          TSP Edge Wear              Plugged 4358        05H                          Restriction              Plugged 3C      1244      03H 0.69    15%TW        TSP Edge Wear w/PLP      Plugged/Stabilized There was only one tube exceeding the Technical Specification (TS) repair limit of 40% TW and required mandatory removal. The rest of the tubes were preventively plugged (not required by TS). Candidates for preventive plugging were selected based on a combination of observed wear rates, detected depths, tube wear at multiple locations, and wear associated with possible loose parts (PLPs). The primary objective of preventive plugging was a proactive measure to reduce the chance that the CM limits would be challenged at the next scheduled inspection.
AIM 2003107742Q1 (NP), Rev. 1                  NON-PROPRIETARY                                    Page 11
 
Table 21  Long Range Inspection Plan - Turkey Point Unit 3 Based on Technical Specification Section 6.8.4.j.d.2 (Completing Inspections Prior to Period End Point)
Guideline Interval        1st ISI                                  1st ISI Period (120 Months)                                                          2nd ISI Period (96 Months)
Cycle #                  CY08    CY09      CY10      CY11        CY12      CY13    CY14    CY15  CY16                  CY16    CY17  CY18      CY19    CY20      CY21      CY22 RFO #                    RFO 09    RFO 10      RFO 11      RFO 12        RFO13      RFO14    RFO15    RFO16                          RFO17    RFO18  RFO19      RFO20    RFO21        RFO22 RFO Outage Dates        Oct83    Mar85      Mar87      Feb90      Oct92      Apr94  Sep95    Mar97                        Sep98    Feb00  Sep01    Mar03    Sep04      Mar06 Cycle EFPH                11950      9065      10983      11459        10859      10980    10910    11603  11740                    419    11442  12911      11463    12725      10062    11060 EFPH Cumulative            11950    21015      31998      43457        54316      65296    76206    87809  99549                  99968    111410  124321    135784    148509      158571    169631 Cycle EFPY                  1.36      1.03        1.25        1.31        1.24        1.25    1.25      1.32    1.34                  0.05      1.31    1.47      1.31      1.45        1.15      1.26 EFPY Cumulative            1.36      2.40        3.65        4.96        6.20        7.45    8.70    10.02  11.36                  11.41    12.72  14.19      15.50    16.95        18.10    19.36 Cycle EFPM                16.37      12.42      15.05      15.70        14.88      15.04    14.95    15.89  16.08                  0.57    15.67  17.69      15.70    17.43        13.78    15.15 Period EFPM Cumulative    16.37    12.42      27.46      43.16        58.04      73.08    88.02    103.92  120.00                  0.57    16.25  33.93      49.64    67.07      80.85      96.00 EFPM Total Since SGRP      16.37      28.79      43.83      59.53        74.41      89.45    104.39  120.29  136.37                  136.94  152.62  170.30    186.01    203.44      217.22    232.37 Plug Visual Inspection      N/A        N/A        N/A        100%          100%      100%      100%    100%                            100%    100%    100%      100%      100%          SKIP ECT Bobbin                  10%        10%        10%        100%          100%      100%      100%    100%                            100%      50%    100%      100%      100%          SKIP H/L TTS (See Note 3)        N/A        N/A        N/A        N/A          N/A      Sample  Sample    Sample                        Sample    100%    50%      100%      100%          SKIP C/L TTS RPC (See Note 3)    N/A        N/A        N/A        N/A          N/A        N/A      N/A      N/A                            N/A      N/A    N/A        N/A      N/A          SKIP Dings & Spec Int. RPC      N/A        N/A        N/A        N/A          N/A      Sample  Sample    Sample                        Sample      20%    30%        50%      50%          SKIP Row 1 & 2 Ubend RPC        N/A        N/A        N/A        N/A          N/A        N/A      N/A      N/A                            N/A      20%    50%        50%      50%          SKIP Guideline Interval                          3rd ISI Period (72 EFPM)                                              4th ISI Period (72 EFPM)                                      5th ISI Period (72 EFPM)
Cycle #                  CY22    CY23      CY24      CY25        CY26      CY27              CY27  CY28      CY29      CY30    CY31              CY31    CY32      CY33      CY34      CY35 RFO #                    RFO23      RFO24      RFO25      RFO26        RFO27                        RFO28  RFO29        RFO30      RFO31                      RFO32    RFO33 RFO34 RFO35 RFO Outage Dates        Sep07    Mar09      Sep10      Feb12      Mar14                        Oct15  Mar17      Sep18    Mar20                      Oct21    Mar23      Oct24    Mar26 Cycle EFPH                  675      12139      11958      10633        11412      5740              6688  11121        12552      12066    10520              2152      12432      12768    12500      12708 EFPH Cumulative          170306    182445      194403      205036      216448    222188              228876  239997      252549    264228    274748            276900    289332      302100    314600    327308 Cycle EFPY                  0.08      1.39        1.37        1.21        1.30        0.66              0.76    1.27        1.43      1.38      1.20              0.25      1.42        1.46      1.43      1.45 EFPY Cumulative            19.44      20.83      22.19      23.41        24.71      25.36              26.13  27.40        28.83    30.16    31.36              31.61    33.03        34.49    35.91      37.36 Cycle EFPM                  0.92      16.63      16.38      14.57        15.63      7.86              9.16  15.23        17.19    16.53    14.41              2.95    17.03        17.49    17.12      17.41 Period EFPM Cumulative      0.92    17.55      33.93      48.50        64.13      72.00              9.16  24.40      41.59      57.59    72.00              2.95    19.98      37.47      54.59      72.00 EFPM Total Since SGRP    233.30    249.92    266.31      280.87        296.50    304.37            313.53  328.76      345.96    361.96  376.37            379.31    396.34      413.84    430.96    448.37 Plug Visual Inspection    100%        SKIP      100%        SKIP        100%                          SKIP  100%          SKIP      100%                        SKIP    100%          SKIP    100%
ECT Bobbin                100%        SKIP      100%        SKIP        100%                          SKIP  100%          SKIP      100%                        SKIP    100%          SKIP    100%
H/L TTS (See Note 3)      100%        SKIP      50%        SKIP          50%                          SKIP    50%          SKIP      50%                        SKIP      50%          SKIP      50%
C/L TTS RPC (See Note 3) Periphery    SKIP    Periphery      SKIP      Periphery                        SKIP Periphery      SKIP  Periphery                      SKIP  Periphery      SKIP  Periphery Dings & Spec Int. RPC      50%        SKIP      50%        SKIP          50%                          SKIP    50%          SKIP      50%                        SKIP      50%          SKIP      50%
Row 1 & 2 Ubend RPC        50%        SKIP      50%        SKIP          50%                          SKIP    50%          SKIP      50%                        SKIP      50%          SKIP      50%
AIM 2003107742Q1 (NP), Rev. 1                                                                  NON-PROPRIETARY                                                                                        Page 12
 
Table 21  Long Range Inspection Plan - TURKEY POINT UNIT 3 (contd)
Based on Technical Specification Section 6.8.4.j.d.2 (Completing Inspections Prior to Period End Point)
Guideline Interval                                            6th ISI Period (72 EFPM)
Cycle #                                      CY35        CY36          CY37        CY38      CY39 RFO #                                      RFO36        RFO37        RFO38      RFO39 RFO Outage Dates                            Oct27        Mar29        Oct30      Mar32      Jul32 End of PEO            End of PEO End of PEO 19 Jul 2032 Cycle EFPH                                    205          12500          12500      12500        2200 EFPH Cumulative                            327513        340013        352513      365013      367213                          ESTIMATED Cycle EFPY                                    0.02          1.43          1.43        1.43        0.25 EFPY Cumulative                              37.39        38.81          40.24        41.67        41.92 Cycle EFPM                                    0.28        17.12          17.12        17.12        3.01 Period EFPM Cumulative                        0.28        17.40          34.53        51.65      54.66 EFPM Total Since SGRP                      448.65        465.77        482.89      500.02      503.03 Plug Visual Inspection                        SKIP        100%            SKIP        100%
ECT Bobbin                                    SKIP        100%            SKIP        100%
H/L TTS (See Note 3)                          SKIP          50%            SKIP        50%
C/L TTS RPC (See Note 3)                      SKIP      Periphery        SKIP      Periphery Dings & Spec Int. RPC                        SKIP          50%            SKIP        50%
Row 1 & 2 Ubend RPC                          SKIP          50%            SKIP        50%
Notes:
: 1)  These Periodicity Tables are based on TSTF510 and Approved PTN License Amendments 255 and 251, dated Nov. 6, 2012.
: 2)  Updated using Fleet Approved Oper Schedule_2019 FINAL (FPL Rev 3, 6419)
: 3)  PTN3 EPU Conditions started with Cycle 26 Operation AIM 2003107742Q1 (NP), Rev. 1                                                            NON-PROPRIETARY                                              Page 13
 
Table 2 Turkey Point Unit 3 - Basis for Tube Examinations at EOC 26 Required or                                Degradation Technique                                            Examination Sample                                                                    Basis              Mechanism Supplemental
[Note 9, 10]
100% full length in rows 3 and higher. Row 1 & 2 examinations will be limited to the hot          Required          Degradation                Wear/
leg and cold leg straight sections. [Note 7]                                                                        Assessment                ODSCC Bobbin Screening of 100% of dings/dents < 5 volts in freespan straight sections.                        Required          Degradation Assessment                ODSCC 50% of the hot leg tubesheet to the extent of TTS +3.00 to TEH [Notes 1, 2 , 3, & 4]              Required      ENG CSI2.2, Rev.42,    Foreign Object Wear Checklist item 1.D, and the Degradation Assessment.      PWSCC/ODSCC All Hot Leg and Cold Leg Periphery Expansion Transitions  +3/2 from top of tubesheet.        Required      ENG CSI2.2, Rev.42,    Foreign Object Wear Periphery Tubes are defined as the two outermost peripheral tubes exposed to the                            Checklist item 1.D., and annulus, and all open row 1 and 2 tubes in columns 192.                                                          the Degradation Assessment.
Tight radius ubends - 50% of Rows 1 & 2 [Notes 1 & 2]                                            Required          Degradation                PWSCC/
Assessment                ODSCC 50% of hot leg freespan dings/dents > 5 volts between TSH and 06H + 1.00 (not inspected          Required          Degradation                PWSCC/
        +PointTM        in prior inspection) [Notes 1 & 2]                                                                                  Assessment                ODSCC 50% of dings/dents at Ubends (not inspected in prior inspection)                                Required          Degradation                PWSCC/
Assessment                ODSCC 50% of dings/dents at HL tube structures (not inspected in prior inspection)                      Required          Degradation                PWSCC/
Assessment                ODSCC All tubes adjacent to previously reported foreign objects that are actively tracked in App. D    Required      ENG CSI2.2, Rev.42,    Foreign Object Wear TM are included in this plan for examination using the rotating +Point probe.                        [Note 8]    Checklist item 1.M., and the Degradation Assessment Diagnostic rotating probe examinations (Special Interest, SI) will be completed as required      Required          Degradation              Degradation based on the results of the bobbin coil.                                                                            Assessment Installed tube plugs [Notes 5]                                                                    Required  EPRI Exam Guidelines Rev.          Plug 7 Section 6.9 &          Degradation Visual                                                                                                                            SGMPIG1201 Channel head bowl scan (both steam generators) [Note 6]                                        Supplemental    Westinghouse OE        Cladding Degradation (NSAL121)
Existing degradation mechanisms are wear at antivibration bars, tube supports and the flow distribution baffles.
AIM 2003107742Q1 (NP), Rev. 1                                                              NON-PROPRIETARY                                                                          Page 14
 
Table 22 (Contd)  Turkey Point Unit 3  Basis for Tube Examinations at EOC 26 NOTES:
Note 1: Data Management to select locations not inspected during the preceding tube examination (TP325).
Note 2: Inspection expansion, if required, will be in accordance with the requirements of the Technical Specifications and Section 3.7 of the EPRI Steam Generator Examination Guidelines Rev 7, and for foreign objects, the EPRI Integrity Assessment Guidelines, Chapter 10 Note 3: This includes minimum 50% sample of BLG & OXP indications within the Tubesheet Note 4: Per the TS, the required inspection depth for the 50% H/L Tubesheet examination is TSH18.11. However, for ease of acquisition, the test extent of TSH
                    +3.00 to TEH will be programmed.
Note 5: The visual tube plug inspection planned for this outage meets the requirements of EPRI Interim Guidance SGMPIG1201, as evaluated in AR 01907053. The recommended visual tube plug inspection interval is each time primary side is opened or at least once every two refueling outages. All tube plugs in both the hot leg and cold leg plenums will be visually inspected to ensure correct location, general condition, and absence of leakage, water droplets and/or boron deposition.
Note 6: Visual inspection of the primary channel head will be performed and reviewed prior to eddy current testing to determine asfound conditions. The entire interior surface should be viewed to the extent possible, with additional attention for (1) visual inspection of the primary channel head surface condition, including the tubesheet to divider plate fillet weld, and the divider plate to channel head fillet weld to address OE 305083 from Wolf Creek Unit 1; and (2) the areas of the bottom of the bowl for foreign material and abnormal conditions.
With the channel head bowl in a dry condition (during plant shutdown), a visual scan of the low lying areas of both the hot and cold legs of the inside surface will be performed. Key areas of inspection include the channel head cladding, and the divider platetochannel head weld. The inspections will look for evidence of gross defects (such as indications in welds, missing weld filler material, a breach in the weld metal, unusual discoloration of the weld metal, dings or gouges, etc.). The inspection can be limited to the approximate area included within a 914 mm (36 inch) radius centered on the very bottom of the channel head bowl. The results of the inspection will be documented. If any unusual conditions are observed, the relevant actions described in NSAL121 will be followed.
Note 7: Per ENG CSI2.2, Rev.42, Checklist item 1.C, all inservice tubes that are adjacent to one of the following plugged tubes shall be inspected for potential wear due to contact from the plugged tube: SG 3A R33C44, SG 3B R42C43, SG 3B R42C45, SG 3C R35C47, SG3C R38C54, SG3C R40C38. Report any evidence of wear on neighboring tubes to Westinghouse for further evaluation. CR20076264 (AR# 00438574)
TM Note 8: Ensure that tubes adjacent to R6 C45 and R7 C45 in SG 3B are examination with the +Point          rotating probe to monitor for presence of a foreign object or associated wear at the 02C support elevation. (AR# 01710324)
Note 9: For Turkey Point Units 3 and 4, monitoring for tube slippage as part of the steam generator tube inspection program (at each scheduled inspection required by the Steam Generator Program).
Note 10: For Turkey Point Units 3 and 4, ensure that tubes previously reported with AOB or COB (AR# 01831425) are reexamined with the rotating +PointTM.
AIM 2003107742Q1 (NP), Rev. 1                                                  NON-PROPRIETARY                                                                                  Page 15
 
Table 23  Turkey Point Unit 3  Basis for Tube Examinations at EOC 28 Expansion Plan [Note 3]                Required or Basis          Degradation Technique                  Examination Sample                                                                    Supplemental Affected S/G            Unaffected S/Gs                                [Note 1]        Mechanism
[Note 2]
100% full length in rows 3 and higher. Row                                                                            Required to satisfy TS Wear/
Bobbin        1 & 2 examinations will be limited to the                N/A                        N/A            Required          SR 4.4.5.1 and TS ODSCC hot leg and cold leg straight sections.                                                                                      6.8.4.l Tight radius Ubends - 50% of Rows 1 & 2                                  All tight radius U                            Degradation          PWSCC/
Remaining 50%.                                        Required
[Note 1]                                                                  bends in Rows 1 & 2.                            Assessment          ODSCC Remaining 50% of H/L 50% of hot leg freespan dings/dents > 5                                  100% of H/L and at AND at least 50% of C/L                                                    Degradation volts between TSH and 06H + 1.00                                        least 30% of C/L.          Required                                  ODSCC freespan dings/dents.                                                        Assessment
[Note 1]                                                                  [Notes 9 & 10]
[Note 9]
Remaining 50% of 50% of dings/dents at Ubends > 5 volts                                  All dings/dents at U                          Degradation dings/dents at Ubends.                                Required                                  ODSCC
[Note 1]                                                                  bends.                                          Assessment
[Note 9]
Remaining 50% of H/L 100% of H/L and at 50% of dings/dents at H/L tube structures    AND at least 50% of C/L                                                    Degradation least 30% of C/L.          Required                                  ODSCC
[Notes 1]                                    dings/dents at tube                                                          Assessment
        +Point                                                                                  [Notes 9 & 10]
structures. [Note 9]
100% of the hot leg tubesheet to the extent of TSH +3.00 to TEH for the signature 2                                                                                Degradation          PWSCC/
tubes                                                      N/A                        N/A          Supplemental Assessment          ODSCC
[Note 5]
25% of signature 2 tubes at TSP & FBP      Remaining 75% of tubes. Remaining 75% of Degradation          PWSCC/
intersections (all H/L and top TSP on C/L      Expand to all C/L          tubes. Expand to all    Supplemental Assessment          ODSCC side).                                        intersections.              C/L intersections.
Diagnostic rotating probe examinations        N/A (performed as (Special Interest, SI) will be completed as  required to bound                                                          Degradation N/A            Required                                Degradation required based on the results of the bobbin  signals of interest such as                                                  Assessment and/or array coils.                          PLP)
Existing degradation mechanisms are wear at antivibration bars, tube supports, and the flow distribution baffles. H/L = Hot Leg; C/L = Cold Leg AIM 2003107742Q1 (NP), Rev. 1                                                      NON-PROPRIETARY                                                                            Page 16
 
Table 22 (Contd)  Turkey Point Unit 3  Basis for Tube Examinations at EOC 28 Expansion Plan [Note 3]                  Required or Basis        Degradation Technique                  Examination Sample                                                                  Supplemental Affected S/G          Unaffected S/Gs                                    [Note 1]      Mechanism
[Note 2]
Remaining 50% of H/L                                                          ENG CSI2.2,    Foreign Object 50% of the hot leg tubesheet to the extent                            100% of H/L and at                                                        Wear from TSH+3 to TEH AND                                                      Checklist Item 1.D, of 01H to TEH                                                        least 30% of C/L.              Required at least 50% of C/L from                                                and the Degradation      PWSCC/
[Notes 1, 4, & 5]                                                    [Notes 9 & 10]
TSC+3 to TEC. [Note 9]                                                        Assessment          ODSCC ENG CSI2.2,      Loose Part All Hot Leg and Cold Leg Periphery Checklist Item 1.D., Detection and Expansion Transitions  +3/2 from top of            N/A                    N/A                  Required and the Degradation  Foreign Object tubesheet. [Note 6]
Assessment          Wear Array All tubes adjacent to PLP and LPM Degradation    Foreign Object indications reported during the preceding              N/A                    N/A                Supplemental Assessment          Wear
                      +Point tube examinations.
All tubes (tubes surrounding actively                                                                                Required by      Loose Part tracked foreign objects and tubes adjacent                                                                            Examination Scope    Detection and to those tubes) affected by previously                  N/A                    N/A                  Required (FPENDE16001,    Foreign Object reported foreign objects that are actively latest revision)      Wear tracked in Appendix D.
EPRI Exam Guidelines Rev. 7 Section 6.9      Plug Installed tube plugs [Note 7]                          N/A                    N/A                  Required                  and          Degradation Visual                                                                                                                                SGMPIG1201 Channel head bowl scan                                                                                          Westinghouse OE        Cladding N/A                    N/A                Supplemental (all steam generators) [Note 8]                                                                                            (NSAL121)      Degradation Existing degradation mechanisms are wear at antivibration bars, tube supports, and the flow distribution baffles. H/L = Hot Leg; C/L = Cold Leg AIM 2003107742Q1 (NP), Rev. 1                                                    NON-PROPRIETARY                                                                              Page 17
 
Table 23 (Contd)  Turkey Point Unit 3  Basis for Tube Examinations at EOC 28 NOTES:
(1)  Data Management to select locations not inspected during the preceding tube examination.
(2)  Required examinations are those required by Technical Specifications and industry guidelines/operating experience. Supplemental examinations are required by this Degradation Assessment.
(3)  Inspection expansion, if required, will be in accordance with the requirements of the Technical Specifications and Section 3.8 of the EPRI Steam Generator Examination Guidelines Rev 7, and for foreign objects, Chapter 10 of the EPRI Integrity Assessment Guidelines Rev 3. N/A means not applicable as these inspections already cover the entire anticipated scope.
(4)  This includes minimum 50% sample of BLG and OXP indications in the hot leg within the Tubesheet.
(5)  Per the TS, the required inspection depth for the 50% H/L Tubesheet examination is TSH18.11. However, for ease of acquisition, the test extent of TSH +3.00 to TEH will be programmed.
(6)  Periphery Tubes are defined as the three outermost peripheral tubes exposed to the downcomer annulus, and all open row 1, 2 and 3 tubes in columns 192. Since some of the hot leg periphery tubes are sampled in the TTS exam, the extent of examination from TTS+3 to TTS2 applies to all cold leg periphery tubes and those hot leg periphery tubes not sampled in the TTS exam. Examinations are programmed from 01H to TEH for the hot leg and from 01C to TEC for the cold leg to cover the expansion transition region.
(7)  The visual tube plug inspection planned for this outage meets the requirements of EPRI Interim Guidance SGMPIG1201, as evaluated in AR 01907053 and 01921577. The recommended visual tube plug inspection interval is each time primary side is opened or at least once every two refueling outages. All tube plugs in both the hot leg and cold leg plenums will be visually inspected to ensure correct location, general condition, and absence of leakage, water droplets and/or boron deposition.
(8)  Visual inspection of the primary channel head will be performed and reviewed prior to eddy current testing to determine asfound conditions. The entire interior surface should be viewed to the extent possible, with additional attention for (1) visual inspection of the primary channel head surface condition, including the tubesheet to divider plate fillet weld, and the divider plate to channel head fillet weld to address OE 305083 from Wolf Creek Unit 1; and (2) the areas of the bottom of the bowl for foreign material and abnormal conditions.
With the channel head bowl in a dry condition (during plant shutdown), a visual scan of the low lying areas of both the hot and cold legs of the inside surface will be performed. Key areas of inspection include the channel head cladding, tubesheettodivider plate weld, and the divider platetochannel head weld. The inspections will look for evidence of gross defects (such as indications in welds, missing weld filler material, a breach in the weld metal, unusual discoloration of the weld metal, dings or gouges, etc.). The inspection should cover as much of the interior surface as possible. In addition, the inspection should check for foreign material and/or abnormal conditions at the bottom of the channel head bowl. The results of the inspection will be documented. If any unusual conditions are observed, the relevant actions described in NSAL121 will be followed.
(9)  Cold leg sample shall include all tubes with detected hot leg cracking. If cracking is then detected in the cold leg sample, expand sample to 100% of cold leg.
(10) If more than one S/G shows cracking, expand inspection scope to 100% of the affected sample for all S/Gs.
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Table 24  Summary of Detected Wear Indications and Anomalies for PTN3 at EOC 28 - March 2017 (Total Count/Newly Detected/Tubes Plugged)
Location              Indication          S/G 3A              S/G 3B            S/G 3C            Total AVB                              Wear              25/1/1              40/2/0            147/6/0          212/9/1 (1)
TSP (Lands)                      Wear              2/0/0              4/0/0              8/0/0          14/0/0 TSP (Edges) (2)                  Wear              8/7/1              2/2/1              9/6/0          19/15/2 TSP (Edge/PLP) (3)              Wear              0/0/0              1/1/1              1/1/1            2/2/2 FBP                              Wear              0/0/0              2/0/0              0/0/0            2/0/0 Tube Obstruction                                  0/0/0              1/0/1              0/0/0            1/0/1 S/G Total:        35/8/2              50/5/3          165/13/1        250/26/6 Notes:
(1) Indications associated with TSP wear at the land contacts of broached holes.
(2) Indications associated with TSP wear at the lower or upper TSP edges (first observed in 2010).
(3) Indications associated with TSP wear at TSP edges coincident with possible loose part (PLP) indication.
These indications are considered as loose part wear at the TSP edge.
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Figure21 - Schematic Illustration of Turkey Point Steam Generators AIM 2003107742Q1 (NP), Rev. 1                NON-PROPRIETARY                      Page 20
 
3 l Operational Assessment Methodology 3.1 Tube Integrity Requirements The operational assessment (OA) is forwardlooking and provides an estimate of the operational period wherein the steam generators will maintain the CM performance criteria. The performance criteria were established for structural integrity and accidentinduced leakage in [1]. The structural integrity performance criteria (SIPC) and accidentinduced leakage performance criteria (AILPC) are as follows:
Structural Integrity  All inservice steam generator tubes shall retain structural integrity over the full range of normal operating conditions (including startup, operation in the power range, hot standby, and cool down), all anticipated transients included in the design specification, and design basis accidents. This includes retaining a safety factor of 3.0 against burst under normal steady state full power operation primarytosecondary pressure differential and a safety factor of 1.4 against burst applied to the design basis accident primarytosecondary pressure differentials.
Apart from the above requirements, additional loading conditions associated with the design basis accidents, or combination of accidents in accordance with the design and licensing basis, shall also be evaluated to determine if the associated loads contribute significantly to burst or collapse. In the assessment of tube integrity, those loads that do significantly affect burst or collapse shall be determined and assessed in combination with the loads due to pressure with a safety factor of 1.2 on the combined primary loads and 1.0 on axial secondary loads.
AccidentInduced Leakage  Accident induced leakage performance criterion: The primaryto secondary accident induced leakage rate for any design basis accident, other than SG tube rupture, shall not exceed the leakage rate assumed in the accident analysis in terms of total leakage rate for all SGs and leakage rate for an individual SG. Leakage is not to exceed 0.6 gpm total through all SGs and 0.2 gpm through any one SG.
The original TS leakage limits for Turkey Point were 1.0 gpm total and 500 gallons per day (gpd) for any single generator. The leakage limits were reduced to 0.60 gpm and 0.20 gpm respectively following the adoption of the alternate source term as part of the Turkey Point License Amendment Nos. 244/240.
Note that the limit of 0.20 gpm equals 288 gpd.
Guidelines for performing the integrity assessment of steam generator tubing are given in [2]. It has been established that the limiting criterion for tube structural integrity for PTN3 is maintaining the margin of 3.0 against burst under normal steady state full power operation primarytosecondary pressure differential [6]. In situ pressure testing guidance for verifying tube burst and leak integrity experimentally during the outage is given in [7].
3.2 Performance Acceptance Standards The performance acceptance standards for assessing tube integrity to the structural integrity and accident leakage performance criteria apply to both condition monitoring and operational assessments.
The acceptance standard for structural integrity is:
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The worstcase degraded tube shall meet the SIPC margin requirements with at least a probability of 0.95 at 50% confidence.
The worstcase degraded tube is established from the estimation of lower extreme values of structural performance parameters (e.g., burst pressure) representative of all degraded tubes in the bundle.
The acceptance standard for accident leakage integrity is:
The probability for satisfying the limit requirements of the AILPC shall be at least 0.95 at 50%
confidence.
The analysis technique for assessing the above conditions may be either deterministic or fully probabilistic in calculation format. The different analysis methods and input assumptions for these assessments are discussed in the EPRI IAGL [2].
3.3      Structural Models The burst strength of a tube subjected to mechanical wear and corrosion degradation was established from industry methods. Wear degradation is represented as a nonplanar flaw, which in general has limited axial or circumferential extent of the damage. Corrosion degradation is characterized by the parameters depth and length of an assumed cracklike planar flaw representing the extent of the degradation. This form of planar degradation can be axial or circumferential, or mixedmode. A library of burst models for various flaw configurations are given in the EPRI Flaw Handbook [8]. Figure 31 shows the burst models for wear degradations. Figure 32 shows the burst models for axial and circumferential cracking.
The burst models are developed from regression analysis of burst test data on actual tube specimens.
The structural parameter controlling tube burst for axial degradation is the structural minimum depth.
For circumferential degradation, the controlling structural parameter is the percent degraded area (PDA) of the flaw based on the tube crosssection.
3.3.1 Burst Pressure Relationships for Wear Degradation Wear degradation is the only existing mechanism for PTN3 steam generators. Typical wear scars such as those created at tube support structures can be well represented as axial thinning with limited circumferential extent (Figure 31a). Given the structurally significant length and depth dimensions, the burst pressure for an axial wear scar is computed from the following burst equation [8]:
c                                    t          L PB  0.58(S y  Su )    1.0        h  291  ZR                                    (31)
Ri      L  2t where PB is the estimated burst pressure in psi, Sy + Su is the sum of the yield and ultimate tensile strength of the tube material at operating temperature, t is the wall thickness, Ri is the inner tube radius, L is the characteristic degradation length, and h is fractional wear depth (d/t). The parameter R is the standard deviation of the offset pressure and represents the relational uncertainty in the computation of burst pressure. The parameter Z is the deviate for a standard normal distribution. For deterministic analysis, the lower 95% tolerance bound on burst pressure is when Z is equal to 1.645.
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3.3.2 Burst Pressure Relationships for Axial Corrosion Degradation Corrosion degradation is classified as a potential mechanism for PTN3 especially at locations of elevated stress. For evaluation of axial cracking, the following burst equation has been used by the industry [8]:
c                                            t                    L PB  0.58(S y  Su )      (1.104  ZC )        h                          (32)
Ri                  L  2t where for OD cracking, is equal to 1.0, and for ID cracking, 1
(33) t      L 1 h Ri L  2 t The parameter c is the standard deviation of model regression pressure and represents the relational uncertainty in the computation of burst pressure. The parameter Z is the deviate for a standard normal distribution.
3.3.3 Burst Pressure Relationships for Circumferential Corrosion Degradation Again, corrosion degradation is classified as only potential for PTN3. For evaluation of circumferential cracking, the industry has used the following burst equations [8]:
c PB  (S y  Su )
Rm t
0.57326  0.35281(PDA / 100)  ZPN  (Region 1)            (34a)
PB  (S y  Su )
Rm t
1.2227[1  (PDA / 100)]  ZPN        (Region 2)            (34b) where the burst pressure is the lower value from the two above equations. PDA is the percent degraded area, Rm is the tube mean radius, and PN is the relational uncertainty for the regression model. The parameter Z is the deviate for a standard normal distribution.
3.4    Leak Rate Models As described in [7, 9], a twophase flow algorithm can used to compute flow rates through cracks as a function of pressure differential (p), temperature (T), crack opening area (A), and total throughwall crack length (L). Friction effects and crack surface roughness were included in the model. Calculated MSLB, room temperature, and normal operating condition leak rates were fitted to regression equations. The leak rate regression equation for MSLB conditions is given as:
c Q  { a  b exp[ c (A /L)n  d(A /L) ]} A pm                                    (35) where a, b, c, d, n, and m are regression coefficients as determined by analysis results. The leak rate Q is expressed in terms of gpm at room temperature (70F). To convert to gpm at any other temperature, AIM 2003107742Q1 (NP), Rev. 1                            NON-PROPRIETARY                        Page 23
 
the calculated Q is multiplied by the ratio of the specific volume of water at temperature (T) to the specific volume of water at 70F. The pressure, p, is in units of psi, A is in inches2, and L (equivalently Lleak as defined above) is in inches. The crack opening area is calculated using appropriate methods discussed in [7].
Equation 33 is appropriate for computing accidentinduced leak rates for SCC degradation. The validity of the leak rate equations is provided by a comparison of calculated leak rates versus measured leak rates as discussed in [7, 9].
For wear type degradation, the likelihood of throughwall leakage is determined from the projected maximum wear depth that would lead to a popthrough or throughwall penetration. A specific leak rate value is not directly computed but it is conservatively assumed that if a wall penetration occurs, the accidentinduced leak limit will be exceeded.
3.5      Inspection Interval Analysis The primary objective of an OA is to determine the allowable operating period between inspections.
This can be accomplished by either deterministic analysis methods or by fully probabilistic modeling of the input variables 3.5.1 Deterministic Analysis A deterministic analysis approach was applied for the existing wear mechanisms to establish an allowable cycle or multicycle run time in accordance with EPRI IAGL. A plug on NDE sizing strategy is used for calculating the allowable inspection interval for these mechanisms. A deterministic OA for calculating cycle run times requires conservative estimates for indication size at beginningofcycle (BOC), limiting size at EOC, and degradation growth rate. For each wear degradation mechanism, the projected maximum worstcase depth at the next scheduled examination is calculated from:
dEOC      dBOC  (WR) tINSP                                                        (36) where dBOC is the depth in percent throughwall (% TW) at the BOC, dEOC is the depth in % TW at EOC, WR is the growth rate due to wear (% TW/EFPY), and tINSP is the operational period in EFPY until the next scheduled examination. Equation 36 is later used in the OA (see Section 5) for the three detected wear mechanisms for 3cycle inspection interval.
3.5.2 Probabilistic MultiCycle Analysis The analysis method used for the potential mechanisms for PTN3 OA is a fully probabilistic analysis of the full tube bundle in accordance with Section 8.3 of the EPRI IAGL [2]. This level of analysis is required because the deterministic approach is not capable in accurately evaluating the potential mechanisms. A plugondetection repair strategy is applied for all indications found within the tube pressure boundary.
The probabilistic model consists of a Monte Carlo simulation of the processes of initiation, degradation growth, ECT inspection, and the removal of degraded tubes. A schematic illustration showing the simulation process on how the distribution of worst case calculated burst pressures are established is shown in Figure 33. The state of degradation of the steam generator tubing is simulated in the model AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                      Page 24
 
by the total flaw population that is defined by several attributes. These attributes include the population size and the distributions of length, structural depth, maximum depth, and material properties. Given a randomized set of these attributes for each flaw indication in the simulated population, an estimate of burst pressure and leakage can be made for each indication of the flaw population. From these estimates, population attributes, such the distribution of minimum burst pressure and accident-induce leakage are determined.
The probabilistic computations were performed using the Interteks OPCON Version 3.03 program [10].
The logic flowchart of the multicycle method is shown in Figure 34. A timetoflawinitiation (Weibull) function is applied. The physical processes of flaw initiation, flaw growth and simulated inspections (via use of a POD function) are modeled for several past and future cycles. Benchmarking of results to the observed information obtained from past inspections provides assurance of the accuracy of predictions over the operating interval to the next inspection.
The OPCON program simulates up to about 15,000 individual initiation sites over several operating cycles. The overall simulation process consists of many thousands of individual Monte Carlo trials, each of which simulates the degradation state of a complete steam generator, or composite steam generator for a given degradation mechanism. The Monte Carlo simulation involves many trials to obtain a converged solution.
The simulation process is shown in Figure 34, which illustrates the Monte Carlo process. There are three major steps in the process:
a Flaw Initiation: Define the attributes for each flaw for the entire period of the analysis trial. This includes tube material properties, the flaw length, and the flaw shape factor. This information and the information for the undetected population of flaws from the prior inspection define the BOC population.
Flaw Growth: Each flaw in the BOC population grows at a wear rate randomly sampled from the wear rate distribution for the prescribed operational period for the cycle. At the end of this step, the EOC flaw distribution is defined. The set of flaws are evaluated for burst pressure and leakage. The flaw with the lowest burst pressure is retained for each trial to establish the distribution of worst case values for comparing with the SIPC at the end of the analysis. Likewise, the cumulative leakage for each trial is retained to determine the 9550 leak rate included in the leakage evaluation for all degradation mechanisms and comparison with AILPC.
Flaw Detection: In the inspection process, the POD is applied to each flaw in the EOC population to create the detected and undetected populations. The detected flaws are compared with the plug limit for the plant and tubes requiring removal are plugged. For plugondetection, all detected flaws are removed (no detected indications flaws can be returned to service at the start of the next operating cycle, except in the case of approved alternate repair criteria, e.g., H* ARC). The undetected population is important, and that flaw population becomes part of the BOC distribution for the next inspection interval.
For the evaluation of the potential mechanisms at PTN3, it is conservative assume to assume for the BOC distribution of flaws following the last inspection that at least one SCC indication had initiation sometime in the previous operating period and that the initiated indication(s) where not reported. As a general figure of merit, the size of the missed indications will be on the order of the no smaller than 5%
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POD value for the ECT technique used in the previous inspection. This assures a reasonable conservative starting population for the simulation.
The simulation process generates a record of the results of all trials performed from which overall burst and leakage probabilities may be inferred and appropriate distributional information obtained. This process is carried over the past operational cycles and current/future operational cycles.
The actual structural dimensions of each flaw, dST and LST, are tracked for the complete trial. Growth is applied to the structural depth. The shape factor for each flaw is applied at the beginning of each trial prior to inspection and the POD determines whether the flaw is detected or not detected. The final output contains the individual cumulative distributions for actual structural depths, detected actual structural depths, and measured maximum depths. The measured depth distribution is created by applying the measurement uncertainty to each flaw by random sampling from the linear regression model on depth sizing.
3.6      Measurement Uncertainty Measurement uncertainty for sizing of indications was applied to NDE results based on mechanism and ECT probe. The source of these data is the EPRI ETSS document. A linearized relationship between actual size and NDE size was assumed. For relating actual sizes from NDE results, X Actual  A 0  A1 XNDE  Error                                          (37) where XActual and XNDE are the indication sizes for actual and NDE bases, and A0, A1, and Error are regression fit constants (intercept, slope, and random error which include the standard error of estimate, e, for the technique and analysts error, a). For relating measured sizes from predicted actual
: sizes, XNDE  B0  B1 X Actual  Error                                            (38) where B0, B1, and error are again regression constants derived from fitting sizing data.
Industry data (ETSS) were used to define the parameters in Eqs. 37 and 38 from standard linear regression data analysis [11]. A summary of sizing uncertainties for the mechanisms applicable to PTN3 is given in Table 31. The scatter in actual data about the regression fit is assumed to be normally distributed with a standard deviation equal to the standard error of estimate.
Measurement uncertainty was applied on the repaironNDE sizing calculations for the existing degradation mechanisms. For the probabilistic analyses, OPCON tracks the progression of the actual flaw sizes (depth and length), so measurement uncertainty was not relevant in the OA for the potential mechanisms in this situation of a one cycle extension.
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Table 31: Relationships for Measurement Uncertainty for PTN3 - March 2017 (1) a, cCondition Monitoring                      Operational Assessment(1)
Mechanism/                Eddy Current                                ETSS            Intercept      Slope        Std Error      Intercept    Slope    Std Error Location                    Probe              Sizing            Reference              A0          A1            e              B0        B1          e Wear at AVB Supports(2)            Bobbin          Depth (%TW)      96004.1Rev 13            2.892      0.984          4.185          1.418      0.983      4.183 TM
                                      +Point          Depth (%TW)        10908.4 Rev 1          0.130      1.058          3.784          0.704      0.924      3.535 Wear at Tube Support Plates(3)      +PointTM        Depth (%TW)      96910.1 Rev 10          4.296        1.007          6.680          0.714      0.909      6.346 TM
                                      +Point          Depth (%TW)        27905.1 Rev 2          4.400      1.093          2.000          4.284      0.909      1.824 Wear at Flow Baffle Plates        +PointTM        Depth (%TW)      96910.1 Rev 10          4.296        1.007          6.680          0.714      0.909      6.346 Wear in Freespan(4)            +PointTM        Depth (%TW)        21998.1 Rev 4          5.809      1.024          6.284          0.976      0.861      5.764 Foreign Object Wear at (3,4)          +PointTM        Depth (%TW)        21998.1 Rev 4          5.809      1.024          6.284          0.976      0.861      5.764 TopofTubesheet
                                      +PointTM        Depth (%TW)        27905.1 Rev 2          4.400      1.093          2.000          4.284      0.909      1.824 NOTES:
(1) Condition monitoring sizing is Actual versus ECT. Operational assessment sizing is NDE versus Actual. The parameters A0, A1 and e are obtained from ETSS measurement uncertainty correlations. The parameters B0, B1 and its corresponding e were calculated from a regression fit of the ETSS sizing data.
(2) ETSS 96910.1 Rev. 10 is not qualified for wear at AVBs.
(3) ETSS 96910.1 Rev. 10 was used to size indications within TSP lands. ETSS 27905.1, Rev. 2 was used for sizing indications at TSP edges.
(4) Wear in freespan was not detected at EOC 28 (ETSS 21998.1 Rev.4 was not required). Volumetric indication (loose part wear) was sized with ETSS 27905.1, Rev. 2.
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c a) Axial Thinning (Limited Circumferential Extent) c b) Circumferential Thinning (Limited axial Extent)
Figure 31  Flaw Models for Wear Degradation (a) Axial and (b) Circumferential AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                        Page 28
 
c a) PartThrough Axial Cracking c
b) PartThrough Circumferential Cracking Figure 32  Flaw Models for SCC Degradation (a) Axial and (b) Circumferential.
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c Figure 33  Aspects of Monte Carlo simulation to Calculate Probability of Tube Burst [2]
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a                              MULTICYCLE MODEL LOGIC Figure 34  Probabilistic Simulation to Determine WorstCase Degraded Tube - Full Bundle Analysis AIM 2003107742Q1 (NP), Rev. 1                      NON-PROPRIETARY                          Page 31
 
4 l Input Variables and Distribution Functions The input variables and the statistical distributions representing the uncertainties in these inputs in the OA to determine structural and leakage integrity are given in this section. These include the mechanical strength, flaw characterization (flaw sizes and shapes), and more importantly, the probability of detection functions (POD) and degradation (wear) growth rates.
4.1 Tubing Properties The PTN3 is a threeloop system design Model 44F, with each steam generator having 3,214 tubes. The steam generator tubing has an outside diameter of 0.875 inch and a nominal wall thickness of 0.050 inch. The tubing material is Alloy 600 thermallytreated (A600TT) [4].
The mechanical strength at operating temperatures was obtained from the EPRI Flaw Handbook [8] with the following statistical values for yield plus ultimate tensile strength, y + u at T = 650oF being established:
Mean:                134,668 psi St Dev:              6,383 psi Min Limit:            122,000 psi Max Limit:            150,000 psi The RT properties for the mean strength of 7/8 OD tubing is 153,380 psi from Table 41 in [8]. It was assumed that the temperature adjusment factor of 0.878 from Table 42 in [8] for 3/4 OD tubing can be used to reduce the mean strength to 134,668 psi at 650oF on a relative basis. Following the recommendations on the options in Section 4.2 in [8], the RT StDev is used for the variation on the elevated temperature properties. This assumption is conservative. The mechanical properties given above are assumed to be normally distributed when used in a probabilistic analysis. The min and max limits on the distribution were estimated to fall within the range of 2.0 to 2.4 StDev about the mean in order to remove any phyically unrealistic values in the simulation.
4.2 Operating Conditions Extended power uprate (EPU) was implemented for both units at the PTN. The EPU license amendment request (LAR No. 2050 was approved by the NRC in June 2012, license amendment Nos. 249/245). The first cycle at EPU conditions for PTN3 was Cycle 26 in Spring 2012. EPU modifications were implemented over the preceding refueling outages (Cycles 24 and 25 for PTN3). Modifications included turbine generator rewinds in the first outages and major component replacements (including the high pressure turbine) during the second outages.
At normal full power operation, the differential pressure across the tube wall has been conservatively assumed as 1514 psi based on design parameters [6]. This steady state normal operating pressure differential (NOPD) bounds current operating conditions, which shows actual NOPD under the EPU conditions is less than 1455 psi for PTN3 [4].
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For accident conditions, maximum MSLB pressure is assumed as 2560 psi. This value for MSLB pressure is also conservative and is based on reactor coolant system design pressure. During Cycle 30, actual steam pressure and THOT for PTN3 were 791 psig and 610.6&deg;F. Prior to EPU, THOT was 601.4oF The operating parameters for PTN3 used for the potential mechanism are listed below:
Normal operating pressure differential (NOPD)            1460 psi Limiting accident pressure differential (LAPD)            2560 psi Hotleg temperature (THOT)                                611oF Three times normal operating pressure (3xNOPD) is therefore 4380 psi. Prior OA results from EOC 28 for the existing mechanisms were based on NOPD = 1514 psi and were not revised because they are conservative.
The operational period for Cycles 26 through 31 were provided by FPL. The EFPY at each outage is shown in the table below [12].
Cycle Length EOC            Outage Date              Inspection (EFPY) 26              March 2014                  Yes                    1.30 27            October 2015                Skip                    1.42 28              March 2017                  Yes                    1.27 29          September 2018                Skip                    1.43 30              March 2020                Skip*                    1.38 31            October 2021                Yes                    1.45
        *Note: Proposed to defer EOC 30 examination to EOC 31.
4.3 Probability of Detection The probability of detection for the examination technique used in the inspection process is an important input to the probabilistic OA because it establishes the size and number of indications that can remain undetected in the tube bundle. When assuming at the start of a cycle that indications are postulated to exist after an inspection, the largest missed postulated flaw(s) generally defines the worst case EOC flaw at the next inspection. The Monte Carlo simulation shown in Figure 34, when plugon detection inspection strategy is used, the BOC flaw population is, by definition, the population of undetected after inspection.
The POD for the inspection technique can be developed in one of three ways:
: 1) Performance demonstration process (PDP) using analyst data on degraded tubes with known number and sizes of the mechanism of concern. A specialized nonlinear regression process is then used to establish the probability of detecting an indication of a given depth.
: 2) An analytically based Ahat methodology or the similar EPRI MAPOD methodology which uses a signal processing approach dealing primarily with flaw signal amplitude and noise amplitudes.
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These methods permit the quantification of POD function behavioral changes with various levels of interfering signal (noise) such as may be present.
: 3) An empirical approach that relies on a benchmarking process to observed inspection data over several cycles of operation. The cumulative distribution of predicted flaw depths is closely related to the system POD function present. In addition, the absence of flaws below a threshold depth precludes a POD function with a nonzero POD below that depth. This eliminates a significant portion of possible POD function candidates obtained by other means.
In practice, a combination of two or more of these methods is often used to obtain a robust estimate of the POD function parameters.
The POD was established from industry data resulting from PDP as developed for recent OAs for St.
Lucie as well as the Turkey Point plants. The POD as a function of wear depth derived from pulledtube bobbin coil data (EPRI ETSS 96004.1). The POD parameters for logistic and loglogistic model used in the Monte Carlo Simulation are shown below:
1 POD(X)                                (Logistic)                    (41) 1  exp[A  B(X)]
1 POD(X)                                (LogLogistic)                (42) 1  exp[A  B Log10 (X)]
where X is the depth in %TW, and the parameters A and B are obtained by logistic regression analysis of hitmiss data from PDP or MAPOD simulations.
The loglogistic model was used in the OA for the potential mechanisms at PTN3. The model parameters for the ECT technique were obtained from qualified industry data or derived from evaluations of the inspection process to obtain the systematic POD including the effect of signal noise at the tube location of interest. For comparative purposes, the +PointTM and Bobbin PODs for detection of axial ODSCC at broached TSPs are shown in Figure 41 [11, 13]. This figure shows the relative detection performance of the +PointTM versus the Bobbin coil for detecting SCC.
4.4 Degradation Growth Rates 4.4.1 Wear Degradation Degradation growth rates for tube wear at support structures and flow distribution baffles have been established in the original EOC 28 OA from past inspections. Growth rates are based on repeat measurements where the distribution of growth rates have been calculated and trended over time.
The sitespecific wear rate for AVB wear indications at Turkey Point for EOC 28 has previously been determined in [14]. The 95% upper bound growth rate was conservatively estimated for use in the original OA. The wear rates for TSP and FBP tube contact locations were determined from the prior examination results and historical reviews of previous outage inspections for both PTN3 and PTN4. A summary of the estimated mean and 9550 wear rates is given below for both units [14]:
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Average WR          9550 WR          Maximum Limit Wear Mechanism
(%TW per EFPY)    (%TW per EFPY)        (%TW per EFPY)
AVBs                      1.5                3.3                    10 TSP at Lands                3.67                6.5                    12 TSP at Edges                                    6.5*
Flow Baffles                1.92                6.5                    12
            *Note: From most recent inspection at PTN4 at EOC 30. Data too limited to establish a full distribution The application of the wear rates used in the OA is described in more detail in Section 5.
4.4.2 Corrosion Degradation There is no active corrosion degradation in the PTN SGs within the pressure boundary; crack growth rates are therefore developed from industry data where available. For the potential mechanisms, the EPRI IAGL typical default distribution had been shown to conservative for A600TT based on the analyses of the available data [13]. The number of tubes with SCC indications in the A600TT fleet is not enough to develop reliable growth rates with the exception of circumferential ODSCC at the TTS expansion transition. Therefore, the default distributions are used in the OA for the potential degradation mechanisms at PTN3. The typical and bounding distributions recommended in the EPRI IAGL are plotted in Figure 41.
For circumferential degradation, a review of SCC data was performed and compared with the EPRI default rates. Figure 43 presents a plot of PDA and maximum depth growth for the EOC 14 and EOC 15 indications from Plant A. These data were provided by the utility. This plot includes the IAGL typical default PDA growth function for comparison. As shown on this plot the IAGL typical default function is judged very conservative for this mechanism. Given the conservatism of this function compared to the Plant A growth data, the OA for circumferential ODSCC will use the EPRI IAGL typical default growth rate as a representation of maximum depth growth.
Figure 43 also shows the PDA growth function developed by applying a shape factor of 1.25. The EPRI IAGL recommends the use a shape factor of 1.25 to estimate maximum depth growth from structural average growth. In this example the IAGL default growth significantly bounds the Plant A data. The IAGL structural average (PDA) growth actually bounds the Plant A maximum depth growth. If the IAGL PDA growth is used as a maximum depth growth allowance the PDA growth can be estimated by application of the shape defined in [2]. Application of the shape factor results in a lognormal mean PDA growth value of 1.28. This growth, which still bounds the Plant A data, was used in a sensitivity case to show the conservatism of the IAGL default growth and further supports the assumption that the EPRI default growths rates are conservative for the potential mechanisms in PTN3. One observation of the circumferential data is that a large percentage of cracking population becomes nongrowers (between 10% to as high as 40%).
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Another conclusion from the EPRI Feasibility Study [13] is that the PWSCC growth rates are bounded by ODSCC growth rates for the same SCC orientation. This observation is used to apply the OA results from the ODSCC to bound the behavior of PWSCC (see Section 6).
4.5 Initiation Function The Weibull statistical distribution is used to model the initiation of SCC in A600TT tubes. The Weibull distribution is a well know model for representing time to failure in various forms of aging mechanisms such as fatigue, cracking, etc. A three parameter function is use where the evolution of SCC during operation is calculated from a slope parameter, characteristic life (shape parameter), and setback. The Weibull model has been utilized in many OAs that addressed SCC behavior of A600 mill annealed (MA) tubing for many of the original SGs. The Weibull model has been shown to provide a conservative representation of flaw initiation trending.
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a, b, c POD Functions for Axial ODSCC at Tube Suport Plates 1.0 0.9 0.8 0.7 Probability of Detection 0.6 0.5 0.4 0.3 0.2
                                                                                                  +PT (ETSS I28425) 0.1                                                            Bobbin (ETSS I28413)
Bobbin  EPRI Study 0.0 0  10      20      30      40        50        60  70    80          90        100 Depth, (%TW)
Figure 41  Comparison of Probability of Detection Functions for Axial ODSCC AIM 2003107742Q1 (NP), Rev. 1                                    NON-PROPRIETARY                                        Page 37
 
c                                            EPRI Default Growth Rates for A600TT on Structural Average Depth 1.0 0.9 0.8 0.7 Cumulative Distribution, CDF 0.6 0.5 0.4 0.3 0.2                                                                    EPRI IAGL "Typical" EPRI IAGL "Bounding" 0.1 0.0 0    2    4    6    8  10    12    14  16  18  20    22      24      26      28  30 Crack Growth Rate, CGR (%TW per EFPY)
Figure 42 - Default Crack Growth Rates for A600TT Tubing at 611oF AIM 2003107742Q1 (NP), Rev. 1                                                NON-PROPRIETARY                                      Page 38
 
a, b, c Figure 43 - Comparison of Various CGR Functions from Operating Data AIM 2003107742Q1 (NP), Rev. 1              NON-PROPRIETARY                      Page 39
 
5 l Operational Assessment for Existing Mechanisms 5.1 Assessment Method A deterministic OA was completed at EOC 28 for a 2cycle operating period based on predicted burst pressures and accidentinduced leakage, sitespecific structural limits, and degradation growth rates through to EOC 30 [3]. This OA was reevaluated for a 3cycle operating period skipping the tube examination at EOC 30. The OA considered the scope of the examination, potential for increased growth rates, and the potential for increased numbers of indications at subsequent examinations.
The existing mechanisms are wear degradation due to tube contact points at AVBs, TSP intersections, and at FBP locations. Wear degradation from known foreign objects in each SG are also evaluated for 3 cycle operating period. The OA for each degradation mechanism evaluated a runtime plan for future cycles of operation. The deterministic calculations for AVB wear, wear at TSPs, and wear at FBP is based on the guidance contained in [2].
Plug (or repair) on NDE sizing strategy is used in the OA of the existing mechanisms. The basic analysis steps for each degradation mechanism are:
: 1. Identify the largest flaw indication which could potentially remain in service at BOC
: 2. Apply NDE bounding uncertainty to the largest flaw potentially remaining in service at BOC
: 3. Calculate the projected largest flaw at EOC for each scheduled outage by applying the upper 95th percentile growth rate for the next operating period to the largest flaw at BOC
: 4. Compare the projected largest flaw size at future EOC inspections to the structural limit size
: 5. Compare the projected largest flaw size at future EOC inspections to leakage size A successful deterministic OA for 3cycles must demonstrate that the performance criteria for tube integrity (burst and leakage) will be satisfied at the acceptance probability of occurrence level of 9550 for all input conditions. Compliance with the structural performance criterion is indicated when:
dEOC  dSL                                            (51) where dEOC is the limiting defect depth at the next tube examination, and dSL is the structural limit. The projected limiting defect for wear is determined from dEOC    dDET  WR (tINSP )                                  (52) where dDET is the actual defect size that can be reliably detected by the inspection technique, WR is the bounding wear rate, and tINSP is the projected cycle length until the next examination. For plug (or repair) on NDE sizing, the BOC defect size is based on distribution of measured or observed sizes, the projected limiting defect must consider NDE measurement uncertainty:
dEOC  dNDE  dERR  WR (tINSP )                                  (53) where dNDE is the measured size, and dERR is the total measurement error at the upper 95% bound.
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Verification by benchmarking predictions with observations as recommended by the EPRI IAGL [2] is discussed in [3]. This process was performed to confirm that analysis input and assumptions regarding detection and progression of the existing degradation mechanism are correct. Benchmarking of the predicted worstcase depths from the prior EOC 26 OA with the NDE results at EOC 28 tube examinations demonstrated that the OA model calculation results bound the largest detected indications for all degradation mechanisms. Therefore, this confirms the prior OA methods and assumptions for existing mechanisms are conservative, and therefore appropriate for assessing a 3cycle operating period.
5.2 AntiVibration Bar Wear The EOC 28 examination for AVB wear consisted of fulllength bobbin probe examination of 100% of the active tubes in Rows 3 and higher, and 50% examination of the Ubend regions in Rows 1 and 2 by +PointTM. Wear indications were sized, based on an EPRI qualified examination technique (ETSS 96004.1). The largest indication allowed to remain inservice at EOC 28 was 36% TW (NDE depth).
This depth is size corrected to the upper 9550 actual size using ECT measurement uncertainty for the ECT technique.
Historical tube wear data for AVB supports for 2010 through 2017 is shown in Figure 51. These data show that AVB wear rates are low with a large percentage of indications showing no growth. There is no significant impact from the power uprate (EPU) implemented in 2012. The general trend is for both the average and upper 95th percentile wear rates to attenuate over time.
The results for the OA are shown in Figure 52. The applied wear rate is 3.3 %TW per EFPY and represents an upper 95th percentile bound as described in the original OA report [3]. The projected depth is less than the 3xNOPD EOC Structural Limit of 64.9% TW after a 3cycle operating period to EOC 31. Therefore, the structural performance criteria of NEI 9706 will be satisfied. The cumulative projected accident leakage will be negligible over the next operational period based on the projected limiting depth sizes for this mechanism.
5.3 Wear at Tube Support Plates For wear indications at TSP locations occurring at the broachedhole lands and at outside surface edges, the projected wear rate for use in the deterministic OA was established from current and past inspection data. The OA structural limit for comparing with the projected limiting wear depth is calculated as 66.6% TW from the geometric profile model for wear at the lands of the broach holes or TSP edges [3]. The largest wear depth by NDE from the EOC 28 examination that is returned to service is 14% TW and 19% TW for wear at the lands and wear at the edges. Depth sizing for TSP wear uses
+PointTM probes (ETSS 96910.1 and ETSS 27905.2). Measurement uncertainty is applied at the upper 95th percentile value in accordance with the EPRI IAGL.
The results from the OA evaluation for 3cycles of operation are shown in Figures 53 and 54. The applied wear rates are bounding based on the evaluation described in the original OA report [3]. For wear at TSP edges, there were very limited repeat depth data for wear in past inspections at PTN. The wear rate that was conservatively assumed as an upper bound was 10.7% TW per EFPY. Recent AIM 2003107742Q1 (NP), Rev. 1                  NON-PROPRIETARY                                  Page 41
 
examination at PTN4 indicated a much lower wear rate for this mechanism (0.4% TW per EFPY). In that assessment, a conservative estimate of the upper 9550 wear rate for TSP edge wear was defined as 6.5%TW per EFPY. Using that value for PTN3 gives the second projection that is plotted in Figure 54. In either analysis, the projected worst case depth at EOC 31 is less than the EOC Structural Limit.
In summary, the projected depths for both TSP locations are less than the 3xNOPD EOC Structural Limits after a 3cycle operating period to EOC 31. Therefore, the structural performance criteria of NEI 9706 will be satisfied. The cumulative leakage rate for TSP wear indications was determined to be negligible based on the upper 95% onesided tolerance limit on peak depth.
5.4 Wear at Flow Distribution Baffle Plates The EOC 28 examination, which consisted of fulllength bobbin probe examination of 100% of the active tubes, detected wear/volumetric indications at flow distribution baffle plates. The indications were sized with +PointTM probe (ETSS 96910.1). The EOC Structural Limit for comparing with the projected limiting wear depth at EOC has been established at 71.4% TW [6]. The maximum NDE depth of the indication returned to service is 9% TW.
Due to limited inspection data, a bounding wear rate is estimated from the past inspections for Turkey Point and other industry information as discussed [3]. For the previous PTN OAs, with little or no growth observed since EOC 26, the upper 95th percentile wear rate was conservatively defined as 6.5%TW per EFPY consistent with TSP wear rates. The results of the depth projection over three cycles are shown in Figure 54. Therefore, the structural performance criteria of NEI 9706 will be satisfied at EOC 31. The cumulative projected accident leakage will be negligible over the next operational period based on the projected limiting depth sizes for this mechanism.
5.5 Foreign Object Evaluation Secondary side foreign objects found in the steam generators and PLP locations identified by ECT at EOC 28 were evaluated by FPL. All newly discovered foreign objects have been removed including all discovered loose parts shortly after the feed pump (SGFP) strainer failure, which occurred in May 2013.
There were no significant parts resulting from the SGFP strainer found at EOC 26 or EOC 28. The potential of having additional loose parts enter the tube bundle has been evaluated by FPL JPNPTN SEMS96003.
Following the failure of SGFP strainers described in AR 1871783 which resulted in a downpower event at PTN3, a rootcause evaluation (RCE) was initiated which included an evaluation of potential steam generator tube wear from loose parts resulting from possible foreign material intrusion [15]. The RCE confirmed that the S/G 3B SGFP suction strainer had catastrophically failed and introduced foreign objects into the feed train. The pieces of the SGFP strainer, which were recovered from all three Unit 3 steam generators during EOC 26 FOSAR inspections.
Although it is not likely to have any strainer failure debris remaining in the SGs after multiple SSIs, any possible foreign objects remaining in the feed train (from the SGFP suction strainer failure) that have the AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                    Page 42
 
potential to migrate to the steam generators have been evaluated by FPL [16]. In this evaluation, the more likely debris arising from strainer failure were considered. The list of credible debris is based on strainer construction, historical debris trapped in the strainer, and the parts of the strainer(s) that were retrieved.
The most limiting wear time from this assessment is 3.68 years. This extends the allowable operating time for PTN3 steam generators to late 2020, which supports a twocycle inspection interval. This weartime analysis limits the wear projections to the Technical Specification repair limit of 40%TW, which is generally much less than an appropriate structural limit to meet the SIPC margin requirements.
Assuming a wear scar from a foreign object that is a 1inch long of uniform depth (flat shape), the CM structural limit is 53% TW. By scaling the wear time for the postulated loose strainer part, the adjusted wear time becomes 4.88 EFPY.
All known historical foreign objects that remain in the generators and are actively tracked have been evaluated by FPL in JPNPTNSEMS96038 [17]. The limiting object has been classified as metallic slag and resides in S/G 3B. The limiting operating time for this loose part is 4.92 years, which is longer that the extended operating interval of 4.26 EFPY for Cycles 29 through and 31. Therefore, any potential future wear caused from historical foreign objects will be bounded for the 3cycle interval between ECT inspections.
5.6 Summary of Operational Assessment Results for Existing Mechanisms The deterministic OA consisted of a comparative evaluation of the projected limiting indication size with the structural limit for each mode of degradation. The maximum calculated operating interval for each existing degradation mode is summarized in the following table:
Allowable Operating Period between Inspections Degradation Mode                  Allowable Interval AVB Wear                            5.72 EFPY TSP Wear at Lands                        5.70 EFPY (1)
TSP Wear at Edges                        7.16 EFPY FBP Wear                            7.04 EFPY (2)
Postulated Loose Part                      4.88 EFPY Existing Loose Part Wear(3)                  4.92 EFPY Notes:
: 1)  This allowable interval is based on the most recent inspection results on wear rates from PTN4 in March 2019.
: 2)  Reevaluated limiting foreign object from strainer debris that is postulated to exist in a limiting location in the steam generators.
: 3)  The operating period for the limiting known/tracked loose part in S/G 3B.
These allowable intervals (i.e., operating periods) can be graphically determined for Figures 52 to 55 by calculating the difference in operation time from the point where the depth growth line would extrapolate cross the structural limit line from the operating time at the start point at BOC 29.
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Accidentinduced leakage for the existing degradation mechanisms is projected to be negligible for three operating cycles based on the peak depths projected to EOC 31.
In summary, the updated EOC 28 OA supports the operation through the extended operating period (Cycles 29 through 31). The performance criteria of NEI 9706 will be satisfied for the threecycle inspection interval.
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PTN-3 AVB Wear Rates - All SGs 60 2010 Data -Before EPU 55 2014 Data - After EPU 50                                                                                  2017 Data - EPU 45 40 35 Frequency 30 25 20 Upper 95% Bound 15 10 5
0
                                  -5.0  -4.0  -3.0  -2.0  -1.0  0.0  1.0  2.0  3.0  4.0  5.0    6.0  7.0    8.0      9.0  10.0 Wear Rate, WR (%TW/EFPY)
Figure 51  Comparison of Wear Rates at AVB Tube Contacts for PTN3 AIM 2003107742Q1 (NP), Rev. 1                                            NON-PROPRIETARY                                                      Page 45
 
a, b                                                  Deterministic Operational Assessment PTN-3 Detected Wear at Anti-Vibration Bars - EOC 28 (3-Cycle OA) 100 90 80 Structural Limit 3xNOPD 70 Wear Depth, d (%TW) 60 EOC 31 EOC 30 50 EOC 29 BOC 29 40 30 Inspection Outage 20 Skip-Inspecion Outage 10 26      27        28    29      30      31      32          33  34 Operation Time (EFPY)
Figure 52  Operational Assessment of AntiVibration Bar Wear for PTN3 AIM 2003107742Q1 (NP), Rev. 1                                        NON-PROPRIETARY                                  Page 46
 
a, b Deterministic Operational Assessment PTN-3 Detected Wear at Tube Support Plate Lands - EOC 28 (3-Cycle OA) 100 90 80 EOC Structural Limit 3xNOPD 70 Wear Depth, d (%TW) 60 EOC 31 50 EOC 30 40 EOC 29 30 BOC 29 Inspection Outage 20 Skip-Inspection Outage 10 26    27      28      29      30      31      32          33  34 Operation Time (EFPY)
Figure 53  Operational Assessment of Tube Support Plate Wear for PTN3 AIM 2003107742Q1 (NP), Rev. 1                                        NON-PROPRIETARY                            Page 47
 
Deterministic Operational Assessment PTN-3 Detected Wear at Tube Support Plate Edges - EOC 28 a, b                                                          (3-Cycle OA) 100 90 80 EOC Structural Limit 3xNOPD 70 Wear Depth, d (%TW)
PTN3 EOC 28 with upper bound WR 60 50 EOC 31 40 Most recent WR EOC 30            from PTN-4 EOC 30 OA 30 EOC 29 20                                              Inspection Outage BOC 29                        Skip-Inspection Outage 10 26    27        28        29      30    31        32        33      34 Operation Time (EFPY)
Figure 54  Operational Assessment of Tube Support Plate Edge Wear for PTN3 AIM 2003107742Q1 (NP), Rev. 1                                          NON-PROPRIETARY                                  Page 48
 
a, b Deterministic Operational Assessment PTN-3 Detected Wear at Flow Baffle Plates at EOC 28 (3-Cycle OA) 100 90 80 Structural Limit 3xNOPD 70 Wear Depth, d (%TW) 60 50                                                          EOC 31 EOC 30 40 EOC 29 30 BOC 29 Inspection Outage 20 Skip-Inspection Outage 10 26    27        28    29        30    31          32          33  34 Operation Time (EFPY)
Figure 55  Operational Assessment of Flow Distribution Baffle Plate Wear for PTN3 AIM 2003107742Q1 (NP), Rev. 1                                      NON-PROPRIETARY                                    Page 49
 
6 l Operational Assessment for Potential Mechanisms 6.1 Assessment Method The potential corrosionrelated mechanisms have been proactively monitored by performing additional qualified eddy current test (ECT) examinations in past outages. To date, PTN has not experienced any corrosion degradation within the tube bundle, except at the tubeends which is outside of the defined pressure boundary for the tubesheet established by the H* Alternate Repair Criteria for PTN3 [19]. In the revised OA, the above potential mechanisms were all postulated to exist following the last inspection. These mechanisms were each evaluated by performing fullbundle probabilistic analyses to calculate the probability of tube burst and leakage potential in accordance with Section 8.3 in the EPRI IAGL. The probabilistic model included the important input distributions for material strength properties for the tubing, probability of detection for the ECT technique, a lognormal crack growth rate model appropriate for each mechanism at THot, and the use of a Weibull initiation function predicting when SCC flaws have developed over time. The overall numerical model is discussed in Section 3.
The following conservative conditions were assumed at the start of the analysis
: 1) All potential mechanisms are assumed to be existing and evaluated in the OA
: 2) It is assumed that prior to the most recent tube examination, SCC had initiated and was missed (not detected) by ECT during the inspection. This assumption will create a population of undetected flaws that will exist at the start of the cycle following the inspection.
: 3) The default crack growth rates were conservatively used in the OA followed EPRI IAGL recommendations for A600TT tubing.
: 4) For mechanisms that were sampled at the last inspection, the tube population was divided into two grouping per the implemented sampling plan (inspected and noninspected) in accordance with Section 8.6 of EPRI IAGL. The probability of burst and leakage assessment was individually computed for each partially inspected group and later numerically combined to give the total probabilities for the mechanism.
In support of the probabilistic OA for the potential mechanism, a leadplant evaluation was performed where the operating history of PTN3 was compared with those plants that have experienced SCC to estimate equivalent initiation times for each mechanism. This information was primarily used to establish when initiation at PTN3 would have occurred, or will occur, and to help to define the range of Weibull parameters appropriate for PTN3 for the OA. The information for this study is contained in [13].
6.2 Potential Degradation Mechanisms As documented in the Degradation Assessment (DA), there are several corrosionrelated degradation mechanisms that are classified as potential for A600TT tube material. These mechanisms involve forms of stress corrosion cracking (SCC) on the primary (ID) or secondaryside (OD), oriented either axial or AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                  Page 50
 
circumferential to the tube axis, and occurring at different locations in the tube bundle. For PTN3, these potential mechanisms are,
: 1. Axial and circumferential ODSCC at the topoftubesheet (TTS)
: 2. Axial and circumferential PWSCC at the TTS (generally bounded by ODSCC analyses)
: 3. Axial ODSCC at TSP intersections on nonhigh residual stress tubes
: 4. Axial ODSCC at TSP intersections on known high residual stress tubes
: 5. Axial ODSCC at tube dings and dents
: 6. Axial ODSCC in freespans
: 7. PWSCC in small radius Ubends The more limiting mechanisms are the first five in the above list. These mechanisms are existing in other A600TT plants. The last two in the list are not considered controlling mechanisms. Axial ODSCC in freespans (without the presence of a ding) has not been observed. These mechanisms are not formally evaluated but considered to be bounded by axial ODSCC at TSPs.
6.3 Circumferential ODSCC at TTS Expansion Transitions Sample inspections have been performed at PTN3 for detecting the onset of SCC at the TTS. A 50%
sampling of TTS expansion transition region was performed at EOC 26 and EOC 28. At EOC 26, the inspection employed the +PointTM probe for SCC detection. At EOC 28, the XProbe replaced the
  +PointTM for detecting SCC. There was no SCC reported in either inspection.
For the EOC 26 group of tubes, the conservative initiation assumption is that initiation of SCC occurred prior to EOC 26 on the tubes last inspected at EOC 26. That is, SCC initiated in the operating period prior to EOC 26 and was not detected by +PointTM. This results in the longest operating period up to the next inspection at EOC 31, which is five operating cycles from the EOC 26 inspection. A susceptible a population size of 120 tubes was assumed, 60 of which are assigned to the population last inspected at EOC26 and 60 assigned to the population last inspected at EOC 28.
For initiation behavior, a Weibull slope of 1.5 for circumferential ODSCC at units which have not reported SCC has been estimated in [13]. The characteristic life is adjusted to produce one initiation at EOC 25. At EOC 26, the average number of initiated flaws after the 10,000 trials in the Monte Carlo simulation is two, as listed in the table below:
a,                                  Circ ODSCC - Summary 50% Exam at EOC 26 b,          Outage          EOC 25      EOC 26    EOC 27      EOC 28      EOC 29    EOC 30      EOC 31 c          Plant EFPY          23.41        24.71    26.13      27.40      28.83      30.16      31.36 Model EFPY            3.0        4.3      5.72      6.99        8.42      9.82        11.32 Cumulative Initiated        1          2          3          4            5        6          7 Exam Scope            Skip        100%      Skip        Skip        Skip      Skip        TBD Number Detected            0        NDD          0          0            0        0          4 AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                  Page 51
 
a, b, c For the 50% tube population inspected at EOC 26, the relevant inputs to the probabilistic OA model are provided below:
Input File Name:                                          TP3_CircOD_EOC25_1st_initiation_Case1_OA Weibull slope, characteristic life and susceptible population size                      1.5, 45 EFPY, 60 Normal Operating Condition Pressure Differential:                                                1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                          1.5, 0.65, 19%/EFPY Model EFPY Equal to First Initiation, Equivalent PTN3 EFPY:                                0, 23.41 EFPY Probe Type and POD Parameters (EOC 26):                                              +PT; 13.56, 11.12 Probe Type and POD Parameters (EOC 28):                                                XProbe; 2.9, 3.5 For this group, the probability of burst at EOC 31 is 2.44%, and the probability of accidentinduced leakage exceeding the AILPC is 0.14% for this mechanism.
For the 50% tube examination at EOC 28, the same approach is followed except that the assumption that one indication initiates in the operating period prior to EOC 28 and is not detected by XProbe. At EOC 28, the average number of initiated flaws after the 10,000 trials in the Monte Carlo simulation is two, and at EOC 31, there are 5 SCC flaws in service with 3 being detected by XProbe. The operating trend is shown in the table below:
a, b, c                          Circ ODSCC - Summary 50% Exam at EOC 28 Outage            EOC 27    EOC 28      EOC 29    EOC 30      EOC 31 Plant EFPY          26.13      27.40      28.83      30.16        31.36 Model EFPY            3.0        4.27        5.7        7.1          8.6 Cumulative Initiated      1          2          3          4            5 Exam Scope            Skip      100%        Skip      Skip        TBD Number Detected          0        NDD          0          0            3 For the 50% tube population inspected at EOC 28, the relevant inputs to the probabilistic OA model are provided below:
Input File Name:                                      TP3_CircOD_EOC27_1st_initiation_Case2_OA Weibull slope, characteristic life and susceptible population size:                  1.5, 45 EFPY, 60 Normal Operating Condition Pressure Differential:                                            1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                      1.5, 0.65, 19%/EFPY Model EFPY Equal to First Initiation, Equivalent PTN3 EFPY:                          3.0, 23.41 EFPY Probe Type and POD Parameters:                                                      XProbe; 2.9, 3.5 The probability of burst at EOC 31 for this group of tubes is 0.77%. The probability of leakage exceeding the AILPC is <0.14% for this mechanism.
The total probability of burst for this mechanism for comparing with the performance standard of 5% is calculated using a Boolean summation of the two probabilities, POB = 1(10.0244)(10.0077) = 3.19%
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The total POB for this mechanism satisfies the SIPC margin requirement performance standard.
6.4 Axial ODSCC at TTS Expansion Transitions The OA for axial ODSCC at TTS is configured in a similar manner as for circumferential ODSCC at the TTS expansion transition. The only difference between the two models is that the initiation function [13].
a  The population judged to be susceptible to axial ODSCC at PTN3 was determined to 60 tubes. Thus, for the population assumed to have initiated one cycle prior to EOC26, with a susceptible population size of 30 tubes and Weibull slope of 1.5; characteristic life is 40 EFPY.
The length distribution applied is the structural equivalent length developed from the combination of all TTS (ODSCC and PWSCC) and ding/dent SCC indications from the A600TT fleet. For the shorter flaws a conservative length measurement uncertainty allowance was applied. The adjusted total length was combined with a uniform distribution from 1.05 to 2.0, which represents a conservative adjustment to a,  the ratio of total to structural average length for the pulled tube data of ETSS I28424 and I28425.
b, Figure 51 presents a plot of the applied length distribution with the asreported lengths and adjusted c
total length.
For initiation behavior, a Weibull slope of 1.5 for axial ODSCC at units which have not reported SCC has been estimated in [13]. The characteristic life is adjusted to produce four initiates at EOC 25. At EOC 26, the average number of initiated flaws after the 10,000 trials in the Monte Carlo simulation is four, as listed in the table below:
a, b,                                Axial ODSCC at TTS Summary for 50% Exam at EOC 26 c            Outage          EOC25      EOC26      EOC27      EOC28      EOC29      EOC30        EOC31 Plant EFPY          23.41      24.71      26.13      27.40      28.83      30.16        31.36 Model EFPY            4.2        5.5        6.92      8.19      9.62      11.02        12.52 Cumulative Initiated      1          2          2          3          3          4            5 Exam Scope            Skip        50%        Skip      Skip      Skip        Skip        100%
Number Detected          0        NDD          0          0          0          0            1 The relevant inputs to the OA model are provided below:
Input File Name:                                              TP3_AxOD_TTS_1stinit_EOC25_Case1_OA Weibull slope, characteristic life and susceptible population size:                      1.5, 40 EFPY, 30 Normal Operating Condition Pressure Differential:                                                1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                        1.5, 0.65, 19%/EFPY Probe Type and POD Parameters:                                                        +PT; 17.72, 11.41 Probability of burst at EOC 31 is 0.25% for this tube group. Probability of leakage exceeding the AILPC is 0.23% for the mechanism.
For the 50% tube examination at EOC 28, the same approach is followed where at least one indication initiates in the operating period prior to EOC 28 and is not detected by XProbe at EOC28 inspection. At EOC 28, the average number of initiated flaws after the 10,000 trials in the Monte Carlo simulation is AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                    Page 53
 
two, and at EOC 31, there are 3 SCC flaws in service with 1 being detected by XProbe. The operating trend is shown in the table below:
a, b, c Axial ODSCC - Summary 50% Exam at EOC 28 Outage              EOC 27      EOC 28 EOC 29    EOC 30      EOC 31 Plant EFPY            26.13        27.40  28.83    30.16        31.36 Model EFPY              3.0        4.27    5.7      7.1          8.6 Cumulative Initiated          1            1      2        3            3 Exam Scope*              Skip        50%    Skip      Skip        TBD Number Detected              0          NDD      0        0            1
                  *Note: Exam is 100% of the sampled tubes.
For the 50% tube population inspected at EOC 28, the relevant inputs to the probabilistic OA model are provided below:
Input File Name:                                          TP3_AxOD_TTS_1stinit_EOC27_Case2_OA Weibull slope, characteristic life and susceptible population size:                  1.5, 45 EFPY, 30 Normal Operating Condition Pressure Differential:                                            1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                      1.5, 0.65, 19%/EFPY Probe Type and POD Parameters:                                                      XProbe; 2.9, 3.5 The probability of burst at EOC 31 for this group of tubes is 0.01%. The probability of leakage exceeding the AILPC is 0.01% for this mechanism.
The total probability of burst for this mechanism for comparing with the performance standard of 5% is calculated using a Boolean summation of the two probabilities, POB = 1(10.0025)(10.0001) = 0.26%
The total POB for this mechanism satisfies the SIPC margin requirement performance standard.
6.5      PWSCC at TTS Expansion Transitions a,  6.5.1 Axial PWSCC at TTS Expansion Transition b,  It has been shown that PWSCC growth rates are bounded by ODSCC growth rates and that the c    developed axial ODSCC growth rates are bounded by the EPRI IAGL typical default curve [13]. Axial PWSCC reported lengths are bounded by the Axial SCC length distribution provided by Figure 61.
Therefore, as the axial ODSCC at TTS OA shows probability of burst and leakage are acceptable, the axial PWSCC OA will also therefore be acceptable.
6.5.2 Circumferential PWSCC at TTS Expansion Transition:
It has been shown that PWSCC growth rates are bounded by ODSCC growth rates and that the developed circumferential ODSCC growth rates are bounded by the IAGL typical default curve [13]. Axial and circumferential PWSCC reported lengths are bounded by the axial and circumferential ODSCC length AIM 2003107742Q1 (NP), Rev. 1                        NON-PROPRIETARY                              Page 54
 
a,    distribution. Therefore, as the axial and circumferential ODSCC at TTS OA shows probability of burst and b,    leakage are acceptable, the axial and circumferential PWSCC OAs will also therefore be acceptable.
c 6.6 Axial ODSCC at TSP Intersections The tube population affected by ODSCC at TSP includes normal nonresidual stress tubes and those tubes that have been identified as having high residual stresses from fabrication [19]. All tubes at TSP intersections have received 100% Bobbin coil examination. In addition, the 77 signature and 2sigma tubes received a 25% sample inspection by +PointTM at EOC 28. The SG with the largest number of high residual stress tubes is S/G 3B with 38 identified tubes. In this assessment, two key assumptions are made:
: 1) The atrisk population was conservatively assumed to cover all hotleg tube intersections in the 38 tubes, a total of 275 locations. This number of possible initiations adds sufficient margin to cover the possibility that some high residual stress tubes may have been missed during the screening of earlier bobbin data for candidates.
: 2) No direct credit is taken for the +PointTM examination since it is a small sample. The OA conservatively relies on the 100% Bobbin examination for predicting the tube integrity condition at EOC 31. The performance of the bobbin POD is not as good as the +PointTM as shown in Figure 42, particularly in the upper tail (deeper depths).
The OA model used considers two different initiation functions to model two possible predicted behaviors. Based on the performance of the other units with this mechanism, the initiation most resembles an acute initiation model which initiates some discrete number of indications within a short operating period. These indications then grow and eventually are detected. At some point(s) in the future, another acute initiation event is experienced. However, since the lead plant analysis would have predicted indications long ago at PTN3, the initiation may not follow an acute initiation model and could be described by a low slope Weibull model. Therefore, two initiation models were evaluated, one with rapid initiation of SCC in a cluster, and the second having a gradual evolution of SCC over a time as observed with other SCC mechanisms.
In the acute model, four indications are assumed to initiate within a very short operating window. This value is selected based on the observation that excluding the Plant B experience, no other high residual stress tube SCC event involved more than 4 tubes. Since this mechanism has not been reported at PTN 3, the model is setup as a relative model. That is, the EFPY values in the model are relative to the a,
b current plant accumulated EFPY. In the model the first initiation occurs at approximately 5.7 EFPY and the characteristic life is selected as 6 EFPY, thus 2.5 indications are initiated at this point. The 6 EFPY model input represents the EOC27 outage. The EOC28 outage is represented as 7.4 EFPY in the model.
In the low slope model, 1 predicted initiate is present at the EOC 28 inspection and 3 initiates are present at the EOC 31 inspection.
As mentioned earlier, a 25% +PointTM inspection of high residual stress tube TSP intersections was performed at EOC 28 in addition to 100% bobbin coil inspection. The supplemental +Point inspection was conservatively neglected in the model.
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The structural average depth growth rate applied in both models is the upper bound default growth value; this function has a Lognormal mean of 1.95 and standard deviation of 0.65. This growth rate is judged conservative for this mechanism.
The applied bobbin probe POD is taken from [13]. This POD curve was conservatively adjusted such that the depth associated with a POD of 0.33 is 40%TW. This POD curve is conservative compared to the the ETSS I28413 POD curve. Due to the manner in which the models were developed, the POD curve has little impact on the predicted probability of burst, only the number of detected indications at the EOC 31 inspection. Figure 62 presents a plot of the ETSS I28413 POD curve and the POD curve used in this analysis.
a, The structural equivalent length distribution used is based on the combined Plant B and Plant C flaw b lengths. The combined length distribution was combined via a Monte Carlo simulation with the uniform distribution applied for axial ODSCC at the TTS.. This distribution adjusts the total flaw length to a structural equivalent length. The ratio of total to structural equivalent for all pulled tubes included in the development of the EPRI ETSS databases has a much larger upper bound value compared to the adjustment distribution thus the applied uniform distribution used to convert total length to structural equivalent length is conservative.
6.6.1    Acute Initiation Model The model predictions for number of initiated indications and Bobbin detections for the plant outages are shown in the table below.
a, b, c                  Axial ODSCC at TSPs - Summary 100% Bobbin at EOC 28 (Acute Case)
Outage            EOC 27    EOC 28      EOC 29    EOC 30        EOC 31 Plant EFPY          26.13      27.40      28.83      30.23          31.73 Model EFPY            5.8        7.07        8.5        9.9            11.6 Cumulative Initiated        1          4          4          4              4 Exam Scope            N/A      100%        N/A        N/A          100%
Number Detected            0        NDD          0          0              3 At EOC 31, the acute model predicts 3 indications will be detected out of the 4 that are inservice.
The relevant inputs to the OA model are provided below:
Input File Name:                                          TP3_AxOD_HS_TSP_Bobbin_Ext_UBGrowth Weibull slope, characteristic life and susceptible population size:                          25, 6 EFPY, 4 Normal Operating Condition Pressure Differential:                                                  1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                          1.95, 0.65, 28%/EFPY Model EFPY Equal to First Initiation, Equivalent PTN3 EFPY:                              5.8, 26.13 EFPY Probe Type and POD Parameters:                                                        Bobbin; 21.9, 13.3 At 11.6 EFPY, which conservatively represents the EOC 31 outage, the probability of burst is 3.25%,
which meets the performance standard of < 5% POB for the SIPC margin requirement of 3xNOPD. The probability of leakage exceeding the AILPC value is 1.13% for the mechanism.
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6.6.2    LowSlope Initiation Model The low slope model uses a Weibull slope of 1.5, characteristic life of 140 EFPY, and susceptible a, population size of 275 locations. PTN3 only has 77 identified high residual stress tubes, with 38 found b, in S/G 3B. All of the PTN3 high residual stress tubes are 2sigma tubes, i.e., identified in Rows 9 and c  higher. The susceptible population size represents all hot leg TSP and FBP intersections for 38 tubes and is judged conservative as previously described.
Axial ODSCC at TSPs - Summary 100% Bobbin at EOC 28 (Low Slope Case)
Outage            EOC 28      EOC 29        EOC 30        EOC 31 Plant EFPY            27.40      28.83        30.28        31.73 Model EFPY            4.00        5.38          6.83          8.25 Cumulative Initiated        2          3            4            5 Exam Scope            100%        N/A          N/A          100%
Number Detected          NDD          0            0            2 The relevant inputs to the OA model are provided below:
Input File Name:                                                    TP3_AxODSCC_TSP_EOC30_Case2A Weibull slope, characteristic life and susceptible population size:                    1.5, 140 EFPY, 275 Normal Operating Condition Pressure Differential:                                                1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                          1.95, 0.65, 28%/EFPY Model EFPY Equal to First Initiation, Equivalent PTN3 EFPY:                              3.3, 26.77 EFPY Probe Type and POD Parameters:                                                        Bobbin; 21.9, 13.3 At 8.25 EFPY, which represents the EOC 31 outage, the probability of burst is 2.6% which meets the performance standard of < 5% POB at the SIPC margin requirement of 3xNOPD. The probability of leakage exceeding the AILPC value is 2.4% at 1xLAPD. For this mechanism, the probabilities from the acute model and lowslope model do not require combination as each OA analysis case is solving the same mechanism under two separate set of assumptions.
6.7      Axial ODSCC at Dings and Dents Tube dings and dents in freespans, at Ubends, and at structures, have been tested in past outages with ECT in a sampling program involving Bobbin coil for dings/dent signals < 5 volts, and with the +PointTM for signal voltages > 5 volts. Each inspection outage, 50% sampling is conducted on the hotleg (HL) side for the > 5 volts population, and 100% for < 5 volt population. The primary focus of the examinations is to monitor for SCC on the hotleg where it is more likely for SCC to initiate first due to higher tube operating temperatures. Bobbin testing does cover both the hotleg and coldleg sides for those dings/dents where voltages are < 5v. Therefore, three OA models required are bobbin examination scope, and one each for the 50% sampled populations by +PointTM (EOC 26 and EOC 28) 6.7.1    Axial ODSCC at Hot/Cold Leg Dings  5 Volts If axial ODSCC initiated at the time estimated from other plant experience, those indications would have been detected at EOC 28, if the growth rate were described by the EPRI IAGL typical default curve. A AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                    Page 57
 
growth rate of LN mean of 1.20 with SD of 0.65 and maximum of 16% TW per EFPY is determined to produce a low probability of detection and if this growth rate were applied, that the probability of burst at EOC 31 is 2.31% and the probability of leakage exceeding the AILPC value is 0.26% assuming that initiation occurred at EOC 21 with no subsequent detections.
Given that the initiation analysis shows that indications would be detected at EOC 28 with initiation at EOC 21, the same methodology applied for other mechanisms that initiation occurs one cycle prior to the most recent 100% inspection, or at EOC 27. The structural equivalent length distribution is taken for the Plant D ding crack total length distribution and the same adjustment distribution as above. The evolution of the number of initiations is shown in the below table.
a, b, c            Axial ODSCC at Dings/Dents - Summary 100% Bobbin at EOC 28 (Case 2)
Outage          EOC28      EOC29      EOC30      EOC31 Plant EFPY          27.40      28.83        30.16      31.36 Model EFPY          3.99        5.42        6.80      8.25 Cumulative Initiated      4          6          8        10 Exam Scope          100%        Skip        Skip      100%
Number Detected          0          0          0          1 The relevant inputs to the OA model are provided below:
Input File Name:                                            TP3_AxODSCC_DingDent_3A_EOC30_Case2 Weibull slope, characteristic life and susceptible population size:                    1.5, 200 EFPY, 30 Normal Operating Condition Pressure Differential:                                              1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                          1.5, 0.65, 19%/EFPY Probe Type and POD Loglogistic Parameters:                                      Bobbin; 74.06, 41.31 At EOC 31, the probability of burst for the  5v population inspected at EOC 28 is 0.97% and the probability of leakage exceeding the AILPC is 0.48% for the mechanism.
6.7.2    Axial ODSCC at Hot Leg >5V Dings The 50% +PointTM examination was performed at EOC 26 and EOC 28 for all three SGs. Because of the long operating period from EOC 26 to EOC 31 (5 cycles), this group of tubes will be the most challenging on tube integrity. The number of hotleg dings/dents in S/G 3A is about 170 so each 50% sample contains about 85 dings/dents. The same crack growth rate used for the bobbin OA model was used, which is based on EPRI IAGL default lognormal distribution. The same length distribution from the Plant D ding crack data set was also used. For the inspection at EOC 28, the evolution of the number of initiations predicted by the model is shown in the below table.
a,b                    Axial ODSCC at Dings/Dents - Summary 50% +PT at EOC 28 (Case 1A)
Outage          EOC 28    EOC 29      EOC 30    EOC 31 Plant EFPY          27.40      28.83        30.16      31.36 Model EFPY          3.99        5.42        6.80      8.25 Cumulative Initiated      2          2          2          3 Exam Scope          100%        Skip        Skip      100%
Number Detected        NDD          0          0          1 AIM 2003107742Q1 (NP), Rev. 1                    NON-PROPRIETARY                                  Page 58
 
The relevant inputs to the OA model are provided below:
a,    Input File Name:                                          TP3_AxODSCC_DingDent_3A_EOC30_Case1A b,    Weibull slope, characteristic life and susceptible population size:                    1.5, 125 EFPY, 85 c      Normal Operating Condition Pressure Differential:                                                1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                          1.5, 0.65, 19%/EFPY Model EFPY Equal to First Initiation, Equivalent PTN3 EFPY:                              2.8, 25.6 EFPY Probe Type and POD Parameters:                                                          +PT; 66.7, 39.2 At EOC 31, the probability of burst for the >5v populations inspected at EOC 28 is 0.62% and the probability of leakage exceeding the AILPC is 0.37% for the mechanism.
The OA for the >5v dings/dents inspected at EOC 26 was evaluated as Case 1B. Except for the longer operating, the input parameters are similar as Case 1A. For the 5 cycles from the inspection at EOC 26, the evolution of the number of initiations predicted by the model is shown in the below table:
a,                      Axial ODSCC at Dings/Dents - Summary 50% +PT at EOC 26 (Case 1B) b,              Outage          EOC 26      EOC 27      EOC 28      EOC 29    EOC 30        EOC 31 c              Plant EFPY          26.13      27.40      28.83        30.23    31.73          26.13 Model EFPY            3.88        5.30        6.57        8.00      9.38          10.83 Cumulative Initiated        1          2          2          3          3            4 Exam Scope            50%        Skip        Skip        Skip      Skip          100%
Number Detected          NDD          0          0            0        0              1 The relevant inputs to the OA model are provided below:
Input File Name:                                          TP3_AxODSCC_DingDent_3A_EOC30_Case1B Weibull slope, characteristic life and susceptible population size:                    1.5, 100 EFPY, 85 Normal Operating Condition Pressure Differential:                                                1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                          1.5, 0.65, 19%/EFPY Probe Type and POD Parameters:                                                          +PT; 66.7, 39.2 At EOC 31 the probability of burst is 1.16% and the probability of leakage exceeding the AILPC is 0.54%
for the mechanism.
For the three submodels, the total POB and POL from a Boolean combination are:
POB = 1(10.0116)(10.0062)(10.0097) = 2.73%
POL = 1(10.0048)*(10.0037)*(10.0054) = 1.38%
The total POB for this mechanism satisfies the SIPC margin requirement performance standard of 5%.
The POL is also  5%.
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6.7.3    Axial ODSCC at Cold Leg Dents > 5 Volts Dings and dents on the cold leg side are not examined in the sample scopes of past inspections.
Although it is not expected that SCC will first develop in the colleg side, there is a risk that small SCC flaws exit in the upper top TSPs (05C and 06C). This risk is evaluated as a check on any adverse effects to the burst and leakage probabilities.
The OA model to evaluate this condition is based solely on projected performance of the tubing as no inspection data are available for cold leg dents >5V. The temperature at the top cold leg TSP is estimated at 565oF. The associated temperature adjustment factor between the Plant B top hot leg TSP and PTN3 top cold leg TSP is 1.70 resulting in an equivalent first initiation of 21.1 EFPY.
At PTN3, 21.1 EFPY is approximately equal to EOC 23 (20.83 EFPY). For a temperature of 565oF, the temperature adjusted EPRI IAGL typical default growth rate would have a Lognormal mean value of 0.41. In this analysis, a conservative value of 1.0 for the Lognormal mean will be used with standard deviation of 0.65, and maximum value of 12%/EFPY. The first initiation point is conservatively taken at EOC 23, or 20.83 EFPY.
There are 1711 cold leg dents >5v. The relevant inputs to the OA model are provided below:
a,    Input File Name:                                              TP3_AxOD_DNGDNT_ColdLeg_GT5V_OA b,    Weibull slope, characteristic life and susceptible population size:                  1.5, 200 EFPY, 1700 c      Normal Operating Condition Pressure Differential:                                                1460 psi LogNormal Structural Average Growth Mean, SD, and maximum:                            1.0, 0.65, 12%/EFPY Model EFPY Equal to First Initiation, Equivalent PTN3 EFPY:                                2.8, 21.1 EFPY Probe Type and POD Parameters:                                                      Bobbin; 74.06, 41.31 The probability of burst at EOC 31 is 0.11% and the probability of leakage exceeding the AILPC is zero.
Therefore, the risk is low that SCC on the coldleg side would cause a significant increase in the burst probabilities or in the leakage potential for this degradation mechanism.
6.8 Other Mechanisms a, b The two other potential mechanisms listed in the DA are axial ODSCC in freespan regions and PWSCC in small radius Ubends. Both degradation mechanisms have not been observed in 600TT plants except when stress risers are present. Due to limited experience and operating data for these mechanisms, it is assumed that they will be conservatively bounded by the results of the OA case for ODSCC at TSPs.
Therefore, the tube integrity for these mechanisms will be maintained during the extended interval.
6.9 Summary of Operational Assessment Results for Potential Mechanisms The OA for the potential mechanisms identified for PTN3 SG tubing has been completed to support deferring the EOC 30 inspections by one operating cycle. The OA evaluated all potential corrosion degradation mechanisms in under the assumption that they are active following the last inspection at EOC 28. The results for probability of burst, leakage, calculated leak rates under the postulated limiting accident conditions are summarized in Table 61.
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The calculated probability of burst for all evaluated mechanisms satisfy the SIPC margin requirement of 3xNOPD for three cycle operating period through to EOC 31. The cumulative accidentinduced leakage is determined by summing the projected leak rates at EOC 31. It would not be credible to assume that all potential mechanisms would be active in one operating period. Plants who have observed multiple corrosion degradation mechanism is limited to two or at most three mechanism existing in a single period. Assuming three limiting mechanisms become active in one SG (i.e., axial ODSCC at TSPs, circumferential ODSCC at TTS, and axial ODSCC at dings/dents), the cumulative leak rate is determined to be 0.11 gpm. This leakage value is less than the AILPC leak limit of 0.2 gpm for any one SG. Therefore, both tube structural integrity and leakage performance meets the requirements of NEI 9706 and the PTN3 Technical Specifications, under the very conservative condition that all potential mechanisms are evaluated as existing.
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Table 61 Summary of OA Results for Limiting Potential Mechanisms Probability of Leakage Exceeding          Calculated Probe                              Probability of        AccidentInduced      95/50 Leakage Mechanism                        Model Case            Type            Exam Slope              Burst                Leak Limit              (gpm)
                                                                      +PT (EOC 26)                                                                              0.051 Circ ODSCC at TTS Expansion Transitions            Generic                                  50%              3.19%                  <0.28%
XProbe (EOC 28)                                                                          [Note 3]
                                                                      +PT (EOC 26)
Axial ODSCC at TTS Expansion Transitions            Generic                                  50%              0.26%                    0.24%                0.0005 XProbe (EOC 28)
Bounding          +PT (EOC 26)
Circ PWSCC at TTS Expansion Transitions                                                      50%              <3.19%                  <0.14%                <0.051
[Note 1]      XProbe (EOC 28)
Bounding          +PT (EOC 26)
Axial PWSCC at TTS Expansion Transitions                                                      50%              <0.26%                  <0.24%                    ~0
[Note 1        XProbe (EOC 28)
Axial ODSCC at TSP including High                    Acute                                                      3.25%                    1.13%                0.0099 Bobbin              100%
Residual Stress Tubes                              LowSlope                                                    2.60%                    2.4%                  0.059 Bobbin (<= 5v)          100%
Axial ODSCC at Tube Dings/Dents                      S/G 3A                                                    2.73%                    1.38%                0.0004
                                                                      +PT (>5v HL)            50%
Bounding Axial ODSCC at Freespans                                                Bobbin              100%                <2.6%                  <1.13%                <0.0099
[Note 2]
Bounding PWSCC in Small Radius UBends                                            +PT                50%                <2.6%                  <1.13%                <0.0099
[Note 2]
Notes:
: 1)  PWSCC at TTS is bounded by ODSCC at TTS cases
: 2)  SCC at freespans has not been observed in A600TT plants except when stress risers are present. The OA case for ODSCC at TSPs is used to bound tube integrity condition for these mechanisms.
: 3)  Leak rate analysis based on EPRI methodology in [9]
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a, b, c Figure 61: Length Distributions of All Axial SCC Flaws for the A600TT Fleet AIM 2003107742Q1 (NP), Rev. 1                  NON-PROPRIETARY                          Page 63
 
a, c                                        Bobbin POD Functions for Axial ODSCC at Tube Suport Plates 1.0 0.9 0.8 0.7 Probability of Detection 0.6 0.5 0.4 0.3 0.2 ETSS I28413 0.1 Applied Curve 0.0 0  10      20    30      40      50      60    70      80        90    100 Depth, (%TW)
Figure 62: Axial ODSCC Bobbin Coil POD Curves AIM 2003107742Q1 (NP), Rev. 1                                          NON-PROPRIETARY                                Page 64
 
7 l Summary and Conclusions Turkey Point Unit 3 is preparing a onetime license amendment request to allow the plant to defer the TP331 steam generators tube examinations to the next schedule outage in October 2021. In support of the LAR, the PTN3 EOC 28 OA was reevaluated to provide the technical basis for skipping the spring 2020 SG inspections. The OA conservatively evaluated the potential corrosion degradation mechanisms as being active in addition to the existing mechanical wear at tube supports and flow distribution baffle plates, and all known or postulated foreign objects in the SG secondary side.
The following conclusions were drawn from the revised OA:
: 1) The results from the revised OA fully support the skipping of the EOC 30 inspection.
: 2) Structural integrity performance criterion margin requirement of three times normal operating pressure (3xNOPD) on tube burst will be satisfied at EOC 31 for the existing and potential degradation,
: 3) Accidentinduced leakage performance criteria for the limiting accident condition will be satisfied for the cumulative leakage requirement for any one SG and for all three SGs for operating period to EOC 31.
Therefore, given the examination scope implemented at EOC 28, all structural and accident leakage performance criteria in NEI 9706 are predicted to be met through the end of Cycle 31 for the existing and potential degradation mechanisms.
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8 l References
[1]  Steam Generator Program Guidelines, Nuclear Energy Institute, NEI 9706, Revision 3 (January 2011).
[2]  Steam Generator Management Program: Steam Generator Integrity Assessment Guidelines, Revision 4, EPRI 3002007571 Electric Power Research Institute, (June 2016).
[3]  Condition Monitoring and Operational Assessment for Turkey Point Unit 3 Steam Generators Based on Turkey Point Eddy Current Examination Results for End of Cycle 28, March 2017, Intertek AIM Report AIM 1602101842Q3, (June 2017).
[4]  Degradation Assessment for Turkey Point Unit 3 and Turkey Point Unit 4 Steam Generators, Update for the Turkey Point Unit 3 EndofCycle 28 Refueling Outage (March 2017), Intertek AIM Report AIM 16101015121 Revision 1, (March 2017)
[5]  Email from K. Thompson (FPL) to R. Cipolla (Intertek AIM), PTN3 QA regarding primary secondary Leakage during Cycle 30, (3/28/2020)
[6]  Structural Limit Evaluation for Steam Generator Tube Degradation at Turkey Point and St. Lucie Nuclear Plants, Intertek AIM, Report AIM 150588682Q1 (November 2016)
[7]  Steam Generator Management Program: Steam Generator In Situ Pressure Testing Guidelines, Revision 5, EPRI 3002007856 (November 2016)
[8]  Steam Generator Management Program: Steam Generator Degradation Specific Management Flaw Handbook, Revision 2, EPRI 3002005426, Electric Power Research Institute, Final Report (August 2015)
[9]  Depth Based Structural Analysis Methods for Steam Generator Circumferential Indications, Report TR 107197 P1, Electric Power Research Institute, (November 1997)
[10] Users Manual for OPCON 3.03  Operational Assessment and Condition Monitoring of Steam Generator Tubes, Aptech Engineering Services, Inc., (2007)
[11] EPRI Examination Technique Specification Sheets, EPRIq database.
[12] Email from K. Thompson (FPL) to R. Cipolla (Intertek AIM), Cycles 29, 30, 31 EFPY, (3/29/2020)
[13] Feasibility Study for the Potential to Extend Inspection Intervals for A600TT Fleet, Intertek Report AIM19061063621, Rev. 0, Electric Power Research Institute 10011093, (December 2019).
[14] Degradation Growth Rates for the St. Lucie Units 1 and 2, and Turkey Point Units 3 and 4 Steam Generators, Intertek AIM, Report AIM 150588682Q2 (October 2016)
[15] CR 1871783, Unit 3B Steam Generator Feedwater Flow and Pressure Transient While at 100%
Power, Turkey Point Nuclear Units 3 & 4 Root Cause Analysis, NEXTera Energy, (12/2/2013).
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[16] Debris Impact on SG Tube Integrity (Revised), Revised Calculation for SG Wear Rate IAW WCAP 14258, Rev. 3, FPL, (7/17/2014).
[17] Florida Power & Light Co., Turkey Point Unit 3, 10 CFR50.59 Evaluation for Unit 3 Steam Generators' Secondary Side, Foreign Objects, FPL JPNPTNSEMS96038
[18] WCAP17091P, H*: Alternate Repair Criteria for the Tubesheet Expansion Region in Steam Generators with Hydraulically Expanded Tubes (Model 44F), (June 2009) FPL Reference PTNENG SESJ09016 Engineering Evaluation Request for H*: Alternate Repair Criteria for Steam Generator Tubesheet Expansion Region.
[19] Screening for High Residual Stress Condition Tubes PTN Unit 4, AREVA Report 515035368001, (October 22, 2009)
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Turkey Point Nuclear Plant                    L-2020-064 Enclosure 3 Docket No. 50-250 Intertek Affidavit
 
1ntertek Total Quality. Assured.
lntertek AIM 3510 Bassett Street Santa Clara, CA 95054 Tel +1408.745.7000 Fax +1408.734.0445 lntertek.com/aim/englneering USA AFFIDAVIT for AIM 200310774-2Q-1 State of California, County of Santa Clara:
(1) I, Michael T. Cronin, have been specifically delegated and authorized to apply for withholding and execute this Affidavit on behalf of lntertek USA, Inc. dba lntertek AIM (lntertek).
(2) I am requesting the proprietary portions of lntertek report AIM 200310774-2Q-1 be withheld from public disclosure under 10 CFR 2.390(a)(4), and for the following reasons to be considered pursuant to 10 CFR 2.390(b)(4).
(3) In making this application for withholding of proprietary and confidential information, I have personal knowledge of the engineering practices and procedures utilized by lntertek, and the ability in designating specific information and data that are considered trade secrets, privileged, confidential, commercial, or financial information.
(4) Pursuant to 10 CFR 2.390, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld.
: a. The information sought to be withheld from public disclosure is owned and has been held in confidence by lntertek and is not customarily disclosed to the public.
: b. Public disclosure of this proprietary information is likely to cause substantial harm to the competitive position of lntertek because it would enhance the ability of competitors to provide similar technical evaluation justifications and licensing defense services for commercial power reactors without commensurate expenses. Also, public disclosure of the information would enable others to use the information to meet NRC requirements for licensing documentation without purchasing the right to use the information.
: c. The information sought to be withheld from public disclosure has been provided to lntertek under a license and/or non-disclosure agreement by a third party and may not be customarily disclosed unless the third party waives its rights to the information.
(5) lntertek does not publically release or disclose proprietary or confidential information in the course of business. Information is held in confidence if the release of which might result in the loss of an existing or potential competitive advantage, or discloses client proprietary information, as listed below:
: a. The information reveals details of proprietary practices or procedures used by lntertek to include analytical methods or processes, where its disclosure to any of lntertek's competitors without license from lntertek will be harmful to lntertek's business.
AWPl-10774-1                                                                                            Page 1 of 2
 
@                                    AFFIDAVIT for AIM 200310774-2Q-1
: b. It consists of supporting data, including test data, relative to an analytical procedure or process, the use of such would give lntertek's competitors an economic advantage.
: c. It reveals procedures, methods, or data which are proprietary to a third party, for which lntertek is obligated to protect.
: d. Its use by a competitor would reduce that competitor's expenditure of resources or improve that competitor's competitive position.
: e. It contains patentable methods for which patent protection may be desirable.
: f. It reveals cost or price information, production capacities, budget levels, or commercial strategies of lntertek, its customers, or its suppliers.
: g. It reveals aspects of past, present, or future lntertek or customer funded development plans and programs of potential commercial value to lntertek.
(6) The attached document is bracketed and marked to indicate the bases for withholding. The justification for withholding is indicated by means of lower case letters (a) through (g) located in the upper left corner within the bracketed area enclosing each item of information being identified as proprietary. These lower-case letters refer to the types of information lntertek customarily holds in confidence identified in Sections (S)(a) through (g) of this Affidavit.
I declare that the affirmations set forth in this Affidavit are true and correct to the best of my knowledge, information, and belief.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on:
Director of Engineering AWPl-10774-1                                                                                        Page 2 of 2


JURAT A notary public or other officer completing this certificate verifies only the identity of the individual who signed the document to which this certificate is attached, and not the truthfulness, accuracy, or validity of that document.
Turkey Point Nuclear Plant                                                              L-2020-069 Docket No. 50-250                                                                        Attachment Page 3 of 3 Discuss how the POD affects the size of the assumed missed indications during the EOC-28 inspection and why the POD has little impact on probability of burst.
State of California County of              Sa.,r,ta Gl~Ct Subscribed and sworn to (or affirmed) before me on this                                  5 th day ot_A_,p~r_;_(___.
FPL Response:
20J.O              by      ~fehad Thr, rl\.ru C.X--o n~ n proved to me on the basis of satisfadory evidence to be the personOO who appeared before me.
In general, when tubes are removed from service based on plug-on detection, the number and size of missed indications will be dependent to the POD. The software algorithm has the ability to model the complete flaw initiation, flaw growth and detection process at any point in time. The manner in which the models were constructed is to force the model to ignore potential detections at the most recent inspection thus allowing all initiated and grown flaws to remain in service. Based on the manner that the models were developed (forced non-detection at most recent inspection), the statement that the POD has little effect on the probability of burst is accurate. Because the EOC 28 population which remains in service at the start of Cycle 29 is composed of both the undetected and what was detected in the model but not removed from service (i.e., repair limit = 100%TW), the POD does not affect the BOC 29 population. This model setup scheme was intentional to assure that a conservative distribution of the number and size of indications are present in the SG at the start of the 3-cycle operating period.
    )l.;JJA._~
: 3. Address whether the discrepancies identified in Reference 6.3 of the submittal discussed below result in any impacts on the analysis results:
l.Signature                                              (SeaQ OPTIONAL INFORMATION                                                              INSTRUCTIONS The wonJing of a6 Jurats corrpleted ii Ca6fomi8 lift.er Jtmary 1, 2015 nll8l be in the foon as set forth within this Jurat. 1hel9 am no exceptioos. If a Jurat to be COllf)leted does nat follow this form, the oota,y l1IJSt oonect the verbiage by using ajJnd stamp CtJflfainklg the cofT&ct wording or allsching a separal& jsat roan such as this one with ooea contsin the proper wmiilg. /n addilion, the notary nllSl requ/t& 8ll odJ OI alfimBlion ffl the DESCRIPTION OF THE ATTACHED DOCUMENT                    document signer regarding the truthWless ri the rontents of the docurrent. The document must be signed AFTER the 08lh or dmalloo. If the doamlent was p,eviously signed, ii must be ,e-signed ii front of the nata,y pubic during the jJl'lt process.
: a. Page 53 - The third paragraph under Section 6.4 refers to four crack initiations at EOC-25 and four crack initiations at EOC-26; however, the table immediately below this paragraph shows one and two initiates for EOC-25 and EOC-26, respectively; and, FPL Response:
(Trlle or description of attached document)
The value in the table immediately below the third paragraph provides the correct result of 2 initiations. The value of four in the text is a typographical error.
* State and county information must be the state and county where the document signer(s) personally appeared before the notary public.
: b. Page 53 - The last paragraph on the page refers to an average of two crack initiations at EOC-28; however, the table immediately below (top of page 54) shows one crack initiation for EOC-28.
(Tille or desaiplion of attached document ainlilued}
FPL Response:
* Date of notarization must be the date the signer(s) personally appeared which must also be the same date the jurat process is completed.
Being a probabilistic analysis, either result is plausible due to most inputs being statistical. After reviewing the analysis case including running the problem case again, two cumulative initiations is the proper value and the associated probability of burst is approximately 0.07% for this case.}}
Number of Pages __ Document Date._ _ __
* Print the name(s) of the* document signer(s) who personally appear at the time of notarization.
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* The notary seal Impression must be clear and photographically reproducible. Impression must not cover text or lines. If seal impression smudges, re-seal if a sufficient area permits, otherwise complete a different jurat form.
                                                                                  +    Additional information Is not required but could help to ensure this jurat is not misused or attached to a different document.
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Revision as of 04:15, 12 May 2020

Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information
ML20100G832
Person / Time
Site: Turkey Point NextEra Energy icon.png
Issue date: 04/09/2020
From: Stamp B
Florida Power & Light Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2020-064
Download: ML20100G832 (6)
v • d • e


Text

April 9, 2020 L-2020-064 10 CFR 50.90 10 CFR 50.91 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington DC 20555-0001 RE: Turkey Point Nuclear Plant, Unit 3 Docket No. 50-250 Renewed Facility Operating License DPR-31 Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information

References:

1. Florida Power & Light Company Letter L-2020-053, Exigent License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program," dated April 4, 2020,

[M L20095J926].

2. Florida Power & Light Company Letter L-2020-064, License Amendment Request 272, One-Time Extension of TS 6.8.4 Steam Generator Inspection Program - Response to Request for Additional Information" dated April 7, 2020, [ML20098F341, ML20098F342J.
3. NRG email "Turkey Point Unit 3 - Request for Additional Information Concerning Deferral of Steam Generator lnservice Inspections (EPID L-2020-LLA-0067)" dated April 9, 2020.

Per Reference 1, Florida Power & Light Company (FPL) requested an exigent amendment to Renewed Facility Operating License DPR-31 for Turkey Point Nuclear Plant Unit 3 pursuant to 10 CFR Part 50.90 and 10 CFR Part 50.91 (a)(6).

On April 4, 2020, the NRG Staff requested supplemental information to facilitate review of the requested amendment. Per Reference 2, FPL provided the response to the request for additional information.

On April 8, 2020, NRC requested additional information needed to facilitate review of the requested amendment (Reference 3). The attachment to this letter provides the response to the requested information.

The information provided in this letter does not alter the no significant hazards determination previously provided by the original application per FPL letter L-2020-053.

Should you have any questions regarding this submittal, please contact Mr. Robert Hess, Turkey Point Licensing Manager, at (305) 246-4112.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on April 9, 2020.

Sincerely,

£
~~

BrirulStamp Site Dlrector Turkey Pornt Nuclear Plant Florida Power & Light Company Florida Power & Light Company

Turkey Point Nuclear Plant L-2020-069 Docket No. 50-250 Page 2 of 2 Attachment - Response to Request for Additional Information cc: USNRC Regional Administrator, Region II USNRC Project Manager, Turkey Point Nuclear Plant USNRC Senior Resident Inspector, Turkey Point Nuclear Plant Ms. Cindy Becker, Florida Department of Health

Turkey Point Nuclear Plant L-2020-069 Docket No. 50-250 Attachment Attachment to L-2020-069 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION

Turkey Point Nuclear Plant L-2020-069 Docket No. 50-250 Attachment Page 1 of 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION CONCERNING DEFERRAL OF STEAM GENERATOR INSERVICE INSPECTION FLORIDA POWER & LIGHT COMPANY TURKEY POINT NUCLEAR GENERATING UNIT NO. 3 DOCKET NO. 50-250

1. Enclosure 2 of the supplement (operational assessment or OA) dated April 7, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20098F341) describes the SG OA for the additional requested cycle before SG inspection. Page 25 of the OA outlines the probabilistic model used to evaluate potential mechanisms such as stress corrosion cracking. The OA states:

A time-to-flaw-initiation (Weibull) function is applied. The physical processes of flaw initiation, flaw growth and simulated inspections (via use of a POD [probability of detection] function) are modeled for several past and future cycles. Benchmarking of results to the observed information obtained from past inspections provides assurance of the accuracy of predictions over the operating interval to the next inspection.

and it is conservative assume[sic] to assume for the BOC [beginning of cycle] distribution of flaws following the last inspection that at least one SCC [stress corrosion cracking] indication had initiation sometime in the previous operating period and that the initiated indication(s) where not reported. As a general figure of merit, the size of the missed indications will be on the order of the no smaller than 5% POD value for the ECT [eddy current testing] technique used in the previous inspection. This assures a reasonable conservative starting population for the simulation.

For the cracking mechanisms analyzed in the OA, please clarify:

a. the details of how the missed indication size distribution is selected from the appropriate POD curve including any limits placed on the missed indication size; and FPL Response:

The distribution of sizes of missed indications following the most recent examination is not selected but is generated in the Monte Carlo simulation that replicates the inspection process. Figure 3-4 in the operational assessment shows the Monte Carlo simulation flowchart, where the application of the Weibull initiation, lognormal growth, and the POD models establishes the BOC indication sizes.

Turkey Point Nuclear Plant L-2020-069 Docket No. 50-250 Attachment Page 2 of 3 For the most recent inspection where no corrosion degradation was observed, it is assumed that at least one crack initiates during the operating period prior to the inspection, and at least two crack initiations are present at the time of the inspection and are not reported during the inspection. This is achieved by adjusting the Weibull model to set the time for first initiation in the prior cycle. Cracks initiated in the prior cycle are allowed to grow using the EPRI default growth rate distribution. As another conservative measure, any cracks that are detected in the simulation are not removed from service but are included in the BOC of missed indications.

The BOC size distribution of indications from the analysis is checked to confirm that median depth of the simulated sizes exceeds the lower 5%

POD performance level. In addition, the 95th percentile of the BOC distribution is reviewed for reasonability against the POD curve. This assures the BOC simulated sizes will not be too small such that the analysis is not effective as a measure of performance and not overly adverse such that the analysis unduly predicts failure. This BOC distribution conservatively envelops any actual flaws that may exist under the condition that the mechanism is existing but not observed at the previous inspection.

b. how the assumed initiated flaws were benchmarked to missed or detected cracks from plant operating experience.

FPL Response:

For the mechanisms judged most challenging to the establishment of satisfaction of the performance criteria at EOC 31, the upper 95th percentile of developed non-detected depths are consistent with observed plant performance from historical look back reviews of indications observed in the outage during which indications were detected. These depths are judged to be conservative compared to the mean probe performance. The parameters for the Weibull initiation function used in the OA were developed from past operating experience of plants that have a history of cracking and form the basis on how each mechanism will evolve over time following first initiation.

2. In Section 6.6 of the OA, which discusses axial outside diameter stress corrosion cracking at tube support plates, there is a discussion regarding how the analysis conservatively adjusted the POD curve. The discussion states:

[d]ue to the manner in which the models were constructed, the POD curve has little impact on the probability of burst, only the number of indications detected at EOC-31 [end of cycle 31].

Turkey Point Nuclear Plant L-2020-069 Docket No. 50-250 Attachment Page 3 of 3 Discuss how the POD affects the size of the assumed missed indications during the EOC-28 inspection and why the POD has little impact on probability of burst.

FPL Response:

In general, when tubes are removed from service based on plug-on detection, the number and size of missed indications will be dependent to the POD. The software algorithm has the ability to model the complete flaw initiation, flaw growth and detection process at any point in time. The manner in which the models were constructed is to force the model to ignore potential detections at the most recent inspection thus allowing all initiated and grown flaws to remain in service. Based on the manner that the models were developed (forced non-detection at most recent inspection), the statement that the POD has little effect on the probability of burst is accurate. Because the EOC 28 population which remains in service at the start of Cycle 29 is composed of both the undetected and what was detected in the model but not removed from service (i.e., repair limit = 100%TW), the POD does not affect the BOC 29 population. This model setup scheme was intentional to assure that a conservative distribution of the number and size of indications are present in the SG at the start of the 3-cycle operating period.

3. Address whether the discrepancies identified in Reference 6.3 of the submittal discussed below result in any impacts on the analysis results:
a. Page 53 - The third paragraph under Section 6.4 refers to four crack initiations at EOC-25 and four crack initiations at EOC-26; however, the table immediately below this paragraph shows one and two initiates for EOC-25 and EOC-26, respectively; and, FPL Response:

The value in the table immediately below the third paragraph provides the correct result of 2 initiations. The value of four in the text is a typographical error.

b. Page 53 - The last paragraph on the page refers to an average of two crack initiations at EOC-28; however, the table immediately below (top of page 54) shows one crack initiation for EOC-28.

FPL Response:

Being a probabilistic analysis, either result is plausible due to most inputs being statistical. After reviewing the analysis case including running the problem case again, two cumulative initiations is the proper value and the associated probability of burst is approximately 0.07% for this case.

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