ML110660648

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February 16, 2011, Summary of Meeting with Southern Nuclear Operating Company, Inc., and Westinghouse on Technical Issues Regarding Steam Generator Tube Inspection Permanent Alternative Repair Criteria
ML110660648
Person / Time
Site: Vogtle  Southern Nuclear icon.png
Issue date: 03/28/2011
From: Patrick Boyle
Plant Licensing Branch II
To:
Boyle, Patrick, NRR/DORL/LPL2-1/415-3936
References
TAC ME5417, TAC ME5418
Download: ML110660648 (51)
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Text

\\.t.",R REG uZq UNITED STATES

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NUCLEAR REGULATORY COMMISSION

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WASHINGTON, D.C. 20555-0001

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0 March 28, 2011

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Southern Nuclear Operating Company, Inc.

FACILITY:

Vogtle Electric Generating Plant, Units 1 and 2

SUBJECT:

SUMMARY

OF FEBRUARY 16, 2011, MEETING WITH SOUTHERN NUCLEAR OPERATING COMPANY, INC., AND WESTINGHOUSE ON TECHNICAL ISSUES REGARDING STEAM GENERATOR TUBE INSPECTION PERMANENT ALTERNATE REPAIR CRITERIA (TAC NOS. ME5417 AND ME5418)

On February 16, 2011, a Category 1 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) staff and representatives of Southern Nuclear Operating Company, Inc. (SNC, the licensee), and Westinghouse Electric Company (Westinghouse) at NRC Headquarters, One White Flint North Building, Room 7 B 6, 11555 Rockville Pike, Rockville, Maryland. SNC is the technical lead for multiple licensees and requested the public meeting to discuss the analysis, results, and submittal plan for the anticipated license amendment requests for steam generator (SG) tube permanent alternate repair criteria (PARC) to support the refueling outages beginning in 2012. A list of attendees is provided as.

The industry presented information (see Enclosure 2) describing the ongoing analytical work associated with the H* analysis in support of the planned PARCo This included a presentation by Westinghouse outlining their response to the questions raised during the August 24, 2010, public meeting. The industry stated that they have contracted for an independent review of the H* methodology, with an outside consultant. The industry agreed to share the results/impacts of this review with the NRC upon its conclusion.

The NRC staff shared its initial thoughts on WCAP-17330 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML103410453) and WCAP-17345 (ADAMS Accession No. ML110240266). The !\\IRC also shared its thoughts on the related information presented at this public meeting. The questions raised by the NRC staff as a result of the review of the WCAP and the discussion at the public meeting are provided as Enclosure 3.

The NRC staff stated that the current review efforts are focused on the submitted license amendments for the temporary alternate repair criteria required for the spring and fall 2011 refueling outages. Once those safety evaluations are completed, attention will be redirected to the Westinghouse documents submitted in support of any PARC license amendment applications.

SNC

- 2 Members of the public representing other utilities and industry groups were in attendance.

Public Meeting Feedback forms were available at the meeting but no comments were received.

Please direct any inquiries to me at 301-415-3936.

Patrick G. Boyle, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-424 and 50-425

Enclosures:

1. List of Attendees
2. Licensee's Presentation, "lndustry/NRCJWestinghouse Public Meeting on Steam Generator H* Issues," IndustryJWestinghouse Presentation, February 16, 2011
3. Technical Staff Questions Developed at Public Meeting cc w/encls: Distribution via Listserv

LIST OF ATTENDEES NRC MEETING WITH SOUTHERN NUCLEAR OPERATING COMPANY, INC. (SNC)

REGARDING STEAM GENERATOR TUBE H* CRITERION PERMANENT ALTERNATIVE REVIEW CRITERIA SCHEDULE FEBRUARY 16, 2011 NAME Robert Martin Patrick Boyle Emmett Murphy Andrew Johnson Robert Taylor Ken Karwoski David Midlik Lesa Hill Hermann Lagally Chris Cassino Dan Mayes Parker Downing Anthony Martin Chung Tran Jay Smith Scott Redner Russell Lieder Steve Swilley Jim Riley AFFILIATION NRC/NRRlDORL NRC/NRRlDORL NRC/NRRlDCI NRC/NRRlDCI NRC/NRRlDCI NRC/NRR/DCI SNC SNC Westinghouse Westinghouse Duke Duke Southern Company Luminant Power Exelon Xcel Energy NextEra Energy EPRI NEI Via Telephone Conference Bridge Line Joel Rivera Adam Roslund Gary Whiteman Patrick Wagner Lisa Scoville Patrick Fabian Candee Lovett Mary Lou Calderone Gary Bowers NRC/Region II Westinghouse Westinghouse Wolf Creek Nuclear Operating Corporation Exelon PSEG-Salem Dominion - Surry Millstone FPL

Industry/NRC/Westinghouse Public Meeting on Steam Generator H*

Issues Industry / Westinghouse Presentation February 16, 2011 1

Industry / Westinghouse Presentation Agenda

  • Status of the H* Analysis Independent Review
  • Methodology Used to Develop the Permanent H*

Amendment Technical Basis

  • First Plant for PARC Submittal/Lead Industry Interface for Industry & NRC Communications
  • Status/Schedule of Industry H* for Spring 2012 Outages - License Amendment Requests 2

Industry / Westinghouse Presentation Status of the H* Analysis Independent Review Jay Smith - Exelon February 16, 2011 3

Topics of Discussion

  • Scope of Independent Review
  • Schedule of Independent Review
  • Method for Disposition of MPR Recommendations
  • Status of Independent Review 4

Scope of Independent Review

methodology and analysis.

  • The purpose of the independent review is to provide assurance that the analyses supporting H* are correct and conservative.
  • MPR will complete a technical review of the permanent H* analysis to identify areas that challenge the bases for the H* conclusions.

- MPR will review Westinghouse reports, letters, RAI responses to NRC questions and NRC documents regarding H* (Le., previous Safety Evaluation Reports).

  • To ensure independence in the review, a Utility Representative is assigned to serve as the interface between Westinghouse and MPR.

5

Scope of Independent Review

  • The review is addressing the following aspects of the H* analysis:

- Input assumptions

- Design and application of the structural models

- Design and application of the square cell model

  • Inputs and boundary conditions

- Probability analysis methods applied to the square cell model

- Leakage models and their inputs

- Tubesheet complex 3D Finite Element Analysis models

- Definition of the limiting tubesheet area for H*

- Thick shell model for calculating contact pressures

  • In addition, the fundamental assumptions are being reviewed for appropriateness and conservatism relative to all aspects of the H* technical justification.

6

Disposition of MPR Recommendations

  • All comments, questions and recommendations will be sent to Westinghouse through the Utility Representative.
  • Westinghouse will provide written disposition of MPR questions, comments and recommendations through the Utility Representative.
  • For issues that cannot be initially resolved, further dialogue between MPR and Westinghouse will occur to achieve alignment.
  • In the end there will be no unresolved issues or recommendations.

- If required based on the Independent Review, Westinghouse will issue revised or new reports. The schedule for this depends on the nature of the recommendation(s}.

7

Status of Independent Review

-MPR started review on January 24, 2011.

- The Review is 20% complete.

- To date, there are no recommendations that impact Westinghouse H* analyses.

8

Schedule of Independent Review

  • The Independent Review is scheduled to be completed within 11 weeks of work authorization.
  • Draft Report completed within 9 weeks
  • Final Report completed 2 weeks later
  • The Independent Review began January 24, 2011
  • Draft Report to be completed by March 28, 2011
  • Final Report to be completed by April 11, 2011 9

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Agenda

  • Overview of H* Methodology
  • Action Items from August 24, 2010 Meeting Ref: NRC Memorandum dated September 8, 2010, A.B.

Johnson to R.M. Taylor; "Summary of the August 24, 2010 Closed Meeting with US Nuclear Industry Representatives to Discuss SG H* Issues."

Current H* Methodology Overview

  • WCAP-17330 and WCAP-17345 represent a complete recalculation of H*, using the Square Cell (C2) Model only, for all models of SG:

- Revised displacement calculations for all models

- Revised mean H* Value for all models

- Revised variability surface for all models

- Adjustment for Poisson contraction applied to final probabilistic results for all models.

Actions from August 24, 2010 Meeting

  • In regard to Alternate Leakage Methods (Ref: ADAMS Accession Number ML102460157):
1. Provide a sample calculation for the K factors in Tables 1 and 2, for example specimen 1-b in Table 1. The sample calculation should include the assumed values (and associated units) for all input parameters.
2. Add a column to Tables 1 and 2 showing average contact pressure.
3. Provide an explanation for the difference between the driving head used in Tables 1 and 2, and the driving head used in the Gap Analysis portion of the white paper.
4. Provide an explanation of why Figure 1 contains four IIcolumns" of normalized calculated contact pressure, since there are only two sets of differential pressure values contained in Tables 1 and 2, with relatively constant values of average contact pressure for each case.

13

Actions from August 24, 2010 Meeting

5. In order to more clearly understand Figure 3, provide tables of average loss coefficient for each axial segment (for the various tubesheet radii) and the average contact pressure for each axial segment (for the various tubesheet radii).
6. Provide a sensitivity analysis of the Figure 3 results to different crevice pressure assumptions consistent with the variability of the data. Also show the sensitivity of the analysis to the use of the thick shell equations, in lieu of the Square Cell model.
7. For Tables 8 and 10, provide the information on a segment-by segment basis (segments as defined in Table 4), which would result in modified Figures 5, 6, and 7.

14

Actions from August 24, 2010 Meeting

  • Complete Square Cell Model analysis for all models of SGs (represented in H*)
  • Complete full-scope Monte Carlo probabilistic analysis on the Model 05 SG
  • Submit papers on BET, Effect of Eccentricity, and modified RAI responses
  • Provide complete and detailed description of the Square Cell Model in permanent license amendment requests
  • Further discussion between NRC and Industry if the location of the Bottom of the Expansion Transition will need to be accounted for in the probabilistic analysis 15

August 24, 2010 Meeting Update

  • Westinghouse Letter LTR-NRC-l0-60, dated 9/3/10, transmitted LTR-SGMP-l0-95-P (and NP), Revision 1 with affidavit to NRC.

LTR-SGMP-l0-95-P Revision 1 is an update of the

((Alternate Leakage Calculation Methods for H* for Situations When Contact Pressure at Normal Operating Conditions Exceeds Contact Pressure at Accident Conditions" white paper that addresses NRC questions regarding Revision 0 of the white paper.

- Revision 0 of LTR-SGMP-l0-95 was submitted prior to, and discussed at, the August 24, 2010 meeting 16

Item 1, 8/24/10 Meeting "Provide a sample calculation for the K factors in Tables 1 and 2, for example specimen 1-b in Table 1. The sample calculation should include the assumed values (and associated units) for all input parameters."

  • Appendix A of LTR-SGMP-l0-95, Revision 1 provides the requested information.

17

Item 2, 8/24/10 Meeting "Add a column to Tables 1 and 2 showing average contact pressure."

  • LTR-SGMP-10-95, Revision 1, Tables 1 and 2 were updated to show calculated (average) contact pressure

- Tables are Westinghouse Proprietary; please refer to submitted document 18

Item 3, 8/24/10 Meeting IiProvide an explanation for the difference between the driving head used in Tables 1 and 2/ and the driving head used in the Gap Analysis portion of the white paper.

N

  • LTR-SGMP-10-95, Revision 1, provides the explanation on page 24, second and third paragraphs 19

Item 3, 8/24/10 Meeting Further explanation is provided below:

The driving heads identified in Tables 1 and 2 of the White Paper represent the average measured primary to secondary pressure difference across each individual test specimen. For normal operating and postulated steam line break conditions, the secondary side pressure was measured from the autoclave outside of the test specimen. The driving head used in the gap analysis represents the crevice pressure that exists coincident with the exit of the annulus between the hydraulically expanded tube and the inner diameter of the test collar. The crevice pressure profile used in the gap analysis excludes Specimen 7 as discussed on page 6-115 of in WCAP-17072-P.

It is judged by Westinghouse that the driving head at the end of the expanded region of each test specimen is approximated by the crevice pressure profile discussed in WCAP-17072-P.

20

Item 4, 8/24/10 Meeting NProvide an explanation of why Figure 1 contains four Ncolumns" of normalized calculated contact pressure, since there are only two sets of differential pressure values contained in Tables 1 and 2, with relatively constant values of average contact pressure for each case."

21

Item 4, 8/24/10 Meeting

  • LTR-SGMP-10-95, Revision 1, provides the explanation on page 4 "Figure 1 shows the Model D5 simulation leak test data from Tables 1 and 2 plotted as a function of the calculated loss coefficient versus to calculated contact pressures in these tests. Tables 1 and 2 show the data for the 600°F tests performed at simulated NOP and SLB conditions. Additional tests were run at an intermediate primary side pressure (approximately 1885 psi) and at room temperature (RT) at pressure differentials of 1450, 1885, and 2835 psid. For the RT tests, the calculated contact pressures were lower due to the absence of differential thermal growth between the tube and the tubesheet. The data from all of these tests are shown on Figure 1 to provide a complete benchmark for the intended purposes - to test various assumptions of relationships between the loss coefficient and the contact pressure to evaluate their effect on predicted leak rate ratios."

22

Item 5, 8/24/10 Meeting "In order to more clearly understand Figure 3~ provide tables of average loss coefficient for each axial segment (for the various tubesheet radii) and the average contact pressure for each axial segment (for the various tubesheet radii}.H

  • LTR-SGMP-10-95, Revision 1, provides the requested tables on pages 16 and 17 The tables are Westinghouse Proprietary; please refer to the submitted document.

23

Item 6, 8/24/10 Meeting NProvide a sensitivity analysis of the Figure 3 results to different crevice pressure assumptions consistent with the variability of the data. Also show the sensitivity of the analysis to the use of the thick shell equations, in lieu of the Square Cell model."

24

Item 6, 8/24/10 Meeting LTR-SGMP-l0-95, Revision 1, provides the requested tables on pages 14 and 15 and Figure 10 "In response to an NRC request, the same analysis described above was completed for the Model D5 SGs based on contact pressures calculated using the Thick She" Equation approach discussed in Reference 1... /1 liThe NRC staff requested that a sensitivity study of crevice pressure on leak rate ratio be performed...the leak rate ratio is not sensitive to the absolute contact pressure...Rather, (it) is sensitive to the difference between the NOP and SLB contact pressure ratio if the SLB contact pressure is less than the NOP contact pressure./I 25

Item 7, 8/24/10 Meeting "For Tables 8 and 10, provide the information on a segment by-segment basis (segments as defined in Table 4), which would result in modified Figures 5, 6, and 7./1

  • LTR-SGMP-l0-95,Revision 1, provides the requested information

- Discussion on page 26; "At the request of the NRC, a similar calculation was performed, but assuming shorter crevice lengths for the test specimens..."

  • [Tables 8, 10 and 4 in Revision 0 translate into Tables 10, 12 and 6 in Revision 1]
  • [Figures 5, 6 and 7 in Revision 0 translate to Figures 12, 13, 14, 15 and 16 in Revision 1]

26

Other Actions, 8/24/10 Meeting "Complete Square Cell Model analysis for all models ofSGs (H*

candidates)N Complete except for 2-loop Model 44F plant See WCAP-17330-P (Models F and D5) and WCAP-17345-P, Rev. 1 (3-loop Model 44F, and 51F)

"Complete full-scope Monte Carlo probabilistic analysis on the Model 05 SG H

Complete except for 2-loop Model 44F plant See WCAP-17330-P (Models F and D5) and WCAP-17345-P, Rev. 1 (3-loop Model 44F, and 51F) 27

Other Actions, 8/24/10 Meeting (Continued)

  • "Submit papers on BET, Effect of Eccentricity, and modified RAJ responses"

- Complete; submitted by Westinghouse to NRC

  • LTR-NRC-IO-69, dated 11/11/10 (BET)
  • LTR-NRC-IO-68, dated 11/11/10 (Effect of Eccentricity)
  • LTR-NRC-IO-70, dated 11/12/10 (Modified RAI Response) 28

Other Actions, 8/24/10 Meeting (Continued)

  • "Provide complete and detailed description of the Square Cell Model in permanent license amendment requests H

Complete except for 2-loop Model 44F plant Section 3.3 of WCAP-17330-P (Models F and D5) and WCAP-17345-P, Revision 1 (3-loop Model 44F, and 51F) provide the complete description of the square cell model and its application to the different models of SG 29

Potential Actions, 8/24/10 Meeting NFurther discussion between NRC and Industry if the location of the Bottom of the Expansion Transition will need to be accounted for in the probabilistic analysis H

  • Probabilistic analysis is based on the critical radius specific to each model of SG
  • For the models of SGs discussed in WCAP-17330-P and WCAP 17345-P, Rev. 1, the square cell results show a length of about 1 inch at the TTS with zero contact pressure at the critical radius 30

Potential Actions, 8/24/10 Meeting (Continued)

  • Actual BET locations were identified (LTR-NRC-l0-69); the largest 95th percentile location among the H* candidate plants is 0.323 inch below the TTS
  • Tubes with BET locations more than 1 inch below the TTS have been, or will be, plugged
  • LTR-SGMP-09-111, Revision 1 concludes significant margins exist in the requested values of H* even if the BET location is

> 1 inch below the TTS

  • It is not necessary, nor practicable, to consider the BET location in the probabilistic analysis 31

Actions From Pre-Application Review

  • "Provide detailed description of the revised 3-D FEA of the lower SG model and the square cell model" How do the models address shortcoming of prior models Provide results for all plants using the revised models Complete probabilistic analysis for at least the Model D5
  • Justify not updating prior probabilistic analyses for other SG Models (F, 44F, 51F) on a case-by-case basis
  • "Account for Poisson's ratio effects in the application of the square cell model"
  • Other information from pre-submittal review Staff review of alternate leakage calculations is not complete

- Potential for meeting among staff, ANL and Westinghouse to address ANL results from severe accident modeling 32

Action 1, Pre-Application Review "Provide detailed description of the revised 3-D FEA of the lower SG model and the square cell model a} How do the models address shortcoming ofprior models b} Provide results for all plants using the revised models c} Complete probabilistic analysis for at least the Model 05

i.

Justify not updating prior probabilistic analyses for other SG Models (G 44G 51F) on a case-by-case basis N

WCAP-17330-P and WCAP-17345-P, Rev. 1 provide detailed descriptions of the TS Complex 3D FEA (Section 3.2) and Square Cell (C2) (Section 3.3) models 33

Action 1, Pre-Application Review (Continued) a) "How do the models address shortcoming ofprior models.l.l

- 3D FEA

  • Non-connected Divider Plate is modeled directly
  • Minor meshing scheme changes to improve displacement outputs for subsequent model
  • Separate thermal loading and pressure loading analyses performed
  • Detailed displacement results requested by NRC are included

Action 1, Pre-Application Review (Continued)

C2 Model

  • Accurately applies gross tubesheet displacements (from 30 FEA model) to the structure surrounding a tube

- Prior Thick Shell analysis applied gross displacement to tubesheet bore 10

  • WCAP-17330-P and WCAP-17345-P, Rev. 1 (Section 3.3) discuss details of the model for Model F, 05, 51F and 3 loop 44F. 2-loop Model 44F report is in preparation.

35

Action 1, Pre-Application Review (Continued) b)

NProvide results for all plants using the revised models N

  • C2 model analysis was performed for all models of SGs that are candidates for H*

2-loop Model 44F report is in preparation.

36

Action 1, Pre-Application Review (Continued) c}

"Complete probabilistic analysisfor at least the Model 05.

Justify not updating prior probabilistic analysesfor other SG Models (~ 44~ 51F) on a case-by-case basis.H Complete probabilistic analyses based on C2 are provided for all models of SGs in WCAP-17330-P and WCAP-17345-P, Rev. 1 (Section 3.4).

WCAP-TBD-P is in preparation for 2-loop Model 44F plant 37

Action 2, Pre-Application Review

Account for PoissonJs ratio effects in the application of the square cell model H

  • WCAP-17330-P and WCAP-17345-P, Rev. 1 (Section 3.5) include analysis and discussion of the effect of Poisson's ratio on H*

38

Final H* Lengths (based on application of Square Cell model)

H* Length (inches)

Justification SLB na na 05 WCAP-17330 8.02 13.35 13.36 (2)

(3)

(3)

WCAP-17330 F

NOP 8.01 14.60 15.t5 15.20 WCAP-17345 51F NOP 10.24 17.41 17.43 17.72 17.74 WCAP-17345 44F(3-L)

NOP 17.58 *............

  • 17.62

.17'-19 17.80

'J, SLB na na 44F (2-L)

WCAP-TBD 18.03 20.11 20.12 (2)

(3)

(3)

i.

Based on limiting plant wltrylndic;atedSGmodeL..

2.

Based on consistent use of models for both NOPand SLB conditlon~

3.

Does notapply for SLB limited H*

39

Final H* Leakage Factors Plant Leakage Factor Change from Prior Basis Reference MiUstone.3 2*.49 tTlf.SGM e-09-l00; Rl Vogtle 1 & 2 2.48 none LTR-SGMP-09-l00, Rl Seabrook 2.49 none LTR-SGMP':09-l00, Rl WolfCreek 2.50 none LTR-SGMP-09-l00, Rl "1"1 Salem 2~16 none LTR~SGMP-09~100J Rl

';:1 Byron/Braidwood 2 3.11 none LTR-SGMP-09-l00, Rl Comanche Peak 2 3.16 none LTR-SGMP-09-l00, Rl Catawba 2 3.27 none LTR-SG MP-l0-34, R2 Jurkey Poin~ 3 &4 1.82 none hTR~SGMP~09~100} Hl f:",;/j:,~

H. B. Robinson 1.82 none LTR-SGMP-09-l00, Rl Surry 1 &. 2

<1.$0 LTR-SGMP-09~100, Rl Point Beach 1 1.73 none LTR-SGMP-09-l00, Rl 40

Summary/Conclusions

  • All NRC questions from the August 24, 2010 meeting and the Vogtle pre-acceptance review have been addressed in WCAPs - 17330 and -17345 for the Model F, D5, 44F (3-Loop) and 51F SGs, and LTR-NRC 10-60
  • Two separate methods show H* exists at 95/95 for H* candidate plants
  • Prior leakage factors still apply; no change required from use of Square Cell Model 41

Industry / Westinghouse Presentation

  • First Plant for PARC Submittal:

Catawba Unit 2 (Duke Energy)

  • Lead Interface for Industry & NRC Communications:

Southern Nuclear Operating Company (SNC) 42

Industry / Westinghouse Presentation Status/Schedule of Industry H* for Spring 2012 Outages License Amendment Requests 43

Industry / Westinghouse Presentation Catawba U2

  • Outage Start Date: 3/2012
  • LAR PARC Submittal: 6/30/2011
  • LAR Requested Approval Date: 2/24/2012 Surry Units 1 & 2
  • Outage Date Unit 1: 4/2012
  • LAR PARC Submittal: 7/29/2011
  • LAR Requested Approval Date: 4/12/2012 44

Technical Staff Questions Developed at Public Meeting Although the staff has not conducted a detailed review of the technical support documents accompanying the requests for interim H* amendments, the staff has developed questions, listed below, relating to one of these documents, WCAP-17330. It is likely that a detailed review of WCAP-17330 would result in additional questions. The questions below were discussed during the meeting; however, Westinghouse was not in a position to answer these questions directly since they were only hearing these questions for the first time. The staff noted during the meeting that these are representative of the type of questions that will need to be addressed when licensees submit applications for permanent H* amendments, but that the staff has an adequate basis to complete its review of the interim amendment requests.

1. Describe the numerical procedure for calculating the H* mean values in Table 3-21.

Provide example solution for the case of Model D5 SLB at the smallest tubesheet radius that supports the H* mean value estimate for that radius. Assess the conservatism of the numerical procedure given that contact pressure has been assumed to vary linearly from zero at an elevation of 16.901 inches to the value noted in Table 3-8 and Figure 3 18 at an elevation of 10.515 inches..

2. For the example case of Model D5 SLB at radius noted in Table 3-8, assess the conservatism of the assumption that contact pressure varies linearly from ZE!ro at an elevation of 16.901 inches to the value noted at the elevation of 10.515 inches for purposes of calculating H*. Why is loss of contact pressure assumed to occur at a different elevation in Table 4-1? Should not the square cell model be run at many additional elevations between 10.515 and 16.901 inches (from BTS) to provide for a more realistic distribution of contact pressure and accumulated resistance force?
3. Different reference points for defining tubesheet elevation are used throughout the report. For example, tubesheet elevation is measured from the bottom of the tubesheet in Table 3-8 and from the top of the tubesheet in Figure 3-18. The use of a consistent reference point would add to report clarity. (This observation was not actually made during the meeting, but is included here for completeness.)
4. According to 3-43 of the text, Figures 3-32 and 3-33 are H* scatter plots from the Monte Carlo analysis of the Model D5 SGs. Confirm this is for NOP conditions (consistent with the condition analyzed in the reference analysis).
5. Figure 3-34 plots H* as a function of rank order. The text on page 3-44 states this figure applies to Model D5 SGs for NOP conditions. Explain apparent inconsistencies between this figure and Figure 3-32. For example, Figure 3-34 shows that H* remains relatively constant at a value of approximately 13 inches, based on the "original" Monte Carlo analysis, for rank orderings ranging from roughly 9150 to just over 9500. Figure 3-22 implies that H* doesn't reach 13 until rank orderings well beyond 9500. Please provide a detailed explanation of how the results in Figure 3-34 were obtained.

-2

6. Figure 3-35 appears to be mislabeled as "vs. Monte Carlo Rank Order." This figure is actually plotted vs. H*. Figure 36 is entitled "Reduced Model F NOP Response Data,"

but the reduced data isn't shown in the figure.

7. The titles for Figures 3-35 and 3-36 state that these Figures are for Model F. The text on page 3-47 states that these figures are for both Model F and D5 for NOP conditions.

Which is correct? If the latter, explain how these figures can apply to both SG models, given that each was subject to a separate Monte Carlo analysis and given the differences in geometry, mean H* values, and the different variability of H* with variations in CTET and CTETS between the SG models. As a related question, explain why the scatter plots for Model D5 SGs in Figures 3-32 and 3-33 are identical to the scatter plots in Figures 3-35 and 3-36 for Model F SGs.

8. Explain the apparent inconsistency between the alpha values of the reduced set data in Figure 3-35 versus the alpha values in Table 3-23 for the Model F SGs. (According to the text at the bottom of page 3-47, these values should be consistent). Also, provide revision to Figure 3-36 that includes plot of the reduced set data.
9. Section 3.4.4, page 3-48, states, The results shown in Table 3-28 are shown graphically in Figure 3-37." Explain why the current licensing basis results in Table 3-28 are not the same as those in Figure 3-37.
10. Provide an explanation for the shape of the scatter plot in Figure 3-38 and why it is so different from that in Figure 3-35. Why is the density of H* estimates so low for H*

estimates between 11 inches and 12.5 inches and so high for H* estimates between 12.5 and 14 inches? Provide a copy of the H* response surface as function of variations in CTET and CTETS for the case of Model D5 SLB that is referre!d to in the top line of page 3-49. (The scatter plot seems to imply a discontinuity in the H* response surface for Model D5 SLB that was not present in the H* response surface for Model 5 NOP.)

11. Figure 3-39 shows alpha values below 3.3 for rank orders ranging from 9100 to over 9900. Why does Figure 3-38 show alpha values below 3.3 only for relatively low H*

estimates (presumably rank orders at the low end of the 9000 to 10000 range)?

12. Provide revision to Figures 3-38 and 3-39 that show the reduced set data from Table 3
23.
13. Provide revision to Table 3-23 showing H* estimates from licensing basis Monte Carlo results corresponding to each of the rank order statistics.

- 3

14. The description of what is in Table 3-25 at the bottom of page 3-47 does not appear consistent with what is actually in the table. Explain how Table 3-47 is showing the "bounding data in the reduced set."
15. The report does not clearly explain the methodology used to select CTET and CTETS values from the reference Monte Carlo results for application to the square cell model.

In addition, the report needs to better justify the conservatism of the methodology in lieu of performing actual Monte Carlo analyses using H* response surfaces which reflect the square cell model and up to date nominal H* values.

16. The contact modeling discussion in Section 2.5 discusses coarse and fine meshes used in the C2 Model. Section 3.3.6 also discusses mesh convergence and notes that Figure 3-16 shows an intermediate mesh that was used in the C2 Model. While the importance of a properly converged mesh is mentioned, there is no discussion of what was used to define a properly converged mesh (e.g., less than 5% delta in contact pressure between two meshes).
17. There was no discussion regarding artificial stiffness of the model, and whether this attribute was looked at in conjunction with mesh convergence.

SNC

- 2 Members of the public representing other utilities and industry groups were in attendance.

Public Meeting Feedback forms were available at the meeting but no comments were received.

Please direct any inquiries to me at 301-415-3936.

IRA!

Patrick G. Boyle, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-424 and 50-425

Enclosures:

1. List of Attendees
2. Licensee's Presentation, "lndustry/NRClWestinghouse Public Meeting on Steam Generator H* Issues," IndustrylWestinghouse Presentation, February 16, 2011
3. Technical Staff Questions Developed at Public Meeting cc w/encls: Distribution via Listserv DISTRIBUTION:

PUBLIC LPL2-1 RlF RidsOgcRp Resource AJohnson, NRR RidsAcrsAcnw_MailCTR Resource RidsRgn2MailCenter Resource NSanfilippo, EDO Re'gion 2 RidsNrrDciCsgb Resource RidsNrrDorlLpl2-1 Resource CSteger, NRR RidsNrrLAMOBrienResource RidsNrrPMVogtle Resource RTaylor, NRR PBoyle, NRR RidsOpaMailResource KKarwoski RMartin, NRR EMurphy, NRR JRivera, NRC, Rgn II ADAMS Accession No ML110660648 OFFICE DORULPL2-1/PM DORULPL2-1/PM DORULPL2-1/LA GB/BC DORI

_.DORULPL2-1/PM NAME PBoyle RMartin MOBrien RTaylor (KKarwoski for)

GKulesa PBoyle DATE 03/28/11 03/28/11 03/24/11 03/28/11 03/25/11 03/28/11 OFFICIAL RECORD COpy

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