ML031080639

FPL Presentation Slides Regarding Changes Needed to Support Increased Steam Generator Tube Plugging

ML031080639
Person / Time
Site:	Saint Lucie
Issue date:	04/17/2003
From:	BNFL, Florida Power & Light Co, Westinghouse
To:	Office of Nuclear Reactor Regulation
References
Download: ML031080639 (18)

Text

St Lucie Unit 2 Changes Needed to Support Increased Steam Generator Tube Plugging L

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Slide 1 jaWestrnuse Agenda Meeting Goals Overview ZIRLOT" fuel rod cladding Reload safety analysis methodology changes Technical Specification changes Details of Changes Anticipated Submittals and Schedules Summary 0BNFL Slide 2 tWestmuse 1

Meeting Goals To present to the NRC staff the scope of the changes necessary to accommodate operation of St. Lucie Unit 2 with increased steam generator tube plugging (SGTP) up to 2520 tubes/SG (-30%) with approximately up to 600 tubes SGTP asymmetry

(-7%)

To identify those areas that will require NRC staff review and approval To identify the NRC review schedule needed to support St. Lucie Unit 2 Cycle 15 operation OBNFL Slide3 Awestzhouse Overview: St. Lucie Unit 2 Steam Generator Status 4000 PSL25G X

3500 - -

PS2 SG Prof CY-14 PSLI OSG c 3000 Current SGPlugging Limit 14 8%

2500- -------

° 2000 I 1500-1000-500 EFFECTIVE FULL POWER YEARS OF OPERATION C)BNFL Slide 4 2

Overview: Strategy Early action needed to avoid exigent analysis and NRC review Changes needed to accommodate and minimize the impact of 30% SGTP Fuel design change to ZIRLOI' fuel rod cladding Reload methodology change to WCAP-9272-P-A Technical Specification changes

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BNFL Slide 5 Wesnnomuse Overview: ZIRLOt' ZIRLO' provides improved corrosion performance needed in the more adverse RCS thermal conditions due to increased SGTP Extensive successful industry operating experience with ZIRLO0 clad fuel rods with over 2,650,000 fuel rods operated in 47 reactors and with burnups of up to 70,000 MWD/MTU (LTAs)

ZIRLO0 has been approved by the NRC for analysis with CENPD methods in CE-NSSS via CENPD-404-P-A NRC approval was subject to 5 conditions for use of ZIRLO.. which will be satisfied by FPL GBNFL Slide 6 OWestnouse 3

I Overview: Transition to WCAP-9272-P-A Methodology (Westingo WCAP-9272-P-A reload analysis methodology successfully used in reload analysis of over 540 reactor cores in the U. S. A.

Westinghouse Reload Safety Evaluation Methodology (WCAP-9272-P-A)

Defines a bounding approach to the reload evaluation process Defines key safety parameters and their limiting direction Defines in general terms how safety analyses are done and effects of key safety parameters Results in a Reload Safety Analysis Checklist (RSAC) approach for reload analysis St. Lucie Unit 2 transition to WCAP-9272-P-A requires all UFSAR Chapter 15 events to be re-analyzed or evaluated All limiting events would also need to be re-analyzed to support 30% SGTP with associated RCS flow reduction and implementation of ZI RLO'1 0BNFL Slide 7 SWesnngtose Overview: Transition to WCAP-9272-P-A Methodology (Westinghqse)

The Westinghouse and CE designs are similar and any minor dissimilarities (i.e.,

typically input parameters but occasionally a model change) can be accounted for and do not invalidate the reload methodology applicability or philosophy Code, selection, use and applicability will be described, explained and justified All code packages that are planned to be used have been previously licensed or will be re-licensed as necessary with the NRC Selection of code packages does not invalidate the reload methodology applicability (BNFL Slide 8 4

Overview: Transition to WCAP-9272-P-A Methodology (Westingh )

Principle areas of licensing focus:

changes to existing codes and models or new codes and models, and changes to existing methodology or new methodology "New" means new with respect to the "intended application" (i.e., the code/model or method was previously licensed, but has been tailored/customized for the current application)

Certain items to be submitted to the NRC for review and approval. Since these items would have been previously licensed, the specific licensing application for St. Lucie Unit 2 should be straightforward By identifying changes and areas that may need NRC review, the NRC staff will be able to more accurately gauge their resource needs to support the review

• BNFL Slide 9 Wewrighouse Overview: Technical Specification & COLR Changes There are several Technical Specification and COLR changes:

Related to 30% SGTP and associated RCS flow reduction Related to implementation of ZIRLO' Related to methodology changes Related to relocation of limits to COLR similar to TSTF-339, Rev. 2 and WCAP-1 4483-A 9 BNFL Slide 10 0 Wesntse 5

Details of Changes: ZIRLOI ZIRLO. approved by NRC for CENPD methods in CE-NSSS via CENPD404-P-A Five conditional requirements:

1. Corrosion limit (best estimate) will remain below 100 microns

> The 100 micron limit will be added to the St Lucie Unit 2 UFSAR and best estimate models will be used to confirm this limit is satisfied

2. All conditions in NRC SERs for CENPD methodologies, used for ZIRLOT' fuel analysis, will continue to be met except that ZIRLO'm cladding in addition to Zircaloy-4 cladding is approved

> The NRC SER conditions for use of the CENPD methodologies used for the analysis of ZIRL0- fuel will be satisfied

3. All CENPD methodologies will be used only within the range for which ZIRLOtm data was found to be acceptable in CEPD-404-P-A

> The ZIRLO data ranges for the methodologies used will be verified 0BNFL Slide 1 1 Westinghoue Details of Changes: ZIRLOsh

4. Until data is available demonstrating performance of ZIRLOtm cladding in CE-NSSS, fuel duty will be limited with some provision for adequate margin to account for variations in core design (e.g., cycle length, plant operating conditions, etc.)

> FDlm will be limited to the CE 1 6x16 design experience database, with only a limited number of fuel assemblies (8) allowed to reach 120% of this limit until data is available demonstrating performance of ZIRLO' cladding in CENP designed plants

5. The approved burnup limit is 60 GWD/MTU

> Burnup limit of 60 GWD/MTU for ZIRLO' fuel will be added to the St. Lucie Unit 2 UFSAR

%VBNFL Slide 12 eWstlin"use 6

Details of Changes: Analytical Approach A presentation of changes to existing codes and models or new codes and models will be provided first, followed by a presentation of changes to existing methodology or new methodology The presentation looks at each functional discipline and the codes and models used An assessment of each proposed code change is provided in the following table OBNFL Slide 13 Dwegouse Details of Changes: Analytical Approach - Codes and Model Functional Discipline Core Design Thernmal-hydraulic Design Correlation Fuel Rod Design Transient Analysis (non-LOCA)

Large Break LOCA Small Break LOCA Current Code Used ALPHA/PHOENIX-P/ANC TORC CE-1 FATES-3B CESEC/STRIKIN-II/

TORC/COAST 85EM SiM Proposed Code Used Same VIPRE/CETOP ABB-NV Same RETRAN/FACTRAN/

VIPRE-W/TWINKLE 99EM 52M Comments No change Addendum submittal for incorporating ABB-NV & ABB-TV into VIPRE Upgrade correlation with ABB-NV which is NRC-accepted for referencing in applications for the St. Lucie Unit 2 fuel design No change Change is within the flexibility of the codes to model both Westinghouse and CE NSSS Upgrade to 99EM which is NRC-accepted for referencing in applications for CE NSSS Upgrade to 52M which is NRC-accepted for referencing in applications for CE NSSS GBNFL Slide 14 Mwestrse 7

Details of Changes: Analytical Approach - Codes and Model VIPRE/ABB-NV VIPRE is flexible with respect to modeling both Westinghouse PWRs and CE PWRs The main difference between modeling either Westinghouse or CE PWRs is the CHF correlation to be used in VIPRE for the corresponding fuel types VIPRE originally licensed by the NRC with the W-3, WRB-1 and WRB-2 CHF correlations (later, WRB-2M was added to VIPRE and licensed with the NRC)

ABB-NV will be used for St. Lucie Unit 2 and ABB-TV is for 1 4x1 4 fuel with Turbo mixing vane grids Both ABB-NV and ABB-TV correlations will be added to VIPRE and benchmarked to TORC results for its entire data base from topical report CENPD-387-P-A IWBNFL Slide 15 0wea=

Details of Changes: Analytical Approach - Codes and Model VIPRE/ABB-NV (cont.)

Findings of a benchmark show that the two sub-channel analysis codes yield essentially the same results The benchmark approach is the same used for the WRB-1 and WRB-2 qualifications with the VIPRE code OBNFL slde16 0Wesnghouse 8

Details of Changes: Analytical Approach - Codes and Model RETRAN/TWINKLE/FACTRAN are used for analysis of transient events The RETRAN code is used to perform analysis for most of the UFSAR transient events FACTRAN is used strictly in combination with either RETRAN or TWINKLE (RETRAN and TWINKLE provide certain time-dependent inputs required by the FACTRAN code)

TWINKLE is limited to the analysis of uncontrolled CEA withdrawal from a subcritical or low power condition, and CEA ejection The minor differences between Westinghouse and CE PWRs, and their corresponding fuel types, is well within the modeling capabilities of these codes OBNFL Slide 1 7 weflinghwuse Details of Changes: Analytical Approach - Codes and Model RETRAN/TWINKLE/FACTRAN (cont.)

Re-analysis of the limiting UFSAR Chapter 15 events are required for transition to Westinghouse WCAP-9272 Reload Methodology, 30% SGTP and reduced RCS flow TS changes will be submitted Use of these codes and models will be justified Results of transient analyses will be provided The general approach using RETRAN can be extended to encompass application to the St. Lucie Unit 2 plant No code changes are necessary, but the St Lucie Unit 2 model would differ slightly compared to those models for Westinghouse PWRs The St. Lucie Unit 2 RETRAN thermal hydraulic model is comparable to that used for Westinghouse PWR analyses The St. Lucie Unit 2 specific control and protection system logic has been incorporated into the RETRAN model 0BNFL Slide 18 AnWegkr 9

Details of Changes: Analytical Approach - Codes and Models RETRAN-02 (cont.)

The protection system simulation will include the St. Lucie Unit 2 variable high power, TM/LP and high pressurizer pressure reactor trips Control systems will reflect St. Lucie Unit 2 design The ECCS, including the Si system and safety injection tanks will reflect St. Lucie Unit 2 design (DBNFL Slide 19 IWes=tiouse Details of Changes: Analytical Approach - Codes and Model 99EM and S2M 1999 Evaluation Model (99EM) for LBLOCA and Supplement 2 Model (S2M)

Evaluation Model for SBLOCA are NRC-accepted for referencing in applications for CE designed PWRs Analysis will use fuel performance data generated with the FATES-3B computer code Since EMs for St. Lucie Unit 2 have already been accepted for use in licensing applications for CE-designed PWRs, UFSAR and licensing report will simply demonstrate acceptable ECCS performance St. Lucie Unit 2 plant-specific studies will be performed for ZIRLOTh cladding ZIRLO' cladding has been analyzed with 99 EM and S2M for two CE PWRs which showed that ECCS performance is not significantly impacted (small PCT benefit) 3 BNFL Slide 20 GWestlrgouse 10

Details of Changes: Analytical Approach -Methods and Methodolo y Analyses being performed support 30% SGTP, a reduced RCS flow, ZIRLO"' cladding, and transition to Westinghouse WCAP-9272 Reload Methodology Even though some of these methodologies may have specific applications called out in the applicable Safety Evaluation Reports (SERs), the general approach, as documented in numerous topical reports, can be extended to encompass application to the St. Lucie Unit 2 plant Demonstration of applicability showing that safety and margins are maintained, will be documented in a licensing report that supports UFSAR changes 0BNFL Slide 21 1Wese Details of Changes: Analytical Approach -Methods and Methodoloci Methodology changes that will be incorporated into the St. Lucie Unit 2 analyses supporting Cycle 15 are:

Relaxed Axial Offset Control (RAOC), analogous to the current Xe Swing methods to ensure safety analyses adequately address a range of power shapes Revised Thermal Design Procedure (RTDP), analogous to the current Extended Statistical Confirmation of Uncertainties (ESCU) methodology for statistical convolution of DNBR uncertainties Modeling of the current TM/LP trip function, analogous to the OTAT and f(DI) trip functions normally employed in Westinghouse PWRs 0 BNFL Slide 22 9westrwue 11

Details of Changes: Analytical Approach -Methods and Methodology Relaxed Axial Offset Control (RAOC)

Starting from a normal operating condition, the following accidents are simulated:

Cooldown Transients Control Rod Malfunctions Boration/Dilution: Note that dilution accidents performed assuming manual rod control only, automatic control rod withdrawal and insertion is blocked in St. Lucie Unit 2 The methodology of RAOC, as described in the topical report, may refer to specific values applicable to Westinghouse-type PWRs, but the approach of handling axial offset (ASI) control, with appropriate numerical values used for St. Lucie Unit 2, can still be handled under RAOC IBNFL Side 23

$ Wesilntfgouse Details of Changes: Analytical Approach -Methods and Methodology Relaxed Axial Offset Control (RAOC) (cont.)

UFSAR analyses will be updated and a licensing report will be prepared The NRC may only have to review minor differences of extending the methodology to the St Lucie Unit 2 application Plant Monitoring and Surveillance Under RAOC Methodology (Part B of WCAP-1 0216-P-A, Revision 1 A),

FXY(z) surveillance has been replaced by FQ(z) surveillance W(z) function that represents the maximum likely increase in the equilibrium measured FQ(z) that might arise during power distribution transients will account for non-equilibrium operation This surveillance is applicable ONLY when fixed incore detectors are out of service

• BNFL Slide 24 Mwesngfwse 12

Details of Changes: Analytical Approach - Methods and Methodology Revised Thermal Design Procedure (RTDP)

RTDP takes uncertainties in system parameters, peaking factors, fuel manufacturing, and engineering hot channel factors in a statistical combination with the uncertainty in a DNB correlation to obtain a DNB uncertainty factor Correlation DNBR + DNB uncertainty factor = plant specific Design Limit DNBR (DL DNBR)

DL DNBR + generic margin = Safety Analysis Limit (SAL) DNBR which is used for the accident analysis (generic margin covers transition core effects, rod bow, etc.)

Since the uncertainties are all included in the uncertainty factor, the accident analysis is done with input parameters at their nominal or best estimate value EBNFL Sride 2 5 i

Westlnghouse Details of Changes: Analytical Approach -Methods and Methodologcy Thermal Margin/Low Pressure (TM/LP) Trip Function DNB protection for the core is provided by TM/LP reactor trip function, which will be retained TM/LP reactor trip function also ensures that vessel exit boiling is precluded to ensure that the AT (hot leg minus cold leg temperature) is proportional to power Since use of the TM/LP reactor trip function is included in the current method, with slight modifications made to the methodology incorporating RAOC and RTDP, only those changes noted will require NRC review UFSAR analyses will be updated and justified via the licensing report The NRC may only need to review minor differences of extending the methodology to the St Lucie Unit 2 application GDBNFL Slide 26 GIWestintuse 13

Details of Changes: Analytical Approach -Methods and Method o

Accident Analyses Accident analyses will be briefly described as to the licensing impacts associated with 30% SGTP, reduced RCS flow analysis, ZIRLO'h cladding, and transition to the Westinghouse WCAP-9272 Reload Methodology A detailed screening process was performed which examined all of the current St. Lucie UFSAR Chapter 15 licensing basis analyses An assessment was performed to determine whether:

• the WCAP-9272 reload methodology could be directly applied with little or no changes to the existing licensing basis analyses, or

• the WCAP-9272 reload methodology does not address specific accidents and they need to be retained 0BNFL Slide27 (a Westiiotmse Details of Changes: Analytical Approach -Methods and Method o

Accident Analyses (cont.)

Analyses with essentially no licensing changes other then addressing the new initial conditions:

CEA Drop Event Loss of Normal Feedwater Increased Main Steam Flow Feedwater Line Break Event CVCS Malfunction - Inadvertent Boron Dilution Inadvertent Opening of the Pressurizer Relief Valves Single Reactor Coolant Pump Shaft Seizure/Sheared Shaft Increase in Feedwater Flow/Decrease in Feedwater Temperature Loss of Condenser Vacuum/Loss of Electrical Load/Turbine Trip Decrease in Reactor Coolant Flow Rate/Complete Loss of RCS Flow Uncontrolled CEA Withdrawal from a Subcritical or Low Power Condition

• BNFL Slide28 ewegwtse 14

Details of Changes: Analytical Approach -Methods and Methodologv Accident Analyses (cont.)

Analyses with minor licensing changes based on extension of methodology or code and models:

Methodology Differences:

Uncontrolled CEA Withdrawal at Power: Credit TM/LP trip CEA Ejection: Separation of BOL/EOL HFP and HZP cases Asymmetric Steam Generator SLB Events: Not specifically analyzed for Westinghouse PWRs, bounded by other cases Examine bounding case only on a reload basis:

Steam System Piping Failures: Demonstrate Post-Trip Steamline Break w/

LOAC bounded by Post-Trip Steamline Break w/o LOAC OBNFL Slide 29 I=Weglhouse Details of Changes: Technical Specification & COLR Changes Related to 30% SGTP and associated RCS flow reduction TS 3.2.5 - RCS flow to be reduced to 335,000 gpm from 355,000 gpm TS Figure 2.1 TMSLL to change to reflect reduced flow conditions TS Table 2.1 Reference RCS to change to reflect 335,000 gpm TS 3.1.1.4 - Revise MTC limit at HFP to < 0 pcm/0F COLR Section 2.6 - A reduction in F, may be needed 0 BNFL Slide 30 MWestmuse 15

Details of Changes: Technical Specification & COLR Changes Related to implementation of ZIRLO' TS 5.3.1 - Change design features description to include ZIRLO' TS 6.9.11.b - Add CENPD404-P-A to COLR methodologies list COLR Section 3.0 - Add CENPD404-P-A to COLR methodologies list

@ BNFL Slide 31 IMWese Details of Changes: Technical Specification & COLR Changes Related to methodology changes TS 1.3.7,4.2.1.3.c, 3.2.2,and 3.2.4 - Replace Fxy with Fq TS 6.9.11.b - Add LOCA and WCAP-9272-P-A to COLR methodologies list COLR Section 2.5 - Replace Fxy with Fq COLR Figure 3.2 Replace Fxy with Fq and Fr part power multiplier COLR - Add a W(z) adjustment for Fq COLR Section 2.6 - Add a part power multiplier to the Fr limit COLR Figure 3.2 Adjust to allow full power operation with excores only COLR Section 3.0 - Add LOCA and WCAP-9272-P-A to COLR methodologies list

@-BNFL Slide 32 nWeslngtouse 16

Details of Changes: Technical Specification & COLR Changes Related to relocation of limits to COLR similar to TSTF-339. Rev. 2 and WCAP-1 4483-A TS Figure 2.1 TMSLL TS Table 2.1-1, Item 4; Figures 2.2-1, 2.2-3 and 2.2-4 -TM/LP TS 3.2-5, Table 3.2 RCS pressure, temperature & flow rate TS 6.9.1.1 1.a - Add limits moved to COLR COLR - Add limits moved to COLR OBNFL Slide 33 Anticipated Submittals and Schedules A VIPRE-W topical addendum for the addition of the ABB-NV and ABB-TV CHF correlations will be submitted Licensing Report submittal will be prepared that references WCAP-9272-P-A:

Describe the accident analyses in sufficient details to support the UFSAR revisions to Chapter 15, including identification and justification of any new methods or methodology or extensions of methods and methodology that have not been previously licensed, and Describe codes used in the analysis and specify new codes and models or extensions to codes and models that have not been previously licensed Technical Specification and Bases changes and markups will be provided with summary discussion of justification for each change CDBNFL Slide 34 feIngheuse 17

A.

Anticipated Submittals and Schedules Schedule:

Activity Anticipated Anticipated Start/Submittal Date Finish/Approval Date Meeting with NRC to Kick-off the Program 4/03 4/03 AddendumtoVIPRETopical 5/03 5/04 (WCAP-14565-P-A)

Acceptance Meeting for Addendum to VIPRE 6/03 6/03 Topical (WCAP-14565-P-A)

Proposed Licensing Amendment for St. Lucie 1/04 10/1/04 Unit 2 submittal Acceptance Meeting for St. Lucie Unit 2 2/04 2/04 submittal

' Application of this topical will be referenced on the St Lucie Unit 2 docket 0BNFL Slide 35 iWestinlftms Summary Scope of changes necessary to accommodate operation of St. Lucie Unit 2 with increased SGTP to -30%, transition to ZIRLOT' cladding, and transition to WCAP-9272 approach requires only minor adjustment to extend to the unique trips and design features of St. Lucie Unit 2, identified and justified in the License Amendment Request NRC staff review and approval can build upon the use of previously approved codes and models, focusing on the acceptability of any extensions beyond those that were previously approved The expected content of the licensing documentation and proposed schedules have been provided to facilitate NRC planning:

VIPRE-Wtopical addendum (5/03 - 5/04)

License Amendment Request (1/04 - 10/04)

GBNFL Slide36 IWestuse 18