5/24/2012

Comanche Peak Nuclear Power PlantUnits 3 and 4

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Agenda

o US-APWR Standard Plant Design Updates

o Licensing Strategy

o Site-Specific Reconciliation of Standard Plant Design

o Seismic Evaluation and Design of Site-Specific Structures

o3 Potentially Related RAIs

L3 Summary and Conclusion

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US-APWR Standard Plant Design Updates

Q] New configuration of Reactor Building (R/B) Complex withcommon basemat supporting:" Pre-stressed Concrete Containment Vessel (PCCV)

" Containment Internal Structure (CIS)* Reactor Building (R/B)

* Auxiliary Building (A/B)

* East and West Power Source Buildings (PS/Bs)

L3 New configuration of Turbine Building (T/B) includingElectrical Room (E/R) with common basemat:0 The Turbine is supported on pedestal separated from T/B Basemat

C3 Standard plant design does not include shear keys orballast

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US-APWR Standard Plant Design Updates (cont.)

o Units 3 and 4 layout is modified to incorporate the updated standardplant configuration and site specific structures design enhancements

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US-APWR Standard Plant Design Updates (cont.)

L1 Dynamic FE Model with embedded foundation serves asstandard design basis model for SSI Analyses of R/BComplex

R/B Complex LMSM used forprevious revisions of DCD and R-COLA Updated R/B Complex FEM

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Licensing Strategy

Lj An evaluation of the R/B Complex (NI Complex) will be submitted toallow the NRC to issue a safety evaluation with an SER Open Item

" The evaluation will be based on CPNPP site characteristics and results fromprevious analyses showing that the US-APWR standard design of R/BComplex bounds the site-specific demands

" The evaluation will also show that the US-APWR standard design of the T/Bbounds the site-specific demands based on evaluation of CPNPP sitecharacteristics

u Perform SSI and SSSI analyses and design evaluation of the site-specific structures

L3 Perform site-specific SSI analyses of the RIB Complex as required byUS-APWR DCD

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Site-Specific Reconciliation of Standard Plant Design

:1 The evaluation will show that the standard design will boundthe CPNPP Units 3 and 4 site-specific seismic demands:* Low seismicity characterizes the CPNPP site resulting in site-specific design

ground motion that is less than 1/3 of the CSDRS defining the seismic inputfor standard design

* The dynamic properties of the limestone subgrade supporting CPNPP RJBComplex and T/B are similar to those of generic soil profiles 900-100 and900-200 used for the SSI analyses serving as the basis for the standard plantseismic design

* The previous revision of R-COLA demonstrated large margins based on site-specific SSI analyses of the R/B Complex lumped mass stick model (LMSM)

* The evaluation of site conditions shows a large level of certainty that thestandard design is applicable to the CPNPP site

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Site-Specific Reconciliation of Standard Plant Design(cont.)oj To meet the requirements of US-APWR DCD, the validity of the standard

seismic design for CPNPP site conditions will be demonstrated for theR-COLA by comparing:* US-APWR standard design CSDRS with the site specific FIRS for R/B

Complex* Strain-compatible dynamic properties of generic layered soil profiles used for

the standard design SSI analyses with the updated site specific soil profiles* 5% damping design basis in-structure response spectra (ISRS) used for

standard design of seismic Category I SSC's with corresponding ISRSobtained from site-specific SSI analyses of R/B Complex dynamic FE model

o T/B will be incorporated-by-reference (IBR) in the R-COLA based on R/BComplex analysis results and the evaluation of CPNPP site conditionsand seismic demands

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Site-Specific Reconciliation of Standard Plant Design(cont.)U Site-specific SSI analyses of R/B Complex will be performed using:

" ACS SASSI frequency domain time history method that accounts for theeffects of SSI frequency dependence, embedment and foundation flexibility

* Modified subtraction method (MSM) for SSI analyses of embeddedfoundations (the applicability of MSM will be demonstrated)

* Site specific input ground motion defined as envelope of the updated sitespecific FIRS and the minimum earthquake (1/3 of CSDRS)

* Updated site-specific profiles of best estimate (BE), lower bound (LB), upperbound (UB) and backfill high bound (HB) strain-compatible dynamic soilproperties

* Updated standard design basis dynamic FE model with single degree offreedom (SDOF) oscillators added to capture effects of concrete cracking onout-of-plane response of slabs and walls

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Site-Specific Reconciliation of Standard Plant Design(cont.)u Structural properties used for CPNPP site-specific and standard design

SSI analyses of R/B Complex and design basis comparisons

Structure Structural Properties DCO Standard Design R-COLA

Stiffness Damping ISRS SSE Loads ISRS

CiS Full (uncracked) 4% X X X

Reduced (cracked) 5% X X

PccV Full (uncracked) 3% X X X

Reduced (cracked) 5% X X

RIB, A/B, Full (uncracked) 4% X X(-)Reduced (cracked) 7% X X

r) SOOF oscillators ame used to capture out-of-plane respons. of cracked slabs and wells.

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Site-Specific Reconciliation of Standard Plant Design(cont.)

0 Site-specific ISRS will be developed to bound the R/B Complexresponses obtained from embedded foundation SSI analyses of BE,LB, UB and HB full column profiles and surface foundation SSIanalyses of LB truncated soil profile

* Embedded models will represent the actual site-specific configurationwhen modeling the contact of the basement walls with surroundingbackfill soil to validate assumptions made in the standard design seismicresponse analyses

* Additional SSI analysis is performed for a surface foundation to providethe bounding responses of the R/B Complex resting on the surface of asofter subgrade which envelopes effects such as backfill soil separation,backfill properties variations, water table variations

* Response due to the three directions of earthquake will be combinedusing SRSS method

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Seismic Evaluation and Design of Site-SpecificStructureso The previous R-COLA had the site-specific Seismic Category I

structures, UHSRS, ESWPT, East and West PSFSV, designedconsidering a design groundwater level (GWL) at El. 780 ft

o Design GWL has increased as identified in RAI 147 and otheractivities

o The higher GWL affects the design of the structures due toincreased soil pressure loadings and introduces buoyancyeffects that have to be addressed in the stability evaluations

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Seismic Evaluation and Design of Site-SpecificStructures (cont.)L Structural evaluations and design enhancements will be

implemented to address the increased load demands dueto the higher GWL, as applicable" Affected structural members will be evaluated and, if needed,

modified to meet the increased load demands

" Nearby site-specific structures may be integrated to eliminate airgaps and improve their stability (ESWPT, UHSRS, PSFSV)

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Seismic Evaluation and Design of Site-SpecificStructures (cont.)

L3 Seismic design of site-specific structures will be re-evaluatedbased on a new set of SSI analyses performed using:0 ACS SASSI frequency domain time history method

0 Modified subtraction method (MSM) for SSI analyses of embeddedfoundations (the applicability of MSM will be demonstrated)

m Site-specific input ground motion that will bound the updated site-specificFIRS and the minimum earthquake (1/3 of CSDRS)

0 Updated site-specific profiles of BE, LB, UB and backfill HB strain-compatibledynamic soil properties

0 Updated dynamic FE models reflecting the design updates and representingthe actual site-specific configuration of the contact between the basementwalls and the backfill soil

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Seismic Evaluation and Design of Site-SpecificStructures (cont.)U Analyses will be performed to address SSSI effects on PSFSV and

ESWPT design basis and to confirm that the standard design envelopsSSSI effects:

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SSSI analysis on combined model ofESWPT, West PSFSV, RIB Complex and T/B

, T/B

SSSI analysis on combined modelof East PSFSV and TIB

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Seismic Evaluation and Design of Site-SpecificStructures (cont.)

!U SSSI effects will be assessed as follows:SSSI effects of UHSRS on the nearby ESWPT segments will be assessedfrom free field response obtained from SSI analyses of stand-alone UHSRSmodel and if significant, will be included in the ESWPT design basis bymagnifying the input ground motion

a SSSI effects of standard plant buildings on PSFSV and ESWPT will beassessed from SSSI analysis of surface foundation combined model of R/BComplex, T/B, West PSFSV and nearby segment of ESWPT

" SSSI effects of T/B on East PSFSV will be assessed from SSSI analyses ofembedded foundations of the T/B and PSFSV combined model

* If significant, SSSI effects will be included in design basis by envelopingresponses obtained from SSI analyses of stand-alone models and SSSIanalyses of combined models

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Potentially Related RAIs

L) Response to RAI 221 indicated that standard plant buildingsmay require shear keys to meet SRP 3.8.4 sliding stabilitycriteria

L3 Shear keys will not be required to meet SRP 3.8.4 stabilityrequirements due to updated standard plant configuration andthe small seismic demands at CPNPP

o The standard plant safety-related structures are not adverselyaffected by the GWL increase because the standard designconsiders a nominal groundwater level of 1 ft below grade

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Potentially Related RAts (cont.)o Update FSAR tables, text, and figures (RAls 60, 64, & 122)

o Estimate additional demands caused by lateral fluid pressure fromvertical mode hydrodynamic effects (RAls 64, 162 & 167)

L3 Show that the PSFSV SSI response is not sensitive to the dynamicproperties of power source fuel storage tank (RAI 167)

o Provide technical justifications (RAls 108 & 102):" Modeling of shell to solid element connections

" Design of ESWPT segment between R/B Complex and T/B

" Increase live load to 50% or more for individually loaded members

" Update earth pressure loadings for PSFSV

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Potentially Related RAls (cont.)

" Update factors of safety for sliding and overturning consideringappropriate flood and groundwater levels (RAI 115)

o Update tornado loads and load combinations (RAI 54 & 66)

oj Provide detailed design of PSFSV tank mountings and theirlocal effects on the PSFSV (RAI 122)

o Eliminate ESWPT shear keys by integrating nearby structuresand other design enhancements (RAI 22)

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Summary and ConclusionL Site-specific reconciliation of the updated design of the US-

APWR standard plant will be performed0 Per DCD requirement, standard design ISRS will be compared with

site-specific ISRS obtained from SSI analyses of updated R/BComplex FE model using updated input design motion and siteproperties

0 T/B will be IBR based on R/B Complex SSI analysis results andevaluation of CPNPP site conditions and seismic demands

L Design of Cat. I site-specific structures (UHSRS, PSFSV andESWPT) will be enhanced to accommodate the changes ofstandard plant configuration and the higher GWL

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Summary and Conclusion (cont.)o Seismic design of UHSRS, PSFSV and ESWPT will be re-

evaluated based on a new set of SSI and SSSI analyses

o Revised R-COLA seismic evaluations will be based on updatedsite inputs and will address RAI concerns

o FSAR Sections 3.7 and 3.8 and Ch. 3 appendices will beupdated to reflect the results of seismic and stability analyses

o Luminant will revise RAls 221 and 226 and provide a responseto recent RAI 247

* Luminant will not revise responses to other RAIs, but will ensurethe issues are addressed by updating the FSAR tables, text, andfigures

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