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Enclosure 4-3 Risk-Informed Closure of GSI-191, Volume 3, Engineering (Casa Grande) Analysis, Cover - Page 211 of 248
	ML13323A190
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Site:	South Texas
Issue date:	11/06/2013
From:	Letellier B C, Sande T D, Zigler G L; ALION Science & Technology Corp, Enercon Services, South Texas
To:	; Office of Nuclear Reactor Regulation
References
	GSI-191, NOC-AE-13003043, TAC MF0613, TAC MF0614, TAC MF2400, TAC MF2401, TAC MF2402, TAC MF2403, TAC MF2404, TAC MF2405, TAC MF2406, TAC MF2407, TAC MF2409 STP-RIGSI191-V03, Rev 2
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NOC-AE-13003043 ENCLOSURE 4-3Risk-Informed Closure of GSI-191Volume 3Engineering (CASA Grande) Analysis STFSouth Texas Project Risk-Informed GSI-191 Evaluation Volume 3CASA Grande AnalysisDocument:

STP-RIGS1191-V03 Revision:

2Date: November 6, 2013Prepared by:Timothy D. Sande, Enercon Services, Inc.Bruce C. Letellier, Alion Science and Technology Gilbert L. Zigler, Enercon Services, Inc.Reviewed by:Zahra Mohaghegh, University of Illinois, Urbana-Champaign Seyed A. Reihani, University of Illinois, Urbana-Champaign Approved by:Ernest J. Kee, South Texas Project South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2The Risk-Informed GSI-191 Closure Pilot Program is piloted by the South Texas Project (STP) NuclearOperating Company and jointly funded with several other licensees.

It is a collaboration of experts fromindustry,

academia, and a national laboratory.

In general, all products are developed jointly andreviewed in regularly scheduled (monthly)

Technical Team Meetings and weekly teleconferences as wellas in specific review cycles by Independent Oversight (technical evaluation of all materials),

STP NuclearOperating Company project management, and STP Nuclear Operating Company quality management.

The business

entities, the main areas of investigation, and the principal investigators of the PilotProgram are summarized below.STP Nuclear Operating CompanyProject Management, Licensing, Quality Assurance Steve Blossom; Rick Grantom (ret.); Ernie Kee; Wayne Harrison (ret.); Wes SchulzAllan Science & Technology Containment Accident Stochastic Analysis (CAS) Grande & GSI-191 Analysis

& Methodology Implementation (GAMI)Bruce Letellier, PhD1; Janet Leavitt, PhD2;Tim Sande3; Gil Zigler3; Austin Glover3, Clint Shaffer, Joe Tezak3The University of New MexicoCorrosion/Head Loss Experiments (CHLE)Kerry Howe, PhDUniversity of Illinois at Urbana Champaign Independent Oversight Zahra Mohaghegh, PhD4; Seyed Reihani, PhD4Texas A&M University Thermal Hydraulics (TH)Yassin Hassan, PhD; Rodolfo Vaghetto, PhD; Saya LeeThe University of Texas at AustinUncertainty Quantification (UQ), Jet Formation Elmira Popova, PhD (1962-2012);

David Morton, PhD; Alex Galenko, PhD; Jeremy Tejada, PhD; ErichSchneider, PhDABS Consulting Probabilistic Risk Assessment (PRA)David Johnson, ScD; Don Wakefield; Tom MikschlKnf Consulting

Services, LLCLocation-Specific Failure Damage Mechanism (DM)Karl Fleming; Bengt Lydell (ScandPower) 1 Previous to 2013, Los Alamos National Laboratory 2 Previously, UNM3 From January 2013, Sande, Glover, Zigler, and Tezak, ENERCON4 Previous to 2013, Soteria Consultants, LLCPage 2 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Revision History LogRevision Date Description 0 1/30/2013 Original document.

1 6/6/2013 The following changes were made in this version of the report:" Miscellaneous editorial changes" Replaced proprietary information related to the fiberglass debrissize distribution and fiberglass erosion fractions with references tospecific tables that contain the same information in otherdocuments.

" Added a new section describing the information process flow inCASA Grande." Added a description at the end of the conventional head losssection to clarify that the head loss values calculated with theNUREG/CR-6224 correlation were increased significantly to accountfor uncertainties in the correlation.

" Replaced informal email reference for shedding parameters with arevised version of the UT technical report and updated parameter values.2 See Cover Several changes were made to this version of the report to addresspage inconsistencies that were discovered between the previous version and theactual implementation in CASA Grande. The changes to the report include:* Revised figures in Section i to reflect the final implementation.

Revised tables and figures in Section 2.1 to reflect the implemented relationship between various input parameters.

Revised discussion in LOCA frequency input section to describeinterpolated values that were excluded from the LOCA frequency inputs, and updated tables to match the format of the reference document.

" Deleted the equations and probability distributions for active watervolume and pool level in Section 2.2 that were not implemented inCASA." Revised footnotes to correct reference numbers." Corrected total SI flow rate for 27.5-inch DEGB in Section 2.2 alongwith the associated figure and equation.

" Added elevation difference below the containment floor for CS andLHSI pumps as well as the HHSI pumps in Section 2.2." Deleted the figure in Section 2.2 showing several pool temperature Page 3 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Revision Date Description profiles along with the interpolation scheme that was notimplemented in CASA, and added a table showing the specificvalues that were implemented.

" Added statements in the design input and debris generation analysis sections that the bounding LBLOCA qualified coatingsquantities were used for all break sizes in CASA. Also added afootnote in Section 2.2 clarifying the basis for the qualified coatingsquantities used." Added an assumption that the qualified coatings debris is assumedto fail as 10 pIm particles.

" Deleted unqualified coatings figures and data in Section 2.2 thatwere not implemented in CASA." Revised description of the treatment of unqualified coatings in thedebris generation analysis section to clarify the CASA evaluation.

Deleted destruction pressures corresponding to the insulation ZOIsizes in Section 2.2.* Split assumption regarding linear interpolation of LOCA frequencies into two separate assumptions-one for the interpolation of thetop-down frequencies and another for the interpolation of thebottom-up frequencies.

" Made several corrections to the characteristic debris sizes anddensities shown in the strainer head loss analysis section including:

o Corrected the size and S, for small and large pieces offiberglass to match fiberglass fines. (Also deleted thecorresponding assumption that small and large pieces offiberglass can be treated as cubes for head losscalculations.)

o Corrected the macroscopic density of Microtherm fiberfrom 15 Ibm/ft3 to 2.4 Ibm/ft3.o Corrected the densities for Microtherm TiO2 and Si02,which were inadvertently switched in the previousrevisions.

o Corrected the size and S, for epoxy fines from 6 pIm to 6mils (152 pm).o Corrected the S, for epoxy chips, which was incorrectly calculated in previous revisions.

o Added justification for specific values used." Deleted discussion of initial pool chemistry, pool pH, and metalPage 4 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Revision Date Description quantity inputs from Section 2.2.* The assumptions that there would be no washdown transport forbreaks where sprays are not initiated, and that unqualified coatingswould wash down to the pool immediately if they fail while thesprays are still on were both deleted.* A new assumption was added that the transport fractions for anLBLOCA in the steam generator compartments can be used for allbreaks.* Updated the debris transport analysis section to more accurately describe specific transport fractions used in CASA Grande.* Deleted table of inputs for clean strainer head loss in Section 2.2and replaced it with the maximum value. Also updated the cleanstrainer head loss analysis section to specify that the maximumclean strainer head loss was used for all breaks.* Revised penetration parameters in Section 2.2 to show n in units ofmin-1 rather than a dimensionless variable.

Also deleted inaccurate equation in the debris penetration analysis section used to correctn from the test conditions to the plant conditions.

Edited assumption for hot leg switchover timing from 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months to arange from 5.75 to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months ." Added a note stating that a 5 minute time increment was used inCASA." Provided additional justification for the assumption that acombination of pumps failing in the same train is worse than thesame combination of pumps failing in separate trains." Modified assumption that spray erosion would occur prior to thestart of recirculation to also include pool erosion." Deleted assumption that the gas void at the pumps would beproportional to the pump flow split since the gas void fraction atthe strainers was assumed to be the same as the gas void fractionat the pumps." Deleted assumption regarding the effects of counter-current flowon debris buildup in the core." Clarified assumption on small break boron precipitation to statethat boron precipitation was not precluded for small breaks." Revised illustration of sump failure criteria in Section 4.2 to correctthe NPSH available equation.

" Revised description of CASA Grande to clarify that it was notPage 5 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Revision Date Description developed as a generic software

package, but was simply used asan evaluation tool for the STP risk-informed GSI-191 calculations.

Revised the description of the LOCA frequency analysis.

" Corrected the equation for the number of medium breaks sampledin the LOCA frequency analysis section." Deleted chemical effects analysis section.* Edited strainer head loss analysis section to clarify that a boundingclean strainer head loss value was used rather than a flow andtemperature dependent correlation.

Corrected typos in head loss correlation equations.

" Revised head loss equation for calculating the composite Sv valuefrom a geometric weighting by volume to a linear weighting bymass for consistency with the equation that was used in CASA." Deleted Froude number equation for vortex formation in the airintrusion analysis section.* Deleted inaccurate equation describing the split in void fractionbetween pumps in air intrusion analysis section." Added a note in the penetration analysis section to clarify that astrainer filtration efficiency of 100% was used for particulate debris." Added footnote in the in-vessel downstream effects analysissection stating that preliminary results from additional thermal-hydraulic modeling has indicated that siphon effects are possibleunder specific conditions.

Added description of the strainer loading table in the strainer headloss analysis section and an assumption that debris loads uniformly on the strainer.

Also added additional strainer geometry input toSection 2.2.* Replaced implicit friction factor equation in the strainer head lossanalysis section with an explicit form. Also added the piperoughness and suction pipe diameter input to Section 2.2." Added a note to the parametric evaluation section to explain thatthe parametric cases were not rerun based on the current changesto CASA and therefore should only be used for qualitative insights.

" Replaced example input deck in Appendix 1 with the new inputdecks." Other miscellaneous editorial changes.Two types of changes were made to the CASA Grande program to supportrequantification of conditional failure probabilities reported in this revision.

Page 6 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Revision I Date Description Changes involving the code structure or equation implementation wereverified to have either no effect or incidental effect by comparing resultsfrom a baseline calculation before and after the modification.

Changesinvolving input parameters were examined as sequential perturbations to abaseline calculation before adopting the entire suite for reevaluation.

Thecode changes to CASA Grande include:" Implemented parallel optimization to increase efficiency.

Created external input file to support batch runs." Optimized degasification routine for matrix evaluation.

" Pulled NPSH required out of subroutine and up to the user inputlevel for each pump type.* Corrected slopes of total injection flow rate to reflect change insummary table.* Corrected logic to allow one CS train off if and only if all threeactuate.* Removed alternate polynomial evaluation of saturation pressurefor degasification calculation and replaced with lookup table fromNIST.* Optimized NPSH routine for matrix evaluation.

Fixed error in passing relative roughness to Colebrook frictionequation caused by misinterpretation of published equation.

The input changes to CASA Grande include:* Corrected pump failure definition for Case 9 to model two LHSIpump failures rather than two HHSI pump failures.

Revised break-dependent SI pump flow rates to match corrected flow rates described in Section 2.2.* Revised CS flow rates to match ranges described in Section 2.2.* Increased sampling resolution to 20 LHS replicates and 15 Johnsonpercentiles from 3 and 5 respectively.

Incorporated new material properties (size and density) consistent with the changes to the strainer head loss analysis section.* Imposed a 100% failure fraction for unqualified coatings.

Changed the failure of unqualified coatings to introduce 100% ofthe transportable coatings at a constant rate over the first 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months ." Corrected recirculation transport fraction for epoxy fine chips(changed from 21% to 41%).t ~1-A A.Page 7 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table of ContentsRevision History Log ......................................................................................................................................

3Table of Contents

..........................................................................................................................................

8List of Figures ..............................................................................................................................................

11List of Tables ...............................................................................................................................................

14Definitions and Acronym s ...........................................................................................................................

161 Introduction

........................................................................................................................................

182 Design Input ........................................................................................................................................

242.1 General Description of Inputs Required

...............................................................................

242.2 Specific Inputs Used ....................................................................................................................

322.2.1 Tim ing for Key Plant Response Actions .........................................................................

322.2.2 Containm ent Geom etry ................................................................................................

332.2.3 LOCA Frequencies

.........................................................................................................

332.2.4 Pum p State Frequencies

................................................................................................

432.2.5 Pool W ater Level ............................................................................................................

452.2.6 Pool Tem perature

.........................................................................................................

452.2.7 Operating Trains ............................................................................................................

512.2.8 ECCS and CSS Flow Rates ................................................................................................

512.2.9 Qualified Coatings Quantity

...........................................................................................

542.2.10 Unqualified Coatings Quantity

.......................................................................................

542.2.11 Crud Debris Quantity

....................................................................................................

552.2.12 Latent Debris Quantity

...................................................................................................

562.2.13 M iscellaneous Debris Quantity

.......................................................................................

562.2.14 Insulation Zones of Influence

.........................................................................................

562.2.15 Insulation Debris Size Distribution

..................................................................................

562.2.16 Debris Characteristics

....................................................................................................

572.2.17 Blow dow n Transport Fractions

.......................................................................................

582.2.18 W ashdow n Transport Fractions

....................................................................................

592.2.19 Pool Fill Transport Fractions

...........................................................................................

602.2.20 Recirculation Transport Fractions

..................................................................................

602.2.21 Debris Erosion .....................................................................................................................

622.2.22 Strainer Geom etry .........................................................................................................

632.2.23 Clean Strainer Head Loss .................................................................................................

662.2.24 Pum p NPSH M argin .......................................................................................................

662.2.25 Strainer Structural M argin .............................................................................................

672.2.26 Vortex Air Ingestion

.......................................................................................................

672.2.27 Bubble Transport

...........................................................................................................

672.2.28 Pum p Gas Lim its ............................................................................................................

672.2.29 Fiberglass Penetration

..................................................................................................

67Page 8 of 248 South Texas Project Risk-informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI 191-V03Revision 22.2.30 Decay Heat Curve ................................................................................

692.2.31 Core Blockage Debris Limits.....................................................................

703 Assumptions..................................................................................................

714 Methodology

................................................................................................

834.1 GSI-191 Analysis Steps ................................................................................

874.2 Structured Information Process Flow................................................................

894.3 Uncertainty Quantification and Propagation........................................................

974.4 Verification and Validation

...........................................................................

975 Analysis

......................................................................................................

985.1 Evaluation Scenarios (PRA Branch Fractions to Populate)..........................................

985.2 Containment CAD Model............................................................................

1015.3 LOCA Frequency......................................................................................

1225.3.1 Relative Weight of Breaks in Specific Weld Categories

.....................................

1245.3.2 Weld Categories and Coordinates

............................................................

1275.3.3 Statistical Fit of NUREG-1829 LOCA Frequencies

............................................

1475.3.4 Sample Epistemic Uncertainty of LOCA Frequencies

........................................

1485.3.5 Sample Break Sizes at Each Weld Location...................................................

1495.4 Debris Generation....................................................................................

1515.4.1 701 Model .......................................................................................

1515.4.2 Insulation Debris Size Distribution Model....................................................

1555.4.3 Insulation Debris ...............................................................................

1565.4.4 Qualified Coatings Debris ......................................................................

1565.4.5 Unqualified Coatings Debris ...................................................................

1575.4.6 Latent Debris....................................................................................

1585.4.7 Miscellaneous Debris ..........................................................................

1585.4.8 Debris Characteristics..........................................................................

1585.5 Debris Transport

.....................................................................................

1585.5.1 Upstream Blockage.............................................................................

1585.5.2 Blowdown Transport

...........................................................................

1595.5.3 Washdown Transport

..........................................................................

1605.5.4 Pool Fill Transport..............................................................................

1605.5.5 Recirculation Transport

........................................................................

1605.5.6 Debris Erosion ..................................................................................

1615.5.7 Strainer Transport..............................................................................

1615.5.8 Time-Dependent Debris Arrival Model .......................................................

1735.6 Strainer Head Loss ...................................................................................

1745.6.1 Clean Strainer Head Loss.......................................................................

1745.6.2 Conventional Debris Head Loss Model .......................................................

1755.6.3 Chemical Debris Head Loss Model ............................................................

1865.6.4 Strainer Head Loss..............................................................................

191Page 9 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 25.6.5 Acceptance Criterion:

NPSH M argin M odule ....................................................................

1925.6.6 Acceptance Criterion:

Structural M argin ..........................................................................

1975.7 Air Intrusion

..............................................................................................................................

1975.7.1 Vortex Form ation ..............................................................................................................

1985.7.2 Degasification

....................................................................................................................

1985.7.3 Gas Transport and Accum ulation ......................................................................................

2035.7.4 Acceptance Criterion:

Pum p Gas Void Lim its ....................................................................

2065.8 Debris Penetration

....................................................................................................................

2065.9 Ex-Vessel Dow nstream Effects ..................................................................................................

2125.9.1 Pum p, Valve, Com ponent W ear ........................................................................................

2125.9.2 System and Com ponent Clogging/Blockage

.....................................................................

2135.10 In-Vessel Dow nstream Effects ..................................................................................................

2145.10.1 Fuel Rod Debris Deposition (LOCADM ) .............................................................................

2145.10.2 Core Blockage Scenarios

...................................................................................................

2155.10.3 Decay Heat Boil-Off Flow Rate ..........................................................................................

2235.10.4 Tim e-Dependent Core Debris Accum ulation ....................................................................

2255.10.5 Acceptance Criteria:

Debris Loads ....................................................................................

2265.11 Boron Precipitation

...................................................................................................................

2265.11.1 Tim e-Dependent Core Debris Accum ulation ....................................................................

2285.11.2 Acceptance Criteria:

Debris Loads ....................................................................................

2285.12 Param etric Evaluations

.............................................................................................................

2286 Results ...............................................................................................................................................

2327 Conclusions

.......................................................................................................................................

2428 References

........................................................................................................................................

243Appendix 1: CASA Grande Input Decks ......................................................................................................

1-1Page 10 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSl191-V03 Revision 2List of FiguresFigure 1.1 -CASA Grande input variables

.............................................................................................

21Figure 1.2 -CASA Grande calculation m odules ....................................................................................

22Figure 1.3 -CASA G rande link to PRA .....................................................................................................

23Figure 2.1.1 -Illustration of input variable relationships for debris generation analysis

.....................

27Figure 2.1.2 -Illustration of input variable relationships for strainer head loss analysis

.....................

29Figure 2.1.3 -Illustration of input variable relationships for gas intrusion analysis

.............................

30Figure 2.1.4 -Illustration of input variable relationships for core blockage and boron precipitation a n a ly sis ........................................................................................................................................................

3 1Figure 2.2.1- Temperature profiles implemented in CASA Grande .....................................................

46Figure 2.2.2 -Total SI flow rate vs. break size .......................................................................................

52Figure 2.2.3 -STP strainer Photo 1 (before protective grating was installed)

.......................................

64Figure 2.2.4 -STP strainer Photo 2 (after protective grating was installed)

..........................................

65Figure 2.2.5 -STP strainer Photo 3 .......................................................................................................

65Figure 2.2.6 -STP strainer Photo 4 .......................................................................................................

66Figure 4.1 -Example of realistic probability distribution for an input variable

.....................................

84Figure 4.2 -Risk-inform ed GSI-191 resolution path .............................................................................

86Figure 4.2.1 -Illustration of a hypothetical DEGB spherical ZOI truncated by a wall ...........................

91Figure 4.2.2 -Illustration of the processes local to the ECCS screen ...................................................

93Figure 4.2.3 -Illustration of the flow paths in the reactor vessel ........................................................

94Figure 4.2.4 -Illustration of sum p failure criteria

.................................................................................

95Figure 4.2.5 -Illustration of processes local to the strainer with a direct impact on the performance th re sh o ld s ...................................................................................................................................................

9 6Figure 5.2.1 -Cross-section of steam generator compartment with Loops B and C ...............................

102Figure 5.2.2 -Close-up view of steam generator compartment with Loops B and C ..............................

102Figure 5.2.3 -O perating deck (Elevation 68'-0") ......................................................................................

103Figure 5.2.4 -Piping and equipm ent (View 1) ..........................................................................................

104Figure 5.2.5 -Piping and equipm ent (View 2) ..........................................................................................

1 05Figure 5.2.6 -Steam generator compartment floor (Elevation 19'0") .....................................................

106Figure 5.2.7 -Plan view of containment floor (Elevation

-11'3") .............................................................

107Figure 5.2.8 -Isometric view of containment floor (Elevation

-11'3") ....................................................

108Figure 5.2.9 -Plan view of m ajor piping and equipm ent .........................................................................

109Figure 5.2.10 -Section view of RCS Loop D (left) and Loop A (right) .......................................................

110Figure 5.2.11 -Section view of RCS Loop D (left) and Loop C (right) .......................................................

111Figure 5.2.12 -Nukon insulation on piping, pressurizer, pumps, and heat exchangers

..........................

112Figure 5.2.13 -Thermal-Wrap insulation on steam generators

...............................................................

113Figure 5.2.14 -Microtherm insulation in secondary shield wall penetrations

........................................

114Figure 5.2.15 -Lead blankets on pipes .....................................................................................................

115Figure 5.2.16 -Welds representing potential LOCA break locations (View 1) .........................................

116Page 11 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.17 -Welds representing potential LOCA break locations (View 2) .........................................

116Figure 5.2.18 -Currently installed ECCS strainers

....................................................................................

117Figure 5.2.19 -Illustration of additional insulation modeled at hanger and valve locations

..................

118Figure 5.2.20 -Illustration of work points used to identify location of welds, hangers, and valves ....... 119Figure 5.2.21 -Exam ple of CAD model text data output .........................................................................

120Figure 5.2.22 -Concrete walls and floors exported from CAD model in STL format ...............................

121Figure 5.2.23 -Geometry of piping and equipment insulation in CASA Grande .....................................

122Figure 5.3.1 -Locations of Category 6B welds that were modeled .........................................................

130Figure 5.3.2 -Illustration of bounded Johnson fit for NUREG-1829 break frequencies

..........................

147Figure 5.3.3 -Illustration of LOCA frequency vs. break size for 62nd percentile

......................................

149Figure 5.3.4 -Example of non-uniform stratified sampling strategy for one weld case ..........................

151Figure 5.4.1 -Illustration of 17D Nukon ZOI for a 31" DEGB ...................................................................

153Figure 5.4.2 -Illustration of 17D Nukon ZOI for a 6" side-wall break ......................................................

154Figure 5.4.3 -Illustration of 17D Nukon ZOI for a 2" side-wall break ......................................................

154Figure 5.4.4 -Illustration of sub-zones used for fiberglass debris size distribution

................................

155Figure 5.4.5 -Distribution of potential fiberglass debris quantities

........................................................

156Figure 5.5.1 -Photograph of 30-inch vent hole in secondary shield wall ................................................

159Figure 5.5.2 -Logic tree for LDFG fines showing total transport fraction implemented for all breaks...

164Figure 5.5.3 -Logic tree for LDFG small pieces showing total transport fraction implemented for allb re a ks ........................................................................................................................................................

1 6 5Figure 5.5.4 -Logic tree for LDFG large pieces showing total transport fraction implemented for allb re a ks ........................................................................................................................................................

1 6 6Figure 5.5.5 -Logic tree for Microtherm fines showing total transport fraction implemented for allb re a ks ........................................................................................................................................................

1 6 6Figure 5.5.6 -Logic tree for crud fines showing total transport fraction implemented for all breaks .... 167Figure 5.5.7 -Logic tree for qualified coatings fines showing total transport fraction implemented for allb re a ks ........................................................................................................................................................

16 8Figure 5.5.8 -Logic tree for unqualified alkyd coatings fines showing total transport fractionim plem ented for all breaks .......................................................................................................................

169Figure 5.5.9 -Logic tree for unqualified epoxy coatings fines showing total transport fractionim plem ented for all breaks .......................................................................................................................

169Figure 5.5.10 -Logic tree for unqualified epoxy coatings fine chips showing total transport fractionim plem ented for all breaks .......................................................................................................................

170Figure 5.5.11 -Logic tree for unqualified epoxy coatings small chips showing total transport fractionim plem ented fo r all breaks .......................................................................................................................

170Figure 5.5.12 -Logic tree for unqualified epoxy coatings large chips showing total transport fractionim plem ented for all breaks .......................................................................................................................

171Figure 5.5.13 -Logic tree for unqualified epoxy coatings curled chips showing total transport fractionim plem ented fo r all breaks .......................................................................................................................

171Page 12 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.5.14 -Logic tree for unqualified IOZ coatings fines showing total transport fractionim plem ented fo r all breaks .......................................................................................................................

172Figure 5.5.15 -Logic tree for latent fines showing total transport fraction implemented for all breaks 172Figure 5.5.16 -Illustration of tim e-dependent transport

........................................................................

174Figure 5.6.1 -Circum scribed strainer dim ensions ....................................................................................

180Figure 5.6.3 -Exponential probability density function for chemical effects bump-up factors applied toS B LO C A s ....................................................................................................................................................

18 9Figure 5.6.4 -Exponential probability density function for chemical effects bump-up factors applied toM B LO C A s ...................................................................................................................................................

19 0Figure 5.6.5 -Exponential probability density function for chemical effects bump-up factors applied toLB LO C A s ....................................................................................................................................................

19 1Figure 5.6.6 -Typical sample of sump-strainer head loss histories generated under the assumption ofexponential chemical effects factor and artificial head-loss inflation

......................................................

192Figure 5.6.7 -Illustration of parameters that affect pump NPSH ............................................................

193Figure 5.6.8 -Schematic of STP ECCS sum p suction piping ......................................................................

195Figure 5.7.1 -Isom etric view of ECCS strainer

.........................................................................................

203Figure 5.7.2 -Cross-section view of ECCS strainer and sump pit .............................................................

204Figure 5.7.3 -Illustration of air bubble accumulation and venting ..........................................................

206Figure 5.8.1 -Illustration of direct passage and shedding

.......................................................................

207Figure 5.8.2 -Illustration of time-dependent parameters associated with debris accumulation on thestraine r and co re .......................................................................................................................................

20 8Figure 5.10.1 -Deposit growth process assumed by LOCADM when core is boiling (63) .......................

215Figure 5.10.2 -Illustration of RCS at STP ..................................................................................................

216Figure 5.10.3 -Large or medium hot leg break during cold leg injection with partial core blockage

..... 217Figure 5.10.4 -Large or medium hot leg break during hot leg injection

.................................................

219Figure 5.10.5 -Large or medium cold leg break during cold leg injection with partial core blockage

.... 220Figure 5.10.6 -Large or medium cold leg break during hot leg injection

................................................

221Figure 5.10.7- Sm all hot leg break during cold leg injection

...................................................................

222Figure 5.10.8 -Tim e-dependent boil-off flow rate ..................................................................................

225Figure 5.11.1 -Amorphous precipitate formation on heated surface (96) .............................................

227Figure 5.12.1 -STP ECCS strainer prior to upgrade ..................................................................................

229Figure 6.1 -Linear-linear interpolation of bounded Johnson extrema (solid) with non-uniform stratified random break-size profiles (dashed)

........................................................................................................

235Figure 6.2 -Empirical distribution of total failure probability for Case 43 (one train operable) based on15 discrete samples of the NUREG-1829 break-frequency uncertainty envelope

...................................

237Page 13 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2List of TablesTable 2.1.1 -General input variables used in multiple aspects of the analysis

.....................................

25Table 2.1.2 -Input variables used primarily in debris generation analysis

..........................................

25Table 2.1.3 -Input variables used primarily in strainer head loss analysis

..........................................

27Table 2.1.4 -Input variables used primarily in gas intrusion analysis

...................................................

29Table 2.1.5 -Input variables used primarily in fiber penetration and in-vessel effects analysis

..........

30Table 2.2.1 -Sum p sw itchover tim e .....................................................................................................

33Table 2.2.2 -NUREG-1829 PWR current-day LOCA frequencies and fitted Johnson parameters

...... 34Table 2.2.3 -Relative frequencies vs. break size for hot leg, SG inlet, and cold leg welds (Categories 1Ath ro u g h 3 B ) .................................................................................................................................................

3 5Table 2.2.4 -Relative frequencies vs. break size for cold leg and surge line welds (Categories 3C through4 D ) ...............................................................................................................................................................

3 6Table 2.2.5 -Relative frequencies vs. break size for pressurizer line welds (Categories 5A through 5F).. 37Table 2.2.6 -Relative frequencies vs. break size for pressurizer and small bore line welds (Categories 5Fth ro u g h 6 B ) .................................................................................................................................................

3 8Table 2.2.7 -Relative frequencies vs. break size for safety injection and recirculation line welds(Catego ries 7A thro ugh 7 F) .........................................................................................................................

39Table 2.2.8 -Relative frequencies vs. break size for safety injection and recirculation line welds(C atego ries 7F thro ugh 7L) ..........................................................................................................................

40Table 2.2.9 -Relative frequencies vs. break size for accumulator injection and CVCS line welds(Catego ries 7M thro ugh 8C) ........................................................................................................................

4 1Table 2.2.10 -Relative frequencies vs. break size for CVCS line welds (Categories 8D through 8F) .........

42Table 2.2.11 -Frequency of success pump combination states ..........................................................

43Table 2.2.12 -Range of water volumes implemented in CASA Grande ..............................................

45Table 2.2.13 -Temperature profiles implemented in CASA Grande ...................................................

46Table 2.2.14-Total SI flow rates .............................................................................

.........

51Table 2.2.15 -Containm ent spray flow rates .........................................................................................

54Table 2.2.16 -Quantity of qualified coatings debris .............................................................................

54Table 2.2.17 -Quantity and location of potentially transportable unqualified coatings debris ...........

55Table 2.2.18 -Unqualified epoxy debris size distribution

....................................................................

55Table 2.2:19 -Q uantity of latent debris ................................................................................................

56Table 2.2.20 -Input variables used primarily in debris penetration and core blockage analysis

...... 56Table 2.2.21 -M aterial properties of debris .........................................................................................

57Table 2.2.22 -Blowdown transport fractions according to break location

.........................................

59Table 2.2.23 -Washdown transport fractions according to spray initiation

.......................................

60Table 2.2.24 -Pool fill transport fractions according to break location

...............................................

60Table 2.2.25 -Recirculation pool transport fractions according to break size and location (insulation)

.. 61Table 2.2.26 -Recirculation transport fractions according to break size and location (coatings, latentd e b ris, crud , d irt/d ust) ................................................................................................................................

6 2Page 14 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.27 -ECCS sum p suction pipe diameters

...............................................................................

67Table 2.2.28 -Fitted filtration parameters for test module ..................................................................

68Table 2.2.29 -Fitted filtration parameters for each ECCS strainer

........................................................

68Table 2.2.30 -Fitted shedding param eters ...........................................................................................

69Table 2.2.31 -Decay heat generation rate based on 1979 ANS plus 2 sigma uncertainty

...................

69Table 3.1 -Strainer debris accumulation and approach velocity comparison

.....................................

75Table 3.2 -Strainer debris accumulation and approach velocity comparison for CS pump failures14

...... 75Table 3.3 -Core debris accumulation for various pump failures

..........................................................

76Table 5.1.1 -Bounding or representative cases for highest frequency pump combination states .........

100Table 5.3.1 -Description of w eld categories

............................................................................................

126Table 5.3.2 -Comparison of LOCA frequency report and CAD model pipe sizes and weld counts .........

128Table 5.3.3 -Weld data from component database and CAD model ......................................................

131Table 5.3.4 -Example calculation of LOCA frequencies vs. break size for 62nd Percentile

......................

148Table 5.5.1 -Blowdown transport fractions used in CASA Grande ..........................................................

159Table 5.5.2 -Washdown transport fractions used in CASA Grande ........................................................

160Table 5.5.3 -Pool fill transport fractions used in CASA Grande ...............................................................

160Table 5.5.4 -Recirculation transport fractions used in CASA Grande ......................................................

161Table 5.5.5 -Tim e-dependent transport

..................................................................................................

173Table 5.6.1 -Head loss characteristics for fibrous debris ........................................................................

179Table 5.6.2 -Head loss characteristics for non-fibrous debris .................................................................

179Table 5.6.3 -Strainer loading table ..........................................................................................................

181Table 5.6.4 -Exponential probability distribution parameters applied to chemical effects bump-upfactors for each LO CA category

................................................................................................................

188Table 5.7.1 -Semi-empirical correlation parameters to calculate Henry's constants in aqueous solvent(8 7 ) ............................................................................................................................................................

1 9 9Table 5.10.1 -Decay heat generation rate based on 1979 ANS plus 2 sigma uncertainty

......................

224Table 5.12.1 -Comparison of mean LBLOCA conditional failure probabilities before and after ECCSstraine r re placem ent' ...............................................................................................................................

23 1Table 6.1 -Mean LBLOCA conditional failure probabilities for five states of pump availability

..............

233Table 6.2 -Distribution of total conditional failure for LBLOCAs under Case 43 (single train operable) 236Table 6.3 -Cold leg split fractions conditioned on LOCA category for Case 43 .......................................

238Table 6.4 -Random itemization of 49 break events that lead to failure for plant state Case 43 ............

239Page 15 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Definitions and AcronymsARL Alden Research Laboratory BC Branch Connection BEP Best Efficiency PointB-F Bimetallic WeldsB-J Single Metal WeldsBWR Boiling Water ReactorCAD Computer Aided DesignCASA Containment Accident Stochastic AnalysisCCDF Complementary Cumulative Distribution FunctionCCW Component Cooling WaterCDF Core Damage Frequency CHLE Corrosion/Head Loss Experiments CS Containment SprayCSHL Clean Strainer Head LossCSS Containment Spray SystemCVCS Chemical Volume Control SystemD&C Design and Construction DefectsDEGB Double Ended Guillotine BreakDM Degradation Mechanism ECC Emergency Core CoolingECCS Emergency Core Cooling SystemEOP Emergency Operating Procedure EPRI Electric Power Research Institute ESF Engineered Safety FeatureFA Fuel AssemblyGL 08-01 Generic Letter 2008-01GSI-191 Generic Safety Issue 191HHSI High Head Safety Injection HLSO Hot Leg Switchover IGSCC Intergranular Stress Corrosion CrackingLBLOCA Large Break Loss of Coolant AccidentLDFG Low Density Fiberglass LERF Large Early Release Frequency LHS Latin Hypercube SamplingLHSI Low Head Safety Injection LOCA Loss of Coolant AccidentMBLOCA Medium Break Loss of Coolant AccidentNIST National Institute of Standards and Technology NPSH Net Positive Suction HeadPage 16 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2NRC Nuclear Regulatory Commission OD Outer DiameterPDF Probability Density FunctionPRA Probabilistic Risk Assessment PWR Pressurized Water ReactorPWROG Pressurized Water Reactor Owner's GroupPWSCC Primary Water Stress Corrosion CrackingRCS Reactor Coolant SystemRHR Residual Heat RemovalRI-ISI Risk-Informed In-Service Inspection RMI Reflective Metal Insulation RWST Refueling Water Storage TankSBLOCA Small Break Loss of Coolant AccidentSC Stress Corrosion SI Safety Injection SIR Safety Injection and Recirculation SRM Staff Requirements Memorandum STP South Texas ProjectSTPNOC South Texas Project Nuclear Operating CompanyTAMU Texas A&M University TF Thermal FatigueTGSCC Transgranular Stress Corrosion CrackingTSC Technical Support CenterUSI A-43 Unresolved Safety Issue A-43UT University of Texas (Austin)V&V Verification and Validation VF Vibration FatigueWCAP Westinghouse Commercial Atomic PowerZOI Zone of Influence Page 17 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSl191-V03 Revision 21 Introduction The emergency core cooling system (ECCS) and containment spray system (CSS) in a pressurized waterreactor (PWR) are designed to safely shutdown the plant following a loss of coolant accident (LOCA) inaccordance with 10CFR50.46.

The assurance of long term core cooling in PWRs following a LOCA has along history dating back to the Nuclear Regulatory Commission (NRC) studies of the mid 1980sassociated with Unresolved Safety Issue (USI) A-43. Results of the NRC research on boiling water reactor(BWR) ECCS suction strainer blockage of the early 1990s identified new phenomena and failure modesthat were not considered in the resolution of USI A-43. As a result of these concerns, Generic SafetyIssue (GSI) 191 was identified in September 1996 related to debris clogging of the ECCS sump suctionstrainers at PWRs. Although plants have taken steps to prevent strainer clogging (by increasing thescreen area, for example),

satisfactory closure of this issue has proved elusive due to long term coolingissues and the effect of chemical precipitates on head loss. Previous investigators have identified bounding scenarios using conservative inputs, methods, and acceptance criteria.

The acceptance criteriaare applied in a "pass/fail" fashion that ignores the risk significance.

That is, if the results are acceptable, the issue has been resolved.

Otherwise, it is necessary to either redo the analysis with partial relaxation of analytical conservatisms or perform additional plant modifications to ensure that the acceptance criteria are met.A sudden break in the reactor coolant system (RCS) piping at a PWR would result in a high energy, two-phase jet. Depending on the size and location of the break, it is possible for the jet to destroy a largequantity of insulation on nearby piping and equipment.

During the RCS blowdown phase, some of theinsulation debris may be blown to upper containment and some may be blown to lower regions of thecontainment.

Per plant design, the ECCS and CSS would be automatically initiated, drawing flow from the refueling water storage tank (RWST). The CSS would wash some debris from upper containment down to thecontainment floor. Debris on the containment floor could be transported by the high-velocity sheetingflow as the pool fills. Some debris may be transported into inactive cavities below the containment floor(such as the reactor cavity),

or directly to the ECCS sump strainers as the sump cavities fill. After theRWST has been depleted, the ECCS and CSS pumps would be automatically switched over torecirculation.

Some of the debris in the containment pool would be transported to the ECCS sumpswhere it would accumulate on the strainers.

Some of the fine debris (particulate and fiberglass fines)would penetrate (i.e., pass through) the strainer.

As debris collects on the strainer, the head loss across the strainer would rise. Corrosion of variouscontainment metals, and dissolution of insulation debris and other materials in the buffered andborated containment pool may result in the formation of chemical precipitates.

These precipitates canaccumulate on the strainer debris beds increasing the overall head loss. Some of the chemicalprecipitates may also penetrate the strainer.

If the head loss across the strainer exceeds either the netPage 18 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2positive suction head (NPSH) margin for the safety injection (SI) system, or the strainer structural margin, long-term core cooling may be compromised.

Debris that penetrates through the strainer can also cause downstream issues including blockage orwear of various downstream components, or more significantly blockage of the fuel channels within thereactor core.The assurance of long-term post-LOCA core cooling must be fully addressed as required by the NRC inGeneric Letter 2004-02 (1). All U.S. PWRs have worked through the required analyses using deterministic approaches.

In 2006, the NRC commissioners issued a staff requirements memorandum (SRM) directing the staff and industry to make a concerted effort to look at resolution of the GSI-191 issue holistically (2). This proved to be challenging since the analyses were performed using bounding methods.

Althoughthere were known conservatisms in the analyses, there was no method for quantifying the overallmargin associated with the conservatisms so that the effects of best-estimate assumptions could be putinto proper perspective and compared to the conservative assumptions to holistically determine theoverall level of margin.In 2010, due to the ongoing challenges of resolving GSI-191, the NRC commissioners directed the staff toconsider new and innovative resolution approaches (3). One of the approaches included in the SRM wasthe option of addressing GSI-191 using a risk-informed approach.

In 2011, South Texas Project (STP)initiated a three-year effort as a pilot plant to define and implement a risk-informed approach to resolveGSI-191.

An evaluation tool called CASA Grande5 was developed to analyze the accident sequences in arealistic time-dependent manner with uncertainty propagation to determine the probabilities of variousfailures potentially leading to core damage from a spectrum of location-specific pipe breaks (i.e., LOCAs)for input into STP's plant-specific probabilistic risk assessment (PRA). The specific failure modes thatneed to be considered are:1. Strainer head loss exceeds the NPSH margin for the pumps causing some or all of the ECCS andCSS pumps to fail.2. Strainer head loss exceeds the strainer structural margin causing the strainer to fail, which couldsubsequently result in larger quantities and larger sizes of debris being ingested into the ECCSand CSS.3. Air intrusion exceeds the limits of the ECCS and CSS pumps causing degraded pumpperformance or complete failure due to gas binding.4. Debris penetration exceeds ex-vessel effects limits causing a variety of potential equipment andcomponent failures due to wear or clogging.

5. Debris penetration exceeds in-vessel effects limits resulting in partial or full core blockage withinsufficient flow to cool the core.5CASA is an acronym for Containment Accident Stochastic AnalysisPage 19 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision

26. Buildup of oxides, crud, LOCA-generated debris, and chemical precipitates on fuel claddingexceeds the limits for heat transfer resulting in unacceptably high peak cladding temperatures.

7. Boron concentration in the core exceeds the solubility limit leading to boron precipitation andsubsequently resulting in unacceptable flow blockage or impaired heat removal.Failure Modes 4 and 6 have been conservatively addressed as part of the previous deterministic evaluation for STP with no issues of concern (see Sections 5.9 and 5.10.1),

and are therefore notexplicitly modeled in CASA Grande. The remaining failure modes are explicitly modeled.This report provides a full description of the STP CASA Grande analysis including the input parameters, assumptions, methodology, and results.

It also provides a description of the limited parametric evaluations that have been performed.

Figure 1.1 and Figure 1.2 illustrate the input variables and analytical modules used for CASA Grande, andFigure 1.3 illustrates the link between CASA Grande and the PRA.Page 20 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2General Inputs" Accident lime" Pool Water Level" Containment Pressure" Pool Temperature

" Operating Trains" Spray Flow Rate" Injection Flow Rate* Sump Flow RateDebris Generation Inouts" LOCA Frequency

Insulation Location" Unqualified CoatingsLocation/Failure

" Latent Debris Quantity" Miscellaneous DebrisQuantity" Destruction Pressure" Size Distribution

" Debris DensityDebris Transport Inputs" Blowdown Transport

" Washdown Transport

Pool Fill Transport

" Recirculation Transport

" Debris Erosion-U -IDebris Penetration I CASA Grande" Filtration Efficiency

" Shedding Parameters I--1--I-IIStrainer Head Loss Inouts" Strainer Dimensions

" Strainer Area" Strainer Interstitial Volume" Clean Strainer HeadLoss" Chemical Effects HeadLoss" NPSH Margin" Structural MarginJ,ICore Blockage InputsCore Fiber LimitsAir Intrusion InputsPump Gas LimitsIBoron Precipitation Inputs" Boil-off Rate" Core Fiber LimitsFigure 1.1 -CASA Grande input variables Page 21 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2CASA Grandei-----------------------------------------------------------------------------------

Figure 1.2 -CASA Grande calculation modulesPage 22 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2PRA Confituration FailureFrequencies

" S/M/L Breaks" Train/Pump Failure-~~~~ ---------------------

'4-CASA GrandeStrainer Head Loss Air Intrusion

Pump Failure (Exceed Pump Failure (ExceedNPSH Margin) Pump Gas Void Limits) I* Strainer Failure (ExceedStructural Margin)Core Blockaze Boron Precioitation Core Damage

Core Damage(Insufficient Core Flow) (Insufficient Core Flow)Pass/Fail Analysis* Compare results to acceptance criteria to determine failure event distributions

Organize results in S/M/L categories for input in PRA4%PRA Conditional FailureProbabilities and Initiating Event Freauencies

S/M/L Breaks-Train/Pump FailureFigure 1.3 -CASA Grande link to PRAPage 23 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 22 Design InputA wide range of input variables are used in the various GSI-191 analysis areas. In some cases, the inputmay consist of a single value, in other cases the input may have a probability distribution or change overtime. Some inputs must be entered into CASA Grande as part of the input deck (e.g., containment pooltemperature profiles),

while other inputs may be calculated within CASA Grande (e.g., strainer head loss,which is directly calculated and then used as an input for the degasification calculation).

Section 2.1provides a general description of the relationship between the various input parameters, and Section2.2 provides a description of the actual inputs used in the STP analysis.

The detailed analyses required to develop each of the design inputs are described in the referenced documents in Section 2.2. The majority of the significant input variables that were developed as part ofthe STP risk-informed GSI-191 evaluation project were developed under the following topical areas:* Containment CAD Model (4)* Thermal Hydraulics Modeling (5; 6)* LOCA Frequency Evaluation (7; 8; 9)* Jet Formation Modeling (10)* Coatings and Crud Debris Calculations (11; 12; 13)* Water Volume/Level Calculation (14)* Chemical Effects Testing (15; 16; 17; 18; 19; 20; 21; 22)* Debris Transport Calculation (23)" Strainer Head Loss Testing (24)" NPSH Calculation (25)* Strainer Penetration Testing (26; 27; 28)* In-vessel Effects Evaluation (29)2.1 General Description of Inputs RequiredTable 2.1.1 through Table 2.1.5 list the design input variables that go into a GSI-191 evaluation.

Theyalso show the relationship between other input and output variables, and whether the conservative direction is represented by a high or low value. Note that in many cases, input values may affectmultiple outputs where in one situation it is conservative to assume a low value and in another situation it is conservative to assume a high value. Figure 2.1.1 through Figure 2.1.4 illustrate how the variousinput variables tie together in CASA Grande.Page 24 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.1.1 -General input variables used in multiple aspects of the analysisDesign Input Conservative Preceding Direct-Input Proceeding Direct- CommentsVariable Direction Variables Output Variables Accident Time N/A N/A Unqualified CoatingsFailure, Spray Flow Rate,Sump Flow Rate, StrainerAccumulation, Containment Temperature, FiberPenetration, Boil-off FlowRate, Core Accumulation Break Location N/A LOCA Frequency Debris Quantity, DebrisSize Distribution, CoreAccumulation Break Size '1 LOCA Frequency Pool Temperature, ZOISize, Injection Flow RatePool Water Break Size Pool Water Level, StrainerVolume Accumulation Pool Water ' Pool Water Volume NPSH Available, Level Degasification Containment Pool Temperature, NPSH Available, Pressure Accident Time Degasification Pool Break Size, Accident Chemical Precipitation, Temperature Time Strainer Head Loss, NPSHAvailable, Degasification Operating 13/4J, N/A Spray Flow Rate, Injection Pumps Flow Rate, Sump FlowRateSpray Flow Rate Operating Pumps, Sump Flow Rate, CoreAccident Time Accumulation Injection Flow '" Operating Pumps, Sump Flow Rate, CoreRate Break Size Accumulation Sump Flow Rate Spray Flow Rate, Strainer ApproachInjection Flow Rate Velocity, NPSH Available, Degasification, FiberPenetration Table 2.1.2 -Input variables used primarily in debris generation analysisDesign Input Conservative Preceding Direct-Input Proceeding Direct- CommentsVariable Direction Variables Output Variables LOCA 1" N/A Break Location, BreakFrequency SizeInsulation N/A N/A Debris Quantity, SizeLocation Distribution Qualified

' N/A Debris QuantityCoatingsQuantityPage 25 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Design Input Conservative Preceding Direct-Input Proceeding Direct- CommentsVariable Direction Variables Output Variables Unqualified

'1' N/A Debris QuantityCoatingsQuantityUnqualified N/A N/A Debris Transport CoatingsLocationUnqualified 1 Accident Time Debris Quantity, DebrisCoatings Failure Transport Latent Debris '1 N/A Debris QuantityQuantityMiscellaneous

'1 N/A Debris QuantityDebris QuantityDestruction

' N/A ZOI SizePressureZOI Size 1" Break Size, Destruction Debris QuantityPressureDebris Size Break Location, Debris Transport, StrainerDistribution Insulation Location Head LossDebris Density N/A Strainer Head Loss Head loss increases with highermacroscopic densityand lower microscopic densityDebris Quantity

'1' Break Location, Strainer Accumulation Insulation

Location, ZOISize, Qualified CoatingsQuantity, Unqualified Coatings

Failure, LatentDebris Quantity, Miscellaneous DebrisQuantityPage 26 of 248 South Texas Project Risk-informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI 191-V03Revision 2Debris Generation AnalysisCASA Grande Inputs]I CASA Grande Calculations IJt) = function of accident timeFigure 2.1.1 -Illustration of input variable relationships for debris generation analysisTable 2.1.3 -Input variables used primarily in strainer head loss analysisDesign Input Conservative Preceding Direct-Input Proceeding Direct- CommentsVariable Direction Variables Output Variables Strainer Height I' N/A Degasification Strainer Area N/A Debris Bed Thickness, Strainer ApproachVelocity, FiberPenetration Strainer N/A Debris Bed Thickness, Interstitial Strainer AreaVolumeDebris '1 Debris Size Distribution, Strainer Accumulation Transport Unqualified CoatingsLocation, Unqualified Coatings FailurePage 27 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Design Input Conservative Preceding Direct-Input Proceeding Direct- CommentsVariable Direction Variables Output Variables Strainer T" Debris Quantity, Debris Debris Bed Thickness, Accumulation Transport, Sump Flow Fiber Penetration, Rate, Pool Volume, Strainer ApproachAccident Time VelocityDebris Bed Strainer Accumulation, Strainer Head LossThickness Strainer Area, StrainerInterstitial VolumeChemical

'1 Pool Temperature Strainer Head LossPrecipitation Strainer

'" Sump Flow Rate, Strainer Head LossApproach Strainer Area, StrainerVelocity Accumulation Clean Strainer

'1 N/A Strainer Head LossHead LossStrainer Head '" Pool Temperature, Degasification, SumpLoss Strainer Approach FailureVelocity, Clean StrainerHead Loss, Debris BedThickness, Debris SizeDistribution, ChemicalPrecipitation NPSH Required

'1 Degasification NPSH MarginNPSH Available 4 Pool Water Level, NPSH MarginContainment

Pressure, Pool Temperature, Sump Flow RateNPSH Margin , NPSH Required, NPSH Sump Failure Acceptance criterion Available compared againststrainer head lossStructural 4 N/A Sump Failure Acceptance criterion Margin compared againststrainer head lossPage 28 of 248 South Texas Project Risk-informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Strainer Head Loss AnalysisI CASA Grande InputsI CASA Grande Calculations I.f(t) = function of accident timeFigure 2.1.2 -Illustration of input variable relationships for strainer head loss analysisTable 2.1.4 -Input variables used primarily in gas intrusion analysisDesign Input Conservative Preceding Direct-Input Proceeding Direct- CommentsVariable Direction Variables Output Variables Degasification 1' Strainer Height, Pool NPSH Required, SumpWater Level, FailureContainment

Pressure, Pool Temperature, Sump Flow Rate,Strainer Head LossPump Gas , N/A Sump Failure Acceptance criterion Limits compared against gasvoid fractionPage 29 of 248 South Texas Project Risk-informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Gas Intrusion AnalysisI CASA Grande Inputs ICASA Grande Calculations f(t) = function of accident timeI Strainer Head Lossf(t) iSump Flow Ratef(t),

Pool Water Level,Strainer Height,Pool Temperaturef (t),Containment Pressuref(t),

h 8"IDegasif ication_!:(t)

I"Pump Gas LimitsSump Failure f(t)Figure 2.1.3 -Illustration of input variable relationships for gas intrusion analysisTable 2.1.5 -Input variables used primarily in fiber penetration and in-vessel effects analysisDesign Input Conservative Preceding Direct-Input Proceeding Direct- CommentsVariable Direction Variables Output Variables Fiber 1' Sump Flow Rate, Core Accumulation Penetration Strainer Accumulation, Strainer Area, AccidentTimeBoil-off Flow 1' N/A Core Accumulation RateCore '1' Break Location, Spray Core Blockage, BoronAccumulation Flow Rate, Injection Precipitation Flow Rate, Boil-off FlowRate, Fiber Penetration, Accident TimePage 30 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Design Input Conservative Preceding Direct-Input Proceeding Direct- CommentsVariable Direction Variables Output Variables Core Blockage 1 Core Accumulation In-Vessel Failure Core accumulation compared to coreblockage acceptance criteriaBoron Core Accumulation In-Vessel Failure Core accumulation Precipitation compared to boronprecipitation acceptance criteriaCore Blockage and Boron Precipitation AnalysisCASA Grande Inputs ICASA Grande Calculations

_f(t) = function of accident time Strainer AccurnSpray Flow Rate f(t),Injection Flow Rate,Boil-off Flow Ratef (t)Figure 2.1.4 -Illustration of input variable relationships for core blockage and boron precipitation analysisPage 31 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 22.2 Specific Inputs UsedThis section documents the specific design inputs used in the CASA Grande analysis.

The actual inputdecks are provided in Appendix 1.2.2.1 Timing for Key Plant Response ActionsThere are a number of automated or proceduralized plant response actions that would occur following aLOCA event. The timing for these actions is important for the GSI-191 evaluation since the timing canhave a significant impact on a variety of phenomena.

Immediately after a LOCA, several things wouldoccur: 1) the pressure in the accumulators ranges from 590 psig to 670 psig (30), so the accumulators would not inject their inventory unless the RCS pressure drops below approximately 600 psig, 2) theLHSI and HHSI pumps would start injecting water from the RWST into the cold legs after the RCSpressure drops below the shutoff head, and 3) the CS pumps would start injecting water from the RWSTinto the containment spray headers if the containment pressure rises above 9.5 psig (31). Note that forbreaks smaller than 2-inches, the accumulators would not inject since the RCS pressure would not dropbelow 600 psig before the accumulators are secured, and the sprays would not be initiated since thecontainment pressure would not rise above 9.5 psig (5).Other important longer-term actions include:* Securing one CS pump if all three CS pumps are successfully initiated

Securing all CS pumps later in the event* Switchover to ECCS sump recirculation after the RWST has been drained* Switchover to hot leg injection Per procedure, if all three trains of containment spray are successfully initiated, one of the three pumpswould be manually secured (32; 33). Since this is a continuous action step that is intended to conservethe RWST, the third train of containment spray would be secured early in the event prior to switchover to recirculation.

In general, the remaining two trains of sprays would be on for a minimum of 6.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months for medium andlarge breaks. The termination criteria are 1) up to 6.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months has passed since the beginning of the event,2) containment pressure has dropped below 6.5 psig, 3) the iodine levels are low enough to support the30-day habitability limits, and 4) the Technical Support Center (TSC) staff has agreed that the sprays canbe terminated (34). Typically, the pressure will drop below 6.5 psig in less than an hour (5), and theiodine levels would be relatively low given that there is no core damage early in the LOCA event.According to the STP operators (35), the decision to terminate containment sprays would probably bemade as soon as the pressure drops below 6.5 psig (well before reaching 6.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months ). However, 6.5 hour5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months swas used as a reasonably conservative time for securing containment sprays.Page 32 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2The timing for switchover to recirculation is dependent on the volume of water in the RWST and thetotal ECCS and CSS flow rate. Table 2.2.1 shows the sump switchover timing as a function of break size6(5).Table 2.2.1 -Sump switchover timeBreak Size Sump Switchover Sump Switchover (in) Time (S)7 Time (min)1.5" 20,239 3372" 4,750 794" 3,353 566" 2,653 448" 2,268 3812" 1,873 3127.5" DEGB 1,773 30Switchover to hot leg injection is started 5.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months after the beginning of the event (32; 36). As discussed in Assumption 2.j, the switchover steps are assumed to be completed between 5.75 and 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months afterthe beginning of the event.2.2.2 Containment GeometryContainment geometry data includes potential break locations (i.e., pipe welds), insulation quantities and locations, robust barrier locations, etc. This information is included in the STP containment computer aided design (CAD) model, which has been formally

prepared, reviewed, and approved for usein safety-related applications (4).Additional description of the CAD model is provided in Section 5.2.2.2.3 LOCA Frequencies The LOCA frequency input for CASA Grande is taken from two sources-a top-down evaluation of theoverall frequencies for different break sizes, and a bottom-up evaluation of the relative frequencies atvarious locations based on specific degradation mechanisms (DMs). The overall frequencies for different 6This is based on best-estimate conditions where all pumps are available.

However, these results can beconservatively applied to scenarios where some pumps fail to start since a reduction in the overall ECCS and CSSflow rates would delay sump switchover, thereby delaying strainer head loss and core blockage as the pump NPSHmargin increases and the required core flow rate decreases.

7 Note that the switchover time in seconds is consistent with the results of the thermal-hydraulic calculation dataspreadsheets.

However, the thermal-hydraulic report (5) presents the values in units of minutes or hours, whichintroduces some rounding error.Page 33 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2break sizes are based on the values provided in NUREG-1829 (37), which were fit using a boundedJohnson distribution as shown in Table 2.2.2 (8).Table 2.2.2 -NUREG-1829 PWR current-day LOCA frequencies and fitted Johnson parameters Size NUREG-1829 Quantiles Fitted Johnson Parameters (in) 5th Median Mean 95th y 6 A0.5 6.80E-05 6.30E-04 1.90E-03 7.10E-03 1.650950 5.256964E-01 4.117000E-05 1.420E-02 1.625 5.00E-06 8.90E-05 4.20E-04 1.60E-03 1.646304 4.593913E-01 2.530000E-06 3.200E-03 28 3.69E-06 6.57E-05 3.10E-04 1.18E-03 1.646308 4.593851E-01 1.870000E-06 2.361E-03 3 2.10E-07 3.40E-06 1.60E-05 6.10E-05 1.646605 4.589467E-01 1.200000E-07 1.220E-04 6.30E-08 1.08E-06 5.20E-06 1.98E-05 1.646403 4.566256E-01 3.000000E-08 3.965E-05 7 1.40E-08 3.10E-07 1.60E-06 6.10E-06 1.645739 4.487957E-01 6.023625E-09 1.220E-05 14 4.10E-10 1.20E-08 2.00E-07 5.80E-07 1.645211 3.587840E-01 2.892430E-10 1.160E-06 31 3.50E-11 1.20E-09 2.90E-08 8.10E-08 1.645072 3.343493E-01 2.636770E-11 1.600E-07 The relative frequencies of breaks in various weld locations are based on specific DMs for categories ofwelds as shown in Table 2.2.3 through Table 2.2.10 (7). There are a total of 45 different categories thatare considered.

Note that several of the values in this table were based on logarithmic interpolation ofthe adjacent values. Since linear interpolation was used for the other portions of the LOCA frequency evaluation (see Assumption 3.d and Assumption 3.e), the logarithmically interpolated values werefiltered out and not used in the evaluation.

Additional details on the LOCA Frequencies are provided in Section 5.3.8 The quantiles are not explicitly defined in NUREG-1829 for 2-inch and 6-inch breaks. However, these values werelinearly interpolated from the 1-5/8-inch, 3-inch, and 7-inch break categories.

The fitted Johnson parameters weredetermined using the same optimization process that was used for the original set of data in NUREG-1829 (8).Page 34 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1291-V03 Revision 2Table 2.2.3 -Relative frequencies vs. break size for hot leg, SG inlet, and cold leg welds (Categories 1A through 3B)Category 1A 1B iC 2 3A 3BSystem Hot Leg Hot Leg Hot Leg SG Inlet Cold Leg Cold LegPipe Size (in) 29 29 29 29 27.5 31DEGB (in) 41.01 41.01 41.01 41.01 38.89 43.84Weld Type B-F B-J B-J B-F B-F B-FDM SC, D&C D&C TF, D&C SC, D&C SC, D&C SC, D&CNo. Welds 4 11 1 4 4 4Break Size, Break Size, Break Size, Break Size, Break Size, Break Size,X (in) F(LOCAIX)

X (in) F(LOCA X (in) F(LOcAX)

X (in) F(LOCAX)

X (in) F(LOcAIX) 0.50 4.02E-07 0.50 1.95E-09 0.50 1.25E-08 0.50 1.98E-06 0.50 1.51E-07 0.50 1.51E-071.50 9.25E-08 1.50 4.49E-10 1.50 2.87E-09 1.50 4.59E-07 1.50 3.43E-08 1.50 3.43E-082.00 6.92E-08 2.00 3.36E-10 2.00 2.15E-09 2.00 3.45E-07 2.00 2.38E-08 2.00 2.38E-083.00 4.61E-08 3.00 2.24E-10 3.00 1.43E-09 3.00 2.31E-07 3.00 1.42E-08 3.00 1.42E-084.00 3.19E-08 4.00 1.55E-10 4.00 9.90E-10 4.00 1.60E-07 4.00 9.49E-09 4.00 9.49E-096.00 1.89E-08 6.00 9.19E-11 6.00 5.89E-10 6.00 9.52E-08 6.00 5.39E-09 6.00 5.39E-096.75 1.61E-08 6.75 7.83E-11 6.75 5.01E-10 6.75 8.12E-08 6.75 4.53E-09 6.75 4.53E-0914.00 7.O1E-09 14.00 3.40E-11 14.00 2.18E-10 14.00 3.35E-08 14.00 2.01E-09 14.00 2.01E-0920.00 3.70E-09 20.00 1.80E-11 20.00 1.15E-10 20.00 1.81E-08 20.00 1.15E-09 20.00 1.15E-0929.00 1.90E-09 29.00 9.24E-12 29.00 5.92E-11 29.00 9.57E-09 27.50 6.96E-10 27.50 6.96E-1031.50 1.64E-09 31.50 7.97E-12 31.50 5.11E-11 31.50 8.30E-09 31.50 5.63E-10 31.50 5.63E-1041.01 1.04E-09 41.01 5.03E-12 41.01 3.22E-11 41.01 5.24E-09 38.89 4.12E-10 43.80 3.38E-10Page 35 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Table 2.2.4 -Relative frequencies vs. break size for cold leg and surge line welds (Categories 3C through 4D)Category 3C 3D 4A 4B 4C 40System Cold Leg Cold Leg Surge Line Surge Line Surge Line Surge LinePipe Size (in) 27.5 31 16 16 16 2.5DEGB (in) 38.89 43.84 22.63 22.63 22.63 3.54Weld Type B-J B-J B-F B-J BC B-JDM D&C D&C SC, TF, D&C TF, D&C TF, D&C TF, D&CNo. Welds 12 24 1 1 7 2 6Break Size, Break Size, Break Size, F(LOC>) Break Size, Break Size, F(LOC>X)

Break Size, F(LOCAX)X (in) F(LOCA>X)

X (in) F(LOCA>X)

X (in) FO > X (in) F(LOCAX)

X (in) X (in)0.50 2.79E-09 0.50 2.79E-09 0.50 9.75E-06 0.50 7.44E-08 0.50 1.21E-07 0.50 7.44E-081.50 6.33E-10 1.50 6.33E-10 1.50 3.30E-06 1.50 2.52E-08 1.50 4.11E-08 1.50 2.52E-082.00 4.39E-10 2.00 4.39E-10 2.00 2.43E-06 2.00 1.85E-08 2.00 3.02E-08 2.00 1.85E-083.00 2.62E-10 3.00 2.62E-10 3.00 1.58E-06 3.00 1.20E-08 3.00 1.97E-08 3.00 1.20E-084.00 1.75E-10 4.00 1.75F-10 4.00 1.03E-06 4.00 7.82E-09 4.00 1.28E-08 3.54 9.42E-096.009.95E-11 6.009.95E-11 6.005.58E-07 6.004.26E-09 6.006.94E-096.75 8.36E-11 6.75 8.36E-11 6.75 4.68E-07 6.75 3.57E-09 6.75 5.82E-0914.00 3.70E-11 14.00 3.70E-11 14.00 1.18E-07 14.00 9.03E-10 14.00 1.47E-0920.00 2.11E-11 20.00 2.11E-11 16.00 9.19E-08 16.00 7.02E-10 16.00 1.15E-0927.50 1.28E-11 27.50 1.28E-11 20.00 6.14E-08 20.00 4.69E-10 20.00 7.65E-1031.50 1.04E-11 31.50 1.04E-11 22.63 4.77E-08 22.63 3.64E-10 22.63 5.93E-1038.897.60E-12 43.806.23E-12Page 36 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.5 -Relative frequencies vs. break size for pressurizer line welds (Categories 5A through 5F)Category 5A 5B SC 5D 5E 5FSystem Pressurizer Pressurizer Pressurizer Pressurizer Pressurizer Pressurizer Pipe Size (in) 6 3 4 3 6 6DEGB (in) 8.49 4.24 5.66 4.24 8.49 8.49Weld Type B-J B-J B-J B-J B-i B-FDM TF, D&C TF, D&C D&C D&C D&C SC, TF, D&CNo. Welds 29 14 53 4 29 0Break Size, Break Size, Break Size, Break Size, Break Size, Break Size,X (in) F(LOCAIX)

X (in) F(LOcAX)

X (in) F(LOCAX)

I X (in) F(LOCAIX) 0.50 4.59E-08 0.50 4.59E-08 0.50 1.72E-08 0.50 1.72E-08 0.50 1.72E-08 0.50 5.09E-060.75 2.76E-08 0.75 2.76E-08 0.75 1.03E-08 0.75 1.03E-08 0.75 1.03E-08 0.75 3.06E-061.00 1.96E-08 1.00 1.96E-08 1.00 7.33E-09 1.00 7.33E-09 1.00 7.33E-09 1.00 2.17E-061.50 1.24E-08 1.50 1.24E-08 1.50 4.64E-09 1.50 4.64E-09 1.50 4.64E-09 1.50 1.38E-062.00 6.64E-09 2.00 6.64E-09 2.00 2.49E-09 2.00 2.49E-09 2.00 2.49E-09 2.00 7.36E-073.00 2.75E-09 3.00 2.75E-09 3.00 1.03E-09 3.00 1.03E-09 3.00 1.03E-09 3.00 3.05E-074.24 1.30E-09 4.24 1.30E-09 4.24 4.87E-10 4.24 4.87E-10 4.24 4.87E-10 4.24 1.44E-075.666.006.758.496.26E-105.47E-104.16E-102.64E-105.66 1 2.34E-105.662.34E-10 1 5.666.94E-086.00 2.05E-10 6.00 6.06E-086.75 1.56E-10 6.75 4.61E-088.49 9.89E-11 8.49 2.93E-08Page 37 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Table 2.2.6 -Relative frequencies vs. break size for pressurizer and small bore line welds (Categories 5F through 6B)Category 5G 5H 51 5J 6A 6BSystem Pressurizer Pressurizer Pressurizer Pressurizer Small Bore Small BorePipe Size (in) 6 6 4 2 2 1DEGB (in) 8.49 8.49 5.66 2.83 2.83 1.41Weld Type B-F B-F BC B-J B-J B-JDM SC, D&C D&C (Weld Overlay)

D&C TF, D&C VF, SC, D&C VF, SC, D&CNo. Welds _ _0 4 2 2 16 193Break Size, Break Size, Break Size, Break Size, Break Size, Break Size,X (in) F(LOCA>X)

X (in) F(LOCA>X)

X (in) F(LOCA>)

X (in) F(LOCA>X)

X (in) F(LOCA?>X)

X (in) F(LOCA>X) 0.50 5.01E-06 0.50 1.74E-08 0.50 1.72E-08 0.50 4.59E-08 0.50 1.22E-06 0.50 1.22E-060.75 3.01E-06 0.75 1.05E-08 0.75 1.03E-08 0.75 2.76E-08 0.75 7.18E-07 0.75 7.18E-071.00 2.13E-06 1.00 7.42E-09 1.00 7.33E-09 1.00 1.96E-08 1.00 5.00E-07 1.00 5.OOE-071.50 1.35E-06 1.50 4.70E-09 1.50 4.64E-09 1.50 1.24E-08 1.40 3.30E-07 1.40 3.30E-072.007.24E-07 1 2.002.52E-09 2.002.49E-09 1 2.006.64E-09 1 1.503.08E-073.00 3.OOE-07 3.00 [ 1.04E-09 1 3.00 1.03E-09 2.83 3.13E-09 1.99 [ 1.75E-074.24 1 1.42E-07 1 4.244.94E-10 1 4.244.87E-105.66 6.83E-08 5.66 2.37E-10 5.66 2.34E-102.00 1.73E-072.80 8.66E-086.005.96E-08 1 6.002.07E-106.75 4.54E-08 6.75 1.58E-108.49 2.88E-08 8.49 1.0OE-10Page 38 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.7 -Relative frequencies vs. break size for safety injection and recirculation line welds (Categories 7A through 7F)Category 7A 7B 7C 7D 7E 7FSystem SIR SIR SIR SIR SIR SIRPipe Size (in) 12 8 8 12 12 10DEGB (in) 16.97 11.31 11.31 16.97 16.97 14.14Weld Type B-J B-J B-J B-J BC, B-J B-JDM TF, D&C TF, D&C SC, TF, D&C SC, D&C D&C D&CNo. Welds 21 9 3 3 57 30Break Size,X (in)Break Size, Break Size,F(LOCa>X)

X (in) F(LOcA>X)

X (in)F(LOCAMX)

Break Size,X (in)F(LOCAX)

Break Size, F(LOC>X)

Break Size,I X (in) I X (in)F(LOCA>X) 0.50 2.78E-06 0.50 2.78E-06 0.50 3.10E-06 0.50 3.54E-07 0.50 1.14E-08 0.50 1.14E-080.75 1.67E-06 0.75 1.67E-06 0.75 1.861-06 0.75 2.12E-07 0.75 6.84E-09 0.75 6.84E-091.00 1.18E-06 1.00 1.18E-06 1.00 1.32E-06 1.00 1.51E-07 1.00 4.85E-09 1.00 4.85E-091.50 7.48E-07 1.50 7.48E-07 1.50 8.34E-07 1.50 9.54E-08 1.50 3.07E-09 1.50 3.07E-092.00 4.01E-07 2.00 4.01E-07 2.00 4.48E-07 2.00 5.12E-08 2.00 1.65E-09 2.00 1.65E-092.83 1.67E-07 2.83 1.67E-07 2.83 1.86E-07 2.83 2.13E-08 2.83 6.85E-10 2.83 6.85E-104.00 8.50E-08 4.00 8.50E-08 4.00 9.48E-08 4.00 1.08E-08 4.00 3.49E-10 4.00 3.49E-104.24 7.41E-08 4.24 7.41E-08 4.24 8.26E-08 4.24 9.45E-09 4.24 3.04E-10 4.24 3.04E-105.66 3.79E-08 5.66 3.79E-08 5.66 4.23E-08 5.66 4.84E-09 5.66 1.56E-10 5.66 1.56E-106.00 3.31E-08 6.00 3.31E-08 6.00 3.70E-08 6.00 4.23E-09 6.00 1.36E-10 6.00 1.36E-106.75 2.52E-08 6.75 2.52E-08 6.75 2.81E-08 6.75 3.22E-09 6.75 1.04E-10 6.75 1.04E-107.20 2.22E-08 7.20 2.22E-08 7.20 2.48E-08 7.20 2.83E-09 7.20 9.12E-11 7.20 9.12E-118.49 1.60E-08 8.49 1.60E-08 8.49 1.79E-08 8.49 2.04E-09 8.49 6.58E-11 8.49 6.58E-1110.00 1.16F-08 10.00 1.16E-08 10.00 1.29E-08 10.00 1.47E-09 10.00 4.75E-11 10.00 4.75E-1111.31 9.11E-09 11.31 9.11E-09 11.31 1.02E-08 11.31 1.16E-09 11.31 3.74E-11 11.31 3.74E-1114.14 5.93E-0916.97 4.05E-0914.147.56E-1014.142.44E-1114.142.44E-1116.975.16E-1016.971.66E-11Page 39 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.8 -Relative frequencies vs. break size for safety injection and recirculation line welds (Categories 7F through 7L)Category 7G 7H 71 71 7K 7LSystem SIR SIR SIR SIR SIR SIRPipe Size (in) 8 6 4 3 2 1.5DEGB (in) 11.31 8.49 5.66 4.24 2.83 2.12Weld Type BC, B-J B-J BC BC BC B-JDM D&C D&C D&C D&C D&C D&CNo. Welds 42 23 5 9 10 0Break Size, Break Size,X (in) I X (in)I Break Size, I Break Size, Break Size, Break Size, IF(LOCAX)

(in) I F(LOCA x ( ) F(LOcAX)

(in) F(LOcAX)

(n) F(LOAX)0.50 1.14E-08 0.50 1.14E-08 0.50 1.14E-08 0.50 1.14E-08 0.50 1.14E-08 0.50 1.14E-080.75 6.84E-09 0.75 6.84E-09 0.75 6.84E-09 0.75 6.84E-09 0.75 6.84E-09 0.75 6.84E-091.00 4.85E-09 1.00 4.85E-09 1.00 4.85E-09 1.00 4.85E-09 1.00 4.85E-09 1.00 4.85E-091.50 3.07E-09 1.50 3.07E-09 1.50 3.07E-09 1.50 3.07E-09 1.50 3.07E-09 1.50 3.07E-092.00 1.65E-09 2.00 1.65E-09 2.00 1.65E-09 2.00 1.65E-09 2.00 1.65E-09 2.00 1.65E-092.836.85E-10 2.836.85E-10 2.836.85E-10 2.836.85E-10 2.836.85E-10+ f 4 + 44.003.49E-10 1 4.003.49E-10 1 4.003.49E-10 1 4.003.49E-104.24 3.04E-10 3 4.24 3.04E-10 4.24 1 3.04E-10 4.24 3.04E-105.661.56E-10 5.661.56E-10 1 5.661.56E-106.001.36E-10 1 6.001.36E-106.75 1.04E-10 6.75 1.04E-107.20 9.12E-11 7.20 9.12E-118.49 6.58E-11 8.49 6.58E-1110.00 4.75E-1111.31 3.74E-11Page 40 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Table 2.2.9 -Relative frequencies vs. break size for accumulator injection and CVCS line welds (Categories 7M through 8C)Category 7M 7N 70 8A 8B 8CSystem ACC ACC ACC CVCS CVCS CVCSPipe Size (in) 12 12 12 2 4 2DEGB (in) 16.97 16.97 16.97 2.83 5.66 2.83Weld Type B-J B-J BC, B-J B-J B-J B-JDM SC, D&C TF, D&C D&C TF, VF, D&C TF, VF, D&C VF, D&CNo. Welds 0 35 15 10 19 47Break Size,X (in)F(LOCAZX)

Break Size, F(LOCAX)

Break Size,I X (in) I O I X (in)F(LOCA Break Size, F(LOCX) Break Size, F(LOCAM)

Break Size, F(LOCAX)I X (in) X(in) X (in)0.50 3.54E-07 0.50 5.18E-08 0.50 6.26E-09 0.50 4.28E-08 0.50 4.28E-08 0.50 1.87E-080.75 2.12E-07 0.75 3.11E-08 0.75 3.75E-09 0.75 2.57E-08 0.75 2.57E-08 0.75 1.12E-081.00 1.51E-07 1.00 2.21E-08 1.00 2.66E-09 1.00 1.82E-08 1.00 1.82E-08 1.00 7.97E-091.50 9.54E-08 1.50 1.40E-08 1.50 1.69E-09 1.50 1.15E-08 1.50 1.15E-08 1.50 5.04E-092.00 5.12E-08 2.00 7.49E-09 2.00 9.04E-10 2.00 6.03E-09 2.00 6.03E-09 2.00 2.64E-092.83 2.13E-08 2.83 3.12E-09 2.83 3.76E-10 3.00 2.42E-09 3.00 2.42E-09 3.00 1.06E-094.001.08E-08 1 4.001.67E-09 1 4.002.02E-104.24 9.45E-09 5.66 7.09E-10 5.66 8.55E-115.66 4.84E-09 6.00 6.19E-10 6.00 7.47E-116.00 4.23E-09 6.80 4.71E-10 6.80 5.69E-116.75 3.22E-09 7.20 4.14E-10 7.20 5.OOE-117.20 2.83E-09 10.00 2.16E-10 10.00 2.61E-118.49 2.04E-09 14.14 1.11E-10 14.14 1.34E-1110.00 1.47E-09 16.97 7.56E-11 16.97 9.12E-124.00 1.26E-095.66 5.77E-1011.3114.1416.971.16E-097.56E-105.16E-10Page 41 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.10 -Relative frequencies vs. break size for CVCS line welds (Categories 8D through 8F)Category 8D 8E 8FSystem cvcS Cvcs CvCsPipe Size (in) 4 4 4DEGB (in) 5.66 5.66 5.66Weld Type B-J BC BCDM VF, D&C TF, D&C D&CNo. Welds 1 6 4 1Break Size, Break Size, Break Size,X (in) F(LOCX) I X (in) F(LOAX) I X (in)0.50 1.87E-08 0.50 7.98E-08 0.50 1.87E-080.75 1.12E-08 0.75 4.79E-08 0.75 1.12E-081.00 7.97E-09 1.00 3.40E-08 1.00 7.97E-091.50 5.04E-09 1.50 2.15E-08 1.50 5.04E-092.00 2.64E-09 2.00 1.12E-08 2.00 2.64E-093.00 1.06E-09 3.00 4.51E-09 3.00 1.06E-094.00 5.49E-10 4.00 2.34E-09 4.00 5.49E-105.66 2.52E-10 5.66 1.08E-09 5.66 2.52E-10Page 42 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 22.2.4 Pump State Frequencies The frequency of various pump state combinations was determined based on the STP PRA model asshown in Table 2.2.11 (38). Note that these frequencies are based on the PRA without considering failure related to GSI-191 phenomena.

Only sequences ending in success, as opposed to core damage,are included in the pump combination state frequencies since only those sequences are candidates totransition to core damage when GSI-191 failure phenomena are considered.

Table 2.2.11 -Frequency of success pump combination statesPump StateCase Working Working Working Frequency HHSI Pumps LHSI Pumps CS Pumps (Fear.1)1 3 3 3 2.64E-042 3 3 2 3.32E-063 3 3 1 7.53E-084 3 3 0 9.77E-095 3 2 3 3.49E-066 3 2 2 4.38E-087 3 2 1 9.80E-108 3 2 0 1.25E-109 3 1 3 3.22E-0810 3 1 2 3.95E-1011 3 1 1 7.59E-1212 3 1 0 9.85E-1313 3 0 3 <1E-1414 3 0 2 <1E-1415 3 0 1 <1E-1416 3 0 0 <1E-1417 2 3 3 1.94E-0618 2 3 2 2.44E-0819 2 3 1 5.39E-1020 2 3 0 6.95E-1121 2 2 3 1.17E-0722 2 2 2 9.16E-0623 2 2 1 7.81E-0824 2 2 0 1.19E-0925 2 1 3 7.65E-1026 2 1 2 6.03E-0827 2 1 1 4.93E-1028 2 1 0 6.16E-12Page 43 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Case Working Working Working Pump StateHHSI Pumps LHSI Pumps CS Pumps (yeareu)29 2 0 3 <1E-1430 2 0 2 <1E-1431 2 0 1 <1E-1432 2 0 0 <1E-1433 1 3 3 2.67E-0834 1 3 2 3.26E-1035 1 3 1 6.18E-1236 1 3 0 8.02E-1337 1 2 3 6.43E-1038 1 2 2 3.54E-0839 1 2 1 2.84E-1040 1 2 0 3.01E-1241 1 1 3 9.96E-1242 1 1 2 1.63E-0943 1 1 1 4.34E-0844 1 1 0 1.76E-1045 1 0 3 <1E-1446 1 0 2 <1E-1447 1 0 1 <1E-1448 1 0 0 <1E-1449 0 3 3 5.84E-1150 0 3 2 6.24E-1351 0 3 1 <1E-1452 0 3 0 <1E-1453 0 2 3 4.92E-1354 0 2 2 3.50E-1155 0 2 1 <1E-1456 0 2 0 <1E-1457 0 1 3 <1E-1458 0 1 2 <1E-1459 0 1 1 3.89E-1160 0 1 0 <1E-1461 0 0 3 <1E-1462 0 0 2 <1E-1463 0 0 1 <1E-1464 0 0 0 <1E-14Page 44 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSl191-V03 Revision 22.2.5 Pool Water LevelThe active water volume is based on the total volume of water in containment (from the RWST, RCS, andaccumulators) minus any water sequestered in inactive regions.

The pool volume is equal to the activewater volume minus the transitory water volume (i.e., water circulating through the ECCS and CSSpiping, containment sprays falling through the air or migrating down to the pool, condensation on wallsand other surfaces, water still in the RCS, etc.). These values were calculated at bounding conditions asshown in Table 2.2.12 (14), and the pool volume for small, medium, and large breaks was sampled inCASA Grande based on these ranges.Table 2.2.12 -Range of water volumes implemented in CASA GrandeMinimum Maximum VolumeBreak Size Volume (ft3) (ft3)LBLOCA 45,201 69,263MBLOCA 39,533 69,444SBLOCA 43,464 61,993The pool water level is calculated using the following equation:

HP° Apool Equation 1where:H,, = Height above the containment floor at Elevation

-11'3"VPoo, = Pool volumeAp= Pool areaThe area of the pool at STP is 12,301 ft2 (14).2.2.6 Pool Temperature The pool temperature profiles were determined for different break sizes based on thermal-hydraulic modeling.

The temperature profiles for breaks that are 6 inches and larger have a similar trends, and thelarger breaks have a higher peak temperature early in the event and then drop down to a lower overalltemperature later in the event (5).Page 45 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2The 6-inch break temperature profile was used to represent all small and medium breaks and the 27.5-inch DEGB temperature profile was used to represent all large breaks (see Assumption 1.k). The 6-inchbreak temperature profile was based on an extended simulation that went out to 30 days, and the 27.5-inch DEGB temperature profile was logarithmically extrapolated from 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months to 30 days as described in Assumption 1.1. The two temperature profiles that were used in the CASA evaluation are shown inFigure 2.2.1 and Table 2.2.13 (5). Note that the initial temperature transient prior to the start ofrecirculation is not shown in Figure 2.2.1 since temperature only affects models that are important afterthe start of recirculation (e.g., the NPSH model).Pool Temperature Profiles200180160pY14012010080-6-inch Break-27.5-inch DEGB6040 "0.1I10Time (hr)1001000Figure 2.2.1 -Temperature profiles implemented in CASA GrandeTable 2.2.13 -Temperature profiles implemented in CASA GrandeTemperature for Temperature forTime (hr) 6-inch Break 27.5-inch DEGB(OF) (*F)0 119.6 119.81130.0847 131.2987 213.9295Page 46 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Temperature for Temperature forTime (hr) 6-inch Break 27.5-inch DEGB(OF) (OF)0.0864 140.1689 242.31040.0881 150.3314 255.02680.0897 156.124 255.79070.0914 159.2343 253.16170.0931 162.1567 252.93720.0947 164.568 252.5390.0964 166.6937 251.90230.0981 168.5685 250.97330.0997 170.2457 249.71690.1014 171.7175 245.88940.1031 172.9577 235.98560.1047 174.0415 224.00510.1064 174.957 212.94950.1081 175.7084 203.54990.1097 176.3081 195.72250.1139 177.5299 179.58940.1306 164.4935 199.80480.1472 132.7076 174.81430.1639 124.0848 174.82760.1806 123.6914 177.35180.1972 123.5988 180.74050.2139 123.5641 183.23330.2306 123.5529 185.16440.2472 124.4938 186.49250.2639 127.6399 187.25790.2806 129.7484 187.8270.2972 131.0391 188.19240.3139 149.8002 188.42660.3306 158.2393 188.56050.3472 162.7694 188.59340.3639 165.496 188.50420.3806 167.3851 188.33750.3972 168.6688 189.31870.4139 169.7687 189.7570.4306 170.9814 189.09230.4472 171.9993 188.52020.4639 172.8771 188.01480.4806 173.715 187.56210.4972 174.4595 187.41030.5139 175.0903 187.06710.5306 175.6074 186.733Page 47 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Temperature for Temperature forTime (hr) 6-inch Break 27.5-inch DEGB(*F) (*F)0.5472 176.0061 186.42490.5639 176.2923 186.15590.5806 176.4625 186.7640.5972 176.4855 186.50120.6139 176.3916 186.25570.6306 176.2055 186.05550.6472 175.9468 185.91190.6639 175.6184 185.82650.6806 175.2411 185.80620.6972 174.8243 185.84950.7139 174.3902 185.95260.7306 173.9374 186.10920.7472 173.4284 187.89000.7639 172.8459 187.96730.7806 172.2319 187.91960.7972 171.6143 187.91190.8139 171.0143 187.93850.8306 170.4548 187.99540.8472 169.9507 188.07100.8639 169.5034 188.16470.8806 169.1086 188.25380.8972 168.7661 188.33850.9139 168.4824 188.40030.9306 168.2551 189.09960.9472 168.0847 188.91990.9639 167.9707 188.74390.9806 167.9020 188.56140.9972 167.8705 188.36221.0139 167.8665 188.13141.0306 167.8947 187.85971.0472 167.9451 187.53871.0639 168.0131 187.16671.0806 168.0978 186.75591.3611 170.0607 178.40911.6944 170.9606 171.87622.0278 171.4105 166.54212.3611 170.8721 162.22382.6944 169.8110 158.14103.0278 168.7942 154.98183.3611 168.1132 151.76733.6944 165.3090 148.9234Page 48 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSl191-V03 Revision 2Temperature for Temperature forTime (hr) 6-inch Break 27.5-inch DEGB(OF) (OF)4.0278 164.1228 146.08344.3611 163.0112 143.79674.6944 161.4436 141.60545.0278 159.9385 139.52515.3611 158.1298 137.98925.6944 158.4517 136.48196.0278 156.5706 134.88656.3611 151.6937 136.90006.6944 163.7090 136.64897.0278 160.9624 135.35697.3611 158.1118 134.31037.6944 156.1579 133.29418.0278 154.6151 132.44538.3611 153.2333 131.94678.6944 151.9641 132.05369.0278 150.8191 132.19159.3611 149.7667 131.30559.6944 148.7924 130.794610.0278 147.8649 130.276520.0833 136.208 123.048932.0833 129.023 118.199144.0833 124.979 114.909556.0833 122.145 112.417068.0833 120.131 110.409680.0833 118.471 108.729092.0833 117.316 107.2834104.0833 116.498 106.0152116.0833 115.616 104.8855128.0833 114.710 103.8671140.0833 113.896 102.9399152.0833 113.173 102.0890164.0833 112.521 101.3027176.0833 111.924 100.5720188.0833 111.358 99.8894200.0833 110.859 99.2491212.0833 110.393 98.6461224.0833 109.993 98.0763236.0833 109.577 97.5362248.0833 109.209 97.0229260.0833 108.910 96.5339272.0833 108.593 96.0669Page 49 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Temperature for Temperature forTime (hr) 6-inch Break 27.5-inch DEGB(°F) (OF)283.3333 108.281 95.6474297.2222 107.968 95.1520308.3333 107.710 94.7720319.4444 107.473 94.4055333.3333 107.162 93.9649344.4444 106.943 93.6254355.5556 106.715 93.2967369.4444 106.477 92.9000380.5556 106.250 92.5932391.6667 106.124 92.2953402.7778 105.893 92.0057416.6667 105.666 91.6547427.7778 105.541 91.3822438.8889 105.316 91.1168452.7778 105.193 90.7942463.8889 105.069 90.5432475.0000 104.844 90.2982488.8889 104.725 89.9998500.0000 104.607 89.7671511.1111 104.377 89.5396525.0000 104.366 89.2620536.1111 104.140 89.0452547.2222 104.023 88.8328561.1111 103.905 88.5733572.2222 103.791 88.3703583.3333 103.673 88.1712597.2222 103.566 87.9276608.3333 103.452 87.7368619.4444 103.335 87.5494633.3333 103.145 87.3198644.4444 103.100 87.1398655.5556 102.913 86.9628669.4444 102.868 86.7457680.5556 102.681 86.5753691.6667 102.645 86.4076702.7778 102.525 86.2427716.6667 102.516 86.0401CASA Grande evaluates water properties by using the current pool temperature to enter a lookup tablebased on the National Institute of Standards and Technology (NIST) reference property database (39).Page 50 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 22.2.7 Operating TrainsIn the event of a LOCA, all three trains of ECCS would be automatically initiated due to a safety injection actuation signal and would begin to draw flow from the RWST (40). As discussed in Section 2.2.1, thethree trains of CS would also be automatically initiated if the containment pressure rises above 9.5 psig.If all three CS pumps start successfully, operators would (per procedure) manually secure one of thethree CS pumps (33). Once the RWST has been drained down to the Lo-Lo RWST level, the recirculation mode of ECCS and CS operation would be automatically initiated through the three ECCS sumps (40).A variety of train or pump failure combinations are possible (many of which go beyond traditional designbasis analyses).

This is discussed in more detail in Section 5.1.2.2.8 ECCS and CSS Flow RatesThe maximum flow rates per train are 2,800 gpm for the low head safety injection (LHSI) flow (41), 1,620gpm for the high head safety injection (HHSI) flow (41), and 2,600 gpm for the containment spray (CS)flow (41). This gives a maximum total sump flow of 7,020 gpm per train. The maximum total flow ratesare only possible for LBLOCA conditions.

For SBLOCA conditions, containment sprays would not beinitiated due to the small increase in containment pressure (5), the LHSI may not inject due to high RCSpressure, and the HHSI flow rate would vary from 0 gpm to 1,620 gpm per train depending on the actualsize of the break and number of trains operating.

For MBLOCA conditions, the sprays would be initiated, but the combined LHSI and HHSI flow would range up to 4,420 gpm per train (41) depending on theactual size of the break. Table 2.2.14 provides a summary of the total SI flow rates for different breaksizes based on thermal-hydraulic modeling9 (5).Table 2.2.14-Total SI flow ratesBreak Size Nominal Total SI(in) Flow (gpm)1.55" 1,2312" 2,0764" 4,1206" 7,9518" 10,28515" 11,78027.5" DEGB 11,988The data in Table 2.2.14 is plotted in Figure 2.2.2 with the 27.5-inch DEGB plotted with the equivalent break size of 38.9 inches. As shown in this figure, the SI flow rate can be approximated using two linear9 These flow rates are based on simulations using nominal operating conditions (i.e., all ECCS trains operating, allfan coolers operating, and nominal CCW heat exchanger temperatures).

Page 51 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2curves (see Equation 2). The reason that the slope changes for breaks greater than approximately 9inches is that the break size is large enough for the LHSI and HHSI pumps to operate at essentially maximum capacity.

For smaller breaks, the reduced break size causes back-pressure in the RCS thatlimits the total SI pump flow.Sl Flow Rate14,000 --.. ............y = 8.7063x+

1164912,000R2=

110,00012,000

__y = 1247.2x /(9.41 in, 11,731 gpm)1 8,000 R2 =0.97254,0002,0130 5 10 15 20 25 30 35 40 45 50Briak Sol ze (in)Figure 2.2.2 -Total SI flow rate vs. break sizeQTsJ = 1,247.2 gpm/in

DbreakQrsI = 8.706gp/1in' Dbreak + 11,649gpm if Dbreak < 9.41 inif Dbreak > 9.41 inEquation 2where:QTS, = Total SI flow rate (combined LHSI and HHSI pump flow rates from all trains)Dbreak = Break diameter (equivalent break diameter for DEGB)Page 52 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Note, however, that the total SI flow rate cannot be greater than the maximum capacity of theoperating pumps. Therefore, the following criterion is defined for the total SI flow rate based on amaximum LHSI pump flow rate of 2,800 gpm, and a maximum HHSI pump flow rate of 1,620 gpm (41):QTSI <- 2,800gpm

NLHSI + 1,620gpm

NHHSI Equation 3where:NLHSI = Number of operating LHSI pumpsNHHSI = Number of operating HHSI pumpsFor any given scenario, the flow rate for individual SI pumps within each train can be estimated based ona ratio of the maximum pump capacities, as well as the number of LHSI and HHSI pumps that arerunning (assuming at least one LHSI pump and one HHSI pump are running).

This is shown in thefollowing equations:

QLHSJ = QTSI2,800gpm

]t 2,80gpm NLHSI + 1,620gpm.

NHHsJI [. 1,620gpm IEquation 4Equation 5HHS1 T12,800gpm

-NLHS, + 1,620gpm

-NHHS,]where:QLHSI = LHSI pump flow rate for an individual trainQHHSI = HHSI pump flow rate for an individual trainIf containment sprays are initiated, the flow rate is not dependent on the size of the break. However, itwould vary depending on the number of trains in operation.

As discussed above, the maximum sprayflow rate for a single train is 2,600 gpm. If all three trains are operating, the maximum flow rate isapproximately 2,060 gpm per train (41). If two trains are operating, the maximum flow rate isapproximately 2,350 gpm per train (42). The minimum probable CS flow rates are approximately 1,657gpm per train for three train operation and 1,932 gpm per train for two train operation (42). Theminimum spray flow rate for one train operation was not available in STP documentation, but wasassumed to be 80% of the maximum flow rate consistent with the range of flow rates for two and threetrain operation (see Assumption 1.i). This gives a minimum spray flow rate of 2,080 gpm for single trainoperation.

Table 2.2.15 provides a summary of the range of containment spray flow rates.Page 53 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.15 -Containment spray flow ratesNumber of Operating Minimum Spray Maximum SprayNmray ofupe Flow per Train Flow per TrainSpray Pumps (gpm) (gpm)One Train 2,080 2,600Two Trains 1,932 2,350Three Trains 1,657 2,0602.2.9 Qualified Coatings QuantityThe total quantity of qualified coatings debris is a function of break size, location, surface area of coatedconcrete and steel within the ZOI, and coating thickness.

The quantity of qualified coatings debrisgenerated was conservatively calculated for four break sizes as shown in Table 2.2.16 (11). The breaksizes include a 2-inch break, a 6-inch break, a 15-inch break, and a 31-inch double-ended guillotine break(DEGB). The results can be conservatively applied for breaks in any location that are less than or equal tobreak sizes listed (e.g., the 15-inch quantities can be used for any breaks between 6 and 15 inches indiameter).

To simplify the evaluation,

however, the quantity of qualified coatings debris for a 31-inchDEGB was applied to all breaks.Table 2.2.16 -Quantity of qualified coatings debris'031-inch DEGB 15-inch Break 6-inch Break 2-inch BreakQuantity (Ibm) Quantity (Ibm) Quantity (Ibm) Quantity (Ibm)Qualified Epoxy 105 25 3 0Qualified IOZ 39 3 0 02.2.10 Unqualified Coatings QuantityThe total quantity and locations of potentially transportable unqualified coatings are shown in Table2.2.17 (12). Note that these coatings are listed as potentially transportable since unqualified coatings inupper containment would not transport if they fail after containment sprays are secured, and10 Note that some breaks analyzed had a slightly higher quantity of qualified epoxy or IOZ coatings (11). However,this table presents the maximum combined quantity of qualified epoxy and IOZ coatings debris for each break size.The most significant difference in the results of the qualified coatings calculation is that the bounding crossover legbreak has 105 Ibm epoxy + 39 Ibm IOZ (144 Ibm total) compared to the bounding cold leg break with 129 Ibm epoxy +8 Ibm IOZ (137 Ibm total) (11). These two breaks represent the bounding quantities of qualified epoxy and IOZdebris for all other breaks. The epoxy and IOZ debris quantities from the crossover leg break were selected for thisevaluation since this represents the maximum total quantity of qualified coatings debris. It is possible thatadjusting the quantity of epoxy up by 24 Ibm and the quantity of IOZ down by 31 Ibm could make the answer slightlyworse since the density of epoxy is lower than the density of IOZ, and lower density has a conservative effect onhead loss. However, since the bounding LBLOCA coatings debris quantities were used for all breaks, the overalltreatment of qualified coatings is very conservative.

Page 54 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2unqualified coatings in the reactor cavity would not transport for breaks outside the reactor cavity. Thisis discussed in more detail in Section 2.2.20 and Section 5.5. The percentages shown in Table 2.2.17were calculated based on the quantity in each location divided by the total quantity.

Table 2.2.17 -Quantity and location of potentially transportable unqualified coatings debrisUpper Lower Reactor TotalCoatings Type Containment Containment Cavity Quantity (Ibm)Quantity (Ibm) Quantity (Ibm) Quantity (Ibm)Unqualified Epoxy 295 (15%) 36 (2%) 1,574 (83%) 1,905Unqualified IOZ 305 (83%) 64 (17%) 0 (0%) 369Unqualified Alkyd 146 (54%) 125 (46%) 0 (0%) 271Unqualified Baked Enamel 0 (0%) 267 (100%) 0 (0%) 267Unqualified Intumescent 0 (0%) 2 (100%) 0 (0%) 2The quantity of unqualified coatings debris that transports to the strainers is dependent on the failurefraction and failure timing. It is possible that some unqualified coatings would experience significantly less than 100% failure.

For example, the unqualified epoxy in the reactor cavity at STP is actually aqualified coatings system, and would likely remain fully intact under post-LOCA conditions.

However,these coatings are conservatively assumed to be unqualified due to higher radiation exposure (12). All ofthe unqualified coatings were conservatively assumed to have a failure fraction of 100%. Theintumescent coatings are assumed to be negligible (see Assumption 4.c). The unqualified coatings failuretiming shows that approximately 6% of the unqualified coatings would fail in the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months (12).The unqualified alkyd and IOZ coatings would fail as fines, but the unqualified epoxy coatings would failin the distribution shown in Table 2.2.18 (12).Table 2.2.18 -Unqualified epoxy debris size distribution Size Designation Size Range Percentage of Total Mass(inches)Fines (particles) 0.006 12.28%Flat Fine Chips 0.0156 37.23%Flat Small Chips 0.125-0.5 9.43%Flat Large Chips 0.5-2.0 20.53%Curled Chips 0.5-2.0 20.53%2.2.11 Crud Debris QuantityThe maximum quantity of RCS crud debris that would be released in a LOCA is 24 Ibm (13).Page 55 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 22.2.12 Latent Debris QuantityThe total quantity of latent debris is shown in Table 2.2.19 (43).Table 2.2.19 -Quantity of latent debris2.2.13 Miscellaneous Debris QuantityThe total quantity of unqualified tags, labels, plastic signs, tie wraps, etc. at STP is bounded by a totalsurface area of 100 ft2 (43).2.2.14 Insulation Zones of Influence The insulation zones of influence (ZOls) used for this analysis are based on the standard deterministic approach described in NEI 04-07 Volumes 1 and 2, where the ZOI size for each type of insulation is basedon the destruction pressure (44; 45). Table 2.2.20 lists the ZOI sizes for each type of insulation at STP.Table 2.2.20 -Input variables used primarily in debris penetration and core blockage analysisZOI Radius/ Reference Insulation Type Break DiameterTransco RMI 2.0 (45)Unjacketed Nukon, 17.0 (45)Jacketed Nukon with standard bandsThermal-Wrap; assumed to be the same 17.0 (45)as Nukon (see Assumption 1.d)Microtherm; assumed to be the same as 28.6 (45)Min-K (see Assumption 4.a)2.2.15 Insulation Debris Size Distribution The debris size distribution used for low density fiberglass (LDFG) insulation (Nukon and Thermal-Wrap) is based on a proprietary methodology report where debris that is generated closest to the breakconsists of a larger fraction of fines and small pieces, and debris generated at the outer portion of theZOI consists of a larger fraction of large pieces and intact blankets.

The fiberglass size distribution thatwas implemented in CASA Grande is shown in Table 4.1 of the Alion debris size distribution report (46).Page 56 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2The Microtherm debris was assumed to fail as 100% fines, but was split into the following categories based on the manufacturing data: 58% SiO2, 39% TiO2, and 3% fibers (43).2.2.16 Debris Characteristics Table 2.2.21 provides the material properties (size and density) for insulation (43; 46; 45), qualified coatings (11; 43), unqualified coatings (12), crud (13), and latent debris (43) at STP.Table 2.2.21 -Material properties of debrisDebris Type Debris Size Macroscopic Microscopic Density DensityFines: 7 Ipm fibersSmall Pieces: <6 inchesNukon Large Pieces: >6 inches 2.4 lbm/ft3 175 lbaft3Jacketed Large Pieces: IntactBlanketsFines: 7 pm fibersSmall Pieces: <6 inchesThermal-Wrap Large Pieces: >6 inches 2.4 Ibmlft3 159 Ibm/ft3Jacketed Large Pieces: IntactBlanketsFines: 6 pm fibers 165 Ibm/ft3Microtherm Fines: 20 pIm Si02 particles 15 Ibm/ft3 137 Ib Jft3Fines: 2.5 pm TiO2 particles 262 Ibm/ft3Qualified Epoxy Fines: 10 pmn particles 94 Ibm/ft3Qualified IOZ Fines: 10 pIm particles

-208 Ibm/ft3Fines: 6 mil particles Fine Chips: 0.0156"x15 milUnqualified Epoxy Small Chips: 0.125"-0.5"x15 mil -124 Ibm/ft3Large Chips: 0.5"-2.0"x15 milCurled Chips: 0.5"-2.0"x15 milUnqualified Alkyd Fines: 4 -20 pm particles

-207 Ibm/ft3Unqualified IOZ Fines: 4 -20 pm particles

-244 Ibm/ft3Unqualified Baked Enamel Fines: 4 -20 pm particles

-93 Ibm/ft3Crud Fines: 8 -63 pm particles

-325 -556 Ibm/ft3Latent Fiber Fines: 7 pm fibers 2.4 lbm/ft3 175 lbm/ft3Dirt/Dust Fines: 17.3 pm particles

-169 lbm/ft3Page 57 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 22.2.17 Blowdown Transport Fractions The blowdown transport fractions were calculated based on the break location, size of debris, upper andlower containment

volumes, and the locations of grating.

The appropriate blowdown transport fractions are shown for each break location and debris size in Table 2.2.22 (23).The types of debris that would be subject to the blowdown forces include Nukon, Microtherm, qualified

coatings, and crud. As discussed in Section 5.4.2, the Nukon debris would fail as fines, small pieces, largepieces, and intact blankets.

The Microtherm, qualified

coatings, and crud debris would all fail as finedebris and would transport similar to the Nukon fines. Since the intact blankets would not transport

readily, this debris was not included in the transport analysis (see Assumption 6.a).Based on the weld locations and transport potential, all LOCA breaks were binned in the following location categories:

1. Steam generator compartments:

Weld locations inside the secondary shield wall aboveElevation 19'-0".2. Reactor cavity: Weld locations inside the primary shield wall.3. Below Steam Generator Compartments:

Weld locations inside the secondary shield wall belowElevation 19'-0".4. Pressurizer compartment:

Weld locations inside the pressurizer compartment (excluding thesurge line).5. Pressurizer surge line: Weld locations on the surge line outside the secondary shield wall.6. RHR compartments:

Weld locations inside the RHR compartments.

7. Annulus:

Weld locations in the annulus (excluding the surge line).Page 58 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.22 -Blowdown transport fractions according to break locationDebris Type and Blowdown Transport Fractions Break Location Size Upper Lower Remaining inContainment Containment Compartments

1. Steam Fines 70% 30% 0%Generator Small LDFG 33-60% 13-25% 15-54%Compartments Large LDFG 0-22% 0% 78-100%Fines 70% 30% 0%2. Reactor Cavity Small LDFG 33-60% 13-25% 15-54%Large LDFG 0-22% 0% 78-100%3. Below Steam Fines 70% 30% NAGenerator Small LDFG 21-50% 50-79% NACompartments Large LDFG 0% 100% NAFines 70% 30% 0%4.mpresi Small LDFG 26-66% 11-28% 6-63%Large LDFG 16-26% 1-11% 63-83%Fines 70% 30% NA5Presuize Small LDFG 3-36% 64-97% NALarge LDFG 0% 100% NAFines 70% 30% 0%6.prHR Small LDFG 3-45% 1-19% 36-96%Large LDFG 0% 0-10% 90-100%Fines 70% 30% 0%7. Annulus Small LDFG 6-37% 13-25% 38-81%Large LDFG 0% 0% 100%2.2.18 Washdown Transport Fractions The washdown transport fractions were calculated based on the spray flow distribution, the size ofdebris, and the number of grating levels that debris would be washed through.

The appropriate washdown transport fractions are shown for each debris size depending on whether sprays are initiated in Table 2.2.23 (23). Note that the washdown transport fractions do not depend on the location of thebreak, but only whether sprays are initiated.

Since unqualified coatings debris may fail later in the event,this debris would only be washed down to the pool if the sprays are initiated and the coatings fail beforethe sprays are secured.Page 59 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.23 -Washdown transport fractions according to spray initiation Sprays Washdown Transport Fractions Initiated?

Debris Type Washed Down in Washed Down insideAnnulus Secondary Shield WallFines 47% 53%Yes Small LDFG 7-19% 21-27%Large LDFG 0% 0%No All 0% 0%2.2.19 Pool Fill Transport Fractions The pool fill transport fractions were calculated based on the size of debris, the break location, thevolume of the inactive cavities and sump cavities, and the pool volume at the time when these cavitieswould be filled. The appropriate pool fill transport fractions are shown for each break location anddebris size in Table 2.2.24 (23).Table 2.2.24 -Pool fill transport fractions according to break locationBreak Location Debris Pool Fill Transport FractionType Each Sump Inactive CavitiesBreaks Inside the Fines (all) 2% 5%Secondary Shield Wall Small LDFG 0% 0%(Locations 1-3) Large LDFG 0% 0%Break Outside the Fines (all) 3% 9%Secondary Shield Wall Small LDFG 0% 0%(Locations 4-7) Large LDFG 0% 0%2.2.20 Recirculation Transport Fractions The transport of debris during the recirculation phase is dependent on the break location, water level,and flow rate. The transport fractions were calculated based on CFD modeling of the recirculation pool.Since it is not practical to run CFD simulations for all possible scenarios to investigate the effects ofdiffering water levels and flow rates, a limited number of simulations were completed to determine recirculation transport fractions for various groups of breaks. The appropriate recirculation transport fractions are shown for each break location and debris size in Table 2.2.25 and Table 2.2.26 (23). Notethat the unqualified epoxy coatings in the reactor cavity would not transport for any breaks outside thereactor cavity. In the case of a reactor cavity break, the transport fractions for the unqualified epoxy inthe reactor cavity are the same as the unqualified epoxy outside the reactor cavity (23).Page 60 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Table 2.2.25 -Recirculation pool transport fractions according to break size and location (insulation)

Recirculation Transport Fractions Break Break Debris in Washed in Washed insideLocation Size Lower Annulus Secondary Containment Shield WallFines 100% 100% 100%SBLOCA Small LDFG 27% 20% 27%1: SteamGenerator Large LDFG 0% NA NAFines 100% 100% 100%CBLOCA Small LDFG 64% 58% 64%LB LOCALarge LDFG 0% NA NA2: Reactor SBLOCA Fines 100% 100% 100%Cavity MBLOCA Small LDFG 64% 58% 64%LBLOCA Large LDFG 0% NA NAFines 100% 100% 100%3: Below SBLOCA Small LDFG 27% 20% 27%Steam Large LDFG 0% NA NAGenerator Fines 100% 100% 100%Compartments MBLOCA Small LDFG 64% 58% 64%LBLOCALarge LDFG 0% NA NA4: Pressurizer SBLOCA Fines 100% 100% 100%Compartment MBLOCA Small LDFG 61% 55% 16%LBLOCA Large LDFG 0% NA NA5: Pressurizer SBLOCA Fines 100% 100% 100%Surge Line MBLOCA Small LDFG 61% 55% 16%LBLOCA Large LDFG 0% NA NA6: RHR SBLOCA Fines 100% 100% 100%Compartments MBLOCA Small LDFG 61% 55% 16%LBLOCA Large LDFG 26% NA NASBLOCA Fines 100% 100% 100%7: Annulus MBLOCA Small LDFG 61% 55% 16%1 LBLOCA Large LDFG NA NA NAPage 61 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Table 2.2.26 -Recirculation transport fractions according to break size and location (coatings, latentdebris, crud, dirt/dust)

Recirculation Transport FractionBreak Debris in Washed WashedBreak Location Bre Debris Type Size Lower in insideSize Containment Annulus Secondary Shield WallQual. Coatings Fines 100% 100% 100%Unqual. Coatings Fines 100%Fine Chips 21%Unqual. Epoxy Small Chips 0%SBLOCA Large Chips 0%Curled Chips 100%Crud Fines 100% 100% 100%Breaks Inside Dirt/Dust Fines 100% 100% 100%the Secondary Latent Fiber Fines 100% 100% 100%Shield Wall Qual. Coatings Fines 100% 100% 100%(Locations 1-3) Unqual. Coatings Fines 100%Fine Chips 41%Small Chips 0%MBLOCA Unqual. Epoxy Larg Chips 0%LBLOCA Large Chips 0%Curled Chips 100%Crud Fines 100% 100% 100%Dirt/Dust Fines 100% 100% 100%Latent Fiber Fines 100% 100% 100%Qual. Coatings Fines 100% 100% 100%Unqual. Coatings Fines 100%Breaks Outside Fine Chips 31%the Secondary MBLOCA Unqual. Epoxy Small Chips 0%Shield Wall LBLOCA Large Chips 0%(Locations 4-7) Curled Chips 100%Crud Fines 100% 100% 100%Dirt/Dust Fines 100% 100% 100%Latent Fiber Fines 100% 100% 100%2.2.21 Debris ErosionSmall or large pieces of fiberglass debris retained on grating in upper containment would be subject toerosion by containment sprays. Small or large pieces of fiberglass debris that settle in the containment pool would also be subject to erosion by the flow of water moving past the debris. The erosion fractionfor fiberglass debris retained in upper containment would be 1%, and the average erosion fraction forPage 62 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2fiberglass debris that settles in the recirculation pool would be a value below 10% as documented inTable 6.6 of the STP debris transport calculation (23).The spray erosion would occur relatively quickly in the event, and can be assumed to occur during thepool fill phase (23). However, the erosion of fiberglass debris in the pool would be a more gradualprocess.

As shown in Table 6.6 of the STP debris transport calculation, the majority of erosion wouldoccur within the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , but some erosion would continue at reduced rates over the duration ofthe event (23).2.2.22 Strainer GeometryThe strainers at STP are PCI Sure-Flow stacked disk strainers.

The gap thickness between the strainerdisks is 1 inch (47). The total surface area of each strainer is 1,818.5 ft2 per train, the interstitial volumeis 81.8 ft3 per train, and the circumscribed strainer area is 419.0 ft2 per train (48). The height of thestrainers above the containment floor is 28.5 inches11 (49), and the center of the strainers is 15.4 inchesabove the floor (49). The height of each strainer module is 25 inches, and the width of each module is 28inches (47). The bottom of the strainer modules are 2.25 inches above the floor (47). Since the core tubeis at the center of the strainer and has a diameter of 10-7/8 inches (47), the minimum water levelrequired to flow through the bottom of the strainer core tube and fill the sump pits is 10 inches. Thestrainer hole size is 0.095 inches (50). The inner diameter of the ECCS sump suction pipes is 15.25 inches(51; 52). The length and width of the sump pits are 10 ft by 4 ft (49).The total length of the strainers (based on the dimensions of Strainer C) was determined using thefollowing parameters:

" Active module length (A): 16-13/16" (47)* Number of active modules:

11 on one side, 9 on the other (49)" Core tube length (C): 21-5/16" (47)" Gap between the middle module and active module (G): 6-3/4" (49)* Middle module length (M): 24" (49)Based on these parameters, the total strainer length was calculated as shown in Equation 6.11 Note that the strainer height was inadvertently entered into CASA Grande as 39 inches. This is conservative sincethe strainer height is used to calculate the average submergence within the degasification model. Because theaverage strainer height was overestimated, the average submergence was reduced and the gas void fraction wasoverestimated.

Page 63 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2L =2" [9. C +2" (C- C A) +2 G + M][(21.31in-16.81in\

1=2 [9- 21.31in +2- (1in 21n1- 2 ) +2 6.75in + 24inJ Equation 61 ft=535min.1

=44.6ft12 inFigure 2.2.3 through Figure 2.2.6 show photos of the STP strainers.

As shown in Figure 2.2.4, protective grating was installed in front of the exposed strainer area to prevent inadvertent damage duringoutages.

The location of the strainers in containment is shown in Section 5.2 (Figure 5.2.7).Figure 2.2.3 -STP strainer Photo 1 (before protective grating was installed)

Page 64 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 2.2.4 -STP strainer Photo 2 (after protective grating was installed)

Figure 2.2.5 -STP strainer Photo 3Page 65 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 2.2.6 -STP strainer Photo 42.2.23 Clean Strainer Head LossClean strainer head loss (CSHL) is a function of the strainer

geometry, sump flow rate, and pooltemperature.

The maximum CSHL measured under bounding test conditions is 0.220 ft based on a testmodule flow rate of 530.1 gpm (equivalent to 10,543 gpm full strainer flow rate'2) at 115.9 °F (53).2.2.24 Pump NPSH MarginThe NPSH required for the HHSI, LHSI, and CS pumps is 12 ft (25). The difference in elevation betweenthe containment floor and the pump impellers is 25.65 ft for the HHSI pumps and 25.83 ft for the LHSIand CS pumps (25).The pipe roughness used to calculate the NPSH available is 0.00015 ft (25).The diameters for the various segments of the suction pipes are shown in the table below (25). Thedefinition of each pipe segment is provided in Section 5.6.5.12 The full strainer flow rate was calculated by scaling the test flow rate up using the test module surface area of91.44 ft2(53) and the full strainer surface area of 1,818.5 ft2(48).Page 66 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.27 -ECCS sump suction pipe diameters Pipe Segment Diameter (ft)AB 1.27BC 0.99BD 1.27DE 0.84DF 1.27FG 0.992.2.25 Strainer Structural MarginThe strainers have been structurally qualified for head losses up to 4.00 psi differential pressure at 128'F (54; 55), which is equivalent to a head loss of 9.35 ft.2.2.26 Vortex Air Ingestion Vortex formation is precluded based on the design of the STP strainers (56).2.2.27 Bubble Transport Partial bubble transport can occur in a horizontal pipe when the Froude number is greater than 0.35,and full transport will occur when the Froude number is greater than 0.55 (57). For vertical pipes, partialtransport will occur when the Froude number is greater than 0.35, and full transport will occur when theFroude number is greater than 1.0 (57).2.2.28 Pump Gas LimitsThe HHSI, LHSI, and CS pumps at STP can withstand gas voids up to 10% for up to 5 seconds depending on the pump flow rate compared to the best efficiency point (BEP) for the pump (58). The acceptance criterion for a steady-state gas void fraction at the pump suction inlet is 2% (59).2.2.29 Fiberglass Penetration The input parameters for filtration and shedding of fiberglass debris at the strainer were defined basedon prototype strainer module testing (60). The filtration efficiency can be described as shown inEquation 7.f M Ms + bf(WS) = if(Mc) + (1 -f (Ml)) ( 1 -e-Cms-m'))

if 0 < Ms <_ Mcif Ms > McEquation 7Page 67 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2where:f = Filtration efficiency Ms = Mass of fiber on strainerm, b, Me, 6 = Fitted filtration parameters The range of filtration coefficients from the test are shown in Table 2.2.28Table 2.2.28 -Fitted filtration parameters for test modulemtest (g"') b 6test (g-1) Mctest (g)Lower 0.0003391 0.656 0.001308 880Center 0.0003263 0.689 0.001125 930Upper 0.0003723 0.706 0.031787 790To use the test results, it is necessary to scale the parameters back to the plant conditions.

Parameter b(the filtration efficiency at clean strainer conditions) is dimensionless.

However, m, 6, and Mc have to bescaled proportional to the scaled strainer area. Given a test module area of 91.44 ft2 and a strainer areaof 1,818.5 ft2 per train, the test parameters can be scaled to the plant conditions using the following equations.

Table 2.2.29 shows the adjusted parameters.

Amodule 91.44f t2mstrainer

= m m: retestS Amodule 91.44ft215strainer

= Stest mo = 15test **tAstrainer 1,818.5ft 2Astrainer 1,818.5ft 2Mc,strainer

= Mc,test A' odueA Mc,test 91.44ft2Equation 8Equation 9Equation 10Table 2.2.29 -Fitted filtration parameters for each ECCS strainerm (Ibm,-) b 6 (Ibm,-) Mc (Ibm)Lower 0.007741 0.656 0.02968 38.5Center 0.007449 0.689 0.02511 40.7Upper 0.008499 0.706 0.7259 34.6The shedding coefficients determined from the testing (results of Tests 5-7) are shown in Table 2.2.30(60).Page 68 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 2.2.30 -Fitted shedding parameters v rj (min"1)Minimum 0.0096 0.0082Average 0.0152 0.0313Maximum 0.0196 0.05462.2.30 Decay Heat CurveAs shown in Table 2.2.31, the decay heat generation rate was taken from the 1979 ANS plus 2 sigmauncertainty (61). The rated thermal power for STP is 3,853 MW (62).Table 2.2.31 -Decay heat generation rate based on 1979 ANS plus 2 sigma uncertainty Time Decay HeatGeneration Rate(Btu/Btu) 10 0.05387615 0.05040120 0.04801840 0.04240160 0.03924480 0.037065100 0.035466150 0.032724200 0.030936400 0.027078600 0.024931800 0.0233891,000 0.0221561,500 0.0199212,000 0.0183154,000 0.0147816,000 0.0130408,000 0.01200010,000 0.01126215,000 0.01009720,000 0.009350Page 69 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Time Decay HeatGeneration Rate(Btu/Btu) 40,000 0.00777860,000 0.00695880,000 0.006424100,000 0.006021150,000 0.005323400,000 0.003770600,000 0.003201800,000 0.0028341,000,000 0.0025802.2.31 Core Blockage Debris LimitsBased on conservative testing by the PWR Owner's Group (PWROG),

debris loads greater than 15 gramsper fuel assembly (g/FA) may cause issues with core blockage (63). STP has a total of 193 fuel assemblies (64). Therefore, the total fiber quantity required to meet the 15 g/FA limit is 2,895 g (6.4 Ibm).Page 70 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 23 Assumptions This section lists the major assumptions made in the CASA Grande analysis.

1. General Assumptions

a. It was assumed that a LOCA that occurs during full power operation (i.e., Mode 1) isequivalent or bounding compared to the other operating modes. This is a reasonable assumption since the RCS pressure and temperature (key inputs affecting the ZOI size)would either be approximately the same or significantly lower for Modes 2 through 6.Also, the flow rate required to cool the core (a key input affecting core blockage) wouldbe significantly reduced for low power or shutdown modes.b. It was assumed that containment would be isolated at the time of an accident.

Althoughcontainment overpressure was not credited (see Assumption 1.c), this is a best-estimate assumption that allows the containment pool temperature to be greater than 212 *F. Ingeneral, assuming a higher pool temperature at the beginning of the event is alsoconservative since corrosion and dissolution would be higher, NPSH margin would belower, and degasification would be higher.c. Containment pressure was assumed to be 14.7 psia for all cases except when the pooltemperature is higher than the boiling temperature.

In cases where the pooltemperature is above 212 °F, the containment pressure was assumed to be equal to thesaturation pressure.

This is a conservative assumption since neglecting containment overpressure reduces the ECCS pump NPSH margin and increases the amount ofdegasification at the strainer.

d. It was assumed that Thermal-Wrap is identical to Nukon for GSI-191 analysis purposes.

This is a reasonable assumption since both are LDFG products with similar properties (44).e. It was assumed that qualified coatings debris would fail as 10 Ilm particles.

This isconsistent with the deterministic debris generation calculation (43) and the guidance inNEI 04-07 (45).f. It was assumed that small and large pieces of fiberglass that are predicted to transport to the strainer can be treated as fine debris with respect to both the transport timingand subsequent effects on head loss and penetration.

This is a conservative assumption since in reality, the pieces of insulation debris would tend to transport more slowly,would be less likely to penetrate the strainer, and would not form as uniform a debrisbed on the strainer resulting in lower head losses.g. The only reflective metal insulation (RMI) in containment at STP is stainless steelTransco RMI that is installed on the reactor vessel (43). It was assumed that the RMI canbe neglected in the STP GSI-191 analysis.

This is a reasonable assumption since 1) thequantity of RMI debris would be relatively small since the ZOI size for Transco RMI isonly 2.0D (45), 2) stainless steel foils are chemically inert, 3) the majority of RMI debrisgenerated would not reach the strainers since the transport paths from the reactorcavity through the secondary shield wall to the strainers are tortuous and not conducive Page 71 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2to transport of the relatively heavy RMI debris (65), and 4) RMI has a minor effect ondebris head loss for strainers that are sitting above the floor elevation (RMI can actuallyreduce head loss by breaking up the uniform accumulation of a fiber debris bed) (66).h. It was assumed that the failure of permanently installed lead blankets within variousbreak ZOIs can be neglected.

This is a reasonable assumption since there are only a fewpipes with lead blankets at STP, a limited number of breaks would be close enough tothese pipes to damage the lead blankets, and the lead debris that is generated wouldnot be likely to transport or cause any significant problems.

Note, however, that thefiberglass insulation underneath the lead shielding on the piping within the appropriate ZOI is considered for the debris generation calculation.

It was assumed that the minimum spray flow rate for single train operation is 80% of themaximum spray flow rate for single train operation.

This is a reasonable assumption since the minimum spray flow rate for two train operation is 82% of the maximum sprayflow rate for two train operation, and the minimum spray flow rate for three trainoperation is 80% of the maximum spray flow rate for three train operation (see Section2.2.8).j. It was assumed that switchover to hot leg injection would occur between 5.75 and 6hours after the start of the event. This is a reasonably assumption since the switchover procedure is started 5.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months after the start of the event and according to plantpersonnel, switchover for both trains can be completed within 15 minutes (67).k. As shown in Table 2.1.1, the pool temperature has an effect on many aspects of theoverall GSI-191 evaluation including chemical effects (material release rates andsolubility limits),

debris transport, strainer head loss, NPSH margin, degasification, andin-vessel effects.

For some aspects of the analysis, a higher temperature profile is moreconservative (e.g., NPSH margin and degasification),

whereas a lower temperature profile is more conservative for other aspects of the analysis (e.g., strainer head loss anddebris transport).

Due to the competing effects and the complexity of the overallevaluation, it is not possible to pre-determine whether a higher or lower pooltemperature profile would be more limiting.

However, several aspects of the evaluation were analyzed independently and implemented in CASA without a direct link to thetemperature profile.

The effects of temperature on the various aspects of the evaluation are described below:1. The chemical effects evaluation includes both an analysis of the release ratesand the solubility limits. Release rates increase with increasing temperature, and solubility decreases with decreasing temperature (with the exception ofproducts that exhibit retrograde solubility),

so it is difficult to say whichdirection is conservative overall for chemical effects.

However, since the STPCHLE testing wasn't fully completed prior to the submittal, a simplified approach was used to address chemical effects where chemical head loss was(mostly) decoupled from the temperature profile in CASA. As discussed inSection 5.6.3, chemical precipitation was assumed to occur when the pooltemperature drops below 140 *F. Therefore, minimizing the temperature profile would be conservative.

Page 72 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2II. The debris settling and tumbling velocities are lower at lower temperatures due to the higher viscosity, so minimizing the temperature profile would beconservative.

However, this effect has been decoupled from the temperature profile in CASA since the debris transport fractions were conservatively determined based on transport testing that was generally conducted at roomtemperature conditions (23).Ill. The clean strainer head loss and conventional debris bed head loss are higherat lower temperatures, so minimizing the temperature profile wouldmaximize the overall strainer head loss. Note, however, that a single boundingvalue was used for the clean strainer head loss in CASA (see Section 2.2.23).IV. The pump NPSH margin is lower at higher temperatures, so maximizing thetemperature profile would be conservative.

However, the strainer structural margin is lower than the NPSH margin for essentially the entire event exceptvery early in the event when the pool temperature is near or above 212 *F.V. The quantity of gas released at the strainer is larger at higher temperatures, so maximizing the temperature profile would tend to be conservative.

However, degasification is also larger for larger pressure drops, whichincreases at lower temperatures, so these two factors are competing.

Ingeneral, the void fraction does not change significantly over the range ofprototypical long-term temperature profiles where the debris bed head losswould be more likely to be high enough for significant degasification to occur(i.e., due to the increase in head loss from chemical precipitates and failedunqualified coatings).

Although additional sensitivity analysis would benecessary to fully understand the effects of the temperature profile onfailures due to degasification, this was not considered to be a significant driver.VI. The boil-off rate (along with the corresponding SI flow split and debristransport to the core for a cold leg break during cold leg injection) increases with increasing temperature, so a higher temperature during the cold leginjection period is conservative.

However, this effect has been decoupled from the temperature profile implemented in CASA since the SI flow enteringthe vessel was assumed to be at saturation conditions (see Section 5.10.3).Based on this evaluation, it was assumed that all small and medium breaks less than 6inches can be conservatively represented by a nominal 6-inch break containment pooltemperature

profile, and all large breaks greater than 6 inches can be represented by anominal 27.5-inch DEGB temperature profile.

These two temperature profiles tend tomaximize the temperature early in the event (i.e., the first 1-2 hours), and thenminimize the temperature for the remainder of the event (5). This is generally conservative since the strainer debris head loss and chemical precipitation timing arethe most significant parameters affected by the temperature profile and will bemaximized if the temperature profile is minimized.

It was assumed that the temperature profiles developed from the thermal-hydraulic modeling can be logarithmically extrapolated from the temperature at the end of thePage 73 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2simulations to the nominal component cooling water (CCW) temperature at 30 days-86 °F (5). This minimizes the long-term temperature profile since the containment pooltemperature will never drop below the CCW temperature and is likely to be higher thanthe CCW temperature at the end of 30 days. As discussed in Assumption 1.k, minimizing the temperature profile is conservative.

m. It was assumed that a 36-hr run time for the CASA Grande simulations is sufficient topredict the scenarios that would proceed to failure.

This is a reasonable assumption since most of the dominant time-dependent phenomena occur within the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .Note that a 5 minute time increment was used to evaluate each of the time-dependent models in CASA.2. Equipment Failure Assumptions (prior to the start of recirculation)

a. It was assumed that pump failures in one train are indistinguishable from identical failures in another train. For example, a failure of the LHSI and CS pumps in Train A (withno other failures) is assumed to be identical to a failure of the LHSI and CS pumps inTrain C (with no other failures).

This is a reasonable assumption since the strainer areaand pump flow rates are essentially the same for all three trains, and the trains arephysically located in the same area in containment.

Therefore, there would be negligible differences in debris transport, head loss, penetration, etc. for cases with identical failures in different trains.b. It was assumed that a combination of pumps failing in the same train is worse than thesame combination of pumps failing in separate trains. For example, given a scenariowhere one LHSI, one HHSI, and one CS pump all fail, the scenario where all three pumpsfail in Train A is worse in terms of strainer failures than the scenario where the HHSI andLHSI pumps fail in Train A and the CS pump fails in Train B. The total CS and SI flowwould be the same for these two cases. In the first case, however, Trains B and C wouldbe operating at maximum flow, whereas in the second case, only Train C would beoperating at maximum flow and the remaining flow would be split between Trains A andB. As illustrated in Table 3.1, by splitting the flow between Trains A and B, the likelihood of either Train A or Train B failing due to high head loss or degasification is significantly reduced.

Note that this assumption is not necessarily conservative in terms of vesselfailures since the additional strainer surface area from one or two extra trains operating could increase the total amount of debris that arrives at the core. However, since it ismore likely for a full train to fail than it would be for an LHSI pump, HHSI pump, and CSpump to fail in separate trains13, this assumption is reasonable.

13 This is illustrated by the pump state frequencies in Table 5.1.1, which shows that the failure for one HHSI pumpand one CS pump is 2.44E-08 yr' compared to a single train failure frequency of 9.16E-06 yr' (i.e., the failure of allthree pumps in one train is over two orders of magnitude more likely than a random failure of one HHSI pump andone CS pump in any of the trains).Page 74 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 3.1 -Strainer debris accumulation and approach velocity comparison 14Scenario 1 Scenario 2(LHSI A, HHSI A, CS A) (LHSI A, HHSI A, CS B)Train A Debris Accumulation 0% 19%Approach Velocity 0 ft/s 0.0032 ft/sTrain B Debris Accumulation 50% 31%Approach Velocity 0.0086 ft/s 0.0054 ft/sTrain C Debris Accumulation 50% 50%1 Approach Velocity 0.0086 ft/s 0.0086 ft/sc. It was assumed that the failure of various combinations of pumps can be bounded interms of strainer failures by other scenarios that have an equal or higher approachvelocity and an equal or higher debris accumulation on any one strainer.

Thisassumption is appropriate based on the conservative assumptions that failure of onepump or train is equivalent to the failure of all pumps and trains (see Assumption 12.athrough Assumption 12.c). This is illustrated in Table 3.2 using CS pump failures as anexample.

In this example, Train C in Scenario 3 has the most limiting conditions with thecombination of highest debris accumulation and highest approach

velocity, andtherefore would be the most likely fail.Table 3.2 -Strainer debris accumulation and approach velocity comparison for CS pump failures14Scenario 1 Scenario 2 Scenario 3 Scenario 4(no failures)

(CS A) (CS A, CS B) (CS A, CS B, CS C)Train A Debris Accumulation 33.3% 24% 28% 33.3%Approach Velocity 0.0086 ft/s 0.0054 ft/s 0.0054 ft/s 0.0054 ft/sTrain B Debris Accumulation 33.3% 38% 28% 33.3%Approach Velocity 0.0086 ft/s 0.0086 ft/s 0.0054 ft/s 0.0054 ft/sTrain C Debris Accumulation 33.3% 38% 44% 33.3%1 Approach Velocity 0.0086 ft/s 0.0086 ft/s 0.0086 ft/s 0.0054 ft/sd. It was assumed that the failure of various combinations of pumps can be bounded interms of in-vessel failures by other scenarios that have a higher flow split to the corewith an equal number of trains in operation.

The flow split to the core is dependent onthe flow split to the SI pumps vs. the total sump flow rate (Qsl/Q.tota),

and the boil-offflow split to the core vs. the total SI flow rate for cold leg breaks (QO/boiQS.).

An examplecalculation is illustrated in the table below.14 Calculated using a strainer area of 1,818.5 ft2 per strainer and flow rates of 2,800 gpm per LHSI pump, 1,620 gpmper HHSI pump, and 2,600 gpm per CS pump. Note that changes in the flow rates due to break size or other effectswould change the specific percentages, but the relative effects between break cases would be consistent with thevalues shown above.Page 75 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 3.3 -Core debris accumulation for various pump failures's Scenario 1 Scenario 2 Scenario 3 Scenario 3 Scenario 3Flow Splits (1 CS) (1 LHSI, 1CS) (1 HHSI, 1CS) (2 CS) (2 LHSI, 1 CS)SI Flow Split 71.8% 66.8% 69.1% 83.6% 59.6%Core Flow Split 4.5% 5.7% 5.2% 4.5% 7.8%Total Split 3.3% 3.8% 3.6% 3.8% 4.7%e. It was assumed that failure of equipment other than pumps does not need to beexplicitly linked to the PRA equipment failure probabilities.

Failures of fan coolers andheat exchangers can have a significant impact on the containment pool temperature.

However, rather than modeling the explicit equipment failure scenarios postulated inthe PRA, the range of equipment failures was considered in the development of thecontainment pool temperature profiles (5).f. It was assumed that pump configurations with a frequency less than 2E-09/yr wouldresult in failure of at least one of the GSI-191 acceptance criteria.

This is a conservative assumption since some of these cases would not proceed to failure.3. LOCA Frequency Assumptions

a. It was assumed that the geometric mean aggregation of LOCA frequencies in NUREG-1829 (37) is the most appropriate set of results to use for this evaluation.

As described in Section 5.3, the NUREG-1829 data must be fit to appropriately determine theepistemic uncertainty associated with LOCA frequency estimates.

Based on anevaluation of the relative merits of the arithmetic mean and geometric mean, thegeometric mean aggregation was determined to be more representative of the overallconsensus of the panelists (68).b. It was assumed that the current-day LOCA frequencies are more appropriate to use forthis evaluation than the end-of-plant-license frequencies.

This is a reasonable assumption for the base analysis, although the effect of using end-of-plant-license frequencies can be evaluated as a sensitivity case.c. It was assumed that breaks on non-weld locations can be excluded from the evaluation.

This is a reasonable assumption since the break frequency for non-weld locations wouldbe significantly smaller than weld locations, and would not generate significantly different quantities of debris from the weld breaks. It was also assumed that isolablebreaks can be excluded from the evaluation since isolable breaks would not lead torecirculation.

d. Linear-linear interpolation of top-down LOCA frequencies from N UREG-1829 was usedto preserve uniform probability density between expert elicitation points provided in15 Calculated for cold leg break conditions with three train operation using flow rates of 2,800 gpm per LHSI pump,1,620 gpm per HHSI pump, 2,600 gpm per CS pump, and a 600 gpm boil-off flow rate. Note that changes in theflow rates due to break size or other effects would change the specific percentages, but the relative effectsbetween break cases would be consistent with the values shown above.Page 76 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2the tables. Uniform probability density avoids any attribution of behavior that the paneldid not intend and generally shifts probability density to larger break sizes.e. It was also assumed that the bottom-up LOCA frequencies that are used to assignrelative frequencies to the individual weld locations can be linearly interpolated.

Thisdoes not necessarily introduce conservatism to the analysis since the bottom-up frequencies are scaled to match the top-down NUREG-1829 frequencies.

However, it is areasonable approach given an incomplete understanding of the physical behavior of theLOCA frequency curve between the established values.f, Out of 193 welds on small bore (0.75-inch and 1-inch) pipes, only 35 were modeled with3 welds modeled on 1-inch pipes and 32 welds modeled on 0.75-inch pipes (4). It wasassumed that the overall break frequency for the 193 welds can be distributed acrossthe 35 welds (176 welds assumed to be 0.75-inch and 17 welds assumed to be 1-inch).This is a reasonable assumption since breaks of this size are generally insignificant withrespect to GSI-191 phenomena.

Also, since the 35 welds that were modeled arescattered around containment, it is not likely that the weld locations that were notmodeled would have any significant differences with respect to the quantity of debristhat would be generated or transported from the locations that were modeled.g. With exception to the small bore weld count discussed in Assumption 3.f, it wasassumed that the weld count in the CAD model (4) is more accurate than the weld countin the LOCA frequency report (7) in any cases where there are deviations (see Section5.3.2). This is a reasonable assumption since the CAD model includes specific references to the source drawings and is consistent with the component database (9).4. Debris Generation Assumptions

a. It was assumed that the ZOI size for Microtherm is identical to the ZOI size for Min-K.This is a reasonable assumption since the two insulation types are essentially the same(44).b. It was assumed that 100% of the miscellaneous debris (tags, labels, etc.) would fail atthe beginning of the event. This is a conservative assumption since the majority of themiscellaneous debris would be outside the ZOI and may not fail at all during the event.c. It was assumed that the quantity of unqualified intumescent coatings is negligible andcan be excluded from the analysis.

This is a reasonable assumption since the totaltransportable quantity is only 2 Ibm (see Section 2.2.10).5. Chemical Effects Assumptions

a. It was assumed that chemical products would not form before the pool temperature drops below 140 *F. This is a reasonable assumption for the purposes of this evaluation since the solubility limit for aluminum precipitates increases significantly at highertemperatures, and calcium precipitates are not expected to form in large quantities formost of the scenarios evaluated (20). Note that the temperature profiles used in theCASA Grande evaluation conservatively minimize the temperature and therefore minimize the time that it would take for chemical products to form.Page 77 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision

26. Debris Transport Assumptions

a. It was assumed that there would be no significant transport of intact blanket debris. Thisis a reasonable assumption since the intact blankets are large pieces that would beeasily held up on structures and would be too heavy to transport readily in thecontainment pool (69).b. It was assumed that miscellaneous tags, labels, etc. are all located in lower containment and would fall directly in the containment pool. It was also assumed that all of themiscellaneous debris would transport to the strainers at the start of recirculation.

This isa conservative assumption since some of the miscellaneous debris would be in locations above the pool where it would not transport.

Also, based on previous testing,miscellaneous debris would not be likely to transport in the recirculation pool (53).c. It was assumed that all latent debris is on the containment floor at the beginning of theevent. This assumption results in an increased transport fraction to inactive

cavities, butneglects any retention of latent debris above the pool where much of it could beshielded from containment sprays.d. It was assumed that debris washed down from upper containment reaches the poolafter the inactive and sump cavities are filled, but before recirculation is initiated.

This isa conservative assumption since it neglects transport of any washdown debris toinactive cavities during pool fill, but accelerates the time that debris would reach thestrainer during the recirculation phase.e. It was assumed that the debris transport to each of the strainers is proportional to theflow rate through each strainer divided by the total flow rate through all of thestrainers.

This is a reasonable assumption since the debris transports with the flow.f. It was assumed that the fine debris that is initially in the pool at the start of recirculation as well as the fine debris that transports to the pool during recirculation would beuniformly distributed in the pool. This is a reasonable assumption since the fine debris inlower containment prior to the start of recirculation would be well mixed in the pool asit fills, and the fine debris washed down from upper containment during recirculation would be well mixed due to the dispersed locations where containment sprays enter thepool.g. It was assumed that fiberglass debris erosion caused by flow in the pool or bycontainment sprays would occur prior to the start of recirculation.

This is a conservative assumption since it accelerates the time that erosion fines would reach the strainers.

h. It was assumed that the overall transport fractions for each type of debris can berepresented by the bounding transport fractions for an LBLOCA in the steam generator compartments.

This is a reasonably conservative recommendation based on thefollowing points (see Section 2.2.17 through Section 2.2.21):I. Worst case values were selected from the transport fraction ranges for steamgenerator compartment blowdown and washdown.

II. Transport fractions for LBLOCAs are equivalent or bounding for MBLOCAs andSBLOCAs.Page 78 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Ill. Sprays are always assumed to be activated (even for SBLOCAs) in theimplemented transport fractions.

IV. Unqualified epoxy coatings in the reactor cavity never transport (even forreactor cavity breaks) in the implemented transport fractions.

V. Pool fill transport to the strainers assumes that all three strainers are active(even for cases where only one or two trains are operating) in theimplemented transport fractions.

VI. Steam generator compartment blowdown transport fractions for small andlarge pieces of fiberglass are not necessarily bounding for other breaklocations.

VII. Washdown transport fractions are applicable to all break locations.

VIII. Inactive cavity transport fractions for breaks inside the secondary shield wallare bounding compared to breaks in the annulus.IX. Steam generator compartment recirculation transport fractions are boundingfor all other break locations.

X. The transport calculation used to determine all of the debris transport fractions includes several conservatisms (23).7. Head Loss Assumptions

a. It was assumed that miscellaneous debris would partially overlap and would fully blockstrainer flow over an area equivalent to 75% of the miscellaneous debris surface area.This assumption is consistent with the guidance in NEI 04-07 (45).b. It was assumed that all coatings materials would have a packing fraction similar toacrylic coatings.

It was also assumed that non-coatings particulate debris would have apacking fraction similar to iron oxide sludge. These assumptions are based onengineering judgment due to limited data.c. It was assumed that a fiber bed of at least 1/16th of an inch is necessary to capturechemical precipitates.

This is a reasonable assumption since a thinner debris bed wouldnot fully cover the strainer and would not support appreciable head losses due tochemical debris.d. It was assumed that 100% of the transported particulate debris would be captured onthe strainer at the time of arrival.

This assumption does not imply that no particulate would penetrate the strainer.

However, since the in-vessel effects acceptance criteriathat were implemented in CASA are independent of the particulate

quantity, thisassumption is conservative.

e. It was assumed that the debris on the strainers would be homogenously mixed. This is areasonable assumption since much of the debris would arrive at the strainersimultaneously.

f. It was assumed that fiberglass debris would accumulate uniformly on the strainers witha density of 2.4 Ibm/ft3.This is consistent with the assumptions used in NUREG/CR-6224 Page 79 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2(70). For the purposes of developing the strainer loading table (see Section 5.6.2), thepool height was assumed to always be sufficient to allow debris to accumulate on thetop of the strainer, but debris accumulation on the bottom of the strainer was limited to2 inches to account for the height of the strainer above the floor. Assuming that thepool height is greater than the debris accumulation on the top of the strainer is notnecessarily accurate for cases where the water level is relatively low and the debris loadis large. However, for the majority of cases, the debris load would not be large enoughto accumulate a fiber bed that exceeds the submergence level.8. Degasification Assumptions

a. It was assumed that Henry's Law is applicable for degasification calculations.

Henry'sLaw essentially states that the solubility of a gas in a liquid is proportional to the partialpressure of the gas above the liquid. At the equilibrium saturation level, the number ofgas molecules moving into and out of solution is constant.

The initial saturation of gas inthe containment pool would have sufficient time to reach equilibrium.

Due to the shorttime that it would take for flow to pass through the debris bed on the ECCS strainers, there may not be sufficient time to reach equilibrium and all of the gas to come out ofsolution in the debris bed itself. However, it is expected that equilibrium conditions would be reached downstream of the strainer.

Therefore, Henry's law is considered tobe applicable for calculating the air released.

b. It was assumed that the temperature upstream and downstream of the strainers isconstant.

This is a reasonable assumption since the water temperature would notchange significantly as the water flows through the strainer.

c. It was assumed that the air in containment would be essentially the same asatmospheric air. For example, the addition of nitrogen from the accumulators and theformation of hydrogen due to chemical reactions in the containment pool were notconsidered.

These and other sources of non-condensable gasses in containment arelikely minor compared to the total initial free volume of air in containment.

d. It was assumed that air behaves as an ideal gas. This is a reasonable assumption sincethe correction factor for non-ideal behavior at low pressures is essentially negligible (71). For example, the z-factor for air at 5 bar (72.5 psi) and 350 K (170 °F) is 1.0002 (72).e. It was assumed that the relative humidity of the containment atmosphere is 100%16.This is a reasonable assumption given the amount of steam released into containment during a LOCA.f. It was assumed that the relative humidity of the gas voids downstream of the ECCSstrainers is 100%. This is a reasonable assumption since the gas bubbles that are formedwould be fully surrounded by water. Note also that this assumption is conservative sincemaximizing the humidity downstream of the strainer minimizes the partial pressure ofthe air, and therefore reduces the equilibrium concentration of dissolved airdownstream of the strainer.

16 Note that a lower relative humidity in containment would increase the concentration of dissolved air in thecontainment pool, resulting in a larger quantity of air released.

Page 80 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2g. It was assumed that the average submergence depth (from the surface of the pool tothe center of the strainer) can be used for the hydrostatic head. This is a reasonable assumption since the STP strainers are designed for uniform flow distribution.

h. It was assumed that any gas voids caused by degasification would be transported to theECCS pumps. This is a conservative assumption since it maximizes potential pumpfailures due to air ingestion, and also maximizes the NPSH required.

The void fraction at the pumps was assumed to be the same as the void fractiondownstream of the sump strainers.

This is a conservative assumption since it neglectsthe decreased bubble size due to the higher static pressure.

9. Penetration Assumptions

a. It was assumed that the debris beds on the strainers would not be disrupted after thedebris initially accumulates.

This is a reasonable assumption since the strainers are notlocated in the immediate vicinity of any potential breaks where the break flow couldimpinge the strainers and shear off a portion of the debris.b. It was assumed that debris that penetrates the strainers would be uniformly distributed in the flow and would transport proportional to the flow split to the SI pumps vs. CSpumps (y) and the flow split to the core vs. bypass paths (A). This is a reasonable assumption since the fiber that penetrates the strainer would be very fine and wouldeasily transport with the flow.c. It was assumed that all debris that penetrates the strainer and transports through thecore would be trapped on the core (i.e., 100% filtration efficiency).

This is a conservative assumption since it maximizes the debris load on the core.d. It was assumed that all debris that penetrates the strainer and bypasses the core (eitherthrough the containment sprays or directly out the break) would immediately betransported back to the containment pool. This is a conservative assumption since itneglects potential hold-up of debris in various locations and neglects the time that itwould take for debris to transport through the systems and wash back to the pool.10. Core Blockage Assumptions

a. It was assumed that a debris bed would not form at the top of the core (blocking flow tothe core) during the hot leg injection phase. This is a reasonable assumption since debrisblockage would result in boiling in the core, which would disrupt the debris bed.b. To calculate the boil-off flow rate for a cold leg break during cold leg injection, it wasassumed that the RCS pressure is 14.7 psia, and the SI flow entering the reactor vessel issaturated liquid (i.e., 212 'F). This assumption conservatively maximizes the boil-off flowrate since a lower inlet temperature and/or a higher RCS pressure would increase theenthalpy required to boil the water.11. Boron Precipitation Assumptions

a. It was assumed that the current STP design basis evaluation methodology used tocalculate the required hot leg switchover timing is appropriate with the exception ofGSI-191 related phenomenon (i.e., formation of a debris bed on the core). This is anPage 81 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2appropriate assumption since the generic boron precipitation issues not related to GSI-191 are being separately addressed by the PWROG and do not need to be evaluated forGSI-191 closure.b. It was assumed that for a medium or large cold leg break during cold leg injection, afiber debris load of at least 7.5 g/FA would form a debris bed that would prevent thenatural mixing processes credited in the design basis hot leg switchover calculation resulting in boron precipitation prior to switchover.

This is a conservative assumption since a debris bed of 15 g/FA was necessary to capture chemical precipitates and causesignificant blockage concerns.

c. It was assumed that boron precipitation would not be an issue for small breaks. This is areasonable assumption since natural circulation would maintain a relatively steadyconcentration of boron in the core. Boron precipitation failures were not explicitly precluded for small breaks (i.e., the same acceptance criteria were used for all breaksizes). However, no boron precipitation failures were observed to occur for small breaks.d. It was assumed that boron precipitation would not be an issue for medium and large hotleg breaks. This is a reasonable assumption since at least one train would be injecting inthe cold leg throughout the event. This flow would pass through the core and maintain arelatively steady concentration of boron. Even if significant core blockage occurs, someflow would still pass through the debris bed and flush through the core.12. Acceptance Criteria Assumptions

a. It was assumed that failure of one pump in any train due to loss of NPSH margin isequivalent to the failure of all pumps in all trains. This is a conservative assumption sincethe NPSH margin is not the same for all pumps, and if one pump failed, the sump flowrate would be reduced making it less likely that a second pump would fail. Also, sincethe trains are independent, failure of one train would not affect the other trains exceptthat suspended debris in the pool after the failure would only accumulate on theremaining trains that are still active.b. It was assumed that structural failure of one strainer would allow sufficient debrisingestion to result in complete failure of the ECCS. This is a conservative assumption since it is possible that the ECCS could continue to operate even with large quantities ofdebris ingested.

c. It was assumed that failure of one pump in any train due to excess air ingestion isequivalent to the failure of all pumps in all trains. This is a conservative assumption sinceone train or one pump in a given train may ingest significantly more air than the othertrains or pumps resulting in the failure of only one train or pump.Page 82 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 24 Methodology The methodology for performing a deterministic GSI-191 evaluation is provided in NEI 04-07 Volume 1(44) as approved by the NRC in their safety evaluation documented in NEI 04-07 Volume 2 (45).To account for any uncertainties associated with the analysis and plant-specific conditions where theyexist, conservative assumptions are adopted in deterministic models. Insulation debris quantities arecalculated based on the maximum possible break size at the worst case break location.

Debris transport is calculated based on maximum flow rates, minimum water level, and smallest debris size distributions.

Chemical precipitation is calculated based on maximum pool temperature and pH, maximum poolvolume, maximum debris quantities, and maximum spray duration.

Strainer head loss is calculated based on maximum quantities of debris generated and transported, minimum debris penetration, maximum flow rate, and minimum pool temperature.

The maximum strainer head loss is comparedagainst the minimum NPSH margin, which is calculated based on maximum flow rate and maximum pooltemperature.

Core head loss is calculated based on maximum debris penetration, maximum flow rate,and worst case flow configurations.

The core head loss is also compared to conservative acceptance criteria based on the minimum available driving head.Although the deterministic methodology is relatively well defined, the conservatism in the overall resultis compounded by the numerous conservatisms introduced in each portion of the analysis.

Also, asidentified above, several conservatisms are mutually exclusive, such as the use of a minimum water levelfor debris transport and a maximum pool volume for chemical precipitation, or use of a minimumtemperature for strainer head loss and a maximum temperature for strainer NPSH margin.In each area of a deterministic

analysis, it is permissible to implement analytical refinements to reducethe level of conservatism.

The appendices to NEI 04-07 Volume 2 contain several refinement optionssuch as CFD modeling to reduce debris transport in the containment pool (45). However, everyrefinement that is applied must be justified to show that some level of conservatism is maintained, andthe analysis still provides bounding results.For a risk-informed analysis of GSI-191, it is necessary to postulate all possible events that requirerecirculation through the ECCS strainers.

To calculate the probability associated with core damage or asubsequent large early release, it is necessary to estimate the frequency of the various initiating events,and determine the outcome for a representative sample of the events (this may require analysis ofthousands of different scenarios).

Rather than analyzing these scenarios in a conservative and boundingmanner like the deterministic

approach, it is necessary to perform the analysis using realistic inputs,methods, and acceptance criteria.

For some input variables, a best-estimate value may be adequate for a realistic analysis (this could betrue for parameters that have a tight range between the minimum and maximum values or forPage 83 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2parameters where the results of the analysis are relatively insensitive to large variations in theparameter values).

However, some input variables may require probability distributions.

Figure 4.1shows an example probability distribution for water volume. Depending on the specific

analysis, eitherthe calculated minimum or calculated maximum water volume would be used as an input for adeterministic evaluation.'

7 For a risk-informed evaluation, the input probability distribution can besampled to determine the actual impact on the results with an appropriate probability weight carriedthrough the analysis for the extreme conditions associated with the minimum and maximum values.Best-estimate

.02LCalculated minimum Actual----- -- minimumCalculated Actual maximummaximum (conservative)

WaterVolume Figure 4.1 -Example of realistic probability distribution for an input variableIn addition to using realistic inputs, it is also important to perform a time-dependent evaluation tocapture the time-dependent factors and events that are significant to GSI-191.

This includes time-dependent failure for unqualified

coatings, time-dependent transport of debris to the strainers, time-dependent precipitation of chemical

products, time-dependent operator actions such as securing pumpsor switching over to hot leg injection, etc.For a risk-informed evaluation, the uncertainties associated with the various input parameters andmodels must also be estimated and carried through the evaluation.

17 Note that a deterministic refinement could be applied by reducing the level of conservatism in the minimum ormaximum water volume calculation.

This may provide significant improvement, but using a bounding value for thewater volume input still produces results that are unrealistically biased in the conservative direction.

Page 84 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2The conditional failure probabilities determined from CASA Grande for the three basic events (small,medium, and large break LOCAs), along with the initiating event frequencies, are used as inputs for theplant-specific PRA. The PRA results are then compared to a hypothetically perfect plant configuration with respect to ECCS performance to calculate the change in core damage frequency (CDF) and largeearly release frequency (LERF). If the ACDF and ALERF values are within Region 3 as defined inRegulatory Guide 1.174 (73), the risk associated with GSI-191 is considered very small. If the ACDF andALERF values are within Region 2 or Region 1, the risk is more significant, and would require moreextensive compensating measures to reduce the risk.Figure 4.2 provides a simplified high level picture of the risk-informed GSI-191 resolution process.Page 85 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Risk-Informed MethodRealistic/probabilistic

" Inputs.Methods" Acceptance CriteriaContainment CAD LOCA Frequencies Model/Input Development Model Frequency estimates Perform testing or analysisDetailed model of for break sizes from to develop realistic inputs,insulation, structures

%" to DEGB at all physical models, andand break locations potential locations acceptance criteria~Uncertainty CASA Grande Quantification Determine uncertainty Analyze debris generation, debris bands for varioustransport, strainer head loss, air intrusion, parameters and modelsdebris bypass, and core blockage forthousands of individual accidentsequences in a time-dependent mannerwhile representatively sampling variations in each input parameter and propagating uncertainties.

Compare each sequence to appropriate acceptance criteria and summarize resultsas a failure probability for S/M/L LOCAcategories.

Repeat analysis for eachpossible equipment configuration.

PRA PCalculate ACDF and ALERF for Within RGPerform plantcurrent configuration vs. 1.174 Region No modifications hypothetically perfect cost, dose, andconfiguration with respect to maintained?

CDF reduction ECCS performance Figure 4.2 -Risk-informed GSI-191 resolution pathPage 86 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 24.1 GSI-191 Analysis StepsThe risk-informed analysis of the physical phenomena associated with GSI-191 includes the following general steps:1. Identify the scenarios that must be evaluated.

This includes essentially all events that lead toECCS sump recirculation from a primary or secondary side break during any mode of operation.

This also includes different equipment failure combinations consistent with the PRA.2. Develop a detailed containment building CAD model. The model should include concretestructures,

grating, insulation on equipment and piping, and potential break locations on welds.3. Estimate the frequency of the initiating events. This requires an assessment of the frequency associated with breaks ranging from a 1/22-inch hole to a full DEGB at each potential breaklocation, based on the following steps:a. Determine the relative probability of breaks in each weld category based on specificdegradation mechanisms and distribute total LOCA frequency to each weld locationbased on relative weight between weld cases.b. Identify appropriate weld category for each weld location.

c. Statistically fit the NUREG-1829 LOCA frequency data.d. Sample the epistemic uncertainty in the NUREG-1829 frequencies using the statistical fit.e. Sample a variety of break sizes at each weld location and record the appropriate frequency for each sampled break.4. Determine the type, quantity, and characteristics of debris that is generated.

This includes thefollowing steps:a. Determine the appropriate ZOI size for each material based on the destruction pressureand break size.b. Determine the appropriate size distribution for each type of insulation debris based onthe insulation type and distance from the break location.

c. Calculate the quantity of each type and size of insulation debris based on the ZOI size,insulation

location, and break location.

d. Calculate the quantity of each type of qualified coatings debris based on the ZOI size,break location, and coatings location.

e. Determine the quantity of unqualified coatings debris based on plant walkdowns andlogs. Also determine the timing for the coatings failure.f. Determine the quantity of latent debris based on plant walkdowns.

g. Determine the quantity of miscellaneous debris based on plant walkdowns.

h. Define the debris characteristics (size and density) for each type of debris.5. Analyze debris transport during each phase of the event. This includes the following steps:a. Evaluate potential blockage upstream of the strainer.

Page 87 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2b. Calculate debris transport during the blowdown phase based on the type and size ofdebris generated inside the ZOI, the break location, and the grating locations.

c. Calculate debris transport during the washdown phase based on the type and size ofdebris in upper containment, the spray distribution, and the grating locations.

d. Calculate debris transport during the pool fill-up phase based on the type and size ofdebris in lower containment at the end of the blowdown phase, the break and sprayflow rate, the cavity volumes below the containment floor elevation, and the poolvolume at the time when the cavities would be filled.e. Calculate debris transport during the recirculation phase based on the type and size ofdebris in the pool, the initial debris distribution at the beginning of recirculation, thepool water level, and the break, spray, and sump flow rates.f. Determine debris erosion fractions based on the type, size, and location of non-transporting pieces of debris.g. Calculate total debris transport to the strainers for each type and size of debris based onthe transport fractions for blowdown,

washdown, pool fill, recirculation, and erosion.h. Determine the time-dependent arrival of debris at the strainers based on time-dependent failure and transport considerations.

6. Determine overall head loss at the strainer and compare to the NPSH and structural margin. Thisincludes the following steps:a. Determine the clean strainer head loss.b. Calculate the conventional head loss due to fiber and particulate debris based on theflow rate and temperature.

c. Account for the increase in head loss due to chemical effects.d. Calculate the total head loss at the strainer based on the CSHL and debris bed head loss.e. Determine the strainer NPSH margin based on the pool temperature, flow rate, and gasvoid fraction, and compare results to the total strainer head loss.f. Compare the strainer structural margin to the total strainer head loss.7. Analyze air intrusion at the strainer.

This includes the following steps:a. Determine the potential for vortex formation.

b. Calculate the quantity of degasification at the strainer based on the containment

pressure, strainer submergence, strainer head loss, flow rate, and temperature.

c. Determine whether gas would transport through the strainer modules and ECCS suctionpiping to the pumps.d. Determine the impact of gas voids on the ECCS and CSS pumps.8. Determine the time-dependent quantity of debris that penetrates the strainer.

9. Evaluate ex-vessel downstream effects issues. This includes the following steps:a. Evaluate wear on pumps, valves, and other components from the penetrated debris.b. Evaluate potential clogging of small orifices from the penetrated debris.10. Evaluate in-vessel downstream effects issues. This includes the following steps:a. Analyze heat transfer issues associated with deposition of debris on the fuel rods.Page 88 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2b. Identify cases where full blockage at the bottom of the core during cold leg injection would not lead to core damage.c. Determine the boil-off flow rate required to remove decay heat from the core.d. For cases where blockage at the bottom of the core could lead to core damage,calculate time-dependent transport of debris to the core based on time-dependent penetration, SI and CS pump flow split, and core bypass flow split.e. Determine core blockage acceptance criteria based on fuel blockage test results.11. Boron precipitation

a. Identify cases where a debris bed could accelerate the onset of boron precipitation priorto hot leg injection.

b. Determine boron precipitation acceptance criteria based on debris load necessary toblock natural mixing processes.

12. Parametric evaluations

a. Modify input parameter(s) of interest.

b. Rerun CASA Grande and compare results to base case to determine influence ofparameter(s).

4.2 Structured Information Process FlowThe basic event for a LOCA scenario consists of a single accident progression that is initiated by a brokenpipe and continues for 30 days. The following outline provides a high level description of the processflow for evaluating independent LOCA scenarios.

Unlike predictive physics models (like RELAP), whichenumerate field equations and constitutive relationships, CASA Grande embodies only massconservation in the form of a first-order rate equation to track debris fractions in the containment pool.Energy balance is addressed in principle by external calculations (e.g., the pool temperature profilesdeveloped from the thermal-hydraulic modeling).

In this respect, CASA Grande is primarily anuncertainty propagation tool, but the timeline of the accident progression is determined by trackingdebris through the system circulation history.

The timeline supports externally calculated parameters such as decay heat, pool temperature, operational configurations, chemical product formation, andcoatings degradation.

It also provides a basis for comparison to time-dependent performance metricslike NPSH available, and core debris loading relative to the timing for switchover to hot leg injection.

1. Set plant failure state (number of trains and specific pumps available).

The failure statedetermines available flow rates through each train and guides operator actions via EOP.2. Randomly select a weld type/case based on relative frequency of break occurrence.

The relativefrequencies reflect susceptibility to failure.3. Randomly select a specific weld from this type/case assuming equal probability among all weldsof the same type/case.

The weld location defines P(x,y,z),

whether it is a hot leg or cold legPage 89 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2break condition, and the specific compartment in containment.

Each weld location has a pre-defined list of insulation targets that can be "seen" in every direction.

Concrete walls are theonly feature that is credited for shielding insulation from potential damage since pipes and largeequipment are assumed to have no effect on a ZOI.4. Conditional upon having a break for this specific weld type/case, sample a break diameter that isconsistent with NUREG-1829:

Dbreak FDbreaklweld case Equation 11Record break contribution to SBLOCA, MBLOCA, or LBLOCA category.

The designation ofSBLOCA, MBLOCA, or LBLOCA becomes an explicit correlation for many following physicalvariables.

5. Randomly select a complete temperature history T(t) from appropriate correlations of thermal-hydraulic trends for SBLOCA, MBLOCA, or LBLOCA events.6. Calculate radii Rijk of the three damage zones indexed by i = 1,2,3, debris sizes (fines, smallpieces, large pieces, or intact blankets) indexed byj = 1,2,3,4, and target type indexed by k,where k E K indexes insulation products in containment.

The three sets are indexed by k: Kdenotes insulation

products,

!F denotes fiber-based insulation, and £ denotes all types of debrisincluding insulation and other debris such as unqualified coatings and crud particulate; so,F c K c £L. The Rijk damage zones for Nukon are scaled to the maximum damage radius forinsulation

k. Figure 4.2.1 is an illustration that shows the nomenclature of damage for ahypothetical break that has its damage radii truncated by a wall.Page 90 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Figure 4.2.1 -Illustration of a hypothetical DEGB spherical ZOI truncated by a wall7. If Dbreak < Dpipe, choose a random direction perpendicular to the pipe according to P -U(0,2ir).

Else, ek is assigned a flag that indicates a spherical ZOI.8. Calculate intersection of damage zones with insulation targets and clip by concrete walls toobtain the amount of debris in each damage radius and debris size (i,],k),

and convert volume tomass:=k": P k diý. a Img e(e) n Viksulaton)

\ Wconcrete Equation 12Here, the "\Wconcrete" designates exclusion of those insulation targets not damaged due tostructural concrete blocking the break jet.Page 91 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision

29. Apply transport logic to obtain all ZOI-generated debris mass arrival at the pool as a function ofbreak size and compartment location.

Complex transport logic is represented here via theoperator Ftronsport:

mP(O) = Ftransport (9 M Equation 13The transport logic captures things like erosion of fibers from large pieces to fines intransforming the vector M of Mijk to the vector mP (t) of mij k (t) t = 0.10. Introduce fixed quantities of non-ZOI debris types (those in £ but not K and not addressed above) like crud particulate, latent debris, and unqualified coatings debris.11. Apply fill up transport fraction Fli, to train -'s strainer sump cavity. This mass of debris isinitially resident on each strainer, in addition to all other debris constituents that arrive overtime:mfk(O) = mlk(0) Equation 1412. At each time t, assume homogenous mixing in the pool:Cf,1k(t)

= m.j,k(O)/V (t) Equation 15While this form is never used explicitly, it is helpful to think about debris mixing, transport, andaccumulation in terms of concentration.

13. Solve coupled differential equations for mass in the pool, mass on the strainer, and mass on thecore (see Figure 4.2.2 and Figure 4.2.3 for the nomenclature setting):

dt- d d mcore(0 Vk ELtmP(0) = SA,)-, -Mkt) -m (t IV t kd k ) e=A,B,C .d kE TFdmk(t) :fyZmi(t))yQ 0M)m (t) -ivme(t),

Vk EL Equation 16dt (t) = flr k ) rn(tt_) Vk k 1d core~Mk M~t = A7 yf mi$(t) kE_dt ke=A,B,CPage 92 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2where sources Sk(t) of debris type k can be time-dependent, flow split X is the fraction of ECCSinjection that passes through the fuel, and flow split y is the fraction of total strainer flow that isinjected.

The complement (1 -y) is the fraction of total strainer flow passed to containment spray, and the complement (1 -X) is the fraction of ECCS injection that bypasses the core. Forcold leg breaks, X is determined based on the time-dependent boil-off rate. For hot leg breaks, A= 1. For simplicity in writing the equations here, the additional subscripts are suppressed andthe masses are indexed by debris type k E £. That said, the other indices matter inimplementation.

For example, the last term in Equation 16 is only present when the k indexindicates fiber, but it is also only present when the size index indicates fines.Figure 4.2.2 -Illustration of the processes local to the ECCS screenPage 93 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2(LLLLFigure 4.2.3 -Illustration of the flow paths in the reactor vessel14. Given histories of fiber and particulate debris thickness 6(t) on the strainer, compute time-dependent head loss across each strainer according to:APe(t) = H (me(t), Qe(t)) N(5,1)'tch(t)

Equation 17where the function H is given by NUREG/CR-6224 with arguments given by the vector me(t) ofm (t) for all k E £, and velocity via the flow rate Qe(t), where N(5,1) is a truncated randomvariable with a mean of 5 and unit variance, and whereDclh(t) = H 1, 8(t) < 1/16" or T(t) > N(140,5)1E, otherwise Equation 18Here, the chemical head loss 41ch takes a value of 1 if the thickness is below 1/16th of an inch orthe temperature exceeds the specified normal random variable, centered on 140 *F. Otherwise, (Dch takes the value of a shifted, and truncated, exponential random variable, which is denotedby E.15. Compare time-dependent head loss to time-dependent NPSH margin and record the scenario asa failure if:Page 94 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2max[APe(t)

-NPSH,argin(t)]

> 0t,,eEquation 19In other words, a failure is recorded for this scenario if anywhere along the 30-day time historythe head loss exceeds the NPSH margin for any strainer

-e = A, B, C. The strainer head loss andNPSH margin and other sump failure criteria are illustrated in Figure 4.2.4.VPool Free Surface, PCLFailure also occurs if R..exceeds the mechankal strength of the fi1ter screenPrMsdebbyttot?losslprMsiure dropthrough the -V zbediscompensated

,he water column downe pump (HW) less flow it(FL) and less vapor z= zsure (VP) .zPumps are operable so long as:APbe <: NPSHmargin Safety injection pumps(two in a train) arelocated below the sumpto ensure adequate NPSH avapFigure 4.2.4 -Illustration of sump failure criteria16. Compare time-dependent head loss to the strainer structural margin and record the scenario asa failure if:maxAPeO(t)

> AP,,Cjht,ieEquation 20where APmecpl is the design strainer structural strength in terms of pressure drop across thestrainer.

Page 95 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 217. Given time-dependent head loss, calculate time-dependent gas evolution and record thescenario as a failure if:max FvOid (AP" (t)) > 2% Equation 2118. For cold leg breaks, compare the time-dependent fiber accumulation on the core against theassumed 7.5 g/FA threshold.

Record the scenario as a failure if maxt me "(t) > 7.5gIFA.19. For hot leg breaks, record the scenario as a success in terms of the core blockage and boronprecipitation criteria.

20. If any performance threshold is exceeded for the scenario, then record a failure.Figure 4.2.5 is an illustration of the processes listed above that need to be evaluated in GSI-191 for ECCSperformance during the recirculation phase.ECCS ScreenHole

(. (2 PIs)Particulate debris (chemical, other) l in the debrisflitered in the screen increases bed causes0 pressure drop pressure droBto1 miyfr FV~ i.the fraction ofdowrstreamnof the 'A the ibevolume~

sto hi to dth ta vupressure drops 11 lafidw "'eanFiberpenetratione

~~ through screcontdbutes to mFigure 4.2.5 -Illustration of processes local to the strainer with a direct impact on the performance thresholds Page 96 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 24.3 Uncertainty Quantification and Propagation As discussed above, the steps listed in Section 4.2 provide a high level illustration of the calculations within CASA Grande for a single scenario.

That specific scenario includes numerous random realizations including the selection of the specific weld location where the break occurs, the effective size of thebreak, the direction of the break on the pipe, etc. Although it is not always explicitly stated in theSection 4.2 description, many of the steps outlined depend on the specifics of the scenario.

To construct a Monte Carlo estimator of the failure probability, these steps would be replicated many times.However, CASA Grande does not simply construct a so-called nalive Monte Carlo estimator.

Rather,techniques are used to reduce the variability of the failure probability calculations and to propagate uncertainties (such as the epistemic uncertainty in the initiating frequency) to the PRA, where thesefailure probabilities become branch fractions at the top event.GSI-191 eValuations include complex calculations with numerous areas of uncertainty.

In some cases,conservative values were selected for input parameters, but in many cases, probability distributions were developed to evaluate the full realistic range of conditions.

The probability distributions for eachparameter were sampled and propagated with the appropriate weighting to realistically determine therisk associated with GSI-191 phenomena.

The detailed methodology for uncertainty quantification andpropagation is described in a report by UT Austin (74).4.4 Verification and Validation A verification and validation (V&V) process is used to ensure that software fulfills the intended purpose.Verification tests are performed to ensure that the software has been correctly programmed (i.e., itcorrectly solves the equations that it is intended to solve). Validation tests are performed to ensure thatthe software correctly models the conditions and physical phenomena (i.e., the equations accurately represent reality).

Since CASA Grande was not developed as a generic software

package, but was simply used as anevaluation tool for the STP risk-informed GSI-191 calculations, it was not put through a formal V&Vprocess.

However, it was independently checked and reviewed following an approach similar to a typicalengineering calculation.

This review included a series of hand and alternate software calculations thatwere compared to the results of CASA Grande (75)18.18 Note that the verification report has not been updated to reflect the recent changes to CASA and Volume 3.Page 97 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 25 AnalysisThis section describes the physical models used in CASA Grande and the calculations performed todetermine debris generation, debris transport, strainer head loss, chemical

effects, air intrusion, strainerdebris penetration, ex-vessel downstream

effects, core blockage, and boron precipitation.

5.1 Evaluation Scenarios (PRA Branch Fractions to Populate)

The STP PRA evaluates LOCA scenarios that fall into the categories of small breaks (up to 2 inches),medium breaks (2 to 6 inches) and large breaks (greater than 6 inches).

The PRA also evaluates a varietyof equipment failure scenarios and different operating modes. To populate specific PRA branch fractions related to GSI-191 phenomena, it is necessary to evaluate the full range of potential scenarios.

As discussed in Assumption 1.a, the CASA Grande evaluation was only performed for full poweroperation (Mode 1). The full spectrum of break sizes was evaluated and subsequently binned into thesmall, medium, and large categories.

Potential equipment failures that can affect the GSI-191 analysesinclude pump failures (either individual pumps or full trains) and fan cooler failures.

The most significant variable affected by the failure of fan coolers is the containment pool temperature.

This is evaluated aspart of the thermal-hydraulic analysis (5), but was not explicitly evaluated in CASA Grande. Pumpfailures, on the other hand, are much more important to the overall GSI-191 analysis, and therefore were directly evaluated by running multiple scenarios with different combinations of pump failures.

STP has a configuration of three trains with one sump per train. Each train has 3 pumps, an LHSI pump,an HHSI pump, and a CS pump. The maximum pump flow rates are 2,800 gpm for each of the LHSIpumps, 1,620 gpm for each of the HHSI pumps, and 2,600 gpm for each of the CS pumps (see Section2.2.8). Variations in the pump flow rates affect several important areas of the overall GSI-191evaluation, so pump failure scenarios must be carefully evaluated.

The following list provides theprimary areas that are impacted by pump flow rates:1. Washdown Transport:

Washdown transport is a function of the total CS flow rate for all pumps.However, based on Assumption 6.h, the washdown transport fractions were assumed to beconstant for all breaks.2. Recirculation Transport:

Recirculation transport is a function of the total break flow rate (HHSIplus LHSI) and the total CS flow rate. Higher pump flow rates would increase the pool turbulence in the locations where the break and spray flow enters the pool, and would also increase thepool velocities in the approach paths to the strainers.

However, since large pieces of debriswould not reach the pool for most scenarios (e.g., breaks inside the SG compartments),

and finedebris would transport to the strainers even at relatively low flow rates, flow rate variations onrecirculation transport would essentially only affect the transport fraction for small pieces ofPage 98 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2fiberglass debris. Based on Assumption 6.h, however, the recirculation transport fractions wereassumed to be constant for all breaks.3. Debris Accumulation:

Since fine debris would be transported in suspension, the accumulation onthe strainers would be proportional to the flow split (i.e., if one sump has twice as much flow asanother sump, the debris load on that sump strainer will be twice as high as the other strainer).

4. Approach Velocity:

The approach velocity for each strainer is equal to the sump flow divided bythe strainer area for each train.5. Strainer Head Loss: The head loss for each strainer is a function of the quantity of debris on thestrainer and the strainer approach velocity.

6. Degasification:

The quantity of air released from solution for each sump is a function of thestrainer head loss and the flow rate through the strainer for each train.7. Strainer Debris Penetration:

The quantity of fiber debris that penetrates each strainer is afunction of the debris quantity that reaches the strainer and the penetration timing is a functionof the flow rate through the strainer.

8. Reactor Vessel Debris Quantity:

The quantity of fiber debris that reaches the reactor vessel is afunction of the strainer debris penetration and the flow split between the CS pumps and the SIpumps for each train.9. Core Accumulation:

The fraction of the debris entering the reactor vessel that accumulates onthe core in cold leg breaks is the ratio of the core boil-off rate due to decay heat to the flowentering the vessel.These effects are discussed in more detail in the following sections.

Any combination of pumps could faildue to mechanical

problems, giving a total of 512 possible combinations for the STP configuration.

However, the number of cases that need to be analyzed can be reduced if certain assumptions aremade. By applying Assumption 2.a (failures in one train are indistinguishable from failures in anothertrain) and Assumption 2.b (combination of pump failures in one train is worse than the samecombination of pump failures in separate trains),

the total number of pump combination states can bereduced to 64. The frequency for each of these pump combination states is provided in Section 2.2.4.Since the pump combination states with a frequency less than 2E-09 would have a negligible impact onthe overall CDF and LERF, these cases can be conservatively assumed to all go to failure withoutsignificantly affecting the overall results (see Assumption 2.f). This eliminates 48 low frequency pumpcombination states. Table 5.1.1 shows the sixteen pump combination states that have a frequency higher than 2E-09.By applying Assumption 2.c (bounding strainer debris accumulation and approach velocity) andAssumption 2.d (bounding core accumulation),

the total number of cases can be reduced to five pumpcombination states that need to be evaluated.

Note that since one CS pump is procedurally securedwhenever all three CS pumps are confirmed to be operating (before the start of recirculation),

caseswith 2 CS pumps operating are essentially identical to cases with all 3 CS pumps operating.

Page 99 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Table 5.1.1 -Bounding or representative cases for highest frequency pump combination statesWorking Working Working Pump Bounding BoundingWokig WokigState Case for Case forCase HHSI LHSl CS CommentsFrequency Strainer VesselPumps Pumps Pumps (yr.1) Failure Failure1 3 3 3 2.64E-04 Case 1 Case 1 One CS pumpprocedurally secured2 3 3 2 3.32E-06 Case 1 Case 1 Identical to Case 13 3 3 1 7.53E-08 Case 22 Case 94 3 3 0 9.77E-09 Case 1 Case 95 3 2 3 3.49E-06 Case 22 Case 9 One CS pumpprocedurally secured6 3 2 2 4.38E-08 Case 22 Case 9 Identical to Case 59 3 1 3 3.22E-08 Case 9 Case 9 One CS pumpprocedurally secured17 2 3 3 1.94E-06 Case 22 Case 9 One CS pumpprocedurally secured18 2 3 2 2.44E-08 Case 22 Case 9 Identical to Case 17One CS pump21 2 2 3 1.17E-07 Case 22 Case 22 procedurally secured,Identical to Case 2222 2 2 2 9.16E-06 Case 22 Case 22 Single train failure23 2 2 1 7.81 E-08 Case 26 Case 2626 2 1 2 6.03E-08 Case 26 Case 2633 1 3 3 2.67E-08 Case 22 Case 9 One CS pumpprocedurally secured38 1 2 2 3.54E-08 Case 26 Case 2643 1 1 1 4.34E-08 Case 43 Case 43 Dual train failureThe scenarios that were explicitly evaluated in CASA Grande were:* Case 1: Full train operation

Case 22: Single train failure" Case 43: Dual train failure* Case 9: Two LHSI pump failures" Case 26: Single train failure with failure of one additional LHSI pumpAll other high frequency pump state cases are bounded by these five pump combination states as shownin Table 5.1.1.Page 100 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 25.2 Containment CAD ModelA CAD model of the STP containment building was developed to perform a variety of GSI-191calculations as well as to define the geometry in CASA Grande (4). The details included in the CAD modeland specific containment features are illustrated in Figure 5.2.1 through Figure 5.2.20.Page 101 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.1 -Cross-section of steam generator compartment with Loops B and CFigure 5.2.2 -Close-up view of steam generator compartment with Loops B and CPage 102 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Figure 5.2.3 -Operating deck (Elevation 68'-0")Page 103 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Figure 5.2.4 -Piping and equipment (View 1)Page 104 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Figure 5.2.5 -Piping and equipment (View 2)Page 105 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.6 -Steam generator compartment floor (Elevation 19'0")Page 106 of 248 30-inchvent holes -South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Sump CSump B"Sump AFigure 5.2.7 -Plan view of containment floor (Elevation

-11'3")Page 107 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Figure 5.2.8 -Isometric view of containment floor (Elevation

-11'3")Page 108 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.9 -Plan view of major piping and equipment Page 109 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2El 68'-0" --El 19'-0"El (-11)'-3" jFigure 5.2.10 -Section view of RCS Loop D (left) and Loop A (right)Page 110 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2El 68'-0" -El 19'-0"El 5'-9"El (-11)'-3"

--El (-2)'-0"Figure 5.2.11 -Section view of RCS Loop D (left) and Loop C (right)Page 111 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Figure 5.2.12 -Nukon insulation on piping, pressurizer, pumps, and heat exchangers Page 112 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.13 -Thermal-Wrap insulation on steam generators Page 113 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Figure 5.2.14 -Microtherm insulation in secondary shield wall penetrations Page 114 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.15 -Lead blankets on pipesPage 115 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.16 -Welds representing potential LOCA break locations (View 1)Figure 5.2.17 -Welds representing potential LOCA break locations (View 2)Page 116 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.18 -Currently installed ECCS strainers Page 117 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2m -.qFigure 5.2.19 -Illustration of additional insulation modeled at hanger and valve locations Page 118 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 216RC-1412-NSS-1 16RC-1412-NSS-8, 16RC-1412-NSS-7

-HLSO04"- 16RC-1412-NSS-4 Figure 5.2.20 -Illustration of work points used to identify location of welds, hangers, and valvesThe geometrical details of the pipes, pipe insulation, and work points (weld, hanger, and valve locations) were exported from the CAD model to a text format. As shown in Figure 5.2.21, the text data includesthe part name (which specifies the line number and insulation type if applicable),

the coordinates for thejunction of each pipe segment, the bend radius for curved portions of the pipe, the inner and outerdiameters (either of the pipe or insulation depending on the part), and a text identifier for any workpoints that are included on the line. The text data was imported into CASA Grande to define thegeometry of the piping and associated insulation.

The insulation associated with the equipment (steam generators, pumps, and pressurizer) was definedby creating primitive shapes based on the dimensions of significant features of the equipment defined inthe CAD model.The concrete walls and floors were exported from the CAD model and imported into CASA Grande instereolithography (STL) format to define robust barriers that would protect some insulation from thebreak jet. The concrete STL file is shown in Figure 5.2.22.Page 119 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 211-09-21 South Texas Plant.iam Number of Points = 3. Number of straights

= 1. unit of Length = Inches..ipt Name, Point,X,Y,Z, Rad, ID,OD,WP0.75RC-1002-BB2

[NUKON]:1,0,97.81,-594.19,998,0,1.05,5.05, 0.75RC-1002-BB2

[NUKON]:1,1,94.56,-594.19,998,0,1.05,5.05,FWO002 0.75RC-1002-BB2

[NUKON]:1,2,86.06,-594.19,998,0,1.05,5.05,FWOOO0 Point to Point Length: 11.7511-09-21 south Texas Plant.iam Number of Points = 3. Number of straights

= 2. unit of Length = Inches..ipt Name,Point,X,Y,Z,Rad,ID,OD,WP 0.75RC-1006-ea1

[NUKON]:1,0,28.6,-725.86,1199.92,0,1.05,6.05, 0.75RC-1006-BB1

[NUKON]:1,1,21.71,-720.48,1199.92,0,1.05,6.05, 0.75RC-1006-BB1

[NUKONJ:1,2,21.71,-720.48,1209.19,0,1.05,6.05, Point to Point Length: 18.0211-09-21 South Texas Plant.iam Number of Points = 14. Number of straights

= 11. unit of Length = Inches..ipt Name,Point,X,Y,2,Rad,ID,OD,WP 0.75RC-1007-BD7

[NUKON]:1,0,2.43,-606,1173.07,0,1.05,6.05, 0.75RC-1007-BD7

[NUKON]:1,1,2.43,-606,1181.82,0,1.05,6.05, 0.75Rc-1007-BD7

[NUKON]:1,2,15.83,-616.47,1181.82,0,1.05,6.05, 0.75RC-1007-BD7

[NUKON]:1,3,15.83,-616.47,1199.92,0,1.05,6.05, 0.75RC-1007-BD7

[NUKONI:1,4,83.5,-669.34,1199.92,0,1.05,6.05, 0.75RC-1007-BD7

[NUKON]:1,5,35.27,-731.07,1199.92,0,1.05,6.05, 0.75RC-1007-BD7

[NUKON]:1,6,28.6,-725.86,1199.92,0,1.05,6.05, Point to Point Length: 216.520.75RC-1007-BD7

[NUKONJ:1,0,53.95,-646.25,1199.92,0,1.05,6.05, 0.75RC-1007-BD7

[NUKONJ:1,1,48.71,-652.95,1199.92,0,1.05,6.05, 0.75RC-1007-BD7

[NUKON]:1,2,6.2,-619.73,1199.92,0,1.05,6.05, 0.75RC-1007-BD7

[NUKONJ:1,3,0.38,-627.18,1199.92,0,1.05,6.05, Point to Point Length: 71.910.75RC-1007-BD7

[NUKONJ:1,0,59.58,-699.94,1199.92,0,1.05,6.05, 0.75RC-1007-BD7

[NUKONJ:1,1,46.16,-689.46,1199.92,0,1.05,6.05, 0.75RC-1007-BD7

[NUKON]:1,2,51.55,-682.56,1199.92,0,1.05,6.05, Point to Point Length: 25.78Figure 5.2.21 -Example of CAD model text data outputPage 120 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.22 -Concrete walls and floors exported from CAD model in STL formatFigure 5.2.23 shows the geometry of the piping and equipment insulation in CASA Grande.Page 121 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.2.23 -Geometry of piping and equipment insulation in CASA Grande5.3 LOCA Frequency Determining the initiating event frequency is a key requirement in performing a risk-informed evaluation.

Estimating the frequencies for LOCA pipe breaks, particularly larger breaks, is challenging since there is limited data from operating experience (due to the very low probabilities of these breaksoccurring).

The best generic estimates for LOCA frequencies are based on an expert elicitation processthat was documented in NUREG-1829 (37). NUREG-1829 provides LOCA frequencies as a function ofbreak size for both BWR and PWR plants. These values are total frequencies that include all potential primary-side break locations.

However, since two equivalent-size breaks in different locations may havea significantly different likelihood of occurrence as well as a significantly different effect on GSI-191related phenomena (e.g., quantity of debris generated, transport fractions, in-vessel flow paths, etc.),the total frequencies for all possible break locations must be broken down into the specific frequencies for each break location.

The LOCA frequencies must then be appropriately sampled to evaluate the fullrange of potential LOCA scenarios.

This was done using the following steps, each of which is explained infurther detail in subsequent sections:

Page 122 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-VO3 Revision 2A. Calculate the relative weight of breaks for specific weld categories based on pipe size, weld type,applicable degradation mechanisms, etc., and distribute total LOCA frequency to each weldlocation based on relative weight between weld cases.B. Identify applicable weld category and spatial coordinates.for each weld location.

C. Statistically fit the NUREG-1829 frequencies (5th, Median, and 95th) using a bounded Johnsondistribution for each size category.

These fits represent the epistemic uncertainty associated with LOCA frequencies.

D. Sample epistemic uncertainty (e.g., 62nd percentile) and determine the corresponding totalfrequency curve based on the bounded Johnson fits (assuming linear interpolation between sizecategories).

E. Sample break sizes at each weld location and proceed with the GSI-191 analysis carrying theappropriate probability weight with each break scenario.

Table 2.2.3 through Table 2.2.10 define the annual frequency of breaks as a function of size for each ofthe weld cases. The tables are accepted as input to CASA Grande as an Excel file, which includes areference list that assigns every weld in containment to one of the defined cases. The units of any pair ofcolumns defining a weld case are break size in inches (Column 1 of a pair) and annual break frequency innumber of breaks per year of size greater than x per weld (Column 2 of a pair), where x is any break sizein Column 1. The purpose of the information in the break-frequency table is to support hybrid breakfrequency assignment (8) by defining relative proportions of break frequency across the weld typeswithin any break size range of interest.

Table 2.2.3 through Table 2.2.10 provide the link betweenaggregate annual break frequencies defined by NUREG-1829 and the assignment of breaks to specificlocations in containment.

Table 2.2.3 through Table 2.2.10 incorporate industry data on break size and weld failure modes in thebottom-up approach for break frequency estimation.

Many of the values in Table 2.2.3 through Table2.2.10 were populated using a log-log interpolation scheme based on arguments invoking fracturemechanics and distributions of observed break sizes. However, as discussed in Assumption 3.e, all break-frequency interpolation was consistently performed using linear-linear interpolation.

Therefore, it wasnecessary to filter out log-log interpolated values from each weld case. Interpolated values wereidentified as co-linear points in log-log space and eliminated from each weld case table.The respective break frequencies were scaled by multiplying by the number of welds in each case anddividing all break frequency entries by the annual total frequency, including all sizes and all weld cases.The number of welds in each case was carefully verified to be consistent with the weld count in the STPCAD model (see Section 5.3.1). Division by the total annual break frequency is not strictly

required, but itemphasizes that the purpose of the table is to define the joint probability distribution that existsbetween break size and weld type. A weld case provides a categorical representation of location withinthe plant as specified by the CAD model.Page 123 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2All break-size intervals needed to support the Latin hypercube sampling (LHS) design were determined across all weld categories and linear-linear interpolation was used to populate each weld category at acommon list of break sizes. There can be a very long list of unique size bins that is determined by theLHS design size, but recall that the sample design preserves the definition of LOCA categories so thatbreak-size intervals never span the LOCA-bin limits.The hybrid break frequency assignment (8) was implemented.

Each uncertainty percentile sampled fromthe Johnson break-size frequency envelope (see Section 5.3.4) was first divided by the total annualbreak frequency to form a conditional probability distribution, and the probability of experiencing abreak within each bin of the common break-size interval list was calculated.

The probability ofexperiencing a break within each interval was then distributed across all weld cases that can support abreak of the given size. Relative probabilities between weld cases supporting the break-size intervaldetermine the proportion assigned to each weld case. Thus, the aggregate frequency specified by thetop-down approach of NUREG-1829 is preserved while the distribution of breaks among weld typesspecified by the bottom-up approach is also preserved.

This equivalence is the essence of the hybridmethodology.

Examples of the hybrid method (8) and the CASA implementation differ only in thenumber of size categories that are manipulated.

The frequencies for each weld location were determined by assigning an equal probability ofexperiencing a given break size for every weld assigned to a given weld case (for each sample of theJohnson uncertainty envelope).

The rebalanced table resulting from systematic mapping of each break-size bin across the weld caseswas used to calculate LHS sample weights associated with every break scenario that was evaluated.

Thehybrid break frequency assignment was repeated as necessary for each sample of the Johnsonuncertainty profile that was propagated through the evaluation.

A description of the process forselecting specific break sizes from each weld category is provided in Section 5.3.5.5.3.1 Relative Weight of Breaks in Specific Weld Categories As discussed in Section 2.2.3, the relative weight of breaks in various weld locations are based onspecific degradation mechanisms for categories of welds. These frequencies were determined from ananalysis of DM-dependent weld failure rates based on service data, a Bayes method for uncertainty treatment developed in the EPRI risk-informed in-service inspection (RI-ISI)

program, and estimates ofconditional probability versus break size using information developed in NUREG-1829.

The resulting weld-specific LOCA frequencies are used to establish the relative probabilities of break size and locationthat are subsequently normalized against the NUREG-1829 frequencies.

Descriptions of the 45 uniquecategories are provided in Table 2.2.3 through Table 2.2.10, and summarized in Table 5.3.1.Page 124 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Note that the pipe size listed in Table 5.3.1 is the nominal diameter, which is treated the same as theinner diameter.

The DEGB size is the diameter of an equivalent hole with twice the inner area of thepipe (i.e., the equivalent break size given a fully offset DEGB with jets emanating from both sides of thebroken pipe), and is calculated using the following equation:

DDEGB = vr2. Di Equation 22where:DDEGB= Equivalent DEGB break size diameter assuming full pipe offsetDi = Pipe inner diameterFor the hot and cold leg piping, the nominal diameter is equal to the inner diameter.

However, thenominal diameter is larger (and in some cases significantly larger) for the higher schedule/thicker walledpipes that are 16 inches and smaller.

For example, the surge line is a 16-inch, Schedule 160 pipe, whichhas an inner diameter of 12.81 inches. Therefore, the actual DEGB size would be 18.12 inches ratherthan 22.63 inches as shown in Table 5.3.1.The weld types include:* ASME Xl Category B-F welds (bimetallic)

ASME Xl Category B-J welds (single metal)* Branch connection (BC) welds, which are B-J welds used at branch connections The degradation mechanisms include:* Design and construction defects (D&C)* Intergranular stress corrosion cracking (IGSCC)* Transgranular stress corrosion cracking (TGSCC)" Primary water stress corrosion cracking (PWSCC)* Thermal fatigue (TF)" Vibration fatigue (VF)As discussed in Section 5.3.2 and Assumption 3.g, the weld count provided in Section 2.2.3 are notconsistent with the CAD model for all break categories.

Therefore, the weld counts were modifiedslightly in Table 5.3.1, and the values that were modified are marked with an asterisk.

Also, Category 6Bcontains two weld sizes (nominal 0.75-inch and 1-inch pipes), and Categories 6A and 8C contain twoweld sizes (nominal 1.5-inch and 2-inch).

As noted in the tables, the different weld sizes were capturedas subcategories.

Page 125 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSl191-V03 Revision 2Table 5.3.1 -Description of weld categories Nominal ActualDEGB WeldCategory System Pipe Size Pipe Size (in) Type DM No. Welds(in) (in)6B-1 0.75* 0.614 0.87 176Small Bore B-J VF, SC, D&C6B-2 1 0.815 1.15 177L SIR 1.5 N/A N/A B-J D&C 051 Pressurizer 2 1.689 2.38 B-J TF, D&C 26A-1 1.5* 1.338 1.89 1*Small Bore B-J VF, SC, D&C6A-2 2 1.689 2.38 23*7K SIR 2 1.689 2.38 BC D&C 11*8A CVCS 2 1.689 2.38 B-J TF, VF, D&C 108C-1 1.5* 1.338 1.89 8CVCS -B-i VF, D&C88C-2 2 1.689 2.38 394D Surge Line 2.5 2.125 3.01 B-J TF, D&C 65B Pressurizer 3 2.626 3.71 B-J TF, D&C 145D Pressurizer 3 2.626 3.71 B-J D&C 471 SIR 3 2.626 3.71 BC D&C 8*5C Pressurizer 4 3.438 4.86 B-J D&C 5351 Pressurizer 4 3.438 4.86 BC D&C 271 SIR 4 3.438 4.86 BC D&C 58B CVCS 4 3.438 4.86 B-J TF, VF, D&C 198D CVCS 4 3.438 4.86 B-J VF, D&C 68E CVCS 4 3.438 4.86 BC TF, D&C 48F CVCS 4 3.438 4.86 BC D&C 15A Pressurizer 6 5.189 7.34 B-J TF, D&C 28*5E Pressurizer 6 5.189 7.34 B-J D&C 295F Pressurizer 6 5.189 7.34 B-F SC, TF, D&C 4*5G Pressurizer 6 N/A N/A B-F SC, D&C 05H Pressurizer 6 5.189 7.34 B-F D&C (Weld Overlay) 47H SIR 6 5.189 7.34 B-J D&C 237B SIR 8 6.813 9.64 B-J TF, D&C 97C SIR 8 6.813 9.64 B-J SC, TF, D&C 37G SIR 8 6.813 9.64 BC, B-J D&C 427F SIR 10 8.500 12.02 B-J D&C 307A SIR 12 10.126 14.32 B-J TF, D&C 217D SIR 12 10.126 14.32 B-J SC, D&C 37E SIR 12 10.126 14.32 BC, B-J D&C 577M ACC 12 N/A N/A B-J SC, D&C 07N ACC 12 10.126 14.32 B-J TF, D&C 3570 ACC 12 10.126 14.32 BC, B-J D&C 154A Surge Line 16 12.814 18.12 B-F SC, TF, D&C 1Page 126 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Nominal ActualDEGB WeldCategory System Pipe Size Pipe Size (in) Type DM No. Welds(in) (in)4B Surge Line 16 12.814 18.12 B-J TF, D&C 74C Surge Line 16 12.814 18.12 BC TF, D&C 23A Cold Leg 27.5 27.500 38.89 B-F SC, D&C 43C Cold Leg 27.5 27.500 38.89 B-J D&C 121A Hot Leg 29 29.000 41.01 B-F SC, D&C 4lB Hot Leg 29 29.000 41.01 B-J D&C 111C Hot Leg 29 29.000 41.01 B-J TF, D&C 12 SG Inlet 29 29.000 41.01 B-F SC, D&C 43B Cold Leg 31 31.000 43.84 B-F SC, D&C 43D Cold Leg 31 31.000 43.84 B-J D&C 24Total 786*5.3.2 Weld Categories and Coordinates The weld categories and locations for each weld were determined based on a LOCA frequency component database (9) and the containment building CAD model (4). Both the database and CADmodel are based on STP's in-service inspection (ISI) drawings.

Table 5.3.3 shows the relevant weld datafrom these two sources.

Note that there were a few discrepancies between the LOCA frequency report(7), the component database (9), and the CAD model (4). The discrepancies are listed below and werecorrected in Table 5.3.3. Note that the corrections are marked with an asterisk.

Weld 31-RC-1102-NSS-5 is listed in the database as Category 71 on a 3-inch pipe. However,according to the CAD model, this is a 2-inch pipe and therefore the weld falls within Category7K.* The component database was updated with a modification to the weld category identifiers afterthe LOCA frequency report was issued. Category 5G corresponds to B-J welds on 6-inchpressurizer piping susceptible to failures from D&C and PWSCC damage mechanisms.

Four weldsat STP that fit this category have weld overlays that eliminate the PWSCC damage mechanism.

This was evaluated as a Category 5G sensitivity in the component

database, but was included asCategory 5H in the LOCA frequency report. Similarly, Categories 5H and 51 in the component database correspond to Categories 51 and 5. in the LOCA frequency report. To clear this up, thewelds falling in these categories were adjusted in Table 5.3.3 to match the categories identified in the LOCA frequency report.* Twenty-one 2-inch welds that are included in the CAD model were not explicitly identified in thecomponent database.

These welds were assigned to Category 6A.* As discussed in Section 5.3.1, the pipe size provided in the LOCA frequency report is the nominalpipe diameter.

The actual pipe diameter is typically smaller than the nominal diameter, whichPage 127 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2also affects the equivalent DEGB size. The pipe diameter differences between the LOCAfrequency report and the CAD model are shown in Table 5.3.2.There are also a few differences between the weld count provided in the LOCA frequency reportand the CAD model as shown in Table 5.3.2. The most notable difference is the weld count forCategory 6B. The LOCA frequency report lists 193 welds in this category, but the CAD model andthe component database only contain a total of 35 of these welds. Upon review, the missingwelds appear to be locations where 0.75-inch pipes (drain lines, etc.) are connected to largerpiping. As shown in Figure 5.3.1, the 35 welds that were modeled are scattered throughout containment.

Given the scattered distribution, and the relatively low significance with respect toGSI-191 phenomena for this size of breaks, it is reasonable to distribute the overall breakfrequency for the 193 welds to the 35 welds that were modeled (see Assumption 3.f). For otherweld categories, the weld count in the CAD model was assumed to be more accurate than theweld count in the LOCA frequency report (see Assumption 3.g).Table 5.3.2 -Comparison of LOCA frequency report and CAD model pipe sizes and weld countsCt Report Pipe CAD Pipe Report CAD DEGB Report Weld CAD WeldSize (in) Size (in) DEGB (in) (in) Count Count6B-1 1 0.614 1.41 0.87 326B-2 0.815 1.15 37L 1.5 N/A 2.12 N/A 0 05J 2 1.689 2.83 2.38 2 26A-1 1.338 1.89 16A-2 1.689 2.38 237K 2 1.689 2.83 2.38 10 118A 2 1.689 2.83 2.38 10 108C-1 2 1.338 2.83 1.89 88C-2 1.689 2.38 394D 2.5 2.125 3.54 3.01 6 65B 3 2.626 4.24 3.71 14 145D 3 2.626 4.24 3.71 4 47J 3 2.626 4.24 3.71 9 85C 4 3.438 5.66 4.86 53 5351 4 3.438 5.66 4.86 2 271 4 3.438 5.66 4.86 5 58B 4 3.438 5.66 4.86 19 198D 4 3.438 5.66 4.86 6 68E 4 3.438 5.66 4.86 4 48F 4 3.438 5.66 4.86 1 15A 6 5.189 8.49 7.34 29 285E 6 5.189 8.49 7.34 29 295F 6 5.189 8.49 7.34 0 45G 6 N/A 8.49 N/A 0 0Page 128 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Report Pipe CAD Pipe Report CAD DEGB Report Weld CAD Weldategory Size (in) Size (in) DEGB (in) (in) Count Count5H 6 5.189 8.49 7.34 4 47H 6 5.189 8.49 7.34 23 237B 8 6.813 11.31 9.64 9 97C 8 6.813 11.31 9.64 3 37G 8 6.813 11.31 9.64 42 427F 10 8.500 14.14 12.02 30 307A 12 10.126 16.97 14.32 21 217D 12 10.126 16.97 14.32 3 37E 12 10.126 16.97 14.32 57 577M 12 N/A 16.97 N/A 0 07N 12 10.126 16.97 14.32 35 3570 12 10.126 16.97 14.32 15 154A 16 12.814 22.63 18.12 1 14B 16 12.814 22.63 18.12 7 74C 16 12.814 22.63 18.12 2 23A 27.5 27.500 38.89 38.89 4 43C 27.5 27.500 38.89 38.89 12 121A 29 29.000 41.01 41.01 4 41B 29 29.000 41.01 41.01 11 11IC 29 29.000 41.01 41.01 1 12 29 29.000 41.01 41.01 4 43B 31 31.000 43.84 43.84 4 43D 31 31.000 43.84 43.84 24 24Total 1 775 628Page 129 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1291-V03 Revision 2Figure 5.3.1 -Locations of Category 6B welds that were modeledPage 130 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 5.3.3 -Weld data from component database and CAD modelNo. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 1 2-CV-1122-BB1 0.75-CV-1122-BB1-1 CV Small Bore 6B-1 0.614 -391.858

-245.642 497.125 Cold SG Compartment 2 2-CV-1122-BB1 0.75-CV-1122-BB1-2 CV Small Bore 6B-1 0.614 -391.858

-260.642 513 Cold SG Compartment 3 2-CV-1124-BB1 0.75-CV-1124-BB1-1 CV Small Bore 6B-1 0.614 -334.812 342.313 513 Cold SG Compartment 4 2-CV-1124-BB1 0.75-CV-1124-BB1-2 CV Small Bore 6B-1 0.614 -334.812 329.313 525 Cold SG Compartment 5 2-CV-1126-BB1 0.75-CV-1126-BBI-1 CV Small Bore 6B-1 0.614 399 269.313 477 Cold SG Compartment 6 2-CV-1126-BB1 0.75-CV-1126-BB1-2 CV Small Bore 6B-i 0.614 399 260.313 513 Cold SG Compartment 7 2-CV-1128-BB1 0.75-CV-1128-BB1-1 CV Small Bore 6B-i 0.614 350.702 -324.25 563.438 Cold SG Compartment 8 2-CV-1128-BB1 0.75-CV-1128-BB1-2 CV Small Bore 6B-1 0.614 341.702 -324.25 563.438 Cold SG Compartment 9 4-RC-1003-BB1 0.75-RC-1001-BBl-1 RC Small Bore 6B-1 0.614 108.001 -648.001 998 Cold PZR Compartment 10 4-RC-1000-BB1 0.75-RC-1002-BB2-1 RC Small Bore 6B-1 0.614 97.812 -594.189 998 Cold PZR Compartment 11 12-RC-1112-BBI 0.75-RC-1112-BB1-1 RC Small Bore 6B-1 0.614 -30.55 -261.662 456.035 Hot SG Compartment 12 8-RC-1114-BB1 0.75-RC-1114-BB1-i RC Small Bore 6B-1 0.614 -141.33 -226.374 483 Hot SG Compartment 13 12-RC-1125-BB1 0.75-RC-1125-BB1-1 Sl-ACC-CL1 Small Bore 6B-i 0.614 -270.999

-310.539 548.204 Cold SG Compartment 14 12-RC-1125-BBI 0.75-RC-1125-BB1-2 Sl-ACC-CL1 Small Bore 6B-1 0.614 -265.077

-384.343 273.017 Cold Below SG Compartment 15 4-RC-1126-BB1 0.75-RC-1126-BB1-1 RC Small Bore 6B-i 0.614 -236 -91.56 507 Cold SG Compartment 16 12-RC-1212-BBI 0.75-RC-1212-BB1-1 RC Small Bore 6B-1 0.614 -30.551 261.636 456.007 Hot SG Compartment 17 8-RC-1214-BB1 0.75-RC-1214-BB1-I RC Small Bore 6B-1 0.614 -143.269 225.591 483 Hot SG Compartment 18 12-RC-1221-BB1 0.75-RC-1221-BBl-1 Sl-ACC-CL2 Small Bore 6B-1 0.614 -270.999 310.309 548.169 Cold SG Compartment 19 12-RC-1221-BB1 0.75-RC-1221-BB1-2 Sl-ACC-CL2 Small Bore 6B-i 0.614 -265.077 384.113 273.006 Cold Below SG Compartment 20 12-RC-1312-BB1 0.75-RC-1312-BB1-1 RC Small Bore 6B-1 0.614 54.55 261.662 455.999 Hot SG Compartment 21 8-RC-1324-BB1 0.75-RC-1324-BBl-1 RC Small Bore 6B-1 0.614 165.148 223.469 492 Hot SG Compartment 22 4-RC-1422-BB1 0.75-RC-1423-BB1-1 RC Small Bore 6B-1 0.614 108.001 -612.751 984 Cold PZR Compartment 23 8-SI-1108-BBI 0.75-51-1130-BB2-1 RC Small Bore 6B-1 0.614 -310.37 -395.39 483 Hot SG Compartment 24 12-SI-1125-BB1 0.75-SI-1132-BB1-1 RC Small Bore 6B-1 0.614 -390.942

-354.644 273.017 Cold Below SG Compartment 25 12-S1-1218-BB1 0.75-S1-1218-BB1-1 SI Small Bore 6B-1 0.614 -364.072 381.285 273.006 Cold Below SG Compartment 26 8-S1-1208-BB1 0.75-51-1223-BB2-1 RC Small Bore 6B-1 0.614 -313.12 395.46 483 Hot SG Compartment 27 12-S1-1315-BB1 0.75-Sl-1315-BB1-1 SI-ACC Small Bore 6B-1 0.614 312.427 331.154 548.194 Cold SG Compartment 28 12-SI-1315-BB1 0.75-SI-1323-BBI-1 SI-ACC Small Bore 6B-1 0.614 345.971 364.697 191.014 Cold Below SG Compartment 29 6-SI-1327-BB1 0.75-51-1327-BB1-1 Sl Small Bore 6B-1 0.614 361.366 383.719 491.924 Hot SG Compartment 30 8-S1-1327-BB1 0.75-S1-1327-BB1-2 SI Small Bore 6B-1 0.614 335.604 393.925 540 Hot SG Compartment 31 8-S1-1327-BB1 0.75-SI-1327-BB1-3 SI Small Bore 6B-1 0.614 200.944 259.265 492 Hot SG Compartment 32 8-SI-1327-BBI 0.75-S1-1328-BB2-1 SI Small Bore 6B-1 0.614 360.352 397.461 491.924 Hot SG Compartment 33 6-RC-I003-BB1 1-RC-1003-BBI-1 RC Small Bore 6B-2 0.815 53.272 -636.728 1263 Cold PZR Compartment 34 4-RC-1123-BB1 1-RC-1123-BB1-1 RC Small Bore 6B-2 0.815 -18.187 -516.189 807 Cold SG Compartment 35 4-RC-1422-BB1 1-RC-1422-BB1-1 RC Small Bore 6B-2 0.815 108.001 -607.626 984 Cold PZR Compartment 36 16-RC-1412-NSS 1.5-RC-1412-NSS-1 RC 6A-1 1.338 165.003 -507 526.221 Hot SG Compartment 37 2(1.5)-CV-1122-BB1 2(1.5)-CV-1122-BB1-1 CV -RCP1A 8C-1 1.338 -391.86 -260.64 551.44 Cold SG Compartment 38 2(1.5)-CV-1122-BB1 2(1.5)-CV-1122-BB1-2 CV- RCPIA 8C-1 1.338 -381.8 -260.64 563.44 Cold SG Compartment 39 2(1.5)-CV-1124-BB1 2(1.5)-CV-1124-BB1-1 CV -RCP1B 8C-1 1.338 -334.81 323.31 563.44 Cold SG Compartment Page 131 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 40 2(1.5)-CV-1124-BB1 2(1.5)-CV-1124-BB1-2 CV -RCP1B 8C-1 1.338 -334.81 311.44 563.44 Cold SG Compartment 41 2(1.5)-CV-1126-BB1 2(1.5)-CV-1126-B81-1 CV -RCP1C 8C-1 1.338 393 260.31 563.44 Cold SG Compartment 42 2(1.5)-CV-1126-BB1 2(1.5)-CV-1126-BB1-2 CV -RCP1C 8C-1 1.338 385.94 260.31 563.44 Cold SG Compartment 43 2(1.5)-CV-1128-BB1 2(1.5)-CV-1128-BB1-1 CV -RCPID 8C-1 1.338 332.7 -318.12 563.44 Cold SG Compartment 44 2(1.5)-CV-1128-BB1 2(1.5)-CV-1128-BB1-2 CV -RCP1D 8C-1 1.338 332.7 -309.56 563.44 Cold SG Compartment 45 2-CV-1121-BB1 2-CV-1121-BB1-1 CV -PZR Auxiliary Spray Line 8A 1.689 11 -588.25 984 Cold PZR Compartment 46 2-CV-1121-BB1 2-CV-1121-BB1-2 CV -PZR Auxiliary Spray Line 8A 1.689 44.93 -588.25 1062 Cold PZR Compartment 47 2-CV-1121-BB1 2-CV-1121-BB1-3 CV -PZR Auxiliary Spray Line 8A 1.689 108 -621.5 1062 Cold PZR Compartment 48 2-CV-1122-BB1 2-CV-1122-BB1-1 CV -RCP1A 8C-2 1.689 -391.86 -212.64 497.12 Cold SG Compartment 49 2-CV-1122-BB1 2-CV-1122-BB1-2 CV -RCP1A 8C-2 1.689 -391.86 -221.64 497.12 Cold SG Compartment 50 2-CV-1122-BB1 2-CV-1122-BB1-3 CV -RCP1A 8C-2 1.689 -391.86 -229.64 497.12 Cold SG Compartment 51 2-CV-1122-BB1 2-CV-1122-BB1-4 CV -RCP1A 8C-2 1.689 -391.86 -242.64 497.12 Cold SG Compartment 52 2-CV-1122-BB1 2-CV-1122-B81-5 CV -RCP1A 8C-2 1.689 -391.86 -248.64 497.12 Cold SG Compartment 53 2-CV-1122-BB1 2-CV-1122-BB1-6 CV -RCP1A 8C-2 1.689 -391.86 -260.64 548.44 Cold SG Compartment 54 2-CV-1124-BB1 2-CV-1124-BB1-1 CV -RCPIB 8C-2 1.689 -325.97 377.65 513 Cold SG Compartment 55 2-CV-1124-BB1 2-CV-1124-BB1-2 CV -RCP1B 8C-2 1.689 -332.69 370.93 513 Cold SG Compartment 56 2-CV-1124-BB1 2-CV-1124-BB1-3 CV -RCP1B 8C-2 1.689 -334.81 365.81 513 Cold SG Compartment 57 2-CV-1124-BB1 2-CV-1124-BB1-4 CV -RCPIB 8C-2 1.689 -334.81 359.31 513 Cold SG Compartment 58 2-CV-1124-BB1 2-CV-1124-BB1-5 CV -RCP1B 8C-2 1.689 -334.81 351.31 513 Cold SG Compartment 59 2-CV-1124-BB1 2-CV-1124-BB1-6 CV -RCP1B 8C-2 1.689 -334.81 345.31 513 Cold SG Compartment 60 2-CV-1124-8B1 2-CV-1124-BB1-7 CV -RCP1B 8C-2 1.689 -334.81 339.31 513 Cold SG Compartment 61 2-CV-1124-BB1 2-CV-1124-BB1-8 CV -RCP1B 8C-2 1.689 -334.81 332.31 513 Cold SG Compartment 62 2-CV-1124-BB1 2-CV-1124-BB1-9 CV- RCP1B 8C-2 1.689 -334.81 329.31 516 Cold SG Compartment 63 2-CV-1124-BB1 2-CV-1124-B81-10 CV -RCP1B 8C-2 1.689 -334.81 329.31 522 Cold SG Compartment 64 2-CV-1124-BB1 2-CV-1124-BB1-11 CV -RCP1B 8C-2 1.689 -334.81 329.31 528 Cold SG Compartment 65 2-CV-1124-BB1 2-CV-1124-BB1-12 CV -RCPIB 8C-2 1.689 -334.81 329.31 560.44 Cold SG Compartment 66 2-CV-1124-BB1 2-CV-1124-BB1-13 CV -RCP1B 8C-2 1.689 -334.81 326.31 563.44 Cold SG Compartment 67 2-CV-1126-BB1 2-CV-1126-BB1-1 CV -RCPIC 8C-2 1.689 399 293.81 477 Cold SG Compartment 68 2-CV-1126-BB1 2-CV-1126-BB1-2 CV -RCPIC 8C-2 1.689 399 286.81 477 Cold SG Compartment 69 2-CV-1126-BB1 2-CV-1126-BB1-3 CV -RCP1C 8C-2 1.689 399 278.81 477 Cold SG Compartment 70 2-CV-1126-BB1 2-CV-1126-BB1-4 CV -RCP1C 8C-2 1.689 399 272.81 477 Cold SG Compartment 71 2-CV-1126-BB1 2-CV-1126-BB1-5 CV -RCP1C 8C-2 1.689 399 266.31 477 Cold SG Compartment 72 2-CV-1126-BB1 2-CV-1126-BB1-6 CV -RCP1C 8C-2 1.689 399 263.31 477 Cold SG Compartment 73 2-CV-1126-BB1 2-CV-1126-BB1-7 CV -RCP1C 8C-2 1.689 399 260.31 480 Cold SG Compartment 74 2-CV-1126-BB1 2-CV-1126-BB1-8 CV -RCP1C 8C-2 1.689 399 260.31 510 Cold SG Compartment 75 2-CV-1126-BB1 2-CV-1126-BB1-9 CV -RCP1C 8C-2 1.689 399 260.31 516 Cold SG Compartment 76 2-CV-1126-BB1 2-CV-1126-BB1-10 CV -RCP1C 8C-2 1.689 399 260.31 560.44 Cold SG Compartment 77 2-CV-1126-BB1 2-CV-1126-BB1-11 CV -RCP1C 8C-2 1.689 396 260.31 563.44 Cold SG Compartment 78 2-CV-1128-BB1 2-CV-1128-BB1-1 CV -RCP1D 8C-2 1.689 379.7 -324.25 563.44 Cold SG Compartment 79 2-CV-1128-BB1 2-CV-1128-BBI-2 CV -RCPID 8C-2 1.689 367.7 -324.25 563.44 Cold SG Compartment 80 2-CV-1128-BB1 2-CV-1128-BB1-3 CV -RCP1D 8C-2 1.689 359.7 -324.25 563.44 Cold SG Compartment Page 132 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 81 2-CV-1128-881 2-CV-1128-BB1-3A CV -RCPID 8C-2 1.689 353.7 -324.25 563.44 Cold SIG Compartment 82 2-CV-1128-BB1 2-CV-1128-BB1-3B CV -RCPID 8C-2 1.689 347.7 -324.25 563.44 Cold SG Compartment 83 2-CV-1128-BB1 2-CV-1128-BB1-4 CV -RCPID 8C-2 1.689 344.7 -324.25 563.44 Cold SG Compartment 84 2-CV-1128-BB1 2-CV-1128-BB1-5 CV -RCPID 8C-2 1.689 338.7 -324.25 563.44 Cold SG Compartment 85 2-CV-1128-B81 2-CV-1128-BB1-6 CV -RCP1D 8C-2 1.689 335.7 -324.25 563.44 Cold SG Compartment 86 2-CV-1128-BB1 2-CV-1128-BB1-7 CV -RCP1D 8C-2 1.689 332.7 -321.12 563.44 Cold SG Compartment 87 2-CV-1141-BB1 2-CV-1141-BB1-1 CV -RC Crossover-4 8A 1.689 243 -209.06 372 Cold 51G Compartment 88 2-CV-1141-BB1 2-CV-1141-BB1-2 CV -RC Crossover-4 8A 1.689 255 -186.06 372 Cold SG Compartment 89 2-RC-1003-BB1 2-RC-1003-BB1-1 PZR Auxiliary Spray Line 5J* 1.689 108 -621.5 1062 Cold PZR Compartment 90 2-RC-1003-BB1 2-RC-1003-BB1-2 PZR Auxiliary Spray Line 5J* 1.689 108 -630 1062 Cold PZR Compartment 91 2-RC-1120-BB1 2-RC-1120-BB1-1 RC 7K 1.689 -252 -323 429.14 Cold SG Compartment 92 2-RC-1120-BB1 2-RC-1120-BB1-2 RC 6A-2" 1.689 -252 -323.001 433 Cold SG Compartment 93 2-RC-1121-BB1 2-RC-1121-BB1-1 RC 6A-2" 1.689 -271.125

-306.08 380.001 Cold SG Compartment 94 2-RC-1121-BB1 2-RC-1121-BB1-2 RC 6A-2" 1.689 -228 -293.08 372.001 Cold SIG Compartment 95 2-RC-1121-BB1 2-RC-1121-BB1-3 RC 6A-2" 1.689 -228 -287.187 372.001 Cold SG Compartment 96 2-RC-1121-BB1 2-RC-1121-BB1-3A RC Drain 6A-2 1.689 -228 -283.19 372 Cold SG Compartment 97 2-RC-1121-BB1 2-RC-1121-BB1-3B RC Drain GA-2 1.689 -228 -275.19 372 Cold SG Compartment 98 2-RC-1121-BB1 2-RC-1121-BB1-4 RC 6A-2P 1.689 -228 -269.187 372.001 Cold SG Compartment 99 2-RC-1219-BB1 2-RC-1219-BB1-1 RC 7K 1.689 -249.25 325.43 429.08 Cold SG Compartment 100 2-RC-1219-BB1 2-RC-1219-BB1-2 RC 6A-2" 1.689 -249.25 325.434 433 Cold SG Compartment 101 2-RC-1220-BB1 2-RC-1220-BB1-1 RC 6A-2" 1.689 -271.146 306.062 379.001 Cold 515 Compartment 102 2-RC-1220-BB1 2-RC-1220-BB1-2 RC 6A-2" 1.689 -228 293 369.751 Cold SG Compartment 103 2-RC-1220-8B1 2-RC-1220-BB1-3 RC 6A-2" 1.689 -228 284.5 369.751 Cold SG Compartment 104 2-RC-1220-BB1 2-RC-1220-BB1-4 RC 6A-2" 1.689 -228 275.5 369.751 Cold SG Compartment 105 2-RC-1319-BB1 2-RC-1319-BB1-1 RC 7K 1.689 272.81 325.82 427.58 Cold SG Compartment 106 2-RC-1319-BB1 2-RC-1319-BB1-2 RC 6A-2P 1.689 272.812 325.821 433 Cold SG Compartment 107 2-RC-1321-BB1 2-RC-1321-BB1-1 RC 6A-2" 1.689 244.134 288.072 372.313 Cold 513 Compartment 108 2-RC-1321-BB1 2-RC-1321-BB1-4 RC 6A-2P 1.689 256.509 276.822 372.313 Cold SG Compartment 109 2-RC-1321-BB1 2-RC-1321-BB1-5 RC 6A-2" 1.689 256.509 268.322 372.313 Cold SG Compartment 110 2-RC-1321-BB1 2-RC-1321-BB1-6 RC 6A-2" 1.689 256.509 259.322 372.313 Cold SG Compartment 111 2-RC-1417-BB1 2-RC-1417-BB1-1 RC 7K 1.689 273.37 -325.32 429.33 Cold SG Compartment 112 2-RC-1417-B81 2-RC-1417-BB1-2 RC 6A-2" 1.689 273.375 -325.323 433 Cold SG Compartment 113 2-RC-1418-BB1 2-RC-1418-BB1-1 RC 6A-2P 1.689 295.146 -306.062 379.293 Cold SG Compartment 114 2-RC-1418-B81 2-RC-1418-BB1-2 CV -RC Crossover-4 8A 1.689 262.02 -306.06 372 Cold SG Compartment 115 2-RC-1418-BB1 2-RC-1418-BB1-3 CV -RC Crossover-4 8A 1.689 258.02 -302.06 372 Cold SG Compartment 116 2-RC-1418-BB1 2-RC-1418-BB1-4 RC 6A-2P 1.689 258.021 -294.812 372 Cold SG Compartment 117 2-RC-1418-BB1 2-RC-1418-BB1-5 RC 6A-2P 1.689 258.021 -284.812 372 Cold SG Compartment 118 2-RC-1418-8B1 2-RC-1418-BB1-6 RC 6A-2P 1.689 258.021 -271.312 372 Cold SG Compartment 119 2-RC-1419-BB1 2-RC-1419-B81-1 CV -RC Crossover-4 8A 1.689 254.02 -306.06 372 Cold SG Compartment 120 2-RC-1419-BB1 2-RC-1419-BB1-2 CV -RC Crossover-4 8A 1.689 243 -294.81 372 Cold SG Compartment 121 2-RC-1419-BB1 2-RC-1419-BB1-3 CV -RC Crossover-4 8A 1.689 243 -284.81 372 Cold SG Compartment Page 133 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 122 2-RC-1419-BB1 2-RC-1419-BB1-4 RC 6A-2* 1.689 243 -218.312 372 Cold SG Compartment 123 2.5-RC-1003-BB1 2.5-RC-1003-881-1 Pressurizer Surge Line 4D 2.125 46.2 -643.8 1266 Cold PZR Compartment 124 2.5-RC-1003-BB1 2.5-RC-1003-BB1-2 Pressurizer Surge Line 4D 2.125 46.2 -643.8 1272.31 Cold PZR Compartment 125 2.5-RC-1003-BB1 2.5-RC-1003-B81-3 Pressurizer Surge Line 4D 2.125 44.08 -645.92 1275.31 Cold PZR Compartment 126 2.5-RC-1003-BB1 2.5-RC-1003-BB1-4 Pressurizer Surge Line 4D 2.125 41.25 -648.75 1275.31 Cold PZR Compartment 127 2.5-RC-1003-BB1 2.5-RC-1003-B81-5 Pressurizer Surge Line 4D 2.125 32.19 -657.81 1275.31 Cold PZR Compartment 128 2.5-RC-1003-BB1 2.5-RC-1003-B81-6 Pressurizer Surge Line 4D 2.125 30.07 -659.93 1275.31 Cold PZR Compartment 129 3-RC-1003-BB1 3-RC-1003-BB1-1 PZR Auxiliary Spray Line 5B 2.626 108 -636 1062 Cold PZR Compartment 130 3-RC-1003-BB1 3-RC-1003-BB1-2 PZR Auxiliary Spray Line SB 2.626 108 -645 1062 Cold PZR Compartment 131 3-RC-1015-NSS 3-RC-1015-NSS-1 Pressurizer PORV Line 5D 2.626 -44.11 -652.56 1262.06 Cold PZR Compartment 132 3-RC-1015-NSS 3-RC-1015-NSS-2 Pressurizer PORV Line 5D 2.626 -46.2 -655.24 1260.66 Cold PZR Compartment 133 3-RC-1015-NSS 3-RC-1015-NSS-3 Pressurizer PORV Line 5B 2.626 -48.29 -657.91 1259.25 Cold PZR Compartment 134 3-RC-1015-NSS 3-RC-1015-NSS-4 Pressurizer PORV Line 5B 2.626 -54.45 -665.79 1259.25 Cold PZR Compartment 135 3-RC-1015-NSS 3-RC-1015-NSS-5 Pressurizer PORV Line 5B 2.626 -59.99 -672.89 1259.25 Cold PZR Compartment 136 3-RC-1015-NSS 3-RC-1015-NSS-6 Pressurizer PORV Line 5B 2.626 -69.2 -684.67 1259.25 Cold PZR Compartment 137 3-RC-1015-NSS 3-RC-1015-NSS-7 Pressurizer PORV Line 5B 2.626 -68.43 -691.14 1259.25 Cold PZR Compartment 138 3-RC-1015-NSS 3-RC-1015-NSS-8 Pressurizer PORV Line 5B 2.626 -48.48 -706.73 1259.25 Cold PZR Compartment 139 3-RC-1015-NSS 3-RC-1015-NSS-9 Pressurizer PORV Line 5D 2.626 -26.26 -629.71 1262.06 Cold PZR Compartment 140 3-RC-1015-NSS 3-RC-1015-NSS-10 Pressurizer PORV Line 5D 2.626 -24.16 -627.04 1260.66 Cold PZR Compartment 141 3-RC-1015-NSS 3-RC-1015-NSS-11 Pressurizer PORV Line 5B 2.626 -22.08 -624.36 1259.25 Cold PZR Compartment 142 3-RC-1015-NSS 3-RC-1015-NSS-12 Pressurizer PORV Line SB 2.626 -15.92 -616.48 1259.25 Cold PZR Compartment 143 3-RC-1015-NSS 3-RC-1015-NSS-13 Pressurizer PORV Line 5B 2.626 -10.38 -609.39 1259.25 Cold PZR Compartment 144 3-RC-1015-NSS 3-RC-1015-NSS-14 Pressurizer PORV Line 58 2.626 -1.17 -597.6 1259.25 Cold PZR Compartment 145 3-RC-1015-NSS 3-RC-1015-NSS-15 Pressurizer PORV Line 58 2.626 5.33 -596.8 1259.25 Cold PZR Compartment 146 3-RC-1015-NSS 3-RC-1015-NSS-16 Pressurizer PORV Line 58 2.626 25.24 -612.36 1259.25 Cold PZR Compartment 147 3-RC-1106-BB1 3-RC-1106-BB1-25 SI -Capped 7J 2.626 -278.44 -299.61 430.31 Cold SG Compartment 148 3-RC-1206-BB1 3-RC-1206-BB1-28 SI -Capped 7J 2.626 -278.44 299.61 430.31 Cold SG Compartment 149 3-RC-1306-BB1 3-RC-1306-BB1-28 SI -Capped 7J 2.626 302.44 299.61 430.31 Cold SG Compartment 150 3-RC-1406-BB1 3-RC-1406-BB1-25 SI -Capped 7J 2.626 302.44 -299.61 430.31 Cold SG Compartment 151 4-CV-1001-BB1 4-CV-1001-BB1-1 CV -RC Crossover-3 88 3.438 204.13 243.01 372.31 Cold SG Compartment 152 4-CV-1001-BB1 4-CV-1001-BB1-2 CV -RC Crossover-3 88 3.438 182.13 243.01 372.31 Cold SG Compartment 153 4-CV-1118-BB1 4-CV-1118-BB1-1 CV -RC Coldleg 1 8B 3.438 -328 -91.56 507 Cold SG Compartment 154 4-CV-1118-BB1 4-CV-1118-BB1-2 CV -RC Coldleg 1 8B 3.438 -269 -91.56 507 Cold SG Compartment 155 4-CV-1120-BB1 4-CV-1120-BB1-1 CV -RC Coldleg 3 8B 3.438 181.59 196.84 522 Cold SG Compartment 156 4-CV-1120-BB1 4-CV-1120-BB1-2 CV -RC Coldleg 3 86 3.438 190.07 205.33 522 Cold SG Compartment 157 4-RC-1000-BB1 4-RC-1000-BBI-1 Pressurizer Spray 5C 3.438 82.44 -594.19 984 Cold PZR Compartment 158 4-RC-1000-BB1 4-RC-1000-BB1-2 Pressurizer Spray 5C 3.438 91.81 -594.19 984 Cold PZR Compartment 159 4-RC-1000-BB1 4-RC-1000-BB1-3 Pressurizer Spray 5C 3.438 97.81 -594.19 990 Cold PZR Compartment 160 4-RC-1000-BB1 4-RC-1000-BB1-4 Pressurizer Spray 5C 3.438 97.81 -594.19 1023 Cold PZR Compartment 161 4-RC-1000-BB1 4-RC-1000-BB1-5 Pressurizer Spray 5C 3.438 100.64 -597.02 1029 Cold PZR Compartment 162 4-RC-1000-BB1 4-RC-1000-BB1-6 Pressurizer Spray 5C 3.438 105.17 -601.55 1029 Cold PZR Compartment Page 134 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 163 4-RC-1000-BB1 4-RC-1000-BB1-7 Pressurizer Spray 5C 3.438 108 -608.38 1029 Cold PZR Compartment 164 4-RC-1000-BB1 4-RC-1000-BB1-8 Pressurizer Spray 5C 3.438 108 -636 1029 Cold PZR Compartment 165 4-RC-1003-BB1 4-RC-1003-BB1-1 Pressurizer Spray 5C 3.438 108 -635 984 Cold PZR Compartment 166 4-RC-1003-BB1 4-RC-1003-B81-2 Pressurizer Spray 5C 3.438 108 -642 984 Cold PZR Compartment 167 4-RC-1003-BB1 4-RC-1003-1B1-3 Pressurizer Spray 5C 3.438 108 -648 990 Cold PZR Compartment 168 4-RC-1003-BB1 4-RC-1003-BB1-4 Pressurizer Spray 5C 3.438 108 -648 1008 Cold PZR Compartment 169 4-RC-1123-BB1 4-RC-1123-BB1-1 Pressurizer Spray 51* 3.438 -252.54 -190.08 545.88 Cold SG Compartment 170 4-RC-1123-BB1 4-RC-1123-BB1-2 Pressurizer Spray 5C 3.438 -252.54 -190.08 708 Cold SG Compartment 171 4-RC-1123-BB1 4-RC-1123-BB1-3 Pressurizer Spray 5C 3.438 -252.54 -190.08 723 Cold SG Compartment 172 4-RC-1123-BB1 4-RC-1123-BB1-4 Pressurizer Spray 5C 3.438 -244.06 -198.57 735 Cold SG Compartment 173 4-RC-1123-BB1 4-RC-1123-BB1-5 Pressurizer Spray 5C 3.438 -211.95 -230.67 735 Cold SG Compartment 174 4-RC-1123-BB1 4-RC-1123-BB1-6 Pressurizer Spray 5C 3.438 -203.47 -234.19 735 Cold SG Compartment 175 4-RC-1123-BB1 4-RC-1123-BB1-7 Pressurizer Spray 5C 3.438 -30.19 -234.19 735 Cold SG Compartment 176 4-RC-1123-BB1 4-RC-1123-BB1-8 Pressurizer Spray 5C 3.438 -18.19 -246.27 735 Cold SG Compartment 177 4-RC-1123-BB1 4-RC-1123-BB1-9 Pressurizer Spray 5C 3.438 -18.19 -372.19 735 Cold SG Compartment 178 4-RC-1123-BB1 4-RC-1123-BB1-10 Pressurizer Spray 5C 3.438 -18.19 -504.19 735 Cold SG Compartment 179 4-RC-1123-BB1 4-RC-1123-1B1-11 Pressurizer Spray 5C 3.438 -18.19 -516.19 747 Cold SG Compartment 180 4-RC-1123-BB1 4-RC-1123-BB1-12 Pressurizer Spray 5C 3.438 -18.19 -516.19 879 Cold SG Compartment 181 4-RC-1123-BB1 4-RC-1123-BB1-13 Pressurizer Spray 5C 3.438 -6.19 -516.19 891 Cold SG Compartment 182 4-RC-1123-BB1 4-RC-1123-BB1-14 Pressurizer Spray 5C 3.438 38.99 -516.19 891 Cold SG Compartment 183 4-RC-1123-BB1 4-RC-1123-BB1-15 Pressurizer Spray 5C 3.438 50.81 -528.19 891 Cold SG Compartment 184 4-RC-1123-BB1 4-RC-1123-BB1-16 Pressurizer Spray 5C 3.438 50.81 -588.19 891 Cold PZR Compartment 185 4-RC-1123-BB1 4-RC-1123-BB1-17 Pressurizer Spray 5C 3.438 50.81 -594.19 897 Cold PZR Compartment 186 4-RC-1123-BB1 4-RC-1123-BB1-18 Pressurizer Spray 5C 3.438 50.81 -594.19 978 Cold PZR Compartment 187 4-RC-1123-BB1 4-RC-1123-BB1-19 Pressurizer Spray 5C 3.438 56.81 -594.19 984 Cold PZR Compartment 188 4-RC-1123-BB1 4-RC-1123-BB1-20 Pressurizer Spray 5C 3.438 75.62 -594.19 984 Cold PZR Compartment 189 4-RC-1126-BB1 4-RC-1126-BB1-1 CV -RC Coldleg 1 8B 3.438 -255 -91.56 507 Cold SG Compartment 190 4-RC-1126-BB1 4-RC-1126-BB1-2 CV -RC Coldleg 1 8B 3.438 -228 -91.56 507 Cold SG Compartment 191 4-RC-1126-BB1 4-RC-1126-BB1-3 CV -RC Coldleg 1 8B 3.438 -222 -91.56 513 Cold SG Compartment 192 4-RC-1126-BB1 4-RC-1126-881-4 CV -RC Coldleg 1 8B 3.438 -222 -91.56 516 Cold SG Compartment 193 4-RC-1126-BB1 4-RC-1126-B81-5 CV -RC Coldleg 1 8B 3.438 -217.76 -95.8 522 Cold SG Compartment 194 4-RC-1126-BB1 4-RC-1126-BB1-6 CV -RC Coldleg 1 8E 3.438 -205.01 -108.55 522 Cold SG Compartment 195 4-RC-1320-BB1 4-RC-1320-BB1-1 CV -RC Crossover-3 8F 3.438 295.13 306.07 381.31 Cold SG Compartment 196 4-RC-1320-BB1 4-RC-1320-BB1-2 CV -RC Crossover-3 8D 3.438 295.13 306.07 377.31 Cold SG Compartment 197 4-RC-1320-BB1 4-RC-1320-BB1-3 CV -RC Crossover-3 8D 3.438 290.13 306.07 372.31 Cold SG Compartment 198 4-RC-1320-BB1 4-RC-1320-BB1-4 CV -RC Crossover-3 8D 3.438 246.13 306.07 372.31 Cold SG Compartment 199 4-RC-1320-BB1 4-RC-1320-BB1-5 CV -RC Crossover-3 8D 3.438 241.13 301.07 372.31 Cold SG Compartment 200 4-RC-1320-BB1 4-RC-1320-BB1-6 CV -RC Crossover-3 8D 3.438 241.13 291.07 372.31 Cold SG Compartment 201 4-RC-1320-BB1 4-RC-1320-BB1-7 CV -RC Crossover-3 8D 3.438 241.13 285.07 372.31 Cold SG Compartment 202 4-RC-1320-BB1 4-RC-1320-B81-8 CV -RC Crossover-3 88 3.438 241.13 274.01 372.31 Cold SG Compartment 203 4-RC-1320-BB1 4-RC-1320-BB1-9 CV -RC Crossover-3 8B 3.438 241.13 258.01 372.31 Cold SG Compartment Page 135 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 204 4-RC-1320-BB1 4-RC-1320-8B1-10 CV -RC Crossover-3 88 3.438 241.13 248.01 372.31 Cold SG Compartment 205 4-RC-1320-BB1 4-RC-1320-BB1-11 CV -RC Crossover-3 8B 3.438 236.13 243.01 372.31 Cold SG Compartment 206 4-RC-1320-BB1 4-RC-1320-8B1-12 CV -RC Crossover-3 88 3.438 220.13 243.01 372.31 Cold SG Compartment 207 4-RC-1323-BB1 4-RC-1323-BB1-1 CV -RC Coldleg 3 8B 3.438 171.7 186.93 522 Cold SG Compartment 208 4-RC-1323-BB1 4-RC-1323-B81-2 CV -RC Coldleg 3 8B 3.438 164.64 179.85 522 Cold SG Compartment 209 4-RC-1323-BB1 4-RC-1323-BB1-3 CV -RC Coldleg 3 86 3.438 164.65 172.78 522 Cold SG Compartment 210 4-RC-1323-BB1 4-RC-1323-BB1-4 CV -RC Coldleg 3 8E 3.438 195.67 141.82 522 Cold SG Compartment 211 4-RC-1420-BB1 4-RC-1420-BB1-1 SI 71 3.438 273.56 -187.1 548 Cold SG Compartment 212 4-RC-1422-BB1 4-RC-1422-BB1-1 Pressurizer Spray 51* 3.438 252.15 -188.74 538.31 Cold SG Compartment 213 4-RC-1422-BB1 4-RC-1422-BB1-2 Pressurizer Spray 5C 3.438 249 -191.89 542.76 Cold SG Compartment 214 4-RC-1422-BB1 4-RC-1422-BB1-3 Pressurizer Spray 5C 3.438 250.24 -199.13 547 Cold SG Compartment 215 4-RC-1422-BB1 4-RC-1422-BB1-4 Pressurizer Spray 5C 3.438 259.44 -208.33 547 Cold SG Compartment 216 4-RC-1422-BB1 4-RC-1422-BB1-5 Pressurizer Spray 5C 3.438 263.68 -212.57 553 Cold SG Compartment 217 4-RC-1422-BB1 4-RC-1422-BB1-6 Pressurizer Spray 5C 3.438 263.68 -212.57 729 Cold SG Compartment 218 4-RC-1422-BB1 4-RC-1422-BB1-7 Pressurizer Spray 5C 3.438 263.68 -218.57 735 Cold SG Compartment 219 4-RC-1422-BB1 4-RC-1422-BB1-8 Pressurizer Spray 5C 3.438 263.68 -228 735 Cold SG Compartment 220 4-RC-1422-BB1 4-RC-1422-BB1-9 Pressurizer Spray 5C 3.438 257.68 -234 735 Cold SG Compartment 221 4-RC-1422-BB1 4-RC-1422-BB1-10 Pressurizer Spray 5C 3.438 57 -234 735 Cold SG Compartment 222 4-RC-1422-BB1 4-RC-1422-1B1-11 Pressurizer Spray 5C 3.438 45 -246 735 Cold SG Compartment 223 4-RC-1422-BB1 4-RC-1422-BB1-12 Pressurizer Spray 5C 3.438 45 -384 735 Cold SG Compartment 224 4-RC-1422-BB1 4-RC-1422-BB1-13 Pressurizer Spray 5C 3.438 45 -504.07 735 Cold SG Compartment 225 4-RC-1422-BB1 4-RC-1422-BB1-14 Pressurizer Spray 5C 3.438 57 -516 735 Cold SG Compartment 226 4-RC-1422-BB1 4-RC-1422-B81-15 Pressurizer Spray 5C 3.438 96.03 -516 735 Cold SG Compartment 227 4-RC-1422-BB1 4-RC-1422-BB1-16 Pressurizer Spray 5C 3.438 108 -516 747 Cold SG Compartment 228 4-RC-1422-BB1 4-RC-1422-BB1-17 Pressurizer Spray 5C 3.438 108 -516 879 Cold SG Compartment 229 4-RC-1422-BB1 4-RC-1422-B81-18 Pressurizer Spray 5C 3.438 108 -528 891 Cold SG Compartment 230 4-RC-1422-BB1 4-RC-1422-BB1-19 Pressurizer Spray 5C 3.438 108 -582 891 Cold SG Compartment 231 4-RC-1422-BB1 4-RC-1422-BB1-20 Pressurizer Spray 5C 3.438 108 -594 903 Cold PZR Compartment 232 4-RC-1422-BB1 4-RC-1422-B81-21 Pressurizer Spray 5C 3.438 108 -594 972 Cold PZR Compartment 233 4-RC-1422-BB1 4-RC-1422-B81-22 Pressurizer Spray 5C 3.438 108 -606 984 Cold PZR Compartment 234 4-RC-1422-BB1 4-RC-1422-B81-23 Pressurizer Spray 5C 3.438 108 -621.38 984 Cold PZR Compartment 235 6-RC-1003-BB1 6-RC-1003-BB1-1 Pressurizer Spray 5E 5.189 108 -648 1017 Cold PZR Compartment 236 6-RC-1003-BB1 6-RC-1003-BB1-2 Pressurizer Spray 5E 5.189 108 -648 1025 Cold PZR Compartment 237 6-RC-1003-BB1 6-RC-1003-BB1-3 Pressurizer Spray 5E 5.189 108 -648 1033 Cold PZR Compartment 238 6-RC-1003-BB1 6-RC-1003-BB1-4 Pressurizer Spray 5A 5.189 108 -648 1058 Cold PZR Compartment 239 6-RC-1003-BB1 6-RC-1003-BB1-5 Pressurizer Spray 5A 5.189 108 -648 1066 Cold PZR Compartment 240 6-RC-1003-BB1 6-RC-1003-BB1-6 Pressurizer Spray 5A 5.189 108 -648 1083 Cold PZR Compartment 241 6-RC-1003-BB1 6-RC-1003-BB1-7 Pressurizer Spray 5A 5.189 97.58 -642.05 1095 Cold PZR Compartment 242 6-RC-1003-BB1 6-RC-1003-BB1-8 Pressurizer Spray 5A 5.189 76.42 -629.95 1095 Cold PZR Compartment 243 6-RC-1003-BB1 6-RC-1003-BB1-9 Pressurizer Spray 5A 5.189 66 -624 1107 Cold PZR Compartment 244 6-RC-1003-BB1 6-RC-1003-BB1-9A Pressurizer Spray 5A 5.189 66 -624 1128 Cold PZR Compartment Page 136 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 245 6-RC-1003-BB1 6-RC-1003-B81-9B Pressurizer Spray 5A 5.189 66 -624 1149 Cold PZR Compartment 246 6-RC-1003-BB1 6-RC-1003-BB1-10 Pressurizer Spray 5A 5.189 66 -624 1251 Cold PZR Compartment 247 6-RC-1003-BB1 6-RC-1003-BB1-11 Pressurizer Spray 5A 5.189 57.51 -632.49 1263 Cold PZR Compartment 248 6-RC-1003-BB1 6-RC-1003-BB1-11A Pressurizer Spray 5A 5.189 49.03 -640.97 1263 Cold PZR Compartment 249 6-RC-1003-BB1 6-RC-1003-BB1-11B Pressurizer Spray 5A 5.189 43.37 -646.63 1263 Cold PZR Compartment 250 6-RC-1003-BB1 6-RC-1003-BB1-12 Pressurizer Spray 5A 5.189 20.49 -669.51 1263 Cold PZR Compartment 251 6-RC-1003-BB1 6-RC-1003-BB1-13 Pressurizer spray 5A 5.189 12 -678 1251 Cold PZR Compartment 252 6-RC-1003-BB1 6-RC-1003-BB1-13A Pressurizer Spray 5A 5.189 12 -678 1236.5 Cold PZR Compartment 253 6-RC-1003-BB1 6-RC-1003-BB1-14 Pressurizer Spray 5H* 5.189 12 -678 1222 Cold PZR Compartment 254 6-RC-1003-BB1 6-RC-1003-BB1-PRZ-1-N2-SE Pressurizer Spray 5F 5.189 12 -678 1222.5 Cold PZR Compartment 255 6-RC-1004-NSS 6-RC-1004-NSS-1 Pressurizer 5RV Line 5H* 5.189 5.95 -721.01 1202.7 Cold PZR Compartment 256 6-RC-1004-NSS 6-RC-1004-NSS-2 Pressurizer SRV Line 5E 5.189 5.59 -723.61 1208.62 Cold PZR Compartment 257 6-RC-1004-NSS 6-RC-1004-NSS-3 Pressurizer 5RV Line 5E 5.189 5.59 -723.61 1227.28 Cold PZR Compartment 258 6-RC-1004-NSS 6-RC-1004-NSS-4 Pressurizer SRV Line 5E 5.189 20.1 -711 1227.27 Cold PZR Compartment 259 6-RC-1004-NSS 6-RC-1004-NSS-5 Pressurizer SRV Line 5A 5.189 20.1 -711 1222.1 Cold PZR Compartment 260 6-RC-1004-NSS 6-RC-1004-NSS-6 Pressurizer SRV Line 5A 5.189 23.31 -729.95 1222.1 Cold PZR Compartment 261 6-RC-1004-NSS 6-RC-1004-NSS-7 Pressurizer SRV Line 5A 5.189 23.31 -729.95 1232.5 Cold PZR Compartment 262 6-RC-1004-NSS 6-RC-1004-NSS-PRZ-1-N3-SE Pressurizer SRV Line 5F 5.189 5.95 -721.01 1202.7 Cold PZR Compartment 263 6-RC-1009-NSS 6-RC-1009-NSS-1 Pressurizer SRV Line 5H* 5.189 49.17 -702.14 1206.45 Cold PZR Compartment 264 6-RC-1009-NSS 6-RC-1009-NSS-2 Pressurizer SRV Line 5E 5.189 51.2 -703.46 1212.19 Cold PZR Compartment 265 6-RC-1009-NSS 6-RC-1009-NSS-3 Pressurizer 5RV Line 5E 5.189 51.2 -703.46 1232.45 Cold PZR Compartment 266 6-RC-1009-NSS 6-RC-1009-NSS-4 Pressurizer SRV Line 5E 5.189 48.64 -686.29 1232.47 Cold PZR Compartment 267 6-RC-1009-NSS 6-RC-1009-NSS-5 Pressurizer SRV Line 5A 5.189 48.64 -686.29 1220.3 Cold PZR Compartment 268 6-RC-1009-NSS 6-RC-1009-NSS-6 Pressurizer SRV Line 5A 5.189 53.56 -679.99 1212.3 Cold PZR Compartment 269 6-RC-1009-NSS 6-RC-1009-NSS-7 Pressurizer SRV Line 5A 5.189 59.03 -672.99 1212.3 Cold PZR Compartment 270 6-RC-1009-NSS 6-RC-1009-NSS-8 Pressurizer SRV Line 5A 5.189 63.95 -666.69 1220.3 Cold PZR Compartment 271 6-RC-1009-NSS 6-RC-1009-NSS-9 Pressurizer SRV Line 5A 5.189 63.95 -666.69 1232.3 Cold PZR Compartment 272 6-RC-1009-NSS 6-RC-1009-NSS-PRZ-1-N4C-SE Pressurizer SRV Line 5F 5.189 49.32 -702.24 1206.63 Cold PZR Compartment 273 6-RC-1012-NSS 6-RC-1012-NSS-1 Pressurizer SRV Line 5H* 5.189 49.79 -654.39 1205.31 Cold PZR Compartment 274 6-RC-1012-NSS 6-RC-1012-NSS-2 Pressurizer SRV Line 5E 5.189 51.78 -653.15 1210.97 Cold PZR Compartment 275 6-RC-1012-NSS 6-RC-1012-NSS-3 Pressurizer SRV Line 5E 5.189 51.78 -653.15 1216.43 Cold PZR Compartment 276 6-RC-1012-NSS 6-RC-1012-NSS-4 Pressurizer SRV Line 5E 5.189 47.03 -652.31 1223.77 Cold PZR Compartment 277 6-RC-1012-NSS 6-RC-1012-NSS-5 Pressurizer SRV Line 5E 5.189 8.75 -645.56 1240.59 Cold PZR Compartment 278 6-RC-1012-NSS 6-RC-1012-NSS-6 Pressurizer SRV Line 5E 5.189 5.62 -645.01 1241.25 Cold PZR Compartment 279 6-RC-1012-NSS 6-RC-1012-NSS-7 Pressurizer SRV Line 5A 5.189 -2.85 -643.51 1241.25 Cold PZR Compartment 280 6-RC-1012-NSS 6-RC-1012-NSS-8 Pressurizer SRV Line 5A 5.189 -10.72 -642.13 1233.25 Cold PZR Compartment 281 6-RC-1012-NSS 6-RC-1012-NSS-9 Pressurizer SRV Line 5A 5.189 -10.72 -642.13 1222.53 Cold PZR Compartment 282 6-RC-1012-NSS 6-RC-1012-NSS-10 Pressurizer SRV Line 5A 5.189 0.69 -626.05 1222.52 Cold PZR Compartment 283 6-RC-1012-NSS 6-RC-1012-NSS-11 Pressurizer SRV Line 5A 5.189 0.69 -626.05 1225.38 Cold PZR Compartment 284 6-RC-1012-NSS 6-RC-1012-NSS-PRZ-1-N4B-SE Pressurizer SRV Line 5F 5.189 49.64 -654.48 1205.13 Cold PZR Compartment 285 6-RC-1015-NSS 6-RC-1015-NSS-1 Pressurizer PORV Line 5E 5.189 5.6 -635.02 1202.71 Cold PZR Compartment Page 137 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 286 6-RC-1015-NSS 6-RC-1015-NSS-2 Pressurizer PORV Line 5E 5.189 5.23 -632.42 1208.64 Cold PZR Compartment 287 6-RC-1015-NSS 6-RC-1015-NSS-3 Pressurizer PORV Line 5E 5.189 5.23 -632.42 1217.93 Cold PZR Compartment 288 6-RC-1015-NSS 6-RC-1015-NSS-4 Pressurizer PORV Line 5E 5.189 6.35 -640.34 1225.93 Cold PZR Compartment 289 6-RC-1015-NSS 6-RC-1015-NSS-5 Pressurizer PORV Line 5E 5.189 7.58 -649.1 1225.93 Cold PZR Compartment 290 6-RC-101S-NSS 6-RC-1015-NSS-6 Pressurizer PORV Line 5E 5.189 5.96 -655.14 1225.93 Cold PZR Compartment 291 6-RC-1015-NSS 6-RC-101S-NSS-7 Pressurizer PORV Line 5E 5.189 2.1 -660.08 1225.93 Cold PZR Compartment 292 6-RC-1015-NSS 6-RC-1015-NSS-8 Pressurizer PORV Line 5E 5.189 -2.84 -666.4 1233.93 Cold PZR Compartment 293 6-RC-1015-NSS 6-RC-1015-NSS-9 Pressurizer PORV Line 5E 5.189 -2.84 -666.4 1240.98 Cold PZR Compartment 294 6-RC-1015-NSS 6-RC-101S-NS5-10 Pressurizer PORV Line 5E 5.189 -6.91 -663.22 1248.46 Cold PZR Compartment 295 6-RC-1015-NSS 6-RC-1015-NSS-11 Pressurizer PORV Line 5E 5.189 -30.76 -644.59 1259.94 Cold PZR Compartment 296 6-RC-1015-NSS 6-RC-101S-NSS-12 Pressurizer PORV Line 5E 5.189 -38.88 -645.87 1262.06 Cold PZR Compartment 297 6-RC-1015-NSS 6-RC-1015-NSS-13 Pressurizer PORV Line 5E 5.189 -40.72 -648.23 1262.06 Cold PZR Compartment 298 6-RC-1015-NSS 6-RC-1015-NSS-14 Pressurizer PORV Line 5E 5.189 -31.49 -636.41 1262.06 Cold PZR Compartment 299 6-RC-1015-NSS 6-RC-101S-NSS-15 Pressurizer PORV Line 5E 5.189 -29.64 -634.05 1262.06 Cold PZR Compartment 300 6-SI-1108-BB1 6-S1-1108-BB1-1 SI 7H 5.189 -394.51 -458.32 483 Hot Annulus301 6-SI-1108-BB1 6-SI-1108-BB1-2 SI 7H 5.189 -390.98 -461.85 483 Hot Annulus302 6-SI-1108-BB1 6-SI-1108-BB1-3 SI 7H 5.189 -376.83 -461.85 483 Hot Annulus303 6-S1-1108-BB1 6-51-1108-BB1-4 SI 7H 5.189 -337.24 -422.26 483 Hot SG Compartment 304 6-51-1111-BB1 6-S1-1111-BB1-1 SI 7H 5.189 -401.01 -237.72 231.01 Cold Below SG Compartment 305 6-SI-1111-BB1 6-S1-1111-BB1-2 SI 7H 5.189 -401.01 -230.38 231.01 Cold Below SG Compartment 306 6-Sl-1208-BB1 6-S1-1208-BB1-1 SI 7H 5.189 -374.64 478.19 483 Hot Annulus307 6-SI-1208-BB1 6-SI-1208-BB1-2 SI 7H 5.189 -378.18 474.65 483 Hot Annulus308 6-S1-1208-BB1 6-SI-1208-B81-3 SI 7H 5.189 -378.18 460.51 483 Hot Annulus309 6-SI-1208-BB1 6-S1-1208-B81-4 SI 7H 5.189 -338.58 420.91 483 Hot SG Compartment 310 6-51-1211-B81 6-S1-1211-BB1-1 SI 7H 5.189 -392.04 236.38 231.01 Cold Below SG Compartment 311 6-S1-1211-BB1 6-SI-1211-BB1-2 SI 7H 5.189 -392.04 229.38 231.01 Cold Below SG Compartment 312 6-SI-1308-BB1 6-S1-1308-881-1 RH 7H 5.189 514 146.37 230.92 Cold RHR Compartment 313 6-SI-1308-B81 6-SI-1308-BB1-2 RH 7H 5.189 454.5 146.37 230.92 Cold Below SG Compartment 314 6-S1-1308-BB1 6-SI-1308-BB1-3 RH 7H 5.189 446.5 154.37 230.92 Cold Below SG Compartment 315 6-S1-1308-881 6-SI-1308-BB1-4 RH 7H 5.189 446.5 164.37 230.92 Cold Below SG Compartment 316 6-SI-1327-BB1 6-S1-1327-BB1-1 SI 7H 5.189 407.93 305.38 491.92 Hot SG Compartment 317 6-SI-1327-BB1 6-SI-1327-BB1-2 SI 7H 5.189 407.9 315.13 491.92 Hot SG Compartment 318 6-SI-1327-BB1 6-S1-1327-BB1-3 SI 7H 5.189 404.5 323.62 491.92 Hot SG Compartment 319 6-SI-1327-BB1 6-S1-1327-BB1-4 SI 7H 5.189 371.97 356.14 491.92 Hot SG Compartment 320 6-SI-1327-BB1 6-SI-1327-BB1-5 SI 7H 5.189 357.12 370.99 491.92 Hot SG Compartment 321 6-S1-1327-BB1 6-51-1327-B81-6 SI 7H 5.189 357.12 379.48 491.92 Hot SG Compartment 322 6-SI-1327-BB1 6-SI-1327-B81-7 Sl 7H 5.189 363.49 385.84 491.92 Hot SG Compartment 323 8-RC-1114-BB1 8-RC-1114-BB1-1 SI 78 6.813 -148.4 -233.45 483 Hot SG Compartment 324 8-RC-1114-BB1 8-RC-1114-BB1-2 SI 7B 6.813 -134.97 -220.01 483 Hot SG Compartment 325 8-RC-1114-BB1 8-RC-1114-BB1-3 SI 78 6.813 -126.48 -211.52 495 Hot SG Compartment 326 8-RC-1114-BB1 8-RC-1114-BB1-4 SI 7G 6.813 -126.48 -211.52 510 Hot SG Compartment Page 138 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1291-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 327 8-RC-1114-BB1 8-RC-1114-BB1-5 51 7G 6.813 -115.35 -216.02 522 Hot SG Compartment 328 8-RC-1114-BB1 8-RC-1114-BB1-6 SI 7G 6.813 -107.94 -219.02 522 Hot SG Compartment 329 8-RC-1214-BB1 8-RC-1214-BBl-1 51 7B 6.813 -149.63 231.95 483 Hot SG Compartment 330 8-RC-1214-BB1 8-RC-1214-BB1-2 SI 7B 6.813 -136.91 219.23 483 Hot SG Compartment 331 8-RC-1214-BB1 8-RC-1214-BB1-3 SI 7B 6.813 -128.42 210.74 495 Hot SG Compartment 332 8-RC-1214-BB1 8-RC-1214-BB1-4 SI 7G 6.813 -128.42 210.74 510 Hot SG Compartment 333 8-RC-1214-BB1 8-RC-1214-BBl-5 SI 7G 6.813 -117.29 215.24 522 Hot SG Compartment 334 8-RC-1214-BB1 8-RC-1214-BB1-6 SI 7G 6.813 -109.12 218.54 522 Hot SG Compartment 335 8-RC-1324-BB1 8-RC-1324-BB1-1 S5 7B 6.813 169.39 227.71 492 Hot SG Compartment 336 8-RC-1324-BB1 8-RC-1324-BB1-2 SI 7B 6.813 160.91 219.23 492 Hot SG Compartment 337 8-RC-1324-BB1 8-RC-1324-BB1-3 51 78 6.813 152.42 210.74 504 Hot SH Compartment 338 8-RC-1324-BB1 8-RC-1324-BB1-4 SI 76 6.813 152.42 210.74 510 Hot SG Compartment 339 8-RC-1324-BB1 8-RC-1324-BB1-5 SI 7G 6.813 141.31 215.23 522 Hot SG Compartment 340 8-RC-1324-BB1 8-RC-1324-BB1-6 SI 7G 6.813 133.12 218.54 522 Hot SG Compartment 341 8-RH-1108-BB1 8-RH-1108-BBI-1 RH 7G 6.813 -438 -221.37 231.01 Cold Below 5G Compartment 342 8-RH-1108-BB1 8-RH-1108-BB1-2 RH 7G 6.813 -422.5 -221.37 231.01 Cold Below SG Compartment 343 8-RH-1112-BB1 8-RH-1112-BBl-1 RH 7G 6.813 -375.82 -358.25 483.01 Hot SG Compartment 344 8-RH-1112-BB1 8-RH-1112-BBl-1A RH 7G 6.813 -333.39 -400.68 483.01 Hot SG Compartment 345 8-RH-1112-BB1 8-RH-1112-BB1-2 RH 7G 6.813 -327.03 -407.04 483.01 Hot 5G Compartment 346 8-RH-1208-BB1 8-RH-1208-BB1-1 RH 7G 6.813 -438 221.38 231.01 Cold Below SG Compartment 347 8-RH-1208-BB1 8-RH-1208-BB1-2 RH 7G 6.813 -422.5 221.38 231.01 Cold Below SG Compartment 348 8-RH-1212-BB1 8-RH-1212-BB1-1 RH 7G 6.813 -367.47 369.22 483.01 Hot SG Compartment 349 8-RH-1212-BB1 8-RH-1212-BB1-2 RH 7G 6.813 -331.42 405.27 483.01 Hot SG Compartment 350 8-RH-1308-BB1 8-RH-1308-BBl-1 RH 7G 6.813 553 170.12 230.92 Cold RHR Compartment 351 8-RH-1308-BB1 8-RH-1308-BB1-2 RH 7G 6.813 516 170.12 230.92 Cold RHR Compartment 352 8-RH-1315-BB1 8-RH-1315-BB1-1 RH 7G 6.813 387.53 370.28 491.92 Hot SG Compartment 353 8-51-1108-B81 8-S1-1108-BB1-1 SI 7G 6.813 -337.24 -422.26 483 Hot SG Compartment 354 8-SI-1108-BB1 8-SI-1108-BB1-2 SI 7G 6.813 -328.77 -413.79 483 Hot SG Compartment 355 8-SI-1108-BB1 8-SI-1108-BB1-3 SI 7G 6.813 -320.28 -405.3 483 Hot SG Compartment 356 8-SI-1108-BB1 8-SI-1108-BB1-4 SI 7G 6.813 -177.96 -262.98 483 Hot SG Compartment 357 8-S1-1108-BB1 8-SI-1108-BB1-5 SI 7C 6.813 -165.23 -250.25 483 Hot 5G Compartment 358 8-SI-1208-BB1 8-S1-1208-BB1-1 SI 7G 6.813 -338.58 420.91 483 Hot SG Compartment 359 8-S1-1208-BB1 8-SI-1208-BB1-2 Sl 7G 6.813 -332.83 415.17 483 Hot SG Compartment 360 8-S1-1208-BB1 8-SI-1208-BB1-3 SI 7G 6.813 -321.52 403.85 483 Hot SG Compartment 361 8-S1-1208-BB1 8-SI-1208-BB1-3A SI 7G 6.813 -177.2 259.54 483 Hot SG Compartment 362 8-S1-1208-BB1 8-SI-1208-BB1-4 SI 7C 6.813 -163.06 245.4 483 Hot SG Compartment 363 8-SI-1327-BB1 8-SI-1327-BB1-1 SI 7G 6.813 371.97 385.84 491.92 Hot SG Compartment 364 8-51-1327-881 8-51-1327-BB1-2 SI 7G 6.813 363.49 394.33 491.92 Hot SG Compartment 365 8-SI-1327-BB1 8-S1-1327-BB1-3 SI 7G 6.813 358.23 399.58 491.92 Hot SG Compartment 366 8-SI-1327-BB1 8-SI-1327-BB1-4 51 7G 6.813 349.75 408.07 503.92 Hot SG Compartment 367 8-SI-1327-BB1 8-S1-1327-BB1-5 SI 7G 6.813 349.75 408.07 528 Hot SG Compartment Page 139 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 368 8-S1-1327-BB1 8-S1-1327-BB1-6 SI 7G 6.813 341.26 399.58 540 Hot SG Compartment 369 8-Sl-1327-BB1 8-SI-1327-BB1-7 SI 7G 6.813 329.95 388.27 540 Hot SG Compartment 370 8-Sl-1327-BB1 8-51-1327-BB1-8 SI 7G 6.813 321.46 379.78 528 Hot SG Compartment 371 8-Sl-1327-BB1 8-SI-1327-BB1-9 SI 7G 6.813 321.46 379.78 504 Hot SG Compartment 372 8-51-1327-BB1 8-S1-1327-BB1-10 SI 7G 6.813 312.98 371.3 492 Hot SG Compartment 373 8-Sl-1327-BB1 8-S1-1327-B81-11 SI 7C 6.813 192.46 250.78 492 Hot SG Compartment 374 10-RH-1108-BB1 10-RH-1108-BBI-1 RH 7F 8.5 -422.5 -221.38 231.01 Cold Below SG Compartment 375 10-RH-1108-BB1 10-RH-1108-BB1-1A RH 7F 8.5 -410.33 -221.38 231.01 Cold Below SG Compartment 376 10-RH-1108-BB1 10-RH-1108-BB1-2 RH 7F 8.5 -404.08 -221.38 231.01 Cold Below SG Compartment 377 10-RH-1108-BB1 10-RH-1108-BB1-3 RH 7F 8.5 -386.08 -221.38 231.01 Cold Below SG Compartment 378 10-RH-1108-BB1 10-RH-1108-BB1-4 RH 7F 8.5 -349.7 -221.38 231.01 Cold Below SG Compartment 379 10-RH-1108-BB1 10-RH-1108-BB1-5 RH 7F 8.5 -333.7 -221.38 247.01 Cold Below SG Compartment 380 10-RH-1108-BB1 10-RH-1108-BB1-6 RH 7F 8.5 -333.7 -221.38 257.01 Cold Below SG Compartment 381 10-RH-1108-BB1 10-RH-1108-BB1-7 RH 7F 8.5 -333.7 -237.38 273.01 Cold Below SG Compartment 382 10-RH-1108-BB1 10-RH-1108-BB1-8 RH 7F 8.5 -333.7 -368.92 273.01 Cold Below SG Compartment 383 10-RH-1108-BB1 10-RH-1108-BB1-9 RH 7F 8.5 -338.39 -380.23 273.01 Cold Below SG Compartment 384 10-RH-1108-BB1 10-RH-1108-BB1-10 RH 7F 8.5 -342.19 -384.03 273.01 Cold Below SG Compartment 385 10-RH-1208-BB1 10-RH-1208-BB1-1 RH 7F 8.5 -422.5 221.38 231.01 Cold Below SG Compartment 386 10-RH-1208-BB1 10-RH-1208-BB1-2 RH 7F 8.5 -407.7 221.38 231.01 Cold Below SG Compartment 387 10-RH-1208-BB1 10-RH-1208-BB1-3 RH 7F 8.5 -395.7 221.38 231.01 Cold Below SG Compartment 388 10-RH-1208-BB1 10-RH-1208-BB1-4 RH 7F 8.5 -349.7 221.38 231.01 Cold Below SG Compartment 389 10-RH-1208-BB1 10-RH-1208-BB1-5 RH 7F 8.5 -333.7 221.38 247.01 Cold Below SG Compartment 390 10-RH-1208-BB1 10-RH-1208-BB1-6 RH 7F 8.5 -333.7 221.38 257.01 Cold Below SG Compartment 391 10-RH-1208-BB1 10-RH-1208-BB1-7 RH 7F 8.5 -333.7 237.38 273.01 Cold Below SG Compartment 392 10-RH-1208-BB1 10-RH-1208-BB1-8 RH 7F 8.5 -333.7 327.46 273.01 Cold Below SG Compartment 393 10-RH-1208-BB1 10-RH-1208-BB1-9 RH 7F 8.5 -333.7 352.87 273.01 Cold Below SG Compartment 394 10-RH-1208-BB1 10-RH-1208-BB1-10 RH 7F 8.5 -338.39 364.09 273.01 Cold Below SG Compartment 395 10-RH-1208-BB1 10-RH-1208-BB1-11 RH 7F 8.5 -346.46 372.16 273.01 Cold Below SG Compartment 396 10-RH-1308-BB1 10-RH-1308-BB1-1 RH 7F 8.5 510 170.12 230.92 Cold RHR Compartment 397 10-RH-1308-BB1 10-RH-1308-BB1-2 RH 7F 8.5 455.5 170.12 230.92 Cold Below SG Compartment 398 10-RH-1308-BB1 10-RH-1308-BB1-3 RH 7F 8.5 437.5 170.12 230.92 Cold Below SG Compartment 399 10-RH-1308-BB1 10-RH-1308-BB1-4 RH 7F 8.5 433 170.12 230.92 Cold Below SG Compartment 400 10-RH-1308-BB1 10-RH-1308-BB1-5 RH 7F 8.5 417 186.12 230.92 Cold Below SG Compartment 401 10-RH-1308-BB1 10-RH-1308-BB1-6 RH 7F 8.5 417 331.73 230.92 Cold Below SG Compartment 402 10-RH-1308-BB1 10-RH-1308-BB1-7 RH 7F 8.5 401 347.73 230.92 Cold Below SG Compartment 403 10-RH-1308-BB1 10-RH-1308-BB1-8 RH 7F 8.5 345 347.73 230.92 Cold Below SG Compartment 404 12-RC-1112-BB1 12-RC-1112-BB1-1 RHR-Suction 7E 10.126 -63.57 -236.94 503.31 Hot SG Compartment 405 12-RC-1112-BB1 12-RC-1112-BB1-2 RHR-Suction 7A 10.126 -53.99 -240.81 492.97 Hot SG Compartment 406 12-RC-1112-BB1 12-RC-1112-BB1-3 RHR-Suction 7A 10.126 -49.64 -242.57 481.66 Hot SG Compartment 407 12-RC-1112-BB1 12-RC-1112-BB1-4 RHR-Suction 7A 10.126 -49.64 -242.57 472.04 Hot SG Compartment 408 12-RC-1112-BB1 12-RC-1112-BB1-5 RHR-Suction 7A 10.126 -38.33 -253.88 4S6.04 Hot SG Compartment Page 140 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 409 12-RC-1112-BB1 12-RC-1112-BB1-6 RHR-Suction 7A 10.126 -22.7 -269.51 456.04 Hot SG Compartment 410 12-RC-1112-BB1 12-RC-1112-BB1-7 RHR-Suction 7A 10.126 -18.02 -280.82 456.04 Hot SG Compartment 411 12-RC-1112-BB1 12-RC-1112-BB1-8 RHR-Suction 7A 10.126 -18.02 -438 456.04 Hot SG Compartment 412 12-RC-1112-BB1 12-RC-1112-BB1-9 RHR-Suction 7E 10.126 -18.02 -485 456.04 Hot SG Compartment 413 12-RC-1112-BB1 12-RC-1112-BB1-10 RHR-Suction 7E 10.126 -34.02 -501 456.04 Hot SG Compartment 414 12-RC-1112-BB1 12-RC-1112-BB1-11 RHR-Suction 7E 10.126 -78.02 -501 456.04 Hot SG Compartment 415 12-RC-1125-BB1 12-RC-1125-BB1-1 SI-ACC-CL1 7N 10.126 -317.4 -428.18 273.02 Cold Below SG Compartment 416 12-RC-1125-BB1 12-RC-1125-BB1-2 SI-ACC-CL1 7N 10.126 -299.02 -446.57 273.02 Cold Below SG Compartment 417 12-RC-1125-BB1 12-RC-1125-BB1-3 Sl-ACC-CL1 7N 10.126 -276.39 -446.57 273.02 Cold Below SG Compartment 418 12-RC-1125-BB1 12-RC-1125-BB1-4 Sl-ACC-CL1 7N 10.126 -250.93 -421.11 273.02 Cold Below SG Compartment 419 12-RC-1125-BB1 12-RC-1125-BB1-5 SI-ACC-CL1 7N 10.126 -250.93 -398.49 273.02 Cold Below SG Compartment 420 12-RC-1125-BB1 12-RC-1125-BB1-6 SI-ACC-CL1 7N 10.126 -293.63 -355.79 273.02 Cold Below SG Compartment 421 12-RC-1125-BB1 12-RC-1125-BB1-7 SI-ACC-CL1 7N 10.126 -304.94 -344.48 289.02 Cold Below SG Compartment 422 12-RC-1125-BB1 12-RC-1125-BB1-8 Sl-ACC-CL1 7N 10.126 -304.94 -344.48 428.2 Cold SG Compartment 423 12-RC-1125-BB1 12-RC-1125-BB1-9 SI-ACC-CL1 7N 10.126 -304.94 -344.48 532.2 Cold SG Compartment 424 12-RC-1125-BB1 12-RC-1125-BB1-10 Sl-ACC-CL1 7N 10.126 -293.63 -333.17 548.2 Cold SG Compartment 425 12-RC-1125-BB1 12-RC-1125-BB1-11 Sl-ACC-CL1 7N 10.126 -220.44 -259.98 548.2 Cold SG Compartment 426 12-RC-1125-BB1 12-RC-1125-BB1-12 Sl-ACC-CL1 7N 10.126 -215.3 -248.6 546.6 Cold SG Compartment 427 12-RC-1125-BB1 12-RC-1125-BB1-13 Sl-ACC-CL1 7N 10.126 -213.67 -194.95 533.24 Cold SG Compartment 428 12-RC-1212-BB1 12-RC-1212-BB2-1 RHR-Suction 7E 10.126 -60.71 238.07 500.23 Hot SG Compartment 429 12-RC-1212-BB1 12-RC-1212-BB1-2 RHR-Suction 7A 10.126 -52.9 241.23 491.81 Hot SG Compartment 430 12-RC-1212-BB1 12-RC-1212-BB1-3 RHR-Suction 7A 10.126 -49.64 242.54 483.33 Hot SG Compartment 431 12-RC-1212-BB1 12-RC-1212-BB1-4 RHR-Suction 7A 10.126 -49.64 242.54 468.01 Hot SG Compartment 432 12-RC-1212-BB1 12-RC-1212-BB1-5 RHR-Suction 7A 10.126 -41.17 251.02 456.01 Hot SG Compartment 433 12-RC-1212-BB1 12-RC-1212-BB1-6 RHR-Suction 7A 10.126 -21.52 270.67 456.01 Hot SG Compartment 434 12-RC-1212-BB1 12-RC-1212-BB1-7 RHR-Suction 7A 10.126 -18.01 279.07 456.01 Hot SG Compartment 435 12-RC-1212-BB1 12-RC-1212-BB1-8 RHR-Suction 7A 10.126 -18.01 414.99 456.01 Hot SG Compartment 436 12-RC-1221-BB1 12-RC-1221-BB1-1 Sl-ACC-CL2 7N 10.126 -317.4 427.95 273.01 Cold Below SG Compartment 437 12-RC-1221-BB1 12-RC-1221-BB1-2 Sl-ACC-CL2 7N 10.126 -299.05 446.3 273.01 Cold Below SG Compartment 438 12-RC-1221-BB1 12-RC-1221-BB1-3 Sl-ACC-CL2 7N 10.126 -276.39 446.34 273.01 Cold Below SG Compartment 439 12-RC-1221-BB1 12-RC-1221-BB1-4 Sl-ACC-CL2 7N 10.126 -250.93 420.88 273.01 Cold Below SG Compartment 440 12-RC-1221-BB1 12-RC-1221-BB1-5 Sl-ACC-CL2 7N 10.126 -250.93 398.26 273.01 Cold Below SG Compartment 441 12-RC-1221-BB1 12-RC-1221-BB1-6 SI-ACC-CL2 7N 10.126 -293.63 355.56 273.01 Cold Below SG Compartment 442 12-RC-1221-BB1 12-RC-1221-BB1-7 Sl-ACC-CL2 7N 10.126 -304.94 344.25 289.01 Cold Below SG Compartment 443 12-RC-1221-BB1 12-RC-1221-BB1-8 Sl-ACC-CL2 7N 10.126 -304.94 344.25 410.59 Cold SG Compartment 444 12-RC-1221-BB1 12-RC-1221-BB1-9 Sl-ACC-CL2 7N 10.126 -304.94 344.25 532.17 Cold SG Compartment 445 12-RC-1221-BB1 12-RC-1221-BB1-10 Sl-ACC-CL2 7N 10.126 -293.63 332.94 548.17 Cold SG Compartment 446 12-RC-1221-BB1 12-RC-1221-BB1-11 Sl-ACC-CL2 7N 10.126 -260.97 300.28 548.17 Cold SG Compartment 447 12-RC-1221-BB1 12-RC-1221-BB1-12 SI-ACC-CL2 7N 10.126 -221.77 261.08 548.17 Cold SG Compartment 448 12-RC-1221-BB1 12-RC-1221-BB1-13 Sl-ACC-CL2 7N 10.126 -216.79 249.88 546.57 Cold SG Compartment 449 12-RC-1221-BB1 12-RC-1221-BB1-14 SI-ACC-CL2 7N 10.126 -215.13 196.36 533.24 Cold SG Compartment Page 141 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 450 12-RC-1312-BB1 12-RC-1312-BB1-1 RH 7E 10.126 84.95 238 500.48 Hot SG Compartment 451 12-RC-1312-BB1 12-RC-1312-BB1-2 RH 7A 10.126 76.9 241.25 491.8 Hot SG Compartment 452 12-RC-1312-BB1 12-RC-1312-BB1-3 RH 7A 10.126 73.64 242.57 483.31 Hot SG Compartment 453 12-RC-1312-BB1 12-RC-1312-BB1-4 RH 7A 10.126 73.64 242.57 468 Hot SG Compartment 454 12-RC-1312-BB1 12-RC-1312-BB1-5 RH 7A 10.126 65.16 251.06 456 Hot SG Compartment 455 12-RC-1312-BB1 12-RC-1312-BB1-6 RH 7A 10.126 45.51 270.7 456 Hot SG Compartment 456 12-RC-1312-B81 12-RC-1312-BB1-7 RH 7A 10.126 42 279.18 456 Hot SG Compartment 457 12-RC-1312-BB1 12-RC-1312-BB1-8 RH 7A 10.126 42 386.95 456 Hot SG Compartment 458 12-RC-1312-BB1 12-RC-1312-BB1-9 RH 7E 10.126 42 487.69 456 Hot SG Compartment 459 12-RC-1312-BB1 12-RC-1312-BB1-10 RH 7E 10.126 54 499.69 456 Hot SG Compartment 460 12-RC-1312-BB1 12-RC-1312-BB1-11 RH 7E 10.126 199.56 499.69 456 Hot SG Compartment 461 12-RC-1322-BB1 12-RC-1322-BB1-1 SI-ACC-CL3 7N 10.126 283.34 302.01 548.18 Cold SG Compartment 462 12-RC-1322-BB1 12-RC-1322-BB1-1A SI-ACC-CL3 7N 10.126 260.67 279.34 548.18 Cold SG Compartment 463 12-RC-1322-B81 12-RC-1322-BB1-2 Sl-ACC-CL3 7N 10.126 242.84 261.51 548.18 Cold SG Compartment 464 12-RC-1322-BB1 12-RC-1322-BB1-3 Sl-ACC-CL3 7N 10.126 238 249.97 546.51 Cold SG Compartment 465 12-RC-1322-BB1 12-RC-1322-BB1-4 Sl-ACC-CL3 7N 10.126 238 196.66 533.24 Cold SG Compartment 466 12-RH-1101-BB1 12-RH-1101-BB1-1 RH 7E 10.126 -108.02 -501 455.7 Hot SG Compartment 467 12-RH-1101-BB1 12-RH-1101-BB1-2 RH 7E 10.126 -226.24 -501 455.83 Hot SG Compartment 468 12-RH-1101-BB1 12-RH-1101-BB1-3 RH 7E 10.126 -237.38 -496.32 455.84 Hot SG Compartment 469 12-RH-1101-BB1 12-RH-1101-BB1-3A RH 7E 10.126 -328.79 -404.91 455.94 Hot SG Compartment 470 12-RH-1101-BB1 12-RH-1101-BB1-4 RH 7E 10.126 -372.86 -360.84 455.99 Hot SG Compartment 471 12-RH-1101-BB1 12-RH-1101-BB1-5 RH 7E 10.126 -408.95 -324.75 456.03 Hot SG Compartment 472 12-RH-1101-BB1 12-RH-1101-B81-6 RH 7E 10.126 -413.64 -313.53 456.04 Hot SG Compartment 473 12-RH-1101-BB1 12-RH-1101-BB1-7 RH 7E 10.126 -413.64 -255.38 456.04 Hot SG Compartment 474 12-RH-1101-BB1 12-RH-1101-B11-8 RH 7E 10.126 -429.64 -239.38 456.05 Hot SG Compartment 475 12-RH-1101-BB1 12-RH-1101-B11-9 RH 7E 10.126 -479.81 -239.37 456.11 Hot SG Compartment 476 12-RH-1101-BB1 12-RH-1101-BB1-10 RH 7E 10.126 -571.54 -239.38 456.21 Hot RHR Compartment 477 12-RH-1101-B81 12-RH-1101-BB1-11 RH 7E 10.126 -587.53 -239.38 440.23 Hot RHR Compartment 478 12-RH-1101-BB1 12-RH-1101-BB1-12 RH 7E 10.126 -587.61 -239.38 369.23 Hot RHR Compartment 479 12-RH-1101-BB1 12-RH-1101-BB1-13 RH 7E 10.126 -587.77 -239.38 225.23 Hot RHR Compartment 480 12-RH-1101-BB1 12-RH-1101-BB1-14 RH 7E 10.126 -587.85 -239.38 149.71 Hot RHR Compartment 481 12-RH-1101-BB1 12-RH-1101-BB1-15 RH 7E 10.126 -587.87 -223.38 129.04 Hot RHR Compartment 482 12-RH-1101-BB1 12-RH-1101-BB1-16 RH 7E 10.126 -587.87 -190.38 129.04 Hot RHR Compartment 483 12-RH-1201-BB1 12-RH-1201-BB1-1 RH 7E 10.126 -18.01 453.99 456.01 Hot SG Compartment 484 12-RH-1201-BB1 12-RH-1201-BB1-2 RH 7E 10.126 -18.01 485.99 456.01 Hot SG Compartment 485 12-RH-1201-BB1 12-RH-1201-BB1-3 RH 7E 10.126 -34.01 501.99 456.01 Hot SG Compartment 486 12-RH-1201-BB1 12-RH-1201-BB1-4 RH 7E 10.126 -226.44 501.99 456.01 Hot SG Compartment 487 12-RH-1201-BB1 12-RH-1201-BB1-5 RH 7E 10.126 -237.76 497.31 456.01 Hot SG Compartment 488 12-RH-1201-BB1 12-RH-1201-BB1-6 RH 7E 10.126 -323.53 411.53 456.01 Hot SG Compartment 489 12-RH-1201-BB1 12-RH-1201-BB1-7 RH 7E 10.126 -409.38 325.69 456.01 Hot SG Compartment 490 12-RH-1201-8B1 12-RH-1201-BB1-8 RH 7E 10.126 -414 314.43 456.01 Hot SG Compartment Page 142 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 491 12-RH-1201-BB1 12-RH-1201-BB1-9 RH 7E 10.126 -414 256.38 456.01 Hot SG Compartment 492 12-RH-1201-BB1 12-RH-1201-BB1-10 RH 7E 10.126 -430 240.38 456.01 Hot SG Compartment 493 12-RH-1201-B81 12-RH-1201-BB1-11 RH 7E 10.126 -530.54 240.38 456.01 Hot RHR Compartment 494 12-RH-1201-BB1 12-RH-1201-BB1-12 RH 7E 10.126 -588 240.38 432.01 Hot RHR Compartment 495 12-RH-1201-BB1 12-RH-1201-BB1-13 RH 7E 10.126 -588 240.38 423.01 Hot RHR Compartment 496 12-RH-1201-BB1 12-RH-1201-BB1-14 RH 7E 10.126 -588 240.38 237.01 Hot RHR Compartment 497 12-RH-1201-BB1 12-RH-1201-BB1-15 RH 7E 10.126 -588 240.38 153.01 Hot RHR Compartment 498 12-RH-1201-BB1 12-RH-1201-BB1-16 RH 7E 10.126 -588 213.12 129.01 Hot RHR Compartment 499 12-RH-1201-BB1 12-RH-1201-BB1-17 RH 7E 10.126 -588 191.38 129.01 Hot RHR Compartment 500 12-RH-1301-BB1 12-RH-1301-BB1-1 RH 7E 10.126 232.84 499.69 456 Hot SG Compartment 501 12-RH-1301-BB1 12-RH-1301-BB1-2 RH 7E 10.126 251.71 499.69 456 Hot SG Compartment 502 12-RH-1301-BB1 12-RH-1301-BB1-3 RH 7E 10.126 263.02 495 456 Hot SG Compartment 503 12-RH-1301-BB1 12-RH-1301-BB1-4 RH 7E 10.126 441.96 316.06 456 Hot SG Compartment 504 12-RH-1301-BB1 12-RH-1301-BB1-5 RH 7E 10.126 454.32 311.37 456 Hot SG Compartment 505 12-RH-1301-881 12-RH-1301-BB1-5A RH 7E 10.126 515.15 311.37 456 Hot RHR Compartment 506 12-RH-1301-BB1 12-RH-1301-BB1-6 RH 7E 10.126 523.96 311.37 456 Hot RHR Compartment 507 12-RH-1301-BB1 12-RH-1301-BB1-7 RH 7E 10.126 539.96 311.37 435 Hot RHR Compartment 508 12-RH-1301-BB1 12-RH-1301-BB1-8 RH 7E 10.126 539.96 311.37 415 Hot RHR Compartment 509 12-RH-1301-BB1 12-RH-1301-BB1-9 RH 7E 10.126 539.96 295.37 399 Hot RHR Compartment 510 12-RH-1301-BB1 12-RH-1301-BB1-10 RH 7E 10.126 539.96 265.37 399 Hot RHR Compartment 511 12-S1-1125-BB1 12-SI-1125-BB1-1 5l-ACC-CL1 70 10.126 -383.87 -361.72 273.02 Cold Below SG Compartment 512 12-S1-1125-BB1 12-S1-1125-881-2 51-ACC-CL1 70 10.126 -364.07 -381.51 273.02 Cold Below SG Compartment 513 12-SI-1125-BB1 12-SI-1125-BB1-3 SI-ACC-CL1 70 10.126 -355.59 -390 273.02 Cold Below SG Compartment 514 12-S1-1125-BB1 12-S1-1125-BB1-4 SI-ACC-CL1 70 10.126 -344.27 -401.31 273.02 Cold Below SG Compartment 515 12-51-1218-BB1 12-SI-1218-BB1-1 SI-ACC-CL2 70 10.126 -383.87 361.49 273.01 Cold Below SG Compartment 516 12-S1-1218-881 12-S1-1218-B81-2 Sl-ACC-CL2 70 10.126 -365.49 379.87 273.01 Cold Below SG Compartment 517 12-51-1218-881 12-SI-1218-B81-3 SI-ACC-CL2 70 10.126 -354.17 391.18 273.01 Cold Below SG Compartment 518 12-S1-1218-BB1 12-S1-1218-8B1-4 SI-ACC-CL2 70 10.126 -344.27 401.08 273.01 Cold Below SG Compartment 519 12-SI-1315-BB1 12-SI-1315-BB1-1 51-ACC-CL4 70 10.126 366.48 385.2 191.01 Cold Below SG Compartment 520 12-SI-1315-BB1 12-51-1315-BB1-2 SI-ACC-CL4 70 10.126 340.31 359.04 191.01 Cold Below SG Compartment 521 12-S1-1315-881 12-S1-1315-BB1-3 Sl-ACC-CL4 70 10.126 329 347.73 207.01 Cold Below 5G Compartment 522 12-S1-1315-881 12-S1-1315-BB1-4 SI-ACC-CL4 70 10.126 329 347.73 225.01 Cold Below SG Compartment 523 12-SI-1315-BB1 12-S1-1315-BB1-5 51-ACC-CL1 70 10.126 329 347.73 237.01 Cold Below SG Compartment 524 12-Sl-1315-BB1 12-S1-1315-B81-6 51-ACC-CL4 70 10.126 329 347.73 379.07 Cold SG Compartment 525 12-SI-1315-BB1 12-S1-1315-BB1-7 51-ACC-CL4 70 10.126 329 347.73 447.73 Cold SG Compartment 526 12-SI-1315-8B1 12-SI-1315-B81-8 51-ACC-CL4 7D 10.126 329 347.73 532.19 Cold SG Compartment 527 12-SI-1315-BB1 12-SI-1315-B81-9 SI-ACC-CL4 7D 10.126 317.69 336.41 548.19 Cold SG Compartment 528 12-SI-1315-BB1 12-S1-1315-BB1-10 SI-ACC-CL4 7D 10.126 309.42 328.15 548.19 Cold SG Compartment 529 16-RC-1412-NSS 16-RC-1412-NSS-1 Pressurizer Surge Line 4B 12.814 12 -678 688.5 Hot Surge Line530 16-RC-1412-NSS 16-RC-1412-NSS-3 Pressurizer Surge Line 48 12.814 181.01 -678 528.97 Hot Surge Line531 16-RC-1412-NSS 16-RC-1412-NSS-4 Pressurizer Surge Line 4B 12.814 205 -654 528.41 Hot Surge LinePage 143 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 532 16-RC-1412-NSS 16-RC-1412-NSS-5 Pressurizer Surge Line 4B 12.814 205 -531 526.97 Hot SG Compartment 533 16-RC-1412-NSS 16-RC-1412-NSS-6 Pressurizer Surge Line 4B 12.814 180.85 -507 526.41 Hot SG Compartment 534 16-RC-1412-NSS 16-RC-1412-NSS-7 Pressurizer Surge Line 4B 12.814 91.98 -507 525.37 Hot SG Compartment 535 16-RC-1412-NSS 16-RC-1412-NSS-8 Pressurizer Surge Line 4B 12.814 12 -400.56 523.22 Hot SG Compartment 536 16-RC-1412-NSS 16-RC-1412-NSS-9 Pressurizer Surge Line 4C 12.814 89.65 -262.75 522 Hot SG Compartment 537 16-RC-1412-NSS 16-RC-1412-NSS-PRZ-1-N1-SE Pressurizer Surge Line 4A 12.814 12 -678 691 Hot Surge Line538 27.5-RC-1103-NSS

-LOOP 1 27.5-RC-1103-NSS-1 RC Cold Leg 1 3C 27.5 -264.83 -202.37 522 Cold SG Compartment 539 27.5-RC-1103-NSS

-LOOP 1 27.5-RC-1103-NSS-3 RC 71 3.438 -252.54 -190.08 541.08 Cold SG Compartment 540 27.5-RC-1103-NSS

-LOOP 1 27.5-RC-1103-NSS-4 SI-ACC-CL1 7N 10.126 -212.31 -149.85 522 Cold SG Compartment 541 27.5-RC-1103-NSS

-LooP 1 27.5-RC-1103-NSS-5 CV 8E 3.438 -201.49 -112.07 522 Cold SG Compartment 542 27.5-RC-1103-NSS

-LOOP 1 27.5-RC-1103-NSS-6 RC Cold Leg 1 3C 27.5 -122.74 -60.28 522 Cold RX Cavity543 27.5-RC-1103-NSS

-LOOP 1 27.5-RC-1103-NSS-7 RC Cold Leg 1 3C 27.5 -117.38 -54.92 522 Cold RX Cavity544 27.5-RC-1103-NSS

-LOOP 1 27.5-RC-1103-NSS-RPV1-N2ASE RC Cold Leg 1 3A 27.5 -108.79 -51.27 522 Cold RX Cavity545 27.5-RC-1203-NSS

-LOOP 2 27.5-RC-1203-NSS-1 RC Cold Leg 2 3C 27.5 -264.83 202.37 522 Cold SG Compartment 546 27.5-RC-1203-NSS

-LOOP 2 27.5-RC-1203-NSS-3 Sl-ACC-CL2 7N 10.126 -214.54 177.45 528.52 Cold SG Compartment 547 27.5-RC-1203-NSS

-LOOP 2 27.5-RC-1203-NSS-4 RC Cold Leg 2 3C 27.5 -122.74 60.28 522 Cold RX Cavity548 27.5-RC-1203-NSS

-LOOP 2 27.5-RC-1203-NSS-5 RC Cold Leg 2 3C 27.5 -110.41 51.96 522 Cold RX Cavity549 27.5-RC-1203-NSS

-LOOP 2 27.5-RC-1203-NSS-RPV1-N2BSE RC Cold Leg 2 3A 27.5 -108.79 51.27 522 Cold RX Cavity550 27.5-RC-1303-NSS

-LOOP 3 27.5-RC-1303-NSS-1 RC Cold Leg 3 3C 27.5 288.83 202.37 522 Cold SG Compartment 551 27.5-RC-1303-NSS

-LOOP 3 27.5-RC-1303-NSS-3 Sl-ACC-CL3 7N 10.126 238 177.01 528.34 Cold SG Compartment 552 27.5-RC-1303-NSS

-LOOP 3 27.5-RC-1303-NS5-4 CV 8E 3.438 198.5 139 522 Cold SG Compartment 553 27.5-RC-1303-NSS

-LOOP 3 27.5-RC-1303-NSS-5 RC Cold Leg 3 3C 27.5 146.74 60.28 522 Cold RX Cavity554 27.5-RC-1303-NSS

-LOOP 3 27.5-RC-1303-NSS-6 RC Cold Leg 3 3C 27.5 134.41 51.96 522 Cold RX Cavity555 27.5-RC-1303-NSS

-LOOP 3 27.5-RC-1303-NSS-RPV1-N2CSE RC Cold Leg 3 3A 27.5 132.79 51.27 522 Cold RX Cavity556 27.5-RC-1403-NSS

-LOOP 4 27.5-RC-1403-NSS-1 RC Cold Leg 4 3C 27.5 288.83 -202.37 522 Cold SG Compartment 557 27.5-RC-1403-NSS

-LOOP 4 27.5-RC-1403-NSS-3 RC 71 3.438 273.56 -187.1 541.06 Cold SG Compartment 558 27.5-RC-1403-NSS

-LOOP 4 27.5-RC-1403-NSS-4 RC 71 3.438 254.15 -186.75 535.48 Cold SG Compartment 559 27.5-RC-1403-NSS

-LOOP 4 27.5-RC-1403-NSS-5 RC Cold Leg 4 3C 27.5 146.74 -60.28 522 Cold RX Cavity560 27.5-RC-1403-NSS

-LOOP 4 27.5-RC-1403-NSS-6 RC Cold Leg 4 3C 27.5 134.41 -51.96 522 Cold RX Cavity561 27.5-RC-1403-NSS

-LOOP 4 27.5-RC-1403-NSS-RPV1-N2DSE RC Cold Leg 4 3A 27.5 132.79 -51.27 522 Cold RX Cavity562 29-RC-1101-NSS

-LOOP 1 29-RC-1101-NSS-1 RC-Hot Leg 1 1B 29 -36.35 -119.66 522 Hot RX Cavity563 29-RC-1101-NSS

-LOOP 1 29-RC-1101-NSS-2 SI 7G 6.813 -99.42 -222.46 522 Hot SG Compartment 564 29-RC-1101-NSS

-LOOP 1 29-RC-1101-NSS-3 RHR-Suction 7E 10.126 -67.51 -235.35 507.55 Hot SG Compartment 565 29-RC-1101-NSS

-LOOP 1 29-RC-1101-NSS-4 RC-Hot Leg 1 18 29 -101.37 -280.59 522 Hot SG Compartment 566 29-RC-1101-NSS

-LOOP 1 29-RC-1101-NSS-5.1 RC-Hot Leg 1 lB 29 -115.72 -316.11 539.86 Hot SG Compartment 567 29-RC-1101-NSS

-LOOP 1 29-RC-1101-NSS-RPV1-NIASE RC-Hot Leg 1 1A 29 -34.1 -114.1 522 Hot RX Cavity568 29-RC-1101-NSS

-LOOP 1 29-RC-1101-NSS-RSG-1A-IN-SE RC-Hot Leg 1 2 29 -115.85 -316.43 540.28 Hot SG Compartment 569 29-RC-1201-NSS

-LOOP 2 29-RC-1201-NSS-1 RC-Hot Leg 2 1B 29 -36.35 119.66 522 Hot RX Cavity570 29-RC-1201-NSS

-LOOP 2 29-RC-1201-NSS-2 Sl 7G 6.813 -99.84 222.29 522 Hot SG Compartment 571 29-RC-1201-NSS

-LOOP 2 29-RC-1201-NSS-3 RC 7E 10.126 -67.5 235.33 507.55 Hot SG Compartment 572 29-RC-1201-NSS

-LOOP 2 29-RC-1201-NSS-4 RC-Hot Leg 2 lB 29 -101.37 280.59 522 Hot SG Compartment Page 144 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1291-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 573 29-RC-1201-NSS

-LOOP 2 29-RC-1201-NSS-5.1 RC-Hot Leg 2 1B 29 -115.72 316.11 539.86 Hot SG Compartment 574 29-RC-1201-NSS

-LOOP 2 29-RC-1201-RPV1-N1BSE RC-Hot Leg 2 1A 29 -34.1 114.1 522 Hot RX Cavity575 29-RC-1201-NSS

-LOOP 2 29-RC-1201-RSG-18-IN-SE RC-Hot Leg 2 2 29 -115.85 316.43 540.28 Hot SG Compartment 576 29-RC-1301-NSS

-LOOP 3 29-RC-1301-NSS-1 RC-Hot Leg 3 1B 29 60.35 119.67 522 Hot RX Cavity577 29-RC-1301-NSS

-LOOP 3 29-RC-1301-NSS-2 SI 7G 6.813 123.84 222.29 522 Hot SG Compartment 578 29-RC-1301-NSS

-LOOP 3 29-RC-1301-NSS-3 RC 7E 10.126 91.51 235.35 507.55 Hot SG Compartment 579 29-RC-1301-NSS

-LOOP 3 29-RC-1301-NSS-4 RC-Hot Leg 3 1B 29 125.37 280.6 522 Hot SG Compartment 580 29-RC-1301-NSS

-LOOP 3 29-RC-1301-NSS-5.1 RC-Hot Leg 3 1B 29 139.72 316.12 539.86 Hot SG Compartment 581 29-RC-1301-NSS

-LOOP 3 29-RC-1301-RPV1-NICSE RC-Hot Leg 3 1A 29 58.1 114.11 522 Hot RX Cavity582 29-RC-1301-NSS

-LOOP 3 29-RC-1301-RSG-1C-IN-SE RC-Hot Leg 3 2 29 139.85 316.44 540.28 Hot SG Compartment 583 29-RC-1401-NSS

-LOOP 4 29-RC-1401-NSS-1 RC-Hot Leg 4 1B 29 60.35 -119.66 522 Hot RX Cavity584 29-RC-1401-NSS

-LOOP 4 29-RC-1401-NSS-2 Pressurizer Surge Line 4C 12.814 95.22 -260.5 522 Hot SG Compartment 585 29-RC-1401-NSS

-LOOP 4 29-RC-1401-NSS-3 RC-Hot Leg 4 iC 29 125.37 -280.59 522 Hot SG Compartment 586 29-RC-1401-NSS

-LOOP 4 29-RC-1401-NSS-4.1 RC-Hot Leg 4 1B 29 139.72 -316.11 539.86 Hot SG Compartment 587 29-RC-1401-NSS

-LOOP 4 29-RC-1401-NSS-RPV1-N1DSE RC-Hot Leg 4 1A 29 58.1 -114.1 522 Hot RX Cavity588 29-RC-1401-NSS

-LOOP 4 29-RC-1401-NSS-RSG-1D-IN-SE RC-Hot Leg 4 2 29 139.85 -316.43 540.28 Hot SG Compartment 589 31-RC-1102-NSS

-LOOP 1 31-RC-1102-NSS-1.1 RC Cold Leg 1 3D 31 -195.08 -364.07 538.7 Cold SG Compartment 590 31-RC-1102-NSS

-LOOP 1 31-RC-1102-NSS-2 RC Cold Leg 1 3D 31 -206.74 -363.05 506.56 Cold SG Compartment 591 31-RC-1102-NSS

-LOOP 1 31-RC-1102-NSS-3 RC Cold Leg 1 3D 31 -206.74 -363.05 441.31 Cold SG Compartment 592 31-RC-1102-NSS

-LOOP 1 31-RC-1102-NSS-4 RC Cold Leg 1 3D 31 -234.4 -338.57 404.31 Cold SG Compartment 593 31-RC-1102-NS5

-LOOP 1 31-RC-1102-NSS-5 RC 7K* 1.689 -252 -323 425.33 Cold SG Compartment 594 31-RC-1102-NSS

-LOOP 1 31-RC-1102-NSS-6 RC 7K 1.689 -271.12 -306.08 383.29 Cold SG Compartment 595 31-RC-1102-NSS

-LOOP 1 31-RC-1102-NSS-7 RC 7J 2.626 -278.44 -299.61 425.33 Cold SG Compartment 596 31-RC-1102-NSS

-LOOP 1 31-RC-1102-NSS-8 RC Cold Leg 1 3D 31 -289.67 -289.67 404.31 Cold SG Compartment 597 31-RC-1102-NSS

-LOOP 1 31-RC-1102-NSS-9 RC Cold Leg 1 3D 31 -322.81 -260.35 448.56 Cold SG Compartment 598 31-RC-1102-NSS

-LOOP 1 31-RC-1102-NSS-RSG-1A-ON-SE RC Cold Leg 1 3B 31 -195.04 -364.07 538.75 Cold SG Compartment 599 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-1.1 RC Cold Leg 2 3D 31 -195.08 364.07 538.7 Cold SG Compartment 600 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-2 RC Cold Leg 2 3D 31 -206.74 363.05 506.56 Cold SG Compartment 601 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-3 RC Cold Leg 2 3D 31 -206.74 363.05 441.31 Cold SG Compartment 602 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-4 RC Cold Leg 2 30 31 -234.43 338.54 404.31 Cold SG Compartment 603 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-5 RC 7K 1.689 -249.25 325.43 425.33 Cold SG Compartment 604 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-6 RC 7J 2.626 -278.44 299.61 425.33 Cold SG Compartment 605 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-7 RC 7K 1.689 -271.15 306.06 383.29 Cold SG Compartment 606 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-8 RC Cold Leg 2 3D 31 -289.7 289.65 404.31 Cold SG Compartment 607 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-9 RC Cold Leg 2 3D 31 -322.81 260.35 448.56 Cold SG Compartment 608 31-RC-1202-NSS

-LOOP 2 31-RC-1202-NSS-RSG-1B-ON-SE RC Cold Leg 2 3B 31 -195.05 364.07 538.74 Cold SG Compartment 609 31-RC-1302-NSS

-LOOP 3 31-RC-1302-NSS-1.1 RC Cold Leg 3 3D 31 219.08 364.07 538.7 Cold SG Compartment 610 31-RC-1302-NSS

-LOOP 3 31-RC-1302-NSS-2 RC Cold Leg 3 3D 31 230.74 363.05 506.56 Cold SG Compartment 611 31-RC-1302-NSS

-LOOP 3 31-RC-1302-NSS-3 RC Cold Leg 3 3D 31 230.74 363.05 441.29 Cold SG Compartment 612 31-RC-1302-NSS

-LOOP 3 31-RC-1302-NSS-4 RC Cold Leg 3 3D 31 258.45 338.53 404.31 Cold SG Compartment 613 31-RC-1302-NSS

-LOOP 3 31-RC-1302-NSS-5 RC 7K 1.689 272.81 325.82 425.33 Cold SG Compartment Page 145 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2No. Line Number Location Name System Category Pipe ID X Y Z Side Compartment 614 31-RC-1302-NSS

-LOOP 3 31-RC-1302-NSS-6 RC 7. 2.626 302.44 299.61 425.33 Cold SG Compartment 615 31-RC-1302-NSS

-LOOP 3 31-RC-1302-NSS-7 RC 71 3.438 295.13 306.07 383.29 Cold SG Compartment 616 31-RC-1302-NSS

-LOOP 3 31-RC-1302-NSS-8 RC Cold Leg 3 3D 31 313.67 289.67 404.31 Cold SG Compartment 617 31-RC-1302-NSS

-LOOP 3 31-RC-1302-NSS-9 RC Cold Leg 3 3D 31 346.81 260.35 448.56 Cold SG Compartment 618 31-RC-1302-NS5

-LOOP 3 31-RC-1302-NSS-RSG-1C-ON-SE RC Cold Leg 3 3B 31 219.08 364.07 538.7 Cold SG Compartment 619 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-1.1 RC Cold Leg 4 3D 31 219.08 -364.07 538.7 Cold SG Compartment 620 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-2 RC Cold Leg 4 3D 31 230.74 -363.05 506.56 Cold SG Compartment 621 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-3 RC Cold Leg 4 3D 31 230.74 -363.05 441.31 Cold SG Compartment 622 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-4 RC Cold Leg 4 3D 31 258.45 -338.53 404.31 Cold SG Compartment 623 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-5 RC 7K 1.689 273.37 -325.32 425.33 Cold SG Compartment 624 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-6 RC 7J 2.626 302.44 -299.61 425.33 Cold SG Compartment 625 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-7 RC 7K 1.689 295.15 -306.06 383.29 Cold SG Compartment 626 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-8 RC Cold Leg 4 3D 31 313.67 -289.67 404.31 Cold SG Compartment 627 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-9 RC Cold Leg 4 3D 31 346.81 -260.35 448.56 Cold SG Compartment 628 31-RC-1402-NSS

-LOOP 4 31-RC-1402-NSS-RSG-1D-ON-SE RC Cold Leg 4 3B 31 219.05 -364.07 538.74 Cold SG Compartment Page 146 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSl191-V03 Revision 25.3.3 Statistical Fit of NUREG-1829 LOCA Frequencies NUREG-1829 provides a set of LOCA frequency uncertainties (corresponding to the 5th percentile, median, mean, and 95th percentile) for six different break sizes (Y2", 1-5/8", 3", 7", 14", and 31") (37).The values corresponding to each break size were fit with a bounded Johnson distribution to define thefull range of epistemic uncertainty associated with LOCA frequencies (8). This is illustrated in Figure5.3.2.10010.2PWR 25-yr Fleet-Average Operation XACDa,++ Bounded Johnson4+,95dm mean+ 50th* 5thI I IIII10-1010"110 20510 15 20Break Size (in.)25 30 35Figure 5.3.2 -Illustration of bounded Johnson fit for NUREG-1829 break frequencies The bounded Johnson cumulative distribution function and optimization model are shown in Equation23 and Equation 24 (8), and the fitted parameters are provided in Section 2.2.3.F[x] = + 6f[(x -'f)/,D]Equation 23Page 147 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2where (D[x] is the cumulative distribution function of a standard normal random variable, y and 6 areshape parameters (with y driving the distribution's skewness),

ý is a location parameter, A, is a scaleparameter, and f(z) = log[z / (1-z)] for k < x!5 + X.min (F[x0.05] -0.05)2 + (F[xo.so]

-0.50)2 + (F[xo.9s] -0.95)2Y,&,ý,As.t. X -X0.05 Equation 24+ ý -> Xo.956, , A 05.3.4 Sample Epistemic Uncertainty of LOCA Frequencies Given the fitted distribution parameters, the epistemic uncertainty of the LOCA frequency data inNUREG-1829 can be sampled.

For example, if the 62nd percentile is selected, the LOCA frequencies canbe calculated based on Equation 23 and the parameters in Section 2.2.3. The calculated 62nd percentile values are shown in Table 5.3.4. Figure 5.3.3 shows the LOCA frequency vs. break size for the 62ndpercentile assuming linear interpolation between the values in Table 5.3.4. (Note that the shape of theinterpolated curves appears to be non-linear on a semi-log plot.)Table 5.3.4 -Example calculation of LOCA frequencies vs. break size for 62nd Percentile 62 Percentile B ize LOCA Frequencies (in) (year")0.5 1.06E-031.625 1.66E-043 6.35E-067 5.92E-0714 2.74E-0831 2.89E-09Page 148 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2LOCA Frequency for 62nd Percentile 1.OE-021.OE-031.OE-041.OE-05I 1.OE-061.0E-071.OE-081.OE-090 5 10 15 20 25 30 35Break Size (In)Figure 5.3.3 -Illustration of LOCA frequency vs. break size for 62nd percentile 5.3.5 Sample Break Sizes at Each Weld LocationCASA Grande evaluates multiple sizes of breaks at every weld in containment, and it always includes theDEGB condition for every weld. The total number of break scenarios investigated for each weld isdetermined based on user input for the maximum desired number of breaks in the largest pipe, NL. Oneof these breaks is assigned to the DEGB condition, and the remaining number are selected from NL-- 1strata defined across the large break size range. The range of break sizes for a given weld wassubdivided into a number of intervals proportional to the range of the largest possible LBLOCA. Thestandard LOCA bins of 0.5 to 2 inches (SBLOCAs),

2 to 6 inches (MBLOCAs),

and greater than 6 inchesPage 149 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2(LBLOCAs) were used; so the number of breaks in the small and medium range were determined by thefollowing formulas19:Ns= ceil ( Dmax 6 NL) Equation 25('6-2 )NM =ceil D -6NL) Equation 26mD~ax-6where:Ns = Number of breaks in SBLOCA categoryNM = Number of breaks in MBLOCA categoryNL = Number of breaks in LBLOCA categoryDmax = Maximum break size in containment (in)The ceil(x) operator simply rounds up to the nearest integer.

This guarantees that there is always at leastone small break and at least one medium break at every weld that can support breaks of these sizes.Given the desired number of breaks in each LOCA category, the conditional probability for breaks in theassociated weld case was divided into an equivalent number of non-uniform bins (unequal size), and theprobability weights for each bin were recorded.

Random percentiles were selected from eachprobability bin, and the conditional probability was interpolated to find corresponding break sizes.(Neither the probability bins, nor the corresponding size intervals are of equal size.) The set of discretebreak sizes are matched with their probability weight and carried throughout the evaluation asindependent break scenarios.

When this algorithm is applied to the STP weld population for NL = 10, the total number of scenarios isapproximately 3,070. When NL = 5, the number of scenarios is approximately 2,250, and when NL = 3,the number of scenarios is approximately 2,100. For this evaluation, all sampling replicates were runwith NL = 5. A given choice of NL determines the LHS sample size for a single replicate CASA evaluation.

Quantitative evaluations presented here are based on 20 replicates for each of 15 Johnson uncertainty percentiles (675,000 break scenarios for each plant failure case).Figure 5.3.4 illustrates the break-size selection process for Weld Case 1B, which includes the largestpipes in containment.

LOCA category limits are marked with vertical solid lines. The DEGB condition, marked with a red dot, represents one of the 10 breaks imposed on the LBLOCA range. The remaining 19 There are several methods that could be used to select the bins for small, medium, and large breaks. Thismethod emphasizes the contributions of the larger breaks while also ensuring that small and medium breaks areconsidered.

Page 150 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2nine equal break-size intervals are separated by vertical dashed lines between 6 inches and 31.5 inches(the maximum pipe diameter).

Note that the size intervals only appear unequal because of thelogarithmic scale. By relative proportion of their respective ranges, only two break intervals are assignedto MBLOCAs, and only one is assigned SBLOCAs.

Thus, for this example, 13 breaks are simulated at eachweld belonging to Weld Case lB.Illustration of Logarithmic Sample Bins for Case 1BIIA .9~10OD 1001010 .--1 1a sI (efeci I i nI ."o I i111111II I1i II I II I I I10"1 .,I t ., I. .100 101 102break size (effective diam, in.)Figure 5.3.4 -Example of non-uniform stratified sampling strategy for one weld case5.4 Debris Generation Debris generation analysis includes calculations of the total quantity of insulation,

coatings, latent, andmiscellaneous debris, as well as a definition of debris characteristics (size and density).

These topics arediscussed in this section.5.4.1 ZOI ModelThe quantity of insulation debris generated is calculated directly in CASA Grande based on the currently accepted deterministic ZOI model. As described in NEI 04-07 Volume 2, the break jet ZOI can beconservatively modeled as a sphere for a fully offset DEGB or as a hemisphere for anything less than aPage 151 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2DEGB (i.e., a side-wall pipe break) (45). The ZOI radius depends on the destruction pressure of theinsulation and the size of the break. As shown in Section 2.2.14, the ZOI sizes for insulation at STP are 2Dfor Transco RMI, 17D for Nukon and Thermal-Wrap (assumed to be the same as Nukon), and 28.6D forMicrotherm (assumed to be the same as Min-K). All insulation that falls within its respective ZOI isassumed to become debris.Figure 5.4.1 through Figure 5.4.3 show examples of the ZOls for a large 31-inch DEGB, a medium 6-inchside-wall break, and a small 2-inch side-wall break. Because of the spherical ZOI assumption, thedirection of the jet is irrelevant for DEGBs (see Figure 5.4.1). The jet direction and orientation of thehemispherical ZOI for side-wall breaks is dependent on the break location radially around the pipe, butthe ZOI is constrained along the axis of the pipe (see Figure 5.4.2 and Figure 5.4.3).Page 152 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.4.1 -Illustration of 17D Nukon ZOI for a 31" DEGBPage 153 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Figure 5.4.2 -Illustration of 17D Nukon ZOI for a 6" side-wall breakFigure 5.4.3 -Illustration of 17D Nukon ZOI for a 2" side-wall breakPage 154 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Jet formation modeling was conducted to evaluate the potential conservatism in the ZOI size and shape(10). However, the effects of realistic jets on the ZOls were not explicitly considered in this evaluation.

5.4.2 Insulation Debris Size Distribution ModelTo implement the fiberglass debris size distribution described in Section 2.2.15, the fiberglass ZOI wassplit into three sub-zones.

The quantity of fiberglass insulation in each sub-zone was multiplied by theappropriate percentage of fines, small pieces, large pieces, and intact blankets as defined in Table 4.1 ofthe Alion debris size distribution report (46). Figure 5.4.4 shows an example of the size distribution sub-zones.11.9D Sub-ZoneFigure 5.4.4 -Illustration of sub-zones used for fiberglass debris size distribution Page 155 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2The Microtherm debris was assumed to fail as 100% fines with components of SiO2, TiO2, and fibers asdescribed in Section 2.2.15.5.4.3 Insulation DebrisUsing the LOCA frequency sampling strategy described in Section 5.3, three replicates of approximately 2,250 break scenarios each were sampled to illustrate the probability distribution associated with ZOIdebris volume. These calculations assumed a 17D ZOI for Nukon and Thermal Wrap insulation.

Figure5.4.5 shows the complementary cumulative probability distribution function formed from the fiberglass debris quantities calculated for these scenarios with the relative initiating event frequencies included asprobability weights.

As shown on this figure, the maximum quantity of fiberglass debris that can begenerated approaches 3,000 ft3, but 99.9% of the scenarios generate less than 10 ft3of fiberglass debris.Dist of ZOi Debris Volume -With Walls100 -2......10- ...102A^ 10".E12o 1410- .10"12 10-1410-,101 102total debris volume (ft3)Figure 5.4.5 -Distribution of potential fiberglass debris quantities 5.4.4 Qualified Coatings DebrisSimilar to insulation debris, the quantity of qualified coatings debris is calculated based on the quantityof coatings within the ZOI. However, due to the difficulty of accurately modeling all of the coatedPage 156 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2surfaces within CASA Grande, the qualified coatings debris calculations were performed outside of CASAGrande using the CAD model. As described in Section 2.2.9, bounding quantities of qualified epoxy andIOZ coatings debris were determined for break sizes of 2-inch, 6-inch, 15-inch, and 31-inch DEGB. InCASA, the bounding 31-inch DEGB quantities were applied for all breaks.5.4.5 Unqualified Coatings DebrisThe inputs for unqualified epoxy, alkyd, IOZ, and baked enamel coatings failure are provided in Section2.2.10. For each of the unqualified

coatings, the total quantity is multiplied by the failure fraction (100%)to determine the actual quantity of unqualified coatings debris generated.

The quantity of unqualified coatings debris that transports to the strainers (as well as the arrival time at the strainers) is dependent on both the failure location and failure timing. Therefore, these inputs were provided in Section 2.2.10also. The following equations illustrate the method for calculating the time-dependent and cumulative coatings failure:Mii(t) = Mtotai,ij "F .il,i" F(t) Equation 27Mij W)Mii'cum -M total,i ' Ffail,i Equation 28where:M(t) = Mass of unqualified coatings that fail during a specific time periodt = Specific time period following the start of the accidentSubscript i = Unqualified coating type (epoxy, IOZ, alkyd, or baked enamel)Subscript j = Coating location (upper containment, lower containment, or reactor cavity)Mtotal = Total mass of unqualified coatingsFfail = Total failure fractionF(t) = Fraction of coatings that fail during a specific time periodMij,cum = Cumulative mass of unqualified coatings that failAlthough the failure fraction could realistically range from 0% to 100% for the various types of coatings, the failure fraction implemented in CASA was conservatively set at 100% for all unqualified coatings.

Asdescribed in Section 5.5.7, however, the transport fractions for unqualified coatings take intoconsideration the coatings location and the failure timing (e.g., unqualified coatings that fail in uppercontainment after containment sprays are secured would not be washed down). Since sprays aresecured prior to 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months (see Section 2.2.1), the quantity of coatings that fail prior to securing sprayswould be 6% or less (see Section 2.2.10).

Therefore, a washdown transport fraction of 6% was used forunqualified coatings in upper containment.

All of the unqualified coatings that were calculated toPage 157 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2transport to the strainer over a total of 30 days were conservatively introduced to the pool at a uniformrate starting at 10 minutes and ending at 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months (i.e., approximately 2.8% per hour).5.4.6 Latent DebrisThe quantities of latent fiber and latent dirt/dust were entered as input parameters in CASA Grandebased on the values specified in Section 2.2.12. The total quantity of latent debris is applicable to allLOCA scenarios.

5.4.7 Miscellaneous DebrisUnqualified tags, labels, plastic signs, tie wraps, etc. are assumed to fail for all LOCA scenarios.

The totalquantity of miscellaneous debris was entered as an input parameter in CASA Grande based on the valuespecified in Section 2.2.13.5.4.8 Debris Characteristics The important debris properties were entered as input parameters in CASA Grande based on the valuesspecified in Section 2.2.16. The parameters that are important for GSI-191 calculations include thecharacteristic diameters of particles and fibers, the macroscopic (or bulk) density of debris, and themicroscopic (or particle) density of debris.5.5 Debris Transport Debris transport is the estimation of the fraction of debris that is transported from the location where itis generated to the sump strainers.

The four major debris transport modes are:* Blowdown transport-the vertical and horizontal transport of debris to all areas of containment by the break jet." Washdown transport-the vertical (downward) transport of debris by the containment spraysand break flow.* Pool fill transport-the horizontal transport of debris during the RWST injection phase to regionsof the pool that may be active or inactive during recirculation.

Recirculation transport-the horizontal transport of debris from the active portions of therecirculation pool to the sump strainers.

The four transport modes, potential upstream

blockage, fiberglass debris erosion, and time-dependent transport are all discussed in this section.5.5.1 Upstream BlockagePotential upstream blockage points at STP include the four 30-inch vent holes in the secondary shieldwall (see Figure 5.2.7 and Figure 5.5.1) and the two 6-inch refueling canal drain lines. These potential Page 158 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2blockage points were previously evaluated as part of the deterministic GSI-191 analysis, and it wasshown that they would not be clogged with debris (65; 76).Figure 5.5.1 -Photograph of 30-inch vent hole in secondary shield wall5.5.2 Blowdown Transport The blowdown transport fractions are provided in Section 2.2.17. As described in Assumption 6.h, thebounding, large break, steam generator compartment blowdown fractions were used for all breaks.These values are shown below in Table 5.5.1.Table 5.5.1 -Blowdown transport fractions used in CASA GrandeBlowdown Transport Fractions Debris Type Upper Upper Remaining inContainment Containment Compartments Fines 70% 30% 0%Small LDFG 60% 25% 15%Large LDFG 22% 0% 78%Page 159 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 25.5.3 Washdown Transport The washdown transport fractions are provided in Section 2.2.18. As described in Assumption 6.h, thebounding washdown transport fractions (assuming sprays are always initiated) were used for all breaks.These values are shown below in Table 5.5.2.Table 5.5.2 -Washdown transport fractions used in CASA GrandeWashdown Transport Fractions Debris Type Washed Down in Washed Down insideAnnulus Secondary Shield WallFines 47% 53%Small LDFG 19% 27%Large LDFG 0% 0%5.5.4 Pool Fill Transport The pool fill transport fractions are provided in Section 2.2.19. As described in Assumption 6.h, the poolfill transport fractions for breaks inside the secondary shield wall were used for all breaks. These valuesare shown below in Table 5.5.3.Table 5.5.3 -Pool fill transport fractions used in CASA GrandePool Fill Transport Fractions Each Sump Inactive CavitiesFines 2% 5%Small LDFG 0% 0%I Large LDFG 0% 0%5.5.5 Recirculation Transport The recirculation transport fractions are provided in Section 2.2.20. As described in Assumption 6.h, thebounding, large break, steam generator compartment recirculation fractions were used for all breaks.These values are shown below in Table 5.5.4.Page 160 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 5.5.4 -Recirculation transport fractions used in CASA GrandeRecirculation Transport Fractions Debris Type Size Debris in Washed in Washed insideLower Annulus Secondary Containment Shield WallFines 100% 100% 100%LDFG Small Pieces 64% 58% 64%Large Pieces 0% NA NAQualified Coatings Fines 100% 100% 100%Unqualified Coatings20 Fines 100%Fine Chips 41%Unqualified Epoxy20 Small Chips 0%Large Chips 0%Curled Chips 100%Crud Fines 100% 100% 100%Dirt/Dust Fines 100% 100% 100%Latent Fiber Fines 100% 100% 100%5.5.6 Debris ErosionPieces of fiberglass debris that are held up on grating and exposed to spray, and pieces of fiberglass debris that settle in the recirculation pool would be subject to erosion.

The erosion fractions aredescribed in Section 2.2.21.5.5.7 Strainer Transport The total transport to the ECCS strainers was determined based on the logic tree method described inNEI 04-07 (44). The transport fractions can be calculated using Equation 29 for debris generated insidethe ZOI, Equation 30 for unqualified coatings debris generated outside the ZOI, and Equation 31 forlatent debris.20 The recirculation transport is assumed to be the same for unqualified coatings washed down to the pool andunqualified coatings that are initially in lower containment since the locations where debris would be washeddown and the locations where unqualified coatings exist in lower containment are spread out and can bereasonably treated as a uniform distribution (23).Page 161 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2DTFzo, FBD(upper)

F (D -- FWD(inside)

-FWD(annutus))

' FErosion?(spray)

+ FWD(inside)

[FRecirc(WDinside)

+ (1 -FRecirc(WDinside))*

FErosion(poot)]

+ FWD(annulus)

, [FRecirc(WDannulus)

+ (1 -FRecirc(WDannulus))"

FErosion(pool)]}

+ (1 -FBD(upper)

-FBD(lower))

, f(1 -FWD(BCinside)

-FWD(BCannulus)).

FErosion(spray)

+ FWD(BCinside)

, [FRecirc(WDinside)

+ (1 -FRecirc(WDinside))"

FErosion(pooj)]

+ FWD(BCannulus)

, [FRecirc(WDannulus)

+ (1 -FRecirc(WDannulus))"

FErosion(pool)]}

+ FBD(lower) t t(1 -3" FPF(sump)

-FpF(inactive))

[FRecirc(lower)

+ (1 -FRecirc(lower))"

FErosion(pool)]

+ Nsumps" FpF(sump)}

where:Equation 29DTFzoI = Total debris transport fraction (for particular type/size of debris generated in the ZOI)FBD(upper)

= Blowdown fraction to upper containment FBD(Iower)

= Blowdown fraction to lower containment FwD(inside)

= Washdown fraction inside secondary shield wallFWD(annulus)

= Washdown fraction in annulusFWD(BCinside)

= Washdown fraction from break compartment to inside secondary shield wallFWD(BCannuIus)

= Washdown fraction from break compartment to annulusFPF(sump)

= Pool fill fraction to each sump strainerFpF(inactive)

= Pool fill fraction to inactive cavitiesNsumps = Number of ECCS sumps in operation during recirculation FReirc(Iower)

= Recirculation fraction for debris initially blown to lower containment FRecirc(WDinside)

= Recirculation fraction for debris washed down inside secondary shield wallFReirc(WDannuIus)

= Recirculation fraction for debris washed down in annulusFfrosion(spray)

= Erosion fraction for debris held up above the poolFErosion(pool)

= Erosion fraction for non-transporting debris in the poolDTFuc = Fyail " [Fupper -Fspray FRecirc + Flower " FRecirc + Freactor' FRecirc(reactor)]

Equation 30Page 162 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2where:DTFuc = Total debris transport fraction (for particular type/size of unqualified coatings debris)Ffail = Total failure fractionFupper = Fraction located in upper containment Flower= Fraction located in lower containment Freactor

= Fraction located in the reactor cavityFspray = Fraction of coatings that would fail prior to securing containment spraysFReerc = Recirculation fraction for debris washed to or initially in lower containment FRecirc(reactor)

= Recirculation fraction for debris in reactor cavityDTFLD = FUpper* FWD " FRecirc + Flower* [(i -3 "FPF(sump)

-FPF(inactive))

"Fnecirc

+ Nsumps Equation 31*FpF(sump)]

where:DTFLD = Total debris transport fraction (for particular type/size of latent debris)Fupper = Fraction located in upper containment Flower= Fraction located in lower containment FWD = Total washdown fractionFPF(Sump)

= Pool fill fraction to each sump strainerFPF(inactive)

= Pool fill fraction to inactive cavitiesN5umps = Number of ECCS sumps in operation during recirculation FRecirc = Recirculation fraction for debris washed to or initially in lower containment Figure 5.5.2 through Figure 5.5.7 show the transport logic trees for each type and size of debrisgenerated inside the ZOI for a large break in the steam generator compartments.

The washdowntransport fractions are based on the actuation of containment sprays (i.e., CS flow is greater than 0gpm), and the pool fill transport fractions are based on all three sumps being active (i.e., at least onepump is running on three different trains).Page 163 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Bodw ahonRecirculatin Eoion Fraction oif DebrisBlowdown, Washdown oo Fil raspr

..Debris Size Transport Transport Pool Fill Transport Transport Erosion at Sump0.00Retained onStructures 1.00 0.3710.70 0.53 Transport Upper Washed Down 0.00Containment Inside Secondary SedimentShield Wall1.00 0.3290.47 Transport Washed Down in 0.00Annulus SedimentLDFG 0.00(Fines) SG Compartments 1.00 0.2670.80 Transport Active Pool 0.00Sediment0.06 0.0180.30 Active Sump(s)LowerContainment 0.00Inactive Sump(s)0.05Inactive CavitiesSum: 0.985Figure 5.5.2 -Logic tree for LDFG fines showing total transport fraction implemented for all breaksPage 164 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Debris Siz Blowdown Washdown PolFgTasot Redarclation Eoin Fraction of DebrisI Transport I rnport I I Trasot II at Suimp I0.010.0030.54I Erodes to Fines.... IRetained onfStructures 0.27I 0.99Remains Intact0.640.104I Transport 0.60UpperContainment Washed DownInside Secondary Shield Wan0.070.36 Erodes to FinesSediment 0.93Remains Intact0.0040.580.066I Transport 0.19Irnnf7Washed Down inAnnulus0.A2 Erodes to FinesSediment 0.93Remains Intact0.010.0030.0010.73LD7G_Retained onStructures 0.15SG Compartments 0.217troaes to 1tmes0.99Remains Intact0.640.026Transport 9I n7Washed DownInside Secondary Shield Wall0.36 Erodes to FinesSediment 0.93Remains Intact0.640.0010.160iransport 1.00Active Pool 0.070.36 Erodes to FinesSediment 0.93Remains Intact0.000.006flt'tt0.250 .00 -Containment Active sump~s)0.00Inactive Sump(s)0.00Inactive CavitiesSum:O.374 Figure 5.5.3 -Logic tree for LDFG small pieces showing total transport fraction implemented for allbreaksPage 165 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Debris size DBowdown Washdown Recrculation Ders ie I rnpot I Transport I Pool Fill Transport I erua~Tianpr Ii Fraction of DebrisIrs~ at Sum p0.010.0021.00Retained on0.22 Structures UpperContainment

0.0 0LowerContainment

Erodes to Fines0.99Remains Intact0.010.0081.00LOFG(Large Pieces)Retained on0.78 Structures SG Compartment

0.0 0LowerContainment

0.00LowerContainment Erodes to Fines0.99Remains IntactSum: 0.010Figure 5.5.4 -Logic tree for LDFG large pieces showing total transport fraction implemented for allbreaksDebrisw Waizeow Re illTranaErsio Fractio of DebrisDerius Size Transport Transpo atPoo Transpot Ero at Sumnp0.0.Retained anStructures 1.00 0L3710.70 O.53 TrawsporUpper _Washed Down 0.00Contairmene Insie Secondaiv SediCime1.000.47 Traosperl W e Down i 0.00LAM e ft ltlmentMlcbr 0.ek1.00 0.2670.89 Transport AI'ePM 0.0Sediment0.30 Active Surnp(s)Contaliment 0.MInactiv Sump(s).OMInac"kM Cawties,sum: 0LIMFigure 5.5.5 -Logic tree for Microtherm fines showing total transport fraction implemented for allbreaksPage 166 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Blowdown Washdown Recirculation Fraction of DebrisDebris Size Transport I Transport Pool Fill Transport Transport I Erosion at Sump0.00Retained onStructures 1.000.371n_7o0.53Transport 070 .------UpperContainment Washed DownInside Secondary Shield Wall0.00Sediment1.000.3290.47Washed Down inAnnulusTransport 0.00SedimentCrud 0.00(Fines) S6 Compartments 1.000.2670.89 Transport Active Pool 0.00Sediment0.060.0180.30LowerContainment Active Sump(s)0.00Inactive Sump(s)0.05Inactive CavitiesSum: 0.905Figure 5.5.6 -Logic tree for crud fines showing total transport fraction implemented for all breaksPage 167 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2i Blwdown Washdown Recirculation Erso Fraction of DebrisDebris Size Transport Transport Transport at Sump0.00Retained onStructures 1.00 0.3710.70 0.53 Transport Upper Washed Down 0.00Containment Inside Secondary SedimentShield Wall1.00 0.3290o47 Transport Washed Down in 0.00Annulus SedimentQualified Coatings 0.00(Fines) SG Compartments 1.00 0.2670.09 Transport Active p wa 0.00Sediment0.00.013 0.010Lower Active Sump(s)containment 0.100Inactive Sump(s)0.05Inactive cavitiesSum: 0.985Figure 5.5.7 -Logic tree for qualified coatings fines showing total transport fraction implemented for allbreaksFigure 5.5.8 through Figure 5.5.15 show transport logic trees for each type and size of debris generated outside the ZOI for a large break in the steam generator compartments.

The transport fraction for theunqualified coatings is based on a failure fraction of 100%, as well as the failure timing for the coatingsin upper containment.

Since the majority of unqualified coatings would fail after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months (approximately 94% as shown in Section 2.2.10),

and the sprays would generally be secured within a fewhours, most of the unqualified coatings in upper containment would not be washed down to the pool.Page 168 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Fracto In Locon Washdown PRerculation Fraction of DebrisI I I I Transport I I Transport I at Sump1.000.0320.06Fails Prior to0.54 Securing SpraysUpperContainment 0.94Fails AfterSecuring SpraysTransport 0.00Sediment1.001.00FailsUnqualfied ANkydCoatings(Fines)0.00Remains Intact0.460046LowerContainment Transport 0.00Sediment0.00Reactor CavitySum: 0.492Figure 5.5.8 -Logic tree for unqualified alkyd coatings fines showing total transport fractionimplemented for all breaksDebris Size Failure Fraction Initial Location Transport Pool Fill Transport Transport at Sump1.00 0.0090.06 Transport t Fails Prior to o.9000.15 Securing Sprays SedimentUpperContainment 0.94Falls AfterSecuring Sprays1.00 1.00 0.020Fails 0.02 Transport Lower 0000Containment SdmnUnqualified EpoxyCoatings 0.00 0.a00(Fines) 0.83 Transport Reactor Cavity _41.00Sediment0.00Remains IntactSum: 0.029Figure 5.5.9 -Logic tree for unqualified epoxy coatings fines showing total transport fractionimplemented for all breaksPage 169 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2i I i Washdown Rerculation Fraction o DebDebris Size Faiure Fraction Initial Location Transport Pool Fil Transport Transport at Sump0.01 0.0040.06 I Transport Fails Prior to 0.590.1 Securing Sprays SedimentConSu 1 0.94Faiis AfterSecuring Sprays1.00 0.41 0.008Falls u.02 ] Transport Lower] 0.59Containment SedimentUnqualified EpoxyCoatings 0.00 0.000(Fine Chips) 0.83 Transport Reactor CavityI 1.00Sediment1 0.00Remains IntactSum: 0.012Figure 5.5.10 -Logic tree for unqualified epoxy coatings fine chips showing total transport fractionimplemented for all breaksDebris Size Failure Fraction Initial Location Transport Pool Fill Transport Recrcuatinsportactio ofumpri0.00 0.0000.06 { Transport Fails Prior to 1.000.15 Securing Sprays SedimentUpperContanentý 0.94Fails AfterSecuring Sprays1.00 0.00 0.0ooFails 0.02 ] Transport Lower1 1.00Containment SedimentUnqualified EpoxyCoatings 0.00 0.000( Small Chips) 0.83 Transport Reactor CavityJ 1.00Sediment0.00Remains IntactSum: 0.000Figure 5.5.11 -Logic tree for unqualified epoxy coatings small chips showing total transport fractionimplemented for all breaksPage 170 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Debris Size Failure Fraction Initi a t ranspor Pool Fil Transport I Recirculation Fraction of DebrisI I I Transport I I Transport I at Sump I0.000.0000.06I Transport

-4Fails Prior to0.15 Securing SpraysUpperContainment 0.94Fails AfterSecuring Sprays1.00Sediment0.000.0001.00Fails0.02Fails Transport LowerContainment 1.00Sediment0.00Unqualified EpoxyCoatings(Large Chips)0.0000.830.3Transport Reactor Cavity1.00Sediment0.00Remains IntactSum: 0.000Figure 5.5.12 -Logic tree for unqualified epoxy coatings large chips showing total transport fractionimplemented for all breaksDebrisWasdo Recirculation Fraction of DebrisI I I I Transport P F Transport at Sump1.000.0091.00 0.0090.06Fails Prior to0.15 Securing SpraysUpperContainment 0.94Fails AfterSecuring SpraysTransport 0.00Sediment1.000.0201.00Fails0.02LowerContainment Transport 0.00Sediment0.00Unqualified EpoxyCoatings(Curled Chips)0.0000.83Reactor CavityTransport 1.00Sediment0.00Remains IntactSum 0.029Figure 5.5.13 -Logic tree for unqualified epoxy coatings curled chips showing total transport fractionimplemented for all breaksPage 171 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Trnsore °°iFiaTrnsIrWashdown Recirculation Fraction of DebisDebris Size i Fraction Location I Transport Pool Fl Transport Transport I at Sump I0.0501.000.06Fails Prior to0.83 Securing SpraysUpperContainment 0.94Falls AfterSecuring SpraysTransport 0.00Sediment1.00FailsUnquaified IOZCoating's (Fines)1 0.00Remains Intact1.000.1700.17LowerContainment 0.00Reactor Cavityiransport 0.00SedimentSum: 0.220Figure 5.5.14 -Logic tree for unqualified IOZ coatings fines showing total transport fractionimplemented for all breaksDersSie krocto asispor PolFllT Rccuiition Erosion Fraction of neriTranspor Transpt atpUpper1110 0.89LaFent 5. ois tOwn Transport A Fised) Active Pooe 0.s 0Sedimerlt 1 .00.)6 0.060t es an ActfT Sump(s)Contaainme3 2.bodwei Sump(s)0115InaUtlue cawftiesSurm: ngoFigure 5.5.15 -Logic tree for latent fines showing total transport fraction implemented for all breaksAs discussed in Assumption 6.e, debris accumulation on the strainers is assumed to be proportional tothe strainer flow split. Therefore, the debris accumulation on each individual strainer can be calculated as shown in Equation 32.DTFsump(x)

= DTF QSUMP(X)Qsump(A)

+ QSump(B)

+ Qsump(c)Equation 32where:DTFsump(x)

= Recirculation transport to Sump(X) for a particular type/size of debris in poolPage 172 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Sump(X) = Sump(A),

Sump(B),

or Sump(C)DTF = Recirculation transport for a particular type/size of debris in poolQsump(x)

= Flow rate to Sump(X)QSumP(ABC)

= Flow rate to Sump(A,B,C)

If all pumps are operating at the same flow rate in all three trains, 33.3% of the transported debriswould accumulate on each strainer.

However, if the pumps in two trains failed, 100% of the transported debris would accumulate on the active strainer.

5.5.8 Time-Dependent Debris Arrival ModelThere are several factors that must be taken into consideration to analyze time-dependent arrival ofdebris at the strainers or in the core. These factors were addressed in the debris transport calculation assummarized in Table 5.5.5 and illustrated in Figure 5.5.16 (23).Table 5.5.5 -Time-dependent transport Source Time or Equation Commentst = -0 s (no curbs around inactive Assume only applies for debris blowncavity entrances) to pool and latent debrist ~425 s (based on a flow rate oft -425s (ase ona fow ateof Assume only applies to debris blownSump Strainer Fill 14,040 gpm and a pool volume of Au ol appliest debris13,325 ft3) to pool and latent debrisTotal Fill (Switchover) t -20 min (LBLOCA)Assume washdown occurs afterInitial Washdown 6 s -1000 s (fines);

inactive and sump cavities are filled,2 min -50 mi (small pieces) but before recirculation is initiated Unqualified Coatings Conservatively introduced at aFailure 0 min -30 days constant rate from 10 minutes to 36hoursRecirculated Spray FlowDebrislashd t -300s Assume instant washdownDebris WashdownRecirculated Break FlowDebrislashd t < 300s Assume instant washdownDebris WashdownSpray Erosion Washdown t < 15 min Assume during pool fillPool Erosion Recirculation 0-30 days Assume during pool fillTotal debris in pool from blowdownInitial Debris in Pool at xi = blowdown

+ initial washdown and initial washdown minus the debrisstart of recirculation (xi) -pool fill transported to inactive cavities or thestrainer during pool fillDebris Recirculation Time Based on arrival time, flow rate, poolNO) Described in Section 5.8 volume, debris penetration, and core(x__t))_bypass.

Page 173 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Debris Circumlated ThroughSpray Nozzlesz FoorUnqualified DebrisOn Corecoatings 0Debris irculed ThroughReactor VessalDebrisEroded OffTrapped Fiberglass Debris in Upper Containment Transported by SpraysDebris Debris on StoanerWashed to PoolPenetrated DebrisDebris Eroded off Non- Xtransporting Pie ofFiberglass Figure 5.5.16 -Illustration of time-dependent transport 5.6 Strainer Head LossOverall head loss across the strainer includes the clean strainer head loss as well as the debris bed headloss from both conventional debris (fiber, particulate, RMI, paint chips, etc.) and chemical precipitates.

Ifthe strainer head loss exceeds the NPSH margin of the pumps, the pumps would fail. Similarly, if thehead loss exceeds the structural margin of the strainers, the strainers would fail potentially allowinglarge quantities of debris to be ingested into the ECCS.5.6.1 Clean Strainer Head LossAs described in Section 2.2.23, a constant clean strainer head loss value of 0.220 ft was used in CASA.This is the maximum clean strainer head loss that was measured for an equivalent approach velocity ofPage 174 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 20.013 ft/s. Note that the maximum strainer approach velocity at STP is 0.0086 ft/s based on a maximumflow rate of 7,020 gpm (see Section 2.2.8) and a strainer area of 1,818.5 ft2 (see Section 2.2.22).5.6.2 Conventional Debris Head Loss ModelThe NUREG/CR-6224 correlation was selected for the CASA computation of conventional debris headloss21 across the strainer.

This correlation is a semi-theoretical head loss model and is described in detailin Appendix B of NUREG/CR-6224 (70). The correlation is based on theoretical and experimental research for head loss across a variety of porous and fibrous media carried out since the 1940s. TheNUREG/CR-6224 head loss correlation was developed in support of the NRC evaluation of the strainerclogging issue in BWRs and has been extensively validated for a variety of flow conditions, watertemperatures, experimental facilities, types and quantities of fibrous insulation debris, and types andquantities of particulate matter debris. The types of fibrous insulation material tested include Nukon,Temp-Mat, and mineral wool. The particulate matter debris tested includes iron oxide particles from 1to 300 Itm in characteristic size, inorganic zinc, and paint chips. In all of these cases, the NUREG/CR-6224 head loss correlation has bounded the experimental results.

Due to the semi-empirical nature of thecorrelation STP performed confirmatory head loss tests to demonstrate the applicability of thecorrelation to STP conditions (24).NUREG/CR-6224 Head Loss Correlation The NUREG/CR-6224 head loss correlation, applicable for laminar, turbulent, and mixed flow regimesthrough mixed debris beds (i.e., debris beds composed of fibrous and particulate matter) is given byEquation 33:[ 2 5 am 21]~ quto3AH = A 3.5S, 2 am1'(1 + 57a 13)1tU + 0.66S,- pUi ALM Equation 33where:AH = Head lossS= Surface to volume ratio of the debrist= Dynamic viscosity of waterU = Fluid approach velocityp = Density of wateram = Mixed debris bed solidity (one minus the porosity)

ALm = Actual mixed debris bed thickness A = Conversion factor:21 The term "conventional debris head loss" is used to distinguish between the debris bed head loss caused bytypical fiber and particulate debris vs. the head loss caused by chemical effects.Page 175 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2A = i for SI unitsA = 4.1528x10s (ft-water/in)/(Ibm/ft 2-s2) for English unitsThe fluid approach

velocity, U, is given simply in terms of the volumetric flow rate and the effective surface area:U Q -Equation 34Awhere:Q = Total volumetric flow rate through the screenA = Screen surface areaThe screen surface area (A) is the submerged (wetted) surface area of the screen. The available surfacearea may change with time, particularly in the case of the STP strainer design. As more debris reachesthe strainer the surface area may eventually evolve to the circumscribed area as the debris starts to fillup the interstitial volume. If the debris load is sufficient to fill the entire interstitial volume, the head lossfor the STP strainer is calculated using the circumscribed area with a debris load equal to the total debrisload transported to the strainer less the quantity of debris required to fill in the interstitial volume of thestrainer.

The mixed debris bed solidity (ctm) is given by:(Cam +'fi r/ a- Equation 35Pp! Cowhere:a,= Solidity of the original fiber blanket (i.e., the "as fabricated" solidity)

T= Particulate to fiber mass ratio in the debris bed (mp/mf)pf= Fiber densitypp= Average particulate material densityc = Actual packing bed density corresponding to a pressure gradient of AH/AL,c. = Reference packing density or theoretical packing densityFor debris deposition on a flat surface of a constant size, the compression (c) relates the actual debrisbed thickness (ALm) and the theoretical fibrous debris bed thickness (ALo) via the relation:

Page 176 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2AL0c = co ALm Equation 36Compression of the fibrous bed due to the pressure gradient across the bed is also taken intoconsideration.

The relation that accounts for this effect, which must be satisfied in parallel to theprevious equation for the head loss, is given by the following equation valid for (AH/ALo)

> 0.5 ft-water/inch-insulation:

c =1.3 Equation 37It should be noted that this formulation for debris bed compression may over predict compression significantly in the case of very thick debris layers (roughly 6-inches or more). Thus, in these cases, it isconservative.

For very large pressure gradients, the compression has to be limited such that a maximum solidity is notexceeded.

In NUREG/CR-6224, this maximum solidity is defined to be:65 Ibm/ft3am -Equation 38PpThis is equivalent to having a debris layer with a density of 65 lb ft3.Note that 65 IbJft3 is themacroscopic, or bulk density of a granular media such as sand or gravel and clay.Each debris constituent has a surface-to-volume ratio based on the characteristic shape of that debristype. For typical debris types, this includes:

Cylindrically-shaped debris: S, = 4/diamSpherically-shaped debris: S, = 6/diamFlakes (flat-plates):

S, = 2/thickwhere:'diam' = Diameter of the fiber or spherical

particle, and'thick' = Thickness of the flake/chip.

The average surface to volume ratio for several debris constituents was calculated in CASA Grande usingthe following equation:

Page 177 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 24 M.) Equation 39where the subscript

'n' refers to the nth constituent, and mn is the mass of each constituent.

Linear massweighting was used because CASA Grande tracks the mass of each debris constituent in the pool, andthe individual proportion of Sv contribution to the composite depends on the quantity of eachconstituent that is present in the bed at any point in time. Many alternative composite weighting schemes could be considered including some based on volume fractions rather than mass fractions thatincorporate geometric weighting like the square-root of the sum of squared contributions.

Note thatusing a mass-weighted averaging to calculate the surface to volume ratio deviates from the guidance inNEI 04-07 Volume 2 Appendix V, which specifies a volumetric-weighted averaging (45). Also note thatperforming the averaging using a linear term rather than a squared term results in a lower Sv value (45).Debris Parameters Required for Head Loss Calculations The NUREG/CR-6224 head loss correlation requires the following debris parameters:

Microscopic

density, also referred to as "material" density* Macroscopic

density, also referred to as "bulk" density* Characteristic size, which is the dimension to be used in computing the surface to volume ratio(i.e., diameter for fibers and particulates, and thickness for chips)Table 5.6.1 and Table 5.6.2 show the parameter values that were used for the head loss calculations inCASA Grande. These parameters are largely based on the debris characteristics provided in Section2.2.16. However, there were some modifications to some of the values:* As described in Assumption 1.f, the small and large pieces of Nukon were treated the same asthe fiber fines (i.e., 7 micron diameter with an S of 571,429 m1).* As described in Assumption 1.d, Thermal-Wrap LDFG was assumed to be identical to NukonLDFG (i.e., 7 micron diameter, 175 Ibm/ft3 microscopic

density, and 2.4 Ibm/ft3 macroscopic density).

" Since the Microtherm debris would fail as fines, the density of the Microtherm fiber thataccumulates on the strainer would be essentially the same as the density of the other fiberglass fines (i.e., 2.4 lbm/ft3).* A crud diameter of 15 grm was used to represent the size range of 8 to 63 grm. This diameter onthe conservatively low end of the range.* An unqualified coatings diameter of 10 pm was used to represent the size range of 4 to 20 4mfor unqualified alkyd, enamel and IOZ coatings.

This diameter is on the conservatively low end ofthe range.* A crud density of 350 Ibrm/ft3 was used to represent the density range of 325 to 556 IbM/ft3.Thisdensity is on the conservatively low end of the range.Page 178 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Table 5.6.1 -Head loss characteristics for fibrous debrisDebris Type Size Geometry Size S, Microscopic Macroscopic (m2/m3) Density Density(lbm/ft3) (Ibm/ft3)Fines cylinder 7 microns 571,429 175 2.4LDFG Small Pieces cylinder 7 microns 571,429 175 2.4Large Pieces cylinder 7 microns 571,429 175 2.4Microtherm Fiber Fines cylinder 6 microns 666,667 165 2.4Latent Fiber Fines cylinder 7 microns 571,429 175 2.4Table 5.6.2 -Head loss characteristics for non-fibrous debrisDebris Type Size Geometry Size S, Microscopic Macroscopic (m2/m3) Density Density(lbm/ft3) (lbm/ft3)Microtherm TiO2 Fines sphere 20 microns 300,000 262 52.4022Microtherm Si02 Fines sphere 2.5 microns 2,400,000 137 27.4022Qualified Epoxy Fines sphere 10 microns 600,000 94 36.66123Qualified EOZ Fines sphere 10 microns 600,000 208 81.1263Crud Fines sphere 15 microns 400,000 350 70.0022Fines sphere 152 microns 39,474 124 48.3623Fine Chips chip24 15 mil thick 5,249 124 48.3623Unqualified Epoxy Small Chips chip24 15 mil thick 5,249 124 48.3623Large Chips chip24 15 mil thick 5,249 124 48.3623Curled Chips chip24 15 mil thick 5,249 124 48.3623Unqualified Alkyd Fines sphere 10 microns 600,000 207 80.7323Unqualified Enamel Fines sphere 10 microns 600,000 93 36.2723Unqualified IOZ Fines sphere 10 microns 600,000 244 95.1623Latent Dirt/Dust Fines sphere 17.3 microns 346,821 169 33.8022Geometric Strainer LoadingCompact strainer designs like the PCI stacked plate modules used at STP are designed to maximize thesurface area available to accommodate a debris load while minimizing the containment floor spacetaken up by the strainer manifold.

The large surface area is intended to distribute total suction flow sothat the face velocity of water entering the strainer is very low. For large volumes of fibrous debris, theinterstitial gaps between strainer plates can load with debris, the effective surface area of a strainer22 Calculated based on a packing fraction of 0.20 for iron oxide sludge (70). See Assumption 7.b.23 Calculated based on packing fraction of 0.39 for acrylic coatings debris (24). See Assumption 7.b.24 Since CASA Grande does not include an S, calculation for chips, the chip debris was treated as particles with aspherical diameter of 1,143 microns, which provides an equivalent Sv value as a 15 mil thick chip.Page 179 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2module transitions to a circumscribed shape, and the velocity of water entering the debris bed increases causing additional head loss.To emulate geometric loading on the STP strainers and conservatively approximate potential increased approach

velocity, a table was constructed to relate fibrous debris volume with idealized bed thickness and circumscribed surface area. The approximation treats each STP strainer train as a rectangular boxwith a clean strainer area, A0, of 1,818.5 ft2 (see Section 2.2.22).

When the strainer is loaded with aperfectly uniform thickness of 0.5 in., interstitial gaps are full and total flow must cross thecircumscribed area. At this thickness the strainer bed is assumed to have the following dimensions (seeSection 2.2.22):* x = 0.5 in (debris thickness)

A = 419 ft2 (debris area)* V = 81.8 ft3 (debris volume)* H = 26 in (loaded strainer height with a half inch of debris on the top and bottom of the strainer)

W = 29 in (loaded strainer width with a half inch of debris on each side)* L = 44.6 ft (loaded strainer length)26 in. J44.6 ft29 in.Figure 5.6.1 -Circumscribed strainer dimensions While debris continues to load on all faces, incremental bed thickness and bed area can be calculated using the following equations for an incremental volume of debris, AV:AVAx = Equation 402 (HW + HL + WL)A = 2[(H + 2Ax)(W + 2Ax) + (H + 2Ax)(L + 2Ax) + (W + 2Ax)(L + 2Ax)] Equation 41Page 180 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2After the incremental thickness exceeds 2 inches, the bottom surface of the strainer is assumed tobecome inaccessible to further debris loading and the incremental bed thickness and bed area obey thefollowing formulas for an incremental volume of debris, AV:A = AVA 2H(W + L) + WLEquation 42Equation 43A = 2(H + Ax)(W + 2Ax) + 2(H + Ax)(L + 2Ax) + (W + 2Ax)(L + 2Ax)Incremental thickness is then always added to the initial fully loaded thickness of 0.5 inches. It isassumed that pool depth is always sufficient to permit additional debris loading on the top surface.The loading formulas were evaluated for a wide range of debris volumes to produce the following tablethat was used in CASA to interpolate bed thickness and area for any time-dependent debris volume.Table 5.6.3 -Strainer loading tableVolume Thickness Area(ft3) (in) (ft2)0 0 1,818.581.790 0.5000 419.0081.800 0.5010 419.31280.16 8.1421 447.18478.53 15.783 592.56676.89 23.424 747.68875.26 31.065 912.531,073.6 38.706 1,087.11,272.0 46.348 1,271.41,470.3 53.989 1,465.51,668.7 61.630 1,669.21,867.1 69.271 1,882.72,065.4 76.912 2,106.02,263.8 84.553 2,338.92,462.2 92.194 2,581.62,660.5 99.835 2,834.12,858.9 107.48 3,096.23,057.3 115.12 3,368.13,255.6 122.76 3,649.73,454.0 130.40 3,941.13,652.4 138.04 4,242.23,850.7 145.68 4,553.04,049.1 153.32 4,873.54,247.4 160.96 5,203.84,445.8 168.60 5,543.8Page 181 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 24,644.2 176.25 5,893.54,842.5 183.89 6,253.05,040.9 191.53 6,622.2Figure 5.6.2 illustrates the relationship between debris volume, bed thickness, and bed surface area thatis embodied in the interpolation table.Page 182 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2PCI Stacked-Plte Strainr3000 1002500 802000-60IW1500401000200 00 500 1000 1500 2000 2500Total Debris Volume (kt3)Figure 5.6.2 -Relationship between bed thickness and circumscribed surface area for idealized strainerloading of fiber debrisApplicability of the NUREG/CR-6224 Head Loss Correlation to STP Conditions I I I IThe NUREG/CR-6224 head loss correlation has been validated over a large range of approach velocities and debris types. However, there were specific STP conditions where the NUREG/CR-6224 head losscorrelation had not been compared to experimental data. In particular, experimental data did not existto evaluate the impact on the NUREG/CR-6224 head loss correlation for the following conditions:

" Low approach velocities prototypical of the STP strainers

-most of the data used to developthe NUREG/CR-6224 head loss correlation was based on tests at higher approach velocities characteristic of the small conical strainers installed in the BWRs before 1992." Buffered borated demineralized water- most of the data used to develop the NUREG/CR-6224 head loss correlation was based on tests with tap water. There were some studies donerecently that suggested that water chemistry has a significant impact on head loss (77)." Temperature

-most of the data used to develop the NUREG/CR-6224 head loss correlation was based on tests at room temperature.

" NEI fiber debris preparation

-most of the data used to develop the NUREG/CR-6224 head losscorrelation was based on tests conducted with mechanically shredded fiber debris prior to thedevelopment of the NEI debris preparation protocol.

Page 183 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2In order to ascertain the applicability of the NUREG/CR-6224 head loss correlation to STP specificconditions, a series of vertical head loss tests were performed (24). The experiments were conducted atSTP conditions including the strainer flow approach velocity of 0.0086 ft/s or less, STP-specific waterchemistry, a range of temperatures prototypical of the post-LOCA conditions, and STP-specific debrisloads.The application of a head loss correlation to head loss data requires the measurements of head loss,water temperature, and flow velocity for a relatively uniform and homogeneous fibrous/particulate debris bed of known composition at relatively stable conditions.

Turbidity measurements, as well aswater clarity, are used to judge the completeness of the filtration process.The correlation validation process depends on knowing the input hydraulic characteristics of each typeand size category of debris introduced into the test. Debris size characterization can be used toapproximate the hydraulic characteristics of simple forms of debris, such as Nukon fibers, but not forcomplex particulates.

A typical particulate consists of roughly shaped particles of varied sizes making theanalytical assessment of the surface to volume ratio, Sv, somewhat difficult and uncertain.

Someinsulation materials such as calcium silicate, Microtherm, Min-K, and amorphous chemical precipitates have complex forms that simply cannot be assessed analytically, and their impact on head loss has to beaddressed experimentally.

The solid density of a particle is based on the material properties and theparticulate bulk density can be deduced by weighing a known volume of the particulate.

The Sv value isdeduced by applying a head loss correlation to head loss test data where all parameters are knownexcept the S, value for the material in question.

As such, inaccuracies in the form of the correlation become inherent in the experimentally deduced input parameters.

Therefore, the correlation and thehydraulic characteristics become somewhat interdependent.

A total of eleven exploratory head loss tests were performed (24). All testing was done using fibers froma single-side baked Nukon blanket, which was processed using the NEI debris preparation process.

Alltesting was conducted starting at 200 °F at the STP buffered and borated water conditions.

Theparticulate types tested were green silicon carbide, iron oxide (the BWR sludge simulant used in thedevelopment of the NUREG/CR-6224 head loss correlation),

tin, and ground acrylic paint. Flow andtemperature sweeps were performed at the end of some of the experiments to examine the impact ofdifferent flow conditions and temperatures.

The NUREG/CR-6224 head loss correlation was used to replicate the measured head loss of the testconducted with iron oxide and a debris bed thickness similar to the test parameters used in thedevelopment of the NUREG/CR-6224 head loss correlation (24). The iron oxide S, value was adjusteduntil the calculated head loss matched the measured head loss. The final Sv value was in reasonable agreement with the specifications of the size distribution of the sludge simulant indicating that theNUREG/CR-6224 head loss correlation was a reasonable predictor of head losses at STP water andPage 184 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2temperature conditions.

The iron oxide test, however, was limited to the lowest approach velocity of0.02 ft/s due to equipment limitations.

The NUREG/CR-6224 head loss correlation also generated reasonable estimates of the head loss experiments conducted with ground acrylic paint and extendedthe approach velocity down to the STP strainer approach velocity of 0.0086 ft/s.The NUREG/CR-6224 head loss correlation,

however, could not replicate the low head losses observed inthe tests with tin and/or green silicon carbide.

The test report provides a hypothesis for this behaviorbased on observations of the difference in smooth surfaces noted on SEMs of green silicon carbide andtin as compared to the rough surfaces of iron oxide and ground acrylic paint (24). Further experiments need to be conducted to confirm this hypothesis.

This lack of agreement between the NUREG/CR-6224 head loss correlation and testing with green silicon carbide and tin does not impact the STP head losscalculations since there is no green silicon carbide or tin in the STP debris mixture.

The green siliconcarbide has been used in the past as a simulant of paint, and the tin has been used as a simulant of IOZcoatings.

Most of the STP particulate debris comes from coatings, either from qualified coatings in theZOI or from unqualified coatings elsewhere.

Another anomaly observed in the STP head loss tests was the absence of a direct correlation of the headlosses observed in the temperature sweeps with the water viscosity.

The test report provides ahypothesis that the temperature also impacts the compression of the fiber debris bed due to thetemperature impact on the malleability of the fibers (24). An analytical model was developed to couplethe compression to temperature that showed good agreement with the experimentally determined temperature sweep data. The compression algorithm implemented in the NUREG/CR-6224 head losscorrelation used in CASA was not modified to incorporate the temperature dependence suggested bythe tests. The experiments showed that the measured head losses at lower temperature were lowerthan the head losses calculated by the NUREG/CR-6224 head loss correlation, hence the CASA calculated head losses are conservative.

Additional experiments and analysis need to be performed to validate thetemperature dependent compression algorithm prior to its implementation in CASA.One of the tests conducted (Test 8) was designed to replicate the August 2008 ARL STP prototype test(24; 53). However, this test completely failed to replicate the head losses observed in the previoustesting.

Both tests used the same primary surrogates of Nukon fibers along with tin and acrylicparticulates.

Three differences in the tests are: 1) Test 8 had a greater thickness of fiber than wasreported in the ARL test, 2) Test 8 used Alion supplied Microtherm and Marinate board particulate instead of the same materials used at ARL, and 3) the ARL fiber debris preparation protocol used a foodprocessor whereas Test 8 used the NEI debris preparation protocol.

Based on the experience of theCHLE tests (17), fiber beds with food processor prepared fiber tended to exhibit higher head losses thanfiber beds prepared in accordance with the NEI debris preparation protocol.

Comparisons of the bedsprepared with food processor prepared debris and the NEI debris protocol revealed that the NEIprotocol fibers tended to bridge the perforated plate holes and form a debris bed over the perforated plate, while the food processor fibers tended to form low porosity "dimples" at the perforated platePage 185 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2holes. The higher head losses observed with food processor beds was attributed to the formation of thelow porosity "dimples".

The food processor prepared fibers used in the ARL test could have also formedlow porosity "dimples",

and allowed the particulate to pack tighter in the ARL test than in Test 8resulting in a lower porosity bed with higher head losses. The formation of "dimples" in the strainerholes instead of a fiber bed over the perforated plate could also explain the very thin bed observed inthe ARL test. The lack of reproducibility of the head losses observed in the Alion vertical loop testcompared with the ARL test does not impact the applicability of the NUREG/CR-6224 in calculating theCASA head losses since the differences in the results are attributable to different debris preparation methods.

The NUREG/CR-6224 head loss correlation assumes the formation of a debris bed over aperforated plate as was observed with the debris beds prepared in accordance with the NEI debrispreparation protocol.

Therefore, the NUREG/CR-6224 head loss correlation is considered to beapplicable to the debris beds formed with STP prototypical debris.The test report also addresses the impact of the three main ACRS comments of the NUREG/CR-6224 head loss correlation (24). These ACRS comments were mainly directed at debris beds containing calcium silicate, a known problematic insulation.

The test report provides suggested modifications to theNUREG/CR-6224 head correlation to address the three main ACRS concerns (24). Note that all Marinite(similar to calcium silicate) has been removed from containment at STP. Therefore, as shown in the testreport, the three main ACRS comments are not significant for STP conditions (24).Overall, these tests demonstrated that the NUREG/CR-6224 head loss correlation provided reasonable predictions of head loss (as implemented in accordance with the guidance of NEI 04-07) for theprototypical STP debris types and loads, water chemistry, temperature, and strainer approach velocities.

However, due to the generic concerns regarding the NUREG/CR-6224 correlation, the head losscalculated using the correlation was increased by a factor of five in CASA Grande to account foruncertainties in the head loss predictions.

5.6.3 Chemical Debris Head Loss ModelA predictive chemical effects evaluation model was not fully developed within this version of theanalysis.

Therefore, the specific conditions associated with each break scenario (pool volume, pooltemperature, debris quantities, etc.) could not be explicitly linked to a corresponding chemical headloss. However, a range of conditions were evaluated using the WCAP-16530-NP calculator and estimated solubility limits for expected product formation to determine a relative comparison of the quantity ofprecipitates for various break scenarios (20).For nominal temperature

profiles, chemical products (aluminum and calcium precipitates) were notpredicted to form for any of the small breaks evaluated.

However, some of the medium and large breakcases evaluated had total aluminum concentrations that were approximately equal to or slightly higherthan the estimated solubility limits (20). The calcium concentration was relatively high for cases where aPage 186 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2maximum fiberglass quantity of 2,385 ft3 was assumed.

However, for cases with 60 ft3 of fiber or less,the calcium concentration was approximately equal to the solubility limit (20). As discussed in Section5.4.3, the quantity of fiberglass insulation debris generated is less than 10 ft3 for 99.9% of the scenarios evaluated in CASA Grande. This indicates that even if chemical products form for the nominal scenarios, the effects on strainer head loss would be relatively benign. An evaluation of the chemicalconcentrations for a maximum temperature

profile, however, indicated that the concentration ofaluminum would be significantly higher (on the order of 20 times greater than the nominal scenarios).

Itis possible that these scenarios could result in significant chemical head loss. However, the maximumtemperature profiles were developed based on a highly unlikely scenario where the CCW temperature isat the maximum level, four out of six fan coolers fail to operate, and all of the RHR heat exchangers fail(5). Extreme temperature profiles like this have not been fully evaluated, so the current limited testingdoes not completely preclude the possibility that chemical products may form and arrive at a debris-laden strainer in sufficient quantity to cause unacceptable head loss.To account for the presence of extreme conditions in the scenario sample space, exponential probability distributions were defined and applied as direct multipliers to the estimated conventional head loss. Theprobability distributions were developed based on the current results from the CHLE testing (18; 19),WCAP-16530-NP calculations (20), and reasonable engineering judgment.

The chemical effects modelthat was implemented in CASA Grande is described below:* No bump-up factor is applied if the fiber quantity on a given strainer is less than 1/16 of an inch(see Assumption 7.c).* No bump-up factor is applied prior to the temperature dropping below 140 °F (see Assumption 5.a). Note that since only two temperature profiles were implemented in CASA Grande (seeSection 2.2.6), the increase in head loss would occur approximately 5 hr after the start of theevent for large breaks, and approximately 16 hr after the start of the event for small andmedium breaks." As shown in Table 5.6.4 and Figure 5.6.3 through Figure 5.6.5, the probability distributions forthe chemical effects bump-up factors were developed with mean bump-up factors ofapproximately 2x for small breaks, 3x for medium breaks, and 3x for large breaks, and maximumbump-up factors of approximately 15x for small breaks, 18x for medium breaks, and 24x forlarge breaks.The exponential probability density function is defined by a single parameter, the mean, and iscontinuous on the interval from zero to infinity.

The chemical effects bump-up factor should never beless than one, and there is a practical maximum above which all events will lead to sump failure, so thefollowing strategy was adopted.

Samples of chemical factor are taken from exponential probability density functions defined using the "formal" parameters given in Table 5.6.4. Manual iteration in a sidecalculation is used to determine a formal maximum endpoint for each formal mean above which thePage 187 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2cumulative tail probability is approximately 1E-5. Thus, the maximum chemical effects bump-up factor isalways assigned a weight of 1E-5. Sampling is performed on a logarithmic scale with an emphasis onlarge values. This means that a much higher proportion of samples are taken from the high end of therange, but each individual sample has a small probability contribution.

Finally, all samples from theformal exponential probability density functions are shifted by one unit to guarantee that the appliedfactors are never less than one.Shifting all samples by a unit of one has the somewhat unintended consequence of inflating thepotential effect of chemical products more than desired.

While the desired means are reported as"formal" parameters, the effective means applied in the quantification are actually closer to the"shifted" values given in the table.Table 5.6.4 -Exponential probability distribution parameters applied to chemical effects bump-upfactors for each LOCA categoryParameters SBLOCA MBLOCA LBLOCA Tail Probability Min 0 0 0 ~1e-5Formal Mean 1.25 1.5 2.0 ~le-5Max 14.3 17.2 23 ~le-5Min 1 1 1 ~le-5Shifted Mean 2.25 2.5 3.0 ~le-5Max 15.3 18.2 24 ~1e-5Page 188 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Chemical Head-Loss Factor for SBLOCA08-0-70.6-CL0.2~01.00 2 6 8 10 1o0.2-0~ 10 2 4 6 8 10 1216chemical elect factorFigure 5.6.3 -Exponential probability density function for chemical effects bump-up factors applied toSBLOCAsPage 189 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Chemical Head-Loss Factor for MBLOCA0.70-60-5S0-4-D-0.3CL0-20.18 10 12cherica efect factorFigure 5.6.4 -Exponential probability density function for chemical effects bump-up factors applied toM BLOCAsPage 190 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GS1191-V03 Revision 2Cherrmcal Head-Loss Factor for IBLOCAaCS-U-oES.00a-10 15chemical effect factor25Figure 5.6.5 -Exponential probability density function for chemical effects bump-up factors applied toLBLOCAs5.6.4 Strainer Head LossThe overall strainer head loss includes a combination of the clean strainer, debris bed, and chemicalhead losses as shown in the following equation:

AHs = AHcs + AHDB " BCEEquation 44where:AHs = Total strainer head loss6Hcs = Clean strainer head lossAHDB = Conventional debris bed head lossBCE = Bump-up factor for chemical effectsFigure 5.6.6 shows an example of the time-dependent head loss for random cases evaluated in CASA.Note that the head loss spikes up at approximately 5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months when the temperature drops below 140 °FPage 191 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2and chemical precipitation is assumed to occur, and then spikes back down at approximately 6.5 hour5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months swhen the containment sprays are secured.Rarndom Sample of AP History0a-.41000time (mi)Figure 5.6.6 -Typical sample of sump-strainer head loss histories generated under the assumption ofexponential chemical effects factor and artificial head-loss inflation 5.6.5 Acceptance Criterion:

NPSH Margin ModuleThe pump NPSH margin is the difference between the NPSH available and the NPSH required, as shownin Figure 5.6.7 and Equation 45 through Equation

47. Note that the NPSH margin does not include theclean strainer or debris bed head losses. Therefore, the strainer head losses are compared to the NPSHmargin to determine whether or not pump cavitation will occur due to loss of NPSH.Page 192 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.6.7 -Illustration of parameters that affect pump NPSHNPSHM = NPSHA -NPSHRPcont P~aNPSHA = + Heev Hpiping -apPg PgNPSHR(as2o%) = NPSHR(aý=O%)

x (1 + 0.5aý)Equation 45Equation 46Equation 47where:NPSHM = NPSH marginNPSHA = NPSH available NPSHR = NPSH requiredPont = Containment pressurep = Water densityPage 193 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2g = Gravitational acceleration Helev = Head of water from the pump to the surface of the poolHpiping = Head losses between the strainer and the pump (not including strainer losses)Pvap = Vapor pressureap* = Volumetric percentage of air in the fluid at the pump inlet (ap* = 100.ap)ap = Void fraction of air in the fluid at the pump inlet25As discussed in Assumption 1.c, no credit was taken for containment overpressure.

The pressure wasassumed to be 14.7 psia, except for cases where the containment pool temperature is greater than 212°F, where the containment pressure was assumed to be equal to the vapor pressure.

The water densityand vapor pressure are determined as a function of the containment pool temperature based onstandard water properties.

The head of water above the pumps is the sum of the water level above the containment floor and theelevation of the containment floor above the pumps as shown in the equation below. The water level isdetermined as discussed in Section 2.2.5. The elevation of the pumps below the containment floor isprovided in Section 2.2.24.Helev = Hpool + Hpump Equation 48where:= Water level above the containment floorHpump = Elevation of pumps below the containment floorThe piping flow losses include both major and minor losses, which are a function of cumulative andindividual pump flow rates for each train as well as the pool temperature and piping geometry.

Aschematic of the ECCS suction piping geometry at STP is shown in Figure 5.6.8. The piping flow lossescan be calculated using Equation 49 through Equation 51 (25).25 As discussed in Assumption 8J, the void fraction used in CASA was the void fraction at the strainers rather thanthe void fraction at the pump inlet.Page 194 of 248 A SumpSouth Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2CLHSIHHSIG(Z CsBDFFigure 5.6.8 -Schematic of STP ECCS sump suction pipingS2 S2 S2 +\Hpiping,LHsl

= 2.06 7 '"fAB + 0.005Tt-

+ 0.58 -" fBC / (QLHs, + QHHSI + Qcs)2+ 2.97[-s'fBC (QLHSI)2Equation 49Hpiping,HHSI

'=S2 S2 22.06+ 0.005 0.19Tg"fBDJ" (QLHs, + QHHsI + Qcs)20.09 -t-5 "fB + O.5S- -fDE ' (QHHsI + Qcs)2 + 624- [Efft +(6.24t7=t5 6.)ft(QHHSI )2Equation 50Page 195 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2S2 S2 S2 +Hpiping,cs

= 2.06-"LfAB + +0.19T " fID (QLHsI + QHHS,ts2+ O.09- fBD + O.197(QHHSI + cs)2( S2 S2 S2 )+ (.09-T'fDF

+ O.58Tt-'fFG

+ 2.957-'fFG)

(Qcs)2where:Hppng,xx

= Flow losses in piping for the LHSI, HHSI, and CS pumps respectively f,, = Friction factor for various pipe segments illustrated in Figure 5.6.8O, = Flow rate for LHSI, HHSI, and CS pumps respectively Equation 51The friction factor is dependent on the Reynolds number, and can be determined using the following equations (25; 78). Note that the implicit form of the friction factor equation in the NPSH calculation (25) was replaced with an explicit equation (78) in CASA to improve runtime.fAB 2 --2 log E-7 5.02 -A lo .2- e " log 3.7 + 13 ) ]1-137 ReAB g _ RB (3.7 D eAB13\V[AB~ =t2Ig3DA DAB~ 5.2'oD.2g(E+RAB)i Re =4" p P (QLHSI + QHHSI + Qcs)1eAB DABf B c 2 --2 lo g -.-.-ff 5 .0 2 R e c lo g D -B 5 .0 2 c lo g E-.-.-1.

D24" .-D (OD3. _s ReB4 P*B (QRBC C BReBC = p.lit", 7T* DBCfBD=t-2-log[

37 5.02 ReED 5.02 Eog 13 -2Bo)+1- 1.7-D ReBD BD ReBD (3.7 -DD + -R AEquation 52Equation 53Equation 54Equation 55Equation 56Equation 57Equation 58Equation 59ReBD = "p (QHHSI + Qcs)RD DBDE_ _ _ 5.02 E 5 .02 g + R13 E )f-2 3.7 -D ReDE (D ReoE 3.7.- D + -DE DE ~ DE eEReDE = p -DDEp" , i" DOEPage 196 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2fDF -" -2* log "3.

D TeDF log F ReDF +o -ReMI4 Eutin6ReDF -- Equation 61L .7r .DDF_ _ 5.02 e 5.02 Re13))]fF= -2"log[37D Re-- log(--- log + Equation 624 .p. (Qcs)ReFG 4- Equation 63[t , .DFGwhere:Rex. = Reynolds number for various pipe segments illustrated in Figure 5.6.8p = Water density as a function of temperature, Ibm/ft3V = Water viscosity as a function of temperature, Ibm/ft-sec

f. = Friction factor for various pipe segments illustrated in Figure 5.6.80,,, = Flow rate for LHSI, HHSI, and CS pumps respectively Du = Pipe diameter, ftE = Pipe roughness, ftThe NPSH required is a fixed value dependent on the pump specifications.

However, if gas voids arepresent (see Section 5.7), the NPSH required must be adjusted as discussed in Regulatory Guide 1.82(59).For each scenario, the time-dependent strainer head loss was compared to the time-dependent NPSHmargin to determine whether any failures occur. As discussed in Assumption 12.a, the failure of onepump in any train was assumed to be equivalent to the failure of all pumps in all trains.5.6.6 Acceptance Criterion:

Structural MarginThe strainer structural margin is 9.35 ft (see Section 2.2.25).

If the strainer head losses exceed thestructural margin, the strainer may fail allowing large quantities of debris to be ingested.

As discussed inAssumption 12.b, the structural failure of one strainer was assumed to lead to complete ECCS failure.5.7 Air Intrusion The presence of air or other gasses in the ECCS, CSS, or other systems can result in the failure of thosesystems to perform their intended safety functions.

Gas intrusion and accumulation issues have beenevaluated in response to Generic Letter 2008-01 (GL 08-01), which identifies concerns with gasPage 197 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2upstream of pumps causing potential pump failure, gas downstream of pumps causing water hammereffects when the pump is started, and other potential issues (79). Some of these issues are directlyrelated to GSI-191, since it is possible for air to enter the ECCS and CSS through vortexing ordegasification at the strainers during recirculation.

5.7.1 Vortex Formation Vortex formation can appear to be an almost random variable since it is strongly influenced by minorvariations in the local flow conditions.

However, as discussed in a series of NUREGs (80; 81; 82; 83; 84),vortex formation is somewhat related to the Froude number. In general, vortexing is dependent on thestrainer flow rate, the submergence depth, the strainer

geometry, and to some extent the containment geometry (which could either induce or inhibit swirling as the flow approaches the strainer).

Vortexing can be easily prevented with simple structures that disrupt swirling motion in the flow.ECCS strainer vortexing has been evaluated at STP, and based on the strainer design, it has beendetermined that vortexing would not occur under even under bounding conditions (56). Therefore, there would be no air ingestion due to vortexing.

5.7.2 Degasification

Under a given set of conditions (temperature,

pressure, humidity, etc.), a certain quantity of air can bedissolved in water. If these conditions change, some of the dissolved air may be released from thewater. In a LOCA scenario, some air would be dissolved in the containment pool, and as the waterpasses through the ECCS strainer, the head loss across the strainer would cause some of the air to bereleased.

The following generic properties of air and water are necessary for calculating degasification:

" The composition of air is approximately 78.08% nitrogen (N2), 20.95% oxygen (02), 0.93% argon(Ar), and 0.04% carbon dioxide (C02) with trace amounts of other gasses (85).* The critical temperature of water is 647.14'K (86)." The molecular weight of water is 18.01528, the molecular weight of nitrogen is 28.01348, themolecular weight of oxygen is 31.9988, the molecular weight of Argon is 39.948, and themolecular weight of carbon dioxide is 44.010 (86). The overall molecular weight of air isapproximately 28.97.The quantity of air released from a given volume of water across an ECCS strainer can be determined bysubtracting the concentration of air dissolved in water in the containment pool by the concentration ofair dissolved in water downstream of the strainer.

The concentration of air is calculated using Henry'sLaw:Page 198 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2CG = KG(T).PGEquation 64where:CG = Saturation concentration of airKG = Henry's constant for air at a given temperature T = Temperature PG = Partial pressure of airHenry's Constant for Air-Water Solutions Henry's constant for air (KG) can be determined based on the individual Henry's constant for eachcomponent of air (N2, 02, Ar, and C02). The volatility constant for each of these components can becalculated using the following semi-empirical correlation (87):Ac Bc"- (1 -T-)°'.355 ln(kc) = ln(PsAT)

+ T-* + + Cc* e(1-T') -(T*)-0"41 where:k, = Volatility constant in units of pressurePSAT = Saturation pressure at the given temperature Ac, Bc, Cc = Constants provided in Table 5.7.1T" = T/Tc where T is the temperature and Tc is the critical temperature of water ("K)Equation 65Table 5.7.1 -Semi-empirical correlation parameters to calculate Henry's constants in aqueous solvent(87)Maximum TSolute Ac Bc Cc (K)(K)Nitrogen

-11.6184 4.9266 13.3445 636.5Oxygen -9.4025 4.4923 11.3387 616.48Argon -7.4316 4.2239 9.6803 568.4Carbon Dioxide -9.4234 4.0087 10.3199 631.7The relationship between the volatility constant and the Henry's solubility constant is shown in Equation66.Page 199 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2K, = MPHOkC'MHOEquation 66where:Kc = Henry's solubility constant for gas component kc = Volatility constant for gas component PH20 = Density of waterMc = Molecular weight of gas component MH20 = Molecular weight of waterThe overall solubility constant for air can be calculated using the individual solubility constants as shownin Equation 67.KATK = KN2"FN2 +KO1 " FOI + KAr FA+KCOFCO where:K = Henry's solubility constant for each gas component F = Mole fraction of each gas component Equation 67Concentration of Air in Containment PoolThe partial pressure of air in the containment atmosphere can be calculated as shown in Equation 68using the containment pressure (P0) and the vapor pressure (Pv,O). Note that the subscript 0 is used todesignate conditions upstream of the ECCS strainer.

PG,o = PO- PEquation 68The vapor pressure can be calculated based on the saturation pressure (PSAT) at the pool temperature, and the relative humidity in containment

(+0) as shown in Equation 69.PV,0= 00-PSAT(TO)

Equation 69Combining Equation 69 into Equation 68 and Equation 68 into Equation 64 yields the following:

CGO = KG(TO) * [PI -00 PsAT(TO)]

Equation 70where:Page 200 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2CG,0 = Saturation concentration of air in the containment poolKG = Henry's constant for air at the pool temperature To = Temperature of the containment poolP0 = Containment pressureý0 = Relative humidity in containment PSAT= Saturation pressure at the pool temperature Concentration of Air Downstream of ECCS StrainerThe pressure downstream of the ECCS strainer can be calculated using the containment pressure (P0),the hydrostatic head of water above the strainer, and the pressure loss across the strainer (APLoss) asshown in Equation

71. The subscript 1 is used to designate conditions downstream of the strainer.

Notethat if the pressure downstream of the strainer is less than the saturation

pressure, boiling will occurresulting in a gas void fraction of essentially 100%. This condition is identified with a flag in CASAGrande.P1 = PO + pL (TO) "g HL -APLOSS Equation 71Similar to the containment pool calculation, the partial pressure of air and the vapor pressuredownstream of the ECCS strainer can be calculated using Equation 72 and Equation

73. Note that thetemperature downstream of the strainer is assumed to be the same as the temperature in thecontainment pool.PG,1 = P1 -Pv,1 Equation 72Pv,1 = 0"PsAT(Tl)

= 01"PSAT(To)

Equation 73Combining Equation 71 and Equation 73 into Equation 72 and Equation 72 into Equation 64 yields thefollowing:

CG,l = KG(TO) " [Po + pL(TO) " g " HL -APLOSS -01 PSAT(TO)]

Equation 74where:CG,1 = Saturation concentration of air downstream of the strainerKG = Henry's constant for air at the pool temperature To = Temperature of the containment poolP0 = Containment pressurePL = Water density at the pool temperature g = GravityHL = Pool height above the strainerPage 201 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2APLoss = Pressure drop across the strainerý, = Relative humidity downstream of the strainerPSAT= Saturation pressure at the pool temperature Quantity of Gas ReleasedAfter determining the concentration of air in solution before and after the strainer, the gas released canbe simply calculated as shown in Equation 75.ACG = CG,O -CGl Equation 75Note that the concentration of air released is in units of mass of air per unit volume of water. Therefore, the mass rate (AmG) that air is released from the water can be calculated by multiplying theconcentration of gas released by the flow rate through the strainer (QL) as shown in Equation 76.AMG = ACG " QL Equation 76The ideal gas law can then be used to convert the mass of gas released to a volume.AmG R -ToQG -M PG, 1 Equation 77where:OG = Volumetric flow rate of air releasedAmG = Mass flow rate of air releasedM = Molecular weight of airR = Ideal gas constantTo= Temperature of the containment poolPG,1 = Partial pressure of air downstream of the strainerThe void fraction (as) can be calculated as shown in Equation 78._ QGas = + QL Equation 78It is important to note that this void fraction is the void fraction just downstream of the strainers.

However, the concern is the void fraction at the pump inlet (a,). Since the temperature between thestrainer and pumps would be roughly constant, the volume of the gas voids at the pumps can becalculated based on the ideal gas law:Page 202 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2PSxP x _SX Equation 79where:apx = Void fraction at Pump XP, = Pressure inside the strainerPpx = Pressure at Pump XIn CASA Grande, the void fraction at the pumps was conservatively assumed to be the same as the voidfraction downstream of the sump strainers (see Assumption 8.i).5.7.3 Gas Transport and Accumulation Depending on the strainer, plenum, sump pit, and suction piping geometry, the local flow conditions, and the size of the gas bubbles released due to the strainer head loss, it is possible that the gas bubbleswould either transport through the ECCS pumps or accumulate at a high point upstream of the pumps.Figure 5.7.1 shows an isometric view of one of the ECCS strainers, and Figure 5.7.2 shows a cross-section of the strainer and sump pit. Air bubbles that are released due to degasification would have to transport horizontally or vertically through the stacked disks into the core tube, horizontally through the core tubeto the plenum, vertically through the plenum and sump pit to the ECCS suction pipe, and horizontally and vertically through the suction pipe to the pumps.Figure 5.7.1 -Isometric view of ECCS strainerPage 203 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Figure 5.7.2 -Cross-section view of ECCS strainer and sump pitBubble transport can be reasonably estimated based on the Froude number. For a horizontal pipe,partial bubble transport will occur when the Froude number is greater than 0.35, and full transport willoccur when the Froude number is greater than 0.55 (see Section 2.2.27).

The Froude number can becalculated using the following equation:

VFr = Equtio 8Equation 80where:Fr = Dimensionless Froude numberv = Velocity (in the core tube, plenum, sump pit, or suction pipe)g = Acceleration of gravityI = Characteristic length (hydraulic diameter of the core tube, plenum, sump pit, or suction pipe)Page 204 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2The diameter of the strainer core tube is approximately 0.9 ft (see Section 2.2.22).

Assuming a maximumsump flow rate of 7,020 gpm (see Section 2.2.8) split evenly between the four strainer core tubes, themaximum flow rate to each core tube would be 1,755 gpm. The Froude number within the core tubes(near the strainer plenum) is 1.14 as shown in the following calculation:

Fr = l,75Sgpm 1.147.48ga ...(_,.ft)2.322f/2 .0 Equation 81Since the maximum Froude number is greater than 0.55, it is possible that some air would betransported through the core tubes into the plenum. For vertical bubble transport from the plenum tothe suction pipe, partial bubble transport will occur when the Froude number is greater than 0.35, andfull transport will occur when the Froude number is greater than 1.0 (see Section 2.2.27).

The diameterof the suction pipe is approximately 1.3 ft (see Section 2.2.22),

and the maximum sump flow rate is7,020 gpm (see Section 2.2.8). The maximum Froude number within the suction pipe is 1.82 as shown inthe following calculation:

Fr = 7,O2gpm=

1.827.48galft 3 " .6 " (1-f). 32.2ft2 .Equation 82The horizontal cross-sectional area of the sump pit is 40 ft2 (see Section 2.2.22).

Since the hydraulic diameter of the sump pit (approximately 5.7 ft) is significantly larger than the suction pipe, the Froudenumber within the sump pit is only 0.03 as shown in the following calculation:

Fr = 7,=2Ogpm

-0.037.48 gal/f t3 "60S/rain" 40ft2 32.2 f t/s2 " 5.7ft Equation 83Therefore, if the bubbles transported to the sump suction piping, they would easily transport to thepumps. However, at the prototypical STP flow rates, it is not likely that the bubbles would transport vertically down through the sump pit. For conservatism in the evaluation of potential pump failures dueto air ingestion, and the negative effects of gas voids on the NPSH required, it was assumed that any gasvoids caused by degasification would be transported to the ECCS pumps (see Assumption 8.h).If the velocity within the strainer and sump is not high enough to transport the air bubbles, the air wouldaccumulate at high points within the strainer or plenum. There is a small area at the top of the strainerplenum where it is possible for air to collect.

It is also possible that air pockets could form at the top ofPage 205 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2the strainer disks. As shown in Figure 5.7.3, if a large enough gas void forms at the top of the plenum, airwould migrate to the strainer disks closest to the plenum. If the buoyancy of the voids in the strainerdisks is greater than the pressure drop across the debris bed on the strainer, the gas voids would breakthrough the debris bed and be vented to the containment pool.Figure 5.7.3 -Illustration of air bubble accumulation and venting5.7.4 Acceptance Criterion:

Pump Gas Void LimitsAs discussed in Section 2.2.28, the acceptance criterion for a steady-state gas void fraction at the pumpsuction inlet is 2%. As described in Assumption 8.i, the void fraction at the pumps was conservatively assumed to be the same as the void fraction at the strainer.

5.8 Debris Penetration Debris penetration is a function of two mechanisms.

The first mechanism is direct passage of debris as itarrives on the strainer.

A portion of the debris that initially arrives at the strainer will pass through, andthe remainder of the debris will be captured by the strainers.

The direct passage penetration is inversely proportional to the combined filtration efficiency of the strainer and the initial debris bed that forms.The second mechanism is shedding, which is the process of debris working its way through an existingbed and passing through the strainer.

By definition, the fraction of debris that passes through thestrainer by direct penetration will go to zero after the strainer has been fully covered with a fiberglass Page 206 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2debris bed. Shedding,

however, is a longer term phenomenon since particulate and small fiber debrismay continue to work its way through the debris bed for the duration of the event. These processes areillustrated in Figure 5.8.1.Clean Strainer40C0CLDirect Passage (1-filtration)

Loaded StrainerSheddingTimeFigure 5.8.1 -Illustration of direct passage and sheddingDebris that penetrates the strainer can cause both ex-vessel and in-vessel problems.

Ex-vessel effectsare addressed in Section 5.9, and in-vessel effects are addressed in Section 5.10 and Section 5.11. Themost significant downstream effects concern is related to the quantity of fiberglass debris thataccumulates in the core. This is a highly time-dependent process due to the following time-dependent parameters.

" Initiation of recirculation with cold leg injection

" Switchoverto hot leg recirculation

" Arrival of debris at the strainer* Accumulation of debris on the strainer" Direct passage* Debris shedding" Flow changes when pumps are securedPage 207 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Decay heat boil-offThe timing for initiation of recirculation, switchover to hot leg injection, and procedurally securingpumps is described in Section 2.2.1. The time-dependent arrival of debris at the strainer is described inSection 5.5.8. The decay heat boil-off curve, which defines the flow split to the core for cold leg breaksduring cold leg injection, is described in Section 5.10.3. Debris accumulation on the strainer and debrispenetration through the strainer (including both direct passage and shedding) are described in moredetail within this section.The various parameters associated with time-dependent debris accumulation on the strainer and coreare illustrated in Figure 5.8.2, where Sn(t) is the source rate for initial introduction of debris type n, V(t) isthe pool volume, mn(t) is the mass of debris n in the pool, fn(t) is the filtration efficiency for debris n atthe strainer, sn(t) is the shedding rate for debris n from the existing debris bed, Q(t) is the volumetric flow rate passing through the strainers, y is the fraction of SI flow compared to the total flow, A is thefraction of flow passing through the core compared to the total SI flow, and gn(t) is the filtration efficiency for debris n at the core.Figure 5.8.2 -Illustration of time-dependent parameters associated with debris accumulation on thestrainer and corePage 208 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2As illustrated by Figure 5.8.2, debris that passes through the strainer will not necessarily end up on thecore. A portion of the debris could pass through the containment spray pumps, and a portion couldeither bypass or pass directly through the core and spill out the break. The debris that doesn'taccumulate in the core may end up back in the pool where it could transport and potentially passthrough the strainer again. The differential rate of change for each debris type in the pool (assuming ahomogenous mixing volume) can be described using the following equation (28):dmn Q Q= S. A -mn -YAg9(1 -f) -mn + Sn -YAqgnSn Equation 84dt Vwhere all of the properties can be time-dependent and have the following definitions:

mn= Mass of debris type n suspended in the poolt = Timefn = Filtration efficiency for debris type n at the strainerQ = Volumetric flow rate passing through strainers V = Total volume of the poolSn = Source rate for initial introduction of debris type ns, = Shedding rate for debris type n from existing bedgn = Filtration efficiency for debris type n at the coreV = Fraction of the total flow going to the SI pumpsA = Fraction of SI flow going to the coreNote that 100% filtration efficiency at the strainer, fn, for non-fibrous debris (i.e., particulate or chips) isused in CASA. This is conservative since it maximizes the strainer head loss, and the particulate debrisquantity is not considered in the core blockage and boron precipitation acceptance criteria.

Based on Equation 84, the total quantity of debris that accumulates on the strainer or the core can bedescribed by the following equations (28):trV(t')MC(t) (1 ] Q(n = J Yt)A W)- fg(t')) mI-(t) + Sn(C) dt' Equation 86where:Page 209 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Ms = Cumulative mass of debris type n on the strainerMc = Cumulative mass of debris type n on the coret' = Dummy integration variable where t' < t denotes all times from the start to t of interestEquation 84 through Equation 86 can be determined using the following analytical

solution, where thesubscript n has been dropped for simplification:

Att....1Nj=1Equation 87Equation 88Equation 89Equation 90N ý ~ -) -A t -1 ( i 1Mti-l) IEquation 91hj(ti _) -Qt i _ )Ati_, = ti -ti-1Equation 92Equation 93where:ti = End of specific time step intervalti.I = Beginning of specific time step intervalN = Number of ECCS strainers Subscript j = Variables specific to a given ECCS strainerSk = Source rate for initial introduction of fiber type kPage 210 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande AnalysisRI-GSI191-V03 Revision 2Each of these equations can be solved by explicit forward integration assuming that the integrands areknown at the beginning of each time step and that they remain constant during each time step.Variables such as the source rate of debris to the pool (S), the strainer flow rate (Q), the pool volume (V),the SI and CS flow split (y), and the SI flow vs. boil-off flow split (A) are defined in other sections.

Thefiltration efficiency for the core (g) is conservatively assumed to be 100% (i.e., all debris that transports to the core is trapped).

Therefore, the primary unknowns in Equation 87 through Equation 93 are thefiltration efficiency at the strainer (f) and the shedding rate (s).The shedding rate can be defined as a function of time as described in the following equation (28):t t)Sn(t) = vnrne-tInt f A( t') Q m(t')eflnt'dt' Equation 94where:Vn = Fraction of debris type n that is "sheddable" (i.e., able to pass through a debris bed)n, = Time constant associated with the shedding processSimilar to the analytical solution above, Equation 94 can be solved as follows where the subscript n hasbeen dropped for simplification:

VmMjh(tt)

= mfh(t.- )* e-7'Ati-,

+ v fj(ti-1) " hj(ti-1) " m(ti-1)[1 -e-O'Ati-1]

Equation 95sj (t,) = 7 .mjh (t,) Equation 96where:mjsh = Mass of sheddable debris in the bedTo determine the filtration efficiency and shedding rate, a series of penetration tests were conducted atAlden Research Laboratory (ARL) (26). A combination of 100% capture filter bags and isokinetic grabsamples were used to gather data regarding the change in penetration as a function of strainer loadingand time. A series of sensitivity tests were also conducted at Texas A&M University (TAMU) and ARL,which showed that penetration is not strongly dependent on water chemistry (27) or debrisconcentration and flow rate within the range of conditions tested (26). The ARL test data wasstatistically evaluated to determine appropriate fitting parameters to describe the shedding andfiltration terms as a function of the debris load on the strainer and time (60). The filtration equation andfitting parameters for filtration and shedding are provided in Section 2.2.29.Page 211 of 248

v t e Letter Sequence Other
TAC:MF0613, (Open) TAC:MF0614, (Open) TAC:MF2400, Control Room Habitability (Open) TAC:MF2401, Control Room Habitability (Open) TAC:MF2402, Control Room Habitability (Open) TAC:MF2403, Control Room Habitability (Open) TAC:MF2404, Control Room Habitability (Open) TAC:MF2405, Control Room Habitability (Open) TAC:MF2406, Control Room Habitability (Open) TAC:MF2407, Control Room Habitability (Open) TAC:MF2409, Control Room Habitability (Open)
Initiation Request Acceptance, Acceptance, Acceptance Supplement, Supplement, Supplement, Supplement Administration Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting Questions 26 November 2013 Answers Results Approval... Other: ML13098A396, ML13098A431, ML13098A511, ML13175A211, ML13323A186, ML13323A189, ML13323A190, ML13323A191, NOC-AE-13003039, Corrections to Information Provided in Revised STP Pilot Submittal and Requests for Exemptions and License Amendment for a Risk-Informed Approach to Resolving Generic Safety Issue (GSI)
MONTHYEAR2013-12-23 [Table View]

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