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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 4-3 Risk-Informed Closure of GSI-191 Volume 3 Engineering (CASA Grande) Analysis STF South Texas Project Risk-Informed GSI-191 Evaluation Volume 3 CASA Grande Analysis Document:

STP-RIGS1191-V03 Revision:

2 Date: November 6, 2013 Prepared 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 Analysis RI-GSI191-V03 Revision 2 The Risk-Informed GSI-191 Closure Pilot Program is piloted by the South Texas Project (STP) Nuclear Operating Company and jointly funded with several other licensees.

It is a collaboration of experts from industry, academia, and a national laboratory.

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

Technical Team Meetings and weekly teleconferences as well as in specific review cycles by Independent Oversight (technical evaluation of all materials), STP Nuclear Operating Company project management, and STP Nuclear Operating Company quality management.

The business entities, the main areas of investigation, and the principal investigators of the Pilot Program are summarized below.STP Nuclear Operating Company Project Management, Licensing, Quality Assurance Steve Blossom; Rick Grantom (ret.); Ernie Kee; Wayne Harrison (ret.); Wes Schulz Allan Science & Technology Containment Accident Stochastic Analysis (CAS) Grande & GSI-191 Analysis & Methodology Implementation (GAMI)Bruce Letellier, PhD 1; Janet Leavitt, PhD 2;Tim Sande 3; Gil Zigler 3; Austin Glover 3 , Clint Shaffer, Joe Tezak 3 The University of New Mexico Corrosion/Head Loss Experiments (CHLE)Kerry Howe, PhD University of Illinois at Urbana Champaign Independent Oversight Zahra Mohaghegh, PhD 4; Seyed Reihani, PhD 4 Texas A&M University Thermal Hydraulics (TH)Yassin Hassan, PhD; Rodolfo Vaghetto, PhD; Saya Lee The University of Texas at Austin Uncertainty Quantification (UQ), Jet Formation Elmira Popova, PhD (1962-2012);

David Morton, PhD; Alex Galenko, PhD; Jeremy Tejada, PhD; Erich Schneider, PhD ABS Consulting Probabilistic Risk Assessment (PRA)David Johnson, ScD; Don Wakefield; Tom Mikschl Knf Consulting Services, LLC Location-Specific Failure Damage Mechanism (DM)Karl Fleming; Bengt Lydell (ScandPower) 1 Previous to 2013, Los Alamos National Laboratory 2 Previously, UNM 3 From January 2013, Sande, Glover, Zigler, and Tezak, ENERCON 4 Previous to 2013, Soteria Consultants, LLC Page 2 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Revision History Log Revision 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 debris size distribution and fiberglass erosion fractions with references to specific tables that contain the same information in other documents." Added a new section describing the information process flow in CASA Grande." Added a description at the end of the conventional head loss section to clarify that the head loss values calculated with the NUREG/CR-6224 correlation were increased significantly to account for uncertainties in the correlation." Replaced informal email reference for shedding parameters with a revised version of the UT technical report and updated parameter values.2 See Cover Several changes were made to this version of the report to address page inconsistencies that were discovered between the previous version and the actual 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 describe interpolated 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 water volume and pool level in Section 2.2 that were not implemented in CASA." Revised footnotes to correct reference numbers." Corrected total SI flow rate for 27.5-inch DEGB in Section 2.2 along with the associated figure and equation." Added elevation difference below the containment floor for CS and LHSI 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 Analysis RI-GSI191-V03 Revision 2 Revision Date Description profiles along with the interpolation scheme that was not implemented in CASA, and added a table showing the specific values that were implemented." Added statements in the design input and debris generation analysis sections that the bounding LBLOCA qualified coatings quantities were used for all break sizes in CASA. Also added a footnote in Section 2.2 clarifying the basis for the qualified coatings quantities used." Added an assumption that the qualified coatings debris is assumed to fail as 10 pIm particles." Deleted unqualified coatings figures and data in Section 2.2 that were not implemented in CASA." Revised description of the treatment of unqualified coatings in the debris generation analysis section to clarify the CASA evaluation.

Deleted destruction pressures corresponding to the insulation ZOI sizes in Section 2.2.* Split assumption regarding linear interpolation of LOCA frequencies into two separate assumptions-one for the interpolation of the top-down frequencies and another for the interpolation of the bottom-up frequencies." Made several corrections to the characteristic debris sizes and densities shown in the strainer head loss analysis section including:

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

o Corrected the macroscopic density of Microtherm fiber from 15 Ibm/ft 3 to 2.4 Ibm/ft 3.o Corrected the densities for Microtherm TiO 2 and Si0 2 , which were inadvertently switched in the previous revisions.

o Corrected the size and S, for epoxy fines from 6 pIm to 6 mils (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 metal Page 4 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Revision Date Description quantity inputs from Section 2.2.* The assumptions that there would be no washdown transport for breaks where sprays are not initiated, and that unqualified coatings would wash down to the pool immediately if they fail while the sprays are still on were both deleted.* A new assumption was added that the transport fractions for an LBLOCA in the steam generator compartments can be used for all breaks.* 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 2.2 and replaced it with the maximum value. Also updated the clean strainer head loss analysis section to specify that the maximum clean strainer head loss was used for all breaks.* Revised penetration parameters in Section 2.2 to show n in units of min-1 rather than a dimensionless variable.

Also deleted inaccurate equation in the debris penetration analysis section used to correct n 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 a range 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 in CASA." Provided additional justification for the assumption that a combination of pumps failing in the same train is worse than the same combination of pumps failing in separate trains." Modified assumption that spray erosion would occur prior to the start of recirculation to also include pool erosion." Deleted assumption that the gas void at the pumps would be proportional to the pump flow split since the gas void fraction at the strainers was assumed to be the same as the gas void fraction at the pumps." Deleted assumption regarding the effects of counter-current flow on debris buildup in the core." Clarified assumption on small break boron precipitation to state that boron precipitation was not precluded for small breaks." Revised illustration of sump failure criteria in Section 4.2 to correct the NPSH available equation." Revised description of CASA Grande to clarify that it was not Page 5 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Revision Date Description developed as a generic software package, but was simply used as an 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 sampled in the LOCA frequency analysis section." Deleted chemical effects analysis section.* Edited strainer head loss analysis section to clarify that a bounding clean strainer head loss value was used rather than a flow and temperature dependent correlation.

Corrected typos in head loss correlation equations." Revised head loss equation for calculating the composite Sv value from a geometric weighting by volume to a linear weighting by mass for consistency with the equation that was used in CASA." Deleted Froude number equation for vortex formation in the air intrusion analysis section.* Deleted inaccurate equation describing the split in void fraction between pumps in air intrusion analysis section." Added a note in the penetration analysis section to clarify that a strainer filtration efficiency of 100% was used for particulate debris." Added footnote in the in-vessel downstream effects analysis section stating that preliminary results from additional thermal-hydraulic modeling has indicated that siphon effects are possible under specific conditions.

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

Also added additional strainer geometry input to Section 2.2.* Replaced implicit friction factor equation in the strainer head loss analysis section with an explicit form. Also added the pipe roughness and suction pipe diameter input to Section 2.2." Added a note to the parametric evaluation section to explain that the parametric cases were not rerun based on the current changes to CASA and therefore should only be used for qualitative insights." Replaced example input deck in Appendix 1 with the new input decks." Other miscellaneous editorial changes.Two types of changes were made to the CASA Grande program to support requantification of conditional failure probabilities reported in this revision.Page 6 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Revision I Date Description Changes involving the code structure or equation implementation were verified to have either no effect or incidental effect by comparing results from a baseline calculation before and after the modification.

Changes involving input parameters were examined as sequential perturbations to a baseline calculation before adopting the entire suite for reevaluation.

The code 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 input level for each pump type.* Corrected slopes of total injection flow rate to reflect change in summary table.* Corrected logic to allow one CS train off if and only if all three actuate.* Removed alternate polynomial evaluation of saturation pressure for degasification calculation and replaced with lookup table from NIST.* Optimized NPSH routine for matrix evaluation.

Fixed error in passing relative roughness to Colebrook friction equation caused by misinterpretation of published equation.The input changes to CASA Grande include:* Corrected pump failure definition for Case 9 to model two LHSI pump 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 Johnson percentiles 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% of the 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 Analysis RI-GSI191-V03 Revision 2 Table of Contents Revision History Log ......................................................................................................................................

3 Table of Contents ..........................................................................................................................................

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

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

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

16 1 Introduction

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

18 2 Design Input ........................................................................................................................................

24 2.1 General Description of Inputs Required ...............................................................................

24 2.2 Specific Inputs Used ....................................................................................................................

32 2.2.1 Tim ing for Key Plant Response Actions .........................................................................

32 2.2.2 Containm ent Geom etry ................................................................................................

33 2.2.3 LOCA Frequencies

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

33 2.2.4 Pum p State Frequencies

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

43 2.2.5 Pool W ater Level ............................................................................................................

45 2.2.6 Pool Tem perature .........................................................................................................

45 2.2.7 Operating Trains ............................................................................................................

51 2.2.8 ECCS and CSS Flow Rates ................................................................................................

51 2.2.9 Qualified Coatings Quantity ...........................................................................................

54 2.2.10 Unqualified Coatings Quantity .......................................................................................

54 2.2.11 Crud Debris Quantity ....................................................................................................

55 2.2.12 Latent Debris Quantity ...................................................................................................

56 2.2.13 M iscellaneous Debris Quantity .......................................................................................

56 2.2.14 Insulation Zones of Influence

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

56 2.2.15 Insulation Debris Size Distribution

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

56 2.2.16 Debris Characteristics

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

57 2.2.17 Blow dow n Transport Fractions

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

58 2.2.18 W ashdow n Transport Fractions

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

59 2.2.19 Pool Fill Transport Fractions

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

60 2.2.20 Recirculation Transport Fractions

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

60 2.2.21 Debris Erosion .....................................................................................................................

62 2.2.22 Strainer Geom etry .........................................................................................................

63 2.2.23 Clean Strainer Head Loss .................................................................................................

66 2.2.24 Pum p NPSH M argin .......................................................................................................

66 2.2.25 Strainer Structural M argin .............................................................................................

67 2.2.26 Vortex Air Ingestion

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

67 2.2.27 Bubble Transport

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

67 2.2.28 Pum p Gas Lim its ............................................................................................................

67 2.2.29 Fiberglass Penetration

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

67 Page 8 of 248 South Texas Project Risk-informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI 191-V03 Revision 2 2.2.30 Decay Heat Curve ................................................................................

69 2.2.31 Core Blockage Debris Limits.....................................................................

70 3 Assumptions..................................................................................................

71 4 Methodology

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

83 4.1 GSI-191 Analysis Steps ................................................................................

87 4.2 Structured Information Process Flow................................................................

89 4.3 Uncertainty Quantification and Propagation........................................................

97 4.4 Verification and Validation

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

97 5 Analysis ......................................................................................................

98 5.1 Evaluation Scenarios (PRA Branch Fractions to Populate)..........................................

98 5.2 Containment CAD Model............................................................................

101 5.3 LOCA Frequency......................................................................................

122 5.3.1 Relative Weight of Breaks in Specific Weld Categories

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

124 5.3.2 Weld Categories and Coordinates

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

127 5.3.3 Statistical Fit of NUREG-1829 LOCA Frequencies

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

147 5.3.4 Sample Epistemic Uncertainty of LOCA Frequencies

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

148 5.3.5 Sample Break Sizes at Each Weld Location...................................................

149 5.4 Debris Generation....................................................................................

151 5.4.1 701 Model .......................................................................................

151 5.4.2 Insulation Debris Size Distribution Model....................................................

155 5.4.3 Insulation Debris ...............................................................................

156 5.4.4 Qualified Coatings Debris ......................................................................

156 5.4.5 Unqualified Coatings Debris ...................................................................

157 5.4.6 Latent Debris....................................................................................

158 5.4.7 Miscellaneous Debris ..........................................................................

158 5.4.8 Debris Characteristics..........................................................................

158 5.5 Debris Transport

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

158 5.5.1 Upstream Blockage.............................................................................

158 5.5.2 Blowdown Transport

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

159 5.5.3 Washdown Transport

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

160 5.5.4 Pool Fill Transport..............................................................................

160 5.5.5 Recirculation Transport

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

160 5.5.6 Debris Erosion ..................................................................................

161 5.5.7 Strainer Transport..............................................................................

161 5.5.8 Time-Dependent Debris Arrival Model .......................................................

173 5.6 Strainer Head Loss ...................................................................................

174 5.6.1 Clean Strainer Head Loss.......................................................................

174 5.6.2 Conventional Debris Head Loss Model .......................................................

175 5.6.3 Chemical Debris Head Loss Model ............................................................

186 5.6.4 Strainer Head Loss..............................................................................

191 Page 9 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 5.6.5 Acceptance Criterion:

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

192 5.6.6 Acceptance Criterion:

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

197 5.7 Air Intrusion

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

197 5.7.1 Vortex Form ation ..............................................................................................................

198 5.7.2 Degasification

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

198 5.7.3 Gas Transport and Accum ulation ......................................................................................

203 5.7.4 Acceptance Criterion:

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

206 5.8 Debris Penetration

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

206 5.9 Ex-Vessel Dow nstream Effects ..................................................................................................

212 5.9.1 Pum p, Valve, Com ponent W ear ........................................................................................

212 5.9.2 System and Com ponent Clogging/Blockage

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

213 5.10 In-Vessel Dow nstream Effects ..................................................................................................

214 5.10.1 Fuel Rod Debris Deposition (LOCADM ) .............................................................................

214 5.10.2 Core Blockage Scenarios

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

215 5.10.3 Decay Heat Boil-Off Flow Rate ..........................................................................................

223 5.10.4 Tim e-Dependent Core Debris Accum ulation ....................................................................

225 5.10.5 Acceptance Criteria:

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

226 5.11 Boron Precipitation

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

226 5.11.1 Tim e-Dependent Core Debris Accum ulation ....................................................................

228 5.11.2 Acceptance Criteria:

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

228 5.12 Param etric Evaluations

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

228 6 Results ...............................................................................................................................................

232 7 Conclusions

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

242 8 References

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

94 Figure 4.2.4 -Illustration of sum p failure criteria .................................................................................

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

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

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

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

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

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

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

106 Figure 5.2.7 -Plan view of containment floor (Elevation

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

107 Figure 5.2.8 -Isometric view of containment floor (Elevation

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

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

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

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

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

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

112 Figure 5.2.13 -Thermal-Wrap insulation on steam generators

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

113 Figure 5.2.14 -Microtherm insulation in secondary shield wall penetrations

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

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

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

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

116 Figure 5.2.18 -Currently installed ECCS strainers

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

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

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

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

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

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

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

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

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

147 Figure 5.3.3 -Illustration of LOCA frequency vs. break size for 6 2 nd percentile

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

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

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

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

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

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

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

155 Figure 5.4.5 -Distribution of potential fiberglass debris quantities

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

195 Figure 5.7.1 -Isom etric view of ECCS strainer .........................................................................................

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

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

206 Figure 5.8.1 -Illustration of direct passage and shedding .......................................................................

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

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

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

216 Figure 5.10.3 -Large or medium hot leg break during cold leg injection with partial core blockage ..... 217 Figure 5.10.4 -Large or medium hot leg break during hot leg injection

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

219 Figure 5.10.5 -Large or medium cold leg break during cold leg injection with partial core blockage .... 220 Figure 5.10.6 -Large or medium cold leg break during hot leg injection

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

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

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

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

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

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

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

235 Figure 6.2 -Empirical distribution of total failure probability for Case 43 (one train operable) based on 15 discrete samples of the NUREG-1829 break-frequency uncertainty envelope ...................................

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

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

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

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

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

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

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

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

3 5 Table 2.2.4 -Relative frequencies vs. break size for cold leg and surge line welds (Categories 3C through 4 D ) ...............................................................................................................................................................

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

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

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

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

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

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

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

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

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

.........

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

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

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

55 Table 2.2.18 -Unqualified epoxy debris size distribution

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

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

56 Table 2.2.20 -Input variables used primarily in debris penetration and core blockage analysis ...... 56 Table 2.2.21 -M aterial properties of debris .........................................................................................

57 Table 2.2.22 -Blowdown transport fractions according to break location .........................................

59 Table 2.2.23 -Washdown transport fractions according to spray initiation

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

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

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

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

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

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

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

68 Table 2.2.29 -Fitted filtration parameters for each ECCS strainer ........................................................

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

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

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

69 Table 3.1 -Strainer debris accumulation and approach velocity comparison

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

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

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

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

100 Table 5.3.1 -Description of w eld categories

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

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

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

131 Table 5.3.4 -Example calculation of LOCA frequencies vs. break size for 6 2 nd Percentile

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

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

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

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

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

161 Table 5.5.5 -Tim e-dependent transport

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

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

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

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

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

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

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

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

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

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

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

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

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

239 Page 15 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Definitions and Acronyms ARL Alden Research Laboratory BC Branch Connection BEP Best Efficiency Point B-F Bimetallic Welds B-J Single Metal Welds BWR Boiling Water Reactor CAD Computer Aided Design CASA Containment Accident Stochastic Analysis CCDF Complementary Cumulative Distribution Function CCW Component Cooling Water CDF Core Damage Frequency CHLE Corrosion/Head Loss Experiments CS Containment Spray CSHL Clean Strainer Head Loss CSS Containment Spray System CVCS Chemical Volume Control System D&C Design and Construction Defects DEGB Double Ended Guillotine Break DM Degradation Mechanism ECC Emergency Core Cooling ECCS Emergency Core Cooling System EOP Emergency Operating Procedure EPRI Electric Power Research Institute ESF Engineered Safety Feature FA Fuel Assembly GL 08-01 Generic Letter 2008-01 GSI-191 Generic Safety Issue 191 HHSI High Head Safety Injection HLSO Hot Leg Switchover IGSCC Intergranular Stress Corrosion Cracking LBLOCA Large Break Loss of Coolant Accident LDFG Low Density Fiberglass LERF Large Early Release Frequency LHS Latin Hypercube Sampling LHSI Low Head Safety Injection LOCA Loss of Coolant Accident MBLOCA Medium Break Loss of Coolant Accident NIST National Institute of Standards and Technology NPSH Net Positive Suction Head Page 16 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 NRC Nuclear Regulatory Commission OD Outer Diameter PDF Probability Density Function PRA Probabilistic Risk Assessment PWR Pressurized Water Reactor PWROG Pressurized Water Reactor Owner's Group PWSCC Primary Water Stress Corrosion Cracking RCS Reactor Coolant System RHR Residual Heat Removal RI-ISI Risk-Informed In-Service Inspection RMI Reflective Metal Insulation RWST Refueling Water Storage Tank SBLOCA Small Break Loss of Coolant Accident SC Stress Corrosion SI Safety Injection SIR Safety Injection and Recirculation SRM Staff Requirements Memorandum STP South Texas Project STPNOC South Texas Project Nuclear Operating Company TAMU Texas A&M University TF Thermal Fatigue TGSCC Transgranular Stress Corrosion Cracking TSC Technical Support Center USI A-43 Unresolved Safety Issue A-43 UT University of Texas (Austin)V&V Verification and Validation VF Vibration Fatigue WCAP Westinghouse Commercial Atomic Power ZOI Zone of Influence Page 17 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSl191-V03 Revision 2 1 Introduction The emergency core cooling system (ECCS) and containment spray system (CSS) in a pressurized water reactor (PWR) are designed to safely shutdown the plant following a loss of coolant accident (LOCA) in accordance with 10CFR50.46.

The assurance of long term core cooling in PWRs following a LOCA has a long history dating back to the Nuclear Regulatory Commission (NRC) studies of the mid 1980s associated 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 modes that were not considered in the resolution of USI A-43. As a result of these concerns, Generic Safety Issue (GSI) 191 was identified in September 1996 related to debris clogging of the ECCS sump suction strainers at PWRs. Although plants have taken steps to prevent strainer clogging (by increasing the screen area, for example), satisfactory closure of this issue has proved elusive due to long term cooling issues and the effect of chemical precipitates on head loss. Previous investigators have identified bounding scenarios using conservative inputs, methods, and acceptance criteria.

The acceptance criteria are 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 large quantity of insulation on nearby piping and equipment.

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

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 the containment floor. Debris on the containment floor could be transported by the high-velocity sheeting flow 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 the RWST has been depleted, the ECCS and CSS pumps would be automatically switched over to recirculation.

Some of the debris in the containment pool would be transported to the ECCS sumps where 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 various containment metals, and dissolution of insulation debris and other materials in the buffered and borated containment pool may result in the formation of chemical precipitates.

These precipitates can accumulate on the strainer debris beds increasing the overall head loss. Some of the chemical precipitates may also penetrate the strainer.

If the head loss across the strainer exceeds either the net Page 18 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 positive 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 or wear of various downstream components, or more significantly blockage of the fuel channels within the reactor core.The assurance of long-term post-LOCA core cooling must be fully addressed as required by the NRC in Generic 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. Although there were known conservatisms in the analyses, there was no method for quantifying the overall margin associated with the conservatisms so that the effects of best-estimate assumptions could be put into proper perspective and compared to the conservative assumptions to holistically determine the overall level of margin.In 2010, due to the ongoing challenges of resolving GSI-191, the NRC commissioners directed the staff to consider new and innovative resolution approaches (3). One of the approaches included in the SRM was the 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 resolve GSI-191. An evaluation tool called CASA Grande 5 was developed to analyze the accident sequences in a realistic time-dependent manner with uncertainty propagation to determine the probabilities of various failures 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 that need to be considered are: 1. Strainer head loss exceeds the NPSH margin for the pumps causing some or all of the ECCS and CSS pumps to fail.2. Strainer head loss exceeds the strainer structural margin causing the strainer to fail, which could subsequently result in larger quantities and larger sizes of debris being ingested into the ECCS and CSS.3. Air intrusion exceeds the limits of the ECCS and CSS pumps causing degraded pump performance or complete failure due to gas binding.4. Debris penetration exceeds ex-vessel effects limits causing a variety of potential equipment and component failures due to wear or clogging.5. Debris penetration exceeds in-vessel effects limits resulting in partial or full core blockage with insufficient flow to cool the core.5 CASA is an acronym for Containment Accident Stochastic Analysis Page 19 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 6. Buildup of oxides, crud, LOCA-generated debris, and chemical precipitates on fuel cladding exceeds 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 and subsequently 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 not explicitly 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, and Figure 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 Analysis RI-GSI191-V03 Revision 2 General Inputs" Accident lime" Pool Water Level" Containment Pressure" Pool Temperature" Operating Trains" Spray Flow Rate" Injection Flow Rate* Sump Flow Rate Debris Generation Inouts" LOCA Frequency* Insulation Location" Unqualified Coatings Location/Failure" Latent Debris Quantity" Miscellaneous Debris Quantity" Destruction Pressure" Size Distribution" Debris Density Debris Transport Inputs" Blowdown Transport" Washdown Transport* Pool Fill Transport" Recirculation Transport" Debris Erosion-U -I Debris Penetration I CASA Grande" Filtration Efficiency" Shedding Parameters I--1--I-I I Strainer Head Loss Inouts" Strainer Dimensions" Strainer Area" Strainer Interstitial Volume" Clean Strainer Head Loss" Chemical Effects Head Loss" NPSH Margin" Structural Margin J, I Core Blockage Inputs Core Fiber Limits Air Intrusion Inputs Pump Gas Limits I Boron Precipitation Inputs" Boil-off Rate" Core Fiber Limits Figure 1.1 -CASA Grande input variables Page 21 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 CASA Grande i-----------------------------------------------------------------------------------

Figure 1.2 -CASA Grande calculation modules Page 22 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 PRA Confituration Failure Frequencies" S/M/L Breaks" Train/Pump Failure-~~~~ ---------------------

'4-CASA Grande Strainer Head Loss Air Intrusion* Pump Failure (Exceed Pump Failure (Exceed NPSH Margin) Pump Gas Void Limits) I* Strainer Failure (Exceed Structural 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 PRA 4%PRA Conditional Failure Probabilities and Initiating Event Freauencies

S/M/L Breaks-Train/Pump Failure Figure 1.3 -CASA Grande link to PRA Page 23 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 2 Design Input A wide range of input variables are used in the various GSI-191 analysis areas. In some cases, the input may consist of a single value, in other cases the input may have a probability distribution or change over time. Some inputs must be entered into CASA Grande as part of the input deck (e.g., containment pool temperature 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 2.1 provides a general description of the relationship between the various input parameters, and Section 2.2 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 of the 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 Required Table 2.1.1 through Table 2.1.5 list the design input variables that go into a GSI-191 evaluation.

They also 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 affect multiple 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 various input variables tie together in CASA Grande.Page 24 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 2.1.1 -General input variables used in multiple aspects of the analysis Design Input Conservative Preceding Direct-Input Proceeding Direct- Comments Variable Direction Variables Output Variables Accident Time N/A N/A Unqualified Coatings Failure, Spray Flow Rate, Sump Flow Rate, Strainer Accumulation, Containment Temperature, Fiber Penetration, Boil-off Flow Rate, Core Accumulation Break Location N/A LOCA Frequency Debris Quantity, Debris Size Distribution, Core Accumulation Break Size '1 LOCA Frequency Pool Temperature, ZOI Size, Injection Flow Rate Pool Water Break Size Pool Water Level, Strainer Volume 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, NPSH Available, Degasification Operating 13/4J, N/A Spray Flow Rate, Injection Pumps Flow Rate, Sump Flow Rate Spray Flow Rate Operating Pumps, Sump Flow Rate, Core Accident Time Accumulation Injection Flow '" Operating Pumps, Sump Flow Rate, Core Rate Break Size Accumulation Sump Flow Rate Spray Flow Rate, Strainer Approach Injection Flow Rate Velocity, NPSH Available, Degasification, Fiber Penetration Table 2.1.2 -Input variables used primarily in debris generation analysis Design Input Conservative Preceding Direct-Input Proceeding Direct- Comments Variable Direction Variables Output Variables LOCA 1" N/A Break Location, Break Frequency Size Insulation N/A N/A Debris Quantity, Size Location Distribution Qualified

' N/A Debris Quantity Coatings Quantity Page 25 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Design Input Conservative Preceding Direct-Input Proceeding Direct- Comments Variable Direction Variables Output Variables Unqualified

'1' N/A Debris Quantity Coatings Quantity Unqualified N/A N/A Debris Transport Coatings Location Unqualified 1 Accident Time Debris Quantity, Debris Coatings Failure Transport Latent Debris '1 N/A Debris Quantity Quantity Miscellaneous

'1 N/A Debris Quantity Debris Quantity Destruction

' N/A ZOI Size Pressure ZOI Size 1" Break Size, Destruction Debris Quantity Pressure Debris Size Break Location, Debris Transport, Strainer Distribution Insulation Location Head Loss Debris Density N/A Strainer Head Loss Head loss increases with higher macroscopic density and lower microscopic density Debris Quantity '1' Break Location, Strainer Accumulation Insulation Location, ZOI Size, Qualified Coatings Quantity, Unqualified Coatings Failure, Latent Debris Quantity, Miscellaneous Debris Quantity Page 26 of 248 South Texas Project Risk-informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI 191-V03 Revision 2 Debris Generation Analysis CASA Grande Inputs]I CASA Grande Calculations I Jt) = function of accident time Figure 2.1.1 -Illustration of input variable relationships for debris generation analysis Table 2.1.3 -Input variables used primarily in strainer head loss analysis Design Input Conservative Preceding Direct-Input Proceeding Direct- Comments Variable Direction Variables Output Variables Strainer Height I' N/A Degasification Strainer Area N/A Debris Bed Thickness, Strainer Approach Velocity, Fiber Penetration Strainer N/A Debris Bed Thickness, Interstitial Strainer Area Volume Debris '1 Debris Size Distribution, Strainer Accumulation Transport Unqualified Coatings Location, Unqualified Coatings Failure Page 27 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Design Input Conservative Preceding Direct-Input Proceeding Direct- Comments Variable Direction Variables Output Variables Strainer T" Debris Quantity, Debris Debris Bed Thickness, Accumulation Transport, Sump Flow Fiber Penetration, Rate, Pool Volume, Strainer Approach Accident Time Velocity Debris Bed Strainer Accumulation, Strainer Head Loss Thickness Strainer Area, Strainer Interstitial Volume Chemical '1 Pool Temperature Strainer Head Loss Precipitation Strainer '" Sump Flow Rate, Strainer Head Loss Approach Strainer Area, Strainer Velocity Accumulation Clean Strainer '1 N/A Strainer Head Loss Head Loss Strainer Head '" Pool Temperature, Degasification, Sump Loss Strainer Approach Failure Velocity, Clean Strainer Head Loss, Debris Bed Thickness, Debris Size Distribution, Chemical Precipitation NPSH Required '1 Degasification NPSH Margin NPSH Available 4 Pool Water Level, NPSH Margin Containment Pressure, Pool Temperature, Sump Flow Rate NPSH Margin , NPSH Required, NPSH Sump Failure Acceptance criterion Available compared against strainer head loss Structural 4 N/A Sump Failure Acceptance criterion Margin compared against strainer head loss Page 28 of 248 South Texas Project Risk-informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Strainer Head Loss Analysis I CASA Grande Inputs I CASA Grande Calculations I.f(t) = function of accident time Figure 2.1.2 -Illustration of input variable relationships for strainer head loss analysis Table 2.1.4 -Input variables used primarily in gas intrusion analysis Design Input Conservative Preceding Direct-Input Proceeding Direct- Comments Variable Direction Variables Output Variables Degasification 1' Strainer Height, Pool NPSH Required, Sump Water Level, Failure Containment Pressure, Pool Temperature, Sump Flow Rate, Strainer Head Loss Pump Gas , N/A Sump Failure Acceptance criterion Limits compared against gas void fraction Page 29 of 248 South Texas Project Risk-informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Gas Intrusion Analysis I CASA Grande Inputs I CASA Grande Calculations f(t) = function of accident time I Strainer Head Lossf(t) i Sump Flow Ratef(t), Pool Water Level, Strainer Height, Pool Temperaturef (t), Containment Pressuref(t), h 8"IDegasif ication_!:(t)

I" Pump Gas Limits Sump Failure f(t)Figure 2.1.3 -Illustration of input variable relationships for gas intrusion analysis Table 2.1.5 -Input variables used primarily in fiber penetration and in-vessel effects analysis Design Input Conservative Preceding Direct-Input Proceeding Direct- Comments Variable Direction Variables Output Variables Fiber 1' Sump Flow Rate, Core Accumulation Penetration Strainer Accumulation, Strainer Area, Accident Time Boil-off Flow 1' N/A Core Accumulation Rate Core '1' Break Location, Spray Core Blockage, Boron Accumulation Flow Rate, Injection Precipitation Flow Rate, Boil-off Flow Rate, Fiber Penetration, Accident Time Page 30 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Design Input Conservative Preceding Direct-Input Proceeding Direct- Comments Variable Direction Variables Output Variables Core Blockage 1 Core Accumulation In-Vessel Failure Core accumulation compared to core blockage acceptance criteria Boron Core Accumulation In-Vessel Failure Core accumulation Precipitation compared to boron precipitation acceptance criteria Core Blockage and Boron Precipitation Analysis CASA Grande Inputs I CASA Grande Calculations

_f(t) = function of accident time Strainer Accurn Spray 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 analysis Page 31 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 2.2 Specific Inputs Used This section documents the specific design inputs used in the CASA Grande analysis.

The actual input decks are provided in Appendix 1.2.2.1 Timing for Key Plant Response Actions There are a number of automated or proceduralized plant response actions that would occur following a LOCA event. The timing for these actions is important for the GSI-191 evaluation since the timing can have a significant impact on a variety of phenomena.

Immediately after a LOCA, several things would occur: 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) the LHSI and HHSI pumps would start injecting water from the RWST into the cold legs after the RCS pressure drops below the shutoff head, and 3) the CS pumps would start injecting water from the RWST into the containment spray headers if the containment pressure rises above 9.5 psig (31). Note that for breaks smaller than 2-inches, the accumulators would not inject since the RCS pressure would not drop below 600 psig before the accumulators are secured, and the sprays would not be initiated since the containment 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 pumps would be manually secured (32; 33). Since this is a continuous action step that is intended to conserve the 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 and large 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 the 30-day habitability limits, and 4) the Technical Support Center (TSC) staff has agreed that the sprays can be terminated (34). Typically, the pressure will drop below 6.5 psig in less than an hour (5), and the iodine 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 be made 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 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months was 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 Analysis RI-GSI191-V03 Revision 2 The timing for switchover to recirculation is dependent on the volume of water in the RWST and the total ECCS and CSS flow rate. Table 2.2.1 shows the sump switchover timing as a function of break size 6 (5).Table 2.2.1 -Sump switchover time Break Size Sump Switchover Sump Switchover (in) Time (S)7 Time (min)1.5" 20,239 337 2" 4,750 79 4" 3,353 56 6" 2,653 44 8" 2,268 38 12" 1,873 31 27.5" DEGB 1,773 30 Switchover 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 after the beginning of the event.2.2.2 Containment Geometry Containment 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 use in 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 the overall frequencies for different break sizes, and a bottom-up evaluation of the relative frequencies at various 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 be conservatively applied to scenarios where some pumps fail to start since a reduction in the overall ECCS and CSS flow rates would delay sump switchover, thereby delaying strainer head loss and core blockage as the pump NPSH margin 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 data spreadsheets.

However, the thermal-hydraulic report (5) presents the values in units of minutes or hours, which introduces some rounding error.Page 33 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 break sizes are based on the values provided in NUREG-1829 (37), which were fit using a bounded Johnson 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 A 0.5 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 of welds as shown in Table 2.2.3 through Table 2.2.10 (7). There are a total of 45 different categories that are considered.

Note that several of the values in this table were based on logarithmic interpolation of the 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 were filtered 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 were linearly interpolated from the 1-5/8-inch, 3-inch, and 7-inch break categories.

The fitted Johnson parameters were determined 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 Analysis RI-GS1291-V03 Revision 2 Table 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 3B System Hot Leg Hot Leg Hot Leg SG Inlet Cold Leg Cold Leg Pipe Size (in) 29 29 29 29 27.5 31 DEGB (in) 41.01 41.01 41.01 41.01 38.89 43.84 Weld Type B-F B-J B-J B-F B-F B-F DM SC, D&C D&C TF, D&C SC, D&C SC, D&C SC, D&C No. Welds 4 11 1 4 4 4 Break 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(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-07 1.50 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-08 2.00 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-08 3.00 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-08 4.00 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-09 6.00 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-09 6.75 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-09 14.00 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-09 20.00 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-09 29.00 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-10 31.50 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-10 41.01 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-10 Page 35 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Table 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 40 System Cold Leg Cold Leg Surge Line Surge Line Surge Line Surge Line Pipe Size (in) 27.5 31 16 16 16 2.5 DEGB (in) 38.89 43.84 22.63 22.63 22.63 3.54 Weld Type B-J B-J B-F B-J BC B-J DM D&C D&C SC, TF, D&C TF, D&C TF, D&C TF, D&C No. Welds 12 24 1 1 7 2 6 Break 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-08 1.50 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-08 2.00 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-08 3.00 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-08 4.00 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-09 6.00 9.95E-11 6.00 9.95E-11 6.00 5.58E-07 6.00 4.26E-09 6.00 6.94E-09 6.75 8.36E-11 6.75 8.36E-11 6.75 4.68E-07 6.75 3.57E-09 6.75 5.82E-09 14.00 3.70E-11 14.00 3.70E-11 14.00 1.18E-07 14.00 9.03E-10 14.00 1.47E-09 20.00 2.11E-11 20.00 2.11E-11 16.00 9.19E-08 16.00 7.02E-10 16.00 1.15E-09 27.50 1.28E-11 27.50 1.28E-11 20.00 6.14E-08 20.00 4.69E-10 20.00 7.65E-10 31.50 1.04E-11 31.50 1.04E-11 22.63 4.77E-08 22.63 3.64E-10 22.63 5.93E-10 38.89 7.60E-12 43.80 6.23E-12 Page 36 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 2.2.5 -Relative frequencies vs. break size for pressurizer line welds (Categories 5A through 5F)Category 5A 5B SC 5D 5E 5F System Pressurizer Pressurizer Pressurizer Pressurizer Pressurizer Pressurizer Pipe Size (in) 6 3 4 3 6 6 DEGB (in) 8.49 4.24 5.66 4.24 8.49 8.49 Weld Type B-J B-J B-J B-J B-i B-F DM TF, D&C TF, D&C D&C D&C D&C SC, TF, D&C No. Welds 29 14 53 4 29 0 Break Size, Break Size, Break Size, Break Size, Break Size, Break Size, X (in) F(LOCAIX)

X (in) F(LOcAX) X (in) F(LOcAX) 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-06 0.75 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-06 1.00 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-06 1.50 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-06 2.00 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-07 3.00 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-07 4.24 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-07 5.66 6.00 6.75 8.49 6.26E-10 5.47E-10 4.16E-10 2.64E-10 5.66 1 2.34E-10 5.66 2.34E-10 1 5.66 6.94E-08 6.00 2.05E-10 6.00 6.06E-08 6.75 1.56E-10 6.75 4.61E-08 8.49 9.89E-11 8.49 2.93E-08 Page 37 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Table 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 6B System Pressurizer Pressurizer Pressurizer Pressurizer Small Bore Small Bore Pipe Size (in) 6 6 4 2 2 1 DEGB (in) 8.49 8.49 5.66 2.83 2.83 1.41 Weld Type B-F B-F BC B-J B-J B-J DM SC, D&C D&C (Weld Overlay) D&C TF, D&C VF, SC, D&C VF, SC, D&C No. Welds _ _0 4 2 2 16 193 Break 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-06 0.75 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-07 1.00 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-07 1.50 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-07 2.00 7.24E-07 1 2.00 2.52E-09 2.00 2.49E-09 1 2.00 6.64E-09 1 1.50 3.08E-07 3.00 3.OOE-07 3.00 [ 1.04E-09 1 3.00 1.03E-09 2.83 3.13E-09 1.99 [ 1.75E-07 4.24 1 1.42E-07 1 4.24 4.94E-10 1 4.24 4.87E-10 5.66 6.83E-08 5.66 2.37E-10 5.66 2.34E-10 2.00 1.73E-07 2.80 8.66E-08 6.00 5.96E-08 1 6.00 2.07E-10 6.75 4.54E-08 6.75 1.58E-10 8.49 2.88E-08 8.49 1.0OE-10 Page 38 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 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 7F System SIR SIR SIR SIR SIR SIR Pipe Size (in) 12 8 8 12 12 10 DEGB (in) 16.97 11.31 11.31 16.97 16.97 14.14 Weld Type B-J B-J B-J B-J BC, B-J B-J DM TF, D&C TF, D&C SC, TF, D&C SC, D&C D&C D&C No. Welds 21 9 3 3 57 30 Break 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-08 0.75 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-09 1.00 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-09 1.50 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-09 2.00 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-09 2.83 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-10 4.00 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-10 4.24 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-10 5.66 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-10 6.00 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-10 6.75 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-10 7.20 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-11 8.49 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-11 10.00 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-11 11.31 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-11 14.14 5.93E-09 16.97 4.05E-09 14.14 7.56E-10 14.14 2.44E-11 14.14 2.44E-11 16.97 5.16E-10 16.97 1.66E-11 Page 39 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 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 7L System SIR SIR SIR SIR SIR SIR Pipe Size (in) 8 6 4 3 2 1.5 DEGB (in) 11.31 8.49 5.66 4.24 2.83 2.12 Weld Type BC, B-J B-J BC BC BC B-J DM D&C D&C D&C D&C D&C D&C No. Welds 42 23 5 9 10 0 Break Size, Break Size, X (in) I X (in)I Break Size, I Break Size, Break Size, Break Size, I F(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-08 0.75 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-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-09 1.00 4.85E-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-09 1.50 3.07E-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-09 2.00 1.65E-09 2.83 6.85E-10 2.83 6.85E-10 2.83 6.85E-10 2.83 6.85E-10 2.83 6.85E-10+ f 4 + 4 4.00 3.49E-10 1 4.00 3.49E-10 1 4.00 3.49E-10 1 4.00 3.49E-10 4.24 3.04E-10 3 4.24 3.04E-10 4.24 1 3.04E-10 4.24 3.04E-10 5.66 1.56E-10 5.66 1.56E-10 1 5.66 1.56E-10 6.00 1.36E-10 1 6.00 1.36E-10 6.75 1.04E-10 6.75 1.04E-10 7.20 9.12E-11 7.20 9.12E-11 8.49 6.58E-11 8.49 6.58E-11 10.00 4.75E-11 11.31 3.74E-11 Page 40 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Table 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 8C System ACC ACC ACC CVCS CVCS CVCS Pipe Size (in) 12 12 12 2 4 2 DEGB (in) 16.97 16.97 16.97 2.83 5.66 2.83 Weld Type B-J B-J BC, B-J B-J B-J B-J DM SC, D&C TF, D&C D&C TF, VF, D&C TF, VF, D&C VF, D&C No. Welds 0 35 15 10 19 47 Break 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-08 0.75 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-08 1.00 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-09 1.50 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-09 2.00 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-09 2.83 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-09 4.00 1.08E-08 1 4.00 1.67E-09 1 4.00 2.02E-10 4.24 9.45E-09 5.66 7.09E-10 5.66 8.55E-11 5.66 4.84E-09 6.00 6.19E-10 6.00 7.47E-11 6.00 4.23E-09 6.80 4.71E-10 6.80 5.69E-11 6.75 3.22E-09 7.20 4.14E-10 7.20 5.OOE-11 7.20 2.83E-09 10.00 2.16E-10 10.00 2.61E-11 8.49 2.04E-09 14.14 1.11E-10 14.14 1.34E-11 10.00 1.47E-09 16.97 7.56E-11 16.97 9.12E-12 4.00 1.26E-09 5.66 5.77E-10 11.31 14.14 16.97 1.16E-09 7.56E-10 5.16E-10 Page 41 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 2.2.10 -Relative frequencies vs. break size for CVCS line welds (Categories 8D through 8F)Category 8D 8E 8F System cvcS Cvcs CvCs Pipe Size (in) 4 4 4 DEGB (in) 5.66 5.66 5.66 Weld Type B-J BC BC DM VF, D&C TF, D&C D&C No. Welds 1 6 4 1 Break 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-08 0.75 1.12E-08 0.75 4.79E-08 0.75 1.12E-08 1.00 7.97E-09 1.00 3.40E-08 1.00 7.97E-09 1.50 5.04E-09 1.50 2.15E-08 1.50 5.04E-09 2.00 2.64E-09 2.00 1.12E-08 2.00 2.64E-09 3.00 1.06E-09 3.00 4.51E-09 3.00 1.06E-09 4.00 5.49E-10 4.00 2.34E-09 4.00 5.49E-10 5.66 2.52E-10 5.66 1.08E-09 5.66 2.52E-10 Page 42 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 2.2.4 Pump State Frequencies The frequency of various pump state combinations was determined based on the STP PRA model as shown 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 to transition to core damage when GSI-191 failure phenomena are considered.

Table 2.2.11 -Frequency of success pump combination states Pump State Case Working Working Working Frequency HHSI Pumps LHSI Pumps CS Pumps (Fear.1)1 3 3 3 2.64E-04 2 3 3 2 3.32E-06 3 3 3 1 7.53E-08 4 3 3 0 9.77E-09 5 3 2 3 3.49E-06 6 3 2 2 4.38E-08 7 3 2 1 9.80E-10 8 3 2 0 1.25E-10 9 3 1 3 3.22E-08 10 3 1 2 3.95E-10 11 3 1 1 7.59E-12 12 3 1 0 9.85E-13 13 3 0 3 <1E-14 14 3 0 2 <1E-14 15 3 0 1 <1E-14 16 3 0 0 <1E-14 17 2 3 3 1.94E-06 18 2 3 2 2.44E-08 19 2 3 1 5.39E-10 20 2 3 0 6.95E-11 21 2 2 3 1.17E-07 22 2 2 2 9.16E-06 23 2 2 1 7.81E-08 24 2 2 0 1.19E-09 25 2 1 3 7.65E-10 26 2 1 2 6.03E-08 27 2 1 1 4.93E-10 28 2 1 0 6.16E-12 Page 43 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Case Working Working Working Pump State HHSI Pumps LHSI Pumps CS Pumps (yeareu)29 2 0 3 <1E-14 30 2 0 2 <1E-14 31 2 0 1 <1E-14 32 2 0 0 <1E-14 33 1 3 3 2.67E-08 34 1 3 2 3.26E-10 35 1 3 1 6.18E-12 36 1 3 0 8.02E-13 37 1 2 3 6.43E-10 38 1 2 2 3.54E-08 39 1 2 1 2.84E-10 40 1 2 0 3.01E-12 41 1 1 3 9.96E-12 42 1 1 2 1.63E-09 43 1 1 1 4.34E-08 44 1 1 0 1.76E-10 45 1 0 3 <1E-14 46 1 0 2 <1E-14 47 1 0 1 <1E-14 48 1 0 0 <1E-14 49 0 3 3 5.84E-11 50 0 3 2 6.24E-13 51 0 3 1 <1E-14 52 0 3 0 <1E-14 53 0 2 3 4.92E-13 54 0 2 2 3.50E-11 55 0 2 1 <1E-14 56 0 2 0 <1E-14 57 0 1 3 <1E-14 58 0 1 2 <1E-14 59 0 1 1 3.89E-11 60 0 1 0 <1E-14 61 0 0 3 <1E-14 62 0 0 2 <1E-14 63 0 0 1 <1E-14 64 0 0 0 <1E-14 Page 44 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSl191-V03 Revision 2 2.2.5 Pool Water Level The active water volume is based on the total volume of water in containment (from the RWST, RCS, and accumulators) minus any water sequestered in inactive regions. The pool volume is equal to the active water volume minus the transitory water volume (i.e., water circulating through the ECCS and CSS piping, containment sprays falling through the air or migrating down to the pool, condensation on walls and other surfaces, water still in the RCS, etc.). These values were calculated at bounding conditions as shown in Table 2.2.12 (14), and the pool volume for small, medium, and large breaks was sampled in CASA Grande based on these ranges.Table 2.2.12 -Range of water volumes implemented in CASA Grande Minimum Maximum Volume Break Size Volume (ft 3) (ft 3)LBLOCA 45,201 69,263 MBLOCA 39,533 69,444 SBLOCA 43,464 61,993 The pool water level is calculated using the following equation: HP° Apool Equation 1 where: H,, = Height above the containment floor at Elevation

-11'3" VPoo, = Pool volume Ap= Pool area The area of the pool at STP is 12,301 ft 2 (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 the larger breaks have a higher peak temperature early in the event and then drop down to a lower overall temperature later in the event (5).Page 45 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 The 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-inch break 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 in Figure 2.2.1 and Table 2.2.13 (5). Note that the initial temperature transient prior to the start of recirculation is not shown in Figure 2.2.1 since temperature only affects models that are important after the start of recirculation (e.g., the NPSH model).Pool Temperature Profiles 200 180 160 pY140 120 100 80-6-inch Break-27.5-inch DEGB 60 40 " 0.1 I 10 Time (hr)100 1000 Figure 2.2.1 -Temperature profiles implemented in CASA Grande Table 2.2.13 -Temperature profiles implemented in CASA Grande Temperature for Temperature for Time (hr) 6-inch Break 27.5-inch DEGB (OF) (*F)0 119.6 119.8113 0.0847 131.2987 213.9295 Page 46 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Temperature for Temperature for Time (hr) 6-inch Break 27.5-inch DEGB (OF) (OF)0.0864 140.1689 242.3104 0.0881 150.3314 255.0268 0.0897 156.124 255.7907 0.0914 159.2343 253.1617 0.0931 162.1567 252.9372 0.0947 164.568 252.539 0.0964 166.6937 251.9023 0.0981 168.5685 250.9733 0.0997 170.2457 249.7169 0.1014 171.7175 245.8894 0.1031 172.9577 235.9856 0.1047 174.0415 224.0051 0.1064 174.957 212.9495 0.1081 175.7084 203.5499 0.1097 176.3081 195.7225 0.1139 177.5299 179.5894 0.1306 164.4935 199.8048 0.1472 132.7076 174.8143 0.1639 124.0848 174.8276 0.1806 123.6914 177.3518 0.1972 123.5988 180.7405 0.2139 123.5641 183.2333 0.2306 123.5529 185.1644 0.2472 124.4938 186.4925 0.2639 127.6399 187.2579 0.2806 129.7484 187.827 0.2972 131.0391 188.1924 0.3139 149.8002 188.4266 0.3306 158.2393 188.5605 0.3472 162.7694 188.5934 0.3639 165.496 188.5042 0.3806 167.3851 188.3375 0.3972 168.6688 189.3187 0.4139 169.7687 189.757 0.4306 170.9814 189.0923 0.4472 171.9993 188.5202 0.4639 172.8771 188.0148 0.4806 173.715 187.5621 0.4972 174.4595 187.4103 0.5139 175.0903 187.0671 0.5306 175.6074 186.733 Page 47 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Temperature for Temperature for Time (hr) 6-inch Break 27.5-inch DEGB (*F) (*F)0.5472 176.0061 186.4249 0.5639 176.2923 186.1559 0.5806 176.4625 186.764 0.5972 176.4855 186.5012 0.6139 176.3916 186.2557 0.6306 176.2055 186.0555 0.6472 175.9468 185.9119 0.6639 175.6184 185.8265 0.6806 175.2411 185.8062 0.6972 174.8243 185.8495 0.7139 174.3902 185.9526 0.7306 173.9374 186.1092 0.7472 173.4284 187.8900 0.7639 172.8459 187.9673 0.7806 172.2319 187.9196 0.7972 171.6143 187.9119 0.8139 171.0143 187.9385 0.8306 170.4548 187.9954 0.8472 169.9507 188.0710 0.8639 169.5034 188.1647 0.8806 169.1086 188.2538 0.8972 168.7661 188.3385 0.9139 168.4824 188.4003 0.9306 168.2551 189.0996 0.9472 168.0847 188.9199 0.9639 167.9707 188.7439 0.9806 167.9020 188.5614 0.9972 167.8705 188.3622 1.0139 167.8665 188.1314 1.0306 167.8947 187.8597 1.0472 167.9451 187.5387 1.0639 168.0131 187.1667 1.0806 168.0978 186.7559 1.3611 170.0607 178.4091 1.6944 170.9606 171.8762 2.0278 171.4105 166.5421 2.3611 170.8721 162.2238 2.6944 169.8110 158.1410 3.0278 168.7942 154.9818 3.3611 168.1132 151.7673 3.6944 165.3090 148.9234 Page 48 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSl191-V03 Revision 2 Temperature for Temperature for Time (hr) 6-inch Break 27.5-inch DEGB (OF) (OF)4.0278 164.1228 146.0834 4.3611 163.0112 143.7967 4.6944 161.4436 141.6054 5.0278 159.9385 139.5251 5.3611 158.1298 137.9892 5.6944 158.4517 136.4819 6.0278 156.5706 134.8865 6.3611 151.6937 136.9000 6.6944 163.7090 136.6489 7.0278 160.9624 135.3569 7.3611 158.1118 134.3103 7.6944 156.1579 133.2941 8.0278 154.6151 132.4453 8.3611 153.2333 131.9467 8.6944 151.9641 132.0536 9.0278 150.8191 132.1915 9.3611 149.7667 131.3055 9.6944 148.7924 130.7946 10.0278 147.8649 130.2765 20.0833 136.208 123.0489 32.0833 129.023 118.1991 44.0833 124.979 114.9095 56.0833 122.145 112.4170 68.0833 120.131 110.4096 80.0833 118.471 108.7290 92.0833 117.316 107.2834 104.0833 116.498 106.0152 116.0833 115.616 104.8855 128.0833 114.710 103.8671 140.0833 113.896 102.9399 152.0833 113.173 102.0890 164.0833 112.521 101.3027 176.0833 111.924 100.5720 188.0833 111.358 99.8894 200.0833 110.859 99.2491 212.0833 110.393 98.6461 224.0833 109.993 98.0763 236.0833 109.577 97.5362 248.0833 109.209 97.0229 260.0833 108.910 96.5339 272.0833 108.593 96.0669 Page 49 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Temperature for Temperature for Time (hr) 6-inch Break 27.5-inch DEGB (°F) (OF)283.3333 108.281 95.6474 297.2222 107.968 95.1520 308.3333 107.710 94.7720 319.4444 107.473 94.4055 333.3333 107.162 93.9649 344.4444 106.943 93.6254 355.5556 106.715 93.2967 369.4444 106.477 92.9000 380.5556 106.250 92.5932 391.6667 106.124 92.2953 402.7778 105.893 92.0057 416.6667 105.666 91.6547 427.7778 105.541 91.3822 438.8889 105.316 91.1168 452.7778 105.193 90.7942 463.8889 105.069 90.5432 475.0000 104.844 90.2982 488.8889 104.725 89.9998 500.0000 104.607 89.7671 511.1111 104.377 89.5396 525.0000 104.366 89.2620 536.1111 104.140 89.0452 547.2222 104.023 88.8328 561.1111 103.905 88.5733 572.2222 103.791 88.3703 583.3333 103.673 88.1712 597.2222 103.566 87.9276 608.3333 103.452 87.7368 619.4444 103.335 87.5494 633.3333 103.145 87.3198 644.4444 103.100 87.1398 655.5556 102.913 86.9628 669.4444 102.868 86.7457 680.5556 102.681 86.5753 691.6667 102.645 86.4076 702.7778 102.525 86.2427 716.6667 102.516 86.0401 CASA Grande evaluates water properties by using the current pool temperature to enter a lookup table based 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 Analysis RI-GSI191-V03 Revision 2 2.2.7 Operating Trains In 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, the three 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 the three 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 design basis analyses).

This is discussed in more detail in Section 5.1.2.2.8 ECCS and CSS Flow Rates The maximum flow rates per train are 2,800 gpm for the low head safety injection (LHSI) flow (41), 1,620 gpm 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 rates are only possible for LBLOCA conditions.

For SBLOCA conditions, containment sprays would not be initiated due to the small increase in containment pressure (5), the LHSI may not inject due to high RCS pressure, and the HHSI flow rate would vary from 0 gpm to 1,620 gpm per train depending on the actual size 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 the actual size of the break. Table 2.2.14 provides a summary of the total SI flow rates for different break sizes based on thermal-hydraulic modeling 9 (5).Table 2.2.14-Total SI flow rates Break Size Nominal Total SI (in) Flow (gpm)1.55" 1,231 2" 2,076 4" 4,120 6" 7,951 8" 10,285 15" 11,780 27.5" DEGB 11,988 The 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 linear 9 These flow rates are based on simulations using nominal operating conditions (i.e., all ECCS trains operating, all fan coolers operating, and nominal CCW heat exchanger temperatures).

Page 51 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 curves (see Equation 2). The reason that the slope changes for breaks greater than approximately 9 inches 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 that limits the total SI pump flow.Sl Flow Rate 14,000 --.. ............y = 8.7063x+ 11649 12,000R2=

1 10,00012,000

__y = 1247.2x /(9.41 in, 11,731 gpm)1 8,000 R 2 =0.9725 4,000 2,013 0 5 10 15 20 25 30 35 40 45 50 Briak Sol ze (in)Figure 2.2.2 -Total SI flow rate vs. break size QTsJ = 1,247.2 gpm/in

Dbreak QrsI = 8.706gp/1 in' Dbreak + 11,649gpm if Dbreak < 9.41 in if Dbreak > 9.41 in Equation 2 where: 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 Analysis RI-GSI191-V03 Revision 2 Note, however, that the total SI flow rate cannot be greater than the maximum capacity of the operating pumps. Therefore, the following criterion is defined for the total SI flow rate based on a maximum 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 3 where: NLHSI = Number of operating LHSI pumps NHHSI = Number of operating HHSI pumps For any given scenario, the flow rate for individual SI pumps within each train can be estimated based on a ratio of the maximum pump capacities, as well as the number of LHSI and HHSI pumps that are running (assuming at least one LHSI pump and one HHSI pump are running).

This is shown in the following equations:

QLHSJ = QTSI 2,800gpm ]t 2,80gpm NLHSI + 1,620gpm.

NHHsJ I [. 1,620gpm I Equation 4 Equation 5 HHS1 T 1 2,800gpm -NLHS, + 1,620gpm -NHHS,]where: QLHSI = LHSI pump flow rate for an individual train QHHSI = HHSI pump flow rate for an individual train If containment sprays are initiated, the flow rate is not dependent on the size of the break. However, it would vary depending on the number of trains in operation.

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

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 Analysis RI-GSI191-V03 Revision 2 Table 2.2.15 -Containment spray flow rates Number of Operating Minimum Spray Maximum Spray Nmray ofupe Flow per Train Flow per Train Spray Pumps (gpm) (gpm)One Train 2,080 2,600 Two Trains 1,932 2,350 Three Trains 1,657 2,060 2.2.9 Qualified Coatings Quantity The total quantity of qualified coatings debris is a function of break size, location, surface area of coated concrete and steel within the ZOI, and coating thickness.

The quantity of qualified coatings debris generated was conservatively calculated for four break sizes as shown in Table 2.2.16 (11). The break sizes 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 to break sizes listed (e.g., the 15-inch quantities can be used for any breaks between 6 and 15 inches in diameter).

To simplify the evaluation, however, the quantity of qualified coatings debris for a 31-inch DEGB was applied to all breaks.Table 2.2.16 -Quantity of qualified coatings debris'0 31-inch DEGB 15-inch Break 6-inch Break 2-inch Break Quantity (Ibm) Quantity (Ibm) Quantity (Ibm) Quantity (Ibm)Qualified Epoxy 105 25 3 0 Qualified IOZ 39 3 0 0 2.2.10 Unqualified Coatings Quantity The total quantity and locations of potentially transportable unqualified coatings are shown in Table 2.2.17 (12). Note that these coatings are listed as potentially transportable since unqualified coatings in upper containment would not transport if they fail after containment sprays are secured, and 10 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 leg break 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 IOZ debris for all other breaks. The epoxy and IOZ debris quantities from the crossover leg break were selected for this evaluation since this represents the maximum total quantity of qualified coatings debris. It is possible that adjusting the quantity of epoxy up by 24 Ibm and the quantity of IOZ down by 31 Ibm could make the answer slightly worse since the density of epoxy is lower than the density of IOZ, and lower density has a conservative effect on head loss. However, since the bounding LBLOCA coatings debris quantities were used for all breaks, the overall treatment of qualified coatings is very conservative.

Page 54 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 unqualified coatings in the reactor cavity would not transport for breaks outside the reactor cavity. This is discussed in more detail in Section 2.2.20 and Section 5.5. The percentages shown in Table 2.2.17 were 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 debris Upper Lower Reactor Total Coatings Type Containment Containment Cavity Quantity (Ibm)Quantity (Ibm) Quantity (Ibm) Quantity (Ibm)Unqualified Epoxy 295 (15%) 36 (2%) 1,574 (83%) 1,905 Unqualified IOZ 305 (83%) 64 (17%) 0 (0%) 369 Unqualified Alkyd 146 (54%) 125 (46%) 0 (0%) 271 Unqualified Baked Enamel 0 (0%) 267 (100%) 0 (0%) 267 Unqualified Intumescent 0 (0%) 2 (100%) 0 (0%) 2 The quantity of unqualified coatings debris that transports to the strainers is dependent on the failure fraction 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 a qualified 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 of the unqualified coatings were conservatively assumed to have a failure fraction of 100%. The intumescent coatings are assumed to be negligible (see Assumption 4.c). The unqualified coatings failure timing 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 fail in 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 Quantity The 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 Analysis RI-GSI191-V03 Revision 2 2.2.12 Latent Debris Quantity The total quantity of latent debris is shown in Table 2.2.19 (43).Table 2.2.19 -Quantity of latent debris 2.2.13 Miscellaneous Debris Quantity The total quantity of unqualified tags, labels, plastic signs, tie wraps, etc. at STP is bounded by a total surface area of 100 ft 2 (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 based on 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 analysis ZOI Radius/ Reference Insulation Type Break Diameter Transco RMI 2.0 (45)Unjacketed Nukon, 17.0 (45)Jacketed Nukon with standard bands Thermal-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 break consists of a larger fraction of fines and small pieces, and debris generated at the outer portion of the ZOI consists of a larger fraction of large pieces and intact blankets.

The fiberglass size distribution that was 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 Analysis RI-GSI191-V03 Revision 2 The Microtherm debris was assumed to fail as 100% fines, but was split into the following categories based on the manufacturing data: 58% SiO 2 , 39% TiO 2 , 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 debris Debris Type Debris Size Macroscopic Microscopic Density Density Fines: 7 Ipm fibers Small Pieces: <6 inches Nukon Large Pieces: >6 inches 2.4 lbm/ft3 175 lbaft 3 Jacketed Large Pieces: Intact Blankets Fines: 7 pm fibers Small Pieces: <6 inches Thermal-Wrap Large Pieces: >6 inches 2.4 Ibmlft 3 159 Ibm/ft 3 Jacketed Large Pieces: Intact Blankets Fines: 6 pm fibers 165 Ibm/ft 3 Microtherm Fines: 20 pIm Si0 2 particles 15 Ibm/ft 3 137 Ib Jft 3 Fines: 2.5 pm TiO 2 particles 262 Ibm/ft 3 Qualified Epoxy Fines: 10 pmn particles 94 Ibm/ft 3 Qualified IOZ Fines: 10 pIm particles

-208 Ibm/ft 3 Fines: 6 mil particles Fine Chips: 0.0156"x15 mil Unqualified Epoxy Small Chips: 0.125"-0.5"x15 mil -124 Ibm/ft 3 Large Chips: 0.5"-2.0"x15 mil Curled Chips: 0.5"-2.0"x15 mil Unqualified Alkyd Fines: 4 -20 pm particles

-207 Ibm/ft 3 Unqualified IOZ Fines: 4 -20 pm particles

-244 Ibm/ft 3 Unqualified Baked Enamel Fines: 4 -20 pm particles

-93 Ibm/ft 3 Crud Fines: 8 -63 pm particles

-325 -556 Ibm/ft 3 Latent Fiber Fines: 7 pm fibers 2.4 lbm/ft 3 175 lbm/ft 3 Dirt/Dust Fines: 17.3 pm particles

-169 lbm/ft 3 Page 57 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 2.2.17 Blowdown Transport Fractions The blowdown transport fractions were calculated based on the break location, size of debris, upper and lower 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, large pieces, and intact blankets.

The Microtherm, qualified coatings, and crud debris would all fail as fine debris 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 above Elevation 19'-0".2. Reactor cavity: Weld locations inside the primary shield wall.3. Below Steam Generator Compartments:

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

Weld locations inside the pressurizer compartment (excluding the surge 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 Analysis RI-GSI191-V03 Revision 2 Table 2.2.22 -Blowdown transport fractions according to break location Debris Type and Blowdown Transport Fractions Break Location Size Upper Lower Remaining in Containment 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% NA Generator Small LDFG 21-50% 50-79% NA Compartments Large LDFG 0% 100% NA Fines 70% 30% 0%4.mpresi Small LDFG 26-66% 11-28% 6-63%Large LDFG 16-26% 1-11% 63-83%Fines 70% 30% NA 5Presuize Small LDFG 3-36% 64-97% NA Large LDFG 0% 100% NA Fines 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 of debris, 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 the break, 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 before the sprays are secured.Page 59 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 2.2.23 -Washdown transport fractions according to spray initiation Sprays Washdown Transport Fractions Initiated?

Debris Type Washed Down in Washed Down inside Annulus Secondary Shield Wall Fines 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, the volume of the inactive cavities and sump cavities, and the pool volume at the time when these cavities would be filled. The appropriate pool fill transport fractions are shown for each break location and debris size in Table 2.2.24 (23).Table 2.2.24 -Pool fill transport fractions according to break location Break Location Debris Pool Fill Transport Fraction Type Each Sump Inactive Cavities Breaks 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 of differing 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). Note that the unqualified epoxy coatings in the reactor cavity would not transport for any breaks outside the reactor cavity. In the case of a reactor cavity break, the transport fractions for the unqualified epoxy in the 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 Analysis RI-GS1191-V03 Revision 2 Table 2.2.25 -Recirculation pool transport fractions according to break size and location (insulation)

Recirculation Transport Fractions Break Break Debris in Washed in Washed inside Location Size Lower Annulus Secondary Containment Shield Wall Fines 100% 100% 100%SBLOCA Small LDFG 27% 20% 27%1: Steam Generator Large LDFG 0% NA NA Fines 100% 100% 100%CBLOCA Small LDFG 64% 58% 64%LB LOCA Large LDFG 0% NA NA 2: Reactor SBLOCA Fines 100% 100% 100%Cavity MBLOCA Small LDFG 64% 58% 64%LBLOCA Large LDFG 0% NA NA Fines 100% 100% 100%3: Below SBLOCA Small LDFG 27% 20% 27%Steam Large LDFG 0% NA NA Generator Fines 100% 100% 100%Compartments MBLOCA Small LDFG 64% 58% 64%LBLOCA Large LDFG 0% NA NA 4: Pressurizer SBLOCA Fines 100% 100% 100%Compartment MBLOCA Small LDFG 61% 55% 16%LBLOCA Large LDFG 0% NA NA 5: Pressurizer SBLOCA Fines 100% 100% 100%Surge Line MBLOCA Small LDFG 61% 55% 16%LBLOCA Large LDFG 0% NA NA 6: RHR SBLOCA Fines 100% 100% 100%Compartments MBLOCA Small LDFG 61% 55% 16%LBLOCA Large LDFG 26% NA NA SBLOCA Fines 100% 100% 100%7: Annulus MBLOCA Small LDFG 61% 55% 16%1 LBLOCA Large LDFG NA NA NA Page 61 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Table 2.2.26 -Recirculation transport fractions according to break size and location (coatings, latent debris, crud, dirt/dust)

Recirculation Transport Fraction Break Debris in Washed Washed Break Location Bre Debris Type Size Lower in inside Size Containment Annulus Secondary Shield Wall Qual. 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 Erosion Small or large pieces of fiberglass debris retained on grating in upper containment would be subject to erosion 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 fraction for fiberglass debris retained in upper containment would be 1%, and the average erosion fraction for Page 62 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 fiberglass debris that settles in the recirculation pool would be a value below 10% as documented in Table 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 the pool fill phase (23). However, the erosion of fiberglass debris in the pool would be a more gradual process. As shown in Table 6.6 of the STP debris transport calculation, the majority of erosion would occur 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 of the event (23).2.2.22 Strainer Geometry The strainers at STP are PCI Sure-Flow stacked disk strainers.

The gap thickness between the strainer disks is 1 inch (47). The total surface area of each strainer is 1,818.5 ft 2 per train, the interstitial volume is 81.8 ft 3 per train, and the circumscribed strainer area is 419.0 ft 2 per train (48). The height of the strainers above the containment floor is 28.5 inches 1 1 (49), and the center of the strainers is 15.4 inches above the floor (49). The height of each strainer module is 25 inches, and the width of each module is 28 inches (47). The bottom of the strainer modules are 2.25 inches above the floor (47). Since the core tube is at the center of the strainer and has a diameter of 10-7/8 inches (47), the minimum water level required to flow through the bottom of the strainer core tube and fill the sump pits is 10 inches. The strainer 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 the following 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 since the strainer height is used to calculate the average submergence within the degasification model. Because the average strainer height was overestimated, the average submergence was reduced and the gas void fraction was overestimated.

Page 63 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 L =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 6 1 ft=535min.1

=44.6ft 12 in Figure 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 during outages. 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 Analysis RI-GSI191-V03 Revision 2 Figure 2.2.4 -STP strainer Photo 2 (after protective grating was installed)

Figure 2.2.5 -STP strainer Photo 3 Page 65 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Figure 2.2.6 -STP strainer Photo 4 2.2.23 Clean Strainer Head Loss Clean strainer head loss (CSHL) is a function of the strainer geometry, sump flow rate, and pool temperature.

The maximum CSHL measured under bounding test conditions is 0.220 ft based on a test module 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 Margin The NPSH required for the HHSI, LHSI, and CS pumps is 12 ft (25). The difference in elevation between the containment floor and the pump impellers is 25.65 ft for the HHSI pumps and 25.83 ft for the LHSI and 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). The definition 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 of 91.44 ft 2 (53) and the full strainer surface area of 1,818.5 ft 2 (48).Page 66 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 2.2.27 -ECCS sump suction pipe diameters Pipe Segment Diameter (ft)AB 1.27 BC 0.99 BD 1.27 DE 0.84 DF 1.27 FG 0.99 2.2.25 Strainer Structural Margin The 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, partial transport will occur when the Froude number is greater than 0.35, and full transport will occur when the Froude number is greater than 1.0 (57).2.2.28 Pump Gas Limits The 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 based on prototype strainer module testing (60). The filtration efficiency can be described as shown in Equation 7.f M Ms + b f(WS) = if(Mc) + (1 -f (Ml)) ( 1 -e-Cms-m'))

if 0 < Ms <_ Mc if Ms > Mc Equation 7 Page 67 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 where: f = Filtration efficiency Ms = Mass of fiber on strainer m, b, Me, 6 = Fitted filtration parameters The range of filtration coefficients from the test are shown in Table 2.2.28 Table 2.2.28 -Fitted filtration parameters for test module mtest (g"') b 6 test (g-1) Mctest (g)Lower 0.0003391 0.656 0.001308 880 Center 0.0003263 0.689 0.001125 930 Upper 0.0003723 0.706 0.031787 790 To 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 be scaled proportional to the scaled strainer area. Given a test module area of 91.44 ft 2 and a strainer area of 1,818.5 ft 2 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 t2 mstrainer

= m m: retest S Amodule 91.44ft 2 15strainer

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

= Mc,test A' odueA Mc,test 91.44ft 2 Equation 8 Equation 9 Equation 10 Table 2.2.29 -Fitted filtration parameters for each ECCS strainer m (Ibm,-) b 6 (Ibm,-) Mc (Ibm)Lower 0.007741 0.656 0.02968 38.5 Center 0.007449 0.689 0.02511 40.7 Upper 0.008499 0.706 0.7259 34.6 The 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 Analysis RI-GSI191-V03 Revision 2 Table 2.2.30 -Fitted shedding parameters v rj (min" 1)Minimum 0.0096 0.0082 Average 0.0152 0.0313 Maximum 0.0196 0.0546 2.2.30 Decay Heat Curve As shown in Table 2.2.31, the decay heat generation rate was taken from the 1979 ANS plus 2 sigma uncertainty (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 Heat Generation Rate (Btu/Btu)10 0.053876 15 0.050401 20 0.048018 40 0.042401 60 0.039244 80 0.037065 100 0.035466 150 0.032724 200 0.030936 400 0.027078 600 0.024931 800 0.023389 1,000 0.022156 1,500 0.019921 2,000 0.018315 4,000 0.014781 6,000 0.013040 8,000 0.012000 10,000 0.011262 15,000 0.010097 20,000 0.009350 Page 69 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Time Decay Heat Generation Rate (Btu/Btu)40,000 0.007778 60,000 0.006958 80,000 0.006424 100,000 0.006021 150,000 0.005323 400,000 0.003770 600,000 0.003201 800,000 0.002834 1,000,000 0.002580 2.2.31 Core Blockage Debris Limits Based on conservative testing by the PWR Owner's Group (PWROG), debris loads greater than 15 grams per 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 Analysis RI-GS1191-V03 Revision 2 3 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) is equivalent 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) would be significantly reduced for low power or shutdown modes.b. It was assumed that containment would be isolated at the time of an accident.

Although containment 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. In general, assuming a higher pool temperature at the beginning of the event is also conservative since corrosion and dissolution would be higher, NPSH margin would be lower, and degasification would be higher.c. Containment pressure was assumed to be 14.7 psia for all cases except when the pool temperature is higher than the boiling temperature.

In cases where the pool temperature is above 212 °F, the containment pressure was assumed to be equal to the saturation pressure.

This is a conservative assumption since neglecting containment overpressure reduces the ECCS pump NPSH margin and increases the amount of degasification 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 is consistent with the deterministic debris generation calculation (43) and the guidance in NEI 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 timing and 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 debris bed on the strainer resulting in lower head losses.g. The only reflective metal insulation (RMI) in containment at STP is stainless steel Transco RMI that is installed on the reactor vessel (43). It was assumed that the RMI can be neglected in the STP GSI-191 analysis.

This is a reasonable assumption since 1) the quantity of RMI debris would be relatively small since the ZOI size for Transco RMI is only 2.0D (45), 2) stainless steel foils are chemically inert, 3) the majority of RMI debris generated would not reach the strainers since the transport paths from the reactor cavity 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 Analysis RI-GSI191-V03 Revision 2 to transport of the relatively heavy RMI debris (65), and 4) RMI has a minor effect on debris head loss for strainers that are sitting above the floor elevation (RMI can actually reduce 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 various break ZOIs can be neglected.

This is a reasonable assumption since there are only a few pipes with lead blankets at STP, a limited number of breaks would be close enough to these pipes to damage the lead blankets, and the lead debris that is generated would not be likely to transport or cause any significant problems.

Note, however, that the fiberglass 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 the maximum 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 spray flow rate for two train operation, and the minimum spray flow rate for three train operation is 80% of the maximum spray flow rate for three train operation (see Section 2.2.8).j. It was assumed that switchover to hot leg injection would occur between 5.75 and 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months 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 plant personnel, 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 the overall GSI-191 evaluation including chemical effects (material release rates and solubility limits), debris transport, strainer head loss, NPSH margin, degasification, and in-vessel effects. For some aspects of the analysis, a higher temperature profile is more conservative (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 and debris transport).

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

However, several aspects of the evaluation were analyzed independently and implemented in CASA without a direct link to the temperature 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 rates and the solubility limits. Release rates increase with increasing temperature, and solubility decreases with decreasing temperature (with the exception of products that exhibit retrograde solubility), so it is difficult to say which direction is conservative overall for chemical effects. However, since the STP CHLE 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 in Section 5.6.3, chemical precipitation was assumed to occur when the pool temperature 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 Analysis RI-GSI191-V03 Revision 2 II. The debris settling and tumbling velocities are lower at lower temperatures due to the higher viscosity, so minimizing the temperature profile would be conservative.

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 room temperature conditions (23).Ill. The clean strainer head loss and conventional debris bed head loss are higher at lower temperatures, so minimizing the temperature profile would maximize the overall strainer head loss. Note, however, that a single bounding value 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 the temperature profile would be conservative.

However, the strainer structural margin is lower than the NPSH margin for essentially the entire event except very 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, which increases at lower temperatures, so these two factors are competing.

In general, the void fraction does not change significantly over the range of prototypical long-term temperature profiles where the debris bed head loss would 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 failed unqualified coatings).

Although additional sensitivity analysis would be necessary to fully understand the effects of the temperature profile on failures 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 debris transport to the core for a cold leg break during cold leg injection) increases with increasing temperature, so a higher temperature during the cold leg injection period is conservative.

However, this effect has been decoupled from the temperature profile implemented in CASA since the SI flow entering the 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 6 inches can be conservatively represented by a nominal 6-inch break containment pool temperature profile, and all large breaks greater than 6 inches can be represented by a nominal 27.5-inch DEGB temperature profile. These two temperature profiles tend to maximize the temperature early in the event (i.e., the first 1-2 hours), and then minimize the temperature for the remainder of the event (5). This is generally conservative since the strainer debris head loss and chemical precipitation timing are the most significant parameters affected by the temperature profile and will be maximized 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 the Page 73 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 simulations to the nominal component cooling water (CCW) temperature at 30 days-86 °F (5). This minimizes the long-term temperature profile since the containment pool temperature will never drop below the CCW temperature and is likely to be higher than the 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 to predict 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 (with no other failures) is assumed to be identical to a failure of the LHSI and CS pumps in Train C (with no other failures).

This is a reasonable assumption since the strainer area and pump flow rates are essentially the same for all three trains, and the trains are physically 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 the same combination of pumps failing in separate trains. For example, given a scenario where one LHSI, one HHSI, and one CS pump all fail, the scenario where all three pumps fail in Train A is worse in terms of strainer failures than the scenario where the HHSI and LHSI pumps fail in Train A and the CS pump fails in Train B. The total CS and SI flow would be the same for these two cases. In the first case, however, Trains B and C would be operating at maximum flow, whereas in the second case, only Train C would be operating at maximum flow and the remaining flow would be split between Trains A and B. 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 vessel failures 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 is more likely for a full train to fail than it would be for an LHSI pump, HHSI pump, and CS pump to fail in separate trains 1 3 , 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 pump and 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 all three pumps in one train is over two orders of magnitude more likely than a random failure of one HHSI pump and one CS pump in any of the trains).Page 74 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 3.1 -Strainer debris accumulation and approach velocity comparison 1 4 Scenario 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/s Train B Debris Accumulation 50% 31%Approach Velocity 0.0086 ft/s 0.0054 ft/s Train C Debris Accumulation 50% 50%1 Approach Velocity 0.0086 ft/s 0.0086 ft/s c. It was assumed that the failure of various combinations of pumps can be bounded in terms of strainer failures by other scenarios that have an equal or higher approach velocity and an equal or higher debris accumulation on any one strainer.

This assumption is appropriate based on the conservative assumptions that failure of one pump or train is equivalent to the failure of all pumps and trains (see Assumption 12.a through Assumption 12.c). This is illustrated in Table 3.2 using CS pump failures as an example. In this example, Train C in Scenario 3 has the most limiting conditions with the combination of highest debris accumulation and highest approach velocity, and therefore would be the most likely fail.Table 3.2 -Strainer debris accumulation and approach velocity comparison for CS pump failures 1 4 Scenario 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/s Train 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/s Train 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/s d. It was assumed that the failure of various combinations of pumps can be bounded in terms of in-vessel failures by other scenarios that have a higher flow split to the core with an equal number of trains in operation.

The flow split to the core is dependent on the flow split to the SI pumps vs. the total sump flow rate (Qsl/Q.tota), and the boil-off flow split to the core vs. the total SI flow rate for cold leg breaks (QO/boiQS.).

An example calculation is illustrated in the table below.14 Calculated using a strainer area of 1,818.5 ft 2 per strainer and flow rates of 2,800 gpm per LHSI pump, 1,620 gpm per HHSI pump, and 2,600 gpm per CS pump. Note that changes in the flow rates due to break size or other effects would change the specific percentages, but the relative effects between break cases would be consistent with the values shown above.Page 75 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 3.3 -Core debris accumulation for various pump failures's Scenario 1 Scenario 2 Scenario 3 Scenario 3 Scenario 3 Flow 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 be explicitly linked to the PRA equipment failure probabilities.

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

However, rather than modeling the explicit equipment failure scenarios postulated in the PRA, the range of equipment failures was considered in the development of the containment pool temperature profiles (5).f. It was assumed that pump configurations with a frequency less than 2E-09/yr would result 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 the epistemic uncertainty associated with LOCA frequency estimates.

Based on an evaluation of the relative merits of the arithmetic mean and geometric mean, the geometric mean aggregation was determined to be more representative of the overall consensus of the panelists (68).b. It was assumed that the current-day LOCA frequencies are more appropriate to use for this 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 would be significantly smaller than weld locations, and would not generate significantly different quantities of debris from the weld breaks. It was also assumed that isolable breaks can be excluded from the evaluation since isolable breaks would not lead to recirculation.

d. Linear-linear interpolation of top-down LOCA frequencies from N UREG-1829 was used to preserve uniform probability density between expert elicitation points provided in 15 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 the flow rates due to break size or other effects would change the specific percentages, but the relative effects between 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 Analysis RI-GSI191-V03 Revision 2 the tables. Uniform probability density avoids any attribution of behavior that the panel did 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 assign relative frequencies to the individual weld locations can be linearly interpolated.

This does 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 a reasonable approach given an incomplete understanding of the physical behavior of the LOCA 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 with 3 welds modeled on 1-inch pipes and 32 welds modeled on 0.75-inch pipes (4). It was assumed that the overall break frequency for the 193 welds can be distributed across the 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 with respect to GSI-191 phenomena.

Also, since the 35 welds that were modeled are scattered around containment, it is not likely that the weld locations that were not modeled would have any significant differences with respect to the quantity of debris that 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 was assumed that the weld count in the CAD model (4) is more accurate than the weld count in the LOCA frequency report (7) in any cases where there are deviations (see Section 5.3.2). 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 at the beginning of the event. This is a conservative assumption since the majority of the miscellaneous 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 and can be excluded from the analysis.

This is a reasonable assumption since the total transportable 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 higher temperatures, and calcium precipitates are not expected to form in large quantities for most of the scenarios evaluated (20). Note that the temperature profiles used in the CASA 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 Analysis RI-GSI191-V03 Revision 2 6. Debris Transport Assumptions

a. It was assumed that there would be no significant transport of intact blanket debris. This is a reasonable assumption since the intact blankets are large pieces that would be easily held up on structures and would be too heavy to transport readily in the containment 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 the miscellaneous debris would transport to the strainers at the start of recirculation.

This is a 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 the event. This assumption results in an increased transport fraction to inactive cavities, but neglects any retention of latent debris above the pool where much of it could be shielded from containment sprays.d. It was assumed that debris washed down from upper containment reaches the pool after the inactive and sump cavities are filled, but before recirculation is initiated.

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

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 be uniformly distributed in the pool. This is a reasonable assumption since the fine debris in lower containment prior to the start of recirculation would be well mixed in the pool as it 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 the pool.g. It was assumed that fiberglass debris erosion caused by flow in the pool or by containment 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 be represented by the bounding transport fractions for an LBLOCA in the steam generator compartments.

This is a reasonably conservative recommendation based on the following points (see Section 2.2.17 through Section 2.2.21): I. Worst case values were selected from the transport fraction ranges for steam generator compartment blowdown and washdown.II. Transport fractions for LBLOCAs are equivalent or bounding for MBLOCAs and SBLOCAs.Page 78 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Ill. Sprays are always assumed to be activated (even for SBLOCAs) in the implemented transport fractions.

IV. Unqualified epoxy coatings in the reactor cavity never transport (even for reactor 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 the implemented transport fractions.

VI. Steam generator compartment blowdown transport fractions for small and large pieces of fiberglass are not necessarily bounding for other break locations.

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

VIII. Inactive cavity transport fractions for breaks inside the secondary shield wall are bounding compared to breaks in the annulus.IX. Steam generator compartment recirculation transport fractions are bounding for 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 block strainer 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 to acrylic coatings.

It was also assumed that non-coatings particulate debris would have a packing fraction similar to iron oxide sludge. These assumptions are based on engineering judgment due to limited data.c. It was assumed that a fiber bed of at least 1/1 6 th of an inch is necessary to capture chemical precipitates.

This is a reasonable assumption since a thinner debris bed would not fully cover the strainer and would not support appreciable head losses due to chemical debris.d. It was assumed that 100% of the transported particulate debris would be captured on the 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 criteria that were implemented in CASA are independent of the particulate quantity, this assumption is conservative.

e. It was assumed that the debris on the strainers would be homogenously mixed. This is a reasonable assumption since much of the debris would arrive at the strainer simultaneously.

f. It was assumed that fiberglass debris would accumulate uniformly on the strainers with a density of 2.4 Ibm/ft 3.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 Analysis RI-GSI191-V03 Revision 2 (70). For the purposes of developing the strainer loading table (see Section 5.6.2), the pool height was assumed to always be sufficient to allow debris to accumulate on the top of the strainer, but debris accumulation on the bottom of the strainer was limited to 2 inches to account for the height of the strainer above the floor. Assuming that the pool height is greater than the debris accumulation on the top of the strainer is not necessarily accurate for cases where the water level is relatively low and the debris load is large. However, for the majority of cases, the debris load would not be large enough to 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's Law essentially states that the solubility of a gas in a liquid is proportional to the partial pressure of the gas above the liquid. At the equilibrium saturation level, the number of gas molecules moving into and out of solution is constant.

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

Due to the short time 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 of solution 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 to be applicable for calculating the air released.b. It was assumed that the temperature upstream and downstream of the strainers is constant.

This is a reasonable assumption since the water temperature would not change significantly as the water flows through the strainer.c. It was assumed that the air in containment would be essentially the same as atmospheric air. For example, the addition of nitrogen from the accumulators and the formation of hydrogen due to chemical reactions in the containment pool were not considered.

These and other sources of non-condensable gasses in containment are likely 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 since the 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 ECCS strainers is 100%. This is a reasonable assumption since the gas bubbles that are formed would be fully surrounded by water. Note also that this assumption is conservative since maximizing the humidity downstream of the strainer minimizes the partial pressure of the air, and therefore reduces the equilibrium concentration of dissolved air downstream of the strainer.16 Note that a lower relative humidity in containment would increase the concentration of dissolved air in the containment 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 Analysis RI-GSI191-V03 Revision 2 g. It was assumed that the average submergence depth (from the surface of the pool to the 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 the ECCS pumps. This is a conservative assumption since it maximizes potential pump failures 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 fraction downstream of the sump strainers.

This is a conservative assumption since it neglects the 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 the debris initially accumulates.

This is a reasonable assumption since the strainers are not located in the immediate vicinity of any potential breaks where the break flow could impinge 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. CS pumps (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 would easily transport with the flow.c. It was assumed that all debris that penetrates the strainer and transports through the core 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 (either through the containment sprays or directly out the break) would immediately be transported back to the containment pool. This is a conservative assumption since it neglects potential hold-up of debris in various locations and neglects the time that it would 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 to the core) during the hot leg injection phase. This is a reasonable assumption since debris blockage 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 was assumed that the RCS pressure is 14.7 psia, and the SI flow entering the reactor vessel is saturated liquid (i.e., 212 'F). This assumption conservatively maximizes the boil-off flow rate since a lower inlet temperature and/or a higher RCS pressure would increase the enthalpy required to boil the water.11. Boron Precipitation Assumptions

a. It was assumed that the current STP design basis evaluation methodology used to calculate the required hot leg switchover timing is appropriate with the exception of GSI-191 related phenomenon (i.e., formation of a debris bed on the core). This is an Page 81 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 appropriate 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 for GSI-191 closure.b. It was assumed that for a medium or large cold leg break during cold leg injection, a fiber debris load of at least 7.5 g/FA would form a debris bed that would prevent the natural 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 cause significant blockage concerns.c. It was assumed that boron precipitation would not be an issue for small breaks. This is a reasonable assumption since natural circulation would maintain a relatively steady concentration 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 break sizes). 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 hot leg breaks. This is a reasonable assumption since at least one train would be injecting in the cold leg throughout the event. This flow would pass through the core and maintain a relatively steady concentration of boron. Even if significant core blockage occurs, some flow 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 is equivalent to the failure of all pumps in all trains. This is a conservative assumption since the NPSH margin is not the same for all pumps, and if one pump failed, the sump flow rate would be reduced making it less likely that a second pump would fail. Also, since the trains are independent, failure of one train would not affect the other trains except that suspended debris in the pool after the failure would only accumulate on the remaining trains that are still active.b. It was assumed that structural failure of one strainer would allow sufficient debris ingestion 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 of debris ingested.c. It was assumed that failure of one pump in any train due to excess air ingestion is equivalent to the failure of all pumps in all trains. This is a conservative assumption since one train or one pump in a given train may ingest significantly more air than the other trains 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 Analysis RI-GSI191-V03 Revision 2 4 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 they exist, conservative assumptions are adopted in deterministic models. Insulation debris quantities are calculated 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 pool volume, 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 compared against the minimum NPSH margin, which is calculated based on maximum flow rate and maximum pool temperature.

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 result is compounded by the numerous conservatisms introduced in each portion of the analysis.

Also, as identified above, several conservatisms are mutually exclusive, such as the use of a minimum water level for debris transport and a maximum pool volume for chemical precipitation, or use of a minimum temperature 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 reduce the level of conservatism.

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

To calculate the probability associated with core damage or a subsequent 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 of thousands of different scenarios).

Rather than analyzing these scenarios in a conservative and bounding manner 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 be true for parameters that have a tight range between the minimum and maximum values or for Page 83 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 parameters where the results of the analysis are relatively insensitive to large variations in the parameter values). However, some input variables may require probability distributions.

Figure 4.1 shows an example probability distribution for water volume. Depending on the specific analysis, either the calculated minimum or calculated maximum water volume would be used as an input for a deterministic evaluation.'

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

.0 2 L Calculated minimum Actual----- -- minimum Calculated Actual maximum maximum (conservative)

WaterVolume Figure 4.1 -Example of realistic probability distribution for an input variable In addition to using realistic inputs, it is also important to perform a time-dependent evaluation to capture 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 pumps or switching over to hot leg injection, etc.For a risk-informed evaluation, the uncertainties associated with the various input parameters and models 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 or maximum water volume calculation.

This may provide significant improvement, but using a bounding value for the water 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 Analysis RI-GSI191-V03 Revision 2 The 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 the plant-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 large early release frequency (LERF). If the ACDF and ALERF values are within Region 3 as defined in Regulatory Guide 1.174 (73), the risk associated with GSI-191 is considered very small. If the ACDF and ALERF values are within Region 2 or Region 1, the risk is more significant, and would require more extensive 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 Analysis RI-GSI191-V03 Revision 2 Risk-Informed Method Realistic/probabilistic" Inputs.Methods" Acceptance Criteria Containment CAD LOCA Frequencies Model/Input Development Model Frequency estimates Perform testing or analysis Detailed model of for break sizes from to develop realistic inputs, insulation, structures

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

Compare each sequence to appropriate acceptance criteria and summarize results as a failure probability for S/M/L LOCA categories.

Repeat analysis for each possible equipment configuration.

PRA P Calculate ACDF and ALERF for Within RGPerform plant current configuration vs. 1.174 Region No modifications hypothetically perfect cost, dose, and configuration with respect to maintained?

CDF reduction ECCS performance Figure 4.2 -Risk-informed GSI-191 resolution path Page 86 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 4.1 GSI-191 Analysis Steps The 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 to ECCS 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 concrete structures, 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 break location, based on the following steps: a. Determine the relative probability of breaks in each weld category based on specific degradation mechanisms and distribute total LOCA frequency to each weld location based 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 the following steps: a. Determine the appropriate ZOI size for each material based on the destruction pressure and break size.b. Determine the appropriate size distribution for each type of insulation debris based on the 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 and logs. 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 Analysis RI-GSI191-V03 Revision 2 b. Calculate debris transport during the blowdown phase based on the type and size of debris 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 of debris 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 of debris in lower containment at the end of the blowdown phase, the break and spray flow rate, the cavity volumes below the containment floor elevation, and the pool volume at the time when the cavities would be filled.e. Calculate debris transport during the recirculation phase based on the type and size of debris in the pool, the initial debris distribution at the beginning of recirculation, the pool 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 on the 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. This includes the following steps: a. Determine the clean strainer head loss.b. Calculate the conventional head loss due to fiber and particulate debris based on the flow 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 gas void 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 suction piping 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 Analysis RI-GSI191-V03 Revision 2 b. 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 prior to hot leg injection.

b. Determine boron precipitation acceptance criteria based on debris load necessary to block 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 of parameter(s).

4.2 Structured

Information Process Flow The basic event for a LOCA scenario consists of a single accident progression that is initiated by a broken pipe and continues for 30 days. The following outline provides a high level description of the process flow for evaluating independent LOCA scenarios.

Unlike predictive physics models (like RELAP), which enumerate field equations and constitutive relationships, CASA Grande embodies only mass conservation 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 profiles developed from the thermal-hydraulic modeling).

In this respect, CASA Grande is primarily an uncertainty propagation tool, but the timeline of the accident progression is determined by tracking debris through the system circulation history. The timeline supports externally calculated parameters such as decay heat, pool temperature, operational configurations, chemical product formation, and coatings degradation.

It also provides a basis for comparison to time-dependent performance metrics like 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 state determines 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 relative frequencies reflect susceptibility to failure.3. Randomly select a specific weld from this type/case assuming equal probability among all welds of the same type/case.

The weld location defines P(x,y,z), whether it is a hot leg or cold leg Page 89 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 break 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 the only feature that is credited for shielding insulation from potential damage since pipes and large equipment 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 is consistent with NUREG-1829:

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

The designation of SBLOCA, MBLOCA, or LBLOCA becomes an explicit correlation for many following physical variables.

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, small pieces, 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: K denotes insulation products, !F denotes fiber-based insulation, and £ denotes all types of debris including 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 for insulation

k. Figure 4.2.1 is an illustration that shows the nomenclature of damage for a hypothetical 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 Analysis RI-GS1191-V03 Revision 2 Figure 4.2.1 -Illustration of a hypothetical DEGB spherical ZOI truncated by a wall 7. 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 to obtain the amount of debris in each damage radius and debris size (i,],k), and convert volume to mass:=k": P k diý. a Img e(e) n Viksulaton)

\ Wconcrete Equation 12 Here, the "\Wconcrete" designates exclusion of those insulation targets not damaged due to structural concrete blocking the break jet.Page 91 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 9. Apply transport logic to obtain all ZOI-generated debris mass arrival at the pool as a function of break size and compartment location.

Complex transport logic is represented here via the operator Ftronsport:

mP(O) = Ftransport (9 M Equation 13 The transport logic captures things like erosion of fibers from large pieces to fines in transforming 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 is initially resident on each strainer, in addition to all other debris constituents that arrive over time: mfk(O) = mlk(0) Equation 14 12. At each time t, assume homogenous mixing in the pool: Cf,1k(t) = m.j,k(O)/V (t) Equation 15 While this form is never used explicitly, it is helpful to think about debris mixing, transport, and accumulation in terms of concentration.

13. Solve coupled differential equations for mass in the pool, mass on the strainer, and mass on the core (see Figure 4.2.2 and Figure 4.2.3 for the nomenclature setting): dt- d d mcore(0 Vk EL tmP(0) = SA,)-, -Mkt) -m (t IV t k d k ) e=A,B,C .d kE TF dmk(t) :fyZmi(t))yQ 0 M)m (t) -ivme(t), Vk EL Equation 16 dt (t) = flr k ) rn(tt_) Vk k 1 d core~Mk M~t = A7 yf mi$(t) kE_dt k e=A,B,C Page 92 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 where sources Sk(t) of debris type k can be time-dependent, flow split X is the fraction of ECCS injection that passes through the fuel, and flow split y is the fraction of total strainer flow that is injected.

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. For cold 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 and the masses are indexed by debris type k E £. That said, the other indices matter in implementation.

For example, the last term in Equation 16 is only present when the k index indicates 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 screen Page 93 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 (LLLL Figure 4.2.3 -Illustration of the flow paths in the reactor vessel 14. 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 17 where the function H is given by NUREG/CR-6224 with arguments given by the vector me(t) of m (t) for all k E £, and velocity via the flow rate Qe(t), where N(5,1) is a truncated random variable with a mean of 5 and unit variance, and where Dclh(t) = H 1 , 8(t) < 1/16" or T(t) > N(140,5)1 E, otherwise Equation 18 Here, the chemical head loss 41ch takes a value of 1 if the thickness is below 1/1 6 th of an inch or the 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 denoted by E.15. Compare time-dependent head loss to time-dependent NPSH margin and record the scenario as a failure if: Page 94 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 max[APe(t)

-NPSH,argin(t)]

> 0 t,,e Equation 19 In other words, a failure is recorded for this scenario if anywhere along the 30-day time history the head loss exceeds the NPSH margin for any strainer -e = A, B, C. The strainer head loss and NPSH margin and other sump failure criteria are illustrated in Figure 4.2.4.V Pool Free Surface, PC L Failure also occurs if R..exceeds the mechankal strength of the fi1ter screen PrMs deb byt tot?lossl prMs iure dropthrough the -V z bediscompensated

, he water column down e pump (HW) less flow it (FL) and less vapor z= z sure (VP) .z Pumps are operable so long as: APbe <: NPSHmargin Safety injection pumps (two in a train) are located below the sump to ensure adequate NPSH avap Figure 4.2.4 -Illustration of sump failure criteria 16. Compare time-dependent head loss to the strainer structural margin and record the scenario as a failure if: maxAPeO(t)

> AP,,Cjh t,ie Equation 20 where APmecpl is the design strainer structural strength in terms of pressure drop across the strainer.Page 95 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 17. Given time-dependent head loss, calculate time-dependent gas evolution and record the scenario as a failure if: max FvOid (AP" (t)) > 2% Equation 21 18. For cold leg breaks, compare the time-dependent fiber accumulation on the core against the assumed 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 boron precipitation 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 ECCS performance during the recirculation phase.ECCS ScreenHole

(. (2 PIs)Particulate debris (chemical, other) l in the debris flitered in the screen increases bed causes 0 pressure drop pressure dro Bto1 miyfr FV~ i.the fraction of dowrstreamnof the 'A the ibevolume~

sto hi to dth ta vu pressure drops 11 lafidw "'ean Fiberpenetratione

~~ through scre contdbutes to m Figure 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 Analysis RI-GSI191-V03 Revision 2 4.3 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 the break, the direction of the break on the pipe, etc. Although it is not always explicitly stated in the Section 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 these failure 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 each parameter were sampled and propagated with the appropriate weighting to realistically determine the risk associated with GSI-191 phenomena.

The detailed methodology for uncertainty quantification and propagation 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., it correctly solves the equations that it is intended to solve). Validation tests are performed to ensure that the 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 an evaluation tool for the STP risk-informed GSI-191 calculations, it was not put through a formal V&V process. However, it was independently checked and reviewed following an approach similar to a typical engineering calculation.

This review included a series of hand and alternate software calculations that were 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 Analysis RI-GSI191-V03 Revision 2 5 Analysis This section describes the physical models used in CASA Grande and the calculations performed to determine debris generation, debris transport, strainer head loss, chemical effects, air intrusion, strainer debris 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 variety of 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 power operation (Mode 1). The full spectrum of break sizes was evaluated and subsequently binned into the small, medium, and large categories.

Potential equipment failures that can affect the GSI-191 analyses include 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 as part of the thermal-hydraulic analysis (5), but was not explicitly evaluated in CASA Grande. Pump failures, 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 LHSI pumps, 1,620 gpm for each of the HHSI pumps, and 2,600 gpm for each of the CS pumps (see Section 2.2.8). Variations in the pump flow rates affect several important areas of the overall GSI-191 evaluation, so pump failure scenarios must be carefully evaluated.

The following list provides the primary 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 be constant for all breaks.2. Recirculation Transport:

Recirculation transport is a function of the total break flow rate (HHSI plus 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 the pool velocities in the approach paths to the strainers.

However, since large pieces of debris would not reach the pool for most scenarios (e.g., breaks inside the SG compartments), and fine debris would transport to the strainers even at relatively low flow rates, flow rate variations on recirculation transport would essentially only affect the transport fraction for small pieces of Page 98 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 fiberglass debris. Based on Assumption 6.h, however, the recirculation transport fractions were assumed to be constant for all breaks.3. Debris Accumulation:

Since fine debris would be transported in suspension, the accumulation on the strainers would be proportional to the flow split (i.e., if one sump has twice as much flow as another 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 by the strainer area for each train.5. Strainer Head Loss: The head loss for each strainer is a function of the quantity of debris on the strainer and the strainer approach velocity.6. Degasification:

The quantity of air released from solution for each sump is a function of the strainer 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 a function of the debris quantity that reaches the strainer and the penetration timing is a function of the flow rate through the strainer.8. Reactor Vessel Debris Quantity:

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

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

Any combination of pumps could fail due 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 are made. By applying Assumption 2.a (failures in one train are indistinguishable from failures in another train) and Assumption 2.b (combination of pump failures in one train is worse than the same combination of pump failures in separate trains), the total number of pump combination states can be reduced 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 on the overall CDF and LERF, these cases can be conservatively assumed to all go to failure without significantly affecting the overall results (see Assumption 2.f). This eliminates 48 low frequency pump combination 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) and Assumption 2.d (bounding core accumulation), the total number of cases can be reduced to five pump combination states that need to be evaluated.

Note that since one CS pump is procedurally secured whenever all three CS pumps are confirmed to be operating (before the start of recirculation), cases with 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 Analysis RI-GS1191-V03 Revision 2 Table 5.1.1 -Bounding or representative cases for highest frequency pump combination states Working Working Working Pump Bounding Bounding Wokig WokigState Case for Case for Case HHSI LHSl CS Comments Frequency Strainer Vessel Pumps Pumps Pumps (yr.1) Failure Failure 1 3 3 3 2.64E-04 Case 1 Case 1 One CS pump procedurally secured 2 3 3 2 3.32E-06 Case 1 Case 1 Identical to Case 1 3 3 3 1 7.53E-08 Case 22 Case 9 4 3 3 0 9.77E-09 Case 1 Case 9 5 3 2 3 3.49E-06 Case 22 Case 9 One CS pump procedurally secured 6 3 2 2 4.38E-08 Case 22 Case 9 Identical to Case 5 9 3 1 3 3.22E-08 Case 9 Case 9 One CS pump procedurally secured 17 2 3 3 1.94E-06 Case 22 Case 9 One CS pump procedurally secured 18 2 3 2 2.44E-08 Case 22 Case 9 Identical to Case 17 One CS pump 21 2 2 3 1.17E-07 Case 22 Case 22 procedurally secured, Identical to Case 22 22 2 2 2 9.16E-06 Case 22 Case 22 Single train failure 23 2 2 1 7.81 E-08 Case 26 Case 26 26 2 1 2 6.03E-08 Case 26 Case 26 33 1 3 3 2.67E-08 Case 22 Case 9 One CS pump procedurally secured 38 1 2 2 3.54E-08 Case 26 Case 26 43 1 1 1 4.34E-08 Case 43 Case 43 Dual train failure The 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 pump All other high frequency pump state cases are bounded by these five pump combination states as shown in Table 5.1.1.Page 100 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 5.2 Containment CAD Model A CAD model of the STP containment building was developed to perform a variety of GSI-191 calculations as well as to define the geometry in CASA Grande (4). The details included in the CAD model and 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 Analysis RI-GSI191-V03 Revision 2 Figure 5.2.1 -Cross-section of steam generator compartment with Loops B and C Figure 5.2.2 -Close-up view of steam generator compartment with Loops B and C Page 102 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Figure 5.2.3 -Operating deck (Elevation 68'-0")Page 103 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Figure 5.2.4 -Piping and equipment (View 1)Page 104 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Figure 5.2.5 -Piping and equipment (View 2)Page 105 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Figure 5.2.6 -Steam generator compartment floor (Elevation 19'0")Page 106 of 248 30-inch vent holes -South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Sump C Sump B"Sump A Figure 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 Analysis RI-GS1191-V03 Revision 2 Figure 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 Analysis RI-GSI191-V03 Revision 2 Figure 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 Analysis RI-GSI191-V03 Revision 2 El 68'-0" --El 19'-0" El (-11)'-3" j Figure 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 Analysis RI-GS1191-V03 Revision 2 El 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 Analysis RI-GS1191-V03 Revision 2 Figure 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 Analysis RI-GSI191-V03 Revision 2 Figure 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 Analysis RI-GS1191-V03 Revision 2 Figure 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 Analysis RI-GSI191-V03 Revision 2 Figure 5.2.15 -Lead blankets on pipes Page 115 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Figure 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 Analysis RI-GSI191-V03 Revision 2 Figure 5.2.18 -Currently installed ECCS strainers Page 117 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 m -.q Figure 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 Analysis RI-GSI191-V03 Revision 2 16RC-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 valves The 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 includes the part name (which specifies the line number and insulation type if applicable), the coordinates for the junction of each pipe segment, the bend radius for curved portions of the pipe, the inner and outer diameters (either of the pipe or insulation depending on the part), and a text identifier for any work points that are included on the line. The text data was imported into CASA Grande to define the geometry of the piping and associated insulation.

The insulation associated with the equipment (steam generators, pumps, and pressurizer) was defined by creating primitive shapes based on the dimensions of significant features of the equipment defined in the CAD model.The concrete walls and floors were exported from the CAD model and imported into CASA Grande in stereolithography (STL) format to define robust barriers that would protect some insulation from the break 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 Analysis RI-GSI191-V03 Revision 2 11-09-21 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,WP 0.75RC-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: 11.75 11-09-21 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: 18.02 11-09-21 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: 216.52 0.75RC-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: 71.91 0.75RC-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: 25.78 Figure 5.2.21 -Example of CAD model text data output Page 120 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Figure 5.2.22 -Concrete walls and floors exported from CAD model in STL format Figure 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 Analysis RI-GSI191-V03 Revision 2 Figure 5.2.23 -Geometry of piping and equipment insulation in CASA Grande 5.3 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 breaks occurring).

The best generic estimates for LOCA frequencies are based on an expert elicitation process that was documented in NUREG-1829 (37). NUREG-1829 provides LOCA frequencies as a function of break 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 have a significantly different likelihood of occurrence as well as a significantly different effect on GSI-191 related 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 full range of potential LOCA scenarios.

This was done using the following steps, each of which is explained in further detail in subsequent sections: Page 122 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-VO3 Revision 2 A. 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 weld location 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 (5 th, Median, and 9 5 th) using a bounded Johnson distribution for each size category.

These fits represent the epistemic uncertainty associated with LOCA frequencies.

D. Sample epistemic uncertainty (e.g., 6 2 nd percentile) and determine the corresponding total frequency curve based on the bounded Johnson fits (assuming linear interpolation between size categories).

E. Sample break sizes at each weld location and proceed with the GSI-191 analysis carrying the appropriate 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 of the weld cases. The tables are accepted as input to CASA Grande as an Excel file, which includes a reference list that assigns every weld in containment to one of the defined cases. The units of any pair of columns defining a weld case are break size in inches (Column 1 of a pair) and annual break frequency in number of breaks per year of size greater than x per weld (Column 2 of a pair), where x is any break size in Column 1. The purpose of the information in the break-frequency table is to support hybrid break frequency assignment (8) by defining relative proportions of break frequency across the weld types within any break size range of interest.

Table 2.2.3 through Table 2.2.10 provide the link between aggregate annual break frequencies defined by NUREG-1829 and the assignment of breaks to specific locations in containment.

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

Many of the values in Table 2.2.3 through Table 2.2.10 were populated using a log-log interpolation scheme based on arguments invoking fracture mechanics 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 was necessary to filter out log-log interpolated values from each weld case. Interpolated values were identified 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 and dividing 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 STP CAD model (see Section 5.3.1). Division by the total annual break frequency is not strictly required, but it emphasizes that the purpose of the table is to define the joint probability distribution that exists between break size and weld type. A weld case provides a categorical representation of location within the plant as specified by the CAD model.Page 123 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 All 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 a common list of break sizes. There can be a very long list of unique size bins that is determined by the LHS design size, but recall that the sample design preserves the definition of LOCA categories so that break-size intervals never span the LOCA-bin limits.The hybrid break frequency assignment (8) was implemented.

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

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

This equivalence is the essence of the hybrid methodology.

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

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

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

The hybrid break frequency assignment was repeated as necessary for each sample of the Johnson uncertainty profile that was propagated through the evaluation.

A description of the process for selecting 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 on specific degradation mechanisms for categories of welds. These frequencies were determined from an analysis 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 of conditional 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 location that are subsequently normalized against the NUREG-1829 frequencies.

Descriptions of the 45 unique categories 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 Analysis RI-GSI191-V03 Revision 2 Note that the pipe size listed in Table 5.3.1 is the nominal diameter, which is treated the same as the inner diameter.

The DEGB size is the diameter of an equivalent hole with twice the inner area of the pipe (i.e., the equivalent break size given a fully offset DEGB with jets emanating from both sides of the broken pipe), and is calculated using the following equation: DDEGB = vr2. Di Equation 22 where: DDEGB= Equivalent DEGB break size diameter assuming full pipe offset Di = Pipe inner diameter For the hot and cold leg piping, the nominal diameter is equal to the inner diameter.

However, the nominal diameter is larger (and in some cases significantly larger) for the higher schedule/thicker walled pipes that are 16 inches and smaller. For example, the surge line is a 16-inch, Schedule 160 pipe, which has an inner diameter of 12.81 inches. Therefore, the actual DEGB size would be 18.12 inches rather than 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 not consistent with the CAD model for all break categories.

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

Also, Category 6B contains two weld sizes (nominal 0.75-inch and 1-inch pipes), and Categories 6A and 8C contain two weld sizes (nominal 1.5-inch and 2-inch). As noted in the tables, the different weld sizes were captured as subcategories.

Page 125 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSl191-V03 Revision 2 Table 5.3.1 -Description of weld categories Nominal Actual DEGB Weld Category System Pipe Size Pipe Size (in) Type DM No. Welds (in) (in)6B-1 0.75* 0.614 0.87 176 Small Bore B-J VF, SC, D&C 6B-2 1 0.815 1.15 17 7L SIR 1.5 N/A N/A B-J D&C 0 51 Pressurizer 2 1.689 2.38 B-J TF, D&C 2 6A-1 1.5* 1.338 1.89 1*Small Bore B-J VF, SC, D&C 6A-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 10 8C-1 1.5* 1.338 1.89 8 CVCS -B-i VF, D&C8 8C-2 2 1.689 2.38 39 4D Surge Line 2.5 2.125 3.01 B-J TF, D&C 6 5B Pressurizer 3 2.626 3.71 B-J TF, D&C 14 5D Pressurizer 3 2.626 3.71 B-J D&C 4 71 SIR 3 2.626 3.71 BC D&C 8*5C Pressurizer 4 3.438 4.86 B-J D&C 53 51 Pressurizer 4 3.438 4.86 BC D&C 2 71 SIR 4 3.438 4.86 BC D&C 5 8B CVCS 4 3.438 4.86 B-J TF, VF, D&C 19 8D CVCS 4 3.438 4.86 B-J VF, D&C 6 8E CVCS 4 3.438 4.86 BC TF, D&C 4 8F CVCS 4 3.438 4.86 BC D&C 1 5A Pressurizer 6 5.189 7.34 B-J TF, D&C 28*5E Pressurizer 6 5.189 7.34 B-J D&C 29 5F 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 0 5H Pressurizer 6 5.189 7.34 B-F D&C (Weld Overlay) 4 7H SIR 6 5.189 7.34 B-J D&C 23 7B SIR 8 6.813 9.64 B-J TF, D&C 9 7C SIR 8 6.813 9.64 B-J SC, TF, D&C 3 7G SIR 8 6.813 9.64 BC, B-J D&C 42 7F SIR 10 8.500 12.02 B-J D&C 30 7A SIR 12 10.126 14.32 B-J TF, D&C 21 7D SIR 12 10.126 14.32 B-J SC, D&C 3 7E SIR 12 10.126 14.32 BC, B-J D&C 57 7M ACC 12 N/A N/A B-J SC, D&C 0 7N ACC 12 10.126 14.32 B-J TF, D&C 35 70 ACC 12 10.126 14.32 BC, B-J D&C 15 4A Surge Line 16 12.814 18.12 B-F SC, TF, D&C 1 Page 126 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Nominal Actual DEGB Weld Category 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 7 4C Surge Line 16 12.814 18.12 BC TF, D&C 2 3A Cold Leg 27.5 27.500 38.89 B-F SC, D&C 4 3C Cold Leg 27.5 27.500 38.89 B-J D&C 12 1A Hot Leg 29 29.000 41.01 B-F SC, D&C 4 lB Hot Leg 29 29.000 41.01 B-J D&C 11 1C Hot Leg 29 29.000 41.01 B-J TF, D&C 1 2 SG Inlet 29 29.000 41.01 B-F SC, D&C 4 3B Cold Leg 31 31.000 43.84 B-F SC, D&C 4 3D Cold Leg 31 31.000 43.84 B-J D&C 24 Total 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 CAD model are based on STP's in-service inspection (ISI) drawings.

Table 5.3.3 shows the relevant weld data from 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 were corrected 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 Category 7K.* The component database was updated with a modification to the weld category identifiers after the LOCA frequency report was issued. Category 5G corresponds to B-J welds on 6-inch pressurizer piping susceptible to failures from D&C and PWSCC damage mechanisms.

Four welds at 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 as Category 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, the welds 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 the component 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 nominal pipe diameter.

The actual pipe diameter is typically smaller than the nominal diameter, which Page 127 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 also affects the equivalent DEGB size. The pipe diameter differences between the LOCA frequency 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 report and the CAD model as shown in Table 5.3.2. The most notable difference is the weld count for Category 6B. The LOCA frequency report lists 193 welds in this category, but the CAD model and the component database only contain a total of 35 of these welds. Upon review, the missing welds appear to be locations where 0.75-inch pipes (drain lines, etc.) are connected to larger piping. 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 to GSI-191 phenomena for this size of breaks, it is reasonable to distribute the overall break frequency for the 193 welds to the 35 welds that were modeled (see Assumption 3.f). For other weld categories, the weld count in the CAD model was assumed to be more accurate than the weld 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 counts Ct Report Pipe CAD Pipe Report CAD DEGB Report Weld CAD Weld Size (in) Size (in) DEGB (in) (in) Count Count 6B-1 1 0.614 1.41 0.87 32 6B-2 0.815 1.15 3 7L 1.5 N/A 2.12 N/A 0 0 5J 2 1.689 2.83 2.38 2 2 6A-1 1.338 1.89 1 6A-2 1.689 2.38 23 7K 2 1.689 2.83 2.38 10 11 8A 2 1.689 2.83 2.38 10 10 8C-1 2 1.338 2.83 1.89 8 8C-2 1.689 2.38 39 4D 2.5 2.125 3.54 3.01 6 6 5B 3 2.626 4.24 3.71 14 14 5D 3 2.626 4.24 3.71 4 4 7J 3 2.626 4.24 3.71 9 8 5C 4 3.438 5.66 4.86 53 53 51 4 3.438 5.66 4.86 2 2 71 4 3.438 5.66 4.86 5 5 8B 4 3.438 5.66 4.86 19 19 8D 4 3.438 5.66 4.86 6 6 8E 4 3.438 5.66 4.86 4 4 8F 4 3.438 5.66 4.86 1 1 5A 6 5.189 8.49 7.34 29 28 5E 6 5.189 8.49 7.34 29 29 5F 6 5.189 8.49 7.34 0 4 5G 6 N/A 8.49 N/A 0 0 Page 128 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Report Pipe CAD Pipe Report CAD DEGB Report Weld CAD Weld ategory Size (in) Size (in) DEGB (in) (in) Count Count 5H 6 5.189 8.49 7.34 4 4 7H 6 5.189 8.49 7.34 23 23 7B 8 6.813 11.31 9.64 9 9 7C 8 6.813 11.31 9.64 3 3 7G 8 6.813 11.31 9.64 42 42 7F 10 8.500 14.14 12.02 30 30 7A 12 10.126 16.97 14.32 21 21 7D 12 10.126 16.97 14.32 3 3 7E 12 10.126 16.97 14.32 57 57 7M 12 N/A 16.97 N/A 0 0 7N 12 10.126 16.97 14.32 35 35 70 12 10.126 16.97 14.32 15 15 4A 16 12.814 22.63 18.12 1 1 4B 16 12.814 22.63 18.12 7 7 4C 16 12.814 22.63 18.12 2 2 3A 27.5 27.500 38.89 38.89 4 4 3C 27.5 27.500 38.89 38.89 12 12 1A 29 29.000 41.01 41.01 4 4 1B 29 29.000 41.01 41.01 11 11 IC 29 29.000 41.01 41.01 1 1 2 29 29.000 41.01 41.01 4 4 3B 31 31.000 43.84 43.84 4 4 3D 31 31.000 43.84 43.84 24 24 Total 1 775 628 Page 129 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1291-V03 Revision 2 Figure 5.3.1 -Locations of Category 6B welds that were modeled Page 130 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Table 5.3.3 -Weld data from component database and CAD model No. 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 Analysis RI-GSI191-V03 Revision 2 No. 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 Analysis RI-GS1191-V03 Revision 2 No. 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 Analysis RI-GSI191-V03 Revision 2 No. 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 Analysis RI-GSI191-V03 Revision 2 No. 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 Analysis RI-GSI191-V03 Revision 2 No. 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 Analysis RI-GSI191-V03 Revision 2 No. 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 Analysis RI-GS1191-V03 Revision 2 No. 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 Annulus 301 6-SI-1108-BB1 6-SI-1108-BB1-2 SI 7H 5.189 -390.98 -461.85 483 Hot Annulus 302 6-SI-1108-BB1 6-SI-1108-BB1-3 SI 7H 5.189 -376.83 -461.85 483 Hot Annulus 303 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 Annulus 307 6-SI-1208-BB1 6-SI-1208-BB1-2 SI 7H 5.189 -378.18 474.65 483 Hot Annulus 308 6-S1-1208-BB1 6-SI-1208-B81-3 SI 7H 5.189 -378.18 460.51 483 Hot Annulus 309 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 Analysis RI-GS1291-V03 Revision 2 No. 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 Analysis RI-GS1191-V03 Revision 2 No. 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 Analysis RI-GS1191-V03 Revision 2 No. 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 Analysis RI-GSI191-V03 Revision 2 No. 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 Analysis RI-GSI191-V03 Revision 2 No. 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 Line 530 16-RC-1412-NSS 16-RC-1412-NSS-3 Pressurizer Surge Line 48 12.814 181.01 -678 528.97 Hot Surge Line 531 16-RC-1412-NSS 16-RC-1412-NSS-4 Pressurizer Surge Line 4B 12.814 205 -654 528.41 Hot Surge Line Page 143 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 No. 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 Line 538 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 Cavity 543 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 Cavity 544 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 Cavity 545 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 Cavity 548 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 Cavity 549 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 Cavity 550 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 Cavity 554 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 Cavity 555 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 Cavity 556 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 Cavity 560 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 Cavity 561 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 Cavity 562 29-RC-1101-NSS

-LOOP 1 29-RC-1101-NSS-1 RC-Hot Leg 1 1B 29 -36.35 -119.66 522 Hot RX Cavity 563 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 Cavity 568 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 Cavity 570 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 Analysis RI-GS1291-V03 Revision 2 No. 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 Cavity 575 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 Cavity 577 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 Cavity 582 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 Cavity 584 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 Cavity 588 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 Analysis RI-GSI191-V03 Revision 2 No. 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 Analysis RI-GSl191-V03 Revision 2 5.3.3 Statistical Fit of NUREG-1829 LOCA Frequencies NUREG-1829 provides a set of LOCA frequency uncertainties (corresponding to the 5 th percentile, median, mean, and 9 5 th 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 the full range of epistemic uncertainty associated with LOCA frequencies (8). This is illustrated in Figure 5.3.2.100 10.2 PWR 25-yr Fleet-Average Operation X A CD a,++ Bounded Johnson 4+,95d m mean+ 5 0 th* 5 th I I IIII 10-10 10"1 10 2 0 5 10 15 20 Break Size (in.)25 30 35 Figure 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 Equation 23 and Equation 24 (8), and the fitted parameters are provided in Section 2.2.3.F[x] = + 6f[(x -'f)/,D]Equation 23 Page 147 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 where (D[x] is the cumulative distribution function of a standard normal random variable, y and 6 are shape parameters (with y driving the distribution's skewness), ý is a location parameter, A, is a scale parameter, and f(z) = log[z / (1-z)] for k < x!5 + X.min (F[x 0.0 5] -0.05)2 + (F[xo.so]

-0.50)2 + (F[xo.9 s] -0.95)2 Y,&,ý,A s.t. X -X0.0 5 Equation 24+ ý -> Xo.9 5 6, , A 0 5.3.4 Sample Epistemic Uncertainty of LOCA Frequencies Given the fitted distribution parameters, the epistemic uncertainty of the LOCA frequency data in NUREG-1829 can be sampled. For example, if the 6 2 nd percentile is selected, the LOCA frequencies can be calculated based on Equation 23 and the parameters in Section 2.2.3. The calculated 6 2 nd percentile values are shown in Table 5.3.4. Figure 5.3.3 shows the LOCA frequency vs. break size for the 6 2 nd percentile assuming linear interpolation between the values in Table 5.3.4. (Note that the shape of the interpolated curves appears to be non-linear on a semi-log plot.)Table 5.3.4 -Example calculation of LOCA frequencies vs. break size for 6 2 nd Percentile 62 Percentile B ize LOCA Frequencies (in) (year")0.5 1.06E-03 1.625 1.66E-04 3 6.35E-06 7 5.92E-07 14 2.74E-08 31 2.89E-09 Page 148 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 LOCA Frequency for 62nd Percentile 1.OE-02 1.OE-03 1.OE-04 1.OE-05 I 1.OE-06 1.0E-07 1.OE-08 1.OE-09 0 5 10 15 20 25 30 35 Break Size (In)Figure 5.3.3 -Illustration of LOCA frequency vs. break size for 6 2 nd percentile

5.3.5 Sample

Break Sizes at Each Weld Location CASA Grande evaluates multiple sizes of breaks at every weld in containment, and it always includes the DEGB condition for every weld. The total number of break scenarios investigated for each weld is determined based on user input for the maximum desired number of breaks in the largest pipe, NL. One of these breaks is assigned to the DEGB condition, and the remaining number are selected from NL-- 1 strata defined across the large break size range. The range of break sizes for a given weld was subdivided into a number of intervals proportional to the range of the largest possible LBLOCA. The standard LOCA bins of 0.5 to 2 inches (SBLOCAs), 2 to 6 inches (MBLOCAs), and greater than 6 inches Page 149 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 (LBLOCAs) were used; so the number of breaks in the small and medium range were determined by the following formulas 1 9: Ns= ceil ( Dmax 6 NL) Equation 25 ('6-2 )NM =ceil D -6 NL) Equation 26 mD~ax-6 where: Ns = Number of breaks in SBLOCA category NM = Number of breaks in MBLOCA category NL = Number of breaks in LBLOCA category Dmax = Maximum break size in containment (in)The ceil(x) operator simply rounds up to the nearest integer. This guarantees that there is always at least one 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 the associated weld case was divided into an equivalent number of non-uniform bins (unequal size), and the probability weights for each bin were recorded.

Random percentiles were selected from each probability 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 discrete break sizes are matched with their probability weight and carried throughout the evaluation as independent break scenarios.

When this algorithm is applied to the STP weld population for NL = 10, the total number of scenarios is approximately 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 run with 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 largest pipes 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. This method emphasizes the contributions of the larger breaks while also ensuring that small and medium breaks are considered.

Page 150 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 nine 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 the logarithmic scale. By relative proportion of their respective ranges, only two break intervals are assigned to MBLOCAs, and only one is assigned SBLOCAs. Thus, for this example, 13 breaks are simulated at each weld belonging to Weld Case lB.Illustration of Logarithmic Sample Bins for Case 1B II A .9~10 OD 10 0 1010 .--1 1 a sI (efeci I i nI ."o I i111111II I1 i II I II I I I 10"1 .,I t ., I. .100 101 102 break size (effective diam, in.)Figure 5.3.4 -Example of non-uniform stratified sampling strategy for one weld case 5.4 Debris Generation Debris generation analysis includes calculations of the total quantity of insulation, coatings, latent, and miscellaneous debris, as well as a definition of debris characteristics (size and density).

These topics are discussed in this section.5.4.1 ZOI Model The 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 be conservatively modeled as a sphere for a fully offset DEGB or as a hemisphere for anything less than a Page 151 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 DEGB (i.e., a side-wall pipe break) (45). The ZOI radius depends on the destruction pressure of the insulation and the size of the break. As shown in Section 2.2.14, the ZOI sizes for insulation at STP are 2D for Transco RMI, 17D for Nukon and Thermal-Wrap (assumed to be the same as Nukon), and 28.6D for Microtherm (assumed to be the same as Min-K). All insulation that falls within its respective ZOI is assumed 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-inch side-wall break, and a small 2-inch side-wall break. Because of the spherical ZOI assumption, the direction of the jet is irrelevant for DEGBs (see Figure 5.4.1). The jet direction and orientation of the hemispherical ZOI for side-wall breaks is dependent on the break location radially around the pipe, but the 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 Analysis RI-GSI191-V03 Revision 2 Figure 5.4.1 -Illustration of 17D Nukon ZOI for a 31" DEGB Page 153 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Figure 5.4.2 -Illustration of 17D Nukon ZOI for a 6" side-wall break Figure 5.4.3 -Illustration of 17D Nukon ZOI for a 2" side-wall break Page 154 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Jet 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 Model To implement the fiberglass debris size distribution described in Section 2.2.15, the fiberglass ZOI was split into three sub-zones.

The quantity of fiberglass insulation in each sub-zone was multiplied by the appropriate percentage of fines, small pieces, large pieces, and intact blankets as defined in Table 4.1 of the Alion debris size distribution report (46). Figure 5.4.4 shows an example of the size distribution sub-zones.11.9D Sub-Zone Figure 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 Analysis RI-GSI191-V03 Revision 2 The Microtherm debris was assumed to fail as 100% fines with components of SiO 2 , TiO 2 , and fibers as described in Section 2.2.15.5.4.3 Insulation Debris Using 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 ZOI debris volume. These calculations assumed a 17D ZOI for Nukon and Thermal Wrap insulation.

Figure 5.4.5 shows the complementary cumulative probability distribution function formed from the fiberglass debris quantities calculated for these scenarios with the relative initiating event frequencies included as probability weights. As shown on this figure, the maximum quantity of fiberglass debris that can be generated approaches 3,000 ft 3 , but 99.9% of the scenarios generate less than 10 ft 3 of fiberglass debris.Dist of ZOi Debris Volume -With Walls 100 -2......10- ...102 A^ 10".E 12 o 14 10- .10"12 10-14 10-, 101 102 total debris volume (ft3)Figure 5.4.5 -Distribution of potential fiberglass debris quantities

5.4.4 Qualified

Coatings Debris Similar to insulation debris, the quantity of qualified coatings debris is calculated based on the quantity of coatings within the ZOI. However, due to the difficulty of accurately modeling all of the coated Page 156 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 surfaces within CASA Grande, the qualified coatings debris calculations were performed outside of CASA Grande using the CAD model. As described in Section 2.2.9, bounding quantities of qualified epoxy and IOZ coatings debris were determined for break sizes of 2-inch, 6-inch, 15-inch, and 31-inch DEGB. In CASA, the bounding 31-inch DEGB quantities were applied for all breaks.5.4.5 Unqualified Coatings Debris The inputs for unqualified epoxy, alkyd, IOZ, and baked enamel coatings failure are provided in Section 2.2.10. 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 2.2.10 also. 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 27 Mij W)Mii'cum -M total,i ' Ffail,i Equation 28 where: M(t) = Mass of unqualified coatings that fail during a specific time period t = Specific time period following the start of the accident Subscript 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 coatings Ffail = Total failure fraction F(t) = Fraction of coatings that fail during a specific time period Mij,cum = Cumulative mass of unqualified coatings that fail Although 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.

As described in Section 5.5.7, however, the transport fractions for unqualified coatings take into consideration the coatings location and the failure timing (e.g., unqualified coatings that fail in upper containment after containment sprays are secured would not be washed down). Since sprays are secured 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 sprays would be 6% or less (see Section 2.2.10). Therefore, a washdown transport fraction of 6% was used for unqualified coatings in upper containment.

All of the unqualified coatings that were calculated to Page 157 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 transport to the strainer over a total of 30 days were conservatively introduced to the pool at a uniform rate 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 Debris The quantities of latent fiber and latent dirt/dust were entered as input parameters in CASA Grande based on the values specified in Section 2.2.12. The total quantity of latent debris is applicable to all LOCA scenarios.

5.4.7 Miscellaneous

Debris Unqualified tags, labels, plastic signs, tie wraps, etc. are assumed to fail for all LOCA scenarios.

The total quantity of miscellaneous debris was entered as an input parameter in CASA Grande based on the value specified 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 values specified in Section 2.2.16. The parameters that are important for GSI-191 calculations include the characteristic diameters of particles and fibers, the macroscopic (or bulk) density of debris, and the microscopic (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 it is 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 sprays and break flow.* Pool fill transport-the horizontal transport of debris during the RWST injection phase to regions of the pool that may be active or inactive during recirculation.

Recirculation transport-the horizontal transport of debris from the active portions of the recirculation 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 Blockage Potential upstream blockage points at STP include the four 30-inch vent holes in the secondary shield wall (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 Analysis RI-GSI191-V03 Revision 2 blockage points were previously evaluated as part of the deterministic GSI-191 analysis, and it was shown that they would not be clogged with debris (65; 76).Figure 5.5.1 -Photograph of 30-inch vent hole in secondary shield wall 5.5.2 Blowdown Transport The blowdown transport fractions are provided in Section 2.2.17. As described in Assumption 6.h, the bounding, 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 Grande Blowdown Transport Fractions Debris Type Upper Upper Remaining in Containment 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 Analysis RI-GSI191-V03 Revision 2 5.5.3 Washdown Transport The washdown transport fractions are provided in Section 2.2.18. As described in Assumption 6.h, the bounding 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 Grande Washdown Transport Fractions Debris Type Washed Down in Washed Down inside Annulus Secondary Shield Wall Fines 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 pool fill transport fractions for breaks inside the secondary shield wall were used for all breaks. These values are shown below in Table 5.5.3.Table 5.5.3 -Pool fill transport fractions used in CASA Grande Pool Fill Transport Fractions Each Sump Inactive Cavities Fines 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, the bounding, 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 Analysis RI-GSI191-V03 Revision 2 Table 5.5.4 -Recirculation transport fractions used in CASA Grande Recirculation Transport Fractions Debris Type Size Debris in Washed in Washed inside Lower Annulus Secondary Containment Shield Wall Fines 100% 100% 100%LDFG Small Pieces 64% 58% 64%Large Pieces 0% NA NA Qualified Coatings Fines 100% 100% 100%Unqualified Coatings 2 0 Fines 100%Fine Chips 41%Unqualified Epoxy 2 0 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 Erosion Pieces 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 are described 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 in NEI 04-07 (44). The transport fractions can be calculated using Equation 29 for debris generated inside the ZOI, Equation 30 for unqualified coatings debris generated outside the ZOI, and Equation 31 for latent debris.20 The recirculation transport is assumed to be the same for unqualified coatings washed down to the pool and unqualified coatings that are initially in lower containment since the locations where debris would be washed down and the locations where unqualified coatings exist in lower containment are spread out and can be reasonably treated as a uniform distribution (23).Page 161 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 DTFzo, 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 29 DTFzoI = 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 wall FWD(annulus)

= Washdown fraction in annulus FWD(BCinside)

= Washdown fraction from break compartment to inside secondary shield wall FWD(BCannuIus)

= Washdown fraction from break compartment to annulus FPF(sump)

= Pool fill fraction to each sump strainer FpF(inactive)

= Pool fill fraction to inactive cavities Nsumps = 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 wall FReirc(WDannuIus)

= Recirculation fraction for debris washed down in annulus Ffrosion(spray)

= Erosion fraction for debris held up above the pool FErosion(pool)

= Erosion fraction for non-transporting debris in the pool DTFuc = Fyail " [Fupper -Fspray FRecirc + Flower " FRecirc + Freactor' FRecirc(reactor)]

Equation 30 Page 162 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 where: DTFuc = Total debris transport fraction (for particular type/size of unqualified coatings debris)Ffail = Total failure fraction Fupper = Fraction located in upper containment Flower= Fraction located in lower containment Freactor = Fraction located in the reactor cavity Fspray = Fraction of coatings that would fail prior to securing containment sprays FReerc = Recirculation fraction for debris washed to or initially in lower containment FRecirc(reactor)

= Recirculation fraction for debris in reactor cavity DTFLD = 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 fraction FPF(Sump)

= Pool fill fraction to each sump strainer FPF(inactive)

= Pool fill fraction to inactive cavities N 5 umps = 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 debris generated inside the ZOI for a large break in the steam generator compartments.

The washdown transport fractions are based on the actuation of containment sprays (i.e., CS flow is greater than 0 gpm), and the pool fill transport fractions are based on all three sumps being active (i.e., at least one pump is running on three different trains).Page 163 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Bodw ahonRecirculatin Eoion Fraction oif Debris Blowdown, Washdown oo Fil raspr

.. Debris Size Transport Transport Pool Fill Transport Transport Erosion at Sump 0.00 Retained on Structures 1.00 0.371 0.70 0.53 Transport Upper Washed Down 0.00 Containment Inside Secondary Sediment Shield Wall 1.00 0.329 0.47 Transport Washed Down in 0.00 Annulus Sediment LDFG 0.00 (Fines) SG Compartments 1.00 0.267 0.80 Transport Active Pool 0.00 Sediment 0.06 0.018 0.30 Active Sump(s)Lower Containment 0.00 Inactive Sump(s)0.05 Inactive Cavities Sum: 0.985 Figure 5.5.2 -Logic tree for LDFG fines showing total transport fraction implemented for all breaks Page 164 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Debris Siz Blowdown Washdown PolFgTasot Redarclation Eoin Fraction of Debris I Transport I rnport I I Trasot II at Suimp I 0.01 0.003 0.54 I Erodes to Fines.... I Retained onf Structures 0.27 I 0.99 Remains Intact 0.64 0.104 I Transport 0.60 Upper Containment Washed Down Inside Secondary Shield Wan 0.07 0.36 Erodes to Fines Sediment 0.93 Remains Intact 0.004 0.58 0.066 I Transport 0.19 I rnnf7 Washed Down in Annulus 0.A2 Erodes to Fines Sediment 0.93 Remains Intact 0.01 0.003 0.001 0.73 LD7G_Retained on Structures 0.15 SG Compartments 0.217 troaes to 1tmes 0.99 Remains Intact 0.64 0.026 Transport 9I n7 Washed Down Inside Secondary Shield Wall 0.36 Erodes to Fines Sediment 0.93 Remains Intact 0.64 0.001 0.160 iransport 1.00 Active Pool 0.07 0.36 Erodes to Fines Sediment 0.93 Remains Intact 0.00 0.006 flt'tt 0.25 0 .00 -Containment Active sump~s)0.00 Inactive Sump(s)0.00 Inactive Cavities Sum:O.374 Figure 5.5.3 -Logic tree for LDFG small pieces showing total transport fraction implemented for all breaks Page 165 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Debris size DBowdown Washdown Recrculation Ders ie I rnpot I Transport I Pool Fill Transport I erua~Tianpr I i Fraction of Debris Irs~ at Sum p 0.01 0.002 1.00 Retained on 0.22 Structures Upper Containment 0.00 Lower Containment Erodes to Fines 0.99 Remains Intact 0.01 0.008 1.00 LOFG (Large Pieces)Retained on 0.78 Structures SG Compartment 0.00 Lower Containment 0.00 Lower Containment Erodes to Fines 0.99 Remains Intact Sum: 0.010 Figure 5.5.4 -Logic tree for LDFG large pieces showing total transport fraction implemented for all breaks Debrisw Waizeow Re illTranaErsio Fractio of Debris Derius Size Transport Transpo atPoo Transpot Ero at Sumnp 0.0.Retained an Structures 1.00 0L371 0.70 O.53 Trawspor Upper _Washed Down 0.00 Contairmene Insie Secondaiv SediCime 1.00 0.47 Traosperl W e Down i 0.00 LAM e ft ltlment Mlcbr 0.ek 1.00 0.267 0.89 Transport AI'ePM 0.0 Sediment 0.30 Active Surnp(s)Contaliment 0.M Inactiv Sump(s).OM Inac"kM Cawties, sum: 0LIM Figure 5.5.5 -Logic tree for Microtherm fines showing total transport fraction implemented for all breaks Page 166 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Blowdown Washdown Recirculation Fraction of Debris Debris Size Transport I Transport Pool Fill Transport Transport I Erosion at Sump 0.00 Retained on Structures 1.00 0.371 n_7o 0.53 Transport 070 .------Upper Containment Washed Down Inside Secondary Shield Wall 0.00 Sediment 1.00 0.329 0.47 Washed Down in Annulus Transport 0.00 Sediment Crud 0.00 (Fines) S6 Compartments 1.00 0.267 0.89 Transport Active Pool 0.00 Sediment 0.06 0.018 0.30 Lower Containment Active Sump(s)0.00 Inactive Sump(s)0.05 Inactive Cavities Sum: 0.905 Figure 5.5.6 -Logic tree for crud fines showing total transport fraction implemented for all breaks Page 167 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 i Blwdown Washdown Recirculation Erso Fraction of Debris Debris Size Transport Transport Transport at Sump 0.00 Retained on Structures 1.00 0.371 0.70 0.53 Transport Upper Washed Down 0.00 Containment Inside Secondary Sediment Shield Wall 1.00 0.329 0o47 Transport Washed Down in 0.00 Annulus Sediment Qualified Coatings 0.00 (Fines) SG Compartments 1.00 0.267 0.09 Transport Active p wa 0.00 Sediment 0.00.013 0.010 Lower Active Sump(s)containment 0.100 Inactive Sump(s)0.05 Inactive cavities Sum: 0.985 Figure 5.5.7 -Logic tree for qualified coatings fines showing total transport fraction implemented for all breaks Figure 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 the unqualified coatings is based on a failure fraction of 100%, as well as the failure timing for the coatings in 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 few hours, 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 Analysis RI-GSI191-V03 Revision 2 Fracto In Locon Washdown PRerculation Fraction of Debris I I I I Transport I I Transport I at Sump 1.00 0.032 0.06 Fails Prior to 0.54 Securing Sprays Upper Containment 0.94 Fails After Securing Sprays Transport 0.00 Sediment 1.00 1.00 Fails Unqualfied ANkyd Coatings (Fines)0.00 Remains Intact 0.460 046 Lower Containment Transport 0.00 Sediment 0.00 Reactor Cavity Sum: 0.492 Figure 5.5.8 -Logic tree for unqualified alkyd coatings fines showing total transport fraction implemented for all breaks Debris Size Failure Fraction Initial Location Transport Pool Fill Transport Transport at Sump 1.00 0.009 0.06 Transport t Fails Prior to o.900 0.15 Securing Sprays Sediment Upper Containment 0.94 Falls After Securing Sprays 1.00 1.00 0.020 Fails 0.02 Transport Lower 0000 Containment Sdmn Unqualified Epoxy Coatings 0.00 0.a00 (Fines) 0.83 Transport Reactor Cavity _41.00 Sediment 0.00 Remains Intact Sum: 0.029 Figure 5.5.9 -Logic tree for unqualified epoxy coatings fines showing total transport fraction implemented for all breaks Page 169 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 i I i Washdown Rerculation Fraction o Deb Debris Size Faiure Fraction Initial Location Transport Pool Fil Transport Transport at Sump 0.01 0.004 0.06 I Transport Fails Prior to 0.59 0.1 Securing Sprays Sediment ConSu 1 0.94 Faiis After Securing Sprays 1.00 0.41 0.008 Falls u.02 ] Transport Lower] 0.59 Containment Sediment Unqualified Epoxy Coatings 0.00 0.000 (Fine Chips) 0.83 Transport Reactor CavityI 1.00 Sediment 1 0.00 Remains Intact Sum: 0.012 Figure 5.5.10 -Logic tree for unqualified epoxy coatings fine chips showing total transport fraction implemented for all breaks Debris Size Failure Fraction Initial Location Transport Pool Fill Transport Recrcuatinsportactio ofumpri 0.00 0.000 0.06 { Transport Fails Prior to 1.00 0.15 Securing Sprays Sediment Upper Contanentý 0.94 Fails After Securing Sprays 1.00 0.00 0.0oo Fails 0.02 ] Transport Lower1 1.00 Containment Sediment Unqualified Epoxy Coatings 0.00 0.000 ( Small Chips) 0.83 Transport Reactor CavityJ 1.00 Sediment 0.00 Remains Intact Sum: 0.000 Figure 5.5.11 -Logic tree for unqualified epoxy coatings small chips showing total transport fraction implemented for all breaks Page 170 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Debris Size Failure Fraction Initi a t ranspor Pool Fil Transport I Recirculation Fraction of Debris I I I Transport I I Transport I at Sump I 0.00 0.000 0.06 I Transport----------

-4 Fails Prior to 0.15 Securing Sprays Upper Containment 0.94 Fails After Securing Sprays 1.00 Sediment 0.00 0.000 1.00 Fails 0.02 Fails Transport Lower Containment 1.00 Sediment 0.00 Unqualified Epoxy Coatings (Large Chips)0.000 0.83 0.3Transport Reactor Cavity 1.00 Sediment 0.00 Remains Intact Sum: 0.000 Figure 5.5.12 -Logic tree for unqualified epoxy coatings large chips showing total transport fraction implemented for all breaks DebrisWasdo Recirculation Fraction of Debris I I I I Transport P F Transport at Sump 1.00 0.009 1.00 0.009 0.06 Fails Prior to 0.15 Securing Sprays Upper Containment 0.94 Fails After Securing Sprays Transport 0.00 Sediment 1.00 0.020 1.00 Fails 0.02 Lower Containment Transport 0.00 Sediment 0.00 Unqualified Epoxy Coatings (Curled Chips)0.000 0.83 Reactor Cavity Transport 1.00 Sediment 0.00 Remains Intact Sum 0.029 Figure 5.5.13 -Logic tree for unqualified epoxy coatings curled chips showing total transport fraction implemented for all breaks Page 171 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Trnsore °°iFiaTrnsIrWashdown Recirculation Fraction of Debis Debris Size i Fraction Location I Transport Pool Fl Transport Transport I at Sump I 0.050 1.00 0.06 Fails Prior to 0.83 Securing Sprays Upper Containment 0.94 Falls After Securing Sprays Transport 0.00 Sediment 1.00 Fails Unquaified IOZ Coating's (Fines)1 0.00 Remains Intact 1.00 0.170 0.17 Lower Containment 0.00 Reactor Cavity iransport 0.00 Sediment Sum: 0.220 Figure 5.5.14 -Logic tree for unqualified IOZ coatings fines showing total transport fraction implemented for all breaks DersSie krocto asispor PolFllT Rccuiition Erosion Fraction of neri Transpor Transpt atp Upper 1110 0.89 LaFent 5. ois tOwn Transport A Fised) Active Pooe 0.s 0 Sedimerlt 1 .00.)6 0.060 t es an ActfT Sump(s)Contaainme3 2.bodwei Sump(s)0115 InaUtlue cawfties Surm: ngo Figure 5.5.15 -Logic tree for latent fines showing total transport fraction implemented for all breaks As discussed in Assumption 6.e, debris accumulation on the strainers is assumed to be proportional to the 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 32 where: DTFsump(x)

= Recirculation transport to Sump(X) for a particular type/size of debris in pool Page 172 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Sump(X) = Sump(A), Sump(B), or Sump(C)DTF = Recirculation transport for a particular type/size of debris in pool Qsump(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 debris would 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 Model There are several factors that must be taken into consideration to analyze time-dependent arrival of debris at the strainers or in the core. These factors were addressed in the debris transport calculation as summarized in Table 5.5.5 and illustrated in Figure 5.5.16 (23).Table 5.5.5 -Time-dependent transport Source Time or Equation Comments t = -0 s (no curbs around inactive Assume only applies for debris blown cavity entrances) to pool and latent debris t ~425 s (based on a flow rate of t -425s (ase ona fow ateof Assume only applies to debris blown Sump Strainer Fill 14,040 gpm and a pool volume of Au ol appliest debris 13,325 ft 3) to pool and latent debris Total Fill (Switchover) t -20 min (LBLOCA)Assume washdown occurs after Initial 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 a Failure 0 min -30 days constant rate from 10 minutes to 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months Recirculated Spray Flow Debrislashd t -300s Assume instant washdown Debris Washdown Recirculated Break Flow Debrislashd t < 300s Assume instant washdown Debris Washdown Spray Erosion Washdown t < 15 min Assume during pool fill Pool Erosion Recirculation 0-30 days Assume during pool fill Total debris in pool from blowdown Initial Debris in Pool at xi = blowdown + initial washdown and initial washdown minus the debris start of recirculation (xi) -pool fill transported to inactive cavities or the strainer during pool fill Debris Recirculation Time Based on arrival time, flow rate, pool NO) 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 Analysis RI-GSI191-V03 Revision 2 Debris Circumlated Through Spray Nozzles z Foor Unqualified DebrisOn Core coatings 0 Debris irculed Through Reactor Vessal DebrisEroded Off Trapped Fiberglass Debris in Upper Containment Transported by Sprays Debris Debris on Stoaner Washed to Pool Penetrated Debris Debris Eroded off Non- X transporting Pie of Fiberglass Figure 5.5.16 -Illustration of time-dependent transport 5.6 Strainer Head Loss Overall head loss across the strainer includes the clean strainer head loss as well as the debris bed head loss from both conventional debris (fiber, particulate, RMI, paint chips, etc.) and chemical precipitates.

If the strainer head loss exceeds the NPSH margin of the pumps, the pumps would fail. Similarly, if the head loss exceeds the structural margin of the strainers, the strainers would fail potentially allowing large quantities of debris to be ingested into the ECCS.5.6.1 Clean Strainer Head Loss As 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 of Page 174 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 0.013 ft/s. Note that the maximum strainer approach velocity at STP is 0.0086 ft/s based on a maximum flow 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 Model The NUREG/CR-6224 correlation was selected for the CASA computation of conventional debris head loss 2 1 across the strainer.

This correlation is a semi-theoretical head loss model and is described in detail in 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. The NUREG/CR-6224 head loss correlation was developed in support of the NRC evaluation of the strainer clogging issue in BWRs and has been extensively validated for a variety of flow conditions, water temperatures, experimental facilities, types and quantities of fibrous insulation debris, and types and quantities 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 1 to 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 the correlation STP performed confirmatory head loss tests to demonstrate the applicability of the correlation to STP conditions (24).NUREG/CR-6224 Head Loss Correlation The NUREG/CR-6224 head loss correlation, applicable for laminar, turbulent, and mixed flow regimes through mixed debris beds (i.e., debris beds composed of fibrous and particulate matter) is given by Equation 33:[ 2 5 am 21]~ quto3 AH = A 3.5S, 2 am 1'(1 + 57a 1 3)1tU + 0.66S,- pUi ALM Equation 33 where: AH = Head loss S= Surface to volume ratio of the debris t= Dynamic viscosity of water U = Fluid approach velocity p = Density of water am = 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 by typical 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 Analysis RI-GSI191-V03 Revision 2 A = i for SI units A = 4.1528x10s (ft-water/in)/(Ibm/ft 2-s 2) for English units The fluid approach velocity, U, is given simply in terms of the volumetric flow rate and the effective surface area: U Q -Equation 34 A where: Q = Total volumetric flow rate through the screen A = Screen surface area The screen surface area (A) is the submerged (wetted) surface area of the screen. The available surface area may change with time, particularly in the case of the STP strainer design. As more debris reaches the strainer the surface area may eventually evolve to the circumscribed area as the debris starts to fill up the interstitial volume. If the debris load is sufficient to fill the entire interstitial volume, the head loss for the STP strainer is calculated using the circumscribed area with a debris load equal to the total debris load transported to the strainer less the quantity of debris required to fill in the interstitial volume of the strainer.The mixed debris bed solidity (ctm) is given by: (C am +'fi r/ a- Equation 35 Pp! Co where: 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 density pp= Average particulate material density c = Actual packing bed density corresponding to a pressure gradient of AH/AL, c. = Reference packing density or theoretical packing density For debris deposition on a flat surface of a constant size, the compression (c) relates the actual debris bed 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 Analysis RI-GSI191-V03 Revision 2 AL 0 c = co ALm Equation 36 Compression of the fibrous bed due to the pressure gradient across the bed is also taken into consideration.

The relation that accounts for this effect, which must be satisfied in parallel to the previous 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 37 It 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 is conservative.

For very large pressure gradients, the compression has to be limited such that a maximum solidity is not exceeded.

In NUREG/CR-6224, this maximum solidity is defined to be: 65 Ibm/ft 3 am -Equation 38 Pp This is equivalent to having a debris layer with a density of 65 lb ft 3.Note that 65 IbJft 3 is the macroscopic, 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 debris type. For typical debris types, this includes: Cylindrically-shaped debris: S, = 4/diam Spherically-shaped debris: S, = 6/diam Flakes (flat-plates):

S, = 2/thick where: '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 using the following equation: Page 177 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 4 M.) Equation 39 where the subscript

'n' refers to the nth constituent, and mn is the mass of each constituent.

Linear mass weighting was used because CASA Grande tracks the mass of each debris constituent in the pool, and the individual proportion of Sv contribution to the composite depends on the quantity of each constituent 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 that incorporate geometric weighting like the square-root of the sum of squared contributions.

Note that using a mass-weighted averaging to calculate the surface to volume ratio deviates from the guidance in NEI 04-07 Volume 2 Appendix V, which specifies a volumetric-weighted averaging (45). Also note that performing 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 in CASA Grande. These parameters are largely based on the debris characteristics provided in Section 2.2.16. 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 as the fiber fines (i.e., 7 micron diameter with an S of 571,429 m 1).* As described in Assumption 1.d, Thermal-Wrap LDFG was assumed to be identical to Nukon LDFG (i.e., 7 micron diameter, 175 Ibm/ft 3 microscopic density, and 2.4 Ibm/ft 3 macroscopic density)." Since the Microtherm debris would fail as fines, the density of the Microtherm fiber that accumulates on the strainer would be essentially the same as the density of the other fiberglass fines (i.e., 2.4 lbm/ft 3).* A crud diameter of 15 grm was used to represent the size range of 8 to 63 grm. This diameter on the conservatively low end of the range.* An unqualified coatings diameter of 10 pm was used to represent the size range of 4 to 20 4m for unqualified alkyd, enamel and IOZ coatings.

This diameter is on the conservatively low end of the range.* A crud density of 350 Ibrm/ft 3 was used to represent the density range of 325 to 556 IbM/ft 3.This density 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 Analysis RI-GSI191-V03 Revision 2 Table 5.6.1 -Head loss characteristics for fibrous debris Debris Type Size Geometry Size S, Microscopic Macroscopic (m 2/m 3) Density Density (lbm/ft 3) (Ibm/ft 3)Fines cylinder 7 microns 571,429 175 2.4 LDFG Small Pieces cylinder 7 microns 571,429 175 2.4 Large Pieces cylinder 7 microns 571,429 175 2.4 Microtherm Fiber Fines cylinder 6 microns 666,667 165 2.4 Latent Fiber Fines cylinder 7 microns 571,429 175 2.4 Table 5.6.2 -Head loss characteristics for non-fibrous debris Debris Type Size Geometry Size S, Microscopic Macroscopic (m 2/m 3) Density Density (lbm/ft 3) (lbm/ft 3)Microtherm TiO 2 Fines sphere 20 microns 300,000 262 52.4022 Microtherm Si0 2 Fines sphere 2.5 microns 2,400,000 137 27.4022 Qualified Epoxy Fines sphere 10 microns 600,000 94 36.66123 Qualified EOZ Fines sphere 10 microns 600,000 208 81.1263 Crud Fines sphere 15 microns 400,000 350 70.0022 Fines sphere 152 microns 39,474 124 48.3623 Fine Chips chip 2 4 15 mil thick 5,249 124 48.3623 Unqualified Epoxy Small Chips chip 2 4 15 mil thick 5,249 124 48.3623 Large Chips chip 2 4 15 mil thick 5,249 124 48.3623 Curled Chips chip 2 4 15 mil thick 5,249 124 48.3623 Unqualified Alkyd Fines sphere 10 microns 600,000 207 80.7323 Unqualified Enamel Fines sphere 10 microns 600,000 93 36.2723 Unqualified IOZ Fines sphere 10 microns 600,000 244 95.1623 Latent Dirt/Dust Fines sphere 17.3 microns 346,821 169 33.8022 Geometric Strainer Loading Compact strainer designs like the PCI stacked plate modules used at STP are designed to maximize the surface area available to accommodate a debris load while minimizing the containment floor space taken up by the strainer manifold.

The large surface area is intended to distribute total suction flow so that the face velocity of water entering the strainer is very low. For large volumes of fibrous debris, the interstitial gaps between strainer plates can load with debris, the effective surface area of a strainer 22 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 a spherical 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 Analysis RI-GS1191-V03 Revision 2 module 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 box with a clean strainer area, A 0 , of 1,818.5 ft 2 (see Section 2.2.22). When the strainer is loaded with a perfectly uniform thickness of 0.5 in., interstitial gaps are full and total flow must cross the circumscribed area. At this thickness the strainer bed is assumed to have the following dimensions (see Section 2.2.22):* x = 0.5 in (debris thickness)

A = 419 ft 2 (debris area)* V = 81.8 ft 3 (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 ft 29 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: AV Ax = Equation 40 2 (HW + HL + WL)A = 2[(H + 2Ax)(W + 2Ax) + (H + 2Ax)(L + 2Ax) + (W + 2Ax)(L + 2Ax)] Equation 41 Page 180 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 After the incremental thickness exceeds 2 inches, the bottom surface of the strainer is assumed to become inaccessible to further debris loading and the incremental bed thickness and bed area obey the following formulas for an incremental volume of debris, AV: A = AV A 2H(W + L) + WL Equation 42 Equation 43 A = 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 is assumed 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 table that was used in CASA to interpolate bed thickness and area for any time-dependent debris volume.Table 5.6.3 -Strainer loading table Volume Thickness Area (ft 3) (in) (ft 2)0 0 1,818.5 81.790 0.5000 419.00 81.800 0.5010 419.31 280.16 8.1421 447.18 478.53 15.783 592.56 676.89 23.424 747.68 875.26 31.065 912.53 1,073.6 38.706 1,087.1 1,272.0 46.348 1,271.4 1,470.3 53.989 1,465.5 1,668.7 61.630 1,669.2 1,867.1 69.271 1,882.7 2,065.4 76.912 2,106.0 2,263.8 84.553 2,338.9 2,462.2 92.194 2,581.6 2,660.5 99.835 2,834.1 2,858.9 107.48 3,096.2 3,057.3 115.12 3,368.1 3,255.6 122.76 3,649.7 3,454.0 130.40 3,941.1 3,652.4 138.04 4,242.2 3,850.7 145.68 4,553.0 4,049.1 153.32 4,873.5 4,247.4 160.96 5,203.8 4,445.8 168.60 5,543.8 Page 181 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 4,644.2 176.25 5,893.5 4,842.5 183.89 6,253.0 5,040.9 191.53 6,622.2 Figure 5.6.2 illustrates the relationship between debris volume, bed thickness, and bed surface area that is embodied in the interpolation table.Page 182 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 PCI Stacked-Plte Strainr 3000 100 2500 80 2000-60IW 1500 40 1000 20 0 0 0 500 1000 1500 2000 2500 Total Debris Volume (kt3)Figure 5.6.2 -Relationship between bed thickness and circumscribed surface area for idealized strainer loading of fiber debris Applicability of the NUREG/CR-6224 Head Loss Correlation to STP Conditions I I I I The 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 loss correlation had not been compared to experimental data. In particular, experimental data did not exist to 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 develop the 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 done recently 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 loss correlation was based on tests conducted with mechanically shredded fiber debris prior to the development of the NEI debris preparation protocol.Page 183 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 In order to ascertain the applicability of the NUREG/CR-6224 head loss correlation to STP specific conditions, a series of vertical head loss tests were performed (24). The experiments were conducted at STP conditions including the strainer flow approach velocity of 0.0086 ft/s or less, STP-specific water chemistry, a range of temperatures prototypical of the post-LOCA conditions, and STP-specific debris loads.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 as water clarity, are used to judge the completeness of the filtration process.The correlation validation process depends on knowing the input hydraulic characteristics of each type and size category of debris introduced into the test. Debris size characterization can be used to approximate the hydraulic characteristics of simple forms of debris, such as Nukon fibers, but not for complex particulates.

A typical particulate consists of roughly shaped particles of varied sizes making the analytical assessment of the surface to volume ratio, Sv, somewhat difficult and uncertain.

Some insulation 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 be addressed experimentally.

The solid density of a particle is based on the material properties and the particulate bulk density can be deduced by weighing a known volume of the particulate.

The Sv value is deduced by applying a head loss correlation to head loss test data where all parameters are known except 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 the hydraulic characteristics become somewhat interdependent.

A total of eleven exploratory head loss tests were performed (24). All testing was done using fibers from a single-side baked Nukon blanket, which was processed using the NEI debris preparation process. All testing was conducted starting at 200 °F at the STP buffered and borated water conditions.

The particulate types tested were green silicon carbide, iron oxide (the BWR sludge simulant used in the development of the NUREG/CR-6224 head loss correlation), tin, and ground acrylic paint. Flow and temperature sweeps were performed at the end of some of the experiments to examine the impact of different flow conditions and temperatures.

The NUREG/CR-6224 head loss correlation was used to replicate the measured head loss of the test conducted with iron oxide and a debris bed thickness similar to the test parameters used in the development of the NUREG/CR-6224 head loss correlation (24). The iron oxide S, value was adjusted until 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 the NUREG/CR-6224 head loss correlation was a reasonable predictor of head losses at STP water and Page 184 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 temperature conditions.

The iron oxide test, however, was limited to the lowest approach velocity of 0.02 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 extended the 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 in the tests with tin and/or green silicon carbide. The test report provides a hypothesis for this behavior based on observations of the difference in smooth surfaces noted on SEMs of green silicon carbide and tin 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 loss calculations since there is no green silicon carbide or tin in the STP debris mixture. The green silicon carbide has been used in the past as a simulant of paint, and the tin has been used as a simulant of IOZ coatings.

Most of the STP particulate debris comes from coatings, either from qualified coatings in the ZOI or from unqualified coatings elsewhere.

Another anomaly observed in the STP head loss tests was the absence of a direct correlation of the head losses observed in the temperature sweeps with the water viscosity.

The test report provides a hypothesis that the temperature also impacts the compression of the fiber debris bed due to the temperature impact on the malleability of the fibers (24). An analytical model was developed to couple the compression to temperature that showed good agreement with the experimentally determined temperature sweep data. The compression algorithm implemented in the NUREG/CR-6224 head loss correlation used in CASA was not modified to incorporate the temperature dependence suggested by the tests. The experiments showed that the measured head losses at lower temperature were lower than 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 the temperature 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 previous testing. Both tests used the same primary surrogates of Nukon fibers along with tin and acrylic particulates.

Three differences in the tests are: 1) Test 8 had a greater thickness of fiber than was reported 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 food processor whereas Test 8 used the NEI debris preparation protocol.

Based on the experience of the CHLE tests (17), fiber beds with food processor prepared fiber tended to exhibit higher head losses than fiber beds prepared in accordance with the NEI debris preparation protocol.

Comparisons of the beds prepared with food processor prepared debris and the NEI debris protocol revealed that the NEI protocol 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 plate Page 185 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 holes. The higher head losses observed with food processor beds was attributed to the formation of the low porosity "dimples".

The food processor prepared fibers used in the ARL test could have also formed low porosity "dimples", and allowed the particulate to pack tighter in the ARL test than in Test 8 resulting in a lower porosity bed with higher head losses. The formation of "dimples" in the strainer holes instead of a fiber bed over the perforated plate could also explain the very thin bed observed in the ARL test. The lack of reproducibility of the head losses observed in the Alion vertical loop test compared with the ARL test does not impact the applicability of the NUREG/CR-6224 in calculating the CASA 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 a perforated plate as was observed with the debris beds prepared in accordance with the NEI debris preparation protocol.

Therefore, the NUREG/CR-6224 head loss correlation is considered to be applicable 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 the NUREG/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 test report, 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 the prototypical 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 loss calculated using the correlation was increased by a factor of five in CASA Grande to account for uncertainties in the head loss predictions.

5.6.3 Chemical

Debris Head Loss Model A predictive chemical effects evaluation model was not fully developed within this version of the analysis.

Therefore, the specific conditions associated with each break scenario (pool volume, pool temperature, debris quantities, etc.) could not be explicitly linked to a corresponding chemical head loss. 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 of precipitates for various break scenarios (20).For nominal temperature profiles, chemical products (aluminum and calcium precipitates) were not predicted to form for any of the small breaks evaluated.

However, some of the medium and large break cases evaluated had total aluminum concentrations that were approximately equal to or slightly higher than the estimated solubility limits (20). The calcium concentration was relatively high for cases where a Page 186 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 maximum fiberglass quantity of 2,385 ft 3 was assumed. However, for cases with 60 ft 3 of fiber or less, the calcium concentration was approximately equal to the solubility limit (20). As discussed in Section 5.4.3, the quantity of fiberglass insulation debris generated is less than 10 ft 3 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 chemical concentrations for a maximum temperature profile, however, indicated that the concentration of aluminum would be significantly higher (on the order of 20 times greater than the nominal scenarios).

It is possible that these scenarios could result in significant chemical head loss. However, the maximum temperature profiles were developed based on a highly unlikely scenario where the CCW temperature is at 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 testing does 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. The probability 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 model that 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 (see Section 2.2.6), the increase in head loss would occur approximately 5 hr after the start of the event for large breaks, and approximately 16 hr after the start of the event for small and medium breaks." As shown in Table 5.6.4 and Figure 5.6.3 through Figure 5.6.5, the probability distributions for the chemical effects bump-up factors were developed with mean bump-up factors of approximately 2x for small breaks, 3x for medium breaks, and 3x for large breaks, and maximum bump-up factors of approximately 15x for small breaks, 18x for medium breaks, and 24x for large breaks.The exponential probability density function is defined by a single parameter, the mean, and is continuous on the interval from zero to infinity.

The chemical effects bump-up factor should never be less than one, and there is a practical maximum above which all events will lead to sump failure, so the following 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 side calculation is used to determine a formal maximum endpoint for each formal mean above which the Page 187 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 cumulative tail probability is approximately 1E-5. Thus, the maximum chemical effects bump-up factor is always assigned a weight of 1E-5. Sampling is performed on a logarithmic scale with an emphasis on large values. This means that a much higher proportion of samples are taken from the high end of the range, but each individual sample has a small probability contribution.

Finally, all samples from the formal exponential probability density functions are shifted by one unit to guarantee that the applied factors are never less than one.Shifting all samples by a unit of one has the somewhat unintended consequence of inflating the potential 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-up factors for each LOCA category Parameters SBLOCA MBLOCA LBLOCA Tail Probability Min 0 0 0 ~1e-5 Formal Mean 1.25 1.5 2.0 ~le-5 Max 14.3 17.2 23 ~le-5 Min 1 1 1 ~le-5 Shifted Mean 2.25 2.5 3.0 ~le-5 Max 15.3 18.2 24 ~1e-5 Page 188 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Chemical Head-Loss Factor for SBLOCA 08-0-7 0.6-CL 0.2~01.0 0 2 6 8 10 1 o0.2-0~ 1 0 2 4 6 8 10 12 16 chemical elect factor Figure 5.6.3 -Exponential probability density function for chemical effects bump-up factors applied to SBLOCAs Page 189 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Chemical Head-Loss Factor for MBLOCA 0.7 0-6 0-5 S0-4-D-0.3 CL 0-2 0.1 8 10 12 cherica efect factor Figure 5.6.4 -Exponential probability density function for chemical effects bump-up factors applied to M BLOCAs Page 190 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GS1191-V03 Revision 2 Cherrmcal Head-Loss Factor for IBLOCA a C S-U-o ES.0 0 a-10 15 chemical effect factor 25 Figure 5.6.5 -Exponential probability density function for chemical effects bump-up factors applied to LBLOCAs 5.6.4 Strainer Head Loss The overall strainer head loss includes a combination of the clean strainer, debris bed, and chemical head losses as shown in the following equation: AHs = AHcs + AHDB " BCE Equation 44 where: AHs = Total strainer head loss 6Hcs = Clean strainer head loss AHDB = Conventional debris bed head loss BCE = Bump-up factor for chemical effects Figure 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 °F Page 191 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 and 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 s

when the containment sprays are secured.Rarndom Sample of AP History 0 a-.4 1000 time (mi)Figure 5.6.6 -Typical sample of sump-strainer head loss histories generated under the assumption of exponential chemical effects factor and artificial head-loss inflation 5.6.5 Acceptance Criterion:

NPSH Margin Module The pump NPSH margin is the difference between the NPSH available and the NPSH required, as shown in Figure 5.6.7 and Equation 45 through Equation 47. Note that the NPSH margin does not include the clean strainer or debris bed head losses. Therefore, the strainer head losses are compared to the NPSH margin 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 Analysis RI-GSI191-V03 Revision 2 Figure 5.6.7 -Illustration of parameters that affect pump NPSH NPSHM = NPSHA -NPSHR Pcont P~a NPSHA = + Heev Hpiping -ap Pg Pg NPSHR(as 2 o%) = NPSHR(aý=O%)

x (1 + 0.5aý)Equation 45 Equation 46 Equation 47 where: NPSHM = NPSH margin NPSHA = NPSH available NPSHR = NPSH required Pont = Containment pressure p = Water density Page 193 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 g = Gravitational acceleration Helev = Head of water from the pump to the surface of the pool Hpiping = Head losses between the strainer and the pump (not including strainer losses)Pvap = Vapor pressure ap* = 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 inlet 2 5 As discussed in Assumption 1.c, no credit was taken for containment overpressure.

The pressure was assumed 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 density and vapor pressure are determined as a function of the containment pool temperature based on standard water properties.

The head of water above the pumps is the sum of the water level above the containment floor and the elevation of the containment floor above the pumps as shown in the equation below. The water level is determined as discussed in Section 2.2.5. The elevation of the pumps below the containment floor is provided in Section 2.2.24.Helev = Hpool + Hpump Equation 48 where:= Water level above the containment floor Hpump = Elevation of pumps below the containment floor The piping flow losses include both major and minor losses, which are a function of cumulative and individual pump flow rates for each train as well as the pool temperature and piping geometry.

A schematic of the ECCS suction piping geometry at STP is shown in Figure 5.6.8. The piping flow losses can 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 than the void fraction at the pump inlet.Page 194 of 248 A Sump South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 C LHSI HHSI G (Z Cs B D F Figure 5.6.8 -Schematic of STP ECCS sump suction piping S2 S2 S 2 +\Hpiping,LHsl

= 2.06 7 '"fAB + 0.005Tt- + 0.58 -" fBC / (QLHs, + QHHSI + Qcs)2+ 2.97[-s'fBC (QLHSI)2 Equation 49 Hpiping,HHSI

'=S 2 S 2 2 2.0 6+ 0.005 0.1 9 Tg"fBDJ" (QLHs, + QHHsI + Qcs)2 0.09 -t-5 "fB + O.5S- -fDE ' (QHHsI + Qcs)2 + 624- [E fft +(6.24t7=t5 6.)ft (QHHSI )2 Equation 50 Page 195 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 S 2 S2 S2 +Hpiping,cs

= 2.0 6-"LfAB + +0.19T " fID (QLHsI + QHHS, ts 2+ O.09- fBD + O.19 7(QHHSI + cs)2 ( S2 S2 S2 )+ (.09-T'fDF

+ O.58Tt-'fFG

+ 2.957-'fFG) (Qcs)2 where: Hppng,xx = Flow losses in piping for the LHSI, HHSI, and CS pumps respectively f,, = Friction factor for various pipe segments illustrated in Figure 5.6.8 O, = Flow rate for LHSI, HHSI, and CS pumps respectively Equation 51 The 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 DAB f 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. D2 4" .-D (OD3. _s Re B4 P*B (QRBC C B ReBC = p.lit", 7T* DBC fBD=t-2-log[

3 7 5.02 ReED 5.02 Eog 13 -2Bo)+1- 1.7-D ReBD BD ReBD (3.7 -DD + -R A Equation 52 Equation 53 Equation 54 Equation 55 Equation 56 Equation 57 Equation 58 Equation 59 ReBD = "p (QHHSI + Qcs)RD DBD E_ _ _ 5.02 E 5 .02 g + R13 E )f-2 3.7 -D ReDE (D ReoE 3.7.- D + -DE DE ~ DE eE ReDE = p -DDE p" , i" DOE Page 196 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 fDF -" -2* log "3.

D TeDF log F ReDF +o -ReMI4 Eutin6 ReDF -- Equation 61 L .7r .DDF_ _ 5.02 e 5.02 Re13))]fF= -2"log[3 7 D Re-- log(--- log + Equation 62 4 .p. (Qcs)ReFG 4- Equation 63[t , .DFG where: Rex. = Reynolds number for various pipe segments illustrated in Figure 5.6.8 p = Water density as a function of temperature, Ibm/ft 3 V = Water viscosity as a function of temperature, Ibm/ft-sec

f. = Friction factor for various pipe segments illustrated in Figure 5.6.8 0,,, = Flow rate for LHSI, HHSI, and CS pumps respectively Du = Pipe diameter, ft E = Pipe roughness, ft The NPSH required is a fixed value dependent on the pump specifications.

However, if gas voids are present (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 NPSH margin to determine whether any failures occur. As discussed in Assumption 12.a, the failure of one pump in any train was assumed to be equivalent to the failure of all pumps in all trains.5.6.6 Acceptance Criterion:

Structural Margin The strainer structural margin is 9.35 ft (see Section 2.2.25). If the strainer head losses exceed the structural margin, the strainer may fail allowing large quantities of debris to be ingested.

As discussed in Assumption 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 those systems to perform their intended safety functions.

Gas intrusion and accumulation issues have been evaluated in response to Generic Letter 2008-01 (GL 08-01), which identifies concerns with gas Page 197 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 upstream of pumps causing potential pump failure, gas downstream of pumps causing water hammer effects when the pump is started, and other potential issues (79). Some of these issues are directly related to GSI-191, since it is possible for air to enter the ECCS and CSS through vortexing or degasification 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 minor variations 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 the strainer 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 been determined 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 be dissolved in water. If these conditions change, some of the dissolved air may be released from the water. In a LOCA scenario, some air would be dissolved in the containment pool, and as the water passes through the ECCS strainer, the head loss across the strainer would cause some of the air to be released.The following generic properties of air and water are necessary for calculating degasification: " The composition of air is approximately 78.08% nitrogen (N 2), 20.95% oxygen (02), 0.93% argon (Ar), and 0.04% carbon dioxide (C0 2) 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, the molecular weight of oxygen is 31.9988, the molecular weight of Argon is 39.948, and the molecular weight of carbon dioxide is 44.010 (86). The overall molecular weight of air is approximately 28.97.The quantity of air released from a given volume of water across an ECCS strainer can be determined by subtracting the concentration of air dissolved in water in the containment pool by the concentration of air dissolved in water downstream of the strainer.

The concentration of air is calculated using Henry's Law: Page 198 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 CG = KG(T).PG Equation 64 where: CG = Saturation concentration of air KG = Henry's constant for air at a given temperature T = Temperature PG = Partial pressure of air Henry's Constant for Air-Water Solutions Henry's constant for air (KG) can be determined based on the individual Henry's constant for each component of air (N 2 , 02, Ar, and C0 2). The volatility constant for each of these components can be calculated 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 pressure PSAT = Saturation pressure at the given temperature Ac, Bc, Cc = Constants provided in Table 5.7.1 T" = T/Tc where T is the temperature and Tc is the critical temperature of water ("K)Equation 65 Table 5.7.1 -Semi-empirical correlation parameters to calculate Henry's constants in aqueous solvent (87)Maximum T Solute Ac Bc Cc (K)(K)Nitrogen -11.6184 4.9266 13.3445 636.5 Oxygen -9.4025 4.4923 11.3387 616.48 Argon -7.4316 4.2239 9.6803 568.4 Carbon Dioxide -9.4234 4.0087 10.3199 631.7 The relationship between the volatility constant and the Henry's solubility constant is shown in Equation 66.Page 199 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 K, = MPHO kC'MHO Equation 66 where: Kc = Henry's solubility constant for gas component kc = Volatility constant for gas component PH20 = Density of water Mc = Molecular weight of gas component MH20 = Molecular weight of water The overall solubility constant for air can be calculated using the individual solubility constants as shown in 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 67 Concentration of Air in Containment Pool The partial pressure of air in the containment atmosphere can be calculated as shown in Equation 68 using the containment pressure (P 0) and the vapor pressure (Pv,O). Note that the subscript 0 is used to designate conditions upstream of the ECCS strainer.PG,o = PO- P Equation 68 The 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 69 Combining Equation 69 into Equation 68 and Equation 68 into Equation 64 yields the following:

CGO = KG(TO) * [PI -00 PsAT(TO)]Equation 70 where: Page 200 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 CG,0 = Saturation concentration of air in the containment pool KG = Henry's constant for air at the pool temperature To = Temperature of the containment pool P 0 = Containment pressureý0 = Relative humidity in containment PSAT= Saturation pressure at the pool temperature Concentration of Air Downstream of ECCS Strainer The pressure downstream of the ECCS strainer can be calculated using the containment pressure (P 0), the hydrostatic head of water above the strainer, and the pressure loss across the strainer (APLoss) as shown in Equation 71. The subscript 1 is used to designate conditions downstream of the strainer.

Note that if the pressure downstream of the strainer is less than the saturation pressure, boiling will occur resulting in a gas void fraction of essentially 100%. This condition is identified with a flag in CASA Grande.P 1 = PO + pL (TO) "g HL -APLOSS Equation 71 Similar to the containment pool calculation, the partial pressure of air and the vapor pressure downstream of the ECCS strainer can be calculated using Equation 72 and Equation 73. Note that the temperature downstream of the strainer is assumed to be the same as the temperature in the containment pool.PG,1 = P 1 -Pv, 1 Equation 72 Pv, 1 = 0"PsAT(Tl)

= 01"PSAT(To)

Equation 73 Combining Equation 71 and Equation 73 into Equation 72 and Equation 72 into Equation 64 yields the following:

CG,l = KG(TO) " [Po + pL(TO) " g " HL -APLOSS -01 PSAT(TO)]

Equation 74 where: CG,1 = Saturation concentration of air downstream of the strainer KG = Henry's constant for air at the pool temperature To = Temperature of the containment pool P 0 = Containment pressure PL = Water density at the pool temperature g = Gravity HL = Pool height above the strainer Page 201 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 APLoss = Pressure drop across the strainerý, = Relative humidity downstream of the strainer PSAT= Saturation pressure at the pool temperature Quantity of Gas Released After determining the concentration of air in solution before and after the strainer, the gas released can be simply calculated as shown in Equation 75.ACG = CG,O -CGl Equation 75 Note 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 the concentration of gas released by the flow rate through the strainer (QL) as shown in Equation 76.AMG = ACG " QL Equation 76 The ideal gas law can then be used to convert the mass of gas released to a volume.AmG R -To QG -M PG, 1 Equation 77 where: OG = Volumetric flow rate of air released AmG = Mass flow rate of air released M = Molecular weight of air R = Ideal gas constant To= Temperature of the containment pool PG,1 = Partial pressure of air downstream of the strainer The void fraction (as) can be calculated as shown in Equation 78._ QG a s = + QL Equation 78 It 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 the strainer and pumps would be roughly constant, the volume of the gas voids at the pumps can be calculated based on the ideal gas law: Page 202 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 PS xP x _SX Equation 79 where: apx = Void fraction at Pump X P, = Pressure inside the strainer Ppx = Pressure at Pump X In CASA Grande, the void fraction at the pumps was conservatively assumed to be the same as the void fraction 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 bubbles would 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 tube to 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 strainer Page 203 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Figure 5.7.2 -Cross-section view of ECCS strainer and sump pit Bubble 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 will occur when the Froude number is greater than 0.55 (see Section 2.2.27). The Froude number can be calculated using the following equation: V Fr = Equtio 8 Equation 80 where: Fr = Dimensionless Froude number v = Velocity (in the core tube, plenum, sump pit, or suction pipe)g = Acceleration of gravity I = 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 Analysis RI-GSI191-V03 Revision 2 The diameter of the strainer core tube is approximately 0.9 ft (see Section 2.2.22). Assuming a maximum sump flow rate of 7,020 gpm (see Section 2.2.8) split evenly between the four strainer core tubes, the maximum 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 1.14 7.48ga ...(_,.ft)2.3 2 2 f/2 .0 Equation 81 Since the maximum Froude number is greater than 0.55, it is possible that some air would be transported through the core tubes into the plenum. For vertical bubble transport from the plenum to the suction pipe, partial bubble transport will occur when the Froude number is greater than 0.35, and full transport will occur when the Froude number is greater than 1.0 (see Section 2.2.27). The diameter of the suction pipe is approximately 1.3 ft (see Section 2.2.22), and the maximum sump flow rate is 7,020 gpm (see Section 2.2.8). The maximum Froude number within the suction pipe is 1.82 as shown in the following calculation:

Fr = 7,O2gpm= 1.82 7.48galft 3 " .6 " (1-f). 3 2.2 ft 2 .Equation 82 The horizontal cross-sectional area of the sump pit is 40 ft 2 (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 Froude number within the sump pit is only 0.03 as shown in the following calculation:

Fr = 7,=2Ogpm -0.03 7.48 gal/f t3 "60S/rain" 40ft 2 32.2 f t/s 2 " 5.7ft Equation 83 Therefore, if the bubbles transported to the sump suction piping, they would easily transport to the pumps. 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 due to air ingestion, and the negative effects of gas voids on the NPSH required, it was assumed that any gas voids 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 would accumulate at high points within the strainer or plenum. There is a small area at the top of the strainer plenum where it is possible for air to collect. It is also possible that air pockets could form at the top of Page 205 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 the strainer disks. As shown in Figure 5.7.3, if a large enough gas void forms at the top of the plenum, air would migrate to the strainer disks closest to the plenum. If the buoyancy of the voids in the strainer disks is greater than the pressure drop across the debris bed on the strainer, the gas voids would break through the debris bed and be vented to the containment pool.Figure 5.7.3 -Illustration of air bubble accumulation and venting 5.7.4 Acceptance Criterion:

Pump Gas Void Limits As discussed in Section 2.2.28, the acceptance criterion for a steady-state gas void fraction at the pump suction 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 it arrives on the strainer.

A portion of the debris that initially arrives at the strainer will pass through, and the 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 existing bed and passing through the strainer.

By definition, the fraction of debris that passes through the strainer 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 Analysis RI-GSI191-V03 Revision 2 debris bed. Shedding, however, is a longer term phenomenon since particulate and small fiber debris may continue to work its way through the debris bed for the duration of the event. These processes are illustrated in Figure 5.8.1.Clean Strainer 40 C 0 CL Direct Passage (1-filtration)

Loaded Strainer Shedding Time Figure 5.8.1 -Illustration of direct passage and shedding Debris that penetrates the strainer can cause both ex-vessel and in-vessel problems.

Ex-vessel effects are addressed in Section 5.9, and in-vessel effects are addressed in Section 5.10 and Section 5.11. The most significant downstream effects concern is related to the quantity of fiberglass debris that accumulates 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 secured Page 207 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Decay heat boil-off The timing for initiation of recirculation, switchover to hot leg injection, and procedurally securing pumps is described in Section 2.2.1. The time-dependent arrival of debris at the strainer is described in Section 5.5.8. The decay heat boil-off curve, which defines the flow split to the core for cold leg breaks during cold leg injection, is described in Section 5.10.3. Debris accumulation on the strainer and debris penetration through the strainer (including both direct passage and shedding) are described in more detail within this section.The various parameters associated with time-dependent debris accumulation on the strainer and core are illustrated in Figure 5.8.2, where Sn(t) is the source rate for initial introduction of debris type n, V(t) is the pool volume, mn(t) is the mass of debris n in the pool, fn(t) is the filtration efficiency for debris n at the 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 the fraction 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 the strainer and core Page 208 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 As illustrated by Figure 5.8.2, debris that passes through the strainer will not necessarily end up on the core. A portion of the debris could pass through the containment spray pumps, and a portion could either bypass or pass directly through the core and spill out the break. The debris that doesn't accumulate in the core may end up back in the pool where it could transport and potentially pass through the strainer again. The differential rate of change for each debris type in the pool (assuming a homogenous mixing volume) can be described using the following equation (28): dmn Q Q= S. A -mn -YAg9(1 -f) -mn + Sn -YAqgnSn Equation 84 dt V where all of the properties can be time-dependent and have the following definitions:

mn= Mass of debris type n suspended in the pool t = Time fn = Filtration efficiency for debris type n at the strainer Q = Volumetric flow rate passing through strainers V = Total volume of the pool Sn = Source rate for initial introduction of debris type n s, = Shedding rate for debris type n from existing bed gn = Filtration efficiency for debris type n at the core V = Fraction of the total flow going to the SI pumps A = Fraction of SI flow going to the core Note that 100% filtration efficiency at the strainer, fn, for non-fibrous debris (i.e., particulate or chips) is used in CASA. This is conservative since it maximizes the strainer head loss, and the particulate debris quantity 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 be described by the following equations (28): t rV(t')MC(t) (1 ] Q(n = J Yt)A W)- fg(t')) mI-(t) + Sn(C) dt' Equation 86 where: Page 209 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Ms = Cumulative mass of debris type n on the strainer Mc = Cumulative mass of debris type n on the core t' = Dummy integration variable where t' < t denotes all times from the start to t of interest Equation 84 through Equation 86 can be determined using the following analytical solution, where the subscript n has been dropped for simplification:

Att....1 N j=1 Equation 87 Equation 88 Equation 89 Equation 90 N ý ~ -) -A t -1 ( i 1 Mti-l) I Equation 91 hj(ti _) -Qt i _ )Ati_, = ti -ti-1 Equation 92 Equation 93 where: ti = End of specific time step interval ti.I = Beginning of specific time step interval N = Number of ECCS strainers Subscript j = Variables specific to a given ECCS strainer Sk = Source rate for initial introduction of fiber type k Page 210 of 248 South Texas Project Risk-Informed GSI-191 Evaluation Volume 3: CASA Grande Analysis RI-GSI191-V03 Revision 2 Each of these equations can be solved by explicit forward integration assuming that the integrands are known 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.

The filtration 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 the filtration 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 94 where: 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 process Similar to the analytical solution above, Equation 94 can be solved as follows where the subscript n has been dropped for simplification:

V mMjh(tt) = mfh(t.- )* e-7'Ati-, + v fj(ti-1) " hj(ti-1) " m(ti-1)[1 -e-O'Ati-1]

Equation 95 sj (t,) = 7 .mjh (t,) Equation 96 where: mjsh = Mass of sheddable debris in the bed To determine the filtration efficiency and shedding rate, a series of penetration tests were conducted at Alden Research Laboratory (ARL) (26). A combination of 100% capture filter bags and isokinetic grab samples were used to gather data regarding the change in penetration as a function of strainer loading and 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 debris concentration and flow rate within the range of conditions tested (26). The ARL test data was statistically evaluated to determine appropriate fitting parameters to describe the shedding and filtration terms as a function of the debris load on the strainer and time (60). The filtration equation and fitting parameters for filtration and shedding are provided in Section 2.2.29.Page 211 of 248

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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]

ML13323A190

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4.2 Structured

5.1 Evaluation

5.3.5 Sample

5.4.2 Insulation

5.4.4 Qualified

5.4.7 Miscellaneous

5.6.3 Chemical

6.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />s

5.7.1 Vortex

5.7.2 Degasification

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ML13323A190

Text

4.2 Structured

5.1 Evaluation

5.3.5 Sample

5.4.2 Insulation

5.4.4 Qualified

5.4.7 Miscellaneous

5.6.3 Chemical

6.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />s

5.7.1 Vortex

5.7.2 Degasification

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