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==9.3 REFERENCES==
==9.3 REFERENCES==
1. OG-13-205, "PWR Owners Group, NRC Technical Concerns Regarding Boric Acid Precipitation in the Presence of In-vessel Fibrous Debris and the Consequential Effects on Long-Term Core Cooling (PWROG PA-SEE-1090 and PA-SEE-1072)," ADAMS Accession Number ML14161A043, May 2013 . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)
: 1. OG-13-205, "PWR Owners Group, NRC Technical Concerns Regarding Boric Acid Precipitation in the Presence of In-vessel Fibrous Debris and the Consequential Effects on Long-Term Core Cooling (PWROG PA-SEE-1090 and PA-SEE-1072)," ADAMS Accession Number ML14161A043, May 2013 . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 638 of 782 PA PCT PIRT PWR PWROG RBS RCP RCS RHR RV RWST RWT SBLOCA SEE SG TH UHSN UP UPI U.S. WCAP WESTINGHOUSE NON-PROPRIETARY CLASS 3 LIST OF ACRONYMS AND ABBREVIATIONS Project Authorization Peak Cladding Temperature Phenomena Identification and Ranking Table(s) Pressurized Water Reactor(s) Pressurized Water Reactor Owners Group Reactor Building Spray Reactor Coolant Purnp(s) Reactor Coolant System Residual Heat Removal Reactor Vessel Refueling Water Storage Tank Refueling Water Tank Small Break Loss-of-Coolant Accident Systems & Equipment Engineering Stearn Generator( s) Therrnal-Hydraulic(s) Upper Head Spray Nozzle(s) Upper Plenum Upper Plenum Injection United States Westinghouse Technical Report Number Preface (formerly Westinghouse Commercial Atomic Power) XVI *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *   
Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 638 of 782 PA PCT PIRT PWR PWROG RBS RCP RCS RHR RV RWST RWT SBLOCA SEE SG TH UHSN UP UPI U.S. WCAP WESTINGHOUSE NON-PROPRIETARY CLASS 3 LIST OF ACRONYMS AND ABBREVIATIONS Project Authorization Peak Cladding Temperature Phenomena Identification and Ranking Table(s) Pressurized Water Reactor(s) Pressurized Water Reactor Owners Group Reactor Building Spray Reactor Coolant Purnp(s) Reactor Coolant System Residual Heat Removal Reactor Vessel Refueling Water Storage Tank Refueling Water Tank Small Break Loss-of-Coolant Accident Systems & Equipment Engineering Stearn Generator( s) Therrnal-Hydraulic(s) Upper Head Spray Nozzle(s) Upper Plenum Upper Plenum Injection United States Westinghouse Technical Report Number Preface (formerly Westinghouse Commercial Atomic Power) XVI *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *   
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* Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 11.3 DISCUSSION OF RESULTS WCAP-17788-NP Mark-ups Page 781 of 782 11-27 During the first 20 minutes of the transient (before debris arrives), the core region has completely reflooded and the cladding temperatures are just above the saturation temperature. The core is boiJing vigorously and the core average void fraction is approximately 50%. The downcomer is filling with coolant supplied to the cold legs via the ECCS. At 20 minutes, the downcomer collapsed liquid level is well below the cold leg elevation. There is a strong recirculation pattern within the core region in which the hot and average assemblies have predominately upflow while the peripheral assemblies have downflow. Vapor generated in the core flows toward the break and liquid carryover to the break is significant. The first set of core inJet blockage simulations (Section 11.2.2) examined a scenario in which the core inlet was instantaneously completely blocked coincident with the transfer to sump recirculation by applying a large form-loss coefficient at the core inlet. No cladding heatup was predicted for this scenario. When the blockage was applied, flow through the core inlet ceased and flow through the BB channel quickJy reversed up to the first row ofLOCA holes. Flow through the BB channel was sufficient to replace boil-off and DI-IR was maintained. In the prototypic system, it is unrealistic to expect all the fibrous and particulate debris to arrive al the core inlet instantaneously. It is expected that the arrival of debris will occur over some finite period of time that is on the order of hours. Since the exact timing of debris arrival is complex and will vary from plant-to-plant, the approach for determining lblock and K.nu via application of an instantaneous blockage simplifies the approach by taking the timing of debris arrival out of the solution. Ts@ s@seRa s@t efser@ ifti@t eleskag@ sim11lal:ieRs (lil@stieR 11.~.3) @?iaRliR@a a ss@Rarie iR whisk a graa11al 011ila Hf! ef aeeris was af!f!liea at the sere ifllet. These are sensidered tke mast realistis sases relal:i1,*e te hew Eibreus and J!artisulate debris is e)tf!ested le arriYe at the sere ifllet; hewever, these sases Ela Rat simulate semf!lete sere inlet eleskage. The gradual addilieR efresistanse at Ille sere ifllet slewly iflsreases the dewRseFRer le,,*el aRd dela}'S the astivatien ef the BB shallllel. EveRlually, the dewnseFRer driviRg heaEi eesemes suffisiently large le shaRge tl1e flew direstieR iR the BB shaRRel. After this f!eint, flew frerR the LP is Sf!lil eel1ween Ille eere iRlet aRd tlte BB aRa, as the eere inlet resistllllee eenliRues le euila, the flew :lraetieR te the BB eeRliflues te iRerease while tlte flew :!raetieR te the eere ifl:let aeereases. r:rem tllese siFRuiatieRB, the eere ifllet resistattee Reeessat)' te aetivate the BB ehaRRel (.K..,i;.,-we& a@t@FHlffi@B te Bil a streng flinstieR eftlt@ li:CClil flew. K.,.1,dilett@a as a fmlstien efli:CClil flew rat@ is f!FeYidea in Figure 11 3 anti the serresf!eRdiRg flew Sf!lit eew,een the sere inlet and the BB shallllel ~) fellewing ~s shewn ifl Figllfe 11 4. From the discussion presented in Section 11.2.3, it is clear that the fiber limit for the operating B&W plants will be the [ ]'*c and that Ksp1;1 and msplit are not needed to determine this limit. That is, within the context of the hot leg break methodology described in Volume 1, K,p1;1 can be assumed to be exceeded at 20 minutes regardless of ECCS flow rate and msplil set to 1.0 for all times after Ksp1i1 occurs. The result will be a fiber limit of [ ]"c which is what would be calculated if more reasonable values for K,p1;1 and msp1;1 were calculated . -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)
* Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 11.3 DISCUSSION OF RESULTS WCAP-17788-NP Mark-ups Page 781 of 782 11-27 During the first 20 minutes of the transient (before debris arrives), the core region has completely reflooded and the cladding temperatures are just above the saturation temperature. The core is boiJing vigorously and the core average void fraction is approximately 50%. The downcomer is filling with coolant supplied to the cold legs via the ECCS. At 20 minutes, the downcomer collapsed liquid level is well below the cold leg elevation. There is a strong recirculation pattern within the core region in which the hot and average assemblies have predominately upflow while the peripheral assemblies have downflow. Vapor generated in the core flows toward the break and liquid carryover to the break is significant. The first set of core inJet blockage simulations (Section 11.2.2) examined a scenario in which the core inlet was instantaneously completely blocked coincident with the transfer to sump recirculation by applying a large form-loss coefficient at the core inlet. No cladding heatup was predicted for this scenario. When the blockage was applied, flow through the core inlet ceased and flow through the BB channel quickJy reversed up to the first row ofLOCA holes. Flow through the BB channel was sufficient to replace boil-off and DI-IR was maintained. In the prototypic system, it is unrealistic to expect all the fibrous and particulate debris to arrive al the core inlet instantaneously. It is expected that the arrival of debris will occur over some finite period of time that is on the order of hours. Since the exact timing of debris arrival is complex and will vary from plant-to-plant, the approach for determining lblock and K.nu via application of an instantaneous blockage simplifies the approach by taking the timing of debris arrival out of the solution. Ts@ s@seRa s@t efser@ ifti@t eleskag@ sim11lal:ieRs (lil@stieR 11.~.3) @?iaRliR@a a ss@Rarie iR whisk a graa11al 011ila Hf! ef aeeris was af!f!liea at the sere ifllet. These are sensidered tke mast realistis sases relal:i1,*e te hew Eibreus and J!artisulate debris is e)tf!ested le arriYe at the sere ifllet; hewever, these sases Ela Rat simulate semf!lete sere inlet eleskage. The gradual addilieR efresistanse at Ille sere ifllet slewly iflsreases the dewRseFRer le,,*el aRd dela}'S the astivatien ef the BB shallllel. EveRlually, the dewnseFRer driviRg heaEi eesemes suffisiently large le shaRge tl1e flew direstieR iR the BB shaRRel. After this f!eint, flew frerR the LP is Sf!lil eel1ween Ille eere iRlet aRd tlte BB aRa, as the eere inlet resistllllee eenliRues le euila, the flew :lraetieR te the BB eeRliflues te iRerease while tlte flew :!raetieR te the eere ifl:let aeereases. r:rem tllese siFRuiatieRB, the eere ifllet resistattee Reeessat)' te aetivate the BB ehaRRel (.K..,i;.,-we& a@t@FHlffi@B te Bil a streng flinstieR eftlt@ li:CClil flew. K.,.1,dilett@a as a fmlstien efli:CClil flew rat@ is f!FeYidea in Figure 11 3 anti the serresf!eRdiRg flew Sf!lit eew,een the sere inlet and the BB shallllel ~) fellewing ~s shewn ifl Figllfe 11 4. From the discussion presented in Section 11.2.3, it is clear that the fiber limit for the operating B&W plants will be the [ ]'*c and that Ksp1;1 and msplit are not needed to determine this limit. That is, within the context of the hot leg break methodology described in Volume 1, K,p1;1 can be assumed to be exceeded at 20 minutes regardless of ECCS flow rate and msplil set to 1.0 for all times after Ksp1i1 occurs. The result will be a fiber limit of [ ]"c which is what would be calculated if more reasonable values for K,p1;1 and msp1;1 were calculated . -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-P Mark-ups Page 782 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (defined as Km.,J was found to be 6*+0~4.75xl05. 12-2 3. The resistance at the core inlet that begins to divert flow into the AFP (defined as Kspli1) was found for a range ofECCS flow rates. These results are shown in Figure 9-3. 4. The flow split between the core inlet and the AFP after ~;1 (defined as ffispHi) was found for a range ofECCS flow rates. A curve that bounds the results was also developed. These results are shown in Figure 9-4. 12.3 COMBUSTION ENGINEERING PLANT CATEGORY CONCLUSIONS 1. The minimum time that complete core inlet blockage can be tolerated (defined as t1,10t1t) was found to be ~333 minutes. 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (defined as Kruax) was found to be 6.5xl06* 3. 4. The resistance at the core inlet that begins to divert flow into the AFP (defined as Ksplii) was found for a range ofECCS flow rates. These results are shown in Figure 10-4. The flow split between the core inlet and the AFP after Ksp1;1 (defined as msplit) was found for a range ofECCS flow rates. A curve that bounds the results was also developed. These results are shown in Figure 10-5. 12.4 BABCOCK & WILCOX PLANT CATEGORY CONCLUSIONS 1. The minimum time that complete core inlet blockage can be tolerated (defined as t1,10t1t) was found to be 20 minutes. 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (defined as Kmax) was found to be lxl08* 3. The resistance at the core inlet that begins to divert flow into the AFP (defined as ~1) was fo:YRa for a range ef E.CCS flew rates can be assumed to be exceeded at 20 minutes ( or the time of sump switchover). These results are sh.ewR iR Figure 11 3. 4. The flow split between the core inlet and the AFP after Ksp1;1 (defined as msplit) can be assumed to be 1.0 for all times after Ksplii is exceeded.was founa for a range efe.CCS flew rates. A euFve that eelff!as !He results wes else tle,,*elef!e8. These restdls ere shewn in Figure 11 4. ... This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-P Mark-ups Page 782 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (defined as Km.,J was found to be 6*+0~4.75xl05. 12-2 3. The resistance at the core inlet that begins to divert flow into the AFP (defined as Kspli1) was found for a range ofECCS flow rates. These results are shown in Figure 9-3. 4. The flow split between the core inlet and the AFP after ~;1 (defined as ffispHi) was found for a range ofECCS flow rates. A curve that bounds the results was also developed. These results are shown in Figure 9-4. 12.3 COMBUSTION ENGINEERING PLANT CATEGORY CONCLUSIONS 1. The minimum time that complete core inlet blockage can be tolerated (defined as t1,10t1t) was found to be ~333 minutes. 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (defined as Kruax) was found to be 6.5xl06* 3. 4. The resistance at the core inlet that begins to divert flow into the AFP (defined as Ksplii) was found for a range ofECCS flow rates. These results are shown in Figure 10-4. The flow split between the core inlet and the AFP after Ksp1;1 (defined as msplit) was found for a range ofECCS flow rates. A curve that bounds the results was also developed. These results are shown in Figure 10-5. 12.4 BABCOCK & WILCOX PLANT CATEGORY CONCLUSIONS 1. The minimum time that complete core inlet blockage can be tolerated (defined as t1,10t1t) was found to be 20 minutes. 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (defined as Kmax) was found to be lxl08* 3. The resistance at the core inlet that begins to divert flow into the AFP (defined as ~1) was fo:YRa for a range ef E.CCS flew rates can be assumed to be exceeded at 20 minutes ( or the time of sump switchover). These results are sh.ewR iR Figure 11 3. 4. The flow split between the core inlet and the AFP after Ksp1;1 (defined as msplit) can be assumed to be 1.0 for all times after Ksplii is exceeded.was founa for a range efe.CCS flew rates. A euFve that eelff!as !He results wes else tle,,*elef!e8. These restdls ere shewn in Figure 11 4. ... This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *}}
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Revision as of 00:54, 18 May 2018

Attachment 2: Westinghouse Responses to NRC RAIs Related to WCAP-17788, Volumes 1 and 4 Supporting the Closure of GSI-191 (PA-SEE-1090) and Mark-ups to WCAP-17788 Non-Proprietary (Part 2 of 2)
ML18029A205
Person / Time
Site: PROJ0694
Issue date: 12/19/2017
From:
PWR Owners Group
To:
Office of Nuclear Reactor Regulation
References
OG-17-335, CAW-17-4688, TAC MF6536
Download: ML18029A205 (234)
v • d • e


Text

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 549 of 782 The third comparison is made between Cases 6 and 7. In Case 6, the gap resistances are not changed and the axial resistance applied at the spacer grid elevations in all the core channels is increased by an order of magnitude. In Case 7, the spacer grid resistances are not changed and the average non-guide tube channel to hot assembly channel gap (Gap 16) resistance is increased by an order of magnitude. The objective of these sensitivities is to change the core two-phase mixing patterns to better understand the sensitivity of local fuel parameters to a change in mixing patterns. Figures RAI-4.27-32 through RAl-4.27-34 show the lateral integrated mass flow rate from the average non-guide tube channel to the hot assembly channel (Gap 16), at the bottom, mid, and top core elevations, respectively. A positive mass flow indicates that flow is from the low power channel to the average guide tube channel. At the bottom of the core, both sensitivity cases reduce the lateral mass flow between the channels. At the mid-core elevation, increasing the spacer grid resistance (Case 6) increases the lateral flow, which is from the hot assembly to the average non-guide tube channel. The case that increases the gap resistance produces the opposite trend and decreases flow from the hot assembly to the average non-guide tube. At the top of the core, increasing the spacer grid resistance increases lateral mass flow from the average non-guide tube channel to the hot assembly, while the increased gap resistance case decreases it. Figures RAl-4.27-35 through RAI-4.27-37 show the integrated axial mass flow rates in the average guide tube channel and hot assembly channel at the bottom of the core, mid-core, and the top of the core, respectively. In the figures, the average non-guide tube channel mass flow is normalized on a per fuel assembly basis in order to provide a direct comparison with the hot assembly channel, which represents a single fuel assembly. Increasing the spacer grid axial resistance (Case 6) significantly reduces the axial mass flow in both core channels across the entire core elevation. The axial flow in the two core channels at the bottom of the core is not significantly impacted by increasing the gap resistance between the two channels (Case 7). At the mid-core elevation, the hot assembly channel axial mass flow is shown to increase, and at the top of the core the hot channel axial mass flow is shown to decrease when the gap resistance is increased. The average non-guide tube channel axial mass flow at these elevations does not change significantly when the gap resistance is increased. Figures RAI-4.27-32 through RAI-4.27-37 demonstrates that these sensitivity cases were successful in significantly changing the core two-phase mixing patterns, especially in the hot assembly channel. As such it is expected that the PCT will vary between the three cases. Figure RAl-4.27-38 shows the PCT, and indicates that the base case produces the highest PCT. Both of the sensitivity studies produce considerably lower PCTs. It is noted that the increased spacer grid resistance case (Case 6) predicts a secondary heatup prior to sump switchover. As there is no physical basis for using a spacer grid resistance of this magnitude prior to the arrival of debris, this heatup was not investigated further. It is also noted that the increased spacer grid resistance case has different heatup characteristics following the application of complete core inlet blockage. Although the initial heatup, just after the application of complete core inlet blockage is lower than the other two cases, short duration intermittent heatups are predicted in this case that were not observed in the base case nor the other sensitivities. When spacer grid resistance of this magnitude is applied, the code is predicting localized dryout at locations just downstream from the spacer grid near the high power axial location. The behavior -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 550 of 782 is cyclic in nature, and is characterized by periods ofliquid being sweep out of the cell, followed by periods where liquid falls back into the cell from the top. Figure RAI-4.27-39 shows the vessel fluid mass, and indicates that the vessel fluid mass is higher in the case with increased spacer grid resistance (Case 6). In this case, the increased spacer grid resistance tends to promote increased liquid inventory in the reactor vessel because the flow resistance through the core is higher, which leads to a higher collapsed liquid level in the downcomer to balance the larger pressure drop across the core region. The figure shows that increased gap resistance between the average noguide tube channel and the hot assembly channel has little impact on the reactor vessel fluid mass. Figures RAI-4.27-40 and RAI-4.27-41 show the axial void distribution in average non-guide tube channel and the hot assembly channel, respectively. The figures indicate that the average non-guide tube channel has a lower void fraction across the core elevation when the spacer grid resistance is increased (Case 6). Increasing the average non-guide tube channel to hot assembly channel gap resistance has little effect on the average non-guide tube void fraction. In the hot assembly channel, the mid-core elevation void fraction is also reduced when spacer grid resistance is increased. Increasing the gap resistance also slightly reduces the mid-core void fraction. At the top of the hot assembly channel, the void fraction is similar in all cases. Figures RAI-4.27-42 and RAI-4.27-43 show the axial liquid velocity in the average non-guide tube channel and the hot assembly channel, respectively. Increasing the spacer grid resistance tends to change the axial liquid phase velocity in both core channels. Increasing the gap resistance does not have as big an effect on the axial liquid phase velocity. The same is true for the axial vapor phase velocities, as shown in Figures RAI-4.27-44 and RAI-4.27-45 for the average non-guide tube channel and the hot assembly channel, respectively. Results from the six sensitivities studies presented above demonstrate that increasing the gap resistance between channels or increasing the axial resistance at spacer grid elevations changes the local two-phase mixing patterns observed in the core region. Increasing the gap resistance between channels tends to reduce the lateral flow between channels, and the core channels behave more one-dimensionally. Increasing the spacer grid resistance tends to increase the liquid inventory in the core, and reduces the void fraction. In general, these effects lead to situations in which the PCT following the application of core inlet blockage is lower compared to the base case presented in WCAP-17788, Volume 4. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 .._ __ _ A-----.._ __ _ 60000 ----E ..Q -0 La.... (/) (I') 40000 0 -0 QJ -+-' ._ O' (U -+-' C: 20000 Swi chover Time Blockage Time Base Case ase 6 ase 7 WCAP-17788, Volume 4 RAI Responses Page 551 of782 I /f :..) --~*-'** , I ,J(" I I ' I I .:.;' .. j' 0 -+--"""-..ac:l:........L..---.----'----L---'--,..--,...__..__.....__-r-_._ .......... ......L.---.----"'---L---'-,--..__......__.__~ 0 2000 iOOO 6000 8000
  • 0000 2000 Ti e (sec) Figure RAI-4.27-32 Integrated Mass Flow Rate from the Average Non-Guide Tube Channel to the Hot Assembly Channel at the Bottom of the Core Showing the Effect of High Gap and Spacer Grid Resistance Applied *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 552 of 782 Swi c o er Time -----I o ck age T i me A-----B o s e C o s e Ir----Ca s e 6 A-----o s e 7 -.... . --...... '-' --...... :A.__ -...._ I . . -*-I **... : .... *-.;~.. *1 * ',. *-*-*--.t...-.J.... -5000 . I', I *-~ . *---....--... E ..0 ..__.... -0000 ..2 u... (/) en 0 2 -0 QJ -5000 '-O' QJ ......... C -20000 -25000 0 2000 *, **,* : '\ +000 6000 Ti e (sec) I

  • I , . . ,,.: .. : \ I : .. 1. I I . I 000 ..... 0000 2000 Figure RAI-4.27-33 Integrated Mass Flow Rate from the Average Non-Guide Tube Channel to the Hot Assembly Channel Mid-Core Showing the Effect of High Gap and Spacer Grid Resistance Applied *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 553 of782 Swi chover Ti e ----* 8 I o ck age T i me A----* Bose Cose .tr----* Cose 6 6----* Cose 7 . . *;.:fr/. -* 000 -E ..Cl .___... ?:; 0 6000 LL.. en en 0 ::l!: -c:, <l.) ...... 4000 .... O' <l) ..... C: 2000 0 0 . . r I /J: ./ I~ .i,*j . ..f .,. . . ( -/ I * *;;*j:i* * *J I. I I/;* I /., *. I *1 . I *****>**1/ .. : .. 1. /* / : / / .J/ 1* .Ir . . . *1 ... ... ;,,*/."<7* .... : .. / . : . ./. . I ir-,,---* . ....1----. /" j,( : ,....~* 1 : ___ ,,..., I . _ _,. : . _ * ..llitt"' 2000 i-000 ..... ,tr-* _,,__,. . 6000 Time (sec) 8000 0000 2000 Figure RAI-4.27-34 Integrated Mass Flow Rate from the Average Non-Guide Tube Channel to the Hot Assembly Channel at the Top of the Core Showing the Effect of High Gap and Spacer Grid Resistance Applied *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAl Responses Page 554 of782 .__ __ _ .tr-----11--------------..--. E .0 80000 ...Cl E <l) Cf) Cf) <( <l) 60000 ::, u.. "-<l) CL 0 LL.. 40000 Cf) Cf) 0 '"'O Q) 0 20000 ..... O'> Q) C Swi chO\'et Ti e Blockage Time Bose Cos g. Non-G ide T as 6 ~v . No -Guid Tub ose 7 Avg. No -Guide Tube Base C se Ho Asscm ly Cha Cose 6 Hot Assembly Channel Cose 7 Hot Assembly Cho ncl e Cha nel Channel Channel e I / I ,, I *,11;, "'* I ,,,, I//" I . I_.. : ~.-,.. . . /-~i .;,-* I / . . I .... ;,JA1". . . I a;,"" : . I .--,: . .Ill *.....-r-ltr-. I('/ : ., ..,. ,k"'"~ I * . .,ll"Y' . _.,.--I . ,,,, /; .~ ****** ..,.,.,....... **I** ,,,, . ~, .... *-:,.,,' 0 """'"" ........................ _,--....._...._. ......... .....,...__.__.__..__-r-........................ __,,--.__....._ ......... -r-........ __._"'----i 0 2000 4 00 6000 00 0000 2000 Time (sec) Figure RAl-4.27-35 Integrated Axial Mass Flow Rates in the Average Non-Guide Tube Channel and the Hot Assembly Channel at the Bottom of the Core Showing the Effect of High Gap and Spacer Grid Resistance Applied *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 555 of 782 .,.__ __ _ ..._ __ _ ...._ __ _ ~--It---------60000 ....--. E ..D ..__... 50000 >--..0 E (I) en en 40000 <( Q) ::, u_ "-0.. 30000 > 0 u_ en en 20000 0 2 --0 Q) ...... 0000 Q"l Q) C 0 0 Swi c over Ti e Blockage Time Base Ca e Avg. Non-G id T Cos 6 v . Non-Guid Tube Case 7 Av . No -Guide Tube Base C sc Ho ssem ly Ctia Case 6 Hot ssem ly Canel Case 7 Hot Ass m ly C a nel e Ctianne I Chann I Channel e I I ,a ./ . 1,....,-: /~ .... ---. ~--~-.;...-~-..... . 'I /" I , I. I . / .. ., .. *r...tr."~ . " ,,( .
  • I . . / If I . . / , . 1* , /. )~--:-/ _-_/ , . I . ~/* ;,** /.1e.,.:. *1. / , . ., .:._/; /r/ ,.... . -* ---* .....__. __ * ; ,/ . ._......-r-.... /II(.*,¥' ....... -~-.. 1. // /. * ,/
  • I ., / . -111 . I . ~., tfll"* / I ,,,fl' . _...A I ...... ., .. ..,;;,,, .... ,,,--;M *...... . ....-* ... , . I 200 4000 6000 8000 0000 2000 Ti e (sec) Figure RAJ-4.27-36 Integrated Axial Mass Flow Rates in the Average Non-Guide Tube Channel and the Hot Assembly Channel Mid-Core Showing the Effect of High Gap and Spacer Grid Resistance Applied *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 556 of782 A----* A----.__ __ _ 11-lt---* 11---* 80000 en CJ') 0 ""O 20000 <I) 0 ._ <I) C: Swi c over Ti e Blockage Time Base Case Avg. OS 6 v9. No Non-G i de T -Guid Tube -Guide Tube e Cha nel Chann I Channel ose 7 . No Base Cos Ho ose 6 Hot ssem ly Cha ssem ly Cho nel ssem ly C a nel Cose 7 Hot e I *1 *. I * ;--.-Y.: VI .., I -~: I -~---.. : ._. *}I'*~,'.~ .. : ...... . J(// , . I . *'/I!,' / :.,,-1*.t.---. ......_ __ _ //'ri./ , ._,; *' I * -...; -*----/~ / ... --. if'/*,,.. .... I . #*, , . /. * "': I ... ~... . .. ,. . .-: ... *1* ... ,,k / , .;.. / /ilf' ,/ ...--~-., ............ :/ .. ~:a/.. 0 .....,.::=-=L.....L--,-'---.l.__...1---.--.....L.---'---'---,-'---.L..--'---,--"----'---'---,-'---.l.__......_-l 0 2000 4000 600 8000 0000 2000 Ti e (sec) Figure RAI-4.27-37 Integrated Axial Mass Flow Rates in the Average Non-Guide Tube Channel and the Hot Assembly Channel at the Top of the Core Showing the Effect of High Gap and Spacer Grid Resistance Applied *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 Swi chover Ti e ----* B I o c I< o g e T i rne .t.-----Bose Cose I/Jr----* Case 6 .t.-----Case 7 800 1 \ ! I 1 700 ,. 1 I .---.. 600 *** LL. I O"' 1 Q) I --Q) *I* . '-500 ........ , I 0 '-<l) 1 CL I E <I) 1 1-400 .
  • 1* I, WCAP-17788, Volume 4 RAI Responses Page 557 of782 200-+--.....___......__._---,.__. ____ L....-.__~....._.....__._~__.___.___.~~-"--......... ....._~__.____.___._----1 0 2000 4000 6000 0000 2000 Ti e (sec) Figure RAI-4.27-38 The Effect of High Gap and Spacer Grid Resistance on Peak Cladding Temperature *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 S**i chovcr Ti c -----Block ge Ti e .._ __ -Ba s e Ca s e ,__ __

  • Ca s e 6 .._ ___ ose 7 (/) (/) 0 200000 80000 60000 40000 120000 WCAP-17788, Volume 4 RA! Responses Page 558 of782 I I 00000 . . . . . . . *I . I 80000 0 2000 4000 6000 8000 0000 2000 Time sec) Figure RAI-4.27-39 The Effect of High Gap and Spacer Grid Resistance on the Reactor Vessel Fluid Mass *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 559 of782 ----. .__ ___ .,_ __ .__ ___ ~--* 11---* 11---* e---e---e---.a .6 . 4 .2 Swi chov r Ti r e Blocka e T i rn Bas ase Case ose as Cose Base ase Cose Cose Bot he Core (Ce I I 6 Bot 0 e Core (Ce I I 2 ) 7 Bottom 0 e Core (Cel I 2 ) Cos Mid-Core Ce I I 7) 6 7 C 6 7 2000 t.iid-Cor (Ce I I 7) Mid-Core (Ce I I 7) s Top Top Top 0 ti Core (Ce I I 1 5) 0 e Core (Ce I I 1 5) 0 e Co r e (Ce II 1 5) . . '(' .....,........._._. __ .. J, ;.........,_.,,. ..... ._......... . I * . -.--I I \ ,"\ \ I \ ,, . .... ,11. \ , \ . ..... } .. !,.
  • 4000 6000 Ti e (sec) r . \ .. .I . ]I 8000 I I ., . 7) ........ "\ \!.**:\ I " I *
  • I *' .~ :,.,. * '* I I '" */ , , 0000 2000 Figure RAl-4.27-40 The Effect of High Gap and Spacer Grid Resistance on the Average Non-Guide Tube Channel Axial Void Distribution *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 560 of 782 ----. ,..__ ___ .ta-----,..__ ___ II----II----II------------._ __ C: .Q u 0 "-LL -0 *o 0.4 > .2 0 0 Swi C 0 Y C r Ti e Blocka e T i rne Bose Cose Bot he Core (Ce I I Caso 6 Bot 0 e Coro (Ce I I 2 ) Cose 7 Bot om 0 e Co r e (Ce I I 2 } ose Cose Mid-Core Ce I I 7) ose 6 Mi -Core ose 7 Mid-ore Base Case Top 0 as 6 Top 0 f ose 7 Top 0 2000 4000 (Cc I I 7) (Ce I I 7) Core (Ce I I Core ( e I I Core (Ce I I 6000 Time (sec) 1 5) 1 5) 0 1 5) 2 ) 0000 2000 Figure RAI-4.27-41 The Effect of High Gap and Spacer Grid Resistance on the Hot Assembly Channel Axial Void Distribution *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 561 of 782 Swi c ov r Ti e -----B I o ck a e T i me A-----Bose Cose Bot om o he Core (Ce I I 2) .....____ as e 6 Bot om o re Core (Ce I I 2) A----* Cose 7 Bot om o he Core (Ce 11 2) 11:---* Bose Cose Mid-Core (Cell 7) 11:---* ase 6 Mid-Core (Cell 7} 11---* Cose 7 Mid-Core (Cell 7) e---Bose Cos Top o ne ore (Cell 15) e---ose 6 Top o e Core (Cell 15) e---Case 7 Top o e Core (Cell 15) 4....----,-------------------,---------, 3 .£ J u 0 (1.) > 0 0 I 'I \\ : ..... ,:,. 2000 1000 6000 Time (sec) 8()00 I I *I*. I I I
  • 1, 1' 0000 2000 Figure RAI-4.27-42 The Effect of High Gap and Spacer Grid Resistance on the Average Non-Guide Tube Channel Axial Liquid Phase Velocity *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 562 of 782 ----... ..,_ ___ .t.----* .t.----* ----* ~--* ~--* ~--~--~--4 3 ........... (/) 7 ............ -..........., >,, Ti 0 <I) > '""' 0 -1 0 Swi C o v e r Ti e Blockage Ti me Bose Cose Bot he Core (Ce II Case 6 Bot om 0 Core (Ce II 2 ) ase 7 Bot om 0 e Core (Ce I I 2 ) ose Cos Mid-Core (Ce I I 7) ose 6 Mid-Core Cose 7 Mid-Core Base Cose Top 0 ose 6 Top 0 Case 7 Top 0 2000 4000 (Ce I I 7) (Ce I I 7) C Core (Ce I I e e Core (Ce I I Core (Cc II 6000 Time (sec) 1 5) 1 5) 8000 1 5) 2) 0000 2000 Figure RAl-4.27-43 The Effect of High Gap and Spacer Grid Resistance on the Hot Assembly Channel Axial Liquid Phase Velocity *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 563 of 782 .__ __ _ .__ __ _ A-----------II----e-e---I ' I I
  • I* 5.,,, i C over Ti e Blockage Ti me Bose Cos c Bo om 0 he Core (Cel I Case 6 Bot 1. om 0 e Core (Cel I 2 ) Case 7 0 t om he Core (Ce I I 2 ) Base Case Mid-Core (Ce I I 7) Case 6 Mid-Core C se 7 Mid-Core Bas C s To 0 Case 6 Top 0 ase 7 Top 0 2000 4000 (Ce I I 7) ( C I I 7) t, e Cor ( C e Core (Ce I I e Core ( C 6000 Time (sec) I I I I 5) 1 5) 1 5) 8000 2 ) 0000 2000 Figure RAl-4.27-44 The Effect of High Gap and Spacer Grid Resistance on the Average Non-Guide Tube Channel Axial Vapor Phase Velocity *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 564 of782 Swi C over Ti e -----Blockage Ti me .t.-----Bose Cose 0 t he Core ( C I I 2 ) .A.------Cose 6 Bot om e Core (Cel I 2 ) .t.-----ose 7 Bot om 0 e Core (Ce I I 2 ) 11----Ba Co* Mid-Core ( C I I 7) 11----Cose 6 Mid-Core (Ce I I 7) 11----Cos 7 Mid-Core (Ce I I 7) ~--Bose Cose Top 0 e Core (Ce I I 1 5) ~--Cose 6 Top 0 e Co r e (Ce I I 1 5) ~--Case 7 Top 0 . e Co r e ( C I I 1 5) 80 60 : .I\ . '-:~.r" {' /~" " J&, V \ . * "" \, * : ......... ... _j_ .1. . ~~\i\ *-.,\ ,~ 20 " :\ JI . :.=a-...-zl-:;. ... ,.. I * * . .... a,;:_ i!*..: ,;.a.:. I , , 0 0 6000 8000 0000 2000 Ti e (sec) Figure RAI-4.27-45 The Effect of High Gap and Spacer Grid Resistance on the Hot Assembly Channel Axial Vapor Phase Velocity *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 RAI-4.28, Vol. 4 WCAP-17788, Volume 4 RAI Responses Page 565 of 782 The Westinghouse upflow, downflow, and CE base plant models were developed for best estimate (BE) PCT and clad oxidation analysis. As discussed in Section 6.1, many of the inputs from the BE models are set to nominal values. Some changes were made to bias the model toward an Appendix K analysis. The use of Appendix K type inputs is intended to add conservatism to the model to account for uncertainties associated with the L TCC phase following a LOCA. Section 5 notes that the EMs used to analyze debris are based on NRC-approved EMs. For example, Section 5.1 notes that WCOBRA/TRAC MOD7A is used within the Code Qualification Document and ASTRUM EMs. However, the approach of nominal modeling with these codes has not been previously reviewed and accepted by the NRC. Provide a table of all physical models and plant parameters that were considered in the uncertainty analysis for each computer code's most recently approved EM, and indicate how the uncertainty analysis has been adjusted to use a somewhat nominal, yet somewhat conservative analytic method. For each adjustment relative to the previously approved application, provide detail or justification that explains how the modified approach introduces an acceptable amount of conservatism. This table should expand on the information provided in, for example, Table 6-1, and should compare the current modeling approach to that previously approved for BE analysis . Response Table RAI-4.28-1 provides the physical models and plant parameters considered in ASTRUM EM from WCAP-16009-P-A (Reference RAI-4.28-1). Table RAI-4.28-1 Physical models and plant parameters considered in ASTRUM uncertainty analysis Physical Models Plant Parameters a,c . *** This record was final approved on 12/18/2017 11:42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RA1 Responses Page 566 of782 As many of the physical models and plant parameters included in the ASTRUM EM uncertainty analysis are related to short-term LOCA analysis, they are not considered in the GSI-191 EM. The following discussion is provided which identifies the important physical models and parameters that are considered in the GSI-191 EM uncertainty assessment. The important physical models and parameters are consistent with the key physical processes provided in the PIRT in the response to RAI-4.7. L *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 567 of782 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

-. -----------, Westinghouse.Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 568 of782 *** This record was final approved on 12/18/2017 11:42:20 AM. ( This statement was added by the PRIME system upon its validation) I * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 L WCAP-17788, Volume 4 RA1 Responses Page 569 of782 Alternate flow path resistance: This parameter is included in the GSI-191 uncertainty assessment. Relative to the base models, the AFP flow resistance was increased to bound all plants in this category. The response to RAI-4.2 provides the calculation of the bounding resistance values. Additional conservatism was added to the resistance used in the GSI-191 thermal-hydraulic analysis to account for uncertainties in the calculational method, as described in the response to RAI-4.2. Core void generation/distribution (mixture level): This parameter is included in the GSI-191 uncertainty assessment. The void generation and distribution refer to the generation and distribution of steam and their effect on the mixture level. For the GSI-191 HLB scenario, the mixture level largely determines the potential for, and the severity of a debris-induced secondary heatup. WCOBRA/TRAC is known to predict the two-phase mixture level under low pressure boil-off conditions. Based on the G 1 and G2 experimental assessment using WCOBRA/TRAC, as described in the response to RAI 4-8, it was determined that the use of the 0.8x nominal interfacial drag is appropriate for the GSI-191 thermal hydraulic analysis. The sensitivity study presented also demonstrates that the interfacial drag multiplier has only a minimal impact on the key parameters output from the GSI-191 thermal hydraulic analysis. Based on the Gl and G2 test comparisons and the sensitivity study, it is concluded that the use of the 0.8 interfacial drag multiplier applies sufficient conservative bias in the calculations such that an additional bias or uncertainty is not required. Sump switchover time: This parameter is included in the GSl-191 uncertainty assessment. Sump switchover is the time that debris begins to transport from the containment sump to the reactor vessel. Earlier arrival of debris will result in the greatest potential for a debris-induced heatup because decay heat is higher. Sensitivity studies provided in the response to RAI-4.19 demonstrate that earlier sump switchover times are limiting in terms of debris-induced heatup. Debris accumulation rate: This parameter is included in the GSl-191 uncertainty assessment. The magnitude and behavior of a debris-induced secondary heatup is dependent on the debris accumulation rate at the core inlet. A 1 minute accumulation rate, which bounds any realistic accumulation rate, is applied to define the parameters Kmax and tb1ock* Conclusions The important phenomena associated with the GSI-191 EM have been identified and included in the uncertainty assessment. Table RAI-4.28-2 summarizes the physical models and plant parameters considered in the GSI-191 EM uncertainty assessment. The extrapolation of WCOBRA/TRAC for use in the GSI-191 HLB EM has been accounted for by applying conservative bias to important parameters such that the uncertainty associated with the modeling of important phenomena is bounded. The impact of the *** This record was final approved on 12/18/201711:42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 570 of782 applied conservative biases was determined to be acceptable by making additional comparisons to applicable experimental data and performing sensitivity studies. Based on the results of these data comparisons and sensitivity studies, it is concluded that the predicted results are bounding of estimate performance. Therefore, the result demonstrates with a high level of probability that the 10 CFR 50.46 long-term cooling acceptance criteria are met. Reference RAI-4.28-1 Table RAI-4.28-2 Physical models and plant parameters considered in GSI-191 uncertainty analysis Physical Models Plant Parameters Core mixture level Alternate flow path resistance Upper plenum drain distribution and Decay heat mixture level Debris accumulation rate Single-phase vapor heat transfer Core power and distribution coefficient Sump switchover time Safety injection water flow rate and temperature WCAP-16009-P-A, "Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment Of Uncertainty Method (ASTRUM)," January 2005 . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAl Responses Page 571 of782 RAI-4.29, Vol. 4 State whether the base plant models were submitted to the NRC to document safety analysis. Describe how the changes made to the base models regarding core volumes, ECCS model, BB flow resistance, break pressure boundary conditions, break flow multipliers, core inlet blockage, and calculation inputs in Tables 6-1 through 6-4 maintain adequate conservatism. Response Both the Westinghouse upflow plant model and the Westinghouse downflow plant model were submitted to the NRC to document safety analysis. The upflow plant model was submitted as Agencywide Documents Access and Management System (ADAMS) Accession Number ML093510099 and the downflow plant model was submitted as ADAMS Accession Number ML102980447. Changes to the base models submitted to the NRC are described in Table RAI-4.29-1. Table RAI-4.29-1 Base model changes for thermal-hydraulic analysis of a large hot leg break with simulation of core inlet blockage Item Parameter Change Description 1 Core Volume No changes were made relative to base model. 2 ECCSModel Changes were made to model the accumulators and pumped ECCS on all loops. These components were not included on the broken loop in the base models for cold leg breaks. Components were added to model ECCS performance changes and ECCS fluid property changes (due to temperature change) during the recirculation phase after sump switchover occurs. 3 Barrel/Baffle Flow Resistance Upflow Plant: Relative to the base models, the (K/A2, ff4) barrel/baffle flow resistance was increased to bound all plants in this category. The response to RAI-4.2 provides the calculation of the bounding resistance value. Additional conservatism was added to the resistance used in the GSI-191 thermal-hydraulic analysis. Downflow Plant: Relative to the base models, no changes were made since this parameter is not a key contributor to analysis results for this plant type . *"* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 572 of 782 Table RAI-4.29-1 Base model changes for thermal-hydraulic analysis of a large hot leg break with simulation of core inlet blockage Item Parameter Change Description 4 Upper Head Spray Nozzle Resistance Upflow Plant: Relative to the base models, no (K/Az, fr4) changes were made since this parameter is not a key contributor to analysis results for this plant type. Downflow Plant: Relative to the base models, the upper head spray nozzle resistance was increased to bound all plants in this category for the Kmax, Ksplit, and msplit analyses. The tblock analysis does not bound all downflow plants. Additional justification is required for plants that are not bounded by the tblock analysis. The response to RAI-4.2 provides the calculation of the resistance values used. Additional conservatism was added to the resistance used in the Kmax, Ksp1;1, and msplit analyses. 5 Break Pressure Boundary Conditions Relative to the base models, the break pressure boundary condition was extended to model a conservatively low containment pressure of 14.7 psia. 6 Break Flow Multipliers No changes were made relative to base model. 7 Core Inlet Blockage Relative to the base models, core inlet resistance was added during recirculation to simulate core inlet blockage. The blockage was applied over a 1 minute period, which is a conservative time. 8 Core Power No changes were made relative to base model. 9 Number of Loops No changes were made relative to base model. 10 Number of Fuel Assemblies No changes were made relative to base model. 11 Total Peaking Factor (FQ) No changes were made relative to base model. The conservatism in the value used for this parameter is further described in the response to RAI 4.5.c. 12 Radial Peaking Factor (F ,rn) No changes were made relative to base model. The conservatism in the value used for this parameter is further described in the response to RAI 4.5.c. 13 Axial Peak Power Location No changes were made relative to base model. The conservatism in the value used for this parameter is further described in the response to RAI 4.5.c. 14 ECCS Recirculation Flow Rate Relative to the base models, a range ofECCS recirculation (gpm/FA) flow rates from 18 gpm/F A to 40 gpm/F A for the upflow plants and 12 gpm/F A to 40 gpm/F A for the downflow plants were modeled in the analyses. Additional discussion regarding the applicability of this range is provided in the response to RAI-4.5. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 573 of782 Table RAI-4.29-1 Base model changes for thermal-hydraulic analysis of a large hot leg break with simulation of core inlet blockage Item Parameter Change Description 15 Containment Pressure during The bases cases did not model the recirculation phase. A Recirculation Phase (psia) conservatively low containment pressure of 14. 7 psia was modeled in the Volume 4 analyses for Westinghouse upflow and downflow plants. 16 ECCS Temperature during The bases cases did not model the recirculation phase. The Recirculation Phase (°F) value modeled is consistent with the saturation temperature at the conservatively low containment pressure of 4.7 psia modeled in the analyses. Using the saturation temperature is conservative since there is no subcooling which minimizes the heat removal capacity of the ECCS and minimizes the density; hence, driving head of the fluid column in the downcomer. 17 Sump Switchover Time (minutes) The bases cases did not model sump switchover. The sump switchover time modeled was 20 minutes, which is an early sump switchover time. The early sump switchover time maximizes decay heat removal requirements when debris arrives to the vessel. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 RAI-4.30, Vol. 4 WCAP-17788, Volume 4 RAI Responses Page 574 of782 Figure 8-19 shows two time periods after complete core blockage during which the downcomer level remains steady ( around 19 and 22 ft) before leveling out for the remainder of the transient. This could be explained by an accumulation of injected liquid in parts of the RCS outside of the RV. In addition, possible transport of liquid into the reactor upper plenum via the SG U-tube bundles can take place after filling the cold leg side of the RCS. The variable msplit is defined as the flow split between the core inlet and AFPs. Figures 8-5, 9-4, 10-5, and 11-4 depict the calculated inputs for msplit. a. Was passage ofECCS liquid into the upper plenum via the SGs predicted for any of the runs used to produce the results shown in Figures 8-5, 9-4, 10-5, and 11-4? For each case that predicted flow into the upper plenum via the SGs, plot (in units of lbm/s) the rate of liquid flow that enters into the core, the AFPs, the reactor upper plenum through each loop, and the total amount into the upper plenum via all loops as functions of time. Response

  • Some passage ofECCS liquid into the upper plenum via the intact loop steam generators (SGs) was predicted for all runs, except the lowest flow cases, used to produce the results shown in WCAP-17788, Volume 4, Figure 8-5 and Figure 9-4. The amount of ECCS liquid entering the upper plenum via the intact SGs decreased as the ECCS flow rate decreased. Results presented in this
  • section are from the revised Kspu/msplit simulations described in the response to RAI-4.20. Results from the Westinghouse upflow plant category are presented first, followed by results from the downflow category. Figure RAI-4.30-1 through Figure RAI-4.30-5 show the ECCS flow split between the reactor vessel and the crossover legs from the Westinghouse upflow plant category. Following the application of core inlet resistance, a fraction of ECCS flow enters the crossover legs, with the majority flowing through the broken loop. At the highest flow rates, the fraction ofECCS entering the crossover legs is larger than the fraction entering the reactor vessel downcomer. Figure RAI-4.30-6 through Figure RAI-4.30-10 show the flow rate through each SG and compares it to the total flow that enters the crossover legs from the ECCS. Flow from the intact SGs enters the upper plenum via the hot legs: Flow through the three intact loops is similar in magnitude and behavior. Figure RAl-4.30-11 through Figure RAI-4.30-15 show the mass flow rate ofliquid that enters the reactor vessel from the cold legs, the core inlet, the barrel/baffle channel (BB) alternate flow path (AFP), the upper head spray nozzle (UHSN) AFP, and the total flow into the upper plenum from the intact SGs. Figure RAI-4.30-16 through Figure RAI-4.30-20 show the ECCS flow split between the reactor vessel and the crossover legs from the Westinghouse downflow plant category. Figure RAI-4.30-21 through Figure RAI-4.30-25 show the flow rate through each SG and compares it to the total flow that enters the crossover legs from the ECCS. Figure RAI-4.30-26 through Figure RAI-4.30-30 show the mass flow rate of liquid that enters the reactor vessel from the cold legs, the core inlet, the UHSN AFP, and the total flow into the upper plenum from the intact SGs. Trends observed in the downflow plant category are consistent with the upflow plant category. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was.added by the PRIME system upon its validation) *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 575 of782 SWITCHOVER TIME *----Toal ECCS Flo11' *--------EC CS F I ow o Ve s s e I e----ECCS Flow o e Crossover Legs Su of Flo o e Vessel ad Crossover Legs ............. u Q) (/'l ............. ..0 ...__.. Q) ..._, Q::'. 0 LL {/) (/'l 920 4 ., ' \~, ... ~._.,__,_. ..... --..A,. .. _..~ 640 *I* * ', * * * * * * * * * * * * * .:..:.e-~"'~ * * * * * * * * * * * * * * * * * * * * * * * * * . . .-,-. ' . ----. J I , _ _.,,., *' --:._ ' . -----... . . . 360 . * *
  • _/ * * * * * * * * * * * * * ~*--~~ *--~:-., .** ..: .* ~-*-**-*-;~_*_* : * * * * * * * * * *
  • I . . *------*----/ 80 -200-+-' .......... ~L..-.....__~~L..-.....____.____,c----...___.___.~-,---'---'~-'---r---'~-'--~--t 500 6500 12500 24500 0500 Ti e (sec) Figure RAl-4.30-1 Westinghouse Uptlow Barrel/Baffle Plant Category Case I -ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 576 of 782 S'lllTCHO ER TIME *----To I ECCS Flow *--------EC C S F I o o V e s s -----ECC5 Flow o e Crossover Legs *""" Su of Flo e Vessel o d Crossover Legs u <I) U1 -.......... .0 <l) .......... a::: ?.: 0 LL U) U) 0 600 400 200 . > ,' \\ . . . I . . . . . -.,. ' ' I ,,, ... * *

  • t4I ';'":* . . . ' . . -.. . . ------------.......... : .... ... :::!._~:~-~-.... : .......... . I ~-. *-*-,*-* . . ,..--: --,---*-----------1J*./ ,I : ****,v***************************************************** ,J : ~. I I 0 I. .......... : ........... : ................................ . -200-+-'--l...----....__~__.~....__--'-~~.,_____..____._~~...l....--L..--1~~......L.---L~.l..---l 500 6500 2500 8500 24500 Ti e (sec) Figure RAl-4.30-2 Westinghouse Upflow Barrel/Baffle Plant Category Case 2 -ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
  • *
  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 577 of 782 *----*--------.-*" 00 SWITCHOVER TIME Tool ECCS Flo*w ECCS Flo o ECCS Flow o t Sum of Flow o Vessel e Crossover Legs e Vessel o d Crossover 600 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * --u Q) (/) ............. ..0 ....__ (J.) ........ 0 0::: :: 0 LL (/1 (/1 0 2 400 -200 500 6500 12500 18500 24500 Ti e (sec) Legs Figure RAl-4.30-3 Westinghouse Upflow Barrel/Baffle Plant Category Case 3 -ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 'HIT HOVER TIME *----To I ECCS Flo*w *--------ECCS FI ow o e Yes s I WCAP-17788, Volume 4 RAJ Responses Page 578 of 782 4t----ECCS Flow o e Crossover Legs _..._ u QJ C/) -...... .D .___... ......., 0 Cl:'.: 3: 0 I.J_ C/) C/) 0 ..2 00 600 400 200 0 Su of Flo o e Vessel ad Crossover Legs .......... --. -(\I"!".'-+, ... _ ... , *--200+-'_.___..__....__-.--__.~....__~---.~~~~~.---~~~~-.-~--'~~--i 500 6500 2500 8500 24500 30500 Ti e (sec) Figure RAl-4.30-4 Westinghouse Upflow Barrel/Baffle Plant Category Case 4 -ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

  • *
  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 *----*--------~ITCHO ER TIME Tool ECCS Flow ECCS Flow *o Vessel ECCS Flow o he Crossover Legs WCAP-17788, Volume 4 RAI Responses Page 579 of 782 ----Sum of flow to he Vessel ad Crossover Legs ...---... (..) (I) C/l ......__ ..0 ..__.. (I) __.. n::: ::-, 0 LL.-(J) (J) Cl 00 600 400 200 I ' ~*w'"'\r , , *' ,, ,: .,.... .. .A.-:..:.. *.-. .. . . . _..__ O \./. .'-'-.-rv~--.f\.,.'.'-'.':-'~~~~~~: .At ... -:-... e: ,..,...,.,...-.._,. ....... --200-+--..___._~....._....._-----.-~_.____._____.~.....-_.._____..___...._-,-~.....__..____._~....-----'----------'----I 500 6500 12500 8500 24500 30500 Ti e {sec) Figure RAl-4.30-5 Westinghouse Upflow Barrel/Baffle Plant Category Case 5 -ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 *----*----------*' ,,_ __ SWITCHO ER 11ME Broken Loop SG Exi ct Loop SG Exi oct Loop 2 SC Exi oct Loop 3 S Exi I S E , Flow WCAP-17788, Volume 4 RAI Responses Page 580 of 782 T-*-*-I Flow o t e Cross O er Legs -u (L) (11 E aoo-r-.------------------------------, 600 .... * .... ...a 400 (L) 0 0::: :s: o 200 LL. *

  • 0 -200 500 6500 2500 8500 24500 JOSOO Ti e (sec) Figure RAI-4.30-6 Westinghouse Upflow Barrel/Baffle Plant Category Case 1 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) *
  • *
  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 *----*----------*" ..---S't1 ITCHOVER TIME roken Loop SG Ex, ct Loop SG Exi oct loop 2 SG Exi ct Loop 3 SC Exi I SG Exi Flo WCAP-17788, Volume 4 RA! Responses Page 581 of782 Y-*-*-I Flo# o e Cross O er Le s ..--... u Cl) .............. E ..0 Q) 0 0::: 3; 0 LI... C/l C/l 600 * * * * * * * * *
  • 400 * * * *
  • 200 0 -200-._..__...__.___~_.___._..._~_....__.___._~_.__....__._--,_....____.__..__--i 500 6500 2500 8500 24500 30500 Ti e (sec) Figure RAl-4.30-7 Westinghouse Uptlow Barrel/Baffle Plant Category Case 2 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-1 7788, Volume 4 RA I Responses Page 582 of 782 *----*-------------y--Y-*-*-200 20 ---u en ---... E ...a 40 QJ ......, 0 0:::: o -40 l.J._ Ul en 0 -20 SWITCHO ER TIME Broken Loop SG Ex, act Loop SG Exi oct Loop 2 SG Exi oct Loop 3 SC Exi al SG Exit Flow ol Flo~ o e Cross 0 er le s -2()()-+--'--'----l.~'--.....----'----'~'--.....----'----'~-'--.....----'----'~-'----,-----'---'~...__--I 500 6500 2500 8500 24500 30500 Ti e (sec) Figure RAl-4.30-8 Westinghouse Upflow Barrel/Baffle Plant Category Case 3 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

  • *
  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 *----*-------. --* 't'---SWITCHO ER TIME Broken Loop SG Ex, I ct Loop SC Exi oct Loop 2 SG Exi act Loop 3 S Exi al S E Flo WCAP-17788, Volume 4 RAJ Responses Page 583 of782 Y-*-*-e Cross 0 er Le s ..----. u <I.) (.fl "-.... E ..0 .__.. <I.) 0 0:: 3: 0 LL. V) (/) 2 20 1 * * * * * * * * * * * * * * * * * *
  • 40 20 * * * * * * * * * * -200 500 6500 12500 8500 24500 JOSOO Ti e sec) Figure RAI-4.30-9 Westinghouse Upflow Barrel/Baffle Plant Category Case 4 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 584 of 782 *---* *-------* --*" .,.._ --'f'"-*-*-.......... u QJ C/1 ............ E ....0 -<I) ........ 0 n:::: s: 0 LL._ V'l (/) 0 :::::!?: 200 20 I . 40 20 -200 500 S'illT HO ER TIME Broken Loop I ct Loop I ct Loop oct Loop I SG Exi SG E JC I SG Exl 2 SG Exi 3 SC Exi Flo I Flow co e Cross O er Le s 6500 2500 8500 Ti e (sec) 24500 30500 Figure RAI-4.30-10 Westinghouse Upflow Barrel/Baffle Plant Category Case 5 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

  • *
  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 585 of782 SY ITCHOVER TIME *---*Toal Vessel Flow ro the Cold Legs *-------* C o r e I ll I t F I o w 4t---* BB I I e FI ow HSN lnl t flow Y---I act HL Nozzle Flow Y-*-*-Bo i I -o
  • a, e ....-... u (I) (fl .............. E ...Q -(I) ........ 0 ex 0 LL. (fl (fl 0 2 800 400 200 0 I ',' * ** ._ \ I . , .. I ' ' ', ' \ ' * * * ...... ' : ..... . ltf **..* \,* ......... ************'"'**** .......................... . I ' ', ' . .*.._ ....... -.... . -.~ .. ~----:a--.......... ----. __ : ..................... :-~-:-*-*-~~.:. ................... . . -*-----.... .,.---: ---*: . -:-. ------**---, . .;:-7~ ~.,. \r"' "-.., ,,~ J\~"t'1° ~\. . f1, Yv1 /\~* ........................................................ -200-+-'L.....1..-L--'--~___JL_..,___._~_..____.___.__~....L.--l._L-..,..---l.__;L_..J._--l 500 6500 12500 Ti e (sec) 24500 30500 Figure RAl-4.30-11 Westinghouse Upflow Barrel/Baffle Plant Category Case 1 -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 586 of 782 *----*------------.-~*-*-800 SWITCHOVER TIME Tool Vessel Flow ro the Cold Legs Core Inlet Flow BB I let Flow HSN Inlet Flow I act HL Nozzle Flow Boil-o Roe 600 l . . f'a ....... : .. ,, .. ' ' . ,. l , ., '*411111, .* . . ,:, . -. -. . ~, ..... .............. -**............... . ............ . \ . . --*--... . 400 *\ ... ..,. ~¥*----~-..... --~-. . -----._, . 200 * * * * * * * * * * * * * * * * * ~:~-.* ~:...:...:.;~.*_:_ * . * ...... . ...., ........ --:----*: * -: --._-:------tt--v= ..... -..£l . !'\,./r~-::;J..,,J ' . 0 -200+-'---'---'----'~,---'----'---'-~.--..i.....-'---'---.~....__.....L..._._~~'---..i.....-'---i 500 6500 2500 8500 Ti e sec) 24500 30500 Figure RAI-4.30-12 Westinghouse Upflow Barrel/Baffle Plant Category Case 2 -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • I _I -Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 SWITCHOVER TIME WCAP-17788, Volume 4 RAI Responses Page 587 of782 *----Toal Vessel Flow ro the Cold Les *--------C o r e I n I e t F I o w e----BB I I e FI ow *° HSN Inlet Flow Y---I act HL Nozzle Flow ..,......._,_ Boil-o
  • Raie 00....--.------------------------------, ..--... u Q) t/l -...... E ..0 ----Q) +-' a a:::: :i:: 0 G:: (/'l t/l a 600 ....................... .. -200 500 6500 12500 8500 Time (sec) 24500 30500 Figure RAl-4.30-13 Westinghouse Uptlow Barrel/Baffle Plant Category Case 3 -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 588 of 782 S~ITCHO ER TIME *----Tool Vessel Flow ro the Cold Legs *-------* C o r e I n I t F I o w tt----8 I le Flow *""-HSN Inlet Flow .----In oct HL Nozzle Flow T--*-Bo i I -o Ro re 800-,---,--------------------------, -u (U (/J ............. E 600 ::9 400 (U ........ 0 0::: s: O 200 c;: (/) (/J I ,Jf!,.:.J:.,..--11\,~** --* ...:-*------*--*--* .. . ._.... . . ~. .'.-_-:-***.................................. ---." ---* *--__ ...... ...: ____ . ____ _ . . -e-=----... -* --~ ______ .,_ __ -...----:-..... ---. . . 0 ,....,_*~-._..,. __ "'r" -~A--T-:-*-1'-*_..,-: -?---* -L'-~,._---.---:-.~ ~-~.~. * .. -~-~ .-:. * ~. -200.+-J.......L..---1-L........---'----'-L........---'----1-.L........---'----'-.L....~---'----'-..1...--I 500 6500 2500 8500 Time (sec) 21500 J050 Figure RAl-4.30-14 Westinghouse Upflow Barrel/Baffle Plant Category Case 4 -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 SWITCHOVER TIME WCAP-17788, Volume 4 RAJ Responses Page 589 of 782 *----Toal Vessel Flow ro the C Id Legs *--------C o r e I n I t F I o w -----BB In I et FI ow
  • HSN lnl t Flow y---In ct HL Nozzle Flow T-*-*-Bo i 1-o Ro e 600 .. * * * ..--.. u Q.) (/1 .............. E ...0 400 ....._... Q.) +-' 0 0:::: ;;: 0 LL. (/l (/l 0 -200-+--'---'~.,___--r----'-~'---'---r----'-~'---'---.---'-~.,___-'---r---J'---'---L----l 500 6500 2500 24500 30500 Ti e (sec) Figure RAl-4.30-15 Westinghouse Upflow Barrel/Baffle Plant Category Case 5 -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 590 of782 S ITCHOVER TIME a---* lo ol ECCS Flow *-------* ECCS Flo o h ess I ----* ECCS Flow to he Crossover Legs .---Sm of Flo* o the essel ond Crossover Legs ..--... u Q) (I) ....._ ..0 ..__... Q) ......, 0 a:::: 0 l1... (I) (I) 0 ()OO""T""r-----------------------------, 760 . *'* ....................................................... . . ~--__-.:._.-***-* ..... _ .. ___ --w; '. . ____ .... -* . . : . _ ... -, r ....... *7r*:** ......... :* .......... :* ......... *:* ......... . ~,,~ , .. ,, .. , 2 i ...... ,_ : : : : **,** ..... *-"'* .. ** .......................................... . I . ..,_ .. _*-.. -~.. ... . . . ' *---.... . ~--.. *~-,-... .. ---.. *----200 500 6500 2500 \8500 24500 Time (secJ Figure RAI-4.30-16 Westinghouse Downflow Barrel/Baffle Plant Category Case 1 -ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

  • *
  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 591 of782 SWITCHOVER TIIJE * ----lo a I ECCS FI ow *--------EC S Flo<< o he Vessel e----EC S Flow to the Crossover legs *-Su of rlo* o the Vessel and Crossover Legs 000-.-....---------------------------..... --.. u Q,) en -..... ..0 ....._... (1) ....... 0 a:: :,. 0 I.J.... V) Cf) 0 2 760 520 280 * -200 500 . . -.,. .. ,v,~*-...-*-"***'--. ,-.1/A:\f\..J\',r ..,. . . "' ..,,,,.,., \ /V... . . . ..,.-""\., . . . *1* _,, . . *,/'. . . . . ~*J'* ~~---~ ......... : ........... : ........... : .......... . ,* . ..., .. ~-.. ,e ,* . . I -*** \ ... , .* , . . . . *-* ... , ' '*-:-,.,..,..... . . . . ." .... , -... ,.,-. ... ,-,,* .. ,--.. t I 6500 2500 l8500 Time (seCJ 24500 30500 Figure RAl-4.30-17 Westinghouse Downflow Barrel/Baffle Plant Category Case 2 -ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 592 of 782 S I TCHOVER TI ME *----lo ol ECCS Flow *--------ECCS Flo 10 e s s I -----EC S flow to ht Crossover Legs ..--.. u (1) Cl) '-... :::9 -(1) -0 a::: > 0 u.. Cl) Cl) 0 o t e essel ad C,osso er Legs 000 760 520 # ,,,4, . . . . 280 ......... ,~ ................................................... . ... ~..... . .---.--------40 -200 500 . '*--, -~.--,-:-: -* I;.,.--: **-*1'*,:-*-,*---~-+---,-*,--* -v . ... / , ....................................................... . 2500 8.500 Time (sec 24500 Figure RAl-4.30-18 Westinghouse Downflow Barrel/Baffle Plant Category Case 3-ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 593 of 782 *----SWITCHOVER TIME lo ol ECCS Flow ECCS Flo* o ECCS Flo* to *--------e Vess I ----* , Crossov,r legs S urn of F Io* o the essel ond Crossover Legs aoo...-.....----------------------------. 600 .......... u Q.) (/) --... .c 400 ....._.... 0 200 LL (/) (I) 0 :a: 0 4 -.I I..,_, * * * * ......... "~~"~* .,':'; .......................................... . * #4 "*-,-... * * . -,.,_,*'----+-~-, . . aL....--* _-.-;. ***~ . ~.-~----. , ..... .---. . .,.r ' .,,.. . . . . !~1/lr. .. : .... ~-.... : ........... : ........... : .......... . -200-+-....... _.___..___,..__...__...._ ....... ......,-......_ ....... __._ ............... __._...__...,...__._...__....._--t 500 6500 2soo issoo Time (sec) 24500 Figure RAI-4.30-19 Westinghouse Downflow Barrel/Baffle Plant Category Case 4 -ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 S ITCHOVER Tit.IE a ----1 o o I ECCS FI ow *--------EC CS f I o

  • o e Vess I WCAP-17788, Volume 4 RAJ Responses Page 594 of 782 -----EC S flo* to c Crossover Legs > 0 I.J_ (/'J (I) 0 800 600 -200 500 Sum of Flo* o the essel and Crossover Legs 2500 t8500 Time {secJ 24500 Figure RAl-4.30-20 Westinghouse Downflow Barrel/Baffle Plant Category Case 5 -ECCS Flow Split in the Cold Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 SWITCHOVER TI IAE *---* Broken Loop SC Exit *-------* In ct Loop SG Ex i e----In oct loop 2 SG Exi lotol SC Exi Flow WCAP-17788, Volume 4 RAJ Responses Page 595 of 782 ..---lo al fie* o e Cros 0¥er Leg .--u cu en ............ ..0 Q) 0 a::: > 0 u::: (I) (I) 0 ::E 800 600 ~00 ' I I . . . . . , . I. *..**..............................*..*.......*........ ;~If .,;,r : : : : 200 0 -200 500 6500 2500 8500 Time (sec 24500 Figure RAl-4.30-21 Westinghouse Downflow Barrel/Baffle Plant Category Case 1 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 SWITCHOVER TIIAE *---* Broke Loop SG Exit *-------* In act Loop SG Exi e---* I n o c t Loop 2 S G Ex i 'lll---lo ol SC Exi Flo WCAP-17788, Volume 4 RAJ Responses Page 596 of 782 .---lo al Flo* o lie Cros Over Legs ..--u Q) (/) ........... ..0 ,;:::... Q) 0 0::: 0 u_ (/) (/) 0 :.:: 800 600 400 200 0 -200 500 I I I :

  • I I 2500 l8500 Time (secJ 24500 Figure RAI-4.30-22 Westinghouse Downflow Barrel/Baffle Plant Category Case 2 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
  • *
  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 597 of 782 SWITCHOVER TIIJE *---* Broke Loop SG Exit *--------I II oc t Loop SG Ex i -----lritoct loop SG Exit ..---lo ol SC Exi Flow ...---Toial Flo 0 e Cros Over Le9s ....---.. u Q) (I') --..a .:::=, <U a:: 0 u:: (/) (I') 0 2 --.......... :.------. . ____ ,,..... . . -r . ..--. . I 160 . ....... . I ,r, ,'.).',t L'"'t)
  • r 'It ................ r". . *,t ..... ,,. ,,, 1. ,. ...*. I,,, . . ,, '-l \ l ,_, V* :,,c: ./ *, -.; . I * :I/ ,, ' : I I ' J ,/\ (f~ '. tt/ . I ' I I . ' ~. : J *~ . . :~\ }1'/ t. . . l -2(!()-t-"~~--~-r-~--~~--.-~--~~___,.--~~~--,--~~~----1 500 6500 2500 \8500 Time (secJ 24500 30500 Figure RAl-4.30-23 Westinghouse Downflow Barrel/Baffle Plant Category Case 3 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 598 of 782 *-------* ----* ..---T----Q) 0 a::: -120 S'NI TCHOVE:R TI IIE Broke Loop SG Exit lniact Loop SG Exit Intact Loop 2 SG Exi lo al SC Exi Flow lo al Flo* o ~e Cross Over Leg -200-+-'~~---~~~~---~~~~---~~~~---~~~~~~--1 500 2500 l8500 Time (secJ 24500 30500 Figure RAI-4.30-24 Westinghouse Downflow Barrel/Baffle Plant Category Case 4 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

  • *
  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 SNITCHOVER Tit.IE *----Broken Loop SG Exit *--------In ct loop SG Exi -----In oct loop 2 SG Exi w---Totol SC Exi Flow WCAP-17788, Volume 4 RAJ Responses Page 599 of 782 y---lo al fie* o Cros Over leq 120 ...--u Q) I: (/) .......... ...0 ..::::::;.. Cl) 0 a:::: ::,;. 0 u:: (/) (/) 0 == -120 -200-+-'_.___. __ .__..,,___.___. __ ....._-,-__.___. __ ....._"""T""__.___,.___,__"-T""__.. __ .....__._-1 500 2500 \8.500 Time (secJ 24500 30500 Figure RAl-4.30-25 Westinghouse Downflow Barrel/Baffle Plant Category Case 5 -Flow at the Steam Generator Outlet *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 600 of 782 SWI TCHOVE:R TI IJE *----lo ol Vessel Flow rom t e Cold Legs *--------Core I le Flow e---* UHSN lnle Flow *'---ln!oct HL Nozzle r10 .---Boil-of Roe ...--.. u <U (/) -...... ..C) -=- 0 u.. (/) (/) 0 ::;:: 600 200 0 . , ........................................................ . f'. * * * * ~, . .... ' .................................................... . \ , .. ,. \ ._ .. '. ' ... ', . ::a. -~--~ .... _ . . . ........... : .... =-* ... *-*-~ .. ,..-..::a:.:.:..:.* ...... : .......... . . -***--*.;-=-~-...... -...... -* --: : --"-~~--*---*-*-* -200 500 6500 2soo iasoo 24500 Time (secJ Figure RAI-4.30-26 Westinghouse Downflow Barrel/Baffle Plant Category Case I -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

  • *
  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume4 RAI Responses Page 60 I of 782 S I TCHOVE:R TI IAE *----lo ol Vessel Flow rom t e Cold Legs *--------Core I le Flow 4t----UHSN I le Flow 111----lntoct HL Nozzle Flo* .,---Bo i I-of Ro e 800 600 ...--<.) Cl.> Cl) ............. .L) 400 ' ' Cl.> .... .
  • 0 a::: '.... . ",.. . ,,* 0 200 0:::: . "-' . .............. , ........................ ,. .............................. . * ... ............. _ \,A*, * ,. ,. ,,.. * * * .... #,~ * * .. ""\\ JI, ,_ L ,_a (/) U) 0 0 -200 500 6500 ., \. .. ,,,,~--* .. -f1ll9 ' -: : ~, * .,.,N~,.,..,-,,.-.. * ._ .. _. 2500 8.500 24500 30500 lime (sec Figure RAl-4.30-27 Westinghouse Downflow Barrel/Baffle Plant Category Case 2 -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 602 of 782 S'NITCHOVER TIME: *----lo ol Vessel Flow rom t e Cold Legs *--------Core I le flow e-----UHSN In I e f I ow ----lnloct HL Nozzle F"low y----Boil-of RQ ..0 <U 0 a::: 800 600 400 200 ,:.:-......... * ........... : ........... : .......... . *--.. --...... . . 0 -200 500 ---*--*---.::. *-*--..... -** -. -----* -ii: --. *----*-.,------~------.-.:-:~ --_.....,._ ................................................... . 24500 30500 2500 \8500 Time (secJ Figure RAI-4.30-28 Westinghouse Downflow Barrel/Baffle Plant Category Case 3 -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 603 of 782 s~*I TCHOVE:R r '"E *----Tool Vessel Flow from the Cold Legs *--------Core I le Flow e----UH SN I I e FI ow In act HL Nozzle Flo* ?---Boil-of Rae 800-,-,-----------------------------, 600 ,.._ u Q) (/) " .L:I -=-400 Q) .. :,. 0 u::: (/') (/) 0 200 .... ': ,'-..-~********************************** ---.... -ii----* ----. . --~--------?Ill--* *~--,,.... .. _*-~---:--..:-:. == 0 -2(!()-t-' .......... ___.~....._--r-........ ~.....__._--,-___.,___......__.___,~.....__._ ........ ~~-'-~~.___. 500 ~o 2500 \8500 Time (seC) 24500 Figure RAI-4.30-29 Westinghouse Downflow Barrel/Baffle Plant Category Case 4 -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 SWITCH0\1£R TIIAE WCAP-17788, Volume 4 RAI Responses Page 604 of 782 *----To al Vessel Flow rom the Cold Legs * -------Core I I e FI ow -----UHSN I le Flow In act HL Nozzle rlo* .---Boil-of R<1 800-.--,.----------------------------, ---u Q.> en ....._ ..c .:::::, Q.> 0 0:::: 0 u.. VI en 0 600 400 200 0 -200 500 2500 l8500 Time {secJ 24500 Figure RAl-4.30-30 Westinghouse Downflow Barrel/Baffle Plant Category Case 5 -Reactor Vessel Flow Split *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 605 of 782 b. Define how msplit is calculated in Case 1 B considered in Figure 8-19 and illustrate the msµIit calculation for this case by plotting the rate (in units of lbm/s) of liquid flow into the core and into the BB AFP, the ECCS recirculation flow, the flow into the upper plenum via the SGs, if predicted, and the calculated msplit ratio (in dimensionless units) as functions of time. Response The parameter msµIit is defined as the fraction of ECCS recirculation flow entering the reactor vessel downcomer that reaches the core region through the AFPs and is calculated as follows: where, mss + muHSN msplit = mEccs-vs m88 = The liquid mass flow rate through the BB channel mu HSN = The liquid mass flow rate through the UHSNs Eq. RAl-4.30-1 mEccs-vs = The liquid mass flow rate from the cold legs into the downcomer The calculation of msplit for Case 18 considered in WCAP-17788-P/NP, Volume 4, Figure 8-19 is illustrated as shown in Figure RAI-4.30-31, which shows the total ECCS recirculation flow, core inlet flow, BB channel inlet flow, the UHSN inlet flow, and the intact HL flow into the upper plenum. As seen in the figure, prior to complete core inlet blockage, approximately all ECCS flow reaches the core through the core inlet. Following complete core inlet blockage, flow through the core inlet ceases and a fraction of the ECCS flow enters the BB channel, with another fraction entering the UHSNs. The remainder of the ECCS liquid flows into the crossover legs and steam generators. After the crossover legs fill, the majority of ECCS liquid that does not flow into the reactor vessel through the cold legs flows through the broken loop steam generator and out of the break in the hot leg. Only a small fraction of ECCS liquid flows into the intact loop steam generators and reaches the upper plenum. The calculation of msµIit for this transient is shown in Figure RAI-4.30-32. As expected, prior to complete core inlet blockage, msplit is approximately zero and after complete core inlet blockage mspli1 is approximately one . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 606 of 782 .. T o t o I ECCS Flow . ----C o r e I nle Flow *--------BB I I e t FI o 'It' -----UHSN I nle Flow ...,_ I n t o c HL F I ow o e Up er Pie u 800 600

  • I ' ...0 400 ........... : .. r, ........ : ........... : ... . I :i 200 ....................... :1 ................................. . 0 -200 0 4500 :1, 8500 Ti 250 e (sec) 6500 20 00 Figure RAl-4.30-31 The Total ECCS Flow, the Core, BB and UHSN Inlet Flows, and Flow into the Upper Plenum from the Intact Hot Legs *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAI Responses Page 607 of 782 ... 0... en E Fr a c Io o' To t Vessel Flow Bypassing he Core 2.....------------------------------, 1.5 .s 0 -0.5-~-~~--,--~~~--,,_~~-~~~-~~-.-~~~~--t 500 4500 850 Ti 12500 e (sec) 650 20500 Figure RAl-4.30-32 Upflow Plant analysis m,pi;, Following Complete Core Inlet Blockage I e *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788, Volume 4 RAJ Responses Page 608 of 782 c. Provide details of the calculation ofmsplit for any runs that resulted in liquid transport into the reactor upper plenum via the SGs. Response Equation RAl-4.30-1 defines the parameter msplit* As shown in the equation, only the net flow that enters the reactor vessel downcomer is considered in the calculation of msplit* In this fashion, any liquid that enters the crossover legs and flows around the SGs to the break, or the upper plenum is not considered, and it is assumed that all debris that enters the reactor coolant system flows with the fraction of liquid that enters the reactor vessel. This introduces conservatism in the in-vessel debris evaluation by not taking credit for debris bypass due to the flow split at the ECCS injection points in the cold legs following the application of core inlet resistance. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups WCAP-17788-NP Mark-ups Page 609 of 782 Revisions to WCAP-17788-NP, Volume I and Volume 4, Revision Oare included in this section. After receipt of the Final Safety Evaluation, the NRC Approved version of the TR will incorporate the proposed revisions. Revisions are identified with revision bars in the left margin. Deleted text is identified as red font with a single strikethrough and new text is identified as red font. Revisions to the TR are summarized as follows:
  • Volume 1, pg. 3-3: Two corrections are made to the component terminology provided in Table 3-1
  • Volume I, pgs. 3-13 through 3-18: Corrections are made to various typographical errors and additional clarifying information is added
  • Volume 1, pg. 4-5: A typographical error is corrected
  • Volume 1, pgs. 6-2 through 6-7: Updates are made consistent with the thermal hydraulic reanalyses completed for the Westinghouse downflow, CE, and B&W plant categories
  • Volume 1, pg. 6-10: Added a statement to identify the need to scale fibrous debris loads if the fuel assembly pitch is different than what was assumed in the subscale testing, consistent with the response to RA I-1.1 Item c
  • Volume 1, pg. 6-12: Updates are made to the CE and B&W flow areas to reflect the response to RAI-1.9
  • Volume 1, pgs. 6-15 and 6-17: The Westinghouse downflow plant category Kmax values in Tables 6-3 and 6-5 are updated to reflect the reanalysis value
  • Volume I, pg. 6-16: Updates are made to the CE and B&W flow areas to reflect the response to RAl-1.9
  • Volume 1, pg. 6-19: The first sentence in Section 6.4.3.1 is updated to provide clarity
  • Volume 1, pg. 6-25: Additional information is provided to clarify the B& W plant category large hot leg break in-vessel debris limit, and applicability to the method for verifying the hot leg break in-vessel debris limits
  • Volume I, pgs. 6-36 and 6-37: Step 8 is updated to reflect the response to RAI-1.1 Item c
  • Volume I, pg. 6-38 (previously pg. 6-37): Step 9 is updated to reflect the response to RAI-4.20
  • Volume 1, pg. 6-39 (previously pg. 6-38): A typographical error is corrected *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 610 of782

  • Volume 1, pg. 9-4: The second to last paragraph in Section 9.2.2 is removed to be consistent with the Section 7 supplement
  • Volume 4, pg. xvi: Reactor Building Spray (RBS) is added to the acronym list
  • Volume 4, pg. 2-4: Added a statement that the Ksplit and msplit analyses are no longer required for the B&W plant category
  • Volume 4, pgs. 4-3 through 4-5: Updates are made to the Critical Inputs Section to reflect changes due to the RAJ responses, and a reference to the ANS/ANSI-5.1-1979 decay heat standard was added
  • Volume 4, pg. 5-3: Added reference to EM BAW-10192
  • Volume 4, pg. 5-5: Removed Section 5.4 consistent with the response to RAI-4.11
  • Volume 4, pg. 5-5: Updated reference 5-6 and added the reference for report BA W-10192
  • Volume 4, pg. 6-2: Replaced Reference 6-2 with the response to RAI-4.2, which will be contained in Appendix A
  • Volume 4, pg. 6-2: Updated the barrel/baffle flow resistance and removed the minimum resistance value in Table 6-2 since it is no longer used in the analyses
  • Volume 4, pg. 6-3: Replaced Reference 6-2 with the response to RAI-4.2, which will be contained in Appendix A
  • Volume 4, pg. 6-4: Updated the upper head spray nozzle flow resistance and removed the minimum resistance value in Table 6-3 since it is no longer used in the analyses
  • Volume 4, pg. 6-5: Updated the CE decay heat model description, the break boundary condition, and the fuel assembly flow area to be consistent with the CE reanalysis
  • Volume 4, pg. 6-5: Replaced References 6-3 and 6-4 with the response to RAI-4.3, which will be contained in Appendix A
  • Volume 4, pg. 6-5: Updated the CE flow area to reflect the response to RAl-1.9
  • Volume 4, pg. 6-6: Updated Table 6-3 to reflect the CE reanalysis
  • Volume 4, pgs. 6-6 through 6-8: Updated the B&W plant model description to reflect the reanalysis
  • Volume 4, pg. 6-7: Updated the B&W flow area to reflect the response to RAl-1.9 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 611 of782
  • Volume 4, pg. 6-8: Removed References 6-2, 6-3, and 6-4 from the references list
  • Volume 4, pgs. 7-1 and 7-2: Added clarifying text to the RCS description prior to debris arrival
  • Volume 4, pg. 7-4: Added clarifying text to the RCS description after debris arrival
  • Volume 4, pgs. 8-1 and 8-2: Updated to reflect the Ksplit and msplit reanalyses consistent with the response to RAI-4.20
  • Volume 4, pgs. 8-5 through 8-8 (added pg. 8-8): Updated to reflect the Ksplit and msplit reanalyses consistent with the response to RAI-4.20
  • Volume 4, pgs. 8-43 through 8-57 (previously pgs. 8-42 through 8-56): Updated to reflect the Ksplit and msplit reanalyses consistent with the response to RAI-4.20
  • Volume 4, pg. 8-59 (previously pg. 8-58): Updated to reflect the Ksplit and msplit reanalyses consistent with the response to RAl-4.20
  • Volume 4, pg. 9-2: Updated to reflect the Kmax, Ksplii, and msplit reanalyses consistent with the responses to RAI-4.7 and RAI-4.20
  • Volume 4, pgs. 9-4 through 9-6: Updated to reflect the Kmax, Ksplit, and msplit reanalyses consistent with the responses to RAI-4.7 and RAl-4.20
  • Volume 4, pgs. 9-27 through 9-35: Updated to reflect the Kmax reanalysis consistent with the response to RAI-4.7
  • Volume 4, pgs. 9-36 through 9-50: Updated to reflect the Ksplit and msplit reanalyses consistent with the response to RAI-4.20
  • Volume 4, pg. 9-52: Updated to reflect the Kmax reanalysis consistent with the response to RAl-4.7
  • Volume 4, pgs. I 0-1 through 10-49 (previously pgs. I 0-1 through 10-48): Updated to reflect the CE plant category reanalysis
  • Volume 4, pgs. 11-1 through 11-27: Updated to reflect the B&W plant category reanalysis
  • Volume 4, pg. 12-2: Updates to reflect the Westinghouse downflow, CE, and B& W plant category reanalyses *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-1 Comparison of System and Component Terminology by NSSS Vendor B&W CE Emergency Core Emergency Core Cooling System (ECCS) Cooling System (ECCS) Reactor Building Spray Containment Spray (RBS) System System (CSS) Decay Heat Removal Shutdown Cooling (DHR) System System (SCS) System Names Low Pressure Injection Low Pressure Safety (LPI) Injection (LPSI) I High Pressure Injection High@F Pressure Safety (HPI) Injection (HPSI) Core Flood Tanks Safety Injection Tanks (CFTs) (SITs) High head normal Centrifugal Charging makeup and purification Injection (CCI) Pumps (HPI pumps for all but DB) Components by Function Tank that stores borated water for Borated Water Storage Refueling Water Tank safety injection/refueling Tank(BWST) (RWT) Supplemental tanks with Boric Acid Storage Boric Acid Mixing concentrated boric acid solution Tank(BAST) Tank(BAMT) I Pump(s) used to supply low-head :i;ieae~* Heel EJ:;m,Low Low Pressure Safety safety injection/recirculation flow Pressure Injecuon (LP!) Injection (LPSI) Pump Pump Pump(s) used to supply high-High Pressure Injection High Pressure Safety pressure safety (HPI)Pump Injection (HPSI) Pump injection/recirculation flow Heat exchangers that provide Decay Heat Coolers Shutdown Cooling Heat decay heat and residual heat (DHCs) Exchangers (SCHXs) removal Furn ps that supply containment Reactor Building Spray Containment Spray (CS) spray flow (RBS)Pumps Pumps Heat exchangers that cool None SCHXs containment spray Nozzles that deliver spray to Building Spray Nozzles CS Nozzles containment building WCAP-17788-NP Mark-ups Page 612 of782 3-3 Westinghouse Emergency Core Cooling System (ECCS) Containment Spray System (CSS) Residual Heat Removal (RHR) System Low-Head Safety Injection (LHSI) High-Head Safety Injection (HHS!) Accumulators (ACCs) Centrifugal Charging Injection (CCI), Chemical and Volume Control System (CVCS) Refueling Water Storage Tank (RWST) Boric Acid Storage Tank(BAST) LHSI Pump, Residual Heat Removal (RHR) Pump HHSI Pump, CCI Pump, or Intermediate-Head Safety Injection (IHSI) Pump RHR Heat Exchangers CS Pumps CS Heat Exchangers cs ozzles *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 613 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-13 3.3 DESCRIPTION OF PWR LOCA AND SAFEGUARDS OPERATIONS The material in this section is general in nature and is presented for background purposes only. The system descriptions are intended to provide useful information about plant design and configuration but should not be used as input to licensing basis analyses. Shortly after a LOCA, a number of safety systems automatically actuate to mitigate the event. In the longer term, operators take action to continue the mitigation and to ensure that the core remains cool. The specific systems that actuate are dependent on the plant design and the plant operating procedures. However, there are general similarities among the U.S. P\VR fleet. This section provides an overview of the event in that context. Note that the descriptions in the following sections relate to plants with cold side ECCS (i.e., plants that initially inject into the cold legs immediately following the LOCA) and are relevant to most of the operating PWR fleet in the U.S. However, there are a small number of plants that initially inject into both the RV UP and into the cold legs. These plants are referred to as upper plenum injection (UPI) plants and are Westinghouse 2-loop designs. While the sequence of events is similar, the flow path to the break during sump recirculation is typically opposite that of the cold leg recirculation plants. Additional discussion of the UPI plant is provided in Section 7 . 3.3.1 General Sequence of Events FoUowing a Large Break LOCA The following is a generic description of a large break LOCA progression in a PWR. Plant-specific designs and operations may result in plant-specific variations from the progression described below. The large break LOCA (LBLOCA) is characterized by rapid depressurization of the RCS to a pressure in near equilibrium with the containment pressure and low enough to allow the operation of the low head safety injection (LHSI) pumps. Containment is isolated due to high containment pressure. In the term, all available ECCS inventory, including the accumulators, is necessary to refill the vessel and recover the core with allowance for a single active failure. The CSS could also be actuated. Supply for both the ECCS and CSS are initially drawn from the refueling water storage tank (RWST). The borated water from this tank helps to reflood the core with fluid containing an effective neutron absorber. Due to RWST injection, the core can be expected to be reflooded and quenched within a few minutes. Fuel cladding temperatures after reflood have decreased to within a few degrees of the liquid saturation temperature. The RWST contains enough coolant for injection to last approximately 20 minutes at maximum ECCS and CSS flow (i.e., no single failures). Initial safety injection flow is into the cold legs (with the exception of UPI plants, where flow is injected into both the RV UP and cold legs). After the RWST has drained, an alternate source of coolant is required. At this point, the supply water source to the ECCS and CSS is switched from the RWST to the containment sump. Continued availability of this coolant assures LTCC. At some point after sump switchover (SSO), the Emergency Operating Procedures (EOPs) require that the operators take some action to mitigate potential boric acid buildup in the core. This is primarily a consideration following a CLB where there is limited liquid throughput in the core; as the core continues to boil, boric acid may concentrate. For HLBs, this is generally not a concern, because there is *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 614 of782 3-14 continuous liquid flow through the core to the break, which continually dilutes the boric acid. However, since the operators do not diagnose the break location, this action ismay be taken for all LOCAs. Westinghouse and CE designed PWRs require switching some or all safety injection to either hot leg recirculation (Westinghouse 3-& 4-loop and CE plants) or simultaneous hot and cold leg recirculation (Westinghouse 2-, 3-, 4-loop and CE plants). Some plants that do not maintain cold leg recirculation after the switch to hot leg recirculation require switching back and forth between hot leg and cold leg recirculation. B&W plants will only take action if core exit subcooling has not been reestablished. If an action is required, Ssome B& W plants may open the decay heat drop line to address boron precipitation, while others may not tab tms astionactuate the pressurizer spray as a hot leg injection method. The timeline for operator action is plant-specific, but will generally occur between 2 and 12 hours following the LOCA. 3.3.2 ECCS Configuration and Performance during Swnp Recirculation 3.3.2.1 Westinghouse Plants For the Westinghouse design, the ECCS components used during recirculation include the low head safety injection (LHSI) (also known as residual heat removal (RHR)) pumps and high head safety injection (HHS!) pumps, and various motor operated vales (MOVs), throttle valves, and check valves in the flow paths from the sump and the flow paths to the cold legs and to the hot legs. To meet the single failure criteria, it is necessary that each active component be duplicated. All valves that need to be opened for proper safety injection system (SIS) function are duplicated in parallel; all valves that must be closed are duplicated in series. All pumps are duplicated in parallel and are designed so that only one pump in each group needs to operate to provide sufficient volume of water to cool the core or the containment atmosphere, as the case may be. The recirculation phase following an accident is automatically or manually initiated either when the RWST low level alarm is actuated or when the operator is prepared to take positive action for a specific accident. Long-term recirculation will be required for any LOCA. For large breaks, the RCS will be depressurized by the initial blowdown. The RHR pumps are aligned to inject directly to the RCS while also providing the suction source to the HHS! pumps. Component cooling water is supplied to the RHR heat exchangers for cooling the sump water. The recirculation phase can continue with one RHR pump operating for a considerable period of time. If one RHR pump should stop functioning or require maintenance, the second RHR pump can be brought into service. The spray pump(s) will continue to inject RWST water into the containment through the spray headers until the RWST reaches a low-low level setpoint. In this case, it may be necessary to continue the spray to the containment using recirculation water. This duty can be performed by both the RHR pumps and the containment spray pumps. The CSS functions to reduce the reactor containment building pressure and quantity of fission products in the containment atmosphere subsequent to a LOCA. Pressure reduction is accomplished by spraying water into the containment atmosphere. The system consists of two independent and identical WCAP-17788-P-A October 2017 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 615 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 subsystems. During recirculation, the failure of a single active or single passive component will not prevent the system from perfonning its safeguard function. 3-15 The CSS consists of two pumps, spray ring headers, a number ofMOVs, and all necessary piping, instruments, and accessories to make the system operable. For the recirculation mode, manual operation of the system is performed remotely from the control room. When the RWST reaches the low-low leveL spray pump suction is switched from the RWST to the containment sump. A separate containment sump suction line is provided to each spray pump. These lines each contain two MOVs in series, in order to provide containment isolation. Two identical spray pumps are installed in the system. Either pump provides sufficient capacity to perform the necessary containment spray function. Spray flow is delivered from the containment sump to the spray headers. 3.3.2.2 Combustion Engineering Plants For CE design plants, borated water for high pressure and low pressure core injection and containment spray is provided by the Refueling Water Tank (RWT). Upon depletion of the RWT volume, a Recirculation Actuation Signal (RAS) realigns the ECCS and CSS suction to the containment sump. The RAS opens the containment sump recirculation line isolation valves and operators close the RWT discharge isolation valves. Transfer to the recirculation mode can also be established manually . In the recirculation mode, low pressure safety injection (LPSI) pumps are automatically secured and core flow is provided only by the high pressure safety injection (HPSI) pumps. However, operators may elect to restart LPSI flow during recirculation to provide additional core flow. Only one HPSI pump is required following recirculation since each train ofHPSI is designed to provide sufficient flow to make up that inventory Jost to boil off at the time of RAS. Recirculation is required only for a LOCA; no other design bases accidents result in depletion of the RWT volume. The decay heat and the latent system heat are removed post-accident to the ultimate heat sink by the shutdown cooling system heat exchangers (SCH.Xs) (through the CSS). In instances where there is sufficient net positive suction head (NPSH), the shutdown cooling system (SCS) can be aligned for LTCC. 3.3.2.3 Babcock and Wilcox Plants For B&W design plants, post-accident recirculation flow is provided by the low pressure injection (LPI) pumps. The recirculation alignment occurs when the borated water storage tank (BWST) has been drained and SIS inventory for recirculation comes from the containment sump, where the i-njsslsd RCS discharged liquid and spilled ECCS inventory collects. Recirculation will be required only for a LOCA. Only the LPI and RBS pumps are aligned to take suction from the sump during the recirculation mode. There are two separate pipes from the sump to the suction side of the LPI pumps and there is an MOV in each line. Depending on the plant, there are either two or three LPI pumps available. On the discharge side of the LPI pumps, there are check valves, MOVs, and the decay heat coolers . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 616 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-16 There are two separate injection paths which inject only to the reactor vessel core flood tank nozzles. Each low pressure pump is aligned to one nozzle or two, depending on the plant design. The containment sump is aligR0e le the seRtaiflffteRI spray pumps tlirnugli twe sepan1te flew paths euriRg resirsulatieRhas two separate discharge lines. Opening MOVs in one line allows suction to one LPI or RBS. The other line and separate MO Vs align to the other set of redundant LP! or RBS pumps. One pump of each type is sufficient to provide LTCC, but both trains will be used if they are available and there is not adequate subcooling at the core exit. The following component list is provided as a generic guideline for the type of equipment used for accident recirculation:

  • Pumps: LP!, CS
  • Heat exchangers: Decay heat coolers (DHR system)
  • Valves: MOVs, checks, throttle
  • Other: CS nozzles B&W units have similar systems and capabilities that are described in more detail for the CE and Westinghouse plants. These systems include those for containment spray, containment atmosphere control and containment isolation. These systems are not described here as they are similar to and function in a like manner as those systems described for the CE and Westinghouse plants. LTCC after a LBLOCA is well within the capability of a single decay heat removal pump operating at a containment pressure near atmospheric. Heat removal from the containment via containment spray and/or fan coolers will ensure that the containment pressure is near atmospheric pressure in the long-term postLOCA environment. Therefore, indefinite operation of the high pressure injection (HPI) pumps is not required except under certain single failures for some plants during LTCC after a large break LOCA. 3.3.3 Boric Acid Precipitation Control All three U.S. PWR designs (Westinghouse, CE, and B&W) use boron as a core reactivity control method and are subject to potential BAP in the core for scenarios that preclude ECCS flow through the core for extended periods following a LOCA. All three plant designs have ECCS features that include an active core dilution mechanism to prevent the core region boric acid concentration from reaching the precipitation point. These dilution mechanisms may or may not require operator action. The common approach for demonstrating adequate boric acid dilution in a post-LOCA scenario includes the use of simplified methods with conservative boundary conditions and assumptions. These simplified methods are used with limiting scenarios in calculations that determine the time at which appropriate operator action must be taken to initiate an active boric acid dilution flow path or alternately, to show that BAP will not occur. The three U.S. PWR designs have different ECCS con.figurations, different methodologies, and procedures for BAPC. Nevertheless, there are common approaches, assumptions and simplifications that have been used in virtually all PWR calculations that address the potential for BAP. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 617 of782 3-17 For typical plant designs (Westinghouse 2-loop UPI plants excluded), the limiting scenario for BAP is a large cold leg (pump discharge) break where the downcomer is eventually filled, and the excess ECCS flow exits out of the break. The ECCS flow into the core region is largely limited to that quantity boileoff in the core to remove the decay heat. The steam generated in the core travels around the intact hot leg(s) (or through the internals reactor vessel vent valves (RVVVs) in the B&W designed plants) to exit the break. Boric acid left behind accumulates in the core region and the boric acid concentration in the core region increases. The calculated rate of increase in boric acid concentration in the core region after a LOCA is directly affected by the asst1meEicalculated liquid volume. During this time, the core and UP are filled with a phase mixture for which the liquid content is dependent on the degree of voiding in the core and UP region. The degree of voiding is a function of the core decay heat and RCS pressure, and the pressure drop around the loop (or through the RVVVs) as it affects the hydrostatic balance between the downcomer head and the collapsed liquid level in the core. At low RCS pressures and high decay heat levels, the boiling in the core is vigorous, and the volume ofliquid in the core region is smaller. As the decay heat drops off, the boiling becomes Jess vigorous and more liquid is retained in the core region. Westinghouse 2-Joop UPI plants differ from typical PWR designs in that they utilize low pressure UPI. For these plants, the limiting large break LOCA BAP scenario is a HLB where the cold leg high pressure safety injection may be terminated at or prior to sump recirculation. This scenario is relevant only with the very conservative assumption that all UPI flow in excess of core boil-off bypasses the core region and flows directly out the break (i.e., no mixing in the core and UP). For Westinghouse design and CE design plants, BAP calculations are used to determine the appropriate time to switch some or all the ECCS sump recirculation flow to the hot leg or to otherwise show that BAP will not occur. For B&W-designed plants, BAP calculations are used to justify plant-specific active boric acid dilution methods or limitations on the dilution methods (e.g., plant-specific auxiliary pressurizer spray flows, protection of the sump strainer(s), prevention of potential water-hammer scenarios in the decay heat piping, challenges to NPSH limits for LPI pumps, hot and cold fluid mixing limits, prevention ofBAP inside the decay heat cooler, etc.). The influence of debris on BAPC and the evaluation completed by this program is discussed in Section 9.1.2 and Section 9.2.2 for the HLB and CLB scenarios, respectively. 3.4 DESCRIPTION OF IN-VESSEL DEBRIS CONCERNS Once the RWST has drained and the operators switch the ECCS suction source to the containment sump, debris laden coolant may begin to enter the RCS via the ECCS. The concentration of debris entering the RCS is a function of time and is dependent upon the sump condition, strainer filtering efficiency, and the ECCS configuration. For any break location, some portion of debris penetrating the sump strainer, traversing the ECCS, and reaching the RCS will enter the RV and some portion will go elsewhere. For the fraction of debris that enters the RV, the path it takes is dependent upon the debris properties, specific vessel geometry, flow condition, break location, etc. During cold leg recirculation, flow transports debris through the downcomer, into the lower head where it encounters some form oflower internal configuration consisting of various plates and vertical columns. Some fraction of debris may *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 6 I 8 of782 3-18 collect or settle on these components, or it may remain suspended in the flow. Debris that continues with the flow, travels through the core support region and enters the core where it could accumulate, remain suspended in the flow, or exit the RCS through the break. Most likely, in-vessel debris transport results from some combination of the above and is distributed throughout the RV. For hot leg breaks, some fraction of debris may flow out of the break since it is at the RV exit. For cold leg breaks, some of the debris will spill out of the break with the excess ECCS not needed to replace core boil-off. The remaining debris, which is a significantly smaller portion of the debris,~ enters the RV WiUand can make it to the core due to the break location and the circulation patterns that are developed. For ECCS recirculation to the hot legs or upper head, flow transports debris into the RV UP where it encounters some form of upper internal con.figuration consisting of various plates and vertical columns (e.g., control rod guide tube housings, instrument tube housings). Some fraction of debris may collect on these structures, or it may remain suspended in the flow. Debris that continues with the flow, travels through the upper core plate and enters the core where it could accumulate, remain suspended in the flow, or exit the RCS through the break. Most likely, the debris does some combination of the above and is distributed throughout the RV. For hot leg breaks, some fraction of debris may flow out of the break before it reaches the core since it is at the RV exit. For cold leg breaks, debris that is not captured in the core may settle in the RV LP or flow up the downcomer and out of the break. Concerns have been raised about the potential for debris ingested into the ECCS to affect LTCC when recirculating coolant from the containment sump. The FA bottom nozzles are designed with flow passages that provide coolant flow from the RV LP into the region of the fuel rods. During operation of the ECCS to recirculate coolant from the containment sump, debris in the recirculating fluid that passes through the sump strainer(s) may collect on the bottom surface of the FA bottom nozzle, causing resistance to flow through this path. The collection of sufficient debris on the FA bottom nozzle is postulated to impede flow into the FA and core. Other concerns have been raised with respect to the collection of debris and post-accident chemical products within the core itself. Specifically, the debris has been postulated to either form blockages or adhere to the cladding, thereby reducing the ability of the coolant to remove decay heat from the core. Similarly, chemical precipitates have been postulated to plate out on fuel cladding, again resulting in a reduction of the ability of the coolant to remove decay heat from the core. Finally, debris may concentrate within the heated core region such that the fluid properties in the core change, and subsequently, the heat removal ability of the water/debris mixture is affected. The potential for localized blockages within the core region, adherence of debris to the heated fuel rods, and plate-out of debris and chemical precipitates are evaluated in WCAP-16793-NP-A, Rev. 2 (Reference 3-1). These evaluations have been found acceptable to the NRC via the SE on Reference 3-1; therefore, no further work on these topics is presented in this report. This report instead focuses on the effects of the following concerns: (1) the effect of blockage by debris at the core inlet and (2) the accumulation and concentration of debris in the core region. 3.5 DEBRIS CONSTITUENTS The Nuclear Energy Institute (NEI) Guidance Report (GR), NEI 04-07 (Reference 3-2), provides the guidelines for determining the type, size, and quantity of debris that is generated following a LOCA. The GR (Reference 3-2) adopts a two-size distribution for material inside the ZOI of a postulated break: small fines and large pieces. Small fines are defined as any material that could transport through gratings, trash *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRJETARY CLASS 3 WCAP-17788-NP Mark-ups Page 619 of 782 4-5 The autoclave testing described in Volume 5 determined the time at which chemical precipitates forem. This time is defined as tchem* Once chemical precipitates form (i.e., tchem is exceeded) the resistance through the debris bed at the core inlet will be greatly increased, and as the fiber load is increased above 15 g/FA, flow through this path may be stopped completely (Reference 4-1). While it is true that flow through the bed will exist for fiber loads less than 15 g/FA, the effect of chemical precipitates on the head loss through these lesser debris beds has not been rigorously studied. It is therefore conservative to assume that no matter the existing fiber load at the core inlet, complete blockage will occur coincident with tchem. That said, if tchem < tblock> then the method described in this document cannot be used to address GSI-191 concerns related to in-vessel effects until a method is devised or plant changes are made to make tchem > tblock* The 1H analyses were also used to determine the maximum resistance at the core inlet that would maintain the cladding temperature below 800°F prior to reaching complete core inlet blockage. This parameter is defined as Kmax* The FA testing with debris described in Volume 6 correlates the head loss at the core inlet due to debris to the actual quantity of debris. In this manner, debris accumulation at the core inlet can be compared to Kmax* The 1H analyses demonstrate that as long as the resistance due to debris is less than Kmax prior to reaching tblock, the cladding temperature remains below 800°F. At some point in the transient, sufficient debris may accumulate at the core inlet such that flow and debris are diverted to the AFPs. The 1H analyses described in Volume 4 provide the conditions at which this occurs and the flow splits between the core inlet and AFPs as well. These parameters are defined as Ksplit and msplit, respectively. Debris that travels through these paths may reach the heated core. Further, after hot leg switchover (HLSO) occurs, debris may reach the heated core from the hot legs. The amount of debris that can accumulate in the heated core without affecting LTCC is defined in Section 6.4. Since the timing of the event is plant dependent, the final debris limits must be established by specific analyses, which are described in Section 6.5. An overview of the process for calculating the amount of debris that reaches the RCS following a HLB is provided in Figure 4-2. The plant-specific inputs are used to calculate Mi:; HLB which is the mass of fiber entering the RV for the HLB scenario. The parameter Mi:; HLB is then compared to the acceptance criteria as described in Section 6.5 to determine if the RV fiber load is acceptable. To help in understanding the process for defining where debris accumulates for a HLB, it is useful to identify various, key events. Specifically, the following events are significant: time of sump recirculation, activation of AFP, formation of chemical precipitates, and implementation of measures to prevent BAP. These events are expanded upon in the following subsections. As part of the program, a substantial investigation was performed to further understand these various events and the phenomena associated with them. The following subsections also provide an overview of how these times are defined as part of the overall solution for improving the debris limits. Finally, some example timelines are presented to illustrate how the timing affects the location of debris deposited within the RV. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 620 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-2 which chemical precipitates can be tolerated on a completely formed fiber and particulate debris bed at the core inlet, which is assumed to lead to complete core inlet blockage. 1bis value is compared to results from chemical effects testing contained in Volume S. 2. The maximum resistance at the core inlet that can occur prior to reaching tblock and meet the acceptance criteria defined in Section 3. 7. 1bis parameter is defined as Kmax and represents the resistance of a fiber and particulate only bed that can be tolerated from the time of SSO to tbLock, the earliest allowable time of complete core inlet blockage. 1bis value is compared to the results from subscale head loss testing contained in Volume 6 to establish an upper bound on the amount of particulate and fibrous debris that can be tolerated at the core inlet. 3. The resistance at the core inlet that begins to divert flow into the AFP. This parameter is defined as Ksplit afta is a fltftelieft efBCCS flew Fale. The subscale head loss testing has defined a correlation between the amount of fiber and an equivalent form-loss coefficient as discussed in Volume 6. Ksplit can then be used to define how much fiber accumulates at the core inlet before flow is diverted to the AFP. 4. The flow split between the core inlet and the AFP after Ksplit* This parameter is defined as msplit* Combined with Ksplit and the subscale head loss test results contained in Volume 6, msplit will be used to track where the debris accumulates after flow is diverted to the AFP. The values that were determined for each plant category are discussed separately below. A summary of the results for Kmax and tblock is provided on Table 6-1. These values and curves are used in Section 6.4 to track the fiber accumulation in the RV and to check to ensure acceptable results. Given that these analyses are conservative representations of a number of plants, margin may be available to individual plants by performing plant-specific analyses to calculate the parameters above using the same methods described in Volume 4. 6.1.1 Westinghouse Upflow Plant Category 1. The minimum time that complete core inlet blockage can be tolerated (tblock) was found to be 143 minutes (2.38 hours). 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (Kmax) was found to be Sxl05* 3. The resistance at the core inlet that begins to divert flow into the AFP (Ksptit) was found for a range ofECCS flow rates. These results are shown in Figures 6-1 and 6-2. 4. The flow split between the core inlet and the AFP after Ksplit (msp!it) was found for a range of ECCS flow rates. A curve that bounds the results was also developed. These results are shown in Figure 6~3. 6.1.2 Westinghouse Downflow Plant Category 1. The minimum time that complete core inlet blockage can be tolerated (tblock) was found to be 260 minutes (4.33 hours). *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 621 of 782 I WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-3 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (Km.ax) was found to be 64.75xlo'. 3. The resistance at the core inlet that begins to divert flow into the AFP (Ksptid was found for a range ofECCS flow rates. These results are shown in Figure 6-M. 4. The flow split between the core inlet and the AFP after Ksplit (msplit) was found for a range of ECCS flow rates. A curve that bounds the results was also developed. These results are shown in Figure 6-45. 6.1.3 Combustion Engineering Plant Category 1. The minimum time that complete core inlet blockage can be tolerated (tblock) was found to be ~333 minutes (4.+75.6 hours). 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (Km.ax) was found to be 6.5xl06. 3. The resistance at the core inlet that begins to divert flow into the AFP (Ksplit) was found for a range ofECCS flow rates. These results are shown in Figure 6-5. 4 . The flow split between the core inlet and the AFP after Ksplit (msplit) was found for a range of ECCS flow rates. A curve that bounds the results was also developed. These results are shown in Figures 6-*,7 and 6-8. 6.1.4 Babcock and Wilcox Plant Category 1. The minimum time that complete core inlet blockage can be tolerated (tblock) was found to be 20 minutes (0.33 hours). 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (Km.ax) was found to be lxl08* 3. The resistance at the core inlet that begins to divert flow into the AFP (Ksplit) was feline fer a range efECCS flew rates can be assumed to be exceeded at 20 minutes (or the time of sump switchover). These res\ilts are shewA in Figure e 7. 4. The flow split between the core inlet and the AFP after Ksplit (msplit) was felillEI fer a range ef E,CCS fle~* rales can be assumed to be 1.0 for all times after K,p1,, is exceeded. A 6\iP,'B !hat ee\inas the resHlts was alse Ele\<ele~eEI. +hese results are shewn iR :E<igure e 8. Table 6-1 Summary of Thermal-Hydraulic Output Parameters Plant Type K,...(-) t., .... (min) Westinghouse Upnow 5.0xlO' 143 Westinghouse Downnow e,44_75xl05 260 CE 6.5xl06 ~333 B&W 10xl08 20 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-P Mark-ups Page 622 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 60000 50000 40000 \ I W-UpflowCurve Fit: y = 2.0x106x*l.7S I \ 1 ' "' 30000 a. *:.t 20000 10000 \ i '~ ------0 0 5 10 15 20 25 30 35 40 45 ECCS Flow Rate (gpm/FA} Figure 6-1 K.,u, as a Function ofECCS Recirculation Flow Rate from Westinghouse UpOow Analysis -..!.,. ... j E 0.6 Curve Fit: y = 0.1351n(x) -1.2 0.5 0.4 0.3 0.2 0.1 0 O.E+OO l.E+05 2.E+05 3.E+05 K-K,plit -40gpm/FA --30gpm/FA ******* 18 gpm/FA 4.E+05 5.E+05 6-4 Figure 6-2 Fraction ofECCS Recirculation Flow through the BB following K.i,11 from Westinghouse UpOow Analysis for Recirculation Flow Rates Greater than 18 gpm/FA *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 623 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 0.6 Curve Fit: y = O.lSln(x)-1.44 0.5 0.4 -...!. .~ 0.3 E 0.2 0.1 0 O.E+OO l.E+OS -18gp,1/FA --12 gp,1/FA --Sgpm/FA 2.E+OS 3.E+OS 4.E+OS 5.E+OS K-Ksplit Figure 6-3 Fraction of ECCS Recirculation Flow through the BB following K,pu, from Westinghouse Upllow Analysis for Recirculation Flow Rates Less than or Equal to 18 gpm/FA 200000 I I I I 180000 160000 140000 ' ! W-Downflow Curve Fit: y = 3.4x106x*1*4 I ' \ 120000 ' -,,, 100000 'ii ':.t.~ 80000 60000 40000 \ \ .\. ' ...... ' ------20000 *~ 0 5 10 15 20 25 30 35 40 45 ECCS Flow Rate (gpm/FA) Figure 6~ Kspm as a Function ofECCS Recirculation Flow Rate from Westinghouse Downllow Analysis 6-5 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 624 of 782 -' -.. C. "' E 0.3 0.25 0.2 0.15 0.1 0.05 WESTING HOUSE NON-PROPRIETARY CLASS 3 Curve Fit: y = 0.0471n(x) -0.44 -40gpm/FA +---:11-~flC.----*-----l---~ ---30 gpm/FA ******* 18 gpm/FA -HIW--+----._----l---~ -12 gpm/FA --Bgpm/FA 0-+J---"'---------l-----4,--------1 0.E+OO 1.E+05 2.E+05 3.E+05 4.E+05 5.E+05 6.E+05 Figure 6-45 Fraction ofE CC S Recirculation Flow through the BB filllowing K,pt from 'Westinghouse Downtlow Analysis 5.Cl:+05 4.SE+OS 4.a:+05 a K/A2 "[ ] a,c A K/A2" --Volume 4 trendffne: y,. 6.416E6*ptw(x,-2.0U) 3.SE+OS 3.~+05 J 2.SE+05 2.~+05 1.SE+OS l.~+05 5.a:+04 o.a:+oo T T 0 5 10 15 20 25 ECCS Flow Rate (cpm/FA) Figure 6..$6 K.i;t as a Fwiction ofE CC S Redrculation Flow Rate from CE Analysis 6-6 30 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 625 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-7 0.9 .., i 0.8 -CD :::-.., fi 0.7 CD .s:; 0.6 .. £ 0.5 ! ii: 0.4 "' u --Volume 4 bound: y=0.07S ln(x)-0.4S ti 0.3 g 1 0.2 ... 0.1 --:-~~;r[bound: y=0.131]n~!/*53
  • K/A2=
  • KJA2= 0 0 1000000 2000000 3000000 4000000 5000000 6000000 K-Ksplit Figure 6-l,7 Fraction of ECCS Recirculation Flow throu&}l the BB following IC.-from CE Analysis for Barrel/Bame Resistance K/A2 = [ )-.. 0.9 .., lfi 0.8 ,-CD :::-.., 0.7
  • fi CD t 0.6 * £ o.s ! ii: 0.4 "' u ti 0.3 g 0.2 ... 0.1 0 0 1000000 2000000 --Volume 4 bound: y=0.0751n(x)-0.4S --Lower bound: y=0.131n(x)-L48
  • KJA2=[418. 248lgpm]a,c K/A2= 418, 1654gpm + K/A2= 418. 827gpm ----3000000 4000000 5000000 K
  • Ksplit 6000000 Figure 6-8 Fraction of ECCS Redrculation Flow through the BB following K<pit from CE Analysis for Baffle ResistanceK/A2= [ 11.,c F'il')Pefi 7 ~Hll F'll1u,a11I\ 11f EGGS Reeil'elllltti111t F'lll'I, Rate Er11M 8&1.J/ 1".<1111l318i.9 Ne&H Ci i Has&i.11& fllf aCC~ RIKH'&lilati11& J.la,v $llnugl\ iha Ranel.'liaffl.11 l11tlat '8llll'l¥iAg ftr8lB 8&W 1\ilai, !AJ *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 626 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-10 relate the subscale debris loading to that of a full-area FA. It is also possible to relate the subscale flow condition to that of the full-area FA using the same flow area ratio. It is noted that the debris loads presented in this section, in terms of g/FA, were scaled assuming a FA pitch of [ 8.466 in2. ] If the FA pitch is different, than the debris load needs to be scaled to account for this difference. See Section 6.5.5, Step 8 of the method for verifying hot leg break debris limits. Subscale testing determined that a low-flow condition was limiting because fiber penetration through the lower end fittings tested was minimized Minimizing the quantity of fiber penetration resulted in a single debris bed on the upstream edge of the lower end fitting. Experimental results confirmed that, for the debris loadings tested, a single debris bed formed at the lower end fitting resulted in a higher overall pressure drop compared to tests performed at higher flow rates that created multiple beds within the test section. For this reason, the low flow tests are used to conservatively define the final core inlet debris limits. Subscale testing also determined that capture geometry has a strong influence on the pressure drop across a debris bed. As a result, the subscale data sets used to define the final core inlet debris limits are different for each fuel vendor since their respective core inlet geometries are significantly different. Figure 6-9 shows the debris bed pressure drop as a function of fiber load (i.e., fiber mass), scaled to a area FA from the final limits data sets for Westinghouse and AREVA fuel. This is Figure 6-1 in Volume 6 . Figure 6-9 Limiting Conditions from Subscale Head Loss Testing Scaled to a Full-Area Fuel Assembly a,c *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 627 of782 WESTING-HOUSE NON-PROPRIETARY CLASS 3 6-12 Next, since the flow area of the subscale column is different from the flow area at which the resistance due lo dehris accumulation was simulah::d in the T/H analyses, an equivalt:nl form-loss coefficient needs to be calculated by taking the ratio of the flow areas squared: Equation 6-3 where: An1 = flow area used in the TH analysis to simulate resistance due to a debris bed The equivalent fonn-loss coefficient calculated using Equation 6-3 can be compared directly to the TH results. 6.3.2 Westinghouse Fuel Using Equations 6-1, 6-2, and 6-3, an equivalent form-loss coefficient can be calculated for each plant category considered in the TH analyses for Westinghouse fuel. First, Equation 6-2 is used to calculate the average supcdicial velocity through the debris bed. The Westinghouse final dataset used the final-Low flow reduction curve shown in figure 3-8, Volume 6. From Section 3.4, Volume 6, the subscale column flow area is 16 in2. From Table 3-7, Volume 6, the Westinghouse tested bottom nouJe flow area is [ ]'-< With the average superficial velocity calculated, the pressure drop data from Figure 6-9, along with the liquid density, is used to calculate the dimensionless form loss coefficient. Ki.est* Figure 6-10 shows Kiest. plotted as a function of cumulative fiber load for Westinghou~e fuel. Next, an equivalent form-loss coefficient is calculated for each plant category using Equation 6-3. Since the TH analyses for Westinghouse upflow and downflow BB plants used the same flow area, only three equivalent form-loss calculations are required; Westinghouse NSSS, CE NSSS, and D&W NSSS. from Section 6, Volume 4, the flow areas used in the 1H analyses for the three ).J'SSS designs are; [ ]'*' respectively. Figure 6-11 shows the equivalent dimensionless f01m-Joss coefficients, K,.q, for each NSSS design that is applicable to plants with Westinghouse fuel. .-\Isa shown in the figure are linear curve fits derived to fit the equivalent fonn loss-coefficient data. These curve fits are described in detail below and are used in the method for verifying the hot leg break in-vessel fiber limits, as described in Section 6.5, to calculate resistance at the core inlet. This is necessary to determine when the AFP activates and to detemune the fraction of debris that travels through the AFP once it activates . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-P Mark-ups Page 628 of 782 I WESTJNGHOUSE NON-PROPRIETARY CLASS 3 6-15 Table 6-3 Acceptable Core Inlet Fiber Loads Prior to Reaching tblod< for Various NSSS designs with Westinghouse Fuel Plant Category K... .. Acceptable Core Inlet Fiber Load (g/FA) Westinghouse Upflow Barrel/Baffle Sxlif Westinghouse Downtlow Barrel/Baffle e4.75xl05 CE 6.5xl06 B&W lxl<f Note: 1 [ ]"' is the maximum debris load tested. Kmu is greater than the resistance due to this debris load. 6.3.3 AREVA Fuel The same approach is taken for determining equivalent form-loss coefficients for AREVA fuel. The AREVA final dataset also used the Final-Low flow reduction curve shown in Figure 3-8, Volume 6. From Section 3.4, Volume 6, the subscale column flow area is 16 in2. From [ J"c the AREVA tested bottom nozzle flow area is ( ]'*' With the average superficial velocity calculated, the pressure drop data from Figure 6-9, along with the liquid density, is used to calculate the dimensionless form loss coefficient, Ktest* Figure 6-12 shows Ktest plotted as a function of cumulative fiber load for AREVA fuel. a,c Figure 6-12 Subscale Dimensionless Form-Loss Coefficient for AREVA Fuel r -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 629 of 782 WESTINGHOUSE NON-PROPRJETARY CLASS 3 6-16 J\ext, an equivalent form-loss coefficient is calculated for each plant category using Equation 6-3. Since the TH analyses for Westinghouse upflow and downflow BBs used lhe same flow area, only three equivalent form-loss calculations are required; \'v*estinghouse !':SSS, CE NSSS, and B& W NSSS. From Seclion 6. Volume 4. the flow areas used in the TH analyses for the three NSSS designs are; f ]"' respectively. Figure 6-13 shows lhe equivalent dimensionless follll-loss coefficienls, Keq, for each NSSS design thal is applicabh:: lo plants with AREVA fud. Also shown in the figure art: lim:ar cw*ve fits <le1ive<l lo fit lhe equivalent form loss-coefficient data. TI1ese eur\'e fits arc described in detail below and arc used in the method for verifying the hot leg break in-vessel fiber limits. as described in Section 6.5, to track the resislanct: al ll1e -:ore inlet. This is ne-:essary lo 1.lt:lt:rmint: when lht: AFP activates and lo <lt:lennim: the fraction of debris that travels through the AFP once it activates. a,c Figure 6-13 Subscale Equivalent Dimensionless Form-Loss Coefficients for Various NSSS Designs with AREVA Fuel The equivalent form-loss coctticicnt curve tit~ arc broken into three discrete regions that arc related to the physical particulate capture mechanisms presenl in a fibrous debris bed observed in the subseale testing. For the AREVA core inlel fuel geometry, al fiber loads less lhan [ ]'*< the fibt:r bed formt:cl al the core inlet is not an efficient particulate tilter. Since only a small fraction of the total injected particulate load captures in the fiber bed, the pressure drop. and thus, the dimensionless resistance remain relatively low. As the fiber load increases beyond [ ]'"' the filtration efficiency improves because of the addilional fiber and particulate, and the resistance rate increases. As the fiber load *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment2 toLTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 630 of782 I WESTINGHOUSE NON-PROPRJETARY CLASS 3 6-17 continues to increase beyond [ ]"c the debris bed is capturing particulates at nearly 100 percent efficiency and the rate of resistance increase is at its highest. Table 6-4 provides the slope and y-intercept used in Equation 6-4 for the three regimes applicable to AREVA fuel for each of the three NSSS designs. Table 6-4 Equivalent Dimensionless Form-Loss Coefficient Linear Relations for Various NSSS designs with AREY A Fuel slope (m) y-intercept (b) NSSSDesign Westinghouse CE B&W With the equivalent form-loss from the subscale data defined, it can now be compared directly to the TH analysis results to detennine the limiting fiber load for debris bed formation at the core inlet. This is done by using the linear relation from regime 2 for the Westinghouse categories and regime 3 for the CE and B& W plant categories, rearranging to solve for the mass of fiber and setting Keq equal to Kmax* Regime 2 is used to detennine the acceptable fiber load for the Westinghouse plant categories in this case because Kmax for the Westinghouse plant categories falls within regime 2. Table 6-5 provides the results of this calculation for the four plant categories considered in the TH analysis. The Westinghouse upflow and downflow BB categories use the same relation for equivalent form-loss. Since Kmax from the B&W plant category results in an equivalent resistance that is greater than the maximum debris load tested, the maximum debris load is chosen as the acceptable fiber load for this plant category. It is noted that these are the acceptable core inlet fiber loads prior to reaching tblock* For times after tblock, the core inlet fiber load can exceed the values shown in Table 6-5 since complete core inlet blockage can be tolerated at times after tblock* This is described further in Section 6.5. Table 6-5 Acceptable Core Inlet Fiber Loads Prior to Reaching**'°"' for Various NSSS designs with AREVA Fuel Plant Category K.. .. Acceptable Core Inlet Fiber Load (g/FA) Westinghouse Upflow Barrel/Baffle 5xl<Y Westinghouse Downflow Barrel/Baille e4.75x105 CE 6.5xl06 B&W Jx)(f Note: 1 [ ]"-' is the maximum debris load tested. Kmu is greater than the resistance due to this debris load. a,c r *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 631 of 782 6-19 Testing in the subscale loop demonstrated that debris entering the AFP will not block the flow paths in that region (Volume 6). The testing demonstrated that some debris will accumulate in the AFP without blocking the flow passages. However, it is conservative to neglect this accumulation to maximize debris transport to the core. Therefore, any debris that reaches the AFP will be assumed to travel on to the core. 6.4.2 Post Hot Leg Switchover For plants that initiate HLSO, coolant will enter the RCS in one or more hot legs. Depending on the time in the event that HLSO is initiated, it is likely that the sump strainer has filtered out most or all of the debris. However, there may be some debris remaining in the sump that introduces debris later in the event. In any case, the coolant and debris will either exit the break or reach the top of the core. It is expected that some or all of the hot leg recirculation flow will exit the broken loop, taking debris with it back to containment, where it will be re-filtered before returning to the ECCS. However, it is conservative to neglect this break carryover of debris with respect to debris accumulation in the core. Therefore, any debris that enters the RV through the hot leg will be assumed to reach the core region. 6.4.3 Justification for In-Core Debris Limit In all scenarios, a number of pieces of information can be used to justify that [ r,c of fiber can be tolerated in the heated core (in addition to what can be tolerated at the core inlet). This section provides the details of this information for any plant type that initially starts cold leg ECCS recirculation (including times after HLSO). UPI plants are discussed in Section 7. 6.4.3.1 Debris Accumulation Shortly after the time of SSO, the core is boiling ,<igeFe~ly, and the average void fraction is gFeater thaftcan be as much as 50 percent or greater. Even after 6-12 hours, the decay heat is high enough to generate boiling in the core, and the void fraction is greater than 20 percent. Given that all or most of the debris reaches the core region within the first few hours, debris will be entering a highly voided core region. The boiling process, in and of itself, precludes significant debris accumulation. While the general flow patterns in the core are well established by the TH analyses (Section 6.1), the local flow patterns are quite complex due to the nature of the boiling process. Boiling at any given location in the core is quite erratic. The instabilities of the boiling process introduce energy to the fluid that varies with time and location. ln the event of debris beginning to accumulate at the leading edge of a spacer grid (similar to what is seen at the core inlet-see Figure 6-14), the perturbations of the local conditions due to this small debris buildup will lead to boiling that will dislodge the debris before a large, contiguous bed can be established that significantly interrupts the core flow patterns. Therefore, debris beds like those seen at the core inlet will not establish in the presence of boiling. Rather, local blockages around spacer grid dimples, springs and other areas with small clearances are expected that do not significantly impact decay heat removal or create conditions that could lead to premature BAP (see Figure 6-15). The discussion above is supported by testing sponsored by the PWROG as described in WCAP-17360 (Reference 6-3). This testing was performed to investigate the heat transfer behavior of buffered and *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 632 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-25 studied in the literature. Therefore, it can be concluded that the addition of debris in the core that remains in suspension will not degrade the ability of the core fluid mixture to remove core decay heat. The debris will displace water, which if great enough can have an effect on core cooling. If sufficient debris is present to effectively reduce the core mixture level below the top of the core, then core cooling may be compromised. The amount of liquid above the top of the core was conservatively determined to be greater than [ ]3'< The volume of debris at the limiting condition calculated above is Therefore, only if all of the debris is concentrated above the core can the amount ofliquid displaced be sufficient to reduce the core mixture level below the top of the core. For the particulate loads expected (i.e., Jess than half of that calculated above) the core will not uncover. 6.4.4 Summary and Conclusion The discussion in the preceding subsections provides the basis for a conservative in-core fiber limit of [ ]'*< This limit is in addition to the amount of fiber that can be tolerated at the core inlet. This amount of fiber (and associated particulate) will not compromise core cooling or established BAPC actions. This value is used in Section 6.5 to ensure acceptable results. 6.5 METHOD FOR VERIFYING HOT LEG BREAK IN-VESSEL DEBRIS LIMITS Using the information from the previous sections, a method for calculating plant-specific fiber limits for large HLBs for cold leg recirculation plants was developed. (While this Section 6 pertains mainly to cold side recirculation plants, the method presented here is flexible enough to also analyze UPI plants. Guidance on how to do this is provided as needed below.) The details of this method are described here in enough detail that plant engineers can determine a plant-specific fiber limit using the calculation method of their choosing. Demonstration cases using the described method are also provided for use by utilities as an additional way of validating their calculations. The sections below are intended to provide the information necessary for a utility engineer to implement the method and replicate the results. The following process can be explicitly followed for all plant categories. However, as discussed in Volume 4, Section 11.2.3, the application of this method and the results of the thermal-hydraulic analyses demonstrate that the operating B& W plants will have an in-vessel fiber limit that corresponds to the core fiber limit. Therefore, the calculations described need not be implemented for the operating B&W plants, and they can declare an in-vessel fiber limit of [ ]'*< The sump fiber load can then be determined using Equation 6-27 from Section 6.5.3 with M1 Rv(tend) = [ ]'*< and plant specific values for strainer efficiency and ECCS flow rates. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 633 of 782 7. WESTINGHOUSE NON-PROPRJETARY CLASS 3 6-36 where, Qc, = the volumetric flow rate in gpm approaching the core inlet QAFP = the volumetric flow rate in gpm approaching the AFP QcE = the volumetric flow rate in gpm approaching the core exit QEccs = the volumetric flow rate in gpm entering the RV after the time of SSO msplit = the fraction of total cold side flow diverted into the AFP ()CL= the fraction of total flow diverted into the cold leg ()HL = the fraction of total flow diverted into the hot leg Using the mass of fiber injected into the RV in Step 3 and the flow splits calculated in Step 6, calculate the fiber load at the core inlet, AFP, core exit, and total. Knowing the total mass of fiber injected into the system in a given time interval and the flow rates at each core location, the mass of fiber at each location can be calculated by assuming that the fluid and debris are well mixed . where, Qc, Mr,c1(t) = -Q--X Mf,inj ECCS QAFP Mf.AFP(t) = -Q--x Mf,inj ECCS QcE Mf,CE(t) = -Q--X Mf,inj ECCS Mr.nv(t) = Mf,Cl + Mr .AFP + Mf,CE Equation 6-32 Equation 6-33 Equation 6-34 Equation 6-35 Mf,inj = the mass of fiber injected into the system over the current time step, as calculated in Step 4. 8. Calculate the core inlet K factor using the mass of fiber at the core inlet calculated in Step 7. This calculation is made by first checking to see if complete core inlet blockage has occurred. If not, then the K factor is calculated based on the results of the subscale testing. Note that the debris loads used in the subscale testing were scaled to units of g/FA assuming a FA pitch of [ 8.466 in. ] If the FAs in the plant being analyzed have a different pitch, then the K factor must be calculated using an adjusted core inlet fiber mass to account for this difference. While the actual fiber mass calculated in Step 7 does not change, it must be adjusted as follows to calculate the proper core inlet K factor . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 634 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-37 The first step is to determine the appropriate scaling factor, Rm: Rm=:, (PFA)2 = [ la,c Equation 6-36 Where, R the subscale-to-full-area FA scaling ratio applied in WCAP-17788, Volume 6. A, = the subscale test column flow area. PFA = the pitch of the FA being analyzed. Using the scaling factor, Rm, it is possible to relate the core inlet debris load calculated in Step 7 to an equivalent core inlet debris load based on a FA pitch of [ ]"c Where, M -_jE._ M [ B] ef,cl -Rm FA Equation 6-37 Mef,CI = the equivalent core inlet debris load (g/FA) based on a FA pitch of [ Mr.ci = the core inlet debris load (g/FA) calculated in Step 7. Rm = the scaling factor determined from Equation 6-36. Note that if the FA pitch is [ ]'*c then Mef,CI = Mr.ci* TI1e equivalent core inlet debris load calculated by Equation 6-37 is then used to determine the core inlet K factor using Equation 6-4 in Section 6.3. a. Check for an infinite core inlet K factor (i.e., complete blockage of the core inlet). If the core inlet is completely blocked then all fluid and debris is transported to the AFP. There are two potential conditions which can force the core inlet resistance to infinity: chemical effects in the presence of a sufficient debris bed or exceeding the maximum fiber load tested. Once chemical precipitates form (i.e., tchem is exceeded) the resistance through the debris bed will be greatly increased, and as the fiber load is increased above 15 g/F A, flow through this path will be stopped completely. While it is true that flow through the bed will exist for fiber loads less than 15 g/FA, the effect of chemical precipitates on the head loss through these lesser debris beds has not been rigorously studied. It is therefore conservative to assume that, so long as there exists a fiber load at the core inlet, complete blockage will occur coincident with tchem* This is accomplished by setting the K factor to a value large enough (lxl020) to prevent all flow through the inlet, thus diverting all flow *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 635 of 782 9. 10. WESTINGHOUSE NON-PROPRJETARY CLASS 3 6-38 through the AFP. The subscale testing was performed up to a maximum fiber load. Due to a lack of data, once the fiber load at the core inlet exceeds the maximum tested value, it must be conservatively assumed that the core inlet becomes completely blocked. b. If the core inlet K factor is not infinite, then it can be calculated as a function of the existing core inlet fiber bed, governed by the fuel-specific correlation developed during subscale testing, which is based on fuel vendor and plant design. Details of these correlations are presented in Section 6.3. Compare the core inlet K calculated in Step 8 to Ksplit* IfK is less than or equal to Ksplit, then msplit is zero, and flow continues to pass through the core inlet only, with all fiber depositing at the inlet. If the core inlet K factor is greater than Ksplit, then calculate the flow split between the core inlet and AFP. Flow is diverted through the AFP according the value of msplit, with a fraction of fiber captured at the core inlet and the remaining fiber passing through the AFP into the core region. This fiber split is directly proportional to msplit, as the fluid and debris are assumed to be well mixed. For core inlet K-factors of 1x1D2° (i.e., complete core inlet blockage) msplit is set to 1.0. The Ksplit and msplit correlations are plant-type dependent and described in Section 6.1 and shown in Figure 6-1 through Figure 6-8. If two curve fits are provided, the fHMminimum fit should be used to 1mnimi~smaximize the debris buildup at the core inlet. The calculated msplit values should be given an upper bound of 1.0 . Now that the core inlet fiber load is known, the following stopping criteria can be tested: a. If the core inlet K factor is greater than Kmax before the time of tblock, then the calculation does not meet the acceptance criteria defined by the 1H analyses (Section 6.1). In this case, steps should be taken to reduce the sump fiberload or minimize the delivery of debris to the RCS (e.g., credit CSS or decrease the strainer bypass fraction). b. If the in-core (Mr .AFP + Mr.c,J fiber load is greater than the maximum allowable in-core fiber limit (Section 6.4 fornon-UPI plants and Section 8 for UPI plants), then adequate core cooling cannot be guaranteed. c. If the total RV fiber load (core inlet plus in-core) exceeds the in-core limit of [ ]'*c then the calculation should be terminated. This is done because fiber capture at the core inlet cannot be guaranteed. This criterion ensures that in the event that debris penetrates the core inlet, the in-core limit is not exceeded due to that penetration. d. If using this method to analyze a CLB for a UPI plant, an additional stopping criterion is needed at the core inlet. As discussed in Section 8, after simultaneous recirculation is re-established, the core inlet fiber load, M f.c,, cannot exceed [ r,c If the case fails on any criterion, steps should be taken to reduce the sump fiber load or minimize the delivery of debris to the RCS (e.g., credit CSS or decrease the strainer bypass fraction) . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NO -PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 636 of782 6-39 11. Iterate in time until the sump fiber load is depleted. 111.is is determined as the time at which the sump fiber load is less than 1 percent of the initial sump fiber load. At this point, it is reasonable to terminate the calculation: M f,sump(t) :5 0.01, terminate calculation Mf.sump(O) Equation 6-3{;8 If the calculation is terminated based upon this criteria, then all of the acceptance criteria have been met and the plant conditions analyzed have been shown not to challenge core cooling for a HLB scenario. 6.5.6 Example Calculations 111.is section provides example calculations that can be used to verify an implementation of this methodology. Two cases are discussed below; liewe*,*eF, eilElil:ieHel eases wit:lithe time dependent results are available to the utilities upon request. Note that the inputs for these cases are not intended to reflect realistic plant conditions; rather, they are intended to test implementation of the methodology. Also note, the time values for inputs are relative to the initiation of the LOCA event, whereas time values in the methodology are relative to the time of sump recirculation. The first case has a time of chemical precipitation, tchem, coincident with the time of SSO. Because chemical effects will cause complete core inlet blockage at the initiation of the transient, all fiber injected into the RV will accumulate in the core. Given an initial sump fiber load, the final fiber load in the RV can be calculated. The inputs for Case 1 are provided in the Table 6-7. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 637 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 debris will not change the current licensing basis calculations for defining the action time to preclude BAP7 and 9-4 Ottee the aetieflS afe tel,ett te HHtigate the e1,1ilEIHjl efeefie aeie itt the RV MEI eere, eeefis will ttet iHl.jjeEle the f11,1shittg flew Heeeee te eil1,1te the eefis eeie e1,1i:IEIHjl iH the sere regieH. Fer jllattls that jlerfeffft a HLSO, the realigRfflefll ef the s~*steffl will Ele lwe thiHgs. Fiffll, it will reffle*,*e the ffleti*,*e ferse heleittg th@ Ei@eFis at th@ eef8 ifllet ay ste)313iHg er r@Ei11eiHg th@ eelEi siEi@ r@eire1,1latiett flew (al lust l@m13erarily). SeseREi, the flew rate frnm tlu, het legs wi:11 travel EiewR the healeEi sere te the ittlet aREi Eiisleege the EieaFis aee as it tra1,els ta the sale leg. Fer jllrutts that HSe aa alternate ff!eaRs efBAPC (e.g., B&W jllattts that SjleR the Eiesay heat Eirejl liM ta iaerease the flew frem the sale side tlH'e1,1gh the sere), the )ask ef a seHlig1101,1s Eieefis aee at Ike sere ifllel meaHs that the aeeilieHal jlr@sstlfe Eirejl al the sere inlet Ei1,1e le EieeFis is aegligiely higher lhaa if the EieaFis were Hat )3resefll. Therefere, the current actions to prescribe BAPC measures for a CLB will continue to keep the boron concentrations in the core region remain below the solubility limit even in the presence of debris.

9.3 REFERENCES

1. OG-13-205, "PWR Owners Group, NRC Technical Concerns Regarding Boric Acid Precipitation in the Presence of In-vessel Fibrous Debris and the Consequential Effects on Long-Term Core Cooling (PWROG PA-SEE-1090 and PA-SEE-1072)," ADAMS Accession Number ML14161A043, May 2013 . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 638 of 782 PA PCT PIRT PWR PWROG RBS RCP RCS RHR RV RWST RWT SBLOCA SEE SG TH UHSN UP UPI U.S. WCAP WESTINGHOUSE NON-PROPRIETARY CLASS 3 LIST OF ACRONYMS AND ABBREVIATIONS Project Authorization Peak Cladding Temperature Phenomena Identification and Ranking Table(s) Pressurized Water Reactor(s) Pressurized Water Reactor Owners Group Reactor Building Spray Reactor Coolant Purnp(s) Reactor Coolant System Residual Heat Removal Reactor Vessel Refueling Water Storage Tank Refueling Water Tank Small Break Loss-of-Coolant Accident Systems & Equipment Engineering Stearn Generator( s) Therrnal-Hydraulic(s) Upper Head Spray Nozzle(s) Upper Plenum Upper Plenum Injection United States Westinghouse Technical Report Number Preface (formerly Westinghouse Commercial Atomic Power) XVI *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 639 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 2-4 2. The maximum resistance at the core inlet that can occur prior to reaching complete core inlet blockage and meet the acceptance criteria defined in Section 2.5. This parameter is defined as Kmax and represents the resistance of a bed comprised of only fibrous and particulate debris that can be tolerated from the time of sump switchover to the time that chemical precipitates arrive at the core inlet. This value is compared to the results from subscale head loss testing contained in Volume 6 to establish an upper bound on the amount of fibrous debris that can be tolerated at the core inlet. 3. The resistance at the core inlet that begins to divert flow into the AFP. This parameter is defined as Ksp1it and is a function ofECCS flow rate. The subscale head loss testing defined a correlation between the amount of fiber and an equivalent form-loss coefficient, as discussed in Volume 1. Ksp1ii can then be used to define how much fiber accumulates at the core inlet before flow is diverted to the AFP. 4. The flow split between the core inlet and the AFP after Ksp1it* This parameter is defined as msplit* Combined with ~it and the subscale head loss test results, msplit will be used to track the fraction of debris that bypasses the core inlet through the AFPs. The use of these parameters in defining the final HLB debris limit is discussed in detail in Volume 1, Section 6. The analyses to determine K.p1i1 and msp1i1 for the B& W plant category are no longer required as described in Section 11. 2.5 ACCEPTANCE CRITERIA The analysis acceptance criteria are developed to ensure LTCC after a postulated large HLB LOCA event. The two aspects ofLTCC considered in this work that pertain to 10 CFR 50.46 (Reference 2-2) are: 1. Decay Heat Removal (DHR) -DHR requires that sufficient coolant be supplied to the core such that the core temperature is maintained at an acceptably low level. For previous GSI-191 evaluations, the maximum allowable post-quench PCT is 800°F (Reference 2-3). This conservative limit will be retained. 2. Boric Acid Precipitation Control (BAPC) -BAPC requires that boron concentrations in the RV remain below the solubility limit. For the large HLB scenario with core inlet blockage, BAPC requires demonstration of adequate break quality to flush boron from the RV and demonstration of adequate mixing within the RV to ensure effectiveness of the flushing flow.

2.6 REFERENCES

2-1 GL 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors," ADAMS Accession Number l'vIL042360586, September 2004. 2-2 10 CFR Part SO §50.46, "Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Reactors," 72 Federal Register 49494, August 28, 2007. 2-3 WCAP-16793-NP-A, Rev. 2, "Evaluation ofLong-Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculation Fluid," July 2013 . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 640 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 4-3 4. A top-skewed power shape is assumed to be most limiting for core uncovery and cladding heatup. The uncovery process is governed by boil-off and subsequent dry out that begins at the top of the core and propagates downward. Using a top-skewed power shape will maximize cladding heatup and provide the most challenge for meeting the 800°F acceptance criterion. S. It is assumed that the guide thimble tubes in the FAs are blocked, and thus no bypass flow through the tubes will be credited. This assumption removes an additional potential path for fluid to bypass the core inlet and reach the core region after core inlet blockage. 6. The ECCS temperature during sump recirculation will be set at or near saturation temperature at containment pressure. Ice condenser plants will likely have some subcooling in the containment sump at the time of sump switchover, while other plants with residual heat removal (RHR) heat exchangers in operation could have subcooled ECCS entering the cold legs during the recirculation phase. Neglecting the presence of subcooling is conservative because it maximizes the steaming rate in the core and minimizes the cooldown rate of the RV and steam generators (SGs). 7. The code simulations assume that the secondary side is isolated and not depressurized, consistent with the short-term LOCA analysis approach. This creates a high secondary side temperature that helps to inhibit flooding the SG on the primary side such that SG spillover, if predicted, is limited in magnitude and delayed in time. 4.2 CRITICAL INPUTS The following critical inputs are considered in the analyses discussed herein. Additional inputs specific to each plant category may also be discussed in the model descriptions contained in Section 6. 1. Barrel/Baffle Flow Resistance -For all plant categories with an upflow BB configuration, ooth thea maximum aRd mimmum BB channel flow resistance that bounds all plants in the category at=e-is examined. Selecting a maximum resistance will require the largest driving head to force flow through the BB channel and into the core region. A maximum resistance also maximizes debris collection at the core inlet. If it can be shown that a highly-resistive BB channel provides adequate bypass flow to achieve LTCC, then lower resistance BB channels will do the same due to the consequent higher flow through the BB channel. 2. Upper Head Spray Nozzle Resistance -For the Westinghouse downflow plant category, th&-a maximum UHSN flow resistance will be ~applied similar to the BB flow resistance. Ul-IS}ls will be modeled using a maximum flew resistaaee fer eases that are used to aetermiae aaa a minimum flew resistaaee will be applied fer eases that are used to aetenmae ~~-The maximum flow resistance cases will effectively model a T-hot upper head plant, whtie the mimmum flew resistaaee eases will model a T eeld liflper head plaat. which bounds T-cold upper head plants. Using a maximum UHSN resistance will maximize debris collection at the core inlet. The UHSN resistance is also considered for the Westinghouse upflow plant category. Since the primary AFP considered for this plant category is the BB channel, the UHSN resistance is set to a *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 641 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 4-4 large value such that any bypass flow through the UHSNs is minimized. This approach is consetvative, since limiting bypass flow through the UHSNs requires more bypass flow through the BB channel for DHR. 3. Core Power -The 10 CFR 50 Appendix K Decay Heat Model (1.2 times the 1971 ANS Infinite Standard [Reference 4-3]) will be used (eF ae11aeleel)for the Westinghouse and B&W plant categories. Appendix K decay heat will generate the highest steaming rate which maximizes the flow requirements for DHR. For the CE plant category, 1.1 times the 1979 ANS Infinite Standard (Reference 4-4) will be used. Reference 4-4 notes that the maximum positive uncertainty for periods after shutdown ofup to 103 seconds is 20% and is reduced to 10% after for time period greater than 103 seconds, but less than 107 seconds. TI1e major events ofinterest in this analysis occur at 1200 seconds for SSO and 20000 seconds for the core inlet blockage. A 1.1 multiplier (10% positive uncertainty) adds additional conservatism to the evaluation, representing the maximum value of uncertainty for the period where relevant phenomena of interest occur, while still being a reasonably high conservative value for the first 1000 seconds, when it accounts for at least half of the maximum positive uncertainty. As discussed in the major assumptions, a skewed power shape is applied. 4. Switchover Time to Sump Recirculation -A minimum switchover time will be used such that the decay heat will be maximized at the time core inlet blockage occurs. This input maximizes the core flow requirement to remove decay heat. In order to achieve sump switchover at this time, full ECCS and RBS flow without single failures must be assumed with the smallest usable RWST liquid volume. The transient response for a DEG HLB case with full ECCS flow would likely result in core exit subcooling and a maximum RV liquid inventory at 20 minutes. The potential for core uncovering after a core inlet blockage from this maximized liquid inventory scenario is less likely. Assuming a single train ofECCS (consistent with the ECCS flow rate assumption discussed below) would result in a much later sump switchover time, which has lower core decay heat removal flow requirements. Disconnecting the sump switchover time from the ECCS flow rate assumption minimizes the RV liquid volume and increases the likelihood of core uncovering. Therefore, analyzing a single train ofECCS with a sump switchover time of20 minutes is conseivative for the GSI-191 thermal-hydraulic analyses. 5. Break Flow -To maximize break flow during the recirculation phase, the pressure boundary condition at the break will be set to 14.7 psia, er S0ffl@ elR@r lew 13r@ss11nj11stili@el ~, a eoRlainmeRI aaal)'sis, during the recirculation phase of the event. 6. Cold leg ECCS Flow -For each category of plants, a range ofECCS flows is seleeteel lt!at examined to determine a representatives value for all plants in the category. For tblock and Kmax analyses, the flow is minimized such that the RV liquid volume is minimized when the blockage is imposed increasing the potential for core uncovering. Further, the low flow rate (sometimes considering the potential for operator throttling of the ECCS during the sump recirculation phase) minimizes the downcomer fill rate needed to develop the driving head to overcome the AFP resistance, further increasing the potential for core uncovering. 1n all cases, the ECCS fluid temperature is set at or near the saturation temperature at containment pressure. Doing so will maximize the steaming rate in the core as well as the cooldown rate of the RV and SGs . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 642 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 4-5 7. Core Inlet Blockage -All core channels will be blocked uniformly at the same time and blockage will begin as early as possible after the sump switchover time. The added resistance will be ramped up such that it takes a finite period of time to reach "complete" core inlet blockage. The ramp rates will be varied as part of the analysis.

4.3 REFERENCES

4-1 10 CFR Part 50, Appendix B to Part 50, "Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," 72 Federal Register 49505, August 28, 2007. 4-2 WCAP-16793-NP-A, Rev. 2, "Evaluation ofLong-Tenn Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculation F1uid," July 2013. 4-3 10 CFR Part 50, Appendix K to Part 50, "ECCS Evaluation Models," 65 Federal Register 34921, June 1, 2000. 4-4 ANS/ANSI-5.1-1979, American National Standard for Decay Heat Power in Light Water Reactors, 1979. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 643 of 782 WESTINGHOUSE NON-PROPRJETARY CLASS 3 5-3 (LBLOCA) in PWRs as described in [ ]"'c. The code is also suitable for analyzing PWR small break LOCA (SBLOCA) and non-LOCA transients. Most recently, AREVA has expanded the capability ofS-RELAPS for analyzing events and phenomena in boiling water reactors (BWRs). RELAPS is a light water reactor (LWR) transient analysis code developed at the Idaho National Engineering Laboratory (INEL) for the NRC. The series ofRELAPS codes released are RELAPS/MOD1, RELAPS/MOD2, and RELAPS/MOD3. S-RELAPS incorporates features of RELAPS/MOD2 and RELAPS/MOD3, and AREVA's improvements. In general, the improvements and modifications included are those required to provide congruency with literature correlations and those required to obtain adequate simulation of key LOCA and non-LOCA experiments. RELAPS is a general-purpose code that, in addition to calculating the behavior of a RCS during a transient, can be used for simulation of a wide variety of hydraulic and thermal transients in both nuclear and non-nuclear systems involving mixtures of steam, water, non-condensable gas, and solute. The RELAPS code is built on a non-homogeneous and non-equilibrium model for the two-phase system. The original objective of the RELAPS development effort was to produce a code that includes important first order effects necessary for accurate prediction of system transients but that is sufficiently simple and cost effective so that parametric and sensitivity studies are feasible. The base RELAPS code includes hydrodynamic models, heat transfer and heat conduction models, a fuel model, a point reactor kinetics model, a control system and a trip system. It uses two-fluid, equilibrium, non-homogeneous field equations for transient simulation of the two-phase hydrodynamic behavior. The hydrodynamic models also include many generic component models such as pumps, valves, separators, jet pumps, turbines and accumulators, and some special-process models such as form-loss of abrupt area changes, critical flow and counter-current flow limit. The system mathematical models are solved by efficient numerical schemes to permit cost-effective computations. The code also includes many user conveniences such as extensive input checking capability to help users detect input errors and inconsistencies, free-format input, restart, renodalization, minor and major edits, and plot variables for interface with plotting tools. The S-RELAPS code evolved from AREVA ANF-RELAP code, a modified RELAPS/MOD2 version, used at AREVA for performing PWR plant licensing analyses including SBLOCA analysis, steam line break analysis, and PWR non-LOCA Chapter 1 S event analyses. The code structure for S-RELAPS was modified to be essentially the same as that for RELAPS/MOD3, with similar code-portability features. Since then, numerous improvements, new models and new capabilities have been implemented and incorporated into S-RELAPS to support various methodologies. 5.3 BABCOCK AND WILCOX PLANT CATEGORY The RELAP5/MOD2-B&W computer code [ ]"'c was used to analyze the B&W plant category in accordance with the EM described in BAW-10192, Rev. 0 (Reference 5-8). RELAP5/MOD2 is an advanced system analysis computer code designed to analyze a variety of TH transients in LWR systems. It was developed by INEL under the NRC Advanced Code Program. RELAP5/MOD2 is advanced over its predecessors by its six-equation, full non-equilibrium, two-fluid model for the liquid flow field and partially implicit numerical integration scheme for more rapid execution. As a system code, it provides simulation capabilities for the reactor primary coolant system, secondary system, *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 644 of782 WESTINGHOUSE NO -PROPRIETARY CLASS 3 5-5 boiling, transition boiling, and film heat transfer from the wall to water and reverse transfer from water to wall, is provided. RELAP5/MOD2 has been adopted and modified by AREVA for licensing and best estimate (BE) analyses of PWR transients in both the LOCA and non-LOCA categories. RELAPS/MOD2-B&W retains virtually all of the features of the original RELAP5/MOD2. Certain modifications have been made to enhance the predictive capabilities of the constitutive models and/or to improve code execution. More significant, however, are the AREVA additions to RELAPS/MOD2 models and features to meet the 10 CFR SO Appendix K requirements for ECCS EMs. The Appendix K modifications are concentrated in the following areas: (1) critical flow and break discharge, (2) fuel pin heat transfer correlations and switching, and (3) fuel clad swelling and rupture for both zircaloy and zirconium-based alloy cladding types. ,A,,NAL¥SIS OF WESTINGHOUSE l)OWNFLOW PLANT CATEGORY USING S RELAPS M

5.4 REFERENCES

5-1 NUREG/CR-3046, "COBRA!fRAC -A Thermal-Hydraulics Code for Transient Analysis of Nuclear Reactor Vessels and Primary Coolant Systems," 1983. 5-2 Thurgood, M. J., et al., "COBRA-TF Development," 81h Water Reactor Safety Information Meeting, 1980. 5-3 NUREG/CR-2054, "TRAC-PD2, An Advanced Best-Estimate Computer Program for Pressurized Water Reactor Loss-of-Coolant Accident Analysis," 1981. 5-4 WCAP-14747 (Non-Proprietary), "Code Qualification Document for Best-Estimate LOCA Analysis," 1998. 5-5 WCAP-16009-NP-A, "Realistic Large Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainly Method (ASTRUM)," January 2005. 5-6 5-7 I 5-8 -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 645 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-2
  • Barrel/Ba:flle Flow Resistance In order to represent all Westinghouse upflow plants in operation in the U.S., a method was developed to calculate appropriate BB flow resistances for use in this analysis. The method and supporting calculations are contained in+ -:I..,. Appendix A, RAI-4.2 response, which confirms that the BB flow resistance& shown in Table 6-1 bound all Westinghouse upflow plants.
  • Break Pressure Boundary Condition The pressure boundary condition at the break was not changed for the short-term LOCA simulation. However, to extend the simulation beyond reflood, the pressure boundary was set to 14.7 psia to maximize break flow during the recirculation phase.
  • Core Inlet Blockage The dimensionless form-loss coefficient at the first core node was adjusted to simulate the build-up of debris during the recirculation phase of the transient. The flow area at the first core node is ( ] ,,c per FA which corresponds to the flow area through the [ ] *.<. The value of the form-loss coefficient was varied from case-to-case. Tables 8-1 and 8-2 list the form-loss coefficient values applied for the various simulations . The key inputs for this analysis are summarized in Table 6-1. These inputs are used for all simulations shown in Tables 8-1 and 8-2. Table 6-1 Summary of Key Inputs-Westinghouse Upflow Barrel/Baffle Plant Design Parameter Analysis Value Core Power including Uncertainty (MWt) 3658 Number of Loops 4 Number of Fuel Assemblies 193 Barrel/Baille Total K/A2 (ft"4) [ ]"' Upper Head Spray Nozzle Total KIA 2 (ft4) [ ] .. ' Total Peaking (FQ) 2.30 Radial Peaking (F 4.II) 1.80 Axial Peak Power Location Top Axial Skew -9 ft ECCS Recirculation Flow Rate (gpm/FA)1 40, 30, 18, 12, 8 Containment Pressure during Recirculation Phase (psia) 14.7 ECCS Temperature after Sump Switchover (0F) 212 Sump Switchover Time (min) 20 Note: I. Only the 40 and 18 gpm/F A flows are used for the fflB!I Fesis~eRee Kmax and tblod cases . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 646 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-3 6.2 WESTINGHOUSE DOWNFLOW PLANT MODEL The base plant model selected for the Westinghouse downflow analysis is a high-power, three-loop plant with a T-hot upper head configuration. The base plant model was developed for BE PCT and clad oxidation analysis. Since the base plant model was developed for BE analysis, many of the model inputs are set to nominal values. For this reason, some changes were made to bias the model toward an Appendix K analysis. Doing so has added conservatism to the model to account for uncertainties associated with the LTCC phase of the post-LOCA transient. The major changes to the base plant model are discussed in further detail below:

  • Break Location For this analysis, a DEG HLB is modeled. Since the base plant model simulated a DEG CLB, the location had to be moved. lbis was completed by moving break components from the cold side of the broken loop to the hot side. The loop containing the pressurizer remained intact. lbis change also required that an accumulator and ECCS model be input into the broken loop such that ECCS flow from all loops was considered.
  • Decay Heat Model The BE decay heat model was replaced with the I 971 ANS infinite+ 20% (Appendix K Standard).
  • Core Region lnterfacial Drag It is known that the version of WCOBRNTRAC utilized tends to over predict two-phase mixture level swell in the core under low pressure pool boiling conditions (Reference 6-1). To account for this, a multiplier on the core axial interfacial drag is applied consistent with the approach taken in Reference 6-1. The resulting reduced interfacial drag in the axial direction within the core region better predicts the void fraction and two-phase mixture level swell for low pressure boil-off conditions.
  • ECCS Model Since this analysis extends the simulation into the sump recirculation phase, additional trips and fills were added to the ECCS model to simulate switchover from RWST injection to sump recirculation.
  • Upper Head Spray Nozzle Flow Resistance In order to represent all Westinghouse downflow plants in operation in the U.S., a method was developed to calculate appropriate UHSN flow resistances for use in this analysis. The method and supporting calculations are contained inf -r" Appendix A, RAI-4.2 response, which confirms that the UHSN flow resistanc~ shown in Table 6-2 bound all Westinghouse downflow plants. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 647 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3
  • Break Pressure Boundary Condition The pressure boundary condition at the break was not changed for the short-term LOCA simulation. However, to extend the simulation beyond reflood, the pressure boundary was set to 14.7 psia to maximize break flow during the recirculation phase.
  • Core Inlet Blockage 6-4 The dimensionless form-loss coefficient at the first core node was adjusted to simulate the build-up of debris during the recirculation phase of the transient. The flow area at the first core node is [ ] ,,c per FA which corresponds to the flow area through the [ ]',c. The value of the form-loss coefficient was varied from case-to-case. Tables 9-1 and 9-2 list the form-loss coefficient values applied for the various simulations. The key inputs for this analysis are summarized Table 6-2. These inputs are used for all simulations shown in Table 9-1 and Table 9-2. Table 6-2 Summary of Key Inputs -Westinghouse Downflow Barrel/Baffle Plant Design Parameter Analysis Value Core Power including Uncertainty (MWt) 2951 Number of Loops 3 Number of Fuel Assemblies 157 Barrel/Baffie Total K/A2 (f\"4) [ l .,. Upper Head Spray Nozzle Total K/A2 (ff4) [ l .,. CKmm K,pJ;t, and m,pJ;, analyses) [ 1*** (tblockanalysis) Total Peaking (F 0) 2.30 Radial Peaking (F .rn) 1.80 Axial Peak Power Location Top Axial Skew -9 ft ECCS Recirculation Flow Rate (gpm/F A)' 40, 30, 18, 12, 8 Containment Pressure during Recirculation Phase (psia) 14.7 ECCS Temperature during Recirculation Phase (°F) 212 Sump Switchover Time (min) 20 Note: 1 Only the 40 and 12 gpm/F A flows are used for the Rl8H FesislafteeKmu and ti,10,k cases. 6.3 COMBUSTION ENGINEERING PLANT MODEL The base plant model selected for the CE analysis is a high-power CE plant design. The base plant model was developed for realistic PCT and clad oxidation analysis. Since the base plant model was developed for realistic analysis, many of the model inputs are set to nominal values. For this reason, some changes were made to bias the model toward an Appendix K analysis. Doing so has added conservatism to the model to account for uncertainties associated with the LTCC phase of the post-LOCA transient. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 648 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-5 The major changes to the base plant model are discussed in further detail below:

  • Break Location For this analysis, a DEG HLB is modeled. Since the base plant. model simulated a DEG CLB, the location had to be moved. This was completed by moving break components from the cold side of the broken loop to the hot side. This change also required that an accumulator and ECCS model be input into the broken loop such that ECCS flow from all loops was considered.
  • Decay Heat Model The realistic decay heat model was modified to represent the 1979 ANS model with infinite operation + 10%beaREi the 1971 ANS iflfimte + 2Qg-., (AfJfJ8REH); K StaREiaFEi) meEiel.
  • Downcomer Condensation Model The condensation heat transfer coefficient in the downcomer was set to a maximum value to ensure saturated conditions at the core inlet.
  • ECCS Model Since this analysis extends the simulation into the sump recirculation phase, additional trips and fills were added to the ECCS model to simulate switchover from RWT injection to sump recirculation.
  • Barrel/Baffle Flow Resistance In order to represent all CE plants in operation in the U.S., a method was developed to calculate appropriate BB flow resistances for use in this analysis. The method and supporting calculations are contained inf -f""-am!-f -f"" Appendix A, RAI-4.3 response, which confirms that the BB flow resistances shown in Table 6-3 bound all CE plants.
  • Break Boundary Condition The pressure boundary condition was set to 14.7 psia beyond 200 seconds after the transient initiationat the break was Rat ehaRgeEi fer the shert term LOCA simalatieR. Fer the TSGH"GHlatieR 13hase, the eeRtaiflfl'l@Rt 13ressare was dyRamieally ealealatsd; hewe'>'er, the e0Rditi0HS were biased te eRsure a law fJressure was eelealetee te ftl8llifflize areal! filew EluMg the t"eeirealetisR fJhese.
  • Core Inlet Blockage The dimensionless form-loss coefficient at the first core node was adjusted to simulate the build-up of debris during the recirculation phase of the transient. The flow area at the first core node is [ ) ,,c per FA which corresponds to the nominal [ ] *,<. The value of the form-loss coefficient was varied from case-to-case. Tables 10-1 and 10-2 Jist the form-loss coefficient values applied for the various simulations. The key inputs for this analysis are summarized Table 6-3. These inputs are used for all simulations shown in Tables 10-1 and 10-2. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 649 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-6 Table 6-3 Summary of Key Inputs-CE Plant Design Parameter Analysis Value Core Power including Uncertainty (MWt) 3458 Number of Fuel Assemblies 217 Barrel/Baffle Total K/A2 [ la,' (Max Resistance Cases) [ la,' (MiflMid Resistance Cases) Steady State Depletion Total Peaking Factor, LHRGss < 13.75~ (k:W/ft)+s,al Peal~ Et'Q7 Nuclear Enthalpy Rise Hot Channel Factor, F!~ < 1.81+.-+e Peal~ Et'MC Steady State Depletion AXJa! Offset, AOs&Ntial Peak < +20.9%+9fl ktial Skew Pswef l,sea,isA ;M00.-2481 gpm total or-l-hll 14 gpm/FA~ High Pressure Safety Injection (HPSI) Flow Rate M001654 gpm total or~7.6 gpm/FA ~827 gpm total or~3.8 gpm/FA Low Pressure Safety Injection (LPSI) Flow Rate 0 gprn (Isolated on sump switchover) Containment Pressure during Recirculation Phase (psia) ~'RffiH ieally Gale\lla,ea 14. 7 ECCS T ernperature during Recirculation Phase (°F) 212 Recirculation Actuation Signal (min) 20 Netes: I. +Re ;l4QQ gpm ease was eA~' iAel\laea iA lfle mifiim\lffi BB FesisteAee eAalysis. 6.4 BABCOCK AND WILCOX PLANT MODEL The base plant model selected for the B&W analysis is a high-power B&W plant design. The base plant model was developed for Appendix K PCT and clad oxidation analysis. The analysis is based on the B& W SBLOCA EM described in [ ]'*'. This model already conforms to Appendix K assumptions; however, certain changes were required. The major changes to the base plant model are discussed in further detail below:
  • Break Location For the analysis, a~EG break in the horizontal pipe connected to thebellom ofthll hot leg nozzle was analyzed. The Ilse of the Q.5 ff HLB is appropriate feF tms aRa!ysis to FSfJFeseat !Re h1mtiag DEG HLB fer the fell01.vifl.g Feasoas:
  • Tlte tiffte ofiRterest fer this e1,*ehtetieft is after tlte EGGS sttetieH seltfee hes svi'iteltea te the eefttaiftffl.eftt SltffifJ (whielt is essttfftea te 1:ie at 2Q RHfttttes).
  • bHak is la~s SftBQglt ts Elsprsss1,1ri.zs IRs RC:i, l:islsw IRs low prsssltfs iRjseQsft (LPI) raRottt eoaElitioa bsfers tit.is Qffis, wltiel~ is ths l:isha,,qsr SJ,psetsEI fello*Niag a DEG erea-k-, *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 650 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-7

  • MoEl8liRg thls ar8al. sii'!8 allows th8 HS8 ofth8 S8LOCA mi!thoElology, whlsh is 98tt8r Elevelofl8EI for lor1ger trartsieRts thart the largs HL8 methodology resHlting irt more roaHst Since the base plant model simulated a CLB, the location had to be moved. This was completed by moving break components from the cold side of the broken loop to the hot side. The loop containing the pressurizer remained intact. This change also required that an accumulator and ECCS model be input into the broken loop such that ECCS flow from all loops was considered.
  • Decay Heat Model The 1971 ANS infinite+ 20% (Appendix K Standard) was already included in the base model; therefore, no changes were made to the decay heat model.
  • Core Volumes The core control volumes were switched from modeling equilibrium conditions (which is needed for calculating a short-term PCT) to non-equilibrium conditions. This change allowed the code to run for long periods of time in a pool boiling mode.
  • ECCS Model Since this analysis extends the simulation into the sump recirculation phase, additional trips and fills were added to the ECCS model to simulate switchover from BWST injection to sump recirculation.
  • Barrel/Baffle Flow Resistance The BB design for all B& W plants is effectively the same and the BB flow resistances shown in Table 6-4 represents all B& W plants. The method and supporting calculations are contained inf r Appendix A, RAl-4.4 response, which confirms the BB flow resistances shown in Table 6-3.
  • Break Pressure Boundary Condition The pressure boundary condition at the break was f!Ot:-changed to be 14.7 psia for the short-term LOCA simulation refill and retlood phases, and. H.owl!ver, to 8l<t8REI 11!8 simHlatiort a~*oREI reflooEI the f)r@ssHr@ aoHRElary was set to 14.7 f)sia to maxim.ii'!e areak flo'll during the recirculation phase.
  • Core Inlet Blockage The dimensionless form-Joss coefficient at the firf;t..core inlet junctiollrteQ& was adjusted to simulate the instantaneous build-up of debris ateHfi.rtg the onset of the recirculation phase of the transient. The junction flow area at the BfSt sore r10Ele is [ ] a.c per FA which corresponds to the nominal [ ] a.c. The valHe of the foFHI loss soeffisi8rtt was ,*arieEI from sase to sase. Tables 11-1 ilflQ -H-+lists the form-Joss coefficient values applied for the ~simulations. The key calculation inputs for this analysis are summarized in Table 6-4. *-This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 651 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-8 Table 6-4 Summary of Key Inputs-B& W Plant Design Parameter Analysis Value Core Power including Uncertainty (MWt) ~2827.4 Number of Fuel Assemblies 177 Barrel/Baffle Total K/ A2 [ )"' Axial Peaking Factor 1.7 Peak Linear Heat Rate Limit (kW /ft) 173 Axial Peak Power Location Top Axial Skew-~! I ft MiA I 4351500 gpm~ Low Pressure Injection (LPI) Flow Rate1 Mim n~,;, gpm Containment Pressure during Recirculation Phase (psia) 147 ECCS Temperature during Recirculation Phase (°F) 200 Sump Switchover Time (min) 20 Notes: 1. Minimal (throttled) flow during sump recirculation.TAe m ini-JAU!ll LPI flew rnte v,es uses te ealeulates .... -!!A64.i.... TAe menimWA bPI flew mte was uses le eelettlele ~"'* 2. TAe LPI flew rnle fellewea e flHH,fl ettFYe iA tAe eAel)*sis. TAB ,*elue sAewA is tl,e flew et F'dfl sttl 88Aeii~i8M.

6.5 REFERENCES

6-1 WCAP-15644-P, Rev. 2 (Proprietary) and WCAP-15644-NP Rev. 2 (Non-Proprietary), "APlOOO Code Applicability Report," March 2004. 6 3 6 1 4-46-2 [ *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 7 REACTOR COOLANT SYSTEM STATE WCAP-17788-NP Mark-ups Page 652 of782 7-1 The RCS state during the post-LOCA LTCC phase of the postulated accident is discussed in this section. Specifically, the RCS conditions prior to and after the anival of debris are discussed. The RCS state prior to the anival of debris describes the initial conditions of the system at the point of switchover to sump recirculation, while the RCS state after debris anival describes the system response after the application of core inlet blockage. The overall RCS state is obseived to be similar for all plant categories and the discussion provided in this section is applicable to all plants considered in the analysis. The focus of this section is primarily on the RV and the flow patterns that are present during the post-LOCA transient. However, additional discussion is provided to also describe the SG state and RCS loops. The discussion is broken into two segments; the RCS state and RV flow patterns present prior to the anival of debris (no core inlet blockage) and the RCS state and RV flow patterns after the anival of debris (core inlet blockage). The segment after the anival of debris is further divided into two periods; the period prior to complete core inlet blockage and the period after complete core inlet blockage. It is also necessary to define when the LTCC phase of the transient begins. For the purposes of this analysis, the LTCC phase begins after the core region has completely quenched and core temperatures have stabilized to acceptably low levels. The RWST is supplying coolant to the ECCS and injection is into the cold legs. Upon switchover to sump recirculation, it is assumed that debris-laden coolant begins to enter the ECCS, where it is transported to the RCS and begins to collect at the core inlet. 7.1 PRIOR TO DEBRIS ARRIVAL Decay heat is at its highest during this segment. To satisfy DHRFor the HLB, fluid enters the downcomer, travels through the LP, into the core (where it removes DH), into the UP, and exits out the break. As decay heat diminishes with time, ~the boiling rate in the core region also diminishes. As a result, the core void fraction decreases and the collapsed liquid level increases, as does the liquid inventory in the RV. -aml-tThe ameunt efliquid carryover out of the break is equal to the ECCS flow rate less boil-off and liquid needed to account for the slow inventory increase in the RV. The BB channel continues to fill, by circulating liquid reaching the UP. The seRsisteRt with the downcomer level is below the bottom of the cold legs, and the upper downcomer and upper head is mostly voided with He lit:tttiEI being previEleEI threttgk the UHS1'1s sinee the Hfl)'ler ElewReemer has yet te Bil. At this point, the loop piping and the SGs are mostly voided except for possibly some liquid in the loop seals. The majority of the-ilfl& steam generated in the core exits through the break. Some steam can flow through openings in the upper RV region (UHSNs, RVVVs, HL nozzle gaps, etc.) or around the loop to condense on the ECCS injected into the cold side of the RV. The predicted flow patterns within the RV just prior to sump recirculation are depicted in Figure 7-1 for an upflow BB plant without pressure relief holes. As the figure shows, ECCS enters the cold legs, flows into the downcomer and enters the inner RV regions. At this point in time, the downcomer collapsed liquid level is most likely above the mid-plane of the active fuel but below the cold leg elevation. The exact location of the downcomer collapsed liquid level depends on the specific RCS and ECCS design, plant condition at the initiation of the postulated accident, and the time at which sump switchover occurs . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 653 of782 'WESTINGHOUSE NON-PROPRIETARY CLASS 3 7-2 For the purposes of this discussion, it is assumed that the down comer collapsed liquid level is at the same elevation as the top of the active fuel. Liquid enters the inner RV, flows through the LP and approaches the core inlet. In Figure 7-1, the core region is represented by a low-power (LP) region, an average-power (AVG) region, and a high-power (HA) region. In general, the high-power region is in the central part of the core and the low-power region is around the periphery of the core. As shown in the figure, flow through the core inlet is predominately upward with a flow distribution that is skewed higher in the higher-power regions of the core. Core inlet flow at the core periphery can be oscillatory with periods of downward flow occurring. The exact flow distribution and mixing patterns at the core inlet are plant-dependent; however, it can generally be said that higher flows at the core inlet tend to result in more even flow distribution with fewer oscillations in the peripheral region, while lower core inlet flows result in a more uneven flow distribution and more oscillations at the core periphery. The flow patterns within the core region, as shown in Figure 7-1, are predominately upward. As the transient progresses, decay heat decreases and a global circulation pattern can begin to form in the core region. At this point, periods of downward flow may exist in the lower-power peripheral regions. As decay heat further decreases, flow in the core periphery can become predominately downward. The mixture level in the core region is al the elevation of the hot leg break, which allows liquid to~ Yeiel iraetieR flew regime exists at Hie sere eit-it. Steam eKitiRg the sere teRels le eRlraiR liE}ttiel with it. A fl0rl:ieR efths li!Rlraieeel fo11,1iil saR exit the break or, wmls aReH!.sr J!eFtieR saRpossibly deposit on structures contained in the UP. As liquid accumulates in the UP, it will drain back to the core region, especially around the periphery where the power and steaming rate are lower. This behavior can also impact the circulation patterns seen in the core region. Liquid from the UP drains into the lower-power periphery of the core, which promotes downflow. The excess liquid in the core periphery then feeds the hotter regions through cross flow. The flow patterns in the BB region just prior to sump switchover depend on the collapsed liquid level in the BB channel. The BB collapsed liquid level is dependent on the downcomer collapsed liquid level and generally lags behind by several feet. For a condition in which the downcomer collapsed liquid level is at the top of the active fuel, the BB collapsed liquid level is likely to be somewhere below the top of the active fuel. For an upflow BB plant, the flow behavior at the BB inlet is similar to that seen in the core periphery. Flow through the BB inlet is mest likely eseillate1ypredominately downward (i.e., from the BB channel into the LP) at this phase of the transient. Again, however, the enaet flew fl&tlem ile13e1tils ee the s130eifie 13laRt eeeelitiee aeel is a fueetiee ef the elewReemer available elriviRg heael aRel the UP pressure. If the ileweeemer eriviHg heeil is high eRettgh te evereeme the BB flew resistaHee see the UP 13resssre, flew through the BB inlst will be upwaril. Ceeversel:)', ifH!.e Eieweeemer i1Fi1,iieg heaEI is eat high eeeugh, liE}ttiEI 688 flew ffBffl the UP regieH iH the BB, resslting iR elewHware flew H!.resgh the ehaflftel. A mere eempleK situatieH aFises fer J!laets with pressure reliefheles, siRee semmueieatiee eicists aetweeR the BB &REI eere J!efi13hel) et inlerffleEiiete ele*ietiees. fer tms eese, there eettle be flew inle the BB freffl the sere peFiphel)' at same press11re reliefhele ele\*atieRs aREI flew eut ef the BB iflle the sere at ether elevatiees. The situation is different for a downflow BB plant. In this design, there is no communication between the BB channel and the UP. Flow enters the top of the BB from the downcomer and flows downward to the core inlet, provided the downcomer collapsed liquid level is above the elevation of the *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 7.2 AFTER DEBRIS ARRIVAL WCAP-17788-NP Mark-ups Page 654 of 782 7-4 After switchover to sump recirculation, debris begins to transport through the ECCS and enters the RV, where it can collect at the core inlet. As debris collects at the core inlet, the resistance to flow through the core inlet increases, which allows the downcomer to fill potentially to the cold leg elevation, depending on the net BB channel resistance. At this ~0i11tlf the level reaches the cold leg for a Westinghouse or CE plant, a fraction of the ECCS flow begins to spill into the crossover legs and a fraction of the ECCS continues to enter the RV. The BB has completely flooded and, for an upflow plant, flow is predominately upward through the BB. Since the core inlet is only partially blocked, flow continues through the core inlet, but the flow rate is reduced due to the added resistance and the flow distribution across the core inlet is more uniform with upward flow in all channels. (This assumes uniform debris collection at the core inlet, as was assumed in the analysis.) If the debris collection across the core inlet is non-uniform, the flow distribution may also be non-uniform with higher flow in areas with less debris. Figure 7-2 provides a depiction of the RV flow patterns predicted under conditions of partial core inlet blockage for an upflow BB plant without pressure relief holes. The presence of pressure relief holes changes the flow patterns in the BB channel. Instead of flow traversing the entire BB channel elevation, upward flow from the BB inlet only reaches the first elevation of pressure relief holes and enters the core. Flow above the first row of pressure relief holes may continue to be in the downward direction and is fed by liquid entering the BB from the UP. Figure 7-2 also illustrates that cross flow from the periphery of the core toward the central region is enhanced due to the increased liquid inventory entering the core periphery at the top from the BB channel and the reduction of flow through the core inlet. As debris continues to accumulate at the core inlet, flow resistance continues to increase and the core inlet flow continues to decrease while the BB flow increases. Also, the crossover legs continue to fill with liquid. Once the crossover legs have filled, the upper downcomer begins to flood and liquid eventually reaches the UHSN elevation if the plant has them. I:t---theflFor these plants, the ECCS can flows through the UHSNs and floods the upper head, where it can drain into the UP and core region to provide additional liquid inventory for DHR. As the transient progresses, debris continues to enter the RV. At some point, chemical products may be generated in the sump and transported to the RV. The arrival of chemical products to an established debris bed at the core inlet can result in complete core inlet blockage, which changes the RV flow patterns as depicted in Figure 7-3 for an upflow BB plant. As shown in the figure, the RV flow patterns are similar to those seen during partial blockage, except that flow through the core inlet has ceased and flow through the BB (or the UHSNs in the case of downflow BB plants) is the only liquid reaching the core region. This change also affects the flow patterns seen in the core region by increasing the downward flow in the periphery and the cross flow toward the central region of the core. Since the amount of liquid entering the core has decreased due to the loss of the core inlet flow path, boiling in the core becomes more vigorous. This leads to more chaotic void motion that tends to increase the overall mixing in the core by enhancing the cross flow radially across the core. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 655 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 8-1 8 WESTINGHOUSE UPFLOW BARREL/BAFFLE DESIGNS In this section, results from the Westinghouse uptlow plant category are presented and discussed. The range of conditions and case matrix are provided in Section 8.1. Results from the analysis are presented in Section 8.2. This section is broken into several subsections and the material contained in each subsection is summarized as follows:
  • In Section 8.2.1, results from a case that did not model debris build-up at the core inlet are used to describe the RCS state at the time of transfer to sump recirculation and the arrival of debris. Since all simulations are identical prior to that point in the transient, the discussion in this section is applicable to all cases. In the simulations, transfer to sump recirculation occurs 20 minutes after the postulated LOCA.
  • In Section 8.2.2, results from the case used to determine thlock are presented. This case did not apply partial blockage to the core inlet prior to the application of complete core inlet blockage. Complete core inlet blockage was applied instantaneously at time !block and was applied uniformly across all core channels. *
  • In Section 8.2.3, results from the case used to determine a value for Kmax are presented. This case applied partial blockage to the core inlet prior to the application of complete core inlet blockage . The partial blockage was applied instantaneously at the point of transfer to sump recirculation and was applied uniformly across all core channels. Complete core inlet blockage was also applied instantaneously at time thlock and was applied uniformly across all core channels. In Section 8.2.4, results from additional cases used to determine K,pii, and msp1i, are presented. For these cases, a linear ramp in resistance was applied uniformly across the core inlet and complete core inlet blockage was not simulated. Since these cases were used to assess the timing of the activation of the BB-AFPs~, the build-up of core inlet resistance was applied more slowly compared to the cases used to determine Kmax* As a result, the RCS response to core inlet blockage was much slower in that the downcomer fill rate and the activation of the BB eftftftftelAFPs occurred over a longer period of time. These simulations are more realistic with regard to the timing at which debris is expected to arrive at the core inlet. Section 8.3 summarizes and discusses the key analysis results. 8.1 RANGE OF CONDITIONS AND CASE MATRIX The simulation matrix used to determine lt,10ck and K.nax is shown in Table 8-1. For these cases, a maximum BB-AFP flow resistance was used. In the table, the loss coefficient column identifies the core inlet losses applied at the designated initiation times to simulate the collection of debris. All cases that modeled core inlet blockage applied a step change or a timewise-linear ramp to the loss coefficient applied at the core inlet. Cases OA and OB did not model core inlet blockage; Cases lA, lB, 2A, and 2B applied step changes; and Cases 3A and 3B applied linear ramps. The core inlet resistances applied for these cases are presented graphically in Figure 8-1, Figure 8-2, and Figure 8-3 . *** This record was final approved on 12/18/2017 11:42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-P Mark-ups Page 656 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 8-2 Step changes in loss coefficients are applied over a 60 second interval and are referred to as instantaneous ramps. For example, in Case 2A, a step change from Oto 7.5x 105 is applied from 1200 to 1260 seconds, and an additional step change from 7.5xl05 to lxl09 is applied from 4800 to 4860 seconds. The second ramp leads to complete core inlet blockage. For simulations that applied a linear ramp, the loss coefficient starts at zero and ramps to a value of 4xl06* Complete core inlet blockage is not applied to the simulations that apply a linear ramp. For Case 3A, the linear ramp occurs over a one-hour period and for Case 38, it occurs over a two-hour period. For all simulations, the sump recirculation flow rate is applied 1200 seconds after the initiation of the event. The simulation matrix used to determine Ksp1;1 and msplit is shown in Table 8-2. For these cases, a miniml!ffl maximum BBAFP flow resistance was used. In the table, the loss coefficient column identifies the core inlet losses applied starting at the designated initiation time and ending at the designated end time. For example, in Case 1, a linear ramp of the loss coefficient at a rate of ~.25xl04 /hr is applied starting at 1200 seconds and ending at H30,000 seconds. The ending value of the loss coefficient is ~5xl05* Complete core inlet blockage is not applied to these cases. For all simulations, the sump recirculation flow rate is applied 1200 seconds after the initiation of the event. Table 8-1 Simulation Matrix for tblock and K.nax -Westinghouse Upflow Plant Design Sump Recirculation Flow Debris Bed Model Case Rate (gpm/FA) Loss Coefficient Initiation Time (sec) OA 40 NONE NIA OB 18 NONE NIA lA 40 lxl09 4800 lB 18 lxl09 8580 2A 40 7 5x!D5llxla9 120014800 2B 18 5xl05llxla9 120018580 3A 40 4xla6/hr 1200 3B 18 2xla6/hr 1200 Table 8-2 Simulation Matrix for K..,u, and m,ptil-Westinghouse Upflow Plant Design Debris Bed Model (Linear Ramp) Case Sump Recirculation Initiation Time End Time Flow Rate (gpm/F A) Loss Coefficient (sec) (sec) l 40 6 25x l 04/hr6GOOl!Hc 1200 30,000-1-¥)00 2 30 6.25xl 04/hr6GOOl!Hc 1200 30,00~ 3 18 6. 25x 104 /hr6GOOl!Hc 1200 30,00~ 4 12 6.25x l 04/hr6GOOl!Hc 1200 30,00~ 5 8 6.26x l 04/hr6GOOl!Hc 1200 36,00~ *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 657 of 782 8-5 approach by taking the timing of debris arrival out of the solution. Taking this approach inherently leads to a conservative K.nu value. This is demonstrated by comparing K.nu to the final form-losses applied to the Series 3 cases. From Table 8-3, the final form-loss applied to the Series 3 cases was 4x 106, which almost an order of magnitude higher than K.n ... With regard to BAPC, all cases demonstrate that, after core inlet blockage, the break exit quality remains sufficiently low such that boron is flushed from the core and concentrations are expected to remain well below the solubility limit. Further, all cases demonstrate tliat the core mixing patterns are such tl1at the core can be considered well-mixed and no localized regions containing higher boron concentration are expected to form. Key results from the K,p.i, and msp1i, simulations are summarized in Table 8-4. The IC,p1i, values shown in the table are used in conjunction with the ECCS sump recirculation flow rates to generate the curve shown in Figure 8-4. The time that K.i,ii, occurs is determined by examination of the BB exit flow rate. The first timestep in which the BB exit flow rate becomes positive is defined as the K.i,ai, time. If flow oscillations (positive BB exit flow followed by a reversal to negative flow) occur, the time ofKsp1i1 is selected after the flow oscillations stop and the BB exit flow remains positive. The fraction ofECCS flow through the core inlet and BB shown in Table 8-4 are taken at the end of the core inlet form-loss ramp. The transient flow split between the core inlet and S&-AFPs is shown in Figure 8-5 for the five ECCS recirculation flow rates investigated. The flew Sf)Ht is ref)reseatea es the ffaetiea eftetal EGGS resirs1tlati0R flaw tlu*eygl~ tlaie lHl ilfla is tilellee as a fYHsliaR af tlaie saH ifHet resistaRse felJewiRg The parameter m,plit is defined as the fraction ofECCS recirculation flow entering the RV downcomer that reaches the core region through the AFPs and is calculated as follows: where, mss + muHsN msplit = mECCS-VS m88 = The liquid mass flow rate through the BB channel mu HSN= The liquid mass flow rate through the UHSNs mEccs-vs = The liquid mass flow rate from the cold legs into the downcomer Equation (8-1) As shown in Figure 8-5, mspLit is a function ofECCS flow rate, and the value ofmsph1 increases as ECCS flow rate increases. Two curves that bound the msp1it on the low side are provided in the figure. The curve fit in plot a) should be applied if the ECCS recirculation flow rate is greater tlian 18 gpm/FA. The curve fit in plot b) should be applied if the recirculation flow rate is less than or equal to 18 gpm/FA. Bounding the ffispii, results on the low side maximizes debris collection at the core inlet by minimizing the amount of debris bypass through the AFPs. Defining msplit as the fraction ofECCS flow entering the RV that reaches the core through the AFPs conservatively neglects the ECCS flow split between RV and the steam generators and allows all the debris entering the RCS to transport to the RV. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 658 of782 8-6 Table 8-3 Summary of Results for thioci. and K..... -Westinghouse U pflow Plant Design Core Inlet Pressure Time Core Inlet Core Inlet Average Core Inlet Drop Break Case Resistance Loss Mass Flow Average Exit PCT Applied Coefficient (K) Rate per Velocity across Quality FA Debris Bed ---seconds ---lbm/sec ft/s psid ---OF OA NIA NIA 5.3 0.54 -0.05 <260 OB NIA NIA 2.4 0.22 -0.20 <260 IA 4800 lxld' 5.3 0.54 -0.25 <500 1B 8580 lxla9 2.4 0.22 -0.25 <800 2A 120014800 7 5xla5/lxla9 0.56 0.057 15.7 0.20 < 700 2B 1200/8580 5x101/lxla9 0.66 0.067 14.4 0.25 < 800 3A 1200-4800 0-4xl06 0.26 0.026 17.5 0.20 <525 3B 1200 -8580 0-4xl06 0.26 0.026 17.5 0.25 <500 Table 8-4 Summary of Results for K.i,w and m,.u, -Westinghouse U pflow Plant Design Fraction of ECCS Fraction of ECCS Final Pressure Drop Case Time of K.i,w K.,m Flow through Core Flow through across Debris Bed Inlet Barrel/Baffle ---seconds ---------psid 1 1295+&-W ]65~ 0.43~ 0.57~ 16.19,e 2 1384.~ 3203~ 0.4~ 0.57~ 159&-4 3 180~ 10,50~ 0.4~ 0.57~ 14.7~ 4 2460~ 21,884+¥+ ; 0.4:W,W 0.57~ 138M 5 4034~ 49,2]~ 0.44G,'.7% 0.5~ 8.3M ,.§. ; *** This record was final approved on 12/1812017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 659 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 60000 50000 40000 \ I W-Upflow Curve Fit: y = 2.0x106x*175 I \ ' -. -*" 30000 a. ':.:.~ 20000 \ i ' 10000 --....... ----0 0 5 10 15 20 25 30 35 40 45 ECCS Flow Rate (gp m/FA) Figure 8-4 K.,n, as a Function ofECCS Recirculation Flow Rate from Westinghouse Upflow Analysis 8-7 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 0.5 0.4 -' *" 0.3 a-E 0.2 -40gpm/FA 0.1 --30gpm/FA ....... 18 gpm/FA 0 O.E+OO l.E+05 2.E+05 3.E+05 4.E+05 K-Ksplit a) ECCS Recirculation Flow Rate Greater than 18 gpm/FA -..!. E 0.6 Curve Fit: y = 0.151n(x)-1.44 0.5 0.4 0.3 0.2 0.1 0 O.E+OO l.E+05 2.E+05 3.E+05 K-Ksplit -18gpm/FA --12gpm/FA -Bgpm/FA 4.E+05 b) ECCS Recirculation Flow Rate Less than or Equal to 18 gpm/FA WCAP-17788-NP Mark-ups Page 660 of 782 8-8 5.E+05 5.E+05 Figure 8-5 Fraction ofECCS Recirculation Flow through the BB following Ksp11 from Westinghouse Upflow Analysis *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 8.2.4 After Debris Introduction -Calculation ofKspm and msput WCAP-17788-P Mark-ups Page 661 of 782 8-43 Five additional cases were run to determine K..,ii, and msplit* For these cases, a linear ramp in resistance was applied at the core inlet and complete core inlet blockage was not simulated. Since these cases were used to assess the timing of the activation of the BB channel, the build-up of core inlet resistance was applied more slowly compared to the cases used to determine Km... As a result, the RCS response to core inlet blockage was much slower in that the downcomer fill rate and the activation of the BB channel occurred over a longer period of time. It is noted that these simulations are more realistic with regard to the timing at which debris is expected to arrive at the core inlet. Even though five simulations were completed to cover the full range ofECCS flows expected during sump recirculation, only the high-, mid-, and low-flow cases were selected for discussion in this section. Similar trends were obseived in the two cases not discussed. 8.2.4.1 Case 1-40 gpm/FA Select transient plots from Case 1 are shown in Figures 8-35 through 8-38. The RCS response to core inlet blockage was expected and is generally consistent with the transient response discussed in Section 8.2.3. Figure 8-35 shows the core inlet and BB exit flow rates compared to boil-off. The figure demonstrates that flow to the core is well above boil-off during the entire transient. The flow response to core inlet blockage is also shown by the figure. As core inlet blockage is applied, the pressure drop across the core inlet increases. Once Kspit is reached, the BB exit flow rate becomes positive and increases as the magnitude of core inlet blockage increases. As a resttlt, the eere ifllet flew rate Eleen,ases eeMisteflt witk tlu, rate tkat !Re BB flew rate i11ereases. Figure 8-36 shows the transient downcomer and BB collapsed liquid levels. As core inlet blockage is applied, both the downcomer and BB collapsed liquid levels increase as expected. When Ksp1;, is reached, the BB collapsed liquid level indicates that the BB channel is completely flooded and the downcomer collapsed liquid level is several feet higher. As core inlet blockage continues to increase, the downcomer continues to flood and eventually reaches the UHSN elevation. The PCT transient is shown in Figure 8-37. The figure indicates that the PCT remains well below 800°F, and the lack of any significant heatups indicates that the core never uncovers after application of core inlet resistance. Figure 8-38 shows the pressure drop across the core inlet and the core inlet liquid velocity. As expected, the core inlet velocity decreases as the pressure drop across the simulated debris bed increases . -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 662 of 782 0 (/l (/l 0 :s WESTINGHOUSE NON-PROPRJETARY CLASS 3 S'ITCHO Ell TIM[ 01 LOrF R TE CO£ INLET FLOW RATE A REL/ AFFLE £ IT FLO' TE 200 ....... .---------------------------, 0 ' ' . t ....................................................... . . ' , \ , ............. :.. .............. : ........... : ........... : .......... . . ... ... "_ . . . .. ~'" ... ,.~ . : .. __ '"--.. --=,-~~-..::.:.::.!..::..-:~-~-~ ./,---~------:--, : : . r----------: -----: ------:------8-44 Figure 8-35 K,put Case 1-Core Inlet and Barrel/Baffie Exit Flow Rates Compared to Boil-off *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 663 of 782 ---.. _ ...__.. cu > (lJ __J WESTINGHOUSE NON-PROPRIETARY CLASS 3 S'11ITCH01ER TIME DO 1NCOIAER CHANNELS LOOP DO 1NCOMER CHANNELS LOOP OWNCOMER HANNELS LOOP DO NCOMER CHANNELS LOOP BARREL/BAFFLE CHANNEL ( ! o. 9. 28. 4 . 67) 2 9. . 27. 40. 66} 3 7. 6. 2 . 36. 64 4 8. 17. 2 . 9. 65 ) 30~~-------------------------~ --4 (* 8 ,_ ,_ 2 6 0 ...j-JL......1.-J..___L_~T --'---'----'---r-,-.,__,_.,_.J.' -,--,_J'L--..l'--'--'-,.----'L--..J......~--l 500 6400 2::lOO 18200 24100 30000 Ti e (sec) Figure 8-36 K,p11t Case 1 -Downcomer and Barrel/Baffle Collapsed Liquid Levels 8-45 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 .... (lJ 0... Q) 236 I-WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCHO ER TIME HOT ROD PCT HOT ASSEMBLY PCT WCAP-17788-NP Mark-ups Page 664 of 782 8-46 220 +-J.--'---'-__J'----,----'---'-__J'----,---'-_,_---'-..---'-----'-----'-..---'-----'----J.---1 500 6400 2300 18200 24100 30000 Time (sec} Figure 8-37 K,put Case 1 -Hot Rod and Hot Assembly Peak Cladding Temperatures *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 665 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Pr ss re (psi) SWITCHO ER TIIAE ----DEBRIS BED PRESS RE DR P Velocity ( /sec) ---------LO PO ER INLET LI UID VELOCITY ----AVERAGE NON-GUIDE TUBE INLET LI ID VELOCITY ---* AVERAGE G IDE T BE INLET LI UID VELOCITY HOT ASSEMBLY INLET LI UI VELOCITY a-----------------------~o.7 (U ...... :::, V) (J) (U ..... a_ o. 0.4 .2 \ . . . 0.3 \ 3.6 0.1 *-. ----*-* o __ ........ _,_ __ ._-.-_.___.__.__....-_.__.__.__,_~~~-r~._~_._-o 500 6400 12.300 18200 woo 30000 Time (sec) Figure 8-38 Case 1 -Debris Bed Pres.sure Drop and Core Inlet Liquid Velocity 8-47 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTJNGHOUSE NON-PROPRIETARY CLASS 3 8.2.4.2 Case 3 -18 gpm/FA WCAP-17788-NP Mark-ups Page 666 of782 8-48 Select transient plots from Case 3 are shown in Figures 8-39 through 8-42. The RCS response to core inlet blockage was expected and is generally consistent with the transient response discussed in Section 8.2.3. Figure 8-39 shows the core inlet and BB exit flow rates compared to boil-off. The figure demonstrates that flow to the core is welJ above boil-off during the entire transient. The flow response to core inlet blockage is also shown by the figure. As core inlet blockage is applied, the pressure drop across the core inlet increases. Once K.p1it is reached, the BB exit flow rate becomes positive and increases as the magnitude of core inlet blockage increases. As a resah, the sore inlet flow rate desreases soMisteRt with the rate that the BB flow rate iRsreases. Comparing this flow response to the high-flow case described previously, it can be seen that reducing the ECCS flow results in a longer time period to reach Ksplit* Figure 8-40 shows the transient downcomer and BB collapsed liquid levels. As core inlet blockage is applied, both the downcomer and BB collapsed liquid levels increase as expected. When K,p1it is reached, the BB collapsed liquid level indicates that the BB channel is completely flooded and the downcomer collapsed liquid level is several feet higher. For this case, the ECCS flow rate is not high enough to completely flood the downcomer to the UHSN elevation during the simulation. The PCT transient is shown in Figure 8-41. The figure indicates that the PCT remains well below 800°F, and the lack of any heatups indicates that the core never uncovers after application of core inlet resistance. Figure 8-42 shows the pressure drop across the core inlet and the core inlet liquid velocity. As expected, the core inlet velocity decreases as the pressure drop across the simulated debris bed increases. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 667 of 782 ....---.... u (I) cn E ..c ---2 0 a::: 3: 0 L,__ en en 0 2 -900 -600 -300 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCHOVER TIME BOILOFf RAH CORE INLET FLOW RATE BARREL/BAFFLE EXIT FLOW RATE ....... , .... ~* .......................... . '-~~, ... -... --,_ \. _ ... ...... _ -500 6400 12300 8200 24 00 JOOOO Ti e (sec) 8-49 Figure 8-39 K.i,ut Case 3 -Core Inlet and Barrel/Baffle Exit Flow Rates Compared to Boil-off *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 668 of 782 (lJ > Q.) _J WESTINGHOUSE NON-PROPRIETARY CLASS 3 S'NITCHO ER TIME DO NCOIAER CHANNELS LOOP DOWNCOMER CHANNELS LOOP DO NCOMER HANNELS LOOP DO NC MER CHANNELS LOOP BARREL/BAFFLE CHANNEL ( Io. 19. 28. 41. 67) 2 9. . 27. 40. 6 } 3 7. 6. 2 . 38. 64 4 8. '7. 2 . 9. 65 ) 30~~-------------------------~ 24 12 * * * * * * ~* 6 0 500 6400 2300 18200 24100 30000 Time (sec) Figure 8-40 Ksp11t Case 3-Downcomer and Barrel/Baffle Collapsed Liquid Levels 8-50 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 600 .... .... 520-* --u.._ .___, 440-::::J ....... 0 ,._ <lJ a... WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCHOVER TIME HOT ROD PCT HOT ASSEMBLY PCT WCAP-17788-NP Mark-ups Page 669 of 782 8-51 Q.) 360-* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  • I--280 -200 500 I I I I 6400 I. I I I I I I 2300 16200 Time (sec) I I I I I I ' 24 00 30000 Figure 8-41 K,put Case 3 -Hot Rod and Hot Assembly Peak Cladding Temperatures *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-P Mark-ups Page 670 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 8-52 Press re (psi) SYilTCHO ER TIME ----DEBRIS BED PRESSURE DROP Veloc1 ty ( /sec) ---------LOW PO ER INLET LI UID VELOCITY ----AVERAGE NON-GUIDE TUBE INLET LIO 10 VELOCITY ----AVERAGE G IDE T BE INLET LI UID VELOCITY HOT ASSEMBLY INLET LI UID VELOCITY .--... ...-... u "ui 9-6 0-4 (l.) CL en ............ ...._,_ (l.) -...__,. '-::, >-en en *u (l.) 0 ,._ .4 Q.3 0.... (l.) > . '-. 0.1 *-, ... -... --*--o48U--L-'-~_JL._J.__J._~_1_-L-'-~___JL._J.__J._~-L-L-'--+-o 500 6400 2300 18200 24100 30000 Time (sec) Figure 8-42 Case 3 -Debris Bed Pressure Drop and Core Inlet Liquid Velocity *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 8.2.4.3 Case 5 -8 gpm/FA WCAP-17788-NP Mark-ups Page 671 of782 8-53 Select transient plots from Case 5 are shown in Figures 8-43 through 8-46. The RCS response to core inlet blockage was expected and is generally consistent with the transient response discussed in Section 8.2.3. Figure 8-43 shows the core inlet and BB exit flow rates compared to boil-off. The figure demonstrates that flow to the core is well above boil-off during the entire transient. The flow response to core inlet blockage is also shown by the figure. As core inlet blockage is applied, the pressure drop across the core inlet increases. Once Ksp1u is reached, the BB exit flow rate becomes positive and increases as the magnitude of core inlet blockage increases. As a rssHlt, the sere ifllet flev, rate desreases sensisteRt with the rate that the BB flew rate iRsreases. Comparing this flow response to the high and mid flow cases described previously, it can be seen that further reducing the ECCS flow results in a longer time period to reach Ksp,H* Figure 8-44 shows the transient downcomer and BB collapsed liquid levels. As core inlet blockage is applied, both the downcomer and BB collapsed liquid levels increase as expected. When Kspit is reached, the BB collapsed liquid level indicates that the BB channel is completely flooded and the downcomer collapsed liquid level is several feet higher. For this case, the ECCS flow rate is not high enough to completely flood the downcomer to the cold leg elevation . The PCT transient is shown in Figure 8-45. The figure indicates that the PCT remains well below 800°F. Figure 8-46 shows the pressure drop across the core inlet and the core inlet liquid velocity. As expected, the core inlet velocity decreases as the pressure drop across the simulated debris bed increases . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 ............ u <l) U'l ...__ ..0 ...__.. QJ 0 0::: 3:: 0 c;=: U'l U'l 0 :::E 200 ---900 --600 --\ -* JOO . -' . WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCHOVER TIME BOILOFf RAH CORE INLET FLOW RATE BARREL/BAFFLE EXIT FLOW RATE ,,~-----... ... ... ... -JOO 500 I I I I I I 600 . I I I I I I I I 4700 { 800 Ti e {sec) I 28900 WCAP-17788-NP Mark-ups Page 672 of 782 8-54 I I 36000 Figure 8-43 K.i,0t Case 5-Core Inlet and Barrel/Baffle Exit Flow Rates Compared to Boil-off *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • I --------Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 673 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 8-55 S'IIITCHO ER TIME DOYNCOUER CHANNELS LOOP 1 Io. 19. 28, 41. 67) OWNCOMER CHANNELS LOOP 2 9. ' , 27. 40. 661 DO NCOUER CHANNELS LOOP .3 7. 6. 2 . JB. 64 DO'NCOMER CHANNELS LOOP 4 8. '7. 2, 9. 65 BARREL/BAFFLE CHANNEL (' ) 24 8 ...--.... ....__, (1) > (l) _J 12 6 0 -+-'~-'---'---,--..____,____._..--__.___. _ _._-r-_....__._~-...---'----L-..__-t 500 7600 i700 21800 2 900 36000 Time (sec) Figure 8-44 Ksp11t Case 5-Dowocomer and Barrel/Baffle Collapsed Liquid Levels *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 600 20 S 440 <l) .._ :::::, ...._. 0 .._ <l) a.. v 360 t-280 200 500 WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCHOVER TIME HOT ROD PCT HOT ASSEMBLY PCT 7600 28900 4700 ~1800 Time (sec) WCAP-17788-P Mark-ups Page 674 of782 8-56 36000 Figure 8-45 K,pBt Case 5-Hot Rod and Hot Assembly Peak Cladding Temperatures *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 675 of782 WESTINGHOUSE NON-PROPR1ETARY CLASS 3 Pressure (psi) SWITCHO ER TIME ----* DEBRIS BED PRESS RE DROP Velocity f /sec) --------* LQ\y PO ER INLET LI UID VELOCITY ---* AVERAGE NON-GUIDE TUBE INLET LIO 10 VELOCITY ---* AVERAGE GIDE T BE INLET LI UIO VELOCITY (I) ..... ::::, U'l U'l (I) HOT ASSE~BLY INLET LIQUID VELOCITY o~-----------------------~0.1 8 o. ............................ O.( ct 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 2 0 500 ~. --7600 lHOO 2 800 Time (sec) * * * * * * * * * * * * * * * * * *
  • 0.1 28900 0 36000 Figure 8-46 K,p11t Case 5 -Debris Bed Pressure Drop and Core Inlet Liquid Velocity 8-57 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 676 of 782 8-59 downcomer and activate the BB channel, no significant heatups were observed when complete core inlet blockage was applied. This demonstrates the inherent conservatism in tblock* The value of the form-loss coefficient applied to simulate partial blockage was iterated upon to determine the maximum value that could be tolerated and maintain the PCT below 800°F. For the range ofECCS flows investigated, it was determined that a constant form-loss coefficient of 5xl05 produced acceptable results. In the prototypic system, it is unrealistic to expect all the fibrous and particulate debris to arrive at the core inlet instantaneously. It is expected that the arrival of debris will occur over some finite period of time that is on the order of hours. Since the exact timing of debris arrival is complex and will vary from plant-to-plant, the approach for determining Ka,.,. via application of an instantaneous ramp simplifies the approach by taking the timing of debris arrival out of the solution. Taking this approach inherently leads to a conservative Kmax value. This is demonstrated by comparing K.nax to the final form-losses applied to the Series 3 cases which applied a linear ramp. From Table 8-3, the final form-loss applied to the Series 3 cases was 4x106, which is almost an order of magnitude higher than the K.nax value determined from the instantaneous cases. The third set of core inlet blockage simulations (Section 8.2.4) examined a scenario in which a gradual build-up of debris was applied at the core inlet. These are considered the most realistic cases relative to how fibrous and particulate debris is expected to arrive at the core inlet; however, these cases do not simulate complete core inlet blockage. The gradual addition ofresistance at the core inlet slowly increases the downcomer level and delays the activation of the BB channel. Eventually, the downcomer driving head becomes sufficiently large to change the flow direction in the BB channel. After this point, flow from the LP is split between the core inlet and the BB and, as the core inlet resistance continues to build, the flow fraction to the BB continues to increase while the flow fraction to the core inlet decreases. The downcomer liquid level reaches the UHSN elevation, and this AFP becomes active. After this point, flow entering the reactor vessel from the cold leg splits between the core inlet, BB channel, and UHSNs. From these simulations, the core inlet resistance necessary to activate the BB sharuu,IAFP (Ksput) was determined to be a strong function of the ECCS flow. Ksp1;1 plotted as a function of ECCS flow rate is provided in Figure 8-4, and the corresponding flow split between the core inlet and the BB ehllflflelAFPs (msp;1) following Ksplit is shown in Figure 8-5. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 677 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9.Sx 105 to lx109 is applied from 15,600 to 15,660 seconds. For all simulations, the sump recirculation flow rate is applied 1200 seconds after the initiation of the event. 9-2 The simulation matrix used to determine Ksp1it and msplit is shown in Table 9-2. For these cases, the plant model with fflmiRHH!! maximum UHSN flow resistance was used. In the table, the loss coefficient column identifies the core inlet losses applied starting at the designated initiation time and ending at the designated end time. For example, in Case 1, a timewise-linear ramp of the loss coefficient at a rate of 60007.5xl05 /hr is applied starting at 1200 seconds and ending at~30,000 seconds. The ending value of the loss coefficient is ~xl05. Complete core inlet blockage is not applied to these cases. For atl simulations, the sump recirculation flow rate is applied 1200 seconds after the initiation of the event. Table 9-1 Simulation Matrix for thlod< and K... .. -Westinghouse Downflow Plant Design Sump Recirculation Flow Debris Bed Model Case Rate (gpm/FA) Loss Coefficient Initiation Time (sec) OA 40 NONE NIA OB &l 2 NONE NIA IA 40 lx!D9 15,600 2A 40 9.5xl05/lx1D9 1200115, 600 2B &l 2 75xl05/lxla9 1200112,000 Table 9-2 Simulation Matrix for K..11, and m,p11t -Westinghouse Downtlow Plant Design Debris Bed Model (Linear Ramp) Case Sump Recirculation Initiation Time End Time (sec) Loss Coefficient Flow Rate (gpm/F A) (sec) l 40 7.5xl04~ 1200 30, OOO-l-9;;l,OO 2 30 7.5xl04/hr~ 1200 30,000~ 3 18 7.5xl04~ 1200 30,0~ 4 12 7 5xl04/hrlJ,QQQlh,:-1200 30,0<me,-400 5 8 7. 5xl 04/hrl ::l,QQ()lhf 1200 30,0~ *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9.2 RESULTS OF ANALYSIS WCAP-17788-NP Mark-ups Page 678 of782 9-4 Key results from the tbiod< and K.nax simulations are summarized in Table 9-3. Cases OA and OB have no core inlet blockage applied. Case lA applies complete core inlet blockage and determines the minimum time that complete blockage can be tolerated. Cases 2A and 2B apply resistances to the core inlet prior to reaching complete core inlet blockage and are used to determine the maximum resistance that can be tolerated prior to reaching complete blockage. Based on the results presented in Table 9-3, it is concluded that LTCC can be maintained if complete core inlet blockage occurs 260 minutes (15,600 sec), or later, after the initiation of the LOCA event. This time is taken from the maximum ECCS recirculation flow case (Case lA). Prior to reaching complete core inlet blockage, a maximum supportable Kmu value of ~'1"4. 75x105, corresponding to a pressure drop of 14.8 psid across the core inlet, is determined to be the limiting value when a uniform resistance is applied instantaneously upon entering sump recirculation. These values are taken from the minimum ECCS recirculation flow case (Case 2B) and bound the range ofrecirculation flows investigated. With regard to BAPC, all cases demonstrate that, after core inlet blockage, the break exit quality remains sufficiently low such that boron is flushed from the core and concentrations are expected to remain well below the solubility limit. Further, all cases demonstrate that the core mixing patterns are such that the core can be considered well-mixed and no localized regions containing higher boron concentration are expected to form. Key results from the K,plitand m,plit simulations are summarized in Table 9-4. The K,plit values shown in the table are used in conjunction with the ECCS sump recirculation flow rates to generate the curve shown in Figure 9-3. This curve will be used in subsequent downstream calculations presented in Volume 1 to track the location of fibrous debris within the RV during the LTCC phase of the transient. The time that K.pu, occurs is determined by examination of the UHSN exit flow rate. The first timestep in which the UHSN exit flow rate becomes positive is defined as the Ksp1;1 time. If flow oscillations (positive UHSN exit flow followed by a reversal to negative flow) occur, the time ofl<.p1;1 is selected after the flow oscillations stop and the UHSN exit flow remains positive. The fraction ofECCS flow through the core inlet and UHSN shown in Table 9-4 are taken at the end of the core inlet form-loss ramp. The transient flow split between the core inlet and UHSN is shown in Figure 9-4 for the five ECCS recirculation flow rates investigated. The flow split, msp1;,, is defined by Eq. 8-1 with flow through the BB channel being equal to zero. The variable m"'1;1 is Ti!flU5@Rl@iil as the f1,1sti0R 0ft0tal EGGS r11sii=sulali0R !lew threugl'I the UHSJ>I anEI is flletteEI as a runslien efthe sere ifllet resistaase fellewiRg K.,,i..defined as the fraction of ECCS recirculation flow entering the RV downcomer that reaches the core region through the UHSN. These curves fit in Figure 9-4 will be used, in conjunction with }(.p;i, in downstream calculations to track the location of fibrous debris within the RV during the LTCC phase of the transient as described in Volume 1. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 679 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9-5 Table 9-3 Summary of Results for 41_ and K... .. -Westinghouse Downflow Plant Design Time Core Core Inlet Core Inlet Pressure Inlet Loss Average Core Inlet Drop Break Case Resistance Mass Flow Average Exit PCT Applied Coefficient Rate per Velocity across Quality (K) FA Debris Bed ---seconds ---lbmlsec ft/s psid ---OF OA NIA NIA 5.3 0.54 NIA 0.05 <250 OB N/A N/A 1.6 0.16 NIA 0.25 <300 IA 15,600 lxla9 5.3 0.54 -0.6 <800 2A 1200/15,600 9 5x105/lxla9 0.58 0.058 20.6 0.6 <650 I 2B 1200/12,000 ex+(l4.75xl05 /lxla9 0.62 0.062 14.8 O.M <+.W800 Table 9--4 Summary of Results for K..,u, and m,p11t -Westinghouse Downflow Plant Design Fraction of ECCS Fraction of ECCS Final Pressure Drop Case Time ofK.,11t K..11t Flow through Core Flow through UHSNs across Debris Bed Inlet ---seconds ---------psid 1 1891~ 14,39~ 0.790,JJ 0.21()41 19.7e-l-2 222~ 21,3654-1-+G 0.79Gc-W 0.21Gc-W 19.3+.4 3 3644~ 50,927~ 0.800,%+ 0.200-W 15.l~ I 4 576~ 95,073~ 0.800-74 0.2~ 14.8+& I 5 953~ 173,667~ 0.8~ 0.200,++ 14.7~ *** This record was final approved on 12/1812017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 680 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 200000 I I I ' ! W-Downflow Curve Fit: y = 3.4x106x*14 J 4\ \ 180000 160000 140000 \ \ ., .......... .....__ ......____ 120000 -*" 100000 80000 60000 40000 20000 -~ 0 5 10 15 20 25 30 35 40 45 ECCS Flow Rate (gpm/FA) Figure 9-3 Kspur as a Function ofECCS Recirculation Flow Rate from Westinghouse Downflow Analysis -..!.. "ii. "' E 0.3 0.25 0.2 0.15 0.1 0.05 Curve Fit: y = 0.0471n(x)-0.44 -40gpm/FA -+--nl-,_,.,rtif'c-----+-----j----1 --30 gpm/FA ******* 18 gpm/FA -12gpm/FA -8gpm/FA 0 ...._.. ___ _,__ ___ ,..._ __ __, ___ __,_ ___ _,_ ___ __, O.E+OO l.E+05 2.E+05 3.E+05 4.E+05 5.E+05 6.E+05 K-Ksplit Figure 9-4 Fraction ofECCS Recirculation Flow through the BB following Kspu, from Westinghouse Downflow Analysis 9-6 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9.2.3 After Debris Introduction -Calculation of Kmax WCAP-17788-NP Mark-ups Page 681 of 782 9-27 Cases 2A and 2B are used to determine a value for K.n,x-These cases apply partial blockage to the core inlet prior to the application of complete core inlet blockage. The partial blockages are applied instantaneously at the time of transfer to sump recirculation and are applied uniformly across all core channels. Case 2B produces the lowest Kmax value and will be discussed in this section. Throughout the duration of the transient, more-than-adequate core cooling flow is provided through the ECCS to the cold legs. The partial blockage is applied at 20 min (1200 seconds) and complete core inlet blockage is applied at-l4J...200 min (~12,000 seconds). After the partial blockage is applied, the RCS response is very similar to the response seen after complete core inlet blockage, as described in Section 9.2.2, except that flow continues through the core inlet at a reduced rate. Coolant from the ECCS backs-up and fills the downcomer to the UHSN elevation. From this point forward, the total flow entering the RV is split between the core inlet and the UHSNs. Figure 9-21 shows that the core experiences a short-duration temperature excursion after the application of partial core inlet blockage; however, PCT remains below 800°F. DHR is maintained via a combination of flow through the core inlet and flow through the UHSNs to the top of the core. The RV fluid mass is shown in Figure 9-22. When partial core inlet blockage is applied, the response in RV fluid inventory is different compared to the no blockage and complete core inlet blockage cases (Case OA and Case lA). The no blockage and complete blockage cases showed a sharp decrease in RV inventory upon entry to sump recirculation due to the loss ofECCS subcooling. In this case, the initial decrease is not as sharp since the application of partial blockage results in an increase in the downcomer collapsed liquid level, which offsets the reduction in RV inventory due to the loss ofECCS subcooling. The application of complete core inlet blockage later in the transient has only minimal impact on the RV fluid inventory. These trends are consistent with the behavior of the core collapsed liquid level as shown in Figure 9-23, which show the hot assembly collapsed liquid. The collapsed liquid levels in the other core channels show similar trends. The downcomer and upper head collapsed liquid levels are shown in Figure 9-24. When the blockage is applied, the downcomer collapsed liquid level quickly increases to the UHSN elevation due to the increased resistance at the core inlet. As a result, the upper head begins to flood with fluid from the downcomer and the total RV fluid mass increases due to the additional fluid in the upper downcomer and upper head. The core inlet mass flow rate and guide tube exit flow rate are compared to boil-off in Figure 9-25. The figure indicates that flow in excess of boil-off is maintained through the core inlet even after the application of the partial blockage. It is not until complete core inlet blockage is applied that the core inlet flow decreases to zero. In terms of guide tube flow, it is seen that after partial blockage, there is a delay associated with filling the downcomer and upper head to the upper guide tube elevation, after which liquid flow through the guide tubes begins. After complete core inlet blockage is applied, the amount of flow through the guide tubes is equivalent to boil-off. Figure 9-26 shows the pressure drop across the debris bed and the core inlet liquid velocities. The figure confirms that flow through the core inlet continues after the application of partial blockage and ceases after the application of complete core inlet blockage . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTIN"GHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 682 of 782 9-28 The break exit quality is shown in Figure 9-27. This figure shows that the quality prior to the application of partial core inlet blockage remains below +20%. After the application of partial blockage, the case shows a spike in the break quality (consistent with the core uncovery), which recovers and stabilizes at Bflfl£enift1alelybelow 40% prior to the application of complete core inlet blockage. When complete core inlet blockage is applied, the break exit quality increases sharply and then recovers to a value of roughly ~0%. Due to the large amount of liquid carryover out the break during the transient, BAP is controlled and boron concentrations in the RV will remain well below the solubility limit. A review of the RV mixing patterns after complete core inlet blockage indicates that flow from the UP flows downward along the core periphery and feeds the average and hot assembly via cross flow. This trend is comparable to the core mixing patterns observed after complete core inlet blockage for the Westinghouse upflow plant category (discussed in Section 8). *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 683 of 782 ..--... LL ...__.... QJ ,._ '.::) ...., 0 ,.._ QJ Cl. QJ 1--000 00 600 400 WESTINGHOUSE NON-PROPRJETARY CLASS 3 SWITCH OVER TIME / PARTIAL BLOCKAGE COMPLETE BLOCKAGE HOT ROD PCT HOT ASSEMBLY PCT I ! I 200-+-...J..L...---'~...___-,-__.____.~...___-,-__.____.~...___-,--......... ___.~...___-,-__.____.~~ 9-29 00 4000 7 00 1 000 14500 18000 Ti e (sec) Figure 9-21 Case 2B -Hot Rod and Hot Assembly Peak Cladding Temperatures *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 684 of 782 E ...0 200000 10000-. 40000-aoooo-WESTINGHOUSE NON-PROPRIETARY CLASS 3 SVITCH OVER TIME/ PARTIAL BLOCKAGE COMPLETE BLOCKAGE VESSEL FLUID MASS ... ... ... ... 9-30 II I I ' ' ' ' ' ' ' 50000-+--'-'-----...,__~..--,-'--......... __.~..---'----'-~'--~ ........ ___.~......_......-__.___.~......_-1 500 4000 7500 11000 18000 Time (sec) Figure 9-22 Case 2B -Reactor Vessel Fluid Mass *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 685 of 782 .---... +-' -.........., <J) > <J) _J 5 2 9 6 3 WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCH OVER TIME/ PARTIAL BLOCKAGE COMPLETE BLOCKAGE HOT ASSEMBLY COLLAPSED L IOUID LEVEL 9-31 0 ....u._..__ ........ __,,---'---'---'--""""T"-'---'---'--,---"--'---'---,,-.....___.__....._--1 500 4000 7500 1000 4500 000 Time (sec) Figure 9-23 Case 2B -Hot Assembly Collapsed Liquid Level *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 686 of 782 (l) > (l) _J WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCH OVER TIME/ PARTIAL BLOCKAGE COMPLETE BLOCKAGE DOWNCOMER PPER HEAD 30--.--.-~~~~-..----~~------------_-__ ....,_,..,,,_.,,_,,,. __ ::-:_::-:_:-::_c=_,::-_::-, __ ::-:_:-::_c=_-:,_,::-_l~:-::c=~-::-C::-:-:'":_:-::":'."'=""'"-='"-:C::-::-C::C_-=-=-::> ~'I/I'~ I 24 2 6 ,*. I ;-I --_.,,,.--.. -----------1 ... ___,.. .,,_,__ _ __,..,_ ....,..., ... _,.,._"""' 9-32 0 500 4000 7500 Ti 000 e (sec) 4500 1 000 Figure 9-24 Case 2B -Downcomer and Upper Head Collapsed Liquid Levels *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 687 of782 ,.--.. u (l) (/) .............. E ...0 .__... (l) +-' 0 O::'. 3:: 0 LL (/) (/) 0 2 6 0 400 200 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCH OVER TIME/ PARTIAL COMPLETE BLOCKAGE BOILOFF RATE CORE INLET FLOW RATE GUIDE TuBE EXIT FLOW RATE INTACT HOT LEG FLOW RATE I BLOCKAGE ! I -L,-------------------1 -----.. ---------:.:.-:::..-=-=--------------t-----~---., ---------------9-33 -200--+-......... ~'--................ ~....._ ........ __.._~.--........ __.._~.__-,--_...,_~.__ ........ .......,..~....._ ........ __.._--1 500 4000 7500 Ti 11000 e (sec) 14500 18000 Figure 9-25 Case 2B -Core Inlet, Guide Tube Exit, and Intact Hot legs Flow Rate Compared to Boil-off *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 688 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Press re (psi) SWITCH OVER TIME/ PARTIAL BLOCKAGE COMPLETE BLOCKAGE ---------DEBRIS BED PRESSuRE DROP Velocity(' /sec) ----LOW PO~ER INLET LI UID ELOCITY ---* AVERAGE NON-GU I DE TUBE INLET LI U ID VELOCITY AVERAGE GUIDE TUE INLET LI UID VELOCITY ---HOT ASSEMBLY INLET LIQUID VELOCITY ...--.... *en 0.. ..__... (l) ,_ ::, (/) (/) (l) ,_ Q_ 30.......-...-----------------------.-o.75 24 8 2 6 0 500 4000 7500 1 000 Ti e (sec) ---4500 0.5 0.25 0 -0.25 -0.5 8000 Figure 9-26 Case 2B -Pressure Drop across Debris Bed and Core Inlet Liquid Velocities 9-34 ...--.... u (l) Vi -............ -+-' ..__... >-.. u 0 (lJ > *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 689 of 782 0 0 o.s-I--"', ,, -WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCH OVER TIME / COMPLETE BLOCKAGE VESSEL SIDE BREAK PARTIAL BLOCKAGE ,, ,, ,, ,, , , , , I 1 1.,'\ ',, I 11 ,, , 1, I '1 ' ' ,, ,,, ~' l 1 I ' .. ' .... ,.,,, ... ,, ,,, "'\ ...... ,,,,,, , ............ ., ' II 1* 11 I\ ft 11 I\ I",, '* I l ,,,, 1, ,, ' I', ', 11 I I I I I I I' I,, I It I l 11 I II I' , ,, , ,, I 11 II If I' '1 i* '1 I 11 \I \J jl '1 It I ' I I I ( I I ) ) ' ... , ... ',, ...... -.. ,, ... , I I n " I I I
  • I 1 I I I I I , , ,, ,, ,, I 9-35 0-+-__. ... , __ ...._,__.,_....,.. __ ,,____.., __ ,__, ....... __ .._, ...... ,,...___..,_ ....... _~*--.._*_1,___,. __ .._, ...... , __ '--, 500 4000 7500 11000 4500 18000 Time (sec) Figure 9-27 Case 2B -Break Exit Quality *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9.2.4 After Debris Introduction -Calculation ofKsput and msput WCAP-17788-NP Mark-ups Page 690 of 782 9-36 Five additional cases were run to determine Ksp1;1 and lllspi;1. For these cases, a linear ramp in resistance was applied at the core inlet and complete core inlet blockage was not simulated. Since these cases were used to assess the timing of the activation of the UHSN AFP, the build-up of core inlet resistance was applied more slowly compared to the cases used to determine K.nax-As a result, the RCS response to core inlet blockage was much slower in that the downcomer fill rate and the activation of the UHSNs occurred over a longer period of time. It is noted that these simulations are more realistic with regard to the timing at which debris is expected to arrive at the core inlet. Even though five simulations were completed to cover the full range of ECCS flows expected during sump recirculation, only the high-, mid-, and low-flow cases are selected for discussion in this section. Similar trends were observed in the two cases not discussed. 9.2.4.1 Case 1-40 gpm/FA Select transient plots from Case 1 are shown in Figures 9-28 through 9-31. The RCS response to core inlet blockage was expected and is generally consistent with the transient response described in Section 9.2.3. Figure 9-28 shows the core inlet, UHSN, and guide tube flow rates compared to boil-off. The figure demonstrates that flow to the core is well above boil-off during the entire transient. The flow response to core inlet blockage is also shown by the figure. As core inlet blockage is applied, the pressure drop across the core inlet increases. Once Ksplit is reached, the UHSN and guide tube flow rate becomes positive and increases as the magnitude of core inlet blockage increases. i',s a res1tll, tke eeFe inl.et flew Fate aeeFeases eeHsisteHI with the F&le that the UIIS~I flew Fate ifleFeases. Figure 9-29 shows the transient downcomer and upper head collapsed liquid levels. As core inlet blockage is applied, the downcomer collapsed liquid level increases as expected. When Ksplit is reached, the downcomer collapsed liquid level has reached the UHSN elevation, and the upper head begins to flood. After a short delay, the upper head fills to the guide tube elevation, and coolant begins to enter the guide tubes and flows downward into the UP region of the RV. The PCT transient is shown in Figure 9-30. The figure indicates that the PCT remains well below 800°F, and the Jack of any significant heatups indicates that the core never uncovers after application of core inlet resistance. Figure 9-31 shows the calculated pressure drop across the core inlet and the core inlet liquid velocity. As expected, the core inlet velocity decreases after K.i,ii, and the pressure drop across the simulated debris bed continues to increase. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 691 of 782 ,,_ <..J (l) V) ...._ E ..0 -(l) -0 a:: ;:: 0 G: V) V) 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCH O ER TIU[ BOI LOFF" R.r..lE CORE INLET FLO RAlE UPPER HEAD SPRAY NOZZLE FLOW GUIDE T BEE IT fLO RATE R.t.TE 00,-,-,---------------------------, no 5-40 360 80 . I\ I I l ' I'.,.'.*'.'* ...... ' .. * ............ **.' .. * .... * ... '*.' ...... * . I I I I I ' ' ' \ ' ..... \* .................................................... . ,, ' * ', ',,. *,, . ', ,, ................. ........ '~-~.;..* ................................ . ---.... _ ... __ -... ___ _ ---,---...... __ . ___ , _____ --.. -* -o-+-.1.....L..__.L-....._--..-'--.....___,__.--......___,____...__..,,__.._--'..__...___--.-___...__......___._--i 500 6500 2500 18500 Time (sec) 24500 30500 Figure 9-28 Ksp11t Case 1 -Core Inlet and Upper Head Spray Nozzle Flow Rates Compared to Boil-off 9-37 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 692 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9-38 ' DO NNCOMER AND UPPER HEAD COLLAPSED LIQ ID LEVELS S ITCH O ER TIIH D 'NCOMER PPER HEAD >n""T"""S.--_,-----------:-------------------~ JO .. ----,r ,r:1--*.--, ..... ... ... J ... I ' * *

  • 24-*I* * * * * * * * *: * * * * * * * * * * * : * * * * * * * * * * * : * * * * * * * * * * * : * * * * * * * * * * * . . . . ... . . . a-.......... : ........... : ........... : ........... : .......... . -. . . . 2-........... : ........... : ........... : ........... : .......... . .......................................................... . ... . . . . ,,,* ...... _ *.** ;,--"***_.._. ** __....,..v~~*..._-, .. -...... ~-*** * * ....... -**--*-~ * **-*, * -.......... -* ... ' * ' 0
  • _# 500 6500 . 2500 8500 Ti e (sec) 24500 30500 Figure 9-29 Krp11t Case 1 -Downcomer and Upper Head Collapsed Liquid Levels *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 400 Q) 300 t--WESTINGHOUSE NON-PROPRIETARY CLASS 3 S 'ITCH O ER TIUE HOT RO PCT HOT ASSEUBL PCT WCAP-17788-NP Mark-ups Page 693 of 782 9-39 ........ 500 6500 2500 8500 24500 Time (sec) Figure 9-30 K,pHt Case 1 -Hot Rod and Hot Assembly Peak Cladding Temperatures -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 694 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Pressure (psi) S 'ITCH OVER TIME ----OEBR IS BED PRESSURE DROP elocity ( / ec) --------* LO' POWEi! INLET LIO ID VELOC IT ---* AVERAGE NOH-GUIDE TUBE INLET LIO ID VELOCITY ---* AVERAGE G IOE T BE INLET LI ID ELOCITY Cl) ..... VI (/) (l) H T ASSEUBL INLET LI ID VELOCITY I I I I I I 0.5 * * * * * * * * * * * * * * * * * * * *

  • r * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  • 0.25 *-*, -*---ct: 8 . . ....................................................... 0 * * -0.25 Q+-'--'--'---L-,,-.,___.__,_-.-_.__,._.,__-r-_,__.__._,,-.,___.__..._-+-_o.5 500 6500 12500 18500 24500 30500 Ti e (sec) V 0 v > Figure 9-31 Ksp11t Case 1 -Debris Bed Pressure Drop and Core Inlet Liquid Velocity 9-40 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9.2.4.2 Case 3 -18 gpm/FA WCAP-17788-NP Mark-ups Page 695 of782 9-41 Select transient plots from Case 3 are shown in Figures 9-32 through 9-35. The RCS response to core inlet blockage was expected and is generally consistent with the transient response shown in Section 9.2.3. Figure 9-32 shows the core inlet, UHSN, and guide tube flow rates compared to boil-off. The figure demonstrates that flow to the core is well above boil-off during the entire transient. The flow response to core inlet blockage is also shown by the figure. As core inlet blockage is applied, the pressure drop across the core inlet increases. Once Kspiit is reached, the UHSN and guide tube flow rate becomes positive and increases as the magnitude of core inlet blockage increases. As a result, the Gore iA:let flew rate aeGreases GeA:sistent with the rate that tht! UHSJ>I flew rate inGreast!s. Figure 9-33 shows the transient downcomer and upper head collapsed liquid levels. As core inlet blockage is applied, the downcomer collapsed liquid level increases as expected. When Ksp1i, is reached, the downcomer collapsed liquid level has reached the UHSN elevation, and the upper head begins to flood. After a short delay, the upper head fills to the guide tube elevation, and coolant begins to enter the guide tubes and flows downward into the UP region of the RV. Comparing this flow response to the high-flow case described previously, it can be shown that reducing the ECCS flow results in a longer time period to reach K,p1it* The PCT transient is shown in Figure 9-34. The figure indicates that the PCT remains well below 800°F and the lack of any significant heatups indicates that the core never uncovers after application of core inlet resistance. Figure 9-35 shows the calculated pressure drop across the core inlet and the core inlet liquid velocity. As expected, the core inlet velocity decreases as the pressure drop across the simulated debris bed increases . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 696 of782 720 (1) -0 , ,, WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCH OVER TIIH 801 LOFF RAH CORE INLET FLOW RAlE UPPER HEAD SPRAY NOZZLE FLOW GUIDE T BE EXIT FLO RATE i' .......................................................... . 1 I I . ;= 0 G: 360 .*......................................................... I ' ....... ._, ' ' -,,, "\.,. -.. . ' . . . 80 ............... -~ .... _._._ ..................................... . ---0 500 6500 ------.,-... ,-.:.~-2500 t8500 Time (secJ ---~----~-~-,--,--~----24500 30500 Figure 9-32 K,p11t Case 3 -Core Inlet and Upper Head Spray Nozzle Flow Rates Compared to Boil-off 9-42 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 697 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9-43 S 'ITCH O ER TIME D 'NCOUER PPER HEA 30 24 * -~-* * * * * *: * * * * * * * * * * *: * * * * * * * * * * *: * * * * * * * * * * *: * * * * * * * * * * * , . . . . 2 6 .... ----_____ ........ -: ...... -.--** , ..... 4'*-*-:-**---* . o-+--._...._....__._--._...___.__...._-.-__.__...._...._--._...___.___. ___ -.-__.__....._....__ 500 6500 2500 8500 24500 30500 Ti e (sec) Figure 9-33 K,p11t Case 3 -Downcomer and Upper Head Collapsed Liquid Levels *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 400 Q) 300 t-WESTINGHOUSE NON-PROPRIETARY CLASS 3 S 'ITCH OVER TIIH HOT ROD PCT HOT ASSHIBL PCT WCAP-17788-NP Mark-ups Page 698 of 782 9-44 i .... : ........... : ........... : ........... : .......... . 200 500 6500 2500 18500 Time (sec) 24500 30500 Figure 9-34 K,pttt Case 3 -Hot Rod and Hot Assembly Peak Cladding Temperatures *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 699 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Pressure (psi) S 'ITCH OVER Tit.IE -----DEBRIS BED PRESS RE DROP Velocity ( /sec) ---------L 'PO ER INLET LIO ID VELOCIT ----AVERAGE NOH-GUI E TUBE INLET LIO VEL CITY ----AVER GE G IOE T BE INLET LI ID ELOCllY (1) .._ VI VI (1) 20 6 ct 8 ... 4 .. 0 500 HT ASSELIBL INLET LI ID VEL CITY 0.75 05 0.25 .. _ *-.. ---.--. ................................................... 0 6500 12500 18500 n e (sec) -0.25 -().5 30500 Figure 9-35 Ksp11t Case 3-Debris Bed Pressure Drop and Core Inlet Liquid Velocity .-?? u 0 -!;. 9-45 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9.2.4.3 Case S -8 gpm/FA WCAP-17788-NP Mark-ups Page 700 of782 9-46 Select transient plots from Case 5 are shown in Figures 9-36 through 9-39. The RCS response to core inlet blockage was expected and is generally consistent with the transient response shown in Section 9.2.3. Figure 9-36 shows the core inlet, UHSN, and guide tube flow rates compared to boil-off. The figure demonstrates that flow to the core is well above boil-off during the entire transient. The flow response to core inlet blockage is also shown by the figure. As core inlet blockage is applied, the pressure drop across the core inlet increases. Once Ksplit is reached, the UHSN and guide tube flow rate becomes positive and increases as the magnitude of core inlet blockage increases. As a result, the sere inlet flew rate Elesreases sensistent with the rate that the UHSN Aew rate msreases. Figure 9-37 shows the transient downcomer and upper head collapsed liquid levels. As core inlet blockage is applied, the downcomer collapsed liquid level increases as expected. When Ksplit is reached, the downcomer collapsed liquid level has reached the UHSN elevation, and the upper head begins to flood. After a delay, the upper head fills to the guide tube elevation, and coolant begins to enter the guide tubes and flows downward into the UP region of the RV. Comparing this flow response to the high-and mid-flow cases described previously, it can be seen that further reducing the ECCS flow results in a longer time period to reach Ksplit* The PCT transient is shown in Figure 9-38. The figure indicates that the PCT remains well below 800°F . Figure 9-39 shows the calculated pressure drop across the core inlet and the core inlet liquid velocity. As expected, the core inlet velocity decreases after Ksplit and the pressure drop across the simulated debris bed continues to increase. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 70 I of 782 ....-... u (1) C/) ........... E ..0 ..::::.. (1) ---0 0::: ;:,. 0 G: Cl) V) 0 00 5~ J60 I I I WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCH OVER TIIH BOILOFF RATE CORE INLET FLO R"TE UPPER HE"D SPRY NOZZLE FLOW GUIDE T BE EXIT FLO' RATE RATE 80 . ' ........................................................ . I ' -,, .... -,----...... ---..... --,---~ ... ---... 1 .... , .. ---:-... --........ ....... --.. ~.1 .. -.............. _ .. -* ....... .-,c;....:,=--------o-l-i-L-...J.-...J.--,--....L--l.-.::::t:::!!:==::r......::..i.:.-.1....---.-.....1...--L.--L.-,--L---L---l-l 500 6500 2500 18500 24500 nme (sec) Figure 9-36 Ksp111 Case 5-Core Inlet and Upper Head Spray Nozzle Flow Rates Compared to Boil-off 9-47 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 702 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 SWITCH OVEI! T IIH D NCOMER PPER HEAD JO-,-,.-------/:--. -_-_,_......,_ .... _-_.,,...,.,,f ___ ,...._~------~--i------.-.-----.,_....., 24 :r---. ' . . . . . . . . rt"* . . . . . . . . . . : . . . . . . . . . . . : . . . . . . . . . . . : . . . . . . . . . . . ti J . . 6 .......................................................... . , ' , . ... .... -... .,,~ *---4 --.. __ .. _ ...... :-. .., ...... -............ ---* .-*---.. --.' o .............. _....__.___,_...__..-.. __ ...._-.-_..__....__.___,._...__.____._~_.___. _ _.__-1 500 6500 2500 8500 Ti e (sec) 24500 30500 Figure 9-37 Ksp11t Case 5 -Downcomer and Upper Head Coll.apsed Liquid Levels 9-48 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 ----, Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 400 200 500 SWITCH OVER TIU[ HOT RO PCT HOT ASSEUBL PCT 6500 2500 18500 nme (sec) 24500 WCAP-17788-P Mark-ups Page 703 of 782 9-49 30500 Figure 9-38 K,put Case 5 -Hot Rod and Hot Assembly Peak Cladding Temperatures *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) I I Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 704 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 9-50 Press re (psi) S 'ITCH O ER Tit.IE -----DEBRIS BED PRESS RE DROP Velocity ( /sec) ---------LO' PO ER INLET LIOUID VELOCIT ----AVERAGE NOH-GUI E TUBE INLET LIO ID VEL CIT ----AVERAGE G IOE T BE INLET LI ID ELOCIT ....--.. *u; a.. ....._.. Cl) ..... <f) (/) Cl) .... a.. 8 0 500 H T ASSEUBL INLET LI UIO VELOCITY 0-25 .... -----... ........................................... 0 6500 12500 18500 n e (sec) moo -0.25 -0..S JO 00 Figure 9-39 Kqu. Case 5 -Debris Bed Pressure Drop and Core Inlet Liquid Velocity *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 705 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Since the partial blockage applied at the time of transfer to sump recirculation was sufficient to fill the downcomer and activate the UHSN, no significant heatups were observed when complete core inlet blockage was applied. This demonstrates the inherent conservatism in tblock* 9-52 The value of the form-loss coefficient applied to simulate partial blockage was iterated upon to deterrnine the maximum value that could be tolerated and maintain the PCT below 800°F. For the range ofECCS flows investigated, it was determined that a constant form-loss coefficient of~~ -4. 75xl<>5 produced acceptable results. In the prototypic system, it is unrealistic to expect all the fibrous and particulate debris to arrive at the core inlet instantaneously. It is expected that the arrival of debris will occur over some finite period of time that is on the order of hours. Since the exact timing of debris arrival is complex and will vary from plant-to-plant, the approach for determining Kmax via application of an instantaneous ramp simplifies the approach by taking the timing of debris arrival out of the solution. Taking this approach inherently leads to a conservative Km .. value. This is demonstrated by comparing Kmu to the final form-losses applied to the Westinghouse upflow plant category Series 3 cases which applied a linear ramp. From Table 8-3, the final form-loss applied to the Series 3 cases was 4xl06, which is almost an order of magnitude higher than the Kmax value determined from the Westinghouse downflow plant category instantaneous cases. The third set of core inlet blockage simulations (Section 9.2.4) examined a scenario in which a gradual build-up of debris was applied at the core inlet. These are considered the most realistic cases relative to how fibrous and particulate debris is expected to arrive at the core inlet; however, these cases do not simulate complete core inlet blockage. The gradual addition of resistance at the core inlet slowly increases the downcomer level and delays the activation of the UHSN AFP. Eventually, the downcomer fills to the UHSN elevation and the upper head floods to the upper guide tube elevation. After this point, flow into the RV is split between the core inlet and the UHSNs and, as the core inlet resistance continues to build, the flow fraction to the UHSNs continues to increase while the flow fraction to the core inlet decreases. From these simulations, the core inlet resistance necessary to activate the UHSN AFP {K,p1;1) was determined to be a strong function of the ECCS flow. Ksp1;1 plotted as a function ofECCS flow rate is provided in Figure 9-3, and the corresponding flow split between the core inlet and the UHSNs (msp1;1) following K,plit is shown in Figure 9-4 . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 706 of 782 WESTINGHOUSE NON-PROPRJETARY CLASS 3 10-l 10 COMBUSTION ENGINEERING DESIGNS In this section, results from the CE plant category are presented and discussed. The range of conditions and case matrix are provided in Section 10. l. Results from the analysis are presented in Section 10.2. This section is broken into several subsections and the material contained in each subsection is summarized as follows:

  • In Section 10.2.1, results from the beginning of the case used to determine Kmax are used to describe the RCS state at the time of transfer to sump recirculation and the arrival of debris. Since all simulations are identical prior to that point in time, the discussion in this section is applicable to all cases. In the simulations, transfer to sump recirculation occurs 20 minutes after the postulated LOCA.
  • In Section 10.2.2, results from the case used to determine tbiock are presented. This case did not apply partial blockage to the core inlet prior to the application of complete core inlet blockage. Complete core inlet blockage was applied instantaneously at time tbiock and was applied uniformly across all core channels.
  • In Section 10.2.3, results from the case used to determine a value for Kmax are presented. This case applies a conservative representation of partial blockage across the core inlet beginning at 1800 seconds (Figure 10-2). The blockage was applied uniformly across all core channels. Complete core inlet blockage was not applied during this case.
  • In Section 10.2.4, results from additional cases used to determine !C.i,i;1 and mspm are presented. For these cases, a linear ramp in resistance was applied uniformly across the core inlet and complete core inlet blockage was not simulated. Since these cases were used to assess the timing of the activation of the BB channel, the build-up of core inlet resistance was applied more slowly compared to the cases used to determine Kmax* As a result, the RCS response to core inlet blockage was much slower in that the downcomer fill rate and the activation of the BB channel occurred over a longer period of time. These simulations are more realistic with regard to the timing at which debris is expected to arrive at the core inlet. Section 10.3 summarizes and discusses the key analysis results. 10.1 RANGE OF CONDITIONS AND CASE MATRIX The simulation matrix used to determine ~lode and Km,x is shown in Table 10-1. For these cases, a maximum BB flow resistance was used. In the table, the loss coefficient column identifies the core inlet losses applied at the designated initiation times to simulate the collection of debris. All cases applied a step change or a timewise ramp to the loss coefficient applied at the core inlet. The core inlet resistances applied for these cases are presented graphically in Figure 10-1 and Figure 10-2. Step changes in loss coefficients are applied over a 60 second interval. In Case 1, a step change from zero to +/-*1411--lx 1020 is applied from ~20,000 to ~20,060 seconds. A ramp of the loss coefficient with time was applied to Case 2 as a conservative representation of debris build-up. For all simulations, the sump recirculation flow rate is applied 1200 seconds after the initiation of the event. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 707 of 782 WESTillGHOUSE NON-PROPRJETARY CLASS 3 10-2 The simulation matrix used to determine K,p1i, and msplio is shown in Table 10-2. For these cases, a HIHHHH!Hl11laximum and medium BB flow resistances was-were used. In the table, the loss coefficient column identifies the core inlet losses applied starting at the designated initiation time and ending at the designated end time. °fef ei.ample, in Case 3a, a liReaf famp efthe less eeefiieieRt at a rate ef 180,000 /Rf is applies staftisg at 1200 seeeRss lifts eRsiHg et 12,000 seeeRss. The eRei:Rg "'eltie ef tlte less eeea:ieieRt is 540,000. Cet11.plete eere inlet eleeltege is Rel applies te these eases. The core inlet resistances applied for these cases are presented graphically in Figure 10-3. The ramp has a slower rate at the beginning of the transient and then a faster rate later to help identify Ksplit more accurately. For all simulations, the sump recirculation flow rate is applied at 1200 seconds after the initiation of the event and continues until Kma.x is reached at 30,000 seconds. Table 10-1 Simulation Matrix for tblock and K... ... -CE Plant Design Sump Recirculation Flow Debris Bed Model Case Rate (gpm/FA) Loss Coefficient Initiation Time (sec) 1 3.;;!8 .j.zj./ll X 1 020 1200 I ~20,000 2 3.18 Figure 10-2 1800 Table 10-2 Simulation Matrix for K,pHt and msplit -CE Plant Design Sump BB Channel Debris Bed Model (Linear Ramp) Case Recirculation Flow K/A2 (ff) Initiation Time End Time (sec) Rate (gpm/FA) Loss Coefficient (sec) 3a 3.;;?8 -a,c Figure 10-3 1200 +;;30,000 3b 7.46 Figure 10-3 1200 +;;30,000 3c 11.+4 Figure 10-3 1200 +;!30,000 3d 3.8 Figure 10-3 1200 30,000 3e 7.6 Figure 10-3 1200 30,000 3f 11.4 .. . Figure 10-3 1200 30,000 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 708 of782 l.2E+20 l.OE+20 2 8.0E+l9 :.: -6.0E+l9 GI ... 8 4.0E+19 2.0E+19 O.OE+oo 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-3 4000 8000 ---------------12000 Time (seconds) 16000 20000 24000 Figure 10-1 Core Inlet Resistance Transient Applied to Case 1 Simulations from CE Analysis 7.00E+06 6.00E 06 5.00E+06 ..-. ..:.. ¥ 4.00E 06 .. .II .5 !! 3.00E+06 8 2.00E+06 l.OOE+06 O.OOE 00 0 2000 4000 6000 Time (sec) 8000 10000 12000 Figure 10-2 Core Inlet Resistance Transient Applied to Case 2 Simulations from CE Analysis *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 ... C QI WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 709 of 782 10-4 :Q S0CX){X)() :t: 8 u 4000000 _, ... QI E 30{X)CX>O QI u 2000CX>O 1000000 0 5000 10000 15000 Time (S) 20000 25000 30000 Figure 10-3 Core Inlet Resistance Transient Applied to Case 3 Simulations from CE Analysis 10.2 RESULTS OF ANALYSIS Key results from the 1:i.Iock and K'°"' simulations are summarized in Table 10-3. From these results, it is concluded that L ICC can be maintained if complete core inlet blockage occurs ~333 minutes (~20,000 sec), or later, after the initiation of the LOCA event. Prior to reaching complete core inlet blockage, a maximum supportable Kn.x value of 6.5xl 06, corresponding to a pressure drop of approximately ~7 psid across the core inlet, is determined to be the limiting value when a uniform resistance is applied that conservatively represents debris build-up (Figure 10-2). Both of these results are based on cases with minimum ECCS recirculation flow and the highest BB resistance. As shown in Section 8 for the Westinghouse upflow plant design, higher ECCS flow rates will fill the downcomer more quickly, leading to more favorable results and the use of the minimum ECCS flow rate bounds the range of recirculation flows expected. With regard to BAPC, all cases demonstrate that, after core inlet blockage, the areak ei,it EJ:H8lity remains si+/-ffisieHtly low susR tflat boron is eventuaJly flushed from the core and concentrations are expected to remain well below the solubility limit. Further, all cases demonstrate that the core mixing patterns are such that the core can be considered weJl-mixed and no localized regions containing higher boron concentration are expected to form. Key results from the K,plit and msplit simulations are summarized in Table 10-4. The Ksplit values shown in the table are used in conjunction with various ECCS sump recirculation flow rates to generate the curve shown in Figure 10-4. The time that Ksp~t occurs is determined by examination of the BB exit flow rate. The time at which the BB exit flow rate becomes positive is defined as the Ksplit time. The transient flow split between the core inlet and BB is shown in Figure 10-5 for the three ECCS recirculation flow rates *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 710 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-5 and two BB resistances investigated. The flow split is defined by Eq. 8-1. For CE plants, muHsN= 0. refJreseRtee as the fraetioR of total EGGS reeireulatioR flow through the BB aReand the parameter msp1i, is then plotted as a function of the core inlet resistance following l<.i,iit* Table 10-3 Summary of Results for tblod< and K,,,.,. -CE Plant Design Time Core Core Inlet Core Inlet Pressure Inlet Loss Average Core Inlet Drop Break Exit Case Resistance Mass Flow Average PCT Applied Coefficient Rate per Velocity across Quality (K) FA Debris Bed ---seconds ---lbm/sec ft/s psid ---OF I l ~20,000 ~lxl020 ~.O ~.O 5.7 Figure 10-<~542 22 I 2 1800 Figure 10-2 G,.l.4JO. I 6 G,009640. 0 I 4.J-7 ~igure <260 10-34 Table 10-4 Summary of Results for K,p111 and m,..11t -CE Plant Design Case Time ofK,..11t K,..Ht ---seconds ---3a ~9840 4.-.~6lH-(l3. 60x l 05 3b 4&4G4480 -l-,i-l*Hli.09xl05 3c ~2720 4.9;*Ht5. 07x l 04 3d 9520 3 33xl05 3e 4200 l.00xl05 3f 2520 4.40xl04 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 711 of782 \71/ESTINGHOUSE NON-PROPRIETARY CLASS 3 10-6 5.!l:+05 f 4.SE+OS 4.!l:+05 a K/A2 =[ ]a,c .t\ K/A2 = --Volume 4 trendline: y = 6.416E6*powlx,-2.012) 3.SE+OS 3.!l:+05 'i 2.SE+OS )! l.ll:+l'-> 1.SE+OS l.!l:+OS 5.!l:+04 O.!l:+00 T 0 5 10 15 20 25 30 ECCS Flow Rate (1pm/FA) Figure 10-4 Klflil as a Function ofECCS Recirculation Flow Rate from CE Analysis *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 712 of782 0.9 .. i 0.8 Ill :::,. .. 5 0.7 Ill To 0.6 .. 0.5 .. i ii: 0.4 e .... '15 0.3 g i 0.2 .. .... 0.1 0 0 a) 0.9 .. i 0.8

  • a, :::,. .. 0.7 5 Ill f. 0.6 I of; 0.5 ! ! ;;:: 0.4 0 u .... 0.3 '15 g 0.2 i .. .... 0.1 0 0 b) WESTINGHOUSE NON-ffi.OPRIETARY CLASS 3 1000000 2000000 BB Resi sta1ce KIA~= ( 1000000 2000000 BB Resistance KIA~= [ --Volume 4 bound: y=0.075 ln(x)-0.45 : ~[bound: y=0.131]nlt/*53
  • K/A2-3000000 4000000 5000000 K
  • Ksplit -Volume 4 bound: y=0.07Sln(x)-0.45 ~~;r[bound: y-0.131]n~.'c1.48 I K/A2-* K/A2-3000000 4000000 5000000 K-Ksplit ] tr4 10-7 Figure 10-5 Fraction ofECCS Recirculation flow through the BB following K.,w frcm CE Analysis *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 713 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-8 10.2.1 All Cases -Before Debris Introduction The results from Case 2 (up to 1200 seconds) are used to describe the RCS state at the point of transfer to sump recirculation and the arrival of debris. Since all simulations are identical prior to that point in the transient, the discussion in this section is applicable to all cases. In the simulations, transfer to sump recirculation occurs 20 minutes after the postulated LOCA. Just before transfer to sump recirculation, the RCS loop piping and SGs are mostly voided. l11e entire core has quenched and the cladding temperatures are just above saturation temperature as shown in Figure 10-6. The core region is covered with a two-phase mixture and the core collapsed liquid level is reughly siJ! feet iHtenear the top of the active fuel region. Figure 10-7 shows the average core collapsed liquid level (the !lata iH this figure represeftts a ruHruftg ifverage efthe ease data) and Figure 10-8 shows the downcomer average collapsed liquid level. The difference between tile collapsed liquid levels in the downcomer and the inner RV is expected given tile additional two-phase pressure losses in the boiling core. It is also noted that the downcomer collapsed liquid level is well below the cold leg elevation which limits the available driving head at the start of sump recirculation. Figure 10-9 shows a running average of the mass flux at the core inlet for each of the four core channels. Just prior to sump recirculation, all eut the sers psriphsrychannels indicate flow from the LP into the core (i.e., upflow). IH the periphe~* efthe eere, there is tlew frem the sere te the LP. Figure 10-10 shows a running average of the mass flux near the core outlet. All channels except the core periphery indicate flow from the core to the UP. In the periphery of tile core, tllere is flow from tile UP to the core. Figure 10-11 shows a running average of tile flow rate from the UP to tile BB region (the data ift tltis figtt£e represeftts a FHtt."liHg acverage ef the ease data). The figure shows that the top of the BB channel is experiencing flow into the channel from the UP. A running average of :rthe break exit quality is shown in Figure 10-12 (the data in this figure represeftts a fHftriiHg average ef the ease Elata). The figure shows that the nominal break exit quality on the RV side of the break is less than 420% upon transfer to sump recirculation which indicates a substantial amount of liquid carryover out the break. At transfer to sump recirculation, the ECCS liquid temperature is increased, which increases tile break quality. Note tllat tile increase in break quality prior to the tinle of sump recirculation is an artifact of tile running average scheme used during post-processing of tile results. Due to the large amount ofliquid carryover prior to sump recirculation, BAP is controlled and boron concentration levels in tile RV upon entry to sump recirculation are expected to be comparable to the ECCS source concentration . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 0800 800 1000 Tme(s) WCAP-17788-NP Mark-ups Page 714 of782 10-9 1200 Figure 10-6 Case 2 -Hot Assembly Peak Cladding Temperature *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 18 / / 12 -4 800 1000 rime (s) Figure 10-7 Case 2 -Average Core Collapsed Liquid Level WCAP-17788-NP Mark-ups Page 715 of782 10-10 1200 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 20 [7 18 12 8 .. 800 1000 T-($) WCAP-17788-NP Mark-ups Page 716 of782 10-11 1200 Figure 10-8 Case 2 -Downcomer Collapsed Liquid Level *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 717 of782 i J IL I 2 100 50 100 800 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-12 *---+---... -.ca. -~o-remo ----------------. 800 1000 1200 Tme(s) Figure 10-9 Case 2 -Core Inlet Mass Flux *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 718 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-13 501---------4---------4-----------, i -----------J "' j -100 '-----~----'----~----'-----~------' 800 800 1000 1200 1llne (s) Figure 10-10 Case 2 -Core Exit Mass Flux *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 719 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-14 501----------1---------+---------1 I ,;:. 1 IL 0>-----------+---------+----------< *100 ~---~---~---~---~-------~ eoo eoo 1000 1200 T-(s) Figure 10-11 Case 2 -Barrel/Baffle Channel Exit Mass Flow Rate *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPR1ETARY CLASS 3 fo.e I WCAP-17788-NP Mark-ups Page 720 of782 10-15 j 0.4 1----------+---------+--------I 0.2 0.0800 800 1000 1200 T-(s) Figure 10-12 Case 2 -Break Exit Quality *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10.2.2 After Debris Introduction -Calculation ofti,1ock WCAP-17788-NP Mark-ups Page 721 of 782 10-16 Case 1 is used to determine lblock* This case does not apply any partial blockage to the core inlet prior to the application of complete core inlet blockage. Throughout the duration of the transient, more-than-adequate core cooling flow is provided through the ECCS to the cold legs. Complete core inlet blockage is applied at~333 min (-1420,000 seconds). After this time, coolant from the ECCS backs-up and fills the downcomer until adequate driving head is achieved such that flow can be provided to the core via the exit of the BB channel. Figure 10-13 shows that ae--a temperature excursion occurs after the application of complete core inlet blockage, resulting in a PCT of 542'F. wm4This result indicates that the delay time associated with filling the downcomer (to provide adequate driving head such that coolant can flow ~ough the BB channel to the top of the core) is short enough to ensure that the eefe sees aet ttaeeYefacceptance criterion of 800'F is not exceeded. Once the BB channel is active in providing coolant to the top of the core, the two-phase mixture level in the core recoverseeatlattes te Ile and resides above the heated core for the remainder of the transient. The RV fluid mass is shown in Figure 10-14 (!he aata ia this figttre reflreseals a RHrning average efthe ease aata). The average channel collapsed liquid level is shown in Figure 10-15 (the data in this figure represents a running average of the case data). When complete core inlet blockage is applied, the RV inventory increases quickly, which can be attributed to the downcomer filling. At the same time, the average channel collapsed liquid level decreases, which reflects the lack of flow to the core to make up for boil-off. Once the downcomer fills and the BB channel becomes an active flow path, the RV fluid mass eventually stabilizes and reffiaias iilidy eeHslaHI fer !he reffiaiHaeFthen builds slowly towards the end of the transient. Similarly, the average channel collapsed liquid level recovers and remains fairly constant for the remainder of the transient. The collapsed liquid levels in the other core channels show similar trends. The downcomer collapsed liquid level is shown in Figure 10-16. When the blockage is applied, the downcomer collapsed liquid level quickly increases due to the blockage at the core inlet. As a result, the BB channel is filled with coolant and flow through the channel provides coolant to the top of the core. The core inlet mass flow rate and the BB exit flow rate are compared to 12Q flereeHI efthe boil-off in Figure 10-17 and Figure 10-18, respectively (the data in these figures for the core inlet flow and BB exit flow represents a running average of the case data). Figure 10-17 indicates that flow into the core is welt in excess of boil-off prior to the application of complete core inlet blockage. After the blockage is applied, flow through the core inlet ceases and flow in excess of boil-off from the BB exit enters the top of the core and provides coolant for DHR. The majority of the flow that exits the BB flows into the peripheral core channel and the flow direction is predominately downward. Figure 10-19 shows the integrated mass flow rate near the top of the core and Figure 10-20 shows the integrated mass flow rate near the bottom of the core. These plots indicate that the flow of liquid is predominately downward along the entire length of the peripheral core channel. With the bulk of the liquid exiting the BB channel and flowing downward in the periphery of the core, cross flow provides liquid to the average channels and hot assembly channel. This behavior is illustrated in Figure 10-21, which shows the integrated mass flow rate from the central core to the average core near the top of the core. The negative slope in the figure indicates that flow is going into the central core from *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 722 of 782 10-17 the average assembly channel. Similar cross flows are observed from the peripheral channel into the average channels along the entire axial elevation of the core. The break exit quality is shown in Figure 10-22 (the data in this figure represents a running average of the case data). This figure shows that, prior to the application of complete core inlet blockage, the quality remains around MO%. After the application of blockage, the case shows a spike in the break quality, which quickly recovers and trends downwards thereafter. The spike is due to the reduction in core flow rate, which decreases the core heat removal and core collapsed liquid level as shown in Figure 10-15. Due to the large amount ofliquid carryover out the break before and after complete core inlet blockage, BAP is controlled and boron concentrations in the RV will remain well below the solubility limit for the duration of the transient. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0
  • I! J 800 I 1 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10000 15000 T-(a) 20000 WCAP-17788-NP Mark-ups Page 723 of 782 10-18 25000 Figure 10-13 Case 1 -Hot Assembly Peak Cladding Temperature *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 150000 I ,} .. , .. n...,.r ,M ,.J,. J .1, .. ,~ .~ .. 1. .,.'II' ..., ... * *-'I' " ........ ,.,, .*,r**ll' 100000 WCAP-17788-NP Mark-ups Page 724 of 782 10-19 p~ 10000 1Sl00 Tille(s) 20000 29000 Figure 10-14 Case 1-Reactor Vessel Fluid Mass *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 725 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 I 0-20 18 I I I I I ' I I I ' I I I ' I I 12 I I ' I I I I I ' V 4 I I I I I I I ' I _,,,.,.,. 10000 15000 rme(s) ..._. . LL IIL-l .i ... ,~ u 20000 Figure 10-15 Case 1-Average Core Collapsed Liquid Level A -"Y" 30000 ... This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 726 of 782 g ] I WESTINGHOUSE NON-PROPRIETARY CLASS 3 30------------------------~ 2IO 10 r ' 10000 1'1000 Tn(s} I I I I -**-0 .... 2 ---* -..e.-, 20000 29000 Figure 10-16 Case 1-Downcomer Collapsed Liquid Level 10-21 ... This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 727 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-22 1000 I I ' I I ' 800 I I ' I I 800 ' I i I I I 200 J._~ 0 -200 -800 -1000 0 ' I I ' I I I I I ' I I I I I ' I I I I I I I I I ' I I I ' I Kl " ** ., I J
  • l 10000 w~
  • UIOOO Time (s) -c..--1 ---' 11 20000 Figure 10-17 Case 1-Core Inlet Flow Rate Compared to Boil-off -30000 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 728 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-23 800 I~ J J IL 0 -200 0 I I I I I ' I I I ' I I ' ' I I I I I ' I I I I I I ' I I I ' I I ' I I ' I I I 1'-. ' I I ' \:./--I l'W' ,. ' I I I I I I ' I I I ' I 10000 ---15000 rrne (s) -----1 ---~* ... 30000 Figure 10-18 Case 1 -Barrel/Baffle Channel Exit Flow Rate Compared to Boil-off *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 729 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-24 3.0Mrr I I I .; I I ~I ' ., I ,* I I ,-E)Hot___,(11.Mtl) I ,If r-*O-Conl ('11.U~ I r -~AIIINOtC-(1L,.~ V --r. ........... c-,11.1u11 I .r** 1# * . 1.0e+07 .,,, .6 ....... V I O.o.+oo I ,-I I ,. ", I -~-*' .~, .... : ---~ -.... I ' I ' ' , ...... I r-,..._ I ', I ' '""' I , ... I ........ ' ,, I I *, ' I ... I ,, I ' *, I ' -1.o.+<17 I -.... I ' I ' I ' I I I ' I -3.oe+o7 0 10000 15000 30000 nme (s) Figure 10-19 Case 1-Integrated Flow Rate Near the Top of the Core *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 730 of 782 i I WESTINGHOUSE NON-PROPRJETARY CLASS 3 4,oe,.()7 ~-, --~-----------------~--~ I ' I : ~,.,. I .~*~ 3.o.+()7' t-;:c' :::;:;:;:;::;:::+/-::;:;:::;::::;:;;;:=,t-----r----t---:..Mr'----, l~Hol~(1ST1' I V' ,--a-Cooo(U7'! _,.._ .. C-(1.97111 ' I ,. -*AIIIIIOtC.(1.-rt) ./ ~0e-t011---' ----+----+-----~16~*----+---~1----------1 .. I I .* I .,., I / I Jf'J I I ' 1JJe+<IT I *" I -' ' i,* : ,,* I _J:' ' Jf' --0.o.+-00 .... d -*1.o.+<l7' ' -... : , ......... : : ,_ -2.o.+<17' 1--'-, ----+----+------+---""'r----+-----11----------1 I ,, I ' I I I ~.o.+<17' I I ' I I I ' I -4.0e-+(JT 0 10000 1eoocl rme(*) ... 20000 , ... ....... ....... 2IIOOO ......... . ..., 30000 Figure 10-20 Case 1 -Integrated Flow Rate Near the Bottom or the Core 10-25 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 --C..lo e e -20000 I -40000 WCAP-17788-NP Mark-ups Page 731 of 782 10-26 -<<>000 t--....._--+-----+-----t----+----++-----t -80000 0 10000 15000 rme(s) 2000CI 25000 30000 Figure 10-21 Case 1-Cross Flow from Central Core to Average Core Near the Top of the Core *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 1.0 OJI 0..2 I r ., I ,/, ~. ' t* I I I I 'I I I r I ;, !, I ,. ,: , . j I I I I I I I I I I I I I I ' I I I I ' I I I ' I I ' ' I I ' I I I ' I ' L ,-Hal .... ----, --BHal'----113-' ( ' 10000 18000 rme(s) *' ~: ... I t1 :, ,* i Figure 10-22 Case 1-Break Exit Quality I I I I I I I I I I I -. -" 11 J t I WCAP-17788-NP Mark-ups Page 732 of782 10-27 I I , , : I , I I I I I I I -I , ' I I I I I ' I I I '* ~* .. r 30000 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * * ~------------------*------------------------------------------------~ * *

  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTillGHOUSE NO -PROPRIETARY CLASS 3 10.2.3 After Debris Introduction -Calculation of Kmax WCAP-17788-NP Mark-ups Page 733 of 782 10-28 Case 2 is used to determine a value for Kmu* This case applies a ramped blockage to the core inlet beginning at 1800 seconds (Figure 10-2). lnroughout the duration of the transient, more-than-adequate core cooling flow is provided through the ECCS to the cold legs. After the blockage is applied, the RCS response is very similar to the response seen after complete core inlet blockage (as described in Section 10.2.2), except that flow continues through the core inlet at a reduced rate. Coolant from the ECCS backs-up and fills the downcomer until adequate driving head is achieved such that flow through the BB channel begins. From this point forward, the total flow entering the LP is split between the core inlet and the BB channel. Figure 10-23 shows that the core did not experience a temperature excursion after the application of the core inlet blockage. DHR is maintained by a combination of flow through the core inlet and flow through the BB channel to the top of the core. The RV fluid mass is shown in Figure 10-24 (tRe Elata ia this Hg~mi reiiresilRts a FYR.'lifl.§ a>,*@n1ge eftRil ease Elata). As the core inlet blockage is applied, the RV inventory increases, which can be credited to filling of downcomer. Once the downcomer fills and the BB channel becomes an active flow path, the RV fluid mass eventually stabilizes for the middle portion of the transient and remaiHs fairly 68RstaRtthen increases near the end for the remainder of the transient as the DH decreases. These trends are consistent with the behavior of the average channel core collapsed liquid level as shown in Figure 10-25 (the data in this figure represents a running average of the case data). The collapsed liquid levels in the other core channels show similar trends. The downcomer collapsed liquid levels are shown in Figure 10-26. When the blockage is applied, the downcomer collapsed liquid level quickly increases due to the increased resistance to flow through the core inlet. As a result, the BB channel is filled with coolant and flow through the channel provides coolant to the top of the core. The core inlet mass flow rate and the BB exit flow rate are compared to 12G iierseRI efthe boil-off in Figure 10-27 and Figure 10-28, respectively (the data in these figures for the core inlet flow and BB channel exit flow represents a running average of the case data). These figures indicate that flow into the core exceeds boil-off after the application of core inlet blockage. Figure 10-29 shows the pressure drop across the debris bed (the data in this figure for the core pressure drop represents a running average of the case data), and Figure 10-30 shows the core inlet liquid velocities (the data in this figure represents a running average of the case data). These figures confirm that flow through the core inlet continues after the application of the blockage. The majority of the flow that exits the BB flows into the peripheral core channel and the flow direction is predominately downward. Figure 10-31 shows the integrated mass flow rate near the top of the core and Figure 10-32 shows the integrated mass flow rate near the bottom of the core. These plots indicate that the flow of liquid is predominately downward along the entire length of the peripheral core channel. With the bulk of the liquid exiting the BB channel and flowing downward in the periphery of the core, cross flow provides liquid to the average channels and hot assembly channel. This behavior is illustrated in Figure 10-33, which shows the integrated mass flow rate from the central core to the average core near the top of the core. The negative slope in the figure indicates that flow is going into the central core from *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRlETARY CLASS 3 WCAP-17788-NP Mark-ups Page 734 of 782 10-29 the average assembly channel. Similar cross flows are observed from the peripheral channel into the average channels along the entire axial elevation of the core. The break exit quality is shown in Figure 10-34 (the data in this figure represents a running average of the case data). After the application of the blockage, the case shows an increase in the break quality which stabilizes f!eaF 7Sll~t or below 60%. Due to the large amount of liquid carryover out the break during the transient, BAP is controlled and boron concentrations in the RV wiU remain well below the solubility limit. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-I 7-102, Revision 0 WCAP-I 7788-NP Mark-ups Page 735 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 e J .. -~--1-----1----.-1-----1-----l-------l :s C. I -400 tt-.,..----;------+----+-----+------11-------t 10000 15000 Time (s) .. 20000 Figure 10-23 Case 2 -Hot Assembly Peak Cladding Temperature 30000 10-30 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 200000 100000 WESTINGHOUSE NON-PROPRIETARY CLASS 3 'r ............. I r -.,,.... rr I I I I I I I I I 10000 -I l ,.. * * ... T I" ".,,,. ... ,. *,r-,, 1!IOOO Tune (a) 20000 * ,.J.I l .,. Figure 10-24 Case 2 -Reactor Vessel Fluid Mass WCAP-17788-NP Mark-ups Page 736 of 782 10-31 'P 30000 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 737 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-32 ],--~+-~-+-~-+-~-+-~-+-~~ I ... 0 .__..___ __ __._ ___ _,__ ___ __. ____ ...___~ _ _._ ___ __. 0 5000 10000 15000 20000 26000 30000 Tm,(s) Figure 10-25 Case 2 -Average Core Collapsed Liquid Level *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY LASS 3 WCAP-17788-NP Mark-ups Page 738 of782 10-33 3(),-----~-----.-----.-----~-----.----~ ] ! 20 10 00 10000 1!5000 11me (I) ---*C-Z --*-* --1!>-4 20000 Figure 10-26 Case 2 -Down comer Collapsed Liquid Le,*els 30000 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 739 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-34 1000 I I I I I I BOO I I I II I eoo I I I 200 d I 0 I ' ' I ' ' I I -200 ' I I I I I ' I ' ' I ' I I I ' I I -800 ' I I ' ' -1000 0 --,-10000 ~I\ A ,~ rime <a> --...,...,-,-1 ---20000 Figure 10-27 Case 2-Core Inlet Flow Rate Compared to Boil-off 30000 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 740 of782 eoo j l 200 s J II. 0 -200 WESTINGHOUSE NON-PROPRIETARY CLASS 3 I ' I ' ' I I ' ' I ----1 I _ ..... _ I I I ' I ' ' I ' ' I I ' I I I I I I ' I ' ' I ' ' I I .. I -..,...,... I ~-' ' I I rv I I ' I I I ' I I ' I I ' ' 0 6000 10000 16000 20000 26000 30000 Time(s) Figure 10-28 Case 2 -Barrel/Baffle Channel Exit Flow Rate Compared to Boil-off 10-35 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-I 7-I 02, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10000 15000 Tane(s) 20000 Figure 10-29 Case 2 -Pressure Drop across Debris Bed WCAP-I 7788-NP Mark-ups Page 741 of 782 10-36 300QO *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 742 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-37 O.!O 0.00 -1.00 -1.50 0 I I I I I I I l .a I * --' I I : V I I I I I I ' I I ' I I I ' I I I I I I ' I I ' I I I I I I ' I I I I I ' ' 10000 _.... 15000 Tl'lle (s) ::::..--=J --.. --c.. -~ ........... 0-20000 25000 Figure 10-30 Case 2 -Core Inlet Liquid Velocities 30000 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WESTINGHOUSE NO -PROPR1ETARY CLASS 3 I ' I ' ' I I ' 2.0e+07 H (11.14_1' I r***DC>Mnl0.(11.M .. r -Aw111910.(11,M1' I /' _"6 .......... C...111.141'1 I ' I I _, ' ' .,; ' 1.0e+07 ' ** r' ' ' /.~ I ' ' I ,r*-> I I r O.Oet<lO I ' I -.... ;*-* .. -.1---' ~""!I..., ' ..... ' ,, ' '-, ' ' ... &.. I ' ' ' ,, ' ' ' ~, -1.0e+07 I ' ' ........ ' .... I ' -. ... ' '~ I ' ' '.to.. I ' ' ' ' ' I I ' ' -3.0e+07 0 10000 UiOOO llrne(I) 20000 WCAP-17788-NP Mark-ups Page 743 of782 I 0-38 _,. -, ,.if ,, .... ' ' , .. 30000 Figure 10-31 Case 2 -Integrated Flow Rate ear the Top of the Core *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 744 of782 I j WESTINGHOUSE NON-PROPRIETARY CLASS 3 ... ()eo()'7 ~---~----~---~----~---~---~ 2.o.+o7 1.o.+o7 .,;" ,* ,* * ,* # . .... o.o.+oo ' ......... ..... .... , -1.o.+<17 -2.o.+()7 ** ** ' ** ** ', ** *" ... -3.o.oo7 ~~---l------+----1-----4------4------l .... .o.+<17 0 IIOOCI 10000 15000 llme(I) 20000 Figure 10-32 Case 2 -Integrated Flow Rat.e Near the Bottom of the Core 30000 10-39 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 1 ~000 I :::E -10000 -IOOOO 0 10000 20000 WCAP-17788-NP Mark-ups Page 745 of782 10-40 30000 Figure 10-33 Case 2 -Cross Flow from Central Core to Average Core Near the Top of the Core -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE ON-PROPRIETARY CLASS 3 ' I I I I I I I I I I .o., ....... +---+, a I I I ' I iu----~--~-1&4&ff-lA-+++++--.H--.-. IIOOCI 10000 1!5000 lane (I) 20000 Figure 10-34 Case 2 -Break E~;t Quality WCAP-17788-NP Mark-ups Page 746 of782 10-41 30000 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10.2.4 After Debris Introduction -Calculation of Kspm and mspm WCAP-17788-NP Mark-ups Page 747 of782 10-42 +hre&--Six additional cases were run to determine Ksplit and m,piit* For these cases, a piecewise linear ramp in resistance was applied at the core inlet (Figure 10-3) and complete core inlet blockage was not simulated. Since these cases were used to assess the timing of the activation of the BB channel, the up of core inlet resistance was applied more slowly compared to the cases used lo determine Km,x* As a result, the RCS response to core inlet blockage was much slower in that the downcomer fill rate and the activation of the BB channel occurred over a longer period of time. It is noted that these simulations are more realistic with regard to the timing at which debris is expected to anive at the core inlet. Even though thre&-six simulations were completed to cover the full range ofECCS flows expected during sump recirculation, only the mid-flow case with high BB resistance is discussed in this section. Similar trends were observed in the ~ases not discussed. Select transient plots from Case 3b are shown in Figures 10-35 through 10-40. The RCS response to core inlet blockage was expected and is generally consistent with the transient response discussed in Section 10.2.3. Figure 10-35 and Figure 10-36 show the core inlet flow rate and BB exit flow rate compared to 120 psFGeflt afof the core boil-off rate, respectively (the data in these figures for the core inlet flow and BB exit flow represents a running average of the case data). 111e figures demonstrate that flow to the core is well above boil-off during the entire transient. The flaw respalliie ta Gare inlet blaskage is alsa shaws ey the figure. As core inlet blockage is applied, the pressure drop across the core inlet increases. Once K,p1;, is reached, the BB exit flow rate becomes positive and increases as the magnitude of core inlet blockage increases. As a result, the core inlet flow rate decreases consistent with the rate that the BB flow rate increases. Figure 10-37 shows the transient downcomer collapsed liquid levels. As core inlet blockage is applied, the downcomer collapsed liquid level increases as expected. When Ksp1;1 is reached, the BB channel is completely flooded. As core inlet blockage continues to increase, the downcomer continues to flood and eventually fills. The PCT transient is shown in Figure 10-38. The figure indicates that the PCT remains well below 800°F and the lack of any significant heatups indicates that the core never uncovers after application of core inlet resistance. Figure 10-39 and Figure 10-40 (the data in HH-sthese figures represents a running average of the case data) a110 Figllfe 10 40 show the pressure drop across the core inlet and the core inlet liquid velocity, respectively. As expected, the core inlet velocity decreases as the pressure drop across the simulated debris bed increases . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 748 of782 u Q) E ..0 = Q) 1ii a:: ::: ..Q u.. 1000 800 600 400 200 0 -200 -400 -600 -800 -1000 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 -Core lntet Flow --+ Bollotl' Rate 5000 10000 15000 20000 25000 30000 Time (s) Figure 10-35 K.,11t Case 3b-Core Inlet Flow Rates Compared to Boil-off 10-43 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 749 of782 0 E .c = Q) iii 0:: 3: 0 u::: 600 500 400 300 200 100 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 1-Baffle Exit Flow I __. Bollorr Rate -100 0 5000 10000 15000 20000 25000 30000 Time (s) Figure 10-36 K.i,nt Case 3b-Barrel/Ba fie Exit Flow Rates Com pared to Boil-off 10-44 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 750 of782 g <ii > j "C *5 0-:.:::i WESTINGHOUSE NON-PROPRIETARY CLASS 3 20 -Sedor1 --..e:t Sedor 2 --~ Sedor3 -~Sedor4 --Averaae 10 0 L-.~~ .......... ~~~'---'-~~~-'--~~~-'-~~~-'-----"~~..........J 0 5000 10000 15000 Time (s) 20000 25000 30000 Figure 10-37 K.,111 Case 3b-Downcomer Collapsed Liquid Levels 10-45 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-P Mark-ups Page 751 of782 G:' 'L, .a 8.. E Cl> f-£ 0 a.. .s:::. (/) Cl> ::i? WESTINGHOUSE NON-PROPRIETARY CLASS 3 1200 800 400 0 ._.._~~-'-~~~-'--'~~-'--'~~~--'----~~~..._,.~~.,_, 0 5000 10000 15000 20000 25000 30000 Time (s) Figure 10-38 K.6, Case 3b HatAssemhly Peak Cladding Temperature 10-46 -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WESTINGHOUSE NOl\-PROPRIETARY CLASS 3 16 4 WCAP-17788-NP Mark-ups Page 752 of782 10-47 5000 10000 15000 20000 25000 30000 Time (s) Figure 10-39 K,,lit Case 3b -Pressure Drop across Debris Bed -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 U) E, *u 0 0.00 -o -0.50 *s 0-:.::i C 0 n C :::, --:, -1.00 WESTINGHOUSE NON-PROPRIETARY CLASS 3 ------11 Hot Assembty -----------Central Core ---A Average Core ------<Ill Peri heral Core -1.50 WCAP-17788-NP Mark-ups Page 753 of782 10-48 0 5000 10000 15000 Time (s) 20000 25000 30000 Figure I 0-40 K.,u, Case 3b -Core Inlet Liquid Velocities *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 10.3 DISCUSSION OF RESULTS WCAP-17788-NP Mark-ups Page 754 of782 10-49 During the first 20 minutes of the transient (before debris arrives), the core region has completely reflooded and the cladding temperatures are just above the saturation temperature. The core is boiling vigorously and the core average void fraction is approximately 50%. The downcomer is filling with coolant supplied to the cold legs via the ECCS. At 20 minutes, the downcomer collapsed liquid level is ~below the cold leg elevation. Similarly, the BB is not liquid solid and is filling with liquid supplied from the UP region. There is a strong recirculation pattern within the core region in which the hot and average assemblies have predominately upflow while the peripheral assemblies have downflow. Vapor generated in the core flows toward the break and liquid carryover to the break is significant. The first core inlet blockage simulation (Section 10.2.2) examined a scenario in which the core inlet was instantaneously completely blocked at some finite time after transfer to sump recirculation by applying a large form-loss coefficient at the core inlet. For this scenario, no partial blockage is applied prior to applying complete core inlet blockage. These simulations showed that the application of an instantaneous complete core inlet blockage resulted in fie-a heatup within the core with a resulting PCT of 542'F. When the blockage was applied, flow through the core inlet ceased and the ECCS began to fill the downcomer. Eventually, the downcomer liquid level reached a point where the driving head was sufficient to push coolant through the BB channel to the top of the core. Tiris process resulted in recovery of the core phase mixture level and return of the cladding temperatures to values near the saturation temperature. A lower ECCS flow rate resulted in a longer time to fill the downcomer and increase the driving head to a value high enough to push flow through the BB channel to the top of the core. It was determined that complete blockage of the core inlet had to be delayed until at least ~333 minutes after the postulated LOCA to maintain a secondary heatup ofless than 800°F. It is recognized that the complete core inlet blockage scenario used to determine li,1oc1< is unrealistic relative to the prototypic system. In reality, the arrival of fibrous and particulate debris to the core inlet prior to the formation of chemical products will create a lower resistance partial blockage well before the core inlet is expected to block completely. The resulting partial blockage will aid in filling the downcomer and activating the BB channel prior to reaching complete core inlet blockage. Higher ECCS flow rates would also fill the downcomer faster and generate an earlier time that complete core inlet blockage could be tolerated. The second core inlet blockage simulation (Section 10.2.3) applied a ramped blockage to the core inlet beginning at 1800 seconds. The magnitude of the form-loss coefficient was such that flow through the core inlet is reduced but not stopped completely. The RCS response to the partial blockage was very similar to the response after complete core inlet blockage, other than the fact that flow through the core inlet continued. No signifieaat heatups were observed in this case. The value of the form-loss coefficient applied to simulate partial blockage was iterated upon to determine the maximum value that could be tolerated and maintain the PCT below 800°F. For the minimum ECCS flow, it was determined that a constant form-loss coefficient of 6.5x106 produced acceptable results. Similar to the Westinghouse cases discussed in Section 8, as ECCS flow increases, this value is expected to increase. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 755 of782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 11-1 11 BABCOCK AND WILCOX DESIGNS In this section, results from the B& W plant category are presented and discussed. The range of conditions and case matrix are provided in Section 11.1. Results from the analysis are presented in Section 11.2. This section is broken into several subsections and the material contained in each subsection is summarized as follows:
  • In Section 11.2.1, results from the beginning of the case used to determine t1i1odc and Kmax are used to describe the RCS state at the time of transfer to sump recirculation and the arrival of debris. Since all simulations are identical prior to reaching sump recirculation, the discussion in this section is applicable to all cases. In the simulations, transfer to sump recirculation occurs 20 minutes after the postulated LOCA.
  • In Section 11.2.2, results from the case used to determine lt,1ock and Km,x are presented. Since the B&W plant category can meet the acceptance criteria with complete core inlet blockage applied at sump switchover, only one case is needed for both parameters. For this case, complete core inlet blockage was applied instantaneously and was applied uniformly across all core channels.
  • In Section 11.2.3, Fes11lls frem aaailieRal eases 11sea ts determineation of appropriate values for Ksp1;1 and msp1;1 are presented. Fer tkese eases, a linear fllfflll it1. resist1111.ee was Elflf!li:ea llflifafffll".,* aeress the eere ifllet aRa esmf!lete eere iIHet eleelrnge was Rat simttlatea. £iRee tkese eases were MS ea ts assess the timiRg sf the aeti,*atiet1. sf tke BB ekaflfl.el, the ettila llfl efeere inlet resistftfl.ee was appliea men slewly sem.parsa te the sases ttSea le aeli!FHliae K....,.. As a resYlt, thi! RC£ n,speasil te seril iRlilt eleskagil was Hn1sk slewilr ia that tkil aewasem.ilr iiJI ratil aaa tl~il asti,*atiea eftke RB shaRflel ess11rrsa ovsr a !eager periea eftim.e. It is Retea IRal thsse sifffillatieHS are mere realistie wilR regard ts the timiag at whisk aeeris is e?ipestea te arri'>'e at the 60FB iruet. Section 11.3 summarizes and discusses the key analysis results. 11.1 RANGE OF CONDITIONS AND CASE MATRIX The simulation matrix used to determine tblodc and K.nax is shown in Table 11-1. Since all BB designs for the B& W plants are effectively the same, the BB flow resistance was not changed. In the table, the loss coefficient column identifies the core inlet losses applied at the designated initiation times to simulate the collection of debris. All cases applied a step change to the loss coefficient applied at the core inlet. The core inlet resistances applied for these cases are presented graphically in Figure 11-1. The sump recirculation flow rate is applied 1200 seconds after the initiation of the event for all simulations. Thi! siFR11latieR matr'Ji llSilaAs discussed in Section 11.2.3, simulations to determine K,.pli, and msplit ts skewa ia Taele 11 2are not required, and no case matrix is provided. £iRss all sf the RB aesigfl!l fer the "B&W plaats aril tRil saFRil, tRil :g:g flew Hsistaasil was aet shaflgila. la tRil taelil, tRil less seil:ffisiilat eel11fflR iaeatiiies tke sere iRlst lessss applied startiag at the assigaatea iailiatieR tims aRa sadiag at ths desigaated ead time. Fer exafflllle, ia Cass 2a, a timewise liRear FaHlp sf the less sesffisiilftt at a rate sf 6000 !hr is applied startiRg at 1200 seseaas aRa eRding at 12,000 sseeRas. The saaiRg ,*al11e 0f ths less sesffisieat is 18,000. Cem.pli!te sere illlet eleekage is aet apf!lied t0 these eases. The ears iIHst *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 756 of782 WESTJNGHOUSE NON-PROPRIETARY CLASS 3 11-2 FesistaRses aflfllieEi feF these eases aFe flFeseRteEi graflhisally iR FigtiFe 11 2. The SHHlfl FesifstilatieR flew Fate is af!JllieEi at 12QQ seseREis after the iflitiatieR ef the 01,reRt fer all sim.HlatieRS. Table 11-1 Simulation Matrix for tblodt and K....,. -B&W Plant Design Sump Recirculation Flow Debris Bed Model Case Rate (gpm/F A) Loss Coefficient Initiation Time (sec) l +.48.5 lxl08 1200 '.!11hle Bi Sim t1l11tioR M11tPa. fer K.i,.;.-ftftd-m.,p11< B&W Pl11Rt Besign DehFis lleil Moilel fl,iRea1* Ramil} (;ase St11Bp ReeiPet1l11*ioR Flow IRiti11tioR '.IilB e Enil +i1ne boss teeffieient Rate (gpm.lF.-\) 4M-eOOG4iF M eOOG4iF *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 757 of782 1.2E+08 l.OE+08 z 8.0E+07 * :.: .. GI c 6.0E+07
  • 4.0E+07 2.0E+07 O.OE+OO 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 11-3 500 1000 1~0 2000 2~0 3000 3~0 4000 Time (seconds} Figure 11-1 Core Inlet Resistance Transient Applied to Case 1 Simulations from B& W Analysis Figun 11 l CeFe Inlet Resistanee TFansient ,"' .. pplied ta Case l Simulatiens fFem B&W ,\nat,*sis *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 11.2 RESULTS OF ANALYSIS WCAP-17788-NP Mark-ups Page 758 of782 11-4 Key results from the !block and K.n,x simulations are summarized in Table 11-3. Case 1 applies complete core inlet blockage and determines the minimum time that complete blockage can be tolerated. This case is also used to determine the maximum resistance that can be tolerated prior to reaching complete blockage. Based on the results presented in Table 11-3, it is concluded that L TCC can be maintained if complete core inlet blockage occurs 20 minutes (1200 sec), or later, after the initiation of the LOCA event. This case also indicates that complete core inlet blockage can be tolerated at the same time, resulting in a K.nax value of lxl08 across the core inlet when a uniform resistance is applied instantaneously upon entering sump recirculation. These results are based on a the mjRiffl1,1m EGGS reeire1,1lati0H flew case that assumes an ECCS recirculation flow rate that is below the minimum expected but still well in excess of the flow needed to make up for core boil-off. As shewft iH SeelieR 8 fer the '>.'esaH:ghetise flleRt desigR, hHigher ECCS flow rates will increase the margin above the core boil-off rate. fill the eewReemer fflere Efliielt-ly, hiaai-Bg te ff!ere f.p 'eraele ns\ilts aH:eTherefore, the use of the HlffiiHNim conservatively low ECCS flow rate bounds the range of recirculation flows expected. With regard to BAPC, Case 1 demonstrates that, after core inlet blockage, the break exit quality remains sufficiently low such that boron is flushed from the core and concentrations are expected to remain well below the solubility limit. The core can be considered well mixed and no localized regions containing higher boron concentration are expected to form for the reasons discussed in Section 11.2.2. As discussed in Section 11.2.3,Ke)* res1,1lts it-em the K,;i,lil is assumed to be exceeded al 20 minutes ( or the time of sump switchover) and 111,,p1;1 is set to 1.0 for all times after l<.µ;1.sim\ilatieas are SlifflHl.aFi2!ee ifl Tallle 11 1. The~ ,,,al1,1es shewft iR the tallle are tisea iR eeajllftetieft *,11ith the EGGS SWHfl reeire1,1lati0ft flew rates te gefterate the 6lii'\'e shewft ift Figlife 11 1. The time that~ eeetirs is aetermiftea 8)' e1.amiftati0ft efthe BB iruet flew rate. The first timestep iR whieh the BB iruet flew rate beeemes flSsitive is aefiHea as the~ lime. If flew 0seillati0Rs (pesitiYe BB iruel flew fellewea by a rt!'iersal 10 HegatiYe flew) 0ee1,1r, the lime ef is seleetea after the flew 0seillali0Rs stefl afta lhe BB mlet flew remeiRs fl0Siti,.*e. The lfefll!ieRt flew Sfllit betweeR the eere inlet eH:a BB is shewR iR Figttre l l S fflr the sin EGGS reeire1,1leti0R 9ew rates iRYestigetea. The flew Sfllit is ref!reseH:tea es the freetieR ef late! J;GGS reeiretiletieH: flew th::-eligh the BB iRlet flfl.8 is fllettea es e filRelieR efthe eere iH:Jet resisleH:ee F0IJ0wing K..,i;.~ Table 11-3 Summary of Results for ft.1oc1t and K.. .. -B&W Plant Design Time Core Core Inlet Core Inlet Pressure Inlet Loss Average Core Inlet Drop Break El.it Case Resistance Mass Flow Average Volume PCT Applied Coefficient Rate per Velocity across Quality (K) FA Debris Bed ---sec ---lbm/sec ft/s psid ---OF I 1200 lxlCJ8 0.00 0.00 ~1.51 <0.41 <J.+Q230 ote: 1 Pressure drop coincides with the pressure drop needed for the alternate BB flow path. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTJNGHOUSE NON-PROPRIETARY CLASS 3 +el!le ll 4 SUHIIIIIIF enlesulh f81* ~<pll<' :QS.~~* Plent Design tttSe :J:itRe ef~ --:;i,a +4eG ;woo ;id J.+&G WCAP-17788-NP Mark-ups Page 759 of782 11-5 -M+ m 4JOO 9800 Figure 11 J as a Funetion of ECCS Reeireulation Flow Rate fron1 B&W Analysis *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 760 of 782 11-6 I Fig11re 11 4 FraEtiaR afECCS ReEirEYlatiaR Flaw thr011gh the Barrel/Qaffle Inlet fallawing fFaffl B&W AHelysis 11.2.1 All Cases -Before Debris Introduction The results from Case 1 (up to 1200 seconds) are used to describe the RCS state at the point of transfer to sump recirculation and the anival of debris. Sinse all sim11lati0ns are iasntisal prier te that point in the k'aRSient, Ills aiss11ssien in tilis sestien is applisaele te all sases. In the simulations, transfer to sump recirculation occurs 20 minutes (1200 sec) after the postulated LOCA. Further, the ECCS flow rate is minimized for the duration of the transient. As discussed in Section 4.2, this combination of inputs minimizes the RV liquid volume at the time of the imposed blockage and maximizes the potential for core uncovering. In general, the trends of the B&W analysis mimic those seen for the Westinghouse and CE analyses discussed previously. The RCS and core rapidly empties, but the CFTs actuate to refill the core and RV and initiate core quench. The pumped ECCS injection completes the core and RV refill to the hot leg nozzle elevation. Around 400 seconds the RV side break flow is effectively equal to the pumped ECCS injection (Figure 11-6) indicating that the RV has refilled such that a two-phase mixture level covers the core to the elevation of the break. One difference to note betwee~ the B&W analysis and the Westinghouse and CE analyses is the usei, of only two core channels -a hot and an average. When only two channels are modeled, the larger grouping used for the average channel does not provide the same information to show detailed local core flow patterns that are available from the Westinghouse and CE plant model results that have additional core bundles modeled, wilisil leaas te differenses in tile preaistea sere flew patterRS. The limitations ef *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 761 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 usiag this ty!')e afa made! afe Eiiseassea eelaw. However, the flow patterns in the core region are expected to be the same among all of the plant designs. Titis assertion is further discussed in Section 11.2.2. 11-7 Figure 11~7 shows the flow rates from which the flow patterns at the core inlet can be characterized. J1:1t1eti0HS 315 QQTraces 'RV I-IC' and4-M-OO 'RV AC' represent flow from the LP to the hot and average channels, respectively. Prior to 1200 seconds, the flow is positive, indicating flow from the LP into the core (i.e., upflow). Janetiat1 314 Q3Trace 'RV BAF' represents flow from the LP to the BB channel (baffle region). Prior to 1200 seconds, the flow is negative, indicating flow from the BB channel to the LP. Figure 11-68 shows the flow rates from wltich the flow patterns at the core outlet can be characterized. Jaaeti0t1S 347 QQTraces 'RV I-IC' and-447-00 'RV AC' represent flow from tl1e hot and average channels, respectively, to the UP. Prior to 1200 seconds, the flow is positive from the hot channel to the UP, indicating flow out of the core (i.e., upflow). Flow from the average core to the UP is generally positive, but a bit more oscillatory, indicating that flow is generally upward. Titis ~ehavior gives some indication of the limitatiat1challenges of the two-channel model, wltich is discussed further in Section 11.2.2belew. J.afletiat1 4 Se Ql Trace 'RV BAF' represents flow from the BB channel to tile UP. Prior to 1200 seconds, the flow is negative, indicating flow from the UP to tl1e BB (i.e., downflow) . Figure 11-+9 shows the axial flow Jlatlems rates in the BB channel. Up to 1200 seconds, the flow is negative indicating downflow in all junctions in the BB. Figure 11-+9 also shows that the mass flow rate in the BB channel increases as elevation decreases wltich indicates that liquid is entering the BB channel from the core periphery through the LOCA holes. Titis is further illustrated in Figure 11~10, wltich shows the cross flow between the BB channel and the average core channel. .Jaaetiaa 4 52 Q2Trace 'From AF3 to AC-9' is at the lowermost set ofLOCA holes. Frnm apJlrn1'1mately 500 seeaaas ta 1200 seeanas, .ffhe flow direction is positive indicatinged flow from the BB channel to the average core. At the ~pper junctions, tile flow direction is negative during tltis same time period, indicating flow from the average core to the BB channel. The trace 'BAF-4 to AC 12' is slightly positive as some of the downward flow from tl1e upper baffle enters the core though the holes and slots at tltis elevation. Due to the large amount ofliquid carryover out the break prior to and after sump recirculation, BAP is controlled and boron concentration levels in the RV both prior to and aftefl:IJl0fl et1ll)' ta sump recirculation are eNpeet@Ei ta es comparable to the ECCS source concentration. The high internal core and UP mass recirculation rates keep all locations well ntixed and near but slightly above the ECCS source concentration . ... This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Figure 11 /; Flew l'Fen1 Lewer Plenum te Gere Regien WCAP-17788-NP Mark-ups Page 762 of 782 11-8 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Fig11re 11 6 Flew fre11t Care RegieH ta the Upper Ple1n1Ht WCAP-17788-NP Mark-ups Page 763 of 782 11-9 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Fig1ue 11 7 A1tiel Flew iR Berrel/Beffie ClteRRel WCAP-17788-NP Mark-ups Page 764 of782 11-10 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRJETARY CLASS 3 WCAP-17788-NP Mark-ups Page 765 of782 11-11 Fig11re 11 8 Flew frem B11rrel/B11l:i:le ChllHHel ta Care Aver11ge CheHHel *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 11.2.2 After Debris Introduction -Calculation offti1oc1< and Kmax Case 1 is used to detennine both lti1ock and K.n ... WCAP-17788-NP Mark-ups Page 766 of 782 11-12 Throughout the duration of the transient, more-than-adequate core cooling flow is provided through the ECCS to the cold legs. Complete core inlet blockage is applied at 20 min (1200 seconds). After this time, coolant from the ECCS slightly increaseseaeks aad fills the downcomer level as it establishes the elevation head needed to reverse the LP to BB channel flow. The downcomer elevation head allows the full ECCS flow to enternatil adsEJ:uats dri>.*iflg head is aehis,*ed saeh that flew eaa ee provided te the BB channel and then the core via the BB ehaftflel tlH*eagh the first row (i.e., lowest elevation) ofLOCA holes (Figure I 1-10). After 400 seconds, the core mixture level remains continuously in the upper plenum (Figure 11-5). Figure 11-9-2 9fteWSCon.firms that the core experiences no temperature excursions after application of complete core inlet blockage. Due to the low resistance of the BB region and the presence ofLOCA holes beginning approximately halfway up the core, there is l,ittls aslay ifl filliag the aewaeemer te pre0,iide ade{laate driviag head saeh that eeelaRt eaR flew threagh the BB ehar.nel aad iRte the eere regieR threagh the LOGA helesno interruption of the flow rate needed to cool the core. The RV collapsed liquid levels are shown in Figure 11--1-03. When complete core inlet blockage is applied, the downcomer level increases ~lightly until the full ECCS flow has a sufficient elevation head to cause it to flow into, fereiag flew d!f'eagh the BB channel to the first row ofLOCA holes and into the heated core. When complete core inlet blockage is applied, there is sufficient liquid inventory in the UP region to replace boil-off until the BB flow reversestllfflag !he tlele~* lime re{lwetl te iaereese the tle~*aeemer ari,*iag head such that the core never uncovers and no heatups are predicted to occur. The core region collapsed liquid levels are shown in Figure 11-4. After the blockage was imposed, the guide tube channel becomes a dead-end channel that fills with water. The baffle collapsed level decreases initially before recovering as the decay heat decreased. The HC level, which was similar to but slightly below the AC by approximately 2 feet as the lower portion of the core voided without subcooled flow from the lower plenum. The AC level also decreased some, but less than the HC when the blockage was established and warmer ECCS temperatures were imposed. Figure 114-1-7 shows the flow rates from which the patterns at the core inlet can be characterized .

  • Jlmetieas 315 OOTraces 'RV HC' and~'RV AC' represent the flow from the LP to the hot and average channels, respectively. After 1200 seconds, the flow is zero, indicating complete blockage at the core inlet. Jaaetiea 314 03Trace 'RV BAF' represents the flow from the LP to the BB channel. After 1200 seconds, the flow is positive, indicating flow from the LP into the BB (i.e., upflow) up to the first row of LOCA holes. Figure 114,;!,8 shows the flow rates from which the patterns at the core outlet can be characterized. Jaaelieas 3 4 7 OOTraces 'RV HC' and 447-@'RV AC' represent the flow from the hot and average channels, respectively, to the UP. After 1200 seconds, the flow is positive from the hot channel to the UP, indicating flow out of the core (i.e., upflow). The flow from the average core to the UP is generally positive, but a bit more oscillatory, which indicates that flow is generally upward. JaaetieR 4 Se 01 Trace *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *
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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 767 of782 11-13 'RV BAF' represents the flow from the BB channel to the UP. After 1200 seconds, the flow is negative, indicating flow from the UP into the BB. Figure 11-H-9 shows the axial flow ~rates in the BB channel. After 1200 seconds, the flow in this region is mixed. In the lower portion (up to the first row ofLOCA holes), the flow is positive, which indicates upflow in this region. Above the first row of LOCA holes, the flow is negative indicating downflow. Figure 11-140 shows the flow ~rates from the BB channel to the average core. JHaeliea 452 ~Trace 'From BAF-3 to AC-9' aad JHaelim1. 45J Q2 areis the lowermost eeftfleetieasrow ofLOCA holes. After 1200 seconds, the flow direction is positive indicated flow from the BB into the average core. Trace "From BAF-4 to AC-12" is the second row ofLOCA holes. After 1220 seconds, the flow direction starts out negative and eventually changes to positive, but hovers around zero flow. JHRetiea 4 5 4 Q2Traces 'from BAF-5 to AC-15', 'From BAF-6 to AC-17', and 'From BAF-7 to AC-20' are the top rows ofLOCA holes. is tfte thtnljtlftetiea freffl tfte ee*letft. After flf)Jlrenifflatei)' lSQQ seeeatls, tftis flew eeeeffles slightly fl0Siti¥s, iatlieating flew ft=effl. tlls BB iate ths a:verags ehaftflsl. The etftsr These junctions are slightly negative during this same time period, indicating flow from the average core into the BB channel. These results help to confirm the flow patterns shown in Figure 7-2. However, because the RELAPS/MOD2-B&W model only has there is eae limilaliea ef the RELJ'.P5/JvI0D2 B&')l H1.00sl ia that there are ealy two channels in the core region, the flow patterns in the core periphery are not calculated separately so they cannot be confirmed. Tkts laelt efWithout additional spatial resolution the detailed fflaltes it tliffieHlt te f)Fetliet the core flow patterns with aay tletailcannot be definitively shown. However, the average channel flow rates do cycle from generally positive to slightly negative, allowing the ECCS flow entering the BB to reach the core inlet elevation. In this case, the oscillations allow the model to predict global effects without the need for localized effects being modeled separately as they do not play a dominant role in the overall results. Use of other evaluations or considerations (such as those from the WEC or CE results that do model additional core channels) can provide insigl1ts to the localized effects if needed. In this case, the B&W plant models can use these insights to evaluate the expected core flow patterns. In a typical PWR, higher fl0Werfresh fuel assemblies that have the highest power are placed tteftfin the interior regions &eater of the core and along diagonals radiating outward. Slightly lower-power assemblies (e.g., once burned) are placed in a checkerboard pattern around them to help control peaking. The lowest-power assemblies (e.g., once or twice burned) are placed fM!afOn the periphery, adjacent to tile baffle plates with the LOCA hales. This core loading pattern leads to a radial power distribution that can create a temperature or void gradient between the ~nboard assemblies with fhigher-power~ and the periphery (lower-power region) of the core. Following a LOCA in which the reactor coolant pumps are tripped, the core evolves into a boiling pot condition during the LTCC phase of the event. Flow through higher-power assemblies is then ltllel)* te ee upwards, with flow in tile peripheral assemblies being downward. This convection roll, or "chimney effect", is el,peehid te drives both local and4h@ global core flow patterns tllat mix the fluid in the core during the post-LOCA transient. While the B&W plant models do not separate the average channel into other groupings to show this circulation, it physically exists like those shown in PWR analyses with additional fuel channels modeled . *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17788-NP Mark-ups Page 768 of 782 l l-14 There are a number of contributing factors in the analyses that also support the intemal circulation describedaeseFif)tieR giveR aeeve. First, the model shows a definitive downflow in the BB channel prior to core inlet blockage. Given that there is no decay heat in the BB and the proximity of the BB channel to the low-power core peripheral assemblies, it stands to reason that downflow is occurring in the peripheral assemblies. Second, the oscillatory behavior of the average core channel implies that if a third, lowepower channel was included in the model; downflow is likely in that lower-power region (core periphery). This assertion can be confirmed by examining the results of the Westinghouse and CE plant simulations that include four core channels (see Sections 8, 9, & 10). The differences in the physical core region between a B& W-designed plant and a Westinghouse or CE plant are not significant with regard to the boiling mechanisms present. It stands to reason that the core flow patterns observed in the Westinghouse and CE models, with more core channels, are representative of the flow patterns expected in the B&W core. Indeed, these models show upflow in the high-power channel (core center) and downflow in the lower-power channel ( core periphery). The break ~volume quality is shown in Figure 11~1 l. This figure shows that the quality prior to the application of complete core inlet blockage is ei!t>>'HR 4Q aRa eQ!/<eless than 1 %. After the application of blockage, the case shows a spike in the break quality which quickly recovers and stabilizes below 405%. Due to the large amount of liquid carryover out the break before and after complete core inlet blockage, BAP is controlled and boron concentrations in the RV will remain well below the solubility limit for the duration of the transient. *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-I 7-I 02, Revision 0 WCAP-I 7788-NP Mark-ups Page 769 of 782 320 I I I I I I 300 280 u. Cl. E Q) 260 I-,:, ca 0 ai C: C: ca 240 .s::. () 0 I 220 200 180 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 -11.2-12.0ft --*110.4-11.211 --~ 9.8-10.4 ft --.!19.2-9.8 ft --< 8.7-9.2 ft -8.1-8.7 ft --7.5-8.1 ft --* 6.9-7.5 ft .. 400 800 1200 1600 2000 2400 2800 3200 3600 Time (s) Figure 11-92 Hot Channel Peak Cladding Temperatures 11-15 -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 770 of 782 20 10 0 ai > Q) __J "C *:5 .!:! -10 __J "C Q) 1/) a. J!! 0 (.) 30 -40 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 --elPlOYel --e OC level --~M; level --eOAlevel --< UP+UH level 400 800 1200 1600 2000 2400 2800 3200 3600 Time (s) Figure 11~3 Reactor Vessel Collapsed Liquid Levels 11-16 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-P Mark-ups Page 771 of782 ¢: ai > (I) ...J :'Q :::, 24 20 16 WESTINGHOUSE NON-PROPRIETARY CLASS 3 --*)AC Level -*1HCLevel --~ BYP Level --6 BAF Level ---<r---------~---------*---1 .!:! 12 ----------'--------------------! ...J -0 (I) (/) C. .!!! 0 0 TOP OF ACTNE CORE 8 4 --f 0 1-~--~--'--~-L-~--1..-~--'-~-L-.~--'-~~--'---o 400 800 1200 1600 2000 2400 2800 3200 3600 Time (s) Figure 11-4 Core Region Collapsed Liquid Levels 11-17 -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 20 ! -Average Channel I 18 16 14 af 12 > Q) TOP OF ACTIVE CORE -' Q) :5 10 x 8 0 0 6 4 2 Void Cutoff= 0.95, Filter Points= 9 0 '--~----~-'-~--'--~--'-~-'-~--'--~----'--'-----'--~'----' WCAP-17788-NP Mark-ups Page 772 of 782 11-18 0 400 800 1200 1600 2000 2400 2800 3200 3600 Figure 11-5 Core and Upper Plenum Region Mixture Levels *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 773 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 ---e1AHP1Flow -*11BHPIFlow --~ 2A HPI Flow --6 28 HPI Flow 500 --CFTFlow -Break Flow (RV Side) --ti Break Flow (SG/RCP Side) --*LPIFlow -... Total Core ECCS Flow (/) E 400 :Q 0 U:: (/) (/) (tJ 300 (tJ Q) ai oe:s Cl) 0 200 0 UJ 100 0 111--At>,¥ __ ...._ __ .....,_lo'°!!!,..._~----l!;oo-.-',!-~a--A!!P-'""'"~ 0 400 800 1200 1600 2000 2400 2800 3200 3600 Time (s) Figure 11-6 RV Side Break Flow and ECCS Flows 11-19 -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to LTR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 774 of782 "' E :fl 0 u:: "' "' (ll > a:: ... Q) 3 0 _J WESTINGHOUSE NON-PROPRIETARY CLASS 3 5000 4500 -LPDC --*1RVBAF --~RVHC --t!.RVAC --<lRVBYP 4000 3500 3000 2500 2000 ,: 1500 1000 500 0 -500 -1000 a.LJ....__-l.....ll.J..____JLJ.._~IJU-~---'-~~--'--~----'-~~-'--~-'-~----' 0 400 800 1200 1600 2000 2400 2800 3200 3600 Time (s) Figure 11-41-7 Flow from Lower Plenum to Core Region 11-20 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 775 of 782 5000 4500 4000 3500 (/) 3000 E :Q 2500 0 u:: (/) (/) 2000 Ill I > I a:: 1500 Q) Q. Q. ::::, 1000 500 0 -500 -1000 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 --EJUPHOL ---EIRVBAF --(>RVJ.C -~RVHC --RVBYP 400 800 1200 1600 2000 2400 2800 3200 3600 Time (s) Figure 11~ Flow from Core Region to Upper Plenum 11-21 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 776 of 782 f/) E a en Q) -; c:: 0 u:: f/) f/) c,:i .!ll Q) E c,:i ID WESTINGHOUSE NON-PROPRIETARY CLASS 3 1200 -From LP to BAF-3 --*I From BAF-3to BAF-4 --From BAF-4 to BAF-5 --i!> From BAF-5 to BAF-6 800 -- E ::9 ti) Q) iii a:: 0 u:: V> V> <ti V> V> e () Q) E <ti OJ 1200 800 400 0 -400 -800 -1200 0 WESTJNGHOUSE NON-PROPRIETARY CLASS 3 -From BAF-3 to AC-9 --El From BAF-4toAC-12 --E> From BAF-5 to AC-15 --6 From BAF-6 to AC-17 ---.: From BAF-7 to AC-20 400 800 1200 1600 2000 2400 2800 3200 3600 Time (s) Figure 11-140 Flow from Barrel/Bame Channel to Core Average Channel 11-23 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 778 of 782 1.2 1.0 ~0.8 Ill :::, 0 E .=2 ..a = 0.6 :::, CT UJ <I) E ..2 0 > 0.4 0.2 WESTINGHOUSE NON-PROPRIETARY CLASS 3 -Outlet "'1nulus-1 -El Outlet "'1 nulus-2 --~HL-2a 11 I E3 400 800 1200 1600 2000 2400 2800 3200 3600 Time (s) Figure 11-1~1 Break Exit Quality 11-24 *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 11.2.3 After Debris Introduction -Calculation of Kspm and msput WCAP-17788-NP Mark-ups Page 779 of 782 11-25 £et aaailioRal eases were nm lo aeteffilille For these eases, a Hftear ramp iR resislaRee was af!f!liea al the eere iftl.et aRa eemf!lete eere iftlel eleeltage was Rel siml:ll.atea. SiRee these eases were ttsea te assess the limiffg eftke aeli1v'atieR eftke BB eh8llflel, the ellila ttf! efeere iRlet resislllftee was af!f!liea mere slewly eemf!area te the eases ttsea te aetefftlme K,,,.,.. As a resl:ll.t; the RCS resf!eRBe te eere iRlet eleehge was mtteh slew11r iR that tit@ aowReom@r fil,I rat@ aRa tit@ aeti,,atioR oftl~i! :QB eilaflfl@I eee1,1rr11a over a loRger perioa of lime. It is ROtea that these simulatioRs are more realislie with regara to the tim:H1g at whieh aeeris is eKpeetea to arriYe at the sere if11et. E.,*eR though se, simulatioRs were eompletea to sever the :full raRge of ECG£ flows e11peetea auriRg sump resireulalioR, Ofti:)' Case 2a was seleetea for aiseussioR iR this seelioR. Similar treRas were oesef\*ea HI the eases Rel aiseussea. Selest lraRsieRt f!lols frem Case 2a are shewR iR i;:igltfes 11 16 lkrettgh 11 2Q. Thi! RCS F8Sf!eRs8 te eere iRlet eloekage was enpeetea aaa is gsRsraU:)* eoRsistsRt wilh the traasisRI rsspenss aise\!Sssa iR £eelioR 11.2.2. Fig1JFe 11 16 sho,..,s ths flow patterns at the sore iBlet. As the eloskage is appliea, the flew eegiRs to aeerease as the sore iftlet resistaaee iRsreases. GoRs1JFFeRtly, the aowRwara flow from the BB shaRRel to the LP eegiB5 to slow aBa eveRtually re>,*erses as the sore inlet resistaRee iRereases, leaaiRg to flow from the LP iRte the BB ehaRRel (i.e., upflow). Fig1JFe 11 17 shows the flo*N patterns at the sore outlet. As the eloskage is appliea at the sore iBlet, flow at Ike sore outlet is positive from the hot eha1mel to the UP, iRaiealiRg flow eut of the sore (i.e., ttf!flow). The flew frem the average eere te the UP is geRerall:)* f!OSitii,*e, ettt a eit FRore essillatef:)', H1aieatH1g that flew is geReraUy Uf!wara. This flo*.v gins serRe ifl.aisalieR of the lifflitatieR efthe w.*e shaRRel FRoael, whish was aissttssea iR SeelieR 11.2.2. After the eloekage is appliea to the sore iRiet; the :Q:Q tlow is Regalive, H1aiealH1g flew frorR th@ UP lo lhe :Q:Q. Figure ll 18 shows lhe a1tial flow patterns HI the BB ehar.Hel. After lWQ seeoRas, the flow ifl. lms regieR is £RH.ea. Flow iR lhe le*Nsr portioR is f!Osili1,*e, whleh iRaisalss llf!flow. Flow iR the 11pper portioR is Regalive iRaiealiRg aowR:llov,r. Figllfe 11 19 shows the tlow f!alterns frorR Ike B:Q lo the a1,*erage sore. After 12QQ seeeRas, the flo*.¥ is mii,ea ifl. that some of the j11:RstioRS are flowiRg from the sore lo the BB eharuu:11 whereas the olherj11Retions are flowiRg from lh0 BB to the sore. The PCT resf!eMe is she*NR HI Pigttre 11 2Q. The fi.gltf8 iRaieales that l:ke PCT remaiM well eelew 8QQ0P aRa tlte laell efaft:)* sigtlifi.eaRt heatltf!S iRaieales l:kat lhe eere R8*,*er 1tRee>,*ers after the af!f!liealieR ef eere iRlilt nsistaR6il. The baffle K/A2 for the operating B&W plants is less than [ ]'-c from bottom to top. However, the TH analyses show that once the core inlet is blocked, the flow need only traverse the lower grid rib and two fonner plates before it has the opportunity to enter the core via a row ofLOCA holes in the baffle plates (see Section 11.2.2). The Kl A2 for this flow path is less than half of the total for the entire BB region. The TH analyses con.firm that complete core inlet blockage can instantaneously occur 20 minutes after the LOCA without resulting in any core uncovering or core heatup due to the blockage. The flow through this low resistance path is able to rapidly reverse direction to provide continuous decay heat removal even if the core inlet is instantaneously completely blocked. The methodology described in WCAP-17788, Volume 1 for the hot leg break defines the in-vessel fiber limit as the sum of fiber that accumulates at the core inlet and the fiber that reaches the heated region (Volume I, Section 4.1). The core inlet debris limit is defined by fuel assembly testing and ranges from *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-NP Mark-ups Page 780 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 ]"c (Volume 1, Section 6.3). The in-core deb1is limit is limited to [ described in Volume 1, Section 6.4. The total in-vessel fiber limit is further restricted to [ described in Volume 1, Section 6.5.5, Step IO. 11-26 ]'*c as r,c as While it is not possible to completely block the core inlet without any fiber buildup, the parameters provided above and the results of the TH analysis demonstrate the operating B& W plants will all have fiber limits [ re If zero fiber builds at the core inlet, then all of the fiber will transpo11 to the heated core. If any amount of fiber builds up at the core inlet, the total amount of fiber possible in the RV would exceed this value, but the total fiber load in the RV [ J'"c Given the above discussion, it is clear that the fiber limit for the operating B&W plants will be the [ r,c and that Ksp1;1 and msplit are not needed to determine this limit. That is, within the context of the hot leg break methodology described in Volume 1, Ksplit can be assumed to be exceeded at 20 minutes regardless of ECCS flow rate and msplit set to 1.0 for all times after Ksp1;1 occurs. The result will be a fiber limit of [ J"c which is what would be calculated if more reasonable values for Ksp1;1 and msplit were calculated. Figure 11 Hi K.,i;. Case 2tl Fie*/, H'elft Le'fter Ple11ulft te Gere R.egie11 Figure 11 17 Case ltl Flew H"elft Gere RegieR te tke U1111er PleRUIR Figure 11 18 Case 2tl Aliiol Flew iR Borrel/8offle Channel .Fig11r0 11 19 Gose ltl Flew frelR 8arrel/8affle Gkannel te tke A..-enge Gere GkaRRel Figure 11 29 K.,.. Case 211 Hat Ckannel Peal, Clatltling Temperatures *** This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *

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  • Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 11.3 DISCUSSION OF RESULTS WCAP-17788-NP Mark-ups Page 781 of 782 11-27 During the first 20 minutes of the transient (before debris arrives), the core region has completely reflooded and the cladding temperatures are just above the saturation temperature. The core is boiJing vigorously and the core average void fraction is approximately 50%. The downcomer is filling with coolant supplied to the cold legs via the ECCS. At 20 minutes, the downcomer collapsed liquid level is well below the cold leg elevation. There is a strong recirculation pattern within the core region in which the hot and average assemblies have predominately upflow while the peripheral assemblies have downflow. Vapor generated in the core flows toward the break and liquid carryover to the break is significant. The first set of core inJet blockage simulations (Section 11.2.2) examined a scenario in which the core inlet was instantaneously completely blocked coincident with the transfer to sump recirculation by applying a large form-loss coefficient at the core inlet. No cladding heatup was predicted for this scenario. When the blockage was applied, flow through the core inlet ceased and flow through the BB channel quickJy reversed up to the first row ofLOCA holes. Flow through the BB channel was sufficient to replace boil-off and DI-IR was maintained. In the prototypic system, it is unrealistic to expect all the fibrous and particulate debris to arrive al the core inlet instantaneously. It is expected that the arrival of debris will occur over some finite period of time that is on the order of hours. Since the exact timing of debris arrival is complex and will vary from plant-to-plant, the approach for determining lblock and K.nu via application of an instantaneous blockage simplifies the approach by taking the timing of debris arrival out of the solution. Ts@ s@seRa s@t efser@ ifti@t eleskag@ sim11lal:ieRs (lil@stieR 11.~.3) @?iaRliR@a a ss@Rarie iR whisk a graa11al 011ila Hf! ef aeeris was af!f!liea at the sere ifllet. These are sensidered tke mast realistis sases relal:i1,*e te hew Eibreus and J!artisulate debris is e)tf!ested le arriYe at the sere ifllet; hewever, these sases Ela Rat simulate semf!lete sere inlet eleskage. The gradual addilieR efresistanse at Ille sere ifllet slewly iflsreases the dewRseFRer le,,*el aRd dela}'S the astivatien ef the BB shallllel. EveRlually, the dewnseFRer driviRg heaEi eesemes suffisiently large le shaRge tl1e flew direstieR iR the BB shaRRel. After this f!eint, flew frerR the LP is Sf!lil eel1ween Ille eere iRlet aRd tlte BB aRa, as the eere inlet resistllllee eenliRues le euila, the flew :lraetieR te the BB eeRliflues te iRerease while tlte flew :!raetieR te the eere ifl:let aeereases. r:rem tllese siFRuiatieRB, the eere ifllet resistattee Reeessat)' te aetivate the BB ehaRRel (.K..,i;.,-we& a@t@FHlffi@B te Bil a streng flinstieR eftlt@ li:CClil flew. K.,.1,dilett@a as a fmlstien efli:CClil flew rat@ is f!FeYidea in Figure 11 3 anti the serresf!eRdiRg flew Sf!lit eew,een the sere inlet and the BB shallllel ~) fellewing ~s shewn ifl Figllfe 11 4. From the discussion presented in Section 11.2.3, it is clear that the fiber limit for the operating B&W plants will be the [ ]'*c and that Ksp1;1 and msplit are not needed to determine this limit. That is, within the context of the hot leg break methodology described in Volume 1, K,p1;1 can be assumed to be exceeded at 20 minutes regardless of ECCS flow rate and msplil set to 1.0 for all times after Ksp1i1 occurs. The result will be a fiber limit of [ ]"c which is what would be calculated if more reasonable values for K,p1;1 and msp1;1 were calculated . -* This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 Attachment 2 to L TR-SEE-17-102, Revision 0 WCAP-17788-P Mark-ups Page 782 of 782 WESTINGHOUSE NON-PROPRIETARY CLASS 3 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (defined as Km.,J was found to be 6*+0~4.75xl05. 12-2 3. The resistance at the core inlet that begins to divert flow into the AFP (defined as Kspli1) was found for a range ofECCS flow rates. These results are shown in Figure 9-3. 4. The flow split between the core inlet and the AFP after ~;1 (defined as ffispHi) was found for a range ofECCS flow rates. A curve that bounds the results was also developed. These results are shown in Figure 9-4. 12.3 COMBUSTION ENGINEERING PLANT CATEGORY CONCLUSIONS 1. The minimum time that complete core inlet blockage can be tolerated (defined as t1,10t1t) was found to be ~333 minutes. 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (defined as Kruax) was found to be 6.5xl06* 3. 4. The resistance at the core inlet that begins to divert flow into the AFP (defined as Ksplii) was found for a range ofECCS flow rates. These results are shown in Figure 10-4. The flow split between the core inlet and the AFP after Ksp1;1 (defined as msplit) was found for a range ofECCS flow rates. A curve that bounds the results was also developed. These results are shown in Figure 10-5. 12.4 BABCOCK & WILCOX PLANT CATEGORY CONCLUSIONS 1. The minimum time that complete core inlet blockage can be tolerated (defined as t1,10t1t) was found to be 20 minutes. 2. The maximum resistance at the core inlet that can be tolerated prior to reaching complete core inlet blockage (defined as Kmax) was found to be lxl08* 3. The resistance at the core inlet that begins to divert flow into the AFP (defined as ~1) was fo:YRa for a range ef E.CCS flew rates can be assumed to be exceeded at 20 minutes ( or the time of sump switchover). These results are sh.ewR iR Figure 11 3. 4. The flow split between the core inlet and the AFP after Ksp1;1 (defined as msplit) can be assumed to be 1.0 for all times after Ksplii is exceeded.was founa for a range efe.CCS flew rates. A euFve that eelff!as !He results wes else tle,,*elef!e8. These restdls ere shewn in Figure 11 4. ... This record was final approved on 12/18/2017 11 :42:20 AM. ( This statement was added by the PRIME system upon its validation) * * *}}

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