ML16305A296

0000-0163-8881-R0-NP, Revision 0, Exelon Nuclear LaSalle County Generating Station Units 1 & 2 Pool Swell Response.

ML16305A296
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Site:	LaSalle
Issue date:	10/27/2016
From:	Hitachi-GE Nuclear Energy, Ltd
To:	Office of Nuclear Reactor Regulation
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ML16305A291	List: ML16305A296 RS-16-193, License Amendment Request to Revise Suppression Pool Swell Design Analysis
References
003N9278-R0-NP
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ATTACHMENT 4 GE Hitachi Nuclear Energy Report 0000-0163-8881-RO, "Exelon Nuclear LaSalle County Generating Station Units 1 & 2 Pool Swell Response,"

October 2016 (Non-Proprietary)

LASALLE COUNTY STATION UNITS 1AND2 Docket Nos. 50-373 and 50-374 Facility Operating License Nos. NPF-11 and NPF-18 42 pages follow

GE Hitachi Nuclear Energy

• HITACHI 003N9278-RO-NP Revision 0 October 2016 Non-Proprietary Information - Class I (Public)

EXELON NUCLEAR LASALLE COUNTY GENERATING STATION UNITS 1 & 2 POOL SWELL RESPONSE Copyright 2016, GE-Hitachi Nuclear Energy Americas LLC All Rights Reserved

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public)

INFORMATION NOTICE This is a non-proprietary version of the document 003N9278-RO-P, Revision 0, which has the proprietary information removed. Portions of the document that have been removed are indicated by an open and closed bracket as shown here (( )).

IMPORTANT NOTICE REGARDING CONTENTS OF THIS REPORT PLEASE READ CAREFULLY The design, engineering, and other information contained in this document is :furnished for the purposes of supporting an evaluation for LaSalle County Generating Station pool swell in proceedings before the U.S. Nuclear Regulatory Commission (NRC). The only undertakings of GEH with respect to information in this document are contained in the contracts between GEH and its customers or participating utilities, and nothing contained in this document shall be construed as changing that contract. The use of this information by anyone for any purpose other than that for which it is intended, is not authorized; and with respect to any unauthorized use, GEH makes no representation or warranty, and assumes no liability as to the completeness, accuracy, or usefulness of the information contained in this document.

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REVISION

SUMMARY

Revision Required Changes to Achieve Revision 0 Initial issuance of the version containing marked GER proprietary information.

This report is based on 0000-0163-8881-RO dated February 2014.

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ACRONYMS AND ABBREVIATIONS Short Form Description BWR Boiling Water Reactor CF Core Flow CLTP Current Thermal Power DBA Design Basis Accident DEGB Doubled Ended Guillotine Break DW Drywell op Degrees Fahrenheit ft Feet GEH GE Hitachi Nuclear Energy HWL High Water Level Loss-of-Coolant Analysis Model for Boiling Water Reactors, GEH LAMB Computer Code for Break Mass and Energy Calculation LCGS LaSalle County Generating Station LOCA Loss-of-Coolant Accident Mark III Containment Pressure and Temperature; GEH Computer Code M3CPT for Short-term DBA-LOCA Containment Response Analysis.

MSIV Main Steam Isolation Valve MWt Megawatts thermal NIA Not Applicable NFWT Normal Feedwater Temperature NRC National Regulatory Commission NSSS Nuclear Steam Supply System PICSM GEH Pool Swell Response Code psia Pounds Per Square Inch Absolute psid Pounds per square inch differential PSTF Partial Scale Test Facility RFWT Reduced Feedwater Temperature RPV Reactor Pressure Vessel RSL Recirculation Suction Line RSLB Recirculation Suction Line Break sec Second SRV Safety Relief Valve TPO Thermal Power Optimization GEH Proprietary Version of the Transient Reactor Analysis Code (TRAC), GEH Computer Code for Best Estimate BWR Transient and TRACG Accident Analysis Calculations.

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Iw!:'Ort Form I * * ***Description I

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TABLE OF CONTENTS 1.0 TASK SCOPE AND PURPOSE ......................................................................................... 1

2.0 BACKGROUND

................................................................................................................. 1 3.0 INPUTS AND ASSUMPTIONS ......................................................................................... 1 4.0 BLOWDOWN MASS AND ENERGY ............................................................................... 2 4.1 Methodology (TRACG) .......................................................................................... 2 4.1.1 RSLB Mass and Energy Release Methodology Details ......................................... .2 4.2 Input and Assumptions ........................................................................................... 6 4.2.1 Key Inputs (TRACG) ............................................................................................... 6 4.3 Results ..................................................................................................................... 6 4.3.1 TRACG Mass and Energy Release .......................................................................... 6 5.0 DRYWELLPRESSURE ................................................................................................... 10 5.1 Methodology (M3CPT) ........................................................................................ 10 5 .1.1 Inputs and Assumptions ......................................................................................... 10 5.2 Results ................................................................................................................... 10 5.2.1 Drywell Pressure .................................................................................................... 10 6.0 POOL SWELL RESPONSE .............................................................................................. 13 6.1 Methodology ......................................................................................................... 13 6.1.1 Inputs and Assumptions ......................................................................................... 13 6.2 Results ................................................................................................................... 15 6.2.1 Maximum Pool Swell Elevation ............................................................................ 15 6.2.2 Pool Swell Response Data ..................................................................................... 15 7.0 OBSERVATIONS ............................................................................................................. 31

8.0 REFERENCES

.................................................................................................................. 34 vi

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) 1.0 TASK SCOPE AND PURPOSE This report discusses and presents the results of analyses performed to generate pool swell response profiles for the LaSalle County Generating Station (LCGS) plant in support of an Exelon assessment of the pool swell loads for LCGS.

Analyses are performed to generate Recirculation Suction Line Break (RSLB) Design Basis Accident - Loss-of-Coolant Accident (DBA-LOCA) mass and energy release using the GER TRACG method. Drywell (DW) pressure history is calculated using the GEH M3CPT method.

Pool surface level, velocity and acceleration histories are subsequently generated with the GER PICSM method.

The analysis in this report is applicable to the Current Licensed Thermal Power (CLTP) with Thermal Power Optimization (TPO) of 3,546 MWt and lower. The maximum power used in the analysis is 3,559 MWt, which is 102% of the stretch power uprate licensed thennal power (3,489 MWt) or 100.36% of the TPO CLTP of 3,546 MWt. This analysis covers the entire power/flow map including the effect of reduced feedwater temperature operation.

Other plant performance improvement and equipment out-of-service options identified in Reference 1 have no effect on the RSLB mass and energy release analyses. The current analysis, therefore, continues to support all flexibility and equipment out of service options.

2.0 BACKGROUND

The RSLB DBA-LOCA is the limiting event with respect to the initial mass and energy break flow to the DW, and therefore limiting for DW pressurization and associated pool swell response. Pool swell loads occur following a postulated DBA LOCA event during which the expulsion of water within the vent system and subsequent transfer of steam and non-condensable mass from the DW through the containment venting system produces loads on initially submerged structures and suppression pool boundaries as well as on structures above the initial suppression pool surface.

The pool swell response is driven by the initial DW pressurization during the first couple of seconds which is controlled by the blowdown mass and energy release rate to the DW during this period. This analysis provides a prediction of the RSLB DBA-LOCA DW pressure response for this initial time period and a prediction of the associated pool swell response.

3.0 INPUTS AND ASSUMPTIONS The analysis in this report is applicable to the CLTP with TPO of 3,546 MWt and lower. The maximum power used in the analysis is 3,559 MWt, which is 102% of the stretch power uprate licensed thermal power (3,489 MWt) or 100.36% of the TPO CLTP of 3,546 MWt.

The mass and energy release from a recirculation suction line double-ended guillotine break was calculated using the TRACG code and the DW pressure response was calculated using the approved M3CPT code. The M3CPT methodology is the same as that used in the current analysis of record for the short term containment analysis for LCGS Units 1and2. The use of the M3CPT model (References 2 and 3) for prediction of the driving DW pressure response and the Mark II pool swell response methodology (PICSM, Reference 4) was approved by the NRC in References 5 and 6.

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A more detailed description of inputs and assumptions are discussed in Section 4 for the TRACG break mass and energy calculation, in Section 5 for the M3CPT DW pressure calculation and in Section 6 for the PICSM pool swell response analysis.

4.0 BLOWDOWN MASS AND ENERGY 4.1 Methodology (TRACG)

The TRACG mass and energy release analysis models the entire reactor system producing accurate pressure and enthalpy conditions for the break and also accounts for the flow inertia in the piping that provides a more realistic evaluation of transient dynamics for downstream containment analysis. Details of the methods used to perform LCGS RSLB mass and energy release analysis are provided below.

The ability of the TRACG code to accurately model critical flow and the mechanisms that control flashing within the ruptured pipe are demonstrated by critical flow model test comparisons documented in Section 3.4 of NEDE-32177P (Reference 7). Section 3.4.1 of NEDE-32177P presents comparisons to Marviken Critical Flow Tests. Section 3.4.2 of NEDE-32177P presents comparisons to Partial Scale Test Facility (PSTF) critical flow tests. Section 3.4.3 of NEDE-32177P presents comparisons to the Edwards pipe blowdown tests. The comparisons to the Marviken and PSTF tests show that TRACG is capable of accurate modeling of critical flow for a range of initial conditions ranging from subcooled water to saturated steam for pressures consistent with Boiling Water Reactor (BWR) vessel pressures. When taken in total, the comparisons documented in Section 3.4 ofNEDE-32177P support the conclusion thatthe TRACG code can be used to generate more realistic mass and energy release rates than that from other codes, such as LAMB (Reference 8).

4.1.1 RSLB Mass and Energy Release Methodology Details 4.1.1.1 TRACG Model for Recirculation Suction Line Break The TRACG model is based on a full reactor system model that has been modified to model breaks at the nozzle safe end to pipe weld for the recirculation suction nozzle. Figure 4-1 presents a diagram of the recirculation loop model used in the standard TRACG reactor system model. The recirculation suction line portion is modeled as (( )) component in TRACG (PIPE0050).

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((

))

Figure 4- 1: Standard TRACG Transient Analysis Model Recirculation System Model For the LCGS pool swell mass and energy release analysis, a double ended guillotine rupture of the Recirculation Suction Line (RSL) is modeled with (( )). The break modeled in this report is an instantaneous Double Ended Guillotine Break (DEGB). The break area is equal to the sum of the cross-sectional areas of the reactor vessel nozzle and the pump-side pipe area.

((

))

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((

))

Figure 4-2: Instantaneous Double-Ended Guillotine Break Model

((

))

((

))

Flow from both sides of the break remains choked at the break location throughout the duration of this event.

Due to the symmetrical design of the reactor pressure vessel and the recirculation loops, the model is applicable to breaks at either RS nozzle safe end. In addition, the model is applicable to either unit, as the key inputs to the RSLB model are identical for LCGS Units 1 and 2.

The TRACG break flow model and qualification basis are described in NEDE-32176P (Reference 9) and NEDE-32177P (Reference 7) respectively.

4.1.1.2 Operating Conditions Considered for Recirculation Suction Line Break Break flow is affected by the enthalpy in in the RSL. The enthalpy of the fluid in the RSL depends on the reactor thermal power, core flow and dome pressure. A lower initial RSL enthalpy results in higher mass flux at the break.

Initial operating conditions listed in Table 4-1 were selected to envelope all licensed operating conditions that may affect this analysis. The following conditions listed in Table 4-1 were selected for the RSLB mass and energy release analysis.

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Table 4-1: Power/Flow Conditions Analyzed for RSLB Case Power Flow Dome Pressure Feedwater

(%TPO) (% Rated Flow) (psia) Temperature 3

(( 1,040 RFWT 1,040 RFWT 1,040 RFWT 1,040 RFWT 1,040 RFWT 1,040 NFWT

)) 1,040 NFWT Notes:

1. 2% uncertainty in power is included.

2. This is percentage ofTPO power of3,546 MWt. The absolute thermal power is 3,559 MWt for those cases.

3. Feedwater temperature reduction of 100°F is considered. The normal feed water temperature at CLTP is 428.5°F.

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003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) 4.2 Input and Assumptions 4.2.1 Key Inputs (TRACG)

Item Parameter "

Value Units Reference/ Basis .

1 Reactor Dome Pressure 1,040 psia --

2 Power/Flow Map Power/Flow NIA Reference 1 Map 3 Length of Recirculation (( )) inch --

Suction Nozzle from the Vessel 4 Loss Coefficient for Flow (( )) NIA ((

from the Vessel into the Recirculation Suction Nozzle

))

Sheet 4 of 4, K Factor Table, Appendix A, Crane Technical Paper No. 410, "Flow of Fluids Through Valves, Fittings and Pipe," 25th Printing, 1991.

5 Safety Relief Valve (SRV) Same as NIA ((

Numbers and Setpoints Reference 10 ))

6 Main Steam Isolation (( )) sec ((

Valve (MSIV) Closure Time

))

7 Feedwater Flow Coast (( )) sec --

Down Time 4.3 Results 4.3.1 TRACG Mass and Energy Release Figures 4-3 and 4-4 show the break mass flow rate and break flow enthalpy, respectively for the cases shown in Table 4-1 at Reduced Feedwater Temperature (RFWT). ((

))

For comparison, the break mass flow rate and break flow enthalpy for the cases shown in Table 4-1 at NFWT are shown in Figures 4-5 and 4-6, respectively.

(

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This analysis covers the entire power/flow map including the effect of reduced feedwater temperature operation.

Other plant performance improvement and equipment out of service options identified in Reference 1 have no effect on the RSLB mass and energy release analyses. The current analysis, therefore, continues to support all flexibility and equipment out of service options.

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((

)

))

Figure 4-3: RSLB Mass Release Rates (RFWT)

((

))

Figure 4-4: RSLB Fluid Enthalpy (RFWT) 8

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((

))

Figure 4-5: RSLB Mass Release Rates (NFWT)

((

))

Figure 4-6: RSLB Fluid Enthalpy (NFWT) 9

003N9278-RO-NP Revision 0 Non-Proprietary Information- Class I (Public) 5.0 DRYWELL PRESSURE 5.1 Methodology (M3CPT)

The DW pressure response is calculated with the M3CPT code. The M3CPT code was used for the short-term DBA-LOCA analysis of record and was also applied to the Reference 10 analysis.

The use of the M3CPT containment response models as an input to the PICSM calculation has been approved by the NRC in References 5 and 6. The M3CPT models include a containment model and a vessel model which is used for calculating internally generated blowdown mass and energy. For this calculation only the containment models ofM3CPT are applied, with blowdown mass and energy externally generated (TRACG) and entered as an input to M3CPT.

5.1.1 Inputs and Assumptions Inputs Key inputs for the M3CPT analyses are summarized in Appendix A.

Assumptions

1. Initial containment conditions are assumed to maximize the DW pressure response and maximum initial DW non-condensable gas.

2. Suppression pool is at the maximum level allowed for normal plant operation (High Water Level (HWL)).

3. WW airspace is saturated with an initial relative humidity of 100%

4. DW airspace relative initial humidity is at the minimum value (20%)

5. The vent flow consists of a homogeneous mixture of the fluid in the DW.

6. No heat loss from fluids in the DW to the structure (heat sinks)

7. The effect of vent back pressure on vent flow is not simulated. The M3CPT model has the capability to simulate the effects of vent backpressure produced by the LOCA bubble on the vent flow calculation and on the DW pressure response. As discussed by the NRC in Reference 5, the DW pressure response obtained with the M3CPT models, with the effects of vent inertia ignored (vent back pressure), are adequate for use with the References 2 and 3 M3CPT models for prediction of the pool swell response.

5.2 Results 5.2.1 Drywell Pressure Figure 5-1 provides a comparison of the DW pressure response for the different TRACG cases identified in Table 4-1. Figure 5-1 also contains a comparison to the prediction based on a blowdown generated with the LAMB (Reference 8) code at 100.36% TPO CLTP/100% Core Flow (CF) and a comparison to the DW pressure used as input to define the LCGS pool swell design basis load.

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Based on the comparison shown in Figure 5-1 the limiting case with TRACG break flow is RFWT Case A. As indicated by the results in Figure 5-1, the DW pressure response for the limiting TRACG-based case is comparable to the LAMB-based prediction. However, it is significantly higher than the DW pressure response shown in the LCGS design basis pool swell calculation during the post vent clearing period which controls the pool swell response.

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((

))

Figure 5-1: Drywell Pressure Comparison 12

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) 6.0 POOL SWELL RESPONSE 6.1 Methodology The Mark II pool swell response is calculated using the GER pool swell analytical code (PICSM).

This calculates the Mark II pool swell elevation, velocity and acceleration as a function of time.

The vent LOCA bubble pressure and WW pressurization due to compression effects is also predicted by the model and included in the output. The PICSM models, as described in Reference 4, were accepted by the NRC for use in predicting the Mark II pool swell response in References 5 and 6.

6.1.1 Inputs and Assumptions Inputs Geometry related inputs were developed based on the data shown in Appendix A. DW pressure data input to the PICSM calculations were selected from the M3CPT analysis of the limiting case (RFWT Case A) as discussed Section 5.0.

Assumptions The following assumptions are associated with the PICSM models (Reference 4).

1. The air is assumed to behave as an ideal gas.

2. Following vent clearing, two assumptions for the vent flow feeding the air bubble beneath the pool are available:

i) Air only flows into the suppression pool, rather than a mixture of air and steam. This maximizes the mass flow rate of non-condensables and therefore maximizes the resultant pool swell. This assumption is referred to as all-air carryover. This assumption is identified for use in design calculations per Reference 4 as approved by the NRC in References 5 and 6.

ii) A flow of air only until a specified amount of air (established by the air mass contained within the non-submerged portion of the vent downcomer) has been purged from the DW and vent systems, followed by a flow of an air-vapor mixture for the remainder of the transient. Complete condensation of the vapor is assumed so that the resultant driving flow of non-condensables to the bubble is reduced. This assumption is called mix and purge.

This assumption, which applies for Cases 3 and 4, assumes that only air flows through the downcomers until all air initially within the non-submerged portion of the downcomers is purged into the suppression pool. For the remainder of the transient, the steam/air ratio for the vent flow is held constant at a value established by the steam/air content in DW at the time all initial air in the downcomer is purged.

The assumption of a constant steam/air mixture is conservative relative to a dynamic steam/air ratio because the amount of air in the mixture gets progressively smaller with time into the transient.

The results with both options are presented in this report.

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3. The mass flow rate of non-condensables into the bubble is calculated assuming adiabatic flow through a duct with friction.

4. The air in the DW is isentropically compressed and heat transfer to the walls is conservatively neglected. For this compression process it is assumed that no mixing occurs, but mix and purge is allowed for in the vent mass flow model.

5. A variable bubble temperature equal to the current DW temperature throughout the transient.

6. Following vent clearing, the water above the exit of the vent (equal to the initial vent submergence plus the pool displacement due to vent clearing) accelerates as a slug of constant thickness.

7. Frictional losses between the water and the confining walls are negligible.

8. Viscous forces are negligible compared to the inertial and pressure forces.

9. The suppression pool air space is isentropically compressed by the upward moving water slug.

Heat transfer to the walls is neglected. (Note that for this calculation a polytropic coefficient of 1.2 is used for air compression pressurization when establishing peak pool swell elevation and for calculation of pool swell velocity and acceleration).

10. The air velocity in the DW is sufficiently small so that static and stagnation conditions are equivalent.

11. The entire pool surface rises as a uniform ligament of constant thickness.

Four PICSM cases are performed.

Case 1 - All Air Vent Flow, Polytropic Coefficient (k) of 1.2 for WW Airspace Compression Case 2 - All Air Vent Flow, Isentropic Coefficient (k) of 1.4 for WW Airspace Compression Case 3 - Mixed Air/Steam Vent Flow, Polytropic Coefficient (k) of 1.2 for WW Airspace Compression Case 4 - Mixed Air/Steam Vent Flow, Isentropic Coefficient (k) of 1.4 for WW Airspace Compression Case 1 assumptions are in accordance with the approved methodology in References 5 and 6 for design calculations.

Cases 1 and 2 use the standard assumption of all air vent flow for the analysis duration which is the more conservative assumption and identified in References 4, 5 and 6 for use in design applications. Cases 3 and 4 use the more realistic air/steam mixture (mix and purge option) which was identified in Reference 4 for application in best estimate calculations.

A polytropic coefficient of 1.2 is used to calculate the WW pressurization due to airspace compression for Cases 1 and 3. This value maximizes pool swell elevation and velocity. The results with the polytropic coefficient of 1.2 should be used to establish maximum elevation, velocity and acceleration profiles for design application. The results based on the polytropic coefficient of 1.2 should also be used for assessments of WW airspace pressurization loads due to 14

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) pool swell induced WW airspace compression. This is consistent with direction given in Appendix C of NUREG-0808 (Reference 6) which specifies that the WW air compression should be calculated consistent with the analyses for determination of the peak pool swell elevation.

The isentropic coefficient of 1.4 for air (Cases 2 and 4) is used to obtain results which maximize pressurization of the WW airspace due to compression effects .. The results based on the isentropic coefficient of 1.4 are presented as a sensitivity study for information purposes and not for design application.

All cases use the isentropic coefficient of 1.4 for air in calculating vent flow rates. The use of 1.4 versus a lower coefficient value (such as 1.3 for steam) results in higher vent flow rates and is therefore used to conservatively calculate vent flow for all cases.

6.2 Results 6.2.1 Maximum Pool Swell Elevation The maximum pool swell height is not directly calculated with PICSM.

Per Reference 6, the maximum pool swell elevation is defined as the higher of 1.5 times the initial submergence(= 1.5* 12.33 ft= 18.5 ft), or the elevation corresponding to the time at which there is a 2.5 psid compressed WW airspace to DW pressure difference (uplift differential pressure).

Per Reference 6, the maximum elevation should be determined based on the WW pressurization response calculated with a 1.2 polytropic coefficient for WW airspace compression.

The results of the PICSM calculation for all cases shows that the WW-to-DW differential pressure (uplift differential pressure) never reaches + 2.5 psid. Therefore, the maximum pool swell elevation as defined per the Reference 6 criteria, is established by 1.5 times the initial vent submergence (12.33 ft)= 18.5 ft.

6.2.2 Pool Swell Response Data Figures 6-1 through 6-4A show the predicted pool swell response for the four PICSM cases described above. Tables 6-1 through 6-4 provide the tabular data used to generate the pool swell response plots shown in the figures. These tables also provide the LOCA bubble pressure and compressed WW airspace pressure.

Figure 6-1 shows the PICSM predicted pool swell elevation versus time. The elevations in Figure 6-1 include a 1.1 multiplier adjustment on the PICSM elevation prediction to be consistent with the 1.1 multiplier on the predicted velocity as required by References 5 and 6. The elevations also include a 0. 7 ft adder to the PICSM prediction to account for the difference between initial pre-LOCA elevation and initial PICSM elevation which corresponds to the elevation after vent clearing. The elevations shown in this and subsequent figures correspond to elevation relative to the pre-LOCA initial pool surface elevation.

Figure 6-2 shows the PICSM predicted pool swell velocity versus time. The velocities in Figure 6-2 include a 1.1 multiplier adjustment on the PICSM velocity prediction as required by References 5 and 6. Velocities corresponding to adjusted elevations greater than the maximum pool swell elevation of 18.5 ft are not included.

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Figure 6-3 shows the PICSM adjusted pool swell velocity vs adjusted elevation up to a maximum adjusted elevation of 18.5 ft. Velocities and elevation used to generate Figure 6-3 include a 1.1 multiplier adjustment.

Figure 6-3A shows the PICSM adjusted pool swell velocity vs. adjusted elevation up to a maximum adjusted elevation of 18.5 ft. However, in Figure 6-3A, the maximum velocity is held constant for elevations above the elevation at which the maximum velocity occurs. This uses the Mark II Owners Group load description for pool swell velocity included in Appendix C of Reference 6. Velocities and elevations used to generate Figure 6-3A include a 1.1 multiplier.

Figure 6-4 shows the PICSM adjusted pool swell acceleration vs. adjusted elevation up to a maximum adjusted elevation of 18.5 ft. Velocities and elevations used to generate the acceleration profiles in Figure 6-4 include a 1.1 multiplier.

Figure 6-4A shows the PICSM adjusted pool swell acceleration vs. adjusted elevation up to a maximum adjusted elevation of 18.5 ft. However, in Figure 6-4A, the acceleration is set to zero for elevations above the elevation at which the maximum velocity occurs. This provides consistency with the velocity assumption used for Figure 6-3A. Velocities and elevations used to generate the acceleration profiles in Figure 6-4A include a 1.1 multiplier.

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Table 6-1: Case 1: PICSM Pool Swell Response-All Air Vent Flow, Polytropic Gas Coefficient of 1.2 for Wetwell Airspace Compression -1.1 Multiplier on Elevation and Velocity

.Pool

.. Surfaee

.. *Elevatii>n

. Pool

. Surface Vent .wetw.ell Ab()ve * ~ool . *Pool Surface . Acceleration:

Bubble **Airspace. *. . initfa1 . '*

• Surface.* Pool Suiface. *. V elocify. Per Per

.. :P~essure

• Pressure ** Elevation 1 *

• Velocity1 : .Acc~Ieratfon 1 *

• Reference 62 Reference*62 TIME:::S.* : (psfa) .

• Trisi~) *. . (ft) ** ' (ft/sec) * *. * (ft/sec2)  : * * (ft/sec) ** fft/sec 2) 0.744 34.7 15.9 0.78 6.237 0 6.237 0 0.769 33.76 15.997 0.961 8.151 76.56 8.151 76.56 0.794 33.46 16.122 1.192 10.021 74.8 10.021 74.8 0.819 33.08 16.274 1.467 11.803 71.28 11.803 71.28 0.844 32.74 16.454 1.786 13.508 68.2 13.508 68.2 0.869 32.4 16.662 2.138 15.125 64.68 15.125 64.68 0.894 31.99 16.898 2.534 16.654 61.16 16.654 61.16 0.919 31.6 17.164 2.974 18.084 57.2 18.084 57.2 0.944 31.24 17.459 3.436 19.404 52.8 19.404 52.8 0.969 30.93 17.785 3.942 20.625 48.84 20.625 48.84 0.994 30.64 18.142 4.47 21.747 44.88 21.747 44.88 1.019 30.35 18.531 5.031 22.759 40.48 22.759 40.48 1.044 30.08 18.954 5.603 23.672 36.52 23.672 36.52 1.069 29.83 19.412 6.208 24.475 32.12 24.475 32.12 1.094 29.61 19.905 6.835 25.157 27.28 25.157 27.28 1.119 29.43 20.436 7.462 25.74 23.32 25.74 23.32 1.144 29.27 21.004 8.122 26.202 18.48 26.202 18.48 1.169 29.15 21.612 8.782 26.554 14.08 26.554 14.08 1.194 29.05 22.26 9.442 26.785 9.24 26.785 9.24 1.219 28.99 22.95 10.113 26.906 4.84 26.906 4.84 1.244 28.95 23.681 10.784 26.906 0 26.906 0 1.269 28.94 24.455 11.455 26.785 -4.84 26.906 0 1.294 28.97 25.27 12.126 26.543 -9.68 26.906 0 1.319 29.02 26.127 12.786 26.169 -14.96 26.906 0 1.344 29.1 27.022 13.435 25.674 -19.8 26.906 0 1.369 29.21 27.955 14.073 25.047 -25.08 26.906 0 1.394 29.36 28.92 14.689 24.299 -29.92 26.906 0 1.419 29.53 29.913 15.283 23.419 -35.2 26.906 0 1.444 29.74 30.927 15.855 22.407 -40.48 26.906 0 1.469 29.99 31.954 16.405 21.274 -45.32 26.906 0 1.494 30.27 32.985 16.922 20.02 -50.16 26.906 0 1.519 30.59 34.006 17.406 18.656 -54.56 26.906 0 1.544 30.94 35.006 17.846 17.182 -58.96 26.906 0 17

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,Pool Surface Pool Elevation Surface Vent Wetwell Above Pool Pool Surface Acceleration Bubble Airspace initial Surface Pool Surface Velocity Per Per Pressure Pressure .. Elevation 1 Velocity1 Accelerafion 1 Reference 62 Reference.62 TIME-S (psia) (psia) ... (ft) (ft/sec) (ft/sec 2) (ft/sec). (ft/sec2)

• 1.569 31.34 35.969 18.264 15.62 -62.48 26.906 0 1.585 31.63 36.562 18.5 14.47371 -64.1283 26.906 0 Notes:

1- Pool Surface elevation, velocity and acceleration account for a 1.1 multiplier to the PICSM output on elevation and velocity.

2- Per Appendix C of Reference 6 velocity held constant at maximum velocity and acceleration held at zero for times after maximum velocity reached.

18

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Table 6-2: Case 2 PICSM Pool Swell Response-All Air Vent Flow, Isentropic Gas Coefficient of 1.4 for Wetwell Airspace Compression -1.1 Multiplier on Elevation and Velocity Pool Surface Elevation Vent Wetwell Above Pool Pool Surface Pool Surface Bubble Airspace initial Surface Pool Surface . Velocity Per

• Acceleration Per Pressure Pressure Elevation1 Velocity' Acceleration 1 Reference 62 Reference 62 TIME-S (psia) (J)sia) (ft) '(ft/sec) (ft/sec 2) (ft/sec) (ft/sec2)

• 0.744 34.7 15.975 0.78 6.237 0 6.237 0 0.769 33.77 16.089 0.961 8.14 76.12 8.14 76.12 0.794 33.47 16.235 1.192 9.988 73.92 9.988 73.92 0.819 33.1 16.413 1.467 11.759 70.84 11.759 70.84 0.844 32.76 16.624 1.775 13.442 67.32 13.442 67.32 0.869 32.43 16.868 2.138 15.037 63.8 15.037 63.8 0.894 32.03 17.146 2.534 16.533 59.84 16.533 59.84 0.919 31.65 17.458 2.963 17.919 55.44 17.919 55.44 0.944 31.31 17.805 3.425 19.206 51.48 19.206 51.48 0.969 31 18.189 3.92 20.383 47.08 20.383 47.08 0.994 30.73 18.61 4.448 21.439 42.24 21.439 42.24 1.019 30.47 19.069 4.987 22.396 38.28 22.396 38.28 1.044 30.22 19.568 5.559 23.243 33.88 23.243 33.88 1.069 29.99 20.109 6.153 23.958 28.6 23.958 28.6 1.094 29.8 20.691 6.758 24.563 24.2 24.563 24.2 1.119 29.64 21.317 7.374 25.036 18.92 25.036 18.92 1.144 29.51 21.988 8.012 25.388 14.08 25.388 14.08 1.169 29.42 22.704 8.65 25.619 9.24 25.619 9.24 1.194 29.35 23.467 9.288 25.718 3.96 25.718 3.96 1.219 29.32 24.275 9.937 25.696 -0.88 25.718 0 1.244 29.33 25.129 10.575 25.531 -6.6 25.718 0 1.269 29.36 26.027 11.213 25.234 -11.88 25.718 0 1.294 29.44 26.968 11.829 24.805 -17.16 25.718 0 1.319 29.54 27.948 12.445 24.233 -22.88 25.718 0 1.344 29.68 28.963 13.039 23.529 -28.16 25.718 0 1.369 29.85 30.007 13.622 22.693 -33.44 25.718 0 1.394 30.07 31.071 14.183 21.714 -39.16 25.718 0 1.419 30.32 32.148 14.711 20.603 -44.44 25.718 0 1.444 30.61 33.225 15.206 19.371 -49.28 25.718 0 1.469 30.94 34.29 15.679 18.018 -54.12 25.718 0 1.494 31.31 35.328 16.108 16.555 -58.52 25.718 0 1.519 31.73 36.323 16.504 14.993 -62.48 25.718 0 1.544 32.19 37.258 16.856 13.354 -65.56 25.718 0 19

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"* .Poor ,.,

., Surface 1.

! _," . -i

, .. Elev_ation '**'.

Vent

• W etwell , * .*'Above Pool .,Pool Surface * . : *-Pool. Surface ,,

Bubble * '.(\irspace initial .. .Surfac_e

• _. Pool Surface~ Velocity Per Acceleration Per

'" ~ ~

Pressure *Pressure ; Elevation 1

• Velocity1 :Accefora'tion 1 ' .  :: Reference 62 *Reference 62 TIME'-S, . (psial fosia)  :(ft): (ft/sec)* .(ft/sec2) .. * (ft/sec) * . *. (ft/sec2)

• 1.569 32.7 38.118 17.164 11.649 -68.2 25.718 0 1.594 33.26 38.887 17.439 9.889 -70.4 25.718 0 1.619 33.87 39.55 17.659 8.118 -70.84 25.718 0 1.644 34.52 40.097 17.846 6.347 -70.84 25.718 0 1.669 35.21 40.519 17.978 4.609 -69.52 25.718 0 1.694 35.93 40.814 18.077 2.926 -67.32 25.718 0 1.719 36.69 40.982 18.132 1.32 -64.24 25.718 0 1.744 37.47 41.027 18.143 0 -52.8 25.718 0 3

Extended 18.5 25.718 0 Notes:

1. Pool Surface elevation, velocity and acceleration account for a 1.1 multiplier to the PICSM output on elevation and velocity.

2. Per Appendix C of Reference 6 velocity held constant at maximum velocity and acceleration held at zero for times after maximum velocity reached.

3. Velocity and acceleration for design per Reference 6 extended to 18.5 ft.

20

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Table 6-3: Case 3: PICSM Pool Swell Response-Mix and Purge Option for Vent Flow, Polytropic Gas Coefficient of 1.2 for Wetwell Airspace Compression -1.1 Multiplier on Elevation and Velocity Pool Surface

• Elevation Pool Surface

• vent Wetwell

• Above Pool Pool Surface Acceleration Bubble Airspace initial Surface Pool Surface Velocity. Per Per Pressure Pressure Elevation 1 Velocity1 Acceleration 1 Reference 62 Reference 62 TIME-S (psia) * (psia) (ft) (ft/sec) (ft/sec 2) . (ft/sec) (ft/sec 2) ..

0.744 34.7 15.9 0.78 6.237 0 6.237 0 0.769 33.76 15.997 0.961 8.151 76.56 8.151 76.56 0.794 33.46 16.122 1.192 10.021 74.8 10.021 74.8 0.819 33.08 16.274 1.467 11.803 71.28 11.803 71.28 0.844 32.74 16.454 1.786 13.508 68.2 13.508 68.2 0.869 32.4 16.662 2.138 15.125 64.68 15.125 64.68 0.894 30.2 16.898 2.534 16.522 55.88 16.522 55.88 0.919 28.76 17.158 2.963 17.578 42.24 17.578 42.24 0.944 27.84 17.442 3.414 18.403 33 18.403 33 0.969 27.2 17.746 3.887 19.074 26.84 19.074 26.84 0.994 26.74 18.07 4.371 19.602 21.12 19.602 21.12 1.019 26.37 18.413 4.866 20.02 16.72 20.02 16.72 1.044 26.08 18.776 5.361 20.328 12.32 20.328 12.32 1.069 25.85 19.156 5.878 20.537 8.36 20.537 8.36 1.094 25.68 19.554 6.395 20.658 4.84 20.658 4.84 1.119 25.55 19.969 6.912 20.68 0.88 20.68 0.88 1.144 25.47 20.4 7.429 20.636 -1.76 20.68 0 1.169 25.42 20.846 7.935 20.504 -5.28 20.68 0 1.194 25.41 21.307 8.452 20.295 -8.36 20.68 0 1.219 25.43 21.781 8.958 20.009 -11.44 20.68 0 1.244 25.48 22.267 9.453 19.668 -13.64 20.68 0 1.269 25.56 22.763 9.937 19.25 -16.72 20.68 0 1.294 25.67 23.267 10.41 18.766 -19.36 20.68 0 1.319 25.81 23.778 10.872 18.227 -21.56 20.68 0 1.344 25.97 24.294 11.323 17.633 -23.76 20.68 0 1.369 26.16 24.811 11.752 16.984 -25.96 20.68 0 1.394 26.38 25.328 12.17 16.291 -27.72 20.68 0 1.419 26.63 25.841 12.566 15.543 -29.92 20.68 0 1.444 26.9 26.347 12.951 14.762 -31.24 20.68 0 1.469 27.2 26.844 13.303 13.948 -32.56 20.68 0 1.494 27.52 27.328 13.644 13.112 -33.44 20.68 0 1.519 27.87 27.796 13.963 12.243 -34.76 20.68 0 1.544 28.25 28.245 14.26 11.363 -35.2 20.68 0 21

003N9278-RO-NP Revision 0 Non-Proprietary Information- Class I (Public)

Pool Surface Elevation Pool Surface Vent Wetwell *Above P9ol Pool Surface Acceleration Bubble Airspace initial Surface Pool Surface Velocity Per Per Pressure .Pressure Elevation 1 Velocity1 Acceleration 1 Reference 62

• Reference 62 TIME-S (psia) (psia) (ft) (ft/sec) (ft/sec2) (ft/sec) (ft/sec2) .

1.569 28.66 28.673 14.535 10.472 -35.64 20.68 0 1.594 29.09 29.076 14.777 9.592 -35.2 20.68 0 1.619 29.55 29.454 15.008 8.712 -35.2 20.68 0 1.644 30.03 29.803 15.217 7.854 -34.32 20.68 0 1.669 30.53 30.123 15.404 7.018 -33.44 20.68 0 1.694 31.06 30.412 15.569 6.215 -32.12 20.68 0 1.719 31.59 30.672 15.712 5.445 -30.8 20.68 0 1.744 32.15 30.902 15.844 4.73 -28.6 20.68 0 1.769 32.72 31.103 15.954 4.07 -26.4 20.68 0 1.794 33.3 31.278 16.042 3.465 -24.2 20.68 0 1.819 33.89 31.427 16.13 2.926 -21.56 20.68 0 1.844 34.48 31.554 16.196 2.464 -18.48 20.68 0 1.869 35.08 31.662 16.251 2.079 -15.4 20.68 0 1.894 35.68 31.753 16.295 1.771 -12.32 20.68 0 1.919 36.26 31.832 16.339 1.529 -9.68 20.68 0 1.944 36.83 31.902 16.372 1.386 -5.72 20.68 0 1.969 37.38 31.967 16.405 1.309 -3.08 20.68 0 1.994 37.91 32.03 16.438 1.298 -0.44 20.68 0 Extended 18.5 3 20.68 3 0 Notes:

1. Pool Surface elevation, velocity and acceleration account for a 1.1 multiplier to the PICSM output on elevation and velocity.

2. Per Appendix C of Reference 6 velocity held constant at maximum velocity and acceleration held at zero for times after maximum velocity reached.

3. Velocity and Acceleration for design per Reference 6 extended to 18.5 ft.

22

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Table 6-4: Case 4: PICSM Pool Swell Response - Mix and Purge Vent Flow Option, Isentropic Gas Coefficient of 1.4 for Wetwell Airspace Compression -1.1 Multiplier on Elevation and Velocity Pool Surface Elevation Pool Sur.face

• Vent Wetwell Above*

• Pool *Pool Surface

• Acceleration

• Bubble Airspace initial Surface Pool Surface Velocity Per Per.

Pressure Pressure Elevation 1 Velocity1 Acceleration~ Reference 62 Reference 62 TIME~s * (psia)* (psia) (ft) (ft/sec) (ft/sec2) (ft/sec) (ft/sec2) 0.744 34.7 15.975 0.78 6.237 0 6.237 0 0.769 33.77 16.089 0.961 8.14 76.12 8.14 76.12 0.794 33.47 16.235 1.192 9.988 73.92 9.988 73.92 0.819 33.1 16.413 1.467 11.759 70.84 11.759 70.84 0.844 32.76 16.624 1.775 13.442 67.32 13.442 67.32 0.869 32.43 16.868 2.138 15.037 63.8 15.037 63.8 0.894 30.24 17.145 2.534 16.401 54.56 16.401 54.56 0.919 28.82 17.452 2.952 17.424 40.92 17.424 40.92 0.944 27.92 17.785 3.403 18.216 31.68 18.216 31.68 0.969 27.3 18.143 3.865 18.832 24.64 18.832 24.64 0.994 26.85 18.524 4.338 19.316 19.36 19.316 19.36 1.019 26.51 18.929 4.822 19.668 14.08 19.668 14.08 1.044 26.25 19.355 5.317 19.921 10.12 . 19.921 10.12 1.069 26.04 19.802 5.823 20.064 5.72 20.064 5.72 1.094 25.9 20.27 6.329 20.108 1.76 20.108 1.76 1.119 25.8 20.757 6.824 20.053 -2.2 20.108 0 1.144 25.75 21.262 7.33 19.91 -5.72 20.108 0 1.169 25.74 21.783 7.825 19.69 -8.8 20.108 0 1.194 25.76 22.319 8.309 19.382 -12.32 20.108 0 1.219 25.82 22.868 8.793 18.997 -15.4 20.108 0 1.244 25.92 23.428 9.255 18.535 -18.48 20.108 0 1.269 26.04 23.996 9.717 18.007 -21.12 20.108 0 1.294 26.2 24.569 10.157 17.402 -24.2 20.108 0 1.319 26.4 25.145 10.586 16.742 -26.4 20.108 0 1.344 26.62 25.719 10.993 16.027 -28.6 20.108 0 1.369 26.88 26.289 11.389 15.257 -30.8 20.108 0 1.394 27.16 26.85 11. 752 14.443 -32.56 20.108 0 1.419 27.48 27.398 12.104 13.585 -34.32 20.108 0 1.444 27.83 27.93 12.434 12.705 -35.2 20.108 0 1.469 28.21 28.442 12.742 l 1.792 -36.52 20.108 0 1.494 28.62 28.93 13.028 10.857 -37.4 20.108 0 l.519 29.06 29.39 13.281 9.922 -37.4 20.108 0 1.544 29.54 29.82 13.523 8.987 -37.4 20.108 0 23

003N9278-RO-NP Revision 0 Non-Proprietary Information- Class I (Public)

Pooi Surface Elevation Pool Surface Vent Wetwen* Above *Pool Pool Surface Acceleration Bubble Airspace initial Surface Pool Surface Velocity Per Per

' 'Pressure Pressure Elevation 1 Velocity1 Accelenition 1 Reference 62 Reference 6 2 TIME-S (psia) (psia) (ft) (ft/sec) (ft/sec2) * (ft/sec) (ft/sec2) 1.569 30.04 30.217 13.732 8.063 -36.96 20.108 0 1.594 30.56 30.58 13.93 7.161 -36.08 20.108 0 1.619 31.I 30.906 14.095 6.292 -34.76 20.108 0 1.644 31.67 31.196 14.238 5.456 -33.44 20.108 0 1.669 32.26 31.449 14.37 4.675 -31.24 20.108 0 1.694 32.87 31.667 14.469 3.949 -29.04 20.108 0 1.719 33.48 31.852 14.568 3.278 -26.84 20.108 0 1.744 34.12 32.007 14.634 2.684 -23.76 20.108 0 1.769 34.76 32.133 14.7 2.167 -20.68 20.108 0 1.794 35.4 32.235 14.744 1.738 -17.16 20.108 0 1.819 36.03 32.317 14.788 1.397 -13.64 20.108 0 1.844 36.65 32.384 14.821 1.133 -10.56 20.108 0 1.869 37.26 32.439 14.843 0.957 -7.04 20.108 0 1.894 37.84 32.487 14.865 0.869 -3.52 20.108 0 1.919 38.4 32.533 14.887 0.858 -0.44 20.108 0 3 3 Extended 18.5 20.108 0 Notes:

1. Pool Surface elevation, velocity and acceleration account for a 1.1 multiplier to the PICSM output on elevation and velocity.

2. Per Appendix C of Reference 6 velocity held constant at maximum velocity and acceleration held at zero for times after maximum velocity reached.

3. Velocity and Acceleration for design per Reference 6 extended to 18.5 ft.

24

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) 20 18 16 14 j'.:' 12 z - CASE 1: K= 1.2 ALL AIR Q.... 10

<( - CASE 2: K=l.4 ALL AIR

>w

..... 8 - CASE 3: K=l.2 MIX &PURGE w

- CASE 4 : K=l.4 MIX & PURGE 6

4 2

0 0 0.5 1 1.5 2 2.5 TIME (SECONDS)

Figure 6-1: Pool Swell Elevation versus Time 25

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) u

.,,w j::- - CASE 1: K=l.2 ALL AIR u..

~15  : = .4 ALL AIR u

0 - CASE 3: K=l.2 MIX & PURGE

....w

> - CASE 4: K=l.4 MIX & PURGE 0 0.5 1 1.5 2 2.5 TIME (SECONDS)

Figure 6-2: Pool Swell Velocity versus Time 26

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) vQI

~

~

~> 15 + - - ---- ' - - - - - - - - - - - -----------'- - - -- -

Qj

~

0"'

0 Q.

. . . CASE 1: GEH K 1.2 ALL AIR

- CASE 2: GEH K 1.4 ALL AIR

-.++- CASE 3: GEH K 1.2 MIX & PURGE 5

- . - CASE 4 : GEH K 1.4 MIX & PURGE

-.++- LSCS DESIGN CALC 3C7-1075-001 RG 0 2 4 6 8 10 12 14 16 18 20 Pool Swell Elevation Above Initial Level (ft)

Figure 6-3: Pool Swell Velocity versus Elevation 27

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) u

~

.~

u

~ 15 +--~--t---+-~~~~~~~~~~~~~~~~~~~~~

Qj

~

0 0

0..

-+- CASE 1: GEH K 1.2 A LL AIR

- CASE 2: GEH K 1.4 ALL AIR

~ CA SE 3: GEH K 1.2 MIX AND PURGE

,.._ CASE 4: GEH K 1.4 MIX &

PURGE LSCS DESIGN CALC 3C7-1075-001 R6 0 4 6 8 10 12 14 16 18 20 Pool Swell Elevation Above Initial Level (ft)

Figure 6-3A: Pool Swell Velocity versus Elevation (Velocity Held Constant at Maximum Velocity for Elevations Above Elevation of Maximum Calculated Velocity per NUREG-0808 Appendix C) 28

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) 60

-e- cASE 1: GEH K 1.2 ALL AIR 40

- CASE 2: GEH K 1.4 ALL AIR

~ CASE 3: GEH K 1.2 MIX &

PURGE

- 20 EA K 1.4 MIX &

u e:

...... PURGE

~

c

.g

"'u Qi 0

u 2 4 14 18 20 ct Qi

~

0"'

0 c.. -20

-100 ~-----------------------------

Pool Swell Elevation Above Initial Level (ft)

Figure 6-4: Pool Swell Acceleration versus Elevation 29

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public)

N' 20 u

~

~

c:

.g

"'~ 0 Qi u

u 2 4 6 8 10 12 14 16 18 20

<(

Qi

~

"'0 0

0.. -20

~ CASE 1: GEH K 1.2 ALL AIR

-40

- CASE 2: GEH K 1.4 ALL AIR

~ CASE 3: GEH K 1.2 MIX &

PURGE

-60 ...,._C SE4: G PURGE

-80

-100 - ' - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Pool Swell Elevation Above Initial Level (ft)

Figure 6-4A: Pool Swell Acceleration versus Elevation (Zero Acceleration for Elevations Above Elevation of Maximum Calculated Velocity, Consistent with Velocity Profile per NUREG-0808 Appendix C) 30

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) 7.0 OBSERVATIONS It is noted that the predicted RSLB DBA-LOCA DW pressure response prior to vent clearing, as shown on Figure 5-1, appears to be higher than the DW pressure history reportedly applied for the LCGS design basis pool swell analyses. The DW pressure history prior to vent clearing was not used for the pool well re ponse calculation. However, the DW pressure history prior to vent clearing can affect the loads defined for vent clearing (e.g., submerged structure drag loads due to expulsion of the liquid slug initially within the vent downcomer). Therefore, it is recommended that Exelon review the LCGS design basis for vent clearing loads to determine if the limiting DW pressure response prior to vent clearing, presented in Figure 5-1 , is bounded by the DW pressure used to define the LCGS vent clearing loads.

The use of the mix and purge modeling (air/steam mixture) is considered a best estimate option as is identified in Reference 4. However, even with the use of this option there remains conservatism in the overall pool swell prediction results presented in this report. The TRACG calculations assume an instantaneous double ended guillotine break which maximizes the break flow during the critical initial period for pool swell. Additionally, the analysis reactor dome pressure of 1,040 psia is higher than the normal operating pressure of 1,020 psia and LCO of 1,035 psia and is being applied for the limiting TRACG case (Case A with RFWT) even though this case corresponds to an off-rated condition. The inherent conservatisms in the M3CPT model are retained for the calculation of the DW pressure response which is used in PICSM. Surface condensation of vapor on initially cold DW and vent downcomer surfaces is neglected. The constituents of the fluid flowing through the vents are based on a homogeneous mixture of the fluid in the DW. This assumption yields increased vent system flow density resulting in higher flow losses and therefore higher DW pressure. The mix and purge option as applied for the PICSM calculation uses a constant value for air fraction(= 0.61) for the transient analysis duration which corresponds to the air fraction in the DW at the time the air initially contained within the downcomer vents have been purged to the suppression pool (approximately 0.9 seconds). As shown in Figure 7-1, the DW air fraction after this time fall to values during the pool swell transient analysis period (to approximately 2 seconds) which are significantly lower than the constant value of 0.61 used for the PICSM calculation. The PICSM calculations use a polytropic coefficient of 1.2 which minimizes the WW airspace compression pressurization and thereby maximizes the predicted pool swell elevation and velocity. The drag effects of downcomer bracing on the bulk pool swell response is neglected in the PICSM pool swell response prediction. The inherent conservatism in the PICSM prediction, along with the use of the 1.1 multiplier, produces a conservative pool swell response prediction. When the 1.1 multiplier is applied to the PICSM predicted data shown in Figure 6.42 of Reference 4 (which is based on best estimate predictions of the Mark I 4 T tests using the mix and purge option), persistent over prediction of the test data is demonstrated (see Figure 7-2). Similar trends in PICSM predicted results versus test data have been shown for predictions of the 1/13 scale Mark II multi-vent tests (Reference 11) cited in NUREG-0487 and the JAERI full scale multi-vent Mark II tests cited in NUREG-0808.

31

003N9278-RO-NP Revision 0 Non-Proprietary Information - Class I (Public) l.OOE-t-00 9.00E-01 8.00E-01 owncomer ent urge Air Fraction= 0.61 7.00E-01 6.00E-01 c

0

" 5.00E-01

~ - orywell Air Fraction RFWT Ca se A

.i Q; 4.00E-01 0

~

3.00E-01 2.00E-01 1.00E-01 0.00E+OO 0 0.5 1.5 2.5 Time (seconds)

Figure 7-1: Drywell Air Fraction (Air Mass/(Air Mass+ Steam Mass))

32

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((

))

Figure 7-2: Comparison of Measured versus Predicted Maximum Pool Swell Velocity Based on Best Estimate of Mark II 4T Test Boundary Conditions 33

003N9278-RO-NP Revision 0 Non-Proprietary Information- Class I (Public)

8.0 REFERENCES

1. GE Hitachi Nuclear Energy, "Safety Analysis Report for LaSalle County Station Units 1 and 2 Thermal Power Optimization," NEDC-33485P, Revision 0, January 2010.

2. General Electric Company, "The GE Pressure Suppression Containment Analytical Model,"

NEDM-10320, March 1971.

3. GE Nuclear Energy, "The General Electric Mark III Pressure Suppression Containment System Analytical Model," NED0-20533, June 1974.

4. GE Nuclear Energy, "Mark II Pressure Suppression Containment Systems: An Analytical Model of the Pool Swell Phenomenon," NEDE-21544-P, December 1976.

5. NUREG-0487, Supplement 1, "Mark II Containment Lead Plant Program Load Evaluation and Acceptance Criteria," September 1980 and NUREG-0487, "Mark II Containment Lead Plant Program Load Evaluation and Acceptance Criteria," October 1978,

6. NUREG-0808, "Mark II Containment Program Load Evaluation and Acceptance Criteria,"

August 1981

7. GE Hitachi Nuclear Energy, "TRACG Qualification," NEDE-32177P, Revision 3, August 2007.

8. General Electric Company, "General Electric Company Analytical Model for Loss-of-Coolant Analysis in Accordance with 10CFR50 Appendix K," NEDE-20566-P-A, September 1986.

9. GE Hitachi Nuclear Energy, "TRACG Model Description," NEDE-32176P, Revision 4, January 2008.

10. GE Hitachi Nuclear Energy, "Exelon Nuclear, LaSalle County Generating Station Units 1 &

2 Sh01i-Term Containment Bounding Pa Assessment," 0000-0149-2311-RO, August 2012.

11. General Electric Company, "Comparison of the 1/13 Scale Mark II Containment Multi-Vent Pool Swell Data with Analytical Methods," NED0-21667, August 1977.

34

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APPENDIX A - KEY INPUT PARAMETERS FOR DRYWELL PRESSURE AND POOL SWELL RESPONSE ANALYSIS

• Item No~ *Parameter Value CONTAINMENT GEOMETRY 1.0 PARAMETERS 1.a. DW Volume(ft3) 229,538 WW Airspace Volume at Suppression Pool 1.b. 164,800 HWL (ft3)

I.e. Initial Suppression Pool Volume at HWL (ft3) 131,900 Suppression Pool Surface in Contact with WW 1.d. 4,999 Airspace (ft2) 1.e. Suppression Pool Depth at HWL (ft) 26.813 Vent Submergence at Suppression Pool HWL 1.f. 12.333 (ft) l.g. Number ofDowncomers 98 1.h. Downcomer Inner Diameter (ft) 1.958 l.i. Vent Loss Coefficient 5.2 Total Vent Downcomer Length from Entrance l.j. Above DW Floor to Submerged Vent 49.29 Dowcomer Exit in Suppression Pool (ft) 2.0 INITIAL CONDITIONS 2.a. Initial DW Temperature (°F) 98 2.b. Initial DW Pressure (psia) 15.45 2.c. Initial DW Relative Humidity (%) 20 2.d. Initial WW Airspace Temperature (°F) 105 2.e. Initial Suppression Pool (SP) Temperature (°F) 105 2.f. Initial WW Pressure (psia) 15.45 2.g. Initial WW Relative Humidity (%) 100 3.0

• LOCA BUBBLE VENT BACK PRESSURE LOCA Bubble Vent Back Pressure Effect No 3.a.

Modeled (See discussion in Section 5)

ADDITIONAL PICSM SPECIFIC 4.0 .. MODEL.ING PARAMETERS A-1

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Itein No. Parameter Value Results are Presented with All Air and Mix and Purge 4.a. Vent Flow Air Fraction Option.

(See discussion in Section 6)

Results are Presented with Isentropic Coefficient of 1.4 Specific Heat Ratio (Polytropic ~oefficient) ~or (air) and Polytropic 4.b.

PICSM WWAirspace Compression Calculation Coefficient of 1.2.

(See discussion in Section 6)

Set Equal to Current 4.c. Bubble Temperature Specification Option Calculated DW Temperature.

Isentropic Coefficient of 1.4 Specific Heat Ratio for Compressible Vent for Air Used.

4.d.

Flow Calculation (See discussion in Section 6) 4.e. Vent Loss Coefficient 5.2 1.1 4.f. Multiplier on Pool Swell Velocity (See discussion in Section 6)

A-2