Analysis of the SGTR accident for LFR by SIMMER code Nicola Forgione CIRTEN Consorzio...

Analysis of the SGTR accident for LFR by SIMMER code

Nicola Forgione

CIRTENConsorzio Interuniversitarioper la Ricerca Tecnologica

Nucleare

UNIVERSITA’ DI PISADipartimento di Ingegneria Meccanica, Nucleare e della Produzione

3rd LEADER International Workshop, September 2012

Content


• Introduction

• SIMMER generalities

• SIMMER history

• SIMMER validation phases

• Example of validation study for FCI phenomenon

• SIMMER applications for SGTR analysis at UNIPI• Simulation of SGI tests

• Experimental campaigns on LIFUS 5 facility

• Simulation of LIFUS 5 tests

• Simplified parametric analysis of the SGTR accident for LFR

• Conclusions

Introduction


The interaction between two fluids, of which one (e.g. lead) is less volatile and at higher temperature than the other one (e.g. water), results in the production of high pressure vapourThus, this is one of the most important concerns for safety issues of:–lead and sodium cooled reactors belonging to “Generation IV” systems –ADS where both core and target are cooled by LBE

In LFR, the liquid metal (primary coolant) might come into contact with the water flowing in the steam generator because of an accidental Steam Generator Tube Rupture (SGTR) CCI

In SFR a loss of coolant accident can increase the core temperature up to the fuel and steel melting, leading this mixture to interact with the surrounding coolant FCI

One of the crucial issue for the safety analysis is represented by the evaluation of the energy released in such interactions, in order to have indications of the potential loads and the resulting damage on reactor structures

SIMMER generalities

SIMMER III is a 2D, three velocity-field, multi-component, multiphase, Eulerian fluid-dynamics code coupled with neutron kinetics model. It can deals with safety analysis problems in advanced fast reactors


• 1st step: SIMMER was developed in 1974 at Los Alamos National Laboratory (USA) for HCDA (Hypothetic Core Disruptive Analysis) in LMFR

• 2nd step: development of a small prototype fluid dynamics code AFDM, at the base for new SIMMER code development

• 3rd step: SIMMER-III development in 1988 in collaboration with PNC (now JNC, Japan Nuclear Cycle Development Institute)

• 4th step: in 1992 Version “0”. Beginning of an European-Japanese (FZK, CEA, IRSN) cooperation on LMFR R&D

• 5th step: in 2000 finalization of the code assessment. Beginning of the reactor integral application for safety analysis studies

• 6th step: two iso-model codes (SIMMER-III and SIMMER-IV) coupled to two neutronic codes (TWODANT and THREEDANT)

SIMMER history


Phase 1 (1992-1996) applied to single- and multi-phase flow benchmark problems, small-scale experiments with reactor and simulant materials, and physical problems with known solutions. It consists of 32 problems, which tested specific code models: fluid convection algorithm, interfacial area and flow regimes, momentum exchange functions, heat transfer coefficients, melting/freezing and vaporization/condensation

Phase 2 (1996-2000) applied to integral, complex multiphase situations. It is intended to cover key accident phenomena, which are directly relevant to the CDA and include: boiling pool, fuel relocation and freezing, material expansion, fuel coolant interactions (FCIs), and disrupted core neutronics


SIMMER validation phases


SIMMER validation phases Problem

#Full Title Short Title Org.

Category 1: Boiling Pool Dynamics CEA-G

1.1 Isothermal 3D bubble column 3D bubble JNC

1.2 2Φ flows with large liquid density Dense flow JNC

1.3 Void distribution in 2Φ flow in a pipe Void in pipe JNC

1.4 Analysis of V/C in the Sebulon experiment SEBULON CEA-G

1.5 Analysis of 2Φ flow phenomena in the Burty and Castillejos experiment Burty CEA-G

1.6 Analysis of vaporization and stratification in the MMB experiment MMB CEA-G

1.7 Calculation of SCARABEE APL3 APL3 CEA-G

1.8 Analysis of SCARABEE BF2 test BF2/JNC JNC

1.9 Analysis of a boiling pool of fuel in the SCARABEE BF2 experiment BF2/CEA CEA-G

1.10 Assessment of the 1-D 2Φ flow modelling of the SIMMER-III code on the LOTUS

LOTUS CEA-G

1.11 Rapid depressurization of a tube initially-filled with water Bartak CEA-G

Category 2: Fuel Freezing and Relocation JNC

2.1 Re-calculation of a THEFIS experiment freezing of AL2O3 melt in a quartz tube

THEFIS JNC

2.2 Analisys of THEFIS with particles THEFIS with particles JNC

2.3 Basic freezing test sin a tube and analysis Basic freezing JNC

2.4 Fuel freezing in a steel tube: analysis of GEYSER and BLOKKER II tests GEYSER/BLOKKER JNC

2.5 2Φ flow freezing interpretation of the Bullage experiment BULLAGE CEA-G

2.6 Analysis of the CABRI-2 E11 experiment CABRI E11 IPSN

2.7 Analysis of CAMEL C6 and C7 tests CAMEL JNC

2.8 Analysis of SCARABEE PV-A test PV-A JNC

Problem #

Full Title Short Title Org.

Category 1: Boiling Pool Dynamics CEA-G

1.1 Isothermal 3D bubble column 3D bubble JNC

1.2 2Φ flows with large liquid density Dense flow JNC

1.3 Void distribution in 2Φ flow in a pipe Void in pipe JNC

1.4 Analysis of V/C in the Sebulon experiment SEBULON CEA-G

1.5 Analysis of 2Φ flow phenomena in the Burty and Castillejos experiment Burty CEA-G

1.6 Analysis of vaporization and stratification in the MMB experiment MMB CEA-G

1.7 Calculation of SCARABEE APL3 APL3 CEA-G

1.8 Analysis of SCARABEE BF2 test BF2/JNC JNC

1.9 Analysis of a boiling pool of fuel in the SCARABEE BF2 experiment BF2/CEA CEA-G

1.10 Assessment of the 1-D 2Φ flow modelling of the SIMMER-III code on the LOTUS

LOTUS CEA-G

1.11 Rapid depressurization of a tube initially-filled with water Bartak CEA-G

Category 2: Fuel Freezing and Relocation JNC

2.1 Re-calculation of a THEFIS experiment freezing of AL2O3 melt in a quartz tube

THEFIS JNC

2.2 Analisys of THEFIS with particles THEFIS with particles JNC

2.3 Basic freezing test sin a tube and analysis Basic freezing JNC

2.4 Fuel freezing in a steel tube: analysis of GEYSER and BLOKKER II tests GEYSER/BLOKKER JNC

2.5 2Φ flow freezing interpretation of the Bullage experiment BULLAGE CEA-G

2.6 Analysis of the CABRI-2 E11 experiment CABRI E11 IPSN

2.7 Analysis of CAMEL C6 and C7 tests CAMEL JNC

2.8 Analysis of SCARABEE PV-A test PV-A JNC


SIMMER validation phases Problem

#Full Title Short Title Org.

Category 3: Fuel Coolant Interaction FZK

3.1 Analysis of the behavior of thermite THINA JNC

3.2 Analysis of high pressure corium melt quenching test FARO JNC

3.3 Analysis of large scale fuel- sodium interaction in the TERMOS T1 experiment

THERMOS CEA-G

3.4 Analysis of FCI experiment in alumina/water system KROTOS JNC

3.5 Analysis of PREMIX experiment PM06 PREMIX FZK

3.6 Analysis of QUEOS experiments Q08 and Q12 QUEOS FZK7JNC

Category 4: Material Expansion Dynamics CEA-C

4.1 Calculation of the SGI expansion phase experiement SGI CEA-G

4.2 Analysis of Purdue OMEGA tests OMEGA JNC

4.3 Calculation of CARAVELLE 6 experiment CARAVELLE CEA-C

4.4 Analysis of VECDTORS experiment VECTORS JNC

4.5 Analysis of developing anular flow Annular flow JNC

Category 5: Disrupted Core Neutronics FZK

5.1 Analysis of FCA - VIII fuel slumping experiments FCA JNC

5.2 Analysis of space- time neutron kinetics using the improved quasi -static method in SIMMER-III

Kinetics JNC

5.3 Analysis of FCA - VIII fuel slumping experiments with TWODANT FCA/TWODANT FZK

5.4 Neutronic validations for reactor transition phase ERANOS CEA-G

Problem #

Full Title Short Title Org.

Category 3: Fuel Coolant Interaction FZK

3.1 Analysis of the behavior of thermite THINA JNC

3.2 Analysis of high pressure corium melt quenching test FARO JNC

3.3 Analysis of large scale fuel- sodium interaction in the TERMOS T1 experiment

THERMOS CEA-G

3.4 Analysis of FCI experiment in alumina/water system KROTOS JNC

3.5 Analysis of PREMIX experiment PM06 PREMIX FZK

3.6 Analysis of QUEOS experiments Q08 and Q12 QUEOS FZK7JNC

Category 4: Material Expansion Dynamics CEA-C

4.1 Calculation of the SGI expansion phase experiement SGI CEA-G

4.2 Analysis of Purdue OMEGA tests OMEGA JNC

4.3 Calculation of CARAVELLE 6 experiment CARAVELLE CEA-C

4.4 Analysis of VECDTORS experiment VECTORS JNC

4.5 Analysis of developing anular flow Annular flow JNC

Category 5: Disrupted Core Neutronics FZK

5.1 Analysis of FCA - VIII fuel slumping experiments FCA JNC

5.2 Analysis of space- time neutron kinetics using the improved quasi -static method in SIMMER-III

Kinetics JNC

5.3 Analysis of FCA - VIII fuel slumping experiments with TWODANT FCA/TWODANT FZK

5.4 Neutronic validations for reactor transition phase ERANOS CEA-G

THINA: out-of-pile experiments, in which a thermite mixture of molten alumina and iron was injected into a sodium pool from the bottom. TH564 and TH562 tests are simulated by SIMMER-III. The aim was to investigate the phenomenology and physics of thermal-hydraulic interactions between melt and sodium.

S-III well reproduces the pressure history

and the experimental mechanical energy

release, so the conversion of thermal

into mechanical energy

S-III underestimates the axial expansion of the 2Φ region (maybe non-condensable gas

initially separated from the melt)

S-III REASONABLY SIMULATES THERMAL INTERACTION

BETWEEN SODIUM AND MELT


Example of validation studyfor FCI phenomenon

3270 KAl2O3+Fe

780-790 K

2D r-z Geometry Mesh 6x30 cells4 material component 3 velocity fields

K.Morita et al., “SIMMER-III applications to fuel-coolant interactions”,

Nucl. Eng. Des., 1999


SIMMER applicationsfor SGTR analysis at UNIPI

Goal: analysis of the phenomena at the basis of the interaction between water and heavy liquid metals (CCI) due to its importance for the safety aspects of SGs foreseen for the LFRs:SIMMER assessment for CCI with the post-test analysis of:

• relevant experimental tests coming from literature (e.g. SGI)• experimental tests that have been carried out at ENEA by LIFUS 5 facility

in two different configurationsSimplified thermal-hydraulic study of the possible consequences deriving from a Steam Generator Tube Rupture (SGTR) accident, which could occur in the LFR prototype

LEADER THINS

Lead-cooled European Advanced DEmonstration Reactor

Thermal-Hydraulics of Innovative Nuclear Systems


Simulation of SGI testsExpansion phase

In case of severe accident: discharge of molten material from core and acceleration of surrounding coolant; redistribution of granulated fuel

Important for work energy potential and mechanical structure load assessment after severe accident

Upper core and vessel structures & behavior to be known (impact on mitigation)

A good evaluation of the expansion phase is crucial for assessing the work potential with a better accuracy than that obtained through the isentropic expansion, which gives a very conservative estimation without taking into account momentum and heat transfer to structures.

SGI Experiment

• An experimental campaign called SGI (Schnelle Gas Injection) was performed in 1994 in former Forschungszentrum Karlsruhe, now KIT.

• The experiments dealing with the injection of a high pressure gas into a stagnant liquid pool.

• Three tests, respectively 91, 93 and 95, have been simulated with SIMMER III and FLUENT codes.

Test n.

Presence of inner

structures

Inner structure diameter

[cm]

Nozzle diameter

[cm]

Initial pressure

[bar]

91 yes 23 9 1193 yes 23 9 695 yes 23 9 3


Simulation of SGI tests

Scheme of the experimental facility for the SGI Campaign (units: [cm])

SIMMER III R-Z geometrical domain

The simple geometry of the experimental facility allows to set-up a two dimensional axial-symmetric computational domain), which was divided into about 10800 cells. The time step chosen for the simulations is equal to10-6 s.

FLUENT geometrical domain

An axial-symmetric domain has been set up for representing the test section. It was subdivided into 31 radial and 68 axial cells (2108 cells). The pressure vessel, the connection tube and the inner walls inside the main vessel have been shaped through ‘no calculation’ regions.

In order to perform a comparison between two different kinds of codes the tests 91, 93, 95 have been chosen. These tests have been arranged with the same geometrical features, that is the presence of an inner vessel wall with a diameter of 23 cm and the nozzle diameter equal to 9 cm. The only parameter changed has been the nitrogen injection pressure which has been respectively set equal to 11 bar for test 91, 6 bar for test 93 and 3 bar for test 95.



Pressure transientin the cover gas region

Experimental and numerical bubble’s shape evaluation (Test 91)



Test 91; Pinj = 11 bar Test 93: Pinj = 6 bar

Gas bubble volume comparison

As can be seen, the bubble volume time trends obtained from FLUENTand SIMMER match each other in the considered time range



Initial configuration of LIFUS 5 facility, adopted to perform the Test n.1 of the IP-EUROTRANS campaign

S1 - reaction tank

Volume 0.1 m3

Inside diameter 0.42 m

Design pressure 200 bar

Design temperature 500 °C

Material AISI 316

S2 - water tank

Volume 0.015 m3

Inside diameter 4 in.sch.160 [in]



Material AISI 316

S3 - safety tank

Volume 2.0 m3

Inside diameter 1.0 m



Material AISI 316

S5 - expansion tank

Volume 10.1 liters

Inside diameter 6 in.sch.160 [in]



Material AISI 316


Experimental campaignson LIFUS 5 facility

Reactiontank

Safetytank

Expansiontank

Watertank

Reactiontank

S2

Reactiontank

Watertank

Safety tank

Scheme of the modified configuration of LIFUS 5 facility, adopted to perform the Test n. 3 and 4 of the IP-EUROTRANS

and Test n. 1 and 2 of ELSY campaigns

•Direct connection of the reaction vessel S1 with the safety vessel S3 through a discharge line

•The four welded plates inside S1 have been removed



IP –EUROTRANS ELSY

Test n.1 Test n.2 Test n.3 Test n.4 Test n.1 Test n.2

LBE temperature [°C] 350 350 350 350 400 400

Pressure on LBE free level [bar] 1 1 1 1 1 1

Water injection pressure [bar] 70 6 40 40 180 180Water temperature [°C] 235 130 235 235 325 325LBE volume [l] 105 80 100 80 80 80

Cover gas volume [l] 5 (in S5) 20 (in S1) no 20 (in S1) 20 (in S1) 20 (in S1)

Orifice diameter [mm] 4 8 4 4 4 4Injector penetration [m] 0.08 0.06 0.05 0.05 0.005 0.25Test duration [s] 10 10 3 3 3 3Presence of S5 yes no no no no no

Summary of the operating conditions in IP-EUROTRANS and ELSY tests



Detailed computational 2D model (20x32 cells)

set-up in order to improvethe results of the simulations

respect to a previousless detailed model

SIMMER III computational model for the Test n.1

of the IP-EUROTRANS campaign


Simulation of LIFUS 5 tests

Reactiontank

Expansiontank

0.E+00

1.E+06

2.E+06

3.E+06

4.E+06

5.E+06

6.E+06

7.E+06

8.E+06

9.E+06

0 2 4 6 8 10 12

Time [s]

Pre

ssure

[P

a]

Experimental

SIMMER III

0.E+00

1.E+06

2.E+06

3.E+06

4.E+06

5.E+06

6.E+06

7.E+06

8.E+06

9.E+06

0 2 4 6 8 10 12

Time [s]

Pre

ssu

re [

Pa]

Experimental

SIMMER III

240

260

280

300

320

340

360

0 2 4 6 8 10 12Time [s]

Tem

pera

ture

[°C

]

TC18

SIMMER III

Pressure and temperature results obtained for IP-EUROTRANS Test n.1

Comparison between the experimental pressure trend and that computed by SIMMER III

Comparison between the temperature measured by the middle thermocouple in S1and that calculated by SIMMER III

The experimental temperature data were found to be in a quite good agreement with the calculated trend



SIMMER III and IV computational models for the Test n.3 and 4 of the IP-EUROTRANS campaign and the Test n. 1 and 2 of the ELSY program

3-D calculation domain employed in SIMMER IV for Tests 3 and 4 IB=20, JB=18, KB=16, cells

Two-dimensional calculation domain, 23x39 cells



S3Safety tank

S2Water tank

Reaction tank

S3

S1

S2

Pressure results obtained for the Test n. 3 and n. 4 of the IP-EUROTRANS campaign, with SIMMER III and IV code

Test n. 3 Test n. 4

Both simulations predict the peak pressure that appear at about 0.6 s, even if in Test 4 the pressure trend is still overestimated, but a better agreement between the two simulations is observed



Temperature results obtained for the Test n.3 and n.4 of the IP-EUROTRANS campaign, with SIMMER III and IV code

The predicted temperatures are affected by large high-frequency oscillationsnot detected in the experimental data

Test n. 3 (middle thermocouple) Test n. 4 (middle thermocouple)



SIMMER III computational models for the Test n.1 and n.2 of the ELSY campaign

Detail of the computational 2D domain for the reaction vessel (S1) Test n.1 Test n.2

Test n. 1 differs from Test n. 2 only for the injector device penetration, respectively, 5 mm and 250 mm



Obtained results for the Test n. 1 and n. 2 of the ELSY campaign with SIMMER III and IV code

SIMMER III succeeded in predicting the pressure peak in terms of value and timing, though slightly overestimating the first part of depressurization phase (from 0.75 to 1.5 s). On the other hand, the SIMMER IV code was found to anticipate the peak pressure

SIMMER III code was found to overestimate the pressure peak (though corresponding in timing) and the first part of the depressurization phase (up to 1.5 s), whereas, SIMMER IV resulted once again to anticipate the peak pressure



Test n. 1 Test n. 2

S4 – Storage tankLBE

LBE

S2Water

S1 - Interaction vessel

V24

Ar supply

V1

Wa. ½’’

S3

Pb – LBE 2'’

Drainage

D1

Gas / LBE 3'’

V13

V11

V3

V4 V14

V5

V6

V16

V15

V9

V7

TC-S4V-01

PC-S4V-01

Discharge

V20

V22

Ar gas

PC-S1V-01 LC-S1V-01

V21

Argon Argon

MT-S2L-01

Drainage

coriolis flow meter

LevelGauge

Housing

LIFUS5/Mod2THINS configuration 2012

V23

Discharge

Vacuum pumpAir circuit

PC-AUX-01

V19

Compressor PC-AUX-02

Wa. 2’’

Wa. 1/2’’

LT-S2V-01

PC-S2V-01

PC-S2V-02

PT-S2L-07

TC-S2L-01

TC-S2V-01

PT-S2V-06

TC-S2V-02

PC-S3V-01

Water

TC-S3L-01

Discharge

Discharge

PT-S1V-05

PT-S1V-03 PT-S1V-02

TC-S1V-02

SG-S1V-03 SG-S1V-02

TC-S1V-01

V25

Discharge



Parameter Value/TypeElectric Power 600 MW Thermal Efficiency 42 % Primary Coolant Pure Lead Primary System Pool Type, Compact Primary Coolant Circulation

Forced

Primary System Pressure Drops

1.5 bar

Primary Coolant Circulation for DHR

Natural

Inlet Core Temperature 400°C Outlet Core Temperature

480°C

Fuel MOX and nitrates (with/without MA)Maximum Clad Temperature

550°C

Reactor Vessel Inox and Austenitic Steel, H = 9 m Steam Generator N°8, inside the reactor vessel Primary Pumps N°8, mechanical, from hot collector Internals Removable Internal Vessel CylindricalDHR immersion cooling container

N°4, inside the cold collector

ELSY reactor sectionMean parameters of the ELSY reactor


Simplified parametric analysisof the SGTR accident for LFR

Spiral-tubeSG

Primarypump

Parameter Value

Number 8Location Reactor vessel Function Heat removal and steam

productionType Spiral tubes Primary fluid Lead Secondary fluid Water Heat transfer capacity 187.5 MW Lead inlet temperature 480°CLead outlet temperature 400°CWater inlet temperature 335°CWater outlet temperature 460°CWater inlet pressure 190 barWater outlet pressure 180 barLead total flow rate 130000 kg/sLead flow velocity 2 m/sWater total flow rate 114.7 kg/s

SG design requirementSteam Generator sections



Approximation of the SG region in the calculation domain

The spatial discretization of the whole domain foresees 20 radial cells and 40 axial cells (SIMMER III)

The domain reproduces the real SG dimensions, radius and height, and a larger expansion volume

Calculation domains and simulation matrix



SeriesInjector

Diameter[mm]

Domain configuration Simulation

A

18 Reference A118 Outer wall Porosity A218 Venturi nozzle in the injector A318 Tube close to the injector A418 Grid in the SG upper plenum A5

B

24 Reference B124 Outer wall Porosity B224 Venturi nozzle in the injector B324 Tube close to the injector B424 Grid in the SG upper plenum B5

Matrix of the simulation campaign

The total orifice coefficient value inside the injector was properly taken equal to 4

Region ComponentVolume

[m3](or Length)

Temperature

[°C ]

Pressure[bar]

I Water injector (1.76 m) 335 190

II SG lead 10.7 450 1-4III SG argon 1.35 450 1IV EV argon 25.2 450 1V EV lead 231 400 1-6



Geometrical domains for each particular condition

Domain configuration Test n.

Outer wall Porosity 2Venturi-nozzle in the injector 3

Tubes close to the injector 4Grid in the SG upper plenum 5

In the Test n. 2 a limited porosity is presented in the SG outer wall. It is due to a non perfect adherence of the two shells (main and companion) of the outer wall, when overpressure occurs during the SGTR accidentIn the Test n. 3 the

Venturi nozzle is introduced into the water injector pipe to try to limit the water mass flow rate coming out

In the Test n. 4 two non-calculation cell groups are taken into account, close to the injector opening, to simulate the SG tube bundle, which could reduce the water mass flow rate and the perturbation propagation

In the Test n. 5 a grid is designed on the SG upper side, a line below the lead level, to simulate internal upper structures



Comparison among water mass flow rate calculated

for different tests

In the case A1, A2, A4 and A5 the water flow increases very quickly reaching the maximum value of nearly 20 kg/s around to 0.02 s. The Venturi-nozzle (A3 case) limits the mass flow rate to a much lower value of about 3 kg/s. In the Venturi orifice critical flow conditions are reached

Obtained results



Pressure trend at the injector exit for all the A simulations

Only a too limited margin of about 5 bar in the first peak value and 10 bar in the following evolution after 0.01 s are noted between the test A3 and the others

Comparison among the pressure peaks of A simulations in the highest cell

In the lead acceleration phase, liquid metal reaches the cover gas region, determining an initial argon pressurization and compression and finally hitting the upper SG wall at about 0.2 s

Obtained results



Comparison between the lead kinetic energy of A and B series.

Comparison among the lead kinetic energy of A simulations. The rapid effect of the SG isolation, due to the double shell wall system, leads to the upward lead motion

The A3 peak is almost not present in respect to that of the other A simulations. This is the clear proof of the damping effects deriving from the Venturi nozzle introduction in water injector pipe

Obtained results



Around to 0.9 s the cover gas becomes a mixture of vapor and argon and the compression work trend loses its meaning

Obtained results



Comparison between the argon compression work of A test series, due to the lead kinetic effect

The main aim of this study was the analysis of the phenomena involved in CCI with particular attention to the SIMMER code qualification, in order to have the possibility of estimating the potential loads on LFR reactor structures due to SGTR

In addition to the analysis of the available LIFUS 5 experimental tests, the analysis of some relevant experimental tests coming from literature have been performed

The injection of a high pressure gas into a stagnant liquid pool, which characterizes the expansion phase of a hypothetical CDA in liquid metal cooled fast reactors, was investigated with SIMMER III and FLUENT codes through the experimental campaign SGI (KIT), obtaining good agreement with the experimental data

The simulation activity performed up to now in support to LIFUS 5 experiments has highlighted the capability of SIMMER code to reproduce quite well the thermal-fluid-dynamics phenomena involved in the interaction between water and heavy liquid metals (LBE)

As future work we will execute post-test analysis of the experimental tests that will be performed, inside THINS EU Project, in the LIFUS 5 facility with the new configuration (LIFUS5/Mod2)


Conclusions

A preliminary parametric analysis of the consequences for the SGTR accident in the LFR has been performed by SIMMER III code using a simplified domain to reproduce the SG

The presence of a Venturi nozzle in the injection line and the closure of a Safety Valve haven’t influences on the impulsive first pressure peak

The Venturi-nozzle inside the LFR SG pipes has, instead, a strong influence on the reduction in the mass flow rate going out from the broken pipe and consequently on the lead kinetic energy value, on the impulsive pressure peak on the top plate and on the cover gas “compression work”

The interaction between water and lead can be subdivided in three main phases: a first impulsive shock wave, a subsequent liquid metal kinetic energy increase which leads to have pressure peaks on the top plate wall and, lastly, a compression work increase in the cover gas


Conclusions

Analysis of the SGTR accident for LFR by SIMMER code Nicola Forgione CIRTEN Consorzio...

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