SARNET Concept for the Advanced communication Tool ACT in SARNET

1
Review of LPCFD recombiner modelling and
experimentsapplicability to reactor simulations
and open issuesErnst-Arndt Reinecke, Stephan
Kelm, Wilfried JahnJÜLICH, Safety Research and
Reactor TechnologyAhmed Bentaib, Nicolas
Meynet, Cataldo CaroliIRSN, Safety Reactor
Division
3rd European Review Meeting on Severe Accident
Research Nesseber, Bulgaria, 23-25 September, 2008
2

Review of LPCFD recombiner modelling and
experimentsapplicability to reactor simulations
and open issues

• Introduction
• PAR Modelling State of the art, challenges
• Recent activities in SARNET- Experiments
  (JÜLICH)- Detailed PAR model (JÜLICH)- CFD
  modelling (IRSN, JÜLICH)
• Specific challenge PAR ignition modelling (IRSN)
• Perspectives for SARNET-2

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Introduction

• Hydrogen in LWR
• Hydrogen release during SA scenario- oxidation
  of LWR fuel rod cladding material melt-concrete
  interaction- formation of flammable H2/air
  mixture in containment
• Implementation of passive auto-catalytic
  recombiners (PAR)- AREVA / NIS / AECL design
• Numerical PAR models required for- accident
  analysis- assessment of PAR efficiency-
  determination of optimum PAR positioning

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PAR modelling State of the art

• Integral Experiments
• global PAR behaviour
• typical data integral conversion rate,
  inlet/outlet temperature, inlet/outlet
  H2 concentration

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PAR modelling State of the art

• PAR models Application and limitations
• parameter models (e.g. implemented in
  GASFLOW)e.g. Siemens correlation
• 1-d detailed model(COCOSYS/ASTEC)
• Applicability limited to- specific PAR
  geometry- experimental boundary conditions-
  parameters measured in experiments

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PAR modelling Challenges

• For advanced containment studies
• Interaction of PAR with containment
  atmosphere(50 PAR with 200 kW thermal power
  each per PWR containment)
• Ignition phenomena
• Influence of flow conditions- forced flow
  situations- flow direction

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PAR modelling Challenges

• For advanced containment studies
• Interaction of PAR with containment
  atmosphere(50 PAR with 200 kW thermal power
  each per PWR containment)
• Ignition phenomena
• Influence of flow conditions- forced flow
  situations- flow direction

8
Review of LPCFD recombiner modelling and
experimentsapplicability to reactor simulations
and open issues

• Introduction
• PAR Modelling State of the art, challenges
• Recent activities in SARNET- Experiments
  (JÜLICH)- Detailed PAR model (JÜLICH)- CFD
  modelling (IRSN, JÜLICH)
• Specific challenge PAR ignition modelling (IRSN)
• Perspectives for SARNET-2

9
Recent activities in SARNET periodJPA/TPA/SAP

• Detailed PAR studies
• Experiments (JÜLICH) - partly national funded
• PAR model development (JÜLICH) - partly national
  funded
• CFD modelling (IRSN, JÜLICH)

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Experiments JÜLICH

• Studies on PAR operational behaviour
• steady-state forced flow conditions(REKO-3)
• transient natural flow conditions(REKO-4)

REKO-3
REKO-4
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Experiments JÜLICH

• Studies on PAR operational behaviour
• steady-state forced flow conditions(REKO-3)

REKO-3
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Experiments JÜLICH

• Studies on PAR operational behaviour
• steady-state forced flow conditions(REKO-3)

REKO-3
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Experiments JÜLICH

• Studies on PAR operational behaviour
• transient natural flow conditions(REKO-4)

PAR
REKO-4
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Experiments JÜLICH

• Studies on PAR operational behaviour
• transient natural flow conditions(REKO-4)

Monday, September 15, 2008
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PAR model development JÜLICH
catalyst temperature
gas temperature
REKO-DIREKT
hydrogen removal
buoyancy flow
transient calculation
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CFD modelling IRSN/JÜLICH

• Three approaches
• model with global chemistry (IRSN)
• black-box model inside CFD code (IRSN/JÜLICH)
• model with mass transfer approach (JÜLICH)

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CFD modelling IRSN

• PAR modelling using CFX (detailed model)
• Low Mach number formulation
• Global chemistry
• Realistic geometry
• Transient calculations

Example of PAR geometry (typical grid 100000
nodes)
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CFD modelling IRSN

• PAR modelling using CFX (detailed model)
• Evaluation of catalytic plates temperature and
  PAR starting

Temperature at leading edge of catalytic plates
(c)
Temperature at PAR outlet (c)
Time (s)
Time (s)
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CFD modelling IRSN

• PAR modelling using TONUS (black-box model)
• Low Mach number formulation for containment
  thermal-hydraulics
• Black-box model for PAR coupled with CFD code
• Realistic geometry
• Transient calculations

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CFD modelling IRSN

• PAR modelling using TONUS (black-box model)
• Preliminary study of the impact of PAR location
  (academic)

Simplified geometry
PDR room
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CFD modelling IRSN
y 1.0 m
y 0.1 m
Risk of stratification according to PAR location
y 2.0 m
y 2.9 m
Hydrogen molar fraction
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CFD modelling IRSN
y 1.0 m
y 0.1 m
Coupling between recirculations and PAR behavior
y 2.0 m
y 2.9 m
Stream function
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CFD modelling JÜLICH

• PAR modelling using CFX (detailed model)
• Mass transfer approach describing reaction
  kinetics

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CFD modelling JÜLICH

• PAR modelling using CFX (detailed model)

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CFD modelling JÜLICH

• PAR modelling using CFX (black-box model)
• Black-box parameter model(Siemens correlation)
• Applied in SARNET PARIS benchmarks

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Review of LPCFD recombiner modelling and
experimentsapplicability to reactor simulations
and open issues

• Introduction
• PAR Modelling State of the art, challenges
• Recent activities in SARNET- Experiments
  (JÜLICH)- Detailed PAR model (JÜLICH)- CFD
  modelling (IRSN, JÜLICH)
• Specific challenge PAR ignition modelling (IRSN)
• Perspectives for SARNET-2

27
Specific challenge Ignition modelling

• High relevance
• basic part of the recombiner operational
  behaviour
• significant influence on the progression of
  accident scenario
• possible impact on the PAR efficiency after
  ignition

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Specific challenge Ignition modelling

• H2PAR and KALI experiments
• Evaluation of flammability limits based on global
  measurements

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Specific challenge Ignition modelling

• REKO-3 ignition experiments
• Evaluation of flammability limits based on local
  measurements

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Specific challenge Ignition modelling

• PAR modelling using SPARK
• Low Mach number formulation
• Complex gaseous chemistry
• Complex surface chemistry
• Detailed transport
• Simplified geometry
• Steady calculations

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Specific challenge Ignition modelling

• PAR modelling using SPARK geometry

Numerical domain (half-channel)
Catalytic Plate
Outlet
Outlet
Complex Gaseous Chemistry
Complex Surface Chemistry
External wall
Symmetry or external wall
Catalytic plate
Internal flow
Detailed Transport
Catalytic Plates Inside PAR
Inlet
Numerical Domain
Inlet
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Specific challenge Ignition modelling

• PAR modelling using SPARK chemistry

Detailed Surface Chemistry, Deutschmann (1996)
Detailed Gaseous Chemistry, Warnatz (1996)
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Specific challenge Ignition modelling

• PAR modelling using SPARK validation

Numerical and experimental OH molar fraction
fields
Inlet
PSI catalytic reactor experiment
Profile of mean OH molar fraction

• Ignition distance
• Experiment 9.30 cm
• Calculation 9.58 cm

Ignition
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Review of LPCFD recombiner modelling and
experimentsapplicability to reactor simulations
and open issues

• Introduction
• PAR Modelling State of the art, challenges
• Recent activities in SARNET- Experiments
  (JÜLICH)- Detailed PAR model (JÜLICH)- CFD
  modelling (IRSN, JÜLICH)
• Specific challenge PAR ignition modelling (IRSN)
• Perspectives for SARNET-2

35
Perspectives for SARNET-2

• Conclusions
• For advanced PAR studies a combination of
  integral and detailed models and experimentsis
  needed.
• Integral data available are complemented by
  detailed experiments at JÜLICH.
• IRSN and JÜLICH develop models with different
  approaches- black-box parameter model in
  TONUS/CFX (IRSN/JÜLICH)- detailed chemistry
  model in CFX (IRSN)- detailed mass transfer
  model in CFX (JÜLICH)
• Specific focus on ignition modelling with SPARK
  code at IRSN

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Perspectives for SARNET-2

• Present state
• Hydrogen Issue has been identified as high
  priority topic.
• The numerical modelling of the operational
  behaviour of PAR plays an important role in the
  assessment of the progression of severe accidents
  with hydrogen release into the containment.
• Advanced containment studies demand more detailed
  numerical models than presently used in order to
  provide useful complementary information in
  addition to the proven LP codes.
• In the frame of SARNET, the series of PARIS
  benchmarks has indicated the need for more
  detailed PAR models.

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Perspectives for SARNET-2

• Future joint objectives
• Development of enhanced models and strategies to
  investigate the local effects of PAR operation
  and hydrogen distribution.
• Significantly improve the tools (codes) for
  assessment of PAR and hydrogen behaviour in SA
  scenarios.

• Future joint activities
• Collaborative exchange on different modelling
  strategiesand experimental data
• Benchmarks on Advanced PAR Studies(continuation
  and further advancement of PARIS benchmarks)

38
Review of LPCFD recombiner modelling and
experimentsapplicability to reactor simulations
and open issuesErnst-Arndt Reinecke, Stephan
Kelm, Wilfried JahnJÜLICH, Safety Research and
Reactor TechnologyAhmed Bentaib, Nicolas
Meynet, Cataldo CaroliIRSN, Safety Reactor
Division
Thank you for your attention !
3rd European Review Meeting on Severe Accident
Research Nesseber, Bulgaria, 23-25 September, 2008