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Thermal Hydraulic Challenges for
Liquid Metal Fast Reactors in
Europe
F. Roelofs, A. Shams, K. van Tichelen,
A. Gerschenfeld, A. Batta, I. DiPiazza
IAEA, Vienna, Austria
15 April 2014
Contents
• Introduction
• Liquid Metal Fast Reactors in Europe
• Thermal Hydraulic Challenges
– Identification process
– Liquid Metal Turbulence Heat Transfer
– LMFR Fuel Assemblies
– LMFR Pool
– Thermal Hydraulic System Behavior
• Summary of Main Challenges for Future
Development
• Acknowledgement
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Introduction
3
Introduction
• Nuclear power plays and probably will play important role in energy production
• Large role is attributed world-wide to fast reactors
• Thermal-hydraulics is considered as key issue
• EU FP7 Project THINS (Thermal Hydraulics of
Innovative Nuclear Systems) and preparation of new framework progam Horizon 2020
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Liquid Metal Fast Reactors in Europe
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Liquid Metal Fast Reactors in EuropeSodium: ASTRID
• ASTRID = Advanced Sodium
Technological Reactor for Industrial
Demonstration
• Characteristics
– Sodium coolant
– 1500 MWth / 600 MWe
• Purpose
– Sodium Fast Reactor Technology
Demonstration
– Maintaining and rebuilding sodium fast
reactor expertise
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Liquid Metal Fast Reactors in EuropeLead: ALFRED
• ALFRED = Advanced Lead Fast
Reactor European
Demonstrator
• Characteristics
– Lead coolant
– 300 MWth / 125 MWe
• Purpose
– Lead fast reactor demonstration
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Liquid Metal Fast Reactors in EuropeLead: SEALER
• SEALER = Swedish Advanced Lead
Reactor
• Characteristics SEALER-3
– Lead coolant
– 8 MWth / 3 MWe
• Purpose
– Electricity production for isolated (arctic) communities
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Liquid Metal Fast Reactors in EuropeLead-bismuth: MYRRHA
• MYRRHA = Multi-purpose hYbrid Research Reactor for
High-tech Applications
• Characteristics
– Critical and ADS mode
– Lead Bismuth Eutectic coolant
• Purpose
– Fast spectrum irradiation facility
– European technology pilot plant for LFR
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Identification Process
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Identification Process
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Literature &
conferences EU Framework ProjectsInternational
Organizations
Challenges
EU System Designers
IdentificationIdentification
PrioritizationPrioritization
Liquid Metal Turbulence Heat Transfer
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Liquid Metal Turbulence Heat Transfer
• Current practice: Reynolds analogy for heat transfer
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Velocity
Temperature (Pr = 1) Temperature (Pr = 0.01)
Field ScalesBoundary
Layer
Velocity Small Thin
Temperature (Pr = 1) Small Thin
Temperature (Pr = 0.01) Large Thick
Liquid Metal Turbulence Heat TransferStatus Model Development 2014
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Local Temperature Dependent Prandtl Number
Reynolds Analogy
AHFM-NRG
Flow Convection Regimes
natural mixed forced
Flu
ids
(P
ran
dtl
nu
mb
er)
air
liquid
meta
ls
Look-up Tables?
AHFM-TransAt?
?
Mixed
Law-of-the-Wall?
Liquid Metal Turbulence Heat Transfer
Challenges:
• Further Assessment– Mixed convection in liquid metals
– Non wall-bounded flows (e.g. jets)
– Complex (industrial) geometries
• Model robustness evaluation by implementation and evaluation in other codes
• Further development for simultaneous application in all convection regimes
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LMFR Fuel Assemblies
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LMFR Fuel AssembliesWire Wraps
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• Application: ASTRID / MYRRHA
• Status:– Hydraulic reference data available only from
high fidelity simulations by ANL
– Thermal data including blockages available in near future from EU SEARCH and MAXSIMA projects
• Challenges:– Reference data
• MIR Experiments to confirm Hydraulics
• High Fidelity CFD including heat transport in addition to thermal data from experiments which is always limited
– Blockage formation by accumulation of small particles
217 pin sodium bundle LES (ANL)
solid
transparent
LMFR Fuel AssembliesGrid Spacers
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• Application: ALFRED
• Status:
– Numerical approaches with little validation
• Challenges:
– Reference data for validation of numerical
approaches
• Hydraulics experiments
• Thermal hydraulics experiments
• High Fidelity simulations
– Evaluation of influence of blockages ALFRED spacer design (ANS)and CFD assessment (NRG)
LMFR Fuel AssembliesInter-wrapper flow
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• Status:
– Limited reference data (PLANDTL
experiments)
• Challenges:
– Reference data for validation of numerical
approaches
PLANDTL Inter-wrapper flow experiments (Kamide et al., 2001)
LMFR Fuel AssembliesComplete Core Simulation
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• Status:
– Subchannel or system thermal hydraulics codes
• Challenges:
– Improvement of existing approaches
– Development of new approaches to obtain more
details or improved accuracy
AP-CGCFD (Viellieber & Class, 2012)
LMFR Pool
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LMFR Pool
• Status:– Designs specific experiments and
simulations
– No validation
• Challenges:– Generic validation for numerical
approaches
– Link hydraulics with thermal hydraulics
– Transition from forced to natural convection cooling
– Evaluation of stratifications
– Numerical modelling of integrated complex components (core, HEX, pumps, fuel handling systemsF)
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RAMONA facility (KIT)
JESSICA facility (CEA)
LMFR Pool
• Development:
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MYRRHAbelle water mock-up (VKI)MYRRHA design (SCK-CEN) ESCAPE LBE mock-up (SCK-CEN)
LMFR Pool
• CIRCE experiments– Transition forced to natural
convection
• Qualification of heat transfer and stratification modeling in CFD
• Prediction of convection patterns in CFD
• Validation of system codes
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heated section
Argon injection
riser
gas separator
heat exchanger
CIRCE facility (ENEA)
LMFR Pool
• Numerical Modelling:
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MYRRHA numerical model (VKI)
- Conjugate heat transfer
- 10-30 million computational volumes
MYRRHA numerical model (CRS4)
- Conjugate heat transfer
- Five fluid regions to describe the core
- Explicit free surface modelling
Thermal Hydraulic System Behavior
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Thermal Hydraulic System BehaviorSystem Code
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Core :
axial
modules
Hot pool
Cold pool
IHX
diagrid
Primary
pumps
Hot pool
Primary
pumps
IHX
Cold
pool
core
CATHARE input deck (CEA)
Thermal Hydraulic System BehaviorMulti Scale
• Code Coupling
– CATHARE – TRIO_U (CEA)
– Phenix natural convection test
– Dedicated post-processing tools enabling 3D
visualization (using 3D glasses) of sodium flow patterns
in reactor pool
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CATHARE – TRIO_U (CEA)
Thermal Hydraulic System BehaviorSystem Code vs. Multi Scale
• System Code– limited stratification
prediction
– stratification prediction linked to discretization
– limited prediction 3D phenomena in complex geometry
• Multi Scale– Domain selection
(domain decomposition or overlapping, iterative method)
– Allows to predict properly local 3D behavior
– CPU intensive (esp. for long transients)
– Validation
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experimentsystem code
coupled
Main Challenges for Future Development
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Main Challenges for Future Development
• Status of LMFR thermal-hydraulics developments & future challenges:
– Liquid Metal Turbulence Heat Transfer
• Further validation of the promising approaches using:
– Geometrically more complex cases
– Flows not bounded by walls
• Development of approaches allowing application in all flow regimes simultaneously
– Fuel Assemblies
• Validation of the flow hydraulics in a wire wrapped rod bundle using high fidelity
numerical reference data or experimental data
• Further development of complete core approaches
– Pool Thermal Hydraulics
• Validation: Flow and heat transfer
• Include heat transport through inner structures in the pool
– Thermal Hydraulic System Behavior
• Include 3D effects from experiments or CFD simulations in STH codes
• Couple system thermal hydraulic codes with CFD codes
• Validation of the coupling methodologies and application
• Transition from forced to natural convection
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National Program on Thermal
Hydraulics Modelling and
Simulation for Fast Reactors
F. Roelofs
IAEA, Vienna, Austria
14 April 2014
Dutch National Program
• Dutch National Program– Four policy targets of Dutch government
– NRG budget 2014 ~ 8 M€
– ‘Optimization of Solutions for Nuclear Waste’
• Characterization of nuclear waste and final disposal
• Minimization of nuclear waste and fast reactors
– Largely Integrated in EU framework
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System Thermal HydraulicsCodes
• RELAP
• MELCOR
• TRACE
• SPECTRA
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Mainly LWR Applications
Flexible Applications
System Thermal HydraulicsSPECTRA
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• Sophisticated Plant Evaluation Code for Thermal-hydraulic Response Assessment.– Fully integrated system analysis
code
– Thermal Hydraulics• Cooling systems
• Emergency & control systems
• Containment
• Reactor building
– Flexible input module for physical properties and correlations enabling application of different coolants
– Flexible in applications: PWR, BWR, HTR, LFR, SFR...
– V&V analysis covering code to code, theoretical as well as experimental and operation cases
System Thermal HydraulicsSPECTRA
• Coolant Selection– Flexible input module for
physical properties and correlations
• Water
• Helium
• Sodium / Lead
• Main code for fast reactor applications– Sodium (ESFR / EBR-II)
– Lead (ELSY / ALFRED)
• Fast Reactor Developments– Mainly further V&V
– ‘Customer’ request
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SPECTRA EBR-II Model
Computational Fluid DynamicsCodes
• STAR-CCM+
• FLUENT
• CFX
• NEK5000
• OpenFOAM
• Code selection on case by case basis, driven
by code competences, user preferences, and
license availability
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NEK5000
Computational Fluid DynamicsFuel Assembly & Core Modelling
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Sub-channel LevelFuel Assembly LevelFull Core Level
CFD
Multiscale
• Validate CFD at sub-channel level
• Scale up (reduced resolution) to fuel assembly level
• Scale up (low resolution) to full core level
Computational Fluid DynamicsFuel Assembly & Core Modelling
• Heat transport (AHFM-NRG)– increasing accuracy and predictability
• Single Subchannel– spacer assessment
– validation
• Down scaled fuel assembly– 7 & 19 pins (validation)
– Experimental blockages (validation)
• Fuel assembly– 127 pin MYRRHA including inlet and
outlet headers
– Partial blockage
• Multiple fuel assemblies– Complete and partial blockages
– Inter wrapper flow
• Complete core– Inter wrapper flow
– Blockages
– Primary system modelling
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Computational Fluid DynamicsPool Modelling
• Scaling Analyses
– MYRRHA - ESCAPE
• Gas Entrainment
– ESFR
• Sloshing
– ELSY
• Development
– Modelling complete fast
reactor primary system
• Stratification
• Transients
• Transition forced-
natural
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Scaling simulations
Full scale – velocity scale – Froude scale
Computational Fluid DynamicsSodium Fire Modelling
• Model Implementation Check– Pool
• Evaporation and combustion of sodium
• Validation– Spray
• Validation to combustion of single falling sodium droplet
• Application– Combined sodium spray and pool fire in
closed environment
• Status– Developed method suitable for scoping
analyses
– Further validation required for safety analyses
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Multi Scale Thermal Hydraulics
• Development of coupling 3D CFD to 1D STH
– Coupling mechanisms tested by coupling STH-STH
(time and space) and CFD-CFD (space)
– Proof of Principle (STH-CFD)
• Heat diffusion in 1D pipe
• Domain overlap
• Treatment of boundary conditions
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T & Q
STH
CFD
Questions?
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