Upload
vuongdieu
View
217
Download
2
Embed Size (px)
Citation preview
11
Integrated Multi-physics Simulation of Nuclear Components as an Essential Element in
Developing Predictive Capabilities for DEMO
A Cross Cutting Research Thrust for the Themes: Fusion Power and Plasma Material Interface
ReNeW Workshop March 2-4, 2009
UCLA
A. Ying, M. Abdou, S. Smolentsev, R. Munipalli, D. Youchison, P. Wilson, M. Sawan, B. Merrill
2
Introductory Remarks• Predicting the performance of a plasma chamber nuclear component
at present involves many technical disciplines and many computational codes such as:– MCNP for neutronics, CFD/thermofluid codes for FW surface
temperatures, and ANSYS for stress/deformation, etc.
• Because of the complex geometry of the fusion system, these codes should be run in 3D with a true geometric representation in order to achieve high quality prediction. – Maintaining consistency in the geometric representation among the
codes is challenging.
• Using the output from a code as an input to the other code currently involves lots of human effort, and machine time. – It is a source of error.
• The proposed research thrust is to remedy this deficiency, whilegiving a more realistic prediction of the phenomena and performances that occur in a fusion nuclear environment.
33
Integrated multi-physics simulation is necessary to model real-world situations, explore design options, and guide R&D
FW
Top Plate
SiC
Grid Plate Assy
Bottom Plate
Back Plate Assy
How will flow distribution be affected by the radiative heat flux, or downstream conditions?
Should the electrical conductivity of SiC FCI be tailored along the flow direction to control natural convection and MHD pressure loss?
How much heat will leak from Pb-17Li into the helium coolant? What is the actual Pb-17Li outlet temperature?
Pb-17Li flow streamlines inside a FCI duct (U contour/U,V vector)
How much tritium will be built-up in this recirculation zone?
DCLL Blanket Details and MHD Flow Features:Sharp gradients, extreme sensitivity to geometry,
Strong coupling across flow/heat/structures
Will structural deformations of FCI have a huge impact on MHD effects?
44
Example: Detailed DAG-MCNP 3-D neutronics analysis of TBM integrated with the surrounding water cooled frame and representation of exact source and other in-vessel components:
– yields total tritium production in the TBM that is 45% lower than the 1-D estimate
– yields total nuclear heating in the TBM that is 35% lower than the 1-D estimate of 0.574 MW
Mid-plane tritium production rate
Mid-plane nuclear heating (gamma: left; neutron: right)
Y2 plane nuclear heating (gamma: left; neutron: right)
Careful representation of a geometrically complex fusion component is essential to predict performance to a reasonable level of accuracy
DCLL TBM
PbLi Volume
W/cc
W/ccg/cc.s
5
Integrated multi-physics Simulation Predictive Capability (ISPC)
• A platform to streamline plasma chamber component design• Utilizing a CAD-based solid component model as the common element
across physical disciplines • The multi-physical phenomena occurring in a fusion nuclear chamber
system are modeled centering on CAD• Many interfaces must be designed to facilitate information transfer,
execution control, and post-processing visualization
Validation/Verification
CAD-Geometry
Mesh services Adaptive mesh/mesh refinement
Visualization
NeutronicsRadiation damage rates
Thermo-fluid
Structure/thermo-mechanics
Species (e.g. T2)transport
Electro-magnetics
Data Management: InterpolationNeutral format
MHD
Coupled effect
Special module
Database/Constitutive equations
RadioactivityTransmutation
Time step control for transient analysis
PartitioningParallelism
Safety
6
Radiativeheat flux
Pb-Li flow FCI
Helium-cooled structure
Utilizing a combination of fusion specific research codes and off-the-shelf third party software
Liquid metal flow in DCLL blanket channels
MHD velocity profile in the ducts computed using HIMAG
Example: MHD flows with heat transfer and natural convection computed using codes developed in the fusion community (such as HIMAG.)Traditional CFD/thermal analysis for non-conducting flows performed using off-the-shelf third party software – motivated by their speed and maturitySample analysis codes and mesh requirements in ISPC
System representation codeRELAP5-3DMELOCR
Safety
Unstructured second order mesh (node based)
COMSOLSpecies transport
Unstructured second order Hex/Tet mesh (node based)
ANSYS/ABAQUS
Structural analysis
Unstructured hybrid mesh (cell based)
HIMAGMHD
Unstructured hybrid mesh (cell based)
Fluent(Gambit)
Unstructured hybrid mesh (node based)
SC/Tetra & CFdesign
CFD/ Thermo-fluids
Unstructured Hex/Tet mesh (node based and edge based formulations)
ANSYS
Unstructured tetrahedral (Hex-) mesh (node based)
OPERA(Cubit)
Electro-magnetics
Unstructured tetrahedral mesh (node based)
Attila
Particle in cell (PIC)MCNPNeutronics
Mesh specificationAnalysis codePhysics
77
Fusion Research provides material database, constitutive equations, and special modules for ISPC
Discrete element simulation of pebble bed provides contact forces at critical pebble/pebble contact areas- eliminating potential design flaws
FEM simulation needs to integrate with a Thermo-fluid code to account accurate temperature boundary conditionsNeeds incorporating fusion specific constitutive equations into user function of structural code. E.g.:
Ceramic breeder
Be pebbles
FW panel
with He channels
Internal cooling plate
Elastic/Plastic deformation region
T < 600 oC
High creep (thermal and irradiation) deformation region
Plot showing how forces propagate through pebble contacts
orthorhombic packing obtained numerically
Example: Pebble bed thermomechanics
σε )/105.21exp(104.1 32.
Txx −− −=
88
The computational meshes, even through are derived from a common CAD model, for different physical analysis have different requirements. The transfer of information between disciplines across various computational meshes has to be accurate and satisfies physical conservation laws.
CAD Model
MHD meshFine mesh resolution in the Hartmann layers
Stress analysis mesh
No discretizationin the fluid domain
∑∑
∑∑=
=
nodes Solidfaces Fluid
nodes Solidfaces Fluid
,
solidfluid
solidfluid
MM
FFvv
vv
• Conservation of forces and moments have to be ensured while translation between computational meshes
Coupling across Physical Disciplines and Data Interpolation
• Total heat deposition qcomputed from a neutronicssolver going into a fluids solver must be conserved (in each material)
99
An effort has begun to develop this integrated multi-physics simulation tool for ITER FW/Shield and TBM Designs
CFD & Heat Transfer
Neutron Source Modeling
Radiation TransportDetailed distribution of nuclear heating
Large orthogonal regular grids in MCNP (~26M voxels)
Large unstructured hybrid mesh in CFD (~15M elements)
Based on MOAB infrastructure (KD tree for MCNP mesh, interpolation to centroid or vertices of CFD cells)
Example: Integrated ITER FW Neutronics and CFD/Thermal Analysis
1010
ISPC – an effective mechanism to integrate results of ongoing R&D and continuously evolve to Validated Predictive Capability for DEMO
Ultimate Goal: Validated Predictive Capability for DEMO
ISPCSingle- and Multiple-effect Experiments
Material DatabaseConstitutive Correlations/
Models
TBM Design and Data Interpretation
ITER TBMFNF/CTF test data
ValidationInitial Benchmark
FNF/CTF Chamber Design
• Compiles data and knowledge base derived from many fusion R&Ds in out-of-pile facilities and fission reactors
• Provides high level of accuracy, reduces substantially risk and cost for the development of complex multi-dimensional system of the plasma chamber in-vessel components
1111
A Research Thrust ISPC provides a most effective, cost- and time-saving approach to develop predictive
capability for DEMO
• To structure the advancement of fusion energy research • To document systematically data, knowledge base, and validation
cases (necessary for QA) for DEMO – preserve investments • To maintain fusion nuclear science and technology research a
cutting edge venture – virtual reality • To provide a natural interface for Fusion Simulation Project (FSP)
through an accurate prediction of the plasma facing surface temperature, enabling realistic characterization of plasma shotsvis-à-vis to its surroundings
It is essential that such a Research Thrust be recommended by ReNeW
1212
Summary• The ISPC represents a paradigm shift in the manner in which
multidisciplinary simulations are performed.– From the outset, the emphasis will be on multi-physics
integration rather than separate threads of model development that might eventually come together at some point in the future.
• We strongly recommend a new Research Thrust aimed at developing Integrated multi-physics Simulation Predictive Capability (ISPC) for Fusion Nuclear Components. – This will allow faster and more effective approach toward
developing Validated/Verified Predictive Capability for DEMO. – In the near term, ISPC will be an important tool for:
• reducing design uncertainties • facilitating the understand of the experimental results• providing a fully integrated, high-fidelity simulation for performance
prediction of FNF/CTF fusion plasma chamber systems – Results from these near-term experiments facilities will also help
validate the ISPC for eventual use in DEMO.