next generation reactor physics code development · shielding codes will not be discussed in this...
TRANSCRIPT
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IAEA Workshop on Advanced Code Suite For Design, Safety Analysis And Operation Of Heavy Water Reactors
(2-5 October, 2012, Ottawa, Marriott Hotel)
Dr. Alexandre Trottier (AECL, Chalk River Laboratories, Computational Reactor
Physics Branch)
AECL’s Next Generation
Reactor Physics Code
Development Program
AECL reactor physics codes
Reactors of interest
Challenges
Program objectives
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Introduction
Physics Codes at AECL
Lattice codes
WIMS-AECL
DRAGON
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Core codes
RFSP
TRIAD3
Other
WOBI
MCNP5
SERPENT
SCALE6
Shielding codes will
not be discussed in
this talk.
Three-Level Deterministic
Calculations
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Basic Lattice Properties
2D Lattice Cell Transport Calculation
Reactivity Devices
3D Super-Cell Transport Calculation
3D Reactor Diffusion Calculation
Steady State, Kinetics, Dynamics, etc.
Reactors of interest – ZED-2
Critical facility
Low-power & flux
– 5 W to 200 W
D2O-moderated tank
Aluminum vessel
Fuel lengths 250 cm to
300 cm
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227 sites
–18 control rods
–4 adjuster rods
84 – 93 driver fuel
rods.
2 loops for fuel
bundle testing
5 to 13 Mo-99 rods
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Reactors of Interest – NRU
Reactors of interest – SCWR
Direct cycle
Light water cooled
–25 MPa coolant pressure
–350°C inlet T
–650°C outlet T
Heavy water moderated
Strong axial gradients
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Challenges
Workforce demographics
Reactor design multiplicity
Legacy coding
Desire for an integrated code
Critical test facility capability maintenance
Critical test data for future fuel designs
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Some Specific Limitations in AECL
Physics Codes
Difficult to integrate within projected reactor code suite
Parallel computing not enabled for most codes
WIMS-AECL is 2D
RFSP and TRIAD3 are design specific
Calculation scheme is challenged for Th-based fuels
No deterministic uncertainty quantification capability
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Physics Code Development Objectives
Stand-alone or integrated operation with AECL reactor
code suite
Parallel computing for deterministic codes
Enable 3D lattice calculations
A core code for any thermal reactor, any fuel
Deterministic uncertainty quantification
Why should we ?
How could we do it ?
Feasibility study
Current efforts
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Mesh-Free Methods
WIMS-AECL versus Other Codes
WIMS-AECL
Number of meshes: < 500
Computing time: < 30 s
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TRITON/NEWT (SCALE)
Number of meshes: > 3600
Computing time: ~ 45 min
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A New Approximation Approach
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Eliminate meshing and specify an approximate solution
according to geometric shape of material regions
What is an R-Function?
Simple definition
Real continuous function, the properties of which depend on
the properties of its arguments.
Properties of interest
Objective
Analytical description of complex spatial domains.
Application
Numerical solution of boundary value problems.
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Three-valued logical algebra
Mathematical Description of Complex Domain
Euler diagrams as an illustration of set operators action
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Complement Intersection Union
R-Function Solid Modeling
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Set operators and R-operators correspondence
Explicit form of R-operators (R0 system)
Domain Functions
Consider each material region
Vi as a distinct spatial domain
specified by a function i.
Cylindrical domains V2, V3, V0:
Complex domain V1:
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Reference Solution
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Energy Group # 1 Energy Group # 75
Continuous flux reconstruction using the integral transport equation applied to
fine-mesh solution obtained by collision probability method.
Mesh-Free Lattice Physics
R-Function approach can express the flux solution
Now need to calculate it
Currently investigating the 2nd order even-parity
formulation
Some difficulties in approximating the high-order
harmonics with R-functions
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An Illustration of Angular Moments Shape
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Infinite Square Lattice of Cylindrical Fuel Elements
Spatial Distribution in Energy Group # 78 (Thermal Peak)
Zero order moment 1st order moment (cosine term)
Low Order Spherical Harmonics Moments
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Increasing the order, the spherical harmonics moments take
more complicated shape s.
2nd order moment 3rd order moment
Mesh-Free Diffusion Code
Solver for multigroup neutron diffusion equation
Variational formulation, using R-function method – D.V. Altiparmakov, Nucl. Sci. Eng. 92, 330-337 (1986)
Designed for maximum geometric flexibility
Just started development
–2D/3D benchmark geometry
–multigroup cross sections
–Fortran 95, Linux/Windows OS
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MCNP/KENO Model Generators
Uncertainty quantification
SALOME testing
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Other Efforts...
Model Generators for Uncertainty
Quantification
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MCNP/KENO model
generator toolset
Modular approach
Common component data
ZED-2
SCWR
Canadian power reactors
Uncertainty Quantification: Needs
and Issues
We need to:
–Assess impact of model data uncertainties
– Integrate nuclear data uncertainties
– Integrate to overall impact on safety analyses
Current tools are:
–WIMS-AECL + MS-Excel (Model data uncertainty)
–TSUNAMI (Nuclear data uncertainty)
Issues:
–TSUNAMI ?
–Compatibility with next generation suite ?
–Computing efficiency ?
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Planned Efforts in Uncertainty
Quantification
Modular SA/UQ system
–Enable use of different codes or data
–Automate model generation and execution
–Advanced input parameter sampling methods
– Integrated analyses of simulation results
…but we still need deterministic nuclear data uncertainty
analysis capability:
–Resonance self-shielding ?
–MC or 1st order perturbation theory ?
–Area of collaboration
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SALOME Platform for Numerical
Simulation
• Integration platform for
numerical simulation
• Under development at
CEA and others
• Rapid prototyping for
physics integration
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SALOME Testing Using CATHENA
and ELOCA
Used SALOME to couple two codes used in Canada
CATHENA: Canadian Algorithm for THErmal-hydraulic
Network Analysis
ELOCA: Element Loss Of Coolant Accident.
Experiment: PDF test simulating LBLOCA
Tested coupling against prior script-based setup
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The PBF LBLOCA Test
Fuel conditioning, 16 hours
in reactor
Blowdown
Power increase after ~50s
Sheath T ~ 1350 K
SCRAM, then reflood
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SALOME Test Results
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A. Zhuchkova, “Application of the SALOME Platform to the Loose Coupling of
the CATHENA AND ELOCA Codes”, 24th Nuclear Simulation Symposium, Ottawa
Next Steps with SALOME
Tight coupling of the codes CATHENA and ELOCA
Loose coupling with neutronics code (DONJON5)
Two possible benchmarks identified to date:
–BWR Turbine Trip
–Loss of Class IV Power at Gentilly-2
Would only test DONJON/CATHENA coupling
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We aim for high computing efficiency
Our codes will not be tied to a design
Our program is evolving
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Summary