Nuclear Material Particle Fuel

Reduces the Material block length for TRISO fuel within input files.

Description

This NuclearMaterialParticleFuel action reduces BISON input file length by internally generating the Materials required for simulating TRISO nuclear fuel.

warning:For TRISO Use Only

This action is designed for use with only TRISO simulations.

User-based Interface

To reduce the length and complexity of necessary blocks for simulations, an extensive standardization of operating conditions has been utilized within the NuclearMaterials.

All of the blocks, generated with the default parameter settings, are shown in Table 1, Table 2, and Table 3. These blocks are created internally, based on the Fuel Models and/or physics conditions shown. Additional parameters for each created class can be found below.

note

Certain parameters are determined internally to further reduce input length and complexity.

The classes in Table 1 are automatically created when using NuclearMaterialParticleFuel depending on the Fuel Models and Fission operation used as well as what occurs under Physics conditions.

Table 1: Material classes created by the NuclearMaterialParticleFuel action

Created Classes	Pre-Set Parameters	Block Name	Layers Models	Fission Operation
StrainAdjustedDensity		'fuel_block_name' + "_density"		Normal
GenericFunctionMaterial	prop_name = fission_rate	fission_rate		Normal
	prop_values = fission_rate
GenericFunctionMaterial	prop_name = fast_neutron_fluence	fast_neutron_fluence		Normal
	prop_values = fast_neutron_fluence
FastNeutronFlux	prop_name = fast_neutron_flux	fast_neutron_flux		Normal
	prop_values = fast_neutron_flux
UCOFGR		fission_gas_release		Normal
ArrheniusDiffusionCoef	arrhenius_prpty_name = "arrhenius_diffusion_coef_" + 'elem_name'	'fuel_block_name' + "_conc_" + 'elem_name'	Diffusion	Normal
SpeciesSourceMaterial	property_name = 'elem_name' + "_generation"	"mass_source" + 'elem_name' + "_property"	Diffusion	Normal
BufferThermal		Buffer_thermal	Thermal	Normal
MonolithicSiCThermal		SiC_thermal	Thermal	Normal

HeatConductionMaterial		IPyC_thermal/OPyC_thermal	Thermal	Normal

note

Either the fast_neutron_flux or fast_neutron_fluence should be selected, but not both at the same time. When either flux or fluence is selected, a function describing it must be included.

The classes in Table 2 are only created when Thermal or if any Fission occurs under the Fission Operation conditions.

Table 2: Auxiliary classes created by the NuclearMaterialParticleFuel action

Created Auxiliary Classes	Type	Pre-Set Parameters	Block Name	Physics/Layers Models
StrainAdjustedDensity	AuxKernel	variable = density	'fuel_block_name' + "_density"
		property = density
StrainAdjustedDensity	AuxVariable		density
Diffusion Coefficient	AuxKernel	variable = 'elem_name' + "_diff_coef"	'fuel_block_name' + "_" + 'elem_name' + diff_coef\| Diffusion
		property = "arrhenius_diffusion_coef_" + 'elem_name'
Diffusion Coefficient	AuxVariable		'elem_name' + diff_coef	Diffusion
Thermal Conductivity	AuxKernel	variable = thermal_conductivity	'fuel_block_name' + "_thermal_conductivity"	Thermal
		property = thermal_conductivity
Thermal Conductivity	AuxVariable		thermal_conductivity	Thermal
Specific Heat	AuxKernel	variable = specific_heat	'fuel_block_name' + "_specific_heat"	Thermal
		property = specific_heat
Specific Heat	AuxVariable		specific_heat	Thermal
Fast Neutron Fluence	AuxKernel	\|fast_neutron_fluence	Normal (Fission)
Fast Neutron Fluence	AuxVariable	\|fast_neutron_fluence	Normal (Fission)
Concentration	Variable		conc + 'elem_name'	Diffusion
Temperature	Variable		temperature	Thermal
HeatConduction	Kernel	variable = temperature	fuel_heat	Thermal
		extra_vector_tags = ref
HeatConductionTimeDerivative	Kernel	variable = temperature	fuel_heat_dt	Thermal
		extra_vector_tags = ref
ArrheniusDiffusion	Kernel	arrhenius_prpty_name = arrhenius_diffusion_coef_" + 'elem_name'	'fuel_block_name' + "_mass_" + 'elem_name'	Diffusion
		variable = "conc_" + 'elem_name'
		extra_vector_tags = ref
TimeDerivative / MassLumpedTimeDerivative	Kernel	variable = "conc_" + 'elem_name'	'fuel_block_name' + "_mass_" + 'elem_name' + _dt	Diffusion

Table 3: Actions created by the NuclearMaterialParticleFuel action

Created Actions	Pre-Set Parameters	Block Name	Physics/Layers Model Conditions
TensorMechanicsAction	volumetric_locking_correction = false	Physics/SolidMechanics/QuasiStatic	Mechanics
	automatic_eigenstrain_names = true
	decomposition_method = EigenSolution
	strain = FINITE

## Example Simple Input Syntax

NuclearMaterials simplifies Material block inputs by applying standard parameter and classes depending on the simulation. It is possible to only replace the Materials blocks in an input file with the equivalent NuclearMaterialParticleFuel. This procedure greatly reduces the length and complexity of the the necessary inputs while fully retaining the same functionality and end results. An example of this can be seen below.

Fission Operation

note

This required parameter describes the characteristic type of fission study that will occur, i.e. Normal. This must be placed under the NuclearMaterials block heading and cannot be placed under sub-blocks such as UCO.

Fuel Model Parameters

Diffusion : Models diffusion of specified elements through the fuel.
Burnup : Models fission rate equations describing the evolution of the concentrations of each heavy element with fuel.

Expanded Fuel Material Block


[Materials]
  [fission_rate]
    type = GenericFunctionMaterial
    prop_names = fission_rate
    prop_values = fission_rate
  []
  [fast_neutron_fluence]
    type = GenericFunctionMaterial
    prop_names = fast_neutron_fluence
    prop_values = fast_neutron_fluence
  []
  [UCO_burnup]
    type = TRISOBurnup
    initial_density = 10400.0
  []
  [UCO_thermal]
    type = UCOThermal
    block = fuel
    temperature = temperature
  []
  [UCO_density]
    type = StrainAdjustedDensity
    block = fuel
    density = 10400.0
  []
  [fission_gas_release]
    type = UCOFGR
    block = fuel
    average_grain_radius = 10e-6
    temperature = temperature
    triso_geometry = particle_geometry
  []
  [fuel_conc_Ag]
    type = ArrheniusDiffusionCoef
    block = fuel
    d1 = 6.7e-9               # m^2/s
    q1 = 165e3                # J/mol
    temperature = temperature
    arrhenius_prpty_name = arrhenius_diffusion_coef_Ag
  []
  [mass_source_Ag_property]
    type = SpeciesSourceMaterial
    property_name = Ag_generation
    kind = Ag
    block = fuel
  []
  [fuel_conc_Cs]
    type = ArrheniusDiffusionCoef
    block = fuel
    d1 = 5.6e-8               # m^2/s
    q1 = 209e3                # J/mol
    temperature = temperature
    arrhenius_prpty_name = arrhenius_diffusion_coef_Cs
  []
  [mass_source_Cs_property]
    type = SpeciesSourceMaterial
    property_name = Cs_generation
    kind = Cs
    block = fuel
  []
  [fuel_conc_Sr]
    type = ArrheniusDiffusionCoef
    block = fuel
    d1 = 2.2e-3               # m^2/s
    q1 = 488e3                # J/mol
    temperature = temperature
    arrhenius_prpty_name = arrhenius_diffusion_coef_Sr
  []
  [mass_source_Sr_property]
    type = SpeciesSourceMaterial
    property_name = Sr_generation
    kind = Sr
    block = fuel
  []
[]

Equivalent Simplified NuclearMaterial Fuel Block

[NuclearMaterials<<<{"href": "../index.html"}>>>]
  fission_operation<<<{"description": "Type of fission occuring in this simulation."}>>> = 'Normal'
  physics<<<{"description": "Type(s) of physics used on this block."}>>> = 'Thermal'
  initial_temperature<<<{"description": "Initial temperature in Kelvins."}>>> = 923.15
  elements_tracked<<<{"description": "The elements tracked within TRISO simulations."}>>> = 'Ag'
  elements_initial_concentration<<<{"description": "Relative ratio of element concentration"}>>> = '0.0'
  element_scaling<<<{"description": "Relative scaling of element percentages"}>>> = '1e14'
  use_automatic_differentiation<<<{"description": "Flag to use automatic differentiation (AD) objects when possible"}>>> = false
  [ParticleFuel<<<{"href": "index.html"}>>>]
    [UCO]
      fuel_type<<<{"description": "Type of fuel used in TRISO simulation.  The choices are: UO2 UCO"}>>> = UCO
      particle_fuel_models<<<{"description": "Type(s) of physics models used on this block.   The choices are: Burnup Diffusion Swelling ThermalExpansion Creep"}>>> = 'Burnup Diffusion'
      diffusion_1st_coefficients<<<{"description": "1st diffusion coefficient."}>>> = '6.7e-9'
      diffusion_1st_activation_energies<<<{"description": "Diffusion activation energies."}>>> = '165e3'
      diffusion_2nd_coefficients<<<{"description": "2nd diffusion coefficient"}>>> = '0'
      diffusion_2nd_activation_energies<<<{"description": "Second diffusion activation energy"}>>> = '0'
      block<<<{"description": "The list of ids of the blocks (subdomain) that the stress divergence kernels will be applied to"}>>> = fuel
      fission_rate_function<<<{"description": "The function that describes the fission rate."}>>> = fission_rate
      fast_neutron_fluence_function<<<{"description": "Function that describes the fast neutron fluence."}>>> = fast_neutron_fluence
      initial_density<<<{"description": "Initial density in kg-UO2/m^3"}>>> = 10400.0
      average_grain_radius<<<{"description": "Average grain radius of fuel"}>>> = 10e-6
      triso_geometry<<<{"description": "TRISOGeometry user object name"}>>> = particle_geometry
    []
  []
[]

Example Fully Reduced Input Syntax

Input file length and complexity can be reduced even further by use of additional Physics and/or LayersModels block parameters, in addition to applying common parameters to sub-blocks under the NuclearMaterials header.

Physics parameters

Mechanics : This will create the TensorMechanicsAction block(s) under which it is listed. If listed under the NuclearMaterial block header, then this will be applied to all blocks under the header.
Thermal : This will create the temperature variable, the Kernel blocks HeatConduction and HeatConductionTimeDerivative needed to model thermal effects for fuel materials.

Expanded Fuel Block


[Variables]
  [temperature]
    initial_condition = 923.15
  []
[]
[AuxVariables]
  [fission_rate]
    block = fuel
    order = CONSTANT
    family = MONOMIAL
  []
  [burnup]
    block = fuel
    order = CONSTANT
    family = MONOMIAL
  []
  [fast_neutron_fluence]
    order = CONSTANT
    family = MONOMIAL
  []
  [density]
    order = CONSTANT
    family = MONOMIAL
  []
  [thermal_conductivity]
    order = CONSTANT
    family = MONOMIAL
  []
  [specific_heat]
    order = CONSTANT
    family = MONOMIAL
  []
  [fis_gas_produced]
    order = CONSTANT
    family = MONOMIAL
  []
  [fis_gas_released]
    order = CONSTANT
    family = MONOMIAL
  []
[]
[Kernels]
  [heat_dt]
    type = HeatConductionTimeDerivative
    variable = temperature
  []
  [heat]
    type = HeatConduction
    variable = temperature
    extra_vector_tags = 'ref'
  []
  [heat_source]
    type = NeutronHeatSource
    variable = temperature
    block = fuel
    fission_rate = fission_rate
    extra_vector_tags = 'ref'
  []
[]
[AuxKernels]
  [fissionrate]
    type = MaterialRealAux
    variable = fission_rate
    property = fission_rate
    block = fuel
    execute_on = timestep_begin
  []
  [burnup]
    type = MaterialRealAux
    variable = burnup
    property = burnup
    block = fuel
    execute_on = timestep_begin
  []
  [fast_neutron_fluence]
    type = MaterialRealAux
    variable = fast_neutron_fluence
    property = fast_neutron_fluence
    block = 'fuel buffer IPyC SiC OPyC'
    execute_on = timestep_begin
  []
  [density]
    type = MaterialRealAux
    variable = density
    property = density
    block = 'fuel buffer IPyC SiC OPyC'
    execute_on = 'initial linear'
  []
  [thermal_conductivity]
    type = MaterialRealAux
    variable = thermal_conductivity
    property = thermal_conductivity
    block = 'fuel buffer IPyC SiC OPyC'
    execute_on = timestep_end
  []
  [specific_heat]
    type = MaterialRealAux
    variable = specific_heat
    property = specific_heat
    block = 'fuel buffer IPyC SiC OPyC'
    execute_on = timestep_end
  []
  [fis_gas_produced]
    type = MaterialRealAux
    variable = fis_gas_produced
    property = fis_gas_produced
    block = fuel
    execute_on = linear
  []
  [fis_gas_released]
    type = MaterialRealAux
    variable = fis_gas_released
    property = fis_gas_released
    block = fuel
    execute_on = linear
  []
[]
[Materials]
  [fission_rate]
    type = GenericFunctionMaterial
    prop_names = fission_rate
    prop_values = fission_rate
  []
  [fast_neutron_fluence]
    type = GenericFunctionMaterial
    prop_names = fast_neutron_fluence
    prop_values = fast_neutron_fluence
  []
  [UCO_burnup]
    type = TRISOBurnup
    initial_density = 10400.0
  []
  [UCO_thermal]
    type = UCOThermal
    block = fuel
    temperature = temperature
  []
  [UCO_density]
    type = StrainAdjustedDensity
    block = fuel
    density = 10400.0
  []
  [fission_gas_release]
    type = UCOFGR
    block = fuel
    average_grain_radius = 10e-6
    temperature = temperature
    triso_geometry = particle_geometry
  []
  [fuel_conc_Ag]
    type = ArrheniusDiffusionCoef
    block = fuel
    d1 = 6.7e-9               # m^2/s
    q1 = 165e3                # J/mol
    temperature = temperature
    arrhenius_prpty_name = arrhenius_diffusion_coef_Ag
  []
  [mass_source_Ag_property]
    type = SpeciesSourceMaterial
    property_name = Ag_generation
    kind = Ag
    block = fuel
  []
  [fuel_conc_Cs]
    type = ArrheniusDiffusionCoef
    block = fuel
    d1 = 5.6e-8               # m^2/s
    q1 = 209e3                # J/mol
    temperature = temperature
    arrhenius_prpty_name = arrhenius_diffusion_coef_Cs
  []
  [mass_source_Cs_property]
    type = SpeciesSourceMaterial
    property_name = Cs_generation
    kind = Cs
    block = fuel
  []
  [fuel_conc_Sr]
    type = ArrheniusDiffusionCoef
    block = fuel
    d1 = 2.2e-3               # m^2/s
    q1 = 488e3                # J/mol
    temperature = temperature
    arrhenius_prpty_name = arrhenius_diffusion_coef_Sr
  []
  [mass_source_Sr_property]
    type = SpeciesSourceMaterial
    property_name = Sr_generation
    kind = Sr
    block = fuel
  []
[]

Fully Simplified Fuel Block

[NuclearMaterials<<<{"href": "../index.html"}>>>]
  fission_operation<<<{"description": "Type of fission occuring in this simulation."}>>> = 'Normal'
  physics<<<{"description": "Type(s) of physics used on this block."}>>> = 'Thermal'
  initial_temperature<<<{"description": "Initial temperature in Kelvins."}>>> = 923.15
  elements_tracked<<<{"description": "The elements tracked within TRISO simulations."}>>> = 'Ag'
  elements_initial_concentration<<<{"description": "Relative ratio of element concentration"}>>> = '0.0'
  element_scaling<<<{"description": "Relative scaling of element percentages"}>>> = '1e14'
  use_automatic_differentiation<<<{"description": "Flag to use automatic differentiation (AD) objects when possible"}>>> = false
  [ParticleFuel<<<{"href": "index.html"}>>>]
    [UCO]
      fuel_type<<<{"description": "Type of fuel used in TRISO simulation.  The choices are: UO2 UCO"}>>> = UCO
      particle_fuel_models<<<{"description": "Type(s) of physics models used on this block.   The choices are: Burnup Diffusion Swelling ThermalExpansion Creep"}>>> = 'Burnup Diffusion'
      diffusion_1st_coefficients<<<{"description": "1st diffusion coefficient."}>>> = '6.7e-9'
      diffusion_1st_activation_energies<<<{"description": "Diffusion activation energies."}>>> = '165e3'
      diffusion_2nd_coefficients<<<{"description": "2nd diffusion coefficient"}>>> = '0'
      diffusion_2nd_activation_energies<<<{"description": "Second diffusion activation energy"}>>> = '0'
      block<<<{"description": "The list of ids of the blocks (subdomain) that the stress divergence kernels will be applied to"}>>> = fuel
      fission_rate_function<<<{"description": "The function that describes the fission rate."}>>> = fission_rate
      fast_neutron_fluence_function<<<{"description": "Function that describes the fast neutron fluence."}>>> = fast_neutron_fluence
      initial_density<<<{"description": "Initial density in kg-UO2/m^3"}>>> = 10400.0
      average_grain_radius<<<{"description": "Average grain radius of fuel"}>>> = 10e-6
      triso_geometry<<<{"description": "TRISOGeometry user object name"}>>> = particle_geometry
    []
  []
[]

The eigenstrain names must be included in the SolidMechanics QuasiStatic Action following the naming convention created by this class. The easiest method to ensure this continutity is to include Mechanics in the physics input parameter. By default, this will select automatic_eigenstrain_names = true.

warning

automatic_eigenstrain_names = true, the eigenstrain_names will be populated under restrictive conditions for classes such as CompositeEigenstrain, ComputeReducedOrderEigenstrain, and RankTwoTensorMaterialADConverter. The input components for these classes are not included in the eigenstrain_names passed to the TensorMechanicsAction. Set the automatic_eigenstrain_names = false and populate this list manually if these components need to be included.

Example Input File Syntax

-!listing test/tests/triso/base_irradiation/triso_accident_action.i block=NuclearMaterials/ParticleFuel/UO2-

Input Parameters

particle_fuel_modelsType(s) of physics models used on this block. The choices are: Burnup Diffusion Swelling ThermalExpansion Creep
C++ Type:MultiMooseEnum
Options:Burnup, Diffusion, Swelling, ThermalExpansion, Creep
Controllable:No
Description:Type(s) of physics models used on this block. The choices are: Burnup Diffusion Swelling ThermalExpansion Creep

Required Parameters

C_UCarbon to uranium ratio
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Carbon to uranium ratio
O_UOxygen to uranium ratio
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Oxygen to uranium ratio
active__all__ If specified only the blocks named will be visited and made active
Default:__all__
C++ Type:std::vector<std::string>
Controllable:No
Description:If specified only the blocks named will be visited and made active
add_variablesFalseAdd the displacement variables
Default:False
C++ Type:bool
Controllable:No
Description:Add the displacement variables
additional_physicsType(s) of physics used on this block. The choices are: Mechanics Thermal
C++ Type:MultiMooseEnum
Options:Mechanics, Thermal
Controllable:No
Description:Type(s) of physics used on this block. The choices are: Mechanics Thermal
automatic_eigenstrain_namesTrueCollects all material eigenstrains and passes to required strain calculator within the solid mechanics physics internally.
Default:True
C++ Type:bool
Controllable:No
Description:Collects all material eigenstrains and passes to required strain calculator within the solid mechanics physics internally.
average_grain_radius1e-05Average grain radius of fuel
Default:1e-05
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Average grain radius of fuel
axial_power_profileFunction that describes the axial power profile as a function of axial position and time.
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function that describes the axial power profile as a function of axial position and time.
burnup_functionBurnup function
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Burnup function
concentration_density1Coefficient to multiply by the body force term
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Coefficient to multiply by the body force term
cutoff_neutron_flux0The cutoff fast neutron flux for enabling the Booth fractional release calculations during accident simulation conditions.
Default:0
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The cutoff fast neutron flux for enabling the Booth fractional release calculations during accident simulation conditions.
d1_functionFunction to be multiplied by d1
C++ Type:std::vector<FunctionName>
Unit:(no unit assumed)
Controllable:No
Description:Function to be multiplied by d1
d1_function_variableVariable to be used when evaluating d1_function. If not given, time will be used.
C++ Type:std::vector<std::string>
Controllable:No
Description:Variable to be used when evaluating d1_function. If not given, time will be used.
decomposition_methodEigenSolutionMethods to calculate the finite strain and rotation increments
Default:EigenSolution
C++ Type:MooseEnum
Options:TaylorExpansion, EigenSolution, HughesWinget
Controllable:No
Description:Methods to calculate the finite strain and rotation increments
densityInitial fuel density
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Initial fuel density
diffusion_1st_activation_energiesDiffusion activation energies.
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:Diffusion activation energies.
diffusion_1st_coefficients1st diffusion coefficient.
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:1st diffusion coefficient.
diffusion_2nd_activation_energiesSecond diffusion activation energy
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:Second diffusion activation energy
diffusion_2nd_coefficients2nd diffusion coefficient
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:2nd diffusion coefficient
element_decay_constantsRadioactive decay constant for elements tracked
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:Radioactive decay constant for elements tracked
element_scalingRelative scaling of element percentages
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:Relative scaling of element percentages
elements_initial_concentrationRelative ratio of element concentration
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:Relative ratio of element concentration
elements_trackedThe elements tracked within TRISO simulations.
C++ Type:MultiMooseEnum
Options:Ag, Cs, Sr
Controllable:No
Description:The elements tracked within TRISO simulations.
energy_per_fission3.28451e-11Energy Released per Fission
Default:3.28451e-11
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Energy Released per Fission
extra_vector_tagsThe tag names for extra vectors that residual data should be saved into
C++ Type:std::vector<TagName>
Controllable:No
Description:The tag names for extra vectors that residual data should be saved into
familyLAGRANGESpecifies the family of FE shape functions to use for this variable.
Default:LAGRANGE
C++ Type:MooseEnum
Options:LAGRANGE, MONOMIAL, SCALAR, LAGRANGE_VEC, MONOMIAL_VEC, L2_HIERARCHIC, L2_HIERARCHIC_VEC, L2_LAGRANGE, L2_LAGRANGE_VEC, L2_RAVIART_THOMAS
Controllable:No
Description:Specifies the family of FE shape functions to use for this variable.
fast_neutron_fluence_functionFunction that describes the fast neutron fluence.
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function that describes the fast neutron fluence.
fast_neutron_fluxfast_neutron_fluxThe fast neutron flux (neutrons/m^2/s) material property
Default:fast_neutron_flux
C++ Type:MaterialPropertyName
Unit:(no unit assumed)
Controllable:No
Description:The fast neutron flux (neutrons/m^2/s) material property
fission_rate_functionThe function that describes the fission rate.
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:The function that describes the fission rate.
flux_factor1Constant multiplied against the function, rod average linear power, or q_variable.
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Constant multiplied against the function, rod average linear power, or q_variable.
flux_functionThe function that describes the fast neutron flux
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:The function that describes the fast neutron flux
fuel_pin_geometryName of the UserObject that reads the pin geometry from the mesh.
C++ Type:UserObjectName
Controllable:No
Description:Name of the UserObject that reads the pin geometry from the mesh.
fuel_typeUCOType of fuel used in TRISO simulation. The choices are: UO2 UCO
Default:UCO
C++ Type:MooseEnum
Options:UO2, UCO
Controllable:No
Description:Type of fuel used in TRISO simulation. The choices are: UO2 UCO
gas_constant8.31446Universal gas constant (J/mol-K)
Default:8.31446
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Universal gas constant (J/mol-K)
gas_swelling_model_typeSIFGRSWhich type of model to use to calculate the gaseous swelling. Choices are SIFGRS MATPRO SIFGRS_IG. If you select SIFGRS or SIFGRS_IG, the SIFGRS model must be included in the input file.
Default:SIFGRS
C++ Type:MooseEnum
Options:SIFGRS, MATPRO, SIFGRS_IG
Controllable:No
Description:Which type of model to use to calculate the gaseous swelling. Choices are SIFGRS MATPRO SIFGRS_IG. If you select SIFGRS or SIFGRS_IG, the SIFGRS model must be included in the input file.
generate_outputAdd scalar quantity output for stress and/or strain
C++ Type:MultiMooseEnum
Options:cauchy_stress_xx, cauchy_stress_xy, cauchy_stress_xz, cauchy_stress_yx, cauchy_stress_yy, cauchy_stress_yz, cauchy_stress_zx, cauchy_stress_zy, cauchy_stress_zz, creep_strain_xx, creep_strain_xy, creep_strain_xz, creep_strain_yx, creep_strain_yy, creep_strain_yz, creep_strain_zx, creep_strain_zy, creep_strain_zz, creep_stress_xx, creep_stress_xy, creep_stress_xz, creep_stress_yx, creep_stress_yy, creep_stress_yz, creep_stress_zx, creep_stress_zy, creep_stress_zz, deformation_gradient_xx, deformation_gradient_xy, deformation_gradient_xz, deformation_gradient_yx, deformation_gradient_yy, deformation_gradient_yz, deformation_gradient_zx, deformation_gradient_zy, deformation_gradient_zz, elastic_strain_xx, elastic_strain_xy, elastic_strain_xz, elastic_strain_yx, elastic_strain_yy, elastic_strain_yz, elastic_strain_zx, elastic_strain_zy, elastic_strain_zz, mechanical_strain_xx, mechanical_strain_xy, mechanical_strain_xz, mechanical_strain_yx, mechanical_strain_yy, mechanical_strain_yz, mechanical_strain_zx, mechanical_strain_zy, mechanical_strain_zz, pk1_stress_xx, pk1_stress_xy, pk1_stress_xz, pk1_stress_yx, pk1_stress_yy, pk1_stress_yz, pk1_stress_zx, pk1_stress_zy, pk1_stress_zz, pk2_stress_xx, pk2_stress_xy, pk2_stress_xz, pk2_stress_yx, pk2_stress_yy, pk2_stress_yz, pk2_stress_zx, pk2_stress_zy, pk2_stress_zz, plastic_strain_xx, plastic_strain_xy, plastic_strain_xz, plastic_strain_yx, plastic_strain_yy, plastic_strain_yz, plastic_strain_zx, plastic_strain_zy, plastic_strain_zz, small_stress_xx, small_stress_xy, small_stress_xz, small_stress_yx, small_stress_yy, small_stress_yz, small_stress_zx, small_stress_zy, small_stress_zz, strain_xx, strain_xy, strain_xz, strain_yx, strain_yy, strain_yz, strain_zx, strain_zy, strain_zz, stress_xx, stress_xy, stress_xz, stress_yx, stress_yy, stress_yz, stress_zx, stress_zy, stress_zz, effective_plastic_strain, effective_creep_strain, firstinv_stress, firstinv_cauchy_stress, firstinv_pk1_stress, firstinv_pk2_stress, firstinv_small_stress, firstinv_strain, hydrostatic_stress, hydrostatic_cauchy_stress, hydrostatic_pk1_stress, hydrostatic_pk2_stress, hydrostatic_small_stress, intensity_stress, intensity_cauchy_stress, intensity_pk1_stress, intensity_pk2_stress, intensity_small_stress, l2norm_mechanical_strain, l2norm_stress, l2norm_cauchy_stress, l2norm_pk1_stress, l2norm_strain, l2norm_elastic_strain, l2norm_plastic_strain, l2norm_creep_strain, max_principal_mechanical_strain, max_principal_stress, max_principal_cauchy_stress, max_principal_pk1_stress, max_principal_pk2_stress, max_principal_small_stress, max_principal_strain, maxshear_stress, maxshear_cauchy_stress, maxshear_pk1_stress, maxshear_pk2_stress, maxshear_small_stress, mid_principal_mechanical_strain, mid_principal_stress, mid_principal_cauchy_stress, mid_principal_pk1_stress, mid_principal_pk2_stress, mid_principal_small_stress, mid_principal_strain, min_principal_mechanical_strain, min_principal_stress, min_principal_cauchy_stress, min_principal_pk1_stress, min_principal_pk2_stress, min_principal_small_stress, min_principal_strain, secondinv_stress, secondinv_cauchy_stress, secondinv_pk1_stress, secondinv_pk2_stress, secondinv_small_stress, secondinv_strain, thirdinv_stress, thirdinv_cauchy_stress, thirdinv_pk1_stress, thirdinv_pk2_stress, thirdinv_small_stress, thirdinv_strain, triaxiality_stress, triaxiality_cauchy_stress, triaxiality_pk1_stress, triaxiality_pk2_stress, triaxiality_small_stress, volumetric_mechanical_strain, volumetric_strain, vonmises_stress, vonmises_cauchy_stress, vonmises_pk1_stress, vonmises_pk2_stress, directional_stress, directional_strain, axial_stress, axial_strain, axial_plastic_strain, axial_creep_strain, axial_elastic_strain, hoop_stress, hoop_strain, hoop_plastic_strain, hoop_creep_strain, hoop_elastic_strain, radial_stress, radial_strain, spherical_hoop_stress, spherical_hoop_strain, spherical_hoop_plastic_strain, spherical_hoop_creep_strain, spherical_hoop_elastic_strain, spherical_radial_stress, spherical_radial_strain
Controllable:No
Description:Add scalar quantity output for stress and/or strain
inactiveIf specified blocks matching these identifiers will be skipped.
C++ Type:std::vector<std::string>
Controllable:No
Description:If specified blocks matching these identifiers will be skipped.
incrementalFalseUse incremental or total strain
Default:False
C++ Type:bool
Controllable:No
Description:Use incremental or total strain
initial_densityInitial density in kg-UO2/m^3
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Initial density in kg-UO2/m^3
initial_enrichmentinitial enrichment fraction of U235 (wt percent)
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:initial enrichment fraction of U235 (wt percent)
initial_porosity0.05Initial porosity. Must be between 0.0 and 1.0.
Default:0.05
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Initial porosity. Must be between 0.0 and 1.0.
localized_initial_temperatureLocalized Initial temperature in Kelvins. This allows individual blocks to have different temperature conditions apart from the global initial conditions.
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Localized Initial temperature in Kelvins. This allows individual blocks to have different temperature conditions apart from the global initial conditions.
localized_temperature_functionFunction that describes localized temperature within the block.
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function that describes localized temperature within the block.
orderSECONDSpecifies the order of the FE shape function to use for this variable.
Default:SECOND
C++ Type:MooseEnum
Options:CONSTANT, FIRST, SECOND, THIRD, FOURTH, FIFTH, SIXTH, SEVENTH, EIGHTH, NINTH
Controllable:No
Description:Specifies the order of the FE shape function to use for this variable.
out_of_plane_pressure0Function used to prescribe pressure in the out-of-plane direction (y for 1D Axisymmetric or z for 2D Cartesian problems)
Default:0
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function used to prescribe pressure in the out-of-plane direction (y for 1D Axisymmetric or z for 2D Cartesian problems)
physicsType(s) of physics used on this block.
C++ Type:MultiMooseEnum
Options:Mechanics, Thermal
Controllable:No
Description:Type(s) of physics used on this block.
poissons_ratioPoisson's ratio for the material.
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Poisson's ratio for the material.
q_variableVariable holding linear heat rate in pellet in W/m
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:Variable holding linear heat rate in pellet in W/m
rod_ave_lin_powFunction that describes the linear power as a function of time.
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function that describes the linear power as a function of time.
strainSMALLStrain formulation
Default:SMALL
C++ Type:MooseEnum
Options:SMALL, FINITE
Controllable:No
Description:Strain formulation
stress_free_temperatureReference temperature for thermal eigenstrain calculation.
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:Reference temperature for thermal eigenstrain calculation.
system_pressure_functionThe function to use for the pressure on the exterior of the cladding.
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:The function to use for the pressure on the exterior of the cladding.
temperatureCoupled temperature: Used in multiple models
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:Coupled temperature: Used in multiple models
thermal_conductivity_modelFINK_LUCUTAThe thermal conductivity model.
Default:FINK_LUCUTA
C++ Type:MooseEnum
Options:FINK_LUCUTA, HALDEN, NFIR, MODIFIED_NFI, RONCHI, STAICU, TOPTAN
Controllable:No
Description:The thermal conductivity model.
triso_geometryTRISOGeometry user object name
C++ Type:UserObjectName
Controllable:No
Description:TRISOGeometry user object name
use_automatic_differentiationFalseFlag to use automatic differentiation (AD) objects when possible
Default:False
C++ Type:bool
Controllable:No
Description:Flag to use automatic differentiation (AD) objects when possible
youngs_modulusYoung's modulus of the material.
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Young's modulus of the material.

Optional Parameters

additional_generate_outputAdd scalar quantity output for stress and/or strain (will be appended to the list in `generate_output`)
C++ Type:MultiMooseEnum
Options:cauchy_stress_xx, cauchy_stress_xy, cauchy_stress_xz, cauchy_stress_yx, cauchy_stress_yy, cauchy_stress_yz, cauchy_stress_zx, cauchy_stress_zy, cauchy_stress_zz, creep_strain_xx, creep_strain_xy, creep_strain_xz, creep_strain_yx, creep_strain_yy, creep_strain_yz, creep_strain_zx, creep_strain_zy, creep_strain_zz, creep_stress_xx, creep_stress_xy, creep_stress_xz, creep_stress_yx, creep_stress_yy, creep_stress_yz, creep_stress_zx, creep_stress_zy, creep_stress_zz, deformation_gradient_xx, deformation_gradient_xy, deformation_gradient_xz, deformation_gradient_yx, deformation_gradient_yy, deformation_gradient_yz, deformation_gradient_zx, deformation_gradient_zy, deformation_gradient_zz, elastic_strain_xx, elastic_strain_xy, elastic_strain_xz, elastic_strain_yx, elastic_strain_yy, elastic_strain_yz, elastic_strain_zx, elastic_strain_zy, elastic_strain_zz, mechanical_strain_xx, mechanical_strain_xy, mechanical_strain_xz, mechanical_strain_yx, mechanical_strain_yy, mechanical_strain_yz, mechanical_strain_zx, mechanical_strain_zy, mechanical_strain_zz, pk1_stress_xx, pk1_stress_xy, pk1_stress_xz, pk1_stress_yx, pk1_stress_yy, pk1_stress_yz, pk1_stress_zx, pk1_stress_zy, pk1_stress_zz, pk2_stress_xx, pk2_stress_xy, pk2_stress_xz, pk2_stress_yx, pk2_stress_yy, pk2_stress_yz, pk2_stress_zx, pk2_stress_zy, pk2_stress_zz, plastic_strain_xx, plastic_strain_xy, plastic_strain_xz, plastic_strain_yx, plastic_strain_yy, plastic_strain_yz, plastic_strain_zx, plastic_strain_zy, plastic_strain_zz, small_stress_xx, small_stress_xy, small_stress_xz, small_stress_yx, small_stress_yy, small_stress_yz, small_stress_zx, small_stress_zy, small_stress_zz, strain_xx, strain_xy, strain_xz, strain_yx, strain_yy, strain_yz, strain_zx, strain_zy, strain_zz, stress_xx, stress_xy, stress_xz, stress_yx, stress_yy, stress_yz, stress_zx, stress_zy, stress_zz, effective_plastic_strain, effective_creep_strain, firstinv_stress, firstinv_cauchy_stress, firstinv_pk1_stress, firstinv_pk2_stress, firstinv_small_stress, firstinv_strain, hydrostatic_stress, hydrostatic_cauchy_stress, hydrostatic_pk1_stress, hydrostatic_pk2_stress, hydrostatic_small_stress, intensity_stress, intensity_cauchy_stress, intensity_pk1_stress, intensity_pk2_stress, intensity_small_stress, l2norm_mechanical_strain, l2norm_stress, l2norm_cauchy_stress, l2norm_pk1_stress, l2norm_strain, l2norm_elastic_strain, l2norm_plastic_strain, l2norm_creep_strain, max_principal_mechanical_strain, max_principal_stress, max_principal_cauchy_stress, max_principal_pk1_stress, max_principal_pk2_stress, max_principal_small_stress, max_principal_strain, maxshear_stress, maxshear_cauchy_stress, maxshear_pk1_stress, maxshear_pk2_stress, maxshear_small_stress, mid_principal_mechanical_strain, mid_principal_stress, mid_principal_cauchy_stress, mid_principal_pk1_stress, mid_principal_pk2_stress, mid_principal_small_stress, mid_principal_strain, min_principal_mechanical_strain, min_principal_stress, min_principal_cauchy_stress, min_principal_pk1_stress, min_principal_pk2_stress, min_principal_small_stress, min_principal_strain, secondinv_stress, secondinv_cauchy_stress, secondinv_pk1_stress, secondinv_pk2_stress, secondinv_small_stress, secondinv_strain, thirdinv_stress, thirdinv_cauchy_stress, thirdinv_pk1_stress, thirdinv_pk2_stress, thirdinv_small_stress, thirdinv_strain, triaxiality_stress, triaxiality_cauchy_stress, triaxiality_pk1_stress, triaxiality_pk2_stress, triaxiality_small_stress, volumetric_mechanical_strain, volumetric_strain, vonmises_stress, vonmises_cauchy_stress, vonmises_pk1_stress, vonmises_pk2_stress, directional_stress, directional_strain, axial_stress, axial_strain, axial_plastic_strain, axial_creep_strain, axial_elastic_strain, hoop_stress, hoop_strain, hoop_plastic_strain, hoop_creep_strain, hoop_elastic_strain, radial_stress, radial_strain, spherical_hoop_stress, spherical_hoop_strain, spherical_hoop_plastic_strain, spherical_hoop_creep_strain, spherical_hoop_elastic_strain, spherical_radial_stress, spherical_radial_strain
Controllable:No
Description:Add scalar quantity output for stress and/or strain (will be appended to the list in `generate_output`)
blockThe list of ids of the blocks (subdomain) that the stress divergence kernels will be applied to
C++ Type:std::vector<SubdomainName>
Controllable:No
Description:The list of ids of the blocks (subdomain) that the stress divergence kernels will be applied to
displacementsThe displacements appropriate for the simulation geometry and coordinate system: Used in density and strain models
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:The displacements appropriate for the simulation geometry and coordinate system: Used in density and strain models
volumetric_locking_correctionFalseFlag to correct volumetric locking
Default:False
C++ Type:bool
Controllable:No
Description:Flag to correct volumetric locking

Mechanics Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.

Advanced Parameters

(assessment/TRISO/validation/AGR-1/AGR-1_action.i)

#COMPACT = <compact_id>
#DATA_FILE = <data_file_name>

[GlobalParams]
  order = SECOND
  family = LAGRANGE
  initial_enrichment = 0.19736 # [wt-]
  energy_per_fission = 3.204e-11 # [J/fission]
  O_U = 1.3613 # Initial Oxygen to Uranium atom ratio
  C_U = 0.3253 # Initial Carbon to Uranium atom ratio
  mass_source_property_OPyC = 7.06e-7 # Default = UCO fuel kernel
  extra_vector_tags = 'ref'
  use_displaced_mesh = false
[]

[Mesh]
  coord_type = RSPHERICAL
  [gen]
    type = TRISO1DFiveLayerMeshGenerator
    elem_type = EDGE3
    kernel_radius = 175e-6
    buffer_thickness = 100e-6
    IPyC_thickness = 40e-6
    SiC_thickness = 35e-6
    OPyC_thickness = 40e-6
    kernel_mesh_density = 18
    buffer_mesh_density = 14
    IPyC_mesh_density = 6
    SiC_mesh_density = 8
    OPyC_mesh_density = 6
    block_names = 'fuel buffer IPyC SiC OPyC'
    include_gap = false
    kernel_bias = 0.8
    buffer_bias = 1.25
  []
[]

[Problem]
  type = ReferenceResidualProblem
  reference_vector = 'ref'
  extra_tag_vectors = 'ref'
[]

[UserObjects]
  [particle_geometry]
    type = TRISOGeometry
    outer_OPyC = OPyC_outer_boundary
    outer_SiC = SiC_outer_boundary
    outer_IPyC = IPyC_outer_boundary
    inner_IPyC = IPyC_inner_boundary
    outer_buffer = buffer_outer_boundary
    outer_kernel = fuel_outer_boundary
    include_particle = true
    include_pebble = false
  []
[]

[Functions]
  [temp_bc_file]
    type = PiecewiseLinear
    #data_file = DATA_FILE
    x_index_in_file = 0
    y_index_in_file = 1
    xy_in_file_only = false
    format = columns
  []
  [temp_bc_safety]
    type = ParsedFunction
    symbol_names = 'test_temperature'
    symbol_values = '1873.15'
    expression = 'start := 55209600+1800;
             ramp1 := 120.0/3600.0;
             ramp2 := 120.0/3600.0;
             ramp3 := 50.0/3600.0;
             ramp4 := -600.0/3600.0;
             room := 303.15;
             plateau1 := 673.15;
             plateau2 := 1523.15;
             hold1 := 7200;
             hold2 := 43200;
             hold3 := 1080000;
             ramp_time1 := (plateau1-room)/ramp1;
             ramp_time2 := (plateau2-plateau1)/ramp2;
             ramp_time3 := (test_temperature-plateau2)/ramp3;
             ramp_time4 := (room-test_temperature)/ramp4;
             t1 := start+ramp_time1;
             t2 := t1+hold1;
             t3 := t2+ramp_time2;
             t4 := t3+hold2;
             t5 := t4+ramp_time3;
             t6 := t5+hold3;
             t7 := t6+ramp_time4;
             if(t<start,room,
             if(t<t1,room+(t-start)*ramp1,
             if(t<t2,plateau1,
             if(t<t3,plateau1+(t-t2)*ramp2,
             if(t<t4,plateau2,
             if(t<t5,plateau2+(t-t4)*ramp3,
             if(t<t6,test_temperature,
             if(t<t7,test_temperature+(t-t6)*ramp4,
             room))))))))'
  []
  [temp_bc]
    type = ParsedFunction
    symbol_names = 'tbcf tbcs'
    symbol_values = 'temp_bc_file temp_bc_safety'
    expression = 'if(t<=55209600,tbcf,tbcs)'
  []
  [power_history] # W/m^3
    type = PiecewiseLinear
    #data_file = DATA_FILE
    x_index_in_file = 0
    y_index_in_file = 2
    xy_in_file_only = false
    format = columns
  []
  [fast_neutron_fluence]
    type = PiecewiseLinear
    #data_file = DATA_FILE
    x_index_in_file = 0
    y_index_in_file = 3
    xy_in_file_only = false
    format = columns
  []
  [fission_rate_from_power]
    type = LinearCombinationFunction
    functions = power_history
    # W/m^3 / (1.602e-13 J/MeV) / (200 MeV/fission)
    w = 3.1211e10
  []
  [fission_rate]
    type = ParsedFunction
    symbol_names = 'fr'
    symbol_values = 'fission_rate_from_power'
    expression = 'if(t<=55209600,fr,0)'
  []
  [d1_function]
    type = ParsedFunction
    expression = 'exp(t/4.5e25)'
  []
[]

[BCs]
  # fix temperature on free surface
  [freesurf_temp]
    type = FunctionDirichletBC
    variable = temperature
    function = temp_bc
    boundary = exterior
  []
[]

[NuclearMaterials]
  fission_operation = 'Normal'
  physics = 'Thermal'
  initial_temperature = 923.15
  elements_tracked = 'Ag'
  elements_initial_concentration = '0.0'
  element_scaling = '1e14'
  use_automatic_differentiation = false
  [ParticleFuel]
    [UCO]
      fuel_type = UCO
      particle_fuel_models = 'Burnup Diffusion'
      diffusion_1st_coefficients = '6.7e-9'
      diffusion_1st_activation_energies = '165e3'
      diffusion_2nd_coefficients = '0'
      diffusion_2nd_activation_energies = '0'
      block = fuel
      fission_rate_function = fission_rate
      fast_neutron_fluence_function = fast_neutron_fluence
      initial_density = 10400.0
      average_grain_radius = 10e-6
      triso_geometry = particle_geometry
    []
  []
  [ParticleLayers]
    layers_models = 'Diffusion'
    fuel_type = UCO
    [SiC]
      [SiC_layer]
        block = SiC
        diffusion_1st_coefficients = '3.6e-9'
        diffusion_1st_activation_energies = '215e3'
        diffusion_2nd_coefficients = '0'
        diffusion_2nd_activation_energies = '0'
        initial_density = 3200.0
        thermal_conductivity_model = miller
      []
    []
    [IPyC]
      [IPyC_layer]
        block = IPyC
        diffusion_1st_coefficients = '5.3e-9'
        diffusion_1st_activation_energies = '154e3'
        initial_density = 1900.0
        thermal_conductivity = 4.0
        specific_heat = 720.0
      []
    []
    [OPyC]
      [OPyC_layer]
        block = OPyC
        diffusion_1st_coefficients = '5.3e-9'
        diffusion_1st_activation_energies = '154e3'
        initial_density = 1900.0
        thermal_conductivity = 4.0
        specific_heat = 720.0
      []
    []
    [Buffer]
      [Buffer_layer]
        block = buffer
        diffusion_1st_coefficients = '1e-8'
        diffusion_1st_activation_energies = '0'
        initial_density = 1050.0
      []
    []
  []
[]

[Dampers]
  [temp]
    type = MaxIncrement
    variable = temperature
    max_increment = 50
  []
[]

[Debug]
  show_var_residual_norms = true
  show_var_residual = 'temperature'
[]

[Preconditioning]
  [smp]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK' # Shall we switch to 'Newton'?
  # solve_type = 'Newton'

  petsc_options_iname = '-pc_type -pc_factor_mat_solver_package'
  petsc_options_value = 'lu superlu_dist'

  line_search = 'none'

  nl_rel_tol = 1e-6
  nl_abs_tol = 1e-12
  nl_max_its = 50

  l_tol = 1e-4
  l_max_its = 50

  start_time = 0.0
  end_time = 55209600
  num_steps = 1500

  dt = 86400
  dtmax = 86400
  dtmin = 100

  [TimeStepper]
    type = FunctionDT
    function = 'if(t<55209600,86400,1800)'
  []
  automatic_scaling = true
  compute_scaling_once = false
[]

[Postprocessors]
  [_dt]
    type = TimestepSize
    execute_on = timestep_end
  []

  ### Temperature
  [temp_min]
    type = NodalExtremeValue
    variable = temperature
    value_type = 'min'
    execute_on = 'initial timestep_end'
  []
  [temp_max]
    type = NodalExtremeValue
    variable = temperature
    value_type = 'max'
    execute_on = 'initial timestep_end'
  []

  ### Postprocessors for CO production
  [total_fission_rate]
    type = ElementIntegralPower
    variable = temperature
    fission_rate = fission_rate
    block = fuel
    energy_per_fission = 1.0
    outputs = exodus
    execute_on = 'initial timestep_end'
  []
  [total_fissions]
    type = TimeIntegratedPostprocessor
    value = total_fission_rate
    outputs = exodus
    execute_on = 'initial timestep_end'
  []

  ##### irradiation conditions
  [particle_power]
    type = ElementIntegralPower
    variable = temperature
    use_material_fission_rate = true
    fission_rate_material = fission_rate
    block = fuel
    execute_on = 'initial timestep_end'
  []

  [max_fluence]
    type = ElementExtremeValue
    variable = fast_neutron_fluence
    value_type = 'max'
    execute_on = 'initial timestep_end'
  []

  [max_burnup]
    type = ElementExtremeValue
    variable = burnup
    block = fuel
    value_type = 'max'
    execute_on = 'initial timestep_end'
  []
[]

[Outputs]
  perf_graph = true
  print_linear_residuals = false
  [console]
    type = Console
    time_step_interval = 1
  []
  [exodus]
    type = Exodus
    file_base = COMPACT
  []
  [release]
    type = CSV
    file_base = release_COMPACT
    sort_columns = true
  []
  [final_release]
    type = CSV
    file_base = final_release_COMPACT
    sort_columns = true
    execute_on = 'final'
  []

[]

(assessment/TRISO/validation/AGR-1/AGR-1_action.i)

#COMPACT = <compact_id>
#DATA_FILE = <data_file_name>

[GlobalParams]
  order = SECOND
  family = LAGRANGE
  initial_enrichment = 0.19736 # [wt-]
  energy_per_fission = 3.204e-11 # [J/fission]
  O_U = 1.3613 # Initial Oxygen to Uranium atom ratio
  C_U = 0.3253 # Initial Carbon to Uranium atom ratio
  mass_source_property_OPyC = 7.06e-7 # Default = UCO fuel kernel
  extra_vector_tags = 'ref'
  use_displaced_mesh = false
[]

[Mesh]
  coord_type = RSPHERICAL
  [gen]
    type = TRISO1DFiveLayerMeshGenerator
    elem_type = EDGE3
    kernel_radius = 175e-6
    buffer_thickness = 100e-6
    IPyC_thickness = 40e-6
    SiC_thickness = 35e-6
    OPyC_thickness = 40e-6
    kernel_mesh_density = 18
    buffer_mesh_density = 14
    IPyC_mesh_density = 6
    SiC_mesh_density = 8
    OPyC_mesh_density = 6
    block_names = 'fuel buffer IPyC SiC OPyC'
    include_gap = false
    kernel_bias = 0.8
    buffer_bias = 1.25
  []
[]

[Problem]
  type = ReferenceResidualProblem
  reference_vector = 'ref'
  extra_tag_vectors = 'ref'
[]

[UserObjects]
  [particle_geometry]
    type = TRISOGeometry
    outer_OPyC = OPyC_outer_boundary
    outer_SiC = SiC_outer_boundary
    outer_IPyC = IPyC_outer_boundary
    inner_IPyC = IPyC_inner_boundary
    outer_buffer = buffer_outer_boundary
    outer_kernel = fuel_outer_boundary
    include_particle = true
    include_pebble = false
  []
[]

[Functions]
  [temp_bc_file]
    type = PiecewiseLinear
    #data_file = DATA_FILE
    x_index_in_file = 0
    y_index_in_file = 1
    xy_in_file_only = false
    format = columns
  []
  [temp_bc_safety]
    type = ParsedFunction
    symbol_names = 'test_temperature'
    symbol_values = '1873.15'
    expression = 'start := 55209600+1800;
             ramp1 := 120.0/3600.0;
             ramp2 := 120.0/3600.0;
             ramp3 := 50.0/3600.0;
             ramp4 := -600.0/3600.0;
             room := 303.15;
             plateau1 := 673.15;
             plateau2 := 1523.15;
             hold1 := 7200;
             hold2 := 43200;
             hold3 := 1080000;
             ramp_time1 := (plateau1-room)/ramp1;
             ramp_time2 := (plateau2-plateau1)/ramp2;
             ramp_time3 := (test_temperature-plateau2)/ramp3;
             ramp_time4 := (room-test_temperature)/ramp4;
             t1 := start+ramp_time1;
             t2 := t1+hold1;
             t3 := t2+ramp_time2;
             t4 := t3+hold2;
             t5 := t4+ramp_time3;
             t6 := t5+hold3;
             t7 := t6+ramp_time4;
             if(t<start,room,
             if(t<t1,room+(t-start)*ramp1,
             if(t<t2,plateau1,
             if(t<t3,plateau1+(t-t2)*ramp2,
             if(t<t4,plateau2,
             if(t<t5,plateau2+(t-t4)*ramp3,
             if(t<t6,test_temperature,
             if(t<t7,test_temperature+(t-t6)*ramp4,
             room))))))))'
  []
  [temp_bc]
    type = ParsedFunction
    symbol_names = 'tbcf tbcs'
    symbol_values = 'temp_bc_file temp_bc_safety'
    expression = 'if(t<=55209600,tbcf,tbcs)'
  []
  [power_history] # W/m^3
    type = PiecewiseLinear
    #data_file = DATA_FILE
    x_index_in_file = 0
    y_index_in_file = 2
    xy_in_file_only = false
    format = columns
  []
  [fast_neutron_fluence]
    type = PiecewiseLinear
    #data_file = DATA_FILE
    x_index_in_file = 0
    y_index_in_file = 3
    xy_in_file_only = false
    format = columns
  []
  [fission_rate_from_power]
    type = LinearCombinationFunction
    functions = power_history
    # W/m^3 / (1.602e-13 J/MeV) / (200 MeV/fission)
    w = 3.1211e10
  []
  [fission_rate]
    type = ParsedFunction
    symbol_names = 'fr'
    symbol_values = 'fission_rate_from_power'
    expression = 'if(t<=55209600,fr,0)'
  []
  [d1_function]
    type = ParsedFunction
    expression = 'exp(t/4.5e25)'
  []
[]

[BCs]
  # fix temperature on free surface
  [freesurf_temp]
    type = FunctionDirichletBC
    variable = temperature
    function = temp_bc
    boundary = exterior
  []
[]

[NuclearMaterials]
  fission_operation = 'Normal'
  physics = 'Thermal'
  initial_temperature = 923.15
  elements_tracked = 'Ag'
  elements_initial_concentration = '0.0'
  element_scaling = '1e14'
  use_automatic_differentiation = false
  [ParticleFuel]
    [UCO]
      fuel_type = UCO
      particle_fuel_models = 'Burnup Diffusion'
      diffusion_1st_coefficients = '6.7e-9'
      diffusion_1st_activation_energies = '165e3'
      diffusion_2nd_coefficients = '0'
      diffusion_2nd_activation_energies = '0'
      block = fuel
      fission_rate_function = fission_rate
      fast_neutron_fluence_function = fast_neutron_fluence
      initial_density = 10400.0
      average_grain_radius = 10e-6
      triso_geometry = particle_geometry
    []
  []
  [ParticleLayers]
    layers_models = 'Diffusion'
    fuel_type = UCO
    [SiC]
      [SiC_layer]
        block = SiC
        diffusion_1st_coefficients = '3.6e-9'
        diffusion_1st_activation_energies = '215e3'
        diffusion_2nd_coefficients = '0'
        diffusion_2nd_activation_energies = '0'
        initial_density = 3200.0
        thermal_conductivity_model = miller
      []
    []
    [IPyC]
      [IPyC_layer]
        block = IPyC
        diffusion_1st_coefficients = '5.3e-9'
        diffusion_1st_activation_energies = '154e3'
        initial_density = 1900.0
        thermal_conductivity = 4.0
        specific_heat = 720.0
      []
    []
    [OPyC]
      [OPyC_layer]
        block = OPyC
        diffusion_1st_coefficients = '5.3e-9'
        diffusion_1st_activation_energies = '154e3'
        initial_density = 1900.0
        thermal_conductivity = 4.0
        specific_heat = 720.0
      []
    []
    [Buffer]
      [Buffer_layer]
        block = buffer
        diffusion_1st_coefficients = '1e-8'
        diffusion_1st_activation_energies = '0'
        initial_density = 1050.0
      []
    []
  []
[]

[Dampers]
  [temp]
    type = MaxIncrement
    variable = temperature
    max_increment = 50
  []
[]

[Debug]
  show_var_residual_norms = true
  show_var_residual = 'temperature'
[]

[Preconditioning]
  [smp]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK' # Shall we switch to 'Newton'?
  # solve_type = 'Newton'

  petsc_options_iname = '-pc_type -pc_factor_mat_solver_package'
  petsc_options_value = 'lu superlu_dist'

  line_search = 'none'

  nl_rel_tol = 1e-6
  nl_abs_tol = 1e-12
  nl_max_its = 50

  l_tol = 1e-4
  l_max_its = 50

  start_time = 0.0
  end_time = 55209600
  num_steps = 1500

  dt = 86400
  dtmax = 86400
  dtmin = 100

  [TimeStepper]
    type = FunctionDT
    function = 'if(t<55209600,86400,1800)'
  []
  automatic_scaling = true
  compute_scaling_once = false
[]

[Postprocessors]
  [_dt]
    type = TimestepSize
    execute_on = timestep_end
  []

  ### Temperature
  [temp_min]
    type = NodalExtremeValue
    variable = temperature
    value_type = 'min'
    execute_on = 'initial timestep_end'
  []
  [temp_max]
    type = NodalExtremeValue
    variable = temperature
    value_type = 'max'
    execute_on = 'initial timestep_end'
  []

  ### Postprocessors for CO production
  [total_fission_rate]
    type = ElementIntegralPower
    variable = temperature
    fission_rate = fission_rate
    block = fuel
    energy_per_fission = 1.0
    outputs = exodus
    execute_on = 'initial timestep_end'
  []
  [total_fissions]
    type = TimeIntegratedPostprocessor
    value = total_fission_rate
    outputs = exodus
    execute_on = 'initial timestep_end'
  []

  ##### irradiation conditions
  [particle_power]
    type = ElementIntegralPower
    variable = temperature
    use_material_fission_rate = true
    fission_rate_material = fission_rate
    block = fuel
    execute_on = 'initial timestep_end'
  []

  [max_fluence]
    type = ElementExtremeValue
    variable = fast_neutron_fluence
    value_type = 'max'
    execute_on = 'initial timestep_end'
  []

  [max_burnup]
    type = ElementExtremeValue
    variable = burnup
    block = fuel
    value_type = 'max'
    execute_on = 'initial timestep_end'
  []
[]

[Outputs]
  perf_graph = true
  print_linear_residuals = false
  [console]
    type = Console
    time_step_interval = 1
  []
  [exodus]
    type = Exodus
    file_base = COMPACT
  []
  [release]
    type = CSV
    file_base = release_COMPACT
    sort_columns = true
  []
  [final_release]
    type = CSV
    file_base = final_release_COMPACT
    sort_columns = true
    execute_on = 'final'
  []

[]

Description
User - based Interface
Example Fully Reduced Input Syntax
Example Input File Syntax
Input Parameters