UPuZrGaseousEigenstrain

Computes and sums the change in fuel pellet volume due to gaseous fission product buildup in UPuZr.

Description

UPuZrGaseousEigenstrain computes a volumetric strain to account for gaseous swelling in U-Pu-Zr metal fuel systems. The derivation for the fuel swelling model for U-Pu-Zr used here was originally presented in Olander (1976). The model is able to simplify the gaseous swelling porosity into an analytical solution by making the following assumptions:

  • Fission gas diffusivity is infinite so that all fission gas is born in the bubbles;

  • The number density of bubbles is constant and their shape is perfectly spherical;

  • The gas within the bubbles can be treated as an ideal gas;

  • The gas/vacancy ratio in the bubbles is in equilibrium, i.e. the bubbles are not over- or under-pressurized;

  • Re-solution of fission gas atoms from the bubbles is neglected;

  • The solid is assumed to be un-stressed.

Following these assumptions, the number of gas atoms in each bubble at some time can be calculated directly from the total number of fissions, (1) where is the yield of gas atoms per fission, is the number density of bubbles (bub/m), is a fixed constant representing the amount of fission gas retained in the solid, and is the average number of fissions between and , where is the fission rate density.

Also included in Eq. (1) is the impact of interconnectivity of the bubbles on the total number of gas atoms per bubble. In the absence of a mechanistically informed interconnection model, the total bubble interconnection can be estimated from the porosity by, (2) where and is the interconnection initiating and terminating porosity respectively, and is the bulk porosity at time . and can be set via the input parameters interconnection_initiating_porosity and interconnection_terminating_porosity. Eq. (2) ensures a linear transition of interconnection from 0 to 1.0, capturing the smooth transition from non-interconnected to fully interconnected porosity. Additionally, an option to include densification during reactor operation has been added for novel fuel designs with fabricated porosities. Initial porosity is updated as a function of temperature: This densification model is derived from 2D mesoscale densification simulations. The gaseous swelling continues as long as the updated porosity is lower than the terminating porosity.

The bubble radius can be simply calculated as a function of the total number of fissions, where is the Boltzmann constant, is the temperature (K), is the surface tension of the fuel (J/m) (Karahan, 2009), is the gaseous fission product yield, is the fission rate density, is time, and is the number density of bubbles (bubbles/m).

Given the radius, the total eigenstrain can be calculated as, (3)

Several checks are performed on the value calculated by Eq. (3), ensuring that swelling due to gas bubbles only increases, and is not larger than the maximum permissible swelling calculated from , where is some initial porosity, e.g. fabrication porosity.

The porosity due to gas can be calculated from the swelling eigenstrain as, and the total porosity can then be calculated from the gaseous eigenstrain as,

Finally, the input parameter anisotropic_factor can be optionally specified between 1 and -1 to preferentially apply the volumetric strain in the radial direction when the axial direction is the y-axis. The factor is applied in Cartesian coordinates, so the x- and z-dimensions are equally modified with the axial y-dimension offsetting both. The factor is applied such that the trace of the volumetric swelling is the same as purely isotropic swelling, but preferential in the radial dimensions:

Example Input Syntax

[Materials<<<{"href": "../../../syntax/Materials/index.html"}>>>]
  [gas_swelling]
    type = UPuZrGaseousEigenstrain<<<{"description": "Computes and sums the change in fuel pellet volume due to gaseous fission product buildup in UPuZr.", "href": "UPuZrGaseousEigenstrain.html"}>>>
    temperature<<<{"description": "Coupled temperature variable"}>>> = temp
    initial_porosity<<<{"description": "Initial or fabrication porosity"}>>> = 0.1
    outputs<<<{"description": "Vector of output names where you would like to restrict the output of variables(s) associated with this object"}>>> = all
    output_properties<<<{"description": "List of material properties, from this material, to output (outputs must also be defined to an output type)"}>>> = 'porosity gaseous_porosity'
    bubble_number_density<<<{"description": "Material property name for the number density of intragranular bubbles, [bubbles/m^3]"}>>> = 1e+20
    eigenstrain_name<<<{"description": "Material property name for the eigenstrain tensor computed by this model. IMPORTANT: The name of this property must also be provided to the strain calculator."}>>> = gas_swelling_eigenstrain
    anisotropic_factor<<<{"description": "Factor applied to radial strains to estimate macroscopic anisotropic swelling. Axial axis must be along Y-axis."}>>> = 0.3
  []
[]
(test/tests/solid_mechanics/upuzr_eigenstrains/upuzr_gaseous_eigenstrain/test.i)

UPuZrGaseousEigenstrain must be used in conjunction with the solid mechanics quasi static action to apply the calculated eigenstrain:

[Physics<<<{"href": "../../../syntax/Physics/index.html"}>>>]
  [SolidMechanics<<<{"href": "../../../syntax/Physics/SolidMechanics/index.html"}>>>]
    [QuasiStatic<<<{"href": "../../../syntax/Physics/SolidMechanics/QuasiStatic/index.html"}>>>]
      [all]
        strain<<<{"description": "Strain formulation"}>>> = FINITE
        add_variables<<<{"description": "Add the displacement variables"}>>> = true
        eigenstrain_names<<<{"description": "List of eigenstrains to be applied in this strain calculation"}>>> = 'gas_swelling_eigenstrain'
        generate_output<<<{"description": "Add scalar quantity output for stress and/or strain"}>>> = 'stress_xx stress_yy stress_zz hydrostatic_stress strain_xx strain_yy'
      []
    []
  []
[]
(test/tests/solid_mechanics/upuzr_eigenstrains/upuzr_gaseous_eigenstrain/test.i)

Input Parameters

  • eigenstrain_nameMaterial property name for the eigenstrain tensor computed by this model. IMPORTANT: The name of this property must also be provided to the strain calculator.

    C++ Type:std::string

    Controllable:No

    Description:Material property name for the eigenstrain tensor computed by this model. IMPORTANT: The name of this property must also be provided to the strain calculator.

  • temperatureCoupled temperature variable

    C++ Type:std::vector<VariableName>

    Unit:(no unit assumed)

    Controllable:No

    Description:Coupled temperature variable

Required Parameters

  • anisotropic_factor0Factor applied to radial strains to estimate macroscopic anisotropic swelling. Axial axis must be along Y-axis.

    Default:0

    C++ Type:double

    Unit:(no unit assumed)

    Controllable:No

    Description:Factor applied to radial strains to estimate macroscopic anisotropic swelling. Axial axis must be along Y-axis.

  • base_nameOptional parameter that allows the user to define multiple mechanics material systems on the same block, i.e. for multiple phases

    C++ Type:std::string

    Controllable:No

    Description:Optional parameter that allows the user to define multiple mechanics material systems on the same block, i.e. for multiple phases

  • blockThe list of blocks (ids or names) that this object will be applied

    C++ Type:std::vector<SubdomainName>

    Controllable:No

    Description:The list of blocks (ids or names) that this object will be applied

  • boundaryThe list of boundaries (ids or names) from the mesh where this object applies

    C++ Type:std::vector<BoundaryName>

    Controllable:No

    Description:The list of boundaries (ids or names) from the mesh where this object applies

  • bubble_number_densityN_bubblesMaterial property name for the number density of intragranular bubbles, [bubbles/m^3]

    Default:N_bubbles

    C++ Type:MaterialPropertyName

    Unit:(no unit assumed)

    Controllable:No

    Description:Material property name for the number density of intragranular bubbles, [bubbles/m^3]

  • computeTrueWhen false, MOOSE will not call compute methods on this material. The user must call computeProperties() after retrieving the MaterialBase via MaterialBasePropertyInterface::getMaterialBase(). Non-computed MaterialBases are not sorted for dependencies.

    Default:True

    C++ Type:bool

    Controllable:No

    Description:When false, MOOSE will not call compute methods on this material. The user must call computeProperties() after retrieving the MaterialBase via MaterialBasePropertyInterface::getMaterialBase(). Non-computed MaterialBases are not sorted for dependencies.

  • constant_onNONEWhen ELEMENT, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps.When SUBDOMAIN, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps. Evaluations on element qps will be skipped

    Default:NONE

    C++ Type:MooseEnum

    Options:NONE, ELEMENT, SUBDOMAIN

    Controllable:No

    Description:When ELEMENT, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps.When SUBDOMAIN, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps. Evaluations on element qps will be skipped

  • declare_suffixAn optional suffix parameter that can be appended to any declared properties. The suffix will be prepended with a '_' character.

    C++ Type:MaterialPropertyName

    Unit:(no unit assumed)

    Controllable:No

    Description:An optional suffix parameter that can be appended to any declared properties. The suffix will be prepended with a '_' character.

  • densificationFalseWhether densification occurs or not

    Default:False

    C++ Type:bool

    Controllable:No

    Description:Whether densification occurs or not

  • fission_gas_yield0.3017Fission gas produced per fission

    Default:0.3017

    C++ Type:double

    Unit:(no unit assumed)

    Controllable:No

    Description:Fission gas produced per fission

  • fission_ratefission_rateFission rate material property name

    Default:fission_rate

    C++ Type:MaterialPropertyName

    Unit:(no unit assumed)

    Controllable:No

    Description:Fission rate material property name

  • initial_porosity0Initial or fabrication porosity

    Default:0

    C++ Type:double

    Unit:(no unit assumed)

    Controllable:No

    Description:Initial or fabrication porosity

  • interconnection_initiating_porosity0.23Porosity at which fission gas release starts

    Default:0.23

    C++ Type:double

    Unit:(no unit assumed)

    Controllable:No

    Description:Porosity at which fission gas release starts

  • interconnection_terminating_porosity0.25Porosity at which fission gas release finishes

    Default:0.25

    C++ Type:double

    Unit:(no unit assumed)

    Controllable:No

    Description:Porosity at which fission gas release finishes

  • retained_gas_fraction0Retained gas fraction that does not contribute to gaseous swelling

    Default:0

    C++ Type:double

    Unit:(no unit assumed)

    Controllable:No

    Description:Retained gas fraction that does not contribute to gaseous swelling

  • surface_energy0.8Surface energy of the bulk material

    Default:0.8

    C++ Type:double

    Unit:(no unit assumed)

    Controllable:No

    Description:Surface energy of the bulk material

Optional 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.

  • enableTrueSet the enabled status of the MooseObject.

    Default:True

    C++ Type:bool

    Controllable:Yes

    Description:Set the enabled status of the MooseObject.

  • implicitTrueDetermines whether this object is calculated using an implicit or explicit form

    Default:True

    C++ Type:bool

    Controllable:No

    Description:Determines whether this object is calculated using an implicit or explicit form

  • seed0The seed for the master random number generator

    Default:0

    C++ Type:unsigned int

    Controllable:No

    Description:The seed for the master random number generator

  • use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

    Default:False

    C++ Type:bool

    Controllable:No

    Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

Advanced Parameters

  • output_propertiesList of material properties, from this material, to output (outputs must also be defined to an output type)

    C++ Type:std::vector<std::string>

    Controllable:No

    Description:List of material properties, from this material, to output (outputs must also be defined to an output type)

  • outputsnone Vector of output names where you would like to restrict the output of variables(s) associated with this object

    Default:none

    C++ Type:std::vector<OutputName>

    Controllable:No

    Description:Vector of output names where you would like to restrict the output of variables(s) associated with this object

Outputs Parameters

  • prop_getter_suffixAn optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.

    C++ Type:MaterialPropertyName

    Unit:(no unit assumed)

    Controllable:No

    Description:An optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.

  • use_interpolated_stateFalseFor the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.

    Default:False

    C++ Type:bool

    Controllable:No

    Description:For the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.

Material Property Retrieval Parameters

  • scalar1Scale factor to be applied to the gaseous swelling strain. Used for calibration and sensitivity studies

    Default:1

    C++ Type:double

    Unit:(no unit assumed)

    Controllable:No

    Description:Scale factor to be applied to the gaseous swelling strain. Used for calibration and sensitivity studies

Advanced: Scaling Factors Parameters

Input Files

References

  1. Aydin Karahan. Modeling of thermo-mechanical and irradiation behavior of metallic and oxide fuels for sodium fast reactors. PhD thesis, Massachusetts Institute of Technology, Jun 2009. URL: https://tinyurl.com/y72vqvbn.[BibTeX]
  2. D. R. Olander. Fundamental aspects of nuclear reactor fuel elements. Technical Information Center, Energy Research and Development Administration, 1976.[BibTeX]