# Thermal Properties for Fast MOX

Computes the thermal conductivity for fast MOX fuel

## Description

The ThermalFastMOX model computes the thermal conductivity for fast MOX fuel. Currently a single correlation is available from Inoue et al. (2004) and used by Karahan (2009).

Mixed oxide fuels for fast reactors contain higher concentrations of plutonium oxide than their LWR counterparts. The thermal model developed by Inoue et al. (2004) and used by Karahan (2009) is valid for for 25% PuO. The thermal conductivity model for fast MOX is similar in form to the model proposed by Lucuta et al. (1996) for UO. The model consists of an unirradiated thermal conductivity that is multiplied by corrective factors for dissolved solid fission products (), precipitated solid fission products (), radiation damage (), and porosity () as given by: (1) where is the effective fuel thermal conductivity in W/m-K and is the fully dense fuel thermal conductivity in W/m-K. , , and are the same correlations as formulated by Lucuta et al.

The dissolved fission products correction is given as (2) and the precipitated fission products correction is calculated as (3) where is the burnup in atomic percent and is the temperature in K. The porosity correction is determined with (4) where is the porosity.

The equation for is the modified Loeb correlation given by: (5) where is the volume fraction of porosity and is a coefficient. Karahan suggests a value of 2.5 for for conservatism.

## Example Input Syntax

[./fuel_thermalFastMOX]
type = ThermalFastMOX
block = 1
temp = T
burnup = burnup
initial_porosity = 0.05
[../]
(test/tests/thermalFastMOX/thermalFastMOX_test.i)

## Input Parameters

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

Default:True

C++ Type:bool

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

• tempCoupled Temperature

C++ Type:std::vector

Description:Coupled Temperature

• initial_porosity0.05Initial porosity

Default:0.05

C++ Type:double

Description:Initial porosity

• thcond_scalef1scaling factor for fuel thermal conductivity

Default:1

C++ Type:double

Description:scaling factor for fuel thermal conductivity

• porosityCoupled Porosity

C++ Type:std::vector

Description:Coupled Porosity

• blockThe list of block ids (SubdomainID) that this object will be applied

C++ Type:std::vector

Description:The list of block ids (SubdomainID) that this object will be applied

• oxy_to_metal_ratio2Deviation from stoichiometry

Default:2

C++ Type:double

Description:Deviation from stoichiometry

• boundaryThe list of boundary IDs from the mesh where this boundary condition applies

C++ Type:std::vector

Description:The list of boundary IDs from the mesh where this boundary condition applies

• burnup_functionBurnup function

C++ Type:FunctionName

Description:Burnup function

• burnupCoupled Burnup Rate

C++ Type:std::vector

Description:Coupled Burnup Rate

### Optional Parameters

• enableTrueSet the enabled status of the MooseObject.

Default:True

C++ Type:bool

Description:Set the enabled status of the MooseObject.

• 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

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.

• control_tagsAdds user-defined labels for accessing object parameters via control logic.

C++ Type:std::vector

Description:Adds user-defined labels for accessing object parameters via control logic.

• seed0The seed for the master random number generator

Default:0

C++ Type:unsigned int

Description:The seed for the master random number generator

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

Default:True

C++ Type:bool

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

• 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 computeSubdomainProperties() 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

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 computeSubdomainProperties() for the 0th quadrature point, and then copy that value to the other qps. Evaluations on element qps will be skipped

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

C++ Type:std::vector

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

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

Default:none

C++ Type:std::vector

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

## References

1. M. Inoue, K. Maeda, K. Katsuyama, K. Tanaka, K. Mondo, and M. Hisada. Fuel-to-cladding gap evolution and its impact on thermal performance of high burnup fast reactor type uranium-plutonium oxide fuel pins. Journal of Nuclear Materials, 326(1):59â€“73, 2004.[BibTeX]
2. Aydin Karahan. Modeling of thermo-mechanical and irradiation behavior of metallic and oxide fuels for sodium fast reactors. PhD thesis, Massachusetts Institute of Technology, June 2009.[BibTeX]
3. P. G. Lucuta, H. J. Matzke, and I. J. Hastings. A pragmatic approach to modelling thermal conductivity of irradiated UO$_2$ fuel: review and recommendations. Journal of Nuclear Materials, 232:166â€“180, 1996.[BibTeX]