# Fission gas release for UPuZr

Fission gas release model for UPuZr metal fuel

## Description

FgrUPuZr is a fission gas release model for UPuZr metal fuel. The amount of fission gas generated per unit volume of fuel is given by (1) where F is the fission density, 0.26 is the fission yield of gas atoms (can be provided by the user), and N is Avogadro's number. According to Barnes (1964) when swelling due to fission gas bubbles reaches 33% , the fission gas bubbles interconnect, and 80% of the fission gas is released.

Interconnection of the fission gas bubbles transforms closed porosity into the open porosity that facilitates instant release of any consequently generated fission gas. Thus, the fission gas induced swelling is terminated, once the interconnection threshold is reached. In the code, porosity is calculated and is monitored in FgrUPuZr (read-in as a material property from VSwellingUPuZr).

When the porosity equals 0.24812 (corresponding to a gaseous swelling of 33%), 80% of the fission gas is released after which, all of the fission gas generated is released.

## Example Input Syntax


[./Fission_Gas_Release]
type = FgrUPuZr
fission_rate = fission_rate
outputs = all
output_properties = 'fis_gas_prod fis_gas_rel'
[../]
(test/tests/vswelling_upuzr/fission_gas.i)

## Input Parameters

• fractional_yield0.3017fraction yield of fission gas atoms per fission

Default:0.3017

C++ Type:double

Description:fraction yield of fission gas atoms per fission

• 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.

• fission_rateCoupled Fission Rate

C++ Type:std::vector

Description:Coupled Fission Rate

• use_material_fission_rateFalseFlag to use the material 'fission_rate_material' instead of variable fission rate

Default:False

C++ Type:bool

Description:Flag to use the material 'fission_rate_material' instead of variable fission rate

• 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

• fission_rate_materialfission_rate_materialFission rate material property name

Default:fission_rate_material

C++ Type:MaterialPropertyName

Description:Fission rate material property name

• 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

### 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. R. S. Barnes. A Theory of Swelling and Gas Release for Reactor Materials. Journal of Nuclear Materials, 11:135â€“148, 1964.[BibTeX]