# HT9 Thermal and Irradiation Creep Update

Thermal and irradiation creep for HT9 based on M. B. Toloczko et al (1999) 18th Symposium ASTM-1325 for tensor mechanics. Must be used in conjunction with ComputeMultipleInelasticStress.

## Description

Thermal and irradiation creep models and material properties from IFR Property Evaluation Working Group (1988) are used for the HT9 model, HT9CreepUpdate. The first two terms of the following equation are for secondary creep and the last term represents the irradiation creep contribution (Ryu et al., 2006). (1) where T is the Temperature (K), is the effective stress (MPa), is the neutron flux (), and is the effective thermal and irradiation creep strain rate (). The following are creep coefficients and activation energies for Eq. 1:

Table 1: Parameters used in the HT9 Creep Model

Model ExpressionParameter Value

## Example Input Syntax


[./creep]
type = HT9CreepUpdate
block = 1
fast_neutron_flux = fast_neutron_flux
[../]
(test/tests/tensor_mechanics/ht9_creep/creep_HT9_3d_test.i)

HT9CreepUpdate must be run in conjunction with the inelastic strain return mapping stress calculator as shown below:


type = ComputeMultipleInelasticStress
tangent_operator = elastic
inelastic_models = 'creep'
block = 1
[../]
(test/tests/tensor_mechanics/ht9_creep/creep_HT9_3d_test.i)

## Input Parameters

• acceptable_multiplier10Factor applied to relative and absolute tolerance for acceptable convergence if iterations are no longer making progress

Default:10

C++ Type:double

Description:Factor applied to relative and absolute tolerance for acceptable convergence if iterations are no longer making progress

• fast_neutron_fluxThe fast neutron flux (neutrons/cm^2-sec)

C++ Type:std::vector

Description:The fast neutron flux (neutrons/cm^2-sec)

• temperatureThe coupled temperature (K)

C++ Type:std::vector

Description:The coupled temperature (K)

• C_51.17e+09The leading coefficent in the first term for thermal creep

Default:1.17e+09

C++ Type:double

Description:The leading coefficent in the first term for thermal creep

• C_68.33e+09The leading coefficent in the second term for thermal creep

Default:8.33e+09

C++ Type:double

Description:The leading coefficent in the second term for thermal creep

• 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

• A2.59e+14Another fitting constant for the irradiation creep term, see explanation above

Default:2.59e+14

C++ Type:double

Description:Another fitting constant for the irradiation creep term, see explanation above

• B0.000183A fitting constant for the irradiation creep term, see explanation above

Default:0.000183

C++ Type:double

Description:A fitting constant for the irradiation creep term, see explanation above

• R1.987The universal gas constant (cal/K-mol)

Default:1.987

C++ Type:double

Description:The universal gas constant (cal/K-mol)

• n_exponent_12The stress exponent in the first term for thermal creep

Default:2

C++ Type:double

Description:The stress exponent in the first term for thermal creep

• Q73000The activation energy for irradiation creep term (cal/mol)

Default:73000

C++ Type:double

Description:The activation energy for irradiation creep term (cal/mol)

• max_inelastic_increment0.0001The maximum inelastic strain increment allowed in a time step

Default:0.0001

C++ Type:double

Description:The maximum inelastic strain increment allowed in a time step

• base_nameOptional parameter that defines a prefix for all material properties related to this stress update model. This allows for multiple models of the same type to be used without naming conflicts.

C++ Type:std::string

Description:Optional parameter that defines a prefix for all material properties related to this stress update model. This allows for multiple models of the same type to be used without naming conflicts.

• n_exponent_31.3The stress exponent in the irradiation creep term

Default:1.3

C++ Type:double

Description:The stress exponent in the irradiation creep term

• n_exponent_25The stress exponent in the second term for thermal creep

Default:5

C++ Type:double

Description:The stress exponent in the second term for thermal creep

• max_its30Maximum number of Newton iterations

Default:30

C++ Type:unsigned int

Description:Maximum number of Newton iterations

• Q_5108276The activation energy in the second term for thermal creep (cal/mol)

Default:108276

C++ Type:double

Description:The activation energy in the second term for thermal creep (cal/mol)

• Q_483142The activation energy in the first term for thermal creep (cal/mol)

Default:83142

C++ Type:double

Description:The activation energy in the first term for thermal creep (cal/mol)

• absolute_tolerance1e-11Absolute convergence tolerance for Newton iteration

Default:1e-11

C++ Type:double

Description:Absolute convergence tolerance for Newton iteration

• relative_tolerance1e-08Relative convergence tolerance for Newton iteration

Default:1e-08

C++ Type:double

Description:Relative convergence tolerance for Newton iteration

• 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

• effective_inelastic_strain_nameeffective_creep_strainName of the material property that stores the effective inelastic strain

Default:effective_creep_strain

C++ Type:std::string

Description:Name of the material property that stores the effective inelastic strain

• 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

• internal_solve_output_onon_errorWhen to output internal Newton solve information

Default:on_error

C++ Type:MooseEnum

Description:When to output internal Newton solve information

• internal_solve_full_iteration_historyFalseSet true to output full internal Newton iteration history at times determined by internal_solve_output_on. If false, only a summary is output.

Default:False

C++ Type:bool

Description:Set true to output full internal Newton iteration history at times determined by internal_solve_output_on. If false, only a summary is output.

### Debug Parameters

• 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. Compiled by: IFR Property Evaluation Working Group. Metallic fuels handbook. Argonne National Laboratory, June 1988.[BibTeX]
2. Ho Jin Ryu, A. M. Yacout, Yeon Soo Kim, and G. L. Hofman. Review of HT9 Cladding Creep Correlations for Advanced Liquid Metal Fast Reactors. In Transactions of the American Nuclear Society, volume 94, 797–798. ANS, 2006.[BibTeX]