Kharon input manual

The Kharon input is a keyword input. It consists of several grouped input parameters. Each group starts with the keyword that defines the group (name of the group), possibly followed by data entries associated with the keyword. The group can consist of several keyword (parameter name) and value pairs that are enclosed within a set of curly brackets.

• A working input file consists of several input groups.

• The order of the groups or the parameter name and value pairs within the group is not important.

• The input file can contain comments: all characters after '#', '!', and '%' on each line are considered as comments.

• All keywords, operators, and data entries must be separated by one or more spaces or line changes, since they are regarded as words.

Input groups

Simulation control parameters

The keyword that defines this group is simulationControl. The following parameters can be set inside this group. The bare minimum is to provide a value for the number of phases, nPhases.

Keyword	Size and type	Valid options / Valid range	Default	Description
nPhases	1*integer	1 = single-phase water or 2 = water and steam		Number of phases.
nIterMax	1*integer	positive integer	500	Number of solution (outer) iterations.
urfU	1*real	[0, 1]	0.5	Under-relaxation factor for velocity [-].
urfP	1*real	[0, 1]	0.5	Under-relaxation factor for pressure [-].
urfH	1*real	[0, 1]	0.9	Under-relaxation factor for enthalpy [-].
gravity	1*real	($-\infty$, $\infty$)	-9.81	Gravitational acceleration (in the direction of positive z-coordinate; upwards) [m/s2]
readRestart	1*integer	0 = No, 1 = Yes	0	Start from a previously saved state?
standAlone	1*integer	0 = Multiphysics coupling, 1 = Stand-alone simulation	0	Start a stand-alone simulation?
writeFormat	1*word	ascii, binary	ascii	Write format for output fields
materialProperties	1*word	libTable, libFluid	libTable	Calculation of material properties: libTable = linear interpolation from a pretabulated set of material properties, libFluid = IAPWS standard polynomial functions.
thermalBC	1*word	power, heatFlux, wallTemperature	heatFlux	Thermal boundary condition: power = set the power to each cell (Kharon converts this to heat flux and calculates the surface temperature distribution), heatFlux = set the heat flux of the heated surfaces in each cell (Kharon converts this to power and calculates the surface temperature distribution), wallTemperature = set the surface temperature of the heated surfaces in each cell (Kharon calculates the heat flux and power distributions).

Inlet definition

The keyword that defines this group is inlet. There are four available inlet types to choose from: pressureInlet, velocityInlet, massFlowInlet, totalMassFlowInlet. The inlet type determines the parameter that is required to define the flow into the domain.

Pressure inlet

Keyword	Size and type	Valid options / Valid range	Description
type	1*word	pressureInlet	Defines a pressure inlet.
pressure	1*real	[0, $\infty$)	Absolute (static) pressure at inlet [Pa].

Velocity inlet

Keyword	Size and type	Valid options / Valid range	Description
type	1*word	velocityInlet	Defines a velocity inlet.
velocity	nPhases*real	[0, $\infty$)	Phase velocities at inlet [m/s].

Mass flow inlet

Keyword	Size and type	Valid options / Valid range	Description
type	1*word	massFlowInlet	Defines a mass flow inlet.
massFlowRate	nPhases*real	[0, $\infty$)	Phase mass flow rates per assembly [kg/s].

Total mass flow inlet

Keyword	Size and type	Valid options / Valid range	Description
type	1*word	totalMassFlowInlet	Defines a total mass flow inlet.
massFlowRate	1*real	[0, $\infty$)	Total mass flow rate into the core [kg/s].

Common inlet parameters

In addition to the inlet type specific parameters shown above, the following parameters need to be given for all inlet types:

Keyword	Size and type	Valid options / Valid range	Description
temperature	nPhases*real	[0, $\infty$)	Phase temperatures at inlet [K].
volumeFraction	nPhases*real	[0, 1]	Phase volume fractions at inlet [-].

Outlet definition

The keyword that defines this group is outlet. The following parameters need to be provided:

Keyword	Size and type	Valid options / Valid range	Description
pressure	1*real	[0, $\infty$)	Absolute (static) pressure at outlet [Pa].
temperature	nPhases*real	[0, $\infty$)	Phase temperatures at outlet (for backflow) [K].
volumeFraction	nPhases*real	[0, 1]	Phase volume fractions at outlet (for backflow) [-].

List of fuel types

The keyword that defines this group is fuelType, which is immediately followed by the fuel type name. Several different fuel types can be defined, which can then referred to by its name when defining the core load pattern.

Keyword	Size and type	Valid options / Valid range	Default	Description
nCells	1*integer	[1, $\infty$)		Number of cells along the height of the fuel assembly.
nPins	1*integer	[1, $\infty$)	1	Number of fuel pins for heat transfer / temperature solution.
bottomElevation	1*real	($-\infty$, $\infty$)		Elevation of the assembly inlet (z-coordinate) [m]. Used for post-processing.
cellHeight	nCells*real	(0, $\infty$)		Cell height [m].
hydraulicDiameter	nCells*real	(0, $\infty$)		Hydraulic diameter [m].
thermalDiameter	nPins*nCells*real	(0, $\infty$)		Thermal diameter [m].
porosity	nCells*real	(0, 1]		Porosity, fluid fraction of total volume [m].

Two operators, * and x, are available to abbreviate the notation when setting the porosities and diameters, in particular.

An integer value times (*) a real value is replaced in its place with the number of said real values. A combination of separate real values and real values given with the *-operator can be used as well. This way you can provide the values for cell height, porosity of the assembly, hydraulic diameter of the assembly, and thermal diameter of a single pin, e.g. porosity of an assembly consisting of 21 cells can be given by: 10 * 0.5 0.5 10 * 0.5 = 0.5 10 * 0.5 10 * 0.5 = 21 * 0.5.

To facilitate definition of the thermal diameters for multiple pin assemblies, the x-operator is introduced. You first need to define the thermal diameters for a single pin. Multiple copies of that pin can be created with the x-operator: 3 x 21 * 0.01 = 21 * 0.01 21 * 0.01 21 * 0.01. Note that you need to use spaces around the x-operator, since otherwise it will be confused as a word.

In the following two identical fuel types, f1 and f2, are defined using a different number of pins for the heat transfer / temperature solution:

fuelType f1
{
    nCells             20
    bottomElevation    0.0
    cellHeight         20 * 0.1
    hydraulicDiameter  20 * 0.0110946
    thermalDiameter    20 * 0.0124111
    porosity           20 * 0.530672
}

fuelType f2
{
    nCells             20
    nPins              265
    bottomElevation    0.0
    cellHeight         20 * 0.1
    hydraulicDiameter  20 * 0.0110946
    thermalDiameter    265 x 20 * 3.28893
    porosity           20 * 0.530672
}