Ants input manual

The input syntax of Ants is currently card based with whitespace as separators.

This input manual is very much incomplete and may contain erroneous information. Many Ants variables may also or only be controlled via Cerberus input/output.

Main input file

Input syntax

The following general syntax guide lines hold for Ants specific input. For example the HEXBU-3D/MOD5 or Genpoly group constant files follow their respective syntax.

• Ants input supports rest of line comment symbols ! and //, and block comments beginning with /* and ending with */.
• Characters beginning and ending with " are treated as one token. This is useful for example in input file paths or titles.
• All tokens are separated with either space , comma , or tabular characters.
• Consecutive input may be repeated using *. The token before * must be a positive integer, which is the number of repeats.
• The input is case insensitive.
• The main block keywords (below) are reserved.
• Keyword include is reserved. It triggers the reading of an additional input file in this position. The input file path is given after the include keyword.
• Maximum line length is currently set to 65536 characters. This can be increased with recompilation, if necessary.

Main blocks

When the main input file is read, it is tokenized and split into main blocks. Depending on the main block, they might be split into sub-blocks. Currently, the main block keywords are

• title
• global
• core
• fuel
• controlrod
• iteration
• library
• output
• start
• end

Title

Set a title for the calculation. Currently not used for anything.

title [ <title> ]

<title> : at most one token for the title. If omitted, an empty title will be set.

Global

Set global calculation parameters. These cards will be processed before any other cards.

Sub-blocks:

• geometry
• neutronics

Geometry

Set neutronics solution geometry type. Exactly one global geometry card has to be present in the input.

global geometry <geometry>

<geometry>

• rectangular: use rectangular geometry (for example BWR, PWR)
• hexagonal : use hexagonal geometry (for example VVER)
• triangular: use triangular geometry with hexagonal fuel assemblies (for example VVER)

Neutronics

Set neutronics solution transport type. Exactly one global neutronics card has to be present in the input.

global neutronics <neutronics>

<neutronics>

• diffusion : solve diffusion equation

Core

Set core parameters.

Sub-blocks:

• width_x
• width_y
• width_xy
• width_x_grid
• width_y_grid
• axial_nodes
• axial_heights
• rows
• columns
• nominal_power
• radial_boundary_coeff
• axial_boundary_coeff
• radial_boundary_coeff_group
• axial_boundary_coeff_group
• radial_boundary_coeff_east
• radial_boundary_coeff_north
• radial_boundary_coeff_west
• radial_boundary_coeff_south
• radial_boundary_coeff_northeast
• radial_boundary_coeff_northwest
• radial_boundary_coeff_southwest
• radial_boundary_coeff_southeast
• axial_boundary_coeff_above
• axial_boundary_coeff_below
• axial_dimensions
• radial_dimensions
• division_x
• division_y
• division_z
• division_hex

width_x

Set node size in x direction for all input nodes (unit cm).

core width_x <width_x>

<width_x> : x direction size of all input nodes

width_y

Set node size in y direction for all input nodes (unit cm). Not used for hexagonal or triangular geometries.

core width_y <width_y>

<width_y> : y direction size of all input nodes

width_xy

Set node size in both x and y directions for all input nodes (unit cm).

core width_xy <width_xy>

<width_xy> : x and y direction sizes of all input nodes

width_x_grid

Set column-wise node sizes in the x direction for all input nodes (unit cm). core columns card has to be read before this card is given.

core width_x_grid <width_x_grid>

<width_x_grid> : column-wise x direction sizes of all input nodes (number of input: core columns). All values have to be the same value for hexagonal or triangular geometries.

width_y_grid

Set row-wise node sizes in the y direction for all nodes (unit cm). core rows card has to be read before this card is given. Not used for hexagonal or triangular geometries.

core width_y_grid <width_y_grid>

<width_y_grid> : row-wise y direction sizes of all input nodes (number of input: core rows)

axial_nodes

Set number of axial input node layers in the z direction for the core. This card determines the number of axial layers in rest of the input.

core axial_nodes <axial_nodes>

<axial_nodes> : number of input node axial layers in the z direction in the core

axial_heights

Set axial layer wise input node sizes in the z direction for all input nodes (unit cm). core axial_nodes card has to be read before this card is given.

core axial_heights <axial_heights>

<axial_heights> : axial layer wise z direction sizes of all input nodes (number of input: core axial_nodes)

rows

Set number of rows in the x direction for the core. This card determines the number of rows in rest of the input.

core rows <rows>

<rows> : number of rows in the x direction in the core

columns

Set number of columns in the y direction for the core. This card determines the number of columns in rest of the input.

core columns <columns>

<columns> : number of columns in the y direction in the core

nominal_power

Set the core nominal power (unit W). Used to initialize the core total power when set and at the beginning of each calculation step if total power is not set otherwise.

core nominal_power <nominal_power>

<nominal_power> : core nominal power (default 1.0 W)

radial_boundary_coeff

Set the boundary albedo for all radial directions for all nodes on the radial boundary of the core for all energy groups.

core radial_boundary_coeff <radial_boundary_coeff>

<radial_boundary_coeff> : boundary albedo for all radial directions for all nodes on the radial boundary of the core (default 0.0)

axial_boundary_coeff

Set the boundary albedo for both axial direction for all nodes on the axial boundary of the core for all energy groups.

core axial_boundary_coeff <axial_boundary_coeff>

<axial_boundary_coeff> : boundary albedo for both axial directions for all nodes on the axial boundaries of the core (default 0.0)

radial_boundary_coeff_group

Set the group-wise boundary albedo for all radial directions for all nodes on the radial boundary of the core.

core radial_boundary_coeff_group <num_group> <radial_boundary_coeff_group_1> <radial_boundary_coeff_group_2> ... <radial_boundary_coeff_group_num_group>

<radial_boundary_coeff_group_n> : boundary albedo of energy group n for all radial directions for all nodes on the radial boundary of the core

axial_boundary_coeff_group

Set the group-wise boundary albedo for both axial direction for all nodes on the axial boundary of the core.

core axial_boundary_coeff_group <num_group> <axial_boundary_coeff_group_1> <axial_boundary_coeff_group_2> ... <axial_boundary_coeff_group_num_group>

<axial_boundary_coeff> : boundary albedo of energy group n for both axial directions for all nodes on the axial boundaries of the core

radial_boundary_coeff_east

Set the boundary albedo for east radial direction for all nodes on the east boundary of the core for all energy groups.

core radial_boundary_coeff_east <radial_boundary_coeff_east>

<radial_boundary_coeff_east> : boundary albedo for east radial direction for all nodes on the east boundary of the core

radial_boundary_coeff_north

Set the boundary albedo for north radial direction for all nodes on the north boundary of the core for all energy groups. Not used for hexagonal or triangular geometries.

core radial_boundary_coeff_north <radial_boundary_coeff_north>

<radial_boundary_coeff_north> : boundary albedo for north radial direction for all nodes on the north boundary of the core

radial_boundary_coeff_west

Set the boundary albedo for west radial direction for all nodes on the west boundary of the core for all energy groups.

core radial_boundary_coeff_west <radial_boundary_coeff_west>

<radial_boundary_coeff_west> : boundary albedo for west radial direction for all nodes on the west boundary of the core

radial_boundary_coeff_south

Set the boundary albedo for south radial direction for all nodes on the south boundary of the core for all energy groups. Not used for hexagonal or triangular geometries.

core radial_boundary_coeff_south <radial_boundary_coeff_south>

<radial_boundary_coeff_south> : boundary albedo for south radial direction for all nodes on the south boundary of the core

radial_boundary_coeff_northeast

Set the boundary albedo for northeast radial direction for all nodes on the northeast boundary of the core for all energy groups. Not used for rectangular geometry.

core radial_boundary_coeff_northeast <radial_boundary_coeff_northeast>

<radial_boundary_coeff_northeast> : boundary albedo for northeast radial direction for all nodes on the northeast boundary of the core

radial_boundary_coeff_northwest

Set the boundary albedo for northwest radial direction for all nodes on the northwest boundary of the core for all energy groups. Not used for rectangular geometry.

core radial_boundary_coeff_northwest <radial_boundary_coeff_northwest>

<radial_boundary_coeff_northwest> : boundary albedo for northwest radial direction for all nodes on the northwest boundary of the core

radial_boundary_coeff_southwest

Set the boundary albedo for southwest radial direction for all nodes on the southwest boundary of the core for all energy groups. Not used for rectangular geometry.

core radial_boundary_coeff_southwest <radial_boundary_coeff_southwest>

<radial_boundary_coeff_southwest> : boundary albedo for southwest radial direction for all nodes on the southwest boundary of the core

radial_boundary_coeff_southeast

Set the boundary albedo for southeast radial direction for all nodes on the southeast boundary of the core for all energy groups. Not used for rectangular geometry.

core radial_boundary_coeff_southeast <radial_boundary_coeff_southeast>

<radial_boundary_coeff_southeast> : boundary albedo for southeast radial direction for all nodes on the southeast boundary of the core

axial_boundary_coeff_above

Set the boundary albedo for upwards axial direction for all nodes on the upper axial boundary of the core for all energy groups.

core axial_boundary_coeff_above <axial_boundary_coeff_above>

<axial_boundary_coeff_above> : boundary albedo for upwards axial direction for all nodes on the upper axial boundary of the core

axial_boundary_coeff_below

Set the boundary albedo for downwards axial direction for all nodes on the bottom axial boundary of the core for all energy groups.

core axial_boundary_coeff_below <axial_boundary_coeff_below>

<axial_boundary_coeff_below> : boundary albedo for downwards axial direction for all nodes on the bottom axial boundary of the core

axial_dimensions

Currently only used with reflector calculations. This card is currently not documented here.

radial_dimensions

Currently only used with reflector calculations. This card is currently not documented here.

division_x

Divide all input nodes (also called super nodes) into multiple calculation nodes (nodes) in x direction. Not used for hexagonal or triangular geometries.

core division_x <division_x>

<division_x> : number of nodes produced in x direction from each input node. The value has to be divisible with 2.

division_y

Divide all input nodes (also called super nodes) into multiple calculation nodes (nodes) in y direction. Not used for hexagonal or triangular geometries.

core division_y <division_y>

<division_y> : number of nodes produced in y direction from each input node. The value has to be divisible with 2.

division_z

Divide all input nodes (also called super nodes) into multiple calculation nodes (nodes) in z direction.

core division_z <division_z>

<division_z> : number of nodes produced in z direction from each input node.

division_hex

Divide all input nodes (also called super nodes) into multiple calculation nodes (nodes) in radial plane. Not used for rectangular or hexagonal geometries. Has to be divisible with 6, and with 4 if the value is greater than 6.

core division_hex <division_hex>

<division_hex> : number of nodes produced in radial plane from each input node.

fuel

Describe fuel and reflector material distributions and state variable distributions in geometry.

Sub-blocks:

• type
• assembly
• load
• rotation
• burnup
• hdco
• tfu
• bor
• dco
• dco_out
• tco
• xen
• sam
• zdf_above
• zdf_below

type

Add fuel or reflector element type.

fuel type <identifier> [description <description> nodes <nodes> subs <subs>]

<identifier> : name of the fuel type to be used for example in fuel load

<description> : description of the fuel type. Currently not used for anything. Optional.

<nodes> : material identifiers for each axial input node of the fuel beginning from the bottom of the core and ending at the top of the core (number of input: core axial_nodes). Includes possible axial reflector nodes. Reflector nodes are specified using "-" character before the material identifier, without a separating space. Either nodes or subs has to be specified.

<subs> : fuel type identifiers for constructing a possibly radially asymmetrical fuel assembly. Not used for hexagonal geometry. The input for rectangular geometry is the fuel type identifiers for NW, NE, SW, SE quarters of the element and the input for triangular geometry is the fuel type identifiers for NW, NE, W, E, SW, SE sixths of the element. See also Ants discontinuity factor rotations. Either subs or nodes has to be specified.

load

Specify fuel load map.

fuel load <identifiers>

<identifiers> : a list of fuel or reflector element identifiers (number of input: core rows*core columns). An identifier "0" is used to represent an empty location. The map runs fastest in the x direction (columns) and then y direction (rows) such that the first row is the northernmost row and the last row is the southernmost row. For hexagonal maps (used in hexagonal and triangular geometry) the row wrap is interpreted such that the first entry on each row is located in the southeast direction of the first hexagon entry on the previous row.

rotation

Specify fuel and control element radial rotation map. Rotation applies for elements, elements defined using subs, and all discontinuity factors and pin power form functions.

fuel rotation <rotations>

<rotations> : a list of rotations (number of input: core rows*core columns). An identifier "0" is used to represent an empty location. The map runs fastest in the x direction (columns) and then y direction (rows) such that the first row is the northernmost row and the last row is the southernmost row. For hexagonal maps (used in hexagonal and triangular geometry) the row wrap is interpreted such that the first entry on each row is located in the southeast direction of the first hexagon entry on the previous row.

• Rectangular geometry:

• E or 1: East direction of the assembly faces east
• N or 2: East direction of the assembly faces north
• W or 3: East direction of the assembly faces west
• S or 4: East direction of the assembly faces south
• -E or 5: Assembly is flipped such that north and south are interchanged and then east direction of the assembly faces east
• -N or 6: Assembly is flipped such that north and south are interchanged and then east direction of the assembly faces north
• -W or 7: Assembly is flipped such that north and south are interchanged and then east direction of the assembly faces west
• -S or 8: Assembly is flipped such that north and south are interchanged and then east direction of the assembly faces south

• Hexagonal and triangular geometry:

• E or 1: East direction of the assembly faces east
• NE or 2: East direction of the assembly faces north-east
• NW or 3: East direction of the assembly faces north-west
• W or 4: East direction of the assembly faces west
• SW or 5: East direction of the assembly faces south-west
• SE or 6: East direction of the assembly faces south-east

• See also Ants discontinuity factor rotations

burnup

Specify fixed burnup distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel burnup <burnups>

<burnups> : a list of burnups (number of input: core axial nodes*core rows*core columns, unit: MWd/kgU)

hdco

Specify fixed historical coolant density distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel hdco <hdcos>

<hdcos> : a list of historical coolant densities (number of input: core axial nodes*core rows*core columns, unit: g/cm^3)

tfu

Specify fixed fuel temperature distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel tfu <tfus>

<tfus> : a list of fuel temperatures (number of input: core axial nodes*core rows*core columns, unit: K)

bor

Specify fixed boron distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel bor <bors>

<bors> : a list of borons (number of input: core axial nodes*core rows*core columns, unit: ppm)

dco

Specify fixed coolant density distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel dco <dcos>

<dcos> : a list of coolant densities (number of input: core axial nodes*core rows*core columns, unit: g/cm^3)

dco_out

Specify fixed unheated coolant density distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel dco_out <dco_outs>

<dco_outs> : a list of unheated coolant densities (number of input: core axial nodes*core rows*core columns, unit: g/cm^3)

tco

Specify fixed coolant temperature distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel tco <tcos>

<tcos> : a list of coolant temperatures (number of input: core axial nodes*core rows*core columns, unit: K)

xen

Specify fixed Xe-135 distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel xen <xens>

<xens> : a list of Xe-135 densities (number of input: core axial nodes*core rows*core columns, unit: 1/cm^3)

sam

Specify fixed Sm-149 distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel sam <sams>

<sams> : a list of Sm-149 densities (number of input: core axial nodes*core rows*core columns, unit: 1/cm^3)

zdf_above

Specify fixed axial discontinuity factor distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel zdf_above <zdf_aboves>

<zdf_aboves> : a list of axial discontinuity factors on top side of input nodes (number of input: core axial nodes*core rows*core columns)

zdf_below

Specify fixed axial discontinuity factor distribution for input nodes for testing purposes. In realistic calculations, this is done via the Cerberus interface.

fuel zdf_below <zdf_belows>

<zdf_belows> : a list of axial discontinuity factors on bottom side of input nodes (number of input: core axial nodes*core rows*core columns, unit: MWd/kgU)

controlrod

Describe control element distributions in geometry.

Sub-blocks:

• type
• position
• group
• individual

type

Add control element type.

controlrod type <identifier> [description <description> parts <parts> lengths <lengths> nodes <nodes> subs <subs>]

<identifier>  : name of the control element type to be used for example in controlrod position

<description> : description of the control element type. Currently not used for anything. Optional.

<parts>  : number of parts of the control element absorber

<lengths>  : lengths of the parts of the control element absorber (number of input: controlrod type parts, unit cm)

<nodes>  : material identifiers for each axial input node and control element absorber part of the control element beginning from the bottom of the core and ending at the top of the core (number of input: core axial_nodes*controlrod type parts). Includes possible axial reflector nodes. Reflector nodes are specified using "-" character before the material identifier, without a separating space. Fastest running index is the axial layer and the slowest index is the control element type. The input means that for a specific axial layer of the core, the corresponding material identifier is used if the specific control element absorber part is present in the axial node. Either nodes or subs has to be specified.

<subs>  : control elemenent type identifiers for constructing a possibly radially asymmetrical control element. Not used for hexagonal geometry. The input order for rectangular geometry is the controlrod element type identifiers for NW, NE, SW, SE quarters of the element and the input order for triangular geometry is the controlrod element type identifiers for NW, NE, W, E, SW, SE sixths of the element. See also Ants discontinuity factor rotations‎‎. Either subs or nodes has to be specified.

position

Specify control element position map.

controlrod position <identifiers>

<identifiers> : a list of control element identifiers (number of input: core rows*core columns). An identifier "0" is used to represent an empty location. The map runs fastest in the x direction (columns) and then y direction (rows) such that the first row is the northernmost row and the last row is the southernmost row. For hexagonal maps (used in hexagonal and triangular geometry) the row wrap is interpreted such that the first entry on each row is located in the southeast direction of the first hexagon entry on the previous row.

group

Specify control element group related variables

controlrod group [load <identifiers> height <identifier> <unit> <height>]

<identifiers> : a list of control element group identifiers (number of input: core rows*core columns). An identifier "0" is used to represent an empty location. The map runs fastest in the x direction (columns) and then y direction (rows) such that the first row is the northernmost row and the last row is the southernmost row. For hexagonal maps (used in hexagonal and triangular geometry) the row wrap is interpreted such that the first entry on each row is located in the southeast direction of the first hexagon entry on the previous row.

<identifier> : identifier of the control element group of which height is specified

<unit> : unit of the height

• cm: cm from the bottom of the core (including possible axial reflectors)
• node: number of full node positions from the bottom of the core (including possible axial reflectors).
• percentage: relative fraction of the full core height (including possible axial reflectors) in percent from the bottom of the core (including possible axial reflectors).

<height> : height of the control element group

iteration

Set iteration parameters.

Sub-blocks:

• conv_crit_keff
• conv_crit_boron
• conv_crit_fsrc
• conv_crit_fsrc_l2
• conv_crit_flux
• conv_crit_partial_current
• conv_crit_poison_density
• conv_crit_power
• num_inner
• num_cgr
• max_outer
• use_cgr
• use_cmr
• use_relaxation
• use_color
• use_discontinuity_factor
• relaxation_factor
• use_mdep
• xenon_state
• samarium_state
• power
• flux
• nufission_rate
• flux_fuel
• normalization_type
• keff
• boron
• control_variable
• use_boron_relaxation
• boron_relaxation_factor
• critical_node_method
• eigenvalue_real_limit
• eigenvalue_critical_limit
• critical_node_shift
• boron_method
• use_exponential_transformation
• update_omega

conv_crit_keff

iteration conv_crit_keff <conv_crit_keff >

<conv_crit_keff> : convergence criterion for absolute value change of effective multiplication factor between consecutive outer iterations (default 1E-7)

conv_crit_boron

iteration conv_crit_boron <conv_crit_boron >

<conv_crit_boron > : convergence criterion for absolute value change of boron concentration (ppm) between consecutive outer iterations (default 1E-2)

conv_crit_fsrc

iteration conv_crit_fsrc <conv_crit_fsrc >

<conv_crit_fsrc > : convergence criterion for maximum of the absolute value of node wise relative fission source change between consecutive outer iterations (default 1E-5)

conv_crit_fsrc_l2

iteration conv_crit_fsrc_l2 <conv_crit_fsrc_l2 >

<conv_crit_fsrc_l2 > : convergence criterion for change of L2 norm of node-integrated fission sources between consecutive outer iterations (default 1.0)

conv_crit_flux

iteration conv_crit_flux <conv_crit_flux>

<conv_crit_flux> : convergence criterion for maximum of the absolute value of node and group wise relative flux change between consecutive outer iterations (default 1.0)

conv_crit_partial_current

iteration conv_crit_partial_current <conv_crit_partial_current>

<conv_crit_partial_current> : convergence criterion for maximum of the absolute value of node, group, and moment wise relative outgoing physical partial current relative change between consecutive outer iterations (default 1.01)

conv_crit_poison_density

iteration conv_crit_poison_density <conv_crit_poison_density>

<conv_crit_poison_density > : convergence criterion for maximum of the absolute value of node wise relative poison nuclide (I-135, Xe-135m, Xe-135, Pm-149, Sm-149) density change between consecutive outer iterations (default 1.0)

conv_crit_power

iteration conv_crit_power <conv_crit_power>

<conv_crit_power> : convergence criterion for absolute value change of total power (W) between consecutive outer iterations (default 1.0)

num_inner

Set the number of inner iterations per outer iteration.

iteration num_inner <num_inner>

<num_inner> : number of inner iterations per outer iteration (default 50)

num_cgr

Set the number of coarse group rebalance (CGR) or coarse mesh rebalance (CMR) iterations per outer iteration. CGR/CMR is not used if boron is used as iteration control_variable.

iteration num_cgr <num_cgr/num_cmr>

<num_cgr/num_cmr> : number of coarse group rebalance (CGR) or coarse mesh rebalance (CMR) per outer iteration (default 4)

max_outer

Set the maximum number of outer iterations per calculation step. Currently not used for anything.

iteration max_outer <max_outer>

<max_outer> : maximum number of outer iterations per calculation step (default huge(0))

use_cgr

Either use or do not use coarse group rebalance (CGR) iteration during the outer iterations or calculate current effective multiplication factor from current node wise values. CGR is not used if boron is used as iteration control_variable.

iteration use_cgr <flag>

<flag>

• 1/y/yes/on/true : coarse group rebalance (CGR) iteration is used (default). Disables use of CMR.
• everything else : coarse group rebalance (CGR) iteration is not used

use_cmr

Either use or do not use coarse mesh rebalance (CMR) iteration during the outer iterations or calculate current effective multiplication factor from current node wise values. CMR is not used if boron is used as iteration control_variable.

iteration use_cmr <flag>

<flag>

• 1/y/yes/on/true : coarse mesh rebalance (CMR) iteration is used. Disables use of CGR.
• everything else : coarse mesh rebalance (CMR) iteration is not used (default)

use_relaxation

Either use partial current relaxation during inner iterations or not. Relaxation coefficient is given with iteration relaxation_factor. Enabling might not work with all neutronics models and other option combinations, ensure from source code.

iteration use_relaxation <flag>

<flag>

• 1/y/yes/on/true : relaxation is used
• everything else : relaxation is not used (default)

use_color

Either use color iteration during the inner iterations or iterate one node at a time in the node indexing order. Two color iteration scheme is used for rectangular and triangular geometries, and four color iteration scheme for hexagonal geometry. Disabling might not work with all neutronics models and other option combinations, ensure from source code.

iteration use_color <flag>

<flag>

• 1/y/yes/on/true : color iteration is used (default)
• everything else : color iteration is not used

use_discontinuity_factor

Either use discontinuity factors in the neutronics solution or not. Disabling might not work with all neutronics models and other option combinations, ensure from source code.

iteration use_discontinuity_factor <flag>

<flag>

• 1/y/yes/on/true : discontinuity factors are used if given in group constant input (default)
• everything else : discontinuity factors are not used

use_mdep

Either use microscopic depletion during burnup calculation or not. Disabling might not work with all neutronics models and other option combinations, ensure from source code.

iteration use_mdep <flag>

<flag>

• 1/y/yes/on/true : microscopic depletion is used if given in group constant input (default)
• everything else : microscopic depletion is not used

relaxation_factor

Set the partial current relaxation factor during inner iterations.

iteration relaxation_factor <relaxation_factor>

<relaxation_factor> : partial current relaxation factor during inner iterations. The new partial currents are multiplied with this value and added to the old partial currents multiplied with (1.0 minus relaxation_factor) (default 1.0, i.e. no relaxation even if iteration use_relaxation would be on)

xenon_state

Set node-wise I-135, Xe-135m and Xe-135 concentration state for calculation. Behavior and usable options depend on group constant model. I-135 and Xe-135m may be completely untouched depending on group constant model.

iteration xenon_state <state>

<state>

• zero: node-wise I-135, Xe-135m and Xe-135 concentrations will be set to zero
• fixed : node-wise I-135, Xe-135m and Xe-135 concentration will stay the values they are before initiating the calculation
• equilibrium : node-wise I-135, Xe-135m and Xe-135 concentrations will be set to the equilibrium values calculated to match the current node power level.
• dynamic: node-wise I-135, Xe-135m and Xe-135 concentrations will be calculated using time dependent equations.
• depletion: node-wise I-135, Xe-135m and Xe-135 concentrations will be accumulated during burnup calculation.

samarium_state

Set node-wise Pm-149 and Sm-149 concentration state for calculation. Behavior and usable options depend on group constant model.

iteration samarium_state <state>

<state>

• zero: node-wise Pm-149 and Sm-149 concentrations will be set to zero
• fixed : node-wise Pm-149 and Sm-149 concentrations will stay at the values they are before initiating the calculation
• equilibrium : node-wise Pm-149 and Sm-149 concentrations will be set to the equilibrium values calculated to match the current node power level. May also mean using Pm-149 and Sm-149 absorption values included in group constants.
• plus_promethium: node-wise Pm-149 will be set to zero. Sm-149 concentration will be set to the equilibrium value of Sm-149 plus equilibrium concentration of Pm-149 (as if all Pm-149 has decayed to Sm-149). Equilibrium value of Sm-149 may also mean the value included in group constants.
• depletion: node-wise Pm-149 and Sm-149 concentrations will be accumulated during burnup calculation.

power

Set the core total power (W).

iteration power <power>

<power> core total power

normalization_type

Set the variable to which the neutronics solution is normalized or disable normalization.

iteration normalization_type <variable>

<variable>

• none  : do not normalize the neutronics solution
• power  : normalize the neutronics solution to total produced neutronics power. The value is given by iteration power (default)
• flux  : normalize the neutronics solution to total flux summed over all energy group and nodes. The value is given by iteration flux
• nufission_rate : normalize the neutronics solution to total fission neutron production summed over all groups and nodes. The value is given by iteration nufission_rate
• flux_fuel  : normalize the neutronics solution to total flux summed over all groups and only fuel nodes. The value is given by iteration flux_fuel

keff

Set the effective multiplication factor initial value for keff iteration control_variable or value for other control variables.

iteration keff <keff>

<keff> effective multiplication factor initial value or value

boron

Set the boron concentration (ppm) initial value for boron iteration control_variable or global concentration value for other control variables.

iteration boron <boron>

<boron> boron concentration initial value or value

control_variable

Set the control variable for critical variable iteration.

iteration control_variable <variable>

<variable>

• none : do not iterate a criticality parameter in the neutronics solution
• keff : iterate a critical effective multiplication factor. Value is calculated during the CGR or CMR iterations, if one is used, or with a direct balance method otherwise.
• boron: iterate a critical global boron concentration. CGR or CMR is not used. The method for estimating the critical boron concentration currently depends on the group constant model. See also iteration use_boron_relaxation and iteration boron_relaxation_factor.

use_boron_relaxation

Either use relaxation of the critical boron concentration or not.

iteration use_boron_relaxation <flag>

<flag>

• 1/y/yes/on/true : critical boron concentration relaxation is used (default). See also iteration boron_relaxation_factor.
• everything else : critical boron concentration relaxation is not used

boron_relaxation_factor

Set the critical boron concentration relaxation factor during outer iterations.

iteration boron_relaxation_factor <relaxation_factor>

<relaxation_factor> : critical boron concentration relaxation factor during outer iterations. The new boron concentration is multiplied with this value and added to the old boron concentration multiplied with (1.0 minus relaxation_factor) (default 0.5)

critical_node_method

Set the method used to handle near critical nodes (real eigenvalue absolute value less than or equal to value given in eigenvalue_critical_limit. Methods will be studied further and added in future.

iteration critical_node_method <method>

<method>

• keff_shift  : add the value given in critical_node_shift to keff value in the near critical node. Neutron balance will not be correct.
• mode_flux_limit : assume near critical eigenvalue to be exactly zero and use pseudo inverse instead of inverse for inverting matrix Qin. Will not represent all linear cross term fluxes.
• fix_eigenvalue  : assume near critical eigenvalue to be exactly eigenvalue_critical_limit with the same sign as the near critical eigenvalue.

eigenvalue_real_limit

Set a tolerance value for the absolute value of the imaginary part of an eigenvalue

iteration eigenvalue_real_limit <limit>

<limit> : if the absolute value of the imaginary part of an eigenvalue is below this value, set it to zero

eigenvalue_critical_limit

Set a tolerance value for the absolute value of the real part of an eigenvalue, under which the node is treated to be near critical

iteration eigenvalue_critical_limit <limit>

<limit> : if the absolute value of the real part of an eigenvalue is below this value, treat the node as near critical

critical_node_shift

Set keff shift value for a near critical node if used.

iteration critical_node_shift <value>

<value> : value to be added in the keff used in a near critical node

boron_method

Set method used to solve critical boron concentration.

iteration boron_method <method>

<method >

• balance : estimate critical boron directly from neutron balance equation (default)
• secant  : estimate critical boron using the secant method from the actual keffs with current and previous boron concentrations

use_exponential_transformation

Either use exponential transformation of the neutron flux in time dependent equations or not.

iteration use_exponential_transformation <flag>

<flag>

• 1/y/yes/on/true : exponential transformation is used (default).
• everything else : exponential transformation is not used

update_omega

Either use update omega values used with exponential transformation of the neutron flux with the flux values obtained during the current time step iteration or not.

iteration use_exponential_transformation <flag>

<flag>

• 1/y/yes/on/true : omega values are updated during the iteration of the current time step (values calculated from flux of the current time step and the previous time step) (default).
• everything else : omega values calculated from the fluxes of the two previous time steps.

library

Set group constant library parameters.

Sub-blocks:

• type
• path

type

Set group constant library type.

library type <type>

<type>

• hexbu-3d/mod5 : HEXBU-3D/MOD5 group constant file format for hexagonal geometry (HEXBU-3D/VVER)
• hexbu-3d/mod5-trab3d : HEXBU-3D/MOD5 group constant file format for rectangular geometry (TRAB3D/BWR/PWR)
• nemtab: NEMTAB group constant file format
• polynomial: polynomial group constant file format
• simple : simple group constant file format

path

Set group constant library input file path

library path <path>

<path> : at most one token for the group constant library input file path. The path is relative to current working directory.

start

Start the calculation.

start

end

End the calculation.

end

Group constant files

HEXBU-3D/MOD5

Ants supports HEBXU-3D/MOD5 group constant file format files for both HEXBU-3D and TRAB3D formats (usually used for VVER and PWR/BWR, respectively). See also library type. The NHET parameter in the NOMCON-record has an additional supported value of -4 described in Ants/doc/square_df_rotation.txt. Remember the maximum line length of 80 characters in BINPUT readable files.

Polynomial

See report on polynomial group constant file format.

NEMTAB

When using the NEMTAB group contant file format, an file describing the contents of the actual NEMTAB group constant files is required. The input syntax is similar with the main input file syntax.

Main blocks

• nemtab
• file_type
• xs_type
• num_group
• num_prec_group
• file

nemtab

Has to be the first input card in the file. Mandatory input.

nemtab group constant library

file_type

Specify how the materials are defined using file cards. Mandatory input.

file_type <file_type>

<file_type >

• 1 : multiple materials in one file, possibly more than one file per file card. First file card defines unrodded materials, second 1st control rod part materials, third 2nd control rod part materials etc. If more than one file given per file card, the materials in second file are numbered as follows. If there are <10 materials in the first file, the first material in the second file is number 11, and the second materials is number 12. If there are <100 materials, the first material in the second file is number 101, and the second material is 102 etc. The third file will be numbered 21, 22, ... or 201, 202, ... and so on.

xs_type

Specify which state variables are given in the files given by file cards and how the files are structured. Mandatory input.

xs_type <xs_type>

<xs_type>

• 1 : "T Fuel, T Mod, Rho Mod, Boron", fitting table at the beginning of each group constant, not compatible with burnup, only two energy groups, group 1 assumed first, after scattering 1->2 group 2 assumed.
• 2 : "T Fuel, Rho Mod, Boron, T Mod", otherwise as <xs_type> = 1.

num_group

Specify how many energy groups are used in file cards. Mandatory input.

num_group <num_group>

<num_group > : number of energy groups

num_prec_group

Specify how many delayed neutron precursor groups are used in file cards. Mandatory input.

num_prec_group <num_prec_group>

<num_prec_group> : number of precursor groups

file

Specify group constant data files. If <file_type> = 1, first occurrence of file card specifies unrodded group constants, the second the 1st control rodded group constants and so on.

file <file1> [ <file2> ... ]

<filen> : path to the group constant data file n. With increasing n, the prefix of material numbers increases, see file_type card.

Simple

A simple group constant file format to be used for example for numerical neutronics benchmarks. The input syntax is similar with the main input file syntax.

Main blocks

• simple
• material
• end
• groups
• precursors
• radialdfs
• axialdfs
• absorption
• nufission
• kappafission
• totalfissionspectrum
• diffusioncoefficient
• transport
• radialdiscontinuityfactor
• axialdiscontinuityfactor
• inversevelocity
• delayedneutronfraction
• precursordecayconstant
• nu
• kappa
• kappamev
• fission
• velocity
• scattering
• removal
• is_void
• ppr_num_pin
• ppr_x
• ppr_y
• ppr_width_x
• ppr_width_y
• ppr_form_function
• is_df_quarter