# Difference between revisions of "Input syntax manual"

Serpent has no interactive user interface. All communication between the code and the user is handled through one or several input files and various output files.

The format of the input file is unrestricted. The file consists of white-space (space, tab or newline) separated words, containing alphanumeric characters(’a-z’, ’A-Z’, ’0-9’, ’.’, ’-’). If special characters or white spaces need to be used within the word (file names, etc.), the entire string must be enclosed within quotes.

The input file is divided into separate data blocks, denoted as cards. The file is processed one card at a time and there are no restrictions regarding the order in which the cards should be organized. The input cards are listed below. Additional options are followed by key word "set". All input cards and options are case-insensitive (note to developers: make it so). Each input card is delimited by the beginning of the next card. It is hence important that none of the parameter strings used within the card coincide with the card identifiers.

The percent-sign ('%') is used to define a comment line. Anything from this character to the end of the line is omitted when the input file is read. Unlike Serpent 1, hashtag ('#') can no longer be used to mark comment lines in Serpent 2 input. The alternative is to use C-style comment sections beginning with "/*" and ending with "*/". Everything between these delimiters is omitted, regardless of the number of newlines or special characters.

This page will contain the whole input syntax of Serpent 2, with links to more detailed descriptions where needed. For reference see also the Serpent 1 input manual[1].

## Input cards

NOTE: Serpent command words are in boldface and input parameters entered by the user in CAPITAL ITALIC. Optional input parameters are enclosed in [ square brackets ], and when the number of values is not fixed, the remaining values are marked with three dots (...).

### branch (branch definition)

branch NAME [ repm MAT1 MAT2 ]
[ repu UNI1 UNI2 ]
[ stp MAT DENS TEMP THERM1 SABL1 SABH1 THERM2 SABL2 SABH2 ... ]
[ tra TGT TRANS ]
[ xenon OPT ]
[ samarium OPT ]
[ norm NSF ]
[ gcu UNI2 ]
[ reptrc FILE1 FILE2 ]
[ var VNAME VAL ]


Defines the variations invoked for a branch in the automated burnup sequence. Input values:

 NAME : branch name MAT1 : name of the replaced material MAT2 : name of the replacing material UNI1 : name of the replaced universe UNI2 : name of the replacing universe MAT : name of the material for which density and temperature are adjusted DENS : material density after adjustment (positive entries for atomic, negative entries for mass densities) TEMP : material temperature after adjustment, or -1 if no adjustment in temperature THERMn : nth thermal scattering data associated with the material SABLn : name of the nth S(α, β) library for temperature below the given value SABHn : name of the nth S(α, β) library for temperature above the given value TGT : target universe, surface or cell TRANS : name of the applied transformation OPT : option for setting poison concentrations (0 = set to zero, 1 = use values from restart file) NSF : normalization scaling factor FILE1 : file path of the replaced transport correction curve data FILE2 : file path of the replacing transport correction curve data VNAME : variable name VAL : variable value

Notes:

• The branch name identifies the branch in the coefficient matrix of the coef card
• The input parameters consist of a number variations, which are invoked when the branch is applied. A single branch card may inclued one or several variations.
• The repm variation can be used to replace one material with another, for example, to change coolant boron concentration.
• The material replacement works as if MAT1 were created using the mat or mix card of MAT2.
• The name of the material present in the geometry will still be MAT1 after the replacement, but the material specification (composition, density, tmp, moder, rgb, etc.) will correspond to MAT2.
• This means that all other input-cards that are linked to a specific material name such as det dm, src sm, set trc and set iter nuc can be linked to the original material (MAT1) and they will automatically apply to whatever material MAT2 replaces MAT1 for the branch calculation.
• The repu variation can be used to replace one universe with another, for example, to replace empty control rod guide tubes with rodded tubes for control rod insertion in 2D geometries.
• The name of the universe present in the geometry will still be UNI1 after the replacement, but the universe contents will correspond to UNI2.
• This means that all other input-cards that are linked to a specific universe name such as det du and src su can be linked to the original universe (UNI1) and they will automatically apply to whatever universe UNI2 replaces UNI1 for the branch calculation.
• The stp variation can be used to change material density and temperature. The adjustment is made using the built-in Doppler-broadening preprocessor routine and tabular interpolation for S(α, β) thermal scattering data.
• The last three parameters of the stp entry are provided only if the material has thermal scattering libraries attached to it (see the therm card).
• The tra variation can be used to move or rotate different parts of the geometry, for example, to adjust the position of control rods in 3D geometries. The name of the transformation refers to the unit (universe, cell or surface) entry in the trans card.
• The xenon and samarium options can be set to enforce the concentrations of fission product poisons Xe-135 and Sm-149 to zero. By default the concentrations are read from the restart file.
• The norm variation can be used to change the normalization. The adjustment is made applying the parameter NSF as a multiplicative scaling factor to the given normalization.
• The gcu variation can be used to replace the universe for group constant generation. This variation is limited to a single-valued GCU-list.
• The reptrc variation can be used to replace a transport correction file with another.
• Variables can be used to pass information into output file, which may be convenient for the post-processing of the data.
• The branch card is used together with the coef card.
• For more information, see detailed description on the automated burnup sequence.
• The replaced material MAT1 of repm variation is also replaced inside mixtures. This means one can not replace a material with a mixture defined with mix card containing the replaced material (for example replacing pure water defined with mat card by a mixture of boron and water defined with a mix card containing the same pure water material).
• The replacing material MAT2 of repm variation can not be included in geometry using other cards than the branch card with the repm variation, version 2.1.30.
• The "sum" option to define the material density as the sum of the constituent nuclide densities is not supported from version 2.2.0 and on.

### casematrix (casematrix definition)

casematrix CASE_NAME
NHIS [ HIS_BR1 HIS_BR2 ... HIS_BRNHIS ]
NBU  [ BU1 BU2 ... BUNBU ]
NBR1 [ BR1,1 BR1,2 ... BR1,NBR1 ]
NBR2 [ BR2,1 BR2,2 ... BR1,NBR2 ]
...


Defines the casematrix for the automated burnup sequence. Input values:

 CASE_NAME : name of the casematrix NHIS : number of history variations HIS_BRk : name of the kth history variation branch NBU : number of burnup points BUn : burnup steps at which the momentary variation branches are invoked NBRm : number branches in the mth dimension of the burnup matrix BRm,i : name of the ith branch in the mth dimension

Notes:

• The casematrix card performs multiple depletions with NHIS (different) historical variations and performs restarts similar as the coef input card.
• The casematrix card creates a multi-dimensional coefficient matrix (of size NBR1 × NBR2 × NBR3 × ... ). The automated burnup sequence performs a restart for each of the listed burnup points, and loops over the branch combinations defined by the coefficient matrix. This is repeated for each different depletion history.
• Positive values in the burnup vector are interpreted as (MWd/kgU), negative values are interpreted as time steps in days.
• The casematrix card is used together with the branch card and -casematrix running option.
• Multiple casematrix cards can be given in a single input file.
• For more information, see detailed description on automated burnup sequence.

### cell (cell definition)

cell NAME UNI0 MAT [ SURF1 SURF2 ... ]


Defines a material cell. Input values:

 NAME : cell name UNI0 : universe where the cell belongs to MAT : material that fills the cell SURFn : surface list
cell NAME UNI0 fill UNI1 [ SURF1 SURF2 ... ]


Defines a filled cell. Input values:

 NAME : cell name UNI0 : universe where the cell belongs to UNI1 : universe that fills the cell SURFn : surface list
cell NAME UNI0 outside [ SURF1 SURF2 ... ]


Defines an outside cell. Input values:

 NAME : cell name UNI0 : universe where the cell belongs to SURFn : surface list

Notes:

• There are three types of cells: material cells, filled cells and outside cells. Filled cells are identified by providing the key word fill, followed by the universe filling the cell. If the key word is missing, the third entry is interpreted as the material filling the cell. Outside cells are identified by replacing the material name with key word outside.
• Cells defined without surfaces are treated as infinite, from version 2.1.32 on.
• Void cells can be defined by setting the material name to "void"
• When the geometry is set up, the root universe must always be defined. By default the root universe is named "0", and it can be changed with the set root option.
• Outside cells are used to define the part of the geometry that does not belong to the model. When the particle enters an outside cell, boundary conditions are applied. It is important that the geometry model is non-re-entrant (convex) when vacuum boundary conditions are used. Delta-tracking might miss the boundary conditions in a re-entrant (concave) outer surface.
• Outside cells are allowed only in the root universe. It is important that all space outside the model is defined.
• The surface list defines the boundaries of the cell by listing the surface names (as provided in the surface card), together with the operator identifiers (nothing for intersection, ":" for union, "-" for complement and "#" for cell complement).
• Universes are implicitly declared for example by using the UNI0 key words on cell cards as there is no explicit universe input card.
• For more information, see detailed description on the universe-based geometry type in Serpent.

### coef (coefficient matrix definition)

coef NBU [ BU1 BU2 ... ]
[ NBR1 BR1,1 BR1,2 ... ]
[ NBR2 BR2,1 BR2,2 ... ]
...


Defines the coefficient matrix for the automated burnup sequence. Input values:

 NBU : number of burnup points BUn : burnup steps at which the branches are invoked NBRm : number branches in the mth dimension of the burnup matrix BRm,i : name of the ith branch in the mth dimension

Notes:

• The coef card creates a multi-dimensional coefficient matrix (of size NBR1 × NBR2 × NBR3 × ... ). The automated burnup sequence performs a restart for each of the listed burnup points, and loops over the branch combinations defined by the coefficient matrix.
• Positive values in the burnup vector are interpreted as (MWd/kgU), negative values are interpreted as time steps in days.
• The coef card is used together with the branch card.
• For multiple historical variations or historical conditions defined using a branch card, see the casematrix card.
• For more information, see detailed description on automated burnup sequence.

### datamesh (general data mesh definition)

The datamesh card allows the user to define various meshes that can be used for spatial discretization e.g. in detectors.

datamesh NAME 1 USELC NX XMIN XMAX NY YMIN YMAX NZ ZMIN ZMAX


Defines a regular Cartesian mesh that can be linked to detectors, interfaces etc.

 NAME : mesh name USELC : use lowest level coordinates (1/yes) instead of global coordinates (0/no) for the mesh search NX : number of cells in the x direction XMIN : mesh lower x boundary XMAX : mesh higher x boundary NY : number of cells in the y direction YMIN : mesh lower y boundary YMAX : mesh higher y boundary NZ : number of cells in the z direction ZMIN : mesh lower z boundary ZMAX : mesh higher z boundary
datamesh NAME 2 USELC NR RMIN RMAX NPHI


Defines a regular 2D cylindrical mesh that can be linked to detectors, interfaces etc.

 NAME : mesh name USELC : use lowest level coordinates (1/yes) instead of global coordinates (0/no) for the mesh search NR : number of cells in the radial direction RMIN : mesh inner radial boundary RMAX : mesh outer radial boundary NPHI : number of cells in the polar angle direction
X-type hexagonal mesh horizontal indexing example for NX = NY = 3.
datamesh NAME 4 USELC X0 Y0 PITCH ZMIN ZMAX NX NY NZ


Defines a regular x-type hexagonal mesh that can be linked to detectors, interfaces etc.

 NAME : mesh name USELC : use lowest level coordinates (1/yes) instead of global coordinates (0/no) for the mesh search X0 : mesh horizontal origin x-coordinate Y0 : mesh horizontal origin y-coordinate PITCH : mesh horizontal pitch (equal to cell flat-to-flat width) ZMIN : mesh lower z boundary ZMAX : mesh higher z boundary NX : number of cells in the x direction NY : number of cells in the y direction NZ : number of cells in the z direction
Y-type hexagonal mesh horizontal indexing example for NX = NY = 3.
datamesh NAME 5 USELC X0 Y0 PITCH ZMIN ZMAX NX NY NZ


Defines a regular y-type hexagonal mesh that can be linked to detectors, interfaces etc.

 NAME : mesh name USELC : use lowest level coordinates (1/yes) instead of global coordinates (0/no) for the mesh search X0 : mesh horizontal origin x-coordinate Y0 : mesh horizontal origin y-coordinate PITCH : mesh horizontal pitch (equal to cell flat-to-flat width) ZMIN : mesh lower z boundary ZMAX : mesh higher z boundary NX : number of cells in the x direction NY : number of cells in the y direction NZ : number of cells in the z direction
datamesh NAME 6 USELC NX NY NZ  X1 ... XNX+1  Y1 ... YNY+1  Z1 ... ZNZ+1


Defines an irregular Cartesian mesh that can be linked to detectors, interfaces etc.

 NAME : mesh name USELC : use lowest level coordinates (1/yes) instead of global coordinates (0/no) for the mesh search NX : number of cells in the x direction NY : number of cells in the y direction NZ : number of cells in the z direction Xi : NX + 1 mesh boundaries in the x direction Yi : NY + 1 mesh boundaries in the y direction Zi : NZ + 1 mesh boundaries in the z direction
datamesh NAME 8 USELC NR NPHI  R1 ... RNR+1


Defines a radially irregular 2D cylindrical mesh that can be linked to detectors, interfaces etc.

 NAME : mesh name USELC : use lowest level coordinates (1/yes) instead of global coordinates (0/no) for the mesh search NR : number of cells in the radial direction NPHI : number of cells in the polar angle direction Ri : NR + 1 mesh boundaries in the r direction
datamesh NAME 9 NLEVEL  MESH1 ... MESHNLEVEL


Defines a regular nested mesh that can be linked to detectors, interfaces etc.

 NAME : mesh name USELC : use lowest level coordinates (1/yes) instead of global coordinates (0/no) for the mesh search NLEVEL : number of nested levels in this mesh MESHi : sub mesh to use at level i

Notes:

• When Serpent makes the mesh search for a specific collision point it will save the collision mesh cell temporarily so that the cell search is conducted at most once even when scoring multiple estimators using the same mesh.

### dep (depletion history)

dep STYPE [ STEP1 STEP2 ... ]


Defines depletion history with steps and activates depletion calculation mode. Input values:

 STYPE : step type STEPn : depletion step list

The possible step types are:

Type Description Quantity Unit
bustep Depletion step Burnup interval MWd/kgHM
butot Depletion step Cumulative burnup MWd/kgHM
daystep Depletion step Time interval d
daytot Depletion step Cumulative time d
decstep Decay step Time interval d
dectot Decay step Cumulative time d
actstep Activation step Time interval d
acttot Activation step Cumulative time d

Notes:

• Transport cycle is omitted with the decstep and dectot options.
• Transport cycle is run only once with the actstep and acttot options.
dep pro REP_NAME STYPE [ STEP1 STEP2 ... ]


Links a reprocessor to the depletion calculation. Input values:

 REP_NAME : reprocessor name STYPE : step type STEPn : depletion step list

Notes:

• The reprocessing system or reprocessor controller is defined using the rep card.
dep bra PTR_BRANCH


### det (detector definition)

det NAME [ PART ]
[ dr MT MAT ]
[ dv VOL ]
[ dc CELL ]
[ du UNI ]
[ dm MAT ]
[ dl LAT ]
[ dx XMIN XMAX NX ]
[ dy YMIN YMAX NY ]
[ dz ZMIN ZMAX NZ ]
[ dn TYPE MIN1 MAX1 N1 MIN2 MAX2 N2 MIN3 MAX3 N3 ] 1/2 [ dn TYPE N1 N2 N3 LIM11...LIM1N+1 LIM21...LIM2N+1 LIM31...LIM3N+1 ] 3/4
[ dh TYPE X0 Y0 PITCH N1 N2 ZMIN ZMAX NZ ]
[ dumsh UNI NC CELL0 BIN0 CELL1 BIN1 ... ]
[ de EGRID ]
[ di TBIN ]
[ ds SURF DIR ]
[ dir COSX COSY COSZ ]
[ dtl SURF ]
[ df FILE FRACTION ]
[ dt TYPE PARAM ]
[ dhis OPT ]
[ dfl FLAG OPT ]
[ da MAT FLX ]
[ dfet TYPE PARAMS ]
[ dphb PHB ]
[ dmesh MESH ]


Detector definition. The first parameter:

 PART : particle type (n = neutron, p = photon)

is optional in single particle simulations. The remaining parameters are defined by separate key words followed by the input values.

Detector response (dr):

 MT : response number MAT : material name or "void" if the material at the collision point is used

Notes:

• If the detector is assigned with multiple responses, the results are divided correspondingly into separate bins.
• The response numbers are ENDF reaction MT's and special reaction types.
• Positive response numbers are associated with microscopic cross sections and the result is independent of material density. Materials for microscopic cross sections must consist of a single nuclide.
• Microscopic reactions to ground and isomeric states can be calculated by adding "g" or "m" at the end of the reaction number (e.g. 102g and 102m refer to radiative capture to ground and isomeric states, respectively). This option is available only for nuclides with branching ratios.
• Negative response numbers are associated with macroscopic cross sections and special types, and the result is multiplied by material density.
• The response material in the dr entry must not be confused with the material in the dm entry. The former defines the material for the response function, while the latter determines the volume of integration.
• The "void" entry allows the response not to be pre-assigned with a specific material (when the detector scores in a collision, the cross-section is taken from the material at the collision point - e.g., to calculate integral reaction rates over regions composed of multiple materials) only can be used with negative response numbers.
• By default, Serpent allows a detector to have at most 10,000,000 bins.

Detector volume (dv):

 VOL : volume in cm3 (3D geometry) or cross-sectional area in cm2 (2D geometry)

Notes:

• The results are divided by detector volume, which is by default set to 1.
• In the case of surface detectors, VOL represents the surface area in cm2 (3D geometry) or the surface length in cm (2D geometry).

Detector cell (dc):

 CELL : cell name where the detector is scored

Notes:

• If multiple detector cells are defined, the results are correspondingly divided into multiple bins.

Detector universe (du):

 UNI : universe name where the detector is scored

Notes:

• If multiple detector universes are defined, the results are correspondingly divided into multiple bins.

Detector material (dm):

 MAT : material name where the detector is scored

Notes:

• If multiple detector materials are defined, the results are correspondingly divided into multiple bins.
• The material entry defines the volume of integration, which must not be confused with the response material in the dr entry.

Detector lattice (dl):

 LAT : lattice name where the detector is scored

Notes:

• The lattice detector automatically divides the results into multiple bins corresponding to the lattice cells.

Cartesian mesh detector (dx, dy and dz):

 XMIN : minimum x-coordinate of the detector mesh XMAX : maximum x-coordinate of the detector mesh NX : number of x-bins YMIN : minimum y-coordinate of the detector mesh YMAX : maximum y-coordinate of the detector mesh NY : number of y-bins ZMIN : minimum z-coordinate of the detector mesh ZMAX : maximum z-coordinate of the detector mesh NZ : number of z-bins

Notes:

• The mesh detectors can be used to sub-divide the results into multiple spatial bins. For a Cartesian mesh the division is provided with separate entries in x-, y- and z- locations.

Curvilinear and unevenly-spaced mesh detector (dn):

 TYPE : Type of curvilinear mesh - 1 = cylindrical (dimensions r, θ, z), 2 = spherical (dimensions r, θ, φ), 3 = unevenly-spaced orthogonal (dimensions x, y, z), 4 = unevenly-spaced cylindrical (dimensions r, θ, z) MINn : Minimum value of coordinate n for the mesh division (lengths in cm, angles in degrees). MAXn : Maximum value of coordinate n for the mesh division (lengths in cm, angles in degrees). Nn : Number of bins in the n coordinate direction (the radial division will be equal r, not equal volume, in evenly-spaced types 1/2). LIMnm : Mesh boundary m in the n coordinate direction (lengths in cm, angles in degrees).

Notes:

• All parameters must be provided, even for one- or two-dimensional curvilinear meshes.
• The results are not divided by cell volume (difference to MCNP mesh tally).
• By default, the curvilinear mesh detectors use the global (universe 0) coordinate system for scoring. If the TYPE parameter is given as a negative value (e.g. -1) the lowest level coordinates are used instead.
• The syntax for curvilinear (evenly-spaced) mesh detectors (1/-1, 2/-2) differs from the unevenly-spaced mesh ones (3/-3, 4/-4).

Hexagonal mesh detector (dh):

 TYPE : Type of hexagonal mesh (2 = flat face perpendicular to x-axis, 3 = flat face perpendicular to y-axis) X0, Y0 : coordinates of mesh center PITCH : mesh pitch N1, N1 : mesh size ZMIN : minimum z-coordinate of the detector mesh ZMAX : maximum z-coordinate of the detector mesh NZ : number of z-bins

Notes:

• All parameters must be provided, even for a two-dimensional hexagonal meshes.

Unstructured mesh detector (dumsh):

 UNI : universe of the unstructured mesh based geometry NC : number of mesh cell bins included in the output CELLn, BINn : cell-bin index pairs defining the mapping

Notes:

• The polyhedral cells in unstructured mesh based geometries are indexed.
• This detector option allows collecting results from the cells into an arbitrary number of bins. One or multiple cells can be mapped into a single bin.

Detector energy binning (de):

 EGRID : energy grid name

Notes:

• The results are divided into multiple energy bins based on the grid structure.
• Energy grid structures are defined using the ene card. Pre-defined energy group structures can not be directly used in detectors, they have to be redefined using for example the fourth type of ene card.
• The energy boundaries of photon photon pulse-height and photon heat analog detectors are solely defined by the associated energy grid and not limited by the unionized energy grid defining the model. That means that analog detectors might collect scores below the physics model minimum energy bound, without a cut-off, if the energy grid sets it.

Detector time binning (di):

 TBIN : time bin structure name

Notes:

• The results are divided into multiple time bins.
• Time bin structures are defined using the tme card.
• Time bin division may require adjusting the average collision distance (set cfe option) to achieve sufficient statistical accuracy.

Surface current / flux detector (ds):

 SURF : surface name DIR : direction with respect to surface normal (-2 = flux, -1 = inward current, 1 = outward current, 0 = net current)

Notes:

• With this option the detector calculates the particle flux over or current through a given surface.
• The surface flux mode is invoked by setting the direction parameter to -2, otherwise this parameter defines the current direction with respect to surface normal.
• Responses are not allowed with current detectors, and with flux detectors, the material name at the collision point has to be specified ("void" is not allowed).
• The use of single-bin mesh and cell detectors is allowed to define the integration surface of the detector, from version 2.1.32 on.
• The surface is treated separate from the geometry, and its position is always relative to the origin of the root universe. This is the case even if the surface is part of the geometry in another universe.
• The results are integrated over the surface area (other detectors integrate over volume).

Detector direction vector (dir):

 COSX : component of the direction vector parallel to x-axis COSY : component of the direction vector parallel to y-axis COSZ : component of the direction vector parallel to z-axis

Notes:

• This option multiplies the detector scores with the scalar product between the particle direction of motion and the given direction vector.

Super-imposed track-length detector (dtl):

 SURF : surface inside which the detector is scored

Notes:

• This option can be used to apply the track-length estimator for calculating reaction rates inside regions defined by a single surface (sphere, cylinder, cuboid, etc.)
• The purpose of the track-length detector is to provide better statistics for special applications (activation wire measurements, etc.).
• The surface is treated separate from the geometry, and its position is always relative to the origin of the root universe. This is the case even if the surface is part of the geometry in another universe.

Detector file (df):

 FILE : file name where the scored points are written FRAC : fraction of recorded scores and ascii/binary option (positive value = ascii, negative value = binary)

Notes:

• This option can be used to write the scored points in a file.
• When used with the surface current detector this option can provide surface source distributions for other calculations.
• The fraction parameters gives the probability that the score is written in the file and it can be used to reduce the file size in long simulations.
• Source files can be read using the sf entry of source cards.

Special types (dt):

 TYPE : special type (see below) PARAM : additional parameters

The types are:

 -1 = cumulative spectrum -2 = division by energy width -3 = division by lethargy width -4 = sum over cell or material bins -5 = importance weighting -6 = sum over number of scores 2 = multiply result with another detector defined by PARAM 3 = divide result with another detector defined by PARAM 4 = multiply response function by (local) temperature

Notes:

• Types -1, -2 and -3 are used with energy binning.
• Type -4 can be used to calculate sum over multiple cell or material bins defined using the dc and dm options. By default separate bins are used for each entry.
• Type 3 can be used to calculate flux-weighted averages (microscopic and macroscopic cross sections, etc.).
• When the results are multiplied or divided by another detector, the number of bins must be compatible (single value or matching number of bins).

History collection option (dhis):

 OPT : option to collect histories (0 = no, 1 = yes)

Notes:

• When this option is set, the batch-wise results are printed in the history output file, [input]_stats.m.
• Note to developers: statistical tests should be documented

Detector flagging (dfl):

 FLAG : flag number (between 1 and 64) OPT : flagging option (0 = reset if scored, 1 = set if scored, -2/2 score if set -3/3 score if not set)

Notes:

• Detector flagging allows limiting detector scores to histories which have already contributed to another score.
• The first two options reset or set the flag if the detector is scored, respectively. The remaining options test if the flag is set and score the detector accordingly. Positive values apply OR-type logic (detector is scored if any of the associated flags is set/unset) and negative values AND-type logic (detector is scored if all the associated flags are set/unset).

Activation detector (da):

 MAT : activated material FLX : flux applied to activation

Notes:

• Activation detector allows performing activation calculation for materials that are not part of the geometry. The flux spectrum applied to neutron irradiation is taken from the detector scores. The absolute flux level can be set using the FLX parameter. If this parameter is set to -1, also the flux magnitude is taken from the detector scores.
• Requires neutron transport simulation and burnup mode. The material provided with the entry must be burnable, and cannot part of the actual geometry. Volume of the material must be defined using the dv parameter.
• Since the activated material is not part of the physical geometry, this option should be applied only to small samples and other activation calculations in which the isotopic changes do not significantly affect the neutronics.

Functional Expansion Tally detector (dfet):

 TYPE : functional expansion type PARAMS : other options, specific to each functional expansion type TYPE
Geometry PARAMS TYPE Description Functional Series Indexing
Cartesian XMIN XMAX XORDER YMIN YMAX YORDER ZMIN ZMAX ZORDER 1 Legendre only $\psi(\xi)_n = P_i(\xi_x) P_j(\xi_y) P_k(\xi_z)$ $n = k + J * \left( i * I + j\right)$
Cylindrical RMAX RORDER HMIN HMAX HORDER HORIENTATION 2 .. .. ..

Notes:

• "-1" can be supplied as an ORDER PARAM to use the built-in default values
• It is not recommended to configure a single FET detector to span multiple different material regions—use individual detectors for each region instead
• Specifics of this implementation:
• The FETs are based on nonseparable expansions, i.e. fully-convolved cross terms are included
• For example, the Legendre-based Cartesian FET uses $\psi(\xi)_n = P_i(\xi_x) P_j(\xi_y) P_k(\xi_z)$ with $n$ as a linear indexer of $\{i,j,k\}$
• Due to the properties of orthogonality, these cross terms can be neglected in post-analyses if only separable terms are desired
• A generalization of the Euler formulas for any orthogonal functional series is used
• The generated FET coefficients $a_n$ already have all contributions from the orthonormalization constant pre-included, i.e. $c_n$ from $\frac{1}{c_n} = \lVert \psi_n \rVert^2 = \int_\Gamma \psi_n^2 \omega_n$
• Thus, an FET can be simply reconstructed/sampled from the standard functional series as: $F(\xi) = \sum a_n \psi_n(\xi) \omega_n(\xi)$
• From version 2.2.0 and on, FET-based detectors follow the standard normalization set in the calculation. The volume standards for detectors are set as default value for FET-based detectors, meaning detectors are not divided by the physical volume (allowing the use of volume detector dv).
• In version 2.2.0, the relative error evaluation associated with FET-based detectors has been revisited.

Detector pulse-height energy broadening (dphb):

 PHB : user-defined (Gaussian) energy broadening for pulse-height detector function name

Notes:

• User-defined Gaussian energy broadening functions for pulse height detector are defined using the phb card.

Detector spatial integration domain and binning based on a generic data mesh (dmesh):

 MESH : name of the datamesh to use for defining the spatial integration domain and binning for the detector scores

Notes:

• Output mesh index will be flattened (one dimensional).

### div (divisor definition)

div MAT [ sep LVL ]
[ subx NX XMIN XMAX ] equal volume [ subx -NX X1 X2 ... XN+1 ] manually spaced limits
[ suby NY YMIN YMAX ] equal volume [ suby -NY Y1 Y2 ... YN+1 ] manually spaced limits
[ subz NZ ZMIN ZMAX ] equal volume [ subz -NZ Z1 Z2 ... ZN+1 ] manually spaced limits
[ subr NR RMIN RMAX ] equal volume [ subr -NR R1 R2 ... RN+1 ] manually spaced limits
[ subs NS S0 ]       equal volume [ subs -NS S1 S2 ... SN+1 ] manually spaced limits
[ lims FLAG ]


Divides a material into a number of sub-zones. Input values:

 MAT : name of the divided material LVL : geometry level at which the cell-wise division takes place (0 = no division, 1 = last level, 2 = 2nd last level, etc.) NX : number of x-zones XMIN : minimum x-coordinate (cm) XMAX : maximum x-coordinate (cm) Xn : x-coordinate boundaries (cm) NY : number of y-zones YMIN : minimum y-coordinate (cm) YMAX : maximum y-coordinate (cm) Yn : y-coordinate boundaries (cm) NZ : number of z-zones ZMIN : minimum z-coordinate (cm) ZMAX : maximum z-coordinate (cm) Zn : z-coordinate boundaries (cm) NR : number of radial zones RMIN : minimum radial coordinate (cm) RMAX : maximum radial coordinate (cm) Rn : radial coordinate boundaries (cm) NS : number of angular sectors S0 : zero position of angular division (degrees) Sn : angular-sector boundaries (degrees) FLAG : flag for mapping regions outside (material) limits to divide material - on (1/yes) or off (0/no)

Notes:

• The automated divisor feature can be used to sub-divide burnable materials into depletion zones, but the use is not limited to burnup mode.
• The spatial sub-division is based on either Cartesian or cylindrical mesh.
• Volumes of the divided materials must be set manually (see detailed description on the definition of material volumes).
• Using automated instead of manual depletion zone division saves memory, which may become significant in very large burnup calculation problems (see detailed description on memory usage).
• For more information see detailed description on automated depletion zone division.
• The usage of LVL is explained on page automated depletion zone division.
• The feature of mapping regions outside limits is set by default OFF.
• The manually-spaced angular-sector boundaries Sn should cover the full/360 degrees angular space.
• If a material is not divided, all occurrences of it are treated as a single depletion zone. For example, if there are multiple fuel pins with same fuel material type, and no div card is present, all pins are depleted as a single pin.

### dtrans (detector mesh transformation)

See transformations.

### ene (energy grid definition)

ene NAME 1 E0 E1 ...

ene NAME 2 N Emin Emax

ene NAME 3 N Emin Emax

ene NAME 4 GRID


Defines an energy grid structure. Input values:

 NAME : energy grid name Ei : bin boundaries (type 1) N : number of equi-width bins (types 2 and 3) Emin : minimum energy (types 2 and 3) Emax : maximum energy (types 2 and 3) GRID : name of the pre-defined grid (type 4)

Notes:

### ftrans (fill transformation)

See transformations.

### fun (function definition)

fun NAME TYPE [ ... ]


Defines a function that can be used with detector responses. Input values:

 NAME : function name TYPE : function type (currently only supported type is 1 = point-wise tabular data)

The syntax for type 1 is:

fun NAME 1 INTT X1 F1 X2 F2 ...


where:

 INTT : is the interpolation type (1 = histogram, 2 = lin-lin, 3 = lin-log, 4 = log-lin, 5 = log-log) Xi, Fi : are the tabulated variable-value pairs

Notes:

• The defined function is linked to detector response using response number -100 (syntax: dr -100 NAME).
• The defined function currently is only supported as a flux-based function, aka, flux multiplier.

### hisv (history variation matrix definition)

hisv [ BU1 NBR1 BR1,1 BR1,2 ... BR1,NBR1 ]
[ BU2 NBR2 BR2,1 BR2,2 ... BR2,NBR2 ]
...


Defines the history variation matrix for the automated burnup sequence. Input values:

 BUn : burnup steps at which the branches are invoked NBRn : number branches in the n-th burnup step BRn,i : name of the i-th branch in the n-th burnup step

Notes:

• The automated burnup sequence defined by the hisv card follows the same principle as the coef input card.
• The hisv card performs multiple depletions within a single depletion calculation following the historical variation sequence, performing a restart at each of the listed burnup points, where it applies the variations defined in the listed branches for the given burnup point.
• Positive values in the burnup vector are interpreted as (MWd/kgU), negative values are interpreted as time steps in days.
• The hisv card is used together with the branch card.

### ifc (interface file)

ifc FILE [setinmat NMAT MAT1 MAT2 ... MATNMAT ]
[setoutmat NMAT MAT1 MAT2 ... MATNMAT ]


Links a multi-physics interface file to be used with the current input. Input values:

 FILE : path to the multi-physics interface file

The optional cards are explained below.

setinmat adds the possibility to link multiple input materials to the same interface, i.e. the same interface gives temperatures and densities (density factors) for multiple materials.

setoutmat adds the possibility to link multiple output materials to the same interface, i.e. the same interface gives temperatures and densities (density factors) for multiple materials.

 NMAT : number of materials to link to the interface MATi : name of the ith material linked to the interface

Notes:

• If multiple materials are linked to the interface using the setinmat/setoutmat option, the densities in the interface file must be given as density factors, i.e. relative to the material card density (values between 0 and 1).
• If the interface is not updated, setinmat/setoutmat options are not eligible. In the case of regular mesh-based, additionally to not updating the interface: a) the input materials cannot be specified using setinmat if power is tallied in pin-type objects; b) the output materials cannot be specified using setoutmat if power is not tallied on the same mesh.
• Option setinmat was setmat in versions before 2.1.32.

### include (read another input file)

include FILE


Reads another input file. Input values:

 FILE : name of the input file

Notes:

• The include card can be used to simplify the structure of complicated inputs.
• The input parser starts reading and processing the new file from the point where the input card is placed. Processing of the original file continues after the new file is completed.
• The included file must contain complete input cards and options, it cannot be used to read the values of another card.

### lat (regular lattice definition)

See also Section 3.6 of Serpent 1 User Manual.

lat UNI TYPE X0 Y0 NX NY PITCH UNI1 UNI2 ...


Defines a finite two-dimensional lattice in xy-plane with square or X- or Y-type hexagonal elements. The lattice is infinite in z-direction. Input values:

 UNI : universe name of the lattice TYPE : lattice type X0 : x-coordinate of the lattice origin (origin is in the center of the lattice). Y0 : y-coordinate of the lattice origin (origin is in the center of the lattice). NX : number of lattice elements in x-direction NY : number of lattice elements in y-direction PITCH : lattice pitch UNIn : list of universes filling the lattice positions

Possible lattice types are:

Type Description
1 Square lattice
2 X-type hexagonal lattice
3 Y-type hexagonal lattice
14 X-type triangular lattice
Lattice type 1 indexing example for NX = NY = 3.
Lattice type 2 indexing example for NX = NY = 3.
Lattice type 3 indexing example for NX = NY = 3.

Notes:

• Number of universes in list of universes must be NX × NY.
• For square lattices the x coordinate increases from left to right and the y coordinate increases from top to bottom, so the first NX values in the list of universes create the bottommost (minimum y) row from minimum x to maximum x and the last NX values in the list of universes create the topmost (maximum y) values. Example of the indexing is provided in the attached figure.
• The line breaks usually present in the list of universes are only used to help visualizing the universe order for the user. Serpent ignores them when processing the list of universes.
• The input of X- and Y-type hexagonal lattices is similar to each other, only the directions of the x- and y-axis change. The axis directions can be checked by using the geometry plotter. Examples of the indexing are provided in the attached figures.
lat UNI TYPE X0 Y0 PITCH UNI1


Defines an infinite two-dimensional lattice in xy-plane with infinitely repeating square or X- or Y-type hexagonal element. The lattice is infinite in z-direction.

 UNI : universe name of the lattice TYPE : lattice type X0 : x-coordinate of the lattice origin Y0 : y-coordinate of the lattice origin PITCH : lattice pitch UNI1 : universe name of the universe filling all lattice positions

Possible lattice types are:

Type Description
6 Square lattice
7 Y-type hexagonal lattice
8 X-type hexagonal lattice

Notes:

• The order of X- and Y-type hexagonal lattice type numbers is reversed when compared with finite hexagonal lattices.
lat UNI TYPE X0 Y0 NR NS,1 RADIUS1 THETA1 UNI1,1 UNI2,1 ... NS,2 RADIUS2 THETA2 UNI1,2 UNI2,2 ... ...


Defines a finite two-dimensional circular cluster array lattice in xy-plane. The lattice is infinite in z-direction.

 UNI : universe name of the lattice TYPE : lattice type X0 : x-coordinate of the lattice origin Y0 : y-coordinate of the lattice origin NR : number of rings in the array NS,R : number of sectors in Rth ring RADIUSR : central radius of Rth ring THETAR : angle of rotation of Rth ring in degrees UNIN,R : list of universes filling the sector positions in Rth ring

Possible lattice type is:

Type Description
4 Circular cluster array

Notes:

• The circular cluster array can be used to define fuel assemblies used for example in AGR, CANDU, MAGNOX and RBMK reactors. It can also be used to define fuel rod layout used for example in TRIGA reactors.
lat UNI TYPE X0 Y0 NL Z1 UNI1 Z2 UNI2 ...


Defines a finite one-dimensional vertical stack in z-direction. The stack is infinite in xy-plane.

 UNI : universe name of the lattice TYPE : lattice type X0 : x-coordinate of the lattice origin Y0 : y-coordinate of the lattice origin NL : number of lattice elements in z-direction (number of axial layers) Zn : z-coordinate of the nth lattice element (lower boundary of the axial layer) UNIn : universe name filling the nth lattice position

Possible lattice type is:

Type Description
9 Vertical stack

Notes:

• The z-coordinates must be given in ascending order.
• Space below the lowest z-coordinate is not defined.
• The top layer fills the entire space above the highest z-coordinate.
• The number of Zn-UNIn pairs must be NL.
lat UNI TYPE X0 Y0 Z0 NX NY NZ PITCHX PITCHY PITCHZ UNI1 UNI2 ...


Defines a finite three-dimensional lattice in xyz-space with cuboidal or X- or Y-type hexagonal prism elements.

 UNI : universe name of the lattice TYPE : lattice type X0 : x-coordinate of the lattice origin Y0 : y-coordinate of the lattice origin Z0 : z-coordinate of the lattice origin NX : number of lattice elements in x-direction NY : number of lattice elements in y-direction NZ : number of lattice elements in z-direction PITCHX : lattice pitch in x-direction PITCHY : lattice pitch in y-direction PITCHZ : lattice pitch in z-direction UNIn : list of universes filling the lattice positions

Possible lattice types are:

Type Description
11 Cuboidal lattice
12 X-type hexagonal prism lattice
13 Y-type hexagonal prism lattice

Notes:

• Number of universes in list of universes must be NX × NY × NZ.
• For hexagonal prism lattices the x- and y-direction pitches must be equal.
• The universe indexing is the similar as with lattice types 1-3. The lowermost z-level is given first, and the uppermost z-level is given last.

### ltrans (lattice transformation)

See transformations.

### mat (material definition)

See Chapter 4 of Serpent 1 User Manual.

mat NAME DENS [ tmp TEMP ]
[ tms TEMP ]
[ tft TMIN TMAX ]
[ rgb R G B ]
[ vol VOL ]
[ mass MASS ]
[ burn NR ]
[ fix ID TEMP ]
[ moder THNAME ZA ]
NUC1 FRAC1
[ NUC2 FRAC2 ]
[    ...     ]


Mandatory information:

 NAME : Name of the material DENS : Density of the material (positive for atomic, negative for mass density) or sum to calculate the density from given nuclide fractions NUCn : Identifier of nth nuclide in composition, e.g. "92235.03c" or "U-235.03c". FRACn : Fraction of nth nuclide in composition, positive values are interpreted as atomic fractions/densities, negative values as mass fractions/densities.

Optional cards:

tmp: Material temperature for Doppler-preprocessor

 TEMP : Temperature (in Kelvin) of the material for Doppler-broadening preprocessor

tms: Material temperature for on-the-fly TMS temperature treatment

 TEMP : Temperature (in Kelvin) of the material for on-the-fly TMS temperature treatment

tft: Temperature limits for material for coupled multi-physics calculations

 TMIN : Lower limit for material temperature TMAX : Upper limit for material temperature

rgb: Material color for geometry plots

 R : Value for the red channel of geometry plots (between 0 and 255) G : Value for the green channel of geometry plots (between 0 and 255) B : Value for the blue channel of geometry plots (between 0 and 255)

vol: Material volume

 VOL : Volume of the material in cm3 (3D geometry) or cross-sectional area in cm2 (2D geometry)

mass: Material mass

 MASS : Mass of the material in grams

burn: Flag material for depletion

 NR : Set to 1 in order to deplete material. The depletion zone division should be done using the div-card.

fix: Library information for decay nuclides

 LIB : Library ID (e.g. "09c") for nuclides without cross section data. TEMP : Temperature (in Kelvin) for nuclides without cross section data.

moder: Use thermal scattering data library for a nuclide. The moder entry can be used several times to define thermal scattering libraries for multiple nuclides, such as hydrogen and deuterium in heavy water.

 THNAME : Name of the thermal scattering data library defined using the therm card. ZA : Nuclide ZA of the thermal scatterer (e.g. 1001 for H-1).

Notes:

• This description is incomplete for both the descriptions and optional settings.
• See defining material volumes and set mvol regarding other ways to set the material volumes for example in burnup calculations.
• The nuclide identifier for nuclides with associated cross-sections corresponds to ZZAAA.ID and, for nuclides without associated cross-sections, e.g., decay nuclides, to ZZAAAI. The identifiers include Z, the atomic number; A, the mass number of the nuclide; I, the isomeric state (0 = ground state, 1 = metastable state); and ID, the library identifier. For nuclides without associated cross-sections, include the fix option to indicate the library and temperature of the given nuclides.

### mesh (mesh plot definition)

mesh ORI XPIX YPIX [ SYM MIN1 MAX1 MIN2 MAX2 MIN3 MAX3 ]

mesh 8 CMAP DET ORI XPIX YPIX [ SYM