Input syntax manual
This page will contain the whole input syntax of Serpent 2
This is a reference to one article 
This is another reference to the same article 
mat (material definition)
surf (surface definition)
cell (cell definition)
det (detector definition)
set gcut <ng>
Sets generation cut-off for neutrons. Input values:
|<ng>||number of simulated generations before cut-off|
The cut-off can be used in neutron external source simulations, to limit the length of fission chains.
- Applicable only to neutron external source simulation (invoked using (set nps)
- Generation or time cut-off (set tcut) is needed for external source simulations in super-critical systems
set nps <ppb> [ <btch> ]
Sets parameters for simulated particle population in external source mode. Input values:
|<ppb>||number of particles per batch|
|<btch>||number of batches|
The simulation is for a number batches using the given batch size.
- Using the nps card sets the mode to external source simulation. Criticality source simulation for neutrons is invoked using set pop.
- Running an external source simulation requires a source, defined by the src card. Source definition also sets the transported particle type.
- Neutron external source simulations are limited to sub-critical systems, unless time cut-off (set tcut) or generation cut-off (set gcut) is invoked.
- Neutron external source simulations in multiplying systems may require adjusting the neutron buffer (set nbuf).
set pop <npg> <ngen> <nskip> [ <keff0> <btch> ]
Sets parameters for simulated neutron population in criticality source mode. Input values:
|<npg>||number of neutrons per generation|
|<ncyc>||number of active generations|
|<nskip>||number of inactive generations|
|<keff0>||initial guess for k-eff|
The simulation is first run for a number of inactive generations to allow the fission source to converge. This is followed by a number of active generations, during which the results are collected. The statistics are divided in batches, and by default each generation forms its own batch.
- Using the pop card sets the mode to criticality source simulation. External source simulation is invoked using set nps.
- Convergence of fission source can be monitored using Shannon entropy (input parameters set his and set entr).
- See detailed description on the statistical effects of batching.