Input syntax manual

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Revision as of 18:37, 17 November 2015 by Jaakko Leppänen (Talk | contribs) (set pop)

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This page will contain the whole input syntax of Serpent 2

This is a reference to one article [1]

This is another reference to the same article [1]

Input cards

mat (material definition)

surf (surface definition)

cell (cell definition)

det (detector definition)


Input options

set pop

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
<btch> batching interval

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.

set nps

set nps <npg> [<keff0> <>] 

Setting the neutron population.

<npg> neutrons_per_generation
<nc> neutrons

set delnu

set roulette


  1. ^ Leppänen, J. "Development of a new Monte Carlo reactor physics code." D.Sc. Thesis, Helsinki University of Technology, 2007. (VTT Publications 640)