Critical density iteration

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Input

set iter nuc CYCLES KEFF NZAI ZAI1 ZAI2 ... ZAINZAI [ NMAT MAT1 MAT2 ... MAXNMAT ]
CYCLES  : number of additional inactive cycles to run for the convergence of the iteration
KEFF  : target k-eff for the iteration
NZAI  : number of different nuclides (ZAI) included in the iteration
ZAIi  : the ZAI (e.g. 50100 for boron 10 ground state) of the nuclide to be included in the iteration
NMAT  : number of different materials included in the iteration (optional parameter)
MATi  : the name of the material to be included in the iteration

Notes:

  • If a list of materials is not given, all materials that contain the included nuclides are included in the iteration.
  • The initial concentration of the nuclides to be iterated should be larger than zero.
  • The critical concentration iteration currently only works for nuclides that have a reactivity effect mainly through neutron absorption. Specifically, critical concentrations of fissile, moderating or reflecting nuclides cannot be iterated using this card.

Output

An output variable ITER_NUC_FACTOR is included in the main [INPUT]_res.m results file. The output variable gives the mean multiplicative scaling factor applied to atomic density of the iterated nuclides to achieve a critical system.

If the batch history recording is set on (see set his) the [INPUT]_his[STEP].m history output file will contain batch-wise estimates for the scaling factor, which can be used to ensure the convergence of the scaling factor during the inactive cycles.

Operation

Serpent will first execute the inactive cycles