Critical density iteration

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.