Keyword:GRPCONVERT
GRPCONVERT nestrc ndstrc
This keyword allows the user to read a neutron (or other projectile) spectrum in an arbitrary number of groups (nestrc) and instruct FISPACT-II to convert it into one of the presently-allowed eleven standard structures. ndstrc must therefore be (in the release 3-00) 162 (charged particle), 709 (neutron) or one of the legacy EAF group structures; using any other value will result in an error message. The user must prepare a file containing the following data and connect it to the arb_flux input stream in the files file:
- nestrc+1 values representing the arbitrary energy boundaries (in eV) starting with the highest energy and monotonically decreasing in energy
- nestrc values representing the flux in each group
- First wall loading (MW per square metre) -- note that this can be set to 1.0 where not needed
- A test string (maximum 100 characters) identifying the spectrum
Note that each of the above groups of items should start on a new line in the file and there should be no blank lines separating them, but otherwise the format of each group is free -- for example the nestrc flux values can all be on one line or split over multiple lines. The output file will contain information about the conversion: what fraction of the input groups are included in each output group and details of the input and the output spectra. The converted spectrum is written to the file connected to the fluxes stream named in the files file; this contains the standard information for a fluxes file:
- ndstrc values representing the flux in each group of the new group structure
- First wall loading (MW per square metre) -- note that this can be 1.0 where not needed
- A test string (maximum 100 characters) identifying the spectrum
Note that although the text string can contain 100 characters only the first 22 will be used as the spectrum identifier, so these should provide an unambiguous description. The conversion is done on an equal flux per unit lethargy basis; e.g. if one of the input groups is split into two or more groups in the converted spectrum then the fraction of particles in each output group is determined by the ratio of each lethargy interval of the output structure to the total lethargy interval of the input structure.
There is also a restriction on the number of arbitrary energy groups; this must be greater than 2.
The group conversion page gives an example for this keyword, which is accompanied by a getting_started example within the standard FISPACT-II Release 3-00 distribution.
