sp-fispact2001 - ENEA AFS Cell

SP-FISPACT, together with these cross-sections, stores the „pseudo cross-sections‟ in this file
and, thus, the different utilization of SP-FISPACT with respect to FISPACT concerns only
the way the file COLLAPX is prepared by the input file „collapx.i‟.
See APPENDIX A for the detailed modifications to the subroutines of FISPACT2001 and
APPENDIX B for the definition of the „pseudo cross-section‟.
3. Calculations with SP-FISPACT2001
The procedure for carrying out the calculations is shown in the following page and is
explained here step by step.
3.1 Preparation of the outputs of MCNPX
The MCNPX input file requires the following cards :
- „f4:n‟. This card calculates the volumetric neutron flux. Choose one of the energy group
structures of FISPACT2001 (XMAS, VITAMIN-J, TRIPOLI, see [4]) 2 and, using the card
„e4‟, define the energy bins accordingly.
- „histp‟. This card creates the file „histp‟ (it can be quite a lengthy file). This file is postprocessed
by the code 3 HTAPE3X [1] for calculation of residual nuclei per source proton
after interactions >20MeV.
Two output files are needed from HTAPE3X: the first providing the elastic collisions (this
output file must be called „elast‟), the second providing the residual nuclei after elastic
and inelastic collisions above 20MeV (this ouput file must be called „resid‟):
1. htape3x int=int1 outt=elast
(„int1‟ is the input file for HTAPE3X with the options IOPT=115 and KOPT=2. „elast‟ is the
output containing the elastic collisions).
Here is an example for int1:
Elastic collision
in 25 cells
115,,,,2,25,,,,/
15,20,25,30,44,46,48,52,54,56,58,60,62,64,92,94,96,98,104,
106,108,110,112,114,116
2 The group structures GAM-II and WIMS are not suitable since their highest energy values are respectively 14.9
MeV and 10 MeV.
3 This code belongs to the MCNPX package.
9