SP-2000: Program for calculating fine group neutron spectrum in multi-region cell and effective broad group constants

The program SP-2000 is one of the 2000-series programs developed for utilizing AGLI fine group cross section library. This program calculates fine group neutron spectrum (about 2000 energy groups) in a multi-region cell by means of the collision probability method. The program also calculates homogenized broad group constants using the calculated neutron spectrum as a weighting function. The program is written in FACOM-230/60 FORTRAN in order to take a part of DOYC computer software system developed for fast reactor analysis. Computing time necessary for solving practical problems is shown to be reasonable and the results of neutron spectrum and heterogeneity effect on criticality obtained by the program are shown to well represent the measured ones. (auth.)