CANDU cells heterogeneity effect in generating effective cross sections

The use of WIMS code to generate effective cross sections is not very appropriate for CANDU type cells for the reason of control-commands and fuel boundless' perpendicularity. For correcting WIMS cross sections we developed a three dimensional collision probability code, PIJXYZ. This code allows a mixed geometry (rectangular-cylindrical) to describe CANDU cells. The influence of corrected and uncorrected cross-sections in global parameters (power and flux distributions, reactivities, maximum bundle and channel power) is presented. These parameters are obtained with DD3ICN (3 D diffusion code) developed in our institute. (Author)