Spatial heterogeneity effect of CANDU cells in core global parameters

This paper shows the influence of spatial heterogeneity correction in values of CANDU core global parameters (such as power distributions, reactivity, maximum power per bundle or channel). Effective cross sections are obtained with WIMS code and after that they are corrected by the use of a more realistic flux distribution in the cell. For this purpose we solve integral transport equation in three-dimensional mixed geometry (rectangular, X-Y-Z, and cylindrical, R-θ-Z) by the first collision probability method. For increasing the rapidity of the numerical algorithms the developed 3D transport code, PI-JXYZ, is based on the block method which is a combination of the interface current method and conventional collision probability method. We show the influence of the correction for some case of CANDU core configurations (core without reactivity devices inserted, core in references case, adjuster withdrawn out of the core, zone controllers empty, zone controllers full). In addition some remarks about multigroup effect and spectral heterogeneity effect in the results are presented. (authors)