First-collisions probabilities calculation of strong absorbers burnup

A method for calculating, using a matrix neutron first-collisions probabilities which is reconstructed at each step, the burnup of cells and fuel assemblies is presented. A method for reconstruction and correction of the first-collisions probabilities using average chords to the first collision of a neutron, which are calculated using the geometric module for reconstructing the stochastic trajectories of neutrons, is described. The results of a calculation of the multiplication coefficient of elementary cells with different material composition relative to the reference cell are presented. Computational results are presented for the burnup of a VVER fuel-assembly fragment with a consumable absorber are presented.