A multi-region boundary element method for multigroup neutron diffusion calculations

For the analysis of a two-dimensional nuclear system consisting of a number of homogeneous regions (termed cells), first the cell matrices which depen d solely on the material composition and geometrical dimension of the cell (hence on the cell type) are constructed using a boundary element formulati on based on the multigroup boundary integral equation. For a particular nuc lear system, the cell matrices are utilized in the assembly of the global s ystem matrix in block-banded form using the newly introduced concept of vir tual side. For criticality calculations, the classical fission source itera tion is employed and linear system solutions are by the block Gaussian-elim ination algorithm. The numerical applications show the validity of the prop osed formulation both through comparison with analytical solutions and asse ssment of benchmark problem results against alternative methods. (C) 2001 E lsevier Science Ltd. All rights reserved.