Abstract: A classical semi-analytical nodal method for neutron diffusion equation with second order neutron flux expansion in radial pin by pin level and 4th order expansion for axial neutron flux is used. A full core coarse mesh finite difference (CMFD) acceleration is adopted in order to achieve good calculation accuracy and efficiency. With IAEA 2D/3D benchmark problem and self-define 3D pin by pin reference problem numerical calculation, it is demonstrated that the proposed methodology achieve anticipated accuracy and with very good CMFD acceleration.

Key words: neutron diffusion, pin by pin, semi-analytic nodal method, coarse mesh finite difference