Exponential function expansion method using partial current moments coupling in hexagonal geometry

A new nodal method for solving neutron diffusion equations in hexagonal geometry is described in this paper. The neutron flux distributions within a node are expanded in a series of exponential functions and second-order orthogonal polynomials for each group. Nodes are coupled each other with both the zero-and first-order partial current moments simultaneously. The response matrix technique is used for the iterative solution of the nodal diffusion equations, which gives a fast-running scheme for the diffusion calculations. Based on the proposed model, the code TLCORE has been developed. This method has been tested against two-dimensional VVER benchmark problems. The numerical results show that the core multiplication factor and nodal powers are predicted accurately. (authors)