Two-Dimensional Calculation of Neutron Flux and Power Distribution in the Fuel Assembly of a Light Water Reactor

The application of the transmission probability method to the calculation of neutron flux distribution in a two-dimensional light water reactor assembly is described. The interior flux within a mesh is assumed to be linearly dependent on X and Y coordinates. At the mesh surfaces the linear space distribution and the P₁ approximation for the anisotropic angular distribution are considered. Simple expressions for the expansion coefficients are derived. These expressions are determined by outgoing and incoming currents and are renewed after each iteration. Based on the proposed method, the two-dimensional code TPM2D has been encoded and a series of two-dimensional assembly benchmark problems have been tested. The numerical results are in good agreement with those of S_n, surface flux transport, discrete node transport, and collision probability methods.