Development of nodal Sn transport method in 3D hexagonal geometry

A new nodal Sn transport calculation code NSHEX has been developed to accurately estimate the 3-D transport effect of fast reactors in hexagonal-z geometry. The intra-node distribution of source is expanded into quadratic polynomials, and the neutron angular distribution of node surface fluxes and intra-node fluxes is considered by Sn quadrature. In addition, some improvements have been made on the code in order to enhance the accuracy. The accuracy of the present method was validated through numerical analyses for a commercial scale fast reactor with the comparison of Monte Carlo method.