Development of a new parallel SN code for neutron-photon transport calculation in 3-D cylindrical geometry

A new three-dimensional parallel discrete ordinate transport code named Hydra has been developed. Hydra applies the Koch-Baker-Alcouffe parallel sweeping algorithm to obtain high parallel efficiency on O(102) processors both for the Cartesian and Cylindrical coordinate. The effects of different octant sweeping order on the PCE (Parallel Computational Efficiency) have been analyzed. In order to reduce the memory required for storing angular-cell-edges flux, a new octant sweeping order has been proposed for the Cylindrical coordinate system. The weighted diamond difference, weighted diamond difference with zero-flux fix-up and theta-weighted diamond difference are involved in Hydra. The anisotropic face source and volume source are described by means of discrete ordinate and spherical harmonics respectively. Several benchmarks have been calculated, where the effective multiplication factor, flux distribution and energy spectrum are verified and compared with the reference solutions from TORT. Moreover, other useful features such as the parallel first-collision source method to eliminate the ray effect, and the energy dependent quadrature set option, etc. are also included in Hydra to make the code more practical in engineering.