A new hexagonal-Z nodal S_N method in SARAX code system

Multigroup transport calculation has become the preferred choice instead of diffusion calculation in the fast reactor core analysis due to the strong anisotropy in hard spectrum. Thus, a stable and efficient transport solver is crucial for fast reactor core-analysis. In this paper, a new hexagonal-Z nodal SN method is proposed. The advantages (improvements) mainly include a more stable and efficient nodal response relation, a simple but effective method for the high-order transverse leakages treatment, the acceleration methods, and the hybrid parallelization. Based on the algorithms, a code named DNTH has been developed in the SARAX code system. Three fast reactor cores including the small-size KNK-2 core, the medium-size CEFR core and the large-size BN-600 core were calculated. The numerical results showed that good accuracy could be achieved by the method, and the efficiency was obviously improved thanks to its stable convergence performance, the acceleration methods and the parallel schemes.