Development of a High-to-Low informing scheme for core neutronics calculations based on NEAMS tools

This study introduces a non-linear High-to-Low (Hi2Lo) calculation scheme based on the iteration between the local fully heterogeneous transport lattice calculation and the global nodal diffusion core calculation. This Hi2Lo method is developed to minimize the inaccuracy and inconsistency of the local lattice calculation by feeding actual core environment into the lattice boundary condition (BC) reconstruction process. PROTEUS-MOC (MOCEX) and PROTEUS-NODAL (NODAL) are selected as the transport lattice solver and the full core diffusion solver in this study, respectively. First, this work presents the implementation of the fixed incoming angular flux BC and the fixed k calculation to MOCEX. Next, the Hi2Lo calculation is tested on the two-dimensional (2D) C5G7 benchmark problem. Two types of BC formulation method are tested, namely the inter-assembly angular flux (IAAF) method and IAAF isotropic-flux method. The eigenvalue and the relative pin power distribution of the two BC methods obtained using the two formulations are compared to the reference full core transport result, which shows that the Hi2Lo approach using both formulations can improve the accuracy of the off-line method and produce a satisfactory result. (authors)