Verification of Control Rod Assembly Homogenization for LMFBR With a New Lattice Physics Code GALAXY-H

A new FBR lattice physics code GALAXY-H has been developed by Mitsubishi Heavy Industries, Ltd. (MHI). GALAXY-H is a hexagonal version of GALAXY, which is a two dimensional transport calculation code for PWR assembly. GALAXY-H generates assembly nuclear constants used in the FBR core calculation code. The methodology of flux calculation for GALAXY-H is based on the method of characteristics (MOC) as well as GALAXY. The fuel assemblies of Japanese demonstrated and commercial FBRs are intended to contain the inner duct called FAIDUS where molten fuel is removed to prevent re-critical at severe accident. One of the objectives for developing GALAXY-H is to treat the inner duct and wrapper tube configurations exactly. In this paper, the method generating nuclear constants of control rod assembly is developed with multi-assembly model to exclude the super-cell model that has been used in FBR design so far. Besides, GALAXY-H employs the SPH method for reduction of homogenization error, which is popular method in LWR design. From this, the advanced nuclear constants calculation method for FBR control rod assembly is developed and the basic applicability of FBR nuclear design by using GALAXY-H is confirmed.