In-core charge assembly

Purpose: To flatten power output distributions for the reactor core using fuels containing Gd as a burnable poison, and at the same time, solve the problems of reactivity penalty at the end of cycle life, storing of used incore charge assembly, etc. Constitution: The incore charge assembly is equipped with multiple number of reaction control components and plugs arranged in parallel. The reaction control components are of zircalloy long-sized solied round bars. Short and round solid stainless-steel bars are used for the plugs. The reaction control components can be made by any materials which hardly absorb neutrons. They can be made by filling up the hollow section of hollow zircalloy bar or tube (with both ends blocked) with such materials as zirconia or alumina which hardly absorbs neutron. (Kawakami, Y.)