Progress report of the design study on actinide recycle reactor concept; Study on the plant system

Akatsu, Minoru; Tozawa, Katsuhiro; Watanabe, Ichiro; Ichimiya, Masakazu; Hayashi, Hideyuki; Mukaibo, Ryuichi

In 1995, a design study on the mixed-oxide fuel core of the large breeder reactor was done to realize actinide (including minor actinide) 600MWe recycle reactor plant aiming at minimization of the radioactive waste products at the view point of not only to lighten the burden of the environment but also to utilize efficiently the resources, Study was carried out and R&D items were clarified as to the following items, as plant system design. (1)influences to the plant system from decay heat increase. (2)reactor structure concept due to adoption ductless fuel assembly concept. The study results are as follows. The coolant flow pass concept to core assemblies and the core support concept were studied by taking account of ductless core system and the large floating force on core assemblies due to ductless core system, the features of the concepts were clarified and the mechanical hold down (MHD) mechanism concept was adopted against the floating force. The characteristics of the connection between the upper internal structure and the core assemblies were studied for the large eccentricity of the two structures due to installation error, thermal expansion difference, inclination of core assemblies, etc. The connection that were led by MHD was guessed to be done with no large problem by special connection procedure. The reactor auxiliary cooling system capacity of 16MW a loop is sufficient to remove core decay heat to maintain the integrity of the coolant boundary structure. The heat removal characteristics under natural convection circulation coolant flow is confirmed to be superior than ducted core plant because of the lower pressure drop property of the ductless core plant. The cask car type fuel handling system was selected as referenceex-vessel fuel handling system. Because the cask car type system was able to simplify the fuel handling system by the in-line configuration of fuel handling facilities. The decay heat of ductless spent fuel assembly in sodium pot ...