Reactor design and safety

Core designs and safety analyses of the Super LWR and Super FR are described in Sects. 2.1 and 2.2. The single-pass core of the Super LWR adopts the fuel assembly with large water rods having a thermal insulator. The upper core structure allows for simplified refueling procedures like light water reactors (LWRs). The single-pass core of a Super FR adopts the blanket fuel assembly with mixed oxide fuel rods in the lower part. Safety characteristics at abnormal transients, accidents and anticipated transients without scram (ATWS) of the Super LWR and Super FR are described. The total loss of flow accident and loss of coolant accidents (LOCAs) are important. Transient sub-channel analysis predicts a lower fuel cladding temperature for accidents and abnormal transients than the single-channel model for the Super FR where peaking is small. Transient subchannel analysis is described in Sect. 2.3. New rod-type spacer was developed and is described in Sect. 2.4. Transmutation of long life radioactive fission products (LLFPs) is studied from the viewpoints of environmental risk and human risk. The high breeding core of the Super FR is developed with the tightly packed fuel rod fuel assembly. They are described in Sects. 2.5 and 2.6 respectively. Nuclear calculation of the fast and thermal neutron coupled core is described in Sect. 2.7. The author of this chapter except Sect. 2.4 is Yoshiaki Oka with assistance of Qingjie Liu and Sutanto. Shinichi Morooka is the author of Sect. 2.4.