FBR type reactors

Purpose: To provide reactor core characteristics equal or superior to those of an axially heterogenous reactor core and excellent operational feasibility such as degree of freedom for fuel shuffling. Constitution: Fuel assemblies having axially uniform fissionable materials and fuel assemblies situated at the axial center thereof and having a blanket fuel region mainly composed of fertile fuel materials with a thickness smaller than the reactor core height situated at are charged in the reactor core of an FBR type reactor. A disk-like internal blanket and circular internal blankets are formed in the reactor core. This can provide the power distribution flattening effect equal or superior to that in the axially heterogenous reactor core. (Horiuchi, T.)