Fast reactor core

Purpose: To insure uniform power distribution of an axial heterogeneous reactor core having heterogeneity in an axial direction. Constitution: The fast reactor core of the present invention is constituted by reducing the axial thickness of blanket fuels in the radial circumference in the inside core range of a prior-art axial heterogeneous core and arranging all of the inside core fuel assemblies having these blanket fuels thus reduced in thickness such that they will come in contact with outer core fuel assemblies, thereby providing uniform radial power distribution and decreasing the number of kinds of flow rates of a coolant flowing to respective assemblies or the removal of heat generated from the fuel. Consequently, the auxiliary structure of the core can be simplified and costs can be reduced. (Takahashi, M.)