Reactor core of fast breeder reactor, components of same, and regulating

Abstract

A fuel containment containing nuclear fuel rods of a fuel assembly which will be loaded into a reactor core of a fast breeder reactor is formed narrow in width at middle portion of vertical direction and long in length of vertical direction. And as being used in the reactor core, the middle portion of vertical direction of the fuel containment, wherein both of heat generation and swelling are larger than that of other portion, expands more than other portion, but undesirable contact with adjacent fuel assemblies can be avoided as the middle portion is previously formed narrow. Moreover, the other portions, wherein expansion of the fuel containment and undesirable contact with adjacent fuel assemblies are barely caused, are formed previously wide in width by enlarging the coolant flow path of the fuel containment, whereby pressure drop of coolant of coolant used in the reactor core can be reduced.