Patent ID: 7693250

Claim:
A fast reactor controlled with a reflector comprising: a reactor vessel accommodating therein a coolant; a reactor core disposed in the reactor vessel and immersed in the coolant; and a reflector that vertically moves for adjusting leakage of neutrons generated from the reactor core to control a reactivity of the reactor core, the reflector including a neutron reflecting part disposed on an outside of the reactor core in a vertically movable manner, and a cavity part positioned above the neutron reflecting part, the cavity part having a neutron reflecting ability lower than that of the coolant, said cavity part includes a frame, and a plurality of sealable containers of a box shape that are held in the frame; wherein the neutron reflecting part is formed of a plurality of metal plates that are stacked on each other, each of the metal plates has a plurality of coolant channels through which the coolant flows, and the number of the coolant channels in each of the metal plates per unit area increases from a side of the reactor vessel to a corresponding side of the reactor core.