Patent ID: 8331523

Claim:
A nuclear reactor in which a coolant is contained comprising: a core composed of nuclear fuel, the coolant moving upwardly from the core by an operation thereof; an annular steam generator annularly arranged around an axis of the core in an upper side thereof into which the upwardly moving coolant flows and adapted to transfer heat in the coolant into water therein to generate a steam; a passage structure that defines a coolant passage for the coolant to an outside of the core, the heat-transferred coolant in the annular steam generator flowing downwardly in the coolant passage so as to flow into the core, thereby moving upwardly; a reactor vessel arranged to surround the coolant passage so as to contain the core, the annular steam generator and the coolant passage therein; a core barrel surrounding an outer periphery of the core; an annular reflector surrounding an outer periphery of the core barrel; a neutron shield arranged in the coolant passage and surrounding the outer periphery of the core; an electromagnetic pump annularly arranged in the coolant passage at a portion between outer and inner partition walls and above the neutron shield; and a guard vessel surrounding an outer periphery of the reactor vessel, wherein the pump is annularly displaced inside of the annular steam generator and the annular steam generator is arranged to surround an outer periphery of an upper portion of the pump so that at least lower portion of the steam generator is overlapped to the upper portion of the pump in an axial direction thereof, and wherein the core barrel, the annular reflector, the neutron shield and the solenoid pump are contained in the reactor vessel.