Patent ID: 7873137
Filing Date: 2011-01-18
Classification: G21C,Y02E

Abstract:
1. A fast reactor comprising: a plurality of fuel assemblies forming a reactor core; a reactivity control assembly including a reactor shutdown rod of a backup reactor shutdown system and sectional neutron absorbers disposed around the reactor shutdown rod to suppress initial surplus reactivity, the reactor shutdown rod and the neutron absorbers being arranged in a hexagonal barrel-shaped wrapper tube at the center of the reactor core; a core barrel surrounding outer periphery of the reactor core; a reflector surrounding the outer periphery of the core barrel and adapted to move up and down; a bulkhead surrounding outer periphery of the reflector and forming an inner wall of a coolant flow channel of primary coolant; an upper support plate supporting the core barrel and the bulkhead; an intermediate heat exchanger arranged in an annular space above the upper support plate; an electromagnetic pump arranged below the intermediate heat exchanger; a reactor vessel containing the fuel assemblies, the reactivity control assembly, the reflector, the bulkhead, the intermediate heat exchanger and the electromagnetic pump and including an upper opening; an upper plug plugging the upper opening of the reactor vessel; a reactor shutdown rod drive mechanism for causing an inner extension tube to fall and to release the reactor shutdown rod by a gripper section that includes latch fingers, at a lowermost end of an outer extension tube by turning off power supply to a holding magnet at a time of scram; and a plurality of units of neutron absorber drive mechanism, each including a dual tube drive shaft including an outer extension shaft and an inner extension shaft, the outer extension shaft being adapted to be pulled up to allow both of the inner and outer extension shafts to be inserted and pushed down after getting to a handling head section of the neutron absorber so as to grasp the neutron absorber externally by the latch fingers of the gripper section and hang up entirely with the drive shaft to individually move the neutron absorber up and down, wherein the reactor shutdown rod drive mechanism and the neutron absorber drive mechanism are integrally formed and arranged at a center of the upper plug, wherein: the reactor shutdown rod has a cylindrical profile and a head is formed at the top of the reactor shutdown rod; the reactivity control assembly includes a cylindrical guide tube arranged in the wrapper tube to surround the reactor shutdown rod and the plurality of sectional neutron absorbers arranged peripherally between the guide tube and the wrapper tube, and a cylindrical neutron absorber handling rod is arranged so as to project from a top of the reactivity control assembly when the neutron absorber moves to a lowest position, a neutron absorber handling head being formed at a top of the neutron absorber handling rod.