Patent Number: 
Section: claims

1. A nuclear reactor comprising:a pressure vessel;a reactor core enclosed in the pressure vessel and comprising an array of fuel units;a plurality of regulating control rods located inside the pressure vessel;a regulating control rod drive module comprising a plurality of regulating control rod drive mechanisms enclosed in the pressure vessel;each regulating control rod drive mechanism connected to a corresponding one of the plurality of regulating control rods and configured to move the corresponding regulating control rod relative to the array of fuel units along a longitudinal axis of the corresponding regulating control rod for regulating nuclear reaction at the reactor core during a normal operation of the nuclear reactor;a plurality of shutdown control rods located inside the pressure vessel;a shutdown control rod drive module comprising a plurality of shutdown control rod drive mechanisms enclosed in the pressure vessel; andeach shutdown control rod drive mechanism connected to a corresponding one of the plurality of shutdown control rods and configured to move the corresponding shutdown control rod relative to the array of fuel units parallel to the longitudinal axis for shutting down the nuclear reactor;wherein the reactor core, the regulating control rod drive module and the shutdown control rod drive module are enclosed in the pressure vessel and arranged along the longitudinal axis such that the reactor core is interposed between the regulating control rod drive module and the shutdown control rod drive module,wherein, the regulating and shutdown control rod drive mechanisms are alternately arranged such that, when viewed along the longitudinal axis, a first one of the regulating control rod drive mechanisms is generally surrounded by multiple ones of the shutdown control rod drive mechanisms and further such that, when viewed along the longitudinal axis, each of the multiple shutdown control rod drive mechanisms overlaps with the first regulating control rod drive mechanism,wherein the nuclear reactor is an integral type reactor in which steam generators, a pressurizer, and a reactor coolant pump are provided inside the pressure vessel,wherein when viewed along the longitudinal axis, the steam generators do not overlap with the regulating control rod drive module and the shutdown control rod drive module. 2. The nuclear reactor of claim 1, wherein the regulating control rod drive module is provided above the reactor core, andwherein the shutdown control rod drive module is provided below the reactor core. 3. The nuclear reactor of claim 1, wherein at least one of the plurality of shutdown control rods comprises a lower portion of burnable poison rod. 4. The nuclear reactor of claim 1, wherein the regulating control rod drive module is provided below the reactor core, andwherein the shutdown control rod drive module is provided above the reactor core.