Patent Number: 
Section: claims

1. A modular lower moving system for nuclear fuel handling, the modular lower moving system comprising:a lower reactor vessel assembly installed below a reactor vessel located in a reactor area, detachable from the reactor vessel, and comprising nuclear fuel loaded therein;a carrier having a space allowing the lower reactor vessel assembly detached from the reactor vessel to be accommodated therein;a rail installed at a bottom of a transfer canal and extended from the reactor area to a fuel handling area;a transfer cart horizontally movable along the rail;a lifting device installed on the transfer cart, horizontally movable along the rail along with the transfer cart, and movable upward or downward with respect to the transfer cart; anda drive device configured to supply power to the transfer cart and the lifting device,wherein the carrier is assembled on the lifting device to be lifted or lowered via the lifting device, the lower reactor vessel assembly detached from the reactor vessel is accommodated in the carrier, and the carrier is horizontally movable along the rail via the transfer cart,wherein the drive device comprises:a drive unit installed in the fuel handling area and configured to provide power;a first extension stem connected to the drive unit and extending downward of the drive unit;a first gear shaft connected to the first extension stem and connected to the transfer cart;a second extension stem connected to the drive unit and extending downward of the drive unit; anda second gear shaft connected to the second extension stem and connected to the lifting device,wherein power of the drive unit is transmitted to the transfer cart via the first extension stem and the first gear shaft, and is transmitted to the lifting device via the second extension stem and the second gear shaft. 2. The modular lower moving system of claim 1, wherein the first gear shaft is connected to the transfer cart via a first gear configured to convert rotational movement of the first gear shaft into horizontal movement of the transfer cart, andthe second gear shaft is connected to the lifting device via a second gear configured to convert rotational movement of the second gear shaft into vertical movement of the lifting device. 3. The modular lower moving system of claim 1, wherein the carrier is provided, at an inner wall thereof, with insertion keys protruding inward of the carrier, andthe lower reactor vessel assembly is provided, at an outer wall thereof, with keyways protruding outside the lower reactor vessel assembly and each having a groove allowing the insertion key to be inserted thereinto. 4. The modular lower moving system of claim 3, wherein the insertion keys are installed along the inner wall of the carrier with constant intervals of 90° therebetween, and the keyways are installed along the outer wall of the lower reactor vessel assembly with constant intervals of 90° therebetween. 5. The modular lower moving system of claim 1, wherein a fixed guide pin is installed at a side surface of the reactor area and another fixed guide pin is installed at a side surface of the fuel handling area, the fixed guide pins having a rod shape and extending upward from a surface on which the rail is installed, anda rotary guide pin is arranged, the rotary guide pin extending upward from the surface, spaced apart from the fixed guide pin by a constant distance, and having a rod shape,wherein the rotary guide pin is rotatable about a first virtual axis extending in a direction parallel to a direction in which the rotary guide pin extends upward. 6. The modular lower moving system of claim 5, wherein the drive device comprises:a rotary gear connected to a side surface of the first gear shaft,wherein a center of the rotary gear is positioned on the first virtual axis, and the rotary guide pin is eccentrically installed at the rotary gear, allowing the rotary guide pin to be rotatable via the rotary gear. 7. The modular lower moving system of claim 6, further comprising:a hole plug installed on at least one of the carrier, the lifting device, and the transfer cart, and having a groove shape allowing the fixed guide pin or the rotary guide pin to be inserted thereinto.