Patent Number: 056446071
Section: claims

1. An automatic refueling apparatus for automatically transferring fuel assemblies between a fuel pool and a reactor core in a nuclear power plant, having a traveling carriage moving on an X-Y axis in a horizontal plane between the reactor core and the fuel pool in said nuclear power plant, a fuel assembly grappling apparatus provided at said traveling carriage and moved in a Z axis direction perpendicular to said X-Y axis horizontal plane, a rotation machine provided at said traveling carriage to rotate said fuel assembly grappling apparatus around said Z axis in a .theta. direction, and driving means for moving said traveling carriage, said fuel assembly grappling apparatus and said rotation machine in each of said X, Y, Z and .theta. directions, said automatic refueling apparatus comprising: input means for inputting information representing positions of a start point and a target terminal point in a fuel assembly transferring operation;  position detection means for detecting a position of said fuel assembly grappling apparatus along said X-Y-Z-.theta. coordinates;  calculation means responsive to outputs of said input means for determining the shortest route between said start point and said target terminal point through a preset fuel transferring permitted region; and  control means for generating control command signals to move said fuel assembly grappling apparatus along said obtained shortest route based on outputs of said position detection means, and for sending said control command signals to said driving means.  inputting information representing positions of a start point and a target terminal point in a fuel assembly transferring operation;  detecting a position of said fuel assembly grappling apparatus along said X-Y-Z-.theta. coordinates;  reading out said input positions of said start point and said target terminal point;  determining the shortest route between said start point and said target terminal point through a preset fuel transferring permitted region;  generating control command signals to move said fuel assembly grappling apparatus along said obtained shortest route based on said detected position of said fuel assembly grappling apparatus; and  sending said control command signals to said driving means. 2. An automatic refueling apparatus according to claim 1, further comprising means for storing coordinates and an indication of the presence of a fuel assembly for each lattice of a fuel rack in said fuel pool, and coordinates and an indication of the presence of a fuel assembly for each fuel cell of said reactor core. 3. An automatic refueling apparatus according to claim 1, wherein said control means includes means for controlling motions of said fuel assembly grappling apparatus so as to pass not less than one predetermined point in said preset fuel transferring permitted region. 4. An automatic refueling apparatus according to claim 3, wherein said control means includes means of selecting one of plural prepared control modes corresponding to intervals obtained by dividing said shortest route between said start point and said target terminal point, each interval being designated by predetermined points. 5. An automatic refueling apparatus according to claim 1, wherein said position detection means includes limit switches provided at boundaries of said preset fuel transferring permitted region. 6. An automatic refueling apparatus according to claim 1 or 5, further comprising prohibition means for prohibiting a transferred fuel assembly from moving beyond the boundaries of said preset fuel transferring permitted region based on information of said position detection means. 7. An automatic refueling method for automatically transferring fuel assemblies between a fuel pool and a reactor core in a nuclear power plant, using a traveling carriage moving on an X-Y axis in a horizontal plane between the reactor core and the fuel pool in said nuclear power plant, a fuel assembly grappling apparatus provided at said traveling carriage and moved in a Z axis direction perpendicular to said X-Y axis horizontal plane, a rotation machine provided at said traveling carriage to rotate said fuel assembly grappling apparatus around said Z axis in a .theta. direction, and driving means for moving said traveling carriage, said fuel assembly grappling apparatus and said rotation machine in each of said X, Y, Z and .theta. directions, said automatic refueling method comprising the steps of: 8. An automatic refueling method according to claim 7, further comprising the step of storing coordinates and an indication of the presence of a fuel assembly for each lattice of a fuel rack in said fuel pool, and coordinates and an indication of the presence of a fuel assembly for each fuel cell of said reactor core. 9. An automatic refueling method according to claim 7, further comprising controlling the motion of said fuel assembly grappling apparatus so that it passes not less than one predetermined point in said preset fuel transferring permitted region. 10. An automatic refueling method according to claim 9, further comprising selecting one of plural control modes in generating said control command signals, a control mode being selected for each of the intervals obtained by dividing said shortest route between said start point and said target terminal point, with each interval being designated by predetermined points.