Patent Number: 052971759
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembling machine which assembles the fuel assembly to be provided for the atomic reactor such as the pressurized-water-type light-water reactor. 2. Background Art Conventionally, there are provided the fuel assembly as disclosed in U.S. Pat. No. 5,068,081. This fuel assembly is illustrated in FIG. 2. In FIG. 2, numerals 1 and 2 respectively designate a top nozzle and a bottom nozzle which are positioned apart from each other in a vertical direction and arranged to be faced with each other. A plurality of control-rod guide pipes 3 are extended between and securely fixed to the top and bottom nozzles 1, 2. A plurality of supporting grids 4 are secured to intermediate portions of the respective control-rod guide pipes 3 such that they are positioned apart from each other in a vertical direction. As illustrated in FIGS. 3 to 5, the foregoing supporting grid 4 is formed such that a plurality of thin-plate-shape straps 7 are assembled perpendicularly to each other into a grid by the mutual fitting of slits 8 which are formed in a longitudinal direction and disposed by an equal pitch in the strap, and consequently, a plenty of grid cells 5 are formed in each grid. At the wall surface of each of the grid cells 5, there is provided a pair of a dimple 9 and a spring 10 which are arranged to be faced with each other, wherein the dimple 9 is used for supporting a fuel rod 6. The fuel rod 6 inserted in the grid cell 5 is supported by being pressed against the dimple 9 by the spring 10. Meanwhile, there are provided some methods for inserting the fuel rod 6 into the grid cell 5 in the above-mentioned fuel assembly, as disclosed in Japanese Patent Laid-Open Publication No. 2-181699, for example. According to this method, the spring 10 is brought into an escaping state by use of a key member; then, the tip edge portion of the fuel rod 6 is held by a pull-in rod; thereafter, the fuel rod 6 is pulled in and inserted into each of the grid cells 5. However, the above-mentioned method must require the pull-in rod providing the holding mechanism at its tip edge portion, drive mechanism for this rod, control means for controlling the operations of these mechanisms and the like, which makes the mechanical construction more complex. In addition, it is necessary to perform the holding operation on the fuel rod by the pull-in rod, which raises a drawback in that the time required for inserting the fuel rod into the grid cell must be longer. SUMMARY OF THE INVENTION The present invention is given under consideration of the above-mentioned circumstances, therefore, it is an object to provide an assembling machine for nuclear fuel assembly, having a simple mechanical construction, by which the time required for inserting the fuel rod can be reduced. The assembling machine according to the present invention provides: a base, formed in a plate shape, which is arranged in an inclined manner; a plurality of supporting posts, disposed linearly on the base along with its inclined direction, each of which supports a supporting grid in a state where a grid cell formed in the supporting grid is directed along with the inclined direction; a fuel magazine, provided at an upper portion of the base in its inclined direction, which holds a fuel rod along with the inclined direction in a free-engaged state; a stopper, fixed in the vicinity of a lower edge portion of the fuel magazine in the inclined direction, which regulates a fall-down movement of the fuel rod; and a releasing mechanism which drives the stopper so as to release a regulating operation of the stopper applied to the fuel rod. In the machine according to the present invention, a drive mechanism drives the stopper so as to release the regulation applied to the fuel rod, and consequently, the fuel rod is fallen down by its own weight so that it can be inserted in the grid cell of the supporting grid supported by the supporting post. In other words, it is not necessary to provide the pull-in rod and its drive mechanism and the like which are required in the prior-art machine, therefore, it is possible to simplify the machine construction. Further, it is not necessary to perform the holding operation of the fuel rod by the pull-in rod which is required in the prior-art machine, thus, it is possible to reduce the time required for performing the inserting operation of the fuel rod.