Patent Number: 039430375
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to FIGS. 1 and 2, in a round reactor building 1 having a generally circularly extending vertical wall 1a, there is eccentrically situated a reactor pressure vessel 2, the upper terminal portion of which projects upwardly into a reactor pool 7. The latter is surrounded in a semicircle by a fuel element storage pool 3 which is of arcuate outline and which is filled with water to a predetermined level. Adjacent the two ends of the semicircular storage pool and in alignment therewith, there are provided openings 12 and 13 which are needed during the transport and insertion of new fuel elements. A connection between the reactor pool 7 and the fuel element storage pool 3 is provided by a channel 4 controlled by a watertight gate. In the fuel element storage pool 3, directly across from the channel 4, there are situated box-stripping machines 5 and, according to a further development of the invention, laterally of the box-stripping machines 5, there are provided tool storing devices 6 for the handling rods and the like. If now a fuel element exchange operation is to be performed, first the pressure vessel 2 is opened by removing the pressure vessel lid 19 and the cover 20. The reactor pool 7, which is situated above the reactor pressure vessel 2, may then be flooded and the gate of the channel 4 may be opened. After these preparatory steps, a main fuel element exchange gantry 8 is put to work. The gantry 8 has a bridge 8a, one end of which is supported for rotation at 14a by a vertical column 14 disposed substantially in the center of the reactor building 1. The bridge 8a is thus horizontally rotatable about a vertical axis 14b which passes through one end of the bridge 8a and which extends in the center of the building 1. The other end of the gantry bridge 8a is supported on a rail 9 which is situated above the level of an operating platform 10 (approximately at a vertical distance of 5 meters therefrom), and extends in an arc along the wall 1a of the reactor building 1. By means of a non-illustrated grasping device arranged on the hoist trolley of the main fuel element exchange gantry 8, a fuel element situated in the reactor pressure vessel 2 may be grasped, withdrawn from the pressure vessel 2 and carried through the channel 4 to one of the box-stripping machines 5. The arrangement of the rail 9 of the main fuel element exchange gantry 8 above the level of the operating platform 10 makes possible the provision of a second, more simple, fuel element exchange gantry 11 also having a fuel element grasping device mounted thereon. The gantry 11 operates simultaneously with the main fuel element exchange gantry 8 and transports the fuel elements from the storage pool 3 to the box-stripping machines 5 and conversely. Further, by means of the fuel element exchange gantry 11, the fuel elements and the fuel element storage racks 18 may be rearranged in the storage pool 3. The fuel element exchange gantry 11 has a cantilever bridge 11a and is supported and travels on two vertically spaced, parallel extending rails 21 and 22, both disposed beneath the rail 9 for the gantry 8. The support structure for the rail 9 may simultaneously serve -- as it is seen in FIG. 1 -- as the support for the upper rail 21 of the gantry 11. As it is also observable in FIG. 1, the gantry 11 may pass freely under the gantry 8. According to another embodiment of the invention, as illustrated in FIG. 3, there is provided a central column 17 which is a modification of the column 14 of the FIG. 1 embodiment. The column 17, in addition to supporting the gantry 8, also supports the inner rail of a building gantry 16 situated above the gantry 8 and further serves as a support member for a building roof 15. The box-stripping machines 5 are not illustrated in detail, because the usual box-stripping machines may be used. As already mentioned the fuel elements (fuel-rod assembly) are disposed in sheath (boxes). The box-stripping machines 5 serve to pull the fuel-rod assembly out of its box. After being pulled out of its box the fuel-rod assembly mas be transported directly to the fuel element storage pool 3 by the gantry 11. On the way back to the box-stripping machines the gantry 11 transports a new fuel element (fuel-rod assembly) which then is inserted in the box by the box stripping machine 5. Also the tool storing devices 6 are not illustrated in detail because the shape of the devices is determined by the tools. These tools may be for example; handling rods, screw-gripper, underwater-screwdrivers, television equipment and so on. It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.