Patent Number: 048266515
Section: summary

The invention relates to a method for assisting the process of loading a reactor core with new and/or irradiated elongated fuel assemblies, in which a fuel assembly from a storage pit is inserted into the grid position of a reactor core using a refueling machine preferably under a neutron-shielding liquid covering. A method of this kind is known from German Published, Prosecuted Application No. DE-AS 22 46 637. In that publication a container having a plurality of fuel assemblies is supposed to be inserted into the reactor core all at once, in order to speed up the loading process when fuel assemblies are changed. It is also known from German Published, Non-Prosecuted Application No. DE-OS 15 64 301 that when binoculars are used for observation and with a covering of water several meters thick, it is impossible to insert the wavering fuel assemblies into the grid positions of the core without expending a great deal of time. During that time, the fuel assemblies are prevented from wobbling by other means. However, one problem in this respect is that the axis of the carrier or base of the fuel assembly dos not coincide with the desired location of the axis. It is true that the deviations that arise due to bowing, are only on the order of only a few millimeters; nevertheless, they make it considerably more difficult to introduce the fuel assembly carrier into a particular grid position in the reactor core. Furthermore, the mechanical insertion aid proposed in German Published, Non-Prosecuted Application No. DE-OS 15 64 301 cannot be used unless enough space is available between the various grid positions for the insertion of cross-shaped control elements. It is accordingly an object of the invention to provide a method and apparatus for assisting the process of loading a reactor core with elongated fuel assemblies, which overcomes the hereinafore-mentioned disadvantages of the heretoforeknown methods and devices of this general type and with which it becomes possible to insert fuel assemblies in which the axis of the carrier or base deviates from its desired axis. With the foregoing and other objects in view there is provided, in accordance with the invention, a method for assisting the loading of a reactor core with new and/or irradiated elongated fuel assemblies, which comprises inserting a fuel assembly with a fuel assembly carrier from a storage pit into a grid position of a reactor core with a refueling machine having propelling equipment preferably under a neutron-shielding liquid covering, supplying an actual position of the fuel assembly carrier to the propelling equipment of the refueling machine during movement of the refueling machine between the storage pit and the reactor vessel, comparing the actual position of the fuel assembly carrier with a desired position of the fuel assembly carrier to find a deviation, and carrying out a correction of the deviation in the travelling movement of the refueling machine based upon the comparison. Bowing of the fuel assembly, which is entirely to be expected because of its length of over four meters, can accordingly no longer hinder the insertion of the fuel assemblies into the grids of the core supporting structure disposed in the reactor core. If the ascertained actual position of the carrier or base deviates from its desired position, the travel movement of the refueling machine is corrected by the amount of the deviation. In accordance with another mode of the invention, there is provided a method which comprises transmitting a picture from a stationary television camera to a monitor, for recognizing the deviation from the desired position and ascertaining the actual position of the fuel assembly carrier. With the objects of the invention in view there is also provided an apparatus for assisting the loading of new and/or irradiated elongated fuel assemblies having fuel assembly carriers into grid positions of a reactor core in a reactor vessel of a reactor having a storage pit, a flooding pit and a lead through therebetween, comprising a refueling machine having propelling equipment for transferring a fuel assembly from the storage pit to the flooding pit and inserting the fuel assembly into a grid position, means for recognizing the actual position of the fuel assembly carrier at a measuring point in the vicinity of the lead through and for supplying the actual position of the fuel assembly carrier to the propelling equipment of the refueling machine during movement of the refueling machine between the storage pit and the reactor vessel, means for comparing the actual position of the fuel assembly carrier with a desired position of the fuel assembly carrier to find a deviation, and means for carrying out a correction of the deviation in the travelling movement of the refueling machine based upon the comparison. The refueling machine moves to a predetermined position relative to the location of the television camera, so that the actual position of the fuel assembly carrier can be ascertained exactly. In accordance with a concomitant feature of the invention, the lead through includes guide rails for a floodgate and means supported in the guide rails for holding the recognizing means at the measuring point. Fixation of the camera is thus accomplished in a simple manner. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a method and apparatus for assisting the process of loading a reactor core with elongated fuel assemblies, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.