Patent Number: 046831045
Section: summary

The invention relates to a device for the inspection of nuclear reactor fuel rods bundled together into fuel rod bundles in a fuel element, including a tool or accessory carrier for equipment that may be inserted into gaps between the fuel rods and moved to several levels, and a frame for holding the fuel element and the tool carrier, formed of four supports, a base plate and a cover plate corresponding to U.S. Pat. No. 4,036,686. A device of this type is known from German Published, Non-Prosecuted Application DE-OS No. 25 58 631. In that device, besides the four supports which form a frame for retaining the fuel element together with the base plate and the cover plate, two U-rails also extend between the base plate and the cover plate. The U-rails serve as guide rails for a frame structure which can travel in vertical direction, the frame structure itself being formed of two U-rails disposed on opposite sides and struts which interconnect them. The U-rails guide a carriage which can travel along the rails and which is constructed in the same way as the aforementioned frame. Finally, a further carriage is guided in the U-rails of this carriage, to which a tool or accessory carrier is attached for inserting mirrors into the gaps between the fuel rods. When such elaborate and complicated equipment is used for the inspection of fuel elements and the inspection as a rule has to take place under water, it results in an increased susceptibility to repairs. Equipment of this kind is usually decontaminated after use and shipped to another nuclear installation. The heavy and bulky equipment is awkward to transport. For the same reasons, its decontamination leads to difficulties. It is accordingly an object of the invention to provide equipment for the inspection of fuel rods of nuclear reactors, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type, and which is less complicated, which therefore weighs less, is less susceptible to repairs and can be more easily handled during transport and decontamination. With the foregoing and other objects in view there is provided, in accordance with the invention, a device for the inspection of fuel rods combined into fuel rod bundles in a fuel element of a nuclear reactor, comprising a frame for supporting a fuel element including a base plate, a cover plate and four supports, columns or pillars in the form of four first leadscrew drive mechanisms integrated into the supports, two mutually parallel second leadscrew drive mechanisms attached to and extending transversely to the first leadscrew drive mechanism, a third leadscrew drive mechanism jointly supported by and extending transversely to the second leadscrew drive mechanism, and an accessory or tool carrier mechanism disposed on the third leadscrew drive mechanism and movable or operable in a plurality of levels for entering gaps between fuel rods of the fuel element. Apart from its base plate and its cover plate, the device is thus composed entirely of leadscrew drives. The drives not only function as moving devices, but they also act as supports and thereby contribute considerably to the weight reduction and simplification of the equipment. In accordance with another feature of the invention, each of the leadscrew drive mechanism includes a respective nut in the form of support plate attached to another of the mechanisms. In this way an immediate motion-transmitting connection is achieved between the leadscrew drives. In accordance with a concomitant feature of the invention, the first leadscrew drive mechanisms each have an end surface and a motor having a flange, the cover plate being held between the end faces and the flanges. 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 equipment for the inspection of fuel rods of nuclear reactors, 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.