Patent Number: 048470368
Section: summary

The invention relates to an apparatus for the inspection of a nuclear reactor fuel assembly, including an ultrasonic test head being carried by a probe and being insertable into spaces between the fuel rods, an encapsulated housing which is disposed in a water-filled pool for accommodating a lever drive mechanism for the movement of the probe disposed outside the housing, and a rotary transmission passing through a wall of the housing, the rotary transmission having a lever linkage at an end thereof disposed outside the housing with a carrier for receiving the probe. Such an apparatus is known from German Published, Non-Prosecuted Application DE-OS No. 33 37 084. In the prior art device, the probe which is equipped with an ultrasonic test head is only to be inserted into the spaces between the fuel rods in one position, namely in the lower end region of the fuel assembly. For this purpose, the rotary trasmission passes through the underside of the housing which is level with the bottom end piece of the fuel assembly and carries the probe by means of a lever linkage. However, the operators of nuclear power plants are required to test the fuel rods for water inclusion, not only at one point but on several levels. It is admittedly known from German Published, Non-Prosecuted Application No. 34 19 765 to move a probe in the vertical direction in order to be able to successively test the fuel rods on several levels. In order to accomplish this, a drive system is necessary which permits the vertical movement of the probes over a fuel assembly length of approximately 4 meters. Apart from the elaborate drive, the vertical movement in the water-filled pool requires a great deal of time to be expended, which is further increased by the step-by-step testing on several levels. Since the testing of the fuel assemblies only takes place with the reactor shut down, the test time reduces the time that the nuclear power plant is available. It is accordingly an object of the invention to provide an apparatus for the inspection of a nuclear reactor fuel assembly, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which permits simultaneous testing on several levels with a reduced amount of time expended. With the foregoing and other objects in view there is provided, in accordance with the invention, an apparatus for the inspection of a nuclear reactor fuel assembly in a water-filled pool having fuel rods with spaces therebetween, comprising an encapsulated housing having walls and being disposed in the water-filled pool, a lever drive mechanism disposed in the housing, a rotary transmission being connected to the lever drive mechanism and extending through one of the walls of the housing toward the surface of water in the pool, a plurality of stationarily disposed lever linkages jutting out from the rotary transmission outside the housing, each of the lever linkages having an end facing away from the rotary transmission, carriers each being connected to a respective one of the ends of the lever linkages, probes each being disposed on a respective one of the carriers, and ultrasonic test heads each being disposed on a respective one of the probes for insertion into the spaces between the fuel rods. The use of several probes permits the simultaneous testing of the fuel assembly on various levels. A time-consuming movement of one probe in the vertical direction is not necessary in order to allow testing successively on various levels. In accordance with another feature of the invention, the carriers are carrying plates, and there is provided a tie bar carrying the probes and interconnecting the carrying plates. This structure permits operation with two lever linkages. However, more than two probes can be attached to the tie bar. In accordance with a concomitant feature of the invention, the rotary transmission has an end facing away from the housing, and there is provided a cover plate in which the end of the rotary transmission is guided, and struts connected between the cover plate and the housing. The additional guidance provides a stabilized construction of the apparatus. 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 an apparatus for the inspection of a nuclear reactor fuel assembly, 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.