Abstract: An ultrasonic angle-beam probe and a method for operating the angle-beam probe include an approach wedge to be driven into a gap. The overall height of the probe sets limits which preclude testing starting from a specific gap width. At least two approach wedges are provided in order to give the angle-beam probe a testing sensitivity that is maintained even in the case of a reduced overall height. A device is provided which can be assigned to a pulse generator, a sound evaluator or a connecting element to a sound transducer, in order to influence a sound echo time.

Abstract: A method of obtaining a leakproof connection between a metallic tube having a leak and a metallic sleeve extending over the leak, includes expanding the sleeve being formed of a material having given strength values against an inner wall surface of the tube being formed of a material having strength values greater than the given values. In order to bridge a gap due to spring-back without the aid of an additional component of a shape memory alloy, a sleeve material having strength values lower than those of the material of the tube is used. A leakproof connection is obtained as the result of the greater spring-back of the tube.

Abstract: A testing head is provided which operates in accordance with the contact technique and has a flexibly constructed adaptor piece that is adapted to an intended contour of the conical bottom surface. A ring structure, which is disposed on the base surface of the adaptor piece, is constructed as a one-piece or multiple-piece ultrasonic transducer.

Abstract: A process and an apparatus for the ultrasonic testing of a component accessible only through a gap, includes driving a carrier accommodating an ultrasonic testing head into an annular gap and bringing the ultrasonic testing head into a position of alignment with the component, for the purposes of repeated testing of components disposed in the poorly accessible gap. Subsequently, the ultrasonic testing head is driven out from the carrier approximately at right angles to the driving-in movement, and is brought into contact with the component. After completing the testing process, the ultrasonic testing head is driven once more into the carrier and brought into a position of alignment with the next component.

Abstract: Pressure vessels of nuclear plants are equipped with so-called pressure-vessel fittings for the purpose of receiving fuel assemblies. If a bulky part of that type is to be exchanged, very large transport containers for transporting to a location outside the nuclear plant are required. In order to ensure that smaller transport containers can be used, it is necessary to dismantle the bulky parts. In order to ensure that the dismantling operation can be carried out without complicated holding devices, provision is made for setting down an open transport container on the bottom of a water tank. A bulky part is inserted into the transport container and the bulky part projects a predeterminable amount above an end surface of the transport container. The bulky part is separated above the end surface through the use of a separating device disposed on the end surface of the transport container.

Abstract: A method for dismantling bulky parts of pressure-vessel fittings of a nuclear plant and for receiving the dismantled parts presents difficulties with regard to radiation-proof handling. In order to solve that problem, a dismantling container which is set down in a water tank is used. The fittings to be dismantled are introduced into the dismantling container. Furthermore, a receiving container for the dismantled parts is inserted into the dismantling container. A dismantling manipulator is supported on the flange of the dismantling container. When the receiving container is full, the dismantling manipulator is moved to the side, the receiving container is extracted and its contents are transferred to a transport container.

Abstract: A method and an apparatus for testing, repairing or exchanging nozzles of the bottom of a reactor pressure vessel include inserting individual shielding containers into the reactor pressure vessel. Shafts pass through a shielding container and water-filled cartridges can be inserted into the shafts. Tubes for receiving probes of an in-core instrumentation are embedded into bottom plates of the remaining shielding containers and into bottoms of the cartridges. After removing a cartridge, a carrier for working tools can be introduced into the shaft. In this way the radioactive loading is considerably reduced by the probes inside or outside the reactor pressure vessel.

Abstract: After some time incipient cracks may occur in nozzles welded directly into a reactor pressure vessel cover for guiding a control rod, which make it necessary to exchange the nozzles. A method is provided for exchanging the nozzles which changes the structure of the cover little during removal and accomplishes low-stress installation. According to the method, the nozzles are installed with prestressing. An annular surface is introduced from the inside of the cover coaxially to the through-bore and a supporting surface is introduced from the outside of the cover, which surfaces serve for applying the prestressing force and arresting the same.

Abstract: A metallic sleeve for bridging a leakage point on a pipe is expanded onto the inner wall surface of the pipe with the aid of an expansion technique. During the expansion process, a gap of approximately 5 to 10 .mu.m occurs between the pipe and the sleeve due to the elastic resilience of the deformed materials. In order to prevent leakage through this gap, the peripheral surface of the end regions of the sleeve carry a component made of a shape-memory alloy which forms a seal between the sleeve and the pipe when a given temperature is reached. The sleeve is used primarily during the repair of heat exchanger tubes.

Abstract: A metallic sleeve for bridging a leakage point on a pipe has a predetermined wall thickness and requires relatively large expansion forces. In order to reduce spring-back after expansion has been completed, the sleeve is of multi-layer construction. The individual layers may be applied one after the other, and the wall thicknesses of all of the layers together correspond to the predetermined wall thickness of the metallic sleeve. The outer surface of each layer has a surface roughness with a profile depth of up to 0.1 mm and the surface hardness of the outer surfaces is greater than the surface hardness of the pipe and of the inner peripheral surfaces of the individual layers.

Abstract: Previously, only webs between connectors in reactor pressure vessel lids have been examined for incipient cracks by using an ultrasonic scanning head. In order to be able to test the connector penetrated by a bush from an annular gap formed between the connector and the bush, a frame is provided which carries a housing through lockable floating bearings for receiving a rotary plate in the housing. The rotary plate is concentrically associated with a centering piece which is adjustable in the vertical direction and is eccentrically associated with a lifting cylinder which is likewise vertically adjustable. A free end of the lifting cylinder carries a probe drive for inserting a probe into the annular gap. The annular gap is scanned by the probe due to an oscillating movement of the rotary plate.

Abstract: Previously when testing a connector penetration of a reactor pressure vessel lid, one assumed that an annular gap between the connector and the sleeve was concentric. However, tests have shown that in some lid structures a deflection of the connector took place after cooling to room temperature, which led to an eccentric configuration of the sleeve and the connector. In order to be able to completely test such annular gaps, a method and device for nondestructive testing of a penetration of a reactor pressure vessel lid according to the invention includes displacing the sleeve with the help of a thrust piece, until an accessible annular gap is reached. A sensor then arrives at the annular gap through a recess in the thrust piece.

Abstract: A boiling water reactor has a control element disposed in a water pond. An apparatus for the neutron-radiography testing of the control element includes a film cassette having a recording area. A water-free hood is fitted over the control element. The hood has an open bottom and a wall facing the film cassette. The wall has an opening formed therein with a cross section corresponding to the recording area. A holding device fits over the opening for receiving the film cassette. The holding device has a downwardly open side extended below the opening through which the film cassette is to be introduced into the water-free space in the holding device. A neutron source, a collimator and the film cassette lie in one measurement plane.

Abstract: Heretofore, dimples or recesses that were distributed over the periphery of a cylindrical wall of a counterbore in a component had to be formed or inserted one after the other, which required complicated positioning work. According to the invention, in order to simultaneously form all of the dimples with a simple positioning device, a deflection body is provided through which at least two milling spindles pass in a planet-like disposition relative to a central control rod. The deflection body is connected to a centering piece facing the counterbore and to an intermediate piece facing away from the counterbore. The intermediate piece in turn forms a type of cylinder/piston connection with a gear housing. Each milling spindle is connected to an output shaft of a gear housing by a flexible shaft that is axially movably guided in between.

Abstract: An apparatus is disposed below a tube plate in a chamber of a steam generator which is accessible through a manhole, for examining and/or repairing steam-generator tubes in the tube plate. A tool or inspection-instrument carrier of the apparatus includes a pneumatic swivel cylinder detachably connected to the apparatus. The swivel cylinder has a housing and an output shaft. A feed unit is supported on the output shaft. A flexible shaft is axially movable by the feed unit. A compressed-air motor is associated with the housing for driving the flexible shaft.

Abstract: In devices for the ultrasonic testing of a head screw inserted into a component, a skew position of an ultrasonic probe with respect to the screw head leads to inaccurate test results. In order to achieve precise test results independently of the position of the screwing-in axis, at least one ultrasonic transducer is disposed in a cradle-mounted centering piece of the ultrasonic probe. An adaptor of the centering piece is located nearer to the screw head than the ultrasonic transducer. The adaptor is matched to the configuration of the screw head. In order to achieve a centering connection with the screw head, the ultrasonic probe can be moved about its axis and in the axial direction. The device is principally to be used to test screws in the core baffle of a nuclear reactor vessel.

Abstract: In this decontamination process, the surfaces contaminated with radioactive substances, in particular on components of cooling circuits in nuclear reactors, are treated in a first treatment step with an aqueous decontamination solution, containing chromic acid and permanganic acid, at a temperature in the range from 270 to 350 K, in particular at usual room temperature. The contaminated surface layers are thus oxidized by means of the permanganic acid, while the effect of the chromic acid is that the modified surface layers do not adhere firmly. In a second treatment step, the surface layers thus modified are removed by a chemical treatment in the same temperature range, as a result of dissolution, or/and removed by mechanical or hydraulic action. Aqueous solutions of organic acids are suitable for the chemical treatment in the second treatment step, it also being advantageously possible to add reducing agents and complexing agents and/or corrosion inhibitors.

Abstract: In order to achieve a precise and time-saving positioning of an inspection device with the aid of a television camera associated with the inspection device, in a process and an apparatus for the remote-controlled positioning according to the invention, the television camera and the inspection device are disposed parallel to each other at a predeterminable distance and one above the other along an axis of symmetry. An internal, inherent or self marking for the television camera is aligned with a marking of the object under inspection. The television camera and the inspection device are displaced together along the axis of symmetry by the predetermined distance.

Abstract: Apparatus for positioning a mast for the inspection and/or repair of a core shroud of a water-cooled nuclear reactor, heretofore have had television cameras directed at centering pins and bores from the side. Due to the inclined direction of surveillance, the alignment produced therewith has been inaccurate. In order to achieve a precise positioning, according to the invention a marking element which is provided between the television camera and the support plate has markings which can be brought into alignment with a marking made on the support plate. The centering pins and the bores are disposed concentrically to one another once they have been brought into alignment.

Abstract: Upper and lower core structures of core internals carry a plurality of centering pins which have free ends protruding into recesses in a fuel assembly endpiece. In the case of the upper core structure in particular, the nuts for fixing the centering pins are difficult to access in the event of a subsequent exchange of pins. Therefore, core internals which do not require a nut for securing on the centering pins are preferred. For this purpose, a centering pin is provided with a center bore passing through it. The ends of the center bores facing away from the fuel assemblies are in the form of conically tapering stepped bores. Each stepped bore has a plug which is displaceable in axial direction relative to the centering pin. The peripheral surface of the plug is conically formed in the same direction and with the same pitch as the stepped bore. The centering pin enters into a play-free fitting connection with a bore in a grid plate.