Patent Number: 051184621
Section: summary

The invention relates to a manipulator for handling operations, particularly for non-destructive testing, in the vicinity of the nozzle of a vessel in the primary loop of a nuclear power plant. The invention also relates to a method for handling a device, in particular for handling a test head or probe. The nozzles on the vessels in the primary loop are among the highly stressed parts of a nuclear power plant. The weld seams and the inner radius of the nozzles must therefore be tested regularly by non-destructive methods. It is known to perform such tests with a manipulator that has an outrigger which is radial to the nozzle and a probe that is axially displaceable on the outrigger. The manipulator slides on an annular rail that surrounds the nozzle to be tested. In order to execute the required motions in the test operations, the manipulator has a respective drive mechanism for each of the circumferential and radial directions. The outrigger in the radial direction is pressed by mechanical devices against the outer vessel wall to be tested and is aligned tangentially. The vessel having the nozzle to be tested is surrounded by a biological shield and insulation. Since the gap between the vessel and the insulation or the biological shield is sometimes quite narrow, it is very difficult to introduce the conventional manipulator into the annular gap and in fact it is not always possible, because the required structural height of the known outrigger prevents its use with a very narrow annular gap. During testing, the probe must be moved around the neck on concentric or elliptical paths. Due to testing technique requirements, it is necessary to use various probes, which must be manually changed in the course of a test. The testing is made more difficult by the increased radiation in the vicinity of the test specimen, and by the cramped conditions. In the known apparatus, changing the probe requires manual disassembly of the manipulator and is therefore very time-consuming and entails considerable radiation exposure to personnel. Moreover, it is not always possible to circumvent obstacles in the test region, because the radial outrigger has a bottom frame with a spindle extending over its entire length for moving the probe and as a result it projects quite far outward. It is accordingly an object of the invention to provide a manipulator for handling operations, particularly for non-destructive testing, and a method for handling a device, which overcome the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type, which can be introduced into the annular gap more easily than before and which can also work in very narrow annular gaps. Moreover, the manipulator should make it possible to shorten the time required for changing the probe and for reducing the exposure load to operating personnel and the method should enable remote-controlled handling of a device by a manipulator under cramped conditions. With the foregoing and other objects in view there is provided, in accordance with the invention, a manipulator for handling operations particularly for non-destructive testing in the vicinity of the nozzle of a vessel, especially in the primary loop of a nuclear power plant, comprising a carriage being movable in circumferential direction of a nozzle of a vessel, a sled being disposed on the carriage and displaceable in the axial direction of the nozzle, a shoulder joint disposed on the sled, a scissors half having an upper arm with one end supported in the shoulder joint and another end, a lower arm with a free end, another joint connecting the other end of the upper arm to the lower arm, a holder, a further joint connecting the holder to the free end of the lower arm, and a tool or a probe disposed on the holder. In this way, a very slender structure is attained, which makes it possible to use the manipulator in cramped spaces, and above all enables good adaptation to the curvature of the annular gap in the region of the nozzle. Obstacles in the test region can be circumvented by retracting the outrigger, because the lower arm can not only be pivoted but can also be moved in the axial direction of the nozzle. The manipulator also not only makes it possible to drive along the test regions on the vessel but also along all of the test regions on the nozzle jacket. The arms of the manipulator can be positioned in three dimensions. The manipulator is therefore not only suitable for testing purposes, but also for handling operations on the nozzle and in the annular gap. In accordance with another feature of the invention, there is provided a rack drive mechanism for displaceably supporting the shoulder joint on the sled. In accordance with a further feature of the invention, the rack drive mechanism has a rack being disposed on the carriage and having a toothless guide element for rerailing and derailing the sled. In accordance with an added feature of the invention, there is provided drive motor with a position transducer and a gear operatively connecting the drive motor and the sled for adjusting the position of the sled, and a control device connected to the position transducer, and/or another drive motor with another position transducer and another gear operatively connecting the other drive motor and the shoulder joint for adjusting a pivoting angle of the upper arm, the control device being connected to the other position transducer, and/or a further drive motor with a further position transducer and a further gear operatively connecting the further drive motor and the other joint for adjusting a pivoting angle between the upper and lower arms, the control device being connected to the further position transducer. The gears may be bevel gears. In accordance with an additional feature of the invention, the other joint includes means for permitting the lower arm to be folded back onto the upper arm, and the shoulder joint includes means for permitting the upper arm to be folded onto the carriage. In accordance with yet another feature of the invention, the lower arm has a shorter length than the upper arm, which is preferably approximately two-thirds the length of the upper arm. In accordance with yet a further feature of the invention, there is provided an annular rail disposed concentrically about the nozzle of the vessel, and means for derailing the carriage from and rerailing the carriage onto the rail. With the objects of the invention in view, there is also provided a method for handling a device, particularly a probe, in the vicinity of the nozzle of a vessel, especially in the primary loop of a nuclear power plant, with a manipulator, the manipulator including a carriage movable in circumferential direction of the nozzle, a sled being disposed on the carriage and displaceable in axial direction of the nozzle, a shoulder joint disposed on the sled, a scissors half having an upper arm with one end supported in the shoulder joint and another end, a lower arm with a free end, another joint connecting the other end of the upper arm to the lower arm, a holder, a further joint connecting the holder to the free end of the lower arm, and at least one drive motor operatively connected to at least one of the arms, and the method comprises controlling the holder and the other joint along a predetermined path with a control device acting upon the at least one drive motor, varying a pivoting angle of at least one of the arms with the at least one drive motor, optionally varying a position of the sled with a drive motor operatively connected to the sled, and optionally connecting a tool or a probe to the free end of the lower arm with the holder. In accordance with another mode of the invention, there is provided a method which comprises controlling the other joint along a path at least approximately parallel to a surface to be tested. In accordance with a concomitant mode of the invention, there is provided a method which comprises folding the lower arm back onto the upper arm and folding the upper arm onto the carriage, folding the probe or the tool onto the sled, changing the probe or the tool, and introducing or removing the manipulator through an opening in a biological shield into an annular gap between the vessel and the biological shield. 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 manipulator for handling operations, particularly for non-destructive testing, and a method for handling a device, 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.