Abstract: A method and an apparatus for detecting defects in the surface of a metal material relying upon the potential drop method. Namely, a method of precisely determining the shape of crack from a distribution of potential differences in the vicinity of crack by arranging power supplying electrodes and measuring electrodes on the surface of the metal material in the form of a matrix, and switching the electrodes that supply electric current and the electrodes that measure potential differences to measure distributions of potential differences in many directions, and an apparatus for detecting surface defects relying upon the potential drop method. In the apparatus for detecting surface defects, the arrangement of power supplying electrodes and supply currents are optimized to precisely detect the shape of crack in the surface.

Abstract: A method for controlling a multi-joint robot having redundant operating joints, wherein joint velocities are calculated for non-redundant joints with redundant joints being fixed for each of at least a portion of the combinations of the non-redundant joints excluding redundant joints capable of attaining the movement of the robot end at a command velocity specified to the robot, by inverse-coordinate-transformation from the spatial coordinate to a joint coordinate inherent to the robot, on the basis of joint angles detected by an encoder mounted on the joints of the robot and the joint velocities are averaged or nearly averaged to obtain the average value or nearly average value as a desired joint velocity for the joints. The desired joint velocity is supplied to a velocity control unit of the robot as a controlled variable.

Abstract: A guide apparatus comprises an annular rail and jaws for attaching the annular rail onto a cylindrical member to be inspected by an inspecting probe on the rail. The attaching jaws are provided on the rail and include at least two radially stationary jaws and at least one radially movable jaw. Each of the radially stationary jaws has a jaw surface to be abutted on an outer periphery of the cylindrical member. A radial distance between the abutting surface of the radially stationary jaw and the inner peripheral surface of the rail is discontinuously variable.

Abstract: A rail apparatus for running an automatic ultrasonic flaw detector around a reactor pressure vessel for detecting any flaw in the weld beads on the reactor pressure vessel. At least two circumferential rails and vertical rails are connected through turn tables at their crossing points to form a rail unit. The rail unit has vertical rails extending upward from the uppermost circumferential rail. The vertical rails are secured to a gamma shield, so that the rail unit as a whole is suspended from the gamma shield by means of these vertical rails. The rail unit is provided with swing prevention devices for preventing swing thereof. In installation of the rail apparatus, the rail unit is temporarily mounted on the reactor pressure vessel before mounting the latter in a containment vessel. Then, after accurately placing the reactor pressure vessel together with the rail unit in a right place within the containment vessel, the rail unit is supported suitably by the gamma shield.

Abstract: A rail apparatus positioned around the surface of a reactor pressure vessel surfaces (1) for carrying equipment such as a flaw detector to permit the equipment to move along the surface of a reactor pressure vessel in the vertical and circumferential directions. The rail apparatus has a plurality of vertical rails (81) and at least one circumferential rail (82) connected to the vertical rails through turn tables (83) at respective points of intersection. Each vertical rail (81) is supported by a supporting member wall fixed at its one end to a gamma-ray shielding wall (2) surrounding the reactor pressure vessel. The vertical and circumferential rails as a unit are retained by the gamma-ray shielding member (84) through oscillation prevention means (86).

Abstract: An ultrasonic flaw detector for detecting any flaw existing in the inner peripheral corner section of the joint portion between the barrel of a nuclear reactor pressure vessel and each of a plurality of cylindrical nozzles projecting from the barrel, by means of an ultrasonic wave applied from the outer peripheral corner section of the joint portion. The flaw detector has a probe pivotable around an axis which is made to follow up the locus of the center of curvature in the rounded surface of the outer peripheral corner section during the movement of the probe around the nozzle. According to this arrangement, it is possible to achieve a full automatic and remote control of the flaw detector except the attaching and detaching of the same, and to facilitate the processing of the signals representing the result of the flaw detection.