Abstract: Apparatus and method for testing TIG (tungsten inert gas) welds of end plugs on a sealed nuclear reactor fuel rod. An X-ray fluorescent spectrograph testing unit detects tungsten inclusion weld defects in the top end plug's seal weld. Separate ultrasonic weld inspection system testing units test the top end plug's seal and girth welds and test the bottom end plug's girth weld for penetration, porosity and wall thinning defects. The nuclear fuel rod is automatically moved into and out from each testing unit and is automatically transported between the testing units by rod handling devices. A controller supervises the operation of the testing units and the rod handling devices.

Abstract: Apparatus for remotely controlled examination of the control rod drive penetration stub tubes in the wall of a nuclear reactor pressure vessel including a rotatable carriage on which is mounted a reciprocable shaft to which is attached an inspection instrument for scanning the stub tubes.

Abstract: The lip of the inner radius of a nozzle mounted through the wall of a nuclear reactor vessel is sandwiched between a transmitter and receiver of ultrasonic sound. The transmitter scans the internal surface of the nozzle lip while maintained a constant average distance from a receiver scanning the nozzle surface on the reactor vessel side of the lip. The two surfaces intersecting to form the inner radius vary in angle as the surfaces are scanned by the transmitter and receiver. Linkage is shown between the transmitter/receiver and the boom with which they are caused to sweep the lip to simultaneously accommodate the saddle shape of the inner radius and the varying angle between the lip surfaces.

Abstract: The invention relates to a method for testing fuel element tubes by ultrasonic energy. For testing, each tube becomes disposed in the space between a transmit transducer and a receive transducer. The echo signals falling within a predetermined time interval are evaluated. Since the distance between the transducers may vary as the transducers move through the space between fuel element tubes, the transmitted signal reaching the receive transducer without passing through the tube may be confused with the revolving echo signal. Therefore, this invention discloses an arrangement for cyclically controlling the setting of the time gate before each such tube is in position between the transducers. To this end, the ultrasonic transit time of signals between the transmit transducer and the receive transducer is measured in the gap between the last tested tube and the next to be tested tube.

Abstract: Method and apparatus for monitoring the movement of the control rods of a nuclear reactor.The number of steps of movement in either direction of the rod from which the control rod is suspended is counted. According to the height of the step, an indication of the position of the suspension rod and of the control rod. The apparatus comprises devices for measuring the speed of movement of the control rod, for logging variations in speed higher than a given value, and for counting such variations according to their sign. The invention is particularly useful in pressurized water nuclear reactors.

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.

Abstract: An ultrasonic flaw detector device including axial and circumferential fixed tracks located in a space defined between a pressure vessel of a nuclear reactor and a heat insulating wall surrounding the vessel and arranged axially and circumferentially respectively of the pressure vessel of the nuclear reactor. A rotary track is located at a junction of the axial fixed track and the circumferential fixed track and moved in rotary movement by a chain and has its angle of rotation restricted by a pair of stoppers. A carrier member supporting an ultrasonic probe is moved on the tracks to effect ultrasonic flaw detection to detect any flow that might be present in the pressure vessel. To transfer the carrier member from the axial fixed track to the circumferential fixed track, the carrier member is first transferred from the axial fixed track to the rotatable track, and after the rotary track is rotated, the carrier member is transferred from the rotatable track to the circumferential fixed track.

Abstract: Method and apparatus for detecting defective fuel elements in a nuclear reactor assembly. The assembly (20) is kept entirely immersed in a liquid such as water, ultrasonic waves are propagated successively in each of the fuel elements of the assembly or rods (21), an ultrasonic sensor (25) is disposed near the assembly (20) and the waves which may be scattered into the protective liquid by the defects in the fuel rod are picked up to determine the presence of a defective assembly and locate the defective rod in the assembly. The invention is particularly applicable to fuel assemblies of a pressurized water nuclear reactor.

Abstract: Method of acoustic-emission testing of a steel component such as a vessel of pipeline especially of primary circulatory loops of nuclear reactor installations wherein the component, on one hand is subjected to a pressure medium, such as water, and, on the other hand, to ultrasonic pulses emitted during deformation development resulting from growth of cracks therein or from leaks and transmitted through the component, which includes detecting and amplifying the ultrasonic pulses with equipment, respectively, formed of test probes, which are disposed so as to determine respective sources of acoustic emission due to differences in transmission time of the ultrasonic pulses through the component, and of electronic amplifiers operatively associated with the test probes, and then feeding a resultant amplified defect signal from the equipment to a display, the equipment being tuned to reception of a frequency band of acoustic-emission spectrum which is above a limiting frequency f.sub.

Abstract: Gases contained in the sheaths of the fuel elements are made to expand in order to cause the escape of gas bubbles in the protective liquid into which the fuel assemblies are immersed. The progress of the gas bubbles in the protective liquid is arrested by means of a screen (1) located above the assembly and an acoustic phenomenon associated with the impact of the gas bubbles on the screen or with the accumulation of gas below the surface of the screen is recorded. The appearance of this acoustic phenomenon permits the detection of defective assemblies.The invention applies in particular to pressurized water nuclear reactors.

Abstract: A tool for manipulating an ultrasonic inspection transducer is actuated to move the transducer over the surface of an irregular weld body. The weld body disclosed, joins the nozzle of a reactor vessel to its vessel, the irregularity of the weld body defined by the intersection of the two cylinders. The transducer is moved over the surface of the weld body and actuated to scan through a predetermined angle in relation to the changing aspect of the geometry of the weld body by a cam mounted at the pivoting center of the tool.

Abstract: A method of testing new fuel rods for assemblies for nuclear reactors.Ultrasonic waves are transmitted in the canning tube of the fuel element disposed in the open, with an oblique incidence with respect to the axis of the tube, from one region of the side wall of the tube. By reflection at the walls of the canning tube, these waves produce plate waves or Lamb waves. These Lamb waves are picked up after a certain distance has been covered along the length of the canning tube and the attenuation undergone by these Lamb waves is measured. From this, by comparison with the attenuation results obtained at another part of the length of the tube or with a standard tube, data on the possible presence of moisture in the fuel rod is deduced. The invention particularly applies to the testing of fuel rods of assemblies for a pressurized water nuclear reactor.

Abstract: Defects in nuclear fuel elements are ascertained and located within an assembled fuel assembly by ultrasonic means. In a typical embodiment of the invention, an ultrasonic search unit is positioned within the fuel assembly opposite the lower plenum of the fuel element to be tested. An ultrasonic pulse is radially projected into the element. Defective fuel elements are ascertained by ultrasonic reflection measurements.

Abstract: A reactor vessel in-service inspection assembly (17) having an improved positioning device (80) for properly and repeatedly locating the inspection transducers (75) of the assembly within a hollow portion of the reactor vessel cavity. An acoustic transducer of the positioning device of this invention is affixed to the positioning arm (40) of the inspection transducers (75). The positioning transducer is operable to generate and simultaneously, radially direct acoustic signals around the circumference of the hollow portion of the vessel cavity and receive the signals reflected off of the cavity walls at a location within the hollow cavity. Means are provided for monitoring the received signals as a function of time. The in-service inspection assembly transducer positioning arm is arranged to automatically move in response to the monitored difference in the time of reception of the received signals to locate the positioning transducer at a preestablished location within the hollow portion of the reactor cavity.