Abstract: An eddy current probe for the nondestructive testing of electrically conductive material parts comprises four identical active elements (10a, 10b, 10c, 10d), at lease in pairs, whose centers are arranged in accordance with a square or a quadrilateral, whose diagonals intersect at right angles and have an intersection point located in the center of one of them. The major axes (18a, 18b, 18c, 18d) of said elements are oriented perpendicular to the plane of the square or intersect at the same point on the normal to the center of the square. The active elements are generally windings. Preferably, opposite windings (10a, 10c and 10b, 10d) of the square are connected pairwise in series, so as to produce magnetic fields, which are summated according to the diagonals of the square and the two pairs are connected to one another according to a differential arrangement or circuit.

Abstract: A device for the simultaneous demodulation of a multifrequency signal comprising a processor in which demodulation takes place by calculation. An injector's output signal is multiplied by a complex signal having sinusoids of varying frequencies corresponding to frequency-shifted carriers, thereby transposing the injector's signal on intermediate frequencies.

Abstract: The present invention relates to a digital oscillator comprising an oscillator (40), a counter (41), a memory (42), a digital-analog converter (43) and a low-pass filter (44). The memory is able to directly store a complex signal, rendering the use of a real time calculating unit unnecessary.

Abstract: For the nondestructive testing of an electrically conductive part (T), an eddy current sensor (22a) is proposed having two transmitter windings (26) and one receiver winding (28). These three windings are arranged symmetrically with respect to a reference plane (P1) oriented perpendicular to the surface of the part (T). The receiver winding (28) is placed between the active portions (26a) of the emitter windings (26) and perpendicular to the plane (P1), whereas the transmitter windings (26) are substantially parallel to said plane. The coils and connections of the transmitter windings are such that the receiver winding is not traversed by any current in the absence of a fault. A tool for testing a tube (T), such as a steam generator tube, has two sensors oriented at right angles to one another.

Abstract: So as to position a device, such as an eddy current probe support inside a cylindrical cavity with radial perforations opening into said cavity, a device (36) is proposed, said device including a pole (50) orientated parallel to the axis of the cavity. This pole may occupy different pre-established indexing positions in rotation and in translation inside the cavity by means of a mechanism (42, 44, 54, 58, 60). In each of these indexing positions, an active head (98), mounted at the extremity of the pole (50) by means of a pantograph (66) and a cladding arm (100), is able to move in a specific active zone on the lower wall of the cavity. To this effect, the active head is clad by the arm (100) and is equipped with autonomous thrustors controlling its movement.

Abstract: In order to carry out interventions, particularly for inspection and maintenance purposes, within heat exchangers, such as the steam generators equipping nuclear power stations, a device is proposed, which has an articulated arm formed from at least two rigid segments (24a, 24b), which are articulated to one another about an axis (A), as well as two plates (30a, 30b) mounted at the ends of the articulated arm via two handles (28a, 28b), each authorizing two rotations about two orthogonal axes (B, C), whereof one (B) is parallel to axis (A) and the other (C) is perpendicular to the surface (31a, 31b) of the corresponding plate. Each plate (30a, 30b) carries fastening members (32) able to engage in perforations (20a) of a tube plate (12) of the exchanger, as well as a support (34) for an intervention tool.

Abstract: Detensioning of expanded tubes is brought by way of an installation using a rotopeening method. The tool is constituted by a cage moved along a helical path centered on the axis of the tube to be treated. The cage supports in rotary manner a shaft, whose axis is parallel and offcentered with respect to that of the cage. The shaft carries flexible plates, called brushes, whose ends are equipped with shot able to peen the inner wall of the tube during the rotation of the shaft. The helical path ensures a regular distribution of the impacts and consequently a uniform treatment of the surface.

Abstract: A circuit for the rapid calculation of the real and imaginary parts of the h first harmonics of a signal supplied by a measuring device and particularly for the analysis of the voltage supplied by a non-destructive eddy current testing probe. The circuit comprises an analog-digital converter, a random access memory, and calculating means comprising a PROM, a counter, a multiplier, an accumulator and a sequencer.

Abstract: A device for positioning a member so as to face each of a plurality of perforations arranged in a given grid in a plate, especially for the inspection of the tubes of a steam generator in a nuclear power station. It comprises a body having at least two attachment members for fastening the device in the perforations. The device is rotatable around one or the other of these attachment members so as to displace it on the plate, and has a support carrying the member and pivotable with respect to the body in order to bring the member into a position facing several perforations without displacing the device.

Abstract: Eddy current non-destructive testing device comprising in per se known manner an exciting generator, a probe connected to the latter, means for sampling in the probe a measuring voltage, means for producing a reference voltage, a differential amplifier having a first and second input and an output, a first input receiving the measuring voltage and the second the reference voltage, digital signal processing means having an input connected to the output of the differential amplifier across an amplifier, said processing means successively comprising an analog--digital converter, a first random access memory and a digital processing circuit, wherein the means for producing a reference voltage comprise a second random access memory having an input and an output, the input being connected to the output of the first random access memory across a switching circuit and a digital--analog converter having an input connected to the output of the memory and an output connected to the second input of the differential ampli

Abstract: Supply circuit for an eddy current probe with two windings, comprising two parallel supply channels connected to the probe by a cable, each channel incorporating a reference winding and an amplification circuit having an input and an output, one of the ends of the reference winding being connected to the output of the amplification circuit and the other to the input of said circuit via a negative feedback resistor, wherein the amplification circuit of each channel comprises a first amplifier having an input constituting an input of the amplification circuit and an output connected to an absolute measurement access, a first resistor, whereof one end is connected to the output of the first amplifier, a second amplifier having an input connected to the other end of the first resistor and an output constituting the output of the amplification circuit, and a second resistor connected between the output and the input of the second amplifier.

Abstract: The present invention relates to a device for introducing a mobile positioning body onto a tube plate of a steam generator through a manhole.The device comprises two substantially parallel rails essentially shaped like a curved angle plate, whereby a trolley can slide along the rails and on which can be placed the said moving body. During the introduction of the moving body, the device is provisionally fixed to the tube plate by lugs and to the inner face of the manhole by a pedal maintained in place by a spring.Application to the inspection of steam generator tubes.

Abstract: Apparatus for checking the tubes of a heat exchanger in an area spaced by a given distance from the end of said tubes, by means of a probe performing a helical movement, wherein the apparatus comprises a threaded rod, which can be screwed into a nut carried by a positioning and supporting device suspended on the exchanger tubes, first flexible means, which are perfectly rigid in torsion and of constant length ensuring the integral transmission of a rotation torque between the threaded rod and the probe, second flexible means ensuring the integral transmission of said rotation torque between the rotation control means and the threaded rod, a flexible sheath connecting the nut and a fixed chassis external of the exchanger, and means for sliding the assembly constituted by the probe, the first flexible means, the threaded rod and the second flexible means between a rest position in which the probe is placed in the said nut and an inspection position in which the threaded rod engages in the nut.

Abstract: Probe-holding apparatus for holding a probe for checking steam generator tubes particularly in a nuclear reactor installation. The apparatus comprises a telescopic arm supported via a ball and socket joint from a support mounted in or near an access aperture in a chamber at one end of the steam generator. A probe guide is carried by a carriage pivotally mounted at the other end of the telescopic arm. The carriage includes an endless belt having a series of spaced projections which engage into the ends of the tubes, the projections being spaced by a distance equal to the tube pitch or a multiple thereof. The belt is driven by a stepping motor in order to move the carriage and place the probe guide opposite different ones of the tubes.

Abstract: A method of withdrawing a mobile inspection sensor assembly from the lower header of a vertical tubular heat-exchanger includes the steps of introducing into a guide tube of the assembly and into a water tube of the heat-exchanger aligned therewith an end portion of a dummy sensor in the form of a tube of a relatively rigid material, which may nevertheless be slightly bent, securing the end of the dummy sensor to the water tube by actuating means operable at the other end of the sensor tube, and sliding the sensor assembly along the tube of the dummy to an access opening of the header.A dummy sensor for carrying out this method includes an expansible head which may be mechanically or pneumatically operated to fix the sensor in a water tube.