Ultrasonic probe for inspecting a component at a temperature above 150 °C and associated inspection method

Description

[0001] The present invention relates to an ultrasonic probe for inspecting a component at a temperature above 150°C.

[0002] The invention also relates to a method of inspecting the component with such a probe.

[0003] The invention applies in particular to the non-destructive testing of components, in particular to the testing of weld beads on these components.

[0004] These components are, for example, nuclear reactor components such as a steam generator, a tank or a primary conduit.

[0005] When replacing such a nuclear reactor component, it is necessary to carry out the welding on site. Carrying out these welds involves the implementation of restrictive measures such as preheating the components to a temperature above 150°C or local chambering with nitrogen.

[0006] Conventionally, once the weld is completed, the structure is cooled and then inspected using ultrasonic non-destructive testing. If the weld contains defects, it is then necessary to bring the component back up to temperature before repairing the weld. This requires the mobilization of operational teams on site until the weld is declared compliant.

[0007] There is therefore a need to be able to control the welding more quickly in order to save time during the replacement operation and thus be able to restart the nuclear reactor more quickly.

[0008] However, known probes that can withstand high temperatures do not have sufficient acoustic performance to be able to properly control a weld.

[0009] Conversely, known probes with good acoustic properties cannot withstand temperatures above 150°C for extended periods of time. This is because the materials constituting the sabot degrade at such temperatures, or their behavior towards the ultrasound beam is considerably modified when the temperature increases.

[0010] CN207649696U discloses a probe according to the preamble of claim .

[0011] In this context, the invention aims to propose an ultrasonic probe for inspecting a component exhibiting good performance, continuously, at temperatures above 150°C and thus allowing significant time savings during maintenance operations.

[0012] For this purpose, the invention relates to an ultrasonic probe for inspecting a component at a temperature above 150°C, the probe being according to claim 1.

[0013] Thus, the probe according to the invention is capable of carrying out an inspection of the equipment at a temperature above 150°C thanks to the disk of piezoelectric material with low acoustic impedance and having a high upper Curie temperature. Such a probe makes it possible to carry out the ultrasonic inspection of a weld bead as the filling steps of the weld bead progress, while the structure is still preheated and in a nitrogen atmosphere. Thus, it is possible to repair a weld defect as soon as possible and therefore save considerable time on the replacement site as well as considerably reduce hazards.

[0014] The probe may comprise one or more features defined in the dependent claims.

[0015] The invention also relates to a method for inspecting a component at a temperature above 150°C by means of at least one probe as defined above, the method comprising at least the following steps: bringing the shoe into contact with the component to be inspected; emitting an ultrasound beam towards the shoe by the translator, the beam being at least partly transmitted by the shoe towards the component.

[0016] Advantageously, the component comprising a weld bead being produced, the method further comprising the provision of two probes according to any one of the preceding claims and the arrangement of each of the probes on either side of the weld bead being produced.

[0017] The invention will be better understood from reading the following description, given solely by way of example, and made with reference to the appended drawings, in which: [Fig 1 ] there figure 1 is a schematic side representation of an ultrasonic probe according to the invention, arranged on a component to be inspected and comprising an ultrasonic translator and a shoe; [ Fig 2 ] there figure 2 is a sectional view of the ultrasonic translator of the Figure 1 ; And [ Fig 3 ] there figure 3 is a schematic side representation of two probes according to the invention on either side of a weld bead to be inspected.

[0018] An ultrasonic probe 10 is shown in the Figure 1 .

[0019] The probe 10 is intended for the inspection of components 12, in particular metallic ones, such as for example nuclear reactor components, by ultrasound. The probe 10 makes it possible to detect defects in these components, and in particular in the weld beads. These defects are for example cavities, cracks or wetting defects. The components inspected are for example made of stainless steel, ferritic steel, Inconel, etc.

[0020] As seen in the Figures, the probe 10 extends along a main axis X-X'.

[0021] The probe 10 comprises a shoe 14 and an ultrasonic translator 16.

[0022] The shoe 14 and the translator 16 are advantageously screwed together.

[0023] The shoe 14 and the translator 16 are acoustically coupled to each other via a thin layer of high temperature resistant liquid or gel.

[0024] Alternatively, the shoe 14 and the translator 16 are bonded to each other by means of a thin layer of high-temperature epoxy resin.

[0025] This shoe 14 is suitable for being placed in contact with the component 12 to be inspected.

[0026] Shoe 14 is advantageously made of polybenzimidazole.

[0027] This class of polymers is particularly suitable for the production of sabot 14. Indeed, these materials are particularly resistant to high temperatures, up to 150°C and even up to 427°C. They do not degrade at 150°C and even up to 427°C. Furthermore, the attenuation of the ultrasound beam increases only slightly with temperature in this class of materials.

[0028] As visible on the Figure 1 , the shoe 14 comprises an inlet surface 20 and an outlet surface 22.

[0029] The output surface 22 is capable of being in direct contact with the component 12.

[0030] The outlet surface 22 of the shoe and the component 12 are brought into contact with each other by means of a thin layer 23 of high temperature resistant coupling liquid or gel.

[0031] The input surface 20 is in contact with the ultrasonic translator 16.

[0032] As visible on the Figure 1 , the inlet surface 20 and the outlet surface 22 form with each other an angle greater than 10°, advantageously greater than 20°.

[0033] The inlet 20 and outlet 22 surfaces are arranged so that the ultrasound beam emitted by the ultrasonic transducer 16 enters the shoe 14 via the inlet surface 20 and exits the shoe 14 via the outlet surface 22.

[0034] The translator 16 is configured to emit an ultrasonic beam towards the shoe 14.

[0035] In reference to the figure 2 , the translator 16 comprises a probe body 24, a disc 26 and a damper 28.

[0036] The probe body 24 comprises external walls, in particular metallic. The probe body 24 has a substantially parallelepiped shape. Alternatively, the probe body 24 has a shape, for example cylindrical.

[0037] The probe body 24 defines an internal volume 30 having a body length LC along the main axis X-X'. The probe body 24 defines an opening 32 towards this internal volume 30.

[0038] The probe body 24 advantageously comprises a ring 34 arranged in the opening 32 and capable of being in contact with the shoe 14.

[0039] The ring 34 is sealed to the disc 26 and to the shock absorber 28, via a seal 36. The seal 36 advantageously extends over a height of between 1 mm and 3 mm along the main axis X-X', for a disc diameter 26 of between 3 mm and 30 mm.

[0040] The disc 26 is arranged in the opening 32.

[0041] The disc 26 is composed of a piezoelectric material. The disc 26 is configured to act as an ultrasonic transmitter and transmit ultrasonic waves towards the shoe 14. The disc 26 is a transducer, capable of generating and capturing ultrasound. It can thus be used as an ultrasonic transmitter or receiver.

[0042] The disc 26 has an acoustic impedance of between 7 MRayl and 25 MRayl, preferably of between 10 MRayl and 25 MRayl.

[0043] The acoustic impedance of the disc 26 is obtained by multiplying the density of the piezoelectric material forming the disc by its sound propagation speed. The impedance of a piezoelectric ceramic varies slightly depending on the temperature. However, this impedance remains low at 150°C, notably less than 25 MRayl.

[0044] The acoustic impedance of a medium for an acoustic wave characterizes the resistance of the medium to the passage of this wave. It is recalled that 1 Rayl is equal to 1 Pa.s / m.

[0045] Disc 26 has a Curie temperature above 250°C.

[0046] The Curie temperature of a ferroelectric material is the temperature at which the material loses its remanent polarization.

[0047] Disc 26, for example, is made of a composite of PZT (lead zirconate titanate) and air.

[0048] The disc 26 has a front face 38 and a rear face 40.

[0049] The front face 38 is configured to be in contact with the shoe 14. In particular, the disc 26 and the shoe 14 are in direct contact.

[0050] Thus, the probe 10 is devoid of an acoustic adaptation blade disposed between the disk 26 and the shoe 14, unlike conventional translators. The stresses generated by an adaptation blade are such that they would cause the piezoelectric disk 26 to bulge and prevent flat contact from being made with the shoe 14 on the front face 38. In the present invention, the disk 26 made of piezoelectric material with low acoustic impedance makes it possible to avoid such acoustic adaptation on the front face 38.

[0051] As visible on the Figure 2 , the shock absorber 28 is fixed on the rear face 40 of the disc 26.

[0052] The shock absorber 28 extends from the rear face 40 into the internal volume 30 along the main axis XX' over a shock absorber length LA less than the body length LC.

[0053] The damper 28 is partially sealed via the ring 34. Thus, a portion of the damper 28 projects freely out of the ring 34 into the internal volume 30. Since the damper 28 expands significantly, the partial sealing of the damper 28 with the probe body 24 avoids the risk that the swelling of the damper 28 will cause the piezoelectric disc 26 to explode.

[0054] The damper 28 comprises silicone 42 and particles 44 dispersed in the silicone 42. The particles 44 make it possible to diffuse the wave sent towards the rear of the probe 10 by the disk 26.

[0055] Each particle 44 is composed of tungsten or alumina in particular.

[0056] Each particle 44 has a transverse dimension between 10 µm and 250 µm.

[0057] The shock absorber 28 has a coefficient of expansion approximately one hundred times higher than that of the disc 26.

[0058] In reference to the figure 2 , the translator 16 further comprises a rear cover 46 and an electrical connector 48.

[0059] The rear cover 46 is fixed on the face of the probe body 24 opposite the opening 32.

[0060] The electrical connector 48 is arranged in the rear cover 46. The electrical connector 48 is connected via an electrical cable 49 to an electronic ultrasonic non-destructive testing (NDT) control station (not shown) and is thus configured to transmit the transmitted and received electrical signals to the disk 26 via a transmission line 51. The transmission line is a coaxial cable capable of withstanding a temperature greater than 250°C.

[0061] The disc 26 has an electrode 53 on each face 38, 40. One of the electrodes 53 is connected to ground and the other to the core of the coaxial cable. The electrode 53 on the side of the front face 38 rises on the lateral edge of the disc 26 in order to allow a return of the electrode 53 and to be able to solder a wire from the rear face 40 of the disc 26.

[0062] The electrical connection between the two electrodes 53 of the disc 26 and the coaxial cable is made with solder having a melting point greater than 250°C by one or more points. This repetition makes it possible to make the probe reliable in the event of one of the connections breaking.

[0063] A method of inspecting a component 12 according to the invention by means of such a probe 10 will now be explained, with reference to the Figure 3 .

[0064] Component 12 is for example a nuclear reactor component.

[0065] Component 12 is heated to a temperature above 150°C before welding is carried out.

[0066] In the example shown here, two probes 10 are used to check the integrity of a weld bead 50 being produced. The weld bead 50 aims to secure two parts 12A, 12B of the component 12 to be checked. The weld bead 50 fills a groove formed between the two parts 12A, 12B. The weld bead is produced in several passes, a layer 52 of filler material being deposited in the groove at each pass. The layers 52 are superimposed on each other.

[0067] As visible on the Figure 3 , the two probes 10 are arranged on either side of the weld bead 50. A first probe 10 is thus arranged on the first part 12A of the component 12 and a second probe 10 is arranged on the second part 12B of the component 12.

[0068] To carry out the inspection of the weld bead 50, the shoe 14 of each probe 10 is placed against the external surface of the component 12, at a distance from the weld bead 50 to be inspected. This distance is chosen so that the transmitted ultrasound beam is directed towards the area to be inspected. Because the angle between the transmitted ultrasound beam and the normal to the surface is relatively constant and independent of the temperature of the component 12 at the time of inspection, it is easy to determine the distance allowing the transmitted beam to be directed onto the weld bead 50 to be inspected.

[0069] Then, the translator 16 is activated and emits an ultrasonic beam towards the shoe 14. The incident ultrasonic beam enters the shoe 14 through the entry surface 20, propagates inside the shoe 14 and exits through the exit surface 22. It then splits into a transmitted beam and a reflected beam. The transmitted beam enters the component 12.

[0070] After striking the weld bead 50, the ultrasonic beam is reflected and its echo returns to the probe 10, as shown in the figure 3 This echo is recorded and interpreted.

[0071] Thus, the probe 10 according to the invention therefore allows control of a component at a temperature above 150°C, thanks to its design based on a choice of suitable materials and on an architecture allowing the reduction of thermomechanical constraints at the different interfaces.

[0072] It is then possible to carry out the ultrasonic inspection of the weld bead 50 as the steps of filling the weld bead 50 progress, while the component 12 is preheated and in a nitrogen atmosphere.

[0073] This makes it possible to repair a welding defect as quickly as possible, saving considerable time on the replacement site and considerably reducing risks.

Claims

1. An ultrasound probe (10) for inspecting a component (12) at a temperature above 150°C, the probe (10) extending along a major axis (X-X') and comprising: - a shoe (14) suitable for being brought into contact with the component (12) to be inspected, and - an ultrasonic transducer (16) attached to the shoe (14) and configured to emit an ultrasonic beam towards the shoe (14), the transducer (16) including: + a probe body (24) defining an internal volume (30) having a body length (LC) along the main axis (X-X'), the probe body (24) further defining an aperture (32) towards the internal volume (30); + a disk (26) of piezoelectric material arranged in the aperture (32), the disk (26) having a front side (38) and a back side (40), the front side (38) being configured to be in contact with the shoe (14); + a damper (28); characterized .in that the disk (26) having an acoustic impedance comprised between 7 MRayl and 25 MRayl and a Curie temperature greater than 250 °C and in that the damper (28) is attached to the back side (40) of the disk (26) and extending from the back side (40) into the internal volume (30) along the main axis (X-X') over a damper length (LA) shorter than the body length (LC).

2. The probe (10) according to claim 1, wherein the damper (28) comprises silicone (42) and particles (44) dispersed in the silicone (42).

3. The probe (10) according to claim 2, wherein each particle (44) has a transverse dimension comprised between 10 µm and 250 µm.

4. The probe (10) according to any of the preceding claims, wherein the probe body (24) comprises a ring (34) arranged in the aperture (32), the ring (34) being sealed to the disk (26) and the damper (28) via a seal (36), the seal (36) extending over a height comprised between 1 mm and 3 mm along the main axis (X-X'), a part of the damper (28) protruding out of the ring (34) into the internal volume (30).

5. The probe (10) according to any of the preceding claims, wherein the shoe (14) is made of polybenzimidazole.

6. The probe (10) according to any of the preceding claims, wherein the shoe (14) comprises an entry surface (20) in contact with the disk (26) of the transducer (16) and an exit surface (22) suitable for being brought in direct contact with the component (12) to be inspected, the entry surface (20) and the exit surface (22) forming an angle greater than 10° with each other.

7. The probe (10) according to any of the preceding claims, wherein the disk (26) and the shoe (14) are in direct contact, the probe (10) having no acoustic matching layer arranged between the disk (26) and the shoe (14).

8. The probe (10) according to any of the preceding claims, wherein the probe (10) comprises an electrical connector (48) arranged in the transducer (16) and configured to supply electricity to the disk (26).

9. A method for inspecting a component (12) at a temperature above 150°C using at least one probe (10) according to any of the preceding claims, the method comprising at least the following steps: - bringing the shoe (14) into contact with the component (12) to be inspected; - emission, by the transducer (16), of an ultrasound beam toward the shoe (12), the beam being at least partially transmitted by the shoe (14) to the component (12).

10. The inspection method according to claim 9, the component (12) comprising a weld bead (50) which is being produced, the method further comprising providing two probes (10) according to any of the preceding claims and the arrangement of each of the probes (10) on both sides of the weld bead (50) being produced.