Corrosion sensors for nitric acid media, related corrosion measurement devices, and facilities

Abstract

The present invention provides a body (2) made of one or more materials capable of withstanding an acidic medium and comprising a cavity (20); a working electrode (3) with a contact surface made of one or more electrically conductive materials; a reference electrode (4) with a contact surface made of one or more electrically conductive materials capable of withstanding acidic media; a counter electrode (5) with a contact surface made of one or more electrically conductive materials capable of withstanding acidic media and intended to form an electric circuit with the working electrode; - three seals (6) made from one or more electrically insulating materials capable of withstanding acidic media, each of the seals (6) housed in a cavity in the body and sealingly enclosing one of the electrodes while leaving the contact surface of the electrode exposed; The corrosion sensor (1) is configured to measure the impedance of an electric circuit by applying a measurement potential to a working electrode.

Description

[Technical Field]

[0001] The present invention relates to the field of corrosion sensors, in particular for corrosion in strong acid media such as nitric acid media.

[0002] The invention relates in particular to a corrosion sensor for concentrated hot nitric acid media, i.e. aqueous media with temperatures comprised between 20°C and 135°C and with nitric acid concentrations comprised between 2 mol / L and 5 mol / L.

[0003] The present invention is not limited to application in nitric acid media, but is contemplated for use in other types of acidic or neutral media, such as those found in wastewater. [Background technology]

[0004] In many applications and installations in corrosive media, it is extremely important to monitor the corrosion of immersed elements, especially to monitor the deterioration of the installation.

[0005] For certain facilities, such as nuclear fuel reprocessing plants, corrosion is typically monitored by measurements using ultrasound and / or measurements that rely on predictive models.

[0006] However, obtaining ultrasonic measurements requires shutting down the facility, making it impossible to monitor corrosion at specific locations in the facility. Specifically, monitoring corrosion by ultrasonic measurements assumes that the speed of ultrasonic wave propagation in the material being monitored is known so that the remaining thickness can be determined. Therefore, this ultrasonic inspection method for monitoring corrosion is suitable for materials with sufficiently smooth surfaces and where corrosion is uniform degradation. However, for surfaces with excessively high roughness, the noise generated by the scattering of ultrasonic waves makes spectral analysis impossible.

[0007] This is why predictive models are used. These predictive models are based on experimental results obtained in the laboratory under stable, predetermined operating conditions. However, these models are not optimal because they require complete knowledge and control of the facility's media chemistry. They are also inadequate for the unknowns that may occur during facility operation and cannot take into account changes in the corrosive potential of the facility's media.

[0008] Additionally, there are corrosion monitoring devices that use electrochemical techniques. Currently, these devices are unsuitable for media with high corrosive potential, such as nitric acid media. Specifically, these devices require the use of a reference electrode whose potential must remain relatively stable over time in high-temperature, corrosive media, which currently proves unattainable in corrosive media with temperatures above 60°C.

[0009] Therefore, there remains a need for a sensor for in-situ, real-time corrosion monitoring that overcomes the aforementioned drawbacks.

[0010] Specifically, there remains a need for a corrosion sensor for in-situ, real-time, non-destructive corrosion monitoring in neutral or acidic media, especially in hot, concentrated nitric acid media. Summary of the Invention [Problem to be solved by the invention]

[0011] The object of the present invention is to at least partially meet this / these needs. [Means for solving the problem]

[0012] To this end, the present invention provides a corrosion sensor for monitoring corrosion in a neutral or acidic medium, comprising: a body made of one or more materials capable of withstanding an acidic medium and provided with a cavity; a working electrode, comprising a contact surface made of one or more electrically conductive materials, to which a measurement potential is intended to be applied; a reference electrode with a contact surface made of one or more electrically conductive materials capable of withstanding acidic media; a counter electrode with a contact surface made of one or more electrically conductive materials capable of withstanding acidic media and intended to form an electric circuit with the working electrode in a neutral or acidic medium; - three seals made from one or more electrically insulating materials capable of withstanding neutral or acidic media, each of the seals housed in a cavity of the body and sealingly enclosing one of the electrodes, the working electrode, the reference electrode, and the counter electrode, while leaving the contact surface of said electrode exposed; Equipped with The present invention relates to a corrosion sensor configured to measure the impedance of an electric circuit by applying a measuring potential, thereby determining the resistance of a working electrode to corrosion in a neutral or acidic medium.

[0013] The reference electrode advantageously has a reference potential that is stable in a neutral or acidic medium, in particular in a nitric acid medium.

[0014] By "acidic medium" in the sense of the present invention is meant a liquid medium with a pH of less than 6; the acidic medium may in particular be a strongly acidic medium, i.e. an acidic medium with a pH of less than 2.

[0015] Similarly, a "neutral medium" is a liquid medium with a pH between 6 and 8. For example, the neutral medium may consist of wastewater.

[0016] A material resistant to an acidic medium is one that does not corrode when immersed in said medium. A material resistant to an acidic medium can be resistant to a medium containing a strong acid and a solvent. For example, a material resistant to an acidic medium can be resistant to a medium containing a strong acid and a solvent, where the solvent is water and the strong acid is sulfuric acid or nitric acid. The concentration of the strong acid can be greater than 2 mol / L, and the medium can be at a temperature comprised between 20°C and 135°C. For example, a material resistant to an acidic medium can be resistant to a nitric acid medium, or even to a concentrated, hot nitric acid medium.

[0017] As an option, the contact area of ​​the working electrode is 0.4 mm 2 From 75mm 2 and / or the contact surface area of ​​the reference electrode is 0.4 mm 2 From 75mm 2 and / or the contact area of ​​the counter electrode is 0.4 mm 2 From 75mm 2 is included between.

[0018] Alternatively, the working electrode is in the form of a cylinder, the contact surface of said electrode being contained in one of the discs forming the base of the cylinder.

[0019] Alternatively, the diameter of the working electrode is comprised between 1 mm and 10 mm, preferably equal to 3 mm, and / or the height of the working electrode is comprised between 5 mm and 10 mm, preferably equal to 8 mm.

[0020] As a preference, the contact surface of the working electrode corresponds to between 50% and 95% of the surface area of ​​the disk forming the base of the cylinder.

[0021] As an option, the reference electrode is in the form of a cylinder, the contact surface of said electrode being one of the discs forming the base of the cylinder.

[0022] Alternatively, the diameter of the reference electrode is comprised between 1 mm and 10 mm, preferably equal to 2 mm, and / or the height of the reference electrode is comprised between 5 mm and 10 mm, preferably equal to 8 mm.

[0023] As a preference, the contact surface of the reference electrode corresponds to between 50% and 95% of the surface area of ​​the disk forming the base of the cylinder.

[0024] Alternatively, the counter electrode is in the form of a cylinder, the contact surface of said electrode being one of the discs forming the base of the cylinder.

[0025] Alternatively, the diameter of the counter electrode is greater than the diameter of the working electrode and is comprised between 1 mm and 10 mm, preferably equal to 5 mm, and / or the height of the counter electrode is comprised between 5 mm and 10 mm, preferably equal to 8 mm.

[0026] As a preference, the contact surface of the counter electrode corresponds to between 50% and 95% of the surface area of ​​the disk forming the base of the cylinder.

[0027] Optionally, the reference electrode and / or the counter electrode are made from a noble metal such as platinum, gold, iridium, or an alloy of said metals.

[0028] Optionally, the body and / or seal are made from a polymer, preferably polyetheretherketone or cyclic olefin copolymer.

[0029] Alternatively, the body is of cylindrical shape, preferably with a diameter comprised between 50 mm and 100 mm and / or a height comprised between 30 mm and 100 mm, the cavity being made in such a way as to leave the contact surface exposed from the same bottom surface of the cylinder.

[0030] Alternatively, each of the seals is in the form of a hollow cylinder with a hollow inner cylinder in which a working electrode, a reference electrode or a counter electrode is intended to be placed.

[0031] Optionally, each of the seals includes an external thread that threads into one of the tapped cavities in the body.

[0032] The present invention relates to a device for measuring corrosion in a neutral or acidic medium, comprising: - at least one corrosion sensor as previously described; - an electronic circuit comprising a current analyzer and connecting electrical wires electrically connecting the analyzer to the working electrode, the reference electrode, and the counter electrode to measure the potential of the working electrode relative to the reference electrode and to measure the current flowing between the working electrode and the counter electrode, at least the electrical wires being at least partially hermetically housed in the body of the sensor; and The present invention also relates to a device comprising:

[0033] Optionally, the device comprises an electromagnetic shielding sheath that is resistant to acidic media, preferably capable of withstanding concentrated nitric acid at elevated temperatures, and preferably made from polyetheretherketone or cyclic olefin copolymer, wherein the analyzer is positioned outside the body and the electrical wires have a section that extends outside the body and is sealed within the shielding sheath.

[0034] Another subject of the invention is a bath containing a neutral or acidic solution, preferably a nitric acid solution, preferably an aqueous solution containing nitric acid at a concentration greater than 2 mol / L, the solution being preferably at a temperature comprised between 20°C and 135°C; - at least one corrosion sensor as described above or at least one corrosion sensor of a device as described above, in which at least the contact surface of the working electrode, the contact surface of the reference electrode and the contact surface of the counter electrode are in contact with a nitric acid solution; It is a facility equipped with the following:

[0035] Alternatively, the facility could be a nuclear fuel reprocessing plant.

[0036] According to other of its aspects, the present invention provides a method for operating the corrosion sensor described above, comprising the steps of: a / measuring how the impedance of an electrical circuit comprising the working electrode and the counter electrode evolves over a given time interval; b) determining the rate of corrosion of the material of the working electrode from the progress in the impedance measured in step a); The present invention relates to a method comprising:

[0037] Thus, the present invention essentially consists in a corrosion sensor configured such that when immersed in a neutral or acidic medium, such as a nitric acid medium, only the contact surface of a working electrode, a contact surface of a reference electrode and a contact surface of a counter electrode are in contact with said neutral or acidic medium, the remaining parts of the electrodes being sealingly housed inside a body by means of a seal and therefore hermetically isolated from said neutral or acidic medium.

[0038] By limiting the contact between the neutral or acidic medium and the reference electrode to selected contact surfaces, the stability of the reference electrode potential over time is improved.

[0039] The corrosion sensor according to the invention therefore has the advantage that the potential of the reference electrode remains relatively stable in neutral or acidic media, in particular in concentrated nitric acid at high temperatures.

[0040] Furthermore, by limiting the contact between the neutral or acidic medium and the working electrode to selected contact areas, it becomes easier to monitor how corrosion progresses using the perfectly calibrated geometric characteristics of said electrode.

[0041] The body and seal also provide protection for the electrical wires that connect the electrodes to the current analyzer.

[0042] Advantageously, the corrosion sensor is suitable for monitoring corrosion in facilities having neutral or acidic media, particularly those having hot concentrated nitric acid, and for doing so non-destructively in situ and in real time without the need to shut down the facility.

[0043] As such, corrosion sensors offer better reliability when monitoring facility deterioration.

[0044] Additionally, corrosion sensors allow for lower costs of operating a facility since it is no longer necessary to shut down the facility to monitor it.

[0045] Furthermore, corrosion sensors, associated measurement devices, and associated operations according to the present invention are able to monitor corrosion at its early stages, which means that they are able to monitor how corrosion is progressing without allowing the corrosion to progress too far.

[0046] Other advantages and features will become more clearly apparent on reading the detailed description given by way of non-limiting example with reference to the following figures. [Brief explanation of the drawings]

[0047] [Figure 1] 1 is a perspective view of a corrosion sensor according to the present invention, the body of which is seen as transparent; [Figure 2] FIG. 2 is a view from above of the corrosion sensor according to FIG. [Figure 3] 2 is a view from below of the corrosion sensor according to FIG. 1. [Figure 4] FIG. 2 is a front view of the corrosion sensor according to FIG. [Figure 5] 2 is a longitudinal cross-section (on line AA) of the corrosion sensor according to FIG. 1; [Figure 6] 1 is a perspective view of a seal as used in a corrosion sensor according to the present invention, in which the seal is seen as transparent. [Figure 7]1 is a perspective view of a corrosion sensor according to the present invention, in which the body is seen as transparent and the corrosion sensor is provided with a shielding sheath. [Figure 8] FIG. 8 is a view from below of the corrosion sensor according to FIG. 7. [Figure 9] FIG. 8 is a front view of the corrosion sensor according to FIG. 7. [Figure 10] FIG. 8 is a longitudinal cross-section (on line AA) of the corrosion sensor according to FIG. 7. [Figure 11] 1 is a schematic front view of a nuclear fuel reprocessing facility equipped with a corrosion sensor according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0048] 1 to 5 show a corrosion sensor 1 according to the present invention.

[0049] The corrosion sensor 1 comprises a body 2, a working electrode 3, a reference electrode 4, a counter electrode 5, and a seal 6. The corrosion sensor 1 also comprises electronic circuitry connected to the various electrodes 3, 4, and 5 to measure the impedance of the electrical circuit comprising the working electrode 3 and the counter electrode 5. The impedance measurement is obtained by measuring the potential of the working electrode 3 by measuring the current flowing between the working electrode 3 and the counter electrode 5.

[0050] The body 2 is made from polyetheretherketone or cyclic olefin copolymer, but may be made from any material that is resistant to acidic media and is chemically inert, in particular with respect to hot nitric acid. The body 2 has the shape of a cylinder, for example with a diameter of 40 mm and a height of 30 mm. The body 2 comprises three cavities 20 that are open to the outside, preferably all made starting from one of the disks that form the base 7 of the cylinder.

[0051] Each cavity 20 accommodates a working electrode 3 , a reference electrode 4 and a counter electrode 5 .

[0052] A seal 6 is interposed between each of the electrodes 3, 4, and 5 and one of the cavities 20. Optionally, each of the electrodes 3, 4, and 5 is set inside one of the seals 6. In the illustrated example, the cavity 20, and thus the electrodes 3, 4, and 5, are arranged in a triangle, meaning that each of the electrodes 3, 4, and 5 is centered at one of the vertices of an imaginary triangle, such as an equilateral triangle. This arrangement advantageously allows optimal recovery of the faradaic current generated by the oxidation or reduction of the working electrode 3. Naturally, other arrangements of the electrodes 3, 4, and 5 are conceivable without thereby departing from the scope of the present invention; for example, the electrodes 3, 4, and 5 may be aligned.

[0053] Each of the working electrode 3 , reference electrode 4 , and counter electrode 5 has the general shape of a solid cylinder extending along a longitudinal axis parallel to the longitudinal axis of the body 2 .

[0054] The working electrode 3, the reference electrode 4, and the counter electrode 5 are fitted into the seal 6 in such a way that only a disk corresponding to one of the bottom surfaces of their cylinders is exposed, and thus only those disks are in direct contact with the external medium when the corrosion sensor 1 is immersed in the medium. The remaining portions of each of the electrodes 3, 4, and 5 are protected inside the body 2, and thereby hermetically isolated from the external medium. The seal 6 thus provides a seal between the wall of each of the electrodes 3, 4, and 5 and the body 2, ensuring that the interior of the body 2 is sealed against intrusion.

[0055] In the embodiment shown in Figures 1-5, the cylinder forming the working electrode 3 has a diameter of 3 mm and a height of 8 mm. The cylinder forming the reference electrode 4 has a diameter of 2 mm and a height of 8 mm. The cylinder forming the counter electrode 5 has a diameter of 5 mm and a height of 8 mm. Other dimensions are generally contemplated without thereby departing from the scope of the present invention.

[0056] The working electrode 3 is made of a material in which it is desired to monitor how corrosion progresses in a neutral or acidic medium in which the corrosion sensor 1 is intended to be at least partially immersed. When the working electrode 3 is in contact with a neutral or acidic medium, such as a hot, concentrated nitric acid medium, a corrosion layer may form on the surface of the working electrode 3 in contact with the acidic medium. The impedance of the electrical circuit comprising the working electrode 3 and the counter electrode 5 progresses in a manner inversely proportional to the rate of corrosion of the material from which the working electrode 3 is made. Thus, by measuring the impedance in this manner, the corrosion sensor 1 can, by equivalents, nondestructively observe and monitor, in situ, in real time, the corrosion of any component of a facility in said acidic medium, the component being made of the same material as the working electrode.

[0057] The reference electrode 4 is made of a noble metal such as platinum, gold, iridium, or an alloy of said metals. The material from which the reference electrode 4 is made is therefore able to withstand acidic media as defined above, and in particular concentrated nitric acid media at high temperatures. This advantageously allows the potential of the reference electrode 4, referred to as the reference potential, to remain relatively constant.

[0058] The counter electrode 5 is made of platinum, and therefore the material from which it is made is able to withstand acidic media, and in particular concentrated nitric acid media at high temperatures.

[0059] The seal 6 of the corrosion sensor 1 according to the invention is shown in Figure 6. The seal 6 has the shape of a hollow cylinder with a through cavity 10 in which the working electrode 3, the reference electrode 4 or the counter electrode 5 is intended to be placed. The seal 6 has a diameter of 10 mm and a height comprised between 5 mm and 10 mm. The seal 6 also comprises a thread 11 for screwing the seal 6 into one of the cavities of the body 2.

[0060] The seal 6 is made from an electrically insulating material that can withstand acidic media at temperatures comprised between 20°C and 135°C, and is chemically inert to nitric acid, in particular. For example, the seal 6 is made from polyetheretherketone or cyclic olefin copolymer. Optionally, the seal 6 and the body 2 are made from the same material.

[0061] Furthermore, the body 2 also comprises a cavity 8 and a passage 9. The passage 9 opens into the cavity 8 and to the outside of the body 2 on the side opposite to the side on which the electrodes 3, 4, and 5 are housed. The cavity 8 can therefore accommodate at least part of an electronic circuit for measuring the impedance of the system. It is also conceivable to place other electronic components in the cavity 8. The body 2 can advantageously protect the electronic circuit from the neutral or acidic medium in which the corrosion sensor 1 is intended to be immersed.

[0062] The cavity 8 has the shape of a cylinder with a diameter of 35 mm and a height of 10 mm.

[0063] The passageway 9 allows a portion of an electronic circuit, such as an electrical wire 12, to pass from the inside to the outside of the body 2. For example, the electrical wire 12 may pass along the passageway 9 to electrically connect the electrodes 3, 4, and 5 to a current analyzer, such as a potentiostat, for measuring the impedance of an electrical circuit comprising the working electrode 3 and the counter electrode 5.

[0064] 7-10 show another embodiment of a corrosion sensor 1 according to the present invention. The corrosion sensor 1 is similar to that described above, except that it also comprises an electromagnetic shielding sheath 13 that can withstand acidic media and is hermetically attached to the body 2 around the passage 9. For example, the shielding sheath 13 may be covered with a layer of diamond. The electrical wire 12 is housed inside the shielding sheath 13. The sheath is long enough to protect the electrical wire 12 from where it exits the body 2 to outside the neutral or acidic medium in which the corrosion sensor 1 is intended to be immersed. For example, the shielding sheath 13 may have a length of more than 1 meter.

[0065] The shielding sheath 13 may be in the form of a tube opening into the passage 9. For example, the shielding sheath shown in Figures 7 to 10 is a tube with a wall thickness equal to 1 mm and a diameter equal to 10 mm.

[0066] Alternatively, the electronic circuitry may be housed in its entirety inside the body 2. For example, the electronic circuitry may comprise an analyzer such as a potentiostat, electrical wires 12 for connecting the electrodes 3, 4, and 5 to the analyzer, a battery, and transmitting means configured to transmit system impedance measurements to an external data processing system. In that case, the body 2 need not comprise the passageway 9.

[0067] The corrosion sensor 1 according to the present invention can be used to monitor corrosion in a neutral or acidic medium, such as a hot concentrated nitric acid medium, of a material made from the same material as the working electrode 3. For example, the corrosion sensor 1 according to the present invention can be included in a facility, such as a nuclear fuel reprocessing facility, that has a bath of an acid solution, such as a hot concentrated nitric acid solution.

[0068] A nuclear fuel reprocessing facility 20 is shown in Figure 11. The facility 20 comprises a vessel 21 containing a bath 22 of an acid solution, such as nitric acid (HNO3), in which the nuclear fuel to be reprocessed is intended to be immersed. The facility 20 comprises an inlet pipe 23 and an outlet pipe 24 for supplying the vessel with the acid that makes up the bath 22. An evaporation pipe 25 is arranged above the vessel 21 and is configured to collect evaporation from the bath 22. The facility 20 also comprises heating means 26 configured to heat the bath 22 to a given temperature. The heating means 26 may, for example, comprise piping through which high-temperature water is circulated.

[0069] Facility 20 is equipped with a corrosion sensor 1 according to the present invention. Body 2 of corrosion sensor 1 is immersed in bath 22, and shielding sheath 13 has a portion immersed in bath 22 and attached to body 2, and a portion emerging from bath 22 and extending to the outside of container 21 at inlet pipe 23. Thus, shielding sheath 13 can protect electrical wire 12 until electrical wire 12 exits bath 22 and container 21.

[0070] The working electrode 3 of the corrosion sensor 1 can be made from the same material as the wall of the container 21. Therefore, by measuring the corrosion of the working electrode 3, the corrosion sensor 1 can monitor how the corrosion of the wall of the container 21 progresses.

[0071] Other modifications and improvements are contemplated without thereby departing from the scope of the invention as defined by the following claims. [Explanation of symbols]

[0072] 1. Corrosion sensor 2 Main unit 3 Working electrode 4 Reference electrode 5. Counter electrode 6 Seals 7 Bottom 8 Vacant Space 9 Passage 10 Through-hole 11 Threaded part 12 Electrical Wires 13 Electromagnetic shielding sheath 20 cavities 20 Nuclear Fuel Reprocessing Facility 21 Container 22 Bath 23 Inlet pipe 24 Outlet pipe 26 Heating means

Claims

1. A corrosion sensor (1) for monitoring corrosion in a neutral or acidic medium, comprising: a body (2) made of one or more materials capable of withstanding said acidic medium and comprising a cavity (20); a working electrode (3) with a contact surface made of one or more electrically conductive materials and to which a measurement potential is intended to be applied; a reference electrode (4) with a contact surface made of one or more conductive materials capable of withstanding said acidic medium; a counter electrode (5) with a contact surface made of one or more electrically conductive materials capable of withstanding said acidic medium and intended to form an electric circuit with said working electrode in said neutral or acidic medium; three seals (6) made from one or more electrically insulating materials capable of withstanding the neutral or acidic medium, each of the seals (6) housed in a cavity of the body and sealingly enclosing one of the electrodes, the working electrode, the reference electrode, and the counter electrode, while leaving the contact surface of the electrode exposed; Equipped with The corrosion sensor is configured to measure the impedance of the electrical circuit upon applying the measurement potential, thereby determining the resistance of the working electrode to corrosion in the neutral or acidic medium.

2. The area of ​​the contact surface of the working electrode is 0.4 mm ２ From 75mm ２ and / or the area of ​​the contact surface of the reference electrode is between 0.4 mm ２ From 75mm ２ and / or the area of ​​the contact surface of the counter electrode is between 0.4 mm ２ From 75mm ２ The corrosion sensor of claim 1 , wherein

3. 3. The corrosion sensor according to claim 1, wherein the working electrode is in the form of a cylinder, the contact surface of the electrode being included in one of the discs forming the base of the cylinder, and preferably the diameter of the working electrode is included between 1 mm and 10 mm and / or the height of the working electrode is included between 5 mm and 10 mm, and the contact surface of the working electrode preferably represents between 50% and 95% of the surface area of ​​the disc forming the base of the cylinder.

4. 4. A corrosion sensor according to claim 1, wherein the reference electrode is in the form of a cylinder, the contact surface of the electrode being one of the discs forming the base of the cylinder, and preferably the diameter of the reference electrode is comprised between 1 mm and 10 mm and / or the height of the reference electrode is comprised between 5 mm and 10 mm, and the contact surface of the reference electrode preferably represents between 50% and 95% of the surface area of ​​the disc forming the base of the cylinder.

5. 5. The corrosion sensor according to claim 1, wherein the counter electrode is in the form of a cylinder, the contact surface of the electrode being one of the discs forming the base of the cylinder, and preferably the diameter of the counter electrode is larger than the diameter of the working electrode and is comprised between 1 mm and 10 mm, and / or the height of the counter electrode is comprised between 5 mm and 10 mm, and the contact surface of the counter electrode preferably corresponds to between 50% and 95% of the surface area of ​​the disc forming the base of the cylinder.

6. 6. The corrosion sensor according to claim 1, wherein the reference electrode and / or the counter electrode are made from a noble metal such as platinum, gold, iridium, or an alloy of said metals.

7. 7. A corrosion sensor according to any one of claims 1 to 6, wherein the body and / or the seal are made from a polymer, preferably from polyetheretherketone or cyclic olefin copolymer.

8. 8. A corrosion sensor according to any one of claims 1 to 7, wherein the body is in the form of a cylinder, preferably with a diameter comprised between 50 mm and 100 mm and / or a height comprised between 30 mm and 100 mm, and the cavity is made in such a way as to leave the contact surface exposed from the same bottom surface of the cylinder.

9. 9. The corrosion sensor according to claim 1, wherein each of the seals is in the form of a hollow cylinder having a hollow inner cylinder (10) in which the working electrode, the reference electrode or the counter electrode is intended to be set.

10. 10. The corrosion sensor of any one of claims 1 to 9, wherein each of the seals comprises an external thread (11) that is screwed into one of the tapped cavities (20) in the body.

11. 1. A device for measuring corrosion in a neutral or acidic medium, comprising: At least one corrosion sensor (1) according to any one of claims 1 to 10, an electronic circuit comprising a current analyzer and connecting electrical wires (12) electrically connecting the analyzer to the working electrode, the reference electrode, and the counter electrode to measure the potential of the working electrode relative to the reference electrode and to measure the current flowing between the working electrode and the counter electrode, at least the electrical wires being at least partially hermetically housed in the body of the sensor; 1. A device comprising:

12. 12. The device of claim 11, comprising an electromagnetic shielding sheath (13) that is resistant to the acidic medium, preferably capable of withstanding hot concentrated nitric acid, and preferably made from polyetheretherketone or cyclic olefin copolymer, wherein the analyzer is arranged outside the body and the electrical wires have areas that extend outside the body and are sealed and housed in the shielding sheath.

13. a bath (22) containing a neutral or acidic solution, preferably a nitric acid solution, preferably an aqueous solution containing nitric acid at a concentration greater than 2 mol / L, said solution preferably being at a temperature comprised between 20°C and 135°C; At least one corrosion sensor (1) according to any one of claims 1 to 10 or at least one corrosion sensor (1) of a device according to claim 11 or 12, wherein at least the contact surface of the working electrode, the contact surface of the reference electrode and the contact surface of the counter electrode are in contact with the nitric acid solution; A facility (20) comprising:

14. 14. The facility of claim 13, which is a nuclear fuel reprocessing plant.

15. 11. A method for operating a corrosion sensor according to any one of claims 1 to 10, comprising: a / measuring how the impedance of the electrical circuit comprising the working electrode and the counter electrode evolves over a given time interval; b) determining the rate of corrosion of the material of the working electrode from the progress in impedance measured in step a); A method comprising:

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