Corrosion sensor for a nitric acid medium, and associated corrosion measurement device and facility

Abstract

The invention relates to a corrosion sensor (1) comprising: • - a body (2) made of one or more materials that can withstand the acid medium comprising cavities (20); • - a working electrode (3) comprising a contact surface made of one or more electrically conductive materials; • - a reference electrode (4) comprising a contact surface made of one or more electrically conductive materials that can withstand the acid medium; • - a counter electrode (5) comprising a contact surface made of one or more electrically conductive materials that can withstand the acid medium, which electrode is intended to form an electrical circuit with the working electrode; • - three seals (6) made of one or more electrically insulating materials that can withstand the acid medium, each of the seals (6) being accommodated in a cavity in the body and sealingly surrounding one of the electrodes while leaving the contact surfaces thereof exposed, the corrosion sensor being configured to measure the impedance of the electrical circuit by applying an electrical potential to the working electrode.

Description

[0001] Description

[0002] Title: Corrosion sensor for nitric acid medium, Corrosion measuring device and associated installation.

[0003] Technical field

[0004] The present invention relates to the field of corrosion sensors, in particular in a strong acid medium, such as a nitric acid medium.

[0005] The present invention relates in particular to a corrosion sensor for a hot and concentrated nitric acid medium, i.e. an aqueous medium where the temperature is between 20°C and 135°C and comprising a nitric acid concentration of between 2 and 5 mol / L.

[0006] The present invention is not limited solely to applications in nitric acid media and may be envisaged for other types of acid media or in neutral media, such as those encountered in wastewater.

[0007] Prior art

[0008] In many applications and installations in corrosive environments, monitoring the corrosion of submerged elements is essential, particularly for monitoring the aging of installations.

[0009] For some facilities, such as a nuclear fuel processing plant, corrosion monitoring is generally done by ultrasonic measurement and / or based on predictive models.

[0010] However, the implementation of ultrasonic measurement requires the installation to be shut down and does not allow corrosion to be monitored in certain areas of the installation. Indeed, monitoring corrosion by ultrasonic measurement requires knowledge of the propagation speed of ultrasonic waves in the material being monitored, in order to determine the residual thickness. This ultrasound method of monitoring corrosion is therefore suitable for a material whose surface is sufficiently smooth and whose corrosion is a homogeneous dissolution. However, for a surface whose roughness is too high, the noise generated by the diffusion of ultrasonic waves makes spectral analysis impossible.

[0011] This is why predictive models are implemented. These predictive models are based on experimental results obtained in the laboratory under stable and predefined operating conditions. However, these models are not optimal, as they require perfect knowledge and mastery of the chemistry of the installation environment. In addition, these models are not adapted to the hazards that may occur during the operation of the installation: they cannot take into account changes in the corrosive power of the installation environment.

[0012] Furthermore, there are devices for monitoring corrosion that use electrochemical techniques. To date, these devices are not suitable for highly corrosive environments, such as nitric acid environments. Indeed, these devices require the use of a reference electrode whose potential must remain relatively stable in the corrosive and hot environment over time, and, to date, this has not been possible in corrosive environments where the temperature exceeds 60 °C.

[0013] There is therefore a need for a corrosion sensor for in-situ and real-time corrosion monitoring that overcomes the aforementioned drawbacks.

[0014] In particular, there is a need for a corrosion sensor for monitoring corrosion in an acidic or neutral environment, in particular a hot and concentrated nitric acid environment, in situ, in real time and non-destructively.

[0015] The aim of the invention is to respond, at least in part, to this(these) need(s).

[0016] Statement of the invention

[0017] To this end, the invention relates to a corrosion sensor for monitoring corrosion in an acidic or neutral medium, the corrosion sensor comprising:

[0018] - a body made of material(s) resistant to the acid environment, including recesses,

[0019] - a working electrode, comprising a contact surface made of electrically conductive material(s) to which an electrical measurement potential is intended to be applied,

[0020] - a reference electrode, comprising a contact surface made of electrically conductive material(s) and resistant to the acid medium; - a counter-electrode, comprising a contact surface made of electrically conductive material(s) and resistant to the acid medium, intended to provide an electrical circuit with the working electrode in the acid or neutral medium;

[0021] - three seals made of electrically insulating material(s) and resistant to the acid or neutral environment, each of the seals being housed in a recess of the body by surrounding in a sealed manner one of the working, reference and counter-electrodes while leaving their contact surfaces visible, the corrosion sensor being configured to measure the impedance of the electrical circuit by applying the electrical measurement potential and thereby determine the resistance of the working electrode to corrosion in the acid or neutral environment.

[0022] The reference electrode advantageously has a stable reference electrical potential in an acidic or neutral medium, in particular in a nitric acid medium.

[0023] For the purposes of the present invention, the term "acid medium" means a liquid medium with a pH of less than 6; in particular, the acid medium may be a strong acid medium, i.e. a liquid medium with a pH of less than 2.

[0024] Similarly, a “neutral medium” is a liquid medium with a pH between 6 and 8. For example, a neutral medium can be wastewater.

[0025] An acid-resistant material is such that when immersed in said medium it does not corrode. Acid-resistant materials may be resistant to media comprising a strong acid and a solvent. For example, acid-resistant materials may be resistant to media comprising a strong acid and a solvent, the solvent being water and the strong acid being sulfuric acid or nitric acid. The concentration of said strong acids may be greater than 2 mol / L and / or said media may be at a temperature between 20°C and 135°C. For example, acid-resistant materials may be resistant to a nitric acid medium, or even a hot and concentrated nitric acid medium.

[0026] Preferably, the contact surface of the working electrode is between 0.4 mm 2 and 75 mm 2, and / or, the contact surface of the reference electrode is between 0.4 mm 2 and 75 mm 2 , and / or, the contact surface of the counter electrode is between 0.4 mm 2 and 75 mm 2 . Preferably, the working electrode is cylindrical in shape and the contact surface of said electrode is included in one of the base discs of the cylinder.

[0027] Preferably, the diameter of the working electrode is between 1 mm and 10 mm, preferably equal to 3 mm, and / or the height of the working electrode is between 5 mm and 10 mm, preferably equal to 8 mm.

[0028] Preferably, the contact surface of the working electrode represents between 50% and 95% of the area of ​​the base disc of the cylinder.

[0029] Preferably, the reference electrode is cylindrical in shape and the contact surface of said electrode is one of the base discs of the cylinder.

[0030] Preferably, the diameter of the reference electrode is between 1 mm and 10 mm, preferably equal to 2 mm, and / or the height of the reference electrode is between 5 mm and 10 mm, preferably equal to 8 mm.

[0031] Preferably, the contact surface of the reference electrode represents between 50% and 95% of the area of ​​the base disc of the cylinder.

[0032] Preferably, the counter electrode is cylindrical in shape and the contact surface of said electrode is one of the base discs of the cylinder.

[0033] Preferably, the diameter of the counter electrode is larger than that of the working electrode, and is between 1 mm and 10 mm, preferably equal to 5 mm, and / or the height of the counter electrode is between 5 mm and 10 mm, preferably equal to 8 mm.

[0034] Preferably, the contact surface of the counter electrode represents between 50% and 95% of the area of ​​the base disc of the cylinder.

[0035] Preferably, the reference electrode and / or the counter electrode are made of a noble metal such as platinum, gold, iridium or their alloys.

[0036] Preferably, the body and / or the seals are made of a polymer, preferably polyetheretherketone or cyclic olefin copolymer.

[0037] Preferably, the body is cylindrical in shape, preferably with a diameter of between 50 mm and 100 mm and / or a height of between 30 mm and 100 mm, the recesses being made so as to leave the contact surfaces visible from the same base of the cylinder. Preferably, each of the seals is hollow cylindrical in shape with a hollow inner cylinder in which the working electrode, the reference electrode or the counter electrode is intended to be crimped.

[0038] Preferably, each of the sealing gaskets comprises an external thread to be screwed into one of the threaded recesses of the body.

[0039] The invention also relates to a device for measuring corrosion in an acidic or neutral medium, comprising:

[0040] - at least one corrosion sensor as described above,

[0041] - an electronic circuit comprising an electric current analyzer and electrical connecting wires electrically connecting the analyzer to the working electrode, the reference electrode and the counter-electrode, so as to measure the potential of the working electrode relative to the potential of the reference electrode and to measure the current flowing between the working electrode and the counter-electrode, at least the electrical wires being housed at least partly in a sealed manner in the body of the sensor.

[0042] Preferably, the device comprises an electromagnetic shielding sheath resistant to the acidic environment, preferably to hot and concentrated nitric acid, preferably being made of polyetheretherketone or cyclic olefin copolymer, the analyzer being arranged outside the body and the electrical wires comprising a section extending outside the body and housed in a sealed manner in the shielding sheath.

[0043] The invention also relates to an installation comprising:

[0044] - a bath containing an acidic or neutral solution, preferably a nitric acid solution, preferably an aqueous solution comprising nitric acid with a concentration greater than 2 mol / L, preferably the solution being at a temperature between 20°C and 135°C,

[0045] - at least one corrosion sensor as described above or the device according to the above, of which at least the contact surfaces of the working electrode, the reference electrode and the counter-electrode are in contact with the nitric acid solution.

[0046] Preferably, the facility is a nuclear fuel processing plant.

[0047] According to another of its aspects, the invention relates to a method for operating a corrosion sensor as described previously, comprising the following steps: a / measuring the change in the impedance of the electrical circuit comprising the working electrode and the counter-electrode over a given time interval; b / determining the corrosion rate of the material of the working electrode from the change in the impedance measured according to step a / .

[0048] The present invention therefore essentially consists of a corrosion sensor configured so that, when immersed in an acidic or neutral medium, for example a nitric acid medium, only contact surfaces of the working electrode, the reference electrode and the counter-electrode are in contact with said acidic or neutral medium, the rest of said electrodes being housed in a sealed manner in a body by means of seals and thus hermetically isolated from said acidic or neutral medium.

[0049] By limiting the contact between the acidic or neutral medium and the reference electrode to a chosen contact surface, the stability of the reference electrode potential over time is improved.

[0050] Thus, the corrosion sensor according to the present invention has the advantage that the potential of the reference electrode remains relatively stable in the acidic or neutral medium, in particular in a hot and concentrated nitric acid medium.

[0051] Furthermore, by limiting the contact between the acid or neutral medium and the working electrode to a chosen contact surface, it is easier to monitor the evolution of corrosion thanks to the perfectly calibrated geometric characteristics of said electrode.

[0052] The body and gaskets also help protect the electrical wires connecting the electrodes to an electrical current analyzer.

[0053] Advantageously, the corrosion sensor is suitable for monitoring corrosion in an installation with an acidic or neutral environment, in particular a hot and concentrated nitric acid environment, in situ, non-destructively, in real time and without requiring the installation to be shut down.

[0054] The corrosion sensor therefore guarantees greater safety for monitoring the aging of an installation.

[0055] Furthermore, the corrosion sensor allows a reduction in the operating cost of an installation because its shutdown is no longer necessary for its monitoring. Furthermore, the corrosion sensor, the measuring device and the associated operation according to the present invention allow early monitoring of corrosion, that is to say they can follow the evolution of corrosion without it being too advanced.

[0056] Other advantages and characteristics will become more apparent upon reading the detailed description, given for illustrative and non-limiting purposes, with reference to the following figures.

[0057] Brief description of the drawings

[0058] [Fig 1] Figure 1 is a perspective view of a corrosion sensor according to the invention, the body being transparent.

[0059] [Fig 2] Figure 2 is a top view of the corrosion sensor according to Figure 1.

[0060] [Fig 3] Figure 3 is a bottom view of the corrosion sensor according to Figure 1.

[0061] [Fig 4] Figure 4 is a front view of the corrosion sensor according to Figure 1.

[0062] [Fig 5] Figure 5 is a longitudinal sectional view (A- A) of the corrosion sensor according to Figure 1.

[0063] [Fig 6] Figure 6 is a perspective view of a seal as used in a corrosion sensor according to the invention, the seal being transparent.

[0064] [Fig 7] Figure 7 is a perspective view of a corrosion sensor according to the invention, the body being transparent, the corrosion sensor comprising a shielding sheath.

[0065] [Fig 8] Figure 8 is a bottom view of the corrosion sensor according to Figure 7.

[0066] [Fig 9] Figure 9 is a front view of the corrosion sensor according to Figure 7.

[0067] [Fig 10] Figure 10 is a longitudinal sectional view (AA) of the corrosion sensor according to Figure 7.

[0068] [Fig 11] Figure 11 is a schematic front view of a facility for the treatment of nuclear fuel comprising a corrosion sensor according to the present invention.

[0069] Detailed description Figures 1 to 5 illustrate a corrosion sensor 1 according to the present invention.

[0070] The corrosion sensor 1 comprises a body 2, a working electrode 3, a reference electrode 4, a counter-electrode 5 and seals 6. The corrosion sensor 1 also comprises an electronic circuit connected to the different electrodes 3, 4 and 5 so as to measure the impedance of the electrical circuit comprising the working electrode 3 and the counter-electrode 5. Said measurement of the impedance is carried out by measuring the potential of the working electrode 3 by measuring the current flowing between the working electrode 3 and the counter-electrode 5.

[0071] The body 2 is made of polyetheretherketone or cyclic olefin copolymer, but it can be made of any material resistant to acidic environments, in particular chemically inert to hot nitric acid. The body 2 has the shape of a cylinder, for example 40 mm in diameter and 30 mm in height. The body 2 comprises three recesses 20 opening outwards, preferably all made from one of the base discs 7 of the cylinder.

[0072] Each recess 20 houses a working electrode 3, reference electrode 4 and counter electrode 5.

[0073] A seal 6 is interposed between each of the electrodes 3, 4 and 5 and one of the recesses 20. Preferably, each of the electrodes 3, 4 and 5 is crimped into one of the seals 6. In the example illustrated, the recesses 20 and, consequently, the electrodes 3, 4 and 5 are arranged in a triangular manner, that is to say that each of the electrodes 3, 4 and 5 is centered on one of the vertices of a fictitious triangle, for example an equilateral triangle. This arrangement advantageously allows optimal recovery of the faradic current generated by the oxidation or reduction of the working electrode 3. Of course, other arrangements of the electrodes 3, 4 and 5 can be envisaged without departing from the scope of the invention, for example the electrodes 3, 4 and 5 can be aligned.

[0074] The working electrode 3, the reference electrode 4 and the counter electrode 5 each have the general shape of a solid cylinder extending along a longitudinal axis parallel to the longitudinal axis of the body 2.

[0075] The mounting of the working electrode 3, the reference electrode 4 and the counter-electrode 5, in the seals 6 is carried out so that only the disc of one of the bases of their cylinders is visible and thus in direct contact with the external environment, when the corrosion sensor 1 is immersed in said environment. The remainder of each of the electrodes 3, 4 and 5 is protected in the body 2 and thus hermetically isolated from the external environment. Thus, the seals 6 guarantee the seal between the walls of each of said electrodes 3, 4 and 5 and the body 2, and guarantee the seal of the interior of the body 2.

[0076] In the embodiment illustrated in Figures 1 to 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 entirely conceivable without departing from the scope of the invention.

[0077] The working electrode 3 is made of a material for which it is desired to monitor the evolution of corrosion in the acidic or neutral medium in which the corrosion sensor 1 is intended to be at least partially immersed. When the working electrode 3 is in contact with an acidic or neutral medium, for example a hot and concentrated nitric acid medium, then a layer of corrosion can form on the surface of the working electrode 3 in contact with the acidic medium. The evolution of the impedance of the electrical circuit comprising the working electrode 3 and the counter-electrode 5 is inversely proportional to the corrosion rate of the material constituting the working electrode 3. Thus, by this measurement of the impedance, the corrosion sensor 1 makes it possible, by equivalence, to study and monitor in situ, in real time and in a non-destructive manner the corrosion of any component of an installation in said acidic medium, the component being made of the same material as the working electrode.

[0078] The reference electrode 4 is made of a noble metal such as platinum, gold, iridium or their alloys. Thus, the material constituting the reference electrode 4 is resistant to an acid medium as defined above, in particular a hot and concentrated nitric acid medium. This advantageously allows the potential of the reference electrode 4, called the reference potential, to remain relatively constant.

[0079] The counter-electrode 5 is made of platinum. Thus, the material constituting the counter-electrode 5 is resistant to an acidic medium, in particular a hot and concentrated nitric acid medium. Figure 6 illustrates a seal 6 of a corrosion sensor 1 according to the invention. The seal 6 has a hollow cylindrical shape with a through cavity 10 in which the working electrode 3, the reference electrode 4 or the counter-electrode 5 is intended to be crimped. The seal 6 has a diameter of 10 mm and a height of between 5 mm and 10 mm. The seal 6 also comprises a threaded portion 11 for screwing the seal 6 into one of the recesses of the body 2.

[0080] The seal 6 is made of an electrically insulating material resistant to acidic environments, in particular chemically inert to nitric acid for temperatures between 20°C and 135°C. For example, the seal 6 is made of polyetheretherketone or cyclic olefin copolymer. Preferably, the seal 6 and the body 2 are made of the same constituent material.

[0081] Furthermore, the body 2 also comprises a cavity 8 and a passage 9. The passage 8 opens onto the cavity 8 and towards the outside of the body 2, on the side opposite to that in which the electrodes 3, 4 and 5 are housed. Thus, the cavity 8 can house at least part of the electronic circuit for measuring the impedance of the system. It is also conceivable to arrange other electronic components in the cavity 8. The body 2 advantageously makes it possible to protect the electronic circuit from the acidic or neutral environment in which the corrosion sensor 1 is intended to be immersed.

[0082] Cavity 8 has a cylindrical shape of 35 mm in diameter and 10 mm in height.

[0083] The passage 9 allows the passage of a part of the electronic circuit, for example electrical wires 12, from the inside of the body 2 to the outside. For example, said electrical wires 12 can pass through the passage 9 to electrically connect the electrodes 3, 4 and 5 to an electrical current analyzer, such as a potentiostat in order to measure the impedance of the electrical circuit comprising the working electrode 3 and the counter electrode 5.

[0084] Figures 7 to 10 illustrate another embodiment of a corrosion sensor 1 according to the present invention. The corrosion sensor 1 is similar to that described previously except that it also comprises an electromagnetic shielding sheath 13, resistant to acidic environments and hermetically fixed to the body 2 around the passage 9. For example, the shielding sheath 13 may be covered with a diamond layer. The electrical wires 12 are housed in the shielding sheath 13. The sheath has a sufficient length to protect the electrical wires 12 from the outlet of the body 2 to the outside of the acidic or neutral environment in which the corrosion sensor 1 is intended to be immersed. For example, the shielding sheath 13 may have a length greater than 1 m.

[0085] The shielding sheath 13 may be in the form of a tube opening into the passage 9. For example, the shielding sheath illustrated in Figures 7 to 10 is a tube with a wall thickness equal to 1 mm and a diameter equal to 10 mm.

[0086] Alternatively, the electronic circuit may be entirely housed in the body 2. For example, the electronic circuit 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 transmission means configured to transmit the impedance measurements of the system to an external data processing system. In this case, the body 2 may not comprise a passage 9.

[0087] The corrosion sensor 1 according to the present invention can be used to monitor the corrosion of components of the same material as the working electrode 3 in an acidic or neutral medium, for example a hot and concentrated nitric acid medium. For example, the corrosion sensor 1 according to the present invention can be included in an installation comprising a bath of an acid solution, for example a hot and concentrated nitric acid solution, for example a nuclear fuel processing installation.

[0088] Figure 11 illustrates an installation 20 for the treatment of nuclear fuel. The installation 20 comprises an enclosure 21 containing a bath 22 of an acid solution, for example nitric acid (HNO3), in which the nuclear fuels to be treated are intended to be immersed. The installation 20 comprises an inlet conduit 23 and an outlet conduit 24 for supplying the enclosure with the acid composing the bath 22. An evaporation conduit 25 is arranged above the enclosure 21 and configured to recover the evaporations from the bath 22. The installation 20 also comprises a heating means 26 configured to heat the bath 22 to a given temperature. The heating means 26 may, for example, comprise pipes in which hot water circulates. The installation 20 comprises a corrosion sensor 1 according to the present invention.The body 2 of the corrosion sensor 1 is immersed in the bath 22 and the shielding sheath 13 comprises a part immersed in the bath 22 fixed to the body 2 and a part emerged from the bath 22 which extends into the inlet conduit 23 to outside the enclosure 21. The shielding sheath 13 thus makes it possible to protect the electrical wires 12 until outside the bath 22 and the enclosure.

[0089] 21.

[0090] The working electrode 3 of the corrosion sensor 1 may be made of the same material as the wall of the enclosure 21. Thus, by measuring the corrosion of the working electrode 3, the corrosion sensor 1 makes it possible to monitor the evolution of the corrosion of the wall of the enclosure 21. Other variants and improvements may be envisaged without departing from the scope of the invention as defined by the claims below.

Claims

Claims 1. Corrosion sensor (1) for monitoring corrosion in an acidic or neutral medium, comprising: - a body (2) made of material(s) resistant to the acid environment, comprising recesses (20), - a working electrode (3), comprising a contact surface made of electrically conductive material(s) on which an electrical measuring potential is intended to be applied, - a reference electrode (4), comprising a contact surface made of electrically conductive material(s) and resistant to the acid environment; - a counter-electrode (5), comprising a contact surface made of electrically conductive material(s) and resistant to the acid medium, intended to provide an electrical circuit with the working electrode in the acid or neutral medium; - three seals (6) made of electrically insulating material(s) and resistant to the acid or neutral environment, each of the seals (6) being housed in a recess of the body by surrounding in a sealed manner one of the working, reference and counter-electrode while leaving their contact surfaces visible, the corrosion sensor being configured to measure the impedance of the electrical circuit by applying the electrical measurement potential and thereby determine the resistance of the working electrode to corrosion in the acid or neutral environment.

2. Corrosion sensor according to the preceding claim, the contact surface of the working electrode being between 0.4 mm 2 and 75 mm 2 , and / or, the contact surface of the reference electrode being between 0.4 mm 2 and 75 mm 2 , and / or, the contact surface of the counter-electrode being between 0.4 mm 2 and 75 mm 2 .

3. Corrosion sensor according to one of the preceding claims, the working electrode being cylindrical in shape and the contact surface of said electrode being included in one of the base discs of the cylinder, preferably the diameter of the working electrode being between 1 mm and 10 mm and / or the height of the working electrode being between 5 mm and 10 mm, preferably the contact surface of the working electrode representing between 50% and 95% of the area of ​​the base disc of the cylinder.

4. Corrosion sensor according to one of the preceding claims, the reference electrode being cylindrical in shape and the contact surface of said electrode being one of the base discs of the cylinder, preferably the diameter of the reference electrode being between 1 mm and 10 mm and / or the height of the reference electrode being between 5 mm and 10 mm, preferably the contact surface of the reference electrode representing between 50% and 95% of the area of ​​the base disc of the cylinder.

5. Corrosion sensor according to one of the preceding claims, the counter-electrode being cylindrical in shape and the contact surface of said electrode is one of the base discs of the cylinder, preferably the diameter of the counter-electrode being larger than that of the working electrode, and being between 1 mm and 10 mm and / or the height of the counter-electrode being between 5 mm and 10 mm, preferably the contact surface of the counter-electrode representing between 50% and 95% of the area of ​​the base disc of the cylinder.

6. Corrosion sensor according to one of the preceding claims, the reference electrode and / or the counter electrode being made of a noble metal such as platinum, gold, iridium or their alloys.

7. Corrosion sensor according to one of the preceding claims, the body and / or the sealing gaskets being made of polymer, preferably polyetheretherketone or cyclic olefin copolymer.

8. Corrosion sensor according to one of the preceding claims, the body being cylindrical in shape, preferably with a diameter of between 50 mm and 100 mm and / or a height of between 30 mm and 100 mm, the recesses being made so as to leave the contact surfaces visible from the same base of the cylinder.

9. Corrosion sensor according to one of the preceding claims, each of the seals being of hollow cylindrical shape with a hollow inner cylinder (10) in which the working electrode, the reference electrode or the counter electrode is intended to be crimped.

10. Corrosion sensor according to one of the preceding claims, each of the sealing joints comprising an external thread (11) to be screwed into one of the threaded recesses (20) of the body.

11. Device for measuring corrosion in an acid or neutral medium, comprising: - at least one corrosion sensor (1) according to one of the preceding claims, - an electronic circuit comprising an electric current analyzer and electrical connecting wires (12) electrically connecting the analyzer to the working electrode, the reference electrode and the counter-electrode, so as to measure the potential of the working electrode relative to the potential of the reference electrode and to measure the current flowing between the working electrode and the counter-electrode, at least the electrical wires being housed at least partly in a sealed manner in the body of the sensor.

12. Device according to claim 11, comprising an electromagnetic shielding sheath (13) resistant to the acidic environment, preferably to hot and concentrated nitric acid, preferably being made of polyetheretherketone or cyclic olefin copolymer, the analyzer being arranged outside the body and the electrical wires comprising a section extending outside the body and housed in a sealed manner in the shielding sheath.

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

14. Installation according to claim 13, the installation being a nuclear fuel processing plant.

15. Method of operating a corrosion sensor according to any one of claims 1 to 10, comprising the following steps: a / measuring the change in the impedance of the electrical circuit comprising the working electrode and the counter-electrode over a given time interval; b / determining the corrosion rate of the material of the working electrode from the change in the impedance measured according to step a / .

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