WO2019121877A1

WO2019121877A1 - System for detecting a leakage of an electrically conductive fluid from a casing

Info

Publication number: WO2019121877A1
Application number: PCT/EP2018/085782
Authority: WO
Inventors: Frédéric Rey; Serge Albaladejo
Original assignee: Commissariat A L'energie Atomique Et Aux Energies Alternatives
Priority date: 2017-12-22
Filing date: 2018-12-19
Publication date: 2019-06-27
Also published as: FR3075959A1; FR3075959B1

Abstract

The invention relates to the detection and the location of a leakage from a casing 2 containing an electrically conductive fluid. A detection and location system and method are proposed. The cable 10 is intended to be arranged, with a conductive element 20, jointly with the casing. It comprises a conductive wire 13 and an electrical insulator 14 configured so as to electrically insulate the conductive wire in the absence of conductive fluid and allow an electrical connection 2010 between the conductive wire and the conductive element in the presence of conductive fluid, such that a leakage of conductive fluid generates said electrical connection. The system comprises a device for checking its functionality, which comprises a driven switch linked firstly to the conductive wire of the detection cable and secondly to the conductive element, so as to be able to measure the ohmic resistance of the conductive wire of the detection cable when the switch is closed.

Description

"Leak detection system of an electrically conductive fluid from an envelope"

TECHNICAL FIELD OF THE INVENTION

The invention relates to the detection and location of leakage from an envelope containing an electrically conductive fluid, such as an ionic liquid or a liquid metal. In practice, the proposed system and method of detection and location apply more particularly to piping elements. They are nonetheless applicable to any enclosure on which it is desired to ensure the detection and localization of a leak of conductive fluid electricity. It finds particularly advantageous for the field of monitoring facilities in which circulate liquid metals, such as liquid metal heat transfer reactor circuits which some nuclear power plants are provided.

STATE OF THE ART

There are several systems and methods for detecting and locating leakage of an electrically conductive fluid out of an envelope containing it.

The most commonly used leak detection systems inform of the occurrence of a leak. The location of the leak requires heavy installation and implementation with current systems. It is for example used systems, such as that illustrated in Figure 1, based on the sectorization of the detection means in several segments.

In the illustrated example, an enclosure 2 to be monitored (the enclosure is defined as the container of an electrically conductive liquid) is associated with a segmented leakage detection system 200 of resolution DI equal to the length of each segment 210. Each segment is connected to a voltage generator V and an alert device 220. Each alert device detects the occurrence of a current on its respective line in case of leakage and contacting the segment with the speaker. In the example illustrated, the enclosure 2 is electrically conductive and is used as a conductor in the electrical circuit. A leak can be located with a current accuracy of DI.

In the particular case of the appearance of a leak at the ends of two consecutive segments, the prediction is substantially improved. Indeed, it can be estimated that it is of the order of magnitude of the diameter of the implantation piping. In the illustrated case, there are more particularly eight segments, so DI = L / 8, where L is the length of the enclosure. For an enclosure which is a pipe of diameter equal to 1 m and length equal to L = 100 m, DI is 12.5 m. If the leak puts two consecutive segments in contact with the enclosure 2, then the localization can be estimated at about 2 meters for a pipe diameter equal to 1 m, which is six times more accurate than in the more common case of the appearance of a leak at the level of a single segment. However, it is not possible to distinguish under which of the two segments lies the leak.

This type of system requires up as many electrical connections as detection segments and the location is a discrete information, non-continuous spatially.

Furthermore, US Pat. No. 5,382,909 discloses a detection system comprising a source wire, a locating wire and a return wire, an electrical power supply connected by a first terminal to the source wire and a second terminal to the first wire. locating wire, and a voltmeter mounted in parallel at both ends of the locating wire via the return wire. The wires, based on a good electrically conductive material, are configured such that a leak causes an electrical junction, by ionic bonding, between the source wire and the locator wire at the leak. A test circuit is thus formed which, by measuring a voltage drop using the voltmeter, makes it possible to locate the leak according to a continuous spatial detection function. The system according to US Pat. No. 5,382,909 is based on the selection of materials whose ohmic resistance does not depend on any other parameter than on its dimensions. This results in a restriction of the thermal range of use or the choice of materials whose ohmic resistivity must depend slightly on the temperature. Without this, the system according to US 5,382,909 is imprecise or even inoperative.

An object of the present invention is therefore to provide a leak detection and localization solution that overcomes at least in part the aforementioned drawbacks. In particular, there is a need to overcome the dependence on ohmic resistance fluctuations of the conductive material constituting the locating wire as a function of temperature. There is also a need for simplification of current detection systems, without degrading detection and localization performance. There is also a need to reduce the costs of current detection systems, their installation and / or maintenance. There is still a need to provide a more reliable detection solution that can reduce or even eliminate the risk of occurrence of a false alarm.

SUMMARY OF THE INVENTION

To achieve this objective, the present invention provides, in a first aspect, a system for detecting and locating leakage of an electrically conductive fluid from an envelope intended to contain it, comprising:

at least one detection cable intended to be arranged in conjunction with the envelope, and

at least one electrically conductive element arranged in conjunction with the detection cable.

The sensing cable includes at least one conductive wire and an electrical insulator, such as a coating, arranged in conjunction with the lead wire. The electrical insulation is configured to electrically insulate the conductive wire and the conductive element in the absence of conductive fluid and to allow electrical connection between the conductive wire and the conductive element in the presence of conductive fluid, so that fluid leakage occurs. conductor from the envelope generates said electrical junction between the conductor wire of the detection cable and the conductive element at the level of the leak.

The detection and location system further comprises:

an electrical generator configured to be electrically connected on the one hand to a first point, preferably to a first end, of the detection cable, on the other hand to the conductive element, preferably at a first end of the conductive element, and

an instrument for identifying an electrical parameter configured to identify the establishment of said electrical junction.

The system is such that it further comprises a device for verifying its functionality. The verification device may more particularly comprise a controlled switch connected on the one hand to a second point, preferably to a second end, of the detection cable, on the other hand to the conductive element, preferably to a second end of the conductive element.

It is thus possible to measure the ohmic resistance of the conducting wire of the detection cable when the switch is closed. This measured ohmic resistance can therefore be used as a reference with respect to an ohmic resistance measurement performed in the event of subsequent identification of the establishment of an electrical junction between the conductor wire of the detection cable and the conductive element. generated by a conductive fluid leakage from the envelope.

According to a first optional feature, the conductive wire of the detection cable is based on a metal alloy chosen so that the conductor wire of the detection cable has a linear ohmic resistance greater than 0.1 W / m, preferably substantially equal to at 0.95 W / m. Preferably, the metal alloy is chosen so that the conductive wire of the detection cable has a linear ohmic resistance greater than 1.5 W / m, for example substantially equal to 1.85 W / m.

The detection cable may more particularly be designed to be arranged at least partly opposite at least part of an outer periphery of the envelope. More particularly, the system may comprise a single detection cable arranged in conjunction with said envelope so as to extend vis-à-vis the entire part of the periphery of the envelope where a leak is likely to appear, or even vis-à-vis at least a full length of the outer periphery of the envelope.

Preferably, the metal alloy has a resistivity greater than 6.10 ⁷ W.GTI, for example substantially equal to 7.5.10 ⁷ W.GTI, preferably greater than 1 10 ⁶ W.GTI, or even greater than 1, 2.10 ⁶ W .GTI, for example substantially equal to 1.45.10 ⁶ W.GTI.

According to a second aspect, the invention provides a leak detection and localization method implementing a system as introduced above. The method comprises the following steps:

- applying, with the help of the electric generator, a voltage on the one hand at a first point of the detection cable, preferably at a first end of the detection cable, on the other hand to the conductive element, preferably at a first end of the conductive element,

monitor, using the identification instrument, a variation of the electrical parameter measured by the identification instrument, so as to identify, according to a predetermined setpoint, a variation corresponding to the establishment of an electrical junction between the detection cable and the conductive element and thus detect the appearance of a leakage of conductive fluid from the envelope, and

in the event of the appearance of a leak, determine, for example by means of the identification instrument and as a function of the measurement of the electrical parameter, the ohmic resistance R1 of the detection cable between said first point and said electrical junction, to deduce the location of the leak according to a continuous spatial detection function.

The method is such that the monitoring of the variation of the electrical parameter comprises, at substantially regular time intervals:

controlling the closing of a switch of a device for verifying the functionality of the system, the controlled switch being connected to a first point, preferably at a second end, of the detection cable, and to the conductive element, preferably at a second end of the conductive element,

measuring, using the identification instrument, the electrical parameter in the electrical circuit comprising the detection cable, preferably from its first end to its second end, the conductive element, the electrical generator and the 'light switch,

deducing according to the result of the measurement and storing, for example by means of the identification instrument, the ohmic resistance R of the detection cable, preferably from its first end to its second end, and

- control the opening of the switch,

so that, in case of occurrence of a leak after the opening of the switch and preferably before a next closing of the switch, the determination of the ohmic resistance R1 of the detection cable between said first point and said electrical junction is a function of the ohmic resistance R of the detection cable, preferably from its first end to its second end, as stored.

The invention in its various aspects makes it possible to spatially locate the leakage of a fluid conducting electricity from the envelope monitored. The spatial continuity of the location makes it possible to achieve a better accuracy than with a segmented detection system. It includes a material simple to install and implement, especially because of the reduction in the number of electrical son it comprises vis-à-vis the detection and localization systems of the prior art. Potentially, there remains only one wire, namely the detection cable, to perform the detection and location functions, the conductor wire of the detection cable.

The invention overcomes the dependence ohmic resistance fluctuations of the conductor wire constituting the sensing cable as a function of temperature; the choice of the material on which the conductor wire of the detection cable is formed is no longer constrained. In particular, it is advantageously possible to choose a conductive wire having dimensions giving it a high linear ohmic resistance and / or a material having a high ohmic resistivity, for a better location result including at the ends of the detection cable, even if this choice implies that the material has a high thermal coefficient.

The invention considerably improves the reliability of the detection system also with respect to solutions in which a separate detection circuit is provided for each enclosure portion. In particular, the risk of detection of false contacts is even smaller than the number of son implemented is reduced.

The invention in its various aspects is advantageously insensitive to any maintenance or repair operations on the one hand of the system, and more particularly the detection cable, on the other hand of the envelope to be monitored. Maintenance or repair operations are also simplified at least because of the reduction in the number of electrical wires required. Indeed, during a repair, many son lifts of a discrete system would complicate the intervention; their reduction is therefore relevant from this point of view. It also simplifies the electrical wiring at the installation.

Other objects, features and advantages of the present invention will become apparent from the following description and accompanying drawings. It is understood that other benefits may be incorporated.

BRIEF DESCRIPTION OF THE FIGURES

The objects, objects, as well as the features and advantages of the invention will become more apparent from the detailed description of an embodiment thereof which is illustrated by the following accompanying drawings in which:

FIG. 1 schematically illustrates a segmented leak detection system according to the prior art; FIG. 2a schematically represents the leak detection and localization system according to an embodiment of the first aspect of the invention in the idle state;

FIGURE 2b schematically shows the system of FIGURE 2a in the presence of a leak;

FIG. 3 diagrammatically represents a leak detection and localization system according to an embodiment of the first aspect of the invention equipped with a device for verifying its functionality in the idle state;

FIGURE 4 schematically shows the system of FIGURE 3 equipped with the device for checking its functionality in the active state;

FIGURES 5a and 5b each schematically represent a section of an alternative embodiment of the detection cable according to the first aspect of the invention;

FIGURE 6 graphically represents the continuous detection function according to which the invention makes it possible to locate a possible leakage of electrically conductive fluid;

FIGURE 7 is a flowchart illustrating an embodiment of the leak detection and locating method according to the third aspect of the invention;

FIG. 8 diagrammatically represents a leak detection and localization system according to an embodiment of the first aspect of the invention equipped with a device for verifying its functionality in the idle state, the verification device being a variant of that illustrated in FIGURE 3; and

FIG. 9 schematically represents the system of FIG. 8 equipped with the device for verifying its functionality in the active state, according to the variant illustrated in FIG. 8.

The drawings are given by way of examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily at the scale of practical applications. In particular, the relative thicknesses of the different wires, coatings and layers are not necessarily representative of reality.

DETAILED DESCRIPTION OF THE INVENTION

Before beginning a detailed review of embodiments of the invention, are set forth below optional features that may optionally be used in combination or alternatively. Optionally, the leak detection and locating system according to the first aspect of the invention may further have at least any of the following features:

the system further comprises a mass connected to the electric generator, preferably to the second terminal of the electric generator, and to the conductive element;

the detection cable and the conductive element are configured to form an electric circuit powered by the electrical generator, the electrical circuit being configured to be closed when a leakage of conductive fluid from the envelope generates said electrical junction between the electrical cable; detection and the conductive element at the level of the leak;

the metal alloy is chosen from:

an alloy commonly used to form a heating resistive wire, such as an iron-chromium-aluminum alloy, and

a preferably austenitic stainless steel, for example 304 steel or 316 steel;

the detection cable has a linear ohmic resistance and / or the metal alloy has a resistivity such that a splicing operation in one or two places of the detection cable induces a linear ohmic resistance variation of the lower conductive wire. at 20%, preferably less than 5%, for example substantially equal to 1%, with respect to the ohmic resistance R of the unlined detection cable. A repair of the system may consist (for example following detection of actual leakage and repair of the envelope containing the fluid, requiring a cut of the detection cable made necessary by its deterioration at the contact with the fluid of the leak or to render the zone accessible to the repair of the envelope) to cut the detection cable, then to splice it with a portion of new cable, thus generating two welds participating in the overall resistance of the detection cable;

the electrical insulation of the detection cable is based on ceramics;

- the electrical insulation covers the conductor wire of the detection cable:

at substantially regular intervals, for example by forming beads threaded on the conductive wire of the detection cable, or

o continuously throughout its length,

on one side of the lead wire or on any side of the lead wire;

- To allow the electrical connection with the conductive wire in the localized presence of conductive fluid, the coating has at least one of the following characteristics: o The electrical insulation is porous to allow the conductive fluid to infiltrate it from one side to the other,

the electrical insulation is able to fade on contact with the conductive fluid, for example by chemical reaction, and

the electrical insulator is able to become electrical conductor in contact with or near the conductive fluid, for example under the effect of the heat released by the conductive fluid; and

the detection cable further comprises at least one interface layer based on a preferably metallic material, for example based on nickel, between the conductive wire and the coating. The interface layer allows the coating to cling to the conductive wire and also allow deformation compatibility between the high thermal expansion coefficient conductive wire and the lower thermal expansion coefficient ceramic coating;

the electric generator is a voltage generator with integrated current limiter and the identification instrument is a voltmeter connected in parallel to the terminals of the generator;

the conductive element comprises at least one of: a conductive wire and the envelope when the envelope is electrically conductive;

the conductive element is based on the same electrically conductive material, metal or alloy as the conductor of the detection cable and has an electric resistance section of one or more orders of magnitude smaller than that of the detection cable; so that its linear ohmic resistance is much lower than that of the detection cable. Alternatively, the conductive element has a resistivity of at least an order of magnitude, preferably at least two orders of magnitude, the resistivity of the metal alloy forming part of the detection cable, for example the conductive element is based on a conductive metal such as copper or aluminum; and

the casing is a pipework and the detection cable is arranged in one of the following ways: according to a generatrix of the pipework and according to a winding around the pipework.

Optionally, the sensing cable according to the second aspect of the invention may further have at least any of the following features:

the metal alloy has at least one of the following characteristics: o it is chosen so that the conductor wire of the detection cable has a linear ohmic resistance greater than 0.1 W / m, for example substantially equal to 0.95 W / m, preferably greater than 1 W / m, or even greater than 1, 5 W / m, for example substantially equal to 1.85 W / m; and

o its resistivity is greater than 6.10 ⁷ W.GTI, for example substantially equal to 7.5.10 ⁷ W.GTI, preferably greater than 1.10 ⁶ W.GTI, or even greater than 1, 2.10 ⁶ W.GTI, for example substantially equal at 1, 45.10 W.GTI, and

the metal alloy has a thermal coefficient on average strictly greater than 0.003, preferably greater than 0.01, per degree Celsius between 10 ° C. and 500 ° C.

Optionally, the leak detection and locating method according to the third aspect of the invention may further have at least any of the following features:

the electric generator being a voltage generator with integrated current limiter and the identification instrument being a voltmeter connected in parallel to the terminals of the generator,

the application of an electric current comprises applying, with the aid of the voltage generator, a first electrical potential to the conductive wire of the detection cable and a second electrical potential, different from the first electrical potential, to the conductive element,

o the monitoring of the variation of the electrical parameter comprises the monitoring of a variation of voltage at the terminals of the voltage generator using the voltmeter, and

in the event of the appearance of a leak, the determination of said ohmic resistance R1 comprises:

^■ limit, using the voltage generator, the intensity of electric current to a predetermined value Imax, and

^■ measure the voltage at the terminals of the voltage generator using the voltmeter at the said limited intensity,

to deduce said ohmic resistance R1;

- The conductive element having a resistivity of at least an order of magnitude, preferably at least two orders of magnitude, the resistivity of the metal alloy constituting part of the detection cable, being of the same conductive material of electricity, metal or alloy as the conductor of the sensing cable but electrically resistant section of one or more orders of magnitude greater than that of the detection cable, so that its resistance ohmic linear is significantly lower than that of the detection cable; the determination of said ohmic resistance R1 comprises: neglecting the ohmic resistor Rf of the conductive liquid generating the electrical junction between the detection cable and the conductive element, neglecting the ohmic resistance Rt of the conductive element between said electrical junction and the electrical generator in front of the ohmic resistance R1 of the detection cable between said first point and said electrical junction; and

the control of the switch can be carried out to keep it closed for a time, of between 10 ms and 1 s, preferably substantially equal to 100 ms, per time interval, of between 100 ms and 1 min, preferably substantially equal to at 1 s. Thus, preferably, a monitoring / scanning time of 900 ms is provided every second to possibly detect and locate a leak.

By "arranged in conjunction with" is meant the functional relationship of two structural elements to each other according to which at least one is arranged according to the other element. In particular, one of the elements can be arranged according to the dimensions and shape of the other element and / or according to a particular arrangement defined with respect to an implantation of the other element, to achieve together a particular function. These terms are therefore intended to cover a multitude of relative arrangements of two structural elements between them, a multitude that it would be vain to want to detail exhaustively, although some examples of this multitude are described below. However, each relative arrangement of this multitude is deemed unequivocally identifiable when said arrangement is observed in situ or when said arrangement is described by a written or oral description. For example, a sensing cable arranged in conjunction with an envelope may be at a distance or in contact with the envelope, but extends with respect to the envelope over at least a portion of the main dimension (or length) of the latter to perform its function of detecting a leak at least from said part.

By "substantially" constant or regular is meant the quality of a thing that does not need to be rigorously constant or regular, so that the function to which that thing is linked can be realized. A parameter "substantially equal to / less than" a given value means that the parameter is equal to / less than the value given at plus or minus 20% of the value given, preferably at plus or minus 10% of the value. given close.

It is specified that in the context of the present invention, the term "over", "overcomes", "overlaps" or "underlying" or their equivalents does not mean necessarily "in contact with". For example, the deposition of an electrical insulator, such as a coating, on a conducting wire does not necessarily mean that the electrical insulator is directly in contact with the conductor wire, but that means that the electrical insulation covers at the same time. at least partially the conductive wire being either directly in contact with it, or being separated from the conductive wire by at least one other layer or at least one other element.

The term "resistive metallic alloy", or even high resistivity:

a metal alloy which would not be chosen by a person skilled in the art for the purpose of acting as a good electrical conductor; or

- A metal alloy in the form of an electrical conductor wire whose linear ohmic resistance is significantly high. Obtaining this high linear ohmic resistance depends on the ohmic resistivity of the metal alloy and a suitable electrical cross section. In practice, it will retain a wire with an electrical passage section for its implementation "industrial" associated with the search for a metal alloy having the highest ohmic resistivity possible, especially among those relatively common materials. A compromise must therefore be made to choose the conductive material. The choice of materials can therefore be expanded if it meets the desired compromise; or

a metal alloy to which a person skilled in the art would have preferred a metal or another metal alloy to act as a good electrical conductor.

A resistive metal alloy generally has a resistivity that depends significantly on its temperature, especially in a temperature range of 10 ° C to 500 ° C. This property of most metal resistive alloys often make them alloys suitable for the manufacture of heating resistors, usually used in thermal processes (for example in furnaces).

The invention implements a leak detection and localization system 1 comprising a detection cable 10. The detection cable comprises a conductive wire 13 based on a metal alloy, preferably said resistive.

In electrothermal applications, the resistive metal alloy is not coated with an electrical insulator (most often also thermal insulating effect) because it is to facilitate the transfer of heat from the conductive wire to the surrounding material (fluid, solid).

In the applications referred to herein, the conductor wire 13 is not used as a power source by Joule effect, it can therefore be coated with an electrical insulator 14, such as a coating, necessary for an electrical isolation function in the system

I as described below. Note however that in its broadest acceptance, the electrical insulation 14 may be an air gap; the conductor wire 13 can be simply placed on the ground under a casing 2 to be monitored, the latter being for example slightly raised above the ground to provide said air gap between the conductive wire 13 and the casing 2. A possible contribution to the As thermal insulation of the electrical insulator 14 has no effect in the system 1.

This association between conducting wire of resistive metal alloy and electrical insulating coating leads to two major advantages in order to detect and locate a leakage of a fluid conducting electricity from the envelope 2 intended to contain it. Firstly, the increase of the ohmic resistance of the conducting wire 13 with respect to the commonly used wires (copper, aluminum) makes it possible to increase the sensitivity of the system accordingly. Second, it leads to the reduction of the sensitivity to the repair. detection cable 10 with respect to the use of a wire good conductor of electricity.

More particularly, the metal alloy may be chosen such that the conductive wire 13 of the detection cable 10 has a linear ohmic resistance, preferably substantially constant along the conductor wire 13, greater than 0.1 W / m, for example substantially equal to 0.95 W / m, preferably greater than 1 W / m, or even greater than 1, 5 W / m, for example substantially equal to 1.85 W / m. This condition is preferably checked at room temperature. This condition assumes that the metal alloy is chosen taking into account the shape and dimensions, in particular of a section, of the conducting wire 13. The latter can be relatively imposed by the specific application aimed at and by the costs associated with its confection. More particularly, the lower the resistivity of the metal alloy, the greater the section of the conductor wire to be able to comply with the above-mentioned requirement relating to the ohmic linear resistance of the conducting wire. A larger section of the conductive wire 13 involves a greater amount of metal alloy, which represents a cost to control, and such a section is not always reasonably compatible with implementation under specific conditions of space.

It is therefore preferable to find a reasonable compromise between the resistivity of the chosen metal alloy and the cross-section of the conductive wire 13 based on this metal alloy, in order to comply with the above-mentioned linear ohmic resistor.

In addition or alternatively, the metal alloy may have a resistivity greater than 6.10 ⁷ W.GTI, for example substantially equal to 7.5.10 ⁷ W.GTI, preferably greater than 1.10 ⁶ W.GTI, or even greater than 1, 2.10 ⁶ W.GTI, for example substantially equal to 1 45.10 ⁶ Qm This condition is preferably checked at room temperature.

The resistive metal alloy is for example based on iron-chromium-aluminum (FeCrAL) which generally has a resistivity substantially equal to 1.45 × 10 ⁶ μm and which has a linear ohmic resistance substantially equal to 1.85 Ω / m, when in the form of a wire of diameter equal to 1 mm, at room temperature.

From a strictly electrical point of view, it is also possible to use a conductive wire 13 made of austenitic stainless steel for example (such as steel 304, 304L, 316, 316L, 321 or other). At ambient temperature, the electrical resistivity of the stainless steel is substantially equal to 7.5 × 10 ⁷ μm, ie about 2 times lower than for a FeCrAI alloy. At ambient temperature, the ohmic linear resistance of stainless steel, when it is in the form of a wire of diameter equal to 1 mm, is substantially equal to 0.95 W / m, ie approximately 2 times lower than for a wire of the same diameter in FeCrAI alloy.

By using stainless steel rather than FeCrAI alloy, the sensitivity to the measurement is divided by 2 and the sensitivity to a repair is increased by 2. Note however that the system is then less precise, but not so much non-operational, the accuracy may remain acceptable, particularly in relation to a specification to be respected.

In addition, it is contemplated that the electrical insulator 14 is ceramic-based. Current industrial processes do not make it possible to perform a ceramic deposit on a stainless steel. In the case of a conductive wire 13 made of stainless steel, an embodiment of the electrical insulator 14 in the form of beads is possible.

The use of a FeCrAI alloy to form at least part of the conductive wire 13 makes it possible to make the influence of a splicing related to a maintenance operation negligible. It is estimated that the repair introduces two local ohmic contact resistances each rated at 0.1 W. Electrically, their contribution is in the form of additional ohmic resistors in series with the ohmic resistance of the conducting wire 13 of the detection cable 10. For example, these additional ohmic resistors are to be compared to that of a conductor wire 13 based on a FeCrAI alloy and having a section equal to 1 mm ² which has an ohmic resistance substantially equal to 1.8 W / m; we see in this example that they are relatively negligible when the conductor wire 13 has a length of the order of 1 m, which will generally be the case given the size of the speakers to monitor. The parameter consisting of the ohmic resistance or more precisely the linear ohmic resistance is interesting because if, contrary to the resistivity of a material, it still depends on the dimensions given to this material, it is still limited because which dimensions can not be envisaged with a view to a reasonable implementation of the present invention. For example, depending on these dimensions, a stainless steel tube may have a linear resistance (in Ohms / m) of the same order of magnitude as a copper wire of much smaller section. Moreover, as we will see later, the system 1 makes it possible to measure an ohmic resistance.

The parameter consisting of the resistivity of the material is not useless. For example, depending on their respective resistivity, it is known that the ohmic resistance of an electrical copper conductor compared to that of an electric FeCrAI or stainless steel conductor is negligible, since the conductors have the same dimensions or dimensions of the same order of magnitude.

Note that the ohmic resistance of the enclosure to be monitored may also be negligible compared to that of an electric conductor made of FeCrAI or stainless steel. Consider, for example, a DN25 copper pipe, this example probably constituting the enclosure to be monitored whose ohmic resistance is greatest; it is therefore a penalizing case. This piping may be arranged in conjunction with a detection cable comprising a FeCrAI or stainless steel conductor wire 13 whose diameter is of the order of 1 mm (generally less). This example presents a reasonable dimensioning for the realization of a leak detection system 1 according to the invention.

The use of a resistive metal alloy goes against what is recommended. Indeed, such alloys generally have a thermal coefficient, measuring the variability of its ohmic resistance as a function of its temperature, which is significant and therefore poorly suited, according to the art, to their application as a component of a detection cable 10. On the contrary, a major advantage related to the choice of a conductive material with low thermal dependence is to make the system immune to the temperature variations of the envelopes or enclosures to be monitored; the temperature of these speakers is indeed often subject to strong variations whether in time or along the detection path. We will see that the present invention makes it possible to overcome this ohmic resistance variability as a function of temperature. Thus, contrary to the state of the art, the present invention advantageously allows the use of a metal alloy called resistive having a thermal coefficient on average strictly greater than 0.003, and possibly greater than 0.01, per degree Celsius between 10 ° C and 500 ° C. Thus, the copper whose thermal coefficient is substantially less than 0.004 can a priori be rendered usable as a material based on which the conductive wire 13 of the detection cable is constituted.

More particularly, a coating as an electrical insulator 14 may cover the lead 13 in several ways. It can cover it substantially at regular intervals. It then takes for example the form of beads strung on the conductor wire 13 of the detection cable 10. It can also cover it continuously throughout its length. Whether the covering of the conductive wire 13 by the coating 14 is continuous or at regular intervals, it may still consist in covering one side of the conductive wire 13 or all the sides of the conductive wire 13. For example, it is possible to insert studs 14 between the conductive wire 13 of the detection cable 10 is the envelope, and optionally to stretch the conductor 13 of the detection cable 10, so that the conductive wire 13 is kept taut at a substantially constant distance from the envelope 2, and more generally of a conductive element 20 as described below.

1 / Case of detection with a cuiyre wire isolated by a deposit of electrical insulation:

Copper having a resistivity of 1.72 × 10 ⁸ Ωm (at 20 ° C.), a copper wire 10 m long and having a section equal to 1 mm ² has an ohmic resistance equal to 0.022 W.

The introduction of two local ohmic contact resistances changes the ohmic resistance of the wire and the gate to a value of about 0.222 W, a variation of more than 900%.

For this reason, the use of copper as the material on which the conductor wire 13 is made does not seem realistic, regardless of the variability of its ohmic resistance as a function of temperature.

21 Case of detection with insulated FeCrAI wire by electrical insulating deposit:

A FeCrAI-based alloy having a resistivity of approximately 1.45 × 10 ⁶ W.GTI (at 20 ° C.), a conductive wire 13 based on such an alloy, 10 m long and with a section equal to 1 mm ² , has an ohmic resistance equal to 18.46 W.

The introduction of the two local ohmic contact resistances changes the ohmic resistance of the conductor wire 13 and the door to a value of 18.66 W, a variation of 1.08%.

More generally, the resistive metal alloy constituting the conductive wire 13 of the detection cable 10 according to the first aspect of the invention may have a resistivity and / or an ohmic resistance per meter such that a splicing operation in one or two places of the detection cable 10 induces a linear ohmic resistance variation of the conductor wire 13 less than 20%, preferably less than 5%, for example substantially equal to 1%, with respect to the ohmic resistance R of the uncoupled detection cable 10. Thus, the use of a stainless steel, such as those listed above, is conceivable since a wire 13 based on such a steel, 10m long and with a section equal to 1 mm ² , offers a variation related to the introduction of the two local ohmic contact resistances substantially limited to 2%.

With reference to FIGS. 5a and 5b, the conductive wire 13 may constitute the core of the detection cable 10. In a nonlimiting manner, and for purely illustrative purposes, it may be prepared from a highly resistive alloy of FeCrAI type. The conductive wire 13 may be coated with an electrically insulating coating 14. Typically, the coating can be made by ceramic deposition to avoid electrical contact between the conductor wire 13 of the detection cable 10 and the casing 2 containing the fluid when the casing is an electrically conductive material.

Functionally, the electrical insulator 14 may be porous to allow infiltration of the electrically conductive fluid to the core of the detection cable 10 or to disappear in contact with the fluid (for example by chemical reaction) or to become electrical conductor in contact with or near the fluid (for example by transferring heat to the coating 14 from a liquid metal as an electrically conductive fluid), to allow the establishment of a 2010 electrical junction between on the one hand the wire conductor 13 of the detection cable 10, on the other hand the conductive envelope 2 and / or the conductive element 20. The coating 14 can be produced on the conductive wire 13 based on a ceramic on a FeCrAI alloy with a deposit prior to an interface layer 15 based on a metal, for example nickel-based, on the conductive wire 13, to allow the attachment of the ceramic and the absorption of the d differential thermal conditions between the conductive wire and the coating, said expansions resulting in thermal expansion coefficient potentially very different between the conductive wire and the coating.

In the case where the envelope 2 containing the fluid is not electrically conductive, it can not act as a conductive element 20 as detailed below. The detection cable 10 with high resistivity and / or high ohmic resistance per meter is then associated with a conductive element 20 of negligible ohmic resistance (which may take the form, for example, of an electrically conductive wire having a copper core or in aluminium). The conducting wire 13 of the detection cable 10 and the conducting element 20 are preferably deployed side by side along the envelope 2 to be monitored. The electrical insulation 14 of the detection cable 10 prevents electrical contact with the conductive element 20 and therefore with the mass 40, as it would with an electrically conductive envelope 2. In the embodiments described below, the enclosure 2 to be monitored is a pipe carrying an electrically conductive fluid, such as a liquid metal. The pipe measures L meters in length. The detection cable 10 is for example arranged along a generatrix of the pipe and also measures L meters in length. Alternatively, the detection cable 10 can be wound in a coil around the pipe, arranged in a spiral on a flat bottom of the casing to locate a leak in the plane of the bottom along an azimuth and a radial rib or disposed in zig-zag on a pipe to locate a leak on an azimuth. Alternatively, the casing 2 may be an open or closed container in which the electrically conductive fluid is to be stored.

Example of a leak detection on a pipe of length 10 m

With reference to FIGS. 2a, 2b and 7, the system 1 and the method 100 according to a first embodiment of the invention are described below.

With reference to FIGS. 2a and 2b, the detection system 1 comprises:

a detection cable 10 as described above,

the aforementioned electrically conductive element, which may consist at least in part of the envelope 2 when the latter is conducting electricity,

an electric generator 30,

- if necessary a mass 40, and

an instrument 50 for identifying an electrical parameter.

The conductive element 20 is arranged together with the detection cable 10 so that a leakage of electrically conductive fluid from the envelope 2 intended to contain it generates an electrical junction 2010 between the conductive element 20 and a portion of the detection cable 10 at the level of the leak.

The electrical generator 30 has a first terminal 31 connected to a first point of the detection cable 10, preferably at a first end 11 of the detection cable 10, and a second terminal 32 connected to the conductive element 20, preferably at a first end 21 of the conductive element 20. According to the joint arrangement of the detection cable 10 and the conductive element 20, the first end 1 1 of the detection cable 10 is preferably substantially closer to the first end 21 of the conductive element 20 than any other point of said conductive element 20.

The mass 40 can be connected to the second terminal 32 of the electric generator 30 and to the conductive element 20.

The identification instrument 50 is configured and arranged to measure an electrical parameter (current, voltage and / or power) in the electrical circuit comprising the detection cable 10, the conductive element 20 and the electrical generator 30.

With reference to FIG. 7, the electric generator 30 is configured to apply a voltage across the electrical circuit. The identification instrument 50 is configured to monitor an electrical parameter variation, so as to detect, according to a predetermined setpoint, an electrical parameter variation that corresponds to the appearance of a leakage of conductive fluid from the envelope 2.

With reference to FIGS. 2b and 7, the identification instrument 50 is furthermore configured, in the event of the appearance of a leak, to determine 130, as a function of the electrical parameter measurement, the ohmic resistance R1 of the cable of FIG. detection 10 between said first point, preferably its first end 1 1, and the electrical junction 2010 generated by the conductive fluid between the conductive member 20 and the detection cable 10. Therefore, it is possible to deduce 140 the location of the leak. This deduction can be performed by an operator of the system 1 or directly by the identification instrument 50, according to a continuous detection function as illustrated in FIG.

On the graph of FIG. 6, in fact, the function S (x, Ri) e R ⁺ , with Ri e R ⁺ , where x is a binary variable characterizing the state of the system, and in particular the presence or absence of a leak and S takes a value whose dimension is an optionally curvilinear length, the electrical junction 2010 along the detection cable 10. A single function S (x, Ri), optionally calibrated, or self-calibrated as described more below, defines the law to which the system 1 obeys. The measure Ri makes it possible to deduce the abscissa, and therefore the corresponding locality, from the leak. The existence of the function S is related to the presence of a leak. The map S (x, Ri) is a bijection. For every R ^ S (x, Ri) is unique and vice versa.

It is advantageously envisaged to associate the detection cable 10 with a voltage generator with integrated current limiter, as an electric generator 30.

With reference to FIG. 2a, in the idle state, defined by a lack of insulation fault of the conducting wire 13 of the detection cable 10, and therefore to the absence of a leak, the voltage applied to the conductor wire 13 by the voltage generator is V _max (equal to the difference between two electrical potentials, a first applied to the detection cable 10 and a second applied to the conductive element 20). No current flows in the conductor wire 13 of ohmic resistance R; the circuit electrical device comprising the detection cable 10, the conductive element 20, the electrical generator 30 and, if appropriate, the mass 40 is open.

With reference to FIGS. 2a, 2b and 7, a leak occurs at a coast or abscissa L1 of the detection cable 10. In the detection state, defined by the appearance of the leak, the current flowing in the portion L1 of conductive wire 13 of the detection cable 10 takes the intensity l _max . There is no current flowing in the portion L2 of the conductive wire 13 of the detection cable 10. The electrical generator 30 works in limitation 131 intensity (current generator). For this, the voltage V at these terminals is reduced to the value necessary to limit 131 the intensity of the current to l _max .

R _{f is} denoted the ohmic resistance of the conductive fluid generating the electrical junction 2010 between the conductive element 20 and the detection cable 10, and R _t the ohmic resistance of the conductive element 20 between said electrical junction 2010 and the generator. electrical 30. R _f is the ohmic resistance at the contact between the fluid flowing out of the enclosure to monitor and the detection cable 10. By experience or hypothesis, we know that R _f is a very low value before R (order of magnitude 0.1 W for liquid sodium as fluid for example). R _f is neglected. R _t is the ohmic resistance seen by the current of intensity l _max as it passes through the chamber 2 to be monitored to return to the generator 30. By experience, or because the conductive element 20 has a resistivity lower than less than one order of magnitude, preferably at least two orders of magnitude, the resistivity of the resistive metal alloy forming part of the detection cable 10, it is known that R _t is a very small value in front of R (order of magnitude). magnitude 0.005 Qm ¹ , even in the case where the chamber 2 to be monitored is a small tube, for example DN1 "). R _t is neglected.

It is a question of determining the distance Li thanks to the system 1 of detection and location of leakage. The measurement 132 of the voltage V, as an electrical parameter, across the terminals of the electric generator 30 makes it possible to determine the position of the leak. Indeed, the quantities l _max , V, R, L being assumed known or determined as explained below, R _f and R _t being negligible, so we also have V _f and V _t negligible, and by way of:

Ri = Vi / l _max , and

V-i V,

so Ri ~ V / l _max , and

Ri = R / L x L-i,

so Li = Ri / R ^* L, and finally

Li = V / l _max / R ^* L. The resistance R can be known or determined by the choice of conductive material of the detection cable, in particular when this material has an electrical resistivity that is not very dependent on temperature; the initial knowledge of the ohmic resistance R of the system then makes it possible to deduce the location of the leak (possibly by measuring the temperature and taking it into account in the calculation as well). The resistor R may also be known or determined, for example initially after installation of the system 1 and / or regularly following this installation, by implementing the system 1 according to an embodiment described below, so as to overcome any variability of the system 1, and in particular any variability of resistance of the detection cable 10, with respect to the temperature.

According to the invention, the embodiment described above can advantageously be associated with a device 60 for verifying the functionality of the system 1. This association is described below, with reference to FIGS. 3, 4 and 7, at least as regards its differences with the embodiment described above.

According to a first embodiment of the invention and as illustrated in FIGS. 3 and 4, the verification device 60 of the functionality of the system 1 comprises a controlled switch C connected to a second point of the cable 10, preferably at the second end 12 of the detection cable 10, on the other hand to the conductive element 20, preferably to a second end 22 of the conductive element 20. According to the joint arrangement of the cable detection 10 and the conductive element 20, the second end 12 of the detection cable 10 is preferably substantially closer to the second end 22 of the conductive element 20 than any other point of said conductive element 20. The switch C is more particularly controlled by a control system 70 (in absolute terms, it could be driven by an operator). The control system 70 may comprise a relay line 71, a control coil 72, a power supply 73 of the control coil 72 and a control switch 74. A terminal of the power supply 73 can be connected to the control unit 72. conductive element 20, preferably at the second end 22 of the conductive element 20, and the other terminal of the power supply 73 can be connected to the control coil 72, for example via the control switch 74. Control coil 72 is arranged together with switch C to control, by magnetic induction, the opening and closing. In Fig. 3, the control switch 74 is open, and the control coil 72 leaves or holds the switch 61 open, whereas in Fig. 4 the control switch 74 is closed, and the control coil 74 control 72 maintains or leaves the switch closed, respectively. Preferably, the switch C is open in a position not constrained by the coil 72 and is closed by the control coil 72 when it applies a magnetic stress thereto.

In the mode to detect a possible leak, the controlled switch C is open 124. During the scanning periods, the method 100 is implemented as described above.

With reference to FIG. 7, the controlled switch C 61 is regularly closed 121. The closure 121 of the switch C makes it possible to simulate a leak by involving the entire length of the conductive wire 13 of the detection cable 10. The closing of the switch C may for example be performed at a frequency of 1 Hz for a time of the order of 100 ms. In this way, the absence of cut-off on the detection cable 10 is checked every second.

More particularly, with reference to FIGS. 4 and 7, the closure 121 of the switch C causes the circulation of a current of intensity l _max in the circuit. In this case, the ohmic resistance R _t of the conductive element 20 is negligible in relation to R, the ohmic resistance of the entire detection cable 10. Also, the voltage drop V _t across the conductive element 20 is negligible. The measurement 122 of the electrical parameter by the identification instrument therefore corresponds to a measurement of the voltage drop across the electrical generator 30. This so-called calibration voltage 122 is denoted V _cai .

If the determination of the ohmic resistance R1 of the detection cable between said first point and said electrical junction in case of occurrence of a leak is preferably carried out before a next closing of the controlled switch C 61, the leak will be all of even detected as said voltage drop at the terminals of the electric generator 30 if the controlled switch C is closed 61 at the appearance of the leak. The system 1 is therefore not rendered temporarily inoperative because of the addition of the control device 60.

It is proposed to use this periodic closure operation 121 to measure the ohmic resistance R of the entire sensing cable. The intensity l _max of the current is known. The voltage _Vcai is measured 122. It deduces and stores 123 the ohmic resistance R of the entire detection cable 10: R = V _cai / l _max , in good approximation. Preferably, the system according to the second aspect of the invention is set up so that the update rate of the value of R is much greater than the thermal time constant of the installation. Thus, the temperature variations on the installation have no impact on the measurement related to the occurrence of a leak and therefore without impact on its location which remains accurate. The system 1 according to the second of Embodiment of the invention thus functions even with a thermally sensitive alloy.

The value of the ohmic resistance R of the entire detection cable 10 is stored 123, for example in the identification instrument 50. It can be updated at each closing 121 of the controlled switch C 61, ie every second. The ohmic resistance R of the detection cable 10 as stored 123 naturally integrates the influence of the temperature on the resistivity of the conductive wire 13 of the detection cable 10. This is therefore a self-calibration operation which makes it possible in particular to avoid having to measure or control the ohmic resistance R of the conducting wire of the detection cable 10, in particular during its installation. In particular, the continuous detection function S (x, Ri) is updated, for example by and in the identification instrument 50, each time the value of the ohmic resistance R of the entire detection cable 10 is updated.

Therefore, the determination 130 of the ohmic resistance R1 of the detection cable 10 between its first end 11 and the electrical junction 2010 generated in the event of leakage of the conductive fluid may advantageously be a function of the ohmic resistance R of the detection cable 10 since its first end 1 1 to its second end 12 as recently stored 123, for example using the identification instrument 50:

Li = V / l _max / R ^* L, in good approximation.

This way of proceeding avoids an operator having to carry out any calibration of the system 1 during installation and commissioning. Moreover, the system 1 is self-calibrating continuously. The influence of external parameters such as temperature, or even a high humidity, is also taken into account with a refresh rate potentially of several orders of magnitude greater than the kinetics of variations in the electrical resistivity of the conducting wire 13 of the detection cable. 10.

The time scales associated with the leak detection system 1 largely allow this mode of operation to be used. Detection is provided at a frequency of 1 Hz and for a closing time substantially equal to 100 ms, in the example given, which therefore leaves a scanning time substantially equal to 900 ms, ie for substantially 90% of the time.

In this way also, during the installation, it is possible to cut sufficient lengths of cable necessary for the surveillance of an enclosure of any size, without constraint compared to a system operating on the basis of standardized cable lengths . The invention is not limited to the previously described embodiments and extends to all the embodiments covered by the claims.

For example, a leak detection and localization system according to an embodiment of the first aspect of the invention is shown in FIGS. 8 and 9. The system illustrated in these figures is equipped with a device for verifying its functionality. which is a variant to that shown in Figures 3 and 4. The verification device according to this variant is more particularly illustrated in the state of rest in Figure 8 and in the active state in Figure 9.

This variant is described below only in that it has different with the verification device as described above with reference to FIGS. 3 and 4. The same functions are performed and the same advantages are achieved by the verification device illustrated in Figures 8 and 9, only by the verification device shown in Figures 3 and 4.

According to this variant, the relay coil 72 is no longer connected to its power supply 73 via the electrically conductive element 20. In fact, the relay coil 72 is connected directly to the edge of the power supply 73 via only the switch 74. The coil 72, the power supply 73 and the switch 74 a circuit different and distinct from the circuit formed by the detection and locating system 1, the controlled switch C 61 and the relay line 71. The coil 72 is always arranged functionally with respect to the controlled switch C 61, so as to be able to control it. The control of the controlled switch C by the coil 72 is identical to that described above.

Claims

A leak detection and localization system (1) of an electrically conductive fluid from an envelope (2) for containing it, comprising:

a detection cable (10) intended to be arranged in conjunction with the envelope (2) and comprising at least one conductive wire (13) and an electrical insulator (14), such as a coating, on at least a part of the conductive thread,

an electrically conductive element (20) arranged in conjunction with the sensor cable (10),

the electrical insulator (14) being configured to electrically isolate the conductive wire (13) from the conductive element (20) in the absence of conductive fluid and to allow electrical connection (2010) between the conductive wire (13) and the conductive element (20) in the presence of conductive fluid, so that a leakage of conductive fluid from the envelope (2) generates said electrical junction (2010) between the sensor cable (10) and the conductive element (20). ) at the level of the leak,

an electrical generator (30) configured to be electrically connected firstly to a first point, preferably at a first end (1 1), of the detection cable (10), and secondly to the conductive element ( 20), preferably at a first end (21) of the conductive member (20), and

an instrument for identifying an electrical parameter (50) configured to identify the establishment of said electrical junction,

the system being characterized in that it further comprises a verification device (60) for the functionality of the system (1), the verification device (60) comprising a piloted switch (61) connected on the one hand to a second stitch, preferably at a second end (12), of the detecting cable (10), on the other hand to the conductive element (20), preferably at a second end (22) of the conductive element (20) , so as to be able to measure the ohmic resistance of the conducting wire of the detection cable when the switch (61) is closed.

2. System (1) according to the preceding claim, comprising a single detection cable (10) arranged in conjunction with said casing (2) so as to extend vis-à-vis the entire part of the periphery of the envelope (2) where a leak is likely to appear, or even vis-à-vis at least a whole length of the outer perimeter of the casing (2).

3. System (1) according to any one of the preceding claims, wherein the conductive wire (13) of the detection cable (10) is based on a metal alloy chosen so that the conductor wire (13) of the cable detection device (10) has a linear ohmic resistance greater than 0.1 W / m, preferably substantially equal to 0.95 W / m.

4. System (1) according to the preceding claim, wherein the metal alloy is chosen so that the conductive wire (13) of the detection cable (10) has a linear ohmic resistance greater than 1.5 W / m, by example substantially equal to 1.85 W / m.

5. System (1) according to any one of the two preceding claims, wherein the metal alloy has a resistivity greater than 6.10 ⁷ W.GTI, for example substantially equal to 7.5.10 ⁷ W.GTI, preferably greater than 1, 10 ⁶ W.GTI, or even greater than 1, 2.10 ⁶ W.GTI, for example substantially equal to 1.45.10 ⁶ W.GTI.

6. System (1) according to any one of the three preceding claims, wherein the metal alloy is chosen from:

a preferably austenitic stainless steel, for example 304 steel or 316 steel.

7. System (1) according to any one of the preceding claims, wherein the conductor wire (13) of the detection cable (10) has an ohmic resistance and / or is based on a metal alloy having a resistivity such (s) that a splicing operation in one or two places of the detection cable (10) induces a linear ohmic resistance variation of the conducting wire (13) less than 20%, preferably less than 5%, for example substantially equal at 1%, with respect to the ohmic resistance R of the uncoupled detection cable (10).

8. System (1) according to any one of the preceding claims, wherein the electrical insulator (14) is based on ceramics.

9. System (1) according to any one of the preceding claims, wherein the electrical insulator (14) covers the conductive wire (13) at regular intervals, for example by forming beads strung on the conductor wire of the detection cable. (10).

10. System (1) according to any one of the preceding claims, wherein the electrical insulator (14) covers the conductive wire (13) in one of the following ways: one side of the conductor wire and any side of the conductive thread.

1 1. System (1) according to any one of the preceding claims, wherein, to allow the electrical connection (2010) between the detection cable (10) and the conductive element (20) at the level of the leak, the electrical insulation (14) is porous to allow the conductive fluid to infiltrate from side to side.

12. System (1) according to any one of the preceding claims, wherein, to allow the electrical connection (2010) the detection cable (10) and the conductive element (20) at the leak, the insulation electrical (14) is able to fade in contact with the conductive fluid, for example by chemical reaction.

13. System (1) according to any one of the preceding claims, wherein, to allow the electrical connection (2010) the detection cable (10) and the conductive element (20) at the leak, the insulation electrical (14) is adapted to become electrical conductor in contact with or near the conductive fluid, for example under the effect of the heat released by the conductive fluid.

14. System (1) according to any one of the preceding claims, wherein the detection cable (10) further comprises at least one interface layer (15) based on a material preferably metal, for example to Nickel base, between the conductive wire (13) and the electrical insulator (14).

15. System (1) according to any one of the preceding claims, wherein the electrical generator (30) is a voltage generator with integrated current limiter and the identification instrument (50) is a voltmeter connected in parallel to the generator terminals (30).

16. System (1) according to any one of the preceding claims, wherein the conductive element (20) comprises at least one conductive wire.

17. System (1) according to any one of the preceding claims, wherein the conductive element (20) comprises at least a portion of the casing (2) when the casing is electrically conductive.

18. System (1) according to any one of the preceding claims, wherein the conductive element (20) is based on the same electrically conductive material, metal or alloy as the lead wire of the detection cable (10). and has an electrical resistance section of one or more orders of magnitude smaller than that of the detection cable (10), so that its linear ohmic resistance is significantly lower than that of the detection cable (10).

19. A method for detecting and locating leakage (100) of an electrically conductive fluid from an envelope (2) for containing it using a system (1) according to any one of claims 1 to 18, comprising the following steps:

- applying (1 10), using the electrical generator (30), a voltage on the one hand at a first point, preferably at a first end (11), the detection cable (10), on the other hand to the conductive element (20), preferably at a first end (21) of the conductive element (20),

- monitor (120), using the identification instrument (50), a variation of the electrical parameter measured by the identification instrument, so as to identify, according to a predetermined setpoint, a variation corresponding to the establishment of an electrical junction (2010) between the detection cable (10) and the conductive element (20) and thus to detect the occurrence of a conductive fluid leak from the envelope

(2), and

in case of occurrence of a leak, determining (130), as a function of the measurement of the electrical parameter, the ohmic resistance R1 of the detection cable (10) between said first point and said electrical junction (2010),

to deduce (140) the location of the leak,

the system (1) further comprising a verification device (60) for the functionality of the system (1), the verification device (60) comprising a controlled switch (61) connected to a second point, preferably at a second end (12), the detection cable (10) and the conductive element (20), preferably at a second end (22) of the conductive element (20), the monitoring (120) of the variation of the electrical parameter further comprises, at substantially regular time intervals:

- control (121) the closing of the switch (61),

measuring (122), using the identification instrument (50), the electrical parameter in the electrical circuit comprising the detection cable (10), preferably from its first end (11) to its second end (12), the conductive element (20), the electric generator (30), the mass (40) and the switch (61),

- deduce according to the result of the measurement (122) and store (123), for example with the aid of the identification instrument (50), the ohmic resistance R of the detection cable (10), preferably from its first end (11) to its second end (12), and

- control (124) the opening of the switch (61),

so that, in case of occurrence of a leak after the opening of the switch (61) and preferably before a next closing of the switch (61), the determination (130) of the ohmic resistance R1 of the detection cable (10) between said first point and said electrical junction (2010) is a function of the ohmic resistance R of the detection cable (10), preferably from its first end (11) to its second end (12) as stored (123).

20. Method (100) according to the preceding claim, wherein, the electric generator (30) being a voltage generator with integrated current limiter and the identification instrument (50) being a voltmeter connected in parallel to the generator terminals. ,

the application (110) of an electrical voltage comprises the application, by means of the voltage generator, of a first electrical potential to the conducting wire (13) of the detection cable (10) and a second potential electric, different from the first electrical potential, to the conductive element (20),

the monitoring (120) of the variation of the electrical parameter comprises the monitoring of a voltage variation across the voltage generator using the voltmeter, and in the event of the occurrence of a leak, the determination (130) of said ohmic resistor R1 comprises:

limit (131), using the voltage generator, the intensity of the electric current to a predetermined value Imax, and

measuring (132) the voltage at the terminals of the voltage generator using the voltmeter at said limited intensity, to deduce said ohmic resistance R1.

A method (100) according to any one of claims 19 and 20, wherein determining (130) said ohmic resistance R1 includes: neglecting the ohmic resistance Rf of the conductive fluid generating the electrical junction (2010) between the detection (10) and the conductive element (20), neglecting the ohmic resistance Rt of the conductive element (20) between said electrical junction (2010) and the electrical generator (30), in front of the ohmic resistance R1 of the detection cable (10) between said first point and said electrical junction (2010).

22. Method (100) according to any one of claims 19 to 21, wherein the control (121, 124) of the switch (61) is designed to keep it closed for a time substantially equal to 100 ms per time interval substantially equal to 1 s.