DEVICE FOR MEASURING A RECEIVED DOSE OF RADIATION BY METHOD OF REFLECTOMETRY OR TRANSFEROMETRY

Description

[0001] The invention relates to the field of nuclear installations which are subjected to irradiation, more generally radiological attacks which can cause damage to structures. The invention relates more generally to any application associated with an environment in which a measurement of irradiation dose is of interest, in particular the space or medical fields.

[0002] The invention relates more specifically to the prevention of failure of equipment subjected to irradiation and relates to a device for measuring the dose of radiation received based on the principle of reflectometry or transferometry.

[0003] Knowledge of the radiation dose absorbed by equipment subjected to irradiation is an important factor for the maintenance and failure prevention of this equipment. In particular, in the field of nuclear installations, preventing equipment malfunction is essential to ensure operator safety.

[0004] Known solutions for measuring radiation doses are most often based on active or passive dosimeters placed locally at certain selected locations on the equipment to be monitored or on individuals. These solutions have the disadvantage of only being able to take measurements at a limited number of points and of requiring as many devices as there are points to be monitored. Similarly, measurements cannot be taken continuously.

[0005] Patent application WO2006 / 104046 describes an example of such a dosimeter for radiotherapy applications.

[0006] Furthermore, reflectometry or transferometry techniques are known for detecting hot spots or temperature variations as proposed in patent applications WO 2006 / 104046 and FR 3042863. These techniques consist of injecting a signal into a cable and measuring the reflected or propagated signal in order to analyze it and detect impedance discontinuities associated with the impact of these temperature variations on the cable. Patent application FR 2987450 relates to a method for measuring the aging of at least one electrical cable and applies in particular to the fields of reflectometry and cable diagnostics. As for application FR 3102562, it describes a device for monitoring the condition of a cable, more particularly the degradation of a cable based on reflectometry.

[0007] The invention proposes to use reflectometry or transferometry techniques to design a device for detecting radiation dose from a cable.

[0008] The main advantage of such a device is that it can be deployed inside a facility to cover a larger area than can be covered with conventional dosimeters. Thus, the invention makes it possible to detect a dose of irradiation with better spatial resolution than prior art solutions.

[0009] Furthermore, the invention can be implemented in the form of a smart fabric that can cover a surface of an object to detect a dose of irradiation received by this object.

[0010] The invention thus allows real-time knowledge at any chosen moment of the level of radiation dose received in a much greater number of simultaneous positions than with conventional dosimeters.

[0011] The invention relates to a device for measuring the dose of radiation received, comprising a cable composed of at least one material sensitive to a dose of radiation received in at least one predetermined value range and measuring equipment connected to the cable and configured to carry out a measurement, by reflectometry or transferometry, of a physical quantity characteristic of the cable, a database comprising a set of pairs of values ​​associating a value of the physical quantity with a value of the dose of radiation received and a processing unit configured to determine a measurement of the dose of radiation received by the cable from the measurement of the physical quantity and by interrogating the database. Such a device is defined in claim 1.

[0012] According to a particular aspect of the invention, the measuring equipment is configured to inject a test signal at a point on the cable and measure said propagated or reflected signal at a point on the cable and determine a measurement of said physical quantity from the measurement of the signal.

[0013] According to a particular aspect of the invention, the physical quantity is an amplitude of a mismatch peak measured on the signal or a reflection coefficient or a characteristic impedance.

[0014] According to a particular aspect of the invention, the physical quantity is measured at a plurality of points on the cable and the radiation dose measurement is determined for each of these points.

[0015] According to a particular aspect of the invention, the processing unit is configured to carry out an interpolation of the values ​​of the database from the measurement of the physical quantity to deduce the measurement of radiation dose.

[0016] According to a particular aspect of the invention, the database comprises several sets of pairs of values ​​for different types of materials and / or different types of radiation.

[0017] According to a particular aspect of the invention, the cable is composed of several dielectrics separated by shields, each dielectric having a sensitivity to radiation in different radiation dose ranges, the measuring equipment being configured to carry out a measurement of the physical quantity for each dielectric.

[0018] According to a particular aspect of the invention, the cable has a coaxial structure and is composed of several coaxial dielectrics separated by shields.

[0019] According to a particular aspect of the invention, the cable has a parallel structure and is composed of several coaxial strands each composed of a central core, a dielectric and a shield.

[0020] According to a particular aspect of the invention, the cable has a parallel structure and is composed of several twisted pairs, each surrounded by a dielectric and a shield.

[0021] According to a particular aspect of the invention, the device further comprises a switching matrix for connecting the measuring equipment to the different dielectrics of the cable.

[0022] The invention also relates to a smart fabric comprising a radiation dose measuring device according to the invention in which the cable is a conductive thread woven to make the fabric.

[0023] The invention, as defined in claim 13, also relates to a method for calibrating a radiation dose measuring device according to the invention comprising the steps of: i. Irradiate at least a portion of the cable with a predetermined radiation dose, ii. Carry out a measurement, by reflectometry or transferometry, of a physical quantity characteristic of the cable, iii. Save in a database the pair of radiation dose values ​​and associated physical quantity, iv. Iterate the previous steps for different radiation doses.

[0024] Other features and advantages of the present invention will become more apparent upon reading the following description in relation to the following appended drawings. [ Fig. 1 ] there figure 1 represents an example of a state-of-the-art reflectometry device, [ Fig. 2 ] there figure 2 represents an example of a time domain reflectogram obtained using the device of the figure 1 , [ Fig. 3 ] there figure 3 represents a time diagram illustrating the general principle of transferometry, [ Fig. 4 ] there figure 4 represents a diagram of a radiation dose detection device according to one embodiment of the invention, [ Fig. 5 ] there figure 5 represents several temporal reflectograms obtained using a device according to the invention to characterize a dose of radiation received, [ Fig.6 ] represents an example of interpolation of cumulative radiation dose values ​​based on a characteristic impedance measurement, [ Fig. 7 ] represents a first variant embodiment of a cable used to produce a device according to the invention, [ Fig. 8 ] represents a second variant embodiment of a cable used to produce a device according to the invention, [ Fig. 9 ] represents a third variant embodiment of a cable used to produce a device according to the invention, [ Fig. 10 ] represents an exemplary embodiment of the device according to the invention.

[0025] We first recall some notions relating to the methods of reflectometry and transferometry applied to the detection of defects in a cable.

[0026] According to a known principle, the so-called reflectometry or transferometry methods are used to detect and / or locate electrical or mechanical faults which cause discontinuities or impedance breaks in a cable.

[0027] Reflectometry methods use a principle similar to that of radar: an electrical signal, often high frequency or broadband, is injected into one or more locations in the cable to be tested. The signal propagates through the cable or network and returns part of its energy when it encounters an electrical discontinuity. An electrical discontinuity can result, for example, from a connection, the end of the cable, or more generally from a breakdown in the signal propagation conditions in the cable. It most often results from a fault that locally modifies the characteristic impedance of the cable by causing a discontinuity in its linear parameters.

[0028] Analysis of the signals returned to the injection point makes it possible to deduce information on the presence and location of these discontinuities, and therefore any potential faults. An analysis in the time or frequency domain is usually carried out. These methods are designated by the acronyms TDR, which comes from the English expression "Time Domain Reflectometry" and FDR, which comes from the English expression "Frequency Domain Reflectometry".

[0029] These methods are generally used to detect and locate local cable damage, for example damage affecting the cable sheath.

[0030] There figure 1 schematically illustrates, as a reminder, the operating principle of a diagnostic method by reflectometry applied to a transmission line L presenting a DNF fault, for example a non-clear fault. The example described below corresponds to a time domain reflectometry method.

[0031] A reference signal S, also called incident signal, is injected into the transmission line at a point P. The reflected signal R is measured at the same point P (or at another point on the line). This signal propagates in the line and encounters, during its propagation, a first impedance discontinuity at the input of the DNF fault. The signal is reflected on this discontinuity with a reflection coefficient Γ 1 . If the characteristic impedance Z c 2 in the area of ​​the non-clear fault DNF is lower than the characteristic impedance Z c 1 before the appearance of the defect, then the reflection coefficient Γ 1 is negative and results in a negative amplitude peak in the reflected signal R. In the opposite case, the reflection coefficient Γ 1 is positive and results in a positive amplitude peak in the reflected signal R.

[0032] The transmitted part of the incident signal S continues to propagate in the line beyond the fault (part T on the figure 1 ) and then encounters a second impedance discontinuity creating a second reflection of the incident signal with a reflection coefficient Γ 2 of opposite sign to the first reflection coefficient Γ 1 . If Γ 1 < 0 then Γ 2 > 0. If Γ 1 > 0 then Γ 2 < 0.

[0033] Thus, by observing the reflected signal R, the signature of the non-clear defect DNF is characterized by two successive peaks of inverted signs as shown in figure 2 .

[0034] There figure 2 represents a time domain reflectogram which corresponds either directly to the measurement of the reflected signal R, or to the cross-correlation between the reflected signal R and the signal injected into the cable S.

[0035] In the case where the injected reference signal is a time pulse, which corresponds to the case of a time domain reflectometry method, the reflectogram can correspond directly to the measurement of the reflected signal R. In the case where the injected reference signal is a more complex signal, for example for methods of the MCTDR (Multi Carrier Time Domain Reflectometry) or OMTDR (Orthogonal Multi tone Time Domain Reflectometry) type, then the reflectogram is obtained by inter-correlating the reflected signal R and the injected signal S.

[0036] On the figure 2 , two reflectograms 201, 202 are shown corresponding to two different pulse durations for the signal injected into the cable or in other words to two different frequencies. Curve 201 corresponds to a pulse duration 2.ΔT much greater than the time taken for the signal to cross the non-clear fault DNF. The length of the fault being noted Ld, this duration is equal to Ld / V, with V the speed of propagation of the signal in the cable. Curve 202 corresponds to a pulse duration 2.ΔT much less than the time taken for the signal to cross the non-clear fault DNF.

[0037] In both cases, the signature 203 of the non-clear defect, in the reflectogram, is always composed of the succession of a first peak and a second peak whose signs are reversed.

[0038] The distance between the two peaks represents the length of the non-clear defect and their amplitude represents the severity of the non-clear defect. Indeed, the greater the variation in the characteristic impedance, the greater the amplitude of the non-clear defect signature in the reflectogram.

[0039] The higher the signal frequency, the greater the accuracy in estimating the defect length as can be identified in the figure 2 .

[0040] As is known in the field of reflectometry diagnostic methods, the position of the non-clear fault on the cable, in other words its distance from the signal injection point P, can be directly obtained from the measurement, on the time domain reflectogram of the figure 2 , of the duration t DNF between the first amplitude peak noted on the reflectogram (at the abscissa 0.5 in the example of the figure 2 ) and the amplitude peak 203 corresponding to the signature of the non-clear defect.

[0041] Various known methods are possible to determine the position of DNF. A first method consists of applying the relationship between distance and time: d DNF = Vt DNF / 2 where V is the speed of propagation of the signal in the cable. Another possible method consists of applying a proportionality relationship of the type d DNF / t DNF = L / t 0 where L is the length of the cable and t 0 is the duration, measured on the reflectogram, between the amplitude peak corresponding to the impedance discontinuity at the injection point and the amplitude peak corresponding to the reflection of the signal on the end of the cable.

[0042] Transferometry methods exploit not the part of the signal reflected on an impedance discontinuity but the part of the signal transmitted after this impedance discontinuity. Thus, a transferometry test consists of measuring the signal propagated at another point in the cable, distant from the signal injection point. For example, the measurement is carried out at the opposite end of the cable from the signal injection.

[0043] A transferometry test consists of comparing the measurement taken with a reference obtained at a previous moment, for example corresponding to a new or healthy state of the cable.

[0044] There figure 3 represents, on a diagram, an example of signals measured after their propagation between two distant point devices of a cable. The injected signal is a time slot. Signal 301 corresponds to a reference obtained for a healthy or undegraded state of the cable. Signals 302, 303, 304 are obtained for different levels of degradation of the cable.

[0045] A transferometry test consists, for example, of calculating the difference between the maximum of the signal peak obtained respectively for the current measurement and for the reference. As can be seen in the figure 3 , the more the cable is degraded, the more the signal peak is attenuated. The transferometry test can take into account other characteristics of the signal, such as the width of the peak at a given amplitude level, or other more complex criteria. The comparison is based in particular on the attenuation or dispersion of the signal. In all cases, one objective of the transferometry test is to compare the shape of the signals obtained at two different times in order to detect a degradation of the cable between these two times. The comparison method is for example based on a least squares method or on a correlation between the two signals in order to evaluate the differences or similarities between the two measurements. The reference measurement 301 can also be obtained by simulation from a modeling of the cable parameters.

[0046] Reflectometry and transferometry methods are generally used to detect faults linked to local damage on a cable.

[0047] The present invention proposes to use these methods to design a new device for measuring the dose of radiation received.

[0048] The impact of irradiation on the insulators used to make cables is known and described in particular in publications [1], [2] and [3]. This impact results in radiation-induced aging which depends on the material (dielectric) used to manufacture the cable. Depending on the material chosen, its sensitivity to radiation differs. Indeed, some materials are sensitive to a very low cumulative dose of radiation while others are resistant up to a higher dose. The maximum dose that can be tolerated before the occurrence of a short circuit is also dependent on the physical properties of the material.

[0049] In installations that require protection from radiation (for example, nuclear power plants), electrical cables are generally designed with the most radiation-resistant materials in order to limit their aging as much as possible in relation to the cumulative radiation dose.

[0050] The invention proposes, on the contrary, to design a radiation dose detection device from a cable designed using radiation-sensitive material in order to be able to characterize the level of dose received.

[0051] To this end, it is proposed to use reflectometry and transferometry techniques to detect impedance discontinuities that impact the cable due to its exposure to radiation. Indeed, certain physical parameters of a cable are directly impacted by radiation and can generate an impedance discontinuity in the same way as physical degradation.

[0052] This is particularly mentioned in publications [4] and [5] which describe the impact of gamma radiation on the physical parameters of a cable, in particular on the real and complex permittivity.

[0053] Reflectometry (or transferometry) allows a cable to be characterized by its RLCG parameters. However, permittivity is involved in the definition of these parameters, in particular C and G but also through the definition of the characteristic impedance and the speed of the wave propagating in the cable, but also more generally in the definition of any physical parameter dependent on C and G such as the delta tangent or attenuation.

[0054] Thus, irradiation of the cable has a direct effect on a reflectogram (or transferogram) in that it induces a local modification of the characteristic impedance of the cable or of any other parameter dependent on C and G.

[0055] Based on this observation, the invention proposes to design a device whose function is to characterize the dose of radiation received by a cable placed in an environment subject to radiation, by carrying out a measurement by reflectometry or transferometry on the cable.

[0056] There figure 4 represents a general diagram of a device according to the invention.

[0057] It comprises a CBL cable designed in at least one radiation-sensitive material. Examples of such a cable will be described in more detail later. The device 400 according to the invention comprises the equipment necessary to carry out a reflectometry test or a transferometry test. In other words, it comprises a reference signal generator GEN and an INJ equipment for injecting the reference signal at a first point of the cable (for example one end). The INJ injection equipment notably comprises a digital-to-analog converter and a coupler. The device also comprises an MES equipment for measuring the signal reflected or propagated in the cable, capable of carrying out a measurement at the same injection point of the cable or at another point (for example the opposite end of the cable). The MES measurement equipment notably comprises a coupler for acquiring the measurement and an analog-to-digital converter for digitizing the measurement.

[0058] The coupler may be a directional coupler with a capacitive or inductive effect or a galvanic connection. The coupler may be achieved by physical connectors that connect the signal generator to the cable or by contactless means, for example by using a metal cylinder whose internal diameter is substantially equal to the external diameter of the cable and which produces a capacitive coupling effect with the cable.

[0059] The device 400 also comprises a processing unit UT configured to generate a time domain reflectogram or a time domain diagram characteristic of a transferometry measurement. For example, the processing unit comprises a filtering module FIL and a processing module TR to generate a physical quantity characteristic of the measurement as a function of the position on the cable. For example, this physical quantity corresponds to a reflection coefficient of the signal at a point on the cable or to a characteristic impedance at a point on the cable or simply to the amplitude of the signal measured by the measuring equipment MES calculated on a chosen peak characteristic of an impedance discontinuity.

[0060] The device 400 also comprises a BDM database in which reference pairs are saved associating on the one hand a cumulative radiation dose value and on the other hand a value of the physical quantity measured or calculated by the processing unit UT. These reference pairs are saved for a plurality of cumulative dose values ​​and, for example, for different types of radiation likely to impact the cable but also for different types of material of which the cable is composed. The materials are, for example, polymers of different types including in particular Ethylene Propylene, Ethylene Vinyl Acetate, Polyvinyl Chloride, Polytetrafluoroethylene or Polyethylene.

[0061] The radiation is, for example, of the gamma or beta type, it can be neutrons or any other type of radiation capable of significantly modifying the electrical parameters of the cable.

[0062] The information contained in the BDM database can be obtained via a calibration phase which will be described in detail later. It allows the construction of a curve 401 of the cumulative radiation dose as a function of the physical quantity characteristic of an impedance discontinuity on the cable, for example a characteristic impedance.

[0063] Alternatively, the information contained in the BDM database can be obtained from a theoretical model of the evolution of the cumulative radiation dose as a function of the physical quantity.

[0064] The device 400 according to the invention also comprises a module for calculating the dose of radiation received CDR by the cable CBL at a given point as a function of the measurement provided by the processing unit UT and the information contained in the database BDM.

[0065] This CDR module is for example implemented in the UT processing unit or in a separate computing unit capable of being interfaced with the UT processing unit and the BDM database.

[0066] The cumulative radiation dose value calculated by the CDR module can be provided to a display or any other human-machine interface.

[0067] The cumulative radiation dose value is, for example, calculated by interpolating the values ​​contained in the BDM database from the value provided by the UT processing unit.

[0068] There figure 5 represents an example of time domain reflectograms obtained by irradiating a cable over a zone Z, for example by placing a portion of this cable in an irradiator. The different curves are obtained for different values ​​of gamma radiation dose received by the cable. In this example, the cable consists of a twisted pair sheathed and screened with Ethylene-vinyl acetate (EVA) insulation.

[0069] The curves of the figure 5 are obtained by performing time domain reflectometry measurements. The impact of gamma radiation is observable via peaks 501 and 502 corresponding respectively to the beginning and end of the irradiated zone.

[0070] These peaks correspond to impedance discontinuities generated by irradiation. The amplitude of peaks 501, 502 depends directly on the dose of radiation received.

[0071] Thus, by analyzing these reflectograms it is possible to deduce an estimate of the radiation dose received.

[0072] More precisely, from the measured reflectograms, a physical quantity characteristic of the impedance discontinuity generated locally by the radiation is determined. This physical quantity can be directly the amplitude of peak 501 or peak 502 measured as a function of the position of this discontinuity on the cable.

[0073] The physical quantity can also be a characteristic impedance obtained from the reflectogram, for example by applying the teachings of the Applicant's French patent application No. 3025320 or French patent application No. 3034203 or any other suitable method.

[0074] More generally, any physical quantity derivable from a reflectogram or a measurement obtained by transferometry can be used.

[0075] The BDM database is generated in advance via a calibration process which consists of irradiating an area of ​​a cable identical to the CBL cable for several radiation dose values ​​and for different types of radiation and measuring each time the aforementioned physical quantity from a reflectometry or transferometry measurement carried out on the cable.

[0076] This calibration process can be performed for different types of cables made with different materials.

[0077] When the device 400 according to the invention is used as a radiation dose sensor, the radiation dose calculation module CDR performs an interpolation of the values ​​of the BDM database from the measurement provided by the processing module TR.

[0078] There figure 6 represents an example of interpolation performed by the CDR module.

[0079] There figure 6 represents different values ​​of radiation doses as a function of a characteristic impedance Zc, corresponding to the pairs of values ​​saved in the database. From these points, a linear interpolation is carried out to obtain, for any value of the characteristic impedance Zc, the corresponding value of the dose.

[0080] More generally, interpolation is not necessarily linear; it can be polynomial or carried out using a more complex interpolation function. The interpolation chosen depends in particular on the type of material from which the cable is made and its sensitivity to radiation.

[0081] The radiation dose is calculated by the CDR module by applying the interpolated function to the value provided by the TR processing module.

[0082] The radiation dose received can be calculated at different points along the cable.

[0083] Different embodiments of CBL cable architecture are possible. According to a first embodiment, the CBL cable is a simple cable which has a single possible path for the outward and return flow of the electric current. For example, it is a standard coaxial cable or a twisted pair cable. However, a disadvantage of this type of cable is that it is based on only a single dielectric material which potentially limits the measurement range of the radiation dose received. Indeed, each dielectric material is sensitive to a type of radiation within a predetermined range of values.

[0084] In order to extend the measurement range, other embodiments are envisaged with more complex cable structures. The common idea in all these embodiments is the use of a series of materials chosen to have good sensitivity to the increasing radiation dose, such as different dielectrics. This makes it easier to obtain a cable that can be used over a wide range of cumulative doses, which would be difficult or even impossible with a single type of material.

[0085] Each dielectric is optimized to provide good sensitivity within a given cumulative dose range and to a given type of radiation. By choosing materials wisely, we can have dose ranges that complement each other, ultimately resulting in a wide coverage range.

[0086] THE figures 7 , 8 et 9 describe three particular embodiments of CBL cable architecture. These three architectures have in common the fact that they include several different dielectrics, each dielectric having a sensitivity to radiation in different ranges of values.

[0087] An advantage of these particular architectures is that they allow the production of a cable with sensitivity to cumulative radiation doses over a wide range of values, which is more difficult to achieve with a single material.

[0088] There figure 7 illustrates the section of a CBL 1 cable with a coaxial structure composed of a central core 701 and surrounded by several different dielectrics 702, 703, 704, 705 separated from each other by shields 710, 720, 730, 740.

[0089] Advantageously, the different dielectrics are chosen so that each of the dielectrics has a sensitivity to radiation in a different range of values. For example, the different dielectrics are designed by choosing a basic insulator and gradually increasing its antioxidant content to design each dielectric layer.

[0090] Preferably, the ranges of values ​​are increasing in the direction from the core 701 towards the outside of the cable. Alternatively, the ranges of values ​​can also be decreasing in the direction from the core 701 towards the outside of the cable.

[0091] In other words, in one embodiment of the invention, the dielectric 702 is chosen to be sensitive to doses of radiation included in the interval [a;b], the dielectric 703 is chosen to be sensitive to doses of radiation included in the interval [b;c], the dielectric 704 is chosen to be sensitive to doses of radiation included in the interval [c;d], the dielectric 705 is chosen to be sensitive to doses of radiation included in the interval [d;e], with a <b<c<d<e.

[0092] There figure 8 represents another alternative embodiment of a CBL 2 cable having a parallel structure. The CBL 2 cable comprises several coaxial strands 801, 802, each being composed of a central core 810, 820, a dielectric 811, 821 and surrounded by an insulating shield 812, 822.

[0093] The different dielectrics 811, 821 are chosen in the same way as for the CBL 1 cable of the figure 7 , that is, they are each sensitive to different ranges of radiation dose values.

[0094] There figure 9 represents yet another variant embodiment of a CBL 3 cable also having a parallel structure but the coaxial strands of the figure 8 are replaced by twisted pairs surrounded by a different dielectric for each pair.

[0095] Without departing from the scope of the invention, other cable architectures are conceivable to the extent that the designed cable comprises several dielectrics, each having different sensitivities to radiation.

[0096] In particular, another possible cable architecture is to use twin-wire lines consisting of two parallel conductors instead of twisted pairs.

[0097] The sensitivity of a dielectric to radiation is measured based on the impact of this radiation on the physical quantity measured from the reflectogram or the measurement obtained by transferometry.

[0098] A dielectric is sensitive to a dose of radiation as soon as this dose generates an impedance discontinuity which modifies the value of the physical quantity, for example the characteristic impedance, compared to a reference value obtained for a cable not subjected to radiation.

[0099] Reflectometry or transferometry tests are carried out by injecting a signal between the core 701 of the CBL1 cable or one of the strands of the CBL2 cable and one of the shields or between two different shields. When a cable of the type described in figure 7 Or figure 8 is used, several tests leading to several measurements are carried out for each of the dielectrics.

[0100] There figure 10 represents a particular example of implementation of the device according to the invention when the cable has a complex architecture of the type of that of the figure 8 .

[0101] In this case, the reflectometry test is implemented by means of signal switching matrices MC based for example on electromagnetic relays making it possible to direct the injection of a reflectometry signal towards the correct pair of conductors. The switching matrix is ​​connected by its inputs to the reflectometer R, that is to say to the device comprising on the one hand means for injecting a signal into a cable and on the other hand means for measuring the back-propagated signal. On the other hand, each output of the switching matrix is ​​connected to one of the coaxial strands 801, 802 of the cable.

[0102] For single cables, the injection of the reflectometry signal is carried out between the two electrical conductors of a twisted pair or between the core and the shielding of a coaxial cable.

[0103] For complex cables, the signal injection is for example carried out between two electrical conductors of the same basic element, i.e. the two conductors of a twisted pair or the core and the shield of a coaxial cable. According to another embodiment, the signal injection is carried out between two electrical conductors of two different basic elements, for example a conductor of a twisted pair with a conductor of another pair or the core of a coaxial cable with the core or the shield of another coaxial cable. This wide range of injection configurations is however limited in practice by the capacities of the relay switching matrix used.

[0104] In a particular embodiment, the CBL cable of the device according to the invention can be manufactured with a very fine diameter so that it can be woven to produce a fabric covering a surface. This fabric can be used to cover the surface of an object or device on which the impact of radiation is to be measured.

[0105] Advantageously, the use of reflectometry or transferometry methods also makes it possible to locate the area of ​​the cable or tissue that is irradiated by identifying the time signature of the impedance discontinuity generated by the irradiation in the signal measurement.

[0106] According to another aspect of the invention, the insulation of cables subjected to too high a radiation rate can be regenerated when they are too damaged so as to restore their initial structure. For example, such insulation can be designed with paraffin which can be heated in order to regenerate its structure for a new use. Références

[0107] [1] Wane Yufen, Cao Xiaolong, Liu Yaonan, « Radiation Effects on Dielectric Properties of Dielectric Films », Conference Record of the 1994 IEEE International Symposium on Electrical Insulation, Pittsburgh, PA USA, June 5-8, 1994. [2] Simone Vincenzo Suraci, Davide Fabiani, Konsta Sipilä, Harri Joki, « Filler impact analysis on aging of crosslinked polyethylene for nuclear applications through dielectric spectroscopy », 2020. [3] Simone Vincenzo Suraci, Davide Fabiani, Laura Mazzocchetti and Loris Giorgini, « Degradation Assessment of Polyethylene-Based Material Through Electrical and Chemical-Physical Analyses », Energies 2020, 13, 650. [4] S. Raghu, K. Archana, C. Sharanappa, S. Ganesh, H. Devendrappa, « Electron beam and gamma ray irradiated polymer electrolyte films: Dielectric properties », Journal of Radiation Research and Applied Sciences 9 (2016) 117-124. [5] V. R. Sunitha,·S.Radhakrishnan, « Gamma irradiation effects on conductivity and dielectric behaviour of PEO-based nano-composite polymer electrolyte systems », Polymer Bulletin (2020) 77:655-670.

Claims

1. A device (400) for measuring a received radiation dose comprising a cable (CBL, CBL1, CBL2, CBL3) made up of at least one material sensitive to a received radiation dose in at least one predetermined value range and measuring equipment (GEN, INJ, MES) connected to the cable and configured to take a measurement, by reflectometry or transferometry, of a characteristic physical quantity of the cable, a database (BDM) having a set of pairs of values associating a value of the physical quantity with a received radiation dose value, and a processing unit (UT) configured to determine a measurement of the radiation dose received by the cable based on the measurement of the physical quantity and by polling the database (BDM).

2. The device for measuring a radiation dose according to claim 1, wherein the measuring equipment is configured to inject a test signal at a point of the cable and to measure said propagated or reflected signal at a point of the cable and to determine a measurement of said physical quantity based on the measurement of the signal.

3. The device for measuring a radiation dose according to any one of the preceding claims, wherein the physical quantity is an amplitude of a mismatch peak measured on the signal or a reflection coefficient or a characteristic impedance.

4. The device for measuring a radiation dose according to any one of the preceding claims, wherein the physical quantity is measured at a plurality of points of the cable and the radiation dose measurement is determined for each of these points.

5. The device for measuring a radiation dose according to any one of the preceding claims, wherein the processing unit (UT) is configured to interpolate the values of the database based on the measurement of the physical quantity to deduce the radiation dose measurement therefrom.

6. The device for measuring a radiation dose according to any one of the preceding claims, wherein the database (BDM) has several sets of pairs of values for various types of materials and / or various types of radiation.

7. The device for measuring a radiation dose according to any one of the preceding claims, wherein the cable (CBL1, CBL2, CBL3) is made up of several dielectrics (702, 703, 704, 705) separated by shields (710, 720, 730, 740), with each dielectric exhibiting sensitivity to radiation in various radiation dose ranges, with the measuring equipment being configured to take a measurement of the physical quantity for each dielectric.

8. The device for measuring a radiation dose according to claim 7, wherein the cable (CBL1) has a coaxial structure and is made up of several coaxial dielectrics (702, 703, 704, 705) separated by shields (710, 720, 730, 740).

9. The device for measuring a radiation dose according to claim 7, wherein the cable (CBL2) has a parallel structure and is made up of several coaxial strands (801, 802), each made up of a central core (810, 820), a dielectric (811, 821) and a shield (812, 822).

10. The device for measuring a radiation dose according to claim 7, wherein the cable (CBL3) has a parallel structure and is made up of several twisted pairs, each surrounded by a dielectric and a shield.

11. The device for measuring a radiation dose according to any one of claims 7 to 10, further comprising a switching matrix for connecting the measuring equipment to the various dielectrics of the cable.

12. A smart fabric comprising a device for measuring a radiation dose according to any one of the preceding claims, wherein the cable is a conductive wire woven to produce the fabric.

13. A method for calibrating a device for measuring a radiation dose according to any one of claims 1 to 11, comprising the following steps of: - irradiating at least one portion of the cable with a predetermined radiation dose, - measuring, by reflectometry or transferometry, a characteristic physical quantity of the cable, - saving the pair of radiation dose and associated physical quantity values in a database, - repeating the preceding steps for different radiation doses.