Device for measuring the dose of radiation received by reflectometry or transferometry

Abstract

A received radiation dose measurement device (400) comprising a cable (CBL, CBL1, CBL2, CBL3) made of at least one material sensitive to a received radiation dose within at least a predetermined range of values, and a measuring instrument (GEN, INJ, MES) connected to the cable and configured to perform a measurement, by reflectometry or transferometry, of a physical quantity characteristic of the cable, a database (BDM) containing 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 from the measurement of the physical quantity and by querying the database (BDM). Figure 4

Description

Title of the invention: Device for measuring the dose of radiation received by reflectometry or transferometry

[0001] The invention relates to the field of nuclear facilities subjected to irradiation, and more generally to radiological hazards that can cause damage to structures. More generally, the invention relates to any application associated with an environment in which measuring radiation dose is of interest, particularly in 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 important data for the maintenance and prevention of failure of this equipment. In particular, in the field of nuclear facilities, preventing equipment malfunction is essential to guarantee the safety of operators.

[0004] Known solutions for measuring radiation doses are most often based on active or passive dosimeters placed locally at specific locations on the equipment to be monitored or on individuals. These solutions have the particular drawback of only being able to perform measurements at a limited number of points and requiring as many devices as there are points to monitor. 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 to detect 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.

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

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

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

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

[0011] The invention relates to a received radiation dose measurement device comprising a cable made of at least one material sensitive to a received radiation dose in at least a predetermined value range and a measurement device connected to the cable and configured to perform 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 received radiation dose and a processing unit configured to determine a measurement of the received radiation dose by the cable from the measurement of the physical quantity and by querying the database.

[0012] According to a particular aspect of the invention, the measuring equipment is configured to inject a test signal at a point in the cable and measure said signal propagated or reflected at a point in 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 perform an interpolation of the database values ​​from the measurement of the physical quantity in order 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 exhibiting sensitivity to radiation in different radiation dose ranges, the measuring equipment being configured to perform 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 consisting 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 an intelligent fabric comprising a radiation dose measurement device according to the invention in which the cable is a woven conductive thread to make the fabric.

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

[0024] Other features and advantages of the present invention will become more apparent from the following description in relation to the following accompanying drawings.

[0025] [fig. 1] [fig. 1] represents an example of a reflectometry device according to the state of the art,

[0026] [fig.2] Fig.2 represents an example of a time-domain reflectogram obtained by means of of the device of [fig.l],

[0027] [fig.3] [fig.3] represents a time diagram illustrating the general principle of transferometry,

[0028] [fig.4] Fig.4 represents a schematic diagram of a ra dose detection device adaptations according to an embodiment of the invention,

[0029] [fig.5] Fig.5 represents several time-domain reflectograms obtained using a device according to the invention to characterize a received radiation dose,

[0030] [fig.6] represents an example of interpolation of cumulative radiation dose values ​​as a function of a characteristic impedance measurement,

[0031] [fig.7] represents a first embodiment of a cable used to achieve a device according to the invention,

[0032] [fig.8] represents a second embodiment of a cable used to achieve a device according to the invention,

[0033] [fig.9] represents a third embodiment of a cable used to achieve a device according to the invention,

[0034] [fig.10] represents an example of an embodiment of the device according to the invention.

[0035] We first recall some notions relating to reflectometry and transferometry methods applied to the detection of defects in a cable.

[0036] According to a known principle, the so-called reflectometry or transferometry methods are used to detect and / or locate electrical or mechanical faults that generate discontinuities or breaks in impedance in a cable.

[0037] Reflectometry methods use a principle similar to that of radar: an electrical signal, often high-frequency or broadband, is injected at one or more points in the cable to be tested. The signal propagates through the cable or network and reflects some of its energy back when it encounters an electrical discontinuity. An electrical discontinuity can result, for example, from a branch connection, the end of the cable, or more generally from a disruption in the signal propagation conditions within the cable. It most often results from a fault that locally alters the characteristic impedance of the cable, causing a discontinuity in its linear parameters.

[0038] 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 on any potential defects. An analysis in the time domain or frequency domain is usually performed. These methods are designated by the acronyms TDR, from the English expression "Time Domain Reflectometry," and FDR, from the English expression "Frequency Domain Reflectometry."

[0039] These methods are generally used to detect and locate local cable damage, for example damage affecting the cable sheath.

[0040] Figure 1 schematically illustrates, as a reminder, the operating principle of a reflectometry diagnostic method applied to a transmission line L exhibiting a DNF fault, for example, a non-obvious fault. The example described below corresponds to a time-domain reflectometry method.

[0041] A reference signal S, also called the 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 along the line and, during its propagation, encounters a first impedance discontinuity at the input of the non-fault DNF. The signal is reflected at this discontinuity with a reflection coefficient rb. If the characteristic impedance Zc2 in the area of ​​the non-fault DNF is less than the characteristic impedance Zcl before the fault occurs, then the reflection coefficient F is negative and results in a negative amplitude peak in the reflected signal R. Conversely, the reflection coefficient T1 is positive and results in a peak of positive amplitude in the reflected signal R.

[0042] The transmitted part of the incident signal S continues to propagate in the line beyond the fault (part T in Figure 1) and then encounters a second impedance discontinuity creating a second reflection of the incident signal with a reflection coefficient T2 of opposite sign to the first reflection coefficient FP. If F{ <0 then F2 > 0. If G > 0 then F2 < 0.

[0043] Thus, by observing the reflected signal R, the signature of the non-frank defect DNF is characterized by two successive peaks of reversed signs as shown in [fig.2].

[0044] Fig. 2 represents a time 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.

[0045] 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 directly correspond 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 type MCTDR (Multi Carrier Time Domain Reflectometry) or OMTDR (Orthogonal Multi-tone Time Domain Reflectometry), then the reflectogram is obtained by intercorrelating the reflected signal R and the injected signal S.

[0046] In [Fig. 2], two reflectograms 201 and 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.AT much greater than the transit time of the signal through the non-obvious fault DNF. Since the fault length is denoted Ld, this duration is equal to Ld / V, where V is the propagation speed of the signal in the cable. Curve 202 corresponds to a pulse duration 2.AT much less than the transit time of the signal through the non-obvious fault DNF.

[0047] In both cases, the signature 203 of the non-obvious defect, in the reflectogram, is always composed of the succession of a first peak and a second peak whose signs are reversed.

[0048] The distance between the two peaks represents the length of the non-obvious defect, and their amplitude represents the severity of the non-obvious defect. Indeed, the greater the variation in the characteristic impedance, the greater the amplitude of the non-obvious defect signature in the reflectogram.

[0049] The higher the frequency of the signal, the greater the accuracy in estimating the length of the defect, as can be identified in [fig.2].

[0050] As is known in the field of reflectometric diagnostic methods, the position dDNF of the non-obvious 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 reflectogram of [Fig. 2], of the duration tDNF between the first peak amplitude recorded on the reflectogram (at abscissa 0.5 in the example of [fig.2]) and the peak amplitude 203 corresponding to the signature of the non-clear defect.

[0051] Several known methods can be used to determine the position dDNF. One method involves applying the relationship between distance and time: dDNF = V.tDNF / 2 where V is the signal propagation speed in the cable. Another possible method involves applying a proportionality relationship of the type dDNF / tDNF = L / t0 where L is the cable length and t0 is the time, measured on the reflectogram, between the amplitude peak corresponding to the impedance discontinuity at the injection point and the amplitude peak corresponding to the signal reflection at the cable end.

[0052] Transfer function methods exploit not the portion of the signal reflected at an impedance discontinuity, but the portion of the signal transmitted after that impedance discontinuity. Thus, a transfer function test consists of measuring the signal propagated at another point in the cable, distant from the signal injection point. For example, the measurement is performed at the opposite end of the cable from the signal injection point.

[0053] A transferometry test consists of comparing the measurement taken to a reference obtained at a previous time, for example corresponding to a new or healthy state of the cable.

[0054] Figure 3 shows, in a diagram, an example of signals measured after their propagation between two devices located at points separated by a cable. The injected signal is a time pulse. Signal 301 corresponds to a reference obtained for a healthy or undegraded state of the cable. Signals 302, 303, and 304 are obtained for different levels of cable degradation.

[0055] A transfer function test consists, for example, of calculating the difference between the maximum signal peak obtained for the current measurement and for the reference. As can be seen in [Fig. 3], the more degraded the cable, the more the signal peak is attenuated. The transfer function test can take into account other signal characteristics, such as the peak width 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 transfer function test is to compare the shape of the signals obtained at two different times in order to detect cable degradation 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.Reference measurement 301 can also be obtained by simulation from a model of the cable parameters.

[0056] Reflectometry and transferometry methods are generally used for the purpose of detecting defects related to local degradation on a cable.

[0057] The present invention proposes to use these methods to design a new device for measuring the dose of radiation received.

[0058] 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 tolerable dose before a short circuit occurs also depends on the physical properties of the material.

[0059] In installations that are to be protected 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 depending on the cumulative radiation dose.

[0060] 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.

[0061] To this end, it is proposed to use reflectometry and transferometry techniques to detect impedance discontinuities that affect the cable due to its exposure to radiation. Indeed, certain physical parameters of a cable are directly affected by radiation and can generate an impedance discontinuity in the same way as physical degradation.

[0062] This is notably 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.

[0063] Reflectometry (or transferometry) allows a cable to be characterized by its RLCG parameters. Permittivity plays a role in the definition of these parameters, in particular C and G, but also through the definition of the characteristic impedance and the Fonde speed propagating in the cable, and more generally in the definition of any physical parameter dependent on C and G such as the tangent delta or the attenuation.

[0064] 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.

[0065] 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 subjected to radiation, by carrying out a measurement by reflectometry or transferometry on the cable.

[0066] Fig. 4 represents a general diagram of a device according to the invention.

[0067] It comprises a CBL cable made of 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 includes the equipment necessary to perform a reflectometry test or a transferometry test. In other words, it includes a reference signal generator (GEN) and an injection equipment for injecting the reference signal at a first point in the cable (for example, one end). The injection equipment includes, in particular, a digital-to-analog converter and a coupler. The device also includes a measurement equipment for measuring the signal reflected or propagated in the cable, capable of performing a measurement at the same injection point in the cable or at another point (for example, the opposite end of the cable). The measurement equipment includes, in particular, a coupler for acquiring the measurement and an analog-to-digital converter for digitizing the measurement.

[0068] The coupler can be a directional coupler with a capacitive or inductive effect, or a galvanic connection. The coupler can be implemented by physical connectors that link 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.

[0069] The device 400 further includes a processing unit UT configured to generate a time-domain reflectogram or a time-domain diagram characteristic of a transfer function measurement. For example, the processing unit includes a FIL filtering module and a TR processing module to generate a physical quantity characteristic of the measurement as a function of its position on the cable. For example, this physical quantity corresponds to a signal reflection coefficient 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 MES measurement equipment calculated on a chosen peak characteristic of an impedance discontinuity.

[0070] The device 400 further includes a BDM database in which reference pairs are stored, 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 stored 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 from which the cable is composed. The materials are, for example, different types of polymers, including Ethylene Propylene, Ethylene Vinyl Acetate, Polyvinyl Chloride, Polytetrafluoroethylene, or Polyethylene.

[0071] The radiations are, for example, of the gamma or beta type; they may be neutrons or any other type of radiation likely to significantly alter the electrical parameters of the cable.

[0072] The information contained in the BDM database can be obtained via a calibration phase which will be described in detail later. This allows a 401 curve to be constructed 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.

[0073] 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.

[0074] The device 400 according to the invention further includes a module for calculating the radiation dose 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.

[0075] 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.

[0076] The cumulative radiation dose value calculated by the CDR module can be provided to a display or any other human-machine interface.

[0077] The cumulative radiation dose value is, for example, calculated by interpolating the values ​​contained in the BDM database from the value provided by the processing unit UT.

[0078] Figure 5 shows an example of time-domain reflectograms obtained by irradiating a cable over a Z-area, for example by placing a portion of this cable in an irradiator. The different curves are obtained for different gamma radiation dose values ​​received by the cable. In this example, the cable consists of a sheathed and shielded twisted pair with ethylene-vinyl acetate (EVA) insulation.

[0079] The curves in [Fig. 5] are obtained by performing time-domain reflectometry measurements. The impact of the gamma radiation is observable via peaks 501 and 502, corresponding respectively to the beginning and end of the irradiated area.

[0080] These peaks correspond to impedance discontinuities generated by irradiation. The amplitude of peaks 501, 502 depends directly on the received radiation dose.

[0081] Thus, by analyzing these reflectograms it is possible to deduce an estimate of the radiation dose received.

[0082] More precisely, a physical quantity characteristic of the impedance discontinuity generated locally by the radiation is determined from the measured reflectograms. This physical quantity can be directly the amplitude of peak 501 or of peak 502 measured as a function of the position of this discontinuity on the cable.

[0083] 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 of the French patent application No. 3034203 or any other suitable method.

[0084] More generally, any physical quantity that can be derived from a reflectogram or a measurement obtained by transferometry can be used.

[0085] 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.

[0086] This calibration process can be carried out for different types of cables designed with different materials.

[0087] 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 ​​from the BDM database from the measurement provided by the TR processing module.

[0088] Fig. 6 represents an example of interpolation performed by the CDR module.

[0089] Figure 6 represents different radiation dose values ​​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 performed to obtain, for any value of the characteristic impedance Zc, the corresponding dose value.

[0090] More generally, interpolation is not necessarily linear; it can be polynomial or performed 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.

[0091] The radiation dose is calculated by the CDR module by applying the interpolated function to the value provided by the TR processing module.

[0092] The radiation dose received can be calculated at different points along the cable.

[0093] Different embodiments of CBL cable architecture are possible. According to One initial design variant, the CBL cable, is a simple cable with only one possible path for the flow of electrical current. For example, it could be a standard coaxial cable or a twisted-pair cable. However, a drawback of this type of cable is that it is based on only one dielectric material, which potentially limits the measurement range of the received radiation dose. Indeed, each dielectric material is sensitive to a specific type of radiation within a given range. predetermined range of values.

[0094] 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 for their high sensitivity to increasing radiation doses, such as different dielectrics. This makes it easier to obtain a cable usable over a wide range of cumulative doses, which would be difficult, if not impossible, with a single type of material.

[0095] Each dielectric is optimized to exhibit good sensitivity within a cumulative dose range and to a given type of radiative radiation. By judiciously selecting the materials, complementary dose ranges can be obtained, ultimately providing a wide coverage area.

[0096] Figures 7, 8 and 9 describe three particular embodiments of CBL cable architecture. These three architectures have in common that they include several different dielectrics, each dielectric having a sensitivity to radiation in different ranges of values.

[0097] One advantage of these particular architectures is that they make it possible to produce a cable having sensitivity to cumulative radiation doses in a wide range of values, which is more difficult to obtain with a single material.

[0098] Fig. 7 illustrates the cross-section of a CBL1 coaxial cable consisting of a central core 701 surrounded by several different dielectrics 702, 703, 704, 705 separated from each other by shields 710, 720, 730, 740.

[0099] Advantageously, the different dielectrics are chosen so that each dielectric exhibits radiation sensitivity within a different range of values. For example, the different dielectrics are designed by selecting a base insulator and progressively increasing its antioxidant content to design each dielectric layer.

[0100] Preferably, the value ranges are increasing in the direction from the core 701 towards the outside of the cable. Alternatively, the value ranges may also be decreasing in the direction from the core 701 towards the outside of the cable.

[0101] In other words, in one embodiment of the invention, the dielectric 702 is chosen to be sensitive to radiation doses within the range [a; b], the dielectric 703 is chosen to be sensitive to radiation doses within the range [b; c], the dielectric 704 is chosen to be sensitive to radiation doses within the range [c; d], the dielectric 705 is chosen to be sensitive to radiation doses within the range [d; e], with a <b<c<d<e.

[0102] Figure 8 shows another embodiment of a CBL2 cable having a parallel structure. The CBL2 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.

[0103] The different dielectrics 811, 821 are chosen in the same way as for the CBLi cable of [fig.7], that is to say, they are each sensitive to different ranges of radiation dose values.

[0104] Fig. 9 represents yet another embodiment of a CBL3 cable also having a parallel structure but the coaxial strands of Fig. 8 are replaced by twisted pairs surrounded by a different dielectric for each pair.

[0105] Without departing from the scope of the invention, other cable architectures are conceivable insofar as the cable designed comprises several dielectrics, each having different sensitivities to radiation.

[0106] In particular, another possible cable architecture consists of using, instead of twisted pairs, two-wire lines made up of two parallel conductors.

[0107] The sensitivity of a dielectric to radiation is measured as a function of the impact of this radiation on the physical quantity measured from the reflectogram or the measurement obtained by transferometry.

[0108] 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, relative to a reference value obtained for a cable not subjected to radiation.

[0109] Reflectometry or transferometry tests are performed by injecting a signal between the core 701 of the CBLI 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 [Fig. 7] or [Fig. 8] is used, several tests leading to several measurements are performed for each of the dielectrics.

[0110] Fig. 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 Fig. 8.

[0111] In this case, the reflectometry test is implemented using signal switching matrices MC based, for example, on electromagnetic relays that direct the injection of a reflectometry signal to the correct pair of conductors. The switching matrix is ​​connected via its inputs to the reflectometer R, i.e., the device comprising, on the one hand, means for injecting a signal into a cable and, on the other hand, means for measuring the backpropagated signal. Furthermore, each output of the switching matrix is ​​connected to one of the coaxial strands 801, 802 of the cable.

[0112] For single cables, the reflectometry signal injection is carried out between the two electrical conductors of a twisted pair or between the core and the shield of a coaxial.

[0113] For complex cables, signal injection is, for example, performed between two electrical conductors of the same basic element, i.e., the two conductors of a twisted pair or the core and shield of a coaxial cable. According to another embodiment, signal injection is performed 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 shield of another coaxial cable. This wide range of injection configurations is, however, limited in practice by the capabilities of the relay switching matrix used.

[0114] 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 create 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.

[0115] Advantageously, the use of reflectometry or transferometry methods also makes it possible to locate the area of ​​the cable or fabric that is irradiated by identifying the time signature of the impedance discontinuity generated by the irradiation in the signal measurement.

[0116] According to another aspect of the invention, cable insulators subjected to excessively high radiation levels can be regenerated when they are too damaged so as to restore their original structure. For example, such insulators can be made of paraffin, which can be heated to regenerate its structure for reuse. References

[0117] [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.

[0118] [2] Simone Vincenzo Suraci, Davide Fabiani, Konsta Sipilâ, Harri Joki, “Filler impact analysis on aging of crosslinked polyethylene for nuclear applications through dielectric spectroscopy”, 2020.

[0119] [3] Simone Vincenzo Suraci, Davide Fabiani, Laura Mazzocchetti and Loris Giorgini, « Dégradation Assessment of Polyethylene-Based Material Through Electrical and Chemical-Physical Analyses », Energies 2020, 13, 650.

[0120] [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.

[0121] [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

Claims

1. Device (400) for measuring the dose of radiation received comprising a cable (CBL, CBLi, CBL2, CBL3) composed of at least one material sensitive to a dose of radiation received in at least one predetermined value range and measuring equipment (GEN, INJ, MES) 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 (BDM) 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 (UT) 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 (BDM).

2. A radiation dose measuring device according to claim 1 wherein 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.

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

4. A radiation dose measuring device according to any preceding claim wherein 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.

5. Radiation dose measuring device according to any one of the preceding claims in which the processing unit (UT) is configured to carry out an interpolation of the values ​​of the database from the measurement of the physical quantity to deduce therefrom the radiation dose measurement.

6. Radiation dose measuring device according to any one of the preceding claims in which the database (BDM) comprises several sets of pairs of values ​​for different types of materials and / or different types of radiation.

7. A radiation dose measuring device according to any preceding claim wherein the cable (CBLi, CBL2, CBL3) is composed of several dielectrics (702, 703, 704, 705) separated by shields (710, 720, 730, 740), 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.

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

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

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

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

12. A smart fabric comprising a radiation dose measuring device according to any preceding claim wherein the cable is a conductive yarn woven to make the fabric.

13. Method for calibrating a radiation dose measuring device according to any one of claims 1 to 11 comprising the steps of: - Irradiating at least a portion of the cable with a predetermined radiation dose, - Carrying out a measurement, by reflectometry or transferometry, of a physical quantity characteristic of the cable, - Saving in a database the pair of radiation dose values ​​and associated physical quantity, - Iterating the previous steps for different radiation doses.

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