Radionuclide detection device

Abstract

The invention relates to a device (101) for detecting a radionuclide in a gas, the device comprising: a scintillation unit (1) configured to contain the gas, the scintillation unit (1) comprising a porous inorganic scintillator (2) and a container (3) containing the porous inorganic scintillator (2) and comprising at least a portion transparent to photons emitted by the scintillator (2) due to decays of the radionuclide, the container (3) comprising at least one opening (7, 8) for the inlet and outlet of the gas, detection means (9, 10) configured to detect photons emitted by the porous inorganic scintillator (2), and an enclosure (12) opaque to photons outside the enclosure (12) allowing the inlet and outlet of the gas and in which the scintillation unit (1) and the measurement means (9, 10) are arranged, the opaque enclosure (12) being openable and closable to allow access to the scintillating unit (1). Figure for abbreviation: [ Fig. 2 ]

Description

Title of the invention: Radionuclide detection device technical field

[0001] The present invention relates to a device for detecting a radionuclide in a gas.

[0002] The field of the invention is, without limitation, that of the monitoring of nuclear activities. State of the art

[0003] Unstable radionuclides, whether naturally occurring or induced by human activities, naturally lead to the emission of so-called ionizing radiation. The highly effective detection of this radiation is of paramount importance in many sectors of society, particularly health, safety, and nuclear waste management.

[0004] State-of-the-art detectors are based on mixing the gases or liquids to be measured with a detector element itself. In the case of a gas, this can be achieved with an ionization chamber (constituting a gas-gas mixture) or with a liquid scintillator (gas-liquid mixture).

[0005] Among the radionuclides to be detected, tritium (3H) is one of the most difficult to analyze, primarily because it is a low-energy beta emitter. However, tritium is involved in many nuclear activities and must be monitored, for example, during mandatory inspections by nuclear safety authorities or during the decommissioning of nuclear power plants.

[0006] Another example is krypton-85 (85Kr), a fission product in nuclear reactors. Since 85Kr is a noble gas, its movement within the reactor, as well as the presence of even the smallest crack, can be monitored, allowing for the verification of the integrity of the barriers between the fuel and the environment. Aside from concerns about atmospheric releases during nuclear waste processing, it is also a good indicator of a reactor's condition.

[0007] Current detection systems are very specific. Liquid scintillation is generally used for measuring ³H in water samples. However, liquid scintillation cannot be performed on other radioactive gases. In particular, the solubility of ¹⁵Kr is very low in the scintillation liquid.

[0008] Proportional counters for 3H and 85Kr are also used.

[0009] Organic scintillators as well as metal-organic networks (MONs; metal- organic frameworks (MOFs, in English) used in current detectors are subject to contamination over time due to the uptake of radionuclides. For example, by isotopic exchange of 3H. This results in a memory effect limiting the possibility of performing real-time measurements. Description of the invention

[0010] It is an object of the invention to provide a compact detection device for gaseous radionuclides.

[0011] Another object of the present invention is to provide a device for detecting a radioactive gas which makes it possible to easily restore the properties of the scintillator or to change it.

[0012] It is a further objective of the present invention to propose such a device with simple electronic and digital processing.

[0013] At least one of these goals is achieved with a device for detecting a radionuclide in a gas, the device comprising:

[0014] - a scintillating unit configured to contain the gas to be analyzed, the scintillating unit comprising a porous inorganic scintillator and a container containing the porous inorganic scintillator and comprising at least a part transparent to photons emitted by the scintillator due to decays of the radionuclide, the container comprising at least one opening for the entry and exit of the radioactive gas,

[0015] - detection means configured to detect photons emitted by the porous inorganic scintillator,

[0016] - an enclosure opaque to photons external to the enclosure allowing the entry and the radioactive gas outlet and in which the scintillating unit and measuring means are arranged, the opaque enclosure being openable and recloseable to allow access to the scintillating unit.

[0017] The device for detecting radionuclides in a gas comprises an inorganic scintillator. An inorganic scintillator has the advantage of not being subject to radionuclide uptake during measurements. Contamination of the scintillator over time is therefore avoided, or at least reduced. Thus, inorganic scintillators have the advantage of not exhibiting a memory effect that could make measurements complex to analyze.

[0018] Thanks to the presence of a hinged and resealable enclosure, the scintillating unit of the device, as a sensitive part, can be removed from the device for replacement or regeneration. Since the enclosure is light-tight, the device's detection means are protected from ambient light.

[0019] The device according to the invention also represents a very compact detector, having for example dimensions of a few tens of cubic centimeters.

[0020] The detection device according to the present invention makes it possible to determine whether a gas to be analyzed is radioactive or not, that is to say, whether radionuclides are present in The device detects whether or not the gas is present at the time of measurement. It provides a signal only when radionuclides are present in the gas. Depending on the device's calibration, it can also identify the type of radionuclide present in the gas, if any.

[0021] According to one embodiment, the container comprises a part that is not transparent to photons emitted by the porous inorganic scintillator and at least one window that is transparent to photons emitted by the porous inorganic scintillator, the non-transparent part being coated, inside the container, with a reflective layer for photons emitted by the porous inorganic scintillator.

[0022] According to one example, the container can be a metallic cylinder comprising at least one window transparent to photons emitted by the porous inorganic scintillator, the metallic part being coated, inside the cylinder, with a layer reflective to photons emitted by the porous inorganic scintillator.

[0023] Advantageously, the inlet and outlet for the radioactive gas are opaque to, or isolated from, surrounding light.

[0024] Opacity can be obtained, for example, by the geometric shape of the inlet and outlet, and / or by an absorbing layer or absorbing material.

[0025] According to one embodiment, the detection means comprise at least one photodetector, and advantageously a photomultiplier.

[0026] Advantageously, the detection means comprise two photomultipliers.

[0027] The presence of two photomultipliers makes it possible to limit the thermal noise of the photomultipliers generating pulses correlated to the real pulse due to the self-motion of the device and to increase the detection efficiency.

[0028] Alternatively, the device according to the invention can be equipped with a single photomultiplier. In this case, the device is suitable for detecting high-energy radioactive gases.

[0029] The device according to the invention may further include a particle filter configured to filter aerosols and allow gases to pass through.

[0030] The filter protects the inorganic scintillator from contamination by dust or other particles of the gas entering the device.

[0031] The device according to the invention may also include a pump configured to circulate the radioactive gas in the scintillating unit.

[0032] The pump, preferably a micro-pump, improves the circulation of the radioactive gas in the scintillating unit.

[0033] The scintillating unit of the device according to the invention may include one or two openings for the entry and exit of the radioactive gas.

[0034] When only one opening is present, the gas circulates in the scintillating unit by diffusion. In this case, the device does not include a pump.

[0035] The device according to the invention may further include a compressor configured to increase the pressure of radioactive gas in the scintillating unit.

[0036] According to one embodiment, the device according to the invention may further include a lead shielding enclosure surrounding the opaque enclosure.

[0037] The shielding enclosure helps to reduce the noise of natural radioactivity.

[0038] According to one embodiment, the shielding enclosure can be surrounded by a plastic scintillator provided with additional detection means.

[0039] The presence of a plastic scintillator makes it possible to implement a technique called "cosmic veto" to avoid noise in the measurements from external ionizing radiation from the environment.

[0040] According to embodiments, the scintillator may have a specific surface area between 50 and 1000 m² / g and preferably between 100 and 500 m² / g

[0041] The porous inorganic scintillator is an inorganic scintillator having a scintillation yield in the crystal state ideally greater than 10000 photons per MeV and a scintillation decay time less than 500ns, preferably less than 100ns, such as for example a Ce-doped Y3Al50i2, Ce-doped Y2SiO5, Ce-doped YPO4 aerogel.

[0042] In a degraded version (yield less than 10000 photons per MeV), the porous inorganic scintillator may include Ce-doped SiO2, glass.

[0043] The device according to the invention may also include a control unit configured to digitize the signal from the detection means corresponding to the detected photons.

[0044] The control unit can be configured to implement an event counting method based on a number of coincidence windows.

[0045] The gas to be analyzed may in particular be air.

[0046] The detection device according to the present invention can be implemented in a method for detecting radionuclides in a gas.

[0047] The device according to the present invention can in particular be implemented to detect or not radionuclides in a gas, in order to verify the presence or not of radionuclides in the gas.

[0048] The device and detection method according to the present invention can in particular be implemented to detect pure beta-emitting radionuclides, i.e., emitting only electrons, such as tritium (3H) and krypton-85 (85Kr) which are involved in nuclear activities.

[0049] The detection device according to the present invention can be implemented in particular for monitoring the operation of nuclear reactors as well as of the territory for nuclear activities, in particular for activities related to energy production and the recycling and storage of nuclear waste.

[0050] The device according to the invention makes it possible to meet the regulatory monitoring obligation imposed by the nuclear safety authorities, for the control of releases and environmental monitoring. Description of the figures and methods of realization

[0051] Other advantages and features will become apparent upon examination of the detailed description of non-limiting examples and the accompanying drawings, in which: - [Fig.1] [Fig.1] schematically represents a scintillation unit of a radionuclide detection device in a gas according to an embodiment of the present invention; - [Fig.2] [Fig.2] schematically represents a detection block of a radionuclide detection device according to an embodiment of the invention; - [Fig.3] [Fig.3] schematically represents a sealed enclosure of a radionuclide detection device according to an embodiment of the invention; - [Fig. 4] [Fig. 4] schematically represents a detection block of a radionuclide detection device according to another embodiment of the invention; and - [Fig.5] [Fig.5] schematically represents a radionuclide detection device, an embodiment of the present invention.

[0052] It is understood that the embodiments described below are in no way exhaustive. In particular, all the variants and embodiments described may be combined with each other provided there are no technical obstacles to such combination.

[0053] In the figures, elements common to several figures may retain the same reference.

[0054] The radionuclide detection device according to the invention includes a scintillator configured to contain the radioactive gas, as well as detection means for detecting photons emitted by the scintillator due to radionuclide decays.

[0055] The detection means comprise one or more photodetectors. For example, the measurement means may comprise one, two, or three photodetectors, such as photomultipliers, depending on the measurement mode applied.

[0056] The scintillator is exposed to the gas in a closed container. The radiation from the radioactive decays interacts with the scintillator, which emits light (photons) as a result of these interactions. The photons can be detected by one or more Photodetectors. In general, to overcome the intrinsic noise of photodetectors, an event is considered valid if at least two photons are detected within a temporal coincidence window. An "event" corresponds to a decay.

[0057] The volume of the scintillator is directly proportional to its sensitivity, within the limit of the transparency of the scintillator for the emitted photons and the diffusion time of the radioactive gas to be measured.

[0058] The photodetector(s) may, in particular, be photomultiplier tubes. It is possible to use either three photodetectors for measurements with one window of coincidence, or two photodetectors for measurements with two different windows of coincidence. It is also possible to use only a single photodetector when the data processing is adapted accordingly.

[0059] Fig. 1 schematically represents, in a side view and a front view, a scintillating unit 1, or scintillation unit, of a device for detecting radionuclides in a gas according to an embodiment of the present invention.

[0060] The scintillating unit 1 comprises a porous inorganic scintillator 2. The porosity of the scintillator is characterized by its specific surface area. In the device according to the invention, the specific surface area of ​​the scintillator is between 50 and 1000 m² / g, and preferably between 100 and 500 m² / g.

[0061] Preferably, the porous inorganic scintillator 2 comprises a Ce-doped Y3A15O 12 aerogel.

[0062] The porous inorganic scintillator 2 can be any other scintillator emitting photons between 350 and 600 nm wavelength, and whose efficiency is preferably greater than 10,000 photons per MeV. The scintillation decay time of the inorganic scintillator is preferably less than 500 ns, and even more preferably less than 100 ns.

[0063] The scintillator 2 may also comprise Ce-doped Y2SiO5, or Ce-doped YPO4.

[0064] In a degraded version (yield less than 10000 photons per MeV), the porous inorganic scintillator may comprise Ce-doped SiO2, or glass.

[0065] The scintillator 2 can be in the form of a set of scintillating capillaries, for example from 10 pm to 2 mm in diameter.

[0066] The scintillator 2 can also be in the form of a 3D printed inorganic scintillator in the form of a cylinder having pores a few micrometers in diameter communicating with each other.

[0067] Preferably, scintillator 2 is in the form of a porous scintillator with pores on the order of a hundred nanometers.

[0068] The scintillating unit 1 further comprises a hermetically sealed container 3 containing the inorganic scintillator 2.

[0069] In the embodiment of [Fig. 1], the container 3 is a cylinder whose two bases are formed by windows 4, 5. The cylinder 3 is hermetically sealed. At least one of the windows 4, 5 is preferably unscrewable or otherwise removable, allowing the scintillator to be installed or changed. The metallic part of the cylinder 3 is opaque to the photons generated in the scintillator 2. Only the windows 4, 5 are transparent to these photons.

[0070] Container 3 is made of metal, and preferably stainless steel.

[0071] The windows 4, 5 can be made of glass or quartz, for example.

[0072] The container 3 must withstand a certain internal pressure, which can rise up to 10 bar, for example.

[0073] Advantageously, the internal surface of the opaque part of the cylinder 3 is provided with a layer 6 which is highly reflective for the light generated in the scintillator 2. This helps to avoid photon losses and thus to increase the sensitivity of the device.

[0074] Container 3 is provided with at least one opening for the entry and exit of the radioactive gas to be measured, i.e., to circulate it in the scintillator.

[0075] In the embodiment as shown in [Fig. 1], the container 3 comprises a radioactive gas inlet 7 and outlet 8. The inlet 7 and outlet 8 are in the form of a tube, respectively. A tube is positioned at each end of the container 3, enabling the circulation of ambient radioactive gas.

[0076] To prevent ambient light from entering the scintillator 2, the shape of the inlet / outlet tubes is chosen to block the light. The tubes may, for example, be spiral or serpentine in shape. Also, the inner walls of the tubes may be coated with an absorbent layer, for example, black paint.

[0077] By way of example, the tube(s) may have a spiral shape with a length of about 20 cm, an internal diameter of 4 mm and an external diameter of 6 mm.

[0078] In order to prevent dust or other foreign bodies from entering and degrading the scintillator, a filter (not shown) may be provided upstream of the inlet opening.

[0079] Figure [Fig.2] schematically represents a detection block of a radionuclide detection device in a radioactive gas according to an embodiment of the present invention.

[0080] The detection block 11 of the device according to the invention comprises a scintillating unit 1, for example as described in relation to [Fig.1].

[0081] The detection block 11 further includes detection means configured to detect photons emitted by the scintillator.

[0082] In the embodiment shown in [Fig.2], the detection means comprise two photodetectors 9, 10. These are preferably photomultipliers.

[0083] The photodetectors 9, 10 are arranged on the flat faces of the cylinder 3, i.e., the windows 4, 5. The photodetectors 9, 10 detect the light emitted by the scintillator and passing through the windows 4, 5.

[0084] The photodetectors 9, 10 can be coupled to the windows 9, 10 using an index gel or optical grease for adapting the refractive index.

[0085] As shown in [Fig.2], the detection block 11 comprises an enclosure 12 surrounding the detection block 1.

[0086] The enclosure 12 is an opaque, or photon-tight, encapsulation enclosure. The enclosure 12 is provided with at least one opening 13, 14 allowing the entry and exit of the radioactive gas. In the example shown in [Fig. 2], the inlet tube 7 and outlet tube 8 of the detection block 1 each pass through an opening 13, 14 of the enclosure.

[0087] The enclosure 12 is preferably made of metal, but may also be made of polymer. The enclosure 12 is lightproof. The enclosure 12 is preferably black, or at least highly absorbent of ambient light.

[0088] Advantageously, the enclosure 12 is openable and / or removable. It is detachable.

[0089] Fig. 3 shows, in a top view and a front view, an example of the enclosure 12 made in two parts 12a, 12b connected by at least one hinge 15 to allow its opening.

[0090] Of course, any other suitable opening / closing system can be used.

[0091] The enclosure 12 can therefore be opened and closed. After closing, the enclosure 12 The unit is returned to its original state, reproducibly. This allows for easy disassembly of scintillator unit 1. Scintillation unit 1 can then be replaced. Scintillation unit 1 can also be subjected to heat treatment (up to 600 °C) in dry air or under other atmospheric conditions to regenerate the inorganic scintillator. Regeneration involves decontaminating the scintillator, which can occur in cases of high water or tritiated water contamination, for example.

[0092] In order to increase the amount of gas in the scintillation unit while maintaining the same detection volume, a compressor and an outlet valve can be provided at the inlet of the device. The pressure is thus increased in the scintillation unit, thereby increasing the detection sensitivity proportionally. The container thus that its windows must be adapted to withstand the increased pressure, particularly in terms of sealing. The pressure in the scintillating unit can, for example, be increased by a factor of 10.

[0093] Figure 4 schematically represents another variant of a detection block of a radionuclide detection device in a radioactive gas according to another embodiment of the present invention.

[0094] In the embodiment of [Fig.4], a detection block 11, for example as described with reference to [Fig.2], is surrounded by a shielding enclosure 17. The shielding enclosure 17 therefore surrounds the sealed enclosure 12 of the detection block 11.

[0095] The shielding enclosure 17 is preferably made of lead.

[0096] An additional plastic scintillator 16 surrounds the shielding enclosure, or shielding layer 17.

[0097] The device also includes additional detection means operating with the plastic scintillator 16. The additional detection means include at least one additional photodetector 19 arranged adjacent to the plastic scintillator 16.

[0098] Fig. 4 also shows the gas inlet 7 and outlet 8.

[0099] The shielding layer 17 makes it possible to reduce the self-movement of the device, that is to say, the noise caused by natural external ionizing radiation, on the measurements carried out.

[0100] The plastic scintillator 16, with the additional detection means, also makes it possible to reduce the self-movement of the device.

[0101] In particular, the plastic scintillator 16 enables the implementation of a cosmic veto. External radiation present in the environment, such as cosmic rays or gamma radiation from the environment, produces events that can be detected by the two scintillators present in the device. If an event is detected in the inorganic scintillator, for example gamma rays or muons, and the same event is detected in the plastic scintillator at the same time (coincidentally), the event is not counted in the inorganic scintillator.

[0102] The action of the shielding layer 17 and that of the plastic scintillator 16 can be combined, as is the case for the embodiment shown in [Fig.4],

[0103] According to another embodiment, the device according to the invention may include a shielding layer surrounding the sealed enclosure, without a plastic scintillator surrounding the shielding layer.

[0104] Depending on the variant, the armor layer can be more or less thick.

[0105] By way of example, the device according to the invention may include a 5 cm thick shielding layer and no plastic scintillator. The noise caused by the device's own motion can then be reduced by a factor of 10. The detection limit of the device is increased by the same factor.

[0106] According to another example, the device according to the invention may include a 10 cm thick shielding layer and no plastic scintillator. The noise caused by the device's own motion can then be reduced by a factor of 100. The detection limit of the device is increased by the same factor.

[0107] According to yet another example, the device according to the invention may comprise a 15 cm thick shielding layer and a plastic scintillator. The noise caused by the self-motion can then be reduced by a factor of 400. The detection limit of the device is increased by the same factor.

[0108] Figure [Fig. 5] schematically represents a device for detecting radionuclides in a radioactive gas according to an embodiment of the present invention.

[0109] The device 101 may include the components as described for example in relation to the embodiment shown in [Fig.2].

[0110] The gas inlet 107 and outlet 108 each include a serpentine portion 107a, 108a.

[0111] The device 101 includes a pump, and in particular a micro-pump 121, for ensuring efficient circulation of the air to be analyzed in the scintillation unit. The pump flow rate can, for example, be on the order of L / min. The micro-pump 121 is arranged downstream of the inlet coil 107a.

[0112] A high-efficiency airborne particle filter (HEPA filter) 128 is arranged upstream of the inlet coil 107a to prevent dust or other foreign matter from entering the inorganic scintillator.

[0113] A power supply circuit for the device 101 includes a microcontroller 122 controlling the micropump 121 and a high-voltage (HV) source 123. The HV source 123 is followed by a voltage divider 124 (for example, an RC circuit) to distribute the voltage and supply the two photodetectors (the power supplies being designated by HV-A and HV-B). The power supplies for the photodetectors are matched to obtain identical performance between the two detectors.

[0114] The two signal outputs (indicated by SA and SB) are connected to a control unit 125 configured to digitize the signal from the photodetector(s) corresponding to the photons generated in the inorganic scintillator and detected.

[0115] The control unit 125 can be a time coincidence unit, implementing two coincidence windows. The coincidence windows, or gates, can be preset or variable. The coincidence unit 125 allows for the processing of measured pulses and the counting of coincidences. In the example shown, the unit Coincidence window 125 performs coincidences between the SA and SB signals detected by the two photodetectors. One coincidence window, or two different coincidence windows, can be implemented.

[0116] Advantageously, the device according to the invention comprises two photomultiplier tubes tuned to the single-photon threshold and implementing at least two time windows of coincidence: a short window, on the order of twice the principal time constant of the inorganic scintillator (for example, 20 ns in the case of YAG:Ce), and a long window, at least ten times longer than the short window (for example, 200 ns). The short window limits the noise related to the device's own motion, and the long window maximizes the detection efficiency.

[0117] Two additional coincidence windows can be implemented in the device according to the invention. Their temporal width is much greater than the decay time of the inorganic scintillator. For example, in the case of YAG:Ce, their width can be 3000 and 3500 ns. The difference in counting between these two windows makes it possible to measure the rate of random coincidences and to apply a correction to the measurement of the number of detected events.

[0118] The detection device according to the present invention can be implemented in a method for detecting radionuclides in a gas.

[0119] The device according to the present invention can in particular be implemented to detect or not radionuclides in a gas, in order to verify the presence or not of radionuclides in the gas and to determine whether a gas is radioactive or not.

[0120] For this purpose, the gas to be analyzed is injected into the scintillation unit, for example by means of a micro-pump as described previously.

[0121] For a certain period of time, for example for 1 minute, the number of coincidences is counted. Each coincidence corresponds to a radioactive event, that is to say, a radioactive decay resulting in the emission of a photon by the scintillator.

[0122] A counting, or detection, signal can be emitted at each coincidence. If there is a detection signal, it indicates the presence of radionuclides in the gas, and therefore the radioactivity of the gas.

[0123] It is thus possible to analyze gases to determine whether they are radioactive or not. The absence of coincidence detection allows us to conclude that there are no radionuclides in the gas.

[0124] When the device has been previously calibrated, it is possible to link the number of coincidences per second to an activity measured in Becquerels for a given radionuclide species.

[0125] In particular, the device may have been calibrated by an average number of photons detected per decay and a decay detection yield for one or more radionuclides. It is possible to measure the average number of photons produced per decay for the gas to be analyzed, and to determine the number of decays for each radionuclide present from the average number of photons detected for each radionuclide and the average number of photons detected for the gas. The activity of each radionuclide can then be determined from the number of decays and the decay detection yield for each radionuclide in the gas to be analyzed.

[0126] Of course, the invention is not limited to the examples just described and many modifications can be made to these examples without departing from the scope of the invention.

Claims

Demands

1. A device (101) for detecting a radionuclide in a gas, the device comprising: - a scintillation unit (1) configured to contain the gas, the scintillation unit (1) comprising a porous inorganic scintillator (2) and a container (3) containing the porous inorganic scintillator (2) and comprising at least a portion transparent to photons emitted by the scintillator (2) due to decays of the radionuclide, the container (3) comprising at least one opening (7, 8) for the inlet and outlet of the gas, - detection means (9, 10) configured to detect photons emitted by the porous inorganic scintillator (2), and - an enclosure opaque to photons outside the enclosure (12) allowing the inlet and outlet of the gas and in which the scintillation unit (1) and the measurement means (9, 10) are arranged, the opaque enclosure (12) being openable and resealable to allow access to the scintillating unit (1).

2. Device (101) according to claim 1, characterized in that the container (3) comprises a part not transparent to photons emitted by the porous inorganic scintillator and at least one window (4, 5) transparent to photons emitted by the porous inorganic scintillator (2), the non-transparent part being coated, inside the container (3), with a reflective layer (6) for photons emitted by the porous inorganic scintillator (2).

3. Device (101) according to any one of the preceding claims, characterized in that the detection means (9, 10) comprise at least one photomultiplier.

4. Device (101) according to any one of the preceding claims, characterized in that it further comprises a shielding enclosure (17) surrounding the opaque enclosure (12).

5. Device (101) according to claim 4, characterized in that the shielding enclosure (17) is surrounded by a plastic scintillator (16) provided with additional detection means (19).

6. Device (101) according to any one of the preceding claims, characterized in that the porous scintillator (2) has a specific surface area between 50 and 1000 m2 / g and preferably between 100 and 500 m2 / g.

7. Device (101) according to any one of the preceding claims, characterized in that the scintillation decay time of the porous inorganic scintillator (2) is less than 500 ns, preferably less than 100 ns.

8. Device (101) according to any one of the preceding claims, characterized in that it further comprises a control unit (125) configured to digitize the detected photons.

9. A method for detecting a radionuclide in a gas, the method being carried out using a device for detecting a radionuclide in a gas according to any one of the preceding claims, the method comprising the following steps: - introduction of the gas into a scintillating unit, - detection, by the detection means (9, 10), of photons emitted by the porous inorganic scintillator (2), - counting of coincidences, each coincidence corresponding to a decay of a radionuclide, and - emission of a counting signal for counts greater than zero, the counting signal indicating the presence of radionuclides in the gas.