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 one portion which is transparent to the photons emitted by the scintillator (2) due to disintegrations of the radionuclide, the container (3) comprising at least one opening (7, 8) for the entry and exit of the gas and for causing it to circulate through the scintillator (2); - detection means (9, 10) configured to detect photons emitted by the porous inorganic scintillator (2); and - an enclosure (12) opaque to photons external to the enclosure (12), which allows the entry and exit of the gas and in which the scintillation unit (1) and the detection means (9, 10) are arranged, the opaque enclosure (12) comprising an opening / closing system and being openable and reclosable so as to allow access to the scintillation unit (1).

Description

Radionuclide detection device

[0001] The present invention relates to a device for detecting one or more radionuclides 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 produced by human activities, naturally lead to the emission of ionizing radiation. The efficient detection of this radiation is of paramount importance in many sectors of society, including health, safety, and nuclear waste management.

[0004] State-of-the-art detectors are based on mixing the gas or liquid 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 is tritium ( 3 Tritium (H) is one of the most difficult to analyze, primarily because it consists of low-energy beta (electron) emitters. However, tritium is involved in numerous 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 ( 85 Kr), a fission product in nuclear reactors. The 85Since potassium oxide (Kr) is a rare gas, its movement within the reactor and the presence of even the smallest crack can be monitored, allowing for checks on the condition 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 3 H on water samples. However, liquid scintillation cannot be performed on other radioactive gases. In particular, the solubility of 85 Kr is very low in scintillating liquid.

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

[0009] Organic scintillators and metal-organic frameworks (MOFs) used in current detectors are subject to contamination over time due to the capture of radionuclides, for example, by isotopic exchange of 3 H. This results in a memory effect that limits the possibility of performing real-time measurements.

[0010] One aim of the invention is to provide a compact detection device for gaseous radionuclides.

[0011] Another objective of the present invention is to provide a device for detecting a radioactive gas which allows the properties of the scintillator to be easily restored or changed.

[0012] It is yet another 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 scintillation unit configured to contain the gas to be analyzed, the scintillation 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 and for circulating it in the scintillator,

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

[0016] - an enclosure opaque to photons outside the enclosure allowing the entry and exit of the radioactive gas and in which the scintillating unit and the detection means are arranged, the opaque enclosure comprising a rapid opening / closing system and being openable and recloseable to allow access to the scintillating unit.

[0017] The device for detecting radionuclides in a gas includes an inorganic scintillator. An inorganic scintillator has the advantage of not being subject to radionuclide uptake during measurements; that is, it does not adsorb the gas being analyzed. Contamination of the scintillator over time is therefore avoided, or at least minimized. Thus, inorganic scintillators have the advantage of not exhibiting a memory effect that can complicate the analysis of measurements.

[0018] The gas to be analyzed is not stored or absorbed in the scintillator, but is circulated in it through at least one opening present in the container encapsulating the scintillator due to its porosity.

[0019] Thanks to the presence of a hinged and resealable enclosure with a quick-release opening / closing system, the scintillator unit of the device, as a sensitive component, can be removed for replacement, decontamination, or regeneration. Regeneration of the inorganic scintillator, in particular, extends its lifespan compared to state-of-the-art scintillators, which is advantageous given the high cost of a porous inorganic scintillator.

[0020] Regeneration allows for the decontamination of the scintillator, for example by heating it in an oven at temperatures exceeding 100°C. This decontamination is particularly necessary when tritiated water is present, as it can accumulate in the scintillator. Both the scintillator and its container can be directly heated in the oven, thus minimizing handling of the potentially fragile scintillating material.

[0021] A quick opening / closing system is defined as any system or means that allows the enclosure to be opened and closed easily and quickly, without the need for tools or external fasteners such as screws.

[0022] Since the enclosure is lightproof, the device's detection means are protected from ambient light.

[0023] The device according to the invention also represents a very compact detector, having for example dimensions of a few tens of cubic centimeters.

[0024] 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, whether radionuclides are present in the gas at the time of measurement. The device provides a signal only when radionuclides are present in the gas. Depending on the calibration of the device, it can also identify the type of radionuclide present in the gas, if any.

[0025] 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 layer that is reflective for photons emitted by the porous inorganic scintillator.

[0026] 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 the photons emitted by the porous inorganic scintillator.

[0027] Advantageously, the inlet and outlet for the radioactive gas are opaque to, or isolated from, surrounding light.

[0028] Opacity can be achieved, for example, by the geometric shape of the inlet and outlet, and / or by an absorbing layer or absorbing material.

[0029] According to one embodiment, the detection means include at least one photodetector, and advantageously a photomultiplier.

[0030] Advantageously, the detection means include two photomultipliers.

[0031] The presence of two photomultipliers helps to limit the thermal noise of the photomultipliers generating pulses correlated to the actual pulse due to the device's own motion and to increase the detection efficiency.

[0032] Alternatively, the device according to the invention can be equipped with a single photomultiplier tube. In this case, the device is suitable for detecting high-energy radioactive gases.

[0033] The device according to the invention may further include a particle filter configured to filter aerosols and allow gases to pass through.

[0034] The filter helps to protect the inorganic scintillator from contamination by dust or other aerosol-type particles entering the device.

[0035] The device according to the invention may also include a pump configured to better circulate the radioactive gas in the scintillation unit.

[0036] The pump, preferably a micro-pump, helps to improve the circulation of radioactive gas in the scintillation unit.

[0037] 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.

[0038] 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.

[0039] The device according to the invention may further include a compressor configured to increase the pressure of radioactive gas in the scintillating unit.

[0040] According to one embodiment, the device according to the invention may further include a lead shielding enclosure surrounding the opaque enclosure.

[0041] The shielding enclosure helps to reduce the noise of natural radioactivity.

[0042] According to one embodiment, the shielding enclosure can be surrounded by an additional scintillator, in particular a plastic scintillator, provided with additional detection means.

[0043] The presence of an additional scintillator makes it possible to implement a technique called "cosmic veto" to reduce noise due to external ionizing radiation from the environment.

[0044] As an example, the additional scintillator could be a plastic scintillator.

[0045] Depending on the embodiment, the scintillator can have a specific surface area between 50 and 1000 m² 2 / g and preferably between 100 and 500 m 2 / g

[0046] The porous inorganic scintillator is an inorganic scintillator exhibiting a scintillation yield in the crystal state ideally greater than 10,000 photons per MeV and a scintillation decay time of less than 500 ns, preferably less than 100 ns, such as, for example, a Y3Al5O aerogel 12 Ce doped, Ce doped Y2SiO5, Ce doped YPO4.

[0047] In a degraded version (yield less than 10000 photons per MeV), the porous inorganic scintillator may include Ce-doped SiO2.

[0048] 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.

[0049] The control unit can be configured to implement an event counting process based on a number of coincidence windows.

[0050] The gas to be analyzed can include air.

[0051] The detection device according to the present invention can be implemented in a method for detecting radionuclides in a gas.

[0052] 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 absence of radionuclides in the gas.

[0053] The detection device and method according to the present invention can in particular be used to detect pure beta-emitting radionuclides, i.e., those emitting only electrons, such as tritium ( 3 H) and krypton-85 ( 85 Kr) who are involved in nuclear activities.

[0054] The detection device according to the present invention can be implemented in particular for monitoring the operation of nuclear reactors as well as the territory for nuclear activities, in particular for activities related to energy production and the recycling and storage of nuclear waste.

[0055] 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

[0056] Other advantages and features will become apparent from the detailed description of non-limiting examples and the accompanying drawings in which: a schematic representation of a scintillation unit of a radionuclide detection device in a gas according to an embodiment of the present invention; a schematic representation of a detection block of a radionuclide detection device according to an embodiment of the invention; a schematic representation of a sealed enclosure of a radionuclide detection device according to an embodiment of the invention; a schematic representation of a detection block of a radionuclide detection device according to another embodiment of the invention; and a schematic representation of a radionuclide detection device according to an embodiment of the present invention.

[0057] It is understood that the embodiments described below are by no means exhaustive. In particular, all the variants and embodiments described are combinable with each other provided there are no technical obstacles to such combination.

[0058] In the figures, elements common to several figures can retain the same reference.

[0059] The radionuclide detection device according to the invention includes a scintillator configured to contain or circulate the radioactive gas, as well as detection means for detecting photons emitted by the scintillator due to radionuclide decays.

[0060] The detection means include one or more photodetectors. For example, the measurement means may include one, two, or three photodetectors, such as photomultiplier tubes, depending on the measurement mode applied.

[0061] The scintillator is exposed to the gas in a sealed container. The radiation from 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. Generally, to eliminate the inherent noise of the photodetectors, an event is considered valid if at least two photons are detected within a specific time window. An "event" corresponds to a radioactive decay.

[0062] The volume of the scintillator is directly proportional to its sensitivity, within the limits of the scintillator's transparency to the emitted photons and the diffusion time of the radioactive gas to be measured.

[0063] The photodetector(s) can 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.

[0064] Lare represents schematically, in a lateral 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.

[0065] 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. 2 / g, and preferably between 100 and 500 m2 / g.

[0066] Preferably, the porous inorganic scintillator 2 comprises a Y3Al5O aerogel 12 doped.

[0067] 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.

[0068] Scintillator 2 may also include Ce-doped Y2SiO5, or Ce-doped YPO4.

[0069] In a degraded version (yield less than 10000 photons per MeV), the porous inorganic scintillator can include Ce-doped SiO2, or glass.

[0070] The scintillator 2 can be in the form of a set of scintillating capillaries, for example from 10 µm to 2 mm in diameter.

[0071] Scintillant 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.

[0072] Preferably, scintillator 2 is in the form of a porous scintillator with pores on the order of a hundred nanometers.

[0073] The scintillating unit 1 further includes a hermetically sealed container 3 containing the inorganic scintillator 2.

[0074] In this embodiment, 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.

[0075] Container 3 is made of metal, and preferably stainless steel.

[0076] Windows 4 and 5 can be made of glass or quartz, for example.

[0077] Container 3 must withstand a certain internal pressure, which can go up to 10 bar, for example.

[0078] 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 increases the sensitivity of the device.

[0079] 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.

[0080] In the embodiment shown in the figure, the container 3 includes an inlet 7 and an outlet 8 for radioactive gas. 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, allowing the circulation of ambient radioactive gas.

[0081] To prevent ambient light from entering scintillator 2, the shape of the inlet / outlet tubes is chosen to block the light. The tubes can, for example, be spiral or serpentine in shape. Additionally, the inner walls of the tubes can be coated with an absorbent layer, such as black paint.

[0082] As an example, the tube(s) may have a spiral shape with a length of approximately 20 cm, an internal diameter of 4 mm and an external diameter of 6 mm.

[0083] To prevent dust or other foreign matter from entering and degrading the scintillator, a filter (not shown) may be provided upstream of the inlet opening.

[0084] Lare represents schematically a detection block of a device for detecting radionuclides in a radioactive gas according to an embodiment of the present invention.

[0085] The detection block 11 of the device according to the invention comprises a scintillating unit 1, for example as described in relation to the.

[0086] The detection block 11 further includes detection means configured to detect photons emitted by the scintillator.

[0087] In the embodiment shown in the figure, the detection means comprise two photodetectors 9, 10. These are preferably photomultipliers.

[0088] Photodetectors 9, 10 are arranged on the flat faces of the cylinder 3, i.e., the windows 4, 5. Photodetectors 9, 10 detect the light emitted by the scintillator and passing through the windows 4, 5.

[0089] The photodetectors 9, 10 can be coupled to the windows 9, 10 using an index gel or optical grease for refractive index adaptation.

[0090] As shown in the figure, the detection block 11 includes an enclosure 12 surrounding the detection block 1.

[0091] The enclosure 12 is an opaque, or photon-tight, encapsulation chamber. 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 the figure, the inlet tube 7 and outlet tube 8 of the detection unit 1 each pass through an opening 13, 14 of the enclosure.

[0092] The enclosure 12 is preferably made of metal, but can also be made of polymer. The enclosure 12 is lightproof. The enclosure 12 is preferably black, or at least highly light-absorbing.

[0093] In the device according to the invention, the enclosure 12 is openable and / or removable. It is completely detachable. The enclosure 12 includes a quick opening / closing system, allowing for its rapid and easy opening and closing.

[0094] Lamontre, in a top view and a front view, shows an example of the hinged and closable enclosure 12. In the example, the enclosure 12 is made of two parts 12a, 12b. The two parts 12a, 12b are connected by at least one hinge 15 to allow the enclosure 12 to be opened and closed.

[0095] The two parts 12a, 12b can be closed, for example, by one or more toggle latches.

[0096] Of course, any other suitable quick opening / closing system can be used.

[0097] The enclosure 12 can therefore be easily opened and closed. After closing, the enclosure 12 returns to its state before opening, in a reproducible manner.

[0098] This allows for easy removal of the scintillating unit 1 from the device. The scintillating unit 1 can then be regenerated or replaced.

[0099] The scintillator unit 1 can be subjected to heat treatment (up to 600 °C) in dry air or other atmospheric conditions to regenerate the inorganic scintillator. Regeneration involves decontaminating the scintillator, which may occur in cases of high water or tritiated water contamination, for example, thus extending its service life. The scintillator can then be reused, which is advantageous given the high cost of an inorganic scintillator.

[0100] To increase the amount of gas in the scintillation unit while maintaining the same detection volume, a compressor and an outlet valve can be installed at the device's inlet. This increases the pressure within the scintillation unit, proportionally increasing its detection sensitivity. The container and its windows must be adapted to withstand the increased pressure, particularly in terms of sealing. The pressure in the scintillation unit can, for example, be increased by a factor of 10.

[0101] Lare represents schematically another variant of a detection block of a radionuclide detection device in a radioactive gas according to another embodiment of the present invention.

[0102] In the embodiment of the, a detection block 11, for example as described with reference to the, is surrounded by a shielding enclosure 17. The shielding enclosure 17 therefore surrounds the sealed enclosure 12 of the detection block 11.

[0103] The shielding enclosure 17 is preferably made of lead.

[0104] An additional scintillator 16, preferably made of plastic, surrounds the shielding enclosure, or shielding layer 17.

[0105] The device also includes additional detection means operating with the additional scintillator 16. The additional detection means include at least one additional photodetector 19 arranged adjacent to the additional scintillator 16.

[0106] Lamontre also the gas inlet 7 and outlet 8.

[0107] The shielding layer 17 helps to reduce the self-movement of the device, that is to say, the noise caused by natural external ionizing radiation, on the measurements taken.

[0108] The additional scintillator 16, with the additional detection means, also makes it possible to reduce the self-movement of the device.

[0109] In particular, the additional scintillator 16 enables the implementation of a cosmic veto. External radiation present in the environment, such as cosmic rays or gamma radiation, produces events that can be detected by the two scintillators 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 additional scintillator at the same time (coincidentally), the event is not counted in the inorganic scintillator.

[0110] The action of the shielding layer 17 and that of the additional scintillator 16 can be combined, as is the case for the embodiment shown in the figure.

[0111] According to another embodiment, the device according to the invention may include a shielding layer surrounding the sealed enclosure, without an additional scintillator surrounding the shielding layer.

[0112] Depending on the variant, the armor layer can be more or less thick.

[0113] As an example, the device according to the invention may include a 5 cm thick shielding layer and no additional scintillator. The noise caused by the device's own motion can then be reduced tenfold. The detection limit of the device is increased by the same factor.

[0114] In another example, the device according to the invention may include a 10 cm thick shielding layer and no additional 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.

[0115] In yet another example, the device according to the invention may include a 15 cm thick shielding layer and an additional scintillator. The noise caused by the device's own motion can then be reduced by a factor of 400. The detection limit of the device is increased by the same factor.

[0116] Lare represents schematically a device for detecting radionuclides in a radioactive gas according to an embodiment of the present invention.

[0117] Device 101 may include components as described for example in relation to the embodiment shown in the.

[0118] The gas inlet 107 and outlet 108 each include a serpentine portion 107a, 108a.

[0119] Device 101 includes a pump, specifically a micro-pump 121, which provides efficient circulation of the air to be analyzed within 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.

[0120] 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.

[0121] A power supply circuit for 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 power the two photodetectors (the power supplies being designated HV-A and HV-B). The power supplies for the photodetectors are matched to achieve identical performance between the two detectors.

[0122] 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.

[0123] 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 processes measured pulses and counts coincidences. In the example shown, the coincidence unit 125 performs coincidences between the SA and SB signals detected by the two photodetectors. One or two different coincidence windows can be implemented.

[0124] 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.

[0125] Two additional coincidence windows can be implemented in the device according to the invention. Their temporal width is significantly 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 times between these two windows allows for the measurement of the rate of random coincidences and the application of a correction to the measurement of the number of detected events.

[0126] The detection device according to the present invention can be implemented in a method for detecting radionuclides in a gas.

[0127] The device according to the present invention can in particular be used to detect or not radionuclides in a gas, in order to verify the presence or absence of radionuclides in the gas and to determine whether a gas is radioactive or not.

[0128] 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.

[0129] 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, a radioactive decay resulting in the emission of a photon by the scintillator.

[0130] 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.

[0131] It is therefore 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.

[0132] 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.

[0133] In particular, if the device has 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 being 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 being analyzed.

[0134] 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

Device (101) for detecting a radionuclide in a gas, the device comprising: a scintillating unit (1) configured to contain the gas, the scintillating unit (1) comprising a porous inorganic scintillator (2) and a container (3) containing the porous inorganic scintillator (2) and comprising at least a part 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 entry and exit of the gas and to circulate it in the scintillator (2), detection means (9, 10) configured to detect photons emitted by the porous inorganic scintillator (2), and an enclosure opaque (12) to photons outside the enclosure (12) allowing the entry and exit of the gas and in which the scintillating unit (1) and the measurement means (9, 10) are arranged,the opaque enclosure (12) comprising a quick opening / closing system (15) and being openable and closable to allow access to the scintillating unit (1). 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). Device (101) according to any one of the preceding claims, characterized in that the detection means (9, 10) comprise at least one photomultiplier. 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). Device (101) according to claim 4, characterized in that the shielding enclosure (17) is surrounded by an additional scintillator (16) provided with additional detection means (19). Device (10) according to claim 5, characterized in that the additional scintillator (16) is a plastic scintillator. 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 2 / g and preferably between 100 and 500 m 2 / g. 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. 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. 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: circulating the gas in a scintillating unit, detecting, by the detection means (9, 10), photons emitted by the porous inorganic scintillator (2), counting coincidences, each coincidence corresponding to a decay of a radionuclide, and emitting a counting signal for counts greater than zero, the counting signal indicating the presence of radionuclides in the gas.

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