Kr-85 portable detection device based on plastic flash detector and SiPM

Abstract

The invention discloses a portable Kr-85 detection device based on a plastic flash detector and SiPM, and relates to the technical field of radioactive gas detection, and the device is composed of an equipment shell, an exhaust pipeline system and a measurement and detection system. By adopting a detection combination of combining a plastic flash detector and SiPM, the size of the detector is effectively reduced, so that the whole detection device is lighter and more portable, beta rays and gamma rays can be detected at the same time, the influence of the gamma rays on beta ray detection is eliminated, and the measurement accuracy is improved; the detection efficiency and the detection lower limit are remarkably enhanced, through the design, the problems that in the prior art, equipment is large in size, slow in response, low in detection efficiency and the like are successfully solved, the effect of rapidly and accurately detecting Kr-85 is achieved, the requirement for portable detection is met, environmental safety and health of workers can be better guaranteed in practical application, and the detection cost is lowered. The popularization and use are convenient.

Description

Technical Field

[0001] The invention relates to the technical field of radioactive gas detection, in particular to a Kr-85 portable detection device based on a plastic scintillation detector + SiPM. Background Art

[0002] Kr-85 is a radioactive gas in the fission products during the reprocessing of nuclear fuel assemblies. When U-235 fuel fissions, Kr-85 will be produced in a certain yield, about 0.293%, with a half-life of 10.74 years. It exists in the environment for a long time, and its half-life is similar to the cooling treatment cycle of spent fuel assemblies. Measuring Kr-85 is of great significance. There are radioactive materials in nuclear fuel reprocessing sites, and the radioactivity level of Kr-85 is directly related to environmental safety and the health of workers. Accurate monitoring of its activity can timely detect potential leaks or abnormal emissions, help evaluate the operating status of nuclear facilities, take appropriate measures to prevent the spread of radioactive contamination, ensure that the environment is not excessively harmed by radioactive materials, and protect workers from excessive radiation. It is also crucial to the compliance operation of nuclear facilities and the public's trust in nuclear activities.

[0003] At present, there are many problems with the existing technology in monitoring radioactive gas activity. The offline sampling and measurement mode has a complicated process, and the Kr-85 sample must be enriched before measurement. It has obvious measurement lag and cannot respond quickly to changes in gas activity. The ionization chamber detector commonly used in the online monitoring mode has low detection efficiency because Kr-85 decays mainly in the form of β rays, and a small amount of low-energy γ rays are easily absorbed and shielded by the outer layer of the ionization chamber detector. Therefore, it is necessary to propose a portable Kr-85 detection device based on plastic scintillation detector + SiPM to solve the problems in the existing technology. Summary of the invention

[0004] In order to make up for the shortcomings of the prior art, the present invention provides a Kr-85 portable detection device based on plastic scintillation detector + SiPM, which can make the detection device as a whole more lightweight and portable, can detect β rays and γ rays at the same time, and eliminate the influence of γ rays on β ray detection, thereby improving measurement accuracy and significantly enhancing detection efficiency and detection lower limit.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a Kr-85 portable detection device based on plastic flash detector + SiPM, which consists of three parts: a shell, an exhaust pipeline system, and a measurement and detection system. The overall dimensions of the device are 250mm×240mm×356mm, and the weight is about 11.3kg;

[0006] The device housing is made of 304L stainless steel plate with a thickness of 1.5mm. The outer surface is sprayed with plastic and has a rounded corner design. It is equipped with a power switch, an air pump switch, an RS485 data transmission interface, two quick-twist pagoda interfaces, an audible and visual alarm device, a glass rotor flowmeter, an air pump switch, and a host display processing unit with an integrated 7-inch touch screen. There is also a lightweight aluminum alloy handle installed on the top of the device. A group of supporting feet are arranged on the bottom surface of the device housing. The power switch is used to connect to a 220V power supply. The RS485 data transmission interface is used for debugging and connecting to a computer to export data. The quick-twist pagoda interface serves as the air inlet and outlet of the air extraction pipeline. The audible and visual alarm device is used to issue an audible and visual alarm when the radioactivity is abnormal. The glass rotor flowmeter is used to adjust the air intake flow of the pipeline. The air extraction pump switch controls the start and stop of the air extraction pump.

[0007] The exhaust pipeline system is mainly installed inside the equipment and consists of an inlet and outlet interface, an inert gas measurement chamber, a glass rotor flowmeter, a gas mass flowmeter, and an exhaust pump. The equipment is connected by a PU hose and the interface is reinforced to ensure air tightness. The inert gas measurement chamber is made of stainless steel and is equipped with two detector interfaces and an inlet and outlet interface. The interior is a cylindrical measurement structure with a diameter of 70 mm and a height of 50 mm, with a total volume of about 192 cm 3 The glass rotor flowmeter is a micro-flow type with a range of 1.5-15L / min, installed on the front of the equipment housing. The gas mass flowmeter is a high-precision thermal micro gas mass flowmeter with an operating voltage of 5V, powered by the host display processing unit, with a working range of 0.2-20L, fixed at the bottom of the equipment. The vacuum pump is a micro vacuum pump with an operating voltage of 24V, a peak flow of 1.5-15L / min, and a relative vacuum degree of ≤-88kPa;

[0008] The measurement and detection system is composed of a power module, a detector part, a host display processing unit, and an audible and visual alarm lamp. The power module supplies power to each component. The detector part includes a detector housing, a carbon fiber protection plate, a β detection crystal, a β light guide, a β silicon photomultiplier tube, a γ detection crystal, a γ light guide, a γ silicon photomultiplier tube, and a signal processing board. The carbon fiber protection plate is in contact with radioactive gas, is acid-proof and corrosion-resistant, and is easy to clean. The β detection crystal is a common plastic scintillator with an effective size of φ70 mm×1 mm and a detection area of ​​about 38 cm 2 The surface layer has an aluminum film with a thickness of 10 μm, and the organic glass light guide is closely attached to it. The γ detection crystal is a high β / γ type plastic scintillator with an effective size of φ70 mm×1 mm and a detection area of ​​about 38 cm 2 The SiPM array has an operating high voltage of about 28.5-29V and a power consumption of about 2W.

[0009] Furthermore, the main display interface of the host display processing unit displays the detector measurement value, activity concentration working curve, alarm status, date and time, alarm threshold, detector status, and alarm buzzer status information, wherein the activity concentration working curve display interface has a default display time of 10 minutes, and 1 hour and 10 hour working curves are available.

[0010] Furthermore, the parameter setting interface of the host display processing unit displays the number, event log, host communication status, detector type, and SD card status information. The conversion parameters, calibration factors, background subtraction factors, and data display length parameters can be set, and the measurement data is recorded to the machine and can be exported as needed.

[0011] Furthermore, the detector interface of the inert gas measurement cavity is arranged on the upper and lower surfaces of the measurement cavity, the air inlet is arranged below the front surface, and the air outlet is arranged above the rear surface. The gas to be measured enters the measurement cavity from the air inlet, flows out of the measurement cavity, passes through the gas mass flowmeter and the glass rotor flowmeter in sequence, and then passes through the vacuum pump and returns to the measurement pipeline from the air outlet.

[0012] Furthermore, there are 7 β silicon photomultiplier tubes and 7 γ photomultiplier tubes, with an effective sensitive area of ​​6 mm×6 mm, arranged in a 2+3+2 array, and the center distance between adjacent SiPMs is 10 mm.

[0013] Furthermore, the operating voltage of the signal processing board is 3.3V, the communication circuit on the signal board uses the RS485 protocol to communicate with the host display processing unit, and the operating voltage of the high-voltage circuit is 28.5V-29V. The specific high-voltage value can be corrected by the built-in temperature compensation algorithm and set by connecting to the host computer software.

[0014] Furthermore, the power module uses MEAN-WELLHDR-30-12 and HDR-60-24, which can output +12V and +24V voltages to power the detector part, the host display processing unit, the sound and light alarm device, the vacuum pump and the gas mass flow meter.

[0015] Furthermore, the sound and light alarm device is a Rambo LB22FM buzzer with an operating voltage of 12V, the vacuum pump is a Hilintec 42V micro vacuum pump with a working flow rate of 8.15L / min, the glass rotor flowmeter is a Changzhou Shuanghuan LZB-6WB type, and the gas mass flowmeter uses a Hangzhou Lihua MFM-20 high-precision thermal micro gas mass flowmeter, which uses the RS485 protocol to upload flow information to the host display processing unit, and the host computer interface is a 2B five-core Remo plug for connecting external devices for data transmission and control operations.

[0016] Furthermore, the signal processing board is composed of a power supply circuit, a signal amplification and shaping circuit, a high-voltage regulation circuit and a communication circuit. The power supply circuit is externally connected to a power supply and supplies power to various components of the signal processing board. The signal amplification and shaping circuit includes a preamplifier circuit, a discrimination circuit and a shaping processing circuit. The signal collected by the SiPM is processed into a voltage pulse signal and transmitted to the host. The preamplifier circuit amplifies and shapes the radioactive signal detected by the probe. The discrimination circuit performs pulse amplitude discrimination and width discrimination on the signal to identify β and γ signals. The shaping circuit performs shaping processing on the discriminated β and γ signals and outputs the β and γ ray count values ​​per unit time. The high-voltage regulation circuit provides normal operating voltage for the SiPM.

[0017] Furthermore, the communication circuit supports RS485 communication and RJ45 communication, which is used to set the detector working parameters and transmit signals to the host. The host display processing unit controls the circuit output parameters through the supporting data acquisition and analysis software, receives and processes the signal and outputs the final counting result of the sample. The data processing algorithm is equipped to calculate the output after deducting the γ effect from the pulse signal. It can be connected to a computer for synchronous display and record saving, and the built-in SD storage card is used to store and export measurement data.

[0018] Compared with the existing technology, the Kr-85 portable detection device based on plastic scintillation detector + SiPM has the following beneficial effects:

[0019] The present invention adopts a detection combination of a plastic scintillation detector and a SiPM, which effectively reduces the size of the detector, making the detection device as a whole more lightweight and portable, and can detect β rays and γ rays at the same time, and eliminate the influence of γ rays on β ray detection, thereby improving measurement accuracy. A dual-detector 4π composite structure is adopted to significantly enhance the detection efficiency and detection lower limit. Through these designs, the problems of large equipment size, slow response, and low detection efficiency existing in the prior art are successfully solved, and the effect of rapid and accurate detection of Kr-85 is achieved, meeting the needs of portable detection, and can better ensure environmental safety and staff health in practical applications, which is convenient for promotion and use.

[0020] Other advantages, objectives and features of the present invention will be set forth in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 This is the right view of the Kr-85 portable detection device based on plastic scintillation detector + SiPM;

[0023] Figure 2 This is the front view of the Kr-85 portable detection device based on plastic scintillation detector + SiPM;

[0024] Figure 3 This is the internal structure diagram of the Kr-85 portable detection device based on plastic scintillation detector + SiPM;

[0025] Figure 4 This is the structural diagram of the detector part of the Kr-85 portable detection device based on plastic scintillation detector + SiPM;

[0026] Figure 5 Schematic diagram of the silicon photomultiplier tube array of the Kr-85 portable detection device based on plastic scintillation detector + SiPM;

[0027] Figure 6 This is the detection flow chart of the Kr-85 portable detection device based on plastic scintillation detector + SiPM.

[0028] In the figure: 1. Detector part; 2. Detector shell; 3. Carbon fiber protection plate; 4. β detection crystal; 5. β light guide; 6. β silicon photomultiplier tube; 7. γ detection crystal; 8. γ light guide; 9. γ silicon photomultiplier tube; 10. Signal processing board; 11. Power supply circuit; 12. Communication circuit; 13. High voltage circuit; 14. Signal amplification and forming circuit; 15. Handle; 16. Support foot 16; 17. Host display processing unit; 18. Power module; 19. Sound and light alarm device; 20. Vacuum pump; 21. Glass rotor flowmeter; 22. Gas mass flowmeter; 23. Inert gas measurement chamber; 24. Air pump switch; 25. Inlet and outlet joints; 26. Power switch; 27. Upper computer interface; 28. Equipment shell. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Embodiment 1

[0031] The Kr-85 portable detection device based on plastic flash detector + SiPM of this embodiment has an overall size of 250mm×240mm×356mm and weighs about 11.3kg. It is mainly composed of three parts: equipment housing 28, exhaust pipeline system, and measurement and detection system. The equipment housing 28 is made of 304L stainless steel plate with a thickness of 1.5mm. Its outer surface is sprayed with plastic and has a rounded corner design, which is not only beautiful but also safe. Multiple functional components are arranged on the housing 28. The power switch 26 is used to connect to an external 220V power supply to power the entire device; the RS485 data transmission interface is used for data transmission with external equipment, which can be used for debugging the device and exporting the detection data to a computer for further analysis. The two quick-screw pagoda interfaces 25 are respectively used as the air inlet and outlet of the exhaust pipeline. Its special quick-screw design makes it more convenient and quick to connect the exhaust pipeline, and the connection is tight to ensure air tightness.

[0032] The sound and light alarm device 19 plays a key role when the radioactivity is abnormal. It can send out sound and light alarm signals in time to remind the staff to pay attention to safety. The glass rotor flowmeter 21 is installed on the front of the equipment housing 28, with a range of 1.5-15L / min. The operator can accurately control the pipeline air intake flow by adjusting its valve to ensure that the gas flow is stable and appropriate during the detection process. The vacuum pump 20 switch is responsible for controlling the start and stop of the vacuum pump 20, thereby controlling the flow of gas in the entire device. In addition, a handle 15 made of lightweight aluminum alloy is installed on the top of the housing 28 to facilitate the staff to carry the device, and a group of support feet 16 arranged on the bottom make the device more stable.

[0033] The exhaust pipeline system is mainly installed inside the equipment, and consists of air inlet and outlet interfaces, an inert gas measurement chamber 23, a glass rotor flowmeter 21, a gas mass flowmeter 22, and an exhaust pump 20. The components are connected by PU hoses, and the interfaces are reinforced to effectively ensure the airtightness of the entire exhaust pipeline system. The inert gas measurement chamber 23 is made of stainless steel, and has a cylindrical measurement structure with a diameter of 70 mm and a height of 50 mm. The total volume is about 192 cm3, and two detector interfaces are provided for connecting the detector part 1, as well as the air inlet and outlet interfaces connected to the exhaust pipeline.

[0034] The gas enters the measuring cavity 23 from the air inlet, and after interacting with the detector part 1 in the cavity, it flows out from the air outlet. The glass rotor flowmeter 21 plays the role of regulating and monitoring the gas flow in the air inlet pipe, and cooperates with the gas mass flowmeter 22 to ensure the accuracy of the gas flow entering the measuring cavity 23. The gas mass flowmeter 22 is a high-precision thermal micro gas mass flowmeter 22, with an operating voltage of 5V, powered by the host display processing unit 17, and its working range is 0.2-20L. It is fixed at the bottom of the device and can accurately measure the gas mass flow rate and transmit the flow information to the host display processing unit 17 through the RS485 protocol. The vacuum pump 20 is a miniature vacuum pump with an operating voltage of 24V, a peak flow rate of 1.5-15L / min, and a relative vacuum degree of ≤-88kPa. It provides power for the entire vacuum pipeline system, allowing the gas to flow stably in the device to ensure the smooth progress of the detection process.

[0035] The measurement and detection system is the core part of the device, which consists of a power module 18, a detector part 1, a host display processing unit 17, and an audible and visual alarm lamp. The power module 18 is selected

[0036] MEAN-WELLHDR-30-12 and HDR-60-24 can output +12V and +24V voltages, providing stable power support for components such as the detector part 1, the host display processing unit 17, the sound and light alarm device 19, the vacuum pump 20, and the gas mass flow meter 22.

[0037] The detector part 1 includes a detector housing 2, a carbon fiber protection plate 3, a β detection crystal 4, a β light guide 5, a β silicon photomultiplier tube 6, a γ detection crystal 7, a γ light guide 8, a γ silicon photomultiplier tube 9, and a signal processing board 10. The carbon fiber protection plate 3 is in direct contact with the radioactive gas, has the characteristics of acid resistance and corrosion resistance, and has a smooth surface that is easy to clean, and can effectively protect the internal detection elements.

[0038] The β detection crystal 4 is a common plastic scintillator with an effective size of φ70mm×1mm and a detection area of ​​about 38cm 2 The 10μm aluminum film on the surface plays a role in light protection and pollution prevention. The organic glass light guide closely attached to it can efficiently transmit the photons generated by the β detection crystal 4 to the β silicon photomultiplier tube 6. The γ detection crystal 7 is a high β / γ type plastic scintillator with an effective size of φ70mm×1mm and a detection area of ​​about 38cm 2 , which can be used to detect β rays and most γ rays. There are 7 β silicon photomultiplier tubes 6 and 7 γ photomultiplier tubes 9, with an effective sensitive area of ​​6mm×6mm, arranged in a 2+3+2 array. The center distance between adjacent SiPMs is 10mm. This arrangement can improve the accuracy and uniformity of detection.

[0039] The SiPM array has an operating voltage of about 28.5-29V and a power consumption of about 2W. It converts optical signals into electrical signals under the action of high voltage. The signal processing board 10 has an operating voltage of 3.3V. The power supply circuit 11 is connected to an external power supply and supplies power to the components of the signal processing board 10. The signal amplification and shaping circuit 14 includes a preamplifier circuit, a discrimination circuit, and a shaping processing circuit. The preamplifier circuit amplifies and shapes the radioactive signal detected by the probe to meet the subsequent processing requirements; the discrimination circuit accurately identifies the β and γ signals by performing pulse amplitude discrimination and width discrimination on the signal; the shaping processing circuit shapes the β and γ signals after discrimination, and outputs the β and γ ray count values ​​per unit time. The high-voltage regulation circuit provides normal operating voltage for the SiPM. The communication circuit 12 uses the RS485 protocol to communicate with the host display processing unit 17, which can set the detector working parameters and transmit signals to the host.

[0040] The host display processing unit 17 integrates a 7-inch touch screen, controls the circuit output parameters through the supporting data acquisition and analysis software, receives, processes signals and outputs the final counting results of the samples. The data processing algorithm can calculate and output the pulse signal after deducting the γ effect. It can be connected to a computer for synchronous display and save records. The built-in SD storage card is used to store and export measurement data. Its main display interface can display the detector measurement value, activity concentration working curve, alarm status, date and time, alarm threshold, detector status, alarm buzzer status and other information. The default display time of the activity concentration working curve display interface is 10 minutes, and 1 hour and 10 hour working curves are optional. The parameter setting interface can display the number, event log, host communication status, detector type, SD card status and other information. The conversion parameters, calibration factors, background subtraction factors and data display length and other parameters can be set, and the measurement data are recorded to the machine and can be exported as needed. The sound and light alarm device 19 is a blue wave LB22FM type buzzer with an operating voltage of 12V. When abnormal radioactivity is detected, a sound and light alarm is issued.

[0041] Embodiment 2

[0042] Assembly and initialization of the device: First, assemble the various components of the Kr-85 portable detection device based on the plastic flash detector + SiPM, install the device housing 28, ensure its stability, and ensure that the various interfaces and components on the housing 28 are installed in the correct positions. Install the power switch 26, RS485 data transmission interface, two quick-screw pagoda interfaces 25, sound and light alarm device 19, glass rotor flowmeter 21, vacuum pump 20 switch, host display processing unit 17 and other components correctly in the corresponding positions of the device housing 28, and check whether their connections are firm. Install a lightweight aluminum alloy handle 15 on the top of the device housing 28, and install a set of support feet 16 on the bottom.

[0043] Next, install the exhaust pipeline system, connect the inlet and outlet interfaces, inert gas measurement chamber 23, glass rotor flowmeter 21, gas mass flowmeter 22, exhaust pump 20 and other components with PU hoses. During the connection process, reinforce the interfaces to ensure air tightness. For the measurement and detection system, install the power module 18 in a suitable position and connect the power supply lines to supply power to other components.

[0044] Assemble the detector housing 2, carbon fiber protection plate 3, β detection crystal 4, β light guide 5, β silicon photomultiplier tube 6, γ detection crystal 7, γ light guide 8, γ silicon photomultiplier tube 9, signal processing board 10 and other components of the detector part 1 according to the design requirements, ensure that the connection between the components is tight and correct, the power supply circuit 11 on the signal processing board 10 is externally powered, the communication circuit 12 is connected to the host display processing unit 17 through the RS485 protocol, and the high-voltage regulation circuit provides normal working voltage for the SiPM.

[0045] The host display processing unit 17 is installed on the device housing 28, and the data transmission lines with other components are connected, such as the signal transmission line with the detector part 1, the RS485 communication line with the gas mass flowmeter 22, etc. In the initialization stage, turn on the power switch 26, the power module 18 starts to work, and supplies power to the host display processing unit 17, the detector part 1, the vacuum pump 20, the gas mass flowmeter 22 and other components. The host display processing unit 17 starts, and its 7-inch touch screen lights up, showing the startup interface. At the same time, the communication status of each component is checked, such as whether the communication with the detector part 1, the gas mass flowmeter 22, etc. is normal. At this time, the vacuum pump 20 is in the off state, and the glass rotor flowmeter 21 and the gas mass flowmeter 22 are in the standby state, waiting for subsequent operation instructions.

[0046] Preparation and settings before testing: Before conducting Kr-85 testing, a series of preparations and settings are required. Through the parameter setting interface of the host display processing unit 17, the operator can view information such as the number, event log, host communication status, detector type, SD card status, etc. According to the detection requirements, the conversion parameters, calibration factors, background subtraction factors, and data display length are set. For example, the calibration factor is set according to the characteristics of the known Kr-85 standard sample to improve the accuracy of the measurement; the background subtraction factor is set according to the background radiation conditions of the detection environment to reduce interference.

[0047] After the setup is completed, connect the air inlet of the exhaust pipeline to the gas source to be tested through the quick-tightening pagoda interface 25, and connect the air outlet to a suitable discharge position (if discharge is required). Check whether the exhaust pipeline connection is tight to ensure that there is no gas leakage. Open the valve of the glass rotor flowmeter 21, adjust the intake flow rate to a suitable range, and generally adjust the flow rate between 1.5-15L / min according to the detection requirements and sample characteristics. At the same time, the gas mass flowmeter 22 starts working to measure and monitor the gas flow rate. It transmits the flow information to the host display processing unit 17 in real time through the RS485 protocol. The host display processing unit 17 displays the current gas flow rate on the display screen. At this time, the carbon fiber protective plate 3 of the detector part 1 is in a state where the gas to be tested can be contacted, and the β detection crystal 4 and the γ detection crystal 7 are ready to receive radioactive particles. The aluminum film on the surface of the β detection crystal 4 prevents external light interference and pollution, and the organic glass light guide ensures the effective transmission of photons.

[0048] The β silicon photomultiplier tube 6 and the γ silicon photomultiplier tube 9 are in a standby state under the 28.5-29V working high voltage provided by the high voltage circuit, ready to convert the received optical signal into an electrical signal. The preamplifier circuit, discrimination circuit, forming processing circuit, etc. of the signal processing board 10 are also in a standby state, waiting to receive and process signals.

[0049] Detection process and data processing: After the preparation work is completed, click the start detection button on the operation interface of the host display processing unit 17. The air pump 20 is started to pump the gas to be tested into the inert gas measurement chamber 23 through the air pump pipeline.

[0050] After the gas to be measured enters the measuring cavity 23, the β and γ particles emitted by Kr-85 interact with the β detection crystal 4 and the γ detection crystal 7, and the β detection crystal 4 and the γ detection crystal 7 generate fluorescence. The photons are transmitted to the β silicon photomultiplier tube 6 and the γ silicon photomultiplier tube 9 through the β light guide plate 5 and the γ light guide plate 8 respectively. The β silicon photomultiplier tube 6 and the γ silicon photomultiplier tube 9 convert the optical signals into electrical signals, which are received by the signal processing board 10. The preamplifier circuit of the signal processing board 10 amplifies and shapes the signals so that the signal strength meets the subsequent processing requirements.

[0051] The discrimination circuit discriminates the pulse amplitude and width of the amplified signal, and accurately identifies the β and γ signals according to the characteristics of the β and γ pulse signals. The shaping processing circuit performs shaping processing on the discriminated β and γ signals, and outputs the β and γ ray count values ​​per unit time. These count values ​​are transmitted to the host display processing unit 17 through the communication circuit 12 of the signal processing board 10 using the RS485 protocol. After receiving the signal, the host display processing unit 17 processes it through the supporting data acquisition and analysis software. The software first deducts the background effect of γ rays according to the set background deduction factor, and then calculates the radioactivity concentration of Kr-85 based on parameters such as the calibration factor.

[0052] During the detection process, the main display interface of the host display processing unit 17 displays the detector measurement value, activity concentration working curve (the default display time is 10 minutes, and it can also be switched to 1 hour or 10 hours working curve for viewing), alarm status, date and time, alarm threshold, detector status, alarm buzzer status and other information in real time. If the detected radioactivity exceeds the preset alarm threshold, the host display processing unit 17 controls the sound and light alarm device 19 (Blue Wave LB22FM type buzzer) to send out sound and light alarm signals to remind the staff to take corresponding measures. At the same time, the detection data is recorded to the machine, and can be connected to the computer through RS485 communication or RJ45 communication, and the data is synchronously displayed on the computer and saved and recorded for subsequent analysis. The built-in SD storage card can also be used to store and export measurement data so that data can be transferred and further processed when necessary. After the detection is completed, turn off the vacuum pump 20, stop gas extraction, close the glass rotor flowmeter 21 valve, and then clean and maintain the equipment as needed, such as cleaning the surface of the carbon fiber protective plate 3.

[0053] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the same elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. Kr-85 portable detection device based on plastic flash detector + SiPM, characterized in that: The device is composed of three parts: an equipment housing (28), an air extraction pipeline system, and a measurement and detection system; The device housing (28) is made of 304L stainless steel plate with a thickness of 1.5 mm, with a plastic-sprayed outer surface and rounded corners, and is provided with a power switch (26), an air pump switch (24), an RS485 data transmission interface, two quick-twist pagoda interfaces (25), an audible and visual alarm device (19), a glass rotor flowmeter (21), a vacuum pump (20) switch, and a host display processing unit (17) with an integrated 7-inch touch screen, as well as a lightweight aluminum alloy handle (15) installed on the top of the device. A group of supporting feet (16) are arranged on the bottom surface of the housing (28); the power switch (26) is used to connect a 220V power supply; the RS485 data transmission interface is used to debug and connect to a computer to export data; the quick-twist pagoda interface (25) serves as an air inlet and an air outlet of the air extraction pipeline; the sound and light alarm device (19) is used to emit a sound and light alarm when the radioactivity is abnormal; the glass rotor flowmeter (21) is used to adjust the air intake flow of the pipeline; and the air extraction pump (20) switch controls the start and stop of the air extraction pump (20); The exhaust pipeline system is mainly installed inside the equipment, and is composed of an air inlet and outlet interface, an inert gas measurement chamber (23), a glass rotor flowmeter (21), a gas mass flowmeter (22), and an exhaust pump (20). The equipment is connected by a PU hose and the interface is reinforced to ensure air tightness. The inert gas measurement chamber (23) is made of stainless steel and is provided with two detector interfaces and an air inlet and outlet interface. The interior is a cylindrical measurement structure with a diameter of 70 mm and a height of 50 mm, with a total volume of about 192 cm3. The glass rotor flowmeter (21) is a micro-flow type with a range of 1.5-15L / min, installed on the front of the device housing (28); the gas mass flowmeter (22) is a high-precision thermal micro gas mass flowmeter (22) with an operating voltage of 5V, powered by the host display processing unit (17), with an operating range of 0.2-20L, fixed on the bottom of the device; the vacuum pump (20) is a micro vacuum pump with an operating voltage of 24V, a peak flow of 1.5-15L / min, and a relative vacuum degree ≤-88kPa; The measurement and detection system is composed of a power module (18), a detector part (1), a host display processing unit (17), and an audible and visual alarm lamp. The power module (18) supplies power to each component. The detector part (1) includes a detector housing (2), a carbon fiber protection plate (3), a β detection crystal (4), a β light guide (5), a β silicon photomultiplier tube (6), a γ detection crystal (7), a γ light guide (8), a γ silicon photomultiplier tube (9), and a signal processing board (10). The carbon fiber protection plate (3) is in contact with radioactive gas, is acid-proof and corrosion-resistant, and is easy to clean. The β detection crystal (4) is a common plastic scintillator with an effective size of φ70 mm×1 mm and a detection area of ​​about 38 cm2. The surface layer thereof has an aluminum film with a thickness of 10 μm, and the latter is closely attached to an organic glass light guide. The γ detection crystal (7) is a high β / γ type plastic scintillator with an effective size of φ70 mm×1 mm and a detection area of ​​about 38 cm2. The SiPM array has an operating high voltage of about 28.5-29 V and a power consumption of about 2 W.

2. The Kr-85 portable detection device based on plastic scintillation detector + SiPM according to claim 1 is characterized in that: The main display interface of the host display processing unit (17) displays the detector measurement value, activity concentration working curve, alarm status, date and time, alarm threshold, detector status, and alarm buzzer status information, wherein the default display time of the activity concentration working curve display interface is 10 minutes, and 1 hour and 10 hour working curves are optional.

3. The Kr-85 portable detection device based on plastic scintillation detector + SiPM according to claim 1 is characterized in that: The parameter setting interface of the host display processing unit (17) displays the number, event log, host communication status, detector type, and SD card status information, and can set conversion parameters, calibration factors, background subtraction factors, and data display length parameters. The measurement data is recorded in the local machine and can be exported as needed.

4. The Kr-85 portable detection device based on plastic scintillation detector + SiPM according to claim 1 is characterized in that: The detector interfaces of the inert gas measurement chamber (23) are arranged on the upper and lower surfaces of the measurement chamber, the air inlet is arranged below the front surface, and the air outlet is arranged above the rear surface. The gas to be measured enters the measurement chamber from the air inlet, flows out of the measurement chamber, passes through the gas mass flowmeter (22) and the glass rotor flowmeter (21) in sequence, and then returns to the measurement pipeline from the air outlet through the air pump (20).

5. The Kr-85 portable detection device based on plastic scintillation detector + SiPM according to claim 1 is characterized in that: The β silicon photomultiplier tubes (6) and the γ photomultiplier tubes both have 7 pieces, with an effective sensitive area of ​​6mm×6mm, arranged in a 2+3+2 array, and the center distance between adjacent SiPMs is 10mm.

6. The Kr-85 portable detection device based on plastic scintillation detector + SiPM according to claim 1 is characterized in that: The working voltage of the signal processing board (10) is 3.3V. The communication circuit (12) on the signal board communicates with the host display processing unit (17) using the RS485 protocol. The working voltage of the high-voltage circuit (13) is 28.5V-29V. The specific high-voltage value can be corrected by the built-in temperature compensation algorithm and set by connecting to the host computer software.

7. The Kr-85 portable detection device based on plastic scintillation detector + SiPM according to claim 1 is characterized in that: The power module (18) is selected from MEAN-WELL HDR-60-12 and HDR-60-24, and can output +12V and +24V voltages to supply power to the detector part (1), the host display processing unit (17), the sound and light alarm device (19), the vacuum pump (20) and the gas mass flow meter (22).

8. The Kr-85 portable detection device based on plastic scintillation detector + SiPM according to claim 1 is characterized in that: The sound and light alarm device (19) is a Rambo LB22FM buzzer with an operating voltage of 12V. The vacuum pump (20) is a Hilintec 42V micro vacuum pump with an operating flow rate of 8.15L / min. The glass rotor flowmeter (21) is a Changzhou Shuanghuan LZB-6WB type. The gas mass flowmeter (22) uses a Hangzhou Lihua MFM-20 high-precision thermal micro gas mass flowmeter (22). The RS485 protocol is used to upload flow information to the host display processing unit (17). The host computer interface (27) is a 2B five-core Remo plug for connecting external devices for data transmission and control operations.

9. The Kr-85 portable detection device based on plastic scintillation detector + SiPM according to claim 1 is characterized in that: The signal processing board (10) is composed of a power supply circuit (11), a signal amplification and shaping circuit (14), a high-voltage regulation circuit and a communication circuit (12). The power supply circuit (11) is externally connected to a power supply and supplies power to various components of the signal processing board (10). The signal amplification and shaping circuit (14) includes a preamplifier circuit, a discrimination circuit and a shaping processing circuit, which processes the signal collected by the SiPM into a voltage pulse signal and transmits it to the host. The preamplifier circuit amplifies and shapes the radioactive signal detected by the probe. The discrimination circuit discriminates the pulse amplitude and width of the signal to identify the β and γ signals. The shaping circuit performs shaping processing on the identified β and γ signals and outputs the β and γ ray count values ​​per unit time. The high-voltage regulation circuit provides normal operating voltage for the SiPM.

10. The Kr-85 portable detection device based on plastic scintillation detector + SiPM according to claim 9, characterized in that: The communication circuit (12) supports RS485 communication and RJ45 communication, and is used to set the detector working parameters and transmit signals to the host. The host display processing unit (17) controls the circuit output parameters through the supporting data acquisition and analysis software, receives and processes the signal and outputs the final counting result of the sample. It is equipped with a data processing algorithm to calculate and output the pulse signal after deducting the γ effect. It can be connected to a computer for synchronous display and record saving, and has a built-in SD storage card for storing and exporting measurement data.

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