Radioactive waste liquid surface pollution multipoint array detection system and method

Abstract

The invention discloses a radioactive waste liquid surface pollution multipoint array detection system and method, and relates to the technical field of nuclear radiation detection. The radioactive waste liquid surface pollution multipoint array detection system comprises a main body fixing frame, a mobile control device, a detector and an upper computer, a plurality of mounting holes arranged in a planar array are formed in the main body fixing frame; the movement control device controls the main body fixing frame to move; the plurality of detectors are mounted in the mounting holes of the main body fixing frame; the upper computer is used for regulating and controlling parameters of the CMOS sensor and storing, displaying, analyzing and processing frame images. The radioactive waste liquid storage tank liquid level pollution monitoring method is applied to a radioactive waste liquid surface pollution multipoint array detection system and is used for monitoring alpha and beta pollution areas of a radioactive waste liquid storage tank liquid level. The whole liquid level area of the radioactive waste liquid storage tank is covered at a time through the detachable detector group arranged in the plane array, and a pollution distribution panorama can be obtained through single-time measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear radiation detection, in particular to a multi-point array detection system and method for radioactive waste liquid surface contamination. Background Art

[0002] Monitoring the surface contamination of radioactive waste storage tanks is a critical component of radiation protection at nuclear facilities, directly impacting the operational safety and decommissioning efficiency of nuclear power plants and reprocessing plants. Traditional monitoring methods rely primarily on single-point surface contamination detectors (such as plastic scintillator detectors) for point-by-point scanning or suspended fixed monitoring. However, these methods suffer from the following drawbacks in practical applications:

[0003] 1. Difficulty covering large areas: Radioactive waste storage tanks can cover tens to hundreds of square meters. Traditional single-point detectors rely on robotic arm scanning, and a single measurement can take hours. While the CoMo series of portable radioactive contamination monitors released by the US company NUVIA can support mobile measurements, they are limited by the effective area of ​​the probe and cannot achieve simultaneous, panoramic monitoring of contamination distribution.

[0004] 2. Poor environmental adaptability: Steam or foam often forms on the surface of radioactive waste, causing measurement fluctuations exceeding ±30% in traditional plastic scintillator detectors. The light-shielding aluminum film on the plastic scintillator surface is susceptible to oxidation and peeling (lifespan less than 6 months) in high-temperature and high-humidity environments, leading to false alarms of radioactive contamination.

[0005] In summary, existing monitoring methods are difficult to achieve synchronous monitoring of large-area liquid surfaces and good adaptation to complex liquid surface environments. There is an urgent need for a modular, freely arrangable multi-point detector array system to achieve efficient and accurate monitoring of surface contamination of radioactive waste liquid. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a multi-point array detection system and method for radioactive waste liquid surface contamination, which solves the problems that the current means of monitoring radioactive waste liquid surface contamination are difficult to achieve synchronous monitoring of large areas of liquid surface and have poor adaptability to complex liquid surface environments.

[0007] The technical solution of the present invention is: a multi-point array detection system for radioactive waste liquid surface contamination is used to monitor radioactive contamination on the liquid surface of a radioactive waste liquid storage tank; the radioactive waste liquid storage tank is a trough-shaped container with an open top; the multi-point array detection system for radioactive waste liquid surface contamination includes a main body fixing frame, a mobile control device, a detector and a host computer;

[0008] The main body fixing frame is provided with a plurality of mounting holes arranged in a planar array;

[0009] The movement control device is fixedly installed on the ground outside the radioactive waste liquid storage tank and is movably connected to the main fixing frame. The movement control device controls the main fixing frame to move closer to or away from the liquid surface of the radioactive waste liquid storage tank through vertical lifting operation, and controls the main fixing frame to move into or out of the area above the liquid surface of the radioactive waste liquid storage tank through horizontal rotation operation;

[0010] Multiple detectors can be detachably installed in various mounting holes of the main body fixing frame, with only one detector installed in each mounting hole, and the detection directions of all detectors are facing the liquid surface of the radioactive waste liquid storage tank; the detector includes a shell, a detection module, a battery module, a communication component and a line integrated converter; the shell is made of radiation-transmissive material, and an inner cavity is provided inside the shell; the detection module includes a CMOS sensor, a circuit board, a chip board and a shell; there is no glass packaging on the photosensitive surface of the CMOS sensor and a light-shielding aluminum film is evaporated, the CMOS sensor is fixedly mounted on a circuit board with a power supply interface, and the circuit board is communicatively connected to the chip board; a SOC chip for outputting frame images is installed on the chip board; the shell is made of radiation-shielding material, and an inner cavity is provided inside the shell, and an entrance hole connected to the inner cavity of the shell is provided on one side of the shell, and the shape and size of the entrance hole are consistent with the shape and size of the photosensitive surface consistent; the circuit board and the chip board are both fixedly installed in the inner cavity of the shell, and the photosensitive surface of the CMOS sensor faces the incident hole of the shell; the detection module is fixedly installed in the inner cavity of the shell as a whole, and the external α and β rays pass through the shell wall and the incident hole of the shell in turn and are incident on the photosensitive surface of the CMOS sensor; the battery module and the circuit integrated converter are both fixedly installed in the inner cavity of the shell; the communication component includes a wireless communication antenna and an auxiliary communication antenna; the circuit integrated converter includes a multi-channel voltage conversion module and a communication protocol conversion module; the input of the multi-channel voltage conversion module is connected to the battery module, and the output of the multi-channel voltage conversion module is divided into multiple power supplies connected to each power-requiring component; the input of the communication protocol conversion module is connected to the chip board, and the output of the communication protocol conversion module is respectively connected to the wireless communication antenna and the auxiliary communication antenna; the direction of the photosensitive surface of the CMOS sensor is the detection direction of the detector;

[0011] The host computer is respectively connected to the wireless communication antenna and the auxiliary communication antenna. The host computer is used to adjust the parameters of the CMOS sensor, and store, display, analyze and process frame images containing radiation response signals.

[0012] The further technical scheme of the present application is that the main body fixing frame is movably connected with the mobile control device through a connecting assembly; the connecting assembly comprises threading rings, connecting ropes and a lifting ring; a plurality of the threading rings are evenly distributed on the upper end of the main body fixing frame in a ring shape around the gravity center of the main body fixing frame; the number of the connecting ropes is consistent with that of the threading rings and the connecting ropes are one-to-one corresponding; the lower end of the connecting rope is connected with the threading ring and the upper end of the connecting rope is connected with the lifting ring; when the whole main body fixing frame is lifted through the lifting ring, all the connecting ropes bear equal tension, and the main body fixing frame is in a horizontal state; in the horizontal state, all the mounting holes on the main body fixing frame are arranged in the same height.

[0013] The further technical scheme of the present application is that the mobile control device is a cantilever crane; the cantilever crane comprises a stand, a cantilever, a rotating device and a lifting device; the cantilever is movably connected with the upper end of the stand and is driven by the rotating device to make horizontal rotation; the rotating device is installed between the stand and the cantilever; the lifting device is installed at the lower end of the cantilever; the lifting device comprises a motor, a speed reducer, a winding drum and a steel wire rope; the power of the motor is transmitted to the winding drum through the speed reducer to drive the rotation of the winding drum, and then drive the winding and unwinding of the steel wire rope wound on the winding drum; the lower end of the steel wire rope is provided with a lifting hook; the cantilever crane is movably connected with the lifting ring through the lifting hook, so as to realize the movable connection with the main body fixing frame.

[0014] The further technical scheme of the present application is that it further comprises lifting guide frames; a plurality of the lifting guide frames are fixedly installed on the ground outside the radioactive waste liquid storage tank; the lifting guide frames are provided with vertically arranged guide convex strips; the upper end of the lifting guide frame is provided with an avoidance chamfer for guiding the lowering of the main body fixing frame; correspondingly, the edge of the main body fixing frame is provided with a guide notch matched with the guide convex strip; the main body fixing frame is slidably installed between all the lifting guide frames in a horizontal state through the cooperation of the guide notch and the guide convex strip.

[0015] The further technical scheme of the present application is that the detector further comprises a cooling fan; the cooling fan is fixedly installed in the inner cavity of the shell, and the two ends of the cooling fan are an air inlet end and an air outlet end respectively; the air outlet end of the cooling fan is arranged opposite to the detection module; the shell is provided with an air inlet hole arranged opposite to the air inlet end of the cooling fan.

[0016] The further technical scheme of the present application is that the shell of the detector is in the shape of a cuboid, and the outer wall of the shell is provided with two symmetrically arranged hanging ears; correspondingly, the two sides of each mounting hole of the main body fixing frame are provided with positioning recesses for embedding the hanging ears of the detector; when the detector is inserted into the mounting hole of the main body fixing frame from top to bottom, the lower end of the detector extends out of the lower end of the main body fixing frame, the two hanging ears of the detector are embedded into the positioning recesses on the two sides of the mounting hole respectively, and the photosensitive surface of the CMOS sensor is parallel to the axis of the mounting hole.

[0017] The further technical scheme of the present application is that the wireless communication antenna is an external 5.8GHz WiFi antenna, which is used for real-time uploading of detection data; the auxiliary communication antenna is a dual-mode Bluetooth antenna supporting classic Bluetooth and low-power Bluetooth, which is used for maintaining standby of the detection module, setting parameters of the CMOS sensor, controlling start and stop of the detection task, and transmitting a basic alarm signal when the wireless communication antenna is shielded.

[0018] The further technical scheme of the present application is that the thickness of the light-shielding aluminum film is uniform, and the thickness of the light-shielding aluminum film is 200±50nm.

[0019] The further technical scheme of the present application is that the wireless communication antenna is connected with the communication protocol conversion module through an SDIO interface, and the auxiliary communication antenna is connected with the communication protocol conversion module through a UART interface.

[0020] The technical scheme of the present application is a radioactive waste liquid tank liquid surface pollution monitoring method applied to the radioactive waste liquid surface pollution multi-point array detection system, and aims to monitor the alpha and beta pollution areas of the radioactive waste liquid tank liquid surface.

[0021] The method is as follows:

[0022] S01, pre-operation:

[0023] A, sensor calibration: the CMOS sensors in all detectors are calibrated respectively, which is used for eliminating the interference of environmental noise and non-pollution factors on subsequent measurement, and the calibration process includes measurement and storage of CMOS sensor base data and setting of CMOS sensor gain; and then each detector is numbered;

[0024] B, construction of detector group: each detector after numbering is inserted into the corresponding mounting hole of the main fixed frame according to a specific array density and arrangement mode, so as to form a planar array arrangement detector group;

[0025] C, pose adjustment: the main fixed frame with detectors is movably connected with the mobile control device through the connecting assembly, the mobile control device is started, the main fixed frame with detectors is hoisted to the top of the radioactive waste liquid tank, and the guide notch of the main fixed frame is opposite to the guide convex strip of the lifting guide frame; the mobile control device is controlled, the main fixed frame with detectors is lowered, the guide notch of the main fixed frame is clamped into the guide convex strip of the lifting guide frame through the guidance and deviation correction of the avoidance chamfer of the lifting guide frame; at this time, the main fixed frame and the lifting guide frame form sliding contact, and the main fixed frame is lowered stably without shaking through the guiding effect of the lifting guide frame; until the distance between the photosensitive surface of the CMOS sensor and the liquid surface of the radioactive waste liquid tank is less than 1cm, the lowering is stopped.

[0026] D. Data collection: All detectors are activated simultaneously, with each detector scanning a specific area of ​​the radioactive waste liquid storage tank surface. The sampling interval and startup sampling time of all detectors are the same, thereby collecting multiple sets of radiation data. Each set of radiation data contains multiple frames with the same timestamp, and each frame image comes from a corresponding detector. Each detector uploads the collected frame image to the host computer in real time via the wireless communication antenna;

[0027] S02, feature extraction:

[0028] The host computer performs the following operations on each set of radiation data:

[0029] A. Response signal extraction: Convert a set of radiation data into a set of grayscale images, then perform noise removal and background correction operations to extract effective radiation response signals from each grayscale image contained in the set of grayscale images;

[0030] B. Characteristic parameter calculation: Calculate the characteristic parameters of the extracted radiation response signal, which include one or more of the average pixel value, distribution shape, and number of pixels;

[0031] C. Response signal differentiation: Under the premise that the radiation response signal only contains α and β response signals, the α and β response signals are differentiated from each grayscale image contained in a set of grayscale images based on the inherent differences in the characteristic parameters of the α and β response signals;

[0032] S03, data shows:

[0033] A. Grouped display: The host computer displays each set of radiation data after feature extraction on the screen. Each set of radiation data is displayed in sequence according to the timestamp. The display duration of a set of radiation data is the sampling interval of the detector. The display content of a set of radiation data includes the α response signal count and β response signal count obtained by processing multiple grayscale images under the data set. That is, multiple group counts are displayed, which is consistent with the number of grayscale images. Each group count is also marked with the corresponding detector number.

[0034] B. Alarm mechanism: For detector groups whose α response signal count or β response signal count exceeds a preset threshold, the host computer 9 executes a graded alarm;

[0035] Level 1 alarm:

[0036] Level 1 alarm is a local early warning, suitable for short-term minor pollution that requires manual review. When the alpha or beta response signal count of a detector group exceeds the operating threshold during a single sampling, the host computer marks the detector number in real time and displays an orange frame in the corresponding area on the screen.

[0037] Secondary alarm:

[0038] Level 2 alarm indicates the need for emergency treatment and is applicable to situations of persistent severe pollution requiring emergency intervention. When the α or β response signal counts of the same detector group exceed the intervention threshold in three consecutive samplings, or the single sampling count exceeds the tolerance threshold, the host computer marks the detector number in real time, displays a red frame in the corresponding area of ​​the screen, and automatically generates a pollution diffusion trend graph, which is superimposed on the center area of ​​the display interface with 50% transparency and 50% screen ratio. The sampling task of the detector group is suspended and an alarm prompt is triggered at the same time.

[0039] C. Self-check mechanism: When the α or β response signal count of a detector group is 0 for five consecutive samples, the host computer determines that the "detector has failed" and wakes up the detector's cooling fan through Bluetooth instructions and checks for voltage fluctuations. If there is no device status feedback within 10 seconds, the point is automatically marked as "faulty" and a yellow alarm mark is triggered, reminding staff to replace the detector.

[0040] A further technical solution of the present invention is: in step S02, the average pixel value is used to characterize the overall brightness level of the radiation response signal, and the calculation formula is shown in Formula 1;

[0041] Formula 1:

[0042] Where M is the average pixel value of the connected area, P is the number of pixels in the connected area, δ is the screening function used to determine whether the target pixel belongs to the connected area, and the connected area is the area occupied by a radiation response signal in the frame image; (i, j) represents the pixel in the i-th row and j-th column, n and m represent the number of rows and columns of the pixel, respectively, I(i, j) represents the pixel value of the i-th row and j-th column, and T is the pixel value threshold of the connected area pixel;

[0043] In step S02, the number of pixels is the number of pixels in the connected area, which is used to reflect the area size of the radiation response signal. The calculation formula is shown in Formula 2;

[0044] Formula 2:

[0045] Where P is the number of pixels in the connected area;

[0046] In step S02, the α response signal exhibits a target-type distribution characteristic in the distribution morphology; the target-type distribution characteristic is manifested as follows: the α response signal includes a central area and an annulus from the inside out; the grayscale value of the pixels in the central area is above 230, the grayscale value of the pixels in the annulus is between 30 and 150, and multiple sub-rings with a grayscale value decreasing gradient distribution are formed from the inside to the outside of the annulus; the β response signal does not have a target-type distribution characteristic;

[0047] In step S02, at the 9dB, 32dB or 63dB level, the average pixel value, distribution form and number of pixels of the α response signal are different from those of the β response signal, and the α response signal and the β response signal are distinguished by the differences.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] 1. Achieve simultaneous, panoramic monitoring of large areas, significantly improving detection efficiency: A detachable detector array arranged in a planar array covers the entire liquid surface area of ​​a radioactive waste storage tank at once, overcoming the limitations of traditional single-point detectors, which can only scan or monitor specific locations. A single measurement provides a panoramic view of contamination distribution, reducing point-by-point detection from hours to minutes, significantly improving nuclear facility operation and maintenance efficiency.

[0050] 2. Breaking through the bottleneck of complex liquid level environment monitoring and ensuring data reliability: The detection module is installed in the inner cavity of a sealed shell, effectively isolating steam and preventing contamination of the CMOS sensor. The shell is made of radiation-transmissive material, the housing is made of radiation-shielding material, and an entrance hole is provided to ensure that the CMOS sensor can receive external α and β radiation (α and β rays pass through the shell and the entrance hole in turn and are incident on the photosensitive surface of the CMOS sensor). If the detector shell is contaminated, the main frame and all detectors mounted thereon are lifted up together through the mobile control device, so that the main frame is out of the guide range of the lifting guide frame. The main frame and all detectors mounted thereon are then driven by the mobile control device to rotate together to the upper external area of ​​the radioactive waste liquid storage tank. Finally, all detector shells are rinsed to wash away the radioactive nuclides contaminated on the detector shells, and the detectors can be put back into use.

[0051] 3. Modular design ensures flexibility and maintainability: Detectors are quickly plugged in and out via mounting ears and positioning recesses, and array density and layout can be dynamically adjusted based on actual monitoring needs. Failure of individual detectors can be replaced individually, avoiding system downtime and reducing maintenance costs.

[0052] 4. The detector combines low cost with high precision: The core detection component, the CMOS sensor, requires only minor modifications (removing the glass encapsulation from the photosensitive surface and depositing aluminum film on it), resulting in a relatively low manufacturing cost compared to traditional radioactive contamination detectors. The CMOS sensor eliminates the boundary effects of plastic scintillators, enabling high-precision radiation detection across its entire photosensitive surface.

[0053] 5. The detector has high sensitivity and good environmental adaptability: the core component of the detector, CMOS sensor, is sensitive to the incident α and β particles due to its own characteristics, and produces different shaped response signals, thereby providing a hardware basis for accurate discrimination of α and β rays. The working temperature range of the industrial-grade CMOS sensor can reach -40℃-60℃, compared with the traditional plastic scintillator, the working temperature range is expanded, and the heat dissipation fan is further ensured to ensure the stability of the detector when working at high temperature for a long time.

[0054] 6. Dual-mode communication architecture: the communication component of the detector innovatively integrates a 5.8GHz WiFi antenna and a dual-mode Bluetooth antenna, which cooperates and divides through a communication protocol conversion module; the 5.8GHz WiFi antenna is used to upload the detection data (continuous frame images) to the host computer in real time, which can meet the IAEA nuclear emergency real-time response standard; the Bluetooth BLE mode can maintain standby power consumption less than 0.1mA, which greatly improves the device endurance; when the WiFi is shielded (5.8GHz signal strength < -90dBm), the Bluetooth (auxiliary communication antenna) transmission basic alarm signal is automatically switched, which ensures the reliability in extreme working conditions.

[0055] The application will be further described in combination with the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 It is a structural schematic diagram of the application;

[0057] Figure 2 It is a structural schematic diagram of the main body fixing frame in the application;

[0058] Figure 3 It is an appearance diagram of the detector;

[0059] Figure 4 It is a schematic diagram of power supply connection / communication connection of each component in the application;

[0060] Figure 5 It is a structural schematic diagram of the detection module.

[0061] Legend: Radioactive waste liquid storage tank 100; cooling fan 200; main body fixing frame 1; mounting hole 11; threading ring 12; connecting rope 13; lifting ring 14; positioning pit 15; guide notch 16; mobile control device 2; column 21; cantilever 22; wire rope 231; hook 232; housing 3; hanging ear 31; detection module 4; CMOS sensor 41; circuit board 42; chip board 43; SOC chip 431; housing 44; incident hole 441; battery module 5; communication component 6; wireless communication antenna 61; auxiliary communication antenna 62; line integrated converter 7; multi-channel voltage conversion module 71; communication protocol conversion module 72; lifting guide frame 8; guide ridge 81; avoidance chamfer 82; host computer 9. DETAILED DESCRIPTION

[0062] Example 1:

[0063] like Figure 1-5 As shown, the multi-point array detection system for radioactive waste surface contamination is used to monitor radioactive contamination on the liquid surface of a radioactive waste storage tank 100. The radioactive waste storage tank 100 is a trough-shaped container with an open top. The multi-point array detection system for radioactive waste surface contamination includes a main frame 1, a mobile control device 2, detectors, and a host computer.

[0064] The main body fixing frame 1 is provided with a plurality of mounting holes 11 arranged in a planar array. The main body fixing frame 1 is movably connected to the mobile control device 2 through a connecting assembly. The connecting assembly includes a threading ring 12, a connecting rope 13 and a lifting ring 14. A plurality of threading rings 12 are evenly distributed in a ring shape around the center of gravity of the main body fixing frame 1 on the upper end (the upper end is the upper surface, and the connection method is welding). The number of connecting ropes 13 is consistent with the number of threading rings 12 and corresponds one to one. The connecting rope 13 is connected to the threading ring 12 at the lower end and to the lifting ring 14 at the upper end. When the entire main body fixing frame 1 is lifted only by the lifting ring 14, all the connecting ropes 13 are subjected to equal tension, and the main body fixing frame 1 is in a horizontal state. In the horizontal state, all the mounting holes 11 on the main body fixing frame 1 are arranged at the same height.

[0065] The movement control device 2 is fixedly mounted on the ground outside the radioactive waste liquid storage tank 100 and is movably connected to the main frame 1. It controls the main frame 1 to move closer to or further away from the liquid level of the radioactive waste liquid storage tank 100 through vertical lifting operations and controls the main frame 1 to move out of the area above the liquid level of the radioactive waste liquid storage tank 100 through horizontal rotation operations. The movement control device 2 is a cantilever crane. The cantilever crane includes a column 21, a cantilever 22, a slewing device (not shown), and a lifting device. The cantilever 22 is rotatably connected to the upper end of the column 21 and rotates horizontally under the drive of the slewing device. The slewing device is installed between the column 21 and the cantilever 22. The lifting device is installed at the lower end of the cantilever 22. The lifting device includes a motor, a speed reducer, a drum, and a wire rope 231. The motor, speed reducer, and drum are all mounted at the lower end of the boom 22. The motor's power is transmitted to the drum via the speed reducer, driving the drum to rotate, which in turn drives the wire rope 231 wound around the drum to retract and extend. A hook 232 is provided at the lower end of the wire rope 231. The boom crane is movably connected to the lifting ring 14 via the hook 232, thereby achieving a movable connection with the main frame 1.

[0066] Multiple detectors are detachably mounted in the mounting holes 11 of the main fixing frame 1 , with only one detector mounted in each mounting hole 11 , and all detectors face the liquid surface of the radioactive waste liquid storage tank 100 .

[0067] The detector includes a housing 3 , a detection module 4 , a battery module 5 , a communication component 6 and a line integrated converter 7 .

[0068] The shell 3 is made of a radiolucent material and has an inner cavity.

[0069] The detection module 4 comprises a CMOS sensor 41, a circuit board 42, a chip board 43, and a housing 44. The photosensitive surface of the CMOS sensor 41 is not encapsulated with glass and is deposited with a light-shielding aluminum film. The CMOS sensor 41 is fixedly mounted on the circuit board 42, which has a power supply interface. The circuit board 42 is in communication with the chip board 43. The chip board 43 houses a SOC chip 431 for outputting frame images. The housing 44 is made of radiation-shielding material and has an internal cavity. An entrance aperture 441 is provided on one side of the housing, connecting to the cavity. The shape and dimensions of the entrance aperture 441 match those of the photosensitive surface. Both the circuit board 42 and the chip board 43 are fixedly mounted within the cavity of the housing 44, with the photosensitive surface of the CMOS sensor 41 facing the entrance aperture 441. The detection module 4 is fixedly mounted within the cavity of the housing 1. External α and β rays sequentially pass through the walls of the housing 3 and the entrance aperture 441 of the housing 44, impinging on the photosensitive surface of the CMOS sensor 41.

[0070] The battery module 5 is fixedly installed in the inner cavity of the housing 1. The battery module 5 is specifically a 5V 3A rechargeable lithium battery.

[0071] Communication component 6 includes a wireless communication antenna 61 and an auxiliary communication antenna 62. Wireless communication antenna 61 is mounted on the exterior of housing 1. It is an external 5.8 GHz WiFi antenna used for real-time uploading of detection data (continuous frame images). Auxiliary communication antenna 62 is mounted within the interior of housing 1. It is a dual-mode Bluetooth antenna supporting both classic Bluetooth and Bluetooth Low Energy. It is used to maintain the standby state of detection module 4, set parameters for CMOS sensor 41, control the start and stop of detection tasks, and transmit basic alarm signals when wireless communication antenna 61 is blocked.

[0072] The circuit integrated converter 7 is fixedly installed in the inner cavity of the shell 3. The circuit integrated converter 7 includes a multi-channel voltage conversion module 71 (for power supply management of each power-demanding component) and a communication protocol conversion module 72 (for signal relay and protocol adaptation). The input of the multi-channel voltage conversion module 71 is connected to the battery module 5 to control the on and off of the main power supply. The output of the multi-channel voltage conversion module 71 is divided into multiple power supplies connected to each power-demanding component to provide power support for each power-demanding component. The input of the communication protocol conversion module 72 is connected to the chip board 43, and the output of the communication protocol conversion module 72 is respectively connected to the wireless communication antenna 61 and the auxiliary communication antenna 62. The direction of the photosensitive surface of the CMOS sensor 41 is the detection direction of the detector.

[0073] Host computer 9 is connected to wireless communication antenna 61 and auxiliary communication antenna 62. Host computer 9 is used to control the parameters of CMOS sensor 41 and store, display, analyze, and process image frames containing radiation response signals. Host computer 9 receives basic alarm signals from auxiliary communication antenna 42 via Bluetooth and displays them to alert personnel to address the situation.

[0074] Preferably, the wall of the housing 3 facing the CMOS sensor is the bottom wall, the outer surface of the bottom wall of the housing 3 is a plane, the photosensitive surface of the CMOS sensor is parallel to the outer surface of the bottom wall of the housing 3, and the distance between the photosensitive surface of the CMOS sensor and the outer surface of the bottom wall of the housing 3 is less than 5 mm.

[0075] Preferably, it also includes a lifting guide frame 8. Multiple lifting guide frames 8 are fixedly installed on the ground outside the radioactive waste liquid storage tank 100. The lifting guide frames 8 are provided with vertically arranged guide ridges 81. The upper ends of the lifting guide frames 8 are provided with avoidance chamfers 82 for guiding the lowering of the main body fixing frame. Correspondingly, the edges of the main body fixing frame 1 are provided with guide notches 16 that match the guide ridges. Through the matching relationship between the guide notches 16 and the guide ridges 81, the main body fixing frame 1 is slidably installed in a horizontal state between all the lifting guide frames 8.

[0076] Preferably, the detector also includes a cooling fan 200. The cooling fan 200 is fixedly mounted within the inner cavity of the housing 3. The cooling fan 200 has an air inlet and an air outlet, with the outlet facing the detection module 4. The housing 3 is provided with an air inlet (not shown) facing the air inlet of the cooling fan 200.

[0077] Preferably, the detector's housing 3 is rectangular, with two symmetrically arranged lugs 31 provided on its outer wall. Accordingly, each mounting hole of the main frame 1 is provided with positioning recesses 15 on either side for the detector's lugs 31 to engage. When the detector is inserted into the mounting hole 11 of the main frame 1 from top to bottom, the detector's lower end protrudes from the lower end of the main frame 1, and the two lugs 31 engage with the positioning recesses 15 on either side of the mounting hole 11. The photosensitive surface of the CMOS sensor 41 is oriented parallel to the axis of the mounting hole 11.

[0078] Preferably, the thickness of the light-shielding aluminum film evaporated on the surface of the CMOS sensor 41 is uniform everywhere, and the thickness of the light-shielding aluminum film is 200±50 nm.

[0079] Preferably, the wireless communication antenna 61 is connected to the communication protocol conversion module via an SDIO interface, and the auxiliary communication antenna 62 is connected to the communication protocol conversion module via a UART interface.

[0080] Briefly describe the working principle of the present invention:

[0081] A method for monitoring liquid surface contamination in radioactive waste storage tanks is applied to the aforementioned multi-point array detection system for radioactive waste surface contamination. The method uses individual detectors to acquire radioactive contamination data (frame images containing radiation response signals) at different locations on the liquid surface of the radioactive waste storage tank. This data is then analyzed and processed by a host computer (corresponding to subsequent steps S02-S03) to monitor alpha and beta contamination zones on the liquid surface of the radioactive waste storage tank.

[0082] Here’s how:

[0083] S01, pre-operation:

[0084] A. Sensor calibration: Calibrate the CMOS sensors 41 in all detectors separately to eliminate interference from environmental noise and non-polluting factors on subsequent measurements. The calibration process includes measuring and storing the base data of the CMOS sensor 41 and setting the gain of the CMOS sensor 41. Then, number each detector.

[0085] B. Constructing a detector group: Install the numbered detectors into the corresponding mounting holes 11 on the main fixing frame 1 according to a specific array density and arrangement, thereby forming a detector group arranged in a planar array;

[0086] C. Posture adjustment: The main body fixing frame 1 equipped with the detector is movably connected to the mobile control device 2 through the connecting assembly, and the mobile control device 2 is started. The main body fixing frame 1 equipped with the detector is lifted and moved to the top of the radioactive waste liquid storage tank 100, and the guide notch 16 of the main body fixing frame 1 is roughly aligned with the guide ridge 81 of the lifting guide frame 8 (the term "roughly" means that the docking error between the main body fixing frame 1 and the lifting guide frame 8 is within the range guided and corrected by the avoidance chamfer 82 of the lifting guide frame 8). The mobile control device 2 is operated to move the main body fixing frame 1 equipped with the detector to the top of the radioactive waste liquid storage tank 100. The main body fixing frame 1 is slowly lowered (the term "slowly" refers to the main body fixing frame 1 being stable and without shaking). The guide notch 16 of the main body fixing frame 1 is engaged with the guide ridge 81 of the lifting guide frame 8 by the guidance and deviation correction of the avoidance chamfer 82 of the lifting guide frame 8. At this time, a sliding contact is formed between the main body fixing frame 1 and the lifting guide frame 8. The guiding action of the lifting guide frame 8 allows the main body fixing frame 1 to descend smoothly without shaking. The descent stops when the distance between the photosensitive surface of the CMOS sensor 41 and the liquid level of the radioactive waste liquid storage tank 100 is less than 1 cm.

[0087] D. Data collection: All detectors are started simultaneously, and each detector scans a specific area of ​​the liquid surface of the radioactive waste storage tank at a fixed point. The sampling interval time of all detectors (for example, all detectors adopt a sampling interval of 1 minute / time) and the start sampling time (for example, the time when all detectors start sampling at the same time is 13:00, 13:01, 13:02...) are the same, so that multiple groups of radiation data are collected. Each group of radiation data contains multiple frame images with the same timestamp, and each frame image comes from a corresponding detector; each detector uploads the collected frame image to the host computer 9 in real time through the wireless communication antenna 61.

[0088] S02, feature extraction:

[0089] The host computer 9 performs the following operations on each set of radiation data:

[0090] A. Response signal extraction: Convert a set of radiation data into a set of grayscale images, then perform noise removal and background correction operations to extract effective radiation response signals from each grayscale image contained in the set of grayscale images;

[0091] B. Characteristic parameter calculation: Calculate the characteristic parameters of the extracted radiation response signal, which include one or more of the average pixel value, distribution shape, and number of pixels;

[0092] C. Response signal distinguishing: under the premise that the radiation response signal only contains α and β response signals, according to the inherent difference of the characteristic parameters of the α and β response signals (which can be obtained and recorded through prior experiments), the α and β response signals are distinguished from each of the gray scale images contained in the group of gray scale images.

[0093] In this step, the average pixel value is used to represent the overall brightness level of the radiation response signal, and the calculation formula is shown in formula 1.

[0094] Formula 1:

[0095] In the formula, M is the average pixel value of the connected region, P is the number of pixels in the connected region, δ is a screening function for determining whether the target pixel belongs to the connected region, the connected region is a region occupied by a radiation response signal in the frame image, (i, j) represents the i-th row and j-th column pixel, n and m represent the number of rows and columns of pixels, respectively, I(i, j) represents the pixel value of the i-th row and j-th column pixel, and T is the pixel value threshold of the connected region.

[0096] In this step, the number of pixels is the number of pixels in the connected region, which is used to reflect the area size of the radiation response signal, and the calculation formula is shown in formula 2.

[0097] Formula 2:

[0098] In the formula, P is the number of pixels in the connected region.

[0099] In this step, in the distribution form, the α response signal presents a target distribution characteristic; the target distribution characteristic is that the α response signal includes a central region and a ring belt from inside to outside; the gray value of the pixel in the central region is above 230, the gray value of the pixel in the ring belt is between 30-150, and a plurality of sub-rings with a descending gradient distribution of gray values are formed from the inside to the outside of the ring belt; the β response signal does not have the target distribution characteristic.

[0100] In this step, under the level of 9dB or 32dB or 63dB, the average pixel value, distribution form and number of pixels of the α response signal are all significantly different from those of the β response signal, and the difference is used to distinguish the α response signal and the β response signal.

[0101] S03, data display:

[0102] A. Group display: The upper computer 9 displays each group of radiation data after feature extraction through screen visualization; each group of radiation data is displayed in sequence according to the timestamp, and the display duration of a group of radiation data is the sampling interval duration of the detector; the display content of a group of radiation data includes the α response signal count and the β response signal count obtained by processing multiple grayscale images under the group of data, that is, multiple group counts consistent with the number of grayscale images are displayed, and the corresponding detector numbers are marked on the screen (for example, the first group (detector number 001): 50,000 α response signals, 100,000 β response signals; the second group (detector number 002): 40,000 α response signals, 90,000 β response signals).

[0103] B. Alarm mechanism: For detector groups whose α response signal count or β response signal count exceeds a preset threshold, the host computer 9 executes a graded alarm;

[0104] Level 1 alarm (local warning) (applicable scenario: short-term minor pollution, manual review required):

[0105] When the α or β response signal count of a detector group exceeds the operation threshold (pre-set according to GB18871 standard) in a single sampling, the host computer 9 marks the detector number in real time and displays an orange frame in the corresponding area of ​​the screen;

[0106] Level 2 alarm (emergency treatment) (applicable scenarios: persistent severe pollution, requiring emergency intervention):

[0107] When the α or β response signal counts of the same detector group exceed the intervention threshold (3 times the operating threshold) in three consecutive samplings, or the single sampling count exceeds the tolerance threshold (10 times the operating threshold), the host computer 9 marks the detector number in real time, displays a red frame in the corresponding area of ​​the screen, and automatically generates a pollution diffusion trend graph, which is superimposed on the center area of ​​the display interface with 50% transparency and 50% screen share, and suspends the sampling task of the detector group (to avoid data overload), and triggers an alarm prompt at the same time (provided that the host computer 9 is connected to an alarm).

[0108] C. Self-check mechanism: When the α or β response signal count of a detector group is 0 for five consecutive samples, the host computer 9 determines that the "detector has failed" and wakes up the cooling fan 200 of the detector through a Bluetooth command and checks the voltage fluctuation; if there is no device status feedback within 10 seconds, the point is automatically marked as "faulty" and a yellow alarm mark is triggered, thereby reminding the staff to replace the detector.

Claims

1. A multi-point array detection system for radioactive waste liquid surface contamination, used to monitor radioactive contamination on the surface of a radioactive waste liquid storage tank; the radioactive waste liquid storage tank is a trough-shaped container with an open top; Its characteristics are: Radioactive waste liquid surface contamination multi-point array detection system, including a main body fixed frame, mobile control device, detectors and host computer; The main body fixing frame is provided with a plurality of mounting holes arranged in a planar array; The movement control device is fixedly installed on the ground outside the radioactive waste liquid storage tank and is movably connected to the main fixing frame. The movement control device controls the main fixing frame to move closer to or away from the liquid surface of the radioactive waste liquid storage tank through vertical lifting operation, and controls the main fixing frame to move into or out of the area above the liquid surface of the radioactive waste liquid storage tank through horizontal rotation operation; Multiple detectors can be detachably installed in various mounting holes of the main body fixing frame, with only one detector installed in each mounting hole, and the detection directions of all detectors are facing the liquid surface of the radioactive waste liquid storage tank; the detector includes a shell, a detection module, a battery module, a communication component and a line integrated converter; the shell is made of radiation-transmissive material, and an inner cavity is provided inside the shell; the detection module includes a CMOS sensor, a circuit board, a chip board and a shell; there is no glass packaging on the photosensitive surface of the CMOS sensor and a light-shielding aluminum film is evaporated, the CMOS sensor is fixedly mounted on a circuit board with a power supply interface, and the circuit board is communicatively connected to the chip board; a SOC chip for outputting frame images is installed on the chip board; the shell is made of radiation-shielding material, and an inner cavity is provided inside the shell, and an entrance hole connected to the inner cavity of the shell is provided on one side of the shell, and the shape and size of the entrance hole are consistent with the shape and size of the photosensitive surface consistent; the circuit board and the chip board are both fixedly installed in the inner cavity of the shell, and the photosensitive surface of the CMOS sensor faces the incident hole of the shell; the detection module is fixedly installed in the inner cavity of the shell as a whole, and the external α and β rays pass through the shell wall and the incident hole of the shell in turn and are incident on the photosensitive surface of the CMOS sensor; the battery module and the circuit integrated converter are both fixedly installed in the inner cavity of the shell; the communication component includes a wireless communication antenna and an auxiliary communication antenna; the circuit integrated converter includes a multi-channel voltage conversion module and a communication protocol conversion module; the input of the multi-channel voltage conversion module is connected to the battery module, and the output of the multi-channel voltage conversion module is divided into multiple power supplies connected to each power-requiring component; the input of the communication protocol conversion module is connected to the chip board, and the output of the communication protocol conversion module is respectively connected to the wireless communication antenna and the auxiliary communication antenna; the direction of the photosensitive surface of the CMOS sensor is the detection direction of the detector; The host computer is respectively connected to the wireless communication antenna and the auxiliary communication antenna. The host computer is used to adjust the parameters of the CMOS sensor, and store, display, analyze and process frame images containing radiation response signals.

2. The multi-point array detection system for radioactive waste surface contamination according to claim 1, wherein: The main body fixing frame is movably connected to the mobile control device through a connecting assembly; the connecting assembly includes a threading ring, a connecting rope and a lifting ring; multiple threading rings are evenly distributed in a ring shape around the center of gravity of the main body fixing frame on the upper end of the main body fixing frame, the number of connecting ropes is consistent with the number of threading rings and corresponds one to one, the connecting rope is connected to the threading ring at the lower end, and the connecting rope is connected to the lifting ring at the upper end; when the entire main body fixing frame is lifted by the lifting ring, all connecting ropes are subjected to equal tension, and the main body fixing frame is in a horizontal state. In the horizontal state, all mounting holes on the main body fixing frame are arranged at the same height.

3. The multi-point array detection system for radioactive waste surface contamination according to claim 2, wherein: The mobile control device is a cantilever crane; the cantilever crane includes a column, a cantilever, a slewing device and a lifting device; the cantilever is rotatably connected to the upper end of the column and rotates horizontally under the drive of the slewing device; the slewing device is installed between the column and the cantilever; the lifting device is installed at the lower end of the cantilever; the lifting device includes a motor, a reducer, a drum and a wire rope. The power of the motor is transmitted to the drum through the reducer, driving the drum to rotate, and then driving the wire rope wound on the drum to be retracted and released. A hook is provided at the lower end of the wire rope; the cantilever crane is movably connected to the lifting ring through the hook, thereby realizing a movable connection with the main fixed frame.

4. The multi-point array detection system for radioactive waste surface contamination according to claim 3, wherein: It also includes a lifting guide frame; multiple lifting guide frames are fixedly installed on the ground outside the radioactive waste liquid storage tank; the lifting guide frame is provided with vertically arranged guide ridges; the upper end of the lifting guide frame is provided with an avoidance chamfer for guiding the main body fixing frame to be lowered; correspondingly, the edge of the main body fixing frame is provided with a guide notch matching the guide ridge; the main body fixing frame is slidably installed in a horizontal state between all the lifting guide frames through the matching relationship between the guide notch and the guide ridge.

5. The multi-point array detection system for radioactive waste surface contamination according to claim 4, characterized in that: The detector also includes a cooling fan; the cooling fan is fixedly installed in the inner cavity of the shell, and the two ends of the cooling fan are respectively an air inlet end and an air outlet end, and the air outlet end of the cooling fan is arranged opposite the detection module; an air inlet hole is provided on the shell and is arranged opposite the air inlet end of the cooling fan.

6. The multi-point array detection system for radioactive waste surface contamination according to claim 5, characterized in that: The detector's outer shell is in the shape of a rectangular parallelepiped, with two symmetrically arranged hanging ears on the outer wall of the shell; accordingly, each mounting hole of the main body fixing frame is provided with a positioning pit on both sides for the detector's hanging ears to be embedded in; when the detector is inserted into the mounting hole of the main body fixing frame from top to bottom, the lower end of the detector extends out of the lower end of the main body fixing frame, and the two hanging ears of the detector are respectively embedded in the positioning pits on both sides of the mounting hole, and the direction of the photosensitive surface of the CMOS sensor is parallel to the axis of the mounting hole.

7. The multi-point array detection system for radioactive waste surface contamination according to claim 6, characterized in that: The wireless communication antenna is an external 5.8GHz WiFi antenna, which is used for real-time uploading of detection data; the auxiliary communication antenna is a dual-mode Bluetooth antenna that supports both classic Bluetooth and low-power Bluetooth. It is used to maintain the standby state of the detection module, set CMOS sensor parameters, control the start and stop of detection tasks, and transmit basic alarm signals when the wireless communication antenna is shielded.

8. The multi-point array detection system for radioactive waste surface contamination according to claim 7, characterized in that: The thickness of the light-shielding aluminum film is consistent everywhere, and the thickness of the light-shielding aluminum film is 200±50nm.

9. A method for monitoring liquid surface contamination in a radioactive waste storage tank, applied to the radioactive waste surface contamination multi-point array detection system of claim 8, for the purpose of monitoring the α and β contamination areas of the liquid surface of a radioactive waste storage tank; Its characteristics are: Here’s how: S01, pre-operation: A. Sensor calibration: Calibrate the CMOS sensors in all detectors separately to eliminate interference from environmental noise and non-polluting factors on subsequent measurements. The calibration process includes measuring and storing the CMOS sensor base data and setting the CMOS sensor gain. Then, number each detector. B. Constructing a detector group: Install the numbered detectors into the corresponding mounting holes on the main frame according to a specific array density and arrangement, thereby forming a detector group arranged in a planar array. C. Posture Adjustment: The main body mounting frame equipped with the detector is movably connected to the mobile control device via a connecting assembly. The mobile control device is activated, and the main body mounting frame equipped with the detector is lifted to the position directly above the radioactive waste liquid storage tank, with the guide notch of the main body mounting frame aligned vertically with the guide rib of the lifting guide frame. The mobile control device is operated to lower the main body mounting frame equipped with the detector. The guide notch of the main body mounting frame is engaged with the guide rib of the lifting guide frame through the guidance and correction of the avoidance chamfer of the lifting guide frame. At this time, sliding contact is formed between the main body mounting frame and the lifting guide frame, and the guidance of the lifting guide frame ensures that the main body mounting frame descends smoothly and without shaking. The descent stops when the distance between the photosensitive surface of the CMOS sensor and the liquid level of the radioactive waste liquid storage tank is less than 1 cm. D. Data collection: All detectors are activated simultaneously, with each detector scanning a specific area of ​​the radioactive waste liquid storage tank surface. The sampling interval and startup sampling time of all detectors are the same, thereby collecting multiple sets of radiation data. Each set of radiation data contains multiple frames with the same timestamp, and each frame image comes from a corresponding detector. Each detector uploads the collected frame image to the host computer in real time via the wireless communication antenna; S02, feature extraction: The host computer performs the following operations on each set of radiation data: A. Response signal extraction: Convert a set of radiation data into a set of grayscale images, then perform noise removal and background correction operations to extract effective radiation response signals from each grayscale image contained in the set of grayscale images; B. Characteristic parameter calculation: Calculate the characteristic parameters of the extracted radiation response signal, which include one or more of the average pixel value, distribution form, and number of pixels; C. Response signal differentiation: Under the premise that the radiation response signal only contains α and β response signals, the α and β response signals are differentiated from each grayscale image contained in a set of grayscale images based on the inherent differences in the characteristic parameters of the α and β response signals; S03, data shows: A. Grouped display: The host computer displays each set of radiation data after feature extraction on the screen. Each set of radiation data is displayed in sequence according to the timestamp. The display duration of a set of radiation data is the sampling interval of the detector. The display content of a set of radiation data includes the α response signal count and β response signal count obtained by processing multiple grayscale images under the data set. That is, multiple group counts are displayed, which is consistent with the number of grayscale images. Each group count is also marked with the corresponding detector number. B. Alarm mechanism: For detector groups whose α response signal count or β response signal count exceeds a preset threshold, the host computer 9 executes a graded alarm; Level 1 alarm: Level 1 alarm is a local early warning, suitable for short-term minor pollution that requires manual review. When the alpha or beta response signal count of a detector group exceeds the operating threshold during a single sampling, the host computer marks the detector number in real time and displays an orange frame in the corresponding area on the screen. Secondary alarm: Level 2 alarm indicates the need for emergency treatment and is applicable to situations of persistent severe pollution requiring emergency intervention. When the α or β response signal counts of the same detector group exceed the intervention threshold in three consecutive samplings, or the single sampling count exceeds the tolerance threshold, the host computer marks the detector number in real time, displays a red frame in the corresponding area of ​​the screen, and automatically generates a pollution diffusion trend graph, which is superimposed on the center area of ​​the display interface with 50% transparency and 50% screen ratio. The sampling task of the detector group is suspended and an alarm prompt is triggered at the same time. C. Self-check mechanism: When the α or β response signal count of a detector group is 0 for five consecutive samples, the host computer determines that the "detector has failed" and wakes up the detector's cooling fan through Bluetooth commands and checks for voltage fluctuations. If there is no device status feedback within 10 seconds, the point is automatically marked as "faulty" and a yellow alarm is triggered, reminding staff to replace the detector.

10. The multi-point array detection system for radioactive waste surface contamination according to claim 9, wherein: In step 02, the average pixel value is used to represent the overall brightness level of the radiation response signal. The calculation formula is shown in Formula 1; Formula 1: Where M is the average pixel value of the connected area, P is the number of pixels in the connected area, δ is the screening function used to determine whether the target pixel belongs to the connected area, and the connected area is the area occupied by a radiation response signal in the frame image; (i, j) represents the pixel in the i-th row and j-th column, n and m represent the number of rows and columns of pixels respectively, I(i, j) represents the pixel value of the pixel in the i-th row and j-th column, and T is the pixel value threshold of the connected area pixel; In step S02, the number of pixels is the number of pixels in the connected area, which is used to reflect the area size of the radiation response signal. The calculation formula is shown in Formula 2; Formula 2: Where P is the number of pixels in the connected area; In step S02, in the distribution morphology, the α response signal presents a target distribution feature; The target-like distribution characteristics are as follows: the α response signal includes a central area and an annulus from the inside out; the grayscale value of the pixels in the central area is above 230, the grayscale value of the pixels in the annulus is between 30-150, and multiple sub-rings with a descending grayscale value distribution from the inside to the outside of the annulus are formed; the β response signal does not have the target-like distribution characteristics; In step S02, at the 9dB, 32dB or 63dB level, the average pixel value, distribution form and number of pixels of the α response signal are different from those of the β response signal, and the α response signal and the β response signal are distinguished by the differences.

Images