Underwater radioactive foreign matter identification method, device and controller

Abstract

The invention provides an underwater radioactive foreign matter identification method and device and a controller, and the method comprises the steps: controlling an underwater vehicle to cruise according to a preset cruise path, and obtaining the counting rates of four gamma radiation detectors; calculating a cruise detection limit in real time according to the counting rate and cruise local data; calculating a total count measurement value according to the count rate, and comparing the total count measurement value with a cruise detection limit; when the total count measured value is lower than the cruise detection limit, it shows that no radioactive foreign matter is found, cruise continues to be conducted according to the cruise path, and the latest count rate serves as cruise background data to be updated; and when the total count measured value is higher than the cruise detection limit, the radioactive foreign matter exists, and the orientation of the radioactive foreign matter is identified according to the counting rates of the four gamma radiation detectors and the radioactive foreign matter moves. The invention provides an efficient, safe and intelligent underwater radioactive foreign matter recognition and treatment scheme, the overall level of radioactive foreign matter management in the spent fuel pool is remarkably improved, and the method has wide application prospects and popularization value.

Description

Technical Field

[0001] The present invention relates to the technical field of radioactive detectors, and in particular to a method, device and controller for identifying underwater radioactive foreign matter. Background Art

[0002] Spent fuel pools are facilities used to store spent nuclear fuel at nuclear power plants. Filled with cooling water, they provide adequate cooling for the fuel and effectively shield it from radioactive radiation. However, during routine operations and maintenance, radioactive foreign matter, such as partially settled metal fragments, radioactive dust, or other contaminants, may enter the pools. These foreign matter not only adversely affects the cooling water quality within the pools but also poses a potential risk to the plant's safety assessment. The presence of radioactive foreign matter in spent fuel pools requires prompt discovery, identification, and salvage to further determine its source and ensure the safety of the plant's operations.

[0003] Existing technologies for identifying radioactive foreign objects mostly rely on manual inspection or simple radioactivity detectors, which pose radiation exposure risks, as well as untimely identification, low efficiency, and insufficient accuracy. Because underwater radioactive foreign objects are often concealed and highly radioactive, the risk of excessive radiation exposure to inspectors is high. Numerous such incidents have occurred internationally. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method, device and controller for identifying underwater radioactive foreign matter, so as to eliminate the risk of accidental exposure to spent fuel pool operators and maintenance personnel, promptly discover radioactive foreign matter in spent fuel pools, and provide a feasible way to promptly identify radioactive foreign matter and determine its source, thereby improving the safety of nuclear power plants.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a method for identifying underwater radioactive foreign matter, comprising:

[0006] Control the submersible to cruise according to the preset cruise path and obtain the count rates of four gamma radiation detectors;

[0007] Calculate the cruise detection limit in real time based on the count rate and cruise local data;

[0008] calculating a total count measurement based on the count rate and comparing it to the cruise detection limit;

[0009] When the total count measurement value is lower than the cruise detection limit, it indicates that no radioactive foreign matter is found, and the cruise is continued according to the cruise path, and the latest count rate is used as the cruise background data for updating;

[0010] When the total count measurement value is higher than the cruise detection limit, it indicates that there is a radioactive foreign object, and the four gamma radiation detectors identify the location of the radioactive foreign object and move.

[0011] In one embodiment of the present invention, the step of controlling the underwater vehicle to cruise according to a preset cruise path and recording the count rates of four gamma radiation detectors includes:

[0012] The count rates of the four gamma radiation detectors are obtained according to a preset period, where the preset period is a preset time interval or a preset movement distance.

[0013] In one embodiment of the present invention, when the total count measurement value is higher than the cruise detection limit, indicating the presence of radioactive foreign matter, the step of identifying the location of the radioactive foreign matter based on the count rates of the four gamma radiation detectors includes:

[0014] The counting rates of the four gamma radiation detectors are obtained and compared, and the vehicle is controlled to move in the direction of the larger counting rate until the counting rate of one of the four gamma radiation detectors reaches the maximum value.

[0015] In one embodiment of the present invention, the method further comprises: when a certain counting rate of the four gamma radiation detectors reaches a maximum value, performing on-site measurement of the activity concentration of the radioactive foreign matter.

[0016] In one embodiment of the present invention, when a certain count rate of the four gamma radiation detectors reaches a maximum value, the step of measuring the activity concentration of the radioactive foreign matter in situ comprises:

[0017] The detection efficiency of four gamma radiation detectors underwater was obtained in advance by Monte Carlo method;

[0018] Based on the counting rates of each detector, the activity measurement results of the four detectors for radioactive foreign matter are calculated, and the average value is used as the final activity concentration value of the radioactive foreign matter.

[0019] In one embodiment of the present invention, the activity concentration of the radioactive foreign matter is calculated according to the following formula:

[0020] Among them, ε i is the detection efficiency of the i-th detector; N psi is the counting rate of the i-th detector at point p on the path, N pbi is the cruise background count rate of the ith detector at point p; t is the measurement time between two measurements; s is the γ-ray emission rate of the nuclide.

[0021] In one embodiment of the present invention, the method further includes: after determining the location of the radioactive foreign object, floating to the water surface and generating a "foreign object found" signal.

[0022] The present invention also proposes a controller comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the underwater radioactive foreign body identification method described in any one of the above-mentioned embodiments when executing the program.

[0023] The present invention also provides an underwater radioactive foreign body identification device, comprising:

[0024] Underwater unmanned submersible body;

[0025] A gamma radiation detection assembly, which includes four gamma radiation detectors installed around the body of the submersible;

[0026] A processor is used to execute the underwater radioactive foreign matter identification method as described in any one of the above embodiments.

[0027] In one embodiment of the present invention, it further comprises:

[0028] A battery power system is installed inside the submersible to provide a power source for the underwater radioactive foreign body identification device;

[0029] An underwater positioning system, installed inside the submersible, for achieving underwater positioning of the underwater radioactive foreign body identification device;

[0030] The camera is installed in front of the submersible;

[0031] Mechanical claw, installed at the bottom of the submersible.

[0032] The present invention proposes a method, device, and controller for identifying underwater radioactive foreign matter, which have significant technical advantages and practical application value compared to existing technologies. It has the following beneficial effects:

[0033] The present invention uses automated equipment instead of manual labor to detect and salvage radioactive foreign matter, effectively avoiding the potential risks of workers working in a high-radiation environment and reducing excessive or accidental exposure incidents caused by direct contact with radioactive sources.

[0034] This invention utilizes a compact, lightweight, and high-energy-resolution cadmium zinc telluride (CTZ) hemispherical detector. This not only solves the problem of autonomous navigation in complex underwater environments, but also overcomes the maintenance difficulties associated with conventional high-purity germanium (HPGe) and sodium iodide (NaI) detectors. The CTZ detector operates at room temperature and requires no external power cord for real-time power, improving system reliability and adaptability.

[0035] The automatic salvage device configured in the present invention can automatically complete the foreign body grabbing and transporting operations after discovering radioactive foreign matter, further reducing the risk of personnel working in high-radiation areas and ensuring the safety of personnel.

[0036] This method uses a method based on differences in detector count rate ratios to accurately locate radioactive foreign objects. It is particularly suitable for identifying and finding small or hidden radioactive sources. By comparing the response data from four gamma radiation detectors, the direction of the radioactive foreign object can be quickly and accurately determined, guiding the submersible to the target location. This solves the problem of traditional methods making it difficult to detect and locate small foreign objects.

[0037] This invention combines regular patrols with foreign object salvage, allowing personnel to intervene only when equipment detects an anomaly, significantly reducing the workload of daily operations and maintenance. This model also significantly increases the probability of timely detection of radioactive foreign objects, enhancing the safety and controllability of nuclear power plant operations.

[0038] This method uses underwater detection instead of traditional surface detection, reducing the shielding effect of water on radioactive foreign objects and improving detection sensitivity and accuracy. Because radioactive foreign objects are often located underwater, this method can more effectively capture low-intensity radiation signals, ensuring the reliability of detection results.

[0039] In summary, the present invention provides an efficient, safe, and intelligent solution for underwater radioactive foreign matter identification and treatment, which not only solves many deficiencies in the existing technology, but also significantly improves the overall level of radioactive foreign matter management in spent fuel pools, and has broad application prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 The figure is a flowchart of a method for identifying underwater radioactive foreign matter in one embodiment of the present invention.

[0042] Figure 2 The present invention is a flowchart of a method for identifying underwater radioactive foreign matter in one embodiment.

[0043] Figure 3 The figure is a structural block diagram of an underwater radioactive foreign body identification device in one embodiment of the present invention.

[0044] Figure 4The figure is a schematic diagram of an underwater radioactive foreign body identification radiation detector according to one embodiment of the present invention. DETAILED DESCRIPTION

[0045] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0046] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0047] See also Figure 1 As shown, the present invention provides a method for underwater radioactive foreign matter identification. This method aims to improve the efficiency and accuracy of radioactive foreign matter detection in spent fuel pools through automated devices and intelligent algorithms, while also reducing the risk of human exposure to radiation. The following is a detailed description of the specific implementation steps of this method:

[0048] S1. Control the submersible to cruise according to the preset cruise path and obtain the count rates of four gamma radiation detectors;

[0049] First, the vehicle's cruise path is pre-set based on the spent fuel pool's structure and the response range of its underwater gamma radiation detectors. The vehicle is equipped with four gamma radiation detectors (e.g., Cadmium Zinc Telluride Hemispherical CTZ detectors), mounted on the four sides of the vehicle's sealed cabin. As the vehicle autonomously cruises along the pre-set path, it acquires count rate data from these four detectors in real time.

[0050] Understandably, before underwater radioactive foreign matter identification can be performed, the vehicle's automated cruising path must be pre-planned based on the spent fuel pool's structural characteristics and the response range of the underwater gamma radiation detector. This path is designed to ensure that even radioactive foreign matter scattered anywhere within the spent fuel pool can be effectively detected by the gamma radiation detector.

[0051] To effectively cover the entire spent fuel pool, the pool's geometry, internal structure, and the attenuation characteristics of gamma rays propagating through water must first be analyzed. The effective detection range of gamma radiation detectors is determined by considering the energy range of gamma rays emitted by possible radioactive foreign matter and the shielding effect of water on gamma rays. Based on this, the inspection routes of the submersible are set, with spacing no greater than 1 meter to ensure that there are no blind spots between adjacent routes.

[0052] Before the spent fuel pool is put into operation or after each batch of spent fuel is loaded or unloaded, the vehicle conducts a comprehensive cruise measurement along a pre-set route, confirming the absence of radioactive foreign matter within the pool. The vehicle records the count rates of the four gamma radiation detectors at each location and stores this data as cruise background data. This background data is used to calculate the cruise limit of detection (LLD) in real time during each subsequent cruise, thereby determining the presence of abnormal radioactive sources.

[0053] During routine operations, the vehicle automatically initiates patrol missions at a set interval (e.g., daily), monitoring the radioactive environment throughout the spent fuel pool along a pre-set path. During patrol, the system continuously collects count rate data from four gamma radiation detectors and calculates the patrol detection limit at that location in real time based on the patrol background data corresponding to the current location.

[0054] In this embodiment, the present invention further optimizes the method for collecting gamma radiation detector data during the cruise process of the underwater vehicle. Specifically, the steps of controlling the underwater vehicle to cruise according to a preset cruise path and recording the count rates of the four gamma radiation detectors include:

[0055] As the vehicle autonomously navigates along a preset cruising path, the system periodically collects count rate data from the four gamma radiation detectors according to a preset period. The preset period can be based on a time interval (e.g., every 5 seconds) or the vehicle's travel distance (e.g., every 0.5 meters). This period is determined based on factors such as the size of the spent fuel pool, the spatial resolution of the gamma radiation detectors, and the desired detection sensitivity. This periodic collection method helps achieve uniform coverage and continuous monitoring of the entire spent fuel pool, avoiding the risk of missed detections due to too few sampling points. It also improves the accuracy and stability of subsequent data analysis. In some preferred embodiments, the preset period can be dynamically adjusted based on actual operating conditions. For example, when approaching a known high-radiation area, the collection period can be shortened to increase detection density; in areas with low background radiation and no abnormal signals, the collection period can be appropriately extended to conserve system resources and improve overall efficiency.

[0056] Furthermore, to ensure data reliability, each collected gamma radiation detector count rate is filtered (e.g., by sliding average or median filtering) to remove transient noise. Data from the four detectors are then fused and analyzed for subsequent calculation of the total count value and comparison with the cruise limit of detection (LLD).

[0057] It can be understood that by setting a reasonable preset period to collect the count rate of the gamma radiation detector, the present invention achieves efficient, stable and continuous monitoring of the radioactive environment in the spent fuel pool, providing a reliable data basis for the timely discovery and accurate positioning of radioactive foreign matter.

[0058] S2. Calculating the cruise detection limit in real time based on the count rate and the cruise local data;

[0059] Before each cruise or periodically, measurements are taken of the spent fuel pool in a clear state. The gamma radiation detector count rates at various locations are recorded as cruise background data. During the cruise, the cruise limit of detection (LLD) is calculated in real time based on the currently measured count rate and the saved cruise background data. The calculation formula for the cruise limit of detection (LLD) is:

[0060] Among them, N psi is the counting rate of the i-th detector at point p on the path, N pbi is the cruise background count rate of the i-th detector at point p.

[0061] S3. Calculating a total count measurement value based on the count rate and comparing it with the cruise detection limit;

[0062] For each point on the cruise path, the count rates of the four gamma radiation detectors are summed to obtain a total count measurement value. This total count measurement value is then compared with the corresponding cruise detection limit. The total count measurement value N pn The calculation formula is:

[0063] Among them, N psi is the counting rate of the i-th detector at point p on the path, N pbi is the cruise background count rate of the i-th detector at point p.

[0064] S4. When the total count measurement value is lower than the cruise detection limit, it means that no radioactive foreign matter is found, and the cruise is continued according to the cruise path, and the latest count rate is used as the cruise background data for updating.

[0065] If the total count measurement falls below the cruise detection limit, indicating there are no radioactive foreign objects in the current area, the vehicle will continue along the pre-set cruise path and update the latest count rate as the new cruise background data, providing a more accurate reference value for subsequent cruises.

[0066] S5. When the total count measurement value is higher than the cruise detection limit, it indicates that there is a radioactive foreign body. Then, the position of the radioactive foreign body is identified according to the count rate of the four gamma radiation detectors and the position is moved.

[0067] When the total count measurement exceeds the cruise detection limit, it indicates the detection of a potential radioactive foreign object. The system then further analyzes the difference in count rates among the four gamma radiation detectors to determine the object's direction. Based on the characteristic that radioactive radiation intensity decays inversely with the square of distance, the direction with the largest count ratio between the two detectors represents the approximate direction of the radioactive foreign object. The vehicle then proceeds in that direction, continuously adjusting its course until it approaches the object.

[0068] In addition, after approaching the target, the vehicle can use tools such as mechanical claws to salvage radioactive foreign matter and move it to a designated safe location for disposal.

[0069] See also Figure 2 and Figure 4 Specifically, based on the above embodiment, the present invention further optimizes the specific steps for identifying the location of a radioactive foreign object and guiding the submersible vehicle toward the object when the total count measurement value exceeds the cruise detection limit. Specifically, when the total count measurement value exceeds the cruise detection limit, indicating the presence of a radioactive foreign object, the step of identifying the location of the radioactive foreign object based on the count rates of the four gamma radiation detectors includes: obtaining and comparing the count rates of the four gamma radiation detectors; obtaining and comparing the count rates of the four gamma radiation detectors, and controlling the submersible vehicle to move in the direction of the larger count rate until the count rate of one of the four gamma radiation detectors reaches a maximum value.

[0070] When a total count measurement exceeds the preset cruise detection limit during a cruise, it indicates the presence of radioactive foreign matter in the area. At this point, the system first acquires real-time count rate data from four gamma radiation detectors (such as cadmium telluride zinc hemispherical detectors (CTZs)). These detectors are mounted on four sides of the vehicle's sealed cabin, providing all-around coverage. The system collects and analyzes the count rates from the four gamma radiation detectors, calculating the relative response intensity differences between each detector. Because the intensity of radioactive radiation decays inversely with the square of the distance, detectors with higher count rates are generally closer to the radiation source.

[0071] Based on the comparison results of the count rates of the four gamma radiation detectors, the system determines the direction most likely pointing to the radioactive foreign object. Specifically, by calculating the count rate ratios between adjacent detectors (for example: CZT_+X / CZT_-X, CZT_+Y / CZT_-Y), the azimuth of the radioactive foreign object relative to the submersible can be identified. The submersible adjusts its course based on this azimuth information and moves in the direction of a larger count rate. During the movement, the submersible continuously updates the count rate data of the four gamma radiation detectors and adjusts its course in real time to ensure that it continues to approach the radioactive foreign object. This process is similar to the gradient ascent algorithm, which ultimately locates the specific location of the radioactive foreign object through step-by-step approximation.

[0072] As the vehicle approaches a radioactive foreign object, the count rate of one or more of its four gamma radiation detectors will increase significantly. When the count rate of one of these detectors reaches its peak, the vehicle has reached its closest approach to the object. At this point, the system stops the vehicle's automatic navigation and switches to manual or semi-automatic mode, allowing the operator to further confirm the object's specific location. During this phase, the vehicle's built-in camera sensor captures images of its surroundings, assisting the operator in accurately identifying the object's appearance and location. The system also measures the radionuclide information and activity concentration of the radioactive foreign object in detail, using Monte Carlo methods to calculate the detection efficiency value, allowing for a precise assessment of the object's hazard level.

[0073] It is understood that once the radioactive foreign object is accurately located, the submersible can use tools such as mechanical claws to salvage the foreign object and transfer it to a designated safe area for subsequent processing. Throughout the entire process, all relevant data (including location information, radionuclide type, activity concentration, etc.) will be recorded for subsequent analysis and reference.

[0074] By acquiring and comparing the count rates of four gamma radiation detectors and controlling the vehicle's movement toward the direction of higher count rates until a particular count rate reaches its maximum, this method efficiently identifies and precisely locates radioactive foreign matter within a spent fuel pool. This method not only improves detection accuracy and reliability but also reduces the radiation risks associated with manual intervention, offering significant application value and potential for widespread adoption.

[0075] See also Figure 1 、 Figure 2 and Figure 4As shown, in this embodiment, the method further includes: when a certain counting rate of the four gamma radiation detectors reaches a maximum value, the activity concentration of the radioactive foreign matter is measured on-site. Specifically, when a certain counting rate of the four gamma radiation detectors reaches a maximum value, the activity concentration of the radioactive foreign matter is measured on-site. It can be understood that when the submersible gradually approaches the radioactive foreign matter and the counting rate of one of the gamma radiation detectors reaches a maximum value, it indicates that the submersible has reached the position closest to the radioactive foreign matter. At this time, the system will start the process of measuring the activity concentration of the radioactive foreign matter on-site. Specifically, it includes the following steps:

[0076] S61. Calculate the underwater detection efficiency of four gamma radiation detectors in advance using the Monte Carlo method;

[0077] To accurately measure the activity concentration of radioactive foreign matter, it is first necessary to determine the underwater detection efficiency of each gamma radiation detector. Because water absorbs and scatters gamma rays, the propagation characteristics of gamma rays of different energies in water vary. Therefore, before actual measurements, the detector's response characteristics in water must be modeled and calculated using Monte Carlo simulation.

[0078] Specifically, using Monte Carlo particle transport simulation software (such as MCNP and Geant4), a virtual model was constructed that included the spent fuel pool structure, radioactive foreign matter, and four gamma radiation detectors. By simulating the propagation of gamma rays of varying energies through water, the actual detection efficiency of each detector for gamma rays emitted by a specific nuclide was calculated. These detection efficiencies served as key parameters in subsequent activity concentration calculations.

[0079] S62. Calculate the activity measurements of the radioactive foreign matter by the four detectors based on the count rates of each detector, and use the average value as the final activity concentration of the radioactive foreign matter. After completing the pre-calculation of the detection efficiency, the system quantitatively analyzes the activity concentration of the radioactive foreign matter based on the real-time count rate data of the four gamma radiation detectors and the pre-calculated detection efficiency values. The activity concentration of the radioactive foreign matter is calculated according to the following formula:

[0080] Among them, ε i is the detection efficiency of the i-th detector; N psi is the counting rate of the i-th detector at point p on the path, N pbi is the cruise background count rate of the i-th detector at point p; t is the measurement time between two measurements; s is the gamma-ray emission rate of the nuclide, which is determined by the nuclide, that is, different radionuclides have different s values, and is the physical constant of the nuclide.

[0081] Taking into account the possibility of slight differences in response between different detectors, the system calculates the activity measurement results corresponding to each of the four detectors and takes the average of these results as the final activity concentration value of the radioactive foreign matter. This effectively reduces measurement deviations caused by errors in individual detectors and improves overall measurement accuracy.

[0082] In addition, during actual operation, the reliability of the measurement results can be further improved by repeating the measurement multiple times and taking the average value. All relevant data (including location information, nuclide type, activity concentration, etc.) will be recorded for subsequent analysis and reference. It can be understood that by using the Monte Carlo method to calculate the detection efficiency of the gamma radiation detector underwater in advance, and calculating the activity concentration of radioactive foreign matter based on the detector counting rate, the present invention realizes the efficient identification and precise positioning of radioactive foreign matter in the spent fuel pool. This method not only improves the detection accuracy and reliability, but also reduces the radiation risk caused by manual intervention, and has significant application value and promotion prospects.

[0083] See also Figure 1 and Figure 2 As shown, in this embodiment, the method further includes: after determining the location of the radioactive foreign object, floating to the water surface and generating a "foreign object found" signal. Specifically, when the submersible confirms through the counting rate analysis of the four gamma radiation detectors that it has reached the position closest to the radioactive foreign object, the system will record the precise coordinate information of the current submersible. These coordinate information can be obtained through an underwater positioning system (such as an acoustic positioning system or an inertial navigation system) and matched with a pre-stored spent fuel pool map to ensure positioning accuracy. Once the specific location of the radioactive foreign object is determined, the submersible will execute an automatic floating procedure and gradually rise to the surface of the spent fuel pool. During this process, the control system will switch the working mode from automatic cruise / positioning mode to salvage preparation mode. The specific operations are as follows:

[0084] Control system mode switching: The control system switches the vehicle's operating mode from automatic cruise mode to salvage preparation mode based on pre-set logic. In this mode, the vehicle's primary task is to safely ascend to the surface and establish a communication link with shore personnel.

[0085] Attitude adjustment during the ascent process: To ensure the safety and stability of the ascent process, the submersible performs real-time attitude adjustment through the built-in attitude control system (such as thrusters, servos, etc.) to avoid deviation from the predetermined path due to water flow or other external factors.

[0086] Sending a "Foreign Object Detected" Signal: When the submersible successfully surfaces, it immediately transmits a "Foreign Object Detected" notification signal to the monitoring center or personnel on shore via the wireless communication module. This signal contains the following key information: the specific location of the radioactive foreign object (3D coordinates), preliminary detection results (such as radionuclide type and activity concentration), and a status report on the submersible (such as remaining battery power and equipment health).

[0087] Staff response and subsequent actions: Upon receiving the "foreign object found" signal, staff will respond quickly and take the following measures:

[0088] Arrival at the site: Workers go to the spent fuel pool area and prepare the necessary tools and equipment (such as external power supply, communication cables, salvage tools, etc.).

[0089] Connecting external power and communication cables: The crew connected the submersible to an external power source on shore to ensure sufficient power to support subsequent salvage operations. They also connected a wired communication interface so that the host computer could monitor the submersible's various parameters and status in real time.

[0090] Activating the underwater camera and robotic claw: Using the host computer software, staff can remotely control the submersible to dive back to the location of the radioactive foreign object. Using the underwater camera, they can observe the surrounding environment and confirm the object's specific shape and location. They can then use tools such as the robotic claw to salvage the radioactive foreign object.

[0091] Real-time monitoring and data feedback: Throughout the salvage process, the host computer will continuously display the current position of the submersible, detector measurement results, and other relevant information, ensuring that operators can make timely adjustments and decisions.

[0092] Place foreign objects at a designated location: After successfully salvaging radioactive foreign objects, the submersible will move them to a designated safe storage area for further processing and disposal by professionals.

[0093] In summary, this invention achieves rapid response and precise handling of radioactive foreign matter within the spent fuel pool by locating the foreign object and automatically surfacing the submersible to the surface and transmitting a "foreign object detected" signal. Combined with the control system's operating mode switching and signal communication capabilities, this system not only improves work efficiency but also ensures operational safety and reliability, demonstrating significant application value and potential for widespread adoption.

[0094] See also Figure 2 、 Figure 3 and Figure 4As shown, in this embodiment, the present invention provides an underwater unmanned vehicle device for identifying radioactive foreign objects in spent fuel pools. Its design aims to achieve automated patrol detection, precise positioning, and safe salvage of radioactive foreign objects. The following is a detailed description of the device's specific structure and functions:

[0095] The underwater unmanned vehicle body 10 serves as the foundational platform for the entire identification system and features excellent sealing properties to adapt to underwater operating environments. The vehicle body primarily consists of a sealed cabin and an underwater propulsion system. The underwater propulsion system includes three thrusters: two underwater thrusters 11 mounted on either side of the vehicle body 10, controlled by a steering stepper motor 12; and an underwater steering thruster 13 located at the rear of the vehicle body 10, which adjusts its direction of travel by rotating its propeller clockwise or counterclockwise. This configuration enables the vehicle to maneuver flexibly in three dimensions, meeting the requirements of autonomous cruising and foreign object recovery.

[0096] The gamma radiation detection assembly, the core component of the identification device, monitors underwater radioactivity levels in real time. This assembly comprises four cadmium zinc telluride (CTZ) hemispherical gamma radiation detectors, designated CZT+X detector 21, CZT-X detector 22, CZT+Y detector 23, and CZT-Y detector 24, respectively. The zero point is located at the center of the identification device. Each detector measures 1 cm (length) × 1 cm (width) × 0.5 cm (thickness) and features high energy resolution, a wide operating temperature range, and a compact size. These four detectors are mounted on four sides of the vehicle's sealed cabin, spaced approximately 10 to 20 cm apart to ensure full coverage. The detector readout signals are processed by a four-channel multichannel analyzer and integrated into an FPGA, enabling a compact signal processing system and further reducing the vehicle's size.

[0097] It is understood that the identification device employs an intelligent identification and navigation method based on the inverse square decay property of gamma-ray intensity with distance to determine the location of a radioactive foreign object and guide the submersible to its target location. This method enables efficient positioning and precise approximation of radioactive foreign objects, and has excellent engineering application value. Specifically, when a radioactive foreign object is located underwater, the four gamma-ray detectors (labeled CZT_+X, CZT_-X, CZT_+Y, and CZT_-Y) mounted around the submersible will produce different response count rates depending on their relative positions. By comparing the count rates between two opposing detectors (e.g., CZT_+X and CZT_-X or CZT_+Y and CZT_-Y), the direction of the radioactive foreign object relative to the submersible can be determined. Specifically, the direction with the highest count rate between the two detectors indicates the most likely location of the radioactive foreign object. For example, if the count rate of the CZT_+X detector is significantly higher than that of the CZT_-X detector, this indicates that the radioactive foreign object is closer to the +X direction; the same logic can be used to deduce other directions. After determining the approximate direction of the radioactive foreign object, the control system guides the submersible in that direction, continuously collecting and updating the response data of the four gamma radiation detectors throughout the movement. The system calculates the count ratio between the detectors in real time and dynamically adjusts the submersible's navigation direction based on the latest results, ensuring that it always approaches the radioactive foreign object.

[0098] The battery power system 30 is installed centrally within the submersible, separating the four CdZnTe detectors. The battery not only provides power for the device's automatic cruise control but also acts as a gamma-ray shield, minimizing the radiation response differences between the detectors. In salvage mode, the battery can be switched to an external power source to ensure extended operation.

[0099] Underwater positioning system 40 is also installed inside the submersible and is used for precise underwater positioning. This system uses acoustic positioning or other advanced positioning technologies (such as an inertial navigation system) to determine the submersible's three-dimensional coordinates in the water, ensuring the accuracy of the inspection path and the precise location of radioactive foreign objects.

[0100] Camera 50, mounted directly in front of the underwater unmanned vehicle body 10, captures images of the surrounding environment, assisting operators in identifying the specific form and location of radioactive foreign matter. The camera's image data can be transmitted via wireless or wired communication to a shore-based monitoring center for real-time review and decision-making.

[0101] A mechanical claw 60 is mounted on the bottom of the underwater unmanned vehicle body 10 and is used to grab and salvage radioactive foreign objects. Once the vehicle approaches and locates the radioactive foreign object, the operator can remotely control the movement of the mechanical claw through the host computer software to move the foreign object to a designated safe storage area.

[0102] The controller 70 includes a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the program to implement the steps of the underwater radioactive foreign body identification method described in the above embodiment. Specifically, the following steps are implemented:

[0103] Control the submersible to cruise according to the preset cruise path and obtain the count rates of four gamma radiation detectors;

[0104] Calculate the cruise detection limit in real time based on the count rate and cruise local data;

[0105] calculating a total count measurement based on the count rate and comparing it to the cruise detection limit;

[0106] When the total count measurement value is lower than the cruise detection limit, it indicates that no radioactive foreign matter is found, and the cruise is continued according to the cruise path, and the latest count rate is used as the cruise background data for updating;

[0107] When the total count measurement value is higher than the cruise detection limit, it indicates that there is a radioactive foreign object, and the position of the radioactive foreign object is identified and moved according to the count rates of the four gamma radiation detectors.

[0108] Specifically, the controller performs the following tasks:

[0109] Data acquisition and processing: Count rate data from four gamma radiation detectors are acquired in real time, and the total count measurement value and cruise detection limit (LLD) are calculated based on this data.

[0110] Path planning and navigation: Control the movement of the submersible according to the preset cruise path and dynamically adjust the heading based on the detection results.

[0111] Signal communication: supports wireless communication and wired communication to ensure data transmission between the submersible and the onshore monitoring center.

[0112] Mode switching: After discovering radioactive foreign objects, switch to salvage preparation mode and send a "foreign object found" signal to the staff.

[0113] As will be appreciated, the system also includes an external power supply communication interface 80 for connecting an external power source and a communication cable. Specifically, personnel connect the submersible to an external power source on shore to ensure sufficient power for subsequent salvage operations. Simultaneously, a wired communication interface is connected to allow the host computer to monitor the submersible's various parameters and status in real time.

[0114] This method enables efficient and automated identification and location of radioactive foreign matter within spent fuel pools, significantly improving the safety and intelligence of nuclear power plant operations and maintenance, and reducing the radiation risks associated with manual intervention. Furthermore, the method combines advanced sensing technology with an intelligent control system, enabling comprehensive coverage and real-time monitoring, improving detection efficiency and accuracy.

[0115] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

[0116] In the description herein, numerous specific details, such as examples of components and / or methods, are provided to provide a complete understanding of the embodiments of the present invention. However, those skilled in the art will recognize that embodiments of the present invention may be practiced without one or more of the specific details or with other devices, systems, assemblies, methods, components, materials, parts, etc. In other cases, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of the embodiments of the present invention.

[0117] Reference throughout this specification to "one embodiment," "an embodiment," or "a specific embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and not necessarily in all embodiments. Thus, various appearances of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the invention may be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein are possible in light of the teachings herein and are considered part of the spirit and scope of the invention.

[0118] It should also be understood that one or more of the elements shown in the figures may also be implemented in a more separate or more integrated manner, or even removed because they are inoperable in certain circumstances or provided because they may be useful depending on the application.

[0119] In addition, unless otherwise expressly indicated, any marking arrows in the drawings should be regarded as illustrative only and not limiting. Furthermore, unless otherwise indicated, the term "or" as used herein is generally intended to mean "and / or." Where a term is unclear in providing separation or combination capabilities, the combination of components or steps will also be considered as indicated.

[0120] As used in the description herein and throughout the claims that follow, “a,” “an,” and “the” include plural references unless otherwise indicated. Likewise, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless otherwise indicated.

[0121] The above description of the illustrated embodiments of the present invention (including that described in the Abstract) is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. Although specific embodiments of the present invention and examples of the present invention are described herein for illustrative purposes only, as those skilled in the art will recognize and appreciate, various equivalent modifications are possible within the spirit and scope of the present invention. As noted, modifications may be made to the present invention in light of the above description of the illustrated embodiments of the present invention, and such modifications will be within the spirit and scope of the present invention.

[0122] Systems and methods have been generally described herein in detail to facilitate understanding of the present invention. In addition, various specific details have been given to provide an overall understanding of embodiments of the present invention. However, those skilled in the relevant art will recognize that embodiments of the present invention may be practiced without one or more of these specific details, or with other devices, systems, accessories, methods, components, materials, parts, etc. In other cases, well-known structures, materials, and / or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention.

[0123] Thus, although the invention has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are contemplated within the foregoing disclosure, and it should be understood that in some cases, some features of the invention will be employed without the corresponding use of other features without departing from the scope and spirit of the claimed invention. Thus, many modifications may be made to adapt a particular environment or material to the true scope and spirit of the invention. The invention is not intended to be limited to the specific terminology used in the claims below and / or to the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but the invention is intended to include any and all embodiments and equivalents falling within the scope of the appended claims. Thus, the scope of the invention will be determined solely by the appended claims.

Claims

1. A method for identifying underwater radioactive foreign matter, characterized in that: include: Control the submersible to cruise according to the preset cruise path and obtain the count rates of four gamma radiation detectors; Calculate the cruise detection limit in real time based on the count rate and cruise local data; calculating a total count measurement based on the count rate and comparing it to the cruise detection limit; When the total count measurement value is lower than the cruise detection limit, it indicates that no radioactive foreign matter is found, and the cruise is continued according to the cruise path, and the latest count rate is used as the cruise background data for updating; When the total count measurement value is higher than the cruise detection limit, it indicates that there is a radioactive foreign object, and the position of the radioactive foreign object is identified and moved according to the count rate values ​​of the four gamma radiation detectors.

2. The underwater radioactive foreign body identification method according to claim 1, characterized in that: The steps of controlling the submarine to cruise according to a preset cruise path and recording the count rates of four gamma radiation detectors include: The count rates of the four gamma radiation detectors are obtained according to a preset period, where the preset period is a preset time interval or a preset movement distance.

3. The underwater radioactive foreign body identification method according to claim 1, characterized in that: When the total count measurement value is higher than the cruise detection limit, it indicates that a radioactive foreign object exists, and the step of identifying the location of the radioactive foreign object according to the count rates of the four gamma radiation detectors includes: The counting rates of the four gamma radiation detectors are obtained and compared, and the vehicle is controlled to move in the direction of the larger counting rate until the counting rate of one of the four gamma radiation detectors reaches the maximum value.

4. The underwater radioactive foreign body identification method according to claim 3, characterized in that: The method further comprises: when a certain counting rate of the four gamma radiation detectors reaches a maximum value, performing on-site measurement of the activity concentration of the radioactive foreign matter.

5. The underwater radioactive foreign body identification method according to claim 4, characterized in that: When a certain count rate of the four gamma radiation detectors reaches a maximum value, the step of measuring the activity concentration of the radioactive foreign matter on site comprises: The detection efficiency of four gamma radiation detectors underwater was obtained in advance by Monte Carlo method; Based on the counting rates of each detector, the activity measurement results of the four detectors for radioactive foreign matter are calculated, and the average value is used as the final activity concentration value of the radioactive foreign matter.

6. The underwater radioactive foreign body identification method according to claim 5, characterized in that: The activity concentration of the radioactive foreign matter is calculated according to the following formula: Among them, ε i is the detection efficiency of the i-th detector; N psi is the counting rate of the i-th detector at point p on the path, N pbi is the cruise background count rate of the ith detector at point p; t is the measurement time between two measurements; s is the γ-ray emission rate of the nuclide.

7. The underwater radioactive foreign body identification method according to claim 5, characterized in that: The method further includes: after determining the location of the radioactive foreign object, floating to the water surface and generating a "foreign object found" signal.

8. A controller, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the underwater radioactive foreign body identification method according to any one of claims 1 to 7 are implemented.

9. An underwater radioactive foreign body identification device, characterized in that: include: Underwater unmanned submersible body; A gamma radiation detection assembly, which includes four gamma radiation detectors installed around the body of the submersible; A processor, configured to execute the underwater radioactive foreign matter identification method according to any one of claims 1 to 7.

10. The underwater radioactive foreign body identification device according to claim 9, characterized in that: Also includes: A battery power system, installed inside the submersible, for providing a power source for the underwater radioactive foreign body identification device; An underwater positioning system, installed inside the submersible, for achieving underwater positioning of the underwater radioactive foreign body identification device; The camera is installed in front of the submersible; Mechanical claw, installed at the bottom of the submersible.

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