Nuclear power plant pressure vessel radioactivity detection apparatus, device and method

Abstract

The application discloses a nuclear power plant pressure vessel radioactive detection device, equipment and method. The device is used for source term investigation of an old top cover of a pressure vessel and comprises a gamma energy spectrum measurement module, a gamma dose rate measurement module and a loading module. The gamma energy spectrum measurement module and the gamma dose rate measurement module are arranged on the loading module. The loading module is provided with a loading driving element and a driving wheel. The loading driving element and the driving wheel are in transmission connection to drive the driving wheel to rotate and drive the loading module to move, so that the gamma energy spectrum measurement module can be moved to the spherical center of the old top cover and detect the old top cover. The device can move the gamma energy spectrum measurement module to the spherical center of the old top cover, ensure that the distance between the detector center and each region of the inner surface of the top cover is the same, thereby reducing the error of source term detection of the old top cover and improving the accuracy of source term detection of the old top cover.

Description

Technical Field

[0001] This invention relates to the field of nuclear power technology, and in particular to a radioactive detection device, equipment and method for pressure vessels in nuclear power plants. Background Technology

[0002] In the field of nuclear power generation, the pressure vessel, as a key component of the nuclear reactor, directly affects the stable operation of the nuclear power plant due to the integrity and safety of its top cover. As nuclear power plants age, the old top covers, subjected to long-term high temperatures, high pressures, and radiation, will experience aging and corrosion, necessitating replacement when necessary. Currently, only the Daya Bay Nuclear Power Plant and the Qinshan Nuclear Power Plant in China have successfully completed the replacement of their old pressure vessel top covers.

[0003] In the replacement project of the old roof at the Daya Bay Nuclear Power Plant, technicians used a theoretical calculation-based method to assess the radioactive source terms of the old roof. This method primarily relies on the neutron flux distribution in the reactor core, using simulation calculations to predict the types of radionuclides and their total radioactivity levels produced after the old roof is activated by neutrons. Simultaneously, it also attempted to estimate the types of radionuclides and their total activity deposited on the inner surface of the old roof by activation corrosion products from the primary coolant. However, this method has significant drawbacks:

[0004] Due to the complex variations in neutron flux in the reactor core and the limitations of theoretical calculation methods, there is a significant discrepancy between the theoretically calculated activation source terms of the old top cover and the actual source terms, making it impossible to accurately reflect the true activation status of each region of the top cover.

[0005] The deposition process of corrosion products from the primary coolant on the inner surface of the old top cover is extremely complex and uneven. Therefore, theoretical estimation alone is insufficient to determine the specific location and radioactivity level of the corrosion products on the inner surface of the top cover, thus failing to provide targeted guidance for subsequent decontamination treatment.

[0006] In view of the shortcomings of theoretical calculation methods, patent number CN115954123A proposes a new technical solution. This solution aims to directly measure and evaluate the radioactive source term of an old roof by constructing a specialized investigation device. The design of this device encompasses its structural composition, working principle, and investigation methods, providing a new approach to the investigation of the source term of old roofs.

[0007] However, the technical solution proposed in patent number CN115954123A has the following problems:

[0008] Because the distance between the detector center and different areas of the inner surface of the top cover varies, the measurement results are affected by the corrections made by the physical model theory, thus introducing a certain measurement error. This error may affect the accuracy of source term assessment, thereby adversely impacting subsequent decontamination treatment decisions. Summary of the Invention

[0009] The purpose of this invention is to provide a radioactive detection device, equipment, and method for pressure vessels in nuclear power plants, aiming to solve the problems of large errors and low accuracy in the source term detection of existing old top covers.

[0010] This invention provides a radioactive detection device for a nuclear power plant pressure vessel, used for source term investigation of an old pressure vessel top cover. The device includes a gamma-ray spectrum measurement module, a gamma-ray dose rate measurement module, and a loading module. Both the gamma-ray spectrum measurement module and the gamma-ray dose rate measurement module are mounted on the loading module. The loading module is equipped with a loading drive component and a drive wheel. The loading drive component and the drive wheel are connected by a transmission mechanism to drive the drive wheel to rotate and move the loading module, allowing the gamma-ray spectrum measurement module to move to the center of the old top cover and perform detection on it.

[0011] Furthermore, the loading module includes a loading bracket, the gamma spectrum measurement module and the gamma dose rate measurement module are both disposed on one side of the loading bracket, the loading drive is installed on the other side of the loading bracket, and the drive wheel is disposed on the other side of the loading bracket.

[0012] Furthermore, the loading module also includes a drive rod, and multiple loading drive components and drive wheels are provided, wherein every two drive wheels are connected by a drive rod, the drive rod is rotatably disposed on the other side of the loading bracket, and at least one loading drive component is pulsatorically connected to the drive rod to drive the drive rod to rotate and drive the drive wheel to rotate.

[0013] Furthermore, the nuclear power plant pressure vessel radioactivity detection device includes a power cable and a measurement and control cable, and the loading module further includes a cable drag chain, which is mounted on the loading bracket to limit the range of motion of the power cable and the measurement and control cable.

[0014] Furthermore, the loading module also includes a laser rangefinder, which is mounted on the loading bracket to determine the distance between the loading module and a preset reference origin.

[0015] Furthermore, the gamma spectrum measurement module includes: a gamma spectrum detector, a turntable, a detector support platform, a support base, a lifting assembly, a rotation drive, and a tilting drive. The tilting drive is driven by the gamma spectrum detector to drive the gamma spectrum detector to rotate along a horizontal axis. The tilting drive is disposed on the turntable. The rotation drive is driven by the turntable to drive the turntable to rotate along a vertical axis. The rotation drive and the turntable are disposed on the detector support platform. The lifting assembly is driven by the detector support platform to drive the detector support platform to rise and fall. The lifting assembly is disposed on the support base, and the support base is disposed on the loading module.

[0016] Furthermore, the lifting assembly includes a lifting drive, a slide rail, and a slider. The lifting drive and the slide rail are both mounted on the support base. One side of the slider is mounted on the detector support platform, and the other side of the slider is slidably mounted on the slide rail. The driving end of the lifting drive is connected to the slider to drive the slider to slide on the slide rail.

[0017] Furthermore, the gamma spectrum measurement module also includes a stop block and a detection element, wherein the stop block is disposed on the tilting drive element and the detection element is disposed on the detector support platform.

[0018] Furthermore, it also includes: an electrical control cabinet, which is mounted on the loading module and is electrically connected to the gamma spectrum measurement module, the gamma dose rate measurement module and the loading module respectively.

[0019] This invention also provides a radioactive detection device for a nuclear power plant pressure vessel, comprising: the aforementioned radioactive detection device for a nuclear power plant pressure vessel.

[0020] Furthermore, it also includes: a source term investigation software platform and a switch, wherein the source term investigation software platform is signal-connected to the gamma spectrum measurement module, the gamma dose rate measurement module and the loading module through the switch.

[0021] This invention also provides a method for detecting radioactivity in a nuclear power plant pressure vessel, which is applied to the aforementioned radioactivity detection equipment for nuclear power plant pressure vessels, and includes:

[0022] Set a reference origin and drive the loading module to move directly below the old top cover;

[0023] The gamma dose rate is detected within a predetermined time using the gamma dose rate measurement module, and the single measurement time of the gamma energy spectrum measurement module is confirmed based on the gamma dose rate.

[0024] The old roof is divided into several grid regions.

[0025] The gamma spectrum measurement module is used to detect several grid regions according to the single measurement time of the gamma spectrum measurement module, so as to obtain the gamma spectrum data of each grid region.

[0026] The gamma-ray spectrum data of each grid region were analyzed to obtain information on the radionuclide composition, activity, and total activity of each grid region.

[0027] Furthermore, the process of dividing the old roof into a grid to obtain several grid regions includes:

[0028] Connect the top of the old top cover to the center of the sphere of the old top cover to obtain a straight line at the top;

[0029] Connect any point on the outer side of the bottom of the flange of the old top cover to the center of the ball of the old top cover to obtain a straight flange line;

[0030] The included angle formed by the top straight line and the flange straight line is divided according to a first predetermined angle to obtain N circular rings;

[0031] The N circular rings are divided into M equal parts according to a second predetermined angle, resulting in M×N grid regions.

[0032] Furthermore, the gamma spectrum measurement module includes a gamma spectrum detector, a rotation drive, and a tilt drive. The step of detecting several grid regions using the gamma spectrum measurement module and based on the single measurement time of the gamma spectrum measurement module to obtain gamma spectrum data for each grid region includes the following scenarios:

[0033] The first method: Using 90° vertical as a reference, the tilting drive is used to tilt the γ-ray detector at the first predetermined angle, and the rotation drive is used to drive the γ-ray detector to rotate one revolution in both the forward and reverse directions at the second predetermined angle.

[0034] The tilting drive increases the first predetermined angle sequentially, and the rotation drive drives the γ-ray spectrometer to rotate one revolution in both the forward and reverse directions according to the second predetermined angle, until the tilt angle of the γ-ray spectrometer reaches the maximum tilt angle, and γ-ray spectrum data of each grid region is obtained.

[0035] The second method: Using 90° vertical as a reference, tilt the γ-ray detector according to the first predetermined angle through the tilting drive, and gradually increase the first predetermined angle.

[0036] Once the tilt angle of the γ-ray detector reaches its maximum tilt angle, the first predetermined angle is gradually reduced to align the γ-ray detector.

[0037] Once the gamma spectrum detector returns to 90°, the rotation drive is used to drive the gamma spectrum detector to rotate at a second predetermined angle until the gamma spectrum detector has rotated one full revolution, and gamma spectrum data for each grid region is obtained.

[0038] Furthermore, the nuclear power plant pressure vessel radioactivity detection equipment also includes: a source term investigation software platform, which, after analyzing the gamma spectrum data of each grid region to obtain the radionuclide composition, activity, and total activity information of each grid region, includes:

[0039] The source term investigation software platform uses continuous colors to reflect the total radioactivity information of each grid area on the inner surface of the old roof and displays it in three dimensions. At the same time, it displays the total radioactivity data of each grid area in a list.

[0040] This invention discloses a radioactive detection device, equipment, and method for pressure vessels in nuclear power plants. The device is used to conduct source term investigations on the old top cover of a pressure vessel. It includes a gamma-ray spectrum measurement module, a gamma-ray dose rate measurement module, and a loading module. Both the gamma-ray spectrum measurement module and the gamma-ray dose rate measurement module are mounted on the loading module. The loading module is equipped with a loading drive and a drive wheel. The loading drive and the drive wheel are kinetically connected to drive the drive wheel to rotate and move the loading module, allowing the gamma-ray spectrum measurement module to move to the center of the old top cover and perform detection. The device of this invention can move the gamma-ray spectrum measurement module to the center of the old top cover, ensuring that the distance between the detector center and all areas of the inner surface of the top cover is the same, thereby reducing the error in source term detection of the old top cover and improving the accuracy of source term detection. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of a radioactive detection device for a pressure vessel in a nuclear power plant.

[0043] Figure 2 for Figure 1 A partial view of A in the middle;

[0044] Figure 3 This is a schematic diagram of the gamma-ray spectrum measurement module;

[0045] Figure 4 A schematic block diagram illustrating the power supply, measurement, and control of radiation detection equipment for pressure vessels in nuclear power plants;

[0046] Figure 5 A schematic diagram of the process for detecting radioactivity in pressure vessels at nuclear power plants;

[0047] Figure 6 This is a structural schematic diagram of a pressure vessel and its top cover.

[0048] Figure 7 A schematic diagram illustrating the naming conventions for gamma-ray spectrum data;

[0049] Explanation of markings in the diagram:

[0050] 100. Gamma spectrum measurement module; 110. Gamma spectrum detector; 120. Turntable; 130. Detector support platform; 140. Support base; 150. Lifting assembly; 151. Lifting drive component; 152. Slide rail; 153. Slider; 160. Rotation drive component; 170. Tilt drive component; 180. Stop; 190. Detection component;

[0051] 200. Gamma dose rate measurement module;

[0052] 300. Loading module; 310. Loading drive unit; 320. Drive wheel; 330. Loading bracket; 340. Drive rod; 350. Cable drag chain; 360. Laser rangefinder;

[0053] 400. Electrical control cabinet;

[0054] 500. Source item survey software platform;

[0055] 600, Switch. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0058] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0059] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0060] Please see Figures 1-3 This embodiment provides a radioactive detection device for a nuclear power plant pressure vessel, used for source term investigation of the old top cover of the pressure vessel. It includes: a gamma spectrum measurement module 100, a gamma dose rate measurement module 200, and a loading module 300. The gamma spectrum measurement module 100 and the gamma dose rate measurement module 200 are both mounted on the loading module 300. The loading module 300 is provided with a loading drive component 310 and a drive wheel 320. The loading drive component 310 and the drive wheel 320 are connected to drive the drive wheel 320 to rotate and drive the loading module 300 to move, so that the gamma spectrum measurement module 100 can move to the center of the old top cover and detect the old top cover.

[0061] This embodiment can move the γ-ray spectrum measurement module 100 to the center of the old top cover, ensuring that the distance between the detector center and each region of the inner surface of the top cover is the same, thereby reducing the error of the source term detection of the old top cover and improving the accuracy of the source term detection of the old top cover.

[0062] The gamma dose rate detector in the gamma dose rate measurement module 200 can be a Geiger counter (GM) or a small ionization chamber.

[0063] In some embodiments, the loading module 300 includes: a loading bracket 330, a γ energy spectrum measurement module 100 and a γ dose rate measurement module 200, both disposed on one side of the loading bracket 330, a loading drive 310 mounted on the other side of the loading bracket 330, and a drive wheel 320 disposed on the other side of the loading bracket 330.

[0064] The loading bracket 330 not only provides the necessary mechanical support but also improves the stability and reliability of the system. The gamma spectrum measurement module 100 and the gamma dose rate measurement module 200 are integrated on the same loading bracket 330, achieving a compact design, reducing space occupation, and simplifying the operation process. The loading drive unit 310 is directly mounted on the loading bracket 330, close to the drive wheel 320, which effectively transmits driving force, enabling the loading module 300 to move smoothly.

[0065] In some embodiments, the loading module 300 further includes: a drive rod 340, a plurality of loading drive members 310 and drive wheels 320, wherein every two drive wheels 320 are connected by a drive rod 340, the drive rod 340 is rotatably disposed on the other side of the loading bracket 330, and at least one loading drive member 310 is tractively connected to the drive rod 340 to drive the drive rod 340 to rotate and drive the drive wheel 320 to rotate.

[0066] Each drive rod 340 connects to two drive wheels 320, meaning that the rotation of both wheels can be controlled simultaneously with a single drive element. This design not only improves drive synchronization but also enhances the adaptability and flexibility of the loading module 300 in complex terrain or missions. Furthermore, at least one drive element is drive-connected to the drive rod 340, ensuring efficient power transmission. This design reduces power loss and improves the overall energy efficiency of the system.

[0067] In some embodiments, the loading module 300 further includes: a drive rod 340, a loading drive member 310 and a drive wheel 320, wherein each drive wheel 320 is connected to a drive rod 340, the drive rod 340 is rotatably disposed on the other side of the loading bracket 330, and each loading drive member 310 is drively connected to a drive rod 340 to drive the drive rod 340 to rotate and drive the drive wheel 320 to rotate.

[0068] Each drive wheel 320 is connected to a drive rod 340, and each drive component is driven by a drive rod 340. This design allows each drive wheel 320 to be driven and controlled independently, thereby improving the flexibility and responsiveness of the loading module 300.

[0069] It should be noted that the drive wheel 320 can be designed like a car tire or a train wheel. It can move the loading module 300 by working with the guide rail. For example, the drive wheel 320 can be a high-density polyethylene wheel, which moves back and forth on the steel guide rail at a set speed.

[0070] In some embodiments, the nuclear power plant pressure vessel radioactivity detection device includes a power cable and a measurement and control cable. The loading module 300 also includes a cable drag chain 350, which is disposed on the loading bracket 330 to limit the range of motion of the power cable and the measurement and control cable.

[0071] The cable chain 350 can limit the range of motion of the power cable and the control cable of the radiation detection device of the pressure vessel of the nuclear power plant, prevent the power cable and the control cable from getting tangled together during the forward or backward movement of the loading module 300, and also ensure that the power cable and the control cable are not crushed by the drive wheel 320 on the loading module 300.

[0072] In some embodiments, the loading module 300 further includes a laser rangefinder 360, which is mounted on the loading bracket 330 to determine the distance between the loading module 300 and a preset reference origin.

[0073] By integrating a laser rangefinder 360, the loading module 300 can accurately measure the distance between itself and a preset reference origin. Laser ranging technology is renowned for its high precision and stability, ensuring reliable measurement results under various environmental conditions (such as changes in light and temperature fluctuations). Furthermore, accurate ranging information helps the loading module 300 quickly and accurately locate the target position, reducing the time spent on repeated adjustments due to inaccurate positioning. This not only improves operational efficiency but also reduces the workload of operators.

[0074] In some embodiments, the gamma spectrum measurement module 100 includes: a gamma spectrum detector 110, a turntable 120, a detector support platform 130, a support base 140, a lifting assembly 150, a rotary drive 160, and a tilting drive 170. The tilting drive 170 is driven to the gamma spectrum detector 110 to drive the gamma spectrum detector 110 to rotate along a horizontal axis. The tilting drive 170 is disposed on the turntable 120. The rotary drive 160 is driven to the turntable 120 to drive the turntable 120 to rotate along a vertical axis. The rotary drive 160 and the turntable 120 are disposed on the detector support platform 130. The lifting assembly 150 is driven to the detector support platform 130 to drive the detector support platform 130 to rise and fall. The lifting assembly 150 is disposed on the support base 140, and the support base 140 is disposed on the loading module 300.

[0075] When the loading module 300 stops directly below the center of the old top cover, the lifting assembly 150 is activated, causing the detector support platform 130 to rise. The rise of the detector support platform 130 causes the rotary drive 160 and the turntable 120 to rise, and the rise of the turntable 120 causes the tilt drive 170 and the gamma spectrum detector 110 to rise. The upward movement stops when the center of the gamma spectrum detector 110 is located at the center of the old top cover. This ensures that the center of the gamma spectrum detector 110 is in the same position as the center of the old top cover.

[0076] Then, when the gamma-ray spectrometer 110 is held at a fixed tilt angle, the rotary drive 160 drives the turntable 120 to rotate, and the gamma-ray spectrometer 110 completes the measurement of its upper top cover within a 360° circumferential range at that tilt angle. The detector of the gamma-ray spectrometer 110 can be a lanthanum bromide detector, a zinc cadmium telluride detector, or a high-purity germanium detector.

[0077] The tilt drive 170 is the drive mechanism for the gamma-ray spectrometer 110, driving the gamma-ray spectrometer 110 to rotate within a set tilt angle step range of 90° to 45°. The rotation drive 160 is used to drive the turntable 120 to rotate within a 360° circumferential range, providing services for the gamma-ray spectrometer 110 to complete the measurement of its upper top cover within a 360° circumferential range at a certain tilt angle.

[0078] In some embodiments, please refer to Figure 3 The lifting assembly 150 includes a lifting drive 151, a slide rail 152, and a slider 153. The lifting drive 151 and the slide rail 152 are both mounted on the support base 140. One side of the slider 153 is mounted on the detector support platform 130, and the other side of the slider 153 is slidably mounted on the slide rail 152. The driving end of the lifting drive 151 is connected to the slider 153 to drive the slider 153 to slide on the slide rail 152.

[0079] When the lifting drive 151 is driven, it will cause the slider 153 to slide upward along the slide rail 152. The upward sliding of the slider 153 will cause the detector support platform 130 to move upward.

[0080] The lifting assembly 150 consists of three main parts: a lifting drive component 151, a slide rail 152, and a slider 153. These components are tightly integrated onto the support base 140, forming a compact and efficient lifting system. This design not only reduces space occupation but also improves the overall operating efficiency of the system. Meanwhile, the sliding connection between the slide rail 152 and the slider 153 ensures the smoothness and accuracy of the lifting movement. The slide rail 152 provides stable guidance, while the slider 153 slides smoothly along the slide rail 152, reducing friction and vibration during movement, thereby improving the stability and reliability of the system.

[0081] It should be noted that the loading drive 310, lifting drive 151, rotation drive 160 and tilt drive 170 can be servo motors, stepper motors, DC motors and reluctance motors, etc.

[0082] In some embodiments, please refer to Figure 2 The γ-ray spectrum measurement module 100 also includes a stop 180 and a detector 190. The stop 180 is mounted on the tilting drive 170, and the detector 190 is mounted on the detector support platform 130.

[0083] When the stop 180 rotates to the position of the detector 190, the detector 190 detects the stop 180. Then the system receives the signal from the detector 190 and controls the turntable 120 to stop rotating.

[0084] The cooperation between the stop block 180 and the detection element 190 enables precise positioning control of the rotation of the turntable 120.

[0085] In some embodiments, the system further includes an electrical control cabinet 400, which is mounted on the loading module 300 and is electrically connected to the gamma spectrum measurement module 100, the gamma dose rate measurement module 200, and the loading module 300, respectively.

[0086] The electrical control cabinet 400 serves as the power supply and control unit for the radiation detection device on the pressure vessel of a nuclear power plant. It not only provides a stable and reliable power supply to each module but also achieves centralized management and operation of the entire system through integrated control functions. This design greatly simplifies the system structure and improves work efficiency.

[0087] Specifically, the electrical control cabinet 400 consists of three power supplies and four control units. The three power supplies are power supply unit 401, power supply unit 402, and power supply unit 403. Power supply unit 401 powers the lifting drive 151, the rotation drive 160, and the tilting drive 170. Power supply unit 402 powers the four loading drive units 310. Power supply unit 403 powers the laser rangefinder 360, the gamma dose rate measurement module 200, and the gamma spectrum detector 110.

[0088] This embodiment also provides a radioactive detection device for a nuclear power plant pressure vessel, including: the radioactive detection device for a nuclear power plant pressure vessel described in the above embodiment.

[0089] In some embodiments, please refer to Figure 4 It also includes: a source term investigation software platform 500 and a switch 600. The source term investigation software platform 500 is connected to the γ energy spectrum measurement module 100, the γ dose rate measurement module 200 and the loading module 300 via the switch 600.

[0090] The source project survey software platform 500 connects to each measurement module and loading module 300 via a switch 600, enabling operators to monitor the system's operational status and data remotely in real time. This remote monitoring capability enhances the system's flexibility and operability. Furthermore, the signal connection via the switch 600 provides greater scalability and compatibility. This means that when adding new measurement modules or functions, only a simple connection configuration via the switch 600 is required, without the need for large-scale modifications to the entire system.

[0091] Specifically, control units 404, 405, 406, and 407 within the electrical control cabinet 400 are operated by a preset control program of the source investigation software platform 500. The control program module 501 of the source investigation software platform 500 remotely controls control unit 404 via a switch 600 and a measurement and control cable, while the control program module 505 of the source investigation software platform 500 remotely controls control units 405, 406, and 407 via the switch 600 and the measurement and control cable. The control unit 404 of the electrical control cabinet 400 locally controls four loading drive components 310 and drive rods 340 to work together, driving four drive wheels 320 to move back and forth on the steel guide rail at a set speed. Control unit 405 locally controls lifting drive 151 to drive slider 153 to rise along slide rail 152, thereby driving turntable 120, rotation drive 160, tilt drive 170, gamma spectrum detector 110, and stop block 180 supported by detector support platform 130 to rise along slide rail 152 until the center of gamma spectrum detector 110 is located at the center of the old top cover and stops sliding upward. This ensures that the center of gamma spectrum detector 110 is in the same position as the center of the old top cover. Control unit 406 locally controls rotation drive 160 to drive turntable 120 to rotate, ensuring that gamma spectrum detector 110 completes the measurement and investigation of radiation source items of the old top cover above it within a 360° circumferential range at a certain set tilt angle. Control unit 407 locally controls tilt drive 170 and drives gamma spectrum detector 110 to rotate within a range of 90° to 45° with a set tilt angle step.

[0092] like Figure 4 As shown, the source term investigation software platform 500 is installed on the workstation. The data receiving and control modules 502, 503, and 504 of the source term investigation software platform 500 communicate with the laser rangefinder 360, the gamma dose rate measurement module 200, and the gamma spectrum detector 110 via a switch 600 and a measurement and control cable, respectively. The data receiving and control modules 502, 503, and 504 receive the reference distance data measured by the laser rangefinder 360, the gamma dose rate data measured by the gamma dose rate measurement module 200, and the gamma spectrum data measured by the gamma spectrum detector 110, respectively. The gamma spectrum analysis module 506 of the source term investigation software platform 500 analyzes the gamma spectrum measured by the gamma spectrum detector 110 to obtain the nuclide types, activities, and total activities in each gamma spectrum; the data and alarm display module 507 receives and displays the measurement data and alarm signals from each component.

[0093] It should be noted that the control program module 501, control program module 505, data receiving and control module 502, data receiving and control module 503, data receiving and control module 504, gamma spectrum analysis module 506, and data and alarm display module 507 of the source term investigation software platform 500 can be replaced by a distributed control system (DCS) to realize the calculation, communication, display, and control functions of the above modules.

[0094] Please see Figure 5 This embodiment also provides a method for detecting radioactivity in nuclear power plant pressure vessels, which is applied to the radioactivity detection equipment for nuclear power plant pressure vessels described in the above embodiment, and includes:

[0095] S101: Set the reference origin and drive the loading module to move directly below the old top cover;

[0096] In this embodiment, before step S101, the pipe seat on the old top cover needs to be cut off by flame cutting, and then the old top cover needs to be placed on the old top cover support frame.

[0097] For details, please refer to Figure 6 The pressure vessel top cover consists of a top cover head and a top cover flange. The pressure vessel top cover head is welded with an exhaust pipe seat, a control rod drive mechanism pipe seat, and core measurement and water level measurement pipe seats. These pipe seats are all welded parts.

[0098] Before conducting the source item investigation of the old roof, the pipe seat on the old roof head can be removed by flame cutting. After removing the pipe seat, only the roof flange and the roof head remain.

[0099] Next, three guide rails are fixed side-by-side directly below the old top cover support frame, with the middle guide rail positioned directly below the center of the old top cover support frame. The old top cover, with the connector removed, is then placed on the old top cover support frame. A crane is used to place the nuclear power plant pressure vessel radioactivity detection device onto two adjacent guide rails, and four drive wheels 320 drive the device along these rails. The drive wheel 320 on the same side as the gamma-ray detector 110 is placed on the middle guide rail, and the drive wheel 320 on the other side is placed on the adjacent guide rail. This ensures that the gamma-ray detector 110 remains aligned with the central axis of the old top cover support frame.

[0100] When the radioactivity detection device for the pressure vessel of the nuclear power plant is placed on the guide rail, the device is then powered on, and communication and control tests of each component are carried out.

[0101] Specifically, before conducting the source term investigation of the old roof, complete all preparatory work. Check that the power cable terminations between each component and the power supply units 401, 402, and 403 of the electrical control cabinet 400 are intact, and that the measurement and control cables between the switch 600 and each device and control module are intact. Confirm that the power cable terminations between the electrical control cabinet 400 and the power plant distribution panel are intact, and that the distribution panel supplies power to the electrical control cabinet 400. Turn on the circuit breakers of power supply units 401, 402, and 403 on the electrical control cabinet 400 to supply power to each device, and confirm that each device is powered normally. On the workstation, confirm that the control unit 404 can be remotely controlled through the control program module 501, and that control units 405, 406, and 407 can be remotely controlled through the control program module 505 of the source term investigation software platform 500. Next, on the workstation, the laser rangefinder 360, the gamma dose rate measurement module 200, and the gamma energy spectrum detector 110 are turned on and their measurement data are received through the data receiving and control modules 502, 503, and 504 of the source term investigation software platform 500. Then, it is confirmed that the data receiving and control modules 502, 503, and 504 can remotely control the laser rangefinder 360, the gamma dose rate measurement module 200, and the gamma energy spectrum detector 110 to start and stop and receive their measurement data.

[0102] After confirming that the communication and control of each component are in good working order, proceed to step S101.

[0103] Specifically, on the workstation, the laser rangefinder 360 is started via the data receiving and control module 502 of the source survey software platform 500, through the switch 600 and the measurement and control cable, and a reference origin is set for the laser rangefinder 360. The distance D between the projection of the reference origin on the ground and the projection of the center of the old roof sphere on the ground is input into the data receiving and control module 502.

[0104] On the workstation, the control program module 501 of the source investigation software platform 500 controls the control unit 404. The control unit 404 locally activates the four loading drive units 310 and controls the four loading drive units 310 and their corresponding drive rods 340 to work together to drive the four drive wheels 320 to move on the steel guide rail at a set speed of 0.1 m / s, thereby causing the loading module 300 to move towards the center of the old top cover.

[0105] Next, the laser rangefinder 360 transmits the distance between the center of the gamma-ray spectrometer 110 and the reference origin to the data receiving and control module 502 via the control cable and switch 600. When the distance between the center of the gamma-ray spectrometer 110 installed on the loading module 300 and the reference origin reaches D (i.e., the distance between the projection of the reference origin on the ground and the projection of the center of the old top cover on the ground), the data receiving and control module 502 automatically sends an alarm signal to the control program module 501. The control program module 501 then sends an automatic stop signal to the control unit 404 via the control cable and switch 600. The control unit 404 locally controls the four loading drive units 310 to stop operating. After the four loading drive units 310 have completely stopped, the control unit 404 sends an alarm signal to the control program module 501 via the control cable and switch 600, prompting the control program module 501 to stop receiving alarm signals from the data receiving and control module 502.

[0106] Then, the measurement data from the laser rangefinder 360, the alarm signals from the data receiving and control module 502, and the alarm signals sent by the control program module 501 are all transmitted to the data and alarm display module 507 of the source investigation software platform 500. The data and alarm display module 507 displays the above data and alarm signals in real time.

[0107] After the above steps are completed, the loading module 300 is now below the old top cover, and the gamma spectrum detector 110 is located directly below the center of the old top cover.

[0108] S102: The γ dose rate is detected by the γ dose rate measurement module within a predetermined time, and the single measurement time of the γ energy spectrum measurement module is confirmed based on the γ dose rate;

[0109] Specifically, after the data and alarm display module 507 displays alarm signals indicating that the four loading drive components 310 have completely stopped, the control program module 505 sets the upward sliding distance M of the slider 153 to the control unit 405. The control unit 405, remotely controlled by the control program module 505, locally controls the lifting drive component 151 to drive the slider 153 upward along the slide rail 152. The slider 153 drives the detector support platform 130, turntable 120, rotation drive component 160, tilt drive component 170, gamma spectrum detector 110, and stop block 180 to rise along the slide rail 152. When the slider 153 slides upward a distance of M, the control unit 405 locally controls the slider 153 to stop sliding and sends an alarm signal indicating that the slider 153 has reached its position via the control cable and switch 600 to the control program module 505 and the data and alarm display module 507. At this time, the center of the gamma spectrum detector 110 is located at the center of the sphere of the old top cover.

[0110] After the data and alarm display module 507 displays an alarm signal indicating that the slider 153 has slid upwards into place, the data receiving and control module 503 activates the gamma dose rate measurement module 200 to perform gamma dose rate measurement directly below the old top cover. The measurement data is fed back to the data receiving and control module 503 and the data and alarm display module 507 in real time via the measurement and control cable and switch 600. The measurement time is 1 minute. The data receiving and control module 503 calculates the average value of the gamma dose rate measurement data received from the gamma dose rate measurement module 200 within 1 minute. Based on the following principles, the data receiving and control module 503 outputs the individual measurement time of the gamma energy spectrum detector 110 and displays it in the data and alarm display module 507. Subsequently, the data receiving and control module 503 shuts down the gamma dose rate measurement module 200, stopping the gamma dose rate measurement.

[0111] The principle is: when the γ dose rate Measurement time: 2 minutes;

[0112] when Measurement time: 1 minute;

[0113] When γ dose rate Measurement time: 30 seconds.

[0114] S103: Divide the old top cover into a grid to obtain several grid areas;

[0115] Specifically, the old roof is divided into several grid areas, including:

[0116] Connect the top of the old top cover to the center of the ball on the old top cover to obtain a straight line at the top;

[0117] Connect any point on the outer side of the bottom of the old top cover flange to the center of the ball of the old top cover to obtain a straight flange line;

[0118] Divide the angle formed by the top straight line and the flange straight line into N rings according to a first predetermined angle;

[0119] Divide the N annular rings into M equal parts according to the second predetermined angle, resulting in M×N grid regions.

[0120] The number of meshes (N×M) can be flexibly controlled by adjusting the first and second predetermined angles. This flexibility allows the method to adapt to old roofs of different sizes and complexities, meeting diverse analysis or renovation needs.

[0121] For example, the old roof can be considered as part of a sphere with a diameter of approximately 4.7m. Connecting the top of the old roof to its center creates a straight line at the top. Connecting any point on the outer side of the flange bottom to the center of the sphere creates a straight line at the flange. The angle between the top and flange lines is approximately 45°. When conducting a source term investigation on the inner surface of the roof, the approximately 45° angle between the top and flange lines is divided into 6 grid regions (i.e., 6 annular sections), with each grid region having an angle of 7.5° (equivalent to dividing the old roof from the top to the flange surface into 6 parts in the planar direction). Then, each annular section is divided into 50 equal parts in a 360° range (equivalent to dividing each annular section vertically into 50 parts, with a second predetermined angle of 7.2°), thus dividing the old roof into 300 grid regions (6 * 50 = 300). The source term survey of the inner surface of the old roof involves measuring each of the 300 grid areas on the inner surface of the old roof to obtain the source term of the old roof's inner surface for each grid area. Based on the source term survey results, information on the radionuclide composition, activity, and total activity of each grid area on the inner surface of the old roof can be obtained, providing information and guidance for the decontamination of the inner surface of the old roof.

[0122] S104: The gamma spectrum measurement module is used to detect several grid regions according to the single measurement time of the gamma spectrum measurement module to obtain gamma spectrum data for each grid region;

[0123] Specifically, the γ-ray spectrum measurement module 100 is used to detect several grid regions based on the single measurement time of the γ-ray spectrum measurement module 100, and the γ-ray spectrum data of each grid region is obtained, including the following cases:

[0124] The first method: With 90° vertical as the reference, the γ energy spectrum detector 110 is tilted at a first predetermined angle by the tilting drive 170, and the γ energy spectrum detector 110 is driven to rotate one revolution in the forward and reverse directions by the rotation drive 160 at a second predetermined angle.

[0125] The tilting drive 170 gradually increases the first predetermined angle, and the rotation drive 160 drives the γ energy spectrum detector 110 to rotate one revolution in both the forward and reverse directions according to the second predetermined angle until the tilt angle of the γ energy spectrum detector 110 reaches the maximum tilt angle, and obtains the γ energy spectrum data of each grid region.

[0126] The second method: Using 90° vertical as a reference, tilt the γ-ray detector 110 at a first predetermined angle by tilting the tilting drive 170, and gradually increase the first predetermined angle.

[0127] Once the tilt angle of the gamma spectrum detector 110 reaches its maximum tilt angle, the first predetermined angle is gradually reduced to return the gamma spectrum detector 110 to its normal position.

[0128] Once the gamma spectrum detector 110 returns to 90°, the rotation drive 160 drives the gamma spectrum detector 110 to rotate at a second predetermined angle until the gamma spectrum detector 110 rotates one full revolution and obtains the gamma spectrum data for each grid region.

[0129] By combining the tilting drive 170 and the rotation drive 160, the gamma-ray spectrometer 110 can scan the grid area at multiple angles and directions. This omnidirectional scanning method ensures that each grid area is fully covered, thereby improving the comprehensiveness and accuracy of the measurement.

[0130] The first scenario will be explained in detail below:

[0131] The control program module 505 sets the tilt angle of the gamma-ray detector 110 driven by the tilting drive 170 to the control unit 407 for a single tilt. Based on the single measurement time T1 of the gamma-ray detector 110 displayed by the data and alarm display module 507 (i.e., the sum of the time it takes for the turntable 120 to complete a 7.2° rotation and the single measurement time of the gamma-ray detector 110), the control program module 505 sets the rotation drive 160 to drive the turntable 120 to complete a 7.2° rotation time T2 to the control unit 406 for a 7.2° rotation. The data receiving and control module 504 sets the single measurement time T3 of the gamma-ray detector 110.

[0132] In this embodiment, the tilting drive 170 drives the gamma-ray spectrometer 110 to tilt at a single angle of 7.5°. When the rotation drive 160 drives the turntable 120 to complete a 7.2° rotation in 2 minutes and a 360° rotation in 100 minutes, the gamma-ray spectrometer 110's single measurement time is 2 minutes. When the rotation drive 160 drives the turntable 120 to complete a 7.2° rotation in 1 minute and a 360° rotation in 50 minutes, the gamma-ray spectrometer 110's single measurement time is 1 minute. When the rotation drive 160 drives the turntable 120 to complete a 7.2° rotation in 30 seconds and a 360° rotation in 25 minutes, the gamma-ray spectrometer 110's single measurement time is 30 seconds.

[0133] The investigation of source terms on the inner surface of the top cover consists of the following steps:

[0134] Step a: The tilting actuator 170 drives the γ-ray spectrometer 110 to tilt 7.5° in a single operation.

[0135] After the above parameters are set by the control program module 505 on the source term investigation software platform 500, the control program module 505 automatically controls the control unit 407, and the control unit 407 locally controls the tilt drive 170 to drive the γ energy spectrum detector 110 to tilt 7.5° away from the support base 140.

[0136] After completing a 7.5° tilt, the control unit 407 sends a signal to the control program module 505 via the measurement and control cable and the switch 600, indicating that the gamma spectrum detector 110 has completed a 7.5° tilt, and transmits the number of tilts and the current tilt angle of the gamma spectrum detector 110. The control program module 505 transmits the number of tilts of the gamma spectrum detector 110 to the data receiving and control module 504, and transmits the tilt angle of the gamma spectrum detector 110 to the data and alarm display module 507, displaying the tilt angle of the gamma spectrum detector 110.

[0137] Through six tilting operations, the tilting drive 170 drives the γ-ray spectrometer 110 to tilt sequentially from 90° to 82.5°, 75°, 67.5°, 60°, 52.5° and 45°.

[0138] Step b: Rotary drive component 160 drives turntable 120 to rotate and measures the inner surface of the old top cover:

[0139] When the control program module 505 receives the signal from the control unit 407 that the gamma spectrum detector 110 has completed a 7.5° tilt, it automatically sends a signal to the data receiving and control module 504. The data receiving and control module 504 then starts the gamma spectrum detector 110 to begin measurement. At the same time, the control program module 505 automatically controls the control unit 406 to locally control the rotary drive 160 to drive the turntable 120 to rotate counterclockwise with the stop block 180 as the starting point.

[0140] When the rotary drive 160 drives the turntable 120 to complete one 360° rotation counterclockwise, the stop block 180 prevents the rotary drive 160 from continuing to drive the turntable 120 to rotate counterclockwise. The control unit 406 locally controls the rotary drive 160 to drive the turntable 120 to complete one 360° rotation clockwise and return to the starting point. At this time, the control unit 406 sends a signal to the control program module 505 via the measurement and control cable and the switch 600 that the turntable 120 has completed one 360° rotation counterclockwise and clockwise. The control program module 505 automatically controls the control unit 407, which locally controls the tilt drive 170 to drive the gamma spectrum detector 110 to tilt 7.5° away from the support base 140. Then, the gamma spectrum detector 110 is tilted 7.5° in a single operation according to step a.

[0141] When the data receiving and control module 504 receives a tilt count of 6 from the gamma spectrum detector 110, it automatically sends a signal to the control program module 505 and automatically stops receiving signals from the control unit 406. After the turntable 120 completes one full 360° rotation counterclockwise and one full 360° clockwise, the data receiving and control module 504 automatically shuts down the gamma spectrum detector 110, completing the source term measurement of the inner surface of the old top cover.

[0142] Similarly, the second scenario is similar to the first, so we will not elaborate further on it.

[0143] When the turntable 120 rotates 7.2°, the gamma spectrum detector 110 completes one measurement and stores the gamma spectrum data in the data receiving and control module 504 via the measurement and control cable and the switch 600 in the format of tilt number X + rotation mode Y + rotation number ZZ (rotation mode is divided into clockwise rotation and counterclockwise rotation, where counterclockwise rotation is represented by 1 and clockwise rotation by 2). Figure 7 (As shown).

[0144] For example, after the gamma spectrum detector 110 tilts for the second time, the turntable 120 rotates counterclockwise. The file name of the gamma spectrum data measured in the 20th grid region on the inner surface of the top cover is "2120". The turntable 120 measures the same grid region both clockwise and counterclockwise. For example, gamma spectrum data file names "2101" and "2250" measure the same grid region on the inner surface of the top cover, and gamma spectrum data file names "2110" and "2241" measure the same grid region on the inner surface of the top cover.

[0145] This data storage method not only simplifies data recording but also improves data readability and accuracy.

[0146] After detecting several grid areas and obtaining the gamma spectrum data for each grid area, it is necessary to return each component to its origin and remove the nuclear power plant pressure vessel radioactivity detection device from under the old top cover.

[0147] Specifically, after completing the source term measurement work on the inner surface of the old top cover, the control program module 505 remotely controls the control unit 407. The control unit 407 locally controls the tilting drive 170 to drive the gamma spectrum detector 110 from 45° back to 90°. The control unit 407 sends a signal to the control program module 505 via the measurement and control cable and switch 600 indicating that the gamma spectrum detector 110 has returned to 90°. Subsequently, the control program module 505 remotely controls the control unit 405, which locally controls the lifting drive 151 to drive the slider 153 down along the slide rail 152 until the slider 153 reaches the origin position. The control unit 405 sends a signal to the control program module 505 via the measurement and control cable and switch 600 indicating that the slider 153 has reached the origin position.

[0148] Then, the data receiving and control module 502 inputs a distance of 0 between the projection of the reference origin onto the ground and the projection of the old top cover's sphere center onto the ground. Next, on the workstation, the control program module 501 of the source investigation software platform 500 controls the control unit 404. Then, the control unit 404 locally activates the four loading drive components 310, controlling the four loading drive components 310 and the drive rod 340 to work together, thereby driving the four drive wheels 320 to move on the steel guide rail at a set speed of 0.1 m / s, and thus driving the nuclear power plant pressure vessel radioactivity detection device to move in the direction of return along the original path.

[0149] The laser rangefinder 360 transmits the distance between the nuclear power plant pressure vessel radioactivity detection device and the reference origin to the data receiving and control module 502 via the measurement and control cable and switch 600. When the distance data between the nuclear power plant pressure vessel radioactivity detection device and the reference origin is 0 (indicating that the four loading drive components 310 and the drive rod 340 work together to drive the nuclear power plant pressure vessel radioactivity detection device back to the starting origin), the data receiving and control module 502 automatically sends an alarm signal to the control program module 501. The control program module 501 sends an automatic stop signal to the control unit 404 via the measurement and control cable and switch 600. The control unit 404 then locally controls the four loading drive components 310 to stop moving.

[0150] Next, the electrical control cabinet 400 shuts down the circuit breakers of power supply units 401, 402 and 403 to disconnect the power to each device, and confirms that all devices are powered off.

[0151] S105: Analyze the γ-ray spectrum data of each grid region to obtain the radionuclide composition, activity, and total activity information of each grid region.

[0152] Specifically, the gamma-ray spectrum data for each grid region is analyzed to obtain information on the radionuclide composition, activity, and total activity for each grid region, including:

[0153] The source term survey software platform 500 uses continuous colors to reflect the total radioactivity information of each grid area on the inner surface of the old roof and displays it in three dimensions. At the same time, it displays the total radioactivity data of each grid area in a list.

[0154] Using continuous colors to reflect the total radioactivity information of each grid area greatly enhances the data visualization effect. Variations in color intensity or hue can intuitively represent the level of radioactivity, facilitating the rapid identification of high-risk areas.

[0155] More specifically, on the workstation, the gamma spectrum analysis module 506 of the source term investigation software platform 500 analyzes each gamma spectrum data stored in the data receiving and control module 504 to obtain information on the radionuclide composition, activity, and total activity of each grid region on the inner surface of the old top cover.

[0156] The gamma-ray spectrometer 110 measures each grid region on the inner surface of the old top cover once when the turntable 120 rotates counterclockwise and clockwise. The average of the two measurements is used as the data of the radioactivity and total activity of that grid region on the inner surface of the old top cover. This reduces the measurement error of the radioactivity and total activity of each grid region on the inner surface of the old top cover and improves the accuracy of the measurement.

[0157] The data and alarm display module 507 divides the top cover into 6 zones from the top of the top cover to the outer side of the flange face (90° to 45°), with each zone having an inclination angle of 7.5°. The 6 zones are divided into 50 parts of 360°, each part being 7.2°. The entire inner surface of the top cover has a grid area of ​​300 grid areas.

[0158] After the gamma-ray spectrum analysis module 506 completes the analysis of the radioactivity and total activity measurements in each grid area of ​​the old roof, it transmits the analysis results to the data and alarm display module 507. The data and alarm display module 507 uses continuous colors to reflect the total radioactivity information of each grid area on the inner surface of the old roof in a three-dimensional format, and simultaneously displays the total radioactivity data of each area in a list format. This data is used to guide the decontamination of the inner surface of the old roof.

[0159] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

[0160] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusivity.

[0161] The term "comprises" implies that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A radioactive detection device for a nuclear power plant pressure vessel, used for source term investigation of the old top cover of the pressure vessel, characterized in that, include: The system includes a gamma spectrum measurement module, a gamma dose rate measurement module, and a loading module. Both the gamma spectrum measurement module and the gamma dose rate measurement module are mounted on the loading module. The loading module is equipped with a loading drive and a drive wheel. The loading drive and the drive wheel are connected by a transmission to drive the drive wheel to rotate and move the loading module, so that the gamma spectrum measurement module can move to the center of the old top cover and detect the old top cover. The gamma spectrum measurement module includes: a gamma spectrum detector, a turntable, a detector support platform, a support base, a lifting assembly, a rotary drive, and a tilting drive. The tilting drive is driven by the gamma spectrum detector to drive the gamma spectrum detector to rotate along a horizontal axis. The tilting drive is mounted on the turntable. The rotary drive is driven by the turntable to drive the turntable to rotate along a vertical axis. The rotary drive and the turntable are mounted on the detector support platform. The lifting assembly is driven by the detector support platform to drive the detector support platform to lift and lower. The lifting assembly is mounted on the support base, and the support base is mounted on the loading module. When the loading module stops directly below the center of the old top cover, the lifting assembly starts and drives the detector support platform to rise. The rise of the detector support platform drives the rotary drive and turntable to rise. The rise of the turntable drives the tilt drive and gamma spectrum detector to rise. When the center of the gamma spectrum detector is located at the center of the old top cover, it stops moving upward. When the gamma spectrum detector is held at a certain fixed tilt angle, the rotary drive drives the turntable to rotate. The gamma spectrum detector completes the measurement of the old top cover above it within a 360° circumference range at this tilt angle.

2. The nuclear power plant pressure vessel radioactivity detection device according to claim 1, characterized in that, The loading module includes a loading bracket, the gamma spectrum measurement module and the gamma dose rate measurement module are both disposed on one side of the loading bracket, the loading drive is installed on the other side of the loading bracket, and the drive wheel is disposed on the other side of the loading bracket.

3. The nuclear power plant pressure vessel radioactivity detection device according to claim 2, characterized in that, The loading module further includes a drive rod, and multiple loading drive components and drive wheels are provided, wherein every two drive wheels are connected by a drive rod, the drive rod is rotatably disposed on the other side of the loading bracket, and at least one loading drive component is pulsatorically connected to the drive rod to drive the drive rod to rotate and drive the drive wheel to rotate.

4. The nuclear power plant pressure vessel radioactivity detection device according to claim 2, wherein the nuclear power plant pressure vessel radioactivity detection device comprises a power cable and a measurement and control cable, characterized in that, The loading module further includes a cable drag chain, which is mounted on the loading bracket to limit the range of motion of the power cable and the control cable.

5. The nuclear power plant pressure vessel radioactivity detection device according to claim 2, characterized in that, The loading module further includes a laser rangefinder, which is mounted on the loading bracket to determine the distance between the loading module and a preset reference origin.

6. The radioactivity detection device for nuclear power plant pressure vessels according to claim 1, characterized in that, The lifting assembly includes a lifting drive, a slide rail, and a slider. The lifting drive and the slide rail are both mounted on the support base. One side of the slider is mounted on the detector support platform, and the other side of the slider is slidably mounted on the slide rail. The driving end of the lifting drive is connected to the slider to drive the slider to slide on the slide rail.

7. The nuclear power plant pressure vessel radioactivity detection device according to claim 1, characterized in that, The gamma spectrum measurement module further includes a stop block and a detection element, wherein the stop block is disposed on the tilting drive element and the detection element is disposed on the detector support platform.

8. The nuclear power plant pressure vessel radioactivity detection device according to claim 1, characterized in that, Also includes: An electrical control cabinet is mounted on the loading module and is electrically connected to the gamma spectrum measurement module, the gamma dose rate measurement module, and the loading module.

9. A radioactivity detection device for pressure vessels in nuclear power plants, characterized in that, include: The radioactivity detection device for nuclear power plant pressure vessels as described in any one of claims 1-8.

10. The nuclear power plant pressure vessel radioactivity detection equipment according to claim 9, characterized in that, Also includes: The source term investigation software platform and the switch are connected via the switch to the gamma spectrum measurement module, the gamma dose rate measurement module and the loading module.

11. A method for detecting radioactivity in a nuclear power plant pressure vessel, applied to the radioactivity detection equipment for a nuclear power plant pressure vessel as described in any one of claims 9-10, characterized in that, include: Set a reference origin and drive the loading module to move directly below the old top cover; The gamma dose rate is detected within a predetermined time using the gamma dose rate measurement module, and the single measurement time of the gamma energy spectrum measurement module is confirmed based on the gamma dose rate. The old roof is divided into several grid regions. The gamma spectrum measurement module is used to detect several grid regions according to the single measurement time of the gamma spectrum measurement module, so as to obtain the gamma spectrum data of each grid region. The gamma-ray spectrum data of each grid region were analyzed to obtain information on the radionuclide composition, activity, and total activity of each grid region.

12. The method for detecting radioactivity in a nuclear power plant pressure vessel according to claim 11, characterized in that, The process of dividing the old roof into grids to obtain several grid regions includes: Connect the top of the old top cover to the center of the sphere of the old top cover to obtain a straight line at the top; Connect any point on the outer side of the bottom of the flange of the old top cover to the center of the ball of the old top cover to obtain a straight flange line; The included angle formed by the top straight line and the flange straight line is divided according to a first predetermined angle to obtain N circular rings; The N circular rings are divided into M equal parts according to a second predetermined angle, resulting in M×N grid regions.

13. The method for detecting radioactivity in a nuclear power plant pressure vessel according to claim 12, wherein the gamma-ray spectrum measurement module comprises: A gamma-ray spectrometer, a rotation drive, and a tilt drive, characterized in that the step of detecting several grid regions through the gamma-ray spectrometer measurement module and obtaining gamma-ray spectrometer data for each grid region according to the single measurement time of the gamma-ray spectrometer measurement module includes the following scenarios: The first method: Using 90° vertical as a reference, the tilting drive is used to tilt the γ-ray detector at the first predetermined angle, and the rotation drive is used to drive the γ-ray detector to rotate one revolution in both the forward and reverse directions at the second predetermined angle. The tilting drive increases the first predetermined angle sequentially, and the rotation drive drives the γ-ray spectrometer to rotate one revolution in both the forward and reverse directions according to the second predetermined angle, until the tilt angle of the γ-ray spectrometer reaches the maximum tilt angle, and γ-ray spectrum data of each grid region is obtained. The second method: Using 90° vertical as a reference, tilt the γ-ray detector according to the first predetermined angle through the tilting drive, and gradually increase the first predetermined angle. Once the tilt angle of the γ-ray detector reaches its maximum tilt angle, the first predetermined angle is gradually reduced to align the γ-ray detector. Once the gamma spectrum detector returns to 90°, the rotation drive is used to drive the gamma spectrum detector to rotate at a second predetermined angle until the gamma spectrum detector has rotated one full revolution, and gamma spectrum data for each grid region is obtained.

14. The method for detecting radioactivity in a nuclear power plant pressure vessel according to claim 11, wherein the radioactivity detection equipment for the nuclear power plant pressure vessel further comprises: The source term investigation software platform is characterized in that, after analyzing the γ-ray spectrum data of each grid region to obtain the radionuclide composition, activity, and total activity information of each grid region, it includes: The source term investigation software platform uses continuous colors to reflect the total radioactivity information of each grid area on the inner surface of the old roof and displays it in three dimensions. At the same time, it displays the total radioactivity data of each grid area in a list.

Images