Device, equipment and method for radioactivity detection of pressure vessel of nuclear power plant

Abstract

The invention discloses a nuclear power plant pressure vessel radioactivity detection device, equipment and method, the device is used for carrying out source item investigation on an old top cover of a pressure vessel, the device 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 both arranged on the loading module, and the loading module is used for loading the gamma energy spectrum measurement module and the gamma dose rate measurement module. The loading module is provided with a loading driving part and a driving wheel, and the loading driving part 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 move to the sphere center of the old top cover and detect the old top cover. According to the device, the gamma energy spectrum measurement module can be moved to the sphere center of the old top cover, it can be ensured that the distances between the center of the detector and all areas of the inner surface of the top cover are the same, and therefore the error of source item detection of the old top cover can be reduced, and the accuracy of source item detection of the old top cover is improved.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power technology, and in particular to a radioactivity detection device, equipment and method for a pressure vessel of a nuclear power plant. Background Art

[0002] In the field of nuclear power generation, the pressure vessel is a key component of the nuclear reactor, and the integrity and safety of its cover are directly related to the stable operation of the nuclear power plant. As the operation life of the nuclear power plant increases, the old cover will be aged and corroded due to long-term exposure to high temperature, high pressure and radiation environment, and needs to be replaced when necessary. At present, only Daya Bay Nuclear Power Plant and Qinshan Nuclear Power Plant have successfully completed the replacement of the old cover of the pressure vessel in China.

[0003] In the old top cover replacement project of Daya Bay Nuclear Power Plant, technicians used a method based on theoretical calculation to evaluate the radioactive source term of the old top cover. This method is mainly based on the neutron flux distribution of the core, and predicts the types of radionuclides and their total radioactivity levels produced after the old top cover is activated by neutrons through simulation calculations. At the same time, attempts were made to estimate the types and total activity of radionuclides deposited on the inner surface of the old top cover by activated corrosion products in the primary coolant. However, this method has significant defects:

[0004] Due to the complex changes in the core neutron flux and the limitations of the theoretical calculation method, there is a large deviation between the old cap activation source term obtained by theoretical calculation and the actual source term, which cannot accurately reflect the actual activation situation of each area of ​​the cap.

[0005] The deposition process of corrosion products in the primary coolant on the inner surface of the old top cover is extremely complex and the deposition distribution is uneven. Therefore, it is difficult to determine the specific location of the corrosion products on the inner surface of the top cover and their radioactivity level based on theoretical estimation alone, and thus it is impossible 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 technical solution aims to directly measure and evaluate the radioactive source term of the old roof by constructing a special investigation device. The design of the device covers the structural composition, working principle and investigation method, providing a new idea for the source term investigation of the old roof.

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

[0008] Since the distances between the center of the detector and the inner surface of the top cover are different, the measurement results will be affected by the theoretical correction of the physical model, thus introducing certain measurement errors. This error may affect the accuracy of the source term evaluation and thus have an adverse impact on the subsequent decontamination treatment decision. Summary of the invention

[0009] The object of the present invention is to provide a radioactive detection device, equipment and method for a nuclear power plant pressure vessel, aiming to solve the problems of large error and low accuracy in the source term detection of the existing old top cover.

[0010] An embodiment of the present invention provides a radioactive detection device for a nuclear power plant pressure vessel, which is used for conducting a source term investigation on the old top cover of the pressure vessel, and includes: a gamma energy spectrum measurement module, a gamma dose rate measurement module and a loading module. Both the gamma energy spectrum measurement module and the gamma dose rate measurement module are arranged on the loading module. A loading driving member and a driving wheel are arranged on the loading module, and the loading driving member 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 center of the sphere of the old top cover and detect the old top cover.

[0011] Further, the loading module includes: a loading bracket. Both the gamma energy spectrum measurement module and the gamma dose rate measurement module are arranged on one side of the loading bracket. The loading driving member is installed on the other side of the loading bracket, and the driving wheel is arranged on the other side of the loading bracket.

[0012] Further, the loading module further includes: a driving rod. There are multiple loading driving members and driving wheels. Among them, every two driving wheels are connected by one driving rod. The driving rod is rotatably arranged on the other side of the loading bracket, and at least one loading driving member is in transmission connection with the driving rod to drive the driving rod to rotate and drive the driving wheel to rotate.

[0013] Further, the radioactive detection device for a nuclear power plant pressure vessel includes a power cable and a measurement and control cable. The loading module further includes: a cable drag chain. The cable drag chain is arranged on the loading bracket to define the movement range of the power cable and the measurement and control cable.

[0014] Further, the loading module further includes: a laser rangefinder. The laser rangefinder is arranged on the loading bracket to determine the distance between the loading module and a preset reference origin.

[0015] Further, the gamma spectrum measurement module includes: a gamma spectrum detector, a turntable, a detector support platform, a support base, a lifting assembly, a rotation driving member, and a tilting driving member. The tilting driving member is in transmission connection with the gamma spectrum detector to drive the gamma spectrum detector to rotate about an axis in the horizontal direction. The tilting driving member is arranged on the turntable. The rotation driving member is in transmission connection with the turntable to drive the turntable to rotate about an axis in the vertical direction. The rotation driving member and the turntable are arranged on the detector support platform. The lifting assembly is in transmission connection with the detector support platform to drive the detector support platform to move up and down. The lifting assembly is arranged on the support base, and the support base is arranged on the loading module.

[0016] Further, the lifting assembly includes: a lifting driving member, a slide rail, and a slider. The lifting driving member and the slide rail are both arranged on the support base. One side of the slider is arranged on the detector support platform, and the other side of the slider is slidably arranged on the slide rail. The driving end of the lifting driving member is in transmission connection with the slider to drive the slider to slide on the slide rail.

[0017] Further, the gamma spectrum measurement module further includes: a stop block and a detection member. The stop block is arranged on the tilting driving member, and the detection member is arranged on the detector support platform.

[0018] Further, it further includes: an electrical control cabinet. The electrical control cabinet is arranged on the loading module, and the electrical control cabinet is electrically connected to the gamma spectrum measurement module, the gamma dose rate measurement module, and the loading module respectively.

[0019] An embodiment of the present invention further provides a radioactive detection device for a nuclear power plant pressure vessel, including: the above-mentioned radioactive detection device for a nuclear power plant pressure vessel.

[0020] Further, it further includes: a source term investigation software platform and a switch. 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] An embodiment of the present invention further provides a radioactive detection method for a nuclear power plant pressure vessel, which is applied to the above-mentioned radioactive detection device for a nuclear power plant pressure vessel, and includes:

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

[0023] Detect the gamma dose rate within a predetermined time through the gamma dose rate measurement module, and confirm the single measurement time of the gamma spectrum measurement module according to the gamma dose rate;

[0024] Perform grid division on the old top cover to obtain a number of grid regions;

[0025] Detect the number of grid regions through the γ-ray spectrometry measurement module and according to the single measurement time of the γ-ray spectrometry measurement module to obtain the γ-ray spectrometry data of each grid region;

[0026] Analyze the γ-ray spectrometry data of each grid region to obtain the radionuclide composition, activity and total activity information of each grid region.

[0027] Further, the performing grid division on the old top cover to obtain a number of grid regions includes:

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

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

[0030] Divide the angle formed by the top straight line and the flange straight line according to the first predetermined angle to obtain N circular rings;

[0031] Divide the 360° of the N circular rings into M equal parts according to the second predetermined angle to obtain M×N grid regions.

[0032] Further, the γ-ray spectrometry measurement module includes: a γ-ray spectrometry detector, a rotation driving member and an inclination driving member. The detecting the number of grid regions through the γ-ray spectrometry measurement module and according to the single measurement time of the γ-ray spectrometry measurement module to obtain the γ-ray spectrometry data of each grid region includes the following situations:

[0033] The first: Based on 90° perpendicular, tilt the γ-ray spectrometry detector by the first predetermined angle through the inclination driving member, and drive the γ-ray spectrometry detector to rotate forward and backward one week respectively by the second predetermined angle through the rotation driving member;

[0034] Gradually increase the first predetermined angle through the inclination driving member, and drive the γ-ray spectrometry detector to rotate forward and backward one week respectively by the second predetermined angle through the rotation driving member until the tilt angle of the γ-ray spectrometry detector reaches the maximum tilt angle, and obtain the γ-ray spectrometry data of each grid region;

[0035] The second: Based on 90° perpendicular, tilt the γ-ray spectrometry detector by the first predetermined angle through the inclination driving member, and gradually increase the first predetermined angle;

[0036] When the inclination angle of the gamma spectrum detector reaches a maximum inclination angle, gradually reducing the first predetermined angle to correct the gamma spectrum detector;

[0037] After the gamma spectrum detector is returned to 90°, the gamma spectrum detector is driven to rotate at a second predetermined angle by the rotary drive member until the gamma spectrum detector rotates one circle, and gamma spectrum data of each grid area is obtained.

[0038] Furthermore, the nuclear power plant pressure vessel radioactivity detection equipment further includes: a source term investigation software platform, wherein the gamma spectrum data of each grid area is analyzed to obtain the radionuclide composition, activity and total activity information of each grid area, and then the following steps are performed:

[0039] The source item survey software platform reflects the total radioactivity information of each grid area on the inner surface of the old top cover with continuous colors in several grid areas on the inner surface of the old top cover and displays it in a three-dimensional form, and at the same time displays the total radioactivity data of each grid area in the form of a list.

[0040] The present invention discloses a radioactivity detection device, equipment and method for a pressure vessel of a nuclear power plant. The device is used to conduct a source term investigation on an old top cover of a pressure vessel, and includes: a gamma spectrum measurement module, a gamma dose rate measurement module and a loading module. The gamma spectrum measurement module and the gamma dose rate measurement module are both arranged on the loading module. A loading drive and a driving wheel are arranged on the loading module. The loading drive and the driving wheel are connected in a transmission manner to drive the driving wheel to rotate and drive the loading module to move, so that the gamma spectrum measurement module can be moved to the spherical center of the old top cover and detect the old top cover. The device of the present invention can move the gamma spectrum measurement module to the spherical center of the old top cover, and can ensure that the distance between the center of the detector and each area 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0042] Figure 1 This is a schematic diagram of the structure of a radioactivity detection device for a pressure vessel of a nuclear power plant;

[0043] Figure 2 for Figure 1 Partial diagram of A in the middle;

[0044] Figure 3 It is a schematic structural diagram of the γ energy spectrum measurement module;

[0045] Figure 4 It is a schematic block diagram of the power supply, measurement and control of the radioactive detection equipment for the nuclear power plant pressure vessel;

[0046] Figure 5 It is a schematic flow diagram of the radioactive detection method for the nuclear power plant pressure vessel;

[0047] Figure 6 It is a schematic structural diagram of the pressure vessel and the top cover;

[0048] Figure 7 It is a schematic diagram of the naming method of γ energy spectrum data;

[0049] Description of the markings in the figure:

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

[0051] 200. γ dose rate measurement module;

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

[0053] 400. Electrical control cabinet;

[0054] 500. Source term investigation software platform;

[0055] 600. Switch. Specific implementation manners

[0056] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope 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, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

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

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

[0060] Please refer to Figures 1 - 3 , this embodiment provides a radioactive detection device for a nuclear power plant pressure vessel, which is used for source term investigation of the old top cover of the pressure vessel, and includes: a gamma energy spectrum measurement module 100, a gamma dose rate measurement module 200, and a loading module 300. The gamma energy spectrum measurement module 100 and the gamma dose rate measurement module 200 are both arranged on the loading module 300. A loading driving member 310 and a driving wheel 320 are arranged on the loading module 300. The loading driving member 310 and the driving wheel 320 are in transmission connection to drive the driving wheel 320 to rotate and drive the loading module 300 to move, so that the gamma energy spectrum measurement module 100 can be moved to the center of the sphere of the old top cover and detect the old top cover.

[0061] This embodiment can move the gamma energy spectrum measurement module 100 to the center of the sphere of the old top cover, can ensure that the distances from the center of the detector to each area of the inner surface of the top cover are 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] Among them, 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. The gamma energy spectrum measurement module 100 and the gamma dose rate measurement module 200 are both arranged on one side of the loading bracket 330. The loading driving member 310 is installed on the other side of the loading bracket 330, and the driving wheel 320 is arranged on the other side of the loading bracket 330.

[0064] The loading bracket 330 not only provides necessary mechanical support, but also improves the stability and reliability of the system. The gamma energy spectrum measurement module 100 and the gamma dose rate measurement module 200 are integrated on the same loading bracket 330, realizing a compact design, reducing space occupation, and simplifying the operation process. The loading driving member 310 is directly installed on the loading bracket 330, close to the position of the driving wheel 320, so that the driving force can be effectively transmitted, enabling the loading module 300 to move smoothly.

[0065] In some embodiments, the loading module 300 further includes: a drive rod 340. There are multiple loading driving members 310 and driving wheels 320. Among them, every two driving wheels 320 are connected by a drive rod 340. The drive rod 340 is rotatably arranged on the other side of the loading bracket 330. At least one loading driving member 310 is in transmission connection with the drive rod 340 to drive the drive rod 340 to rotate and drive the driving wheels 320 to rotate.

[0066] Each drive rod 340 is connected to two driving wheels 320, which means that the rotation of two wheels can be controlled simultaneously by a single driving member. This design not only improves the synchronization of driving, but also enhances the adaptability and flexibility of the loading module 300 in complex terrains or tasks. In addition, at least one driving member is in transmission connection with the drive rod 340, ensuring the effective transmission of power. This design reduces power loss and improves the energy utilization efficiency of the entire system.

[0067] In some embodiments, the loading module 300 further includes: a drive rod 340. There are multiple loading driving members 310 and driving wheels 320. Among them, each driving wheel 320 is connected to a drive rod 340. The drive rod 340 is rotatably arranged on the other side of the loading bracket 330. Each loading driving member 310 is in transmission connection with a drive rod 340 to drive the drive rod 340 to rotate and drive the driving wheels 320 to rotate.

[0068] Each driving wheel 320 is connected to a drive rod 340, and each driving member is in transmission connection with a drive rod 340. This design enables each driving wheel 320 to be independently driven and controlled, thereby improving the flexibility and response speed of the loading module 300.

[0069] It should be noted that the driving wheel 320 can be designed in the style of an automobile tire or the wheel of a train, and the position movement of the loading module 300 can be achieved by cooperating with a guide rail. For example, the driving wheel 320 can adopt a high-density polyethylene wheel, and the high-density polyethylene wheel moves back and forth on the steel guide rail at a set speed.

[0070] In some embodiments, the radioactive detection device for a nuclear power plant pressure vessel includes a power cable and a measurement and control cable. The loading module 300 further includes: a cable drag chain 350. The cable drag chain 350 is arranged on the loading bracket 330 to define the movement range of the power cable and the measurement and control cable.

[0071] The cable drag chain 350 can define the movement range of the power cable and the measurement and control cable of the radioactive detection device for a nuclear power plant pressure vessel, prevent the power cable and the measurement and control cable from being entangled with each other during the forward or backward movement of the loading module 300, and also ensure that the power cable and the measurement and control cable will not be crushed by the driving wheels 320 on the loading module 300.

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

[0073] By integrating the laser rangefinder 360, the loading module 300 can accurately measure the distance to the preset reference origin. Laser ranging technology is known for its high precision and stability, and can ensure reliable measurement results under various environmental conditions (such as light changes, temperature fluctuations, etc.). In addition, the accurate ranging information helps the loading module 300 quickly and accurately locate to the target position, reducing the repeated adjustment time caused by inaccurate positions. This not only improves the operation efficiency but also reduces the labor intensity of the operator.

[0074] In some embodiments, the gamma spectroscopy measurement module 100 includes: a gamma spectroscopy detector 110, a turntable 120, a detector support platform 130, a support base 140, a lifting assembly 150, a rotation drive member 160, and a tilt drive member 170. The tilt drive member 170 is in transmission connection with the gamma spectroscopy detector 110 to drive the gamma spectroscopy detector 110 to rotate along the horizontal axis. The tilt drive member 170 is disposed on the turntable 120. The rotation drive member 160 is in transmission connection with the turntable 120 to drive the turntable 120 to rotate along the vertical axis. The rotation drive member 160 and the turntable 120 are disposed on the detector support platform 130. The lifting assembly 150 is in transmission connection with the detector support platform 130 to drive the detector support platform 130 to move up and down. 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 and drives the detector support platform 130 to rise. The rising of the detector support platform 130 drives the rotation drive member 160 and the turntable 120 to rise. The rising of the turntable 120 drives the tilt drive member 170 and the gamma spectroscopy detector 110 to rise, and stops moving upward when the center of the gamma spectroscopy detector 110 is located at the center position of the old top cover. This ensures that the center of the gamma spectroscopy detector 110 and the center of the old top cover are in the same position.

[0076] Then, when the gamma spectroscopy detector 110 maintains a certain fixed inclination state, the rotation drive member 160 drives the turntable 120 to rotate, and the gamma spectroscopy detector 110 measures the upper old top cover within a 360° circumferential angle range at this inclination. The detector of the gamma spectroscopy detector 110 can be a lanthanum bromide detector, a cadmium zinc telluride detector, or a high-purity germanium detector.

[0077] Among them, the tilt driving member 170 is a driving mechanism of the γ-ray spectrometry detector 110, and drives the γ-ray spectrometry detector 110 to rotate within the range of 90° to 45° with a set tilt angle step. The rotation driving member 160 is used to drive the turntable 120 to rotate within the range of 360° of the circumferential angle, so as to provide services for the γ-ray spectrometry detector 110 to measure the old top cover at a certain tilt angle within the range of 360° of the circumferential angle.

[0078] In some embodiments, referring to Figure 3 , the lifting assembly 150 includes: a lifting driving member 151, a slide rail 152 and a slider 153. The lifting driving member 151 and the slide rail 152 are both arranged on the support base 140. One side of the slider 153 is arranged on the detector support platform 130, and the other side of the slider 153 is slidably arranged on the slide rail 152. The driving end of the lifting driving member 151 is in transmission connection with the slider 153 to drive the slider 153 to slide on the slide rail 152.

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

[0080] The lifting assembly 150 is composed of three main parts: a lifting driving member 151, a slide rail 152 and a slider 153. These components are closely integrated on the support base 140 to form a compact and efficient lifting system. This design not only reduces the space occupation, but also improves the overall operating efficiency of the system. At the same time, the sliding connection mode of the slide rail 152 and the slider 153 ensures the smoothness and accuracy of the lifting movement. The slide rail 152 provides a stable guiding function, while the slider 153 slides smoothly along the slide rail 152, reducing the friction and vibration during the movement, thereby improving the stability and reliability of the system.

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

[0082] In some embodiments, referring to Figure 2 , the γ-ray spectrometry measurement module 100 further includes: a stop block 180 and a detection member 190. The stop block 180 is arranged on the tilt driving member 170, and the detection member 190 is arranged on the detector support platform 130.

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

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

[0085] In some embodiments, it further includes: an electrical control cabinet 400, which is arranged on the loading module 300 and is electrically connected to the γ-ray spectrometry measurement module 100, the γ-ray dose rate measurement module 200, and the loading module 300 respectively.

[0086] As the power supply unit and control unit of the radioactive detection device for the nuclear power plant pressure vessel, the electrical control cabinet 400 is not only responsible for providing stable and reliable power supply to each module, but also realizes the centralized management and operation of the entire system through the integrated control function. This design greatly simplifies the system structure and improves the working efficiency.

[0087] Specifically, the electrical control cabinet 400 is composed of 3 power supply units and four control units. The 3 power supply units of the electrical control cabinet 400 are the power supply unit 401, the power supply unit 402, and the power supply unit 403 respectively. The power supply unit 401 supplies power to the lifting drive member 151, the rotary drive member 160, and the tilting drive member 170. The power supply unit 402 supplies power to the four loading drive members 310. The power supply unit 403 supplies power to the laser rangefinder 360, the γ-ray dose rate measurement module 200, and the γ-ray spectrometry 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 in the above embodiment.

[0089] In some embodiments, please refer to Figure 4 , it further includes: a source term investigation software platform 500 and a switch 600. The source term investigation software platform 500 is signal-connected to the γ-ray spectrometry measurement module 100, the γ-ray dose rate measurement module 200, and the loading module 300 through the switch 600.

[0090] The signal connection between the source term investigation software platform 500 and each measurement module and the loading module 300 through the switch 600 enables the operator to remotely monitor the running status and data of the system in real time. This remote monitoring ability improves the flexibility and operability of the system. In addition, through the signal connection via the switch 600, the system has stronger expandability and compatibility. This means that when new measurement modules or functions need to be added, only simple connection configuration through the switch 600 is required, without large-scale modification of the entire system.

[0091] Specifically, the control units 404, 405, 406, and 407 within the electrical control cabinet 400 are controlled by a preset control program of the source term investigation software platform 500. The control program module 501 of the source term investigation software platform 500 remotely controls the control unit 404 through the switch 600 and the measurement and control cable. At the same time, the control program module 505 of the source term investigation software platform 500 remotely controls the control unit 405, the control unit 406, and the control unit 407 through the switch 600 and the measurement and control cable. The control unit 404 of the electrical control cabinet 400 locally controls the four loading driving parts 310 to act together with the driving rod 340 to drive the 4 driving wheels 320 to move back and forth on the steel guide rail at a set speed. The control unit 405 locally controls the lifting driving part 151 to drive the slider 153 to rise along the slide rail 152, driving the turntable 120 supported by the detector support table 130, the rotation driving part 160, the tilt driving part 170, the γ-ray spectrometry detector 110, and the stop block 180 to rise along the slide rail 152 until the center of the γ-ray spectrometry detector 110 is located at the center of the sphere of the old top cover and stops sliding upward. Ensure that the center of the γ-ray spectrometry detector 110 is in the same position as the center of the sphere of the old top cover; the control unit 406 locally controls the rotation driving part 160 to drive the turntable 120 to rotate, ensuring that the γ-ray spectrometry detector 110 completes the radiation source term measurement and investigation of the upper old top cover within a 360° circumferential angle at a set inclination angle; the control unit 407 locally controls the tilt driving part 170 and drives the γ-ray spectrometry detector 110 to rotate within the range of 90° to 45° at a set inclination angle step.

[0092] As Figure 4 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 γ-dose rate measurement module 200, and the γ-ray spectrometry detector 110 through the switch 600 and the measurement and control cable respectively. The data receiving and control modules 502, 503, and 504 respectively receive the reference distance data measured by the laser rangefinder 360, the γ-dose rate data measured by the γ-dose rate measurement module 200, and the γ-ray spectrometry data measured by the γ-ray spectrometry detector 110. The γ-ray spectrometry analysis module 506 of the source term investigation software platform 500 analyzes the γ-ray spectrometry measured by the γ-ray spectrometry detector 110 to obtain the nuclide types, activities, and total activities in each γ-ray spectrometry; the data and alarm display module 507 receives the measurement data and alarm signals of each component and displays them.

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

[0094] Please refer to Figure 5 , this embodiment also provides a method for detecting the radioactivity of a nuclear power plant pressure vessel, which is applied to the nuclear power plant pressure vessel radioactivity detection device of the above embodiment, and includes:

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

[0096] In this embodiment, before step S101, the nozzle seats on the old top cover head need 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] Specifically, please refer to Figure 6 , the pressure vessel top cover is composed of a top cover head and a top cover flange. The pressure vessel top cover head is welded with exhaust nozzle seats, control rod drive mechanism nozzle seats, core measurement and water level measurement nozzle seats, and these nozzle seats are all welded parts.

[0098] Before conducting the source item investigation of the old top cover, the nozzle seats on the old top cover head can be cut off by flame cutting. The old top cover after cutting off the nozzle seats only remains the top cover flange and the top cover head.

[0099] Then, three guide rails are fixed side by side directly below the old top cover support frame. The middle guide rail is directly below the center of the old top cover support frame, and the old top cover with the nozzle seats cut off is placed on the old top cover support frame. The nuclear power plant pressure vessel radioactivity detection device is placed on two adjacent guide rails by a crane. The four drive wheels 320 drive the nuclear power plant pressure vessel radioactivity detection device to travel on the guide rails. The drive wheel 320 on the same side as the γ spectrometry detector 110 in the nuclear power plant pressure vessel radioactivity detection device is placed on the middle guide rail, and the drive wheel 320 on the other side is placed on the adjacent guide rail. Ensure that the γ spectrometry detector 110 is always located on the central axis of the old top cover support frame.

[0100] When the nuclear power plant pressure vessel radioactivity detection device is placed on the guide rails, then power on the device and conduct communication and control tests for each component.

[0101] Specifically, before conducting the source term investigation of the old top cover, various preparatory work should be done. Check that the terminations of the power cables between each component and the power supply units 401, 402, and 403 of the electrical control cabinet 400 are in good condition, and the terminations of the measurement and control cables between the switch 600 and each device and control module are in good condition. Confirm that the termination of the power cable between the electrical control cabinet 400 and the power distribution panel of the power plant is in good condition, and the power distribution panel supplies power to the electrical control cabinet 400. Turn on the air switches of the 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 on normally. On the workstation, confirm that the control unit 404 can be remotely controlled through the control program module 501 on the workstation, and at the same time, the control units 405, 406, and 407 can be remotely controlled through the control program module 505 of the source term investigation software platform 500. Then, on the workstation, turn on the laser rangefinder 360, the γ dose rate measurement module 200, and the γ energy spectrum detector 110 through the data reception and control modules 502, 503, and 504 of the source term investigation software platform 500 and receive their measurement data, and then confirm that the data reception and control modules 502, 503, and 504 can remotely control the start and stop of the laser rangefinder 360, the γ dose rate measurement module 200, and the γ energy spectrum detector 110 respectively and receive their measurement data.

[0102] After confirming that the communication and control of each component are in good condition, then step S101 is executed.

[0103] Specifically, on the workstation, the laser rangefinder 360 is started through the data reception and control module 502 of the source term investigation software platform 500 via 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 sphere of the old top cover on the ground is input into the data reception and control module 502.

[0104] On the workstation, the control unit 404 is controlled through the control program module 501 of the source term investigation software platform 500. The control unit 404 locally starts four loading driving parts 310, and controls the four loading driving parts 310 and the corresponding driving rods 340 to act together to drive the 4 driving wheels 320 to move on the steel guide rail at a set speed of 0.1 m / s, so that the loading module 300 moves towards the center of the old top cover.

[0105] Subsequently, the laser rangefinder 360 transmits the distance between the center of the γ - ray spectrometer detector 110 and the reference origin to the data receiving and control module 502 via the measurement and control cable and the switch 600. When the data of the distance between the center of the γ - ray spectrometer detector 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 sends an automatic stop signal to the control unit 404 via the measurement and control cable and the switch 600, and the control unit 404 locally controls the four loading driving parts 310 to stop operating. After the four loading driving parts 310 completely stop, the control unit 404 sends an alarm signal to the control program module 501 via the measurement and control cable and the switch 600, prompting the control program module 501 to stop receiving the alarm signal sent by the data receiving and control module 502.

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

[0107] After the above steps are completed, at this time, the loading module 300 is below the old top cover, and the γ - ray spectrometer detector 110 is directly below the center of the old top cover.

[0108] S102: Detect the γ - ray dose rate within a predetermined time through the γ - ray dose rate measurement module, and confirm the single - measurement time of the γ - ray spectrometer measurement module according to the γ - ray dose rate;

[0109] Specifically, after the data and alarm display module 507 displays the alarm signal that the four loading driving parts 310 have completely stopped, the control program module 505 sets the upward sliding distance M of the slider 153 for the control unit 405. The control program module 505 remotely controls the control unit 405 to locally control the lifting driving part 151 to drive the slider 153 to rise along the slide rail 152. The slider 153 drives the detector support platform 130, the turntable 120, the rotation driving part 160, the tilt driving part 170, the γ - ray spectrometer detector 110, and the stopper 180 to rise along the slide rail 152. When the upward sliding distance of the slider 153 is M, the control unit 405 locally controls the slider 153 to stop sliding and sends an alarm signal that the slider 153 has slid upward and is in place to the control program module 505 and the data and alarm display module 507 via the measurement and control cable and the switch 600. At this time, the center of the γ - ray spectrometer detector 110 is located at the center position of the old top cover.

[0110] After the data and alarm display module 507 displays the alarm signal indicating that the slider 153 has slid upward and is in place, the data reception and control module 503 activates the γ dose rate measurement module 200 to conduct γ dose rate measurement directly below the old top cover. The measurement data is fed back to the data reception and control module 503 and the data and alarm display module 507 in real time via the measurement and control cable and the switch 600, and the measurement time is 1 minute. The data reception and control module 503 calculates the average value of the measurement data received from the γ dose rate measurement module 200 within 1 minute. According to the following principles, the data reception and control module 503 determines the single measurement time for the γ energy spectrum detector 110 and displays it on the data and alarm display module 507. Subsequently, the γ dose rate measurement module 200 is turned off via the data reception and control module 503 to stop the γ dose rate measurement.

[0111] The principles are as follows: When the γ dose rate the measurement time is 2 min;

[0112] When the measurement time is 1 min;

[0113] When the γ dose rate the measurement time is 30 s.

[0114] S103: Divide the old top cover into a grid to obtain a number of grid regions;

[0115] Specifically, dividing the old top cover into a grid to obtain a number of grid regions includes:

[0116] Connect the top of the old top cover and the center of the sphere of the old top cover to obtain a top straight line;

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

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

[0119] Divide the 360° of the N circular rings into M equal parts according to a second predetermined angle to obtain M×N grid regions.

[0120] By adjusting the first predetermined angle and the second predetermined angle, the number of grids (N×M) can be flexibly controlled. This flexibility enables the method to adapt to old top covers of different sizes and complexities, meeting diverse analysis or renovation requirements.

[0121] For example, the old top cover can be regarded as a part of a sphere. The diameter of the sphere corresponding to the old top cover is about 4.7 m. Connect the top end of the old top cover with the center of the sphere of the old top cover to obtain the top straight line; connect any point on the outer side of the flange bottom of the old top cover with the center of the sphere of the old top cover to obtain the flange straight line; the included angle formed by the top straight line and the flange straight line is about 45°. When conducting the source term investigation on the inner surface of the top cover, divide the included angle of about 45° formed by the top straight line and the flange straight line into 6 grid regions (i.e., 6 circular rings), and the included angle of each grid region is 7.5° (equivalent to dividing the old top cover into 6 parts in the plane direction from the top to the flange surface). Then divide each circular ring into 50 equal parts by 360° (equivalent to dividing each circular ring into 50 parts in the vertical direction, and the second predetermined angle is 7.2°), thus dividing the old top cover into 300 grid regions (6 * 50 = 300). The source term investigation on the inner surface of the top cover is to conduct measurements on each of the 300 grid regions on the inner surface of the old top cover one by one to obtain the source term of the inner surface of the old top cover for each grid region. According to the results of the source term investigation, the radionuclide composition, activity and total activity information of each grid region on the inner surface of the old top cover can be obtained, providing information and guidance for decontamination of the inner surface of the old top cover.

[0122] S104: Detect a plurality of the grid regions through the γ - ray spectrometry measurement module and according to the single - measurement time of the γ - ray spectrometry measurement module, and obtain the γ - ray spectrometry data of each grid region;

[0123] Specifically, detecting a plurality of grid regions through the γ - ray spectrometry measurement module 100 and according to the single - measurement time of the γ - ray spectrometry measurement module 100 to obtain the γ - ray spectrometry data of each grid region includes the following situations:

[0124] The first type: Based on the vertical 90°, tilt the γ - ray spectrometer 110 by the first predetermined angle through the tilt driving member 170, and drive the γ - ray spectrometer 110 to rotate forward and backward one full circle by the second predetermined angle through the rotation driving member 160;

[0125] Increase the first predetermined angle successively through the tilt driving member 170, and drive the γ - ray spectrometer 110 to rotate forward and backward one full circle by the second predetermined angle through the rotation driving member 160 until the tilt angle of the γ - ray spectrometer 110 reaches the maximum tilt angle, and obtain the γ - ray spectrometry data of each grid region;

[0126] The second type: Based on the vertical 90°, tilt the γ - ray spectrometer 110 by the first predetermined angle through the tilt driving member 170, and increase the first predetermined angle successively;

[0127] When the tilt angle of the γ - ray spectrometer 110 reaches the maximum tilt angle, decrease the first predetermined angle successively to return the γ - ray spectrometer 110 to the upright position;

[0128] Wait for the γ - ray energy spectrum detector 110 to return to 90°, and drive the γ - ray energy spectrum detector 110 to rotate according to a second predetermined angle through the rotation driving member 160 until the γ - ray energy spectrum detector 110 rotates one week, and obtain the γ - ray energy spectrum data of each grid area.

[0129] By the combined use of the tilt driving member 170 and the rotation driving member 160, the γ - ray energy spectrum detector 110 can scan the grid area at multiple angles and directions. This all - around scanning method ensures that each grid area can be fully covered, thereby improving the comprehensiveness and accuracy of the measurement.

[0130] The following is a detailed description of the first case:

[0131] The control program module 505 sets the angle of a single tilt of the tilt driving member 170 to drive the γ - ray energy spectrum detector 110 for the control unit 407. According to the data and the single measurement time T1 of the γ - ray energy spectrum detector 110 (i.e., the sum of the rotation time of the turntable 120 for 7.2° and the single measurement time of the γ - ray energy spectrum detector 110) displayed by the data and alarm display module 507, the control program module 505 sets the rotation time T2 of the rotation driving member 160 to drive the turntable 120 to complete a 7.2° rotation for the control unit 406, and sets the single measurement time T3 of the γ - ray energy spectrum detector 110 in the data reception and control module 504.

[0132] In this embodiment, the angle of a single tilt of the tilt driving member 170 to drive the γ - ray energy spectrum detector 110 is 7.5°. When the rotation time of the rotation driving member 160 to drive the turntable 120 to complete a 7.2° rotation is 2 min, the rotation time to complete a 360° rotation is 100 min, and the single measurement time of the γ - ray energy spectrum detector 110 is 2 min; when the rotation time of the rotation driving member 160 to drive the turntable 120 to complete a 7.2° rotation is 1 min, the rotation time to complete a 360° rotation is 50 min, and the single measurement time of the γ - ray energy spectrum detector 110 is 1 min; when the rotation time of the rotation driving member 160 to drive the turntable 120 to complete a 7.2° rotation is 30 s, the rotation time to complete a 360° rotation is 25 min, and the single measurement time of the γ - ray energy spectrum detector 110 is 30 s.

[0133] The investigation of the source term on the inner surface of the top cover is divided into the following steps:

[0134] Step a: The tilt driving member 170 drives the γ - ray energy spectrum detector 110 to tilt 7.5° once:

[0135] After the above parameter settings are completed on the source item survey software platform 500 through the control program module 505, 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-ray spectrometer detector 110 to tilt 7.5° away from the support base 140.

[0136] After completing the 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 γ-ray spectrometer detector 110 has completed a 7.5° tilt, transmitting the tilt count and the current tilt angle of the γ-ray spectrometer detector 110. The control program module 505 transmits the tilt count of the γ-ray spectrometer detector 110 to the data reception and control module 504, and transmits the tilt angle of the γ-ray spectrometer detector 110 to the data and alarm display module 507 and displays the tilt angle of the γ-ray spectrometer detector 110.

[0137] Through 6 tilt operations, the tilt drive 170 drives the γ-ray spectrometer detector 110 to tilt from 90° to 82.5°, 75°, 67.5°, 60°, 52.5° and 45° in sequence.

[0138] Step b: The rotation drive 160 drives the turntable 120 to rotate and measure the source item on the inner surface of the old top cover:

[0139] After the control program module 505 receives the signal from the control unit 407 indicating that the γ-ray spectrometer detector 110 has completed a 7.5° tilt, it automatically sends a signal to the data reception and control module 504. The data reception and control module 504 starts the measurement of the γ-ray spectrometer detector 110. At the same time, the control program module 505 automatically controls the control unit 406 to locally control the rotation drive 160 to drive the turntable 120 and rotate counterclockwise starting from the stop block 180.

[0140] When the rotation drive 160 drives the turntable 120 to complete a 360° rotation counterclockwise, the stop block 180 prevents the rotation drive 160 from driving the turntable 120 to continue rotating counterclockwise. The control unit 406 locally controls the rotation drive 160 to drive the turntable 120 to complete a 360° rotation clockwise and return to the starting origin. At this time, the control unit 406 will send a signal to the control program module 505 via the measurement and control cable and the switch 600 indicating that the turntable 120 has completed a 360° rotation counterclockwise and clockwise. 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-ray spectrometer detector 110 to tilt 7.5° away from the support base 140. Then, the operation of tilting the γ-ray spectrometer detector 110 by 7.5° once is completed according to the method in step a.

[0141] When the number of tilts of the gamma energy spectrum detector 110 received by the data receiving and control module 504 reaches 6, the data receiving and control module 504 automatically sends a signal to the control program module 505 to automatically stop receiving the signal from the control unit 406. After the turntable 120 has completed one full 360° rotation in both the counterclockwise and clockwise directions, the data receiving and control module 504 automatically shuts down the gamma energy spectrum detector 110, completing the measurement of the source term on the inner surface of the old top cover.

[0142] Similarly, the second scenario is similar to the first, and will not be elaborated further here.

[0143] When the turntable 120 rotates by 7.2° each time, the gamma energy spectrum detector 110 completes one measurement, and stores the gamma energy 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 count X + rotation mode Y + rotation count ZZ (the rotation modes are divided into counterclockwise rotation and clockwise rotation, where counterclockwise rotation is represented by 1 and clockwise rotation is represented by 2) (as Figure 7 shown).

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

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

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

[0147] Specifically, after completing the measurement of the source term 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 γ-ray spectrometer 110 to return from 45° to 90° in the reverse direction. The control unit 407 sends a signal indicating that the γ-ray spectrometer 110 has returned to 90° to the control program module 505 via the measurement and control cable and the switch 600. Subsequently, the control program module 505 remotely controls the control unit 405. The control unit 405 locally controls the lifting drive 151 to drive the slider 153 to descend along the slide rail 152 until the slider 153 descends to the origin position. The control unit 405 sends a signal indicating that the slider 153 has descended to the origin position to the control program module 505 via the measurement and control cable and the switch 600.

[0148] Then the data reception and control module 502 inputs 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 as 0. Then, on the workstation, the control program module 501 of the source term investigation software platform 500 is used to control the control unit 404. Then the control unit 404 locally activates the four loading drives 310. The four loading drives 310 and the drive rod 340 act together to drive the four drive wheels 320 to move on the steel guide rail at a set speed of 0.1 m / s, and then drive the radioactive detection device of the nuclear power plant pressure vessel to move in the direction of returning along the original path.

[0149] The laser rangefinder 360 transmits the distance between the radioactive detection device of the nuclear power plant pressure vessel and the reference origin to the data reception and control module 502 via the measurement and control cable and the switch 600. When the data of the distance between the radioactive detection device of the nuclear power plant pressure vessel and the reference origin is 0 (indicating that the four loading drives 310 and the drive rod 340 act together to drive the radioactive detection device of the nuclear power plant pressure vessel to return to the starting origin), then the data reception 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 the switch 600. The control unit 404 locally controls the four loading drives 310 to stop moving.

[0150] Then the electrical control cabinet 400 turns off the air switches of the power supply unit 401, the power supply unit 402, and the power supply unit 403 to cut off the power supply for each device, and confirms that each device has been powered off.

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

[0152] Specifically, after analyzing the γ-ray spectrum data of each grid area to obtain the radioactive nuclide composition, activity, and total activity information of each grid area, it includes:

[0153] The source term investigation software platform 500 uses continuous colors to reflect the total radioactivity information of each grid area on the inner surface of the old top cover in several grid areas and displays it in a three-dimensional form. At the same time, the total radioactivity data of each grid area is displayed in a list form.

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

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

[0156] The γ - ray spectrum detector 110 measures each grid area on the inner surface of the old top cover once when the turntable 120 rotates counterclockwise and clockwise, and takes the average of the two measurement results as the data of the radioactivity and total activity of the grid area on the inner surface of the old top cover, thereby reducing the measurement error of the radioactivity and total activity of each grid area on the inner surface of the old top cover and improving the measurement accuracy.

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

[0158] After the γ - ray spectrum analysis module 506 completes the analysis of the radioactivity and total activity measurement values of each grid area of the old top cover, 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 top cover and displays it in a three - dimensional form. At the same time, the total radioactivity data of each region is displayed in a list form. This data is used to guide the decontamination of the inner surface of the old top cover.

[0159] The various embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method section. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

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

[0161] Comprising, such that a process, method, article or device including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device including the element.

Claims

1. A radioactivity detection device for pressure vessels in nuclear power plants, used for source item investigation of old top covers of pressure vessels, characterized in that: include: A gamma spectrum measurement module, a gamma dose rate measurement module and a loading module, wherein the gamma spectrum measurement module and the gamma dose rate measurement module are both arranged on the loading module, and a loading drive and a driving wheel are arranged on the loading module, and the loading drive and the driving wheel are connected in a transmission manner to drive the driving wheel to rotate and drive the loading module to move, so that the gamma spectrum measurement module can move to the center of the old top cover and detect the old top cover.

2. The nuclear power plant pressure vessel radioactivity detection device according to claim 1, characterized in that: The loading module comprises: a loading bracket, the gamma spectrum measurement module and the gamma dose rate measurement module are both arranged on one side of the loading bracket, the loading drive is installed on the other side of the loading bracket, and the driving wheel is arranged 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 also includes: a driving rod, a plurality of loading driving members and driving wheels, wherein every two driving wheels are connected by a driving rod, the driving rod is rotatably arranged on the other side of the loading bracket, and at least one loading driving member is transmission-connected to the driving rod to drive the driving rod to rotate and drive the driving wheel to rotate.

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

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

6. The nuclear power plant pressure vessel radioactivity detection device according to claim 1, characterized in that: The gamma spectrum measurement module includes: a gamma spectrum detector, a turntable, a detector support platform, a support base, a lifting assembly, a rotating drive and a tilting drive. The tilting drive is connected to the gamma spectrum detector to drive the gamma spectrum detector to rotate along a horizontal axis. The tilting drive is arranged on the turntable. The rotating drive is connected to the turntable to drive the turntable to rotate along a vertical axis. The rotating drive and the turntable are arranged on the detector support platform. The lifting assembly is connected to the detector support platform to drive the detector support platform to rise and fall. The lifting assembly is arranged on the support base, and the support base is arranged on the loading module.

7. The nuclear power plant pressure vessel radioactivity detection device according to claim 6, characterized in that: The lifting assembly includes: a lifting drive member, a slide rail and a slider, the lifting drive member and the slide rail are both arranged on the support base, one side of the slider is arranged on the detector support platform, and the other side of the slider is slidably arranged on the slide rail, and the driving end of the lifting drive member is transmission-connected to the slider to drive the slider to slide on the slide rail.

8. The nuclear power plant pressure vessel radioactivity detection device according to claim 6, characterized in that: The gamma energy spectrum measurement module further includes: a stopper and a detection member, wherein the stopper is arranged on the tilt driving member, and the detection member is arranged on the detector supporting platform.

9. The nuclear power plant pressure vessel radioactivity detection device according to claim 1, characterized in that: Also includes: An electrical control cabinet is arranged 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.

10. A radioactivity detection device for pressure vessels of nuclear power plants, characterized in that: include: A radioactivity detection device for a nuclear power plant pressure vessel as described in any one of claims 1 to 9.

11. The nuclear power plant pressure vessel radioactivity detection equipment according to claim 10, characterized in that: Also includes: A source item investigation software platform and a switch, wherein the source item investigation software platform is signal-connected with the gamma energy spectrum measurement module, the gamma dose rate measurement module and the loading module through the switch.

12. A method for detecting radioactivity of a pressure vessel in a nuclear power plant, applied to the radioactivity detection device for a pressure vessel in a nuclear power plant as claimed in any one of claims 10 to 11, characterized in that: include: Setting the reference origin, and driving the loading module to enter directly below the old top cover; Detecting a gamma dose rate within a predetermined time by the gamma dose rate measurement module, and confirming a single measurement time of the gamma energy spectrum measurement module according to the gamma dose rate; Dividing the old roof into grids to obtain a plurality of grid areas; Detecting a plurality of the grid areas by the gamma spectrum measurement module and according to a single measurement time of the gamma spectrum measurement module, to obtain gamma spectrum data of each grid area; The gamma energy spectrum data of each grid area are analyzed to obtain the radionuclide composition, activity and total activity information of each grid area.

13. The method for detecting radioactivity of a pressure vessel of a nuclear power plant according to claim 12, characterized in that: The old roof is divided into grids to obtain several grid areas including: Connect the top of the old top cover and the center of the sphere of the old top cover to obtain a top straight line; Connect any point on the outer side of the bottom of the flange of the old top cover and the center of the sphere of the old top cover to obtain a flange straight line; Dividing the angle formed by the top straight line and the flange straight line according to a first predetermined angle to obtain N circular rings; The N circular rings of 360° are equally divided into M parts according to a second predetermined angle to obtain M×N grid areas.

14. The method for detecting radioactivity of a pressure vessel in a nuclear power plant according to claim 13, wherein the gamma spectrum measurement module comprises: The gamma spectrum detector, the rotating drive member and the tilting drive member are characterized in that the gamma spectrum measurement module is used to detect a plurality of the grid areas according to a single measurement time of the gamma spectrum measurement module, and the gamma spectrum data of each grid area is obtained, including the following situations: The first method: taking the vertical 90° as a reference, the gamma spectrum detector is tilted at the first predetermined angle by the tilt driving member, and the gamma spectrum detector is driven to rotate one circle in the forward direction and one circle in the reverse direction at the second predetermined angle by the rotation driving member; The first predetermined angle is gradually increased by the tilt driving member, and the gamma spectrum detector is driven to rotate in a forward direction and a reverse direction by the rotation driving member at a second predetermined angle for one circle each, until the tilt angle of the gamma spectrum detector reaches a maximum tilt angle, and gamma spectrum data of each grid area is obtained; The second method is to tilt the gamma energy spectrum detector according to the first predetermined angle by the tilt driving member with a vertical angle of 90° as a reference, and gradually increase the first predetermined angle; When the inclination angle of the gamma spectrum detector reaches a maximum inclination angle, gradually reducing the first predetermined angle to correct the gamma spectrum detector; After the gamma spectrum detector is returned to 90°, the gamma spectrum detector is driven to rotate at a second predetermined angle by the rotary drive member until the gamma spectrum detector rotates one circle, and gamma spectrum data of each grid area is obtained.

15. The method for detecting radioactivity of a pressure vessel of a nuclear power plant according to claim 12, wherein the radioactivity detection equipment for detecting radioactivity of a pressure vessel of a nuclear power plant further comprises: The source term investigation software platform is characterized in that the gamma spectrum data of each grid area is analyzed to obtain the radionuclide composition, activity and total activity information of each grid area, and then the following steps are performed: The source item survey software platform reflects the total radioactivity information of each grid area on the inner surface of the old top cover with continuous colors in several grid areas on the inner surface of the old top cover and displays it in a three-dimensional form, and at the same time displays the total radioactivity data of each grid area in the form of a list.

Images