Radioactive source positioning system and method

Abstract

The invention discloses a radioactive source positioning system and a radioactive source positioning method. The positioning method comprises the following steps: preparing a radiation detector and a shielding detector, wherein a shielding block sleeves a detection end of the shielding detector; the thickness of the shielding block is uniformly and progressively increased, and the outer end surface is spiral; when a suspected radiation field area is reached, a radiation detector and a shielding detector are adopted at the same position to detect a radioactive source radiation intensity counting rate N0 and a radioactive source shielding radiation intensity counting rate N of the current area; calculating a proportional relation between a radioactive source radiation intensity counting rate N0 and a radioactive source shielding radiation intensity counting rate N according to a ray attenuation formula, judging the incident thickness and the incident angle of rays penetrating through the shielding block, determining the orientation of the radioactive source, and obtaining the orientation information of the radioactive source; meanwhile, the distance between the radioactive source and the radiation detector is calculated according to the measured radiation intensity of the radioactive source; and positioning the radioactive source according to the azimuth information of the radioactive source and the distance of the radioactive source relative to the radiation detector.

Description

Technical Field

[0001] The present invention relates to the field of nuclear radiation detection, and in particular to a radiation source positioning system and a positioning method. Background Art

[0002] With the continuous development of the nuclear industry, the application of radioactive sources is becoming more and more widespread. Radioactive sources often leak and are stolen, which seriously threatens people's health and life safety. Therefore, it is of great practical significance to quickly search and remove scattered radioactive contamination sources. At present, the search for radioactive sources is generally carried out by workers engaged in nuclear technology, who carry radiation detectors and rely on their own experience, or by vehicles carrying detectors to conduct carpet searches of the target area. These methods are inefficient and may endanger the safety of operators in serious cases.

[0003] The Chinese patent application number 2024103808269 discloses a method and device for locating a radiation source, which uses a detection device to collect radiation intensity information of the surrounding environment; obtains the first position information of the detection device; controls the horizontal rotation and pitch deflection of the detection device to collect the first radiation intensity information of the surrounding environment; generates a first radiation intensity map based on the first radiation intensity information, and determines the first azimuth of the radiation source relative to the detection device based on the first radiation intensity map; obtains the second position information when the detection device is in the second position; collects the second radiation intensity information of the surrounding environment; generates a second radiation intensity map based on the second radiation intensity information, and determines the second azimuth of the radiation source relative to the detection device based on the second radiation intensity map; determines the position information of the radiation source based on the first azimuth, the second azimuth, and the distance between the first position and the second position. The above detection method uses a detection device to collect different radiation intensities at different positions, and then determines the position information of the radiation source by comparing the distance between the radiation intensities and position information detected twice. Although this measurement method obtains the position of the radiation source by integrating the azimuth information twice, the method of obtaining the two azimuths by only detecting the radiation intensity once by one detector to determine the azimuth is not accurate. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a radiation source positioning system and positioning method to solve the problem that the prior art method of obtaining the azimuth of the radiation source is inaccurate, resulting in inaccurate subsequent positioning results.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A radiation source positioning system comprises a detection module, a power supply module and a main control module. The detection module is electrically connected to the power supply module 1 and comprises a radiation detector and a shielding detector. The radiation detector is used to detect the radiation intensity count rate of the radiation source in the current environment and send the detected radiation intensity to the main control module. A shielding block with a uniformly increasing thickness is sleeved on the detection end of the shielding detector, which is used to detect the shielding radiation intensity count rate of the radiation source at the same position and detection environment of the radiation detector and send the shielding radiation intensity count rate of the radiation source to the main control module. The main control module is electrically connected to the power supply module and comprises a data processing module. The radiation intensity count rate of the radiation source emitted by the radiation detector and the shielding radiation intensity count rate of the radiation source emitted by the shielding detector are received; and converted into a radiation intensity dose rate p to calculate the distance of the radiation source relative to the detection module. At the same time, the proportional relationship between the radiation intensity count rate of the radiation source and the shielding radiation intensity dose rate of the radiation source is calculated according to the ray attenuation formula, and the incident thickness and incident angle of the radiation passing through the shielding block are judged to determine the position of the radiation source. Finally, according to the position information of the radiation source and the distance information of the radiation source relative to the detection module, the position of the radiation source is determined, the radiation source is located, and the source positioning information is sent to the client or the cloud. In this way, the radiation source positioning system used has a radiation detector and a shielding detector, which can perform a radiation intensity test on the suspected lost area of ​​the radiation source at the same position, and obtain the radiation intensity after shielding and the radiation intensity without shielding, so that the incident thickness of the radiation emitted by the radiation source can be judged according to the proportional relationship between the two, and then the position of the radiation source can be determined. This method of determining the shielding thickness after comparing the shielding radiation intensity with the current radiation intensity, and determining the position of the radiation source according to the position corresponding to the shielding thickness in the shielding block, the position acquisition is more accurate. The thickness of the shielding block increases evenly and the installation position is fixed. Therefore, when the radiation enters different positions, the intensity count rate of the detected radiation source after shielding is different, and the position is more accurate. Under the premise of more accurate radiation source position, the radiation source positioning obtained by combining the radiation source position and the distance between the radiation source and the radiation detector is more accurate. The system used contains fewer components and less calculation, and can be widely promoted.

[0007] Furthermore, the ray attenuation formula is as follows: N = N 0 e -ud , where N 0 is the radiation intensity count rate of the radiation source, N is the radiation intensity count rate of the radiation source shielding, u is the attenuation coefficient of the gamma ray in the shielding block, and d is the shielding thickness of the shielding block at the incident point; transforming the ray attenuation formula, we can get: The shielding thickness d on the shielding block corresponds to the thickness position interval, which is the incident angle of the ray, and the azimuth indicated by the incident angle is the azimuth of the radiation source. In this way, after adopting the above formula, the specific values ​​detected by the radiation detector and the shielding detector are substituted into the formula to quickly obtain the shielding thickness of the ray incident, thereby determining the incident angle and azimuth.

[0008] Furthermore, it also includes a display alarm module, which is electrically connected to the power supply module and is in communication connection with the main control module, and includes a display module and an alarm module. The display module is used to display the radiation source location information sent by the main control module; the main control module is also used to send an alarm message to the alarm module after receiving the radiation intensity exceeding the alarm threshold; the alarm module is used to receive the alarm message sent by the main control module and alarm through voice or light. In this way, after using the display alarm module, it is convenient for operators to perform corresponding operations.

[0009] Furthermore, the shielding block is a lead shielding block or a tungsten shielding block; the radiation detector and the shielding detector are respectively assembled in a protective cover or a protective shell, and the detection ends are arranged adjacent to each other. In this way, in application, the radiation detector and the shielding detector can be installed as needed.

[0010] A method for locating a radiation source comprises the following steps: S1, preparing two detectors, one of which is a radiation detector 21, and the other is a shielding detector with a shielding block on the detection end; the thickness of the shielding block increases uniformly, and the outer end surface is spiral; S2, reaching a suspected radiation field area, using the radiation detector and the shielding detector at the same position to detect the radiation intensity count rate N of the radiation source in the current area 0 and the radiation intensity count rate N of the radiation source shielding; S3, the radiation intensity count rate N of the radiation source is calculated by the controller according to the ray attenuation formula 0The incident thickness and incident angle of the radiation passing through the shielding block are judged based on the proportional relationship between the radiation intensity count rate N of the radiation source shielding, the orientation of the radiation source is determined, and the orientation information of the radiation source is obtained; at the same time, the distance between the radiation source and the radiation detector is calculated based on the measured radiation intensity of the radiation source; S4, according to the orientation information of the radiation source and the distance of the radiation source relative to the radiation detector, the position of the radiation source is determined, and the radiation source is positioned. In this way, when positioning the radiation source, the orientation of the radiation source is first determined based on the different radiation intensity count rates detected by the two detectors, and then the distance between the detector and the radiation source is calculated in combination with the radiation intensity dose rate of the radiation source detected by the detector, so that the precise position of the radiation source can be determined under the dual indication of orientation and distance. When determining the orientation of the radiation source, the shielding thickness of the radiation entering is calculated based on the ratio of the radiation intensity count rate of the unshielded radiation source and the radiation intensity count rate of the shielded radiation source, and the orientation of the radiation source is determined based on the orientation corresponding to the shielding thickness in the shielding block, so that the orientation is obtained more accurately. The thickness of the shielding block increases evenly and the installation position is fixed. Therefore, when the radiation enters different directions, the intensity count rate of the radiation source detected after shielding will be different, making the position more accurate.

[0011] Furthermore, when locating the radioactive source, in order to reduce errors, the radioactive source is located twice in succession, wherein the test position for the second radioactive source location is changed to a new position after the first test is completed, and the radiation intensity test of the radioactive source is performed again; the method of locating the radioactive source twice is as described in S2-S4, and the radioactive source location interval 1 is obtained after the first radioactive source location, and the radioactive source location interval 2 is obtained after the second radioactive source location; after obtaining the radioactive source location interval 1 and the radioactive source location interval 2, it is determined whether the two radioactive source location intervals overlap, if not, it is considered that the radioactive source is blocked, and multiple tests are required to improve the accuracy; if there is an overlapping interval, the overlapping interval is integrated and the overlapping interval is used as the radioactive source location interval. In this way, this method of using the overlapping parts of each location interval as the radioactive source location interval after multiple determinations of the radioactive source location interval is more accurate than a one-time determination.

[0012] Furthermore, in order to make the method of rapid location of radioactive sources applicable to a variety of nuclides, it is necessary to make appropriate extensions. 0 e -ud , N and N 0 is the detector measurement data, which can be read directly, e is a constant, u is the shielding coefficient of the shielding body for a certain nuclide. When the nuclide is determined, u is a constant, and d is the thickness of the shielding body corresponding to the radiation source orientation, which is the only variable to be sought. For a specific nuclide, the shielding coefficient u can be found by simply substituting the measured N and N 0The thickness d can be calculated to determine the direction of the radiation source. The type of nuclide can be determined by using a detector with nuclide identification capability. Different u values ​​can be called according to the type of nuclide to achieve rapid positioning of multiple nuclides. To further improve the positioning accuracy, the actual measurement experiment can be conducted to measure the difference between N and N when a specific radiation source is located in the direction of different thicknesses d of the shield. 0 The specific value of N and N 0 The fitting formula for thickness d is directly written into the data processing program of the controller, and the controller can calculate the thickness d according to the measured N and N 0 The value of can automatically determine the location of the radiation source.

[0013] Furthermore, in S2, when detecting the radiation intensity count rate N of the radiation source 0 When the radiation intensity count rate N of the radiation source is detected, the radiation detector and the shielding detector are installed in the same protective cover for synchronous detection. When installed, the detection end of the radiation detector and the shielding detector are arranged up and down, and the two detection ends are adjacent. 0 When measuring the radiation intensity count rate N of the radiation source shielding, the radiation detector and the shielding detector can also be respectively assembled in a protective shell and tested successively at the same test position. In this way, in the application process, both synchronous measurement and sequential measurement are possible, so that the existing detector can be modified according to the actual situation. Both methods can achieve the radiation intensity count rate N of the radiation source. 0 And the measurement of radiation intensity count rate N of the radiation source shielding. The method of installing two detectors together and detecting synchronously is more convenient and faster. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a structural block diagram of a radiation source positioning system in an embodiment;

[0015] Figure 2 It is a schematic diagram of the split structure of the shielding detector and the shielding block in the embodiment;

[0016] Figure 3 A schematic diagram of a state where radiation rays enter a shielding block in an embodiment;

[0017] Figure 4 is a flow chart of a method for locating a radiation source in an embodiment;

[0018] Figure 5 A schematic diagram of the ray angle between the detector and the radiation source in the embodiment;

[0019] Figure 6 It is a schematic diagram showing the display of the azimuth angle measured multiple times in the embodiment. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0021] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] This embodiment studies how to quickly locate a lost radioactive source. Generally speaking, the existing radioactive source generally refers to a gamma source, and gamma rays have a strong penetrating ability. In radioactive source location, the radioactive source can be approximately regarded as a point source. The gamma ray source continuously emits gamma photons to the surrounding space. The gamma photons emitted by the source to the surrounding space are isotropic. The count rate n of the detector at a distance r obeys the following formula:

[0023] Where ε is the detection efficiency of the detector, A is the activity of the radiation source, and r is the distance between the detector and the radiation source. From the above formula, it can be concluded that the detector count rate n is inversely proportional to the square of the distance from the source. Determining the location of the radiation source by detecting the change in the radiation count rate is one of the most basic methods. In addition, the gamma rays generated by the radiation source propagate in a straight line and have directionality. When passing through the shielding material, the intensity will be weakened. Its attenuation formula obeys: N = N 0 e -ud ,

[0024] Where N 0 and N represent the number of photons before and after passing through the material layer respectively; d is the thickness of the material layer, and u is the linear attenuation coefficient of gamma rays in the material. Through this property, we can study the direction detectors that are sensitive to the direction of gamma rays to achieve the purpose of locating the radiation source.

[0025] like Figure 1 , Figure 2As shown, the radiation source positioning system provided in this embodiment includes a detection module 2, a power supply module 1 and a main control module 3. The detection module 2 is electrically connected to the power supply module 1, and includes a radiation detector 21 and a shielding detector 22. The radiation detector 21 is used to detect the radiation intensity count rate of the radiation source in the current environment, and send the detected radiation intensity to the main control module 3. A shielding block 23 with a uniformly increasing thickness is sleeved on the detection end of the shielding detector 22, which is used to detect the shielding radiation intensity count rate of the radiation source in the same position and detection environment as the radiation detector 21, and send the shielding radiation intensity count rate of the radiation source to the main control module 3; the main control module 3 is electrically connected to the power supply module 1, and includes a data processing module 31 for receiving radiation The radiation intensity count rate and radiation intensity dose rate of the radiation source emitted by the radiation detector 21, the radiation intensity count rate of the radiation source shielding radiation intensity emitted by the shielding detector 22, and the start and stop of the first detection module and the shielding detector 22 are controlled; and the distance of the radiation source relative to the detection module 2 is calculated according to the radiation intensity dose rate p of the radiation source. At the same time, the proportional relationship between the radiation intensity count rate of the radiation source and the radiation intensity dose rate of the radiation source shielding is calculated according to the ray attenuation formula, and the incident thickness and incident angle of the ray passing through the shielding block 23 are judged to determine the position of the radiation source. Finally, according to the azimuth information of the radiation source and the distance information of the radiation source relative to the detection module 2, the position of the radiation source is determined, the radiation source is located, and the radiation source positioning information is sent to the client or the cloud. The power supply module 1 is provided with electric energy by a power supply, and also has a charging circuit for charging the power supply with an external power supply. In this way, the radiation source positioning system used has a radiation detector 21 and a shielding detector 22, which can test the radiation intensity of the suspected lost area of ​​the radiation source at the same position, and obtain the radiation intensity after shielding and the radiation intensity without shielding, so that the incident thickness of the radiation emitted by the radiation source can be judged according to the proportional relationship between the two, and then the direction of the radiation source can be determined. This method determines the shielding thickness by comparing the shielding radiation intensity with the current radiation intensity, and determines the direction of the radiation source according to the direction corresponding to the shielding thickness in the shielding block 23, and the direction is obtained more accurately. The thickness of the shielding block 23 increases evenly and the installation direction is fixed. Therefore, after the radiation enters different directions, the radiation source intensity count rate detected after shielding is different, and then the direction is more accurate. On the premise that the radiation source direction is more accurate, the radiation source positioning obtained by combining the radiation source direction and the distance between the radiation source and the radiation detector 21 is also more accurate. The system used has fewer components and less calculation, and can be widely promoted.

[0026] Furthermore, the ray attenuation formula is as follows: N = N 0 e -ud , where N 0is the radiation intensity count rate of the radiation source, N is the radiation intensity count rate of the radiation source shielding, u is the linear attenuation coefficient of the gamma ray in the shielding block 23, and d is the shielding thickness of the shielding block 23 at the incident point; transforming the ray attenuation formula, we can get: The shielding thickness d corresponding to the thickness position interval position on the shielding block 23 is the incident angle of the ray, and the azimuth indicated by the incident angle is the azimuth of the radiation source. In this way, after adopting the above formula, the specific values ​​detected by the radiation detector 21 and the shielding detector 22 are substituted into the formula to quickly obtain the shielding thickness of the incident ray, thereby determining the incident angle and azimuth.

[0027] Furthermore, it also includes a display alarm module 4, which is electrically connected to the power supply module 1 and is in communication connection with the main control module 3, including a display module 41 and an alarm module 42. The display module 41 is used to display the radiation source positioning information issued by the main control module 3; the main control module 3 is also used to send an alarm message to the alarm module 42 after receiving that the radiation intensity exceeds the alarm threshold; the alarm module 42 is used to receive the alarm message issued by the main control module 3 and alarm through voice or light. In this way, after using the display alarm module 4, it is convenient for operators to perform corresponding operations. After the alarm module 42 alarms, the main control module 3 can control the shielding detector 22 to turn on and perform radiation measurement. In this embodiment, the shielding detector 22 and the radiation detector 21 are both LaBr3 detectors. The main control module 3 also includes a storage module and a communication module. The storage module is used to store the detection data issued by the detection module 2, and the communication module is used to transmit information.

[0028] Further, the shielding block 23 is a lead shielding block 23 or a tungsten shielding block; the radiation detector 21 and the shielding detector 22 are respectively assembled in a protective cover or assembled in a protective shell, and the detection ends are arranged adjacent to each other. In this way, in application, the radiation detector 21 and the shielding detector 22 can be installed as needed.

[0029] like Figure 2-Figure 6 As shown, this embodiment also provides a method for locating a radiation source, including the following steps: S1, preparing two detectors, one of which is a radiation detector 21, and the other is a shielding detector 22 with a shielding block 23 on the detection end; the thickness of the shielding block 23 is uniformly increased, and the outer end surface is spiral; S2, reaching the suspected radiation field area, using the radiation detector 21 and the shielding detector 22 at the same position to detect the radiation intensity count rate N of the radiation source in the current area 0 and the radiation intensity count rate N of the radiation source shielding; S3, calculate the radiation intensity count rate N of the radiation source according to the ray attenuation formula 0The incident thickness and incident angle of the radiation passing through the shielding block 23 are judged according to the proportional relationship between the radiation intensity count rate N of the radiation source shielding, the orientation of the radiation source is determined, and the orientation information of the radiation source is obtained; at the same time, the distance between the radiation source and the radiation detector 21 is calculated according to the measured radiation intensity of the radiation source; S4, according to the orientation information of the radiation source and the distance of the radiation source relative to the radiation detector 21, the position of the radiation source is determined, the first positioning of the radiation source is completed, and the radiation source positioning interval 1 is obtained; S5, repeating S2--S4, completing the second positioning of the radiation source, and obtaining the radiation source positioning interval 2; S6, determining whether the two radiation source positioning intervals overlap, if not, performing multiple tests until there is an overlapping interval; if there is an overlapping interval, the overlapping interval is integrated and the overlapping interval is used as the radiation source positioning interval. In this way, when locating the radiation source, the radiation source orientation is first determined according to the different radiation intensity count rates detected by the two detectors, and then the distance between the detector and the radiation source is calculated in combination with the radiation intensity dose rate of the radiation source detected by the detector, so that the precise position of the radiation source can be determined under the dual indication of orientation and distance. When determining the orientation of the radiation source, the shielding thickness of the radiation entering is calculated according to the ratio of the radiation intensity count rate of the unshielded radiation source and the radiation intensity count rate of the shielded radiation source, and the orientation of the radiation source is determined according to the orientation corresponding to the shielding thickness in the shielding block 23, so that the orientation is obtained more accurately. The thickness of the shielding block 23 increases evenly and the installation orientation is fixed. Therefore, after the radiation enters different orientations, the intensity count rate of the radiation source detected after shielding is different, and the orientation is more accurate. After determining the radiation source positioning interval multiple times, the overlapping part of each positioning interval is used as the radiation source positioning interval, which is more accurate than a one-time determination.

[0030] Furthermore, in order to make the method of rapid location of radioactive sources applicable to a variety of nuclides, it is necessary to make appropriate extensions. 0 e -ud , N and N 0 is the detector measurement data, which can be read directly, e is a constant, u is the shielding coefficient of the shielding body for a certain nuclide. When the nuclide is determined, u is a constant, and d is the thickness of the shielding body corresponding to the radiation source orientation, which is the only variable to be sought. For a specific nuclide, the shielding coefficient u can be found by simply substituting the measured N and N 0 The thickness d can be calculated to determine the direction of the radiation source. The type of nuclide can be determined by using a detector with nuclide identification capability. Different u values ​​can be called according to the type of nuclide to achieve rapid positioning of multiple nuclides. To further improve the positioning accuracy, actual measurement experiments can be conducted to measure the difference between N and N when a specific radiation source is located in the direction of different thicknesses d of the shield. 0 The specific value of N and N 0 The fitting formula for thickness d is directly written into the system main control program, and the system can calculate the thickness d according to the measured N and N0 The value of u can automatically determine the location of the radiation source. This method can reduce the amount of subsequent calculations and make the system more user-friendly. The fitting formula is not much different from the theoretical formula obtained by directly querying the u value. If the conditions are limited, it is also possible to directly use the theoretical formula. In order to verify the accuracy of the fitting formula, the results of multiple actual measurements can be analyzed for errors. The formula can be fine-tuned in the process, and the shielding angle calculation formula obtained is more accurate.

[0031] Furthermore, in S2, when detecting the radiation intensity count rate N of the radiation source 0 When the radiation intensity count rate N of the radiation source is detected, the radiation detector 21 and the shielding detector 22 are installed in the same protective cover for synchronous detection. When installed, the detection end of the radiation detector 21 and the shielding detector 22 are arranged up and down, and the two detection ends are adjacent. 0 When the radiation intensity count rate N of the radiation source shielding is measured, the radiation detector 21 and the shielding detector 22 can also be respectively assembled in a protective shell and tested successively at the same test position. In this way, in the application process, both synchronous measurement and sequential measurement are possible, so that the existing detector can be modified according to the actual situation. Both methods can achieve the radiation intensity count rate N of the radiation source. 0 And the measurement of radiation intensity count rate N of the radiation source shielding. The method of installing two detectors together and detecting synchronously is more convenient and faster.

[0032] When measuring in the field, a tripod can be used to adapt to uneven terrain. A level is placed on top of the tripod to ensure that the instrument can be placed horizontally during measurement.

[0033] The shielding block 23 used in this embodiment is a lead shielding block 23, with a minimum thickness of 2mm and a maximum thickness of 20mm. The thickness increases uniformly in the clockwise direction. A mounting hole is provided in the middle of the shielding block 23, and the shielding block 23 is fixed to the detection end of the shielding detector 22 through the mounting hole. The working principle of the radiation source position measurement device is as follows: the device has two separate detection ends for measuring the radiation intensity of the measured environment; one of the detectors is not shielded and can directly measure the radiation intensity at the location, and a lead shielding block 23 is provided on the detection end of the other detector. The measured radiation intensity is the radiation after the attenuation of the radiation passing through the lead shielding block 23. It can be seen from the ray attenuation formula that the attenuation coefficient of the radiation passing through the material is related to the type and thickness of the material. Since the thickness of the shielding lead increases uniformly, the lead thickness in each direction is different. Therefore, for the gamma rays incident from different directions, the measurement values ​​of the lead shielding detector 22 will be different. By comparing the measurement results of the two detectors and calculating the proportional relationship, the incident angle of the gamma ray can be determined, thereby determining the position of the radiation source.

[0034] Taking the experimental data of azimuth measurement of 137Cs as an example, the count N0 of the unshielded detector 22 is measured to be 105438, and the count N of the lead shielded detector 22 varies with the angle as shown in the following table (the measurement time is uniformly 30s):

[0035]

[0036]

[0037] Substituting N0, N and β, the angle fitting formula is calculated as: β = 183.705*ln(N / N0)-45.468. Substituting the angle fitting formula into the measured result, the angle measurement error is calculated as follows:

[0038] Actual β 0 15 30 45 60 75 Error value -0.86 0.85 0.74 -0.29 -0.12 0.33 Actual β 90 105 120 135 150 165 Error value -0.49 -0.69 0.50 0.61 -0.59 -0.65 Actual β 180 195 210 225 240 255 Error value -0.53 -0.10 -0.39 0.51 -0.90 -0.32 Actual β 270 285 300 315 330 345 Error value -0.80 -0.71 -0.78 -0.37 -0.69 0.63

[0039] The fitting formula was verified by another 137Cs source, N = 298389, N 0 The angle error is as follows (the measurement time is uniformly 30s):

[0040] Angle β 0 15 30 45 60 75 Count N 233862 213891 197211 182409 168165 154280 Error value -0.70 0.69 0.60 -0.05 -0.12 0.70 Actual β 90 105 120 135 150 165 Count N 143116 131832 120892 111239 102985 94548 Error value -0.49 -0.40 0.50 0.79 -0.03 0.66 Actual β 180 195 210 225 240 255 Count N 87504 80636 74311 68257 63294 58236 Error value -0.11 -0.09 -0.09 0.51 -0.61 -0.31 Actual β 270 285 300 315 330 345 Count N 53612 49568 45651 42020 38756 35494 Error value -0.11 -0.70 -0.58 -0.36 -0.50 0.64

[0041] The two measurement results are similar, the error is controllable, and the situation remains unchanged after multiple experiments. Therefore, the fitting formula is suitable for the device to detect the azimuth of the 137Cs radiation source. In this embodiment, the maximum thickness of the lead shielding block 23 is 20 mm, and the angle of the radial line of the thickness is positioned at 0°, and so on. On this basis, the relationship between the radiation source shielding azimuth angle β and the thickness d of the lead shielding block 23 is: β = 20*(d-2).

[0042] In a specific implementation, when the shielding block 23 is made of different materials and the shielding thickness is set differently, the formula for calculating the shielding angle will also be different.

[0043] After the above-mentioned orientation is determined, the orientation will point directly to the radiation source, and the indicated dose rate P is the dose rate of the radiation field generated by the radiation source at the device. According to the dose rate formula at a certain point in the radiation field:

[0044] Where: P is the air kerma rate, i.e., the dose rate, in Gy / h; A is the activity of the point source, in Ci or Bq; L is the distance between the measurement point and the point source, in m; Γ K is the air kerma rate constant.

[0045] When the type of the lost radioactive source is known, the distance between the radioactive source and the equipment at this time can be directly calculated, and combined with the current azimuth pointing, the location of the radioactive source can be inferred. In actual situations, there may be errors in the measured dose rate value and the azimuth measurement value, which will lead to inaccurate positioning results and require data processing. The azimuth measurement angle error may cause the positioning of the radioactive source to be offset at an angle, which is at a certain angle to the indicated direction. This angle is the maximum angle error of the measuring instrument. At this time, the position of the radioactive source should be between the angles of the two lines. Therefore, in order to reduce errors and quickly determine the position of the radioactive source, the radioactive source is positioned twice in succession in this embodiment. After multiple measurements, the range of the radioactive source position is gradually reduced, and the actual position of the radioactive source is within the intersection of all test results. At this time, the positioning is completed and the radioactive source can be recovered. If the contaminated area is large or the terrain on site is complex, consider adding measurement points to improve positioning accuracy.

[0046] When the radiation source is blocked, the measurement result in a certain direction will have a large deviation. At this time, the positioning interval formed by the measurement is very different from other measurement results. The test result of this point should be ignored during positioning, and the obstruction should be avoided and detected again.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A radiation source positioning system, comprising a detection module, a power supply module and a main control module, characterized in that: The detection module is electrically connected to the power supply module, and includes a radiation detector and a shielding detector. The radiation detector is used to detect the radiation intensity in the current environment and send the detected radiation intensity to the main control module. A shielding block with a uniformly increasing thickness is sleeved on the detection end of the shielding detector, which is used to detect the partially shielded radiation intensity at the same position and detection environment of the radiation detector, and send the partially shielded radiation intensity to the main control module. The main control module is electrically connected to the power supply module, and includes a data processing module for receiving original measurement data of radiation intensity at the current position measured by the radiation detector, and original measurement data of radiation intensity at the partially shielded position measured by the shielding detector; The distance of the radiation source relative to the detection module is calculated based on the radiation intensity at the current position. At the same time, the proportional relationship between the unshielded radiation intensity and the partially shielded radiation intensity is calculated according to the ray attenuation formula, and the incident thickness and incident angle of the ray passing through the shielding block are judged to determine the location of the radiation source. Finally, based on the azimuth information of the radiation source and the distance information of the radiation source relative to the detection module, the position of the radiation source is determined, the radiation source is located, and the source positioning information is sent to the client or the cloud.

2. The radiation source positioning system according to claim 1, characterized in that: The ray attenuation formula is as follows: N = N0e -ud , where N0 is the radiation intensity count rate of the radiation source, N is the radiation intensity count rate of the radiation source shielding, u is the linear attenuation coefficient of the gamma ray in the shielding block, and d is the shielding thickness of the shielding block at the incident point; transforming the ray attenuation formula, we can get: The shielding thickness d on the shielding block corresponds to the thickness position interval position, which is the incident angle of the ray. The azimuth indicated by the incident angle is the azimuth of the radiation source.

3. The radiation source positioning system according to claim 1 or 2, characterized in that: It also includes a display alarm module, which is electrically connected to the power supply module and to the main control module, and includes a display module and an alarm module. The display module is used to display the radiation source positioning information issued by the main control module; the main control module is also used to send an alarm message to the alarm module after receiving a radiation dose rate exceeding a preset alarm threshold; the alarm module is used to receive the alarm message issued by the main control module and issue an alarm through voice or light.

4. The radiation source positioning system according to claim 3, characterized in that: The shielding block is a lead shielding block or a tungsten shielding block; the radiation detector and the shielding detector are respectively assembled in a protective cover or a protective shell, and the detection ends are arranged adjacent to each other.

5. A method for locating a radiation source, characterized in that: The method comprises the following steps: S1, preparing two detectors, one of which is a radiation detector, and the other is a shielding detector with a shielding block on the detection end; the thickness of the shielding block is uniformly increased, and the outer end surface is spiral; S2, arriving at the suspected radiation field area, using the radiation detector and the shielding detector at the same position to detect the radiation intensity count rate N0 of the radiation source and the radiation intensity count rate N of the radiation shielding in the current area; S3, using a controller to calculate the proportional relationship between the radiation intensity count rate N0 of the radiation source and the radiation intensity count rate N of the radiation shielding according to the ray attenuation formula to determine the incident thickness and incident angle of the ray passing through the shielding block, determine the position of the radiation source, and obtain the radiation source position information; At the same time, the distance between the radiation source and the radiation detector is calculated according to the measured radiation intensity of the radiation source; S4, according to the orientation information of the radiation source and the distance of the radiation source relative to the radiation detector, the position of the radiation source is determined and the radiation source is located.

6. The method for locating a radiation source according to claim 5, characterized in that: When locating the radiation source, in order to reduce errors, the radiation source positioning is performed twice in succession, wherein the test position during the second radiation source positioning is changed to a new position based on the first test position and then the radiation intensity test of the radiation source is performed; the method of locating the radiation source twice is as described in S2-S4, and the radiation source positioning interval 1 is obtained after the first radiation source positioning, and the radiation source positioning interval 2 is obtained after the second radiation source positioning; after obtaining the radiation source positioning interval 1 and the radiation source positioning interval 2, it is determined whether the two radiation source positioning intervals overlap, if not, it is considered that the radiation source is blocked, and multiple tests are required to eliminate the interference of the blocking; if there is an overlapping interval, the overlapping interval is integrated and the overlapping interval is used as the radiation source positioning interval.

7. The method for locating a radiation source according to claim 5 or 6, characterized in that: In order to make the method of rapid location of radioactive sources applicable to a variety of nuclides, it is necessary to expand it appropriately. For the formula N = N0e -ud , N and N0 are the measurement data of the radiation detector and the shielding detector respectively, which can be read directly, e is a constant, u is the shielding coefficient of the shielding body for a certain nuclide, when the nuclide is determined, u is a constant, d is the thickness of the shielding body corresponding to the orientation of the radiation source, which is the only variable to be sought; for a specific nuclide, the shielding coefficient u can be found, and the thickness d can be calculated by substituting the measured N and N0 to determine the orientation of the radiation source. The type of nuclide can be determined by using a detector with nuclide identification capability, and different u values ​​can be called according to the type of nuclide to achieve rapid positioning of multiple nuclides; in order to further improve the positioning accuracy, the specific values ​​of N and N0 can be measured when a specific radiation source is located in the direction of different thicknesses d of the shielding body through actual measurement experiments, and the fitting formula using N and N0 to represent the thickness d is obtained, which is directly written into the data processing program of the controller, and the controller can automatically determine the orientation of the radiation source according to the measured values ​​of N and N0.

8. The method for locating a radiation source according to claim 7, characterized in that: In S2, when detecting the radiation intensity count rate N0 of the radiation source and the radiation intensity count rate N of the radiation source shielding, the radiation detector and the screen 22 are installed in the same protective cover for synchronous detection. During installation, the detection end of the radiation detector and the shielding detector are arranged up and down, and the two detection ends are adjacent.

9. The method for locating a radiation source according to claim 7, characterized in that: In S2, when detecting the radiation intensity count rate N0 of the radiation source and the radiation intensity count rate N of the radiation shielding, the radiation detector and the shielding detector are tested successively at the same test position.

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