Shielding device for gamma detector

Abstract

The invention belongs to the technical field of nuclear radiation measurement and radiation protection, and relates to a shielding device for a gamma detector, the shielding device comprises a shielding box body, a shielding assembly and a controller, a through ray channel is arranged in the shielding box body, the ray channel comprises an inlet end and an outlet end, the outlet end is used for installing a gamma detector probe, and the controller is connected with the shielding assembly. The shielding assembly comprises a shielding body and a driving unit. The output end of the driving unit is connected with the shielding body. The shielding body comprises a plurality of shielding sections arranged in the direction perpendicular to the connecting line of the inlet end and the outlet end, the shielding capacity of the shielding sections is sequentially reduced, and each shielding section is used for blocking the inlet end. According to the scheme, the position of the shielding body can be automatically adjusted, the counting rate is made to be within the preset counting rate interval, and the method and device are suitable for scenes where gamma ray fluctuation in the environment is large and gamma rays of the to-be-detected sample change.

Description

Technical Field

[0001] This invention belongs to the field of nuclear radiation measurement and radiation protection technology, and relates to a shielding device for a gamma detector. Background Technology

[0002] In high-radiation areas such as nuclear facilities and spent fuel reprocessing plants, quantitative monitoring of gamma radiation is required for radioactive materials in specific containers or locations. Quantitative gamma radiation monitoring refers to the measurement of gamma rays emitted by radioactive nuclides in a specific radiation field or object using a gamma detector, and through energy spectrum analysis, to achieve precise detection of the type of target nuclide and its radioactivity.

[0003] In high-radiation regions, gamma rays are also generated in the environment, resulting in extremely strong gamma background radiation. Direct measurement can easily overwhelm the target's gamma characteristic peak signal, potentially causing significant "dead time" and spectral distortion in the gamma detector due to an excessively high count rate. This leads to difficulties in nuclide identification and inaccurate activity analysis. The count rate, the number of pulses recorded per second by the detector, reflects the gamma photon flux received by the detector. Therefore, a shielding device is needed to block excessively strong gamma rays, ensuring the count rate is within a suitable range for the gamma detector's operation and measurement requirements, thereby improving the accuracy of gamma detector measurements.

[0004] Existing shielding devices typically consist of a shielded enclosure with an internal X-ray channel. One end of the channel houses a gamma detector probe, while the other end is shielded, with the sample to be tested positioned outside the shield. Gamma rays from the sample and the environment are shielded by the shield before exiting through the X-ray channel and being received by the gamma detector probe. The shielded enclosure also shields against ambient gamma rays. Under this shielding effect, the count rate remains within a set range, resulting in more accurate gamma detector measurements.

[0005] However, in nuclear facilities and spent fuel reprocessing plants, real-time gamma-ray monitoring of radioactive materials in specific containers or locations is required. The gamma-ray levels in the environment fluctuate significantly, and the samples being tested also change continuously during processing, causing the count rate detected by the gamma detector to exceed the set range. When the count rate is below the lower limit of the set range, the shielding effect of the shielding device is too strong, resulting in an insufficient effective count rate and inaccurate measurements. When the count rate is above the upper limit of the set range, the shielding effect of the shielding device is insufficient, resulting in an excessively high count rate, which may exceed the range of the gamma detector, distorting the data and even damaging the gamma detector. Summary of the Invention

[0006] The purpose of this invention is to provide a shielding device for gamma detectors, so as to solve the technical problem that existing shielding devices are applicable to only one scenario and cannot adapt to scenarios where gamma ray fluctuations are large and the sample under test changes.

[0007] To achieve the above objectives, the present invention provides a specific technical solution for a shielding device for a gamma detector as follows: A shielding device for a gamma detector includes a shielding housing, a shielding assembly, and a controller. The shielding housing has a through-channel X-ray path, including an inlet and an outlet, with the outlet used to mount the gamma detector probe. The shielding assembly includes a shielding body and a drive unit, with the output of the drive unit connected to the shielding body. The shielding body includes multiple shielding sections arranged perpendicular to the line connecting the inlet and outlet, with the shielding capabilities of the multiple shielding sections decreasing sequentially. Each shielding section is used to block the inlet. The controller is configured to: based on a comparison between the count rate transmitted by the gamma detector and a preset count rate range, control the drive unit to move the shielding body, sequentially blocking the inlet from the shielding section with the strongest shielding capability to the shielding section with the weakest shielding capability, until the count rate falls within the preset count rate range.

[0008] Furthermore, each shielding section includes a first shielding block and a second shielding block arranged along the length of the line connecting the inlet end and the outlet end. The first shielding block is located on the side of the second shielding block away from the inlet end. Along the direction of decreasing shielding capability of the shielding body, the thickness of the first shielding block gradually decreases, and the thickness of the second shielding block gradually increases. The first shielding block is made of a first metallic material with an atomic number of not less than 70, and the second shielding block is made of a second metallic material with an atomic number between 20 and 70.

[0009] Furthermore, there are five first shielding blocks, and the thicknesses of the five first shielding blocks are (95mm-105mm), (56mm-66mm), (41mm-51mm), (26mm-36mm), and (12mm-22mm) respectively; there are five second shielding blocks, and the thicknesses of the five second shielding blocks are (34mm-44mm), (49mm-59mm), (64mm-74mm), (78mm-88mm), and (95mm-105mm) respectively.

[0010] Furthermore, the first metallic material is a tungsten-nickel-copper alloy or lead; the second metallic material is aluminum, copper, or steel.

[0011] Furthermore, the shielding assembly also includes a pad, two first limiting strips, and two second limiting strips; the two first limiting strips are respectively connected to the two side walls in the length direction of the pad, and the two second limiting strips are respectively connected to the two side walls in the width direction of the pad, with both the first and second limiting strips extending upward beyond the pad; a limiting groove is formed between the pad, the two first limiting strips, and the two second limiting strips to limit the first shielding block and the second shielding block; the pad is connected to the output end of the driving unit.

[0012] Furthermore, the drive unit includes a motor and a nut and screw mechanism, the nut and screw mechanism includes a mating nut and a screw, the output shaft of the motor is connected to the screw, and the bottom of the pad is connected to the nut.

[0013] Furthermore, the shielding assembly also includes a baffle and an infrared sensor. The baffle is located on the top of the shielding body, and the infrared sensor is located on the side wall of the shielding box. The infrared sensor is at the same height as the baffle and is used to detect the position of the shielding body.

[0014] Furthermore, the side wall of the shielding enclosure is formed with a mounting groove, which penetrates the side wall of the shielding enclosure along the moving direction of the shielding body; both the shielding body and the driving unit are located on the lower wall surface of the mounting groove.

[0015] Furthermore, the shielding device for the gamma detector also includes a sleeve, one end of which is snapped into the inlet end, and the other end of which is connected to the side wall of the shielding box located at the outlet end; the sleeve is used to accommodate the gamma detector probe; the inner wall of the sleeve and the gamma detector probe are filled with boron-containing polyethylene; and lead is filled between the sleeve and the shielding box.

[0016] Furthermore, the shielding device for the gamma detector also includes a shielding door assembly, which comprises two lead chamber doors, two sliders, a guide rail, an upper baffle, and two lower baffles. The guide rail is arranged parallel to the shielding body, and the two sliders are slidably mounted on the guide rail. The two lead chamber doors are used to close the inlet end of the radiation channel. Each lower baffle connects one lead chamber door and a corresponding slider. A clearance hole is formed on the side of the two lead chamber doors that are close to each other for the gamma detector probe to pass through. The upper baffle is Z-shaped, with one end connected to the side wall of the shielding box and the other end located on the outer side of the upper end of the lead chamber door to limit the lead chamber door.

[0017] The shielding device for a gamma detector according to the present invention has the following advantages: The shielding device for a gamma detector of the present invention comprises multiple shielding sections with progressively decreasing shielding capabilities. During operation, the shielding section with the strongest shielding capability first blocks the inlet of the radiation section. When the count rate is lower than the lower limit of a preset count rate range, the shielding body is moved so that a shielding section with a lower shielding capability blocks the inlet of the radiation section, until the count rate falls within the preset count rate range. This shielding section effectively shields the gamma rays from the sample under test and the environment, achieving optimal gamma ray shielding. This ensures an effective count rate while preventing excessively high count rates that could exceed the gamma detector's range or even damage it. Particularly useful in scenarios where environmental gamma ray levels fluctuate significantly and the gamma ray levels of the sample under test change, the shielding device can automatically adjust the position of the shielding body to block the inlet of the radiation section with the corresponding shielding section, thus achieving shielding against gamma rays from both the environment and the sample under test. Therefore, the shielding device of the present invention is suitable for scenarios where environmental gamma ray levels fluctuate significantly and the gamma ray levels of the sample under test change.

[0018] Furthermore, during each test, the shielding section with the strongest shielding capability is first used to block the entrance end of the radiation section, and then the shielding sections with a lower shielding capability are used to block the entrance end of the radiation section in turn. This can prevent the gamma detector from being distorted or even damaged due to a high count rate. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the shielding device for a gamma detector according to the present invention; Figure 2 This is a schematic diagram of the shielding device for a gamma detector according to the present invention from another perspective. Figure 3 This is a cross-sectional view of the shielding device for a gamma detector according to the present invention; Figure 4 This is a cross-sectional view of the shielding enclosure of the present invention; Figure 5 This is a schematic diagram of the shielding body of the present invention.

[0020] Figure label: 1. Shielding enclosure; 11. X-ray channel; 111. Inlet end; 112. Outlet end; 12. Mounting slot; 2. Gamma detector probe; 3. Shielding assembly; 31. Shielding body; 311. First shielding block; 312. Second shielding block; 32. Pad; 33. First limiting strip; 34. Second limiting strip; 35. Motor; 36. Nut and screw mechanism; 37. Baffle plate; 38. Infrared sensor; 4. Sleeve; 5. Boron-containing polyethylene; 6. Shielding door assembly; 61. Lead chamber door; 62. Slider; 63. Guide rail; 64. Upper baffle; 65. Lower baffle; 7. Lifting ring; 8. Test bench. Detailed Implementation

[0021] The technical solutions of this application will now be described clearly and in detail with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, "multiple" refers to two or more. The terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0022] like Figures 1 to 5 As shown, this invention provides a shielding device for a gamma detector, including a shielding housing 1, a shielding assembly 3, and a controller. The shielding housing 1 has a through-type X-ray channel 11, which includes an inlet end 111 and an outlet end 112. The outlet end 112 is used to mount the gamma detector probe 2. The shielding assembly 3 includes a shield body 31 and a drive unit, with the output end of the drive unit connected to the shield body 31. The sample to be tested is placed outside the shield body 31. The shield body 31 includes multiple shielding sections arranged along a direction perpendicular to the line connecting the inlet end 111 and the outlet end 112. The shielding capabilities of the multiple shielding sections decrease sequentially, and each shielding section is used to block the inlet end 111. The controller is configured to: based on a comparison between the count rate transmitted by the gamma detector and a preset count rate range, control the drive unit to drive the shield body 31 to move, so that the shielding sections with the strongest shielding capability to the shielding sections with the weakest shielding capability sequentially block the inlet end 111 until the count rate is within the preset count rate range.

[0023] In the shielding device for a gamma detector in this embodiment of the invention, firstly, the gamma detector probe 2 is installed at the exit end 112 of the ray channel 11, and the exit end 112 of the ray channel 11 is aligned with the sample to be tested. Then, when the shield 31 is in its initial position, i.e., when the shielding section with the strongest shielding capability blocks the inlet end 111, the gamma rays from the sample to be tested and the environment are shielded by the shielding section and pass through the ray channel 11 to be acquired by the gamma detector. The gamma detector measures the count rate and transmits it to the controller. The controller determines whether the count rate is within the acceptable range. Within the preset count rate range, if the gamma rays are within the preset count rate range, the gamma rays are shielded by the shielding section with the strongest shielding capability, and the measured gamma rays are detected. If the count rate is lower than the lower limit of the preset count rate range, the controller controls the drive unit to move the shield 31, so that the shielding section with a lower shielding capability blocks the position of the inlet end 111. The above steps are repeated until the count rate is within the preset count rate range, at which point the shield 31 stops moving, and the gamma rays are shielded by that shielding section, and the measured gamma rays are detected. After the detection is completed, the shield 31 returns to the initial position.

[0024] The shielding device for a gamma detector of the present invention comprises a shielding body 31 consisting of multiple shielding sections with progressively decreasing shielding capabilities. During operation, the shielding section with the strongest shielding capability first blocks the inlet end 111 of the ray section. When the count rate is less than the lower limit of a preset count rate range, the shielding body is moved so that a shielding section with a lower shielding capability blocks the inlet end 111 of the ray section until the count rate is within the preset count rate range. This shielding section is used to shield the gamma rays in the sample to be tested and the environment, so that the shielding section has the best gamma ray shielding effect. This not only obtains an effective count rate but also prevents the count rate from being too high, exceeding the range of the gamma detector, or even damaging the gamma detector.

[0025] Especially in scenarios where the gamma ray levels in the environment fluctuate significantly and the gamma ray levels of the sample under test change, this shielding device can automatically adjust the position of the shield 31 to block the inlet end 111 of the ray section in the corresponding shielding section, thereby achieving shielding against gamma rays in the environment and the sample under test. Therefore, the shielding device of the present invention is suitable for scenarios where the gamma ray levels in the environment fluctuate significantly and the gamma ray levels of the sample under test change.

[0026] Furthermore, during each test, the shielding section with the strongest shielding capability is first used to block the inlet end 111 of the radiation section, and then the shielding sections with a lower shielding capability are used to block the inlet end 111 of the radiation section in turn. This can prevent the gamma detector from being distorted or even damaged due to a high count rate.

[0027] In some embodiments of the present invention, the preset count rate range is 80 CPS to 120 CPS. CPS represents the electrical pulse signal of gamma rays detected by the gamma detector per second, i.e., the count rate. Of course, the preset count rate range will vary depending on the application scenario; this is just a general reference value. The gamma detector can be a Saint-Gobain 2M2 / 2-X type scintillation gamma detector.

[0028] In some embodiments of the present invention, such as Figure 5As shown, each shielding section includes a first shielding block 311 and a second shielding block 312 arranged along the length of the line connecting the inlet and outlet ends. The first shielding block 311 is located on the side of the second shielding block 312 furthest from the inlet end. Along the direction of decreasing shielding capability of the shielding body 31, the thickness of the first shielding block 311 gradually decreases, while the thickness of the second shielding block 312 gradually increases. The first shielding block 311 is made of a first metallic material with an atomic number of not less than 70, and the second shielding block 312 is made of a second metallic material with an atomic number between 20 and 70. The first metallic material with an atomic number of not less than 70 has exceptionally good shielding capability against gamma rays and also has a high density, typically greater than 9 g / cm³. High density means that more atoms are contained within a unit thickness, further enhancing the shielding effect. For example, the first metallic material can be a tungsten-nickel-copper alloy, a tungsten-nickel-iron alloy, or lead. The second metallic material, with an atomic number between 20 and 70, has a suitable atomic number and can effectively absorb the low-energy scattered gamma rays generated after being shielded by the first shielding block 311, thus playing a role in "purifying" the energy spectrum. For example, the second metallic material can be aluminum, copper, or steel.

[0029] In this embodiment, the thickest first shielding block is the shielding section with the strongest shielding capability, the thickest second shielding block is the shielding section with the weakest shielding capability, and the shielding capability of the remaining second shielding blocks superimposed with the corresponding first shielding blocks is between the two. Gamma rays are received by the gamma detector after being shielded sequentially by the first shielding block 311 and the second shielding block 312. The first shielding block 311 is made of a first metallic material because it has high density and a high atomic number, enabling efficient attenuation of medium- and high-energy gamma rays, thus providing strong shielding capability with a relatively thinner physical thickness. Simultaneously, this material possesses good mechanical strength and machinability, making it suitable for manufacturing components requiring precise movement. The second shielding block 312 is made of a second metallic material because it has a moderate atomic number, effectively absorbing the low-energy scattered gamma rays generated after being shielded by the first shielding block 311, thus playing a role in "purifying" the energy spectrum, while also providing reliable support for the first shielding block 311. This embodiment achieves variations in shielding capability by changing the thickness of the first and second shielding blocks. Furthermore, the first and second shielding blocks 311 and 312, made of different materials, can achieve efficient attenuation of gamma rays and play a spectral "purification" role for low-energy scattered gamma rays.

[0030] In some embodiments of the present invention, such as Figure 5As shown, there are five first shielding blocks 311, namely shielding block one, shielding block two, shielding block three, shielding block four, and shielding block five, with thicknesses of (95mm-105mm), (56mm-66mm), (41mm-51mm), (26mm-36mm), and (12mm-22mm), respectively. There are also five second shielding blocks 312, namely shielding block six, shielding block seven, shielding block eight, shielding block nine, and shielding block ten, with thicknesses of (34mm-44mm), (49mm-59mm), (64mm-74mm), (78mm-88mm), and (95mm-105mm), respectively. Shielding block two is joined with shielding block six, shielding block three with shielding block seven, shielding block four with shielding block eight, and shielding block five with shielding block nine, and the thickness of each shielding segment after joining is equal. Shielding block one and shielding block ten each form a corresponding shielding section, with shielding block one being the strongest shielding section and shielding block ten being the weakest. The shielding body 31, formed by splicing the first shielding block 311 and the corresponding second shielding block 312, is a cuboid with a total thickness of 100mm, a height of 80mm, and a length of 400mm. Shielding blocks one, two, three, four, and five are integrally formed in a stepped shape. Shielding blocks six, seven, eight, nine, and ten are also integrally formed in a stepped shape.

[0031] In this embodiment, shielding block one is the shielding section with the strongest shielding capability, which can attenuate the gamma rays generated by cesium by approximately 10. 5 The shielding section formed by the splicing of shielding block two and shielding block six can attenuate gamma rays generated by cesium by approximately 10 times. 4 The shielding section formed by the combination of shielding block three and shielding block seven can attenuate gamma rays generated by cesium by approximately 10 times. 3 The shielding section formed by the splicing of shielding block four and shielding block eight can attenuate gamma rays generated by cesium by approximately 10 times. 2 The shielding section formed by the splicing of shielding block five and shielding block nine can attenuate gamma rays generated by cesium by approximately 10 times. 1 The shielding block 10 is the weakest shielding section, attenuating gamma rays generated by cesium by approximately three times. This embodiment achieves stepped shielding of gamma rays by setting six shielding sections, resulting in a wider shielding coverage and meeting the shielding requirements of most application scenarios.

[0032] In some embodiments of the present invention, such as Figure 1 and Figure 5As shown, the shielding assembly 3 also includes a pad 32, two first limiting strips 33, and two second limiting strips 34. The two first limiting strips 33 are respectively connected to the two side walls along the length direction of the pad 32, and the two second limiting strips 34 are respectively connected to the two side walls along the width direction of the pad 32. Both the first limiting strips 33 and the second limiting strips 34 extend upwards beyond the pad 32. A limiting groove is formed between the pad 32, the two first limiting strips 33, and the two second limiting strips 34 to limit the first shielding block 311 and the second shielding block 312. The pad 32 is connected to the output terminal of the drive unit.

[0033] In this embodiment, during the assembly of the shielding body 31, the first shielding block 311 and the second shielding block 312 are spliced ​​together and placed on top of the pad 32. Then, two first limiting strips 33 and two second limiting strips 34 are respectively connected to the side wall of the pad 32, so that the first shielding block 311 and the second shielding block 312 are clamped and limited. In this embodiment, the assembly of the first shielding block 311 and the second shielding block 312 is achieved through the pad 32, the two first limiting strips 33 and the two second limiting strips 34, forming the shielding body 31. The output end of the driving unit drives the pad 32 to move, thereby driving the shielding body 31 to move.

[0034] In some embodiments of the present invention, such as Figure 1 As shown, the drive unit includes a motor 35 and a nut and screw mechanism 36. The nut and screw mechanism 36 includes a mating nut and a screw. The output shaft of the motor 35 is connected to the screw, and the bottom of the pad 32 is connected to the nut. The motor 35 can be a servo motor or a stepper motor.

[0035] In this embodiment, the rotation of motor 35 drives the lead screw to rotate synchronously, causing the nut to move along the length of the lead screw, thereby driving the pad 32 and the shield 31 to move synchronously. Of course, other drive units can also be used, such as gear and rack mechanisms, cylinders, and linear motor 35.

[0036] In some embodiments of the present invention, such as Figure 1 and Figure 5 As shown, the shielding assembly 3 also includes a baffle 37 and an infrared sensor 38. The baffle 37 is located on the top of the shielding body 31, and the infrared sensor 38 is located on the side wall of the shielding enclosure 1. The infrared sensor 38 is at the same height as the baffle 37 and is used to detect the position of the shielding body 31.

[0037] Specifically, four infrared sensors 38 are provided, arranged sequentially along the movement direction of the shield 31. The four positions of the infrared sensors 38 are, in order, the negative limit position, the zero point position, the calibration position, and the positive limit position, with the negative limit position located at the end of the shielding section where the shielding capability decreases. Two baffles 37 are provided, arranged sequentially from the end of the shielding section with the lowest shielding capability to the other end as baffle one and baffle two. When the shield 31 moves to the zero point position corresponding to baffle one, the shielding section with the strongest shielding capability blocks the inlet end 111, and the position of the shield 31 at this time is the initial position in the above embodiment. When the shield 31 moves to the calibration position corresponding to baffle two, the controller controls the drive unit to drive the shield 31 back to the initial position, that is, the zero point position corresponding to baffle one. The negative limit position and the positive limit position are set to prevent the infrared sensors 38 at the zero point position and the calibration position from failing. When baffle one corresponds to the negative limit position or baffle two corresponds to the positive limit position, the controller controls the drive unit to drive the shield 31 back to the initial position. The infrared sensor 38 adopts the ZJF78-SX672-NT type through-beam photoelectric sensor.

[0038] In this embodiment, the infrared sensor 38 and the baffle 37 are used together. During the test, the shield 31 always starts to move from the initial position. By controlling the displacement of the shield 31, different shielding sections are controlled to block the inlet end 111. When the shield 31 moves to the corresponding correction position of the baffle, the shield 31 is controlled to return to the initial position for the next test.

[0039] In some embodiments of the present invention, such as Figures 1 to 4 As shown, a mounting groove 12 is formed on the side wall of the shielding enclosure 1, and the mounting groove 12 penetrates the side wall of the shielding enclosure 1 along the moving direction of the shielding body 31. The shielding body 31 and the drive unit are both located on the lower wall surface of the mounting groove 12.

[0040] In this embodiment, the shield 31 and the drive unit are accommodated by setting the mounting slot 12, so that the shield 31 and the drive unit do not protrude outward, which not only plays a protective role, but also makes it more aesthetically pleasing.

[0041] In some embodiments of the present invention, such as Figure 3 As shown, the shielding device for the gamma detector also includes a sleeve 4. One end of the sleeve 4 is snapped into the inlet end 111, and the other end of the sleeve 4 is connected to the inner wall of the outlet end 112. The other end of the sleeve 4 has a flange, which is connected to the inner wall via a flange. The sleeve 4 is used to accommodate the gamma detector probe 2. The space between the inner wall of the sleeve 4 and the gamma detector probe 2 is filled with boron-containing polyethylene 5. The space between the sleeve 4 and the shielding housing 1 is filled with lead.

[0042] In this embodiment, the sleeve 4 provides installation space for the gamma detector probe 2 and is used to form a lead-filled space in conjunction with the shielding box 1. During the propagation of the gamma rays of the sample under test within the sleeve 4, gamma rays in the environment can be shielded by the lead between the sleeve 4 and the shielding box 1, while neutrons and other particles can be shielded by the boron-containing polyethylene 5, thereby achieving a good shielding effect against gamma rays in the environment.

[0043] In some embodiments of the present invention, such as Figures 1 to 3 As shown, the shielding device for the gamma detector also includes a shielding door assembly 6, which includes two lead chamber doors 61, two sliders 62, a guide rail 63, an upper baffle 64, and two lower baffles 65. The guide rail 63 is arranged parallel to the shielding body 31, and the two sliders 62 are slidably mounted on the guide rail 63. The two lead chamber doors 61 are used to close the inlet end 111 of the X-ray channel 11. Each lower baffle 65 connects a lead chamber door 61 and a corresponding slider 62. A clearance hole is formed on the side of the two lead chamber doors 61 that is close to each other, for the gamma detector probe 2 to pass through. The upper baffle 64 is Z-shaped, with one end connected to the side wall of the shielding box 1 and the other end located on the outer side of the upper end of the lead chamber door 61 to limit the lead chamber door 61.

[0044] In this embodiment, the two lead chamber doors 61 are manually pulled to open them to the sides for installing the gamma detector probe 2 or for maintenance. During testing, the two lead chamber doors 61 are pushed together to close the inlet end 111 and prevent gamma ray leakage.

[0045] In some embodiments of the present invention, such as Figures 1 to 4 As shown, the top of the shielding box 1 is equipped with a lifting ring 7. Since the shielding box 1 is filled with lead and is relatively heavy, it can be lifted by fixing the lifting ring 7 with a lifting device, so that the shielding box 1 can be lifted onto the test bench 8 to provide support.

[0046] In some embodiments of the present invention, the walls of the shielding box 1 are welded from 304 stainless steel with a thickness of 10mm, and after the shielding box 1 is lifted to the test bench 8, it is fixed to the test bench 8 with screws.

[0047] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A shielding device for a gamma detector, comprising a shielding box, a through radiation channel being formed in the shielding box, the radiation channel comprising an inlet end and an outlet end, the outlet end being configured to mount a gamma detector probe, characterized in that, The shielding device further comprises a shielding assembly and a controller, the shielding assembly comprises a shielding body and a driving unit, and an output end of the driving unit is connected to the shielding body; the shielding body comprises a plurality of shielding sections arranged along a direction perpendicular to a line connecting the inlet end and the outlet end, and shielding capabilities of the plurality of shielding sections decrease in turn, each of the shielding sections being used for plugging the inlet end; and the controller is configured to: according to a comparison result of the count rate transmitted by the gamma detector and a pre-designed count rate interval, control the driving unit to drive the shielding body to move, so that the shielding sections with the strongest shielding capability to the weakest shielding capability plug the inlet end in turn, until the count rate is located in the pre-designed count rate interval.

2. The shielding device for a gamma detector according to claim 1, characterized in that, Each of the shielding sections comprises a first shielding block and a second shielding block arranged along a length direction of the line connecting the inlet end and the outlet end, the first shielding block is located on a side of the second shielding block away from the inlet end; along a direction in which the shielding capability of the shielding body decreases, the thickness of the first shielding block gradually decreases, and the thickness of the second shielding block gradually increases; the first shielding block is made of a first metal material with an atomic number not less than 70, and the second shielding block is made of a second metal material with an atomic number between 20 and 70.

3. The shielding device for a gamma detector according to claim 2, characterized in that, The first shielding block has five first shielding blocks, and the thicknesses of the five first shielding blocks are (95mm-105mm), (56mm-66mm), (41mm-51mm), (26mm-36mm) and (12mm-22mm) in turn; the second shielding block has five second shielding blocks, and the thicknesses of the five second shielding blocks are (34mm-44mm), (49mm-59mm), (64mm-74mm), (78mm-88mm) and (95mm-105mm) in turn.

4. The shielding device for a gamma detector according to claim 2, characterized in that, The first metal material is tungsten-nickel-copper alloy or lead; and the second metal material is aluminum, copper or steel.

5. The shielding device for a gamma detector according to claim 2, characterized in that, The shielding assembly further comprises a base plate, two first limiting strips and two second limiting strips; the two first limiting strips are respectively connected to two side walls in a length direction of the base plate, and the two second limiting strips are respectively connected to two side walls in a width direction of the base plate, and the first limiting strips and the second limiting strips all upwardly exceed the base plate; a limiting groove is formed between the base plate, the two first limiting strips and the two second limiting strips, and is used for limiting the first shielding blocks and the second shielding blocks; and the base plate is connected to an output end of the driving unit.

6. The shielding device for a gamma detector according to claim 5, characterized in that, The driving unit comprises a motor and a nut-screw rod mechanism, the nut-screw rod mechanism comprises a nut and a screw rod matched with each other, an output shaft of the motor is connected to the screw rod, and a bottom of the base plate is connected to the nut.

7. The shielding device for a gamma detector according to claim 1, characterized in that, The shielding assembly further comprises a baffle and an infrared sensor, the baffle is arranged at a top of the shielding body, and the infrared sensor is arranged at a side wall of the shielding box body; the infrared sensor is at a same height as the baffle, and is used for detecting a position of the shielding body.

8. The shielding device for a gamma detector according to claim 1, characterized in that, The side wall of the shielding box is formed with a mounting groove which penetrates the side wall of the shielding box along the moving direction of the shielding body; the shielding body and the driving unit are arranged at the lower wall of the mounting groove.

9. The shielding device for a gamma detector according to claim 1, characterized in that, The shielding door assembly comprises two lead chamber doors, two sliding blocks, a guide rail, an upper baffle and two lower baffles; the guide rail is arranged along the direction parallel to the shielding body, and the two sliding blocks are slidingly arranged on the guide rail; the two lead chamber doors are used for closing the inlet of the radiation channel; each lower baffle is connected with one lead chamber door and the corresponding sliding block; the side of the two lead chamber doors close to each other is formed with a gap for the gamma detector probe to pass through; the upper baffle is Z-shaped, one end of the upper baffle is connected with the side wall of the shielding box, and the other end is located outside the upper end of the lead chamber door to limit the lead chamber door.

10. The shielding device for a gamma detector of claim 1, wherein, The shielding door assembly comprises two lead chamber doors, two sliding blocks, a guide rail, an upper baffle and two lower baffles; the guide rail is arranged along the direction parallel to the shielding body, and the two sliding blocks are slidingly arranged on the guide rail; the two lead chamber doors are used for closing the inlet of the radiation channel; each lower baffle is connected with one lead chamber door and the corresponding sliding block; the side of the two lead chamber doors close to each other is formed with a gap for the gamma detector probe to pass through; the upper baffle is Z-shaped, one end of the upper baffle is connected with the side wall of the shielding box, and the other end is located outside the upper end of the lead chamber door to limit the lead chamber door.

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