A plutonium-bearing material measurement device

Abstract

This invention discloses a plutonium-containing material measuring device, relating to the technical field of radioactive element measuring devices. The device includes a measuring chamber, a lower cover assembly, and an automatic feeding structure. A gamma detector is installed above the measuring chamber, and a neutron detector is installed inside. The automatic feeding structure includes a horizontal transmission mechanism and a synchronous lifting mechanism. The synchronous lifting mechanism is a symmetrical structure driven by a single power source. The lower cover assembly, which carries the material to be measured, is placed on the horizontal transmission mechanism and can be conveyed horizontally to the lifting position. The synchronous lifting mechanism then conveys the lower cover assembly along with the material to be measured vertically into the upper measuring chamber, and the lower cover assembly seals the bottom of the measuring chamber, thus forming a closed measuring space. The device provided by this invention can simultaneously perform neutron and gamma measurements on materials, reducing measurement time, minimizing transport time, reducing radiation hazards to personnel, reducing equipment size, and increasing measurement accuracy.

Description

Technical Field

[0001] This invention belongs to the technical field of radioactive element measuring devices, specifically relating to a measuring device for plutonium-containing materials. Background Technology

[0002] Small amounts of plutonium-containing materials are generated during scientific research experiments and production processes at nuclear facilities. These materials may include residual plutonium crucibles, molten salt slag, plutonium-containing filter screens, wiping materials, spent salt, and so on. Measuring the plutonium content in these materials can provide data support for nuclear material balance calculations and provide a basis for improving production processes.

[0003] When measuring plutonium-containing materials using the neutron coincidence measurement method, the total plutonium content in the material is calculated using the formula for calculating the total plutonium content.

[0004] Pu 总量 The calculation formula is:

[0005]

[0006] In the above formula: 240 Pu eff Defined as the production of diploid isotopes of all Pu in a material equivalent to 240 The coincidence neutron count rate D produced by Pu is:

[0007] 240 Pu eff = 2.52( 238 Pu) +( 240 Pu )+ 1.68( 242 Pu)

[0008] In other words, 1g 238 The D produced by Pu is equivalent to 2.52 g 240 D produced by Pu, 1g 242 The D produced by Pu is equivalent to 1.68 g 240 D produced by Pu.

[0009] In the formula: effective 240 Pu factor F 240eff = f 238 f 240 f 242 It represents the abundance of the corresponding Pu isotope in the sample.

[0010] According to the formula for calculating total plutonium, in order to accurately measure the plutonium content in a material, it is necessary to know the plutonium isotope abundance and effective plutonium content in the material. 240 The amount of Pu is so high that when measuring materials, it is necessary to measure the abundance of the material and the neutron information.

[0011] Currently, the measurement of similar materials both domestically and internationally mainly employs separate neutron and gamma measurements. During data analysis, plutonium isotope abundance information and neutron measurement data are manually input into analysis software to calculate the total plutonium content. These devices are large, require ample space, and involve two measurements with intermediate transport, increasing the risk of radiation exposure for personnel. Furthermore, analyzing the data twice results in lengthy measurement times. Summary of the Invention

[0012] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a plutonium-containing material detection device. This device can simultaneously measure neutrons and gamma rays in materials, reduce measurement time, reduce the transfer process, reduce radiation hazards to personnel, reduce equipment size, and increase measurement accuracy.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] A plutonium-containing material measuring device includes a measuring chamber, a lower cover assembly, and an automatic feeding structure. A gamma detector is installed above the measuring chamber, and a neutron detector is installed inside the chamber to achieve simultaneous gamma and neutron measurements of the material to be measured.

[0015] The automatic feeding structure is used to transport the material to be measured to the measuring chamber for measurement. It includes a horizontal transmission mechanism and a synchronous lifting mechanism. The synchronous lifting mechanism is a symmetrical structure and is driven by a single power source. The power is precisely distributed and synchronously transmitted to the lifting execution points on both sides through the transmission of the gearbox and the lead screw pair.

[0016] The lower cover assembly is used to carry the material to be tested and is placed on the horizontal transmission mechanism. The horizontal transmission mechanism conveys the lower cover assembly and the material to be tested horizontally to the lifting position. The synchronous lifting mechanism conveys the lower cover assembly and the material to be tested vertically to the measuring chamber above and seals the bottom of the measuring chamber, thereby forming a closed measuring space.

[0017] Furthermore, in the plutonium-containing material measuring device described above, the synchronous lifting mechanism includes a servo drive motor. The output end of the servo drive motor is connected to a first gearbox. The first gearbox has two output shafts, which are respectively connected to a first transmission shaft and a third transmission shaft. The ends of the first and third transmission shafts are respectively connected to a second and a fourth gearbox, and the output shafts of the second and fourth gearboxes are respectively connected to the second and fourth transmission shafts.

[0018] The ends of the second and fourth transmission shafts are respectively connected to the third and fifth gearboxes. The output shafts of the third and fifth gearboxes are respectively connected to the input shafts of the first and second lead screw pairs. The nuts of the first and second lead screw pairs are respectively fixed with a first lifting plate and a second lifting plate. Under the drive of the servo drive motor, the first and second lifting plates can move up and down synchronously.

[0019] Furthermore, in the plutonium-containing material measuring device described above, the output shaft of the servo drive motor is arranged vertically upward and coaxially connected with the input shaft of the first gearbox; the two output shafts of the first gearbox are 180 degrees symmetrical and arranged horizontally radially outward.

[0020] Furthermore, in the plutonium-containing material measuring device described above, the first and third drive shafts are arranged horizontally and collinearly opposite each other, extending in opposite directions; the input shafts of the second and fourth gearboxes are horizontal, and their output shafts are arranged horizontally in the same direction and perpendicular to the corresponding input shafts.

[0021] Furthermore, in the plutonium-containing material measuring device described above, the input shaft of the third gearbox is horizontally coaxially connected to the second transmission shaft, the input shaft of the fifth gearbox is horizontally coaxially connected to the fourth transmission shaft, and the output shafts of the third and fifth gearboxes are vertically downward.

[0022] Furthermore, in the plutonium-containing material measuring device described above, the lower cover assembly is cylindrical in shape and includes, from bottom to top, a barrel-shaped mounting plate, a reflective layer, a shielding layer, a moderating layer, and a tray cover, on which the material to be measured is placed.

[0023] Furthermore, in the plutonium-containing material measuring device described above, the moderating layer is made of polyethylene, the shielding layer is made of cadmium sheet, and the reflective layer is made of graphite.

[0024] Furthermore, in the plutonium-containing material measuring device described above, the measuring chamber is a hollow cylindrical structure, and the neutron detector is a multi-column structure, which is evenly distributed in multiple rings along the circumference of the measuring chamber.

[0025] Compared with the prior art, the plutonium-containing material measuring device provided by the present invention has the following beneficial effects:

[0026] 1) Without damaging the neutron multiplicity measurement device, by setting up a gamma detector above the measurement chamber and neutron detectors around the measurement chamber, and adding an automatic feeding structure, it is possible to simultaneously measure plutonium-containing materials with neutrons and gammas. This reduces measurement time and transportation process, reduces radiation hazards to personnel, reduces equipment size, and increases measurement accuracy.

[0027] 2) The neutron detectors are evenly distributed around the measurement chamber, which can reduce the corresponding spatial position differences during neutron measurement and improve measurement efficiency and accuracy.

[0028] 3) The measuring chamber is made of high-density polyethylene, which can slow down neutrons, increase the reaction cross section, and improve detection efficiency;

[0029] 4) In the synchronous lifting mechanism, the transmission between the gearbox and the lead screw pair enables the synchronous lifting mechanism to achieve synchronous up and down lifting of the two lifting plates using only one drive motor, ensuring the consistency of the lifting plate lifting and the lifting process without jamming.

[0030] 5) The lower cover assembly can be moved to the measurement chamber through the horizontal transmission mechanism and the synchronous lifting mechanism, and the measurement chamber is sealed to form a closed space. The closed measurement chamber can effectively reduce environmental interference and improve detection efficiency.

[0031] 6) The design of the lower cover assembly can shield external nuclear radiation from interfering with the measurement, while preventing internal nuclear radiation from polluting the environment;

[0032] 7) Both the neutron detector and the gamma detector are electrically connected to the control system, and there is only one control system, which reduces the manufacturing cost of the equipment. Attached Figure Description

[0033] To further illustrate the above and other advantages and features of this application, the specific embodiments of this application will be described in more detail below with reference to the accompanying drawings. The accompanying drawings, together with the following detailed description, are included in and form a part of this specification. It should be understood that these drawings only depict typical examples of this application and should not be considered as limiting the scope of this application.

[0034] Figure 1 This is a schematic diagram of the overall structure of a plutonium-containing material detection device provided in a specific embodiment of the present invention;

[0035] Figure 2 for Figure 1 A schematic diagram of the synchronous lifting mechanism;

[0036] Figure 3 for Figure 1 Cross-sectional view of the lower cover assembly;

[0037] Figure 4 for Figure 1 Structural schematic diagram of the device;

[0038] Figure 5 for Figure 1 Cross-sectional view of the central measuring chamber;

[0039] In the diagram, 1-Horizontal transmission mechanism, 2-Measuring chamber, 3-Synchronous lifting mechanism, 3.1-Servo drive motor, 3.2-First gearbox, 3.3-Second gearbox, 3.4-Third gearbox, 3.5-Fourth gearbox, 3.6-Fifth gearbox, 3.7-First drive shaft, 3.8-Second drive shaft, 3.9-Third drive shaft, 3.10-Fourth drive shaft, 3.11-First lead screw pair, 3.12-Second lead screw pair, 3.13-First lifting plate, 3.14-Second lifting plate, 4-Lower cover assembly, 4.1-Barrel-shaped mounting plate, 4.2-Moderates layer, 4.3-Shielding layer, 4.4-Reflective layer, 4.5-Tray cover, 5-Gamma detector, 6-Neutron detector. Detailed Implementation

[0040] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0041] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0042] The embodiments or examples disclosed below are used to implement this application. To simplify the disclosure of this application, the components and methods of specific examples are described below. Of course, they are merely examples and are not intended to limit this application.

[0043] This measuring device uses a gamma detector to measure plutonium-containing materials and uses gamma spectroscopy to analyze the isotope abundance. It also uses a neutron detector to measure neutrons and uses neutron analysis to obtain neutron information of plutonium-containing materials. Combined with the isotope abundance, the plutonium content in the material can be obtained.

[0044] In neutron analysis of materials, neutron multiplicity is widely used due to its advantages of short measurement time, high accuracy, and the fact that it does not require prior knowledge of the sample medium or pre-calibration with standard samples. When using neutron multiplicity analysis for neutron measurement data analysis, the measuring device should meet the following conditions: ① cavity structure; ② high detection efficiency, generally greater than 30% is preferred; ③ neutron detectors are uniformly distributed around the measurement chamber, with small spatial response differences. This ensures that its detection efficiency is as independent of spatial location and neutron energy spectrum as possible, exhibiting a flat spatial and energy response to satisfy the basic assumptions of the "point model".

[0045] Figure 1 The diagram illustrates the overall structure of a plutonium-containing material detection device according to a specific embodiment of the present invention. The device includes: a horizontal transmission mechanism 1, a measuring chamber 2, a synchronous lifting mechanism 3, a lower cover assembly 4, a gamma detector 5, a neutron detector 6, and a mounting bracket. The horizontal transmission mechanism 1 and the synchronous lifting mechanism 3 together constitute an automatic feeding structure. The lower cover assembly 4 is placed on the horizontal transmission mechanism 1, and the material to be tested is placed on the lower cover assembly 4. The horizontal transmission mechanism 1 transports the lower cover assembly 4 along with the material to be tested horizontally to the lifting position. The synchronous lifting mechanism 3 is fixed to the mounting bracket and transports the lower cover assembly 4 along with the material to be tested vertically into the upper measuring chamber 2. The lower cover assembly 4 then seals the bottom of the measuring chamber 2, forming a closed measuring space. The measuring chamber 2 is equipped with a gamma detector 5 and a neutron detector 6 for simultaneous gamma and neutron measurements of the material to be tested.

[0046] like Figure 2 As shown, the synchronous lifting mechanism 3 is used to realize the lifting motion of the lower cover assembly 4 and the material to be tested. Its core lies in being driven by a single power source, through the transmission of a gearbox and a lead screw pair, to precisely distribute and synchronously transmit power to the lifting execution points on both sides. Specifically, the synchronous lifting mechanism 3 includes a high-precision servo drive motor 3.1, which serves as the sole power source for the synchronous lifting mechanism 3. Its output shaft is vertically connected to the input shaft of the first gearbox 3.2. The center line of the first gearbox 3.2 is coaxial with the center line of the output shaft of the servo drive motor 3.1 to achieve compact vertical power transmission. The first gearbox 3.2 has two output shafts in the horizontal direction. These two output shafts are arranged radially outward in a 180-degree symmetrical manner on the housing of the first gearbox 3.2, that is, their axes are located in the same horizontal plane, in opposite directions, and both perpendicular to the vertical output shaft of the servo drive motor 3.1, thereby achieving deceleration and converting the vertical rotational motion of the servo drive motor 3.1 into horizontal rotational motion. These two output shafts are connected to the first drive shaft 3.7 and the third drive shaft 3.9 respectively. The two drive shafts are therefore collinear and horizontally opposed, extending in opposite directions.

[0047] The end of the first drive shaft 3.7 is connected to the second gearbox 3.3. The input shaft of the second gearbox 3.3 is horizontally coaxially connected to the first drive shaft 3.7, while its output shaft is horizontal and perpendicular to its input shaft. The output shaft is connected to the second drive shaft 3.8, thereby achieving a 90-degree turn in horizontal rotation. Similarly, the end of the third drive shaft 3.9 is connected to the fourth gearbox 3.5. The input shaft of the fourth gearbox 3.5 is horizontally coaxially connected to the third drive shaft 3.9, while its output shaft is horizontal and perpendicular to its input shaft. The output shaft is connected to the fourth drive shaft 3.10.

[0048] The end of the second drive shaft 3.8 is connected to the third gearbox 3.4. The input shaft of the third gearbox 3.4 is horizontally coaxially connected to the second drive shaft 3.8, while its output shaft is vertically downward, thus realizing the conversion of horizontal rotational motion into vertical rotational motion. Similarly, the end of the fourth drive shaft 3.10 is connected to the fifth gearbox 3.6. The input shaft of the fifth gearbox 3.6 is horizontally coaxially connected to the fourth drive shaft 3.10, while its output shaft is vertically downward.

[0049] The output shaft of the third gearbox 3.4 is connected to the input shaft of the first lead screw pair 3.11, and the output shaft of the fifth gearbox 3.6 is connected to the input shaft of the second lead screw pair 3.12. A horizontally arranged first lifting plate 3.13 is fixed on the first lead screw pair 3.11; symmetrically, a horizontally arranged second lifting plate 3.14 is fixed on the second lead screw pair 3.12. Driven by the first lead screw pair 3.11 and the second lead screw pair 3.12, the first lifting plate 3.13 and the second lifting plate 3.14 can move synchronously up and down.

[0050] During operation, the servo drive motor 3.1 rotates, which drives the first transmission shaft 3.7 and the third transmission shaft 3.9 to rotate synchronously via the first gearbox 3.2; the first transmission shaft 3.7 drives the second transmission shaft 3.8 to rotate via the second gearbox 3.3, while the third transmission shaft 3.9 drives the fourth transmission shaft 3.10 to rotate via the fourth gearbox 3.5; the second transmission shaft 3.8 drives the first lead screw pair 3.11 to rotate via the third gearbox 3.4, while the fourth transmission shaft 3.10 drives the second lead screw pair 3.12 to rotate via the fifth gearbox 3.6; the first lead screw pair 3.11 drives the first lifting plate 3.13 to move, while the second lead screw pair 3.12 drives the second lifting plate 3.14 to move, thus achieving synchronous movement of the first lifting plate 3.13 and the second lifting plate 3.14. In this synchronous lifting mechanism 3, the transmission between the gearbox and the lead screw pair enables the synchronous lifting mechanism 3 to achieve synchronous up and down lifting of the two lifting plates using only one drive motor 3.1, ensuring the consistency of the lifting plate lifting and the lifting process without jamming.

[0051] like Figure 3As shown, the lower cover assembly 4, from bottom to top, includes a barrel-shaped mounting plate 4.1, a reflective layer 4.4, a shielding layer 4.3, a moderating layer 4.2, and a tray cover 4.5. In some preferred embodiments, the moderating layer 4.2 is made of polyethylene, the shielding layer 4.3 is made of cadmium sheet, and the reflective layer 4.4 is made of graphite. The lower cover assembly 4 allows for the enclosure of the measurement chamber 2 during measurement, thereby reducing environmental interference and improving the accuracy of the measurement results. The tray cover 4.5 can be used as both a cover and a tray for holding the material to be measured.

[0052] like Figure 5 As shown, the measuring chamber 2 is used to simultaneously perform neutron and gamma measurements on plutonium-containing materials. Specifically, the measuring chamber 2 has a hollow cylindrical structure. A gamma detector 5 is installed above the measuring chamber 2 for gamma measurements of the plutonium-containing materials; multiple neutron detectors 6 are installed inside the measuring chamber 2 for neutron measurements of the plutonium-containing materials. The neutron detectors 6 are multiple columnar bodies, evenly distributed around the perimeter of the measuring chamber 2. During neutron measurements, this arrangement reduces spatial differences and improves measurement efficiency and accuracy.

[0053] Figure 4 This is a schematic diagram illustrating the working principle of the device. The workflow for detecting plutonium-containing materials using this device is as follows:

[0054] Step 1: Before the equipment is running, confirm that the lower cover assembly 4 is located at the beginning of the horizontal transmission mechanism 1, and place the material to be tested onto the lower cover assembly 4.

[0055] Step 2: When the equipment is running, the servo motor M1 of the horizontal transmission mechanism 1 starts to rotate, and the material to be tested moves along the horizontal transmission mechanism 1. When the servo motor M1 rotates for a set number of pulses, it stops, and the material to be tested moves to the lifting position.

[0056] Step 3: The servo motor M2 of the synchronous lifting mechanism 3 starts to rotate, and the synchronous lifting mechanism 3 drives the material to be tested to move upward. When the servo motor M2 rotates for a set number of pulses, it stops and the material to be tested enters the measuring chamber 2. At this time, the lower cover assembly 4 and the measuring chamber 2 form a closed measuring space, which effectively reduces environmental interference and improves the accuracy of the measurement data.

[0057] Step 4: Begin neutron and gamma measurements and transmit the measurement data to the control system.

[0058] Step 5: After the measurement is completed, the servo motor M2 of the synchronous lifting mechanism 3 rotates in the opposite direction, and the synchronous lifting mechanism 3 drives the material to be measured to move downward. When the servo motor M2 rotates in the opposite direction for a set number of pulses, it stops, and the material to be measured moves to the horizontal transmission mechanism 1.

[0059] Step 6: The servo motor M1 of the horizontal transmission mechanism 1 begins to rotate in the reverse direction. After rotating for a set number of pulses, motor M1 stops, and the material to be tested moves along the horizontal transmission mechanism 1 to the head end. The entire process is automated, allowing the operator to stay away from the material to be tested and reducing the risk of nuclear radiation.

[0060] The plutonium-containing material measuring device provided by this invention, without compromising the neutron multiplicity measuring device, achieves simultaneous neutron and gamma measurements of plutonium-containing materials by placing a gamma detector above the measuring chamber and neutron detectors around the measuring chamber, and adding an automatic feeding structure. This reduces measurement time and transportation process, lowers radiation hazards to personnel, reduces equipment size, and increases measurement accuracy. The neutron detectors are evenly distributed around the measuring chamber, reducing spatial positional differences during neutron measurement and improving measurement efficiency and accuracy. The measuring chamber is made of high-density polyethylene, which slows down neutrons, increases the reaction cross-section, and improves detection efficiency. A synchronous lifting mechanism is also included. In this system, the synchronous lifting mechanism utilizes only one drive motor to achieve synchronized up-and-down movement of the lifting plates on both sides, ensuring consistent lifting and preventing jamming during the process. The lower cover assembly can be moved to the measurement chamber via a horizontal transmission mechanism and a synchronous lifting mechanism, sealing the measurement chamber to form a closed space. This closed measurement chamber effectively reduces environmental interference and improves detection efficiency. The design of the lower cover assembly can shield external nuclear radiation from interfering with the measurement, while also preventing internal nuclear radiation from polluting the environment. Both the neutron detector and the gamma detector are electrically connected to the control system, and the control system is singular, thus reducing the equipment's manufacturing cost.

[0061] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention is also intended to include these modifications and variations.

Claims

1. A plutonium-bearing material measurement device, characterized by, The device includes: a measuring chamber (2), a lower cover assembly (4) and an automatic feeding structure. A gamma detector (5) is installed above the measuring chamber (2), and a neutron detector (6) is installed inside it to realize simultaneous gamma measurement and neutron measurement of the material to be measured. The automatic feeding structure is used to transport the material to be measured to the measuring chamber (2) for measurement; it includes a horizontal transmission mechanism (1) and a synchronous lifting mechanism (3). The synchronous lifting mechanism (3) is a symmetrical structure and is driven by a single power source. The power is precisely distributed and synchronously transmitted to the lifting execution points on both sides through the transmission of the gearbox and the lead screw pair. The lower cover assembly (4) is used to carry the material to be tested and is placed on the horizontal transmission mechanism (1). The lower cover assembly (4) and the material to be tested are conveyed horizontally to the lifting position through the horizontal transmission mechanism (1). The lower cover assembly (4) and the material to be tested are conveyed vertically to the upper measuring chamber (2) through the synchronous lifting mechanism (3). The bottom of the measuring chamber (2) is sealed by the lower cover assembly (4), thereby forming a closed measuring space.

2. The plutonium-bearing material measurement device of claim 1, wherein, The synchronous lifting mechanism (3) includes a servo drive motor (3.1), the output end of which is connected to a first gearbox (3.2). The first gearbox (3.2) has two output shafts, which are respectively connected to a first transmission shaft (3.7) and a third transmission shaft (3.9). The ends of the first transmission shaft (3.7) and the third transmission shaft (3.9) are respectively connected to a second gearbox (3.3) and a fourth gearbox (3.5). The output shafts of the second gearbox (3.3) and the fourth gearbox (3.5) are respectively connected to a second transmission shaft (3.8) and a fourth transmission shaft (3.10). The ends of the second drive shaft (3.8) and the fourth drive shaft (3.10) are respectively connected to the third gearbox (3.4) and the fifth gearbox (3.6). The output shafts of the third gearbox (3.4) and the fifth gearbox (3.6) are respectively connected to the input shafts of the first lead screw pair (3.11) and the second lead screw pair (3.12). The nuts of the first lead screw pair (3.11) and the second lead screw pair (3.12) are respectively fixedly provided with a first lifting plate (3.13) and a second lifting plate (3.14). Under the drive of the servo drive motor (3.1), the first lifting plate (3.13) and the second lifting plate (3.14) can move up and down synchronously.

3. The plutonium bearing material measurement apparatus according to claim 2, wherein, The output shaft of the servo drive motor (3.1) is arranged vertically upward and coaxially connected with the input shaft of the first gearbox (3.2); the two output shafts of the first gearbox (3.2) are 180 degrees symmetrical and arranged horizontally radially outward.

4. The plutonium bearing material measurement apparatus according to claim 3, wherein, The first drive shaft (3.7) and the third drive shaft (3.9) are horizontally and collinearly opposite each other, extending in opposite directions; the input shafts of the second gearbox (3.3) and the fourth gearbox (3.5) are horizontal, and their output shafts are horizontally arranged in the same direction and perpendicular to the corresponding input shafts.

5. The plutonium bearing material measurement apparatus according to claim 4, wherein, The input shaft of the third gearbox (3.4) is horizontally coaxially connected to the second transmission shaft (3.8), and the input shaft of the fifth gearbox (3.6) is horizontally coaxially connected to the fourth transmission shaft (3.10). The output shafts of the third gearbox (3.4) and the fifth gearbox (3.6) are vertically downward.

6. The plutonium bearing material measurement apparatus according to claim 1, wherein, The lower cover assembly 4 is cylindrical in shape and includes, from bottom to top, a barrel-shaped mounting plate (4.1), a reflective layer (4.4), a shielding layer (4.3), a moderating layer (4.2), and a tray cover (4.5). The material to be tested is placed on the tray cover (4.5).

7. The plutonium bearing material measurement apparatus according to claim 6, wherein, The moderating layer (4.2) is made of polyethylene, the shielding layer (4.3) is made of cadmium sheet, and the reflective layer (4.4) is made of graphite.

8. The plutonium bearing material measuring device of claim 6 or 7, wherein, The measuring chamber (2) is a hollow cylindrical structure, and the neutron detector (6) is a multi-column structure, which is evenly distributed in multiple rings along the inside of the measuring chamber (2).

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