A neutron measuring instrument

Abstract

The present invention discloses a neutron meter, relating to the field of nuclear radiation detection technology. Specifically, the neutron meter comprises a spherical outer polyethylene moderator assembly and a cylindrical inner polyethylene moderator assembly. The cylindrical inner polyethylene moderator assembly is assembled inside the spherical outer polyethylene moderator assembly. The spherical outer polyethylene moderator assembly mainly comprises a spherical cover, a spherical outer polyethylene moderator body, and a support column. A thermal neutron detector is assembled in the cylindrical inner polyethylene moderator body. The neutron meter utilizes a method of fixing with a locating pin and integrated processing of a thermal neutron absorption layer hole to achieve secure and accurate positioning of the neutron meter, thereby ensuring an optimized energy response effect of the neutron meter. Furthermore, the neutron meter has a compact overall structure, moderate size, and low weight.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear radiation detection, and more particularly to a neutron measuring instrument. Background Art

[0002] Neutron meter is a common nuclear radiation detection instrument, also called neutron detector. It is suitable for RI facilities, especially neutron measurement in accelerator facilities, police, fire protection systems, emergency equipment (corresponding to critical accidents), nuclear power facilities, measuring neutron lines from reactors, measuring environmental neutron dose rate and cumulative dose, monitoring site radiation levels. Neutron measurement methods include nuclear reaction method, nuclear recoil method, activation method, and nuclear fission method. Among them, the nuclear reaction method is more widely used. This method can be used to detect slow and fast neutron flux density and neutron dose rate.

[0003] At present, the thermal neutron detectors commonly used in neutron nuclear reaction method are 3He counter tube, 6 Li glass, BF3 counter tubes, etc., the reaction cross section of these detectors to neutrons conforms to the 1 / v law, that is, they are only sensitive to thermal neutrons and have a very low energy response to fast neutrons. To improve the detection efficiency and energy response of fast neutrons, polyethylene moderators are used. By utilizing the elastic and inelastic scattering of neutrons with light nuclei such as C and H in the polyethylene moderator, the fast neutrons are slowed down into thermal neutrons. Therefore, neutron measuring instruments generally consist of a thermal neutron detector, a polyethylene moderator, and a measurement system. The thermal neutron detector is located at the geometric center and is surrounded by a polyethylene moderator. Although the use of a polyethylene moderator in a neutron measuring instrument can improve the energy response of fast neutrons, it also attenuates and absorbs thermal neutrons, resulting in insufficient thermal neutron energy response. It also fully moderates intermediate energy neutrons, resulting in an excessively large intermediate energy neutron energy response.

[0004] In general, the neutron measurement instrument underestimates in the slow neutron energy range and the fast neutron energy range, and overestimates in the medium energy range. It cannot meet the energy response error requirements of "GB / T14318-2019 Radiation Protection Instrument Neutron Ambient Dose Equivalent (Rate) Meter": thermal neutron ~ 50keV, the response is 0.2~8.0; 50keV~10MeV, the response is 0.5~2.0; 10MeV~20MeV, the response is 0.2~2.0, which seriously affects the detection performance. To this end, we designed a neutron measurement instrument to solve the above problems. Summary of the Invention

[0005] In view of the above problems, the present invention proposes a neutron measuring instrument to improve the above problems.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a neutron measuring instrument, comprising a spherical outer polyethylene moderator assembly and a cylindrical inner polyethylene moderator assembly, wherein the cylindrical inner polyethylene moderator assembly is assembled on the inner side of the spherical outer polyethylene moderator assembly, the spherical outer polyethylene moderator assembly mainly comprising a spherical cover, a spherical outer polyethylene moderator body, and a support column, a thermal neutron detector is assembled in the cylindrical inner polyethylene moderator body, the cylindrical inner polyethylene moderator assembly comprises a cylindrical inner polyethylene moderator body, a side thermal neutron absorption layer, a top thermal neutron absorption layer, a bottom thermal neutron absorption layer, a thermal neutron detector, a hardware module, and a gland, the side thermal neutron absorption layer is sleeved on the outside of the cylindrical inner polyethylene moderator body, a positioning column is assembled at the bottom of the cylindrical inner polyethylene moderator body to assist in the assembly of the cylindrical inner polyethylene moderator assembly, and a positioning groove is formed in the spherical outer polyethylene moderator assembly to match the positioning column.

[0007] Furthermore, there are three support columns, and the three support columns are evenly installed at the bottom of the spherical outer polyethylene moderator assembly.

[0008] Furthermore, the cylindrical inner polyethylene moderator assembly is designed with 10 air channels, including 1 top air channel, 1 bottom air channel, and 8 outer air channels evenly distributed outside the spherical outer polyethylene moderator assembly.

[0009] Furthermore, the outer side of the side thermal neutron absorption layer is processed with 8 evenly distributed first thermal neutron absorption layer holes by an integrated processing method, and the positions of the first thermal neutron absorption layer holes correspond to the positions of the external air channels.

[0010] Furthermore, a second thermal neutron absorption layer hole is designed on the top thermal neutron absorption layer, and a third thermal neutron absorption layer hole is designed on the bottom thermal neutron absorption layer.

[0011] Furthermore, the side thermal neutron absorption layer is in the shape of a thin-walled cylinder, and is made of cadmium or boron-containing polyethylene material.

[0012] Furthermore, 8 positioning pin holes are evenly designed on the side thermal neutron absorption layer, and the positioning pin holes are evenly distributed at the upper and lower and circumferential positions of the side thermal neutron absorption layer, and the side thermal neutron absorption layer is installed on the side of the cylindrical inner layer polyethylene moderator body, aligned up and down, and the outside of the cylindrical inner layer polyethylene moderator body is equipped with positioning pins that match the positioning pin holes.

[0013] Furthermore, the air channels of the spherical outer polyethylene moderator assembly are respectively aligned with the thermal neutron absorption layer holes of the cylindrical inner polyethylene moderator assembly. The specific corresponding relationship is that the top air channel is aligned with the second thermal neutron absorption layer hole, the bottom air channel is aligned with the third thermal neutron absorption layer hole, and the outer air channel is aligned with the first thermal neutron absorption layer hole.

[0014] The present invention provides a neutron measuring instrument, which has the following beneficial effects:

[0015] 1. The neutron measuring instrument has a good energy response effect by designing the thermal neutron absorption layer and air channel, which fully meets the requirements of the "GB / T14318-2019 Radiation Protection Instrument Neutron Ambient Dose Equivalent (Rate) Meter" for energy response error: thermal neutron ~ 50keV, the response is 0.2~8.0; 50keV~10MeV, the response is 0.5~2.0; 10MeV~20MeV, the response is 0.2~2.0.

[0016] 2. The neutron measuring instrument adopts a method of fixing with positioning pins and processing the thermal neutron absorption layer hole in an integrated manner to achieve firm and accurate positioning of the neutron measuring instrument, thereby ensuring the energy response optimization effect of the neutron measuring instrument. In addition, the overall structure of the neutron measuring instrument is compact, the size is moderate, and the weight is relatively light. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic diagram of the spherical outer polyethylene moderator body proposed in the present invention is shown;

[0019] Figure 2 A schematic diagram showing the air passage of the spherical outer polyethylene moderator proposed in the present invention is shown;

[0020] Figure 3 A schematic diagram of the cylindrical inner layer polyethylene moderator body proposed in the present invention is shown;

[0021] Figure 4 The figure shows the external schematic diagram of the side thermal neutron absorption layer proposed by the present invention;

[0022] Figure 5 It shows a schematic diagram of the structure after machining the first thermal neutron absorption layer hole outside the side thermal neutron absorption layer proposed by the present invention;

[0023] Figure 6A schematic diagram showing the interior of a cylindrical inner layer polyethylene moderator assembly proposed in the present invention is shown;

[0024] Figure 7 The figure shows the internal structure of the neutron measuring instrument proposed by the present invention.

[0025] In the figure: 1. Spherical outer polyethylene moderator assembly; 11. Spherical cover; 12. Spherical outer polyethylene moderator body; 13. Support column; 111. Top air channel; 121. Bottom air channel; 122. Outer air channel; 123. Positioning groove; 2. Cylindrical inner polyethylene moderator assembly; 21. Cylindrical inner polyethylene moderator body; 211. Positioning column; 22. Side thermal neutron absorption layer; 221. Positioning pin hole; 222. First thermal neutron absorption layer hole; 23. Top thermal neutron absorption layer; 231. Second thermal neutron absorption layer hole; 24. Bottom thermal neutron absorption layer; 241. Third thermal neutron absorption layer hole; 25. Thermal neutron detector; 26. Hardware module; 27. Pressure cover. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Please refer to Figure 1 As shown in FIG, the spherical outer layer polyethylene moderator main body assembly 1 is composed of a spherical cover 11, a spherical outer layer polyethylene moderator main body 12 and support columns 13. Three support columns 13 are evenly installed at the bottom of the spherical outer layer polyethylene moderator main body assembly 1 to form a good support surface.

[0028] Reference Figure 2 As shown in the figure, the spherical outer polyethylene moderator main assembly 1 requires air channels to improve the energy response of thermal neutrons. The present invention employs ten air channels: one top air channel 111, one bottom air channel 121, and eight outer air channels 122 evenly distributed along the horizontal circle of the sphere. This ensures uniform improvement in the energy response of thermal neutrons entering from all directions. Furthermore, two positioning grooves 123 are designed at the bottom of the spherical outer polyethylene moderator main assembly 1 to facilitate precise positioning with the cylindrical inner polyethylene moderator main assembly.

[0029] Reference Figure 3 As shown in FIG, the cylindrical inner polyethylene moderator body 21 is designed with two positioning posts 211 at the bottom for precise positioning with the spherical outer polyethylene moderator body assembly 1.

[0030] Reference Figure 4 As shown in the figure, the side thermal neutron absorption layer 22 is a thin-walled cylindrical layer, requiring the design of thermal neutron absorption layer holes. Furthermore, it must be securely and accurately positioned with the air passage of the spherical outer polyethylene moderator body. Any misalignment will affect the energy response. However, it is generally made of soft materials such as cadmium or boron-containing polyethylene, which have relatively thin walls and are difficult to achieve. The present invention utilizes a method for integrated positioning pin fixation and thermal neutron absorption layer hole processing. The side thermal neutron absorption layer 22 is uniformly designed with eight positioning pin holes 221, located above and below and around the circumference; the thermal neutron absorption layer holes are not processed at this time.

[0031] Reference Figure 5 As shown in Figure 2, the side thermal neutron absorption layer 22 is mounted on the side of the cylindrical inner polyethylene moderator body 21, aligned vertically. Eight locating pin holes 221 are used to securely secure the two together. The eight evenly spaced thermal neutron absorption layer holes 222 are then fabricated using an integrated manufacturing method, making the process easy and ensuring precise positioning.

[0032] Reference Figure 6 As shown in the figure, the cylindrical inner layer polyethylene moderator main body assembly 2 consists of a cylindrical inner layer polyethylene moderator main body 21, a side thermal neutron absorption layer 22, a top thermal neutron absorption layer 23, a bottom thermal neutron absorption layer 24, a thermal neutron detector 25, a hardware module 26 and a pressure cover 27, wherein the top thermal neutron absorption layer 23 is designed with a thermal neutron absorption layer hole 231, and the bottom thermal neutron absorption layer 24 is designed with a thermal neutron absorption layer hole 241.

[0033] Reference Figure 7 As shown, the neutron measurement instrument consists of a spherical outer polyethylene moderator main assembly 1 and a cylindrical inner polyethylene moderator main assembly 2. These are positioned and assembled using positioning posts 211 and positioning slots 123. The air channels of the spherical outer polyethylene moderator main assembly 1 are aligned with the thermal neutron absorption layer holes of the cylindrical inner polyethylene moderator main assembly 2. Specifically, the air channels 111 align with the thermal neutron absorption layer holes 231, the air channels 121 align with the thermal neutron absorption layer holes 241, and the outer air channels 122 align with the thermal neutron absorption layer holes 222. This design ensures optimal energy response.

[0034] In summary, the present invention provides a neutron measuring instrument. When in use, the three support columns 13 are evenly installed at the bottom of the spherical outer polyethylene moderator main body component 1 to form a good support surface to support the spherical outer polyethylene moderator main body component 1. The side thermal neutron absorption layer 22 is installed on the side of the cylindrical inner polyethylene moderator main body 21, aligned up and down, and eight positioning pin holes 221 are used to fix the two firmly. Then, the eight evenly distributed thermal neutron absorption layer holes 222 are processed by an integrated processing method to design the bottom of the cylindrical inner polyethylene moderator main body 21. The two positioning posts 211 are inserted into the spherical outer polyethylene moderator main assembly 1. Positioning and assembly are completed according to the positioning posts 211 and the positioning grooves 123. At this time, the air channels of the spherical outer polyethylene moderator main assembly 1 are aligned with the thermal neutron absorption layer holes of the cylindrical inner polyethylene moderator main assembly 2. The thermal neutron detector obtains neutron ray signals after the energy response of the polyethylene moderator, thermal neutron absorption layer, and air channels is optimized. Through signal recognition, processing, and display by the hardware module, neutron radiation monitoring is achieved, completing the assembly and operation process of the entire neutron measuring instrument.

[0035] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or components referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes and should not be understood as indicating or implying relative importance. In addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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, an indirect connection through an intermediate medium, or it can be internal communication between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Furthermore, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0036] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A neutron measuring instrument comprising a spherical outer polyethylene moderator assembly (1) and a cylindrical inner polyethylene moderator assembly (2), wherein the cylindrical inner polyethylene moderator assembly (2) is assembled on the inner side of the spherical outer polyethylene moderator assembly (1), characterized in that: The cylindrical inner polyethylene moderator assembly (2) is designed with 10 air channels, namely, a top air channel (111), a bottom air channel (121), and 8 outer air channels (122) uniformly distributed outside the spherical outer polyethylene moderator assembly (1). The spherical outer polyethylene moderator assembly (1) is composed of a spherical cover (11), a spherical outer polyethylene moderator body (12), and a support column (13). The cylindrical inner polyethylene moderator assembly (2) is composed of a cylindrical inner polyethylene moderator body (21), a side thermal neutron absorption layer (22), a top thermal neutron absorption layer (23), a bottom thermal neutron absorption layer (24), a thermal neutron detector (25), a hardware module (26), and a pressure cover (27). The cylindrical inner polyethylene moderator body (21) is equipped with a thermal neutron detector (25); the outer side of the side thermal neutron absorption layer (22) is processed by an integrated processing method to have 8 evenly distributed first thermal neutron absorption layer holes (222); the positions of the first thermal neutron absorption layer holes (222) correspond to the positions of the external air channels (122); the side thermal neutron absorption layer (22) is sleeved on the outside of the cylindrical inner polyethylene moderator body (21); the bottom of the cylindrical inner polyethylene moderator body (21) is equipped with a positioning column (211) for assisting the assembly of the cylindrical inner polyethylene moderator assembly (2); and the spherical outer polyethylene moderator assembly (1) is provided with a positioning groove (123) that matches the positioning column (211).

2. A neutron measuring instrument according to claim 1, characterized in that: There are three support columns (13), and the three support columns (13) are evenly installed at the bottom of the spherical outer polyethylene moderator assembly (1).

3. A neutron measuring instrument according to claim 1, characterized in that: A second thermal neutron absorption layer hole (231) is designed on the top thermal neutron absorption layer (23), and a third thermal neutron absorption layer hole (241) is designed on the bottom thermal neutron absorption layer (24).

4. A neutron measuring instrument according to claim 1, characterized in that: The side thermal neutron absorption layer (22) is in the shape of a thin-walled cylinder, and the side thermal neutron absorption layer (22) is made of cadmium or boron-containing polyethylene material.

5. A neutron measuring instrument according to claim 1, characterized in that: Eight positioning pin holes (221) are evenly designed on the side thermal neutron absorption layer (22), and the positioning pin holes (221) are evenly distributed at upper and lower and circumferential positions of the side thermal neutron absorption layer (22). The side thermal neutron absorption layer (22) is installed on the side of the cylindrical inner layer polyethylene moderator body (21) and is aligned up and down. The outside of the cylindrical inner layer polyethylene moderator body (21) is equipped with positioning pins that match the positioning pin holes (221).

6. A neutron measuring instrument according to claim 3, characterized in that: The air channels of the spherical outer polyethylene moderator assembly (1) are aligned with the thermal neutron absorption layer holes of the cylindrical inner polyethylene moderator assembly (2), respectively. Specifically, the top air channel (111) is aligned with the second thermal neutron absorption layer hole (231), the bottom air channel (121) is aligned with the third thermal neutron absorption layer hole (241), and the outer air channel (122) is aligned with the first thermal neutron absorption layer hole (222).

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