Variable cross-section shielding device and nuclear facility shielding system

Abstract

The application discloses a variable cross-section shielding device, comprising: a shielding device body, the shielding device body is installed in a through hole, used for shielding ionizing radiation, the shielding device body extends along the axial direction of the through hole, the diameter of the shielding device body decreases along the axial direction of the through hole, so that the vertical cross section of the shielding device body is conical, the smaller end of the cross section of the shielding device body is used for inserting into the through hole, the shielding device body is composed of one or more shielding units, the shielding unit comprises a central shaft and a spiral blade, the central shaft extends along the axial direction of the through hole, the spiral blade is arranged on the central shaft, the outer edge of the spiral blade abuts against the inner wall of the through hole, and the spiral blade is used for scattering, slowing down and absorbing the rays, so as to reduce the radiation intensity and the ray energy. Therefore, the variable cross-section shielding device can effectively shield ionizing radiation and radiation leakage and avoid potential radiation risks. The application further discloses a nuclear facility shielding system.

Description

TECHNICAL FIELD

[0001] The present application relates to a variable cross-section shielding device and a nuclear facility shielding system. BACKGROUND

[0002] There are various shielding bodies in a nuclear facility, including shielding walls and shielding boxes, for protecting and shielding various types of radiation. There are usually through holes in the shielding bodies to meet various needs, such as for cable installation, ventilation, pipe penetration, medium flow and exchange, heat dissipation, etc. However, the radiation and radiation leakage in the nuclear facility will leak out from the through holes, which will increase the radiation level outside the shielding body, causing the environmental radiation level outside the shielding body to exceed the standard, increasing the radiation risk to personnel.

[0003] Currently, to keep the environmental radiation level within an acceptable range, the existing shielding bodies usually set the through holes as a multi-bend channel structure to reduce radiation and radiation leakage. For example, as shown in FIG. 1, a multi-bend channel 4 is opened in a wall 3 between a high radiation level area 1 and a low radiation level area 6, a compensation shield 2 is added in the wall 3, and an additional shielding body 5 is added outside the wall 3, so as to weaken the through radiation and radiation leakage. Figure 1

[0004] However, although this multi-bend through hole shielding structure can reduce direct leakage of radiation and radiation leakage, the multi-bend through hole in the shielding body causes a large number of cavities in the shielding body, affecting the overall shielding effect of the shielding body and increasing the potential radiation risk. Moreover, the shape of the through hole is complex, which greatly increases the manufacturing difficulty of the shielding body.

[0005] In addition, due to the increase in the channel length of the through hole, the length of the pipes and cables and other equipment installed therein also increases, and needs to be bent multiple times, which increases the installation difficulty of the pipes and cables and other equipment and makes it inconvenient to replace and disassemble.

[0006] The compensation shield 2 and the additional shielding body 5 in the existing shielding structure will increase the cost. Moreover, the additional shielding body 5 will also occupy additional space, hindering the passage of equipment and personnel. Moreover, the radiation intensity is different in different areas of the nuclear facility, and in order to ensure the shielding effect, different shielding compensation schemes need to be designed for each through hole, which requires the compensation shield 2 and the additional shielding body 5 to be designed and constructed separately, and cannot be scaled designed and constructed, which greatly increases the design cost. SUMMARY

[0007] ​The technical problem to be solved by the present application is to provide a variable cross-section shielding device and a nuclear facility shielding system, which can effectively shield ionizing radiation and radiation leakage and avoid potential radiation risks, and can be installed conveniently and quickly.

[0008] According to the embodiment of the first aspect of the present application, a variable cross-section shielding device is provided, comprising: a shielding device body, which is installed in a through hole and used for shielding ionizing radiation, the shielding device body extending along the axial direction of the through hole, the diameter of the shielding device body decreasing along the axial direction of the through hole, so that the vertical cross section of the shielding device body is conical, the smaller end of the cross section of the shielding device body being used for inserting into the through hole, the shielding device body being composed of one or more shielding units, the shielding unit comprising a central shaft and a spiral blade, the central shaft extending along the axial direction of the through hole, the spiral blade being arranged around the central shaft, the outer edge of the spiral blade abutting against the inner wall of the through hole, the spiral blade being used for scattering, slowing down and absorbing the rays to reduce the radiation intensity and the ray energy.

[0009] Preferably, the number of the shielding units is multiple, the multiple shielding units being fixedly connected in sequence along the axial direction of the through hole, the length of each spiral shielding unit being greater than or equal to 10 mm, and the total length of the multiple shielding units being not more than 200% of the thickness of the shielding body.

[0010] Preferably, the spiral blade is made of a multi-component alloy material, the multi-component alloy material being composed of a hydrogenated metal, boron carbide, tungsten and aluminum, wherein the hydrogenated metal is lithium hydride / titanium hydride / zirconium hydride, the mass ratio of the hydrogenated metal being 1-20 wt%, the mass ratio of the boron carbide being 2-20 wt%, the mass ratio of the tungsten being 20-70 wt%, and the mass ratio of the aluminum being 30-70 wt%.

[0011] Preferably, the central shaft is made of a multi-component alloy material, the multi-component alloy material being composed of a hydrogenated metal, boron carbide, tungsten and aluminum, wherein the hydrogenated metal is lithium hydride / titanium hydride / zirconium hydride, the mass ratio of the hydrogenated metal being 1-20 wt%, the mass ratio of the boron carbide being 2-20 wt%, the mass ratio of the tungsten being 20-70 wt%, and the mass ratio of the aluminum being 30-70 wt%.

[0012] Preferably, the outer diameter D of the spiral blade is 10-2000 mm, and the diameter d of the central shaft is 5-300 mm.

[0013] Preferably, the elongation ratio of the spiral blade is 0.1-100, the elongation ratio being the ratio of the axial length L2 of the spiral blade rotating one round around the central shaft to the maximum radial length L1 of the spiral blade.

[0014] Preferably, the single shielding unit comprises one or more spiral blades, each of which is arranged around the central shaft which is integrally formed with the spiral blade.

[0015] Preferably, the number of spiral blades is greater than or equal to two, each spiral blade is arranged along the circumference of the central shaft in sequence, and the distance between adjacent spiral blades is greater than 1 mm.

[0016] Preferably, the number of spiral blades ranges from 1 to 12, and the thickness of the spiral blade is 1-200 mm.

[0017] According to the embodiment of the second aspect of the present application, a nuclear facility shielding system is provided, comprising a shielding body for shielding ionizing radiation, a through hole is formed in the shielding body, the vertical section of the through hole is conical, and the system further comprises the variable cross-section shielding device described above, which is fixedly installed in the through hole, and the spiral blade of the variable cross-section shielding device and the inner wall of the through hole form a spiral channel for the passage of cables and the exchange of media.

[0018] Preferably, a blocking net is further included, which is installed on the outside of the shielding body and covers the through hole, for preventing sundries from falling into the spiral channel.

[0019] Preferably, the through hole is arranged in the vertical direction, and the shielding body is provided with a boss at the upper end of the through hole, which is used to prevent liquid from flowing into the through hole.

[0020] The shielding device body in the present application is installed in the through hole of the shielding body. The outer edge of the spiral blade of the shielding unit abuts against the inner wall of the through hole, and the spiral blade can scatter and absorb the rays entering the through hole, thereby reducing the radiation intensity and ray energy. Through the central shaft and the spiral blade, ionizing radiation and radiation leakage can be effectively shielded, designers no longer need to design the through hole to be bent, and the length of the through hole does not need to be greatly extended, thereby reducing the hollow volume in the shielding body, and effectively avoiding potential radiation risks. In addition, since the vertical section of the shielding device body is conical, by arranging the smaller end of the cross section of the shielding device body to the front, the shielding device body can be quickly inserted into the through hole, thereby improving the installation efficiency. Therefore, the variable cross-section shielding device can effectively shield ionizing radiation and radiation leakage and avoid potential radiation risks, and can be conveniently and quickly installed. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram of the shielding structure of a nuclear facility in the prior art;

[0022] Figure 2 is a structural schematic view of a cross-section of a shielding unit in some embodiments of the present application;

[0023] Figure 3 is a structural schematic view of a shielding unit in some embodiments of the present application;

[0024] Figure 4a is a vertical cross-sectional view of a shielding device body of a first type in some embodiments of the present application;

[0025] Figure 4b is a vertical cross-sectional view of a shielding device body of a second type in some embodiments of the present application;

[0026] Figure 4c is a vertical cross-sectional view of a shielding device body of a third type in some embodiments of the present application;

[0027] Figure 4d is a vertical cross-sectional view of a shielding device body of a fourth type in some embodiments of the present application;

[0028] Figure 5a is a structural schematic view of a nuclear facility shielding unit without a boss in some embodiments of the present application;

[0029] Figure 5b is a structural schematic view of a nuclear facility shielding unit with a boss in some embodiments of the present application.

[0030] In the figure: 1 - high radiation level area, 2 - compensating shield, 3 - wall, 4 - channel, 5 - additional shield, 6 - low radiation level area, 7 - central axis, 8 - helical blade, 9 - shielding device body, 10 - shield, 11 - barrier net, 12 - boss. DETAILED DESCRIPTION

[0031] The technical solutions in the present application will be described clearly and completely below in conjunction with the drawings in the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0032] In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience and simplification of description, and do not indicate or imply that the devices or elements referred to must be provided with a particular orientation, constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0033] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection," "setting," "installation," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] Example 1

[0036] Please see Figure 2 and Figure 3 The present invention discloses a variable cross-section shielding device, including a shielding device body 9.

[0037] The shielding device body 9 is installed inside the through-hole to shield ionizing radiation. The shielding device body 9 extends axially along the through-hole, and its diameter decreases axially to create a tapered vertical cross-section. The smaller end of the shielding device body 9 is inserted forward into the through-hole. Specifically, during installation, the worker ensures the smaller end faces forward; this end's cross-section is smaller than the cross-section of the through-hole entrance. Therefore, alignment is quicker, eliminating the need for extensive time and improving installation efficiency.

[0038] Then, the operator applies pressure towards the inside of the shielding device body 9 to press it against the sidewall of the through hole, and then secures it within the through hole using fasteners. For example, the operator places the shielding device body 9 into the through hole and applies pressure by hand to press it against the sidewall of the through hole. Next, a positioning screw is installed at the end of the shielding device body 9 with the larger cross-section. This positioning screw restricts the axial movement of the shielding device body 9, thus securing it within the through hole. For disassembly, simply removing the positioning screw allows the shielding device body 9 to be easily removed.

[0039] Furthermore, the shielding device body 9 is composed of shielding units, each including a central shaft 7 and helical blades 8. The central shaft 7 extends axially along the through-hole, and the helical blades 8 are wound around the central shaft 7. The outer edge of the helical blades 8 abuts against the inner wall of the through-hole. The helical blades 8 are used to scatter, slow down, and absorb radiation to reduce radiation intensity and energy. The central shaft 7 and helical blades 8 within the through-hole effectively shield ionizing radiation and radiation leakage. Designers no longer need to bend the through-hole or significantly extend its length, thus reducing the volume of voids within the shielding body 10 and effectively avoiding potential radiation risks.

[0040] Therefore, this variable cross-section shielding device can effectively shield radiation and radiation leakage beams and avoid potential radiation risks, while also being easy and quick to install.

[0041] Please see Figure 4a , Figure 4b , Figure 4c and Figure 4d The shielding device body 9 can be composed of one or more shielding units. It is understood that when the radiation intensity in the service environment is low, installing a single shielding unit in the through-hole is sufficient to achieve a good shielding effect. To ensure the shielding effect of the shielding device body 9, the length of a single shielding unit should be greater than or equal to 10 mm.

[0042] When the radiation intensity in the service environment is high, multiple shielding units are required to achieve the desired shielding effect. Multiple shielding units are sequentially fixedly connected along the axial direction of the through-hole. In some embodiments, such as... Figure 4a , Figure 4c and Figure 4d As shown, the shielding device body 9 consists of three variable cross-section shielding units. The outer diameter of the helical blades 8 of these shielding units gradually decreases along the extension direction of the central axis 7, making each shielding unit conical. In other embodiments, as described... Figure 4b As shown, the shielding device body 9 consists of three shielding units with different cross-sections. The cross-sectional area of ​​a single shielding unit does not change along the extension direction of the central axis 7, but the cross-sections of multiple shielding units decrease sequentially along the axial direction of the through hole, thus causing the diameter of the shielding device body 9 to decrease in a stepwise manner along the axial direction of the through hole. When installing the shielding device body 9 composed of multiple shielding units, the operator can first fix the multiple shielding units together, and then install the whole assembly into the through hole. Adjacent shielding units can be fixed together by means of adhesive bonding, welding, tenon and mortise joints, bolts, or pins. Alternatively, the operator can first place multiple shielding units into the through hole and then fix them in place using positioning screws.

[0043] Furthermore, if the total length of multiple shielding units connected together is too long, it will occupy excessive additional space, thus obstructing the passage of equipment and personnel. To avoid obstructing the passage of equipment and personnel, the total length of multiple shielding units connected together should not exceed 200% of the thickness of the shielding body.

[0044] Please see Figure 2 Each shielding unit includes one or more helical blades 8, all of which are wound around a central shaft 7. When there are two or more helical blades 8, each helical blade 8 is arranged sequentially along the circumference of the central shaft 7. Figure 2 This is a schematic diagram of a shielding unit with six helical blades 8. It is easy to see that when the shielding unit is installed inside a through-hole, a helical channel is formed between the helical blades 8 and the sidewall of the through-hole. Furthermore, when there are two or more helical blades 8, a helical channel is formed between each pair of adjacent helical blades 8. Figure 2 The shielding unit shown has six spiral channels. These spiral channels are used for cable routing and for media flow and exchange.

[0045] Specifically, the rotation angle of a single helical blade 8 around the central axis 7 is not less than 3°, and the sum of the rotation angles of multiple helical blades 8 around the central axis 7 should be greater than 360° to ensure that multiple helical blades 8 can cover the cross-section of the through hole, thereby effectively shielding radiation and radiation leakage. Furthermore, when the through hole is used for cable installation, the rotation angle range of the helical blade 8 around the central axis 7 is 5°-360°. When the through hole is used for medium flow and exchange, heat dissipation, heat transfer, or ventilation, the rotation angle range of the helical blade 8 around the central axis 7 is 3°-360°. A single helical blade 8 can be a smooth, continuous helical surface or composed of multiple discontinuous, stepped helical surfaces.

[0046] It is worth noting that the more spiral blades 8 a single shielding unit has, the better the shielding effect. However, too many spiral blades 8 will narrow the spiral channel, making it difficult for cables to pass through smoothly, and will reduce the efficiency of medium flow and exchange. Preferably, the number of spiral blades 8 ranges from 1 to 12. Moreover, to ensure the efficiency of medium flow and exchange, the distance between two adjacent spiral blades 8 should be at least greater than 1 mm.

[0047] Furthermore, the number of helical blades 8 on a single shielding unit needs to be selected based on the radioactivity intensity of ionizing radiation in the service environment. For low-level ionizing radiation, the number of helical blades 8 in the shielding unit is 1 or 2. For intermediate-level ionizing radiation, the number of helical blades 8 in the shielding unit is 3-6. For high-level ionizing radiation or strong neutron radiation, the number of helical blades 8 in the shielding unit is 7-12.

[0048] Please refer to the relevant regulations, including Announcement No. 65 of 2017 issued by the Ministry of Environmental Protection, the Ministry of Industry and Information Technology, and the State Administration of Science, Technology and Industry for National Defense, entitled "Classification of Radioactive Waste"; National Standard GB18871-2002 "Basic Standards for Radiation Protection and Radiation Source Safety of Ionizing Radiation"; and Nuclear Industry Standard EJ849 "Radiation Safety Design Regulations for Nuclear Fuel Reprocessing Plants". The activity concentration of low-ionizing radiation radioactive waste is greater than 8 × 10⁻⁶. 4 And less than or equal to 4 × 10 6 (Unit: Bq / L or Bq / kg); The activity concentration of radioactive waste with moderate ionizing radiation is greater than 4 × 10⁻⁶. 6 And less than or equal to 4 × 10 10 (Unit: Bq / L or Bq / kg); The activity concentration of radioactive waste with high ionizing radiation is greater than 4 × 10⁻⁶. 10 (Unit: Bq / L or Bq / kg). The neutron source intensity of strong neutron radiation is greater than 100,000 n / s.

[0049] Furthermore, relevant regulations stipulate that compared to low and medium-level ionizing radiation, high-level ionizing radiation, in addition to having a higher concentration of radioactivity, is also accompanied by heat release, hydrogen release, and stronger secondary radiation. Therefore, the methods for protection, shielding, handling, and disposal of low, medium, and high-level ionizing radiation are fundamentally different. It is easy to understand that for high-level ionizing radiation, the shielding unit of this shielding device also needs to consider factors such as radiation resistance, high-temperature resistance, corrosion resistance, and overall shielding performance. Therefore, when this shielding device is used to shield high-level or strong neutron radiation, personnel need to consider the heat release, hydrogen release, secondary radiation level, and irradiation level of the high-level or strong neutron radiation to select key parameters such as the number, material, elongation ratio, thickness, and radial length of the helical blades 8.

[0050] Specifically, the number of helical blades (8) is one of the main factors affecting the effectiveness of shielding against high-level radioactive ionizing radiation. For high-level radioactive radiation or strong neutron radiation, secondary radiation generated by its interaction with the shielding body and shielding units can account for 20%-80% of the total radiation. Secondary radiation includes (n,γ) reactive photons and bremsstrahlung, etc. Through modeling calculations and experimental measurements, the number of helical blades (8) should be 7-12 to effectively shield against high-level radioactive radiation or strong neutron radiation with strong penetrating power.

[0051] For example, the shielding unit contains seven helical blades 8. In this case, the helical blades 8 form a Canon-style shielding mechanism. That is, by repeatedly stacking a specific number of helical blades 8 according to specific parameters, high-radioactivity or strong neutron radiation interacts with the front helical blades 8 to generate secondary radiation. The rear helical blades 8 can shield against the secondary radiation generated in the front section, and the helical channels formed between the helical blades 8 can achieve the shielding effect of absorbing secondary radiation through resonant absorption and scattering. When the number of helical blades 8 is 8, 9, 10, 11, or 12, the principle is similar to the above and will not be elaborated further.

[0052] In some embodiments, the helical blade 8 and the central shaft 7 are made of a multi-component alloy material with excellent comprehensive shielding performance to shield against high-level radioactive ionizing radiation or strong neutron radiation. Specifically, both the helical blade 8 and the central shaft 7 are made of a multi-component alloy material composed of lithium hydride, boron carbide, tungsten, and aluminum. The mass proportion of lithium hydride is 1-20 wt%, boron carbide is 2-20 wt%, tungsten is 20-70 wt%, and aluminum is 30-70 wt%. Of course, lithium hydride can be replaced with other hydride metals, such as titanium hydride or zirconium hydride. Different nuclide components in this multi-component alloy material have different radiation shielding mechanisms. By rationally utilizing the shielding mechanisms of different nuclides, the comprehensive shielding capability can be improved. Specifically, the light nuclide element (i.e., hydrogen) in this alloy material has a large neutron reaction cross section and a high probability of interacting with neutrons, effectively shielding neutron radiation. The boron element in this alloy material produces low gamma energy from neutron radiation capture, which can further reduce secondary radiation, such as (n,γ) reactions.

[0053] Furthermore, tungsten has a high inelastic scattering cross section, which can slow down fast neutrons, reducing them to low- to medium-energy neutrons. These low- to medium-energy neutrons then undergo elastic scattering with hydrogen, further lowering their energy and slowing them down to thermal neutrons. Boron, with its large absorption cross section, then further absorbs the energy of these thermal neutrons. This series of actions not only efficiently slows down and absorbs neutrons, but also significantly reduces the secondary radiation generated by the reaction of neutrons with the shielding material due to the substantial reduction in the total number and intensity of fast neutrons. Simultaneously, the aluminum and tungsten metals in this alloy can effectively shield against gamma rays directly emitted from neutron fission and secondary gamma rays generated by the interaction of neutrons with the shielding material.

[0054] Of course, in other embodiments, the helical blades 8 and the central shaft can also be made of other materials. It is understood that different types of radiation exist in different nuclear facilities or different areas of the same nuclear facility. For example, areas such as high-level radioactive waste treatment facilities and perimeter buildings of fusion reactor devices experience strong neutron radiation. Areas such as nuclear power plant buildings experience strong photon radiation, i.e., gamma rays. Areas such as nuclear power and reprocessing facilities experience strong single-electron or charged-particle radiation, i.e., beta rays. Different materials need to be selected for different types of radiation to achieve better radiation shielding. For example, in cases of strong neutron radiation, the helical blades 8 and central shaft 7 of the shielding unit can also be made of materials that have a certain neutron moderation and secondary radiation reduction effect, such as polyethylene, polypropylene, and epoxy resin. In cases of strong photon radiation, the helical blades 8 and central shaft 7 can also be made of metallic materials, such as carbon steel, stainless steel, cast steel, ductile iron, aluminum alloy, magnesium alloy, copper alloy, and tungsten. For single electron or charged particle radiation, the spiral blades 8 and the central shaft 7 can also be made of materials such as polyethylene, boron-containing polyethylene, lead / tungsten boron polyethylene, aluminum alloy, magnesium alloy, epoxy resin, boron-containing resin or lead / tungsten boron resin.

[0055] It should also be noted that in some nuclear facilities, the radiation situation is more complex, often involving mixed radiation fields containing multiple types of rays, such as neutrons, photons, and electrons. For these mixed radiations, multiple shielding units can be made of different materials. By installing multiple shielding units made of different materials within a through-hole, the mixed radiation can be effectively shielded.

[0056] Please see Figure 2 and Figure 3 In some embodiments, the outer diameter D of the helical blade 8 is 10-2000 mm, and the inner diameter d is 5-300 mm. Specifically, the outer diameter of the helical blade 8 of the shielding unit, i.e., the diameter of this shielding device, needs to be selected according to the diameter of the through hole. It is easy to see that the height of the helical channel is determined by the outer and inner diameters of the helical blade 8. When this shielding device is installed on the shielding body of different nuclear facilities, the function of the helical channel is different, and the required height of the helical channel is also different.

[0057] For example, when the helical channel is used for cable insertion, the outer diameter of the helical blade 8 is 10-600 mm and the inner diameter is 5-100 mm to allow the cable to pass through easily. In this case, the height of the helical channel allows the cable to pass through relatively easily. Furthermore, when the helical channel is used for media flow and exchange, to improve the efficiency of media flow, the outer diameter of the helical blade 8 can be 50-2000 mm and the inner diameter can be 10-300 mm. In this case, the cross-section of the helical channel increases, thereby improving the efficiency of media flow and exchange.

[0058] Furthermore, it can be seen that the radial length L1 of the helical blade is (Dd) / 2. When the shielding unit is used to shield high-level radioactive ionizing radiation or strong neutron radiation, the high-level radioactive radiation will release a large amount of heat. In order to improve the heat dissipation and heat conduction effect of the shielding device, the outer diameter of the helical blade 8 is 50-2000 mm, and the inner diameter is 10-300 mm. For example, the outer diameter of the helical unit is 1500 mm, the inner diameter of the helical blade 8 is 300 mm, and the radial length L1 is 600 mm. At this time, the helical channel has a large cross-section, thereby improving the heat dissipation effect. Moreover, the use of a large radial length L1 for the helical blade 8 can increase the contact area between the helical blade 8 and the central shaft 7 and the hot air, thereby improving the efficiency of heat conduction and heat transfer.

[0059] In some embodiments, to ensure the shielding effect of the helical blade 8, the thickness of the helical blade 8 should be no less than 1 mm. Specifically, when the through hole is used for cable installation, the thickness of the helical blade 8 is 1-100 mm. When the through hole is used for medium flow and exchange, heat dissipation, heat transfer, or ventilation, the thickness of the helical blade 8 is 5-200 mm. Furthermore, for high-level radioactive ionizing radiation or strong neutron radiation, due to their strong penetrating power, a larger thickness of the helical blade 8 should be selected. For example, when the shielding unit is used to shield against high-level radioactive radiation, the thickness of the helical blade 8 can be 150 mm.

[0060] Please see Figure 3In some embodiments, the preferred range for the elongation ratio of the helical blade 8 is 0.1-100. The elongation ratio of the helical blade 8 is the ratio of the axial length L2 of the helical blade 8 rotating around the central axis 7 to the maximum radial length L1 of the helical blade 8. It is easy to see that, with the maximum radial length L1 of the helical blade 8 remaining constant, a larger elongation ratio results in a larger axial length L2 of the helical blade 8 rotating around the central axis 7, and a lower degree of torsion in the helical channel; a smaller elongation ratio results in a smaller axial length L2 of the helical blade 8 rotating around the central axis 7, and a higher degree of torsion in the helical channel. In addition, it can be seen that, with the total axial length of the helical blade 8 remaining constant, reducing the elongation ratio of the helical blade 8 increases the number of rotations of the helical blade 8 around the central axis 7, thereby improving the shielding effect of the shielding unit.

[0061] Choosing a smaller elongation ratio for the helical blade 8 can improve the shielding effect, but it will cause the helical channel to twist too much, which is not conducive to the passage of cables and pipes. The elongation ratio of the helical blade 8 also needs to be selected according to the function of the helical channel.

[0062] Because cables cannot be excessively twisted, otherwise plastic deformation or even damage may easily occur, the elongation ratio of the helical blade 8 cannot be too small when the through hole is used for cable installation. The optimal range for the elongation ratio of the helical blade 8 when the through hole is used for cable installation is 0.2-100. When the through hole is used for media flow and exchange, heat dissipation, heat transfer, or ventilation, a smaller elongation ratio can be selected within the allowable range of the project to improve the shielding effect of the shielding unit. In this case, the optimal range for the elongation ratio of the helical blade 8 is 0.1-10.

[0063] Furthermore, when the shielding unit is used to shield against high-level radioactive ionizing radiation or strong neutron radiation, the helical blade 8 should have a smaller elongation ratio to achieve a good shielding effect. For example, the elongation ratio of the helical blade 8 can be 1, 2, etc.

[0064] Please continue reading. Figure 3 In some embodiments, the central shaft 7 of the shielding unit and the helical blade 8 are integrally formed. Of course, it is understood that the helical blade 8 and the central shaft 7 can also be connected through secondary assembly, such as bonding or welding. The helical blade 8 can be manufactured by casting, forging, 3D printing, milling, or machining.

[0065] Furthermore, the workers need to perform heat treatment, polishing, electroplating, coating and grinding on the outer surface of the spiral blade 8 to increase the surface strength and corrosion resistance of the spiral blade 8.

[0066] Furthermore, to verify the shielding effect of this variable cross-section shielding device, after the device is installed inside the through-hole, the personnel need to measure the shielding coefficient or radiation attenuation coefficient. The shielding coefficient is the ratio of the radiation dose inside the shielding body 10 to the radiation dose outside the shielding body 10. When the cross-sectional area of ​​the shielding device is less than or equal to 100 cm²... 2 When the maximum outer diameter of the spiral blade 8 is less than or equal to 10 cm, the shielding coefficient of this shielding device is not less than 10% of the shielding coefficient of the complete shielding body 10. When the cross-sectional area of ​​the shielding device is greater than 100 cm², the shielding coefficient of this shielding device is not less than 10% of the shielding coefficient of the complete shielding body 10. 2 When the maximum outer diameter of the spiral blade 8 is greater than 10cm, the shielding coefficient of this shielding device shall not be less than 50% of the shielding coefficient of the complete shielding body 10. If the shielding effect of this shielding device fails to meet the standard, the material and parameters of the shielding unit need to be reselected.

[0067] In summary, this variable cross-section shielding device has the following beneficial effects:

[0068] 1. This shielding device is easy to install and has excellent comprehensive radiation protection and shielding performance. By adjusting the parameters of a single shielding unit, or by combining multiple shielding units with different parameters and materials, it can shield various types of ionizing radiation rays or particles, and can meet the functions of cable installation, medium flow and exchange, and heat dissipation.

[0069] 2. This shielding device, while ensuring the shielding effect, does not weaken the shielding effect of the shielding body, nor does it affect the structural safety of the shielding body, and can ensure the safety of the overall structure.

[0070] 3. This shielding device does not require the installation of additional compensation shielding bodies and corresponding supporting facilities, which can save space, increase space utilization, and thus help improve the operating efficiency of nuclear facilities, as well as the smooth and safe flow of personnel and materials.

[0071] 4. This shielding device is easy to mass-produce in engineering projects, reducing the use of non-standard equipment and thus significantly reducing equipment procurement, processing and manufacturing costs and engineering construction costs.

[0072] 5. The engineering design and construction cycle of this shielding device is relatively short. The manufacturing of the shielding unit is independent of the construction of the nuclear facility and the shielding body, and can be carried out simultaneously. At the same time, this invention does not require the installation of additional compensation shielding and additional shielding bodies, nor does it require bending design or lengthening of the through holes in the shielding body, reducing the time required for secondary pouring construction and embedded part installation.

[0073] Example 2

[0074] Please see Figure 5a and Figure 5bThe present invention also discloses a nuclear facility shielding system, including a shielding body 10 and the variable cross-section shielding device in Embodiment 1.

[0075] The shielding body 10 is used to shield ionizing radiation. Specifically, the shielding body 10 is made of materials such as concrete, heavy concrete, steel / iron / lead sand, fiber, or silicone foam. Therefore, the shielding body 10 has good shielding performance and can effectively shield ionizing radiation.

[0076] A through-hole is provided in the shielding body 10 for the installation of cables and pipes, as well as for the flow and exchange of media. The vertical cross-section of the through-hole is tapered to accommodate the variable cross-section shielding device in Embodiment 1. The cross-sectional area of ​​the through-hole gradually decreases along the axial direction, with the larger end facing outwards from the shielding body 10 and the smaller end facing inwards, thereby reducing radiation entering the through-hole and radiation leakage. The through-hole is an flared through-hole, which is easy to process and shape, significantly reducing the manufacturing difficulty of the shielding body 10 and thus reducing the construction cost of the nuclear facility shielding system. In addition, the flared through-hole avoids the formation of a large number of voids inside the shielding body 10, thereby reducing the impact on the structural safety of the shielding body 10.

[0077] When installing the variable cross-section shielding device, the operator places it with the smaller cross-section end facing forward and inserts it into the through-hole from the larger cross-section end. The sidewall of the through-hole acts as a guide, allowing for easy installation without requiring extensive alignment. Then, pressure is applied to the larger cross-section section of the shielding device to secure it in place within the through-hole. The spiral blades 8 of the variable cross-section shielding device form a spiral channel with the inner wall of the through-hole, providing space for cable routing and media flow and exchange.

[0078] The variable shielding device can effectively shield radiation and radiation leakage, preventing nuclear radiation leakage. Designers no longer need to bend the through holes or significantly extend their length, thus reducing the volume of voids within the shielding body 10 and effectively avoiding potential radiation risks.

[0079] In some embodiments, specifically as follows Figure 5a As shown, the through-hole on the shield 10 extends vertically, and the cross-section of the through-hole gradually decreases vertically. At this point, the worker only needs to place the variable cross-section shielding device with the larger cross-section end facing upwards and the smaller cross-section end facing downwards inside the through-hole. The variable cross-section shielding device, under the influence of gravity, presses firmly against the sidewall of the through-hole. Even without additional pressure, it can be fixed inside the through-hole and will not detach or fall.

[0080] In some embodiments, a pressure difference exists between the inner and outer sides of the shielding body 10 of a nuclear facility. In this case, the end with the larger cross-section of the through-hole faces the side of the nuclear facility with higher pressure, and the end with the smaller cross-section faces the side of the nuclear facility with lower pressure. When installing the variable cross-section shielding device, the operator places the smaller cross-section end of the variable cross-section shielding device forward into the through-hole. The pressure difference on both sides of the shielding body 10 causes the variable cross-section shielding device to press against the side wall of the through-hole, thus fixing the variable cross-section shielding device inside the through-hole. Therefore, this variable cross-section shielding device is easy to install and also has high safety.

[0081] In some embodiments, the system further includes a barrier net 11, which is installed on the outside of the shield 10 and covers the through holes to prevent debris from falling into the spiral channel. Figure 5a As shown, the through hole is set vertically, with the end of the through hole with a larger cross-section facing upwards and the end with a smaller cross-section facing downwards. At this time, debris above the shield 10 is likely to fall into the through hole. By setting the barrier net 11, debris can be prevented from falling into the through hole and the spiral channel.

[0082] Furthermore, such as Figure 5b As shown, when the through hole on the shield 10 extends in the vertical direction, the shield 10 has a boss 12 at the upper end of the through hole. The boss 12 surrounds the variable cross-section shield unit to prevent liquid from flowing into the through hole and the spiral channel.

[0083] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A variable cross-section shielding device, characterized in that, include: The shielding device body (9). The shielding device body (9) is installed inside the through hole to shield ionizing radiation and radiation leakage. The shielding device body (9) extends along the axial direction of the through hole, and the diameter of the shielding device body (9) decreases along the axial direction of the through hole so that the vertical cross-section of the shielding device body (9) is conical. The end of the shielding device body (9) with the smaller cross-section is used to insert forward into the through hole. As the through hole extends vertically, the cross-section of the through hole gradually decreases vertically. The shielding device body (9) with the larger cross-section facing upward and the smaller cross-section facing downward is placed inside the through hole, and the shielding device body (9) presses against the inner wall of the through hole by its own weight. When there is a pressure difference between the inner and outer sides of the shield (10), the end with the larger cross-section of the through hole faces the side of the shield (10) with greater pressure, and the end with the smaller cross-section faces the side of the shield (10) with less pressure. The end with the smaller cross-section of the shielding device body (9) is inserted into the through hole. The pressure difference between the two sides of the shield (10) causes the shielding device body (9) to press against the inner wall of the through hole. The shielding device body (9) is composed of one or more shielding units. The shielding unit includes a central shaft (7) and a spiral blade (8). The central shaft (7) extends along the axial direction of the through hole. The spiral blade (8) is wound around the central shaft (7). The outer edge of the spiral blade (8) abuts against the inner wall of the through hole. The spiral blade (8) is used to scatter, slow down and absorb radiation to reduce radiation intensity and radiation energy. The elongation ratio of the helical blade (8) is 0.2-100, and the elongation ratio is the ratio of the axial length L2 of the helical blade rotating around the central axis to the maximum radial length L1 of the helical blade. Both the helical blade (8) and the central shaft (7) are made of a multi-component alloy material, which consists of metal hydride, boron carbide, tungsten and aluminum. The metal hydride is lithium hydride / titanium hydride / zirconium hydride, with a mass ratio of 1-20 wt%, boron carbide has a mass ratio of 2-20 wt%, tungsten has a mass ratio of 20-70 wt%, and aluminum has a mass ratio of 30-70 wt%. The number of the spiral blades (8) is selected based on the radioactivity intensity of ionizing radiation in the service environment: for low-level ionizing radiation, i.e., radioactive waste activity concentration greater than 8 × 10⁻⁶. 4 And less than or equal to 4 × 10 6 Bq / L or Bq / kg, the number of spiral blades (8) is 1-2, targeting intermediate radioactive ionizing radiation, i.e., radioactive waste activity concentration greater than 4×10⁻⁶. 6 And less than or equal to 4 × 10 10 Bq / L or Bq / kg, the number of spiral blades (8) is 3-6, targeting high radioactive ionizing radiation, i.e., radioactive waste activity concentration greater than 4×10⁻⁶. 10 Bq / L or Bq / kg, or strong neutron radiation, i.e., neutron source intensity greater than 100000n / s, and the number of the spiral blades (8) is 7-12.

2. The variable cross-section shielding device according to claim 1, characterized in that, The number of shielding units is multiple, and the multiple shielding units are fixedly connected sequentially along the axial direction of the through hole. The length of each shielding unit is greater than or equal to 10 mm, and the total length of multiple shielding units connected together does not exceed 200% of the thickness of the shielding body (10).

3. The variable cross-section shielding device according to claim 1, characterized in that, The outer diameter D of the helical blade is 10-2000 mm, and the diameter d of the central shaft is 5-300 mm.

4. The variable cross-section shielding device according to claim 1, characterized in that, Each shielding unit includes one or more helical blades (8), all of which are wound around the central shaft (7), and the central shaft (7) and the helical blades (8) are integrally formed.

5. The variable cross-section shielding device according to claim 4, characterized in that, The number of the spiral blades (8) is greater than or equal to two, and each spiral blade is arranged sequentially along the circumference of the central axis, and the distance between two adjacent spiral blades (8) is greater than 1 mm.

6. The variable cross-section shielding device according to claim 4, characterized in that, The number of the spiral blades (8) ranges from 1 to 12. The thickness of the spiral blade (8) is 1-200 mm.

7. A nuclear facility shielding system, comprising a shielding body (10) for shielding ionizing radiation and radiation leakage, wherein the shielding body (10) has a through hole, the vertical cross-section of which is conical, characterized in that, The system further includes the variable cross-section shielding device according to any one of claims 1-6. The variable cross-section shielding device is fixedly installed inside the through hole. The spiral blades (8) of the variable cross-section shielding device form a spiral channel with the inner wall of the through hole. The spiral channel is used for cable installation and medium flow and / or exchange.

8. The nuclear facility shielding system according to claim 7, characterized in that, It also includes a barrier net (11), which is installed on the outside of the shield and covers the through hole to prevent debris from falling into the spiral channel.

9. The nuclear facility shielding system according to claim 8, characterized in that, The through hole is arranged vertically, and the shield (10) has a boss (12) at the upper end of the through hole. The boss (12) is used to prevent liquid from flowing into the through hole.

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