A method for designing a multi-ray comprehensive shielding composite material

Abstract

The application provides a multi-ray comprehensive shielding composite material design method. Based on the neutron and gamma ray shielding physical process, the equivalent energy and equivalent intensity of three types of neutron rays and gamma rays in a radiation source are calculated respectively, and the required amount of the shielding component corresponding to each shielding step of each type of ray is calculated according to the calculation result. Finally, the multi-ray comprehensive shielding composite material component distribution is arranged according to the functions of the shielding components. Through the above method, the distribution of the shielding components in the matrix is regulated, so that the shielding components can participate in different rays and different shielding processes. On the premise of ensuring the good overall shielding performance of the material, the thickness of the shielding material is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear radiation shielding, in particular to a design method for a multi-ray integrated shielding composite material. Background Art

[0002] While the rapid development of nuclear technology has brought tremendous benefits to humanity, it also poses direct and indirect radiation hazards to the environment. Nuclear radiation primarily refers to neutrons and gamma rays of various energies, originating from radioactive sources, the natural environment, and cosmic rays. Nuclear radiation shielding materials, as specialized structural materials, are widely used in nuclear power plants, underwater and surface nuclear power plants, high-energy particle accelerators, spacecraft, and nuclear medicine diagnostic and treatment equipment.

[0003] Different components are required to moderate, absorb, and shield different types of nuclear radiation. When these shielding components are dispersed as particulate reinforcements within a matrix material, their distribution significantly impacts the composite's overall shielding efficiency. Given the current trend toward miniaturization and lightweighting of reactor components, the shielding layer must be reduced in thickness while maintaining good shielding performance. Therefore, achieving this reduction without sacrificing shielding performance is a key issue in improving the applicability of nuclear radiation shielding materials. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a design method for a multi-ray comprehensive shielding composite material. Based on the physical process of neutron and gamma ray shielding, the present invention calculates the equivalent energy and equivalent intensity of three types of neutron rays and gamma rays in the radioactive source, and calculates the required amount of shielding components corresponding to each shielding step of each type of ray based on the equivalent energy and equivalent intensity. Finally, the distribution of the components of the multi-ray comprehensive shielding composite material is arranged according to the function of each shielding component. The present invention regulates the distribution of the shielding components in the matrix through the above method, so that they can participate in different rays and different shielding processes, and reduce the thickness of the shielding material while ensuring good overall shielding performance of the material.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention provides a method for designing a multi-ray integrated shielding composite material. The multi-ray integrated shielding composite material comprises functional layers I to IV in order from the outside to the inside. The functional layers I to IV are composed of a matrix and a shielding component doped in the matrix. The shielding component in the functional layers I to IV is selected from any one or more of the following: shielding component (a) for absorbing gamma rays and heavy nuclear materials for moderating high-energy neutrons, shielding component (b) for moderating light nuclear materials for medium-energy neutrons, and shielding component (c) for absorbing low-energy neutrons.

[0007] The method comprises the following steps:

[0008] (1) Obtaining the equivalent energy and equivalent intensity of neutron rays in the radioactive source; in the technical solution of the present invention, the neutron rays include high-energy neutron rays, medium-energy neutron rays, and low-energy neutron rays; in certain specific embodiments, when writing a Monte Carlo calculation card in a simulation, the equivalent intensity of each neutron ray is represented by its ratio;

[0009] (2) Obtain the total content of each shielding component, including:

[0010] Calculating the content of each shielding component required for the neutron rays in the radioactive source during the first shielding action with the multi-ray integrated shielding composite material according to the equivalent energy and equivalent intensity of the neutron rays obtained in step (1); the first shielding action is the shielding action process between the initial neutron rays in the radioactive source and the multi-ray integrated shielding composite material;

[0011] Obtaining the content of each shielding component required for the neutron ray shielding process after the first shielding through a genetic algorithm②;

[0012] The total content of each shielding component required is obtained by adding the shielding component contents ① and ② obtained above;

[0013] (3) Arranging the hierarchical structure of the multi-ray integrated shielding composite material according to the total content of each shielding component calculated in step (2); the arranged hierarchical structure of the multi-ray integrated shielding composite material includes the type, content and layer thickness of the shielding components in each functional layer of the functional layers I to IV.

[0014] In the technical solution of the present invention, the substrate is a shielding substrate material commonly used in the art, specifically metals (stainless steel, aluminum alloy, etc.), polymers (polyethylene, epoxy resin, etc.), and concrete.

[0015] In the technical solution of the present invention, the shielding component (a) is selected from at least one of tungsten and lead; the shielding component (b) is selected from at least one of water, metal hydride and carbon; the shielding component (c) is preferably a material with a large thermal neutron absorption cross-section, such as at least one of gadolinium, boron / boron carbide, cadmium and samarium.

[0016] As a preferred embodiment, the calculation formulas for the equivalent energy ē and equivalent intensity I of the neutron ray are shown in formula (1) and formula (2):

[0017]

[0018] I=∑I x (2)

[0019] In formula (1) and formula (2): E xis the energy of a neutron in the neutron energy spectrum of the neutron ray, in MeV; I x The energy in the neutron energy spectrum of the neutron ray is E x The intensity of neutrons, in n / s;

[0020] In the technical solution of the present invention, the equivalent energy of a certain neutron ray is the average energy of the neutron group in the neutron ray; the equivalent intensity of a certain neutron ray is the sum of the intensities of the neutrons in the neutron ray.

[0021] As a preferred embodiment, in step (2), the calculation basis of the content ① of the shielding component is as shown in formula (3):

[0022]

[0023] In formula (3), I is the equivalent intensity of the ray; I' is the intensity of the ray after shielding, and the neutron transmittance (I':I) is ≤50%;

[0024] σ t is the microscopic reaction cross section of the target nucleus;

[0025] N is the surface density of the target core, that is, the atomic density of the shielding component in the matrix; the volume fraction of the shielding component in the matrix of each functional layer is equivalent to the surface density of the target core, which is 5% to 15%;

[0026] x is the thickness;

[0027] The product of N and x is the content of the shielding component①;

[0028] In the technical solution of the present invention, the content of the required shielding component ① can be calculated by the physical theoretical model of the interaction between neutrons and target nuclei. After setting the neutron transmittance (I' / I*100%), the microscopic reaction cross section σ of the target nucleus is known. t That is, the total content of the target nucleus (shielding component) required can be calculated (Formula 3). Therefore, when the radioactive source is known, the content of each shielding component required in each shielding process, the content of the shielding component specifically used to shield secondary gamma rays, and the thickness of each layer can be calculated according to Formula (3).

[0029] As a preferred embodiment, in step (3), the types of shielding components in each functional layer are as follows:

[0030] The functional layer I contains shielding components (a) to (c);

[0031] The functional layer II contains shielding components (a) to (c);

[0032] The functional layer III contains a shielding component (a) and a shielding component (c);

[0033] The functional layer IV contains a shielding component (a); in the technical solution of the present invention, the shielding component (c) releases secondary gamma rays when absorbing low-energy neutrons, so it is necessary to set the functional layer IV to absorb the secondary gamma rays.

[0034] As a preferred embodiment, in step (3), the shielding components in the functional layer I are tungsten, yttrium hydride and boron carbide; wherein, tungsten is used to moderate initial high-energy neutrons; yttrium hydride is used to moderate initial medium-energy neutrons; and boron carbide is used to absorb initial low-energy neutrons.

[0035] As a preferred embodiment, in step (3), the shielding components in the functional layer II are yttrium hydride, boron carbide and tungsten; wherein, yttrium hydride is used to moderate the medium-energy neutrons formed by the initial high-energy neutrons being moderated once through the functional layer I; boron carbide is used to absorb the low-energy neutrons formed by the initial medium-energy neutrons being moderated once through the functional layer I; and tungsten is used to shield the secondary gamma rays emitted by the initial low-energy neutrons during the absorption process of the functional layer I.

[0036] As a preferred embodiment, in step (3), the shielding components in the functional layer III are boron carbide and tungsten; wherein, boron carbide is used to absorb low-energy neutrons formed by secondary slowing down of initial high-energy neutrons by the functional layer II; and tungsten is used to shield secondary gamma rays emitted by initial medium-energy neutrons during the absorption process of the functional layer II.

[0037] As a preferred embodiment, in step (3), the shielding component in the functional layer IV is tungsten; wherein, tungsten is used to shield secondary gamma rays emitted during the absorption process of initial high-energy neutrons by the functional layer III.

[0038] As a preferred embodiment, in step (3), the arrangement of the content of the shielding component in each functional layer structure satisfies the following relationship:

[0039] ① The total content of any one of the shielding components in the multi-ray integrated shielding composite material is not less than the maximum content of the required shielding component calculated in step (2), and is preferably equal to the maximum content of the required shielding component calculated in step (2);

[0040] ② The shielding content of any one of the shielding components used to shield neutron rays I in the radioactive source is x, and the shielding content used to shield neutron rays II in the radioactive source is y, and the energy range of the neutron rays I is higher than that of the neutron rays II; the content of the shielding component between two adjacent layers satisfies the following relationship:

[0041] ix ≥ y, the layer for shielding radiation I containing the shielding component is closer to the surface than the layer for shielding radiation II containing the shielding component, and the content of the shielding component in the layer for shielding radiation I containing the shielding component is ≤ xy; the content of the shielding component in the layer for shielding radiation II containing the shielding component is ≥ y;

[0042] or;

[0043] ii. x<y, the content of the shielding component in the layer for shielding radiation II containing the shielding component is ≥y; the layer adjacent to and close to the surface of the layer for shielding radiation II containing the shielding component does not contain the shielding component;

[0044] In the technical solution of the present invention, the above arrangement can avoid the components in each layer from repeatedly playing the shielding role, and achieve the thinning effect when the usage ratio of each shielding component to the matrix of the multi-ray integrated shielding composite material is fixed.

[0045] Compared with the prior art, the present invention has the following advantages:

[0046] This invention provides a method for designing composite materials for multi-ray shielding. By leveraging different shielding physical processes and the order in which various shielding reactions occur, the distribution of multiple shielding components within the matrix material is regulated, thereby reducing the thickness of the shielding layer while simultaneously improving shielding efficiency. This method eliminates the need for individually screening a large number of samples. Instead, it uses shielding physics principles as a guide to design a distribution plan for shielding functional components, avoiding the complex experimental process associated with large-scale sample screening methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the distribution of various shielding components and the multifunctionality of each layer in Example 1 of the present invention.

[0048] Figure 2 Schematic diagram of controlling the interlayer content of shielding components to thin the material in Example 1 of the present invention.

[0049] Figure 3 This is a schematic diagram showing a comparison of the shielding efficiency simulations of a single shielding component in a layer and multiple shielding components in a layer in Example 1 of the present invention. DETAILED DESCRIPTION

[0050] The following embodiments are merely some of the embodiments of the present invention, rather than all of them. Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0051] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0052] Example 1

[0053] This embodiment provides a design method for a multi-ray integrated shielding composite material. The multi-ray integrated shielding composite material includes functional layers I to IV in order from the outside to the inside. The functional layers I to IV are composed of a matrix (316L stainless steel in this embodiment) and a shielding component doped in the matrix. The shielding component is selected from any one or more of tungsten, yttrium hydride, and boron carbide. Among them, tungsten can undergo inelastic scattering with high-energy neutrons to slow them down to medium-energy neutrons, and can also absorb gamma rays; yttrium hydride can undergo elastic scattering with medium-energy neutrons to slow them down to low-energy neutrons; and boron carbide can undergo an absorption reaction with low-energy neutrons and release secondary gamma rays.

[0054] The method comprises the following steps:

[0055] 1) Setting the energy spectrum of the radiation source: The radiation source in this embodiment is a neutron point distribution spectrum, where the energy of high-energy neutrons is 10 MeV and the energy of medium-energy neutrons is 10 -2 MeV, the energy of low-energy neutrons is 10 -5 MeV; the intensity ratio of the three types of neutron radiation is: high-energy neutron: medium-energy neutron: low-energy neutron = 1:1000:625000; since gamma-ray shielding only requires one absorption process, the presence of initial gamma rays in the radiation source is ignored in the actual operation case, and only neutron radiation of different energy types is set;

[0056] 2) Calculate the total amount of shielding components required for each neutron ray based on the radiation source energy spectrum in step 1):

[0057] First, the neutron transmittance Since the intensities of the three neutron rays are different, the ratio of the neutron transmittance for the three rays is: high energy neutron: medium energy neutron: low energy neutron = 10000:10:0.016; assuming the shielding rate for high energy neutrons is 5E-1, the shielding rate for medium energy neutrons is 5E-4, and for low energy neutrons it is 8E-7. By looking up the relationship between the target nucleus reaction cross section and neutron energy when the shielding component shields the corresponding rays, it can be found that the reaction cross section of tungsten for 10 MeV energy neutrons is about 0.2 barns, and for medium energy neutrons it is about 10 -2 The cross section of the MeV neutron reaction is 6 barns, and the low energy neutron reaction is 10 -5The reaction cross section of MeV neutrons is about 0 barns. According to formula (3), the product of the surface density N and the material thickness x is the atomic (target nucleus) amount of the shielding component. According to the shielding efficiency required by the three neutrons and the reaction cross section of the shielding component required for the first shielding reaction in this case, it can be seen that the ratio of the number of atoms of effective shielding elements in tungsten, yttrium hydride, and boron carbide is: 15:5:6. Since the intensity of low-energy neutrons is much higher than that of medium-energy neutrons and high-energy neutrons; the intensity of medium-energy neutrons is much higher than that of high-energy neutrons, the mass ratio of the above shielding materials is taken as the ratio of the total amount of each shielding material in the final material. That is, under the given radiation source intensity in this embodiment, there is no need to use a genetic algorithm to calculate the content of the corresponding shielding components required for subsequent reactions other than the first shielding reaction;

[0058]

[0059] 3) Layered arrangement of shielding components: The shielding components and their contents corresponding to the above-mentioned types of rays are designed. Figure 1 The distribution pattern shown is as follows: the first layer (i.e., the outermost layer) contains tungsten for moderating the initial high-energy neutrons, yttrium hydride for moderating the initial medium-energy neutrons, and boron carbide for absorbing the initial low-energy neutrons; the second layer contains yttrium hydride for moderating the medium-energy neutrons formed by the primary deceleration of the initial high-energy neutrons, boron carbide for absorbing the low-energy neutrons formed by the primary deceleration of the initial medium-energy neutrons, and tungsten for shielding the secondary gamma rays emitted during the absorption of the initial low-energy neutrons; the third layer contains boron carbide responsible for absorbing the low-energy neutrons formed by the secondary slowing of the initial high-energy neutrons, and for shielding the gamma rays emitted by the initial medium-energy neutrons during the absorption process in the second layer; the fourth layer of material is used to absorb the secondary gamma rays released when absorbing low-energy neutrons in the final step of the high-energy neutron shielding process;

[0060] Solutions with multiple shielding components per layer ( Figure 2 Right) and each layer contains a single shielding component ( Figure 2 In the left figure), the total content of each shielding component remains unchanged. Therefore, when a certain shielding component in a layer in the left figure is removed to another layer, the thickness of the layer where the shielding component originally resides can be reduced while ensuring that the mass percentage of the shielding component in the matrix remains unchanged ( Figure 2 The blue part of the right picture);

[0061] 4) Distribution of shielding components in each layer:

[0062] The total amount of each shielding material is roughly divided into Figure 2 In the distribution scheme shown in the right figure, and considering the subsequent manufacturability, the volume fraction of each shielding component in the matrix is ​​controlled at 5% to 15%;

[0063] In the ecard neutron transport simulation software based on Monte Carlo calculation, four layers of materials are set, the first layer of material has a shielding component atomic number ratio of tungsten: hydrogen: boron: iron = 30:5:4:500; the second layer of shielding component atomic number ratio is hydrogen: boron: tungsten: iron = 5:4:10:250; the third layer of shielding component atomic number ratio is boron carbide: tungsten: iron = 2:5:180; the fourth layer of shielding component atomic number ratio is tungsten: iron = 5:180, wherein the content of tungsten is obtained by genetic algorithm; the material thickness is set as 10mm for the first layer, 5mm for the second layer, 3.3mm for the third layer, and 3.3mm for the fourth layer, and the layers are arranged in close contact in order.

[0064] The total thickness of each layer of the nuclear shielding layer containing multiple shielding components obtained by the above setting in this embodiment is 21.6mm.

[0065] This embodiment also sets a control group containing only one shielding component in each layer, which is four layers of nuclear shielding materials with equal thickness, and the total thickness is 40mm, the shielding component atomic number ratio of the first layer of material is tungsten: iron = 48:100; the shielding component atomic number ratio of the second layer is hydrogen: iron = 4:100; the shielding component atomic number ratio of the third layer is boron carbide: iron = 16:100; the shielding component atomic number ratio of the fourth layer is tungsten: iron = 48:100.

[0066] The shielding efficiency simulation diagram of the above two nuclear shielding materials set in this embodiment is shown in Figure 3 From the Figure 3 It can be clearly seen from the visualization interface that the reflection and transmission rate of neutrons are both reduced, which indicates that the neutron absorption rate is improved, and the shielding design of multiple materials in each layer can better realize the integration of shielding layer function structure than the shielding design of single material in each layer, and conforms to the development trend of miniaturization and light weight of various reactors.

[0067] The above is only the preferred embodiment of the present application, it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for designing a multi-ray integrated shielding composite material, characterized in that: The multi-ray integrated shielding composite material comprises functional layers I to IV in order from the outside to the inside; the functional layers I to IV are composed of a matrix and a shielding component doped in the matrix; the shielding component in the functional layers I to IV is selected from any one or more of the following: shielding component (a) a heavy nuclear material for absorbing gamma rays and moderating high-energy neutrons, shielding component (b) a light nuclear material for moderating medium-energy neutrons, and shielding component (c) a material for absorbing low-energy neutrons; The method comprises the following steps: (1) Obtaining the equivalent energy and equivalent intensity of neutron rays in the radioactive source; the neutron rays include high-energy neutron rays, medium-energy neutron rays and low-energy neutron rays; (2) Obtain the total content of each shielding component, including: Calculating the content of each shielding component required for the neutron rays in the radioactive source during the first shielding action with the multi-ray integrated shielding composite material according to the equivalent energy and equivalent intensity of the neutron rays obtained in step (1) ①; the first shielding action is the shielding action process between the initial neutron rays in the radioactive source and the multi-ray integrated shielding composite material; Obtaining the content of each shielding component required for the neutron ray shielding process after the first shielding through a genetic algorithm②; The total content of each shielding component required is obtained by adding the shielding component contents ① and ② obtained above; (3) Arranging the hierarchical structure of the multi-ray integrated shielding composite material according to the total content of each shielding component calculated in step (2); the arranged hierarchical structure of the multi-ray integrated shielding composite material includes the type, content and layer thickness of the shielding components in each of the functional layers I to IV.

2. The method according to claim 1, characterized in that The matrix is ​​selected from any one of metal, polymer and concrete; The shielding component (a) is selected from at least one of tungsten and lead; the shielding component (b) is selected from at least one of water, metal hydride and carbon; and the shielding component (c) is selected from at least one of gadolinium, boron / boron carbide, cadmium and samarium.

3. The method according to claim 1, wherein In step (1), the calculation formulas for the equivalent energy Ē and equivalent intensity I of the neutron ray are shown in formula (1) and formula (2): （1） （2） In formula (1) and formula (2): E x is the energy of a neutron in the neutron energy spectrum of the neutron ray, in MeV; I x The energy in the neutron energy spectrum of the neutron ray is E x The intensity of neutrons, in n / s.

4. The method according to claim 1, wherein In step (2), the content of the shielding component ① is calculated according to formula (3): （3） In formula (3), I is the equivalent intensity of the ray; I' is the intensity of the ray after shielding, and the neutron transmittance (I':I) is ≤50%; σ ｔ is the microscopic reaction cross section of the target nucleus; N is the surface density of target nuclei, which is 5% to 15%; x is the thickness; The product of N and x is the content of the shielding component①.

5. The method according to claim 1, wherein In step (3), the types of shielding components in each functional layer are as follows: The functional layer I contains shielding components (a) to (c); The functional layer II contains shielding components (a) to (c); The functional layer III contains a shielding component (a) and a shielding component (c); The functional layer IV contains a barrier component (a).

6. The method according to claim 5, characterized in that In step (3), the shielding components in the functional layer I are tungsten, yttrium hydride and boron carbide.

7. The method according to claim 5, characterized in that In step (3), the shielding components in the functional layer II are yttrium hydride, boron carbide and tungsten.

8. The method according to claim 5, characterized in that In step (3), the shielding components in the functional layer III are boron carbide and tungsten.

9. The method according to claim 5, characterized in that In step (3), the shielding component in the functional layer IV is tungsten.

10. The method according to any one of claims 1 to 9, characterized in that: In step (3), the arrangement of the content of the shielding component in each functional layer structure satisfies the following relationship: ① The total content of any one of the shielding components in the multi-ray integrated shielding composite material is not less than the maximum content of the required shielding component calculated in step (2); ② The shielding content of any one of the shielding components used to shield neutron rays I in the radioactive source is x, and the shielding content used to shield neutron rays II in the radioactive source is y, and the energy range of the neutron rays I is higher than that of the neutron rays II; the content of the shielding component between two adjacent layers satisfies the following relationship: i. x ≥ y, the layer for shielding radiation I comprising the shielding component is closer to the surface than the layer for shielding radiation II comprising the shielding component, and the content of the shielding component in the layer for shielding radiation I comprising the shielding component is ≤ xy; the content of the shielding component in the layer for shielding radiation II comprising the shielding component is ≥ y; or; ii. x<y, the content of the shielding component in the layer for shielding radiation II comprising the shielding component is ≥y; the layer adjacent to and close to the surface of the layer for shielding radiation II comprising the shielding component does not contain the shielding component.

11. The method according to claim 10, characterized in that In relationship ①, the total content of any one of the shielding components in the multi-ray integrated shielding composite material is equal to the maximum value of the required content of the shielding component calculated in step (2).

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