Neutron shielding multilayer structure

Abstract

Provided is a structure having excellent neutron shielding properties. When designing a neutron-shielding structure, the structure is made into a multilayer structure (1) in which at least two or more first layers (2) comprising a resin or an elastomer and at least two or more second layers (3) comprising a resin or an elastomer and inorganic fiber bundles containing a neutron-absorbing element are laminated. The neutron shielding properties of the multilayer structure (1) are superior to those of conventional particle dispersed structures even with the same neutron absorbing element content.

Description

(19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number (43) Application Publication Date (21) Application Number 202480040766.4 (22) Application Date 2024.06.03 (30) Priority Data 2023-108928 2023.06.30 JP (85) PCT International Application Entering National Phase Date 2025.12.18 (86) PCT International Application Application Data PCT / JP2024 / 020181 2024.06.03 (87) PCT International Application Publication Data WO2025 / 004698 JA 2025.01.02 (71) Applicant: New Japan Fiber Co., Ltd. Address: Chiba Prefecture, Japan (72) Inventor: Yu Fukasawa (74) Patent Agency: Beijing Runping Intellectual Property Agency Co., Ltd. 11283 Patent Attorney Liu Bing (51) Int.Cl. G21F 3 / 00 (2006.01) B32B 5 / 28 (2006.01) G21F 1 / 10 (2006.01) (54) Invention Title: Neutron-Shielding Multilayer Structure (57) Abstract: This invention provides a structure with excellent neutron shielding properties. In designing the neutron-shielding structure, the structure is made into a multilayer structure (1), which is formed by laminating at least two first layers (2) composed of resin or elastomer and at least two second layers (3) formed by inorganic fiber bundles containing neutron-absorbing elements and resin or elastomer. Even with the same neutron-absorbing element content, the neutron shielding properties of this multilayer structure (1) are superior to those of conventional particle-dispersed structures. Claims 1 page, Description 7 pages, Drawings 6 pages, CN 121532837 A 2026.02.13 CN 1 21 53 28 37 A 1. A multilayer structure, which is a neutron-shielding multilayer structure that separates a neutron source from a protected object, said multilayer structure being formed by laminating at least one first layer and at least one second layer formed by neutron-absorbing inorganic fiber bundles and said resin or elastomer. 2. The multilayer structure according to claim 1, wherein the total mass of one or more elements selected from gadolinium, samarium, and cadmium accounts for more than 10% by mass in said inorganic fiber bundles. 3. The multilayer structure according to claim 2, wherein said inorganic fiber bundle is any one of fiber cloth, roving, roving cloth, diced felt, ground fiber, nonwoven fabric, and fiber felt. 4. The multilayer structure according to claim 3, wherein said resin or elastomer of the first layer is the same as that of the second layer. 5. The multilayer structure according to claim 4, wherein the layer closest to the protected object is formed by a second layer.6. The multilayer structure according to claim 4, wherein the layer closest to the neutron source is formed by a first layer. 7. The multilayer structure according to claim 5 or 6, wherein there are two or more first layers and second layers. 8. The multilayer structure according to claim 7, wherein the thickness of each first layer increases sequentially from the side closest to the protected object to the side closest to the neutron source. 9. The multilayer structure according to claim 7, wherein the thickness of each second layer increases sequentially from the side closest to the neutron source to the side closest to the protected object. 10. The multilayer structure according to claim 7, wherein, with respect to each second layer, from the side closest to the neutron source to the side closest to the protected object, i) the content of inorganic fiber bundles per unit volume of each layer increases sequentially; or ii) the volume porosity of the inorganic fiber bundles constituting each layer decreases sequentially; or iii) the content of neutron-absorbing elements (gadolinium, samarium, cadmium) in the inorganic fiber bundles constituting each layer increases sequentially. 11. A multilayer structure, which is a neutron-shielding multilayer structure separating a neutron source from a protected object, said multilayer structure being composed of at least two laminated layers formed of neutron-absorbing inorganic fiber bundles and resin or elastomer, having the following configuration: from the side closest to the neutron source to the side closest to the protected object, i) the content of inorganic fiber bundles per unit volume of each layer sequentially increases; or ii) the volume porosity of the inorganic fiber bundles constituting each layer sequentially decreases; or iii) the content of neutron-absorbing elements (gadolinium, samarium, cadmium) in the inorganic fiber bundles constituting each layer sequentially increases. 12. The multilayer structure according to claim 10, wherein the resin is a bisphenol A type epoxy resin or a cured product of hydrogenated bisphenol A type epoxy resin. 13. The multilayer structure according to claim 11, wherein the resin is a bisphenol A type epoxy resin or a cured product of hydrogenated bisphenol A type epoxy resin. 14. The method for manufacturing a multilayer structure according to claim 10, wherein it utilizes an injection molding method. 15. The method for manufacturing a multilayer structure according to claim 11, wherein it utilizes an injection molding method. Claims 1 / 1 Page 2 CN 121532837 A Multilayer Structure with Neutron Shielding Technical Field

[0001] The present invention relates to a multilayer structure with excellent neutron shielding. Background Art

[0002] With the advancement of nuclear energy-related technologies and aerospace technologies, the necessity of neutron shielding materials has increased more than ever before.

[0003] There is a continuous demand to improve the performance of neutron shielding materials in order to protect humans from neutron radiation. Furthermore, when focusing on the electronic equipment necessary for controlling nuclear energy facilities or space-related machines, the "soft error" of communication devices is gradually increasing due to the high integration of semiconductors mounted on these electronic equipment.Soft errors refer to the inversion of bit data caused by neutrons from cosmic rays entering semiconductor elements, resulting in malfunctions of electronic devices. Therefore, materials that can effectively shield against neutrons are required not only to protect humans but also to protect electronic devices.

[0004] Concrete has been known as a representative example of neutron shielding materials, but it is not suitable for precision-machined parts such as the casings of electronic devices. As an alternative material, a material combining a neutron shielding substance and a resin has been proposed.

[0005] For example, Japanese Patent Application Publication No. 6-180388 (Patent Document 1) discloses a heat-resistant neutron shielding material made by incorporating inorganic boron compounds, gadolinium oxide, etc., into a phenolic resin as a thermal neutron shielding substance. In addition, Japanese Patent Application Publication No. 2020-30088 (Patent Document 2) discloses a resin composition made by incorporating boron carbide, boric acid, gadolinium, or mixtures thereof within a specific particle size range into a hardening resin. Both inventions described in Patent Documents 1 and 2 involve adding neutron-absorbing "powder" raw materials to resin materials.

[0006] On the other hand, the inventors have developed inorganic fibers with excellent neutron shielding properties containing high amounts of gadolinium and the like (WO2022 / 145401 A1, Patent Document 3).

[0007] [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Publication No. 6-180388 [Patent Document 2] Japanese Patent Application Publication No. 2020-30088 [Patent Document 3] International Publication WO2022 / 145401 A1 Summary of the Invention [Problems to be Solved by the Invention] Both inventions in Patent Documents 1 to 3 use rare earth elements such as gadolinium and samarium as neutron-absorbing elements. Therefore, from the viewpoint of effectively utilizing rare resources, it is ideal to use materials that suppress the amount of rare earth elements used and maximize the neutron shielding function of these elements.

[0008] Therefore, the inventors conducted research on creating a neutron shielding structure that suppresses the amount of neutron-absorbing elements used and maximizes neutron shielding performance.

[0009] [Technical means to solve the problem] As a result, it was found that in a composite material in which a material containing neutron-absorbing elements is filled into a base material such as resin, the material containing neutron-absorbing elements is filled in the form of fiber bundles rather than particles, which is superior in terms of neutron shielding performance.

[0010] That is, the present invention is a neutron-shielding multilayer structure, which is a multilayer structure formed by laminating at least one first layer composed of resin or elastomer and at least one second layer formed by neutron-shielding inorganic fiber bundles and resin or elastomer.In the multilayer structure of the present invention, the first layer functions to attenuate the energy of neutrons (decelerate the velocity of neutrons), and the second layer functions to absorb the decelerated neutrons.

[0011] [Effects of the Invention] In the multilayer structure of the present invention, the material containing neutron-absorbing elements filling the parent material is in the form of inorganic fiber bundles rather than powder, thus providing superior neutron shielding. Furthermore, since the filling material is inorganic fiber bundles, layers that attenuate neutrons and layers that absorb neutrons can be effectively configured and formed within the structure. Brief Description of the Drawings

[0012] FIG1 is a schematic diagram showing the layer structure of the multilayer structure of the present invention.

[0013] FIG2 is a schematic diagram showing a conventional neutron shielding structure in which the material containing neutron-absorbing elements is powder.

[0014] FIG3 is a graph showing the results of PHITS calculations.

[0015] FIG4 is a partially enlarged view of the graph in FIG3.

[0016] FIG5 is a schematic diagram of two examples of multilayer structure models used in PHITS calculations.

[0017] FIG6 is another graph showing the results of the PHITS calculation.

[0018] FIG7 is a graph showing a preferred configuration of the multilayer structure of the present invention.

[0019] FIG8 is a graph showing another preferred configuration of the multilayer structure of the present invention.

[0020] FIG9 is a graph showing another preferred configuration of the multilayer structure of the present invention.

[0021] FIG10 is a graph showing yet another preferred configuration of the multilayer structure of the present invention. Detailed Description

[0022] Hereinafter, the multilayer structure of the present invention will be described with appropriate use of figures.

[0023] In the present invention, neutron-absorbing inorganic fibers are used as the neutron-absorbing component, instead of the conventionally used neutron-absorbing inorganic powder. Inorganic fibers can be made into fiber bundles of various shapes by forming them together, and combined with resin or elastomer to form a composite material in which the fiber bundles are arranged in layers in the base material of the resin or elastomer. The multilayer structure of the present invention is formed by maximizing the above-mentioned advantages of the fiber bundles.

[0024] FIG1 shows the basic configuration of the present invention. In the figure, the multilayer structure (1) is positioned in the middle to prevent the protected object (O) from being irradiated by neutrons.

[0025] The multilayer structure (1) is composed of two layers (i.e., the first layer (2) and the second layer (3)). The first layer (2) and the second layer (3) each have at least one layer participating in the construction of the multilayer structure (1). By combining the first layer (2) and the second layer (3) into two or more layers respectively, the ratio of the neutron-shielding inorganic fiber bundles present in the multilayer structure (1) increases from the neutron source (S) toward the protected object (O).

[0026] The first layer (2) is composed of resin (or elastomer). The second layer (3) is composed of neutron-shielding inorganic fiber bundles and resin (or elastomer).

[0027] Here, the resin (or elastomer) constituting the first layer (2) and the resin (or elastomer) constituting the second layer (3) need not be the same. However, by making the resin (or elastomer) constituting the first layer (2) and the resin (or elastomer) constituting the second layer (3) the same, the manufacturing process of the multilayer structure (1) as the final product can be simplified, and therefore it is preferred.

[0028] The resin (or elastomer) is used as a common component of the first layer (2) and the second layer (3). In addition, the term "base material" is sometimes used for the resin (or elastomer) involved in the formation of the second layer (3).

[0029] Hereinafter, the resin or elastomer used in the present invention will be described.

[0030] According to the molding method of the multilayer structure (1), the resin (or elastomer) can be of any type, such as thermosetting or thermoplastic. From the viewpoint of emphasizing the heat resistance or strength of the multilayer structure (1), a thermosetting type is preferred, but a thermoplastic type can also be used considering production efficiency. In addition, resins and elastomers containing a large amount of hydrogen in the molecular skeleton are more preferred because they increase the performance of neutron deceleration.

[0031] When the multilayer structure (1) requires moderate flexibility, an elastomer is used instead of a resin.

[0032] Examples of curing resins include epoxy resins, unsaturated polyester resins, vinyl ester resins, bismaleimide resins, and phenolic resins, but are not limited to these. From the viewpoint of neutron shielding, among these, it is preferred to have a large amount of hydrogen in the skeleton. Examples of such curing resins include bisphenol A type epoxy resins, and further examples include hydrogenated bisphenol A type epoxy resins. The above-mentioned thermosetting resins are ultimately thermosetting by using a curing agent and become components of the first layer (1) and the second layer (3).

[0033] Examples of thermoplastic resins include polypropylene, polyethylene, polystyrene, ABS resin, polyphenylene ether, polycarbonate, and polyamide, but these are not limited to. Among these, polypropylene and polyethylene are preferred because they are not only inexpensive but also contain a large amount of hydrogen in their molecular backbone.

[0034] As elastomers, both thermosetting elastomers and thermoplastic elastomers can be used.

[0035] Examples of thermosetting elastomers (including their cured forms) include ethylene propylene rubber (EPDM), nitrile rubber (NBR), acrylic rubber (ACM), urethane rubber (PUR), silicone rubber, ethylene-vinyl acetate rubber (EVA), and epichlorohydrin rubber (ECO). They all have excellent weather resistance, and ethylene propylene rubber (EPDM) and silicone rubber are preferred because they contain a large amount of hydrogen in their molecular backbone.

[0036] Examples of thermoplastic elastomers include: polystyrene-based thermoplastic rubber, polyolefin-based thermoplastic rubber, polyurethane-based thermoplastic rubber, polyester-based thermoplastic rubber, polyamide-based thermoplastic rubber, and polyvinyl chloride-based thermoplastic rubber.

[0037] Examples of polystyrene-based thermoplastic rubbers include: styrene-ethylene-butene-styrene block copolymer (SEBS) and styrene-ethylene-propylene-styrene block copolymer (SEPS).

[0038] Among the above thermoplastic elastomers, ethylene propylene rubber (EPDM), polyolefin-based thermoplastic rubber, styrene-ethylene-butene-styrene block copolymer (SEBS), and styrene-ethylene-propylene-styrene block copolymer (SEPS) have excellent weather resistance and contain a large amount of hydrogen in their molecular backbone, and are therefore more preferred.

[0039] The second layer (3) constituting the multilayer structure (1) of the present invention comprises the above-mentioned resin or elastomer and inorganic fiber bundles. In this invention, inorganic fiber bundles refer to secondary processed products of fiber cloth, roving, roving fabric, woven felt, nonwoven fabric, fiber felt, and other inorganic fibers. They can be appropriately selected according to the forming method.

[0040] In this invention, the inorganic fibers that form the basis of the inorganic fiber bundle contain a high content of any one of gadolinium, samarium, or cadmium, which are rich in neutron absorption. More specifically, the inorganic fiber oxide preferably contains at least 10% by mass of any one of gadolinium, samarium, or cadmium, more preferably at least 20% by mass, more preferably at least 30% by mass, and most preferably at least 40% by mass.

[0041] Furthermore, regarding gadolinium, samarium, and cadmium, two or more of them may be contained, with gadolinium having overwhelmingly superior neutron absorption. Therefore, in order to improve the neutron absorption per unit mass of inorganic fiber, it is preferable to contain gadolinium at least 10% by mass (calculated as oxides), more preferably at 20% by mass, more preferably at 30% by mass, and most preferably at 40% by mass.

[0042] In manufacturing inorganic fiber, any one of these three elements (metals) or oxides can be used as raw material.

[0043] In addition to the above three elements as essential components, the inorganic fiber also contains known oxides with excellent glass-forming properties, namely silicon oxide and aluminum oxide, as main components. In addition, calcium oxide may also be included as a secondary component.

[0044] The second layer (3) is composed of inorganic fiber bundles and resin (or elastomer), and more specifically, it is a structure in which the voids of the inorganic fiber bundles are filled by the same parent material (resin or elastomer) that forms the first layer (2) as described above.

[0045] The proportion of the inorganic fiber bundle in the total mass of the second layer (3) is 10 to 95% of the mass.From the viewpoint of improving the neutron absorption efficiency of the second layer (3), it is preferable to be 25% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more.

[0046] The proportion of the inorganic fiber bundle in the total mass of the second layer (3) depends largely on the volume porosity (void fraction) of the inorganic fiber bundle, and can also be adjusted by the specific molding method of combining the inorganic fiber bundle with the resin (or elastomer).

[0047] Therefore, when increasing the proportion of the inorganic fiber bundle in the total mass of the second layer (3), it can be adjusted by using an inorganic fiber bundle with a small volume porosity and increasing the pressure when molding the inorganic fiber bundle with the parent material (resin or elastomer) as needed.

[0048] Considering the above, when manufacturing the second layer (3), if a hardened resin or hardened elastomer is used as the parent material, it can be obtained by impregnating the prepolymer of the resin or elastomer into the inorganic fiber bundle, and then by pressurizing and heating.

[0049] As a specific molding method, known methods such as autoclave molding, injection molding, and hand-forming can be appropriately employed.

[0050] On the other hand, when using thermoplastic resin or thermoplastic elastomer as the base material, for example, a sheet containing thermoplastic resin or thermoplastic elastomer can be prepared in advance, and the sheet can be overlapped with a fiber cloth and heated and pressurized to obtain the product. As an example of heating and pressing molding, calendering can be cited.

[0051] In the present invention, since the resin or elastomer forming the first layer (2) and the second layer (3) are the same, although the first layer (2) and the second layer (3) can be produced in different processes and then laminated to form the target multilayer structure, in the case where the base material is thermosetting, the following molding method can be used to simplify the process.

[0052] That is, if inorganic fiber bundles (e.g., fiber cloth) are overlapped in the form of multiple layers in advance, and then impregnated with a prepolymer of the parent material, and the pressure, temperature and time are adjusted, a first layer (2) consisting only of the parent material and a second layer (3) consisting of inorganic fiber bundles impregnated in the parent material can be formed between the aforementioned inorganic fiber bundles in one process.

[0053] The ratio of the first layer (2) and the second layer (3) in the multilayer structure (1) is not particularly limited, but it is preferably the ratio of the total thickness of the first layer (2) to the total thickness of the second layer (3) is in the range of 10 / 90 to 90 / 10.

[0054] The multilayer structure (1) of the present invention is formed by laminating at least one first layer (2) and at least one second layer (3).

[0055] In a multi-layer structure consisting of a first layer (2) and a second layer (3), of course, the first layer (2) is disposed on the neutron source side and the second layer (3) is disposed on the protected object side.

[0056] However, the inventors used Monte Carlo particle calculation code to perform simulations, and the results showed that when both the first layer (2) and the second layer (3) are two or more multilayer structures (1), if the outermost layer on the protected object side is the first layer (2), the neutron shielding performance unexpectedly deteriorates. Therefore, it is preferable that the layer closest to the protected object is the second layer (3). Based on this insight, it was found that in a multilayer structure (1) where the layer closest to the protected object is the first layer (i.e., the neutron deceleration layer), the presence of the first layer (2) impairs the neutron shielding performance of the multilayer structure (1) even if it is thin. Therefore, in this multilayer structure, it is preferable that the layer closest to the protected object is the second layer (3).

[0057] The simulation results will be mentioned below. Although various Monte Carlo particle calculation codes are known and used, the inventors used the Monte Carlo particle transport calculation code known as PHITS (Particle and Heavy Ion Transport code System). PHITS can be obtained from the website of the Japan Nuclear Energy Agency (https: / / phits.jaea.go.jp / indexj.html), and the method of using it has been disclosed.

[0058] Figure 3 shows the result of calculating the energy spectrum of the transmitted neutron beam when a neutron beam of a specified energy spectrum is irradiated onto the multilayer structure (1) using the above calculation code.

[0059] Here, the energy spectrum of the incident neutron is the thermal neutron furnace neutron spectrum.

[0060] In addition, the thickness of the multilayer structure (1) is set to 30 mm, the bisphenol A epoxy resin hardened body is assumed to be the first layer (2), and the gadolinium-containing inorganic fiber cloth is assumed to be the second layer (3). In addition, for ease of calculation, the second layer (3) is assumed to be composed only of inorganic fiber cloth, and the volume porosity of the inorganic fiber cloth is set to 0.5.

[0061] The following is the premise of the multilayer structure model used in the calculation.

[0062] The ratio of the total thickness of the first layer (2) to the total thickness of the second layer (3): 90 / 10 The mass ratio of the first layer (2): Bisphenol A / hardener: 80 / 20 The composition of the second layer (3) (the composition of the inorganic fiber cloth): Gadolinium oxide (Gd2O3) 10% by mass, silicon dioxide (SiO2) 48% by mass, aluminum oxide (Al2O3) 15% by mass, iron oxide (Fe2O3) 9% by mass, calcium oxide (CaO) 10% by mass, boron oxide (B2O3) 5% by mass, potassium oxide (K2O) 2% by mass The number of the first layer (2): 20 (each has the same thickness) The number of the second layer (3): 19 (each has the same thickness) In addition, as a comparative structure relative to this multilayer structure model, a particle dispersion structure (Fig. 2) is also used. Calculations were performed, and the particle-dispersed structure contained gadolinium oxide in the same amount as the second layer of the multilayer structure model in the same resin as the first layer of the multilayer structure model. Furthermore, the particle size was set to 0.50 mm. The calculation results are shown in Figure 3.

[0063] As can be seen from Figure 3, in the region where the neutron energy is below 10⁻⁷ MeV, the multilayer structure of the present invention exhibits superior neutron shielding compared to conventional particle-dispersed structures.

[0064] Figure 4 is a partial enlarged view of Figure 3 focusing on the region where the neutron energy is below 10⁻⁷ MeV.

[0065] The above calculation results suggest the advantage of a layered localized distribution of neutron-absorbing elements in the parent resin.

[0066] In the above calculations, a configuration was adopted where the outermost layer on the protected object side was the first layer (2R) (Figure 5(a)). However, compared with a model where this first layer was moved to the forefront on the neutron source side (Figure 5(b)), the results were contrary to expectations, with further improvement in neutron shielding (Figure 6).

[0067] The same calculation results were confirmed even in the simplest model.

[0068] That is, for a two-layer structure model consisting of one first layer (2) (neutron source side) and one second layer (3) (protected object side), when compared with a model in which another first layer of the same thickness is added and deposited on the back of the second layer of the two-layer structure, the neutron shielding of the latter multilayer structure is found to be worse.

[0069] Therefore, the multilayer structure (1) of the present invention is preferably formed with the second layer (3) (neutron absorption layer) as the outermost layer on the protected object side. Specification 5 / 7 pages 7 CN 121532837 A

[0070] However, in the FRP molding of fiber bundles and thermosetting resin, the surface of the molded article is usually covered by layers of different thicknesses consisting only of the parent material.Therefore, when manufacturing the multilayer structure (1) of the present invention, taking into account the above calculation results, care should be taken to avoid forming the first layer (2) (a layer composed only of resin or elastomer) in the layer closest to the object being protected (outermost layer), or even if it is formed, to make it as thin as possible.

[0071] Based on this view, when using a curing resin (or elastomer) to manufacture the multilayer structure (1) of the present invention, among the many thermosetting molding methods, injection molding or filament winding molding is a more preferred molding method.

[0072] In particular, injection molding is a molding method in which fiber bundles such as fiber cloth or non-woven fabric are sandwiched between the film of the upper mold and the lower mold, maintaining the airtightness of the film, and at the same time using vacuum pressure to draw resin for filling and impregnation. Therefore, it has the advantages of less resin (or elastomer) seepage to the surface of the molded article and is also easy to apply to molded articles with unevenness.

[0073] When the multilayer structure (1) of the present invention has two or more first layers (2), the configuration of these first layers (2) may also be such that the thickness of the layers increases sequentially from the layer (2R) closest to the object being protected to the layer (2F) closest to the neutron source (Fig. 7).

[0074] In addition, when the multilayer structure (1) of the present invention has two or more second layers (3), the following variations may be adopted for these second layers (3).

[0075] That is, the following changes: Regarding each of the multiple second layers (3), from the layer (3F) closest to the neutron source to the layer (3R) closest to the object being protected, i) the thickness of each layer increases sequentially [thickness increase pattern of each layer] (Fig. 8); ii) the content of inorganic fiber bundles per unit volume of each layer increases sequentially [increase in inorganic fiber bundle content of each layer (or decrease in volume porosity of inorganic fiber bundles) pattern] (Fig. 9); iii) the content of neutron-absorbing elements (gadolinium, samarium, cadmium) constituting the inorganic fiber bundles of each layer increases sequentially [neutron-absorbing element concentration increase pattern of each layer] (Fig. 10).

[0076] The above variations can be combined. That is, variations i) and ii) are combined, variations ii) and iii) are combined, variations i) and iii) are combined, and all variations i), ii) and iii) are combined.

[0077] As an improvement to the multilayer structure of the present invention, a multilayer structure can also be adopted in which two or more of the above-mentioned second layer, namely, the laminated layer composed of neutron-shielding inorganic fiber bundles and resin (or elastomer), are substantially formed.

[0078] More specifically, the following multilayer structure can be listed, which is composed of two or more laminated layers composed of resin (or elastomer) and inorganic fiber bundles, and is configured such that, from the layer closest to the neutron source to the layer closest to the object being protected, a) the content of inorganic fiber bundles per unit volume of each layer increases sequentially; or b) the content of neutron-absorbing elements (gadolinium, samarium, cadmium) in the inorganic fiber bundles constituting each layer increases sequentially.

[0079] Regarding the multilayer structure with the above-described configuration, known methods such as autoclave molding, injection molding, and hand-forming can also be suitably employed.

[0080] [Industrial Applicability] The multilayer structure of the present invention exhibits excellent neutron shielding properties. Furthermore, since it is composed of an inorganic fiber bundle filling material with resin or elastomer as the matrix, it offers a higher degree of shape freedom compared to concrete-based materials. Therefore, it is suitable as equipment, machinery, and components in various fields such as nuclear energy, aerospace, and medicine.

[0081] Examples of equipment, machinery, and components in the field of nuclear energy include: equipment, machinery, and components for nuclear power generation; equipment, machinery, and components for preventing criticality reactions in operations related to the extraction and storage of molten nuclear fuel; equipment, machinery, and components for the mining and processing of uranium ore; equipment, machinery, and components for the secondary processing of nuclear fuel (including conversion, enrichment, reconversion, shaping, and MOX manufacturing); equipment, machinery, and components for the storage, processing, and reprocessing of used nuclear fuel; equipment, machinery, and components for the storage, processing, and disposal of neutron radiation waste; machinery and components for transporting uranium ore, secondary processed nuclear fuel, used nuclear fuel, or neutron radiation waste; and other nuclear-related equipment, machinery, and components.

[0082] More specific examples of the equipment, machinery, and components used for nuclear power generation described above include: nuclear reactor buildings (including research and experimental reactors), nuclear reactor storage containers, piping within nuclear reactor facilities, and robots for waste disposal.

[0083] Examples of equipment, machinery, and components used in the aerospace field include: space base buildings, space stations, artificial satellites, planetary exploration satellites, etc.

[0084] Examples of equipment, machinery, and components used in the medical field include: medical devices utilizing particle rays.

[0085] The above examples are provided to demonstrate the usefulness of the composite materials of the present invention and do not limit the scope of the invention.

[0086] [Symbol Explanation] 1: Multilayer structure 2: First layer 2F: First layer closest to the neutron source 2R: First layer closest to the protected object 3: Second layer 3F: Second layer closest to the neutron source 3R: Second layer closest to the protected object 4: Conventional neutron shielding structure 5: Dispersed particles 6: Resin S: Neutron source O: Protected object Specification 7 / 7 page 9 CN 121532837 A Figure 1 Figure 2 Specification Figure 1 / 6 page 10 CN 121532837 A Figure 3 Figure 4 Specification Figure 2 / 6 page 11 CN 121532837 A Figure 5 Specification Figure 3 / 6 page 12 CN 121532837 A Figure 6 Figure 7 Specification Figure 4 / 6 page 13 CN 121532837 A Figure 8 Figure 9 Specification Figure 5 / 6 page 14 CN 121532837 A Figure 10 Specification Figure 6 / 6 page 15 CN 121532837 A.

Claims

1. A multi-layered structure, which is a neutron-shielding multi-layered structure that separates a neutron source from the object to be protected. The multi-layer structure is Comprising at least one or more first layers, and It consists of at least one second layer formed by neutron-absorbing inorganic fiber bundles and the resin or elastomer.

2. The multilayer structure according to claim 1, wherein the total mass of one or more elements selected from gadolinium, samarium, and cadmium accounts for more than 10% by mass in the inorganic fiber bundle.

3. The multilayer structure according to claim 2, wherein the inorganic fiber bundle is any one of fiber cloth, roving, roving cloth, diced felt, ground fiber, nonwoven fabric, or fiber felt.

4. The multilayer structure according to claim 3, wherein the resin or elastomer of the first layer is the same as the resin or elastomer of the second layer.

5. The multilayer structure according to claim 4, wherein the layer closest to the protected object is formed by a second layer.

6. The multilayer structure according to claim 4, wherein the layer closest to the neutron source is formed by the first layer.

7. The multilayer structure according to claim 5 or 6, wherein the first layer and the second layer are both two or more.

8. The multilayer structure according to claim 7, wherein the thickness of each first layer increases sequentially from the side closest to the protected object to the side closest to the neutron source.

9. The multilayer structure according to claim 7, wherein the thickness of each second layer increases sequentially from the side closest to the neutron source to the side closest to the object being protected.

10. The multilayer structure according to claim 7, wherein each layer of the second layer, from the side closest to the neutron source to the side closest to the object being protected, i) The content of inorganic fiber bundles per unit volume in each layer increases sequentially; or ii) The volumetric porosity of the inorganic fiber bundles constituting each layer decreases sequentially; or iii) The content of neutron-absorbing elements (gadolinium, samarium, cadmium) in the inorganic fiber bundles that make up each layer increases in sequence.

11. A multi-layered structure, which is a neutron-shielding multi-layered structure that separates a neutron source from the object to be protected. The multilayer structure is composed of at least two laminated layers formed by neutron-absorbing inorganic fiber bundles and resin or elastomer, with the following configuration: from the side closest to the neutron source to the side closest to the protected object. i) The content of inorganic fiber bundles per unit volume in each layer increases sequentially; or ii) The volumetric porosity of the inorganic fiber bundles constituting each layer decreases sequentially; or iii) The content of neutron-absorbing elements (gadolinium, samarium, cadmium) in the inorganic fiber bundles that make up each layer increases in sequence.

12. The multilayer structure according to claim 10, wherein the resin is a bisphenol A type epoxy resin or a cured product of hydrogenated bisphenol A type epoxy resin.

13. The multilayer structure according to claim 11, wherein the resin is a bisphenol A type epoxy resin or a cured product of hydrogenated bisphenol A type epoxy resin.

14. The method for manufacturing a multilayer structure according to claim 10, wherein the method utilizes an injection molding method.

15. The method for manufacturing a multilayer structure according to claim 11, wherein the method utilizes injection molding.

Images