A high temperature resistant neutron and photon composite shielding material

Abstract

The application provides a high-temperature-resistant neutron and photon composite shielding material, raw material components of which are matched according to mass ratio, and the raw material components comprise 1-20wt% gadolinium oxide powder, 15-30wt% stainless steel powder and 50-80wt% tungsten carbide, and the material is formed by hot pressing or hot isostatic pressing method. The material provided by the application has good shielding capacity for thermal neutron, fast neutron, high-energy neutron and photon, and has the advantage of high-temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of radiation protection, and in particular to a high-temperature resistant composite shielding material for neutrons and photons. The material can be used for shielding against neutrons and gamma rays and can be used for a long time at ambient temperatures below 1200 degrees Celsius. Background Technology

[0002] With the development of nuclear science, the relationship between ionizing radiation and humanity is becoming increasingly close. While nuclear power and nuclear technology contribute to modern civilization, the health problems caused by ionizing radiation are receiving increasing attention. Different scenarios place different demands on ionizing radiation shielding materials, requiring the development of specific shielding materials for each environment. At room temperature, the requirements for ionizing radiation shielding materials are mainly based on shielding effectiveness and cost, with lower requirements for mechanical properties and thermal stability. However, for special applications, in addition to shielding performance, shielding materials are required to possess specific functions. In the nuclear energy field, because nuclear reactions within the reactor produce a large number of neutrons and photons, the shielding material needs to reduce the impact of neutrons and photons inside the reactor on ionizing radiation outside the reactor under high temperature and high radiation conditions. For compact reactors, the shielding material also needs to have high-efficiency shielding capabilities, achieving a shielding effect within a limited space.

[0003] Existing mature shielding materials include silicate cement shielding materials, polyethylene-based shielding materials, and metal-based shielding materials. Silicate cement is widely used for radiation shielding in nuclear power plants and hospitals. The advantages of silicate cement are its low cost, mature construction methods, and good mechanical properties; however, its main disadvantage is its relatively low shielding performance per unit volume. Currently, many studies have explored ways to improve the shielding performance of silicate cement by adding borides, heavy metals, and various ores. Polyethylene-based shielding materials are characterized by their low density and are often used for ionizing radiation shielding in spacecraft and portable instruments. However, their performance in shielding photons and heavy ions is poor. Therefore, metal elements, such as lead-boron polyethylene and tungsten-boron polyethylene, are often mixed into them to improve their photon and heavy ion shielding performance. However, a common drawback of polyethylene-based shielding materials is their poor thermal stability; their long-term operating temperature does not exceed 150 degrees Celsius. Metal matrix composites typically use heavy metals and their oxides as the substrate. Tungsten-based shielding materials possess advantages such as high density, high scattering cross section, excellent mechanical properties, and low activation performance, making them suitable for radiation shielding in extreme environments. However, tungsten's neutron absorption cross section is not particularly outstanding. Therefore, Windsor et al. utilized tungsten boride as a shielding material (CGWindsor et al 2018 Nucl. Fusion 58076014, Colin G.Windsor et al 2021 Nucl. Fusion 61 086018). 10Boron's high thermal neutron absorption cross section enhances the overall neutron capture cross section of the material; however, tungsten boride powder lacks mature commercial products and is expensive, hindering its large-scale application. Gadolinium, due to its significantly higher thermal neutron absorption and photon reaction cross sections compared to most other elements, is widely used for neutron absorption and moderation. Gadolinium oxide (Gd₂O₃) is an excellent non-toxic neutron shielding material, but its low density and mass attenuation coefficient reduce its shielding ability against secondary photons, making it difficult to use as a shielding material independently. This invention proposes using stainless steel powder as a binder to mold gadolinium oxide powder and tungsten carbide powder through hot pressing or hot isostatic pressing. The resulting shielding material combines the shielding advantages of both tungsten and gadolinium, enabling neutron and photon shielding at high temperatures. Summary of the Invention

[0004] The technical problem solved by this invention is ionizing radiation shielding under high temperature and high radiation environments. To solve the above problem, this invention provides a non-toxic, high temperature resistant, and corrosion resistant neutron and gamma shield that can be applied to ionizing radiation shielding under high temperature and high radiation environments, shielding neutron and photon mixed radiation fields.

[0005] The present invention adopts the following technical solution:

[0006] This invention provides a high-temperature resistant neutron and photon composite shielding material, which is prepared by a method comprising the following steps: mixing 1-20 wt% gadolinium oxide, 15-30 wt% stainless steel, and 50-80 wt% tungsten carbide by weight of the total raw material mixture to obtain a raw material mixture, and then molding the raw material mixture by hot pressing or hot isostatic pressing.

[0007] Furthermore, the high-temperature resistant neutron and photon composite shielding material is prepared by a method comprising the following steps: mixing 1-10 wt% gadolinium oxide, 15-25 wt% stainless steel, and 50-80 wt% tungsten carbide by weight of the total raw material mixture to obtain a raw material mixture, and then molding the raw material mixture by hot pressing or hot isostatic pressing; wherein, by weight of the total raw material mixture, the sum of the mass percentages of gadolinium oxide, stainless steel, and tungsten carbide is 100 wt%.

[0008] Furthermore, based on the total mass of the raw material mixture, the gadolinium oxide content is 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, 12.5 wt%, 13 wt%, 13.5 wt%, 14 wt%, 14.5 wt%, 15 wt%, 15.5 wt%, 16 wt%, 16.5 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, and 20 wt%.

[0009] Furthermore, the stainless steel content is 15 wt%, 15.5 wt%, 16 wt%, 16.5 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, 20 wt%, 20.5 wt%, 21 wt%, 21.5 wt%, 22 wt%, 22.5 wt%, 23 wt%, 23.5 wt%, 24 wt%, 24.5 wt%, 25 wt%, 25.5 wt%, 26 wt%, 26.5 wt%, 27 wt%, 27.5 wt%, 28 wt%, 28.5 wt%, 29 wt%, 29.5 wt%, or 30 wt%, based on the total mass of the raw material mixture.

[0010] Furthermore, the tungsten carbide content, based on the total mass of the raw material mixture, is 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, or 80 wt%.

[0011] Furthermore, the high-temperature resistant neutron and photon composite shielding material can be used for a long time at ambient temperatures below 1200 degrees Celsius.

[0012] Furthermore, the density of the high-temperature resistant neutron and photon composite shielding material is 7.0–13.2 g / cm³. 3 .

[0013] Furthermore, the gadolinium oxide is in powder form with a particle size of 100-500 mesh; the gadolinium mass percentage is 75-90 wt%, the oxygen mass percentage is 9-23 wt%, and the total mass percentage of impurity elements is less than 1%.

[0014] Furthermore, the stainless steel is in powder form, specifically martensitic or ferritic stainless steel powder, with a particle size of 50-200 mesh; the chromium content is 8-18 wt%, the carbon content is less than 0.03 wt%, and the oxygen content is less than 0.3 wt%.

[0015] Furthermore, the tungsten carbide is in powder form with a particle size of 100-500 mesh; the total mass percentage of the five impurity elements Sn, Ni, Cu, Mg, and Ba is less than 0.5%.

[0016] Furthermore, the hot isostatic pressing method is performed at a temperature of 1000-1800℃, a pressure of 60-110MPa, and a holding time of 15-40 minutes.

[0017] Implementing the embodiments of the present invention has the following beneficial effects:

[0018] The novel neutron and photon composite shielding material provided by this invention has the advantages of high temperature resistance and high density compared with tungsten boron polyethylene and lead boron polyethylene materials. It can be used for a long time at an ambient temperature below 1200 degrees Celsius, and the density is 7.0 to 13.2 g / cm3, resulting in better shielding effect per unit volume of material.

[0019] The novel neutron and photon composite shielding material provided by this invention contains gadolinium, which has a high capture cross section for low and medium energy neutrons; it has a high tungsten content, which has a good effect on slowing down and capturing high-energy neutrons and a good shielding ability for secondary photons, and can generally meet the shielding requirements of neutron and gamma mixed radiation fields. Attached Figure Description

[0020] Figure 1 The neutron energy spectrum used to test the shielding performance of materials is shown.

[0021] Figure 2 This demonstrates the advantages of silicate cement and 316L stainless steel, developed using materials from Embodiment 1 of the present invention and existing technologies, for... Figure 1 The shielding effect of the neutron energy spectrum. Detailed Implementation

[0022] The following describes a novel neutron and photon composite shielding material provided by the present invention.

[0023] Example 1: A novel neutron and photon composite shielding material provided by the present invention is prepared by the following steps:

[0024] (1) Weigh the following raw materials: 5.5wt% gadolinium oxide (Nanjing Xinuo Chemical Technology Co., Ltd., purity 99.9%, 400 mesh particle size, gadolinium mass percentage 87-88wt%, oxygen mass percentage 12-13wt%, impurities Tb4O7, Y2O3, Eu2O3, Dy2O3, Sm2O3 total content 0.1wt%), 22wt% stainless steel (Nangong Yingtai Metal Materials Co., Ltd., 316L, particle size 180 mesh, chromium mass percentage 17wt%, carbon mass percentage... 0.02wt%, oxygen 0.2wt%, nickel 14wt%, molybdenum 2wt%, silicon 0.8wt%, carbon 0.02wt%, phosphorus 0.03wt%, sulfur 0.02wt%, Fe 65.9%), 72.5wt% tungsten carbide (Nangong Yingtai Metal Materials Co., Ltd., purity 99.9%, 300 mesh particle size, total mass percentage of Sn, Ni, Cu, Mg, Ba 0.1wt%)

[0025] (2) The above raw materials are mixed using a mixer, and then the mixed powder is preheated to 500 degrees Celsius.

[0026] (3) The preheated and homogenized powder was subjected to hot isostatic pressing (HIP-200 equipment, Institute of Metal Research, Chinese Academy of Sciences) at a temperature of 1200 degrees Celsius and a pressure of 150 MPa for 180 minutes, followed by natural cooling. The density of the formed material was 11.2 g / cm³. 3 .

[0027] The dimensions of the one-piece molding are 200mm×200mm×100mm.

[0028] Implementing the embodiments of the present invention has the following beneficial effects:

[0029] This invention provides a high-temperature resistant neutron and photon composite shielding material. A raw material mixture is obtained by mixing 1-10 wt% gadolinium oxide, 15-25 wt% stainless steel, and 50-80 wt% tungsten carbide. This mixture is then formed by hot pressing or hot isostatic pressing to obtain a novel neutron and photon composite shielding material. Compared to tungsten boron polyethylene and lead boron polyethylene, this novel neutron and photon composite shielding material has better heat resistance, effectively increasing its operating temperature. Compared to silicate cement shielding materials, it has a larger absorption cross-section and higher neutron moderation efficiency, thus providing a higher nuclear radiation shielding efficiency per unit volume. To fully demonstrate the shielding material performance of this invention, the developed material is compared with commonly used shielding materials. A proton accelerator is used as the neutron source term, and the neutron energy spectrum is as follows: Figure 1 The shielding effect of the test materials is shown. In addition to the materials developed in this invention, silicate cement (PII-42.5 from Wuxi Jianghuai Building Materials Technology Co., Ltd.) and 316L stainless steel (from Wuxi Zhongxing Yide Stainless Steel Co., Ltd.) were used as controls to measure the shielding effect of different materials. Figure 1 The shielding effect of the neutron energy spectrum.

[0030] Figure 2 The comparison results show that the material developed in this invention exhibits better shielding performance compared to silicate cement and 316L stainless steel. For Figure 1 The neutron energy spectrum, after passing through 100cm thick silicate cement, 316L stainless steel, and the material developed in this invention, resulted in a dose reduction to 2.2%, 1.6%, and 0.01% of the initial dose, respectively. Compared to traditional shielding materials, the shielding material provided by this invention exhibits excellent shielding performance.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the claims of the present invention. Therefore, any equivalent changes or modifications made without departing from the spirit disclosed in the present invention should be included within the scope of the claims of the present invention.

Claims

1. A high-temperature resistant neutron and photon composite shielding material, characterized in that: The high-temperature resistant neutron and photon composite shielding material is prepared by a method comprising the following steps: mixing 1-19 wt% gadolinium oxide, 15-29.5 wt% stainless steel, and 50-80 wt% tungsten carbide by weight of the total raw material mixture to obtain a raw material mixture, and then molding the raw material mixture by hot isostatic pressing. The gadolinium oxide is in powder form with a particle size of 100-500 mesh; the gadolinium mass percentage is 75-90 wt%, the oxygen mass percentage is 9-23 wt%, and the total mass percentage of impurity elements is less than 1%. The stainless steel is in powder form, specifically martensitic or ferritic stainless steel powder, with a particle size of 50-200 mesh; the chromium content is 8-18 wt%, the carbon content is less than 0.03 wt%, and the oxygen content is less than 0.3 wt%. Tungsten carbide is in powder form with a particle size of 100-500 mesh; the total mass percentage of the five impurity elements Sn, Ni, Cu, Mg, and Ba is less than 0.5%. The hot isostatic pressing (HIP) method involves forming at temperatures of 900-1800℃, pressures of 70-210MPa, and holding times of 30-300 minutes.

2. The high-temperature resistant neutron and photon composite shielding material according to claim 1, characterized in that: The density of the high-temperature resistant neutron and photon composite shielding material is 7.0 ~ 13.2 g / cm³.

3. The high-temperature resistant neutron and photon composite shielding material according to claim 1, characterized in that: The raw material mixture consists of the following components: 1-10 wt% gadolinium oxide, 15-25 wt% stainless steel, and 50-80 wt% tungsten carbide by weight of the total raw material mixture, and the sum of the weight percentages of gadolinium oxide, stainless steel, and tungsten carbide is 100 wt%.

Images