阅读说明：本技术 一种辐射屏蔽容器及其制备方法 (Radiation shielding container and preparation method thereof ) 是由 李圆圆 苏功建 李统业 梁勇 陈小军 杨静 潘小强 王宇 于 2019-09-23 设计创作，主要内容包括：本发明公开了一种辐射屏蔽容器及其制备方法,辐射屏蔽容器包括容器盖与容器筒体两部分,均为夹层结构屏蔽容器,包括屏蔽容器包壳,以及填充在屏蔽容器包壳内的中间层；屏蔽容器包壳为不锈钢,中间层为耐热耐辐照的中子屏蔽材料,屏蔽容器包壳用于屏蔽伽玛射线,提供力学强度,中间层用于提供中子射线屏蔽；方法包括包壳加工,配料,初步混料,加引发剂,浇注,静置固化,封焊,打磨,清洗；本发明能够减少氧化钚粉末的储存时对环境辐射的影响,通过本发明中的辐射屏蔽容器能够使氧化钚粉末在储存过程中产生的中子与伽玛射线剂量得到有效屏蔽,避免拼接缝剂量热点,提高容器的屏蔽效果,通过本发明中的制备方法能够提高屏蔽容器的生产效率。(The invention discloses a radiation shielding container and a preparation method thereof, wherein the radiation shielding container comprises a container cover and a container barrel, is a shielding container with a sandwich structure and comprises a shielding container envelope and an intermediate layer filled in the shielding container envelope; the shell of the shielding container is made of stainless steel, the middle layer is made of a heat-resistant and radiation-resistant neutron shielding material, the shell of the shielding container is used for shielding gamma rays and providing mechanical strength, and the middle layer is used for shielding neutron rays; the method comprises the steps of processing cladding, burdening, primarily mixing, adding an initiator, casting, standing for curing, sealing and welding, polishing and cleaning; the radiation shielding container can effectively shield the dose of neutrons and gamma rays generated in the process of storing the plutonium oxide powder, avoid splicing seam dose hot spots and improve the shielding effect of the container, and the production efficiency of the shielding container can be improved by the preparation method provided by the invention.)

1. A radiation shielding container is characterized by comprising a shielding container cylinder and a shielding container cover, wherein the shielding container cylinder and the shielding container cover are of a sandwich structure, and the sandwich structure comprises a shielding container envelope and an intermediate layer filled in the shielding container envelope; the shielding container shell is made of stainless steel, the middle layer is made of a heat-resistant and radiation-resistant neutron shielding material, the shielding container shell is used for shielding gamma rays and providing mechanical strength required by container handling, the middle layer is used for providing neutron ray shielding, the thickness of the inner packaging shell of the shielding container is 2-10mm, the thickness of the outer packaging shell is 2-10mm, the thickness of the middle layer is 60-150mm, and the shielding container shell comprises a shielding container barrel shell and a shielding container cover shell.

2. The radiation-shielding container of claim 1, wherein the heat and radiation resistant neutron shielding material is a boron-containing epoxy.

3. A method of making a radiation-shielding container according to any one of claims 1 to 2, comprising:

the first step of cladding processing: processing a shielding container cylinder jacket and a shielding container cover jacket, and reserving a pouring gate;

and step two, material preparation: weighing a certain amount of epoxy resin, boron carbide powder and aluminum hydroxide according to a formula;

thirdly, preliminary mixing, namely putting the epoxy resin, the boron carbide powder and the aluminum hydroxide into a vacuum mixer, vacuumizing and stirring;

fourthly, adding an initiator into the preliminarily mixed materials, pouring the initiator into the materials, vacuumizing and stirring the materials;

pouring the material stirred in the fourth step into the shell of the shielding container and the shell of the shielding container cover, standing and curing;

sixthly, sealing and welding, namely after the epoxy resin is cured, respectively covering the shielding container cylinder and the cover plate of the shielding container cover, and sealing and welding by adopting a water cooling measure;

and step seven, polishing and cleaning the shielding container cylinder and the shielding container cover.

4. The method for manufacturing a radiation shielding container according to claim 3, wherein the epoxy resin, the boron carbide powder and the aluminum hydroxide are prepared in the following formula ratios: 30-50 parts of epoxy resin, 0.5-2 parts of boron carbide, aluminum hydroxide powder: 48 to 69.5 portions.

5. The method of manufacturing a radiation shielding container according to claim 3, wherein the boron carbide has a particle size of 5 to 50 μm.

6. The method of manufacturing a radiation shielding container according to claim 3, wherein the particle size of the aluminum hydroxide is 30 to 100 μm.

7. A method of manufacturing a radiation-shielding container according to claim 3, wherein the preliminary mixing is performed for a mixing time of 10 to 60 min.

8. The method of claim 3, wherein the fourth step is carried out for a mixing time of 10-60 min.

9. The method of claim 3, wherein the sealing is argon arc welding.

Technical Field

The invention relates to the field of nuclear fuel circulation and material radiation protection, in particular to a radiation shielding container and a preparation method thereof.

Background

The transuranic element isotope is an important nuclear material in modern nuclear industry, including plutonium, an element isotope with an atomic coefficient of americium and the like larger than 92, the transuranic element such as an isotope of plutonium has extremely strong chemical toxicity, and in the storage process, alpha rays are generated due to spontaneous decay, radioactive aerosol and gamma rays, and simultaneously, neutron rays are generated by spontaneous fission and (alpha, n) reaction, heat can be generated during the decay of the transuranic element isotope, the specific power is higher, the central temperature of a material is higher than 300 ℃, neutron ray protection needs to be considered for the long-term storage of the transuranic element isotope, gamma ray protection, the heat-resisting problem of a shielding material and the like. The long-term storage of plutonium-containing oxide powder materials places high demands on the shielded containers. There is no prior art relating to shielded containers for long term storage of isotopes.

Disclosure of Invention

The invention aims to reduce the influence of the plutonium oxide powder and other transuranic isotopes on environmental radiation during storage, effectively shield the dose of neutrons and gamma rays generated in the storage process of the powder, avoid splicing seam dose hot spots, improve the shielding effect of the container and improve the production efficiency of the shielding container.

Because the gamma ray energy emitted by transuranic isotopes such as plutonium oxide powder is low, the gamma dose can be reduced to a low level by using a thin stainless steel material, the neutron ray energy is high, the shielding difficulty is high, a neutron moderating material with hydrogen content and a material with a large neutron absorption cross section are required to shield, and the neutron ray can be shielded below a dose control value by using a thick shielding material. As the decay heat power of the transuranic element is higher in the storage process, the long-term use temperature of the shielding material needs to reach more than 100 ℃ in order to avoid the influence of heat release on the shielding material.

In order to achieve the above object, the present application provides, in one aspect, a radiation shielding container comprising two parts, namely a shielding container cylinder and a shielding container cover, wherein the shielding container cylinder and the shielding container cover are of a sandwich structure, and the sandwich structure comprises a shielding container envelope and an intermediate layer filled in the shielding container envelope; the shielding container shell is made of stainless steel, the middle layer is made of a heat-resistant and radiation-resistant neutron shielding material, the shielding container shell is used for shielding gamma rays and providing mechanical strength required by container handling, and the middle layer is used for providing neutron ray shielding.

The thickness of an inner package shell of the shielding container is 2-10mm, the thickness of an outer package shell of the shielding container is 2-10mm, the shielding container is mainly used for providing mechanical strength and gamma ray shielding for the container, if the cladding is lower than 2mm, on one hand, the gamma dose on the outer surface of the shielding container can be rapidly increased, on the other hand, the mechanical strength of the container can be influenced to a certain extent, if the cladding is too thick, the total weight of the container can be increased due to higher density of steel, the container is heavy as a whole, the energy spectrum of transuranic gamma rays is softer, the attenuation speed of the gamma rays in the steel is higher, the attenuation effect on the total dose is smaller and smaller along with the increase of the thickness of steel, and most. The interlayer in the middle of the shielding container is used for shielding neutron rays, the thickness is 60-150mm, if the thickness of the shielding layer is less than 60mm, the shielding rate of the shielding container to the neutron rays is lower than 50%, the effect is not obvious, when the thickness of the shielding layer reaches 150mm, the shielding rate reaches more than 80%, if the thickness is increased, the effect is not obvious, the weight and the volume of the shielding body can be greatly increased, the carrying difficulty is increased, and if the shielding rate is increased by 5%, the thickness of the shielding body needs to be increased by more than 40 mm.

The preferred neutron ray shielding material is boron-containing epoxy resin, the maximum temperature of the boron-containing epoxy resin reaches 150 ℃, and the boron-containing epoxy resin can be molded by a pouring method.

The preferred proportion of each component in the boron-containing epoxy resin is as follows: epoxy resin: 30-50 parts of boron carbide, 0.5-2 parts of aluminum hydroxide powder: 48 to 69.5 portions. The epoxy resin serves as a binder and provides a certain amount of hydrogen, the boron carbide serves as a neutron absorbing material, and the aluminum hydroxide provides hydrogen as a neutron moderator, and simultaneously, the cost of the shielding material is reduced.

In another aspect, the present invention also provides a method of making a radiation-shielding container, the method comprising:

the first step of cladding processing: processing a shielding container cylinder jacket and a shielding container cover jacket, and reserving a pouring gate;

and step two, material preparation: weighing a certain amount of epoxy resin, boron carbide powder and aluminum hydroxide according to a formula;

thirdly, preliminary mixing, namely putting the epoxy resin, the boron carbide powder and the aluminum hydroxide into a vacuum mixer, vacuumizing and stirring;

fourthly, adding an initiator into the preliminarily mixed materials, pouring the initiator into the materials, vacuumizing and stirring the materials;

pouring the material stirred in the fourth step into the shell of the shielding container and the shell of the shielding container cover, standing and curing;

sixthly, sealing and welding, namely after the epoxy resin is cured, respectively covering the shielding container cylinder and the cover plate of the shielding container cover, and sealing and welding, wherein a water cooling measure is adopted to avoid the shielding material from being damaged under the action of high welding temperature;

and step seven, polishing and cleaning the shielding container cylinder and the shielding container cover.

Preferably, the formula proportions of the epoxy resin, the boron carbide powder and the aluminum hydroxide are as follows: epoxy resin: 30-50 parts of boron carbide, 0.5-2 parts of aluminum hydroxide powder: 48 to 69.5 portions. The epoxy resin is a high-temperature-resistant binding phase, the aluminum hydroxide is a neutron moderator, the boron carbide is a neutron absorbing material, the moderated neutrons are absorbed, the shielding material formed by combining the epoxy resin, the aluminum hydroxide and the boron carbide has high heat-resistant temperature, can normally work under the decay and heat release conditions of radioactive substances, has high hydrogen content, and has excellent shielding effect on neutron rays emitted by transuranic isotopes.

Preferably, the particle size of the boron carbide is 5 to 50 micrometers, if the particle size of the boron carbide is too large, the boron carbide particles are easy to settle, and if the particle size is too small, micro-bubbles are easy to form, so that the density of the shielding material is reduced.

Preferably, the particle size of the aluminum hydroxide is 30 to 100 microns. If the particle size of the aluminum hydroxide is too large, the particles are easy to settle, and if the particle size is too small, micro bubbles are easy to form, so that the density of the shielding material is reduced, and the shielding effect of the shielding material is influenced. Preferably, the mixing time of the preliminary mixing is 10-60 min.

Preferably, the mixing time in the fourth step is 10-60min, and according to experiments, the mixing time in the first mixing step and the fourth step is too short, so that the materials are not easy to mix uniformly, and the production efficiency is affected if the mixing time is too long.

Preferably, the sealing welding mode is argon arc welding.

One or more technical solutions provided by the present application have at least the following technical effects or advantages:

the radiation shielding container can effectively shield the dose of neutrons and gamma rays generated in the process of storing the plutonium oxide powder, avoid splicing seam dose hot spots and improve the shielding effect of the container, and the production efficiency of the shielding container can be improved by the preparation method provided by the invention. If polyethylene or boron polyethylene shielding materials are adopted, plates are required to be processed into arc-shaped sections to be assembled into barrel or cover shapes, the material utilization rate is low, the cost is high, the processing efficiency is low, splicing seams are easy to form, the service temperatures of the polyethylene, boron polyethylene and other materials are low, the shielding materials can deform, collapse and deform under the action of decay heat, and therefore the shielding effect of the container is influenced.

The material containing 1.5 kilograms of plutonium oxide is put into the shielding container described by the invention, the total surface dose rate of the container is lower than 20 MuSv/h, and the transuranic isotope can be safely stored for a long time.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, the present invention will be described in further detail with reference to specific embodiments. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflicting with each other.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described and thus the scope of the present invention is not limited by the specific embodiments disclosed below.