阅读说明：本技术 一种用于核反应堆废料容器的表面处理方法 (Surface treatment method for nuclear reactor waste container ) 是由 潘文高 李朝明 李运红 禹兴利 韩辉 于 2019-10-29 设计创作，主要内容包括：本发明公开了一种用于核反应堆废料容器的表面处理方法,包括以下步骤：S1：将质量百分含量比为5％-70％：30％-95％的Al合金和B<Sub>4</Sub>C粉末采用高速混合机进行混合,混合时间为60-240min,得到混合粉体；S2：使用超声波对S1中得到的混合粉体表面进行超声波筛分得到B<Sub>4</Sub>C/Al复合颗粒；以及S3：采用超音速火焰喷涂法,通过喷枪将S2中的B<Sub>4</Sub>C/Al复合粉末直接喷涂到核反应堆废料容器表面,得到一层B<Sub>4</Sub>C/Al复合涂层,随后喷枪在核反应堆废料容器表面上方来回重复喷涂,使B<Sub>4</Sub>C/Al复合涂层层层堆积,每一层B<Sub>4</Sub>C/Al复合涂层的厚度为10到20μm。本发明满足容器的结构强度要求,且达到放射性屏蔽的目的,提高B<Sub>4</Sub>C/Al复合涂层与核反应堆废料容器的结合力和致密度,降低了B<Sub>4</Sub>C/Al复合涂层的孔隙率,同时使B<Sub>4</Sub>C均匀分散。(The invention discloses a surface treatment method for a nuclear reactor waste container, which comprises the following steps: s1: 5-70 percent of the following components in percentage by mass: 30% -95% of Al alloy and B 4 Mixing the powder C by a high-speed mixer for 60-240min to obtain mixed powder; s2: ultrasonic screening of the surface of the mixed powder obtained in S1 by ultrasonic waves was performed to obtain B 4 C/Al composite particles; and S3: spraying B in S2 with supersonic flame 4 C/Al composite powder is directly sprayed on the surface of a nuclear reactor waste container to obtain a layer B 4 C/Al composite coating, then repeatedly spraying with a spray gun back and forth over the surface of the nuclear reactor waste container to enable B 4 The C/Al composite coating layers are stacked layer by layer, each layer B 4 The thickness of the C/Al composite coating is10 to 20 μm. The invention meets the structural strength requirement of the container, achieves the aim of radioactive shielding and improves B 4 The binding force and the density of the C/Al composite coating and the nuclear reactor waste container are reduced, and B is reduced 4 Porosity of C/Al composite coating while making B 4 C is uniformly dispersed.)

1. A surface treatment method for a nuclear reactor waste container, characterized in that it comprises the following steps:

s1: 5-70 percent of the following components in percentage by mass: 30% -95% of Al alloy and B₄Mixing the powder C by adopting a high-speed mixer, wherein the mixing power is 15-30kW, the rotating speed is 4000-;

s2: performing ultrasonic screening on the surface of the mixed powder obtained in the step S1 by using ultrasonic waves for 15-30min to obtain B₄C/Al composite particles; and

s3: b in S2 is sprayed by a spray gun by using a supersonic flame spraying method₄C/Al composite powder is directly sprayed on the surface of the nuclear reactor waste container to obtain a layer B₄C/Al composite coating, then repeatedly spraying the spray gun back and forth above the surface of the nuclear reactor waste container to enable B₄The C/Al composite coating layers are stacked layer by layer, each layer B₄The thickness of the C/Al composite coating is 10 to 20 mu m; when the supersonic flame spraying is carried out, the flame flow speed of the supersonic flame spraying is more than 2000m/s, the speed of the sprayed particles is 400-500m/s, the temperature of the outer surface of the nuclear reactor waste container is less than 150 ℃ when the spraying is carried out, the fuel pressure is 1.2-1.5MPa, and the distance between the spray gun and the surface of the nuclear reactor waste container is 150-300mm when the spraying is carried out.

2. The method of claim 1, wherein B in S1 is B₄The particle size of the C powder is 15-50 μm, and the particle size of the Al alloy in S1 is 15-50 μm.

3. The method of claim 1, wherein the accumulated B in S3 is used as a surface treatment for a nuclear reactor waste container₄The porosity of the C/Al composite coating is less than 1%, the binding force is higher than 50MPa, and the thickness is 50-2000 mu m.

4. The method of claim 1, wherein the accumulated B in S3 is used as a surface treatment for a nuclear reactor waste container₄The thermal neutron absorption performance of the C/Al composite coating is greater than or equal to 95%.

5. A surface treatment method for a nuclear reactor waste vessel according to claim 1, in which the Al alloy and B are mixed₄The mass percentage of the C powder is 40-70%: 30 to 60 percent.

6. The surface treatment method for the nuclear reactor waste container as recited in claim 1, wherein when the surface of the mixed powder obtained in S1 is ultrasonically screened, the mixed powder is sent to an ultrasonic crusher for ultrasonic vibration screening, and the ultrasonic frequency is 30000 and 40000 Hz.

Technical Field

The invention relates to a surface treatment method for a nuclear reactor waste container.

Background

Generally, each million kilowatt nuclear power unit can discharge 25t of spent fuel every year, and the current spent fuel accumulated in China reaches more than 1000 t. At present, most of the storage modes of the spent fuel at home and abroad adopt 'wet' storage (namely, the spent fuel is stored on a grid frame of a pool) and 'dry' storage, and a dry storage container has the functions of storing and transporting the spent fuel. The spent fuel discharged from the nuclear reactor has extremely strong radioactivity, has certain neutron emissivity, and needs to be stored in a spent fuel pool for a period of time so as to enable most of radioactive nuclides with short half-life period to decay away and take away decay heat. The materials for processing the spent fuel are required to have high thermal neutron absorption capacity, and also have the characteristics of high strength, high temperature corrosion resistance, irradiation resistance, low thermal expansion coefficient and the like. At present, the spent fuel storage and transportation equipment and the grid work material used abroad are mainly boron-containing steel, boron-aluminum alloy and B₄C/Al composite material, cadmium-gadolinium-containing neutron absorbing material, organic polymer and the like. The existing common spent fuel dry storage and transportation container is mainly composed of boron-containing steel, but the boron-containing steel has low boron content, low absorption capacity for thermal neutrons and epithermal neutrons, poor neutron absorption capacity and difficulty in meeting the storage and transportation of the spent fuel, and the boron-containing steel and boron-aluminum alloy have low boron content and the strength is reduced along with the increase of the boron content; the cadmium-gadolinium material is easy to generate neutron poison, and the organic polymer is difficult to resist high temperature and easy to age under the irradiation condition. B is₄The C/Al composite material combines the advantages of toughness, ductility, formability and the like of aluminum metal with the advantages of hardness, ablation resistance, low density and the like of boron carbide ceramic, so B₄The C/Al composite material has low density, high thermal conductivity, good mechanical property and high neutron absorption capacity, is already applied abroad, but the material has high price and cannot be popularized and applied in a large scale. And B₄C/AlB₄The combination of the C/Al composite coating and the stainless steel substrate provides a more economical solution for the treatment of the spent fuel, but the combination of the C/Al composite coating and the stainless steel substrate meets the structural strength requirement of the containerThe purpose of radioactive shielding is achieved, and the process for arranging the composite material coating on the stainless steel substrate has higher requirements. The Chinese academy utilized the cold spraying process to prepare B on a steel matrix₄C/Al composite coating. The cold spray process is a coating formed by plastic deformation of high velocity powder particles as they impact a substrate at low temperatures. B obtained by the method₄In the C/Al composite coating, the porosity is below 5%, the binding force is higher than 30MPa, the thickness is above 500 mu m, B₄The C particles are substantially uniformly distributed in the Al matrix. However, due to the limitation of the process principle, the prepared coating has low binding force with a substrate and high porosity, when the coating is used for a long time in a complex environment containing radioactivity and high corrosivity, tiny primary batteries are easily generated on the surface of a container to cause pore corrosion, and the coating falls off when the coating is serious. High Velocity Oxygen (HVOF) is a high temperature, high velocity combustion flame stream generated by combustion of a hydrocarbon fuel gas such as propane or propylene, or hydrogen and high pressure oxygen in a combustion chamber or in a special nozzle. Spraying compact B on a steel substrate by HVOF process₄The method of the C/Al composite coating has not been reported at home and abroad.

Disclosure of Invention

The object of the present invention is to solve the above problems by providing a surface treatment method for a nuclear reactor waste container, which satisfies the structural strength requirements of the container and simultaneously achieves the purpose of radioactive shielding, and B is improved₄The binding force and the compactness of the C/Al composite coating and the nuclear reactor waste container are further reduced, and B is further reduced₄Porosity of C/Al composite coating while making B₄C in B₄The C/Al composite coating is uniformly dispersed.

The purpose of the invention is realized as follows:

the invention relates to a surface treatment method for a nuclear reactor waste container, which comprises the following steps:

s1: 5-70 percent of the following components in percentage by mass: 30% -95% of Al alloy and B₄Mixing the powder C by adopting a high-speed mixer, wherein the mixing power is 15-30kW, the rotating speed is 4000-;

s2: ultrasonic screening of the surface of the mixed powder obtained in S1 by ultrasonic waves was performed to obtain B₄C/Al composite particles, which can destroy agglomeration and uniformly disperse for 15-30 min; and

s3: spraying B in S2 with supersonic flame₄C/Al composite powder is directly sprayed on the surface of a nuclear reactor waste container to obtain a layer B₄C/Al composite coating, then repeatedly spraying with a spray gun back and forth over the surface of the nuclear reactor waste container to enable B₄The C/Al composite coating layers are stacked layer by layer, each layer B₄The thickness of the C/Al composite coating is 10 to 20 mu m; when the supersonic flame spraying is carried out, the flame flow speed of the supersonic flame spraying is more than 2000m/s, the jet particle speed is 500m/s, the temperature of the outer surface of the nuclear reactor waste container is less than 150 ℃ when the spraying is carried out, the fuel pressure is 1.2-1.5MPa, and the distance between a spray gun and the surface of the nuclear reactor waste container is 150mm and 300mm when the spraying is carried out.

A surface treatment method for a nuclear reactor waste container as described above, wherein B in S1₄The particle size of the C powder is in the range of 15-50 μm, and the particle size of the Al alloy in S1 is in the range of 15-50 μm.

The surface treatment method for a nuclear reactor waste container, wherein the accumulated B in S3₄The porosity of the C/Al composite coating is less than 1%, the binding force is higher than 50MPa, the thickness is 50-2000 mu m, B₄C in B₄The C/Al composite coating is uniformly dispersed.

The surface treatment method for a nuclear reactor waste container, wherein the accumulated B in S3₄The thermal neutron absorption performance of the C/Al composite coating is greater than or equal to 95%.

The surface treatment method for the nuclear reactor waste container is characterized in that Al alloy and B₄The mass percentage of the C powder is 40-70%: 30 to 60 percent.

In the surface treatment method for a nuclear reactor waste container, when the surface of the mixed powder obtained in S1 is ultrasonically classified by using ultrasonic waves, the mixed powder is sent to an ultrasonic crusher to be ultrasonically vibrated and classifiedThe ultrasonic frequency is 30000-40000Hz, the agglomeration and conglomeration of large particles of mixed powder are reduced, thereby increasing the sieving amount and reducing the number of the large particles, B₄The C/Al powder is more dispersed and more uniform in gradation.

The invention has the following beneficial effects:

1. b obtained by applying the surface treatment method of the invention₄The C/Al composite coating greatly improves the density and the bonding strength by a high-speed mixer mixing, ultrasonic screening and supersonic flame spraying method, and the supersonic flame spraying method is adopted, and the parameters are set by creative labor of an inventor, B₄The speed of the C/Al composite particles impacting the surface of the nuclear reactor waste container is greatly improved, and the density and the bonding strength are further ensured; meanwhile, the micro-pore corrosion resistance and the slit corrosion resistance are excellent, the service life is longer, and the purpose of radioactive shielding is achieved while the structural strength requirement of the container is met;

2. invention B₄The boron content in the C/Al composite coating is high, B₄C content is more than or equal to 30 wt.%; b obtained by the invention₄The C/Al composite coating has strong thermal neutron absorption capacity, wherein the neutron absorption cross section is far superior to that of common boron-containing stainless steel, and the thermal neutron absorption performance is greater than or equal to 95%;

3. ultrasonic wave screening ensures B₄The C/Al composite particles achieve the effects of breaking agglomeration and uniformly dispersing;

4. the high speed mixer mixing and supersonic flame spraying method ensure B₄C in B₄The C/Al composite coating is uniformly dispersed;

5. the invention forms B by applying a supersonic flame spraying method on the surface of a nuclear reactor waste container₄The C/Al composite coating greatly reduces the production cost while achieving the purpose of radioactive shielding.

Detailed Description

The present invention will be further described with reference to examples 1 to 3 and comparative examples 1 to 2.