KR102174554B1 - Spent fuel canister using 3D printing technique and manufacturing method thereof - Google Patents

Abstract

According to the present invention, provided is a spent fuel canister. Even through the spent fuel canister is manufactured through three-dimensional printing, the spent fuel canister has excellent mechanical properties such as strength, impact resistance, tensile strength, and the like, and has the effect of minimizing variations in the mechanical properties in accordance with a stacking direction. Even through the spent fuel canister contains a sufficient amount of neutron shielding materials capable of completely preventing exposure of radioactive nuclides, the spent fuel canister has the effect of minimizing deterioration in the mechanical properties such as toughness, strength, and the like. Moreover, according to the present invention, the spent fuel canister has excellent corrosion resistance and durability, has high structural stability, does not require external fastening parts such as bolts, nuts, and the like, and has excellent sealing properties even though the spent fuel canister is free from welding. In addition, according to the present invention, the spent fuel canister has sufficient neutron shielding performance and minimizes the thickness of the canister, thereby having a more advantageous effect in securing space.

Description

Spent fuel canister using 3D printing technique and manufacturing method thereof

It relates to a spent fuel canister and a method of manufacturing the same.

Nuclear wastes such as high-level waste and spent nuclear fuel that are unavoidably generated from the nuclear industry must be safely isolated from the ecosystem for a long period of time. One of the engineering barriers for this, the canister, can usually be made of a single or alloy material. France, the United Kingdom, and Japan are considering a method of putting high-level waste into a glass solidified material, putting it in a container, and then packing the container in another container, and Canada, Germany, Finland, and Sweden are considering putting the spent fuel directly into the container. I am considering how to wrap it. In the U.S., separate disposal containers are envisioned for two types of solidified glass and spent fuel. In the case of Korea, the concept of disposing of spent nuclear fuel in the deep stratum is pursued. For example, a disposal container is mounted vertically in a 500 m deep crystalline rock mass, and the surrounding area is filled with compressed bentonite.

However, as described above, in a disposal cave built in a rock mass of 500 m or more underground where the disposal container containing spent nuclear fuel is to be disposed, there is a water pressure of 50 atm or more due to groundwater and a swelling pressure of 100 atm or more by the buffer material to protect the disposal container. I can. Therefore, the disposal container must have structural stability that can withstand such pressure. In addition, it should be able to semi-permanently suppress the leakage of radionuclides existing in the spent nuclear fuel into the surrounding environment.

The canister, a container that can store spent nuclear fuel, is made of a tubular metal canister, and a basket is provided inside the metal canister to store the spent nuclear fuel. The basket inside the metal canister is fixed through a support member or a storage member, and a neutron shield is provided outside the canister to store nuclear fuel after use.

In general, the canister material is mainly stainless steel, and includes a canister shell surrounding the side of the basket, a canister cover plate surrounding the upper end of the basket, and a canister bottom plate surrounding the lower end of the basket. It is common that the canister lid plate is fixed by bolt-nut coupling to the canister shell and sealed by welding after the spent nuclear fuel is loaded into the basket.

However, these welding areas (welding areas and heat-affected areas) and bolt/nut bonding areas are vulnerable to corrosion cracking and are a factor that damages the integrity of the nuclear fuel dry storage system after use, and the welding process involving heat is strictly controlled in temperature. It is a process with very high risk factors in the dry storage process of spent nuclear fuel that must be used.

In addition, canisters made of stainless steel, which are commonly used, must have a fairly thick thickness to prevent the leakage of radionuclides into the surrounding environment, and a neutron shielding body to completely semi-permanently block the leakage of radionuclides into the surrounding environment. Since the canister is provided as a separate member outside the canister, the structure of the canister is complicated, and the size of the canister is inevitably increased compared to the used capacity, which is more disadvantageous in securing space.

Korean Patent Registration No. 10-2078482

It is an object of the present invention to provide a spent fuel canister and a method for manufacturing the same, which have excellent mechanical properties such as strength, impact resistance, and tensile strength even though they are manufactured through 3D printing, and can minimize variations in mechanical properties depending on the stacking direction. will be.

Another object of the present invention is to provide a spent fuel canister capable of minimizing deterioration of mechanical properties such as toughness and strength even though it contains a sufficient amount of neutron shielding material to completely prevent exposure of radionuclides and a method for manufacturing the same. .

Another object of the present invention is to provide a spent fuel canister having excellent corrosion resistance and durability and high structural stability, and a method of manufacturing the same.

Another object of the present invention is to provide a spent fuel canister and a method of manufacturing the same, which does not require external fastening parts such as bolt-nuts, etc., and has excellent sealing properties even when free from welding.

Another object of the present invention is to provide a spent fuel canister and a method of manufacturing the same, which is more advantageous in securing space by minimizing the thickness of the canister while having sufficient neutron shielding performance.

Spent fuel canister according to the present invention is a spent fuel canister including a case having an inner space for accommodating spent nuclear fuel, wherein the case is made of a metal layer and an outer surface of a shielding layer, the metal layer and The shielding layer is integrally formed, and the shielding layer includes a dispersed phase of a metal matrix and a neutron shielding material.

In an example of the present invention, the metal particles of the metal layer and the metal particles of the metal matrix of the shielding layer may form a continuous body by forming a grain boundary with each other.

In an example of the present invention, the metal layer includes: a first crystalline alloy in which a first amorphous alloy having a first glass transition temperature is crystallized; And a second amorphous alloy having a second glass transition temperature higher than the first glass transition temperature, wherein the metal matrix of the shielding layer may include a second amorphous alloy having the second glass transition temperature. have.

In an example of the present invention, the first glass transition temperature may be 450°C or higher.

In an example of the present invention, the metal layer may include 25 to 400 parts by weight of the second amorphous alloy based on 100 parts by weight of the first crystalline alloy.

In an example of the present invention, a thickness ratio of the metal layer and the shielding layer may be 100:10-100.

In an example of the present invention, the thickness of the case may be 5 to 50 mm.

In an example of the present invention, the shielding layer may include 0.1 to 10 parts by weight of the neutron shielding material based on 100 parts by weight of the metal matrix.

In an example of the present invention, the metal of the metal layer and the metal of the shielding layer are independently of each other Fe based, Cu based, Al based, Mg based, Zr based, Ca based, Ti based, Ni based, Co based and Hf It may include any one or two or more selected from the system.

In an example of the present invention, the neutron shielding material is any one selected from boron carbide, boron nitride, boron oxide, zinc borate, aluminum hydroxide, hafnium, hafnium diboride, titanium diboride, ferroboron, uranium dioxide, etc. or It can contain more than one.

A method of manufacturing a spent nuclear fuel canister according to an embodiment of the present invention is a method of manufacturing a spent nuclear fuel canister including a case having an inner space for accommodating spent nuclear fuel, wherein a metal layer composition and a shielding layer composition are used face-to-face (layer by layer) technique to produce a case of a three-dimensional molded article having an inner surface of a metal layer and an outer surface of a shielding layer by 3D printing, and a heat treatment step of heat-treating the 3D molded article, and the metal layer composition It contains metal powder, and the shielding layer composition may contain a metal powder and a neutron shielding material.

In an example of the present invention, the metal powder of the metal layer composition comprises: a first amorphous alloy having a first glass transition temperature; And a second amorphous alloy having a second glass transition temperature higher than the first glass transition temperature, wherein the metal powder of the shielding layer composition includes a second amorphous alloy having the second glass transition temperature. The heat treatment step may include a first sintering step and a second sintering step, and in the first sintering step, the sintering temperature is equal to or higher than the first glass transition temperature of the first amorphous alloy and the second amorphous alloy The sintering temperature may be less than the second glass transition temperature of, and in the second sintering step, the sintering temperature may be greater than or equal to the crystallization initiation temperature of the first amorphous alloy and less than the crystallization initiation temperature of the second amorphous alloy.

In an example of the present invention, in the first sintering step, the first amorphous alloy of the metal layer may be converted to a liquid phase during sintering, and the second amorphous alloy of the metal layer and the shielding layer may maintain a solid phase, and the second In the sintering step, during sintering, the first amorphous alloy of the metal layer may be crystallized and converted into a solid phase, and the second amorphous alloy of the metal layer and the shielding layer may be converted to a liquid phase.

In one example of the present invention, in the molding step, the metal layer composition and the shielding layer composition may further include a binder, and in the heat treatment step, the binder in the molded product may be removed by heat treatment.

In an example of the present invention, in the forming step, the metal layer composition and the shielding layer composition are 3D printed by repeating a unit process including a powdery surface forming process and an adhesive composition spraying process by a layer by layer technique, It may include a forming step of manufacturing a case of a three-dimensional molded article made of the metal layer and the outer surface of the shielding layer.

In an example of the present invention, the adhesive composition spraying process may be a process of spraying an adhesive composition including a binder and a solvent onto the formed powdery surface, and in the heat treatment step, the binder in the molded product may be removed by heat treatment. .

A method of manufacturing a spent nuclear fuel canister according to an embodiment of the present invention is a method of manufacturing a spent nuclear fuel canister including a case having an inner space for accommodating spent nuclear fuel, wherein a metal layer composition and a shielding layer composition are used face-to-face (layer By layer) method, a unit process including a powdery surface forming process and a sintering process is repeated and 3D-printed to produce a case of a three-dimensional molded object with an inner surface of a metal layer and an outer surface of a shielding layer. In addition, the metal layer composition may contain a metal powder, and the shielding layer composition may contain a metal powder and a neutron shielding material.

In an example of the present invention, after the molding step, a heat treatment step of heat-treating the three-dimensional molding may be further included, wherein the metal powder of the metal layer composition comprises: a first amorphous alloy having a first glass transition temperature; And a second amorphous alloy having a second glass transition temperature higher than the first glass transition temperature, wherein the metal powder of the shielding layer composition includes a second amorphous alloy having the second glass transition temperature. In the forming step, the sintering temperature may be in a range equal to or higher than the first glass transition temperature of the first amorphous alloy and less than the second glass transition temperature of the second amorphous alloy, and in the heat treatment step, the sintering temperature is The crystallization initiation temperature of the first amorphous alloy may be higher and less than the crystallization initiation temperature of the second amorphous alloy.

In an example of the present invention, in the forming step, the first amorphous alloy of the metal layer may be converted to a liquid phase during sintering, and the second amorphous alloy of the metal layer and the shielding layer may maintain a solid phase, and in the heat treatment step, During sintering, the first amorphous alloy of the metal layer may be crystallized and converted into a solid phase, and the second amorphous alloy of the metal layer and the shielding layer may be converted to a liquid phase.

In an exemplary embodiment of the present invention, through the heat treatment step, the metal particles of the metal layer and the metal particles of the metal matrix of the shielding layer form a grain boundary with each other to form a continuous body.

Although the spent fuel canister according to the present invention is manufactured through 3D printing, it has excellent mechanical properties such as strength, impact resistance, and tensile strength, and has an effect of minimizing variations in mechanical properties depending on the stacking direction.

The spent fuel canister according to the present invention has an effect of minimizing deterioration of mechanical properties such as toughness and strength even though it contains a sufficient amount of neutron shielding material to completely prevent exposure of radionuclides.

The spent fuel canister according to the present invention has excellent corrosion resistance and durability, and has high structural stability.

The spent fuel canister according to the present invention does not require external fastening parts such as bolts and nuts, and has excellent sealing properties even when it is free from welding.

The spent fuel canister according to the present invention has a more advantageous effect in securing space by minimizing the thickness of the canister while having sufficient neutron shielding performance.

1 and 2 show changes in the state of the alloy according to each step in the method of manufacturing a canister after use according to an example of the present invention.

Hereinafter, a spent fuel canister using a 3D printing technique according to the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

The drawings described in this specification are provided as an example in order to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the present invention is not limited to the drawings to be presented and may be embodied in other forms, and the drawings may be exaggerated to clarify the spirit of the present invention.

Unless otherwise defined, technical terms and scientific terms used in the present specification have the meanings commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention in the following description and accompanying drawings A description of known functions and configurations that may unnecessarily obscure will be omitted.

Unless otherwise defined, the unit of% used in this specification means% by weight.

The singular form of terms used in the present specification may be interpreted as including the plural form unless otherwise indicated.

In the present specification and the appended claims, terms such as first and second are not used in a limiting meaning, but are used for the purpose of distinguishing one component from other components.

In the present specification and the appended claims, terms such as include or have means that the features or components described in the specification are present, and one or more other features or components are added unless specifically limited. It does not preclude the possibility of becoming.

In the present specification and the appended claims, when a part such as a film (layer), a region, a component, etc. is said to be on or on another part, not only the case that is directly above in contact with the other part, but also the other film ( Layer), other areas, and other components are also included.

Conventional spent fuel canisters are made of stainless steel, etc., in order to completely semi-permanently block the leakage of radionuclides into the surrounding environment, and have a fairly thick thickness, and the neutron shield is provided as a separate member outside the canister. As a result, the canister structure becomes complex, and the size of the canister is inevitably increased compared to the used capacity, so there is a significant disadvantage in securing the space to fill the canister.

However, in the present invention, by providing a spent fuel canister in which a shielding layer containing a neutron shielding material and a metal layer are integrally formed and a method of manufacturing the same, it has sufficient neutron shielding performance and minimizes the thickness of the canister, thereby providing a more advantageous effect in securing space. have.

In particular, the spent fuel canister according to the present invention has a sufficient amount of neutron shielding material to completely prevent exposure of radionuclides as metal powders having specific properties are used for each layer and subjected to a multi-stage sintering process with a temperature difference during manufacture. Even though it contains, there is an effect of minimizing deterioration of mechanical properties such as toughness and strength. In addition, even though it is manufactured through 3D printing, it has excellent mechanical properties such as strength, impact resistance, and tensile strength, and has the effect of minimizing variations in mechanical properties according to the stacking direction.

Therefore, the present invention has excellent chemical resistance such as corrosion resistance, remarkably excellent mechanical properties such as strength, ductility, and impact resistance, and the spent fuel canister and its manufacture, which have a larger capacity to accommodate spent fuel per unit volume compared to the prior art. Provides a way.

The spent fuel canister according to the present invention includes a case having an inner space for accommodating the spent fuel. In the following description, the spent fuel canister is described as meaning a case, but it is of course possible to further include (equip) means (structures, parts, devices, etc.) other than the case.

The case is characterized in that the inner surface is made of a metal layer and the outer surface is made of a shielding layer, and the metal layer and the shielding layer are integrally formed. Here, the term “one body” means that the metal particles of the metal layer and the metal particles of the metal matrix of the shielding layer form a continuum by forming a grain boundary, and the metal layer and the shielding layer are continuously connected. Therefore, since the interface between the metal layer and the shielding layer does not exist, mechanical properties such as tensile strength, impact resistance, ductility, etc. per unit volume and structural stability are remarkably superior compared to the prior art even though it has high radiation shielding performance.

The shielding layer includes a metal matrix and a dispersed phase of a neutron shielding material. Specifically, the shielding layer is present as a phase in which a neutron shielding material is dispersed within a metal matrix. Through this, it is possible to impart neutron shielding performance of the canister, and the shielding layer including the neutron shielding material may have a structure integrated with the metal layer.

That is, in the spent fuel canister according to the present invention, the shielding layer is present on the outer surface portion, the metal layer is present on the inner surface portion, and the shielding layer and the metal layer are integrated with each other. In order to impart sufficient neutron shielding properties, the neutron shielding material must be in a certain amount or higher in the metal matrix.However, if the content of the neutron shielding material in the metal matrix increases, the shielding material acts as an impurity, and mechanical properties such as toughness and strength of the material may rapidly decrease. have. Therefore, while the outer surface of the canister is a shielding layer containing a neutron shielding material and imparting sufficient shielding properties, the shielding layer can implement high mechanical properties as it is integrated with a metal layer that does not contain a neutron shielding material. In addition, a shielding layer containing a neutron shielding material is located on the outer surface of the canister to realize higher shielding performance.

Although it will be described in more detail in the method of manufacturing a canister to be described later, the spent fuel canister according to the present invention undergoes a heat treatment step as it is manufactured by a 3D printing technique, and the structure of the molded product is changed due to the difference in the thermal expansion coefficient between layers during the heat treatment process. It may collapse, and there is a risk of deteriorating the mechanical properties of the finally manufactured canister.

However, the metal layer may include a first crystalline alloy in which a first amorphous alloy having a first glass transition temperature is crystallized; And a second amorphous alloy having a second glass transition temperature higher than the first glass transition temperature, and when the metal matrix of the shielding layer includes a second amorphous alloy having the second glass transition temperature, the canister In the manufacturing process (heat treatment), the collapse of the three-dimensional molded structure can be prevented, and the above-described effects can be further remarkably improved. Specifically, as shown in Fig. 1 or 2, before the first sintering, the metal layer includes the first amorphous alloy (M1) and the second amorphous alloy (M2), and the temperature during the first sintering is The range is greater than or equal to the first glass transition temperature of the 1 amorphous alloy (M1) and less than the second glass transition temperature of the second amorphous alloy (M2). Therefore, during the primary sintering, the first amorphous alloy (M1) of the metal layer is converted from a solid phase to a liquid phase and has fluidity, whereas the second amorphous alloy (M2) of the metal layer and the second amorphous alloy (M2) of the shielding layer are hard ( Rigid) Maintains the solid particulate form. Since the temperature during secondary sintering is above the crystallization initiation temperature of the first amorphous alloy (M1) and less than the crystallization initiation temperature of the second amorphous alloy (M2), the first amorphous alloy of the metal layer during the secondary sintering after the first sintering (M1) is crystallized and converted into a solid first crystalline alloy (M1), and the second amorphous alloy (M2) of the metal layer and the second amorphous alloy (M2) of the shielding layer are converted to a liquid phase. In addition, since the secondary sintering temperature is in the range below the crystallization initiation temperature of the second amorphous alloy (M2), even after the secondary sintering is completed, the metal of the metal layer and the shielding layer exist in an amorphous phase as the second amorphous alloy (M2), compared to the crystalline alloy. Mechanical properties such as strength are remarkably high and have excellent surface conditions.

That is, while the metal layer includes the first crystalline alloy and the second amorphous alloy and the shielding layer includes the second amorphous alloy, the fluidization of each layer is sequentially performed in the process of integrating the metal layer and the shielding layer through the heat treatment step. Therefore, due to the characteristics of canisters that require a certain thickness, local variations in heat applied during heat treatment, different coefficients of thermal expansion of each layer, composition differences due to the incorporation of impurities other than metals (neutron shielding material), and rapid phase change of the entire layer By reducing, it is possible to provide a spent fuel canister having excellent physical properties by preventing structural collapse due to heat treatment during manufacturing.

As described above, in the spent fuel canister according to a preferred example of the present invention, since the metal layer including the first crystalline alloy and the second amorphous alloy and the shielding layer including the second amorphous alloy are integrally formed, The 3D printing technique minimizes the problem of structural collapse such as side effects due to the difference in the thermal expansion coefficient in the manufacturing process, so the final manufactured canister has remarkably excellent structural stability and maintains the amorphous alloy state to maintain rigidity and toughness. There are remarkably excellent mechanical properties such as.

Furthermore, when an amorphous alloy is used in the present invention, the amorphous alloy has a very low coefficient of thermal expansion compared to the crystalline alloy, and therefore, due to the nature of 3D printing accompanying heat treatment, structural collapse of the molded product by heat treatment is used when only crystalline metal is used. The contrast is further minimized.

The metal of the metal layer and the metal of the shielding layer are independently of each other, one or two selected from Fe-based, Cu-based, Al-based, Mg-based, Zr-based, Ca-based, Ti-based, Ni-based, Co-based, and Hf-based. It may include more than one. That is, the amorphous alloy or crystalline alloy described above includes any one or two or more selected from Fe-based, Cu-based, Al-based, Mg-based, Zr-based, Ca-based, Ti-based, Ni-based, Co-based, and Hf-based. It may be an amorphous alloy or a crystalline alloy.

The first glass transition temperature is not particularly limited, but considering that the temperature must be strictly maintained at 400° C. or less in the entire process of dry storage of nuclear fuel after use, the first glass transition temperature is 450° C. or more, specifically It may be 450 to 950°C, more specifically 450 to 750°C, and even more specifically 450 to 600°C. Examples of amorphous alloys having a glass transition temperature of 450°C or higher include Fe-based amorphous alloys (eg, Fe-Co-Cr-Mo-CBY alloy, Fe-Si-BP alloy, Fe-YB alloy, etc.), Ni-based amorphous alloys (For example, Ni-Nb-Ta alloy, Ni-Nb-Ti-Hf alloy, Ni-Zr-Ti-Sn alloy, Ni-Nb-Ti-Hf alloy, etc.), Cu-based amorphous alloy (for example, Cu- Zr alloy, Cu-Ti-Zr-Ni alloy, Cu-Hf-Al alloy, Cu-Zr-Al alloy, Cu-Zr-Al-(Y, Ag, Be) alloy, etc.), Al-based amorphous alloy (for example, , Al-La-Y-Ni alloy, etc.), Mg-based amorphous alloy (Mg-Ni-Nd alloy, etc.), Zr-based amorphous alloy (Zr-Al-Ni alloy, Zr-Al-Cu-Ni alloy, Zr-Be -Cu-Ni-Ti alloy, Zr-Al-Co alloy, Zr-Cu-Al-Ge-Be alloy, etc.), and the like), but are not limited thereto. In addition, the above-described component-based alloy was described as an amorphous alloy, but since the amorphous alloy can be converted into a crystalline alloy through heat treatment, the aforementioned component-based alloy can also be interpreted (used) as the crystalline alloy.

When the metal layer includes the first crystalline alloy and the second amorphous alloy, the weight ratio thereof is not limited, for example, 25 to 400 parts by weight of the second amorphous alloy, specifically 50 parts by weight based on 100 parts by weight of the first crystalline alloy. To 300 parts by weight. If this is satisfied, it is possible to more easily convert the fluidity of each layer in the heat treatment process including the first sintering step and the second sintering step, thereby further minimizing the problem of collapse of the structure of the molded article by heat treatment and having better mechanical properties. Can provide.

As described above, since a shielding layer including a metal layer and a shielding material is present on the inner and outer surfaces of the canister, respectively, it has high neutron shielding performance and excellent mechanical properties at the same time. At this time, it may be preferable that the thickness of the metal layer is greater than or equal to the thickness of the shielding layer, for example, the thickness ratio of the metal layer and the shielding layer is 100:10 to 100. If this is satisfied, it is possible to realize higher mechanical properties by providing a semi-permanent sufficient shielding property, while the shielding layer can be integrated with a metal layer containing no neutron shielding material according to a higher interaction.

The thickness of the canister may be sufficient as long as sufficient neutron shielding performance and required structural stability can be ensured, for example, 5 mm or more, specifically 5 to 50 mm, and more specifically 5 to 20 mm. However, this is only described as a specific example, of course, the present invention is not limited thereto.

The content of the neutron shielding material contained in the shielding layer may be sufficient as long as it can impart sufficient neutron shielding performance, for example, 0.01 to 10 parts by weight of the neutron shielding material, specifically 0.1 to 10 parts by weight per 100 parts by weight of the metal matrix. , More specifically, it may contain 0.1 to 5 parts by weight. However, this is only described as a specific example, and the present invention is not interpreted as being limited thereto.

The neutron shielding material may be a variety of known materials, for example, any one selected from boron carbide, boron nitride, boron oxide, zinc borate, aluminum hydroxide, hafnium, hafnium diboride, titanium diboride, ferroboron and uranium dioxide. Or two or more. As a preferred example, the neutron shielding material may be a boron-based shielding material, and specifically, boron carbide is exemplified. In particular, when the metal matrix of the shielding layer contains Fe-based metal and boron carbide is used as a neutron shielding material, high mechanical properties can be implemented while having sufficient neutron shielding performance.

The shape of the neutron shielding material is not largely limited, and various examples such as a spherical shape, an oval shape, a rod shape, and a flake shape may be mentioned, and it may be easy to have a spherical shape or an elliptical shape. However, this is only described as a specific example, and the present invention is not interpreted as being limited thereto.

The size of the neutron shielding material may be sufficient as long as it is easy to disperse on the metal matrix and provides the required shielding performance. As a preferred example, the average particle diameter of the neutron shielding material may be 500 nm to 300 µm, preferably 500 nm to 100 µm, and a particle diameter of D50 corresponding to 50% of the total volume when the volume is accumulated from small particles. , More preferably 500 nm to 50 μm. When the neutron shielding material has such an average particle diameter, it may be more evenly dispersed and present on the metal matrix, and incorporation in the metal matrix may be further improved.

Hereinafter, a method of manufacturing a spent fuel canister according to the present invention will be described.

The method of manufacturing a spent fuel canister according to the present invention may be through various known metal 3D printing techniques, and specifically, the method of manufacturing a spent fuel canister according to the present invention includes a metal layer composition and a shielding layer composition face-to-face ( layer by layer) technique to produce a case of a three-dimensional molded article having an inner surface of a metal layer and an outer surface of a shielding layer by 3D printing, and a heat treatment step of heat treating the three-dimensional molded article, and the metal layer composition Silver metal powder is contained, and the shielding layer composition may contain a metal powder and a neutron shielding material.

In a preferred example, the metal powder of the metal layer composition comprises: a first amorphous alloy having a first glass transition temperature; And a second amorphous alloy having a second glass transition temperature higher than the first glass transition temperature, wherein the metal powder of the shielding layer composition includes a second amorphous alloy having the second glass transition temperature. I can. In this case, the heat treatment step may include a first sintering step and a second sintering step. In the first sintering step, the sintering temperature is equal to or higher than the first glass transition temperature of the first amorphous alloy and the second amorphous alloy. 2 The glass transition temperature may be less than the range, and in the second sintering step, the sintering temperature may be greater than or equal to the crystallization initiation temperature of the first amorphous alloy and less than the crystallization initiation temperature of the second amorphous alloy. When the metal powder of the metal layer composition contains the first amorphous alloy and the metal powder of the shielding layer composition contains the second amorphous alloy and primary sintering and secondary sintering having the above-described specific temperature range are performed It is possible to provide a spent fuel canister with excellent physical properties by preventing structural collapse due to heat treatment.

When using metal 3D printing, due to the characteristics of canisters that require a certain thickness, local variations in heat applied during heat treatment, different coefficients of thermal expansion of each layer, composition differences due to mixing of impurities other than metal (neutron shielding material), and overall It may cause structural collapse of the 3D molded product due to a rapid phase change of the layer, and therefore, it may be difficult to manufacture a canister with a complex and precise structure.Through the above method, the fluidity of each layer according to the sintering temperature is sequentially This problem can be minimized as it can be secured. Specifically, during primary sintering, the first amorphous alloy of the metal layer is converted to a liquid phase, and the second amorphous alloy of the metal layer and the shielding layer maintains a solid phase, and during the secondary sintering, the first amorphous alloy of the metal layer is crystallized and converted into a solid phase. Since the second amorphous alloy of the metal layer and the shielding layer is converted into a liquid phase, structural collapse of the 3D molded product can be minimized.

In the present specification, it is preferable that the heat treatment time of the primary sintering and the heat treatment time of the secondary sintering are performed after the primary sintering is sufficiently performed so that the primary sintering and the secondary sintering are distinguished. As a specific example, the heat treatment time during the first sintering is, for example, 1 minute to 10 hours, for example, 8 hours or less, 5 hours or less, 3 hours or less, 1 hour or less so that the first amorphous alloy of the metal layer has sufficient fluidity. , May be 30 minutes or less, in which case the lower limit value may be 1 minute, 3 minutes, 5 minutes, or 10 minutes. As a specific example, the heat treatment time during the secondary sintering is, for example, 1 minute to 10 hours, in another example, 8 hours or less, 5 hours or less so that the second amorphous alloy of the metal layer and the second amorphous alloy of the shielding layer have fluidity, It may be 3 hours or less, 1 hour or less, 30 minutes or less, and the lower limit value may be 1 minute, 3 minutes, 5 minutes, 10 minutes or 30 minutes.

Through this method, the metal particles (Grain) of the metal layer and the metal particles (Grain) of the metal matrix of the shielding layer can be converted into a state in which a continuous body is formed by forming a grain boundary. Here, the metal particles do not mean particles of the metal powder included in the composition themselves, but mean particles used to distinguish between amorphous and crystalline metals.

The above-described method of manufacturing a spent fuel canister according to the present invention can be divided into a method using an adhesive and a method not using an adhesive as follows.

A method of using an adhesive, comprising: a first aspect of performing heat treatment (primary sintering and secondary sintering) after manufacturing a molded article by laminating surfaces in a unit process in a layer by layer through an adhesive; And a second aspect of secondary sintering after manufacturing a molded article by laminating cotton in a unit process including a surface forming step and a sintering step.

As a first aspect of using an adhesive, in the method of manufacturing a spent fuel canister according to an example of the present invention, in the molding step, the metal layer composition and the shielding layer composition may further include a binder, and in the heat treatment step, heat treatment By this, the binder in the molded article can be removed. That is, the manufacturing method comprises a forming step of 3D printing a metal layer composition and a shielding layer composition using a layer by layer technique to manufacture a case of a three-dimensional molded article whose inner surface is made of a metal layer and the outer surface is made of a shielding layer, and the 3 A heat treatment step of heat-treating the dimensional molding may be included, wherein each composition includes a binder, and in the heat treatment step, the binder in the molded product may be removed by heat treatment.

In addition, as a first aspect of using an adhesive, the manufacturing method of a spent fuel canister according to a preferred example of the present invention comprises a metal layer composition and a shielding layer composition by 3D printing by a layer by layer technique. It may include a molding step of manufacturing a case of a three-dimensional molded article having a top outer surface of a shielding layer, and a heat treatment step of heat-treating the three-dimensional molded article, and the heat treatment step may include a first sintering step and a second sintering step. have. Specifically, in the molding step, the metal layer composition and the shielding layer composition each including a binder are sprayed onto the substrate, but are sprayed so that the surface has a desired shape. At this time, the outer surface of the molded product is positioned so that the shielding layer composition is positioned, and the inner face of the molded product is distributed so that the metal layer composition is positioned to form a surface, and the binder is cured and laminated to finally produce a 3D molded product having a desired shape. Subsequently, heat is applied to the 3D molding to perform primary sintering and secondary sintering to remove the binder in the molding. At this time, the primary sintering satisfies the temperature range of the aforementioned primary sintering, and the secondary sintering satisfies the temperature range of the secondary sintering described above.

The content of the binder contained in each composition may be sufficient as long as it has an adhesive strength enough to maintain the stacked structure in which each unit surface is stacked, and this content can be selected in consideration of the shape, composition, and size of the metal powder. As a specific example, 0.1 to 100 parts by weight, specifically 1 to 50 parts by weight of the binder may be used based on 100 parts by weight of the metal powder, but is not limited thereto.

As a second aspect of using an adhesive, the method of manufacturing a spent fuel canister according to an example of the present invention comprises a powdery surface forming process and an adhesive composition spraying process using a metal layer composition and a shielding layer composition by a layer by layer technique. It may include a forming step of manufacturing a case of a three-dimensional molded article in which the inner surface is made of a metal layer and the outer surface is made of a shielding layer by repeating the unit process including 3D printing, and a heat treatment step of heat-treating the three-dimensional molded article. At this time, in the heat treatment step, the binder in the molded product may be removed by heat treatment.

As a second aspect using an adhesive, a method of manufacturing a spent fuel canister according to a preferred example includes a powdery surface forming process and an adhesive composition spraying process by using a metal layer composition and a shielding layer composition as a layer by layer technique. 3D printing by repeating the unit process may include a forming step of manufacturing a case of a three-dimensional molded article in which an inner surface is made of a metal layer and an outer surface is a shielding layer, and a heat treatment step of heat-treating the three-dimensional molded article, the heat treatment step May include a first sintering step and a second sintering step. Specifically, in the molding step, the metal layer composition and the shielding layer composition are sprayed onto the substrate, but are sprayed so that the surface has a desired shape. At this time, the outer surface of the molded product is positioned so that the shielding layer composition is positioned, and the inner face of the molded product is distributed so that the metal layer composition is positioned to form a powdery surface, and the adhesive composition is sprayed thereon to sufficiently wet the adhesive composition on the powder. Then, the sprayed adhesive composition is cured and the surfaces are laminated to finally produce a 3D molded product having a desired shape. Subsequently, heat is applied to the 3D molded product to perform primary sintering and secondary sintering to remove the binder in the molded product. At this time, the primary sintering satisfies the temperature range of the aforementioned primary sintering, and the secondary sintering satisfies the temperature range of the secondary sintering described above.

In the spraying process, spraying conditions may refer to documents known in the art of metal binder jet printing technology.

The adhesive composition may include a binder and a solvent, and the weight ratio thereof may be such that the metal powder can be adhered by spraying the adhesive composition onto the metal powder and curing. For example, the binder is 0.1 based on the total weight of the adhesive composition. It can be used in to 20% by weight, specifically 1 to 10% by weight. However, this is only described as a specific example, and the present invention is not interpreted as being limited thereto.

In the first aspect or the second aspect using an adhesive, the curing time and curing temperature of the binder may be such that metal powders are adhered to each other to maintain the shape of the 3D molding, for example, 5 to 100°C, and the curing time Silver may be appropriately adjusted according to the type of binder, the amount of binder or solvent used, and environmental conditions (temperature, humidity, pressure, etc.).

In the first or second aspect using an adhesive, the binder may be any known in the art of metal 3D printing, and for example, alkyl cellulose-based, polyalkylene carbonate-based, polyalkylene oxide-based, lignin A binder including any one or two or more selected from the system and polyvinyl alcohol system may be used. In the above, the alkyl cellulose includes, for example, an alkyl cellulose having an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms such as methyl cellulose or ethyl cellulose. Examples of the polyalkylene oxide may include an alkylene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms such as polyethylene oxide or polypropylene oxide. Polyalkylene oxide may be exemplified, and the polyalkylene carbonate includes an alkylene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms such as polyethylene carbonate. Polyalkylene carbonate and the like may be exemplified, and as polyvinyl alcohol, polyvinyl alcohol or polyvinyl acetate may be exemplified. However, this is only described as a specific example, and the present invention is not interpreted as being limited thereto.

In a method that does not use an adhesive, the method of manufacturing a spent fuel canister according to an example of the present invention comprises a powdery surface forming process and a sintering process in a layer by layer technique of a metal layer composition and a shielding layer composition. 3D printing by repeating the unit process may include a molding step of manufacturing a case of a three-dimensional molded article having an inner surface of a metal layer and an outer surface of a shielding layer, wherein the metal layer composition contains metal powder, and the shielding layer The composition may contain metal powder and a neutron shielding material.

As a method without using an adhesive, the method of manufacturing a spent fuel canister according to a preferred example is a unit process including a powdery surface forming process and a sintering process by using a metal layer composition and a shielding layer composition as a layer by layer technique. By repeating 3D printing, a forming step of manufacturing a case of a three-dimensional molded article having an inner surface of a metal layer and a shielding layer of an outer surface thereof, and a heat treatment step of heat treatment of the three-dimensional molded article may be included. Specifically, in the molding step, the metal layer composition and the shielding layer composition are sprayed onto the substrate, but are sprayed so that the surface has a desired shape. At this time, the outer surface of the molded product is positioned so that the shielding layer composition is located, and the inner surface of the molded product is distributed so that the metal layer composition is positioned to form a powdery surface, and a heat source such as a laser is applied so that the powdery surface is sintered (primary sintering). By laminating, a 3D molded article having a desired shape is finally produced. At this time, sintering satisfies the temperature range of the above-described primary sintering. Subsequently, heat is applied to the 3D molded product to perform secondary sintering to remove the binder in the molded product, wherein the sintering satisfies the temperature range of the secondary sintering described above.

In the heat treatment mentioned in the present invention, various heat sources may be used as the means, and various known heat sources such as hot air, infrared rays, and lasers may be used. As a preferred example, in the case of a method through a unit process including a powdery surface forming process and a sintering process, the use of a laser as a heat source is good in terms of being able to manufacture a complex and precise 3D molded product. In the case of a method of sintering an integral part, a heat source such as hot air or infrared rays that can heat-treat the entire molded product at once may be good.

The shape of the metal powder is not largely limited, and various examples such as a spherical shape, an oval shape, a rod shape, and a flake shape may be exemplified, and it may be easy to have a spherical shape or an oval shape. However, this is only described as a specific example, and the present invention is not interpreted as being limited thereto.

The average particle diameter of the metal powder may be sufficient as long as 3D printing is possible, for example, 5 to 100 µm, specifically 10 to 50 µm. However, this is only described as a preferred example, and the present invention is not interpreted as being limited thereto.

The spent fuel canister according to an embodiment may further include a basket for fixing the spent fuel accommodated in the inner space of the case. Accordingly, the basket may be located in the inner space of the case, and may have a conventional structure used to fix the spent nuclear fuel in the canister in the field of dry storage of spent nuclear fuel. For example, the basket may have a rectangular grid structure, and may have a shape in which a plurality of rectangular tubes extending in the longitudinal direction are gathered. At this time, spent nuclear fuel may be located inside each square tube. In addition, it goes without saying that the canister may further include a supporting member for fixing and supporting the basket together with the basket or a storage member into which the basket is inserted.

The spent fuel canister according to the present invention may contain the spent fuel after the canister is finally manufactured, or the manufacturing process may be completed while the spent fuel is received during the manufacturing process of the canister.

As a specific example, when the spent fuel is accommodated after the canister is finally manufactured, the canister includes: a main body having an inner space that is opened at one end and allows the spent fuel to be mounted; It may include a case including; a cover seated on the open end of the body and fixed to the body. In this case, the coupling method of the main body and the cover may be any known fastening means, and for example, an external fixing member such as bolt-nut coupling and/or welding may be used.

As a specific example, the manufacturing process is completed while the spent fuel is received during the manufacturing process of the canister.Since the primary sintering can be performed through laser, it is possible to safely use 3D printing techniques without transferring heat to the spent fuel. Case molding is possible, and the secondary sintering is based on the spent fuel, after forming the canister molded product (including the primary sintering using a heat source such as laser) by 3D printing from the lower end of the spent fuel to the side and then the upper end. (At this time, the spent fuel does not need to be located inside the molding), and the canister body is manufactured by secondary sintering. Then, after the spent nuclear fuel is charged into the main body, the cover is subsequently formed and sintered (primary and secondary) by 3D printing at the upper end of the main body to integrally manufacture the canister. In this case, the spent nuclear fuel is accommodated in the main body, and as the main body and the cover are integrated, the canister has a solid structure in which the canister is integrated, so that structural stability and durability are remarkably excellent.

In one embodiment, the spent fuel canister may be a container for dry storage of spent nuclear fuel, and may be a container for transport, storage, or transport and storage of the spent nuclear fuel.

Claims (19)

As a spent nuclear fuel canister comprising a case having an inner space to accommodate the spent nuclear fuel,
The case is made of a metal layer on the inner surface and a shielding layer on the outer surface, and the metal layer and the shielding layer are integrally formed,
The shielding layer comprises a dispersed phase of a metal matrix and a neutron shielding material,
The metal layer includes: a first crystalline alloy in which a first amorphous alloy having a first glass transition temperature is crystallized; And a second amorphous alloy having a second glass transition temperature higher than the first glass transition temperature,
A spent fuel canister, characterized in that the metal matrix of the shielding layer comprises a second amorphous alloy having the second glass transition temperature. The method of claim 1,
The spent fuel canister, wherein the metal particles of the metal layer and the metal particles of the metal matrix of the shielding layer form a continuum by forming a grain boundary with each other. delete The method of claim 1,
The spent nuclear fuel canister having the first glass transition temperature of 450°C or higher. The method of claim 1,
The metal layer is a spent fuel canister comprising 25 to 400 parts by weight of the second amorphous alloy based on 100 parts by weight of the first crystalline alloy. The method of claim 1,
Spent fuel canister with a thickness ratio of the metal layer and the shielding layer of 100:10 to 100. The method of claim 6,
The thickness of the case is 5 to 50 mm spent nuclear fuel canister. The method of claim 1,
The shielding layer is a spent fuel canister comprising 0.1 to 10 parts by weight of the neutron shielding material based on 100 parts by weight of the metal matrix. The method of claim 1,
The metal of the metal layer and the metal of the shielding layer are independently of each other, one or two selected from Fe-based, Cu-based, Al-based, Mg-based, Zr-based, Ca-based, Ti-based, Ni-based, Co-based, and Hf-based. Spent fuel canister including the above. The method of claim 1,
The neutron shielding material is a spent nuclear fuel comprising any one or two or more selected from boron carbide, boron nitride, boron oxide, zinc borate, aluminum hydroxide, hafnium, hafnium diboride, titanium diboride, ferroboron and uranium dioxide Canister. As a method of manufacturing a spent fuel canister comprising a case having an internal space to accommodate the spent fuel,
A forming step of 3D printing the metal layer composition and the shielding layer composition by using a layer by layer technique to manufacture a case of a three-dimensional molded article whose inner surface is made of a metal layer and the outer surface is made of a shielding layer, and
Including a heat treatment step of heat treatment of the three-dimensional molding,
The metal layer composition contains a metal powder, and the shielding layer composition is a method of manufacturing a spent nuclear fuel canister containing metal powder and a neutron shielding material. The method of claim 11,
The metal powder of the metal layer composition may include a first amorphous alloy having a first glass transition temperature; And a second amorphous alloy having a second glass transition temperature higher than the first glass transition temperature, wherein the metal powder of the shielding layer composition includes a second amorphous alloy having the second glass transition temperature,
The heat treatment step includes a first sintering step and a second sintering step,
In the first sintering step, the sintering temperature is in a range equal to or higher than the first glass transition temperature of the first amorphous alloy and less than the second glass transition temperature of the second amorphous alloy,
In the second sintering step, the sintering temperature is in a range equal to or higher than the crystallization initiation temperature of the first amorphous alloy and less than the crystallization initiation temperature of the second amorphous alloy. The method of claim 12,
In the first sintering step, during sintering, the first amorphous alloy of the metal layer is converted to a liquid phase, and the second amorphous alloy of the metal layer and the shielding layer maintains a solid phase,
In the second sintering step, during sintering, the first amorphous alloy of the metal layer is crystallized and converted to a solid phase, and the second amorphous alloy of the metal layer and the shielding layer is converted to a liquid phase. The method of claim 11,
In the molding step, the metal layer composition and the shielding layer composition further include a binder,
In the heat treatment step, a method of manufacturing a spent fuel canister in which the binder in the molded product is removed by heat treatment. The method of claim 11,
In the forming step, the metal layer composition and the shielding layer composition are 3D printed by repeating a unit process including a powdery surface forming process and an adhesive composition spraying process using a layer by layer technique, whereby the inner surface is made of a metal layer and the outer surface is shielded. It includes a forming step of manufacturing a case of a three-dimensional molded article consisting of a layer,
The adhesive composition spraying process is a process of spraying an adhesive composition containing a binder and a solvent onto the formed powdery surface,
In the heat treatment step, a method of manufacturing a spent fuel canister in which the binder in the molded product is removed by heat treatment. As a method of manufacturing a spent fuel canister comprising a case having an internal space to accommodate the spent fuel,
The metal layer composition and the shielding layer composition are 3D printed by repeating a unit process including a powdery surface forming process and a sintering process using a layer by layer technique, and the inner surface is made of a metal layer and the outer surface is made of a shielding layer. And a molding step of manufacturing a case of,
The metal layer composition contains a metal powder, and the shielding layer composition is a method of manufacturing a spent nuclear fuel canister containing metal powder and a neutron shielding material. The method of claim 16,
After the forming step, further comprising a heat treatment step of heat-treating the three-dimensional molding,
The metal powder of the metal layer composition may include a first amorphous alloy having a first glass transition temperature; And a second amorphous alloy having a second glass transition temperature higher than the first glass transition temperature, wherein the metal powder of the shielding layer composition includes a second amorphous alloy having the second glass transition temperature,
In the molding step, the sintering temperature is in a range equal to or higher than the first glass transition temperature of the first amorphous alloy and less than the second glass transition temperature of the second amorphous alloy,
In the heat treatment step, the sintering temperature is above the crystallization initiation temperature of the first amorphous alloy and less than the crystallization initiation temperature of the second amorphous alloy. The method of claim 17,
In the forming step, during sintering, the first amorphous alloy of the metal layer is converted to a liquid phase, and the second amorphous alloy of the metal layer and the shielding layer maintains a solid phase,
In the heat treatment step, during sintering, the first amorphous alloy of the metal layer is crystallized and converted into a solid phase, and the second amorphous alloy of the metal layer and the shielding layer is converted to a liquid phase. The method according to any one of claims 11 to 15, 17 and 18,
The method of manufacturing a spent fuel canister in which the metal particles of the metal layer and the metal particles of the metal matrix of the shielding layer form a continuum through the heat treatment step.

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