KR102102977B1 - Method of manufacturing nuclear fuel pellet consisting of duplex grains - Google Patents

Abstract

The present invention relates to a method for manufacturing a nuclear fuel sintered body having a double crystal grain structure, and without using a dual structure molding method, a compound containing a silicon element or silicon oxide is penetrated outside the molded body to form an additive and a liquid in the molded body to form a sintered body. It is to provide a method for manufacturing a sintered uranium oxide body having a double grain structure in which the grain size of the outer region is larger than the grain size of the inner region.
According to the present invention as described above, by providing a nuclear fuel sintered body having a double grain structure having different outer and inner parts, through the functional interaction of grains, suppression of rim structure formation and mechanical interaction between the sintered body and the cladding tube are alleviated. This greatly improves the safety and combustion degree of nuclear fuel at high combustion, and can increase the operating power and operating temperature.

Description

Manufacturing method of nuclear fuel sintered body with double grain structure {METHOD OF MANUFACTURING NUCLEAR FUEL PELLET CONSISTING OF DUPLEX GRAINS}

The present invention relates to a method for manufacturing a sintered nuclear fuel, and more particularly, to provide a method for manufacturing a sintered nuclear fuel having a different size grain structure in the outer and inner regions.

A method of manufacturing a uranium oxide sintered body used as a nuclear fuel is obtained by adding and mixing an additive to the uranium oxide powder and compression molding the mixture to a pressure of about 2 ton / cm ² or higher in a reducing gas atmosphere at a temperature of about 1700 to 1800 ℃ 2 It is prepared by sintering for 8 hours.

The uranium oxide sintered body manufactured by the above process has a relative density of 95% or more relative to the theoretical density, and the grain size generally has a range of 5 to 8 μm, and the grain size is such as sintering temperature, sintering time, U ₃ O ₈ and UO ₂ , etc. It varies depending on the mixed composition of uranium oxide, and the grain size has a uniform grain size throughout the sintered body.

The sintered uranium oxide for nuclear fuel is charged to a zirconium alloy cladding tube, filled with helium at a pressure of about 150 bar, and then a sealed bundle of nuclear fuel rods is used as a heat source in a nuclear reactor.

The sintered body in the nuclear fuel rod burned over 40 to 45 GDW / MtU in the nuclear reactor is Pu-239 produced locally due to the neutron resonance absorption of U-238 at the edge, and the local combustion degree is 2 to 3 than the average combustion degree of the sintered body. As it doubles, an abnormal tissue called a rim structure or a high burnup structure begins to form.

The rim structure is composed of a number of pores having a porosity of about 10 to 20% and a size of 1 μm or less and very small grains of 0.1 to 0.5 μm.

The rim structure is increased inward from the surface portion as the degree of combustion increases.

The reason for the formation of the rim structure is that the combustion degree in the rim is much higher than the average combustion degree of the sintered body and at the same time the temperature is low, and depletion, bubble formation and grain refinement of fission gases such as xenon on the uranium oxide matrix are It is known to be formed while being sequentially generated.

When the fuel rod combustion degree is 60 GWD / MtU or more, the porosity is increased by a large amount of rim structure, and the nuclear fuel temperature increases due to a decrease in cooling efficiency. Due to this increase in temperature, the fission gas emission is rapidly increased, which is a problem for high combustion of nuclear fuel. In addition, due to the volume expansion of the sintered body due to the increase in porosity, the contact between the cladding tube and the surface of the sintered body causes stress concentration, and the probability of occurrence of damage to the cladding tube in the stress-concentrated region is increased through corrosion by fission emission. In addition, there is a possibility that the pores of the tissue constituting the rim structure of the sintered body may form a channel and cause desorption of fine particles, so that they can be easily released when the sheath is damaged.

Therefore, in order to burn nuclear fuel for a long time, it is necessary to suppress the rim structure as much as possible, and it is known that an increase in the grain size of the sintered body has an effect of suppressing the expansion of the rim structure.

In addition, in relation to the increase in the size of the grain, a high-combustion fuel has been developed in order to increase the economic efficiency of the fuel, and the main technology of the high-combustion fuel is an increase in the grain size. The larger the grain size of the sintered body, the longer the distance that the fission gas generated inside the crystal reaches the grain boundary has the advantage of reducing the amount of fission gas emission.

On the other hand, an increase in grain size causes a decrease in creep performance, and an increase in the sintered body swelling rate due to an increase in the fission gas trapping performance increases, resulting in difficulty in deformation of the sintered body due to swelling, which results in stress on the cladding tube and increase the possibility of damage. This is because creep creep rate is generally inversely proportional to the square of the grain size.

In general, a method of increasing the creep strain rate of a single-phase polycrystalline uranium oxide sintered body is a method of increasing the excess oxygen x of UO _{2 + X} and a method of doping elements contained in the additive into the uranium lattice using the additive. . Both methods increase vacancy in the uranium oxide to increase the rate of creep deformation rate, uranium diffusion rate, and consequently, the movement of voids and dislocations due to the increase in diffusion rate actively increases the creep deformation rate. . Therefore, in order to improve the creep deformation rate, it is necessary to form a large amount of vacancy inside the grain while reducing the size of the grain.

Therefore, the sintered body suitable for high-combustion fuel having the function of reducing the fission gas emission, suppressing the formation of a rim structure, and alleviating the interaction (PCl) between the fuel sintered body and the cladding tube is doped with additives in the inner region of the sintered body. By forming small crystal grains, it improves creep strain rate, responds to creep stress relaxation and total volume change, and forms large grains in the outer region to suppress rim structure formation and reduce fission gas emission. A sintered body having a double crystal grain structure with different inside is preferred.

The manufacturing method of a nuclear fuel sintered body having a double grain structure with different outer and inner parts as described above is formed in the Republic of Korea Patent Publication No. 2001-0071578 by adding niobium pentoxide (Nb ₂ O ₅ ) to a larger grain size of 25 µm or more and A method for producing a sintered nuclear fuel structure having a small grain structure of 12 to 15 µm in size has been proposed. However, the manufacturing method is a dual structure molding method in which fuel containing a composition having large crystal grains in the outer region and fuel containing a composition having small crystal grains in the inner region are independently arranged and molded, and the molding process is very complicated and takes a long time. There is a disadvantage that productivity is lowered and is not economical due to an increase in manufacturing cost. In addition, since the thickness of the outer region of the sintered body is controlled by the molding process, there is a limit in the thickness control.

Although the particle size distribution of the outer and inner regions is different, a technique for manufacturing a sintered body having a double grain structure has been proposed as follows.

In Korean Patent Registration No. 10-0451711, the fuel molded body is sintered for 10 minutes to 15 hours at 1400 to 1750 ° C. in an oxygen partial pressure atmosphere having a carbon dioxide / hydrogen gas ratio of 0.15 to 0.70, and the grain size of the outer region of the sintered body is 3 to 15 μm. A method of manufacturing a sintered body having a grain structure in which the outer and inner parts of the inner region have different grain sizes from 1.5 to 8 times larger than the outer region is known.

In Japanese Patent Laid-Open No. 64-29796, 0.1 to 0.3% by weight of Cr ₂ O ₃ is added to UO ₂ powder to sinter for 10 to 20 hours at 1600 ° C. or less, so that the grain size in the outer region is about 10 μm and the grain size in the inner region. A method for manufacturing a sintered body having a double grain structure of about 30 μm has been disclosed.

In the Republic of Korea Patent No. 10-0272727, UO ₂ granules containing 0.3 to 0.5% Nb ₂ O ₅ are added to UO ₂ powder, so that 6 μm-sized grains and 10-30 μm-sized grains are uniform in the inner and outer regions of the sintered body. A well-distributed sintered body manufacturing method is known.

However, all of the above methods minimize the interaction between the nuclear fuel sintered body and the cladding material (PCl) by improving creep stress relaxation performance, while small grains of 15 µm or less form the outer region of the sintered body or are homogeneously distributed, resulting in a rim structure. structure) There is a disadvantage that it is not effective in suppressing formation.

In order to suppress the rim structure, Korean Patent Registration No. 10-0836954 proposed a sintered body with irregularities to maintain a high temperature on the surface of the sintered body. Because of this difference, there is a disadvantage that direct application is difficult.

The object of the present invention, as described above, in order to solve the problems of the prior art, by injecting a compound containing silicon or silicon oxide into the fuel mixture containing the additive, through reaction with the mixed additive, the outside of the fuel sintered body In the manufacture of a nuclear fuel sintered body having a double grain structure having different grain sizes in the outer and inner regions of the sintered body by increasing the particle size of the region.

In order to achieve the above object, the present invention provides a method for producing a sintered nuclear fuel, comprising the steps of: (1) mixing an additive with a fuel powder to prepare a mixture; (2) compression molding the mixture to produce a molded body; And (3) sintering in an inert atmosphere in a state in which silicon elements or silicon oxides coexist with respect to the molded body, characterized in that the grain size in the outer region of the sintered body is larger than the grain size in the inner region, double grain structure One aspect of the present invention is to provide a method for manufacturing a sintered nuclear fuel having a structure.

The nuclear fuel powder may be uranium oxide.

The nuclear fuel powder further includes plutonium dioxide (PuO ₂ ), and the plutonium dioxide (PuO ₂ ) may be 1 to 30% by weight compared to 100% by weight of the nuclear fuel powder.

The nuclear fuel powder further includes gadolinium oxide (III) (Gd ₂ O ₃ ), and the gadolinium oxide (III) (Gd ₂ O ₃ ) may be 1 to 15% by weight compared to 100% by weight of the nuclear fuel powder.

The nuclear fuel powder may further include aviation oxide (Er ₂ O ₃ ), and the aviation oxide (Er ₂ O ₃ ) may be 0.5 to 8% by weight compared to 100% by weight of the nuclear fuel powder.

The additive may be at least one material selected from the group consisting of Mg, Al, Ca, Bi, Ti, Cr oxide, nitride, sulfide, phosphide, carbide, and particle size of nuclear fuel such as uranium oxide by reacting with silicon oxide It may be an element containing an increase.

In step (1), the nuclear fuel powder is 99.5 to 99.995 wt%, and the additive may be 0.005 to 0.5 wt%.

In step (3), the silicon element may be provided from a chemical reaction between a compound containing at least one material or a silicon element selected from the group consisting of metal silicon, silicon alkoxide, and silicon alkylsilane, and a heterogeneous material.

The sintering temperature may be 1400 to 1800 ℃.

According to the present invention as described above, by providing a nuclear fuel sintered body having a double grain structure with different outer and inner parts, the large grains constituting the outer region improve the collection performance of the nuclear fission gas and suppress the release of the fuel gas, and the rim structure (rim structure) Formation can be suppressed, and the small grains constituting the inner region alleviate the mechanical interaction between the sintered body and the cladding tube by improving the creep deformation rate of the existing fuel sintered body. For this reason, through the functional interaction of the crystal grains constituting the outer and inner regions, the safety and combustion degree of nuclear fuel at high combustion can be greatly improved, and the operation output and operation temperature can be increased.

In addition, the manufacturing method provided in the present invention does not change the sintering atmosphere or undergo a separate reduction process after sintering, while using a conventional commercial nuclear fuel sintered body manufacturing process that maintains a reducing atmosphere without using a dual structure forming method. It has an economic advantage because it can manufacture a nuclear fuel sintered body having a double grain structure with different outer and inner parts.

1 is an axial cross-sectional view of a nuclear fuel sintered body having a double crystal grain structure according to one embodiment of the present invention.
2 is a photograph of the grain structure (a) of the outer region of the sintered body manufactured by the method of Example 1 of the present invention, the grain structure (b) of the inner region, the boundary (c) of the outer and inner regions, and the cross-section of the sintered body (d) This is a 500x magnification with Nikon's MA200 camera.
3 is a photograph of the grain structure (a) of the outer region and the grain structure (b) of the inner region of the sintered body manufactured by the method of Example 2 of the present invention, which is a photograph enlarged 500 times with a Nikon MA200 camera.
4 is a photograph of the grain structure (a) of the outer region and the grain structure (b) of the inner region of the sintered body manufactured by the method of Example 3 of the present invention, which is a photograph enlarged 500 times with a Nikon MA200 camera.
5 is a photograph of the grain structure (a) of the outer region and the grain structure (b) of the inner region of the sintered body manufactured by the method of Example 4 of the present invention, a photograph enlarged 500 times with a Nikon MA200 camera.
FIG. 6 is a photograph of a grain structure (a) of the outer region and a grain structure (b) of the inner region of the sintered body manufactured by the method of Example 5 of the present invention, which is a photograph enlarged 500 times with a Nikon MA200 camera.
7 is a photograph of the grain structure (a) of the outer region and the grain structure (b) of the inner region of the sintered body manufactured by the method of Example 6 of the present invention, a photograph magnified 500 times with a Nikon MA200 camera.
8 is a photograph of the grain structure (a) of the outer region and the grain structure (b) of the inner region of the sintered body manufactured by the method of Example 7 of the present invention, a photograph enlarged 500 times with a Nikon MA200 camera.
FIG. 9 is a photograph of the grain structure (a) of the outer region and the grain structure (b) of the inner region of the sintered body manufactured by the method of Example 8 of the present invention, which is a photograph enlarged 500 times with a Nikon MA200 camera.
FIG. 10 is a photograph of the grain structure (a) of the outer region and the grain structure (b) of the inner region of the sintered body manufactured by the method of Example 9 of the present invention, which is a photograph enlarged 500 times with a Nikon MA200 camera.

Hereinafter, the present invention will be described in detail.

The present invention reacts with silicon oxide, a uranium oxide mixture containing an element that increases the particle size of uranium oxide, and a silicon and silicon oxide-containing gas reacting with a double crystal grain structure having improved external and internal properties and improved creep stress relaxation characteristics , To provide a method for producing a sintered uranium oxide body having improved fission product gas trapping property and suppressing formation of a rim structure. In the case of silicon, it is oxidized to silicon oxide by reacting with oxygen of uranium oxide, and the mechanism of forming double crystal grains is the same.

Referring to FIG. 1, a cross-sectional view of a cylindrical fuel sintered body manufactured by the method provided by the present invention is shown, and the grain size of the outer region 2 constituting the nuclear fuel sintered body 1 has a large grain size of 15 μm or more, The inner region 3 has grains having a size of less than 3 to 15 μm. The thickness of the outer region has a thickness including 50 to 3000 μm in the center direction from the outer surface.

A method for producing a nuclear fuel sintered body having a double crystal grain structure according to one embodiment of the present invention includes: (1) preparing a mixture by mixing an additive with a nuclear fuel powder; (2) compression molding the mixture to produce a molded body; And (3) sintering in an inert atmosphere in a state in which silicon elements or silicon oxides coexist with respect to the molded body. Through this, a nuclear fuel sintered body having a double grain structure in which the grain size in the outer region of the sintered body is larger than the grain size in the inner region is manufactured.

The nuclear fuel powder may use uranium oxide alone, or the nuclear fuel powder further includes plutonium dioxide (PuO ₂ ), and the plutonium dioxide (PuO ₂ ) is 1 to 30% by weight compared to 100% by weight of the nuclear fuel powder You can. Alternatively, the nuclear fuel powder may further include gadolinium oxide (III) (Gd ₂ O ₃ ), and the gadolinium oxide (III) (Gd ₂ O ₃ ) may be 1 to 15% by weight compared to 100% by weight of the nuclear fuel powder. . Alternatively, the nuclear fuel powder may further include aviation oxide (Er ₂ O ₃ ), and the aviation oxide (Er ₂ O ₃ ) may be 0.5 to 8% by weight compared to 100% by weight of the nuclear fuel powder. Plutonium oxide is used as nuclear fuel in the form of uranium oxide and mixed oxide (MOX) fuel, and the content of plutonium oxide in MOX for light water reactors and highways is limited to 1 to 8% by weight and 20 to 30% by weight, respectively. Gadolinium oxide (III) (Gd ₂ O ₃ ) acts as a neutron absorbing material that inhibits the nuclear fuel reaction. When a high content of 15% by weight or more is contained, it is difficult to burn nuclear fuel. If less than 1% by weight is included, initial fuel output This increase makes it difficult to control the reactor. The aviation oxide (Er ₂ O ₃ ) also plays a role as a neutron absorbing material that suppresses the nuclear fuel reaction. When a high content of 8% by weight or more is contained, it is difficult to burn nuclear fuel, and when it is less than 0.5% by weight, the initial output of nuclear fuel is increased. Therefore, it becomes difficult to control the reactor.

The additive is a group containing an element that increases the particle size of nuclear fuel, such as uranium oxide by reacting with silicon oxide, preferably Mg, Al, Ca, Bi, Ti, Cr oxide, nitride, sulfide, phosphide, carbide It may be a mixture of one or two or more selected from the group consisting of.

In step (1), the nuclear fuel powder is 99.5 to 99.995 wt%, and the additive may be 0.005 to 0.5 wt%. The reason for limiting the content of the additive is that the additive content specified by ASTM is extremely limited, and when the weight of the additive is less than 0.005% by weight, the size of the grains in the outer region reacts with the silicon element and does not increase more than 15 μm. This is because, at a content exceeding 0.5% by weight, the commercial specification significantly exceeds uranium concentration. More preferably, the nuclear fuel powder is 99.8 to 99.99% by weight, and the additive may be 0.01 to 0.2% by weight.

In the step (3), a silicone polymer containing a silicon element is dissolved in a solvent and applied to the surface of the molded body, and then a precursor containing a silicon element or silicon oxide is disposed around the molded body without or through normal temperature drying and crosslinking. Can be sintered together. As described above, the reason for applying the silicone polymer or disposing the precursor containing the silicon element or silicon oxide around the molded body is that the silicon polymer or the precursor containing the silicon element and the silicon oxide is thermally decomposed or vaporized during the temperature rising process for sintering to form silicon. In the form of a gas containing element or silicon oxide, it penetrates into the molded body to form a liquid phase at an additive and process point, thereby increasing the diffusion rate of uranium oxide to promote sintering and particle size increase of the molded body.

In addition, the grain size of the inner region in which the compound gas containing silicon element or silicon oxide has not penetrated is equal to or slightly larger than 3 to 8 μm, which is the grain size of the uranium oxide due to the doping of the additive element. Less than.

The silicon element may be provided from a chemical reaction between a compound containing at least one material or a silicon element selected from the group consisting of metal silicon, silicon alkoxide, and silicon alkylsilane, and a heterogeneous material.

Specifically, a compound containing a silicon element or a silicon oxide may be provided from a silicone polymer of silicon alkoxide or silicone alkylsilane, and the silicon alkoxide or silicone alkylsilane is polysilioxane, polysilane, polycarbo It may be any one of silane (polycarbosilane), polycarbosiloxane, polysilsesquioxane, tetraethylorthosilicate, and allylhydridopolycarbosilane. In addition, it may be provided by volatilization of a metal silicon material, or one or more chemical reactions among silicon oxide, carbide, nitride, sulfide, and phosphide. It may also be a silicon oxide gas formed by a chemical reaction between a compound containing a silicon element and a heterogeneous material. For example, SiO2 gas may be formed by a chemical reaction between UO ₂ and SiC. The "heterogeneous material" refers to all chemicals capable of generating a silicon oxide gas by reacting with a compound containing a silicon element.

In the step (3), the sintering temperature may be 1400 to 1800 ℃. The molded body is heated in a reducing gas atmosphere at 1400 to 1800 ° C., and then sintered for 0.5 to 6 hours, the grain size in the outer region is 15 μm or more, and the grain size in the inner region is 3 to 15 μm. A nuclear fuel sintered body having a different double grain structure is produced. In a reducing atmosphere below 1400 ° C, uranium oxide is difficult to sinter, and the temperature for sintering the nuclear fuel may be 1730 ° C or higher but 1800 ° C or higher, preferably 1730 ° C, which is a commercial sintering temperature.

The atmosphere during sintering may be argon (Ar), nitrogen (N ₂ ), water vapor (H ₂ O) _, carbon dioxide (CO ₂ ) atmosphere, etc., but a reducing atmosphere such as hydrogen (H ₂ ) or ammonite (NH ₄ ) may be used. It is preferred to create.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as limited by these examples.

Example 1.

Step 1: Dry Reconversion UO ₂ powder (99.95% by weight of KEPCO Magnetic Fuel Co., Ltd.) and 0.05% by weight of AIN powder as additives were mixed to obtain a uniform mixture.

Step 2: The mixture prepared after the mixing process is preformed at a pressure of 1 ton / cm ² , and then the preform is crushed into granules. The granulation process may be any process that does not cause separation between the constituent raw materials, but the process of making granules through a conventional preforming process is most preferable for a subsequent molding process.

Step 3: After mixing the lubricant with the granules, placed in a molding mold having a diameter of 12 mm and molded at a pressure of 3 ton / cm ² .

Step 4: A polysiloxane was dissolved in ethanol to prepare a solution at a concentration of 30%. However, the concentration of the solution is only desirable to perform a subsequent application process, and does not necessarily fix the concentration of the solution. In addition, when the material containing the silicon element is disposed around the molded body and sintered, it is not necessary to go through this step and step 5.

Step 5: The dissolved solution was applied to a molded body using a nebulizer and dried at room temperature. At this time, the content of the polysiloxane applied to the molded body was 700 ppm based on the weight of the molded body. However, the content of the applied polysiloxane is only desirable for performing a subsequent sintering process, but does not necessarily fix the polysiloxane content.

Step 6: The molded body coated with the polysiloxane was cross-linked at 170 ° C. for 2 hours in an atmospheric atmosphere. However, the cross-linking process is preferable to perform a subsequent sintering process, but is not necessarily performed.

Step 7: The crosslinked molded body was heated in a hydrogen gas atmosphere to 1700 ° C. at a heating rate of 240 ° C. per hour, maintained for 2 hours, and then cooled. However, when the compound solution containing silicon element or silicon oxide is not applied, it is preferable to place the compound precursor containing silicon element or silicon oxide around the molded body to sinter.

Example 2.

The same procedure as in Example 1 was carried out, but in step 1, 99.95% by weight of dry-reconverted UO ₂ powder and 0.05% by weight of Al ₂ O ₃ powder as an additive were mixed.

Example 3.

The same procedure as in Example 1 was performed, but in step 1, 99.5% by weight of dry-reconverted UO ₂ powder and 0.5% by weight of Al ₂ O ₃ powder as an additive were mixed.

Example 4.

The same procedure as in Example 1 was carried out, but in step 1, 99.9% by weight of dry-reconverted UO ₂ powder and 0.05% by weight of CaCO ₃ powder as an additive were mixed. In the case of CaO, CaCO ₃ is required because it is decomposed into CaO and CO ₂ in an H ₂ atmosphere. CaCO ₃ was added as much as the content.

Example 5.

The same procedure as in Example 1 was performed, but in step 1, 99.995% by weight of dry-reconverted UO ₂ powder and 0.005% by weight of MgO powder as an additive were mixed.

Example 6.

The same procedure as in Example 1 was carried out, but in step 1, 99.95% by weight of dry-reconverted UO ₂ powder and 0.05% by weight of MgO powder as an additive were mixed.

Example 7.

The same procedure as in Example 1 was carried out, but in step 1, 99.85% by weight of dry-reconverted UO ₂ powder and 0.15% by weight of Bi ₂ O ₃ powder as an additive were mixed.

Comparative Example 1.

The same procedure as in Example 1 was carried out, but in step 1, the dry-reconverted UO ₂ powder was used in the same manner as in Example 1 using only UO ₂ powder without mixing additives.

Comparative Example 2.

The same procedure as in Example 2 was performed, but steps 4 to 6 were not performed.

Hereinafter, the composition ratios of the fuel powders and additives of Examples 1 to 7, Comparative Examples 1 and 2 are summarized in Table 1 below.

division
(weight%)
Dry conversion UO ₂ powder AlN powder Al ₂ O ₃ powder
CaO powder MgO powder
Bi ₂ O ₃ powder Example





One 99.95 0.05 - - - - - - 2 99.95 - 0.05 - - - - - 3 99.5 - - 0.5 - - - - 4 99.9 - - - 1.0 - - - 5 99.995 - - - - 0.005 - - 6 99.85 - - - - - 0.15 - 7 99.85 - - - - - - 0.15 Comparative example
One 100 - - - - - - - 2 99.95 - 0.5 - - - - -

Measurement example 1.

The density of the sintered bodies prepared in Examples 1 to 7, Comparative Examples 1 and 2, the grain size, and the size of the outer region in the center direction from the outer surface were measured. The density of the sintered body is measured by a buoyancy method, and the grain size is measured by a straight line crossing method. Table 2 shows the results.

division
Density (g / cm ³ ) External area grain size (㎛) Internal grain size (㎛) External area size (㎛) Example





One 10.69 23 8 1700 2 10.74 23 8 1650 3 10.72 23 7 3000 4 10.72 20 6 2000 5 10.68 22 6 1000 6 10.71 25 9 1600 7 10.69 21 8 250 Comparative example
One 10.61 6 6 - 2 10.64 9 9 -

As described above, specific parts of the present invention have been described in detail. For those skilled in the art, this specific technique is only a preferred embodiment, and it is obvious that the scope of the present invention is not limited thereby. something to do. Therefore, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

1: Nuclear fuel sintered body 2: External area
3: Internal area

Claims (9)

In the manufacturing method of the nuclear fuel sintered body,
(1) preparing an admixture by mixing an additive with nuclear fuel powder;
(2) compression molding the mixture to produce a molded body; And
(3) sintering in an inert atmosphere in which silicon oxide is present with respect to the molded body,
The step (3) further comprises a reducing gas to perform sintering,
In the step (3), a solution in which silicon oxide is dissolved is applied to the molded body to perform sintering,
Method of manufacturing a nuclear fuel sintered body having a double grain structure, characterized in that the grain size of the outer region of the sintered body is larger than the grain size of the inner region.
According to claim 1,
The nuclear fuel powder is a method for producing a sintered nuclear fuel having a double grain structure, characterized in that the uranium oxide.
According to claim 2,
The nuclear fuel powder further includes plutonium dioxide (PuO ₂ ),
The plutonium dioxide (PuO ₂ ) is a nuclear fuel powder 100% by weight compared to 1 to 30% by weight of the nuclear fuel sintered body manufacturing method having a double grain structure.
According to claim 2,
The nuclear fuel powder further comprises gadolinium oxide (III) (Gd ₂ O ₃ ),
The gadolinium oxide (III) (Gd ₂ O ₃ ) is a nuclear fuel powder 100% by weight compared to 1 to 15% by weight of the nuclear fuel sintered body manufacturing method having a double grain structure.
According to claim 2,
The nuclear fuel powder further comprises aviation oxide (Er ₂ O ₃ ),
The aviation oxide (Er ₂ O ₃ ) is a fuel sintered body having a double crystal structure, characterized in that 0.5 to 8% by weight compared to 100% by weight of the nuclear fuel powder.
According to claim 1,
The additive is Mg, Al, Ca, Bi, Ti oxide, nitride, sulfide, phosphide, a method for producing a nuclear fuel sintered body having a double grain structure, characterized in that at least one material selected from the group consisting of carbides.
According to claim 1,
In the step (1), the nuclear fuel powder is 99.5 to 99.995% by weight, and the additive is 0.005 to 0.5% by weight.
According to claim 1,
In the step (3), the silicon element of silicon oxide is one that is provided from a chemical reaction between a compound containing at least one material or silicon element selected from the group consisting of metal silicon, silicon alkoxide, and silicon alkylsilane, and a heterogeneous material. Method for manufacturing a sintered nuclear fuel having a double crystal grain structure.
According to claim 1,
In step (3) above,
The temperature of the sintering step is 1400 to 1800 ℃ nuclear fuel sintered body manufacturing method having a double grain structure.

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