Preparation method of nuclear fuel uranium-molybdenum alloy

Abstract

The invention particularly relates to a preparation method of a nuclear fuel uranium-molybdenum alloy. The preparation method comprises the following steps: step 1, preparing a uranium-molybdenum alloy blank by adopting an electron beam melting or high-frequency induction melting process; 2, the uranium-molybdenum alloy blank is subjected to homogenizing heat treatment; and 3, the uranium-molybdenum alloy blank is subjected to pressure machining forming, and the nuclear fuel uranium-molybdenum alloy is obtained. By means of the method, sufficient alloying of the uranium-molybdenum alloy is achieved, the content of impurity element carbon and inclusions is controlled, the density of the uranium-molybdenum alloy is improved, the microstructure is refined, meanwhile, the phase reaction, the reaction temperature and the microstructure in the uranium-molybdenum alloy annealing process are defined, and therefore the processing technology of the nuclear fuel uranium-molybdenum alloy is standardized.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear fuel preparation, and in particular to a method for preparing a nuclear fuel uranium-molybdenum alloy. Background Art

[0002] With the continuous progress of society and the continuous development of science and technology, the demand for energy is also increasing. At this stage, with the gradual consumption of non-renewable energy such as coal and oil, nuclear energy, as a clean and efficient form of energy, has always been a hot spot for research and application in various countries. The development of the nuclear industry can provide a reliable and large-scale power supply. Nuclear power plants can stably generate a large amount of electricity to provide security for the country's energy needs, reduce dependence on traditional fossil fuels, and reduce greenhouse gas emissions. Among many nuclear fuels, uranium-molybdenum alloy fuel has the advantages of high uranium density, high phase structure stability, excellent irradiation performance and simple processing. It is an important development direction for space heat pipe reactor fuel and low-enriched uranium fuel for research reactors.

[0003] At present, the preparation process of uranium-molybdenum alloy fuel is graphite tongs induction melting and casting, followed by direct mechanical processing. This preparation process has problems such as difficulty in alloying, high content of impurity element carbon and inclusions, coarse cast structure of the alloy, low density, and composition and structure segregation. In addition, in the preparation process of uranium-molybdenum alloy fuel, there is no detailed record of the phase change process of uranium-molybdenum alloy, the temperature at which the phase change reaction occurs, and the structure after the reaction, making it impossible to effectively regulate the specific process during the processing, which in turn leads to significant limitations on the performance of the produced uranium-molybdenum alloy products. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a nuclear fuel uranium-molybdenum alloy, achieve full alloying of the uranium-molybdenum alloy, control the content of impurity element carbon and inclusions, improve the density of the uranium-molybdenum alloy, refine the microstructure, and at the same time clarify the phase reaction, reaction temperature and structure during the annealing process of the uranium-molybdenum alloy, so as to standardize the processing technology of the nuclear fuel uranium-molybdenum alloy.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing a nuclear fuel uranium-molybdenum alloy comprises the following steps:

[0007] Step 1, preparing uranium-molybdenum alloy billet by electron beam melting or high-frequency induction melting process;

[0008] Step 2, performing homogenization heat treatment on the uranium-molybdenum alloy blank;

[0009] Step 3: pressure-processing the uranium-molybdenum alloy billet to obtain a nuclear fuel uranium-molybdenum alloy.

[0010] As one of the feasible methods, step 1, preparing uranium-molybdenum alloy billet by high-frequency induction melting process, comprises the following steps:

[0011] Step 111, adding a raw material consisting of metallic uranium and metallic molybdenum into a water-cooled tongs pot, wherein the content of metallic molybdenum in the raw material accounts for (8-12.5) wt%;

[0012] Step 112, placing the water-cooled tongs pot into a high-frequency induction melting furnace, evacuating the furnace, gradually heating to (2300-2800)°C, keeping the temperature for 30 minutes, and then cooling with the furnace; repeating this process (1-2) times to achieve the melting of the raw materials and obtain the melted ingot;

[0013] Step 113, take out the smelted ingot and put it into a graphite tongs induction furnace, heat it to (1400-1500)°C, keep it warm for (30-50) minutes and stir it continuously, then cast it into an ingot by bottom casting and cool it to obtain a uranium-molybdenum alloy billet.

[0014] As one achievable manner, in step 111, the metallic uranium is a uranium sheet, and the metallic molybdenum is a molybdenum granule.

[0015] As one of the achievable methods, step 1, preparing a uranium-molybdenum alloy billet by electron beam melting process, comprises the following steps:

[0016] Step 121, using an electrode composed of metallic uranium and metallic molybdenum as a raw material, wherein the content of metallic molybdenum in the raw material accounts for (8-12.5) wt%;

[0017] Step 122, placing the raw material into an electron beam melting furnace, evacuating the furnace, bombarding the raw material and the bottom ingot with an electron beam, causing the bottom ingot to melt to form a molten pool, and the raw material is continuously melted and falls into the molten pool; repeating this process (1 to 2) times to achieve smelting of the raw material and obtain a smelted ingot;

[0018] Step 123, take out the smelted ingot and put it into a graphite tongs induction furnace, heat it to (1400-1500)°C, keep it warm for (30-50) minutes and stir it continuously, then cast it into an ingot by bottom casting and cool it to obtain a uranium-molybdenum alloy billet.

[0019] As one achievable manner, in step 121, the metal uranium is a uranium rod, and the metal molybdenum is a molybdenum wire.

[0020] As one possible implementation method, step 2, homogenization heat treatment of the uranium-molybdenum alloy billet, comprises the following steps:

[0021] Step 21: Place the uranium-molybdenum alloy billet into a heat treatment furnace, heat it to 1000° C., keep it warm for (5-6) hours, and then anneal it.

[0022] As one of the feasible ways, in step 2, the phase change reaction during the annealing process of the uranium-molybdenum alloy billet is:

[0023] Step 22, as the temperature of the uranium-molybdenum alloy billet decreases, the phase transformation reaction of uranium is: the γ phase precipitates the γo phase; the precipitated γo phase nucleates and grows along the grain boundary of the γ parent phase, with a content of 30wt%, and presents an equiaxed crystal morphology;

[0024] Step 23: As the temperature of the uranium-molybdenum alloy billet continues to drop, the phase transformation reaction of uranium is: the remaining γ phase eutectoidally decomposes into γ" phase and γ o phase, γ" phase content 20wt%, forming a granular eutectoid structure, that is, (γ" phase + γ o Mutually) E ;

[0025] Step 24: As the temperature of the uranium-molybdenum alloy billet continues to drop, the phase change reaction of uranium is: γ o The phase dissolves and precipitates along the grain boundaries and inside the grains to form the γ"II phase.

[0026] As one achievable method, in step 21, the uranium-molybdenum alloy billet is structured as γ-phase uranium;

[0027] In step 22, the temperature at which the phase change reaction occurs is (515-580)°C, and the structure of the uranium-molybdenum alloy billet after the phase change reaction is γ-phase uranium + γ-phase o Phase uranium;

[0028] In step 23, the temperature of the phase change reaction is 515°C, and the microstructure of the uranium-molybdenum alloy billet after the phase change reaction is γ o phase uranium + (γ" phase uranium + γ o Phase uranium) E ;

[0029] In step 24, the temperature at which the phase change reaction occurs is below 515°C, and the microstructure of the uranium-molybdenum alloy billet after the phase change reaction is γ o Phase uranium + (γ o γ-phase uranium +γ-phase uranium) E ;

[0030] As one of the achievable methods, step 3, pressure processing of the uranium-molybdenum alloy billet to obtain the nuclear fuel uranium-molybdenum alloy, comprises the following steps:

[0031] Step 31, forming the uranium-molybdenum alloy blank by pressure processing at 850° C. to obtain a formed uranium-molybdenum alloy blank;

[0032] Step 32: directly process the formed uranium-molybdenum alloy billet into a nuclear fuel uranium-molybdenum alloy; or anneal the billet at (500-620)°C for (4-6) hours and then process the billet into a nuclear fuel uranium-molybdenum alloy.

[0033] As one achievable method, in step 31 , the pressure forming method is extrusion or forging.

[0034] As one of the feasible ways, in step 32, the formed uranium-molybdenum alloy billet is placed in a heat treatment furnace, heated to (500-620)°C at a rate of 10°C / min, kept warm for (4-6) hours, and then cooled with the furnace; the formed uranium-molybdenum alloy billet is taken out for cooling, finishing and size processing to obtain a nuclear fuel uranium-molybdenum alloy.

[0035] As another feasible manner, in step 32, the formed uranium-molybdenum alloy billet is cooled, finished and dimensionally processed to obtain a nuclear fuel uranium-molybdenum alloy.

[0036] Beneficial technical effects of the present invention:

[0037] The preparation method of the nuclear fuel uranium-molybdenum alloy of the present invention adopts electron beam melting or high-frequency induction melting process to achieve full alloying of the uranium-molybdenum alloy, and the content of impurity element carbon and inclusions is effectively controlled; through homogenization heat treatment and pressure processing, the density of the uranium-molybdenum alloy ingot is improved, and the microstructure is further refined; at the same time, the phase reaction process and the temperature at which the phase reaction occurs in each temperature range of the uranium-molybdenum alloy with a molybdenum content of (8-12.5)% are clarified, and the structure of the uranium-molybdenum alloy in each temperature range is determined, so that the processing technology of the nuclear fuel uranium-molybdenum alloy is clearer and more specific, and the structure in the corresponding temperature range can be selected according to performance requirements, and the corresponding processing technology can be designed according to corresponding conditions, so that the preparation technology of the nuclear fuel uranium-molybdenum alloy is accurately guided and participated. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the metallographic structure of cast uranium-10% molybdenum alloy.

[0039] Figure 2 Schematic diagram of the metallographic structure of the uranium-10% molybdenum alloy after pressure processing. DETAILED DESCRIPTION

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0041] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0042] The present invention provides a method for preparing a nuclear fuel uranium-molybdenum alloy, comprising the following steps:

[0043] Step 1, preparing uranium-molybdenum alloy billet by electron beam melting or high-frequency induction melting process;

[0044] Step 2, performing homogenization heat treatment on the uranium-molybdenum alloy blank;

[0045] Step 3: pressure-processing the uranium-molybdenum alloy billet to obtain a nuclear fuel uranium-molybdenum alloy.

[0046] In the present invention, as one of the achievable methods, step 1, using a high-frequency induction melting process to prepare a uranium-molybdenum alloy billet, comprises the following steps:

[0047] Step 111, adding a raw material consisting of metallic uranium and metallic molybdenum into a water-cooled tongs pot, wherein the content of metallic molybdenum in the raw material accounts for (8-12.5) wt%;

[0048] Step 112, placing the water-cooled tongs pot into a high-frequency induction melting furnace, evacuating the furnace, gradually heating to (2300-2800)°C, keeping the temperature for 30 minutes, and then cooling with the furnace; repeating this process (1-2) times to achieve the melting of the raw materials and obtain the melted ingot;

[0049] Step 113, take out the smelted ingot and put it into a graphite tongs induction furnace, heat it to (1400-1500)°C, keep it warm for (30-50) minutes and stir it continuously, then cast it into an ingot by bottom casting and cool it to obtain a uranium-molybdenum alloy billet.

[0050] In the present invention, as one of the achievable methods, in step 111, the metal uranium is a uranium sheet, and the metal molybdenum is a molybdenum granule.

[0051] In the present invention, as one of the achievable methods, step 1, preparing a uranium-molybdenum alloy billet by an electron beam melting process, comprises the following steps:

[0052] Step 121, using an electrode composed of metallic uranium and metallic molybdenum as a raw material, wherein the content of metallic molybdenum in the raw material accounts for (8-12.5) wt%;

[0053] Step 122, placing the raw material into an electron beam melting furnace, evacuating the furnace, bombarding the raw material and the bottom ingot with an electron beam, causing the bottom ingot to melt to form a molten pool, and the raw material is continuously melted and falls into the molten pool; repeating this process (1 to 2) times to achieve smelting of the raw material and obtain a smelted ingot;

[0054] Step 123, take out the smelted ingot and put it into a graphite tongs induction furnace, heat it to (1400-1500)°C, keep it warm for (30-50) minutes and stir it continuously, then cast it into an ingot by bottom casting and cool it to obtain a uranium-molybdenum alloy billet.

[0055] In the present invention, as one achievable method, in step 121, the metal uranium is a uranium rod, and the metal molybdenum is a molybdenum wire.

[0056] In the present invention, as one of the achievable methods, step 2, homogenizing heat treatment of the uranium-molybdenum alloy billet, comprises the following steps:

[0057] Step 21: Place the uranium-molybdenum alloy billet into a heat treatment furnace, heat it to 1000° C., keep it warm for (5-6) hours, and then anneal it.

[0058] In the present invention, as one achievable method, in step 2, annealing the uranium-molybdenum alloy billet comprises the following steps:

[0059] Step 22, as the temperature of the uranium-molybdenum alloy billet decreases, the phase transformation reaction of uranium is: the γ phase precipitates the γo phase; the precipitated γo phase nucleates and grows along the grain boundary of the γ parent phase, with a content of 30wt%, and presents an equiaxed crystal morphology;

[0060] Step 23: As the temperature of the uranium-molybdenum alloy billet continues to drop, the phase transformation reaction of uranium is: the remaining γ phase eutectoidally decomposes into γ" phase and γ o phase, γ" phase content 20wt%, forming a granular eutectoid structure, that is, (γ" phase + γ o Mutually) E ;

[0061] Step 24: As the temperature of the uranium-molybdenum alloy billet continues to drop, the phase change reaction of uranium is: γ o The phase dissolves and precipitates along the grain boundaries and inside the grains to form the γ"II phase.

[0062] In the present invention, as one of the achievable methods, in step 21, the uranium-molybdenum alloy billet is structured as γ-phase uranium;

[0063] In step 22, the temperature at which the phase change reaction occurs is (515-580)°C, and the structure of the uranium-molybdenum alloy billet after the phase change reaction is γ-phase uranium + γ-phase o Phase uranium;

[0064] In step 23, the temperature of the phase change reaction is 515°C, and the microstructure of the uranium-molybdenum alloy billet after the phase change reaction is γ o phase uranium + (γ" phase uranium + γ o Phase uranium) E ;

[0065] In step 24, the temperature at which the phase change reaction occurs is below 515°C, and the microstructure of the uranium-molybdenum alloy billet after the phase change reaction is γ o Phase uranium + (γ o γ-phase uranium +γ-phase uranium) E ;

[0066] In the present invention, as one of the achievable methods, step 3, pressure processing of the uranium-molybdenum alloy billet to obtain the nuclear fuel uranium-molybdenum alloy, comprises the following steps:

[0067] Step 31, forming the uranium-molybdenum alloy blank by pressure processing at 850° C. to obtain a formed uranium-molybdenum alloy blank;

[0068] Step 32: directly process the formed uranium-molybdenum alloy billet into a nuclear fuel uranium-molybdenum alloy; or anneal the billet at (500-620)°C for (4-6) hours and then process the billet into a nuclear fuel uranium-molybdenum alloy.

[0069] In the present invention, as one of the feasible ways, in step 31, the pressure forming method is extrusion or forging.

[0070] In the present invention, as one of the feasible ways, in step 32, the formed uranium-molybdenum alloy billet is placed in a heat treatment furnace, heated to (500-620)°C at a rate of 10°C / min, kept warm for (4-6) hours, and then cooled with the furnace; the formed uranium-molybdenum alloy billet is taken out for cooling, finishing and size processing to obtain a nuclear fuel uranium-molybdenum alloy.

[0071] In the present invention, as another achievable method, in step 32, the formed uranium-molybdenum alloy billet is cooled, finished and dimensionally processed to obtain a nuclear fuel uranium-molybdenum alloy.

[0072] See also Figure 1 and 2 The average grain size of the cast sample is about 100μm, and the average grain size of the sample after pressure processing is about 30μm. Pressure processing has a significant effect on grain refinement.

[0073] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings and specific embodiments.

[0074] Example 1

[0075] This embodiment provides a method for preparing a nuclear fuel uranium-molybdenum alloy, comprising the following steps:

[0076] Step 1, using an electrode composed of 90wt% uranium rod and 10wt% molybdenum wire as a raw material;

[0077] Step 2, the raw materials are placed in an electron beam melting furnace, and after vacuuming, the electron beam is used to bombard the raw materials and the bottom ingot, so that the bottom ingot is melted to form a molten pool, and the raw materials are continuously melted and fall into the molten pool, thereby realizing the smelting of the raw materials; this process is repeated twice to obtain the smelted ingot;

[0078] Step 3, taking out the smelted ingot and placing it in a graphite tongs pot induction furnace, heating it to 1450° C., keeping it warm for 30 minutes with continuous stirring, then casting it into an ingot by bottom casting and cooling it to obtain a uranium-molybdenum alloy billet;

[0079] Step 4: Place the uranium-molybdenum alloy billet into a heat treatment furnace, heat to 1000° C., keep warm for 5 hours, and then anneal;

[0080] Step 5, forming the uranium-molybdenum alloy blank by pressure processing at 850° C. to obtain a formed uranium-molybdenum alloy blank;

[0081] Step 6: Cool, finish and size-process the formed uranium-molybdenum alloy billet to obtain a nuclear fuel uranium-molybdenum alloy.

[0082] The nuclear fuel uranium-molybdenum alloy prepared in Example 1 was tested, and the impurity element carbon content was 476 μg / g, which was lower than 1000 μg / g of the existing process; the inclusion content was less than 1.3%, which was lower than 2% of the existing process; the density was 97.1%, which was better than 98% of the existing process; the average grain size was 29 μm, which was less than 100 μm of the existing process.

[0083] Example 2

[0084] This embodiment provides a method for preparing a nuclear fuel uranium-molybdenum alloy, comprising the following steps:

[0085] Step 1, adding a raw material consisting of 90wt% uranium flakes and 10wt% molybdenum particles into a water-cooled tongs pot;

[0086] Step 2, place the water-cooled tongs pot into a high-frequency induction melting furnace, evacuate, gradually heat to (2300-2400)°C, keep warm for 30 minutes and then cool with the furnace; repeat this process twice to melt the raw materials and obtain the smelted ingot;

[0087] Step 3, taking out the smelted ingot and placing it in a graphite tongs pot induction furnace, heating it to 1500° C., keeping it warm for (30 to 50) minutes and stirring it continuously, then casting it into an ingot by bottom casting and cooling it to obtain a uranium-molybdenum alloy billet;

[0088] Step 4: Place the uranium-molybdenum alloy billet into a heat treatment furnace, heat to 1000° C., keep warm for 6 hours, and then anneal;

[0089] Step 5, forming the uranium-molybdenum alloy blank by pressure processing at 850° C. to obtain a formed uranium-molybdenum alloy blank;

[0090] Step 6: Place the formed uranium-molybdenum alloy billet into a heat treatment furnace, heat it to 610°C at a rate of 10°C / min, keep it warm for 4 hours, and then cool it with the furnace; take out the formed uranium-molybdenum alloy billet for cooling, finishing and size processing to obtain a nuclear fuel uranium-molybdenum alloy.

[0091] The nuclear fuel uranium-molybdenum alloy prepared in Example 2 was tested, and the impurity element carbon content was 426 μg / g, which was lower than 1000 μg / g of the existing process; the inclusion content was less than 1.1%, which was lower than 2% of the existing process; the density was 97.3%, which was better than 98% of the existing process; the average grain size was 37 μm, which was less than 100 μm of the existing process.

[0092] Example 3

[0093] This embodiment provides a method for preparing a nuclear fuel uranium-molybdenum alloy, comprising the following steps:

[0094] Step 1, adding a raw material consisting of 92wt% uranium flakes and 8wt% molybdenum particles into a water-cooled tongs pot;

[0095] Step 2, place the water-cooled tongs pot into a high-frequency induction melting furnace, evacuate, gradually heat to (2300-2400)°C, keep warm for 30 minutes and then cool with the furnace; repeat this process once to obtain a smelted ingot;

[0096] Step 3, taking out the smelted ingot and placing it in a graphite tongs pot induction furnace, heating it to 1500° C., casting it into an ingot by bottom casting and cooling it to obtain a uranium-molybdenum alloy billet;

[0097] Step 4: Place the uranium-molybdenum alloy billet into a heat treatment furnace, heat to 1000° C., keep warm for 5 hours, and then anneal;

[0098] Step 5, forming the uranium-molybdenum alloy blank by pressure processing at 850° C. to obtain a formed uranium-molybdenum alloy blank;

[0099] Step 6: Place the formed uranium-molybdenum alloy billet into a heat treatment furnace, heat it to 520°C at a rate of 10°C / min, keep it warm for 6 hours, and then cool it with the furnace; take out the formed uranium-molybdenum alloy billet for cooling, finishing and size processing to obtain a nuclear fuel uranium-molybdenum alloy.

[0100] The nuclear fuel uranium-molybdenum alloy prepared in Example 3 was tested, and the impurity element carbon content was 389 μg / g, which was lower than 1000 μg / g of the existing process; the inclusion content was less than 1.0%, which was lower than 2% of the existing process; the density was 97.5%, which was better than 98% of the existing process; the average grain size was 32 μm, which was less than 100 μm of the existing process.

[0101] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a nuclear fuel uranium-molybdenum alloy, characterized in that: The steps include: Step 1, preparing uranium-molybdenum alloy billet by electron beam melting or high-frequency induction melting process; Step 2, performing homogenization heat treatment on the uranium-molybdenum alloy blank; Step 3: pressure-processing the uranium-molybdenum alloy billet to obtain a nuclear fuel uranium-molybdenum alloy.

2. The method for preparing the nuclear fuel uranium-molybdenum alloy according to claim 1, characterized in that: Step 1, preparing a uranium-molybdenum alloy billet by a high-frequency induction melting process, comprises the following steps: Step 111, adding a raw material consisting of metallic uranium and metallic molybdenum into a water-cooled tongs pot, wherein the content of metallic molybdenum in the raw material accounts for (8-12.5) wt%; Step 112, placing the water-cooled tongs pot into a high-frequency induction melting furnace, evacuating the furnace, gradually heating to (2300-2800)°C, keeping the temperature for 30 minutes, and then cooling with the furnace; repeating this process (1-2) times to achieve the melting of the raw materials and obtain the melted ingot; Step 113, take out the smelted ingot and put it into a graphite tongs induction furnace, heat it to (1400-1500)°C, keep it warm for (30-50) minutes and stir it continuously, then cast it into an ingot by bottom casting and cool it to obtain a uranium-molybdenum alloy billet.

3. The method for preparing the nuclear fuel uranium-molybdenum alloy according to claim 2, characterized in that: In step 111, the metallic uranium is a uranium flake, and the metallic molybdenum is a molybdenum granule.

4. The method for preparing the nuclear fuel uranium-molybdenum alloy according to claim 1, characterized in that: Step 1, preparing a uranium-molybdenum alloy billet by electron beam melting process, comprising the following steps: Step 121, using an electrode composed of metallic uranium and metallic molybdenum as a raw material, wherein the content of metallic molybdenum in the raw material accounts for (8-12.5) wt%; Step 122, placing the raw material into an electron beam melting furnace, evacuating the furnace, bombarding the raw material and the bottom ingot with an electron beam, causing the bottom ingot to melt to form a molten pool, and the raw material is continuously melted and falls into the molten pool; repeating this process (1 to 2) times to achieve smelting of the raw material and obtain a smelted ingot; Step 123, take out the smelted ingot and put it into a graphite tongs induction furnace, heat it to (1400-1500)°C, keep it warm for (30-50) minutes and stir it continuously, then cast it into an ingot by bottom casting and cool it to obtain a uranium-molybdenum alloy billet.

5. The method for preparing the nuclear fuel uranium-molybdenum alloy according to claim 4, characterized in that: In step 121, the metal uranium is a uranium rod, and the metal molybdenum is a molybdenum wire.

6. The method for preparing the nuclear fuel uranium-molybdenum alloy according to claim 1, characterized in that: Step 2, homogenizing heat treatment of the uranium-molybdenum alloy blank, comprises the following steps: Step 21: Place the uranium-molybdenum alloy billet into a heat treatment furnace, heat it to 1000° C., keep it warm for (5-6) hours, and then anneal it.

7. The method for preparing the nuclear fuel uranium-molybdenum alloy according to claim 6, characterized in that: In step 2, the phase change reaction during the annealing process of the uranium-molybdenum alloy billet is: Step 22, as the temperature of the uranium-molybdenum alloy billet decreases, the phase transformation reaction of uranium is: the γ phase precipitates the γo phase; the precipitated γo phase nucleates and grows along the grain boundary of the γ parent phase, with a content of 30wt%, and presents an equiaxed crystal morphology; Step 23: As the temperature of the uranium-molybdenum alloy billet continues to drop, the phase transformation reaction of uranium is: the remaining γ phase eutectoidally decomposes into γ" phase and γ o phase, γ" phase content 20wt%, forming a granular eutectoid structure, that is, (γ" phase + γ o Mutually) E ; Step 24: As the temperature of the uranium-molybdenum alloy billet continues to drop, the phase change reaction of uranium is: γ o The phase dissolves and precipitates along the grain boundaries and inside the grains to form the γ"II phase.

8. The method for preparing the nuclear fuel uranium-molybdenum alloy according to claim 7, characterized in that: In step 21, the uranium-molybdenum alloy billet is structured into γ-phase uranium; In step 22, the temperature at which the phase change reaction occurs is (515-580)°C, and the structure of the uranium-molybdenum alloy billet after the phase change reaction is γ-phase uranium + γ-phase o Phase uranium; In step 23, the temperature of the phase change reaction is 515°C, and the microstructure of the uranium-molybdenum alloy billet after the phase change reaction is γ o phase uranium + (γ" phase uranium + γ o Phase uranium) E ; In step 24, the temperature at which the phase change reaction occurs is below 515°C, and the microstructure of the uranium-molybdenum alloy billet after the phase change reaction is γ o Phase uranium + (γ o γ-phase uranium +γ-phase uranium) E。 9. The method for preparing the nuclear fuel uranium-molybdenum alloy according to claim 1, characterized in that: Step 3, pressure processing the uranium-molybdenum alloy billet to obtain a nuclear fuel uranium-molybdenum alloy, comprises the following steps: Step 31, forming the uranium-molybdenum alloy blank by pressure processing at 850° C. to obtain a formed uranium-molybdenum alloy blank; Step 32: directly process the formed uranium-molybdenum alloy billet into a nuclear fuel uranium-molybdenum alloy; or anneal the billet at (500-620)°C for (4-6) hours and then process the billet into a nuclear fuel uranium-molybdenum alloy.

10. The method for preparing the nuclear fuel uranium-molybdenum alloy according to claim 1, characterized in that: In step 31, the pressure forming method is extrusion or forging; in step 32, the formed uranium-molybdenum alloy billet is cooled, finished and dimensionally processed to obtain a nuclear fuel uranium-molybdenum alloy.

Images