A device and method for controlling macroscopic homogeneity of a U-pu-zr metal fuel solidification process

Abstract

A device and method for controlling macroscopic uniformity of U-Pu-Zr metal fuel solidification process, comprising a gravity casting furnace and an injection casting furnace; the gravity casting furnace comprises a graphite crucible, a bottom ingot mold, a graphite crucible cover installed on the upper part of the graphite crucible, a pouring plate installed through a guide sleeve on the lower part, a bottom ingot mold connected to the lower part of the pouring plate, and a bottom cover installed on the lower part of the bottom ingot mold; the injection casting furnace comprises an injection casting furnace crucible and a quartz mold, and the injection casting furnace crucible is provided with a thermocouple insertion groove at the bottom; the quartz mold is installed on a mold support, and the quartz mold is provided with an argon blowing hole; the control method comprises raw material preparation, alloy smelting, core smelting and core detection; the invention introduces a process of preparing a master alloy first, and prepares a U-Pu-Zr ternary alloy ingot under vacuum conditions by using the electromagnetic stirring function of induction heating; the argon blowing method is used to further accelerate the cooling rate of the core during the core forming and cooling process, and the obtained metal fuel rod has high macroscopic composition uniformity.

Description

Technical Field

[0001] This invention relates to the field of metal fuel preparation technology, specifically to an apparatus and method for controlling the macroscopic uniformity of the solidification process of U-Pu-Zr metal fuel. Background Technology

[0002] Metallic fuels generally refer to alloys composed of U, Zr, or U, Pu, Zr, etc., with specific dimensional and technical specifications. Metallic fuels have advantages such as high nuclear density, high multiplication ratio, high thermal conductivity, and low fissile nuclide loading. By considering them in conjunction with dry reprocessing methods such as electrolytic refining, the reprocessing process can be greatly simplified, improving the safety and economy of the closed nuclear fuel cycle.

[0003] Metallic fuels can be manufactured using various methods, including injection casting, centrifugal casting, continuous casting, gravity casting, atomization, and extrusion. For large-scale production, the process should be cost-effective and minimize radioactive waste. However, the densities of U, Pu, and Zr in metallic fuels differ significantly, and the composition distribution during core casting is influenced by flow and temperature fields. Furthermore, one-time solidification processes often fail to meet the requirements for macroscopic uniformity of elements within the fuel.

[0004] Compared to the commonly used direct one-step injection casting process for preparing metallic fuels, adding a master alloy preparation step can effectively improve and control the macroscopic uniformity of the metallic fuel. The master alloy can be prepared using conventional gravity casting methods, that is, by first melting three metals in a vacuum melting furnace and casting them into a master alloy ingot, and then using injection casting to further improve and control the macroscopic uniformity of the metallic fuel. See the attached process flow diagram for details. Figure 1 . Summary of the Invention

[0005] The purpose of this invention is to provide a method for controlling the macroscopic uniformity of U-Pu-Zr metal fuel solidification process, thereby solving the problem of difficulty in controlling the macroscopic uniformity of metal fuel.

[0006] The technical solution of the present invention is as follows: a device for controlling the macroscopic uniformity of the solidification process of U-Pu-Zr metal fuel, comprising a gravity casting furnace and an injection casting furnace;

[0007] The gravity casting furnace includes a graphite crucible and a bottom ingot mold. A graphite crucible cover is installed on the upper part of the graphite crucible, and a pouring plate is installed on the lower part through a guide sleeve. The lower part of the pouring plate is connected to the bottom ingot mold, and a bottom cover is installed on the lower part of the bottom ingot mold. The pouring plate has a protrusion, and the bottom of the graphite crucible has a hole, and the protrusion matches the bottom hole of the graphite crucible. A graphite crucible thermocouple is installed in the graphite crucible, and a bottom ingot mold thermocouple is installed in the bottom ingot mold.

[0008] The injection casting furnace includes an injection casting furnace crucible and a quartz mold. The bottom of the injection casting furnace crucible has a thermocouple insertion groove. The quartz mold is mounted on a quartz mold support and has argon gas blowing holes.

[0009] The crucible of the injection casting furnace has a crucible gripping groove.

[0010] The graphite crucible contains Zr granules, Pu ingots, and U ingots; the injection casting furnace crucible contains molten alloy.

[0011] It also includes a vacuum system for evacuating the gravity casting furnace and the injection casting furnace.

[0012] It also includes an induction heating system.

[0013] A method for controlling the macroscopic uniformity of the solidification process of U-Pu-Zr metallic fuels includes the following steps:

[0014] Step 1: Raw material preparation; using metal U rods and Zr particles as raw materials for preparing U-Zr fuel cores, and using metal U rods, Zr particles and Pu metal ingots as raw materials for preparing U-Pu-Zr cores;

[0015] Step 2: Alloy smelting;

[0016] Step 3: Core melting;

[0017] Step 4: Core testing.

[0018] Step 1 includes:

[0019] Step 1.1: The metal U rod is surface treated using a lathe, and the amount of metal U is determined according to the metal fuel ratio to form metal U ingot 11;

[0020] Step 1.2: Weigh the Zr metal particles according to the metal fuel ratio, and use solvents such as acetone and anhydrous ethanol to clean the contaminants on the metal surface to form Zr metal particles;

[0021] Step 1.3: Cut out an appropriate weight of Pu metal according to the metal fuel ratio to form metallic Pu.

[0022] Step 1.4: Assemble the bottom ingot mold with the graphite crucible, place the Zr granules at the bottom of the graphite crucible, place the Pu granules on top of the Zr granules, and place the U ingots on the top layer, then load the furnace.

[0023] The metal fuel composition is 10% Zr, 1%–20% Pu, and 70%–89% U.

[0024] Step 2 includes:

[0025] Step 2.1: Start the vacuum system and evacuate the gravity casting furnace;

[0026] Step 2.2: Start the induction heating system to heat the graphite crucible and the bottom ingot mold;

[0027] Step 2.3: After the graphite crucible reaches the set temperature, it is kept at that temperature to allow all the metal inside the graphite crucible to melt and form a preliminary alloy liquid. Then, the bottom ingot mold is separated from the graphite crucible, allowing the molten preliminary alloy liquid to flow from the bottom hole of the graphite crucible into the casting tray, and then into the bottom ingot mold through the hole at the bottom of the casting tray.

[0028] Step 2.4: After the gravity casting furnace is cooled to below 40°C, the mold is removed and the U-Pu-Zr master alloy is obtained after demolding.

[0029] Step 3 includes:

[0030] Step 3.1: The U-Pu-Zr master alloy obtained in Step 2 is surface treated, divided, and placed into the injection casting furnace crucible 13;

[0031] Step 3.2: Start the vacuum system to evacuate the injection casting furnace;

[0032] Step 3.3: Set the heating temperature of the injection casting furnace crucible to 1300-1550℃, the preheating temperature of the quartz mold to 600-1000℃, insert the thermocouple into the thermocouple insertion slot 14, and the U-Pu-Zr master alloy obtained in step 3 forms alloy liquid 19 in the injection casting furnace crucible 13.

[0033] Step 3.4: After the quartz mold reaches the set temperature, it is kept at that temperature. Then, the quartz mold 18 is lowered and inserted into the molten alloy in the crucible of the injection casting furnace. A pressure difference is formed between the surface of the molten alloy and the inside of the quartz mold, so that the molten alloy is injected into the quartz mold.

[0034] Step 3.5: The alloy liquid solidifies into a solid in the quartz mold, and during the cooling process, air is blown into the quartz mold through the air blowing hole to accelerate the cooling.

[0035] Step 3.6: After the injection casting furnace is cooled to below 40°C, the quartz mold is broken to obtain the U-Pu-Zr core.

[0036] Step 4 includes: taking chips from the upper, middle and lower parts of the U-Pu-Zr core obtained in step 3. If the difference in U, Pu and Zr content between the upper, middle and lower parts of the U-Pu-Zr core is less than ±1wt%, it indicates that it is qualified.

[0037] The significant advantages of this invention are as follows: The method for controlling the macroscopic uniformity of U-Pu-Zr metal fuel, considering the large differences in the proportions of the three metal components and the significant density deviations of the three metals in U-Pu-Zr metal fuel, introduces a step of first preparing a master alloy. Under vacuum conditions, the electromagnetic stirring function of induction heating is used to prepare U-Pu-Zr ternary alloy ingots, enabling interdiffusion between the high-density uranium-plutonium alloy and the low-melting-point zirconium metal, thus initially improving the uniformity of the alloy. At the same time, during the core forming and cooling process, argon gas blowing is used to further accelerate the core cooling rate, effectively suppressing the gravity sedimentation effect of the high-density U / Pu phase during solidification and the grain boundary segregation phenomenon of Zr element. The final obtained metal fuel rod has a macroscopic composition uniformity deviation of less than 1 wt%, providing a method for controlling the macroscopic uniformity of various metal elements in metal fuel. Attached Figure Description

[0038] Figure 1 Process route diagram of this invention;

[0039] Figure 2 Schematic diagram of gravity casting;

[0040] Figure 3 Schematic diagram of injection casting;

[0041] In the figure: 1—graphite crucible lid, 2—graphite crucible; 3—guide sleeve, 4—pouring tray, 5—bottom ingot mold, 6—bottom cover, 7—graphite crucible thermocouple, 8—bottom ingot mold thermocouple, 9—metallic Zr granules, 10—metallic Pu, 11—metallic U ingot.

[0042] 12—U-Pu-Zr core; 13—Injection casting furnace crucible; 14—Thermocouple insertion slot; 15—Crucible gripping slot; 16—Argon blowing hole; 17—Quartz mold support; 18—Quartz mold; 19—Molten alloy; 20—Protrusion. Detailed Implementation

[0043] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below.

[0044] The terminology used in one or more embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of one or more embodiments of this application. The singular forms “a,” “the,” and “the” used in one or more embodiments of this application and in the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” used in one or more embodiments of this application refers to and includes any or all possible combinations of one or more associated listed items.

[0045] It should be understood that although the terms first, second, etc., may be used to describe various information in one or more embodiments of this application, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first may also be referred to as second without departing from the scope of one or more embodiments of this application, and similarly, second may also be referred to as first.

[0046] A device for controlling the macroscopic uniformity of the solidification process of U-Pu-Zr metallic fuel includes a gravity casting furnace and an injection casting furnace.

[0047] The gravity casting furnace includes a graphite crucible 2 and a bottom ingot mold 5. A graphite crucible cover 1 is installed on the upper part of the graphite crucible 2, and a pouring plate 4 is installed on the lower part through a guide sleeve 3. The bottom ingot mold 5 is connected to the lower part of the pouring plate 4, and a bottom cover 6 is installed on the lower part of the bottom ingot mold 5.

[0048] The casting plate 4 has a protrusion 20, and the bottom of the graphite crucible 2 has a hole. The protrusion 20 matches the bottom hole of the graphite crucible 2, so that the molten metal in the graphite crucible 2 will not flow out. When the protrusion 20 separates from the bottom hole of the graphite crucible 2, the molten metal in the graphite crucible 2 flows into the casting plate 4 under the action of gravity. The bottom of the casting plate 4 also has a hole, and the molten metal flows into the bottom ingot mold 5 through the hole at the bottom of the casting plate 4.

[0049] The graphite crucible 2 is equipped with a graphite crucible thermocouple 7, and the bottom ingot mold 5 is equipped with a bottom ingot mold thermocouple 8.

[0050] The graphite crucible 2 contains Zr particles 9, Pu 10, and U ingots 11.

[0051] The injection casting furnace includes an injection casting furnace crucible 13 and a quartz mold 18. The bottom of the injection casting furnace crucible 13 has a thermocouple insertion groove 14 for installing a thermocouple. The injection casting furnace crucible 13 has a crucible gripping groove 15 for automatically gripping the injection casting furnace crucible 13. The inside of the injection casting furnace crucible 13 contains alloy liquid 19.

[0052] The quartz mold 18 is mounted on the quartz mold support 17, and the quartz mold 18 has an argon gas blowing hole 16. The prepared U-Pu-Zr core 12 is located in the quartz mold 18.

[0053] It also includes a vacuum system capable of evacuating gravity casting furnaces and injection casting furnaces, preferably evacuating to 10... -3 Pa.

[0054] It also includes an induction heating system. Both the gravity casting furnace and the injection casting furnace are located in the induction heating system during operation. The induction heating system heats the gravity casting furnace and the injection casting furnace, and monitors and maintains the temperature of the gravity casting furnace and the injection casting furnace through the graphite crucible thermocouple 7, the bottom ingot mold thermocouple 8 and the thermocouple in the thermocouple insertion slot 14, respectively.

[0055] A method for controlling the macroscopic uniformity of the solidification process of U-Pu-Zr metallic fuels includes the following steps:

[0056] Step 1: Raw material preparation; using metal U rods and Zr particles as raw materials for preparing U-Zr fuel cores, and using metal U rods, Zr particles and Pu metal ingots as raw materials for preparing U-Pu-Zr core 12.

[0057] Step 1.1: Use a lathe to perform surface treatment on the metal U rod, remove the oxide layer of 0.5 to 2 mm from the outer surface, and determine the amount of metal U to be fed according to the U-Pu-Zr metal fuel ratio (metal Zr accounts for 10%, metal Pu accounts for 1% to 20%, metal U accounts for 70% to 89%), to form metal U ingot 11.

[0058] Step 1.2: Weigh the Zr metal particles according to the U-Pu-Zr metal fuel ratio, and use solvents such as acetone and anhydrous ethanol to clean the contaminants on the metal surface to form Zr metal particles 9.

[0059] Step 1.3: Based on the U-Pu-Zr metal fuel ratio, use a lathe to cut a suitable weight of Pu metal from the Pu metal ingot to form metal Pu10.

[0060] Step 1.4: Assemble the bottom ingot mold 5 for casting with the graphite crucible 2. Place the Zr granules 9 at the bottom of the graphite crucible 2, place the Pu 10 on top of the Zr granules 9, and place the U ingot 11 on the top layer. Load the furnace. See attached diagram for details. Figure 2 As shown.

[0061] Step 2: Alloy smelting;

[0062] Step 2.1: Start the vacuum system and evacuate the gravity casting furnace to 10°C. -3 Pa.

[0063] Step 2.2: Start the induction heating system to heat the graphite crucible 2 and the bottom ingot mold 5. Set the heating temperature of the graphite crucible 2 to 1300℃~1600℃ and the heating temperature of the bottom ingot mold 5 to 1200℃~1400℃.

[0064] Step 2.3: After the temperature of graphite crucible 2 reaches the set temperature, it is kept at that temperature for 20 to 40 minutes to allow all the metal inside the graphite crucible 2 to melt and form a preliminary alloy liquid. Then, the casting process is started, and the bottom ingot mold 5 descends and separates from the graphite crucible 2. The molten preliminary alloy liquid flows from the bottom hole of the graphite crucible 2 into the casting tray 4 under the action of gravity, and then flows into the bottom ingot mold 5 through the bottom hole of the casting tray 4, thus completing the melting and casting.

[0065] Step 2.4: After the gravity casting furnace is cooled to below 40°C, the mold is removed and the U-Pu-Zr master alloy is obtained after demolding.

[0066] Step 3: Core melting;

[0067] Step 3.1: The U-Pu-Zr master alloy obtained in Step 2 is surface treated by removing 0.5-2 mm of oxide slag from the surface using a lathe. Then, it is divided according to the crucible feeding limit (400g-1000g) and placed into the injection casting furnace crucible 13.

[0068] Step 3.2: Start the vacuum system and evacuate the injection casting furnace to 10°C. -3 Pa.

[0069] Step 3.3: Set the heating temperature of the injection casting furnace crucible 13 to 1300℃~1550℃, the preheating temperature of the quartz mold 18 to 600℃~1000℃, insert the thermocouple into the thermocouple insertion slot 14, and start the thermocouple heating. The U-Pu-Zr master alloy obtained in step 3 forms alloy liquid 19 in the injection casting furnace crucible 13.

[0070] Step 3.4: After the quartz mold 18 reaches the set temperature, it is kept at that temperature for 10 to 30 minutes. Then, the injection program is started. The quartz mold 18 is lowered and inserted into the alloy liquid 19 in the crucible 13 of the injection casting furnace. A pressure difference is formed between the surface of the alloy liquid 19 and the inside of the quartz mold 18, so that the alloy liquid 19 is injected into the quartz mold 18.

[0071] Step 3.5: The alloy liquid 19 solidifies into a solid in the quartz mold 18. During the cooling process, air is blown into the quartz mold 18 through the air blowing hole 16 to accelerate the cooling. The flow rate of the blowing argon gas is 1-10 L / min. The temperature of the quartz mold 18 drops to 600℃ within 1-20 minutes.

[0072] Step 3.6: After the injection casting furnace is cooled to below 40°C, the quartz mold 18 is broken to obtain the U-Pu-Zr core.

[0073] Step 4: Core testing;

[0074] Step 4.1: Using a lathe, take 2g of chips from the upper, middle and lower parts of the U-Pu-Zr core obtained in Step 3 for U, Pu and Zr content analysis.

[0075] Step 4.2: Measure the relative contents of U and Zr using X-ray fluorescence method, and measure the Pu content in the U-Pu-Zr core using controlled potential coulometric method. The difference in U, Pu, and Zr contents in the upper, middle, and lower parts of the U-Pu-Zr core does not exceed ±1wt%, indicating that the macroscopic uniformity of the core is qualified.

[0076] The following is a specific embodiment.

[0077] Step 1: Raw material preparation; using metal U rods and Zr particles as raw materials for preparing U-Zr fuel cores, and using metal U rods, Zr particles and Pu metal ingots as raw materials for preparing U-Pu-Zr core 12.

[0078] Step 1.1: The metal U rod is surface treated using a lathe to remove 0.5 mm of oxide layer from the outer surface. Based on the U-Pu-Zr metal fuel ratio (10% metal Zr, 10% metal Pu, and 80% metal U), the amount of metal U to be fed is determined to be 560 g, forming metal U ingot 11.

[0079] Step 1.2: Weigh 70g of Zr metal particles according to the U-10Pu-10Zr metal fuel ratio, and clean the contaminants on the metal surface using solvents such as acetone and anhydrous ethanol to form Zr metal particles 9.

[0080] Step 1.3: According to the U-10Pu-10Zr metal fuel ratio, use a lathe to cut 70g of Pu metal of appropriate weight from the Pu metal ingot to form metal Pu10.

[0081] Step 1.4: Assemble the bottom ingot mold 5 for casting with the graphite crucible 2. Place the Zr granules 9 at the bottom of the graphite crucible 2, place the Pu 10 on top of the Zr granules 9, and place the U ingot 11 on the top layer. Load the furnace. See attached diagram for details. Figure 2 As shown.

[0082] Step 2: Alloy smelting;

[0083] Step 2.1: Start the vacuum system and evacuate the gravity casting furnace to a vacuum level of 6×10⁻⁶. -3 Pa.

[0084] Step 2.2: Set the heating temperature of graphite crucible 2 to 1450℃ and the preheating temperature of bottom ingot mold 5 to 1300℃, and start the induction heating system of both graphite crucible and bottom ingot mold.

[0085] Step 2.3: After the temperature of graphite crucible 2 reaches 1450℃, it is kept at that temperature for 30 minutes to allow all the metal inside the graphite crucible 2 to melt. Then, the casting process is started, and the bottom ingot mold 5 descends and separates from the graphite crucible 2, so that the molten alloy liquid can flow from the graphite crucible 2 into the casting tray 4. Under the action of gravity, it flows through the casting tray 4 into the bottom ingot mold 5, completing the melting and casting.

[0086] Step 2.4: After the gravity casting furnace is cooled to below 40°C, the mold is removed and the U-Pu-Zr master alloy is obtained after demolding.

[0087] Step 3: Core melting;

[0088] Step 3.1: The U-Pu-Zr master alloy obtained in Step 2 is surface treated by removing 2mm of oxide slag from the surface using a lathe. Then, according to the crucible feeding limit (400g~1000g), 600g is divided and placed into the injection casting furnace crucible 13.

[0089] Step 3.2: Start the vacuum system and evacuate the injection casting furnace to a vacuum level of 2×10⁻⁶. -3 Pa.

[0090] Step 3.3: Set the heating temperature of the injection casting furnace crucible 13 to 1450℃, the preheating temperature of the quartz mold 18 to 950℃, insert the thermocouple into the thermocouple insertion slot 14, and start the thermocouple heating. The U-Pu-Zr master alloy obtained in step 3 forms alloy liquid 19 in the injection casting furnace crucible 13.

[0091] Step 3.4: After the quartz mold 18 reaches 1450℃, it is kept at that temperature for 20 minutes. Then the injection program is started. The quartz mold 18 is lowered and inserted into the alloy liquid 19 in the crucible 13 of the injection casting furnace. A pressure difference is formed between the surface of the alloy liquid 19 and the inside of the quartz mold 18, so that the alloy liquid 19 is injected into the quartz mold 18.

[0092] Step 3.5: During the cooling process, air is blown into the quartz mold 18 through the air blowing hole 16 to accelerate the cooling. The air blowing argon flow rate is 5L / min. Within 18 minutes, the temperature of the quartz mold 18 drops to 600℃.

[0093] Step 3.6: After the injection casting furnace is cooled to below 40°C, the quartz mold 18 is broken to obtain the U-10Pu-10Zr core.

[0094] Step 4: Core testing;

[0095] Step 4.1: Using a lathe, take 2g of chips from the upper, middle and lower parts of the U-10Pu-10Zr core obtained in Step 3 for U, Pu and Zr content analysis.

[0096] Step 4.2: The relative contents of U and Zr were measured using X-ray fluorescence spectrometry, and the content of Pu was measured using controlled potential coulometric method. The U contents of the upper, middle, and lower parts were 79.55wt%, 80.45wt%, and 80.56wt%, respectively; the Pu contents of the upper, middle, and lower parts were 10.11wt%, 9.68wt%, and 9.79wt%, respectively; and the Zr contents of the upper, middle, and lower parts were 10.34wt%, 9.87wt%, and 9.65wt%, respectively. The differences in U, Pu, and Zr contents did not exceed ±1wt%, and the macroscopic uniformity of the core was qualified.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0098] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0099] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0100] The preferred embodiments disclosed above are merely illustrative of this application. The optional embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this application. These embodiments are selected and specifically described in this application to better explain the principles and practical applications of this application, thereby enabling those skilled in the art to better understand and utilize this application.

Claims

1. A method for controlling the macroscopic uniformity of the solidification process of U-Pu-Zr metallic fuel, and an apparatus for controlling the macroscopic uniformity of the solidification process of U-Pu-Zr metallic fuel, comprising a gravity casting furnace and an injection casting furnace. The gravity casting furnace includes a graphite crucible (2) and a bottom ingot mold (5). A graphite crucible cover (1) is installed on the upper part of the graphite crucible (2), and a pouring plate (4) is installed on the lower part through a guide sleeve (3). The bottom ingot mold (5) is connected to the lower part of the pouring plate (4), and a bottom cover (6) is installed on the lower part of the bottom ingot mold (5). The pouring plate (4) has a protrusion (20), and the bottom of the graphite crucible (2) has a hole, and the protrusion (20) matches the hole at the bottom of the graphite crucible (2). A graphite crucible thermocouple (7) is installed on the graphite crucible (2), and a bottom ingot mold thermocouple (8) is installed on the bottom ingot mold (5). The injection casting furnace includes an injection casting furnace crucible (13) and a quartz mold (18). The bottom of the injection casting furnace crucible (13) has a thermocouple insertion groove (14). The quartz mold (18) is mounted on a quartz mold support (17) and has an argon gas blowing hole (16). The crucible (13) of the injection casting furnace has a crucible gripping groove (15); The graphite crucible (2) contains Zr particles (9), Pu (10), and U ingots (11); the injection casting furnace crucible (13) contains molten alloy (19). It also includes a vacuum system for evacuating the gravity casting furnace and the injection casting furnace; It also includes an induction heating system; Its features are: Includes the following steps: Step 1: Raw material preparation; Step 1.1: The metal U rod is surface treated using a lathe, and the amount of metal U is determined according to the metal fuel ratio to form metal U ingot (11); Step 1.2: Weigh the Zr metal particles according to the metal fuel ratio and clean the contaminants on the surface to form Zr metal particles (9); Step 1.3: According to the metal fuel ratio, cut out an appropriate weight of Pu metal to form metallic Pu(10); Step 1.4: Assemble the bottom ingot mold (5) and the graphite crucible (2), place the metal Zr particles (9) at the bottom of the graphite crucible (2), place the metal Pu (10) on the top layer of the metal Zr particles (9), and place the metal U ingot (11) on the top layer. The metal fuel composition is 10% Zr, 1%~20% Pu, and 70%~89% U; Step 2: Alloy smelting; Step 2.1: Start the vacuum system and evacuate the gravity casting furnace; Step 2.2: Start the induction heating system to heat the graphite crucible (2) and the bottom ingot mold (5); Step 2.3: After the temperature of the graphite crucible (2) reaches the set temperature, it is kept warm so that all the metal in the graphite crucible (2) melts and forms a preliminary alloy liquid. Then the bottom ingot mold (5) is separated from the graphite crucible (2), so that the preliminary alloy liquid flows from the hole at the bottom of the graphite crucible (2) into the pouring pan (4), and then flows into the bottom ingot mold (5) through the hole at the bottom of the pouring pan (4). Step 2.4: After the gravity casting furnace is cooled to below 40°C, the bottom ingot mold (5) is removed, and the U-Pu-Zr master alloy is obtained after demolding. Step 3: Core melting; Step 3.1: The U-Pu-Zr master alloy obtained in step 2 is surface treated, divided, and placed into the injection casting furnace crucible (13); Step 3.2: Start the vacuum system to evacuate the injection casting furnace; Step 3.3: Set the heating temperature of the injection casting furnace crucible (13) to 1300~1550℃, the temperature of the quartz mold (18) to 600~1000℃, insert the thermocouple into the thermocouple insertion slot (14), and the U-Pu-Zr master alloy obtained in step 3 forms an alloy liquid (19) in the injection casting furnace crucible (13); Step 3.4: After the quartz mold (18) reaches the set temperature, it is kept warm. Then the quartz mold (18) is lowered and inserted into the alloy liquid (19) in the crucible (13) of the injection casting furnace. A pressure difference is formed between the surface of the alloy liquid (19) and the inside of the quartz mold (18), so that the alloy liquid (19) is injected into the quartz mold (18). Step 3.5: The alloy liquid (19) solidifies into a solid in the quartz mold (18), and during the cooling process, air is blown into the quartz mold (18) through the air blowing hole (16) to accelerate the cooling. Step 3.6: After the injection casting furnace is cooled to below 40°C, the quartz mold (18) is broken to obtain the U-Pu-Zr core; Step 4: Core inspection; Take chips from the upper, middle and lower parts of the U-Pu-Zr core obtained in Step 3. If the difference in U, Pu and Zr content in the upper, middle and lower parts of the U-Pu-Zr core is less than ±1wt%, it is considered qualified.

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