Rapid preparation method of alloyed metal fuel sample

Abstract

The invention belongs to the technical field of reactor metal fuel preparation, and particularly relates to a rapid preparation method of an alloyed metal fuel sample. The method comprises the following steps: step 1, raw material surface treatment; 2, raw material distribution; and 3, vacuum non-self-consumption smelting is carried out. By adopting a metal fuel non-consumable smelting process, the preparation of three hectogram-level alloyed metal fuel samples with different components can be successfully realized through experiments of the same furnace, so as to support the research and development of the metal fuel.

Description

Technical Field

[0001] This invention belongs to the field of reactor metal fuel preparation technology, specifically relating to a rapid method for preparing alloyed metal fuel samples. Background Technology

[0002] Compared to conventional fuels (UO2), metallic fuels possess high thermal conductivity, high uranium loading, and high breed ratios. Furthermore, they are compatible with dry reprocessing techniques, facilitating closed-loop fuel cycles. Therefore, they are considered potential fuels for fourth-generation advanced reactor nuclear energy systems and are currently a hot research area for major nuclear technology powers. However, metallic fuels exhibit significant irradiation swelling compared to conventional fuels, affecting fuel element lifespan and burn-up depth. Therefore, current research primarily addresses this by adding alloying elements to metallic fuels to alloy them, refine crystal grains, and solidify fission products. This helps to expel gaseous fission products from grain boundaries, reducing swelling tendency and preventing the migration of fission products to the fuel element cladding surface, which could lead to fuel element failure.

[0003] Traditional alloyed metal fuels are produced by melting raw materials uniformly using induction melting after component proportioning, followed by casting and cooling into ingots. However, limitations of induction melting equipment necessitate meeting minimum feed rates, making it unsuitable for initial component screening of alloyed metal fuels. Furthermore, the slow cooling rate and long experimental cycle of induction melting ingots can lead to alloy segregation, hindering the production of homogeneous alloyed metal fuel ingots and impacting subsequent performance evaluation. Therefore, it is necessary to develop a rapid preparation method for alloyed metal fuel samples for component screening, building upon existing metal fuel melting technologies, to support metal fuel research and development. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a rapid preparation method for alloyed metal fuel samples, which addresses the problems of large feed volume, long preparation cycle and low efficiency in traditional alloyed metal fuel ingot casting. By adopting a non-consumable metal fuel smelting process, it is possible to successfully prepare three alloyed metal fuel samples with different compositions in the same batch of experiments, thus supporting the research and development of metal fuels.

[0005] The technical solution adopted in this invention is as follows:

[0006] A rapid method for preparing alloyed metal fuel samples includes the following steps:

[0007] Step 1: Surface treatment of raw materials; Step 2: Fabrication of raw materials; Step 3: Vacuum non-consumable melting.

[0008] The raw materials are high-purity refined uranium ingots and nuclear-grade pure metal elements.

[0009] The surface treatment of the raw materials specifically includes:

[0010] High-purity uranium ingots were processed into small pieces with a side length of ≤15mm. They were ultrasonically cleaned with acetone for 5-10 minutes to remove surface oil. After being taken out, they were rinsed with alcohol and then soaked in a 40-45 vol.% HNO3 deionized water solution for 3-5 minutes. After that, they were rinsed with alcohol and finally placed on lint-free paper to air dry. According to the composition requirement of no more than 350g of each alloyed metal fuel sample, nuclear-grade pure metal elements and high-purity uranium ingots were weighed sequentially using an electronic balance.

[0011] The raw material fabric is specifically:

[0012] Multiple smelting stations are set up in the water-cooled copper crucible of the vacuum non-consumable melting equipment. All the raw materials required for an alloyed metal fuel sample are placed in each station. The raw materials in each smelting station are placed in order of increasing metal melting point. A small piece of high-purity uranium ingot is placed on top of the raw materials for subsequent melting and arc ignition. Up to three different alloyed metal fuel sample raw materials are placed in the furnace at the same time.

[0013] The vacuum non-consumable melting process is as follows: after closing the furnace door and drawing a vacuum to 5×10-2 Pa, high-purity Ar gas is introduced to raise the pressure inside the furnace to 0.05-0.08 MPa, and melting is carried out by pulse arc ignition.

[0014] The pulsed arc ignition melting process involves adjusting the distance between the non-consumable electrode and the top of the high-purity uranium ingot of the raw material, igniting the arc with a pulse, and immediately raising the non-consumable electrode after ignition, using the electric arc as a heating source to heat and melt the raw material.

[0015] After ignition, a low melting current is used and the position of the arc on the raw material is adjusted. Initially, a low melting current is used and the position of the arc on the raw material is adjusted to ensure that the raw material is heated evenly. After the raw material begins to turn red-hot, the melting current is increased. After all the raw material in the melting station has formed a molten pool, the melting current is further increased to 550-650A.

[0016] Turn on the induction coil below the corresponding work station to perform magnetic induction stirring of the melt; after the molten pool is completely formed and homogenized in the melting crucible work station for 3-5 minutes, reduce the melting current until the arc is extinguished, and cool the alloyed metal fuel sample in the furnace within the work station; move the melting electrode to the next melting work station and repeat the above process.

[0017] Before the arc is broken, the melting current is reduced at a rate of 100-200 A / s, and the arc is continuously controlled to move in circles on the sample surface until the arc is broken.

[0018] Before proceeding to the next melting stage, the cooled sample is flipped 180° and the melting process is repeated.

[0019] The beneficial effects of this invention are:

[0020] (1) The present invention provides a rapid preparation method for alloyed metal fuel samples, which adopts a vacuum non-consumable arc melting process for alloyed metal fuels to rapidly prepare alloyed metal fuel samples with different compositions, so as to realize rapid iteration of alloyed metal fuel research and development.

[0021] (2) The present invention provides a rapid preparation method for alloyed metal fuel samples. By placing raw materials with different composition ratios at different work stations in the same furnace, controlling the melting process of alloyed metal fuel samples by adjusting the melting current and melting passes, cooling the homogenized samples with the furnace, and melting and cooling the metal fuel raw materials at different work stations in sequence, thereby obtaining alloyed metal fuel samples with different compositions in the same furnace experiment.

[0022] (3) The present invention provides a rapid preparation method for alloyed metal fuel samples, which enables the preparation of up to three alloyed metal fuel samples with different compositions in the same batch of experiments, with the uniformity deviation of the main components of the samples within 2% of the target composition. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0024] This invention provides a rapid method for preparing alloyed metal fuel samples, comprising the following steps:

[0025] Step 1: Surface treatment of raw materials

[0026] The raw materials are high-purity uranium ingots (O≤80ppm) and nuclear-grade pure metal elements (purity≥99.9wt.%).

[0027] The high-purity uranium ingots were processed into small pieces with a side length of ≤15mm. They were ultrasonically cleaned with acetone for 5-10 minutes to remove surface oil. After being taken out, they were rinsed with alcohol and then soaked in a 40-45% vol.% HNO3 deionized water solution for 3-5 minutes. After that, they were rinsed with alcohol and finally taken out and placed on lint-free paper to air dry naturally.

[0028] In accordance with the requirement that each alloyed metal fuel sample should not exceed 350g, nuclear-grade pure metal elements and high-purity refined uranium ingots were weighed sequentially using an electronic balance.

[0029] Step 2, Raw material fabric

[0030] Multiple smelting stations are set up in the water-cooled copper crucible of the vacuum non-consumable melting equipment. All the raw materials required for an alloyed metal fuel sample are placed in each station. The raw materials in each smelting station are placed in order of increasing metal melting point. A small piece of high-purity uranium ingot is placed on top of the raw materials for subsequent melting and arc ignition. Up to three different alloyed metal fuel sample raw materials can be placed in the furnace at the same time.

[0031] Step 3: Vacuum non-consumable melting

[0032] Close the furnace door and evacuate to a vacuum level of 5×10. -2 After Pa, high-purity Ar gas (purity ≥ 99.999 wt.%) is introduced to increase the pressure inside the furnace to 0.05–0.08 MPa.

[0033] Adjust the distance between the non-consumable electrode and the top of the high-purity uranium ingot, then pulse-ignite the arc. Immediately after ignition, raise the non-consumable electrode and use the electric arc as a heating source to heat and melt the raw material. After ignition, use a low melting current (≤350A) and adjust the position of the arc on the raw material.

[0034] Initially, a low melting current is used and the position of the electric arc on the raw material is adjusted to ensure uniform heating. Once the raw material begins to glow red-hot, the melting current is increased. After the raw material in the melting station has formed a molten pool, the melting current is further increased to (550-650) A, and the induction coil below the corresponding station is activated to magnetically stir the melt. After the molten pool in the melting crucible station has completely formed and become homogeneous (3-5 minutes), the melting current is reduced until the arc is extinguished. Before extinguishing the arc, the melting current is reduced at a rate of (100-200) A / s, and the electric arc is continuously controlled to circle around the sample surface until the arc is extinguished. The alloyed metal fuel sample is cooled in the furnace within the station. The melting electrode is moved to the next melting station, and the above process is repeated. Before the alloyed metal fuel sample undergoes the next melting pass, the cooled sample is rotated 180° and the above melting process is repeated. Depending on the actual condition of the alloyed metal fuel sample, it is melted a total of (3-5) times before being cooled and removed from the furnace.

[0035] Using the above process, 100-gram samples of alloyed metallic fuel with three different compositions can be prepared in the same batch of experiments. Testing showed that the uniformity deviation of the main components in the samples was within 2% of the target composition.

[0036] While those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention, the embodiments should be considered in all respects as exemplary and non-limiting. The scope of the invention is defined by the appended claims rather than the foregoing description, and therefore all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

[0037] Furthermore, it should be understood that although the present invention is described according to embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A rapid preparation method for alloyed metal fuel samples, characterized in that, Includes the following steps: Step 1: Surface treatment of raw materials; Step 2: Fabrication of raw materials; Step 3: Vacuum non-consumable melting.

2. The rapid preparation method for alloyed metal fuel samples according to claim 1, characterized in that, The raw materials are high-purity refined uranium ingots and nuclear-grade pure metal elements.

3. The rapid preparation method for alloyed metal fuel samples according to claim 2, characterized in that, The surface treatment of the raw materials specifically includes: High-purity uranium ingots were processed into small pieces with a side length of ≤15mm. They were ultrasonically cleaned with acetone for 5-10 minutes to remove surface oil. After being taken out, they were rinsed with alcohol and then soaked in a 40-45 vol.% HNO3 deionized water solution for 3-5 minutes. After that, they were rinsed with alcohol and finally placed on lint-free paper to air dry. According to the composition requirement of no more than 350g of each alloyed metal fuel sample, nuclear-grade pure metal elements and high-purity uranium ingots were weighed sequentially using an electronic balance.

4. The rapid preparation method for alloyed metal fuel samples according to claim 3, characterized in that, The raw material fabric is specifically: Multiple smelting stations are set up in the water-cooled copper crucible of the vacuum non-consumable melting equipment. All the raw materials required for an alloyed metal fuel sample are placed in each station. The raw materials in each smelting station are placed in order of increasing metal melting point. A small piece of high-purity uranium ingot is placed on top of the raw materials for subsequent melting and arc ignition. Up to three different alloyed metal fuel sample raw materials are placed in the furnace at the same time.

5. The rapid preparation method for alloyed metal fuel samples according to claim 4, characterized in that, The vacuum non-consumable melting process specifically involves: closing the furnace door and evacuating to a vacuum level of 5×10⁻⁶. -2 After Pa, high-purity Ar gas is introduced to raise the pressure inside the furnace to 0.05-0.08 MPa, and melting is carried out by pulse arc ignition.

6. The rapid preparation method for alloyed metal fuel samples according to claim 5, characterized in that, The pulsed arc ignition melting process involves adjusting the distance between the non-consumable electrode and the top of the high-purity uranium ingot of the raw material, igniting the arc with a pulse, and immediately raising the non-consumable electrode after ignition, using the electric arc as a heating source to heat and melt the raw material.

7. The rapid preparation method for alloyed metal fuel samples according to claim 6, characterized in that, After ignition, a low melting current is used and the position of the arc on the raw material is adjusted. Initially, a low melting current is used and the position of the arc on the raw material is adjusted to ensure that the raw material is heated evenly. After the raw material begins to turn red-hot, the melting current is increased. After all the raw material in the melting station has formed a molten pool, the melting current is further increased to 550-650A.

8. The rapid preparation method for alloyed metal fuel samples according to claim 7, characterized in that, Turn on the induction coil below the corresponding work station to perform magnetic induction stirring of the melt; after the molten pool is completely formed and homogenized in the melting crucible work station for 3-5 minutes, reduce the melting current until the arc is extinguished, and cool the alloyed metal fuel sample in the furnace within the work station; move the melting electrode to the next melting work station and repeat the above process.

9. The rapid preparation method for alloyed metal fuel samples according to claim 8, characterized in that, Before the arc is broken, the melting current is reduced at a rate of 100-200 A / s, and the arc is continuously controlled to move in circles on the sample surface until the arc is broken.

10. The rapid preparation method for alloyed metal fuel samples according to claim 9, characterized in that, Before proceeding to the next melting stage, the cooled sample is flipped 180° and the melting process is repeated.