System and method for processing fuel elements

Abstract

The embodiment of the invention relates to the field of reactor fuel elements, in particular to a system and method for processing a fuel element. The fuel element comprises a shell, a plurality of pellets, a cooling medium and gas, wherein the pellets, the cooling medium and the gas are arranged in the shell, and the pellets are located below the liquid level of the cooling medium. The system comprises a holding device, a heating device and a vibrating device. The holding device is used for holding a plurality of fuel elements; the heating device is used for heating the multiple fuel elements so that cooling media of the fuel elements can be in a liquid state. And the vibration device is used for driving the holding device to vibrate, so that the multiple fuel elements are driven to vibrate, and gas in the liquid cooling medium can escape to the position above the liquid level of the cooling medium. According to the processing system provided by the embodiment of the invention, the liquid cooling medium can be uniformly distributed in the shell, the heat transfer efficiency between the shell of the fuel element and the pellet can be improved, and the phenomenon of local overheating of the fuel element is avoided.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of reactor fuel elements, and in particular to a system and method for processing fuel elements. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] The fuel elements of the reactor will generate heat during use. In order to avoid safety hazards caused by the temperature increase of the fuel elements, a reactor coolant is provided outside the fuel elements to cool the fuel elements.

[0004] The fuel element mainly includes a shell and a pellet installed in the shell. The heat generated by the fuel element during use comes from the pellet, which is transferred from the pellet to the shell and then to the reactor coolant outside the shell. When the heat transfer efficiency between the pellet and the shell is low, the heat generated by the pellet cannot be transferred to the reactor coolant in time, causing the temperature of the pellet to rise, resulting in local overheating, which poses a hidden danger to the safe use of the fuel element. Therefore, it is necessary to take measures to improve the heat transfer efficiency between the pellet and the shell.

[0005] At present, a cooling medium is usually added between the shell and the core block to improve the heat transfer efficiency between the core block and the shell. However, when the cooling medium is added, the cooling medium is unevenly distributed, so that the heat transfer efficiency between the core block and the shell cannot be effectively improved. Summary of the invention

[0006] A brief overview of the present application is provided below in order to provide a basic understanding of certain aspects of the present application. It should be understood that this overview is not an exhaustive overview of the present application. It is not intended to identify the key or important parts of the present application, nor is it intended to limit the scope of the present application. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0007] In the related art, the method of adding metallic sodium to the shell is usually to directly add liquid sodium to the shell. Since the melting point of metallic sodium is relatively high, it is necessary to heat the metallic sodium to about 97.8°C to melt it. Therefore, in the process of filling liquid sodium, if the heating temperature of the container wall cannot reach about 97.8°C, the liquid sodium may solidify quickly when it contacts the cooler wall. This phenomenon will cause the metallic sodium to condense at the entrance of the shell, forming a blockage, thereby preventing the subsequent addition of liquid sodium. Once this happens, the shell needs to be additionally heated to re-melt the condensed sodium, or the shell needs to be replaced and the sodium filling process restarted. This process is not only time-consuming, but may also increase operational risks.

[0008] In the improved method, the method of adding metallic sodium to the shell is to directly add solid sodium to the shell. Then, the pellet is placed in the shell and located above the solid sodium part; the shell is heated to melt the solid sodium part and surround the pellet. The inventor of the present application found that in this process, some gas will be trapped at the lower end of the shell, and will squeeze the liquid sodium to move upward in an unstable manner, so that pores and air gaps are formed inside the liquid sodium, resulting in uneven distribution of the liquid sodium, which in turn leads to the problem of local overheating of the fuel element.

[0009] To solve the above problems, the embodiments of the present application provide a system and method for processing a fuel element. The fuel element includes a shell and a plurality of pellets disposed in the shell, a cooling medium and a gas, wherein the plurality of pellets are located below the liquid level of the cooling medium.

[0010] In the first aspect, the system for processing fuel elements provided by the embodiments of the present application includes a holding device, a heating device, and a vibrating device. The holding device is used to hold a plurality of fuel elements; the heating device is used to heat the plurality of fuel elements so that the cooling medium of the fuel elements is in a liquid state; the vibrating device is used to drive the holding device to vibrate, thereby driving the plurality of fuel elements to vibrate, so that the gas inside the liquid cooling medium can escape to above the liquid surface of the cooling medium.

[0011] The processing system provided in the embodiment of the present application drives the retaining device to vibrate through a vibrating device, thereby driving multiple fuel elements to vibrate, so that the gas inside the cooling medium can escape to above the liquid surface of the cooling medium, and then the liquid cooling medium can be evenly distributed in the shell, which can improve the heat transfer efficiency between the shell and the core block of the fuel element and avoid local overheating of the fuel element.

[0012] In a second aspect, the method for processing fuel elements provided in the embodiments of the present application is implemented using the system for processing fuel elements provided in the embodiments of the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other objects and advantages of the present application will become apparent from the following description of the embodiments of the present application with reference to the accompanying drawings, and will help to provide a comprehensive understanding of the present application.

[0014] Figure 1 It is a schematic diagram of the structure of a system for processing fuel elements provided in an embodiment of the present application.

[0015] Figure 2 yes Figure 1 A schematic diagram of the structure of the main body of a system for processing fuel elements is shown.

[0016] Figure 3The fuel element and Figure 1 A schematic diagram of the structure of the holding device of the system for handling fuel elements after assembly is shown.

[0017] Figure 4 yes Figure 3 A front view of the structure is shown.

[0018] Figure 5 yes Figure 4 A cross-sectional view of the structure is shown.

[0019] Figure 6 yes Figure 5 A partial enlarged view of .

[0020] Figure 7 yes Figure 2 An exploded schematic diagram of the structure is shown.

[0021] Description of reference numerals:

[0022] 100. A system for processing fuel elements;

[0023] 10. holding device; 11. holding portion; 111. holding member; 1111. clamping groove; 112. clamping member; 12. connecting portion; 13. extending portion; 14. supporting portion;

[0024] 20. Heating device; 21. Heating shell; 211. Half shell; 2111. Shell; 2112. Insulating member; 22. Inner shell; 221. Connecting member; 23. Gas passage; 201. Heating chamber; 2101. Opening;

[0025] 30. Vibration device; 31. Mechanical vibration part; 311. Main body; 312. Vibration part; 32. Ultrasonic vibration part; 321. Mounting connector;

[0026] 40. Mounting plate; 50. Lifting device;

[0027] 60. Sealing device; 61. Bellows; 611. Sealing connector; 612. Vibrating connector; 62. Sealing connector; 621. First connector; 622. Second connector; 623. Connecting pipe; 624. Mounting interface; 6241. Matching connector;

[0028] 70. Cooling device; 71. Cooling fan; 80. Control device;

[0029] 101. guide member; 102. guide connector; 103. air inlet pipe; 104. air outlet pipe;

[0030] 200. Fuel elements.

[0031] It should be noted that the drawings are not necessarily drawn to scale, but are merely shown in a schematic manner that does not affect the reader's understanding. DETAILED DESCRIPTION

[0032] Exemplary embodiments of the present application will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual implementation are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual implementation in order to achieve the developer's specific goals, such as meeting those constraints related to the system and business, and these constraints may vary from implementation to implementation. In addition, it should be understood that although the development work may be very complex and time-consuming, it is only a routine task for those skilled in the art who benefit from the content of this application.

[0033] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure and / or processing steps closely related to the scheme according to the present application are shown in the accompanying drawings, while other details that are not very relevant to the present application are omitted.

[0034] See also Figure 1 and Figure 2 The system 100 for processing the fuel element 200 provided in the embodiment of the present application (hereinafter referred to as the processing system 100) may include a holding device 10, a heating device 20 and a vibrating device 30. The holding device 10 is used to hold a plurality of fuel elements 200; the heating device 20 is used to heat the plurality of fuel elements 200 so that the cooling medium of the fuel elements 200 is in a liquid state; the vibrating device 30 is used to drive the holding device 10 to vibrate, thereby driving the plurality of fuel elements 200 to vibrate, so that the gas inside the liquid cooling medium can escape to above the liquid surface of the cooling medium.

[0035] The processing system 100 provided in the embodiment of the present application drives the retaining device 10 to vibrate through the vibration device 30, thereby driving the multiple fuel elements 200 to vibrate, so that the gas inside the cooling medium can escape to above the liquid surface of the cooling medium, and then the liquid cooling medium can be evenly distributed in the shell, which can improve the heat transfer efficiency between the shell and the core block of the fuel element and avoid local overheating of the fuel element 200.

[0036] In some embodiments, the cooling medium may be sodium metal.

[0037] In some embodiments, the heating device 20 may heat the fuel element 200 to 550° C. to process the fuel element 200 .

[0038] In some embodiments, the holding device 10 is capable of holding 10 to 30, for example 20, fuel elements 200 .

[0039] See also Figure 2 In some embodiments, the vibration device 30 may include a mechanical vibration unit 31, which is used to drive the holding device 10 to vibrate. The gas inside the liquid cooling medium will form bubbles inside the cooling medium. In such an embodiment, the mechanical vibration unit 31 can make the large bubbles inside the cooling medium form small bubbles under the action of mechanical vibration, which is conducive to the bubbles escaping to the surface of the cooling medium.

[0040] The mechanical vibration unit 31 is, for example, a mechanical vibration table.

[0041] In some embodiments, the mechanical vibration part 31 can provide a thrust in the vertical direction, so that the fuel element 200 can vibrate in the vertical direction. In some embodiments, the maximum thrust that the mechanical vibration part 31 can provide is 10 kN.

[0042] See also Figure 2 In some embodiments, the mechanical vibration part 31 may include a body 311 and a vibration part 312 capable of vibrating relative to the body 311. Figure 3 and Figure 4 In some embodiments, the holding device 10 may include a holding portion 11 and a connecting portion 12 connected to the holding portion 11, wherein the holding portion 11 is used to hold a plurality of fuel elements 200, and the connecting portion 12 is used to be connected to the vibrating portion 312, so that the vibrating portion 312 drives the connecting portion 12 and the holding portion 11 to vibrate. In such an embodiment, the vibrating portion 312 can drive the connecting portion 12 and the holding portion 11 to vibrate, so as to achieve vibration of the fuel elements 200.

[0043] See also Figure 3 and Figure 4 In some embodiments, the holding device 10 may further include an extension portion 13, and the extension portion 13 is connected to the connection portion 12. In some embodiments, the holding portion 11 may include a multi-layer holding member 111 and a plurality of clamping members 112, and the multi-layer holding member 111 is connected to the extension portion 13, and each fuel element 200 may be connected to each layer of holding members 111 through a clamping member 112. Since the length of the fuel element 200 is relatively long (the fuel element 200 may reach 1 meter), in such an embodiment, the fuel element 200 is held by the multi-layer holding member 111 and the plurality of clamping members 112, so that the stability of the fuel element 200 during vibration can be ensured, and the fuel element 200 is prevented from shaking.

[0044] See also Figure 3In some embodiments, a clamping groove 1111 may be formed on the radially outer side of the retaining member 111, and each fuel element 200 is clamped in the clamping groove 1111 by the clamping member 112. In such an embodiment, the fuel element 200 is clamped by the clamping member 112 and the clamping groove 1111, so that the fuel element 200 and the retaining member 111 can be prevented from being separated during vibration.

[0045] In some embodiments, the clamping member 112 is, for example, a clamp.

[0046] In some embodiments, the retaining member 111 is, for example, an annular plate.

[0047] join Figure 4 and Figure 5 In some embodiments, the holding device 10 may further include a supporting portion 14 connected to the connecting portion 12, the supporting portion 14 being disposed below the multi-layer holding member 111, and the plurality of fuel elements 200 being in contact with the supporting portion 14, so that the plurality of fuel elements 200 are supported by the supporting portion 14. In such an embodiment, the plurality of fuel elements 200 are supported by the supporting portion 14, which is conducive to improving the stability of the holding portion 11 in holding the fuel elements 200.

[0048] See also Figure 5 In some embodiments, the heating device 20 is configured to form a heating chamber 201 having an opening at the bottom. Figure 1 and Figure 3 In some embodiments, the processing system 100 may further include a mounting plate 40, a lifting device 50, a sealing device 60, and a gas provider. The mounting plate 40 is disposed on the body 311, and a through hole is formed in the mounting plate 40. The connecting portion 12 of the holding device 10 is connected to the vibrating portion of the mechanical vibrating portion 31 through the through hole; the lifting device 50 is disposed on the mounting plate 40, and is used to drive the heating device 20 to move up and down, so that the holding portion 11 is located outside or inside the heating chamber 201; the sealing device 60 is used to seal the heating chamber 201 when the lifting device 50 drives the heating device 20 to descend to abut against the sealing device 60; and the gas provider is used to provide a protective gas to the heating chamber 201. In such an embodiment, the heating device 20 is driven up and down by the lifting device 50 to load and unload the holding device 10 and the fuel element 200; the heating chamber 201 is sealed by the sealing device 60, and the protective gas is provided to the heating chamber 201 by the gas provider, so that external air can be prevented from entering the heating chamber 201, and the fuel element 200 is prevented from contacting with the external air when it is damaged.

[0049] See also Figure 3In some embodiments, the retaining member 111, the supporting portion 14, the extending portion 13 and the connecting portion 12 can be configured as a hollow structure. The hollow structure can reduce the overall weight on the one hand; on the other hand, since the cooling medium in the shell of the fuel element 200 expands after being heated, the shell may be damaged and then flow out of the shell. In such an embodiment, the retaining member 111, the supporting portion 14, the extending portion 13 and the connecting portion 12 are configured as a hollow structure, so that the cooling medium flowing out of the shell can flow to the bottom of the retaining device 10, avoiding splashing under the action of vibration, thereby facilitating the collection of the flowing cooling medium and facilitating the uniform distribution of the protective gas.

[0050] See also Figure 6 In some embodiments, the sealing device 60 may include a bellows 61 and a sealing connection portion 62 connected to the bellows 61. The bellows 61 is used to connect the vibration portion 312 and the mounting plate 40; the sealing connection portion 62 is disposed on the mounting plate 40, and is used to be sealed and connected to the heating device 20 when the lifting device 50 drives the heating device 20 to descend so that the holding portion 11 is located inside the heating chamber 201. In such an embodiment, since the bellows 61 connects the vibration portion 312 and the mounting plate 40, and the sealing connection portion 62 is disposed on the mounting plate 40 and connected to the bellows 61, the bellows 61, the sealing connection portion 62, and the vibration portion 312 can seal the heating chamber 201 together. At the same time, since the vibration part 312 is connected to the mounting plate 40 through the bellows 61, the mounting plate 40 will not vibrate along with the vibration part 312 when the vibration part 312 vibrates; since the lifting device 50 and the sealing connection part 62 are both arranged on the mounting plate 40, when the vibration part 312 vibrates, the heating device 20 will not vibrate along with the vibration part 312 either.

[0051] See also Figure 5 In some embodiments, the heating device 20 may further include a heating outer shell 21 and an inner shell 22, wherein the inner shell 22 is disposed radially inward of the heating outer shell 21, and the inner shell 22 is configured to form a heating chamber 201. An opening 2101 is formed below the heating outer shell 21, and the lower end of the inner shell 22 extends from the opening 2101 to a position protruding from the heating outer shell 21. The heating outer shell 21 can heat the inner shell 22, and thus can heat the retaining portion 11 and the fuel element 200.

[0052] The heating outer shell 21 is, for example, a heating furnace, and the inner shell 22 is, for example, a high-temperature kettle. In some embodiments, the heating device 20 may further include a heating connector for connecting the heating outer shell 21 and the inner shell 22. The heating connector may be, for example, a screw.

[0053] See also Figure 5In some embodiments, the heating outer shell 21 may include two half shells 211, the two half shells 211 are provided with lateral openings, and the lateral openings of the two half shells 211 are arranged opposite to each other; the two half shells 211 are arranged to be hingedly connected so that the relative position state of the two half shells 211 can be switched between an open state and a closed state; wherein, when the relative position state of the two half shells 211 is in an open state, the inner shell 22 is exposed. In some embodiments, the two half shells 211 may also be provided with a bottom opening communicating with the lateral opening, and the bottom openings of the two half shells 211 together form an opening 2101.

[0054] See also Figure 5 In some embodiments, each half shell 211 may include a shell 2111, a heating element, and a heat preservation element 2112. The heating element is disposed on the heat preservation element 2112 to heat the inner shell 22; the heat preservation element 2112 is connected to the shell 2111 to keep the heating element warm; the shell 2111 is disposed on the outside of the heat preservation element 2112 to protect the heating element and the heat preservation element 2112. In some embodiments, the shell 2111 and the heat preservation element 2112 are configured to form a side opening and a bottom opening.

[0055] The inner shell 22 is a cylindrical member with a closed upper end and an open lower end. The sealing device 60 is used to seal the inner shell 22.

[0056] See also Figure 6 In some embodiments, the sealing connection part 62 may be fixedly connected to the bellows 61. In some embodiments, the sealing connection part 62 may include a first connection member 621, a second connection member 622, and a connection pipe member 623. The first connection member 621 is sealedly connected to the inner shell 22, the second connection member 622 is fixedly connected to the bellows 61, and the connection pipe member 623 is used to connect the first connection member 621 and the second connection member 622.

[0057] See also Figure 6 In some embodiments, a connector 221 may be formed at the lower end of the inner shell 22 , and the connector 221 is sealed and connected to the first connector 621 , so that the bellows 61 , the sealing connection part 62 , and the vibration part 312 can seal the heating chamber 201 together.

[0058] See also Figure 6 In some embodiments, the sealing device 60 may include a sealing connector 611 and a vibration connector 612. The sealing connector 611 and the vibration connector 612 are respectively connected to both ends of the bellows 61. The sealing connector 611 is fixedly connected to the second connector 622 of the sealing connection part 62, and the sealing connector 611 is also connected to the mounting plate 40; the vibration connector 612 is connected to the vibration part 312.

[0059] The first connection member 621 , the second connection member 622 , the sealing connection member 611 and the vibration connection member 612 are flanges, for example.

[0060] In some embodiments, the shielding gas may be an inert gas, such as argon gas, and accordingly, the gas provider may be an inert gas bottle, such as an argon gas bottle.

[0061] See also Figure 5 In some embodiments, the processing system 100 may further include an air inlet pipeline 103, which is disposed at the lower end of the inner shell 22 and located outside the heating outer shell 21. The air inlet pipeline 103 is fluidly connected to the heating chamber 201 and the gas provider, and the protective gas provided by the gas provider can enter the heating chamber 201 through the air inlet pipeline 103.

[0062] See also Figure 5 In some embodiments, the processing system 100 may further include an outlet pipe 104, which is disposed at the upper end of the inner shell 22. The outlet pipe 104 is in fluid communication with the heating chamber 201, and the gas in the heating chamber 201 may flow out of the heating chamber 201 through the outlet pipe 104. In some embodiments, the heating outer shell 21 is formed with a gas channel 23, which is formed at the upper end of the heating outer shell 21. The outlet pipe 104 is disposed in the gas channel 23 and extends from the gas channel 23 to the outside of the heating outer shell 21.

[0063] join Figure 2 In some embodiments, the processing system 100 may further include a guide member 101 and a guide connector 102. The guide member 101 is disposed on the mounting plate 40. The guide member 101 and the heating housing 21 are connected by the guide connector 102, and are used to provide guidance for the heating device 20 when the lifting device 50 drives the heating device 20 to rise and fall. In some embodiments, the guide member 101 may be disposed between the lifting device 50 and the heating device 20. The guide member 101 is, for example, a rod. The lifting device 50 is, for example, an electric push cylinder.

[0064] See also Figure 2 In some embodiments, the vibration device 30 may further include an ultrasonic vibration part 32, and the ultrasonic vibration part 32 is used to drive the holding device 10 to vibrate through ultrasound. In such an embodiment, after the mechanical vibration part 31 is used to drive the fuel element 200 to vibrate mechanically so that large bubbles in the cooling medium form small bubbles under the action of mechanical vibration, the holding device 10 is then driven to vibrate by ultrasound so that the small bubbles in the cooling medium can move upward to above the liquid surface of the cooling medium. The embodiments of the present application facilitate the gas inside the liquid cooling medium to escape to above the liquid surface of the cooling medium through the synergistic effect of the mechanical vibration part 31 and the ultrasonic vibration part 32. The ultrasonic vibration part 32 is, for example, an ultrasonic vibration generator.

[0065] In some embodiments, the ultrasonic vibration part 32 can make the fuel element 200 vibrate at an ultrasonic vibration frequency of 20 kHz. In some embodiments, the number of the ultrasonic vibration part 32 can be one or more, for example, two. Figure 6 In some embodiments, the sealing connection portion 62 may further include at least one mounting interface 624 for mounting the ultrasonic vibration portion 32. The mounting interface 624 is disposed on the connecting pipe 623 and is connected to the connecting pipe 623. The ultrasonic vibration portion 32 can pass through the mounting interface 624 and abut against the extension portion 13 of the retaining device 10, thereby transmitting ultrasound to the extension portion 13 of the retaining device 10.

[0066] See also Figure 6 and Figure 7 In some embodiments, the ultrasonic vibration portion 32 is formed with a mounting connector 321, and the mounting interface 624 is formed with a mating connector 6241 at the end facing the ultrasonic vibration portion 32. The mounting connector 321 can be connected to the mating connector 6241, so that the ultrasonic vibration portion 32 can be mounted to the mounting interface 624.

[0067] See also Figure 1 In some embodiments, the processing system 100 may further include a cooling device 70 for cooling components in the processing system 100. In some embodiments, the cooling device 70 may include a cooling fan 71, which may be used to provide cooling for other components in the processing system 100 to prevent other components from being damaged due to excessive temperature, so as to protect other components in the processing system 100. For example, the cooling fan 71 may be used to provide cooling for the mechanical vibration unit 31 to protect the mechanical vibration unit 31.

[0068] See also Figure 1 In some embodiments, the processing system 100 may further include a control device 80 for controlling and recording the temperature in the heating chamber 201, and the vibration thrust, vibration frequency, vibration displacement, etc. of the mechanical vibration part 31. In some embodiments, the processing system 100 may further include a power regulator, and the control device 80 controls the temperature in the heating chamber 201 by adjusting the power regulator.

[0069] The embodiment of the present application also provides a method for processing a fuel element 200 (hereinafter referred to as a processing method). The processing method is implemented using the processing system 100 provided in any embodiment of the present application.

[0070] In some embodiments, the treatment method may include: heating the fuel element 200 so that the cooling medium of the fuel element 200 is in a liquid state; driving the fuel element 200 to perform mechanical vibration so that large bubbles in the cooling medium are formed into small bubbles under the action of the mechanical vibration; and then, using ultrasonic waves to perform ultrasonic vibrations on the fuel element 200 so that the small bubbles in the cooling medium can move upward to above the liquid surface of the cooling medium.

[0071] In the embodiment of the present application, mechanical vibration is first performed in the up-and-down direction (the direction of the mechanical vibration is the same as the axial direction of the fuel element 200). Since the fuel element 200 has a stroke during the up-and-down vibration, most of the bubbles that are not blocked in the vertical direction can be eliminated (i.e., the bubbles are not between the two pellets, and they can move directly upward to above the cooling medium liquid surface without being blocked), and the bubbles stuck between two adjacent pellets can be moved horizontally to the outside of the pellets, and further moved upward to above the cooling medium liquid surface; in addition, large bubbles can be vibrated into small bubbles; and ultrasonic vibration is then used, because ultrasound is usually high frequency with a small amplitude, small bubbles can be moved upward. The embodiment of the present application facilitates the gas inside the liquid cooling medium to escape above the cooling medium liquid surface through the synergistic effect of mechanical vibration and ultrasonic waves.

[0072] In some embodiments, before heating the fuel element 200 , the air in the heating chamber 201 may be replaced with a protective gas to protect the fuel element 200 .

[0073] Specifically, the air in the heating chamber 201 can be replaced with protective gas through the air inlet pipeline 103 , the air outlet pipeline 104 and the gas providing member to protect the fuel element 200 .

[0074] In some embodiments, before heating the fuel element 200, the size and distribution of bubbles formed by the gas inside the liquid cooling medium can be determined by ultrasound, and whether to use ultrasonic vibration or mechanical vibration first and then ultrasonic vibration can be determined based on the size and distribution of bubbles formed by the gas inside the liquid cooling medium. In such an embodiment, the gas inside the liquid cooling medium can be more reasonably and quickly allowed to escape above the liquid surface of the cooling medium.

[0075] In some embodiments, when the bubble size inside the liquid cooling medium is larger than a preset size, mechanical vibration is used first, and then ultrasonic vibration is used; when the bubble size inside the liquid cooling medium is smaller than the preset size, ultrasonic vibration can be used directly. In some embodiments, the preset size can be 1.5 mm.

[0076] The inventor of the present application has found that when bubbles are between two adjacent core blocks, even if the bubble size is smaller than the preset size, it is difficult to move the bubbles out from between the two core blocks by using ultrasonic vibration. Therefore, in some embodiments, when the bubble size inside the liquid cooling medium is smaller than the preset size, but some bubbles are between two adjacent core blocks, mechanical vibration is first used to move the bubbles stuck between the two adjacent core blocks horizontally to the outside of the core blocks, and further move upward to above the cooling medium liquid surface; then ultrasonic vibration is used.

[0077] It is easy to understand that for a fuel element, its shell is welded by a cladding tube and end caps at both ends. There is a risk of adversely affecting the weld when removing bubbles by mechanical vibration.

[0078] Therefore, in the embodiments of the present application, it is first determined whether mechanical vibration is needed based on the size and position of the bubbles. When the bubble size is small and there is no obstruction in the vertical direction, ultrasonic vibration can be used to remove the bubbles to minimize the risk of adverse effects on the weld.

[0079] When the bubble size is large or there are bubbles between two core blocks, mechanical vibration is used to remove the bubbles.

[0080] In some embodiments, when there are no bubbles between two adjacent pellets, it is easy to make the bubbles rise to the liquid surface by mechanical vibration, so a small amplitude mechanical vibration can be used to reduce the risk of adversely affecting the weld. When some bubbles are between two adjacent pellets, the amplitude of the mechanical vibration used is greater than the amplitude of the mechanical vibration used when there are no bubbles between the two adjacent pellets, so as to facilitate the bubbles to move out of the gap between the two pellets.

[0081] In some embodiments, when some bubbles are between two adjacent core blocks, the amplitude of the mechanical vibration used may be 5-10 mm; when no bubbles are between two adjacent core blocks, the amplitude of the mechanical vibration used may be less than 5 mm.

[0082] In some embodiments, since the processing system of the embodiment of the present application can process multiple fuel elements at the same time, the multiple fuel elements to be processed can be grouped according to the size of bubbles formed by the fuel element gas and the distribution of bubbles, and the fuel elements that need to be mechanically vibrated with a larger amplitude can be grouped together, and the fuel elements that need to be mechanically vibrated with a smaller amplitude can be grouped together, and the fuel elements that only need ultrasonic vibration can be grouped together, and the fuel elements of different groups can be put into the processing system in batches for processing. In this way, the adverse effects of vibration on the fuel elements can be minimized when it is not necessary.

[0083] The following describes in detail a method for processing a fuel element 200 according to an embodiment of the present application in conjunction with the accompanying drawings and specific embodiments.

[0084] Assemble multiple fuel elements 200 with the holding device 10, and connect the connecting part 12 with the vibrating part 312, lower the high-temperature autoclave 22 by the electric push cylinder 50, so that the fuel elements 200 enter the heating chamber 201, and set the two half shells 211 of the heating furnace 21 to a closed state, so that the heating furnace 21 can cover the high-temperature autoclave 22.

[0085] Open the argon gas bottle, and the argon gas enters the heating chamber 201 through the air inlet pipe 103, and the air in the heating chamber 201 flows out of the heating chamber 201 from the air outlet pipe 104. During this process, the gas pressure in the heating chamber 201 is maintained at 0.05MPa, and pressure protection is provided by a pressure relief valve with a pressure setting of 0.1MPa. When the gas pressure in the heating chamber 201 exceeds 0.05MPa, the heating chamber 201 can automatically relieve pressure.

[0086] The heating element of the heating shell 21 is started to slowly raise the temperature in the heating chamber 201 to 550°C.

[0087] The cooling fan 81 is started to provide cooling for the mechanical vibration table 31 so that the temperature of the mechanical vibration table 31 is not too high.

[0088] The target temperature of the heating chamber 201 is set by the control system, and the heating element is adjusted so that the temperature in the heating chamber 201 is stabilized at the target temperature. Since the volume of the argon gas in the heating chamber 201 expands after being heated, it is necessary to always keep the gas outlet pipe 104 open during this process so that the high-temperature argon gas in the heating chamber 201 can leave the heating chamber 201 and the gas pressure in the heating chamber 201 is maintained within the required range.

[0089] The vibration thrust, vibration frequency, amplitude, and vibration time of the mechanical vibration table 31 are set through the control system, and the vibration frequency and vibration time of the ultrasonic vibration generator 32 are set, and the mechanical vibration table 31 and the ultrasonic vibration generator 32 are started in sequence.

[0090] After the vibration is finished, the heating is stopped to allow the temperature of the heating chamber 201 to slowly drop, and at the same time, argon gas is introduced into the heating chamber 201 to maintain the pressure in the heating chamber 201 at 0.05 MPa to prevent the argon gas in the heating chamber 201 from cooling and forming a vacuum.

[0091] The heating device 20 is lifted by the electric push cylinder 50 so that the fuel element 200 leaves the heating chamber 201 , and the fuel element 200 is removed from the holding device 10 , thereby completing the processing of the fuel element 200 .

[0092] Regarding the embodiments of the present application, it should also be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other to obtain new embodiments.

[0093] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A system for processing a fuel element, the fuel element comprising a shell and a plurality of cores disposed in the shell, a cooling medium and a gas, wherein the plurality of cores are located below the liquid level of the cooling medium; characterized in that: The system comprises: a holding device for holding a plurality of fuel elements; A heating device, used for heating the plurality of fuel elements so that the cooling medium of the fuel elements is in a liquid state; The vibrating device is used to drive the retaining device to vibrate, thereby driving the plurality of fuel elements to vibrate, so that the gas inside the liquid cooling medium can escape to above the liquid surface of the cooling medium.

2. The system according to claim 1, characterized in that The vibration device includes a mechanical vibration part, and the mechanical vibration part is used to drive the holding device to vibrate.

3. The system according to claim 2, characterized in that The mechanical vibration part includes a body and a vibration part capable of vibrating relative to the body; The holding device comprises a holding portion and a connecting portion connected to the holding portion, wherein the holding portion is used to hold the plurality of fuel elements, and the connecting portion is used to be connected to the vibrating portion so that the vibrating portion drives the connecting portion and the holding portion to vibrate.

4. The system according to claim 3, characterized in that The holding device further comprises an extension portion, wherein the extension portion is connected to the connection portion; The holding portion comprises a plurality of layers of holding members and a plurality of clamping members, wherein the plurality of layers of holding members are connected to the extending portion, and each of the fuel elements is connected to each layer of the holding members via a clamping member.

5. The system according to claim 4, characterized in that A clamping groove is formed on the radial outer side of the retaining member, and each of the fuel elements is clamped in the clamping groove by the clamping member.

6. The system according to claim 4, characterized in that The holding device further includes a supporting portion connected to the connecting portion, wherein the supporting portion is disposed below the multi-layer holding member, and the plurality of fuel elements are in contact with the supporting portion so as to be supported by the supporting portion.

7. The system according to claim 6, characterized in that The retaining member, the supporting portion, the extending portion and the connecting portion are configured as a hollow structure.

8. The system according to claim 3, characterized in that The heating device is arranged to form a heating chamber with an opening at the bottom; The system further comprises: A mounting plate, disposed on the body, the mounting plate forming a through hole, the connecting portion of the holding device being connected to the vibrating portion of the mechanical vibrating portion through the through hole; A lifting device, disposed on the mounting plate, for driving the heating device to move up and down so that the holding portion is located outside or inside the heating chamber; A sealing device, used for sealing the heating chamber when the lifting device drives the heating device to descend to abut against the sealing device; A gas supply component is used to provide protective gas to the heating chamber.

9. The system according to claim 8, characterized in that The sealing device comprises: A bellows, used to connect the vibration part and the mounting plate; A sealing connection portion is connected to the bellows and is disposed on the mounting plate, and is used for being sealedly connected to the heating device when the lifting device drives the heating device to descend so that the retaining portion is located inside the heating chamber.

10. The system according to claim 1, characterized in that The vibration device further includes an ultrasonic vibration part, and the ultrasonic vibration part is used to drive the holding device to vibrate through ultrasound.

11. A method for processing a fuel element, the method being implemented using the system according to any one of claims 1-10.

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