Self-regulating fuel assembly

Abstract

The present application relates to nuclear reaction technical field, specifically provide a kind of self-regulating fuel assembly, to solve the existing coolant flow distribution structure cannot automatically adjust coolant flow according to demand, thus causing fuel cannot be fully released energy in different service life problems.For this purpose, the self-regulating fuel assembly of the present application includes: energy assembly and support assembly connected;Support assembly includes integrally constructed lower tube base and lower tube pin, and counterweight body is arranged in the inside of lower tube base and lower tube pin, and lower tube base has flow channel hole;Wherein, counterweight body is used to expand or shrink with temperature change, so that the gap of counterweight body and flow channel hole increases or reduces, for controlling coolant flow.When temperature is higher, gap increases, increases coolant flow, when temperature is lower, gap shrinks, reduces coolant flow, realizes the flow of automatically adjusting coolant into energy assembly, so that fuel is fully released energy in different service life.

Description

Technical Field

[0001] This invention relates to the field of nuclear reaction technology, and specifically provides a self-regulating fuel assembly. Background Technology

[0002] Fuel assemblies are indispensable components of a nuclear reactor. They contain the fuel needed for the fission reaction, releasing a large amount of energy and generating heat to produce steam, which drives the turbine to do work and ultimately generate electricity. Therefore, fuel assemblies are crucial for the normal operation of the reactor.

[0003] Fuel assemblies require an appropriate flow rate of coolant to ensure that different locations within the reactor and at different times receive the corresponding coolant flow rates. Generally, the power output in the reactor core area is higher, thus requiring more coolant to remove nuclear heat. Assemblies located at the core edges, however, require limited and appropriately reduced coolant flow rates. During the reactor's lifespan, the initial fuel releases a large amount of heat, which changes or decreases over time due to fuel consumption, requiring varying coolant flow rates. However, conventional coolant flow distribution structures are fixed at the initial fuel assembly manufacturing stage and cannot be automatically adjusted according to demand. This results in the fuel not fully releasing energy throughout its lifespan.

[0004] Accordingly, there is a need in the art for a new self-regulating fuel assembly to address the aforementioned problems. Summary of the Invention

[0005] The present invention aims to solve the above-mentioned technical problems, namely, to solve the problem that the existing coolant flow distribution structure is fixed at the beginning of fuel assembly manufacturing, and cannot automatically adjust the coolant flow according to demand, thus causing the fuel to not fully release energy at different lifespans.

[0006] This invention provides a self-regulating fuel assembly, which includes an energy assembly and a support assembly connected together. The support assembly includes an integrally formed lower tube seat and lower tube foot, and a counterweight disposed inside the lower tube seat and the lower tube foot. The lower tube seat has a flow channel hole. The counterweight is used to expand or contract with temperature changes, so that the gap between the counterweight and the flow channel hole increases or decreases, thereby controlling the coolant flow rate.

[0007] When the above technical solution is adopted, at higher energy component temperatures, the lower tube seat and counterweight expand with increasing temperature, creating a temperature difference that increases the gap between the counterweight and the flow channel orifice, thereby increasing the coolant flow rate and keeping the energy component within the preset temperature range. Conversely, at lower energy component temperatures, the lower tube seat and counterweight shrink with decreasing temperature, creating a temperature difference that reduces the gap between the counterweight and the flow channel orifice, thereby decreasing the coolant flow rate and keeping the energy component within the preset temperature range. This automatic adjustment of the coolant flow rate into the energy component allows the fuel to fully release energy throughout its different lifespans.

[0008] In the preferred embodiment of the self-regulating fuel assembly described above, the lower tube seat is a cylindrical body with a diameter that gradually increases from bottom to top.

[0009] When the above technical solution is adopted, the volume of the lower tube seat is increased to increase the flow of coolant so as to match the size of the lower end of the tube of the energy component, facilitate connection with the tube body, and have better support.

[0010] In the preferred embodiment of the self-regulating fuel assembly described above, the lower pin is a cylindrical body with a guide point at the lower end.

[0011] By adopting the above technical solution, the lower end of the lower tube pin is made into a guide point, which facilitates the insertion of the lower tube pin and improves the installation efficiency.

[0012] In the preferred embodiment of the self-regulating fuel assembly described above, the lower part of the counterweight is a cylinder and is located inside the lower tube foot, the upper part of the counterweight is a cylinder with a gradually increasing diameter from bottom to top and is located inside the lower tube seat, and the upper end of the counterweight is located at the flow channel hole.

[0013] When the above technical solution is adopted, the lower part of the counterweight is set as a cylinder to match the shape of the lower tube pin, and the upper part of the counterweight is set as a cylinder with a gradually increasing diameter to match the shape of the lower part of the lower tube seat, so as to confine the counterweight inside the lower tube pin and the lower tube seat.

[0014] In the preferred embodiment of the self-regulating fuel assembly described above, the counterweight is made of tungsten, and the upper outer wall of the counterweight is provided with a molybdenum material layer.

[0015] When the above technical solution is adopted, the linear expansion coefficient of tungsten and molybdenum is only 1 / 3 to 1 / 4 of that of stainless steel material for the lower tube seat, and they have high thermal conductivity. The temperature change of the fuel assembly is fed back to the gap change, thereby realizing the self-regulation of the flow rate. The density of tungsten and molybdenum is much higher than that of liquid metal coolant. Relying on their own weight, they can overcome the buoyancy of the coolant and impact vibration, and realize the self-support of the fuel assembly.

[0016] In the preferred embodiment of the above self-regulating fuel assembly, the fuel assembly includes a tube body, an upper tube seat, and a fuel rod; the upper end of the tube body is connected to the upper tube seat, the lower end of the tube body is connected to the lower tube seat, the fuel rod is disposed inside the tube body, and the upper end of the fuel rod is connected to the upper tube seat.

[0017] When the above technical solution is adopted, the upper end of the tube body is sealed by the upper tube seat, so that the tube body is in a state of one-end sealing. The upper tube seat is also used to fix the upper end of the fuel rod so that the fuel rod is fixed and avoids shaking. The tube body is used to protect the fuel rod, and at the same time, it is convenient for coolant to enter the interior of the tube body to cool the fuel rod.

[0018] In the preferred embodiment of the self-regulating fuel assembly described above, a support plate is provided at the connection between the lower end of the tube body and the lower tube seat, and the support plate is connected to the lower end of the fuel rod.

[0019] When the above technical solution is adopted, the support plate separates the tube body and the lower tube seat, and is also used to fix the lower end of the fuel rod, making the fuel rod more stable.

[0020] In the preferred embodiment of the self-regulating fuel assembly described above, the support plate has multiple through holes to allow the coolant to enter the interior of the tube for cooling the fuel rods.

[0021] When the above technical solution is adopted, by setting multiple through holes, the coolant can be dispersed into the interior of the tube, so that the coolant enters the tube evenly.

[0022] In the preferred embodiment of the self-regulating fuel assembly described above, the support assembly further includes a flow channel cavity, which is formed between the upper end of the counterweight, the upper inner part of the lower pipe seat, and the support plate; wherein the flow channel cavity and the flow channel hole are connected to each other, so that the coolant can enter the interior of the pipe to regulate the temperature.

[0023] When the above technical solution is adopted, by setting the flow channel cavity, there is a buffer space for the coolant before it enters the tube body, which can ensure that the coolant enters the tube body continuously. At the same time, the flow channel cavity is not filled by the counterweight, which can ensure the flow rate of the coolant entering the flow channel hole.

[0024] In the preferred embodiment of the above-mentioned self-regulating fuel assembly, the fuel assembly further includes a support rod, the upper end of which is connected to the lower part of the support plate, and the lower end of which extends into the flow channel cavity and is inserted into the interior of the counterweight to fix the counterweight.

[0025] When the above technical solution is adopted, the support plate and the counterweight can be connected by setting a support rod, which can also be used to fix the counterweight. This can avoid the problem of the counterweight shaking when the counterweight and the lower tube seat expand. Attached Figure Description

[0026] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0027] Figure 1 This is a cross-sectional side view of a self-regulating fuel assembly according to the present invention;

[0028] Figure 2 Figure 1 is a partially enlarged view of a self-regulating fuel assembly according to the present invention;

[0029] Figure 3 This is a cross-sectional view of the gap expansion of a self-adjusting fuel assembly according to the present invention;

[0030] Figure 4 This is a cross-sectional view of the gap reduction of a self-adjusting fuel assembly according to the present invention.

[0031] List of markers in the diagram:

[0032] 1. Energy component; 11. Tube body; 12. Upper tube seat; 13. Fuel rod; 14. Support plate; 15. Through hole; 16. Support rod;

[0033] 2. Support assembly; 21. Lower tube seat; 22. Counterweight; 23. Lower tube foot; 24. Guide corner; 25. Flow channel hole; 26. Clearance. Detailed Implementation

[0034] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the self-regulating fuel assembly of the present invention and are not intended to limit the scope of protection of the present invention.

[0035] It should be noted that in the description of this invention, terms such as "upper," "lower," "inner," and "outer," indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] Fuel assemblies are indispensable components of a nuclear reactor. They contain the fuel needed for the fission reaction, releasing a large amount of energy and generating heat to produce steam, which drives the turbine to do work and ultimately generate electricity. Therefore, fuel assemblies are crucial for the normal operation of the reactor.

[0038] Fuel assemblies require an appropriate flow rate of coolant to ensure that different locations within the reactor and at different times receive the corresponding coolant flow rates. Generally, the power output in the reactor core area is higher, thus requiring more coolant to remove nuclear heat. Assemblies located at the core edges, however, require limited and appropriately reduced coolant flow rates. During the reactor's lifespan, the initial fuel releases a large amount of heat, which changes or decreases over time due to fuel consumption, requiring varying coolant flow rates. However, conventional coolant flow distribution structures are fixed at the initial fuel assembly manufacturing stage and cannot be automatically adjusted according to demand. This results in the fuel not fully releasing energy throughout its lifespan.

[0039] To address the aforementioned problems, this application provides a self-regulating fuel assembly, which includes an energy component 1 and a support component 2, connected together. The support component 2 includes a lower tube seat 21, a lower tube pin 23, and a counterweight 22. The lower tube seat 21 and the lower tube pin 23 are connected, and the counterweight 22 is disposed inside the lower tube seat 21 and the lower tube pin 23. The lower tube seat 21 has a flow channel hole 25, and the upper end of the counterweight 22 is located within the flow channel hole 25.

[0040] The technical solution provided in this application allows the lower tube seat 21 and the counterweight 22 to expand as the temperature rises, creating a temperature difference that increases the gap 26 between the counterweight 22 and the flow channel hole 25, thereby increasing the coolant flow rate and keeping the energy assembly 1 within a preset temperature range. Conversely, when the temperature of the energy assembly 1 is low, the lower tube seat 21 and the counterweight 22 shrink as the temperature drops, creating a temperature difference that reduces the gap 26 between the counterweight 22 and the flow channel hole 25, thereby decreasing the coolant flow rate and keeping the energy assembly 1 within a preset temperature range. This automatic adjustment of the coolant flow rate into the energy assembly 1 allows the fuel to fully release energy throughout its different lifespans.

[0041] First refer to Figure 1-4 This invention provides a self-regulating fuel assembly, which includes an energy component 1 and a support component 2 connected to each other. The support component 2 generally includes an integrally formed lower tube seat 21 and lower tube foot 23, and a counterweight 22 disposed inside the lower tube seat 21 and lower tube foot 23. The lower tube seat 21 has a flow channel hole 25. The counterweight 22 expands or contracts with temperature changes, thereby increasing or decreasing the gap 26 between the counterweight 22 and the flow channel hole 25, to control the coolant flow rate.

[0042] Thus, when the temperature of energy component 1 is high, the lower tube seat 21 and the counterweight 22 expand as the temperature rises, creating a temperature difference that increases the gap 26 between the counterweight 22 and the flow channel hole 25, thereby increasing the coolant flow rate and keeping energy component 1 within the preset temperature range. When the temperature of energy component 1 is low, the lower tube seat 21 and the counterweight 22 shrink as the temperature drops, creating a temperature difference that decreases the gap 26 between the counterweight 22 and the flow channel hole 25, thereby reducing the coolant flow rate and keeping energy component 1 within the preset temperature range. This automatic adjustment of the coolant flow rate into energy component 1 allows the fuel to fully release energy throughout its different lifespans.

[0043] The self-regulating fuel assembly of this application can be used in various reactors. Taking a lead-based reactor as an example, the coolant is a lead-bismuth alloy, the base flow rate of the fuel assembly is approximately 40 kg / s, the flow velocity does not exceed 2 m / s, and the flow channel area is 2000 mm². 2 The diameter of the lower tube seat 21 is 150mm, the component temperature change is 100℃, and the difference in the linear expansion coefficients between tungsten / molybdenum metal and 316L stainless steel is 13×10⁻⁶. -6 K -1 Based on this calculation, the flow area will change by 100mm. 2 That is, for every 100°C change in the core assembly temperature, the flow area of ​​the flow channel 25 will change by about 5%, resulting in a flow self-regulation of about 5%.

[0044] See Figure 1 and Figure 2 In the preferred embodiment of the above-described self-regulating fuel assembly, with Figure 1Taking the direction shown as an example, the energy component 1 is located at the top, and the support component 2 is located at the bottom, and the two are fixedly connected. The lower tube seat 21 and the lower tube foot 23 can also be separately constructed and connected by welding, depending on the actual application requirements. The upper end of the counterweight 22 is located in the middle of the lower tube seat 21, which can block one-half or one-third of the flow channel hole 25. The upper outer wall of the counterweight 22 and the inner wall of the lower tube seat 21 can be fitted together or have a certain gap 26. The lower outer wall of the counterweight 22 and the inner wall of the lower tube foot 23 can be fitted together or have a certain gap, depending on the actual requirements, and this application does not impose any restrictions. The flow channel hole 25 is a plurality of holes equally spaced on the circumference of the lower tube seat 21 for coolant entry.

[0045] See Figure 1 and Figure 2 In the preferred embodiment of the above-described self-regulating fuel assembly, with Figure 1 Taking the direction shown as an example, the lower tube seat 21 is a cylindrical body with a gradually increasing diameter from bottom to top, which is used to increase the volume of the lower tube seat 21 to increase the flow of coolant so as to match the size of the lower end of the tube body 11 of the energy component 1, facilitate connection with the tube body 11, and have good support force.

[0046] See Figure 1 In the preferred embodiment of the self-adjusting fuel assembly described above, the lower pin 23 is a cylindrical body with a guide tip 24 at the lower end. By making the lower end of the lower pin 23 into a guide tip 24, it is easier to insert the lower pin 23 and improve the installation efficiency.

[0047] Alternatively, the lower end of the lower pin 23 may also be a plane.

[0048] As one possible implementation, the mounting hole that can be inserted into the lower end of the lower pin 23 can be a cylindrical mounting hole or a cylindrical mounting hole with a pointed corner. Both cylindrical mounting holes and cylindrical mounting holes with pointed corners can be inserted into the lower end of the lower pin 23, making the connection convenient and quick.

[0049] See Figure 1 Specifically, with Figure 1 Taking the direction shown as an example, the lower part of the counterweight 22 is a cylinder and is located inside the lower pin 23. The upper part of the counterweight 22 is a cylinder with a gradually increasing diameter from bottom to top and is located inside the lower tube seat 21. The upper end of the counterweight 22 is located at the flow channel hole 25. By setting the lower part of the counterweight 22 to be a cylinder to match the shape of the lower pin 23, and setting the upper part of the counterweight 22 to be a cylinder with a gradually increasing diameter to match the shape of the lower part inside the lower tube seat 21, the counterweight 22 is confined inside the lower pin 23 and the lower tube seat 21.

[0050] In the preferred embodiment of the self-regulating fuel assembly described above, the counterweight 22 is made of tungsten, and a molybdenum layer is provided on the upper outer wall of the counterweight 22. Since the linear expansion coefficients of tungsten and molybdenum in the counterweight 22 are only 1 / 3 to 1 / 4 of those in the stainless steel structural material of the lower tube seat 21, and they have high thermal conductivity, the temperature changes of the fuel assembly are fed back to the gap 26, thereby achieving self-regulation of the flow rate. Specifically, when the fuel assembly is located in the core region or experiences abnormal fluctuations, the fuel assembly temperature rises, the gap 26 between the counterweight 22 and the lower tube seat 21 or lower tube foot 23 increases, the coolant flow area increases and the flow resistance decreases, allowing more coolant to pass through the fuel assembly and achieving a temperature drop and balance. Since the density of tungsten and molybdenum is much higher than that of liquid metal coolant, their own weight can overcome the buoyancy of the coolant and impact vibrations, enabling the fuel assembly to stand upright. Simultaneously, the counterweight 22, located at the bottom of the fuel assembly, lowers the center of gravity of the fuel assembly, thus stabilizing it.

[0051] This fuel assembly can achieve self-balancing of flow distribution throughout its lifespan. For example, taking the assembly in the core center region as an example, in the early stage of its lifespan, the power peak factor of this assembly region is high and the fuel assembly temperature is high. At this time, the gap 26 at the counterweight 22 is large, which can automatically increase the coolant flow at this fuel assembly. At the end of its lifespan, due to the rapid consumption of fuel, the power peak factor of this fuel assembly region is low and the fuel assembly temperature decreases. At this time, the gap 26 at the counterweight 22 is reduced or even closed, which can automatically reduce the coolant flow at this fuel assembly.

[0052] In this embodiment, tungsten is a non-ferrous metal. Metals are generally classified into two main categories based on their color and properties: ferrous metals and non-ferrous metals. Ferrous metals mainly refer to iron, manganese, chromium, and their alloys, such as steel, pig iron, ferroalloys, and cast iron. Metals other than ferrous metals are called non-ferrous metals, and tungsten falls into this category. Non-ferrous alloys generally have higher strength and hardness than ferrous metals, higher electrical resistance, and a smaller temperature coefficient of resistance, exhibiting excellent comprehensive mechanical properties. Therefore, as a non-ferrous metal, tungsten has very high strength and hardness. Due to these characteristics, tungsten carbide, with its high hardness and wear resistance, is widely used in cutting tools and mining tools.

[0053] See Figure 1 and Figure 2In the preferred embodiment of the self-regulating fuel assembly described above, the fuel assembly 1 generally includes a tube body 11, an upper tube seat 12, and a fuel rod 13. The upper end of the tube body 11 is connected to the upper tube seat 12, and the lower end of the tube body 11 is connected to the lower tube seat 23. The fuel rod 13 is disposed inside the tube body 11, and its upper end is connected to the upper tube seat 12. The upper tube seat 12 seals the upper end of the tube body 11, creating a one-end sealed state. The upper tube seat 12 also serves to fix the upper end of the fuel rod 13 in place, preventing it from shaking. The tube body 11 protects the fuel rod 13 and facilitates the entry of coolant into the interior of the tube body 11 to cool the fuel rod 13.

[0054] As one possible implementation, the upper end of the pipe body 11 and the upper pipe seat 12 can be connected in various ways, such as: threaded connection, which facilitates disassembly, maintenance, and replacement of the pipe body 11 and the upper pipe seat 12; or welding connection, which makes the connection between the pipe body 11 and the upper pipe seat 12 more secure. There are multiple fuel rods 13, which are equidistantly arranged inside the pipe body 11, with a certain gap between adjacent fuel rods 13 for coolant flow. The multiple fuel rods 13 are of the same size. The fuel rods 13 and the upper pipe seat 12 can be connected in various ways, such as: threaded connection, which facilitates disassembly, maintenance, and replacement of the upper end of the fuel rods 13 and the upper pipe seat 12; or welding connection, which makes the connection between the fuel rods 13 and the upper pipe seat 12 more secure; or snap-fit ​​connection, which facilitates disassembly, maintenance, and replacement of the upper end of the fuel rods 13 and the upper pipe seat 12.

[0055] It should be noted that the specific number, size, and type of fuel stored inside the fuel rods 13 in this application are not limited in this application, and the specific details shall be subject to actual use.

[0056] Optionally, the tube body 11 is cylindrical, and its material can be selected according to actual needs, such as stainless steel. The upper tube seat 12 is cylindrical, and its material can be selected according to actual needs, such as stainless steel. The tube body 11 and the upper tube seat 12 can also be integrally machined using a mold, resulting in optimal robustness and sealing performance.

[0057] See Figure 1 and Figure 2 In the preferred embodiment of the self-adjusting fuel assembly described above, a support plate 14 is provided at the connection between the lower end of the tube body 11 and the lower tube seat 21, and the support plate 14 is connected to the lower end of the fuel rod 13. The support plate 14 separates the tube body 11 and the lower tube seat 21, and at the same time serves to fix the lower end of the fuel rod 13, making the fuel rod 13 more stable.

[0058] Optionally, the support plate 14 is generally circular, and its cross-section can be adapted to that of the tube 11.

[0059] Continue reading Figure 1 and Figure 2 In the preferred embodiment of the self-regulating fuel assembly described above, the support plate 14 has a plurality of through holes 15 to allow coolant to enter the interior of the tube 11 for cooling the fuel rods 13. By providing a plurality of through holes 15, the coolant can be dispersed into the interior of the tube 11, resulting in uniform coolant flow inside the tube 11.

[0060] Optionally, the multiple through holes 15 are set at equal intervals.

[0061] As one possible implementation, a portion of the through holes 15 closer to the fuel rod 13 has a slightly larger size, which can increase the coolant flow rate in that area, thus accelerating the cooling of that area. Conversely, a portion of the through holes 15 farther from the fuel rod 13 has a slightly smaller size, which can reduce the coolant flow rate in that area, thus slowing down the cooling of that area. This allows for more even cooling inside the tube body 11.

[0062] Continue reading Figure 1 and Figure 2 In the preferred embodiment of the self-regulating fuel assembly described above, the support assembly 2 generally further includes a flow channel cavity 26, which is formed by the upper end of the counterweight 22, the upper inner part of the lower tube seat 21, and the support plate 14. The flow channel cavity 26 communicates with the flow channel hole 25 and the through hole 15 to allow coolant to enter the tube body 11 to regulate temperature. By providing the flow channel cavity 26, a buffer space is provided for the coolant before it enters the tube body 11, ensuring uninterrupted coolant flow into the tube body 11. Simultaneously, since the flow channel cavity 26 is not filled by the counterweight 22, the flow rate of coolant entering the flow channel hole 25 is guaranteed.

[0063] Continue reading Figure 1 and Figure 2 In the preferred embodiment of the self-adjusting fuel assembly described above, the fuel assembly 1 generally further includes a support rod 16. The upper end of the support rod 16 is connected to the lower part of the support plate 14, and the lower end of the support rod 16 extends into the flow channel cavity 26 and is inserted into the interior of the counterweight 22 to fix the counterweight 22. By providing the support rod 16, the support plate 14 and the counterweight 22 can be connected, and the counterweight 22 can be fixed. This avoids the problem of the counterweight 22 shaking when the counterweight 22 and the lower tube seat 21 expand.

[0064] Specifically, the support rod 16 is a metal rod. The upper end of the support rod 16 and the lower end of the support plate 14 can be welded or threaded. The lower end of the support rod 16 extends into the flow channel cavity 26 and is embedded in the interior of the counterweight 22 for fixing the counterweight 22.

[0065] As one possible implementation, the lower end of the support rod 16 may also be provided with an anti-detachment structure, which is of the first style and / or the second style.

[0066] The first style is: the diameter of the section of the support rod 16 inserted into the counterweight 22 gradually increases from top to bottom, so as to avoid gaps between the counterweight 22 and the support rod 16 after the counterweight 22 expands, which would cause the connection between the counterweight 22 and the support rod 16 to be not firm enough.

[0067] The second style is: a horizontal bar is welded to the lower end of the support rod 16 and is embedded in the interior of the counterweight 22 along with the lower end of the support rod 16, so as to avoid gaps between the counterweight 22 and the support rod 16 after the counterweight 22 expands, which would cause the connection between the counterweight 22 and the support rod 16 to be not firm enough.

[0068] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A self-regulating fuel assembly, characterized in that, The fuel assembly includes an energy component and a support component connected together; The support assembly includes an integrally formed lower tube seat and lower tube foot, and a counterweight disposed inside the lower tube seat and lower tube foot. The lower tube seat has a flow channel hole and is made of stainless steel, while the counterweight is made of tungsten. The counterweight is used to expand or contract with temperature changes, so that the gap between the counterweight and the flow channel hole increases or decreases, thereby controlling the coolant flow rate. Specifically, when the energy component temperature is high, the lower tube seat and the counterweight expand as the temperature rises, creating a difference in size, which increases the gap between the counterweight and the flow channel hole to increase the coolant flow rate; when the energy component temperature is low, the lower tube seat and the counterweight shrink as the temperature drops, creating a difference in size, which reduces the gap between the counterweight and the flow channel hole to decrease the coolant flow rate.

2. The self-regulating fuel assembly according to claim 1, characterized in that, The lower tube seat is a conical cylinder whose diameter gradually increases from bottom to top.

3. The self-regulating fuel assembly according to claim 2, characterized in that, The lower pin is a cylindrical body with a guide point at the lower end.

4. The self-regulating fuel assembly according to any one of claims 1-3, characterized in that, The lower part of the counterweight is a cylinder and is located inside the lower tube foot. The upper part of the counterweight is a tapered column with a gradually increasing diameter from bottom to top and is located inside the lower tube seat. The upper end of the counterweight is located at the flow channel hole.

5. The self-regulating fuel assembly according to claim 4, characterized in that, The upper outer wall of the counterweight is provided with a molybdenum material layer.

6. The self-regulating fuel assembly according to claim 1, characterized in that, The fuel assembly includes a tube body, an upper tube seat, and fuel rods; The upper end of the tube is connected to the upper tube seat, the lower end of the tube is connected to the lower tube seat, the fuel rod is disposed inside the tube, and the upper end of the fuel rod is connected to the upper tube seat.

7. The self-regulating fuel assembly according to claim 6, characterized in that, A support plate is provided at the connection between the lower end of the tube body and the lower tube seat, and the support plate is connected to the lower end of the fuel rod.

8. The self-regulating fuel assembly according to claim 7, characterized in that, The support plate has multiple through holes to allow the coolant to enter the interior of the tube for cooling the fuel rods.

9. The self-regulating fuel assembly according to claim 8, characterized in that, The support assembly also includes a flow channel cavity, which is formed by the upper end of the counterweight, the upper inner part of the lower tube seat, and the support plate. The flow channel cavity and the flow channel hole are connected to each other, so that the coolant can enter the interior of the tube to regulate the temperature.

10. The self-regulating fuel assembly according to claim 9, characterized in that, The fuel assembly also includes a support rod, the upper end of which is connected to the lower part of the support plate, and the lower end of which extends into the flow channel cavity and is inserted into the interior of the counterweight to fix the counterweight.

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