Liquid lithium-lead self-cooled blanket with low mhd pressure drop

Abstract

The application discloses a liquid lithium-lead self-cooling cladding with low MHD pressure drop, and relates to the technical field of fusion reactor engineering; comprising: an outer cladding, which comprises an outer cladding circumferential arc-shaped main flow channel; the outer cladding circumferential arc-shaped main flow channel comprises a first wall region flow channel and a tritium breeding zone flow channel arranged in sequence from inside to outside along the radial direction; an inner cladding, which comprises an inner cladding circumferential arc-shaped main flow channel; wherein the flow direction of the outer cladding circumferential arc-shaped main flow channel and the inner cladding circumferential arc-shaped main flow channel is parallel or tends to be parallel to the magnetic line direction of the circumferential magnetic field of the fusion reactor; the outer cladding circumferential arc-shaped main flow channel and the inner cladding circumferential arc-shaped main flow channel are provided with flow channel inserts at the turning positions of the inlet and the outlet; and the polar height a of the outer cladding circumferential arc-shaped main flow channel and the inner cladding circumferential arc-shaped main flow channel is greater than the radial width b; the cladding has the advantages of low MHD pressure drop, simple structure, small processing difficulty and easy realization in engineering.

Description

Technical Field

[0001] This invention relates to the field of fusion reactor engineering technology, and more specifically to a liquid lithium-lead self-cooling cladding with low MHD pressure drop. Background Technology

[0002] Tritium breeder blankets are a key component of fusion reactors, playing a crucial role in shielding neutron radiation, tritium breeding, and the extraction and conversion of nuclear fusion energy. Depending on the breeder, tritium breeder blankets can be classified as liquid or solid blankets. Liquid blankets typically use liquid lithium metal or lithium-lead alloys as breeders. Liquid blankets offer advantages such as low operating pressure, simple structure, high thermal conversion efficiency, and the ability to extract tritium online, making them a primary option for tritium production in the fusion community. As an advanced tritium breeder blanket technology, it is considered one of the most competitive key technologies for achieving fusion energy.

[0003] For the liquid blanket of magnetically confined fusion reactors, the strong magnetic field used to confine the plasma can reach up to 10T, generating a very strong magnetohydrodynamic (MHD) effect in the liquid metal. When the liquid metal moves in a strong magnetic field, it generates a Lorentz force that hinders its forward flow, resulting in a very large MHD pressure drop, typically more than ten thousand times that of ordinary hydraulic pressure drop. This remains a key problem to be solved. The MHD pressure drop increases additional pump power consumption, reduces economic competitiveness, and induces unbearable stresses in the piping structure materials, thus raising the issue of the engineering feasibility of liquid blanket MHD pressure drop. Research results indicate that the MHD pressure drop in the liquid blanket should be limited to within 2MPa, which poses a significant challenge to the design of the liquid blanket.

[0004] Currently, three different types of liquid coatings have been proposed internationally: self-cooled, dual-cooled, and individually cooled liquid coatings.

[0005] The self-cooled liquid cladding uses liquid metal as both a tritium breeder and a coolant, greatly simplifying the cladding structure. However, it requires a high flow rate to meet the cooling requirements (around 1 m / s). This high flow rate leads to a very large MHD pressure drop, which is usually difficult to meet the 2 MPa pressure drop limit. To reduce the MHD pressure drop, the concept of a dual-cooled lithium-lead cladding was proposed. This scheme uses high-temperature, high-pressure helium to cool the first wall and structural materials, while the tritium breeding region is self-cooled by liquid lithium-lead. The average flow rate of the liquid lithium-lead is about 0.1 m / s to meet the cooling requirements of the breeding region. To reduce the MHD pressure drop in the poloidal flow channel, a high-insulation, low-thermal-conductivity silicon carbide composite material flow channel insert is used to reduce the pressure drop and increase the temperature of the lithium-lead at the flow channel outlet, thereby improving the thermal conversion efficiency of the cladding. Due to the use of helium cooling and silicon carbide flow channel inserts, the structure of the double-cold cladding is very complex. Furthermore, the preparation and processing technology of composite silicon carbide flow channel inserts is still immature, and many problems remain to be solved before its large-scale application. To reduce the MHD pressure drop of the liquid cladding, the EU proposed the concept of separately cooling the liquid cladding. In this scheme, the liquid lithium-lead flows very slowly (approximately 1 mm / s), and the entire cladding, including the tritium breeding region, is cooled by high-temperature, high-pressure helium or water. The liquid lithium-lead is only slowly circulated out of the fusion reactor for online tritium production and does not have a cooling function. Due to the slow lithium-lead flow rate, the MHD pressure drop in the breeding region is small, but at the inlet and outlet manifolds, due to the higher flow rate, the MHD pressure drop is still large, requiring insulating coatings and other methods to reduce the pressure. The structure of separately cooling the lithium-lead cladding is also very complex, with low thermal conversion efficiency and potentially serious tritium retention problems.

[0006] Comparing the three types of liquid cladding, self-cooled cladding has the simplest structure and the highest thermal conversion efficiency, making it the ultimate research and development goal for liquid cladding. However, its development is also the most challenging, with the high MHD pressure drop caused by the large flow rate being the main obstacle to its development. Dual-cooled and individually cooled liquid cladding structures are complex, and the mainstream of liquid lithium-lead flows along the polar direction, interacting with the strong circumferential magnetic field to generate a very large MHD pressure drop. Furthermore, their thermal conversion efficiency is far lower than that of self-cooled cladding, especially helium-cooled or water-cooled lithium-lead cladding, which has a thermal conversion efficiency of only about 33%, failing to meet the long-term economic requirements of fusion power plants. Therefore, reducing the MHD pressure drop of liquid cladding through engineering-feasible methods has become a crucial issue that urgently needs to be addressed in the development of liquid cladding. Summary of the Invention

[0007] This invention aims to address the technical problems of high MHD (Mean Hardness Displacement) pressure drop, complex structure, and difficult processing of existing liquid cladding. The goal is to provide a self-cooled liquid lithium-lead cladding with low MHD pressure drop. By combining a circumferential arc-shaped flow channel, flow channel inserts only at the inlet and outlet bends of the circumferential arc-shaped flow channel, and a large aspect ratio of the flow channel, the MHD pressure drop of the entire cladding module is significantly reduced. Furthermore, its structure is much simpler than that of dual-cooling and single-cooling claddings, and it is easier to manufacture, meeting the compact requirements of small fusion reactors. It offers advantages such as low MHD pressure drop, simple structure, easy processing, and ease of engineering implementation.

[0008] The present invention is achieved through the following technical solution.

[0009] A liquid lithium-lead self-cooling cladding with low MHD voltage drop, comprising: The outer cladding layer includes an outer cladding layer circumferential arc-shaped main channel, wherein the outer cladding layer circumferential arc-shaped main channel includes a first wall region channel and a tritium breeding region channel arranged radially from the inside to the outside; The inner cladding layer includes the inner cladding layer circumferential arc-shaped main channel; Among them, the flow direction of the outer cladding circumferential arc-shaped main channel and the inner cladding circumferential arc-shaped main channel is parallel or nearly parallel to the magnetic field lines of the fusion reactor circumferential magnetic field. The outer cladding circumferential arc-shaped main channel and the inner cladding circumferential arc-shaped main channel are equipped with flow channel inserts at the inlet and outlet bends. The polar height 'a' of the outer cladding circumferential arc-shaped main channel and the inner cladding circumferential arc-shaped main channel is greater than the radial width 'b'.

[0010] This invention reduces MHD voltage drop by designing a unique flow channel arrangement, which has the advantages of low MHD voltage drop, simple structure, low processing difficulty, and easy engineering implementation.

[0011] When the magnetic field lines of the applied magnetic field are aligned with the mainstream direction of the liquid lithium-lead, no Lorentz resistance is generated to impede its forward flow. Under this condition, the MHD pressure drop is negligible, meaning it is primarily a hydraulic pressure drop. For magnetically confined fusion reactors, the main magnetic fields are circumferential and poloidal. The poloidal magnetic field is much smaller than the circumferential field, approximately one-tenth its strength. Therefore, this invention reduces the MHD pressure drop in the mainstream direction by arranging the mainstream pipes of the liquid metal in a direction parallel to the circumferential magnetic field of the fusion reactor. Furthermore, this invention provides flow channel inserts at the bends of the inlet and outlet of the circumferential arc-shaped mainstream channels of the outer cladding and the inner cladding, but does not provide flow channel inserts within the arc-shaped flow channels. This effectively reduces the three-dimensional MHD pressure drop at the bends, greatly simplifies the structure, and makes it easier to manufacture, meeting the compact requirements of small fusion reactors. Simultaneously, the cross-sectional characteristics of the flow channels have a large aspect ratio, meaning the height 'a' of the flow channel along the poloidal direction of the fusion reactor is greater than the width 'b' along the radial direction, thus reducing the MHD pressure drop caused by the poloidal magnetic field of the fusion reactor.

[0012] In summary, this invention significantly reduces the MHD voltage drop of the entire cladding module by combining three factors: setting a circumferential arc-shaped flow channel, setting flow channel plugs at the inlet and outlet bends of the circumferential arc-shaped flow channel, and setting a large aspect ratio of the flow channel.

[0013] Furthermore, the flow velocity in the first wall region is greater than that in the tritium breeding region. The high flow rate and average velocity in the first wall region meet the cooling requirements of the first wall, while the relatively low flow rate and average velocity in the tritium breeding region meet the cooling requirements of the relatively small neutron nuclei in this region and are beneficial to improving the tritium breeding rate.

[0014] Furthermore, within the circumferential arc-shaped main channel of the outer cladding layer, multiple branch channels are arranged radially side-by-side, with each branch channel having a number greater than 2. Depending on the required radius of the fusion reactor and the tritium breeding rate, the number of branch channels in the first wall region channel and the tritium breeding region channel can be set as needed. The number of branch channels in the first wall region channel is 2-4, while the number of branch channels in the tritium breeding region channel is 2-8.

[0015] Furthermore, the branch channels within the circumferential arc-shaped main channel of the outer cladding layer are connected at their inlets to the radially arranged outer cladding layer flow distribution pipe, and at their outlets to the outer cladding layer outflow summary pipe. The outer cladding layer flow distribution pipe is used to distribute the liquid lithium-lead entering the circumferential arc-shaped main channel of the outer cladding layer into branch channels, with some entering the first wall region channel and some entering the tritium breeding region channel, and then the liquid lithium-lead flows out from the outer cladding layer outflow summary pipe. Each branch channel is equipped with a silicon carbide flow channel insert at the connection between its inlet and the outer cladding layer flow distribution pipe, and at the connection between its outlet and the outer cladding layer outflow summary pipe.

[0016] In this process, because the liquid lithium-lead undergoes a change from radial to circumferential direction when entering the outer cladding flow distribution pipe and from a direction perpendicular to the magnetic field lines to a direction parallel to the magnetic field lines, a significant three-dimensional MHD pressure drop is generated. Therefore, silicon carbide flow channel inserts are used at the inlet and outlet bends to reduce this three-dimensional pressure drop. Silicon carbide flow channel inserts are applied at all bends in both the inner and outer cladding pipes. The silicon carbide flow channel inserts are made of SiC with silicon carbide fibers. f The SiC composite material ensures its structural strength and good resistance to lithium and lead corrosion.

[0017] Furthermore, the width of the flow channels from the first wall region to the tritium breeding region increases radially. The branch flow channels in the first wall region have smaller cross-sectional dimensions, with a radial width between 20mm and 100mm, to ensure a high flow velocity of liquid lithium-lead in the first wall region (average velocity approximately 1m / s) to cool the first wall region with its high heat load. The radial thickness of the entire first wall region is between 100mm and 300mm. For the branch flow channels in the tritium breeding region, since the neutron volumetric nuclear heat is much smaller than that in the first wall region, the cross-sectional dimensions of the branch flow channels are relatively larger, with a radial width between 60mm and 200mm. The flow velocity of liquid lithium-lead in this region is relatively low (average velocity approximately 0.1m / s) to cool the tritium breeding region while simultaneously circulating lithium-lead out of the fusion reactor. The radial thickness of the entire tritium breeding region is between 200mm and 1000mm, and the specific thickness can be adjusted according to the tritium breeding rate requirements.

[0018] Furthermore, the inlet of the circumferential arc-shaped main channel of the outer cladding is higher than the outlet in the extreme upward direction, thereby ensuring that liquid lithium lead can flow out of the cladding channel by gravity during reactor shutdown. Each branch channel is equipped with a silicon carbide channel insert at the connection between the inlet and the outer cladding flow distribution pipe, and at the connection between the outlet and the outer cladding outflow collection pipe.

[0019] Furthermore, the inner cladding circumferential arc-shaped main channel has multiple branch channels arranged side-by-side along the polar direction, with a number greater than two. There are two designs for the inner cladding circumferential arc-shaped main channel: one where multiple branch channels arranged side-by-side along the polar direction each flow out after approximately 360 degrees of circumferential flow, with an average flow velocity between 0.2 m / s and 0.5 m / s; the other where only one large spiral circumferential main channel is provided, with liquid lithium-lead spiraling downwards along the inclined circumferential main channel and finally flowing out through the bottom outlet, with an average flow velocity between 0.2 m / s and 1 m / s.

[0020] Furthermore, the branch channels of the inner cladding circumferential arc-shaped main channel are connected to the radially arranged inner cladding flow distribution pipe at the inlet, and to the inner cladding outflow collection pipe at the outlet. Each branch channel is equipped with a silicon carbide flow channel insert at the connection point between its inlet and the inner cladding flow distribution pipe, and at the connection point between its outlet and the inner cladding outflow collection pipe.

[0021] In this process, because the liquid lithium-lead undergoes a 90° turn from polar to circumferential direction as it enters the inner cladding flow distribution pipe into the inner cladding circumferential main channel, changing from a direction perpendicular to the magnetic field lines to a direction parallel to the magnetic field lines, a significant three-dimensional MHD pressure drop is generated. Therefore, silicon carbide flow channel inserts are used at the inlet and outlet bends to reduce this three-dimensional pressure drop. Silicon carbide flow channel inserts are applied at all bends in both the inner and outer cladding pipes. The silicon carbide flow channel inserts are made of SiC with silicon carbide fibers. fThe SiC composite material ensures its structural strength and good resistance to lithium and lead corrosion.

[0022] Furthermore, in both the outer and inner cladding circumferential arc-shaped main flow channels, the ratio of the poloidal height *a* to the radial width *b* of the branch channels is between 2 and 8. The main flow channel, along the direction of the circumferential magnetic field lines, has a cross-sectional characteristic of a large aspect ratio; that is, the inner diameter height of the pipe along the fusion reactor's poloidal direction is greater than its radial width, in order to reduce the MHD pressure drop caused by the fusion reactor's poloidal magnetic field. Its aspect ratio is between 2 and 8, with the specific value determined based on the requirement to reduce the MHD pressure drop.

[0023] Furthermore, the inner cladding circumferential arc-shaped main channel is a spiral circumferential flow channel extending along the polar direction.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects.

[0025] 1. This invention reduces MHD pressure drop by designing a unique flow channel layout. By setting a circumferential arc flow channel, placing flow channel inserts only at the inlet and outlet bends of the circumferential arc flow channel, and setting a large aspect ratio of the flow channel, the combination of these three factors greatly reduces the MHD pressure drop of the entire blanket module. At the same time, its structure is much simpler than that of dual-cooling and single-cooling blankets, and it is easier to process and manufacture. It can meet the compact requirements of small fusion reactors and has the advantages of low MHD pressure drop, simple structure, low processing difficulty, and easy engineering implementation.

[0026] 2. The present invention applies silicon carbide flow channel inserts only at the flow channel bends, thus the cladding scheme has a high degree of engineering maturity.

[0027] 3. The present invention has a large flow rate and average velocity in the flow channel in the first wall region, which can meet the cooling requirements of the first wall, while the flow rate and average velocity in the flow channel in the tritium breeding region are relatively small, which can meet the cooling requirements of the relatively small neutron nucleus heat in this region and is conducive to improving the tritium breeding rate.

[0028] 4. In this invention, the inlet of the circumferential arc-shaped main channel of the outer cladding is higher than the outlet in the polar direction, thereby ensuring that liquid lithium lead can flow out of the cladding channel by its own gravity during reactor shutdown.

[0029] 5. The inner cladding circumferential arc-shaped main channel of the present invention can be designed as a large spiral circumferential main channel. This spiral circumferential channel extends along the polar direction and has only one inlet and one outlet. This design can avoid the high MHD pressure drop problem caused by the large average flow velocity of the inlet and outlet junction pipe in multiple annular channel structures.

[0030] 6. The cladding of the present invention adopts a modular design along the polar direction. In the current modular design concept of cladding, it is difficult for liquid lithium lead to flow out of the cladding channel completely. After the reactor is shut down, the lithium lead cools and solidifies, blocking the cladding channel and making it difficult to restart the cladding after the reactor is shut down. However, the channel structure designed in the present invention can drain the liquid lithium lead in the cladding module, thereby making it quick and convenient to restart the cladding after the reactor is shut down.

[0031] 7. The cladding material of the present invention can be ODS steel, which will significantly improve the thermal conversion efficiency by about 45%, and a higher tritium growth rate can be obtained by increasing the radial thickness of the cladding, i.e. the size of the tritium growth region. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 A schematic diagram of a liquid lithium-lead self-cooling cladding with low MHD voltage drop; Figure 2 A schematic diagram of the vertical polarity flow channel cross-section of a self-cooled liquid lithium-lead cladding with low MHD pressure drop; Figure 3 A schematic diagram of the flow channel cross-section at the inlet of the outer cladding layer and the bend in the flow direction; Figure 4 This is a schematic diagram of the inlet and outlet flow channels of the inner cladding. Figure 5 This is a schematic diagram of a spiral inner cladding structure; Figure 6 This is a top view of the spiral inner cladding. Figure 7 This is a schematic diagram of the cross-section of the circumferential arc-shaped main channel perpendicular to the circumferential flow channel.

[0033] The attached diagram shows the markings and corresponding component names: 1-Outer cladding flow distribution pipe one, 11-Outer cladding branch flow channel inlet pipe one, 12-Outer cladding branch flow channel inlet pipe two, 2-Outer cladding flow distribution pipe two, 21-Outer cladding branch flow channel inlet pipe three, 22-Outer cladding branch flow channel inlet pipe four, 23-Outer cladding flow channel insert, 3-Outer cladding circumferential arc-shaped main flow channel, 31-Outer cladding branch flow channel one, 32-Outer cladding branch flow channel two, 33-Outer cladding branch flow channel three, 34-Outer cladding branch flow channel four, 4-Outer cladding outflow collection pipe, 5-Plasma, 6-Inner cladding 7-Inner cladding flow distribution pipe, 71-Inner cladding flow channel insert one, 72-Inner cladding flow channel insert socket one, 73-Inner cladding flow distribution inlet branch pipe one, 74-Inner cladding flow channel insert socket two, 75-Inner cladding flow distribution inlet branch pipe two, 8-Inner cladding outflow summary pipe, 81-Inner cladding flow channel insert two, 82-Inner cladding flow channel insert socket three, 83-Inner cladding outflow outlet branch pipe one, 84-Inner cladding flow channel insert four, 85-Inner cladding outflow outlet branch pipe two, 9-First wall tungsten tile. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0035] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, circuits, materials, or methods have not been specifically described in order to avoid obscuring the invention.

[0036] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] In the description of this invention, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this application is usually placed in when in use, or the orientation or positional relationship that is commonly understood by those skilled in the art. It is only for the convenience of describing this application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.

[0038] Meanwhile, the terms "set up," "assemble," "connect," and "link" 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 or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] Example 1 A liquid lithium-lead self-cooling cladding with low MHD voltage drop, see [link to relevant documentation]. Figure 1-6 ,include: The outer cladding layer includes an outer cladding layer circumferential arc-shaped main channel 3, wherein the outer cladding layer circumferential arc-shaped main channel 3 includes a first wall region channel and a tritium breeding region channel arranged radially from the inside to the outside; The inner cladding layer includes the inner cladding layer circumferential arc-shaped main channel 6; Among them, the flow direction of the outer cladding circumferential arc-shaped main channel 3 and the inner cladding circumferential arc-shaped main channel 6 is parallel or nearly parallel to the magnetic field lines of the fusion reactor circumferential magnetic field. The outer cladding circumferential arc-shaped main channel 3 and the inner cladding circumferential arc-shaped main channel 6 are provided with flow channel inserts at the inlet and outlet bends. The polar height a of the outer cladding circumferential arc-shaped main channel 3 and the inner cladding circumferential arc-shaped main channel 6 is greater than the radial width b.

[0040] This invention reduces MHD voltage drop by designing a unique flow channel arrangement, which has the advantages of low MHD voltage drop, simple structure, low processing difficulty, and easy engineering implementation.

[0041] When the magnetic field lines of the applied magnetic field are in the same direction as the main flow of liquid lithium lead, there will be no Lorentz resistance to hinder its forward flow. Under this condition, the MHD pressure drop is almost negligible, that is, the main pressure drop is hydraulic. For magnetically confined fusion reactors, the main magnetic fields include circumferential and poloidal magnetic fields. The poloidal magnetic field is much smaller than the circumferential field, about one-tenth of its strength. Therefore, this invention reduces the MHD pressure drop in the mainstream direction by arranging the mainstream pipes of liquid metal in a direction parallel to the circumferential magnetic field of the fusion reactor. In addition, this invention provides flow channel inserts at the bends of the inlet and outlet of the outer cladding circumferential arc-shaped mainstream channel 3 and the inner cladding circumferential arc-shaped mainstream channel 6, but does not provide flow channel inserts inside the arc-shaped flow channels. This can effectively reduce the three-dimensional MHD pressure drop at the bends and greatly simplify the structure, making it easier to process and manufacture, and meeting the compact requirements of small fusion reactors. At the same time, the cross-sectional characteristics of the flow channels have a large aspect ratio, that is, the height a of the flow channel along the poloidal direction of the fusion reactor is greater than the width b along the radial direction, so as to reduce the MHD pressure drop caused by the poloidal magnetic field of the fusion reactor.

[0042] In summary, this invention significantly reduces the MHD voltage drop of the entire cladding module by combining three factors: setting a circumferential arc-shaped flow channel, setting flow channel plugs at the inlet and outlet bends of the circumferential arc-shaped flow channel, and setting a large aspect ratio of the flow channel.

[0043] Plasma 5 is positioned between the outer and inner cladding layers. The side of the cladding facing the plasma 5 has a first wall tungsten tile 9 to withstand the thermal load of the high-temperature plasma 5 and the bombardment of high-current particles. Both the tritium breeder and coolant in the self-cooling cladding are made of liquid lithium-lead alloy. The structural materials are low-activation ferritic steel or ODS steel. The former has a more mature preparation and processing technology, meeting the current structural material requirements for this liquid lithium-lead self-cooling cladding. ODS steel, on the other hand, can operate at temperatures up to 650℃, significantly improving the cladding's thermal conversion efficiency to approximately 45%. Furthermore, a higher tritium breeding rate can be achieved by increasing the radial thickness of the cladding, i.e., the size of the tritium breeding region. The first wall facing the plasma 5 component is made of pure tungsten, a material currently widely used in industry.

[0044] The liquid lithium-lead cladding described in this invention adopts a modular design along the polar direction, and can be divided into 8-16 cladding modules. The specific number of modules is determined based on the large radius of the fusion reactor and the size of the divertor. In current modular cladding designs, it is difficult for liquid lithium-lead to completely flow out of the cladding channels. After reactor shutdown, the lithium-lead cools and solidifies, blocking the cladding channels and making it difficult to restart the cladding after shutdown. However, the channel structure designed in this invention can drain the liquid lithium-lead from the cladding modules, thereby making it quick and convenient to restart the cladding after reactor shutdown.

[0045] Example 2 This embodiment, based on embodiment 1, provides a detailed description of the specific structure of the outer cladding layer.

[0046] The flow velocity in the first wall region is greater than that in the tritium breeding region. The flow rate and average velocity in the first wall region are large, which can meet the cooling requirements of the first wall. In contrast, the flow rate and average velocity in the tritium breeding region are relatively small, which meets the cooling requirements of the relatively small neutron nuclei in this region and is conducive to improving the tritium breeding rate.

[0047] The outer cladding circumferential arc-shaped main channel 3 has multiple branch channels arranged radially side by side, with each branch channel having more than two branches. Depending on the required radius of the fusion reactor and the tritium breeding rate, the number of branch channels in the first wall region channel and the tritium breeding region channel can be set as needed. The number of branch channels in the first wall region channel is 2-4, while the number of branch channels in the tritium breeding region channel is 2-8.

[0048] In one specific implementation, the outer cladding layer includes two 180-degree circumferential arc-shaped main channels in the circumferential direction, each having its own flow path.

[0049] like Figure 2 and 3 As shown, each branch channel is equipped with an outer cladding channel insert 23, i.e., a silicon carbide channel insert, at the connection between the inlet and the outer cladding flow distribution pipe, and at the connection between the outlet and the outer cladding outflow collection pipe 4. Since the liquid lithium lead undergoes a change from radial to circumferential direction and from perpendicular to the magnetic field lines to parallel to the magnetic field lines when entering the outer cladding circumferential arc-shaped main channel 3 from the outer cladding flow distribution pipe, a significant three-dimensional MHD pressure drop is generated. Upon exiting, the liquid lithium lead undergoes a change from circumferential to radial direction. Therefore, silicon carbide channel inserts are used at the inlet and outlet bends to reduce the three-dimensional pressure drop at these locations. Silicon carbide channel inserts are applied to all bends in both the inner and outer cladding pipes. The silicon carbide channel inserts are made of SiCf / SiC composite material with silicon carbide fibers, ensuring structural strength and good resistance to lithium lead corrosion.

[0050] In one specific implementation, such as Figure 2 and 3 As shown, the outer cladding layer circumferential arc-shaped main channel 3 is provided with 4 branch channels, two branch channels are provided in the first wall region channel, and two branch channels are provided in the tritium breeding zone channel. Specifically, these are outer cladding layer branch channel 1 31, outer cladding layer branch channel 2 32, outer cladding layer branch channel 33, and outer cladding layer branch channel 4 34; the inlets of outer cladding layer branch channel 1 31 and outer cladding layer branch channel 2 32 are connected to the radially arranged outer cladding layer flow distribution pipe 1, and the inlets of outer cladding layer branch channel 33 and outer cladding layer branch channel 4 34 are connected to the radially arranged outer cladding layer flow distribution pipe 2; the outlets of outer cladding layer branch channel 1 31, outer cladding layer branch channel 2 32, outer cladding layer branch channel 33, and outer cladding layer branch channel 4 34 are all connected to the outer cladding layer outflow collection pipe 4.

[0051] The outlet of the outer layer flow distribution pipe 1 is connected to the outer layer branch channel inlet pipe 11 and the outer layer branch channel inlet pipe 2 12. The outer layer branch channel inlet pipe 11 and the outer layer branch channel inlet pipe 2 12 are bends, allowing the outer layer flow distribution pipe 1 to turn and connect to the outer layer branch channel 31 and the outer layer branch channel 2 32. The outlet of the outer layer flow distribution pipe 2 2 is connected to the outer layer branch channel inlet pipe 3 21 and the outer layer branch channel inlet pipe 4 22. The outer layer branch channel inlet pipe 3 21 and the outer layer branch channel inlet pipe 4 22 are also bends, allowing the outer layer flow distribution pipe 1 to turn and connect to the outer layer branch channel 3 33 and the outer layer branch channel 4 34. Similarly, bends are also provided at the connection between the outer layer outflow collection pipe 4 and the branch channel to achieve flow channel turning.

[0052] like Figure 3 As shown, the silicon carbide flow channel insert is installed at the bend in the pipe. The silicon carbide flow channel insert extends into the outer circumferential arc-shaped main flow channel 3, with an insertion length between 100mm and 200mm. Similarly, to reduce the three-dimensional MHD pressure drop at the outlet, a flow channel insert made of the same silicon carbide composite material is applied at the outlet bend. There is a gap between the silicon carbide flow channel insert and the inner wall of the branch flow channel (the flow channel uses ferritic steel pipe), with a gap size between 3 and 10mm.

[0053] In one specific implementation, for the flow channel in the first wall region, the outer cladding branch flow channel 31 has a radial width between 20mm and 50mm and has the highest average flow velocity of about 1m / s. The outer cladding branch flow channel 32 has a radial width between 50mm and 80mm and has a lower flow velocity compared to the outer cladding branch flow channel 31. For the tritium breeding region channel, the lithium-lead flow rate in the outer cladding flow distribution pipe 2 is relatively small. The flow rate in the outer cladding flow distribution pipe 1 and the outer cladding flow distribution pipe 2 can be controlled by connecting a separate flow supply pipe and adjusting the pump power. Ultimately, the average flow velocity in the outer cladding branch channel 33 and the outer cladding branch channel 4 34 is less than the average flow velocity in the outer cladding branch channel and the outer cladding branch channel 2 32.

[0054] In one specific implementation, the width of the outer cladding branch channel 33 is between 50mm and 100mm, with an average flow velocity of about 0.2m / s, and the width of the outer cladding branch channel 4 34 is between 70mm and 120mm, with an average flow velocity of about 0.1m / s.

[0055] Preferably, the inlet of the outer cladding circumferential arc-shaped main channel 3 is higher than the outlet in the polar direction, thereby ensuring that liquid lithium lead can flow out of the cladding channel by gravity during reactor shutdown. To prevent liquid lithium lead from cooling and solidifying in the cladding channel during shutdown and causing cladding restart failure, outer cladding flow distribution pipe 1 and outer cladding flow distribution pipe 2 are positioned higher than the outer cladding outflow collection pipe 4 in the polar direction, with a height difference between 10 mm and 20 mm.

[0056] As a preferred option, such as Figure 7 As shown, in the circumferential arc-shaped main channel 3 of the outer cladding, the ratio of the poloidal height 'a' to the radial width 'b' of the branch channels is between 2 and 8. The main channel, along the direction of the circumferential magnetic field lines, has a cross-sectional characteristic of having a large aspect ratio; that is, the inner diameter height of the pipe along the fusion reactor's poloidal direction is greater than its radial width, in order to reduce the MHD pressure drop caused by the fusion reactor's poloidal magnetic field. Its aspect ratio is between 2 and 8, with the specific value determined according to the requirement to reduce the MHD pressure drop.

[0057] Example 3 This embodiment, based on Embodiment 1, provides a detailed description of the specific structure of the inner cladding.

[0058] like Figure 2 and 4 As shown, the inner cladding circumferential arc-shaped main channel 6 consists of multiple branch channels arranged side-by-side along the polar direction. The branch channels of the inner cladding circumferential arc-shaped main channel 6 are connected at the inlet to the radially arranged inner cladding flow distribution pipe 7, and at the outlet to the inner cladding outflow collection pipe 8.

[0059] Liquid lithium-lead metal flows into the inner cladding through the inner cladding flow distribution pipe 7 along the polar direction. After a 90-degree turn, it flows into multiple branch channels of the circumferential arc-shaped main flow channel, and then flows approximately 360 degrees circumferentially into the inner cladding outflow collection pipe 8. The flow direction of the collection pipe is downward along the polar direction. Finally, the liquid metal flows out from below the polar direction of the fusion reactor through the collection pipe, thus ensuring that during reactor shutdown, the liquid lithium-lead metal can flow out of the cladding channels by gravity, preventing the lithium-lead from cooling and solidifying during shutdown, which could cause a reactor restart failure.

[0060] Due to the limited radial space of the inner cladding, there is only one circumferential arc-shaped flow channel in the radial direction, with the inner cladding flow distribution pipe 7 closely attached to the inner cladding outflow collection pipe 8. To cool the wall heat load of the first wall and the neutron volume nuclear heat of the inner cladding, the average flow velocity in the circumferential arc-shaped main flow channel is between 0.2 m / s and 0.5 m / s.

[0061] As the liquid lithium lead enters the inner cladding circumferential arc-shaped main channel 6 from the inner cladding flow distribution pipe 7, it undergoes a 90° turn from polar to circumferential, changing from a direction perpendicular to the magnetic field lines to a direction parallel to the magnetic field lines, resulting in a large three-dimensional MHD pressure drop. Furthermore, the outlet undergoes a change from circumferential to polar. Therefore, inner cladding flow channel plug-in 1 71 and inner cladding flow channel plug-in 2 81 are respectively installed at the inlet and outlet bends. That is, silicon carbide flow channel plugs are installed at the connection between the inlet and the inner cladding flow distribution pipe 7 and at the connection between the outlet and the inner cladding outflow collection pipe 8 of each branch channel to reduce the three-dimensional pressure drop at these locations.

[0062] In one specific implementation, such as Figure 4 As shown, the inner cladding circumferential arc-shaped main channel 6 consists of two branch channels arranged side-by-side along the polar direction. The inner cladding flow distribution pipe 7 is connected to the inlets of the upper and lower branch channels via inner cladding flow distribution inlet branch pipe 1 73 and inner cladding flow distribution inlet branch pipe 2 75, respectively. An inner cladding flow channel insert port 1 72 is provided in the inner cladding flow channel insert 1 73 for inserting the inner cladding flow channel insert 1 71. An inner cladding flow channel insert 1 71 is provided in the inner cladding flow distribution inlet branch pipe 2 75. The inner cladding flow channel plug-in port 2 74 is used for inserting the inner cladding flow channel plug-in 1 71; the outlets of the upper and lower branch flow channels are respectively connected to the inner cladding flow outlet branch pipe 1 83 and the inner cladding flow outlet branch pipe 2 85. The inner cladding flow outlet branch pipe 1 83 is provided with an inner cladding flow channel plug-in port 3 82 for inserting the inner cladding flow channel plug-in 2 81, and the inner cladding flow outlet branch pipe 2 85 is provided with an inner cladding flow channel plug-in port 4 84 for inserting the inner cladding flow channel plug-in 2 81.

[0063] Preferably, the inner diameter 'a' of each branch channel along the polar direction is much larger than the inner diameter 'b' along the radial direction, with an aspect ratio 'a / b' between 2 and 8, 'a' between 80 mm and 400 mm, and 'b' between 40 mm and 200 mm, thereby reducing the MHD pressure drop caused by the polar magnetic field of the fusion reactor.

[0064] Example 4 This embodiment, based on Embodiment 1, provides a detailed description of another specific structure of the inner cladding.

[0065] like Figure 5 and 6As shown, in this embodiment, the inner cladding circumferential arc-shaped main flow channel 6 is a large spiral circumferential main flow channel that extends along the polar direction. With only one inlet and one outlet, this design avoids the high MHD pressure drop problem caused by the large average flow velocity in the inlet / outlet junction pipe of the structure in Embodiment 3. Liquid lithium-lead flows into the inner cladding circumferential arc-shaped main flow channel 6 along the polar direction, then flows 90 degrees to the circumferential direction, spiraling downwards along the inclined circumferential main flow channel, and finally flows out of the inner cladding along the polar direction through the outlet. To cool the wall heat load of the first wall and the neutron volumetric nuclear heat of the inner cladding, the average flow velocity in the circumferential main flow channel is between 0.2 m / s and 1 m / s.

[0066] In this embodiment, the liquid metal flows upward from the electrode and finally flows out downward from the electrode, thereby ensuring that the liquid lithium-lead metal can flow out of the blanket channel by gravity during the shutdown period, preventing the lithium-lead from cooling and solidifying during the shutdown period, which would cause a reactor restart failure.

[0067] The spiral circumferential main channel has an angle with the horizontal direction. The size of the angle is determined by the radius of the fusion reactor and the angle should be minimized as much as possible to reduce the pressure drop of the three-dimensional MHD. The angle range is between 5 and 20 degrees.

[0068] To reduce the MHD voltage drop caused by the poloidal magnetic field, the cross-sectional characteristics of the spiral circumferential main channel are the same as those of the outer cladding. The inner diameter a along the poloidal direction of the channel is much larger than the inner diameter b along the radial direction. Its length-to-width ratio a / b is between 2 and 8, with a value between 80 mm and 400 mm and b value between 40 mm and 200 mm.

[0069] like Figure 6 As shown, to reduce the three-dimensional MHD pressure drop at the inlet and outlet, flow channel inserts made of silicon carbide composite material are installed at the flow bends at the inlet and outlet. These inserts cover the inlet and outlet pipe areas and partially extend into the spiral circumferential main flow channel, with an extension length between 100mm and 200mm. A gap exists between the silicon carbide flow channel inserts and the inner wall of the spiral circumferential main flow channel, with a gap size between 3 and 10mm.

[0070] Finally, it should be noted that the above specific embodiments are only used to describe the purpose, technical solution, and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation of the present invention and is not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the foregoing specific embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions or improvements can be made to some or all of the technical features. These modifications, equivalent substitutions, and improvements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A liquid lithium-lead self-cooling cladding with low MHD voltage drop, characterized in that, include: The outer cladding layer includes an outer cladding layer circumferential arc-shaped main channel (3), wherein the outer cladding layer circumferential arc-shaped main channel (3) includes a first wall region channel and a tritium breeding region channel arranged radially from the inside to the outside; The inner cladding includes the inner cladding circumferential arc-shaped main channel (6); Among them, the flow direction of the outer cladding circumferential arc-shaped main channel (3) and the inner cladding circumferential arc-shaped main channel (6) is parallel or tends to be parallel to the magnetic field lines of the fusion reactor circumferential magnetic field. The outer cladding circumferential arc-shaped main channel (3) and the inner cladding circumferential arc-shaped main channel (6) are provided with flow channel inserts at the bends at the inlet and outlet. The polar height a of the outer cladding circumferential arc-shaped main channel (3) and the inner cladding circumferential arc-shaped main channel (6) is greater than the radial width b.

2. The liquid lithium-lead self-cooling cladding with low MHD voltage drop according to claim 1, characterized in that, The flow velocity in the first wall region is greater than that in the tritium breeding region.

3. The liquid lithium-lead self-cooling cladding with low MHD voltage drop according to claim 1, characterized in that, The outer cladding layer has multiple branch channels arranged radially side by side in the circumferential arc-shaped main channel (3), and the number of each branch channel is greater than 2.

4. The liquid lithium-lead self-cooling cladding with low MHD voltage drop according to claim 3, characterized in that, The branch channels within the circumferential arc-shaped main channel (3) of the outer cladding layer are connected at the inlet to the radially arranged outer cladding layer flow distribution pipe, and at the outlet to the outer cladding layer outflow summing pipe (4).

5. A liquid lithium-lead self-cooling cladding with low MHD voltage drop according to any one of claims 1-4, characterized in that, The width of the flow channel from the first wall region to the tritium breeding region increases radially.

6. A liquid lithium-lead self-cooling cladding with low MHD voltage drop according to any one of claims 1-4, characterized in that, The entrance of the outer circumferential arc-shaped main channel (3) is higher than the exit at the extreme upward.

7. A liquid lithium-lead self-cooling cladding with low MHD voltage drop according to claim 1, characterized in that, The inner cladding circumferential arc-shaped main channel (6) has multiple branch channels arranged side by side along the polar direction, and the number is greater than 2.

8. A liquid lithium-lead self-cooling cladding with low MHD voltage drop according to claim 7, characterized in that, The branch channels of the inner cladding circumferential arc-shaped main channel (6) are connected at the inlet to the radially arranged inner cladding flow distribution pipe (7), and at the outlet to the inner cladding outflow summing pipe (8).

9. A liquid lithium-lead self-cooling cladding with low MHD voltage drop according to claim 3 or 7, characterized in that, In the outer circumferential arc-shaped main channel (3) and the inner circumferential arc-shaped main channel (6), the ratio of the polar height a to the radial width b of the branch channel is between 2 and 8.

10. A liquid lithium-lead self-cooling cladding with low MHD voltage drop according to claim 8, characterized in that, The inner cladding circumferential arc-shaped main channel (6) is a spiral circumferential channel extending along the polar direction.

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