Liquid lithium lead self-cooling cladding with low MHD pressure drop

Abstract

The invention 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 layer, the outer cladding layer comprises an outer cladding layer annular arc-shaped main flow channel, and the outer cladding layer annular arc-shaped main flow channel comprises a first wall area flow channel and a tritium breeding area flow channel which are sequentially arranged from inside to outside in the radial direction; the inner cladding comprises an inner cladding annular arc-shaped main runner; wherein the flowing directions of the outer cladding annular arc-shaped main flow channel and the inner cladding annular arc-shaped main flow channel are parallel to or tend to be parallel to the magnetic line direction of a fusion reactor annular magnetic field, and the outer cladding annular arc-shaped main flow channel and the inner cladding annular arc-shaped main flow channel are provided with flow channel inserting pieces at the turning positions of an inlet and an outlet. The polar height a of the outer cladding annular arc-shaped main runner and the polar height a of the inner cladding annular arc-shaped main runner are larger than the radial width b; the cladding provided by the invention has the advantages of low MHD voltage drop, simple structure, low processing technology difficulty, and easy realization in engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of fusion reactor engineering, and in particular to a liquid lithium-lead self-cooling blanket with low MHD pressure drop. Background Art

[0002] Tritium breeder blankets are a key component of fusion reactors, providing neutron shielding, tritium breeding, and extracting and converting fusion energy. Tritium breeder blankets can be categorized as either liquid or solid, depending on the breeder agent. Liquid blanket breeders are typically liquid lithium metal or lithium-lead alloys. Liquid blankets offer advantages such as low operating pressure, simple structure, high thermal conversion efficiency, and the ability to generate tritium online. Liquid blankets are considered a key solution 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] In the liquid blanket of a magnetic confinement fusion reactor, the intense magnetic fields used to confine the plasma can reach as high as 10 T, generating a very strong liquid metal magnetohydrodynamic (MHD) effect. When liquid metal moves in a strong magnetic field, it generates a Lorentz force that impedes its forward flow, resulting in a very large MHD pressure drop, often more than 10,000 times the normal hydraulic pressure drop. This remains a key unresolved issue. This MHD pressure drop increases pump power consumption, reduces economic competitiveness, and induces unbearable stresses in the piping structural materials, raising questions about the feasibility of engineering MHD pressure drop in the liquid blanket. Research results indicate that the MHD pressure drop in the liquid blanket should be limited to less than 2 MPa, posing a significant challenge to its design.

[0004] Currently, three different types of liquid blankets have been proposed internationally, namely self-cooling, double-cooling and single-cooling liquid blankets.

[0005] The liquid metal of the self-cooled liquid blanket serves as both a tritium breeder and a coolant, greatly simplifying the blanket structure. However, a higher flow rate is required to meet the cooling requirements (about 1m / s). The higher flow rate will bring about a very large MHD pressure drop, which is usually difficult to meet the pressure drop limit of 2MPa. In order to reduce the MHD pressure drop, the concept of a double-cooled lithium-lead blanket was proposed. This scheme uses high-temperature and high-pressure helium to cool the first wall and structural materials, while the tritium breeding zone is self-cooled by liquid metal lithium-lead. The average flow rate of the liquid lithium-lead is about 0.1m / s to meet the cooling requirements of the breeding zone. In order to reduce the MHD pressure drop in the polar flow channel, a high-insulation and low-thermal-conductivity silicon carbide composite material flow channel plug-in is used to reduce the pressure drop and increase the temperature of the lithium-lead at the flow channel outlet to improve the thermal conversion efficiency of the blanket. Due to the use of helium cooling and silicon carbide flow channel inserts, the structure of the double-cooled blanket is very complex. At present, the preparation and processing technology of composite silicon carbide composite flow channel inserts are still immature, and many problems remain before its large-scale application. To reduce the MHD pressure drop of the liquid blanket, the European Union has proposed the concept of separately cooled liquid blanket. In this scheme, the liquid lithium-lead flows very slowly (about 1mm / s). The entire blanket, including the tritium breeding zone, is cooled by high-temperature and high-pressure helium or water. The liquid lithium-lead is only slowly circulated out of the fusion reactor for online tritium extraction and has no cooling function. Due to the slow flow rate of lithium-lead, the MHD pressure drop in the breeding zone is small. However, due to the high flow rate at the inlet and outlet manifolds, the MHD pressure drop is still large. Insulation coating and other means are still needed to reduce the pressure here. The structure of separately cooled lithium-lead blanket is also very complex, the thermal conversion efficiency is low, and there may be a serious problem of tritium retention.

[0006] Comprehensively comparing the three types of liquid blankets mentioned above, the self-cooling blanket has the simplest structure and the highest heat conversion efficiency, and is the ultimate research and development goal of the liquid blanket. However, its research and development is also the most difficult, and the high MHD pressure drop caused by the large flow rate is the main problem restricting its development. The double-cooled and single-cooled liquid blankets have complex structures, and the mainstream of the liquid lithium-lead is along the pole direction, which interacts with the strong toroidal magnetic field to produce a very large MHD pressure drop. In addition, its heat conversion efficiency is much lower than that of the self-cooling blanket, especially the helium-cooled or water-cooled lithium-lead blanket, which has a heat conversion efficiency of only about 33%, which cannot meet the economic requirements of long-term fusion power stations. Therefore, reducing the MHD pressure drop of the liquid blanket through engineering feasible methods has become a key issue that urgently needs to be solved in the development of liquid blankets. Summary of the Invention

[0007] The present invention aims to solve the technical problems of high MHD pressure drop, complex structure and great processing difficulty of existing liquid blankets. The purpose is to provide a liquid lithium-lead self-cooling blanket with low MHD pressure drop. By providing an annular arc flow channel, arranging flow channel plugs only at the inlet and outlet turns of the annular arc flow channel, and setting the flow channel with a large aspect ratio, the three are combined to greatly reduce the MHD pressure drop of the entire blanket module. At the same time, its structure is greatly simplified compared with dual-cooling and single-cooling blankets, and it is easier to process and manufacture, which can meet the compact requirements of small fusion reactors. It has the advantages of low MHD pressure drop, simple structure, low processing difficulty, and is easier to implement in engineering.

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

[0009] A liquid lithium-lead self-cooling blanket with low MHD pressure drop, comprising: An outer envelope, comprising an outer envelope annular arcuate main flow channel, wherein the outer envelope annular arcuate main flow channel comprises a first wall region flow channel and a tritium breeding region flow channel sequentially arranged from the inside to the outside in radial direction; An inner cladding layer, comprising an inner cladding annular arc-shaped main flow channel; Among them, the flow direction of the outer envelope annular arc main channel and the inner envelope annular arc main channel is parallel or tends to be parallel to the direction of the magnetic lines of force of the annular magnetic field of the fusion reactor. The outer envelope annular arc main channel and the inner envelope annular arc main channel are provided with flow channel plug-ins at the turning points of the inlet and outlet. The poloidal height a of the outer envelope annular arc main channel and the inner envelope annular arc main channel is greater than the radial width b.

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

[0011] When the magnetic lines of force of the external magnetic field align with the mainstream direction of the liquid lithium-lead flow, no Lorentz drag is generated to hinder its forward flow. Under these conditions, the MHD pressure drop is almost negligible, meaning that the primary pressure drop is hydraulic. A magnetic confinement fusion reactor primarily comprises toroidal and poloidal magnetic fields. The poloidal field is much smaller than the toroidal field, at approximately one-tenth its strength. Therefore, the present invention reduces the MHD pressure drop in the mainstream direction by arranging the liquid metal main flow pipe parallel to the toroidal magnetic field of the fusion reactor. Furthermore, the present invention provides flow channel inserts at the inlet and outlet corners of the outer and inner cladding annular curved main flow channels, but does not include flow channel inserts within the curved flow channels. This effectively reduces the three-dimensional MHD pressure drop at these corners and significantly simplifies the structure, making it easier to manufacture and meeting the compact requirements of small fusion reactors. Furthermore, the cross-sectional characteristics of the flow channel have a large aspect ratio, meaning that the channel's height (a) along the poloidal direction of the fusion reactor is greater than its width (b) along the radial direction, thereby reducing the MHD pressure drop caused by the poloidal magnetic field of the fusion reactor.

[0012] In summary, the present invention greatly reduces the MHD pressure drop of the entire cladding module by combining the provision of an annular arc flow channel, the provision of a flow channel plug-in at the inlet and outlet turns of the annular arc flow channel, and the provision of a larger aspect ratio for the flow channel.

[0013] Furthermore, the flow velocity of the flow passages in the first wall region is greater than the flow velocity of the flow passages in the tritium breeding region. The high flow rate and average flow velocity in the flow passages in the first wall region can meet the cooling requirements of the first wall, while the relatively low flow rate and average flow velocity in the flow passages in the tritium breeding region meet the cooling requirements of the relatively small neutron nuclear heat in this region and help improve the tritium breeding rate.

[0014] Furthermore, multiple branch flow channels are radially arranged side by side within the outer envelope's annular arcuate main channel, and the number of each branch flow channel is greater than two. The number of branch flow channels in the first wall region flow channel and the tritium breeding region flow channel can be adjusted as needed, with the number of branch flow channels in the first wall region flow channel being 2-4 and the number of branch flow channels in the tritium breeding region flow channel being 2-8.

[0015] Furthermore, the branch flow channels within the outer envelope's annular curved main channel are connected at their inlets to radially arranged outer envelope flow distribution pipes, and at their outlets to the outer envelope's outflow collection pipe. The outer envelope's flow distribution pipe is used to distribute liquid lithium-lead entering the outer envelope's annular curved main channel through branch flow channels, with some entering the first wall region flow channel and some entering the tritium breeding region flow channel. The liquid lithium-lead then flows out of the outer envelope's outflow collection pipe. Silicon carbide flow channel inserts are provided at the inlet connection with the outer envelope's flow distribution pipe, and at the outlet connection with the outer envelope's outflow collection pipe.

[0016] Among them, since the liquid lithium lead enters the outer cladding annular arc main channel from the outer cladding flow distribution pipe, it undergoes a transformation from radial to annular, and from the direction perpendicular to the magnetic lines of force to the direction parallel to the magnetic lines of force, which will produce a large three-dimensional MHD pressure drop. Therefore, silicon carbide flow channel plugs are used at the inlet and outlet turns to reduce the three-dimensional pressure drop here. Silicon carbide flow channel plugs are applied to all bends of the inner and outer claddings; the silicon carbide flow channel plugs are made of SiC with silicon carbide fibers. f / SiC composite material to ensure its structural strength and good resistance to lithium-lead corrosion.

[0017] Furthermore, the width of the flow channel from the first wall region to the tritium breeding region increases radially. The branch flow channels in the first wall region have a smaller cross-sectional dimension, with a radial width between 20 mm and 100 mm. This ensures a high flow velocity (average flow velocity of approximately 1 m / s) for the liquid lithium-lead in the first wall region, thereby cooling the first wall region with a higher heat load. The entire first wall region has a radial thickness between 100 mm and 300 mm. The branch flow channels within the tritium breeding region have a relatively larger cross-sectional dimension, with a radial width between 60 mm and 200 mm, as the nuclear heat of the subvolume is much smaller than that of the first wall region. The liquid lithium-lead flow velocity in this region is relatively low (average flow velocity of approximately 0.1 m / s), cooling the tritium breeding region while circulating the lithium-lead out of the fusion reactor. The entire tritium breeding region has a radial thickness between 200 mm and 1000 mm, and the specific thickness can be adjusted based on the required tritium breeding rate.

[0018] Furthermore, the inlet of the outer blanket's annular curved main channel is higher than the outlet in the polar direction, ensuring that liquid lithium-lead can flow out of the blanket channel by gravity during shutdown. Silicon carbide flow channel inserts are installed at the inlet connection with the outer blanket flow distribution pipe and at the outlet connection with the outer blanket outflow collection pipe.

[0019] Furthermore, the inner cladding annular curved main channel is provided with multiple branch flow channels arranged side by side along the pole direction, and the number of branch flow channels is greater than two. There are two designs for the inner cladding annular curved main channel: one is that the multiple branch flow channels arranged side by side along the pole direction each flow circumferentially for approximately 360 degrees before flowing out, with an average flow rate between 0.2m / s and 0.5m / s; the other is that only one large spiral annular main channel is provided, and the liquid lithium-lead spirals downward along the inclined annular main channel and finally flows out through the outlet at the bottom, with an average flow rate between 0.2m / s and 1m / s.

[0020] Furthermore, the branch flow channels of the inner cladding annular arcuate main channel are connected to a radially arranged inner cladding flow distribution pipe at their inlet and to an inner cladding outflow collection pipe at their outlet. Silicon carbide flow channel inserts are provided at the inlet connection with the inner cladding flow distribution pipe and at the outlet connection with the inner cladding outflow collection pipe of each branch flow channel.

[0021] Among them, since the liquid lithium lead enters the inner cladding annular arc main channel from the inner cladding flow distribution pipe, it undergoes a 90° turn from polar to annular, and from the direction perpendicular to the magnetic field lines to the direction parallel to the magnetic field lines, which will produce a large three-dimensional MHD pressure drop. Therefore, silicon carbide flow channel plugs are used at the inlet and outlet turns to reduce the three-dimensional pressure drop here. Silicon carbide flow channel plugs are applied to all bends of the inner and outer claddings; the silicon carbide flow channel plugs are made of SiC with silicon carbide fibers. f / SiC composite material to ensure its structural strength and good resistance to lithium-lead corrosion.

[0022] Furthermore, in the outer and inner envelope annular curved main channels, the ratio of the poloidal height a to the radial width b of the branch channels is between 2 and 8. The cross-section of the main channel along the toroidal magnetic field lines is characterized by a large aspect ratio. Specifically, the pipe inner diameter height along the poloidal direction of the fusion reactor is greater than the radial width. This reduces the MHD pressure drop caused by the poloidal magnetic field of the fusion reactor. The aspect ratio is between 2 and 8, with the specific value determined based on the need to reduce the MHD pressure drop.

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

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

[0025] 1. The present invention reduces the MHD pressure drop through a unique flow channel arrangement. By providing annular curved flow channels, installing flow channel inserts only at the inlet and outlet bends of the annular curved flow channels, and setting the flow channels with a large aspect ratio, the three combined measures significantly reduce the MHD pressure drop of the entire blanket module. Furthermore, its structure is significantly simpler than dual-cooling and single-cooling blankets, making it easier to manufacture and process, meeting the compact requirements of small fusion reactors. It offers the advantages of low MHD pressure drop, simple structure, minimal manufacturing complexity, and ease of engineering implementation.

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

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

[0028] 4. The inlet of the outer blanket annular arc main flow channel of the present invention is higher than the outlet in the polar direction, thereby ensuring that liquid lithium-lead can flow out of the blanket flow channel by its own gravity during shutdown.

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

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

[0031] 7. The cladding material of the present invention can be made of ODS steel, which will significantly increase its heat conversion efficiency by about 45%. By increasing the radial thickness of the cladding, that is, the size of the tritium breeding area, a higher tritium breeding rate can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings: Figure 1 Schematic diagram of the overall liquid lithium-lead self-cooling blanket with low MHD pressure drop; Figure 2 Schematic diagram of the flow channel cross section perpendicular to the pole direction of the liquid lithium-lead self-cooling blanket with low MHD pressure drop; Figure 3 This is a schematic diagram of the flow channel cross section at the outer envelope inlet and flow turning point; Figure 4 Schematic diagram of the cross section of the inner cladding inlet and outlet flow channels; Figure 5 Schematic diagram of the spiral inner cladding structure; Figure 6 This is a top view of the spiral inner cladding; Figure 7 It is a schematic diagram of the cross section of the annular arc main channel and the vertical annular flow channel.

[0033] Markings and corresponding parts names in the accompanying drawings: 1-Outer cladding flow distribution pipe 1, 11-Outer cladding branch flow channel inlet pipe 1, 12-Outer cladding branch flow channel inlet pipe 2, 2-Outer cladding flow distribution pipe 2, 21-Outer cladding branch flow channel inlet pipe 3, 22-Outer cladding branch flow channel inlet pipe 4, 23-Outer cladding flow channel plug-in, 3-Outer cladding annular arc main channel, 31-Outer cladding branch flow channel 1, 32-Outer cladding branch flow channel 2, 33-Outer cladding branch flow channel 3, 34-Outer cladding branch flow channel 4, 4-Outer cladding outflow collection pipe, 5-Plasma, 6-Inner cladding Annular arc main channel, 7-inner cladding flow distribution pipe, 71-inner cladding flow channel plug-in 1, 72-inner cladding flow channel plug-in socket 1, 73-inner cladding flow distribution inlet branch pipe 1, 74-inner cladding flow channel plug-in socket 2, 75-inner cladding flow distribution inlet branch pipe 2, 8-inner cladding outflow collection pipe, 81-inner cladding flow channel plug-in 2, 82-inner cladding flow channel plug-in socket 3, 83-inner cladding outflow outlet branch pipe 1, 84-inner cladding flow channel plug-in socket 4, 85-inner cladding outflow outlet branch pipe 2, 9-first wall tungsten tile. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions 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 to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that these specific details are not necessarily required to practice the present invention. In other embodiments, well-known structures, circuits, materials, or methods are not described in detail to avoid obscuring the present invention.

[0036] Throughout this specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment," "an embodiment," "an example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combinations and / or subcombinations. Furthermore, it will be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes only and are not necessarily drawn to scale. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0037] In the description of the present invention, the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are merely for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present application.

[0038] At the same time, the terms "dispose," "assemble," "connect," and "connect" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediary, or internal connections between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention.

[0039] Example 1 A liquid lithium-lead self-cooling blanket with low MHD pressure drop, see Figure 1-6 ,include: The outer envelope includes an outer envelope annular arcuate main flow channel 3, wherein the outer envelope annular arcuate main flow channel 3 includes a first wall region flow channel and a tritium breeding region flow channel sequentially arranged from the inside to the outside in the radial direction; An inner cladding layer, including an inner cladding annular arc-shaped main flow channel 6; Among them, the flow directions of the outer cladding annular arcuate main channel 3 and the inner cladding annular arcuate main channel 6 are parallel or tend to be parallel to the direction of the magnetic lines of force of the fusion reactor's annular magnetic field. The outer cladding annular arcuate main channel 3 and the inner cladding annular arcuate main channel 6 are provided with flow channel plug-ins at the turning points of the inlet and outlet. The poloidal height a of the outer cladding annular arcuate main channel 3 and the inner cladding annular arcuate main channel 6 is greater than the radial width b.

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

[0041] When the magnetic lines of the external magnetic field are in the same direction as the mainstream of liquid lithium-lead, no Lorentz resistance will be generated to hinder its forward flow. Under this condition, the MHD pressure drop can be almost ignored, that is, the main pressure drop at this time is hydraulic pressure drop. For a magnetic confinement fusion reactor, it mainly includes toroidal and poloidal magnetic fields. The poloidal magnetic field is much smaller than the toroidal field, about one tenth of its field strength. Therefore, the present invention reduces the MHD pressure drop in the mainstream direction by arranging the mainstream pipe of the liquid metal in a direction parallel to the toroidal magnetic field of the fusion reactor. In addition, the present invention provides flow channel plug-ins at the turning points of the inlet and outlet of the outer cladding annular arc main channel 3 and the inner cladding annular arc main channel 6, but does not provide flow channel plug-ins in the arc flow channel, which can effectively reduce the three-dimensional MHD pressure drop at the turning point 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 channel 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, the present invention greatly reduces the MHD pressure drop of the entire cladding module by combining the provision of an annular arc flow channel, the provision of a flow channel plug-in at the inlet and outlet turns of the annular arc flow channel, and the provision of a larger aspect ratio for the flow channel.

[0043] Plasma 5 is located between the outer and inner blankets. The side of the blanket facing the plasma 5 features a first wall of tungsten tiles 9 to withstand the heat load of the high-temperature plasma 5 and the intense particle bombardment. The tritium breeder and coolant in the self-cooling blanket are both liquid metal lithium-lead alloys, and the structural materials are low-activation ferritic steel or ODS steel. The former has a mature preparation and processing technology and meets the recent structural material requirements of the liquid lithium-lead self-cooling blanket. ODS steel has an operating temperature of up to 650°C and significantly improves the blanket's thermal conversion efficiency to approximately 45%. A higher tritium breeding rate can be achieved by increasing the radial thickness of the blanket, i.e., the size of the tritium breeding zone. The first wall region facing the plasma 5 is made of pure tungsten, a relatively mature industrial material.

[0044] The liquid lithium-lead outer blanket described in this invention adopts a modular design along the pole direction, allowing for 8-16 blanket modules along the pole direction. The specific number of modules is determined by the maximum radius of the fusion reactor and the size of the divertor. Current modular blanket designs make it difficult for liquid lithium-lead to completely flow out of the blanket flow channels. After a reactor shutdown, the lithium-lead cools and solidifies, blocking the blanket flow channels and making blanket restart difficult. However, the flow channel structure designed in this invention allows for the emptying of liquid lithium-lead from the blanket modules, making blanket restart quick and easy after a reactor shutdown.

[0045] Example 2 Based on Example 1, this example describes in detail the specific structure of the outer cladding layer.

[0046] The flow velocity of the flow channel in the first wall area is greater than the flow velocity of the flow channel in the tritium breeding area. The flow rate and average flow velocity of the flow channel in the first wall area are large, which can meet the cooling demand of the first wall. The flow rate and average flow velocity in the flow channel in the tritium breeding area are relatively small, which meets the cooling demand of the relatively small neutron nuclear heat in this area and is conducive to improving the tritium breeding rate.

[0047] Multiple branch channels are radially arranged side by side within the outer envelope's annular arcuate main channel 3, with the number of each channel exceeding two. The number of branch channels in the first wall region and tritium breeding zone channels can be adjusted as needed, depending on the fusion reactor radius and tritium breeding rate requirements. The number of branch channels in the first wall region channels is 2-4, while the number of branch channels in the tritium breeding zone channels is 2-8.

[0048] In a specific embodiment, the outer cladding includes two 180-degree circumferential arcuate main flow channels in the circumferential direction, and the two circumferential arcuate main flow channels have respective flow channels.

[0049] like Figure 2 and 3 As shown, each branch flow channel is equipped with an outer cladding flow channel insert 23, i.e., a silicon carbide flow 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. As the liquid lithium-lead enters the outer cladding annular arc main flow channel 3 from the outer cladding flow distribution pipe, it undergoes a transition from radial to annular, and 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. During outflow, the liquid lithium-lead undergoes a transition from annular to radial. Therefore, silicon carbide flow channel inserts are used at the inlet and outlet bends to reduce the three-dimensional pressure drop there. Silicon carbide flow channel inserts are also applied to all bends in the inner and outer cladding. These silicon carbide flow channel inserts are made of SiCf / SiC composite material with silicon carbide fibers to ensure structural strength and good resistance to lithium-lead corrosion.

[0050] In a specific embodiment, Figure 2 and 3 As shown, the outer blanket annular arcuate main channel 3 is provided with four branch channels, two of which are provided in the first wall region channel, and two of which are provided in the tritium breeding region channel. Specifically, they are outer blanket branch channel 1 31, outer blanket branch channel 2 32, outer blanket branch channel 3 33, and outer blanket branch channel 4 34. The inlets of outer blanket branch channel 1 31 and outer blanket branch channel 2 32 are connected to the radially arranged outer blanket flow distribution pipe 1 1, while the inlets of outer blanket branch channel 3 33 and outer blanket branch channel 4 34 are connected to the radially arranged outer blanket flow distribution pipe 2 2. The outlets of outer blanket branch channel 1 31, outer blanket branch channel 2 32, outer blanket branch channel 3 33, and outer blanket branch channel 4 34 are all connected to the outer blanket outflow manifold 4.

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

[0052] like Figure 3 As shown, the silicon carbide flow channel insert is placed precisely at the elbow, partially extending into the outer cladding's annular curved main channel 3, with a length ranging from 100mm to 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 installed at the outlet elbow. A gap of 3-10mm exists between the silicon carbide flow channel insert and the inner wall of the branch channel (which is made of ferritic steel).

[0053] In a specific embodiment, for the flow channel in the first wall region, the outer cladding branch flow channel 1 31 has a radial width between 20 mm and 50 mm, and has the highest average flow velocity of approximately 1 m / s. The outer cladding branch flow channel 2 32 has a radial width between 50 mm and 80 mm, and has a lower flow velocity than the outer cladding branch flow channel 1 31. For the tritium proliferation area flow channel, the lithium-lead flow in the outer envelope flow distribution tube 2 is relatively small. The flow in the outer envelope flow distribution tube 1 and the outer envelope flow distribution tube 2 can be controlled by separately connecting to the flow supply pipe and adjusting the pump power, so that the average flow rate of the outer envelope branch flow channel 3 33 and the outer envelope branch flow channel 4 34 is finally smaller than the average flow rate in the outer envelope branch flow channel and the outer envelope branch flow channel 2 32.

[0054] In a specific embodiment, the width of the outer layer branch channel three 33 is between 50mm-100mm, the average flow velocity is about 0.2m / s, and the width of the outer layer branch channel four 34 is between 70mm-120mm, the average flow velocity is about 0.1m / s.

[0055] Preferably, the inlet of the outer blanket annular arcuate main channel 3 is higher than the outlet in the polar direction, ensuring that liquid lithium-lead can flow out of the blanket channel by gravity during shutdown. To ensure that liquid lithium-lead can flow out of the blanket channel by gravity during shutdown and prevent the liquid lithium-lead from cooling and solidifying within the blanket channel, which could cause further blanket failure, the outer blanket flow distribution pipe 1 and the outer blanket flow distribution pipe 2 are higher than the outer blanket outflow manifold 4 in the polar direction, with a height difference of between 10 mm and 20 mm.

[0056] As a preference, Figure 7 As shown, in the outer envelope's annular curved main channel 3, the ratio of the branch channel's poloidal height a to its radial width b is between 2 and 8. The main channel's cross-section, along the toroidal magnetic field lines, features a large aspect ratio. Specifically, the channel's inner diameter height along the poloidal direction of the fusion reactor is greater than its radial width. This reduces the MHD pressure drop caused by the reactor's poloidal magnetic field. The aspect ratio ranges from 2 to 8, with the specific value determined based on the need to minimize the MHD pressure drop.

[0057] Example 3 Based on Example 1, this example describes the specific structure of the inner cladding in detail.

[0058] like Figure 2 and 4 As shown, the inner cladding annular arcuate main channel 6 comprises a plurality of branch channels arranged side by side in the polar direction. The branch channels of the inner cladding annular arcuate main channel 6 are connected to the radially arranged inner cladding flow distribution pipe 7 at the inlet and to the inner cladding outflow collection pipe 8 at the outlet.

[0059] Liquid lithium-lead metal flows from the poloidal inner blanket flow distribution pipe 7 into the inner blanket, making a 90-degree turn before flowing into multiple branch flow channels of the circumferentially curved main channel. It then flows circumferentially through approximately 360 degrees into the inner blanket outflow manifold 8, with the flow direction of the manifold oriented downwardly, along the poloidal direction. Ultimately, the liquid metal exits the manifold from below the poloidal region of the fusion reactor. This ensures that the liquid lithium-lead metal flows out of the blanket flow channels by gravity during shutdown, preventing the lithium-lead metal from cooling and solidifying during shutdown, which could cause a restart failure.

[0060] Due to the limited radial space within the inner blanket, there is only one annular curved flow channel in the radial direction. The inner blanket flow distribution pipe 7 is in close proximity to the inner blanket outflow collection pipe 8. To cool the heat load on the first wall and the neutron volume nuclear heat of the inner blanket, the average flow velocity within the annular curved main flow channel is between 0.2 m / s and 0.5 m / s.

[0061] Since the liquid lithium-lead undergoes a 90° turn from polar to circumferential when entering the inner cladding annular arc main channel 6 from the inner cladding flow distribution pipe 7, and changes from a direction perpendicular to the magnetic lines of force to a direction parallel to the magnetic lines of force, a large three-dimensional MHD pressure drop will be generated, and the outlet undergoes a transition from circumferential to polar. Therefore, inner cladding flow channel plug-in 1 71 and inner cladding flow channel plug-in 2 81 are respectively provided at the inlet and outlet turning points. That is, each branch flow channel is provided with a silicon carbide flow channel plug-in 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 to reduce the three-dimensional pressure drop there.

[0062] In a specific embodiment, Figure 4 As shown, the inner cladding annular arcuate main flow channel 6 is composed of two branch flow channels arranged side by side in the polar direction. The inner cladding flow distribution pipe 7 is connected to the inlets of the upper and lower branch flow channels through the inner cladding flow distribution inlet branch pipe 1 73 and the inner cladding flow distribution inlet branch pipe 2 75, respectively. The inner cladding flow distribution inlet branch pipe 1 73 is provided with an inner cladding flow channel plug-in socket 1 72 for inserting the inner cladding flow channel plug-in 1 71, and the inner cladding flow distribution inlet branch pipe 2 75 is provided with an inner cladding flow channel plug-in socket 1 The laminar flow channel plug-in socket 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 outflow outlet branch pipe 1 83 and the inner cladding outflow outlet branch pipe 2 85. The inner cladding outflow outlet branch pipe 1 83 is provided with the inner cladding flow channel plug-in socket 3 82 for inserting the inner cladding flow channel plug-in 2 81, and the inner cladding outflow outlet branch pipe 2 85 is provided with the inner cladding flow channel plug-in socket 4 84 for inserting the inner cladding flow channel plug-in 2 81.

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

[0064] Example 4 This embodiment describes in detail another specific structure of the inner cladding based on the embodiment 1.

[0065] like Figure 5 and 6As shown, in this embodiment, the inner blanket annular arc main channel 6 is a large spiral annular main channel, and the spiral annular flow channel extends in the poloidal direction. There is 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 manifolds in the structure of Example 3. Liquid lithium-lead flows into the inner blanket annular arc main channel 6 along the poloidal direction, then turns to the annular direction after 90 degrees, spirals downward along the inclined annular main channel, and finally flows out of the inner blanket through the outlet along the poloidal direction. In order to cool the wall heat load of the first wall and the neutron volume nuclear heat of the inner blanket, the average flow velocity in the annular main channel is between 0.2m / s and 1m / s.

[0066] In this embodiment, the liquid metal flows in from the upper pole and eventually flows out from the lower pole, thereby ensuring that the liquid metal lithium-lead can flow out of the cladding flow channel by gravity during the shutdown period, preventing the lithium-lead from cooling and solidifying during the shutdown period, thereby causing a stack restart failure.

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

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

[0069] like Figure 6 As shown, to reduce the 3D MHD pressure drop at the inlet and outlet, flow channel inserts made of silicon carbide composite material are installed at the flow turns between the inlet and outlet. These inserts cover the inlet and outlet pipe areas and partially extend into the spiral annular main channel. The length of the inserted flow channel insert is between 100mm and 200mm. A gap between the silicon carbide flow channel insert and the inner wall of the spiral annular main channel is between 3mm and 10mm.

[0070] Finally, it should be noted that the above specific embodiments are only used to explain in detail the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above is only a specific implementation method of the present invention and is not used to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above specific embodiments, ordinary technicians in this field should understand that it is still possible to modify the technical solutions described in the above embodiments, or to replace or improve some or all of the technical features therein. These modifications, equivalent replacements, and improvements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered by the scope of the claims and description of the present invention.

Claims

1. A liquid lithium-lead self-cooling blanket with low MHD pressure drop, characterized in that: include: The outer cladding includes an outer cladding annular arcuate main flow channel (3), wherein the outer cladding annular arcuate main flow channel (3) includes a first wall region flow channel and a tritium breeding region flow channel sequentially arranged from the inside to the outside in the radial direction; An inner cladding layer, comprising an inner cladding annular arc-shaped main flow channel (6); The flow directions of the outer cladding annular arc main channel (3) and the inner cladding annular arc main channel (6) are parallel to or tend to be parallel to the direction of the magnetic field lines of the annular magnetic field of the fusion reactor, the outer cladding annular arc main channel (3) and the inner cladding annular arc main channel (6) are provided with flow channel plug-ins at the turning points of the inlet and outlet, and the poloidal height a of the outer cladding annular arc main channel (3) and the inner cladding annular arc main channel (6) is greater than the radial width b.

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

3. The liquid lithium-lead self-cooling blanket with low MHD pressure drop according to claim 1, characterized in that: A plurality of branch flow channels are radially arranged side by side in the outer cladding annular arc-shaped main flow channel (3), and the number of the branch flow channels is greater than 2.

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

5. A liquid lithium-lead self-cooling blanket with low MHD pressure drop according to any one of claims 1 to 4, characterized in that: The width of the flow channel from the first wall region to the flow channel in the tritium breeding region increases sequentially along the radial direction.

6. A liquid lithium-lead self-cooling blanket with low MHD pressure drop according to any one of claims 1 to 4, characterized in that: The inlet of the outer cladding annular arc-shaped main channel (3) is higher than the outlet in the polar direction.

7. The liquid lithium-lead self-cooling blanket with low MHD pressure drop according to claim 1, characterized in that: A plurality of branch flow channels are arranged side by side along the polar direction in the inner cladding annular arc-shaped main flow channel (6), and the number of the branch flow channels is greater than 2.

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

9. The liquid lithium-lead self-cooling blanket with low MHD pressure drop according to claim 3 or 7, characterized in that: In the outer cladding annular arcuate main channel (3) and the inner cladding annular arcuate main channel (6), the ratio of the polar height a to the radial width b of the branch flow channel is between 2 and 8.

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

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