Supercritical carbon dioxide cooled lead breeder blanket structure

Abstract

This invention discloses a supercritical carbon dioxide-cooled lead breeder blanket structure, belonging to the field of fusion reactor blankets, comprising a sector-shaped blanket and multiple breeder units. Each breeder unit includes a U-shaped first wall, a cooling plate, a circumferential steel reinforcing plate, a silicon carbide partition, and multiple backplates. A three-stage coolant manifold is formed between the backplates, with the annular backplate serving as an outlet manifold embedded in the second-stage manifold. The cooling plate is fixed by passing through grooves in the backplate and the circumferential steel reinforcing plate, and the silicon carbide partition is positioned above the cooling plate. The rear region of the breeder zone is formed by the cooling plate, the circumferential steel reinforcing plate, and the third backplate, creating a first internal cavity filled with lithium lead oxide microspheres as a tritium breeder. The front region of the breeder zone is formed by the U-shaped first wall, the circumferential steel reinforcing plate, the cooling plate, and the silicon carbide partition, creating a second internal cavity filled with lanthanum lead oxide microspheres. Advanced ceramic breeder microspheres are filled in the smaller front cavity. This invention significantly improves the tritium breeder ratio by optimizing the cavity layout and material configuration.

Description

Technical Field

[0001] This invention belongs to the field of fusion reactor blankets, specifically relating to a supercritical carbon dioxide cooled lead breeding blanket structure. Background Technology

[0002] As a crucial direction for future clean energy, fusion energy faces a core challenge: achieving a self-sustaining cycle of tritium fuel. Solid-state tritium breeder blankets have become a mainstream research focus due to their structural stability and operational safety. Traditional solid-state blankets typically employ lithium orthosilicate (Li4SiO4) or lithium titanate (Li2TiO3) as tritium breeder materials, supplemented with beryllium (Be) as a neutron multiplier to increase neutron flux and improve the tritium breeder ratio (TBR). However, beryllium suffers from high toxicity, resource scarcity, and high cost, severely limiting the economic viability and deployability of fusion reactors.

[0003] Based on the form of the tritium breeder used in the blanket, blankets can be divided into solid-state and liquid-state breeder blankets. Liquid-state breeder blankets use liquid lithium-lead as a neutron multiplier, tritium breeder, and coolant. However, liquid lithium-lead has a high flow rate, and in a strong magnetic field environment, the magnetohydrodynamic (MHD) effect between lithium-lead and the conductive steel wall is very strong. The conductive current cuts through the magnetic field, significantly increasing the voltage drop and thus reducing power generation efficiency. In addition, liquid lithium-lead is corrosive to structural materials, making long-term operation difficult. Therefore, some fusion institutions at home and abroad have focused on solid-state breeder blankets as their main research direction. Solid-state breeder blankets mainly use beryllium microspheres as neutron multipliers and lithium orthosilicate and lithium aluminate ceramic microspheres as tritium breeders, which has advantages such as good structural and material compatibility and the absence of MHD effect. However, beryllium resources in nature are limited, and the market price is high, which makes this blanket scheme lack economic competitiveness. In addition, the solid-state cladding has a complex structural design, and its core components such as the first wall, cooling plate, and cover plate all require cooling. The first wall bears the highest heat load and must be the primary target for cooling, while the cover plate and cooling plate are cooled sequentially. This cooling priority setting increases the number of coolant headers required in the system, significantly reducing the effective space of the breeding zone and consequently lowering the tritium breeding ratio, thus failing to achieve the core objective of tritium self-sufficiency.

[0004] To improve cooling efficiency, existing technologies often incorporate multi-layer coolant manifolds and complex flow channels in the cladding backplate area. For example, CN107945886B proposes an "M"-shaped six-layer backplate structure, while CN107195332B employs a dual-loop eight-manifold cross-cooling system. While these designs offer some optimization in terms of thermal-hydraulic aspects, the numerous non-functional structures (such as multi-stage manifolds and distribution chambers) encroach on valuable breeding zone space, resulting in a reduction in effective breeding volume and thus limiting further improvements in TBR. Furthermore, some solutions, such as CN113593727B, which utilizes liquid lithium-lead cladding and possesses self-breeding and self-multiplication capabilities, face engineering challenges such as large magnetohydrodynamic (MHD) pressure drops and strong material corrosivity. Although CN107093466B integrates tritium extraction and cooling functions using a sleeve-type helium-cooled structure, its material system still relies on traditional breeding / multiplication combinations, failing to address the cost and safety bottlenecks associated with beryllium.

[0005] In summary, existing solid-state cladding technologies generally suffer from key problems such as structural redundancy leading to limited growth space, reliance on expensive and toxic beryllium-based multiplier materials, and failure to balance high TBR with good economic efficiency. There is an urgent need for a new cladding configuration that simplifies the structure while achieving material system innovation, thereby breaking through the dual constraints of TBR and cost. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a supercritical carbon dioxide-cooled lead breeding blanket structure, employing a two-layer coolant manifold. The supercritical carbon dioxide outlet manifold is embedded in the middle of the second-stage supercritical carbon dioxide coolant manifold in a ring-shaped configuration, thereby reducing the space of the coolant manifold area and increasing the space of the breeding zone, thus increasing the tritium breeding ratio to achieve tritium breeding. The neutron multiplier is lanthanum lead oxide (LaPb3), which has a high melting point and can maintain a solid state inside the breeding blanket. The tritium breeding agent is lithium octa-lead oxide (OLP), whose presence of lead gives it both neutron multiplication and tritium breeding capabilities. Furthermore, tritium has a high diffusion coefficient and short residence time in irradiated lithium octa-lead oxide, which is beneficial to the safety of the breeding blanket and tritium self-sufficiency.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A supercritical carbon dioxide cooled lead breeding cladding structure includes a sector-type cladding structure, each sector containing multiple breeding units. Each breeding unit includes a U-shaped first wall, a cooling plate, a circumferential steel reinforcing plate, a silicon carbide partition, a first back plate, a second back plate, a third back plate, and an annular back plate fixed on the second back plate, all welded and fixed together. A first-stage coolant inlet manifold is formed between the first and second back plates, a second-stage coolant manifold is formed between the second and third back plates, and the annular back plate serves as a third-stage coolant outlet manifold. Within the U-shaped groove of the first U-shaped wall, a first back plate, a second back plate, an annular back plate, a third back plate, and a circumferential steel reinforcing plate are arranged radially in sequence. The annular back plate, the third back plate, and the circumferential steel reinforcing plate are provided with grooves. A cooling plate passes through the grooves and is fixed to the first U-shaped wall. A silicon carbide partition is located above the cooling plate. A first internal cavity is formed between the cooling plate, the circumferential steel reinforcing plate, and the third back plate in the rear region of the breeding zone, filled with lithium lead oxide microspheres as tritium breeding agents. A second internal cavity, including a third cavity and a fourth cavity, is formed between the first U-shaped wall, the circumferential steel reinforcing plate, the cooling plate, and the silicon carbide partition at the front end of the breeding zone. The volume of the third cavity is larger than that of the fourth cavity. The third cavity is filled with lanthanum lead oxide microspheres as neutron multipliers. The fourth cavity is filled with advanced ceramic breeder microspheres as tritium breeding agents.

[0009] Furthermore, cover plates are welded to the top and bottom of the sector, with the bottom cover plate connecting the coolant inlet and the tritium purge gas inlet, and the top cover plate connecting the coolant outlet and the tritium purge gas outlet.

[0010] Furthermore, the annular backplate is shaped like a racetrack and is embedded in the middle of the second-stage coolant header through reinforcing ribs.

[0011] Furthermore, the cooling plate comprises multiple layers, with gaps between adjacent cooling plates in the same layer and between the cooling plate and the U-shaped first wall for the flow of tritium purging gas.

[0012] Furthermore, multiple grooves are provided on the circumferential steel reinforcing plate to facilitate the flow of tritium purging gas.

[0013] Furthermore, both the U-shaped first wall and the cooling plate are equipped with rectangular cooling channels. Supercritical carbon dioxide coolant enters from the coolant inlet, is distributed into the U-shaped first wall through the first-stage coolant inlet header, is collected in the second-stage coolant header through the U-shaped first wall, is distributed into the cooling plate through the second-stage coolant header, is collected in the third-stage coolant outlet header formed by the cooling plate and flows out through the coolant outlet.

[0014] Furthermore, the diameter of the lanthanum lead oxide microspheres is 8 mm, the diameter of the advanced ceramic amplified microspheres is 8 mm, and the diameter of the lithium octa-lead oxide microspheres is 8 mm.

[0015] Furthermore, the advanced ceramic amplification microspheres are made of lithium orthosilicate or lithium titanate ceramic materials.

[0016] Furthermore, the U-shaped first wall, cooling plate, circumferential steel reinforcing plate, first back plate, second back plate, third back plate and annular back plate are made of low-activation ferritic martensitic steel.

[0017] Furthermore, the tritium purging gas is a mixture of low-pressure helium and hydrogen.

[0018] Beneficial effects:

[0019] 1. This invention embeds the coolant outlet header in the middle of the second-stage coolant header to form a compact annular racetrack-shaped layout, which greatly reduces the space occupied by the non-breeding structure, maximizes the volume of the breeding region, and effectively improves neutron utilization efficiency and tritium production.

[0020] 2. This invention uses high-melting-point, low-toxicity lanthanum lead oxide (LaPb3) to replace beryllium as the neutron multiplier in the front region. This not only avoids the toxicity and scarcity issues of beryllium but also improves the material's stability under high-temperature irradiation. Lanthanum lead oxide has a high melting point and can maintain a solid state within the breeding blanket. Advanced ceramic breeder Li2SiO4 / Li2TiO3 microspheres with a diameter of 8mm are used as the tritium breeder at the front of the breeding region, while lithium octa-lead oxide (Li2Pb8O3) with a diameter of 8mm is used in the rear region. 11 (OLP) microspheres serve as tritium multipliers. The presence of lead in OLP endows them with neutron multiplication and tritium multiplication capabilities. Furthermore, tritium exhibits a high diffusion coefficient and short residence time in irradiated lithium octa-lead oxide, which is beneficial for the safety of the multiplication blanket and tritium self-sufficiency.

[0021] 3. This invention introduces lithium octa-lead oxide (OLP, Li2Pb8O) with dual functions of neutron multiplication and tritium multiplication at the rear of the breeding region. 11 Its excellent tritium diffusion performance helps reduce local tritium retention, improve tritium recovery efficiency and operational safety.

[0022] 4. This invention features only two cooling manifolds, using supercritical carbon dioxide (sCO2) as a highly efficient cooling medium. The system boasts high integration and excellent thermal performance, while simultaneously reducing manufacturing complexity and maintenance costs. Specifically, the supercritical carbon dioxide outlet manifold is embedded in the middle of the second-stage supercritical carbon dioxide coolant manifold in a ring-shaped design. This reduces the space required for the coolant manifold area while increasing the space for the tritium breeding zone, thereby increasing the tritium breeding ratio and achieving tritium breeding. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the outer cladding sector, inner cladding sector, and proliferation unit of the present invention.

[0024] Figure 2 This is a cross-sectional view of the proliferation unit of the present invention.

[0025] Figure 3 This is an exploded view of the proliferation unit of the present invention.

[0026] Figure 4 This is a partial cross-sectional view of the proliferation unit of the present invention.

[0027] Figure 5 This is a schematic diagram of the coolant flow in the proliferation unit of the present invention.

[0028] Figure 6 This is a schematic diagram of the annular back plate and reinforcing rib structure.

[0029] Figure 7 This is a schematic diagram of the cooling plate structure and a schematic diagram of the cooling flow channels.

[0030] Figure 8 This is a schematic diagram of the U-shaped first wall structure and a schematic diagram of the coolant flow channel.

[0031] Figure 9 This is a graph showing the variation of the tritium breeding ratio with the size of the tritium breeding region.

[0032] The attached figures are labeled as follows: 1-outer cladding segment; 2-breeding unit; 3-U-shaped first wall; 4-first back plate; 5-second back plate; 6-annular back plate; 7-third back plate; 8-cooling plate; 9-circumferential steel reinforcing plate; 10-silicon carbide partition; 11-lithium lead oxide ball bed; 12-lanthanum lead oxide ball bed; 13-advanced ceramic breeder ball bed; 14-cover plate; 15-first stage coolant inlet manifold; 16-second stage coolant manifold; 17-third stage coolant outlet manifold; 18-coolant inlet; 19-tritium purge gas inlet; 20-coolant outlet; 21-tritium purge gas outlet; 22-reinforcing rib; 23-inner cladding segment; 24-first internal cavity; 25-second internal cavity. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0034] like Figures 1-4 As shown, the present invention provides a supercritical carbon dioxide cooled lead breeding cladding structure with a large breeding ratio. It adopts a sector-type cladding structure, namely an outer cladding sector 1 and an inner cladding sector 23. Each outer cladding sector 1 and inner cladding sector 23 contains multiple breeding units 2.

[0035] The proliferation unit 2 includes a U-shaped first wall 3, a cooling plate 8, a circumferential steel reinforcing plate 9, a silicon carbide partition 10, a first back plate 4, a second back plate 5, a third back plate 7, and an annular back plate 6. The U-shaped first wall 3, the cooling plate 8, the circumferential steel reinforcing plate 9, the silicon carbide partition 10, the first back plate 4, the second back plate 5, and the third back plate 7 are fixed together by welding.

[0036] The first back plate, the second back plate, the annular back plate, the third back plate and the circumferential steel reinforcing plate are arranged radially in the U-shaped groove of the first U-shaped wall. The annular back plate, the third back plate and the circumferential steel reinforcing plate are provided with transverse grooves. The cooling plate passes through the transverse grooves and is fixed to the first U-shaped wall. The silicon carbide partition is located above the cooling plate. The first back plate 4 and the second back plate 5 form a first-stage coolant inlet manifold 15, and the second back plate 5 and the third back plate 7 form a second-stage coolant manifold 16.

[0037] The top and bottom of the outer cladding segment 1 and the inner cladding segment 23 are respectively welded with cover plates 14. The bottom cover plate 14 is connected to a coolant inlet 18 and a tritium purge gas inlet 19, and the top cover plate 14 is connected to a coolant outlet 20 and a tritium purge gas outlet 21.

[0038] like Figure 6 As shown, the annular back plate 6 serves as the third-stage coolant outlet manifold 17 and is welded to the second back plate 5 via reinforcing ribs 22. The reinforcing ribs 22 have grooves for coolant flow.

[0039] like Figure 7 As shown, the cooling plate 8 comprises multiple layers, and there are gaps between adjacent cooling plates and between the cooling plates and the U-shaped first wall 3 for the flow of tritium purging gas.

[0040] like Figure 5 , Figure 7 , Figure 8 As shown, both the U-shaped first wall 3 and the cooling plate 8 are equipped with rectangular cooling channels. Supercritical carbon dioxide is used as the coolant. The supercritical carbon dioxide coolant enters from the coolant inlet 18, is distributed into the U-shaped first wall 3 through the first-stage coolant inlet header 15, and is collected in the second-stage coolant header 16 through the U-shaped first wall 3. It is then distributed into the cooling plate 8 through the second-stage coolant header 16, and is collected in the third-stage coolant outlet header 17 formed by the annular back plate 6 through the cooling plate 8. It then flows out of the blanket structure through the coolant outlet 20, carrying away the nuclear heat of the blanket breeding region.

[0041] The circumferential steel reinforcing plate 9 has multiple grooves for the flow of tritium purging gas; multiple first internal cavities 24 are formed between the cooling plate 8, the circumferential steel reinforcing plate 9, and the third back plate 7 in the rear region of the breeding zone, and the cavities are filled with lithium lead oxide (Li2Pb8O). 11The microspheres serve as a tritium multiplier, forming an octa-lithium lead oxide spherical bed 11. Multiple second internal cavities 25 are formed at the front end of the multiplication zone between the U-shaped first wall 3, the circumferential steel reinforcing plate 9, the cooling plate 8, and the silicon carbide partition 10. Each second internal cavity 25 includes a third cavity with a larger front-end area and a fourth cavity with a smaller front-end area. The third cavity is filled with lanthanum lead oxide (LaPb3) microspheres as a neutron multiplier, forming a lanthanum lead oxide spherical bed 12. The fourth cavity is filled with advanced ceramic multiplier Li2SiO4 / Li2TiO3 microspheres as a tritium multiplier, forming an advanced ceramic multiplier spherical bed 13.

[0042] Preferably, the U-shaped first wall 3, cooling plate 8, circumferential steel reinforcing plate 9, first back plate 4, second back plate 5, third back plate 7 and annular back plate 6 are made of low-activation ferritic martensitic steel.

[0043] Preferably, the tritium purging gas is a mixture of low-pressure helium and hydrogen, which flows slowly within the solid-state breeding sphere bed and carries away the tritium produced by the breeding process.

[0044] like Figure 9 As shown, the tritium breeding ratio increases with the increase in the size of the breeding region. This invention embeds the annular third-stage coolant outlet header between the second-stage coolant headers, which increases the breeding region's spatial thickness by 100 mm and increases the tritium breeding ratio by 0.02. This indicates that increasing the size of the breeding region can effectively improve the tritium breeding capability of the blanket, contributing to better performance assurance for tritium self-sufficiency in fusion reactors.

[0045] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A supercritical carbon dioxide cooled lead breeding cladding structure, characterized in that, The structure includes a segmented cladding structure, with each segment containing multiple multiplication units. Each multiplication unit comprises a U-shaped first wall, a cooling plate, a circumferential steel reinforcing plate, a silicon carbide partition, a first back plate, a second back plate, a third back plate, and an annular back plate fixed to the second back plate, all welded and fixed together. A first-stage coolant inlet manifold is formed between the first and second back plates, a second-stage coolant manifold is formed between the second and third back plates, and the annular back plate serves as a third-stage coolant outlet manifold. The first back plate, second back plate, annular back plate, third back plate, and circumferential steel reinforcing plate are arranged radially within the U-shaped groove of the U-shaped first wall. The three backplates and the circumferential steel reinforcing plate are provided with grooves. The cooling plate passes through the grooves and is fixed to the U-shaped first wall. The silicon carbide partition is located above the cooling plate. The cooling plate, the circumferential steel reinforcing plate and the third backplate form a first internal cavity in the rear region of the breeding zone, which is filled with lithium lead oxide microspheres as tritium breeding agent. The U-shaped first wall, the circumferential steel reinforcing plate, the cooling plate and the silicon carbide partition form a second internal cavity in the front end of the breeding zone, which includes a third cavity and a fourth cavity. The volume of the third cavity is larger than that of the fourth cavity. The third cavity is filled with lanthanum lead oxide microspheres as neutron multipliers. The fourth cavity is filled with advanced ceramic breeder microspheres as tritium breeding agent.

2. The supercritical carbon dioxide cooled lead breeding cladding structure according to claim 1, characterized in that, Cover plates are welded to the top and bottom of the sector segment respectively.

3. The supercritical carbon dioxide cooled lead breeding cladding structure according to claim 1, characterized in that, The annular backplate is shaped like a racetrack and is embedded in the middle of the second-stage coolant header through reinforcing ribs.

4. The supercritical carbon dioxide cooled lead breeding cladding structure according to claim 1, characterized in that, The cooling plate consists of multiple layers, with gaps between adjacent cooling plates in the same layer and between the cooling plate and the U-shaped first wall for the flow of tritium purging gas.

5. The supercritical carbon dioxide cooled lead breeding cladding structure according to claim 1, characterized in that, Multiple grooves are provided on the circumferential steel reinforcing plate to allow for the flow of tritium purging gas.

6. The supercritical carbon dioxide cooled lead breeding cladding structure according to claim 1, characterized in that, Both the U-shaped first wall and the cooling plate are equipped with rectangular cooling channels. Supercritical carbon dioxide coolant enters from the coolant inlet, is distributed through the first-stage coolant inlet header into the U-shaped first wall, is collected through the U-shaped first wall into the second-stage coolant header, is distributed through the second-stage coolant header into the cooling plate, is collected through the cooling plate into the third-stage coolant outlet header formed by the annular back plate, and flows out through the coolant outlet.

7. The supercritical carbon dioxide cooled lead breeding cladding structure according to claim 2, characterized in that, The bottom cover plate connects the coolant inlet and the tritium purge gas inlet, and the top cover plate connects the coolant outlet and the tritium purge gas outlet.

8. The supercritical carbon dioxide cooled lead breeding cladding structure according to claim 1, characterized in that, The advanced ceramic amplification microspheres are made of lithium orthosilicate or lithium titanate ceramic materials.

9. The supercritical carbon dioxide cooled lead breeding cladding structure according to claim 1, characterized in that, The U-shaped first wall, cooling plate, circumferential steel reinforcing plate, first back plate, second back plate, third back plate, and annular back plate are made of low-activation ferritic martensitic steel.

10. A supercritical carbon dioxide cooled lead breeding cladding structure according to claim 4, characterized in that, The tritium purging gas is a mixture of low-pressure helium and hydrogen.

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