High burnup spent fuel assembly cask based on passive heat removal and composite shielding

Abstract

This invention discloses a high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding, belonging to the field of nuclear fuel transportation and storage technology. It aims to solve the problems of high risks associated with active heat dissipation in existing containers, the coupling contradiction between passive heat dissipation and composite shielding, and reliance on imported core technologies. It includes a cylindrical assembly, a neutron shielding assembly, a basket assembly, a passive heat dissipation assembly, and a cover assembly. The cylindrical assembly and the neutron shielding assembly respectively shield gamma rays and neutrons, forming a composite shielding system. The basket assembly loads the high-burnup spent fuel assembly through a storage sleeve. The heat sink of the passive heat dissipation assembly connects the cylindrical assembly and the outer shell of the neutron shielding assembly and contacts the neutron shielding layer. The cover assembly is sealed and fitted to the cylindrical assembly. This invention constructs a passive heat dissipation system, resolving the coupling contradiction between heat dissipation and shielding, achieving efficient synergy between the two, providing core support for the domestic production of dry transfer containers outside the pool, and aligning with the passive safety design concepts of third- and fourth-generation nuclear power plants.

Description

Technical Field

[0001] This invention belongs to the field of nuclear fuel transportation and storage technology, specifically relating to a high burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding. Background Technology

[0002] With the rapid development of nuclear power technology in my country, 14-foot (approximately 4.27-meter) long high-burnup spent fuel assemblies have become the mainstream. These spent fuels are characterized by high radioactivity and high decay heat, and their safe transfer and temporary storage are key aspects of nuclear power plant operation and maintenance.

[0003] Existing spent fuel transport containers must strictly maintain the liquid state of the internal cooling medium, such as boron-containing water, during transport to prevent the decay heat released from spent fuel assemblies from causing the internal water to boil. Especially when loading spent fuel assemblies with high burnup and short cooling cycles, their significant internal heat release makes controlling the cooling medium temperature below 100°C a core design constraint. Currently, achieving this technical requirement heavily relies on the continuous operation of external active cooling systems such as forced circulation cooling systems. This inevitably introduces an inherent dependence on the reliability of active equipment, external power supply, and system interfaces, posing significant safety hazards.

[0004] Drawing lessons from the Fukushima nuclear accident and the passive safety design concepts of third- and fourth-generation nuclear reactors, the nuclear power industry is continuously evolving towards a higher level of inherent safety. Developing and integrating passive cooling technologies has become an inevitable choice for improving the safety and reliability of spent fuel transfer containers and compensating for the vulnerabilities of existing active cooling systems. It is also a core technological foundation for implementing the safety standards of advanced third- and fourth-generation nuclear power plants. However, in the field of spent fuel transfer containers, the engineering application of passive cooling technologies is still lacking, and related technology research and development faces multiple bottlenecks.

[0005] The most critical technical challenge lies in the fact that the transport of high-burnup spent fuel places stringent demands on both efficient passive heat dissipation and comprehensive composite radiation shielding. These two functions are inherently contradictory in structural design, and current technologies have consistently failed to achieve efficient synergy between them. For example, the structural integrity of the shielding system can easily obstruct heat dissipation paths, leading to a significant decrease in passive heat dissipation efficiency. Conversely, the arrangement of the heat dissipation structure can easily disrupt the continuity and uniformity of the shielding layer, creating radiation shielding blind spots. Furthermore, improper heat sink placement can exacerbate uneven material filling and obstructed heat dissipation channels. This "one-sided" technical dilemma makes it difficult for existing solutions to simultaneously achieve efficient composite radiation shielding while constructing a passive heat dissipation architecture, failing to achieve simultaneous optimization of heat dissipation efficiency and shielding performance. This has become the core technical bottleneck in the integrated design of passive heat dissipation and composite shielding.

[0006] In addition, existing spent fuel transfer containers suffer from insufficient sealing redundancy, with some sealing surfaces employing a single structural design and incomplete leak detection coverage, making reliable monitoring under all operating conditions and scenarios impossible. Furthermore, the core technologies of dry transfer containers outside the pool largely rely on imports. The lack of domestically produced technology not only leads to high equipment procurement costs and long maintenance and spare parts supply cycles, severely impacting the operation and maintenance efficiency of nuclear power plants, but also poses a potential risk to the independent security of my country's nuclear power supply chain. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide a high-burnup spent fuel transport container based on passive heat dissipation and composite shielding, so as to fill the gap in the engineering application of passive heat dissipation technology in the field of spent fuel transport, resolve the coupling contradiction between passive heat dissipation and all-dimensional composite radiation shielding in structural design, achieve simultaneous optimization of heat dissipation efficiency and shielding performance, improve the sealing redundancy and leakage detection capability of the container, meet the inherent safety requirements of high-burnup spent fuel transport, and realize the localization of the core technology of dry transport container outside water tank.

[0008] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0009] A high-burnup spent fuel assembly transport container based on passive heat dissipation and composite shielding includes: a cylindrical assembly, which is a vertical cylindrical structure with an open end, forming a cylindrical receiving cavity inside for accommodating a basket assembly; the cylindrical assembly can shield gamma rays and provide structural support; a neutron shielding assembly connected to the cylindrical assembly, including a shell coaxially sleeved on the outside of the cylindrical assembly, and a neutron shielding layer filled between the shell and the outer surface of the cylindrical assembly; and a basket assembly disposed within the cylindrical receiving cavity of the cylindrical assembly, including multiple baskets for loading... Storage sleeve for high-burnup spent fuel assemblies; passive heat dissipation assembly, including a support plate, a heat transfer plate, and heat dissipation fins distributed circumferentially along the outer surface of the cylindrical assembly, all located within the basket assembly; the storage sleeve is positioned and fitted to the support plate, the heat transfer plate is fitted to the support plate and adapted to the inner cavity of the cylindrical assembly, one end of the heat dissipation fins is fixedly connected to the outer surface of the cylindrical assembly, and the other end is fixedly connected to the inner side of the outer shell of the neutron shielding assembly, with the heat dissipation fins in contact with the neutron shielding layer; cover assembly, located at the open end of the cylindrical assembly, and sealed and adapted to the cylindrical assembly.

[0010] This invention, for the first time in the field of spent fuel transport containers, constructs a full-path passive heat dissipation system. Through the coordinated internal and external layout of the support plate and heat transfer plate inside the basket assembly and the heat dissipation fins on the outer surface of the cylinder assembly, it fills the gap in the engineering application of passive heat dissipation technology in the field of spent fuel transport, gets rid of the dependence of existing technologies on external active heat dissipation systems, and eliminates the safety hazards caused by equipment reliability, power supply and system interface from the root.

[0011] Secondly, the present invention cleverly resolves the structural coupling contradiction between passive heat dissipation and composite shielding through the integrated connection design of heat sink, neutron shielding layer and neutron shielding component shell, and achieves deep integration of heat dissipation structure and shielding system; relying on the synergistic effect of cylinder component and neutron shielding component, while ensuring efficient operation of passive heat dissipation, it achieves full-dimensional composite shielding of gamma rays and neutrons, and solves the technical dilemma of "one increasing while the other decreases" between the two.

[0012] Furthermore, through the precise loading structure of the basket assembly and the highly reliable sealing design of the cover assembly, this invention ensures the safety and stability of the high-burnup spent fuel transfer process. Its passive integrated design aligns with the safety concepts of third- and fourth-generation nuclear power plants, providing core technical support for the localization of dry transfer containers outside the pool.

[0013] Specifically, the passive heat dissipation path of the present invention is as follows: the decay heat generated by the spent fuel assembly is dissipated into the atmosphere by passing through the storage sleeve → support plate → heat transfer plate → cylinder assembly → neutron shielding layer → heat sink → outer shell in sequence. This path relies on the triple heat transfer mechanism of radiation, convection and conduction to achieve efficient and continuous passive removal of decay heat.

[0014] Furthermore, the outer shell of the neutron shielding assembly and the outer surface of the cylindrical assembly enclose a ring-shaped shielding cavity; heat sinks extend axially along the cylindrical assembly and are arranged within the ring-shaped shielding cavity, with equal circumferential spacing between adjacent heat sinks, dividing the ring-shaped shielding cavity into multiple circumferentially uniformly distributed neutron shielding filling chambers; each neutron shielding filling chamber is used to fill neutron shielding material to form a neutron shielding layer, and the outer surface of the heat sinks is in close contact with the neutron shielding material. Here, "equal circumferential spacing" between adjacent heat sinks means that the arc length distance between two adjacent heat sinks in the circumferential direction of the cylindrical assembly is equal.

[0015] This design ensures uniform filling of neutron shielding material, making radiation protection more stable, and further optimizes the heat conduction path through the structure of the heat sink and the shielding material being tightly bonded. It completely solves the technical pain point of mutual interference between the shielding layer and the heat dissipation path in traditional designs, and achieves the dual effect of enhanced composite shielding performance and improved passive heat dissipation efficiency.

[0016] Furthermore, the heat sinks are offset by 5-15° in the radial direction relative to the central axis of the cylindrical assembly, and the offset angles of adjacent heat sinks are consistent.

[0017] This design effectively increases the contact area between the heat sink and the neutron shielding material, optimizes the thermal convection channels within the shielding cavity, improves the uniformity and efficiency of passive heat dissipation, and ensures the stability of the internal temperature field of the container.

[0018] Furthermore, the heat sink is a stainless steel-aluminum composite heat sink with a thickness of 10-16mm.

[0019] This composite structure, combined with its thickness design, balances high thermal conductivity with structural strength and radiation resistance, making it suitable for the harsh operating conditions of transporting high-fuel-consumption spent fuel and ensuring the long-term stable operation of the heat dissipation components.

[0020] Furthermore, the neutron shielding assembly also includes a top neutron shielding sleeve and a bottom neutron shielding sleeve; the top neutron shielding sleeve and the bottom neutron shielding sleeve are respectively formed by enclosing an upper end plate and a lower end plate of an annular shielding cavity, and are disposed on both sides of the axial direction of the neutron shielding layer, and both the top neutron shielding sleeve and the bottom neutron shielding sleeve are filled with neutron shielding material.

[0021] This design fills the axial protection blind spot of the main neutron shielding layer, achieving all-round neutron shielding of the container without dead angles; the integrated design of the end plate improves the stability of the assembly structure and ensures the uniformity and stability of the overall neutron shielding performance of the container.

[0022] Furthermore, the cover assembly includes: an inner cover, positioned and assembled inside the opening end of the cylinder assembly, with an automatic gripping positioning boss at its center, and a gripping cover on the outside of the automatic gripping positioning boss, the gripping cover being fixedly connected to the inner cover; an inner cover clamping flange, located above the inner cover, fixedly connected to the upper end face of the cylinder assembly, for axially clamping the inner cover; and an outer cover, located above the inner cover clamping flange, fixedly connected to the upper end face of the cylinder assembly, forming an axial limiting constraint on the inner cover clamping flange.

[0023] The three-layer cover structure enhances sealing stability and structural reliability through a dual design of compression and limiting; the automatic gripping structure adapts to automated operation, improving the efficiency of container disassembly and spent fuel loading, and reducing the risk of human intervention.

[0024] Furthermore, the inner cover is provided with an air inlet and a water outlet, and the upper and lower circumferential parts of the cylinder assembly are respectively provided with water outlets. The air inlet of the inner cover is equipped with a quick-connect gas delivery connector, and the water outlets of the inner cover and the cylinder assembly are all equipped with quick-connect liquid delivery connectors, and each outlet is provided with a suitable cover. The sealing mating surfaces of the outer cover and the inner cover clamping flange, the inner cover clamping flange and the inner cover, the inner cover and the cylinder assembly, and the sealing mating surfaces of each outlet cover are all provided with two concentric sealing grooves, and a sealing ring is embedded in each sealing groove to form two concentric sealing rings. An inspection hole is provided between the two concentric sealing rings.

[0025] The design, with its multi-functional orifice and quick connector configuration, is adaptable to various operating scenarios for the container; the double sealing rings on the fully sealed surface and the detection holes form a dual sealing guarantee and real-time leakage monitoring capability, effectively preventing the leakage of radioactive materials and improving the safety protection level of the container.

[0026] Furthermore, the cylindrical assembly includes an annular inner cylinder and a bottom end cap fixedly connected to the bottom of the annular inner cylinder. The bottom end cap and the annular inner cylinder enclose a cylindrical receiving cavity. Multiple lifting trunnions are provided circumferentially on the upper part of the annular inner cylinder. The multiple lifting trunnions are evenly arranged along the circumference of the annular inner cylinder. The outer end of the lifting trunnions is provided with a safety stop to prevent the lifting device from slipping.

[0027] This design ensures the overall structural strength of the container, while the circumferentially uniform lifting trunnions and safety stops ensure balanced force during lifting and transportation, improving the stability and safety of container lifting and transportation, and adapting to heavy-duty handling requirements.

[0028] Furthermore, the bottom end cap of the cylindrical assembly is provided with at least two rotating trunnions on the outside to enable the container to flip between horizontal and vertical positions; the top end face of the annular inner cylinder of the cylindrical assembly is provided with multiple positioning protrusions, which are evenly arranged circumferentially for positioning the outer cover and the middle position of the inner cover and the flange of the extraction device.

[0029] The rotating trunnion allows for flexible adjustment of the container's posture to adapt to different operational scenarios; the circumferential positioning protrusion provides a unified positioning benchmark for the assembly of multiple components, ensuring assembly coaxiality and further enhancing sealing performance and ease of operation.

[0030] Furthermore, the suspended platform assembly also includes a top plate, a bottom plate, and a threaded rod; a support plate and a heat transfer plate are located between the top plate and the bottom plate, and the threaded rod passes through and locks the bottom plate, top plate, support plate, and heat transfer plate, with adjacent plates maintaining a distance through positioning blocks; a storage sleeve is used to load 14-foot-high spent fuel assemblies and is positioned and supported on the support plate.

[0031] The design forms a robust basket frame structure, providing reliable support for the storage sleeve; the close fit between the storage sleeve and the support plate enhances the internal heat transfer path, ensuring the loading stability of the high-burnup spent fuel assembly and improving the efficiency and reliability of passive heat dissipation.

[0032] The beneficial effects of this invention are as follows: For the first time, it innovatively constructs a full-path passive heat dissipation system in the field of high-burnup spent fuel transport containers. Relying on a triple heat transfer mechanism of radiation, convection, and conduction, it achieves efficient and passive removal of decay heat, filling the gap in the engineering application of passive heat dissipation technology in this field. It eliminates dependence on external active heat dissipation systems, enhances the inherent safety of the container, and aligns with the passive safety design concepts of third- and fourth-generation nuclear power plants. Simultaneously, through the core structural design of the heat sink, it resolves the natural coupling contradiction between passive heat dissipation and composite shielding, achieving deep integration and synergistic efficiency between the two. While ensuring heat dissipation efficiency, it achieves full-dimensional composite shielding against gamma rays and neutrons, completely solving the technical dilemma of the trade-off between the two in existing technologies. Furthermore, through an integrated design of high-redundancy sealing, precise loading, and convenient operation, this invention ensures the safe and stable transport of high-burnup spent fuel, providing core technical support for the localization of dry transport containers outside the water pool and breaking the foreign technological monopoly.

[0033] The present invention, a high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding, is disclosed in detail below with reference to the embodiments and reference numerals in the accompanying drawings. Attached Figure Description

[0034] Figure 1 This is an external view of the transport container of the present invention;

[0035] Figure 2 for Figure 1 AA cross-section view;

[0036] Figure 3 for Figure 1 The C-direction view;

[0037] Figure 4 for Figure 3 BB cross-section;

[0038] Figure 5 for Figure 4 Enlarged view of a portion at point A;

[0039] Figure 6 for Figure 1 View from direction C (with the outer cover removed);

[0040] Figure 7 for Figure 1 View from direction C (outer cover removed, inner cover clamping flange, gripping cover).

[0041] Figure 8 for Figure 1 View from direction C (only the basket is shown);

[0042] Figure 9 This is an external view of the cylindrical body assembly and neutron shielding assembly structure of the present invention;

[0043] Figure 10 for Figure 9 GG cross-section;

[0044] Figure 11 This is a schematic diagram showing the distribution of the neutron shielding filling chamber in this invention;

[0045] Figure 12 for Figure 9 EE cross-section;

[0046] Figure 13 for Figure 9 FF cross-sectional view;

[0047] Figure 14 This is a schematic diagram showing the distribution of the safety relief valve of the present invention;

[0048] Figure 15 for Figure 9 The D-direction view;

[0049] Figure 16 for Figure 14 HH cross-section diagram;

[0050] Figure 17 for Figure 14 Section II;

[0051] Figure 18 This is a schematic diagram of the suspended platform assembly structure of the present invention;

[0052] Figure 19 for Figure 18 A magnified view of a portion of point I;

[0053] Figure 20 This is a schematic diagram of the installation structure of the storage sleeve, fuel assembly support plate, and top plate of the present invention.

[0054] Figure Labels

[0055] 1. Upper annular inner cylinder; 2. Lower annular inner cylinder; 3. Bottom end cap; 4. Lifting trunnion; 5. Rotating trunnion; 6. Outer shell; 7. Upper end section; 8. Lower end section; 9. Upper end plate; 10. Lower end plate; 11. Positioning protrusion; 12. Cylindrical receiving cavity; 13. Annular shielding cavity; 14. Neutron shielding filling chamber; 15. Shear block; 16. Neutron shielding layer; 17. Top neutron shielding sleeve; 18. Bottom neutron shielding sleeve; 19. Safety relief valve; 20. Top plate; 21. Bottom plate; 22. Storage sleeve; 23. Threaded rod; 24. Positioning block; 25. Fuel assembly support. 26. Storage sleeve support plate; 27. Support plate; 28. Heat transfer plate; 29. ​​Heat sink; 30. Storage sleeve mounting hole; 31. Top plate reinforcing beam; 32. Sheet positioning notch; 33. Inner cover; 34. Inner cover clamping flange; 35. Outer cover; 36. Air inlet; 37. Water hole; 38. Hole cover; 39. Sealing ring; 40. Inspection hole; 41. Inner cover positioning notch; 42. Drain pipe assembly; 43. Positioning boss; 44. Automatic gripping positioning boss; 45. Gripping cover; 46. Screw; 47. Screw hole; 48. Top nut; 49. Lifting screw hole; 50. Trunnion screw cover. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments of this invention. Obviously, the described embodiments are one embodiment of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0057] like Figures 1-20As shown, this invention discloses a high-burnup spent fuel assembly transport container based on passive heat dissipation and composite shielding, including a cylindrical assembly, a neutron shielding assembly, a basket assembly, a passive heat dissipation assembly, and a cover assembly. These components work together to achieve integrated passive heat dissipation and composite shielding, adapting to the safe transport requirements of high-burnup spent fuel. The cylindrical assembly is a vertical cylindrical open structure, with an internal cylindrical receiving cavity 12 to accommodate the basket assembly, while effectively shielding gamma rays and providing support for the overall structure. The neutron shielding assembly is coaxially sleeved on the outside of the cylindrical assembly, including an outer shell 6 and a neutron shielding layer 16 filled between the outer shell 6 and the outer surface of the cylindrical assembly, forming a neutron radiation protection barrier. The basket assembly is located within the cylindrical receiving cavity 12, and multiple storage sleeves 22 enable precise loading and positioning of the high-burnup spent fuel assembly. The passive heat dissipation assembly… It consists of a support plate and a heat transfer plate 28 inside the basket assembly, and heat dissipation fins 29 distributed circumferentially on the outer surface of the cylinder assembly. The storage sleeve 22 is positioned and matched with the support plate. The heat transfer plate 28 is adapted to the support plate and fits against the inner cavity of the cylinder. One end of the heat dissipation fin 29 is fixed to the outer surface of the cylinder assembly, and the other end is fixed to the inner side of the outer shell 6 of the neutron shielding assembly. The heat dissipation fin 29 is in close contact with the neutron shielding layer 16 to form a full-path heat transfer channel. The cover assembly is sealed and assembled at the open end of the cylinder assembly to achieve sealing and protection of the container end.

[0058] This invention is the first to construct a full-path passive heat dissipation system in the field of high burnup spent fuel transport containers. Simultaneously, it forms a gamma-ray-neutron composite shielding system through the cylindrical assembly and the neutron shielding assembly, achieving efficient synergistic protection. Relying on the core structure where the heat sink 29 directly contacts the neutron shielding layer 16 and is connected at both ends to the outer shells of the cylindrical assembly and the neutron shielding assembly respectively, it completely resolves the inherent coupling contradiction between passive heat dissipation and composite shielding in structural design. Without requiring external active equipment and efficiently dissipating spent fuel decay heat, it ensures the protective effect of the composite shielding, avoiding safety hazards related to equipment reliability, power supply, and interface compatibility in active heat dissipation systems. Combined with the precise loading structure of the basket assembly and the highly redundant sealing design of the cover assembly, it comprehensively ensures the safety and stability of the high burnup spent fuel transport process. Its passive integrated design fully conforms to the safety design concepts of third- and fourth-generation nuclear power plants.

[0059] like Figure 2 , Figure 4 , Figure 16 and Figure 17As shown, the cylindrical assembly is integrally formed by welding the upper annular inner cylinder 1, the lower annular inner cylinder 2, and the bottom end cap 3 together, forming a cylindrical receiving cavity 12 to provide housing space for the suspended platform assembly. The entire cylindrical assembly is machined from SA-965M F304 stainless steel forgings. This material combines excellent gamma-ray shielding performance, structural strength, and corrosion resistance, providing core gamma-ray protection support for the composite shielding system, adapting to the harsh working conditions of high-burnup spent fuel transportation, and providing a stable heat transfer foundation for the passive heat dissipation system.

[0060] like Figure 1 , Figure 6 and Figure 13 As shown, four lifting trunnions 4 (one each at 0°, 90°, 180°, and 270°) are uniformly welded to the upper circumference of the upper annular inner cylinder 1. Each lifting trunnion 4 is fixed to the outer surface of the upper annular inner cylinder 1 by a shear block 15. Both the lifting trunnion 4 and the shear block 15 are made of SA-705 630 stainless steel. Operators can use the lifting trunnion 4 to lift the container vertically. The shear block 15 serves as a force buffer and overload protection component, which can absorb the accidental impact energy during the lifting process, prevent the lifting trunnion 4 from directly transmitting excessive load to the cylinder weld, prevent the weld from cracking and causing the trunnion to fall off, and a safety stop is provided at the outer end of the lifting trunnion 4 to prevent the lifting device from slipping.

[0061] Two rotating trunnions 5 are symmetrically welded to the outer side of the bottom end cap 3. The rotating trunnions 5 are also fixed to the outer surface of the bottom end cap 3 by shear blocks 15, which is used to enable the container to flip between horizontal and vertical postures. During the flipping process, the radial load caused by the shift of the container's center of gravity is balanced by the shear blocks 15, avoiding stress concentration and fatigue damage at the connection between the rotating trunnions 5 and the bottom end cap 3. The connection positions of the lifting trunnion 4 and the rotating trunnion 5 are equipped with trunnion screw caps 50 to protect the connection structure from external environmental corrosion.

[0062] like Figure 6 , Figure 7 and Figure 15 As shown, the top end face of the upper annular inner cylinder 1 is provided with three positioning bosses 43 distributed circumferentially at 90° intervals, which provide a unified positioning reference for the outer cover 35, inner cover 33 and the flange of the extraction device, ensuring the coaxiality of the assembly of multiple parts and avoiding the impact of assembly deviation on the sealing effect and the heat transfer stability of passive heat dissipation.

[0063] like Figure 1 , Figure 4 , Figure 9 , Figure 12As shown, the upper annular inner cylinder 1 has one water hole 37 at a -45° position around its circumference, which is adapted to the liquid flow path in the vertical transport posture of the container, facilitating rapid filling and drainage and monitoring of the internal cavity pressure; the bottom end cap 3 has two water holes 37 around its circumference, one of which is coaxially corresponding to the water hole 37 of the upper annular inner cylinder 1 (at a -45° position), forming a through flow channel to ensure smooth liquid entry and exit in the vertical posture, and the other is located at a +45° position, symmetrically distributed with the former, and the diameter and interface specifications of the two bottom water holes 37 are completely consistent. Each water hole 37 is equipped with a hole cover 38. Two concentric fluororubber sealing rings 39 are installed on the inner side of the hole cover 38, which together form the first containment boundary for radioactive material leakage from the container. A detection hole 40 is reserved between the two concentric sealing rings 39. The detection hole 40 is divided into a weld detection hole and a seal detection hole. The weld detection hole monitors the sealing performance of the weld connecting the water hole 37 and the cylinder assembly. The seal detection hole judges the sealing status of the sealing ring 39 in real time through pressure monitoring or gas detection, realizing early warning of leakage, making up for the deficiency of incomplete seal detection coverage in existing containers, and forming a double sealing guarantee.

[0064] like Figure 9-13 As shown, a neutron shielding assembly is coaxially sleeved on the outside of the cylindrical assembly. This assembly consists of an outer shell 6, an upper end cylindrical section 7, a lower end cylindrical section 8, an upper end plate 9, a lower end plate 10, a neutron shielding layer 16, a top neutron shielding sleeve 17, a bottom neutron shielding sleeve 18, and positioning protrusions 11. The outer shell 6 is welded to the upper end plate 9 via the upper end cylindrical section 7 and to the lower end plate 10 via the lower end cylindrical section 8. The upper end plate 9 and the lower end plate 10 are welded to the outer surface of the cylindrical assembly, together forming an annular shielding cavity 13. The outer shell 6 is made of SA-240 TYPE 304 steel plate with a thickness of 6mm. The upper end plate 9 and the lower end plate 10 are both 12mm thick, taking into account both structural strength and shielding compatibility.

[0065] like Figure 3 and Figure 4 As shown, a positioning protrusion 11 is arranged circumferentially between the lateral contact surfaces of the top neutron shielding sleeve 17 and the upper annular inner cylinder 1. One end of the positioning protrusion 11 is fixed to the outer side of the upper annular inner cylinder 1, and the other end abuts against the inner side of the top neutron shielding sleeve 17, so as to achieve precise radial alignment and circumferential positioning between the two, ensure the assembly coaxiality of the top neutron shielding sleeve 17, and prevent it from radially offset or circumferentially rotating.

[0066] Several heat sinks 29 are arranged along the axial direction of the cylindrical assembly inside the annular shielding cavity 13. The circumferential spacing of adjacent heat sinks 29 is equal, dividing the annular shielding cavity 13 into multiple circumferentially evenly distributed neutron shielding filling chambers 14. Each filling chamber is filled with neutron shielding material to form a neutron shielding layer 16. The thickness of the circumferential neutron shielding layer 16 is about 334 mm. The top neutron shielding sleeve 17 and the bottom neutron shielding sleeve 18 are installed on both sides of the axial direction of the neutron shielding layer 16 through the upper end plate 9 and the lower end plate 10, respectively. Both sleeves are filled with neutron shielding material, effectively filling the axial protection blind zone of the main neutron shielding layer 16.

[0067] The upper end plate 9 and the lower end plate 10 have the dual functions of sealing the annular shielding cavity and positioning the shielding sleeve, making the assembly structure more stable and the operation more convenient. The shielding material inside the sleeve works together with the main body neutron shielding layer 16 to ensure that the overall neutron shielding performance of the container is uniform and stable. Together with the gamma-ray shielding of the cylinder assembly, it forms a full-dimensional composite shielding system, which fully meets the stringent radiation protection requirements of transporting high-burnup spent fuel.

[0068] This invention achieves a partitioned composite shielding design for lateral and end shielding through the coordinated operation of the cylindrical assembly and the neutron shielding assembly. This system is deeply integrated with the passive heat dissipation system and does not interfere with each other. The lateral shielding employs a triple protection system: a stainless steel cylindrical body, a composite structure of a neutron shielding layer, and the self-shielding effect of the fuel rods. The stainless steel cylindrical body serves as the first gamma-ray shielding barrier, the neutron shielding layer 16 specifically protects against neutron radiation, and the self-shielding effect of the fuel rods within the storage sleeve 22 further weakens the lateral radiation intensity. These three elements work together to achieve efficient lateral protection, and the stainless steel cylindrical body provides an efficient heat transfer medium for passive heat dissipation. The end shielding employs a dual protection system of a stainless steel shield and the self-shielding effect of the fuel rods. The top and bottom neutron shielding sleeves directly cover both axial ends of the cylindrical assembly, providing precise protection against end radiation blind spots. Combined with the self-shielding effect of the spent fuel assembly, this effectively blocks end radiation leakage, ensuring radiation protection throughout the container's circumference without any blind spots. This partition design optimizes the balance between the weight of the shield and the protective effect, avoids the shortcomings of a single shield structure, and ensures that the radiation dose under all operating conditions meets the regulatory transport limits when the container is fully loaded with high-burnup spent fuel assemblies, without obstructing the heat transfer path of passive heat dissipation.

[0069] like Figure 10 , Figure 11 As shown, the passive heat dissipation component consists of a support plate and a heat transfer plate 28 inside the basket assembly, and heat dissipation fins 29 distributed circumferentially on the outer surface of the cylinder assembly. One end of the heat dissipation fin 29 is fixed to the outer surface of the cylinder assembly, and the other end is fixed to the inner side of the outer shell 6 of the neutron shielding assembly. The outer surface of the heat dissipation fin 29 is in close contact with the neutron shielding material, making the neutron shielding layer 16 an important part of the passive heat dissipation path, constructing an efficient heat conduction channel, and realizing the deep integration of the heat dissipation structure and the shielding system.

[0070] The heat sink 29 adopts a stainless steel-aluminum composite structure with a total thickness of 10-16mm (preferably 14mm, of which the stainless steel layer is 8mm and the aluminum layer is 6mm). The high thermal conductivity of aluminum ensures the heat transfer efficiency of passive heat dissipation, while the stainless steel improves the structural strength and radiation resistance, making it suitable for the harsh working conditions of high fuel consumption and spent fuel transportation, ensuring the long-term stable operation of the heat dissipation component, and the composite material will not damage the protective performance of the neutron shielding layer 16.

[0071] like Figure 10 As shown, in a preferred embodiment of the present invention, the heat sink 29 is offset by 5-15° (preferably 10°) radially relative to the central axis of the cylindrical assembly, and the offset angles of adjacent heat sinks 29 are completely consistent. This design, through structural angle optimization, further resolves the coupling contradiction between passive heat dissipation and composite shielding, achieving synergistic performance improvement of both. Specifically, the offset arrangement of the heat sink 29 significantly increases the effective contact area with the neutron shielding material by increasing the contact width without increasing the axial height. The contact width mentioned here specifically refers to the additional extension length of the heat sink in the circumferential plane of the annular shielding cavity, compared to the pure radial arrangement, due to the tilt offset, which is the additional length of contact with the neutron shielding material; that is, as the heat sink extends from the outer surface of the inner cylinder to the outer shell of the neutron shielding assembly, the coverage width of its plate surface in the shielding material filling area is effectively expanded, while making each heat sink 29 form a continuous and uniform high-efficiency "thermal bridge". These thermal bridges are evenly distributed around the annular shielding cavity 13. They can quickly absorb the decay heat of spent fuel components conducted from the cylinder assembly to the neutron shielding layer 16 through the high thermal conductivity of the stainless steel-aluminum composite structure and efficiently transfer it to the outer shell 6 for dissipation. They can also avoid the concentration or absence of local heat transfer channels, ensure a uniform temperature field inside the container, effectively reduce material thermal stress, and improve structural stability.

[0072] Secondly, the design does not compromise the integrity and uniformity of the neutron shielding layer 16. The circumferential spacing between adjacent heat sinks 29 remains equal, and the consistent offset angle divides the annular shielding cavity 13 into regularly shaped and uniformly sized neutron shielding filling chambers 14. This division constitutes a regular physical partition, preventing structural breaks and radiation protection blind spots in the neutron shielding layer. The neutron shielding material can be uniformly filled without local gaps or uneven distribution. Furthermore, the stainless steel-aluminum composite material of the heat sinks 29 does not affect neutron moderation and absorption, and the offset direction does not conflict with the neutron radiation propagation path, thus preventing the formation of radiation leakage channels and ensuring that the neutron shielding protection effect is not affected.

[0073] Furthermore, the offset straight heat sinks form regularly inclined flow channels, avoiding the problems of narrow flow channels and right-angle obstruction caused by traditional radial vertical arrangements, reducing the flow resistance of the convective heat dissipation medium (air), and further improving passive heat dissipation efficiency. In summary, this design achieves synergistic optimization of neutron shielding and heat transfer efficiency from a structural perspective, effectively solving the technical pain point of mutual interference between the two in existing technologies.

[0074] The passive heat dissipation of the present invention relies on a triple heat transfer mechanism of radiation, convection and conduction. The specific path is as follows: the decay heat generated by the spent fuel assembly passes through the storage sleeve 22 → support plate → heat transfer plate 28 → cylinder assembly → neutron shielding layer 16 → heat sink 29 → outer shell 6 in sequence, and is finally dissipated into the atmosphere. There is no external power drive throughout the process, which completely gets rid of the dependence of existing technologies on external active heat dissipation systems and eliminates various safety hazards caused by active heat dissipation from the root.

[0075] like Figure 4 As shown, the cover assembly consists of an inner cover 33, an inner cover clamping flange 34, and an outer cover 35. Through the dual design of clamping and limiting, the sealing stability and structural reliability of the container opening are enhanced, solving the problem of insufficient sealing redundancy in existing containers.

[0076] like Figure 5 and Figure 7 As shown, the inner cover 33 is positioned and assembled inside the opening end of the cylinder assembly, which is the key boundary for containing radioactive materials. An automatic gripping positioning boss 44 is provided at its center, and a gripping cover 45 is installed on the outside of the boss. The gripping cover 45 is fixed to the inner cover 33 by screws 46, which can be directly adapted to the automated extraction device of nuclear power plants, reducing the risk of manual intervention. The inner surface of the inner cover 33 has four lifting screw holes 49 marked "lifting" to facilitate the installation of rotating lifting eye screws for lifting and disassembly. The inner cover 33 also has an inner cover positioning notch 41 on its edge, which precisely matches the positioning structure of the cylinder assembly, ensuring the coaxiality of the inner cover 33 and the cylinder assembly, and avoiding assembly deviations from affecting the sealing effect and the internal heat transfer environment.

[0077] The inner cover clamping flange 34 is located above the inner cover 33 and is fastened by screwing screws 46 into the screw holes 47 of the upper annular inner cylinder 1. During installation, the guide pin is first inserted into the designated threaded hole of the cylinder assembly to guide the inner cover 33 into accurate position and prevent the inner cover from shifting and causing sealing failure. The outer cover 35 is located above the inner cover clamping flange 34 and is also fixed to the cylinder assembly by screws 46. Its lower end face is tightly fitted with the upper end face of the inner cover clamping flange 34 to form an axial limiting constraint and prevent the flange from loosening during transportation or hoisting.

[0078] The outer cover 35 and the inner cover clamping flange 34 have the same disassembly and assembly structure design. Both have four lifting bolt holes 49 marked "lifting" on the inner side of their outer surfaces, which can be quickly lifted by lifting tools to meet the efficient operation requirements of daily maintenance and spent fuel assembly loading. The inner cover 33 is also provided with an air inlet 36 and a water hole 37. The air inlet 36 is equipped with a quick gas delivery connector to adapt to operations such as internal cavity pressure testing, vacuum drying, and helium filling protection. The water hole 37 is equipped with a quick liquid delivery connector to facilitate water filling and venting. Both the air inlet 36 and the water hole 37 are equipped with a hole cover 38 and a sealing ring 39 to ensure the reliability of the interface sealing.

[0079] The sealing surfaces of the outer cover 35 and the inner cover clamping flange 34, the sealing surfaces of the inner cover clamping flange 34 and the inner cover 33, the sealing surfaces of the inner cover 33 and the cylinder assembly, and the sealing surfaces of the air inlet 36 and the water inlet 37 cover 38 are all machined with two concentric sealing grooves. Sealing rings 39 are embedded in the grooves, and a detection hole 40 is provided between every two concentric sealing rings 39. The sealing status can be monitored in real time through pressure monitoring or gas detection to realize early warning of sealing failure. The structure ensures the reliability of radioactive material containment and meets the nuclear safety transportation requirements of high burnup spent fuel.

[0080] like Figure 8 , Figure 16-20 As shown, the basket assembly is located inside the cylindrical receiving cavity 12 and is the core internal structure of the all-path passive heat dissipation system, providing a smooth internal heat transfer path for the efficient transfer of decay heat. The preferred embodiment of the present invention is a transport container adapted to a 14-foot (approximately 4.27-meter) high burnout spent fuel assembly. Its main structure is consistent with the above-mentioned technical solution. Considering the size of the 14-foot spent fuel assembly, loading requirements, and decay heat release characteristics, the material selection, number of components, assembly layout, and structural details of the basket assembly have been comprehensively optimized.

[0081] The basket assembly in this embodiment includes a top plate 20, a bottom plate 21, a storage sleeve 22, a threaded rod 23, a positioning block 24, a support plate, and a heat transfer plate 28. The support plate is further divided into a fuel assembly support plate 25, a storage sleeve support plate 26, and a support plate 27. To adapt to the heavy-load characteristics and high heat flux density heat transfer requirements of the 14-foot high-burnup spent fuel assembly, the top plate 20 and the bottom plate 21 are made of SA-182 304 stainless steel forgings, the support plate is made of SA-705 630 stainless steel forgings, and the heat transfer plate 28 is made of 6061-T6 aluminum plate. The top plate 20 is equipped with a cross-shaped top plate reinforcement beam 31, which significantly enhances the structural strength of the top plate and meets the requirements of heavy-load transportation conditions.

[0082] The support plates and heat transfer plates 28 are evenly distributed along the axial direction of the suspended platform. There are 70 heat transfer plates 28 and 36 support plates 27. Two heat transfer plates 28 are arranged between adjacent support plates 27, forming an alternating high-efficiency heat transfer-support structure. All plates are inserted and locked by four threaded rods 23. The adjacent plates are kept at a fixed distance by positioning blocks 24. The top plate 20 is axially fastened at the through end by a top nut 48 to ensure the overall stability of the suspended platform assembly. A drain pipe assembly 42 is fixedly installed axially on the inner wall of the cylinder assembly. This assembly is the core drainage structure of the container cavity. Extending axially along the cylindrical receiving cavity 12, it adapts to the drainage needs of the container in different working postures (vertical / horizontal). Each support plate and heat transfer plate 28 of the suspended basket assembly has a shelf positioning notch 32 at the installation position of the drain pipe assembly 42. The drain pipe assembly 42 is embedded in the notch, which can effectively prevent circumferential displacement of the plate body, ensure the coaxiality of the suspended basket assembly and the cylinder assembly, and avoid structural displacement from affecting the decay heat conduction efficiency. At the same time, the axial arrangement of the drain pipe assembly 42 is unobstructed, forming a through drainage channel with the water hole 37 on the cylinder assembly, ensuring that the water accumulated in the container cavity is quickly and completely drained.

[0083] There are 12 storage sleeves 22, whose length and cross-sectional dimensions are precisely adapted to the outline of the 14-foot high spent fuel assembly. The inner surface of the storage sleeve 22 has a square cross-section, and the four sides are made of inner and outer stainless steel plates with neutron absorbing material sandwiched in between. This not only does not bear mechanical load, but also effectively fixes the neutron absorbing material and ensures critical safety. The storage sleeve 22 is fitted with storage sleeve support plate 26, each support plate 27 and heat transfer plate 28. Both ends are positioned and supported in the storage sleeve mounting holes 30 of the fuel assembly support plate 25 and the top plate 20, respectively. After assembly, it fits tightly with each support plate and heat transfer plate, which not only ensures the structural stability of the 14-foot spent fuel assembly after loading, but also quickly conducts decay heat to the subsequent heat transfer structure of the passive heat dissipation system, realizing efficient removal of decay heat.

[0084] The basket assembly in this embodiment adopts an open structure design, forming a coordinated fluid flow system with the drainage pipe assembly 42 on the inner wall of the cylinder assembly. This significantly enhances the fluid flow performance inside and at the bottom, adapting to container filling, drainage, and drying operations. It can meet the requirements of dry transport outside the water tank without additional complex auxiliary structures. The spacing, number, and arrangement of the heat transfer plates 28 and support plates in the basket assembly are all optimized through simulation based on the decay heat release characteristics of the 14-foot high burnout spent fuel assembly. This ensures that the decay heat is quickly and evenly transferred to the heat transfer plates 28 through the storage sleeve 22, and then introduced into the passive heat dissipation main channel. At the same time, the thickness design and partitioned shielding scheme of the neutron shielding layer 16 are specifically matched to the radiation intensity distribution of the 14-foot high burnout spent fuel assembly, ensuring that the radiation dose during container transportation meets regulatory limits.

[0085] This invention, as the first domestically produced high-burnup spent fuel transfer container outside a water pool, achieves multiple core technological breakthroughs in the field of nuclear fuel transfer through integrated design. Its core innovations and advantages are reflected in:

[0086] (1) Pioneering full-path passive heat dissipation system: It fills the gap in the engineering application of passive heat dissipation technology in the field of spent fuel transportation. It relies on the triple heat transfer mechanism of radiation, convection and conduction to achieve efficient and non-powered heat dissipation of decay heat. No external active equipment is required throughout the process, which completely gets rid of the equipment and power dependence of traditional active heat dissipation, ensures the reliability of thermal management under extreme working conditions, and improves the inherent safety of the container.

[0087] (2) Resolving the contradiction between heat dissipation and shielding: Through the core structural design of the heat sink, the passive heat dissipation system and the composite shielding system are deeply integrated. Under the premise of ensuring heat dissipation efficiency, the full-dimensional, dead-angle-free, and efficient protection of γ-rays and neutrons is achieved. This completely solves the technical dilemma of the trade-off between heat dissipation efficiency and shielding performance in the existing technology, and achieves the simultaneous optimization of the two.

[0088] (3) Construct a full-scenario high-redundancy sealing system: All sealing surfaces are equipped with double sealing rings and online monitoring and detection holes, forming a dual guarantee of sealing failure early warning and redundancy protection, which solves the problems of insufficient sealing redundancy and incomplete leakage detection of existing containers, and ensures the reliability of radioactive material containment;

[0089] (4) Realize the localization of core technologies: It has completely broken the foreign monopoly on the core technology of the dry-process high burnup spent fuel transfer container outside the pool, provided the localization of core technology support for the transfer of high burnup spent fuel assemblies in my country, reduced the cost of equipment procurement and maintenance, improved the operation and maintenance efficiency of nuclear power plants and the independent security of the nuclear power supply chain, and laid a solid foundation for the independent guarantee capability of the back end of my country's nuclear fuel cycle.

[0090] (5) Excellent material and structural compatibility: The main structure is made of 304 stainless steel and 630 forgings, which takes into account structural strength, corrosion resistance and radiation shielding performance. The material has high smoothness and good decontamination performance, which is fully compatible with the operation and maintenance and protection requirements of nuclear power plants.

[0091] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0092] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment includes only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding, characterized in that, include: The cylindrical assembly is a vertical cylindrical structure with an open end, and has an internal cylindrical receiving cavity for accommodating the basket assembly. The cylindrical assembly can shield gamma rays and provide structural support. A neutron shielding assembly connected to the cylindrical assembly includes a shell coaxially sleeved on the outside of the cylindrical assembly, and a neutron shielding layer filled between the shell and the outer surface of the cylindrical assembly. The basket assembly is disposed within the cylindrical receiving cavity of the cylindrical assembly and includes multiple storage sleeves for loading high-burnup spent fuel assemblies. The passive heat dissipation component includes a support plate and a heat transfer plate disposed in the basket assembly, and heat dissipation fins distributed circumferentially along the outer surface of the cylindrical assembly; the storage sleeve is positioned and fitted to the support plate, the heat transfer plate is fitted to the support plate and adapted to the inner cavity of the cylindrical assembly, one end of the heat dissipation fin is fixedly connected to the outer surface of the cylindrical assembly, the other end is fixedly connected to the inner side of the outer shell of the neutron shielding assembly, and the heat dissipation fin is in contact with the neutron shielding layer; A cover assembly is disposed at the open end of the cylindrical assembly and is sealed and adapted to the cylindrical assembly.

2. The high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding according to claim 1, characterized in that, The outer shell of the neutron shielding assembly and the outer surface of the cylindrical assembly enclose an annular shielding cavity; the heat sink extends axially along the cylindrical assembly and is arranged in the annular shielding cavity, and the circumferential spacing between adjacent heat sinks is equal, dividing the annular shielding cavity into multiple circumferentially uniformly distributed neutron shielding filling chambers; each of the neutron shielding filling chambers is used to fill neutron shielding material to form the neutron shielding layer, and the outer surface of the heat sink is in close contact with the neutron shielding material.

3. The high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding according to claim 2, characterized in that, The heat sinks are offset by 5-15° in the radial direction relative to the central axis of the cylindrical assembly, and the offset angles of adjacent heat sinks are the same.

4. The high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding according to claim 3, characterized in that, The heat sink is a stainless steel-aluminum composite heat sink with a thickness of 10-16mm.

5. The high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding according to claim 1, characterized in that, The neutron shielding assembly further includes a top neutron shielding sleeve and a bottom neutron shielding sleeve; the top neutron shielding sleeve and the bottom neutron shielding sleeve are respectively formed by enclosing an upper end plate and a lower end plate of an annular shielding cavity, and are disposed on both sides of the axial direction of the neutron shielding layer, and both the top neutron shielding sleeve and the bottom neutron shielding sleeve are filled with neutron shielding material.

6. The high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding according to claim 1, characterized in that, The cover assembly includes: The inner cover is positioned and assembled on the inner side of the opening end of the cylindrical assembly. An automatic gripping and positioning boss is provided at its center. A gripping cover is provided on the outer side of the automatic gripping and positioning boss. The gripping cover is fixedly connected to the inner cover. An inner cover clamping flange is located above the inner cover and is fixedly connected to the upper end face of the cylinder assembly for axially clamping the inner cover. The outer cover, located above the inner cover clamping flange, is fixedly connected to the upper end face of the cylinder assembly, forming an axial limiting constraint on the inner cover clamping flange.

7. The high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding according to claim 6, characterized in that, The inner cover is provided with an air inlet and a water outlet, and the upper and lower circumferential parts of the cylinder assembly are respectively provided with water outlets. The air inlet of the inner cover is equipped with a quick-connect gas delivery connector, and the water outlets of the inner cover and the cylinder assembly are all equipped with quick-connect liquid delivery connectors, and each outlet is provided with a suitable cover. The sealing mating surfaces of the outer cover and the inner cover clamping flange, the inner cover clamping flange and the inner cover, the inner cover and the cylinder assembly, and the sealing mating surfaces of each outlet cover are all provided with two concentric sealing grooves, and a sealing ring is embedded in each sealing groove to form two concentric sealing rings. A detection hole is provided between the two concentric sealing rings.

8. The high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding according to claim 1, characterized in that, The cylindrical assembly includes an annular inner cylinder and a bottom end cap fixedly connected to the bottom of the annular inner cylinder. The bottom end cap and the annular inner cylinder enclose the cylindrical receiving cavity. The upper part of the annular inner cylinder is provided with a plurality of lifting trunnions, which are evenly arranged along the circumference of the annular inner cylinder. The outer end of the lifting trunnions is provided with a safety stop to prevent the lifting device from slipping.

9. The high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding according to claim 8, characterized in that, The bottom end cap of the cylindrical assembly is provided with at least two rotating trunnions to enable the container to flip between horizontal and vertical positions; the top end face of the annular inner cylinder of the cylindrical assembly is provided with multiple positioning protrusions, which are evenly arranged circumferentially for positioning the outer cover and the middle position of the inner cover and the flange of the extraction device.

10. The high-burnup spent fuel assembly transfer container based on passive heat dissipation and composite shielding according to claim 1, characterized in that, The suspended platform assembly also includes a top plate, a bottom plate, and a threaded rod; the support plate and the heat transfer plate are disposed between the top plate and the bottom plate, and the threaded rod passes through and locks the bottom plate, the top plate, the support plate, and the heat transfer plate. Adjacent plates are spaced apart by positioning blocks; the storage sleeve is used to load a 14-foot high burnup spent fuel assembly and is positioned and supported by the support plate.

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