Three-petcock assembly for a reactor and a refueling petcock for a three-petcock assembly

Abstract

Embodiments of the present application relate to the technical field of nuclear reactors, and particularly to a three-globe assembly suitable for a reactor and a refueling globe suitable for the three-globe assembly. The refueling globe is used to install a refueling machine. The three-globe assembly further comprises a vessel opening globe used to be rotatably arranged at a vessel opening of a reactor vessel and a control rod drive globe used to install a control rod drive mechanism; the control rod drive globe is rotatably arranged at the vessel opening globe, and the refueling globe is rotatably arranged at the control rod drive globe. The refueling globe is provided with an eccentric third through hole, and the third through hole is smaller than the radius of the refueling globe. The refueling globe further comprises a refueling machine pipe seat arranged at the third through hole and used to install the refueling machine. The refueling globe suitable for the three-globe assembly provided by the embodiments of the present application is beneficial to increase the moving range of the refueling machine, and at the same time, is beneficial to reduce the size of the three-globe assembly as a whole and improve the economy of the reactor.

Description

Technical Field

[0001] The embodiments of this application relate to the field of nuclear reactor technology, specifically to a three-turn plug assembly suitable for a reactor and a refueling plug suitable for the three-turn plug assembly. Background Technology

[0002] The statements herein are provided merely as background information in connection with this application and do not necessarily constitute prior art.

[0003] In fast reactors, the plug assembly is the main refueling device located on the reactor vessel. It enables the refueling machine to position the reactor core components and works with the refueling machine to move components inside the reactor vessel. Simultaneously, the plug assembly, installed on the reactor vessel, serves as part of the pressure boundary of the reactor vessel, sealing it and preventing the leakage of radioactive argon and sodium aerosols.

[0004] Currently, there are still many problems in the design of the plug assembly, which affect the economics of the reactor. Summary of the Invention

[0005] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0006] To address the aforementioned issues, embodiments of this application provide a three-turn plug assembly suitable for a reactor and a refueling plug suitable for the three-turn plug assembly.

[0007] In a first aspect, embodiments of this application provide a refueling cock suitable for a three-cockpit assembly for mounting a refueling machine. The three-cockpit assembly further includes a container opening cock rotatably disposed at the container opening of a reactor vessel and a control rod drive cock for mounting a control rod drive mechanism; the control rod drive cock is rotatably disposed above the container opening cock, and the refueling cock is rotatably disposed above the control rod drive cock. The refueling cock has an eccentric third through hole, the third through hole being smaller than the radius of the refueling cock. The refueling cock also includes a refueling machine mounting base disposed in the third through hole for mounting the refueling machine.

[0008] The refueling cock provided in the embodiments of this application for a three-cylinder assembly has an eccentric third through hole, and the refueling machine is installed in the third through hole which is smaller than the radius of the refueling cock. This is beneficial to increasing the movement range of the refueling machine and reducing the size of the container opening cock, thereby reducing the overall size of the three-cylinder assembly and improving reactor economics.

[0009] Secondly, embodiments of this application provide a three-cockscrew assembly suitable for a reactor. The reactor includes a reactor vessel and a core assembly disposed within the reactor vessel. The reactor vessel includes a vessel opening coaxial with the core assembly. The reactor also includes a refueling machine and a control rod drive mechanism. The three-cockscrew assembly includes a vessel opening cock, a control rod drive cock, and the refueling cock provided in the first aspect of this application. The vessel opening cock is rotatably disposed in the vessel opening of the reactor vessel. The vessel opening cock has an eccentric first through hole, the size of which is larger than the radius of the vessel opening cock. The control rod drive cock is disposed in the first through hole of the vessel opening cock and is rotatable relative to the vessel opening cock. The control rod drive cock has an eccentric second through hole. The refueling cock is disposed in the second through hole of the control rod drive cock and is rotatable relative to the control rod drive cock. The control rod drive mechanism is disposed in the control rod drive cock, and the refueling machine is disposed in the third through hole of the refueling cock.

[0010] The three-cocks assembly provided in the embodiments of this application, by setting three cocks and making the size of the first through hole larger than the radius of the container opening cock, can increase the movement range of the refueling machine through the rotational cooperation of the three cocks, while reducing the size of the container opening cock, thereby reducing the overall size of the three-cocks assembly and improving reactor economy. Attached Figure Description

[0011] Other objects and advantages of this application will become apparent from the following description of embodiments of this application with reference to the accompanying drawings, and will help to provide a comprehensive understanding of this application.

[0012] Figure 1 This is a cross-sectional schematic diagram of a three-cylinder assembly according to an embodiment of this application;

[0013] Figure 2 This is a schematic diagram showing the distribution of the three valves;

[0014] Figure 3 yes Figure 1 The diagram shows a top view of the three-cylinder assembly with the control rod drive mechanism mounting base omitted.

[0015] Figure 4 yes Figure 1 A cross-sectional schematic diagram of the container opening stopcock shown;

[0016] Figure 5 yes Figure 4 A top view of the container opening stopcock shown;

[0017] Figure 6 yes Figure 1 A schematic cross-sectional view of the control rod driving the rotary valve is shown.

[0018] Figure 7 yes Figure 6The top view of the control rod driving the valve shown;

[0019] Figure 8 yes Figure 1 A schematic cross-sectional view of the refueling valve shown.

[0020] Figure 9 yes Figure 8 A top view of the refill valve shown;

[0021] Figure 10 yes Figure 1 The enlarged view shown below;

[0022] Figure 11 yes Figure 1 The enlarged view shown below;

[0023] Figure 12 yes Figure 10 The enlarged view shown here indicates the direction of airflow, with arrows pointing to the direction of airflow.

[0024] Figure 13 yes Figure 12 The enlarged view shown here indicates the direction of airflow, with arrows pointing to the direction of airflow.

[0025] Figure 14 yes Figure 8 A partially enlarged schematic diagram of the feed changer;

[0026] Figure 15 yes Figure 6 The diagram shows a partially enlarged view of the control rod driving the valve.

[0027] Explanation of reference numerals in the attached figures:

[0028] 11. Reactor container; 111. Container opening; 12. Core assembly; 13. Tie rod; 14. Moving guide tube; 15. Internal shielding;

[0029] 101. Circular negative pressure air duct;

[0030] 20. Container opening stopcock; 21. First dynamic sealing structure; 22. First body section; 221. Upper shell; 2211. Upper top plate; 2212. Upper bottom plate; 2213. Upper radial outer side plate; 2214. Upper surrounding plate of the first through hole; 222. Lower shell; 2221. Support plate; 2222. Steel column; 223. Screw; 23. First gamma shielding section; 24. First connecting section; 241. Reinforcing rib; 25. Manhole plug; 251. Plug body shielding section; 253. Plug body gamma shielding layer; 254. Connecting rod; 26. Manhole passage; 27. First through hole;

[0031] 201, First air duct; 2011, First air inlet;

[0032] 202. First bearing; 203. First gear ring; 204. First drive mechanism;

[0033] 30. Control rod drive valve; 31. Second dynamic sealing structure; 32. Second body section; 321. Second housing; 3211. Second top plate; 3212. Second bottom plate; 3213. Second radial outer plate; 3214. Second through-hole surrounding plate; 33. Second gamma shielding section; 34. Second connecting section; 35. Control rod drive mechanism mounting tube; 350. Predetermined circumference; 351. First mounting plate; 360. Second mounting plate; 36. Control rod protection component; 361. Cylinder; 362. Bottom end cap; 37. Thermocouple mounting tube; 38. Lifting mechanism tube; 39. Second through-hole;

[0034] 301, Second air duct; 3011, Second air inlet;

[0035] 302. Second bearing; 303. Second gear ring; 304. Second drive mechanism;

[0036] 40. Material changing cock; 41. Third dynamic sealing structure; 42. Third body section; 421. Third shell; 4211. Third top plate; 4212. Third bottom plate; 4213. Third radial outer plate; 4214. Third through-hole surrounding plate; 4215. Fourth through-hole surrounding plate; 43. Third gamma shielding section; 44. Third connecting section; 45. Third through-hole; 46. Fourth through-hole; 47. Material changing machine tube seat;

[0037] 401, Third air duct; 4011, Third air inlet;

[0038] 402. Third bearing; 403. Third gear ring; 404. Third drive mechanism;

[0039] 51. Thermal shielding layer; 52. Neutron shielding layer;

[0040] 61. First sealing plate; 62. First support cylinder; 621. Ventilation hole of first support cylinder; 63. First air-cooled enclosure cylinder; 631. First air-cooled ventilation hole; 64. First annular plate; 65. First ventilation plate; 66. First sealing connection part;

[0041] 71. Second sealing plate; 72. Second support cylinder; 721. Ventilation hole of second support cylinder; 73. Second air-cooled enclosure cylinder; 731. Second air-cooled ventilation hole; 74. Second annular plate; 76. Second sealing connection part;

[0042] 81. Third sealing plate; 82. Third support cylinder; 83. Third air-cooled enclosure cylinder; 831. Third air-cooled ventilation hole; 84. Third annular plate;

[0043] 91. First ventilation duct; 92. Second ventilation duct; 93. Third ventilation duct; 94. Sealing body; 95. Fitting parts; 96. Heating assembly; 97. Receiving tank; 971. First tank; 972. Second tank; 98. Liquid metal.

[0044] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation

[0045] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0046] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0047] In related technologies, a plug assembly includes: a container opening plug rotatably disposed at the container opening of a reactor vessel and a refueling plug for mounting a refueling machine. The refueling plug is rotatably disposed on the container opening plug, and the refueling machine is disposed on the refueling plug. The rotation of the container opening plug and the refueling plug enables the refueling machine to have a certain refueling range. The inventors of this application have discovered that in plug assemblies with the above structure, the container opening plug is usually large, resulting in a large overall size of the plug assembly, which is detrimental to improving reactor economics.

[0048] Therefore, in order to solve the above-mentioned technical problems, the embodiments of this application provide a three-turn plug assembly suitable for a reactor and a refueling plug suitable for the three-turn plug assembly.

[0049] See Figures 1 to 3 as well as Figure 8 , Figure 1 This is a cross-sectional schematic diagram of a three-cylinder assembly according to an embodiment of this application. Figure 2 This is a schematic diagram showing the distribution of the three valves. Figure 3 This is a top view of the three-cylinder assembly with the control rod drive mechanism mounting bracket omitted. Figure 8 yes Figure 1The cross-sectional schematic diagram of the refueling cock shown indicates that the three-cockpit assembly may further include a container opening cock 20 rotatably disposed on the container opening 111 of the reactor vessel 11 and a control rod drive cock 30 for mounting a control rod drive mechanism; the control rod drive cock 30 is rotatably disposed on the container opening cock 20, and the refueling cock 40 is rotatably disposed on the control rod drive cock. The refueling cock 40 has an eccentric third through hole 45, the third through hole 45 being smaller than the radius of the refueling cock 40; the refueling cock 40 also includes a refueling machine seat 47 disposed in the third through hole 45 for mounting the refueling machine.

[0050] The refueling cock 40 for a three-cockscrew assembly provided in the embodiments of this application, by having an eccentric third through hole 45 and installing the refueling machine in the third through hole 45 which is smaller than the radius of the refueling cock 40, is beneficial to increasing the movement range of the refueling machine and reducing the size of the container opening cock 20, thereby reducing the overall size of the three-cockscrew assembly and improving reactor economics.

[0051] See Figure 2 In some embodiments, the distance between the center of the third through hole 45 of the refueling valve 40 and the center of the container opening valve 20 is equal to twice the distance between the center of the control rod drive valve 30 and the center of the container opening valve 20. With this configuration, when the refueling machine in the third through hole 45 rotates 180 degrees with the control rod drive valve 30, the refueling machine can cover the position of the exact center of the core assembly 12, thereby achieving effective refueling throughout the entire range of the core assembly 12.

[0052] See Figure 8 In some embodiments, the refueling valve 40 may also be provided with an eccentric fourth through hole 46 for placing a spare refueling machine or flow meter, thereby improving the reactor's maintenance efficiency and flexibility.

[0053] In some embodiments, the fourth through hole 46 and the third through hole 45 are symmetrically distributed with respect to the center of the material changing plug 40, and the center of the fourth through hole 46, the center of the third through hole 45 and the center of the material changing plug 40 are collinear, so that the material changing plug 40 is compactly arranged.

[0054] See Figure 8 and Figure 9 as well as Figure 14 , Figure 9 This is a top view of the feed changer 40. Figure 14 yes Figure 8The diagram shows a partial enlarged view of the refill valve 40. In some embodiments, the refill valve 40 may include a third body section 42, a third gamma shield section 43, and a third connecting section 44, with the third gamma shield section 43 connected to the third body section 42 via the third connecting section 44. This embodiment divides the refill valve 40 into multiple sections, which can effectively reduce the deformation of the refill valve 40 caused by temperature differences.

[0055] In some embodiments, the third body segment 42 may include a heat shielding layer 51 and a neutron shielding layer 52, which are used to reduce heat transfer and shield neutrons in the reactor, respectively.

[0056] In some embodiments, the third body segment 42 may include a third housing 421, a multilayer neutron shielding layer 52 and a multilayer heat shielding layer 51 disposed within the third housing 421. The third housing 421 may include a third top plate 4211, a third bottom plate 4212, a third radial outer plate 4213, a third through-hole surrounding plate 4214 and a fourth through-hole surrounding plate 4215, which together form a sealed space, in which the neutron shielding layer 52 and the heat shielding layer 51 are disposed.

[0057] The upper part of the sealed space of the third body section 42 can be provided with multiple neutron shielding layers 52, and the lower part can be provided with alternating neutron shielding layers 52 and heat shielding layers 51, with the bottom being the heat shielding layer 51, thereby effectively insulating heat and shielding neutrons.

[0058] In some embodiments, the material changer tube seat 47 may be disposed on the third body section 42.

[0059] In some embodiments, the third connecting section 44 can be a steel cylinder structure, and the third gamma shielding section 43 is connected to the bottom end of the steel cylinder. The steel cylinder can effectively reduce the temperature of the third gamma shielding section 43 and play a role in heat shielding.

[0060] In some embodiments, the third gamma shielding section 43 can be a multi-layer steel plate structure, which can enhance the shielding effect against gamma rays and improve the safety of reactor operation.

[0061] In some embodiments, the material changing valve 40 further includes a third sealing plate 81 disposed above the third top plate 4211, a third support cylinder 82 connecting the third sealing plate 81 and the third top plate 4211, a third air-cooling confined cylinder 83 disposed radially outside the third support cylinder 82, and a third annular plate 84 connecting the third air-cooling confined cylinder 83 and the third support cylinder 82. The third sealing plate 81, the third top plate 4211, and the third support cylinder 82 form a third air duct 401 for ventilating and cooling the third top plate 4211. The third top plate 4211 is provided with a third air inlet 4011 communicating with the third air duct 401, thereby achieving cooling of the top of the material changing valve 40, which is beneficial to the stable operation of the material changing valve 40.

[0062] In some embodiments, the control rod drive cylinder 30 may include a second top plate 3211, a second sealing plate 71 disposed above the second top plate 3211, a second support cylinder 72 connecting the second sealing plate 71 and the second top plate 3211, a second air-cooled confining cylinder 73 disposed radially outside the second support cylinder 72, and a second annular plate 74 connecting the second air-cooled confining cylinder 73 and the second support cylinder 72. A second air duct 301 for ventilating and cooling the second top plate 3211 is formed between the second sealing plate 71, the second top plate 3211, the second support cylinder 72, and the third air-cooled confining cylinder 83. The second top plate 3211 is provided with a second air inlet 3011 communicating with the second air duct 301, thereby achieving cooling of the top of the control rod drive cylinder 30, which is beneficial to the stable operation of the control rod drive cylinder 30.

[0063] See Figure 11 , Figure 11 yes Figure 1 The enlarged view shown in the partial diagram indicates that in some embodiments, the third air-cooled casing 83, the third annular plate 84, the third support cylinder 82, and the second top plate 3211 form a third connecting ventilation duct 93 that connects the second air duct 301 and the third air duct 401, thereby achieving communication between the top of the control rod drive valve 30 and the top of the material changing valve 40.

[0064] In some embodiments, the refilling cock 40 may further include a third ventilation plate disposed between the third top plate 4211 and the third sealing plate 81. The third ventilation plate forms through holes, and the area of ​​the third support cylinder 82 located below the third ventilation plate forms third support cylinder ventilation holes distributed in a circumferential direction. Air in the third air duct 401 flows into the area below the third ventilation plate through the through holes and enters the third connecting ventilation duct 93 through the third support cylinder ventilation holes. In this embodiment, by setting the ventilation plate, the air in the third air duct 401 flows through the ventilation plate and enters the third connecting ventilation duct through the third support cylinder ventilation holes, thereby achieving uniform cooling of the top of the refilling cock and improving the operational stability of the three-cockpit assembly.

[0065] Embodiments of this application also provide a three-rotor assembly suitable for reactors. See also Figures 1 to 3The reactor may include a reactor vessel 11 and a core assembly 12 disposed within the reactor vessel 11. The reactor vessel 11 may include a vessel opening 111 coaxial with the core assembly 12. The reactor may also include a refueling machine and a control rod drive mechanism. The three-cockpit assembly suitable for a reactor provided in the embodiments of this application may include a vessel opening cockpit 20, a control rod drive cockpit 30, and a refueling cockpit 40 provided in any embodiment of this application. A container opening valve 20 is rotatably disposed at the container opening 111 of the reactor vessel 11. The container opening valve 20 has an eccentric first through hole 27, the size of which is larger than the radius of the container opening valve 20. A control rod drive valve 30 is disposed at the first through hole 27 of the container opening valve 20 and is rotatable relative to the container opening valve 20. The control rod drive valve 30 has an eccentric second through hole 39. A refueling valve 40 is disposed at the second through hole 39 of the control rod drive valve 30 and is rotatable relative to the control rod drive valve 30. A control rod drive mechanism is disposed at the control rod drive valve 30, and a refueling machine is disposed at the third through hole 45 of the refueling valve 40.

[0066] The three-cocks assembly provided in the embodiments of this application, by setting three cocks and making the size of the first through hole 27 larger than the radius of the container opening cock 20, can increase the movement range of the refueling machine through the rotation and cooperation of the three cocks, while reducing the size of the container opening cock 20, thereby optimizing the arrangement space of the three-cocks assembly and improving the economy and refueling efficiency of the reactor.

[0067] See Figure 2 In some embodiments, the sum of the distances between the center of the second through-hole 39 and the center of the control rod drive valve 30 is equal to half the radius of the core assembly 12. It is easy to understand that the refueling machine rotates relative to the control rod drive valve 30 with the third through-hole 45 of the refueling valve 40, the control rod drive valve 30 rotates relative to the container opening valve 20, and the container opening valve 20 rotates relative to the container opening 111 of the stack container 11, so that the movement trajectory of the refueling machine is affected by the position of the eccentric through-hole of each valve. This arrangement allows the refueling machine to move within a circular area centered on the center of the core assembly 12 and with the radius of the core assembly 12 as the radius. This ensures that, while keeping the size of the three-valve assembly as small as possible, the movement trajectory of the refueling machine can still completely cover the core assembly 12, thereby improving the space utilization and refueling efficiency of the three-valve assembly.

[0068] In some embodiments, the reactor may further include multiple control rods, with a control rod drive mechanism connected to the control rods. See also Figure 2 and Figure 7 , Figure 7The diagram shows a top view of the control rod drive cock 30, which may include multiple control rod drive mechanism mounting brackets 35 for mounting multiple control rod drive mechanisms. The multiple control rod drive mechanism mounting brackets 35 are disposed within a predetermined circumference 350. By rotating the control rod drive cock 30 relative to the container opening cock 20, the predetermined circumference 350 can be positioned concentrically with the container opening cock 20. Since the control rod drive cock 30 can rotate relative to the container opening cock 20, and the container opening cock 20 can rotate relative to the container opening 111, the predetermined circumference 350 containing the control rod drive mechanism mounting brackets 35 can be adjusted accordingly. When the control rod drive cock 30 is in the working position and not rotated, the predetermined circumference 350 is concentric with the container opening cock 20. At this time, each control rod drive mechanism mounting bracket 35 can be located directly above the core assembly 12. When refueling is required, after all the control rods have fallen, the control rod drive valve 30 can be rotated to move the control rod drive mechanism mounting base 35 above the core assembly 12, providing space for the refueling machine. This ensures accurate positioning and effective control of the control rods and control rod drive mechanism during normal reactor operation, while also enabling flexible avoidance during refueling, thus improving the overall operating efficiency and safety of the reactor.

[0069] In some embodiments, see Figure 2 The center of the second through hole 39 is collinear with the center of the first through hole 27 and the center of the container opening plug 20, which ensures a compact layout, reduces space waste and additional material requirements caused by eccentric arrangement, and thus helps to reduce the size of the container opening plug 20 while ensuring the function of the plug, thereby improving space utilization.

[0070] In some embodiments, see Figure 1 The three-cocks assembly also includes a first dynamic sealing structure 21, a second dynamic sealing structure 31, and a third dynamic sealing structure 41. The first dynamic sealing structure 21 seals the container opening cock 20 and the container opening 111 of the reactor vessel 11. The second dynamic sealing structure 31 seals the control rod drive cock 30 and the first through-hole 27 of the container opening cock 20. The third dynamic sealing structure 41 seals the refueling cock 40 and the second through-hole 39 of the control rod drive cock 30. The difference between the diameter of the container opening cock 20 and the diameter of the core assembly 12 is equal to the sum of the annular widths of the first dynamic sealing structure 21, the second dynamic sealing structure 31, and the third dynamic sealing structure 41. This ensures that the refueling machine's movement trajectory completely covers the core assembly 12, while also guaranteeing the sealing of the opening of the reactor vessel 11, effectively preventing the leakage of radioactive materials.

[0071] In some embodiments, see Figure 13 , Figure 13This is a partially enlarged view of the three-turn valve assembly. The first dynamic sealing structure 21 may include a sealing body 94, a mating member 95, and a heating assembly 96. The sealing body 94 is connected to the periphery of the container opening 111 on the radially outer side of the stack container 11. The sealing body 94 is configured to form a receiving groove 97, which contains liquid metal 98 (e.g., a lead-bismuth alloy). The mating member 95 is connected to the container opening valve 20. The mating member 95 divides the receiving groove 97 into a first groove 971 located on the radially inner side and a second groove 972 located on the radially outer side. The bottoms of the first groove 971 and the second groove 972 are connected. The heating assembly 96 is disposed on the radially outer side of the receiving groove 97 for heating the liquid metal 98 in the receiving groove 97. When the container opening stopcock 20 does not rotate, the solidified liquid metal provides a static seal for the container opening stopcock 20 and the stack container 11; when the container opening stopcock 20 needs to rotate, the heating component 96 heats the liquid metal 98 in the receiving tank 97, melting it into a liquid state, and uses the liquid metal to provide a dynamic seal for the stopcock and the stack container.

[0072] In some embodiments, the second dynamic sealing structure 31 and the third dynamic sealing structure 41 may have the same structure as the first dynamic sealing structure 21.

[0073] See Figure 4 , Figure 4 This is a cross-sectional schematic diagram of the container opening stopcock 20. In some embodiments, the container opening stopcock 20 may include a first body section 22, a first gamma shield section 23, and a first connecting section 24. The first gamma shield section 23 is connected to the first body section 22 through the first connecting section 24. The first body section 22 faces the container opening 111 of the reactor vessel 11, and the first connecting section 24 and the first gamma shield section 23 enter the interior of the reactor vessel 11. It is easy to understand that part of the structure of the container opening stopcock 20 is located inside the reactor vessel 11 and is affected by the high temperature inside the reactor, while the part of the structure located outside the reactor is at room temperature, resulting in a significant temperature difference in the container opening stopcock 20, which can easily cause deformation. In this embodiment, the container opening stopcock 20 is divided into multiple segments, which can effectively reduce the deformation of the container opening stopcock 20 caused by the temperature difference.

[0074] The first gamma shield section 23 of the container opening plug 20 can enter the radially inner side of the top of the in-stack shield 15.

[0075] In some embodiments, the first body segment 22 may include a heat shielding layer 51 and a neutron shielding layer 52, which are used to reduce heat transfer and shield neutrons in the reactor, respectively.

[0076] In some embodiments, the heat shielding layer 51 may be a calcium silicate layer. In some embodiments, the neutron shielding layer 52 may be a graphite layer.

[0077] In some embodiments, the first body segment 22 may include an upper segment and a lower segment, with the lower segment connected to the upper segment via a plurality of screws 223. The upper segment of the first body segment 22 may include an upper housing 221 and a multilayer neutron shielding layer 52 disposed within the upper housing 221. The upper housing 221 forms a sealed structure and may include an upper top plate 2211, an upper bottom plate 2212, an upper radial outer side plate 2213, and a first through-hole upper surrounding plate 2214. These plates together enclose a sealed space, in which the multilayer neutron shielding layer 52 is disposed.

[0078] The lower section of the first body segment 22 may include a lower shell 222, a multi-layer neutron shielding layer 52 and a multi-layer thermal shielding layer 51 disposed within the lower shell 222. The lower shell 222 may include a lower top plate, a lower bottom plate, a lower radial outer plate and a lower surrounding plate with a first through hole. These plates together form a sealed space. The neutron shielding layer 52 and the thermal shielding layer 51 are alternately arranged, with the thermal shielding layer 51 at the bottom. In this embodiment, the first body segment 22 is divided into an upper section and a lower section. The upper section is mainly used to ensure structural stability and shield neutrons. The lower section, due to its proximity to the reactor and higher temperature, alternates between the neutron shielding layer 52 and the thermal shielding layer 51, with the thermal shielding layer 51 at the bottom, which can effectively prevent thermal deformation and shield neutrons; and enhance the stability of the overall structure and each shielding material.

[0079] In addition, by setting the upper shell 221 and the lower shell 222 as a sealed structure, it is also possible to prevent the leakage of radioactive materials.

[0080] In some embodiments, the lower section may further include multiple support plates 2221 (e.g., thin steel plates) for supporting the neutron shielding layer 52 and the heat shielding layer 51. To enhance the support effect, the lower section may also include multiple steel columns 2222 disposed between two adjacent support plates 2221. The bottom of the steel column 2222 can be fixed to the lower support plate 2221 by a threaded connection, and the top of the steel column 2222 abuts against the upper support plate 2221 to support the upper support plate 2221. This facilitates installation and also helps to avoid structural deformation caused by thermal expansion.

[0081] In some embodiments, the first connecting section 24 can be a steel cylinder structure, and the first gamma shielding section 23 is connected to the bottom end of the steel cylinder. The steel cylinder can effectively reduce the temperature of the first gamma shielding section 23, reduce the deformation of the container opening stopcock 20 caused by temperature difference, and also play a role in heat shielding.

[0082] In some embodiments, the first gamma shielding section 23 can be a multi-layered, spaced steel plate structure, which can enhance the shielding effect against gamma rays and improve the safety of reactor operation. In some embodiments, the inner wall of the steel cylinder can be provided with multiple inclined reinforcing ribs 241, which can enhance the structural strength of the steel cylinder and prevent the steel cylinder from deforming due to high temperature.

[0083] See Figure 4 and Figure 5 , Figure 5 This is a top view of the container opening stopcock 20. In some embodiments, the container opening stopcock 20 may also form a manhole passage 26 for operator passage and a manhole plug 25 for closing the manhole passage 26. The manhole passage 26 extends downward through the first body section 22 and the first gamma shield section 23. The manhole passage 26 is located radially inside the first connecting section 24.

[0084] The manhole plug 25 may include a plug body shielding section 251, a connecting rod 254, and a plug body gamma shielding layer 253 connected to the plug body shielding section 251 via the connecting rod 254. The plug body shielding section 251, the connecting rod 254, and the plug body gamma shielding layer 253 face the first body section 22, the first connecting section 24, and the first gamma shielding section 23, respectively. In this embodiment, by forming a manhole channel 26 in the container opening stopcock 20, it is convenient for operators to enter the reactor container 11 for maintenance and repair. After completing the maintenance or repair work, the operators can use the manhole plug 25 to close the manhole channel 26, ensuring the overall sealing of the container opening stopcock 20. At the same time, the manhole plug 25 is also equipped with multiple layers of shielding to ensure the safety of reactor operation.

[0085] In some embodiments, the plug body gamma shielding layer 253 can be a cylindrical steel block used to shield gamma rays and cool high-temperature gases escaping from the reactor. The structure of the plug body shielding section 251 can be the same as the structure of the first body section 22.

[0086] In some embodiments, multiple control rod drive mechanism mounting seats 35 may be disposed on the second body section 32. The control rod drive valve 30 may further include a control rod protector 36. The control rod protector 36 is connected to the lower end of the second connecting section 34. The control rod extends downward from the radially inward side of the control rod protector 36. The control rod protector 36 effectively prevents the control rod from being impacted by the in-reactor coolant, thereby ensuring the stability of the control rod during reactor operation.

[0087] In some embodiments, the control rod protector 36 may include a cylinder 361 and a bottom end cap 362. The bottom end cap 362 is provided with a through hole for each control rod to pass through, so that the control rod can be protected inside the cylinder 361 to avoid impact from liquid metal. Furthermore, the control rod can also fall through the through hole of the bottom end cap 362 during reactor operation, ensuring the safety of the reactor.

[0088] In some embodiments, a minimum distance exists between the third through-hole 45 and the control rod protector 36. During rotation, the material changer maintains a constant distance from the control rod protector 36 to prevent interference with its operation. This minimum distance can be determined based on the dimensions of the material changer and the external dimensions of the control rod protector 36, ensuring no interference and no impact on the material changer's operation. Increasing this minimum distance increases the overall size of the three-cylinder assembly, which is detrimental to economic efficiency and cylinder arrangement. In some embodiments, the minimum distance can be, for example, greater than 127 mm.

[0089] In some embodiments, the reactor may further include multiple thermocouples, and the control rod drive valve 30 may further include multiple thermocouple mounting sockets 37 for mounting the multiple thermocouples. The multiple thermocouple mounting sockets 37 may be disposed in the second body section 32. This embodiment, by installing multiple thermocouple mounting sockets 37 in the body section of the control rod drive valve 30, achieves stable installation of the thermocouples, facilitating temperature monitoring within the reactor and thereby improving the safety of reactor operation.

[0090] In some embodiments, the reactor may further include multiple moving conduit lifting mechanisms, and the control rod drive valve 30 may include multiple lifting mechanism seats 38. The reactor may include multiple pull rods 13 and multiple moving conduits 14. The lifting mechanism seats 38 are used to mount the multiple moving conduit lifting mechanisms. The multiple lifting mechanism seats 38 may be disposed in the second body section 32. The moving conduit lifting mechanisms are used to drive the pull rods 13 and moving conduits 14 to move up and down, thereby driving the control rods to move up and down.

[0091] In some embodiments, see Figure 6 The second body segment 32 may include a heat shielding layer 51 and a neutron shielding layer 52, which are used to reduce heat transfer and shield neutrons inside the reactor, respectively.

[0092] In some embodiments, the second body segment 32 may include a second housing 321, a multilayer neutron shielding layer 52 and a multilayer heat shielding layer 51 disposed within the second housing 321. The second housing 321 may include a second top plate 3211, a second bottom plate 3212, a second radially outer plate 3213 and a second through-hole surrounding plate 3214, which together form a sealed space in which the neutron shielding layer 52 and the heat shielding layer 51 are disposed.

[0093] The upper part of the sealed space can be provided with multiple neutron shielding layers 52, and the lower part of the sealed space is provided with alternating neutron shielding layers 52 and thermal shielding layers 51, with the thermal shielding layer 51 at the bottom. In this embodiment, by providing multiple shielding layers on the second body segment 32, heat transfer and shielding of neutrons within the reactor are reduced.

[0094] In some embodiments, the second connecting section 34 can be a steel cylinder structure, and the second gamma shielding section 33 is connected to the bottom end of the steel cylinder. The steel cylinder can effectively reduce the temperature of the second gamma shielding section 33 and play a role in heat shielding.

[0095] In some embodiments, the second body segment 32 may include a first mounting plate 351, and the second connecting segment 34 is connected to the first mounting plate 351. The first mounting plate 351 has a plurality of holes for suspending the conduits of the control rod drive mechanism, the thermocouple conduits, and the control rod drive mechanism conduits.

[0096] In some embodiments, the second gamma shielding section 33 may include a multi-layer steel plate structure, which can enhance the shielding effect against gamma rays and improve the safety of reactor operation.

[0097] In some embodiments, the control rod drive valve 30 may include a second mounting plate 360, and the control rod protector 36 is connected to the second mounting plate 360.

[0098] In some embodiments, the upper top plate 2211 of the container opening valve 20, the second top plate 3211 of the control rod driving valve 30, and the third top plate 4211 of the material changing valve 40 can all be low alloy steel plates with a certain thickness and rigidity, which serve as supports for each valve.

[0099] See Figure 3 , Figures 10 to 13 , Figures 10 to 13 This shows a partially enlarged cross-sectional view of the three-cylinder assembly. Figure 12 and Figure 13 The arrows in the diagram indicate the direction of airflow. In some embodiments, the reactor also includes an annular negative pressure duct 101 located radially outside the container opening 111.

[0100] See Figures 11 to 13The container opening stopcock 20 also includes a first sealing plate 61 disposed above the upper top plate 2211, a first support cylinder 62 connecting the first sealing plate 61 and the upper top plate 2211, a first air-cooling confined cylinder 63 disposed radially outside the first support cylinder 62, and a first annular plate 64 connecting the first air-cooling confined cylinder 63 and the first support cylinder 62. A first air duct 201 for ventilating and cooling the upper top plate 2211 is formed between the first sealing plate 61, the upper top plate 2211, the first support cylinder 62, and the second air-cooling confined cylinder 73. The upper top plate 2211 is provided with a first air inlet 2011 communicating with the first air duct 201, thereby achieving cooling of the top of the container opening stopcock 20, which is beneficial to the stable operation of the container opening stopcock 20.

[0101] In embodiments of this application, an air duct is formed at the top of each cock to cool the three-cocks assembly and ensure the stability of the three-cocks assembly operation.

[0102] In some embodiments, the first air inlet 2011, the second air inlet 3011, and the third air inlet 4011 can be used to supply air. Air entering the third air duct 401 can enter the second air duct 301. Air entering the second air duct 301 can enter the first air duct 201. Air entering the first air duct 201 can enter the annular negative pressure air duct 101. In this embodiment, by connecting the air ducts of the three cocks and cooperating with the annular negative pressure air duct 101, cooling and ventilation of the three-cocks assembly are achieved, reducing the impact of high in-core temperatures on the three-cocks assembly, thereby ensuring the stability of the three-cocks assembly operation.

[0103] The container opening 111 of the stack container 11 is welded to the sealing body 94 of the first dynamic sealing structure 21; the first annular plate 64 is welded to the mating part 95.

[0104] The container opening stopcock 20 also includes a first sealing connection 66, which is connected to the first body section 22. The first sealing connection 66 is located on the radial outer side of the second air-cooled casing 73.

[0105] See Figure 15 The second annular plate 74 is welded to the sealing body 94 of the second dynamic sealing structure 31; the first sealing connection part 66 is welded to the mating part 95 of the second dynamic sealing structure 31.

[0106] The control rod drive valve 30 also includes a second sealing connection 76, which is connected to the second body section 32. The second sealing connection 76 is located on the radially outer side of the third air-cooled casing 83. The third annular plate 84 is welded to the sealing body 94 of the third dynamic sealing structure 41; the second sealing connection 76 is welded to the mating part 95 of the third dynamic sealing structure 41.

[0107] See Figure 12 and Figure 13In some embodiments, the first air-cooled enclosure 63, the first annular plate 64, the first support cylinder 62, and the stack container 11 form a first connecting ventilation duct 91. The first air-cooled enclosure 63 forms a first air-cooled ventilation hole 631, and the first connecting ventilation duct 91 is connected to the annular negative pressure air duct 101 through the first air-cooled ventilation hole 631. In this embodiment, by forming a first connecting ventilation duct 91 and connecting it with the annular negative pressure air duct 101, air can flow in from the first air inlet 2011, flow through the top plate of the container opening valve 20, and then flow out from the annular negative pressure air duct 101, thus achieving ventilation and cooling of the top of the container opening valve 20, which is beneficial to the stable operation of the container opening valve 20.

[0108] See Figure 12 In some embodiments, the second air-cooled confining cylinder 73, the second annular plate 74, the second support cylinder 72, and the upper top plate 2211 of the container opening valve 20 form a second connecting ventilation duct 92. The second air-cooled confining cylinder 73 forms a second air-cooled ventilation hole 731, and the second connecting ventilation duct 92 is connected to the first air duct 201 through the second air-cooled ventilation hole 731, thereby realizing air circulation between the top of the container opening valve 20 and the top of the control rod drive valve 30.

[0109] See Figure 12 In some embodiments, a first ventilation duct 91 is formed between the first air duct 201 and the annular negative pressure air duct 101, a second ventilation duct 92 is formed between the second air duct 301 and the first air duct 201, and a third ventilation duct 93 is formed between the third air duct 401 and the second air duct 301. A first dynamic sealing structure 21 is disposed in the first ventilation duct 91, a second dynamic sealing structure 31 is disposed in the second ventilation duct 92, and a third dynamic sealing structure 41 is disposed in the third ventilation duct. This arrangement ensures cooling and ventilation of the three-cockpit assembly while also achieving sealing between the individual cockpits.

[0110] See Figure 12 In some embodiments, the container opening stopcock 20 may further include a first ventilation plate 65 disposed between the upper top plate 2211 and the first sealing plate 61. The first ventilation plate 65 forms a through hole, and the area of ​​the first support cylinder 62 located below the first ventilation plate 65 forms a first support cylinder ventilation hole 621 distributed in a circumferential direction. Air in the first air duct 201 flows into the area below the first ventilation plate 65 through the through hole, and enters the first connecting ventilation duct 91 through the first support cylinder ventilation hole 621.

[0111] Accordingly, the control rod drive valve 30 may also include a second ventilation plate disposed between the second top plate 3211 and the second sealing plate 71. The second ventilation plate forms a through hole, and the area of ​​the second support cylinder 72 located below the second ventilation plate forms second support cylinder ventilation holes 721 distributed in a circumferential direction. Air in the second air duct 301 flows into the area below the second ventilation plate through the through hole, and enters the second connecting ventilation duct 92 through the second support cylinder ventilation holes 721. Air in the second connecting ventilation duct 92 enters the first air duct 201 through the second air-cooled ventilation hole 731.

[0112] In some embodiments, the third air-cooled casing 83 forms a third air-cooled ventilation hole 831, and the third connecting ventilation duct 93 is connected to the second air duct 301 through the third air-cooled ventilation hole 831, thereby realizing air circulation between the top of the control rod drive valve 30 and the top of the material changing valve 40.

[0113] Air from the third connecting ventilation duct 93 enters the second air duct 301 through the third air-cooled ventilation hole 831. In the embodiments of this application, by setting a ventilation plate, the air in the first air duct 201, the second air duct 301, and the third air duct 401 flows through the ventilation plate and enters the connecting ventilation duct through the ventilation holes of the support cylinder of each cock, thereby achieving uniform cooling of the top of each cock and improving the operational stability of the three-cocktail assembly.

[0114] The container opening valve 20 is rotatably connected to the container opening 111 via a first bearing 202. The reactor may also include a first drive mechanism 204 for driving the container opening valve 20 to rotate relative to the reactor vessel 11. The first drive mechanism 204 may be disposed on the reactor vessel 11.

[0115] The control rod drive valve 30 is rotatably connected to the first through hole 27 via a second bearing 302. The reactor may also include a second drive mechanism 304 for driving the control rod drive valve 30 to rotate relative to the vessel opening valve 20. The second drive mechanism 304 may be disposed on the vessel opening valve 20.

[0116] The refueling cock 40 is rotatably connected to the second through hole 39 via a third bearing 402. The reactor may also include a third drive mechanism 404 for driving the refueling cock 40 to rotate relative to the control rod drive cock 30. The third drive mechanism 404 may be disposed on the control rod drive cock 30.

[0117] In some embodiments, the container opening stopcock 20 may further include a first gear ring 203 disposed on the first support cylinder 62, and the first drive mechanism 204 meshes with the first gear ring 203 through a transmission gear to drive the container opening stopcock 20 to rotate relative to the stacking container 11.

[0118] In some embodiments, the control rod drive valve 30 may further include a second gear ring 303 disposed on the second support cylinder 72, and the second drive mechanism 304 meshes with the second gear ring 303 through a transmission gear to drive the control rod drive valve 30 to rotate relative to the container opening valve 20.

[0119] In some embodiments, the material changing valve 40 may further include a third gear ring 403 disposed in the third support cylinder 82, and the third drive mechanism 404 meshes with the third gear ring 403 through a transmission gear to drive the material changing valve 40 to rotate relative to the control rod drive valve 30.

[0120] The three-cylinder assembly provided in the embodiments of this application, by setting three cylinders and making the size of the first through hole 27 larger than the radius of the container opening cylinder 20, facilitates the increase of the refueling machine's movement range and reduces the size of the container opening cylinder 20, thereby optimizing the arrangement space of the three-cylinder assembly and improving the reactor's economy and refueling efficiency; by setting multiple shielding layers and dynamic sealing structures, the safety of reactor operation is ensured; by forming multiple air ducts on the top of the three-cylinder assembly, cooling of the three-cylinder assembly is achieved, thereby ensuring the stability of the three-cylinder assembly's operation.

[0121] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0122] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A changing valve for a three-cylinder assembly, used for mounting a changing machine, characterized in that, The three-cocks assembly further includes a container opening cock for rotatably disposed at the container opening of the reactor vessel and a control rod drive cock for mounting a control rod drive mechanism; the control rod drive cock is rotatably disposed at the container opening cock, and the refueling cock is rotatably disposed at the control rod drive cock. The feed changer is provided with an eccentric third through hole, the third through hole being smaller than the radius of the feed changer; The material changing valve also includes a material changing machine tube seat, which is disposed in the third through hole and used to install the material changing machine; The refueling valve also includes: a third body section. The third body segment includes a third housing; The third housing includes a third top plate; The refueling valve also includes: The third sealing plate is disposed above the third top plate, the third support cylinder connects the third sealing plate and the third top plate, the third air-cooled enclosure cylinder is disposed radially outside the third support cylinder, and the third annular plate connects the third air-cooled enclosure cylinder and the third support cylinder. The third sealing plate, the third top plate, and the third support cylinder form a third air duct for ventilating and cooling the third top plate; The third top plate is provided with a third air inlet that communicates with the third air duct; The control rod drive valve includes: a second top plate, a second sealing plate disposed above the second top plate, a second support cylinder connecting the second sealing plate and the second top plate, a second air-cooled confining cylinder disposed radially outside the second support cylinder, and a second annular plate connecting the second air-cooled confining cylinder and the second support cylinder; A second air duct for ventilating and cooling the second top plate is formed between the second sealing plate, the second top plate, the second support cylinder, and the third air-cooled enclosure cylinder. The third air-cooled enclosure, the third annular plate, the third support cylinder, and the second top plate form a third connecting ventilation duct for connecting the second air duct and the third air duct.

2. The refueling valve according to claim 1, characterized in that, The distance between the center of the third through hole and the center of the container opening stopcock is equal to twice the distance between the center of the control rod drive stopcock and the center of the container opening stopcock.

3. The refueling valve according to claim 1, characterized in that, The material changing valve is also provided with an eccentric fourth through hole for placing a spare material changing machine or flow meter; The fourth through hole and the third through hole are symmetrically distributed with respect to the center of the material changing valve, and the center of the fourth through hole, the center of the third through hole and the center of the material changing valve are collinear.

4. The refueling valve according to claim 1, characterized in that, Also includes: The third gamma shielding section and the third connecting section are connected to the third body section through the third connecting section.

5. The refueling valve according to claim 4, characterized in that, The third body section also includes a multi-layer neutron shielding layer and a multi-layer thermal shielding layer disposed within the third housing.

6. The refueling valve according to claim 5, characterized in that, The third housing also includes a third bottom plate, a third radial outer plate, a third through-hole surrounding plate, and a fourth through-hole surrounding plate, which together with the third top plate form a sealed space. The upper part of the sealed space is provided with multiple layers of the neutron shielding layer; The lower part of the sealed space is alternately provided with the neutron shielding layer and the thermal shielding layer, with the thermal shielding layer being the lowest.

7. The refueling valve according to claim 1, characterized in that, Also includes: A third ventilation plate is disposed between the third top plate and the third sealing plate; The third ventilation plate forms a through hole, and the area of ​​the third support cylinder located below the third ventilation plate forms ventilation holes of the third support cylinder distributed in a circumferential direction. The air in the third air duct flows into the lower part of the third ventilation plate through the through hole of the third ventilation plate, and enters the third connecting ventilation duct through the ventilation hole of the third support cylinder.

8. A three-turn plug assembly suitable for a reactor, the reactor comprising a reactor vessel, a core assembly disposed within the reactor vessel, the reactor vessel including a vessel opening coaxial with the core assembly, the reactor further comprising a refueling machine and a control rod drive mechanism, characterized in that, The three-turn valve assembly includes: A container opening stopcock is rotatably disposed at the container opening of the reactor vessel, and the container opening stopcock is provided with an eccentric first through hole, the size of which is larger than the radius of the container opening stopcock. A control rod drive valve is provided in the first through hole of the container opening valve and is rotatable relative to the container opening valve. The control rod drive valve is provided with an eccentric second through hole. A material changing valve is disposed in the second through hole of the control rod drive valve and is rotatable relative to the control rod drive valve; The feed changer is provided with an eccentric third through hole, the third through hole being smaller than the radius of the feed changer; The material changing valve also includes a material changing machine tube seat, which is disposed in the third through hole and used to install the material changing machine; The control rod drive mechanism is disposed in the control rod drive valve, and the material changer is disposed in the third through hole of the material change valve; The refueling valve also includes: a third body section. The third body segment includes a third housing; The third housing includes a third top plate; The refueling valve also includes: The third sealing plate is disposed above the third top plate, the third support cylinder connects the third sealing plate and the third top plate, the third air-cooled enclosure cylinder is disposed radially outside the third support cylinder, and the third annular plate connects the third air-cooled enclosure cylinder and the third support cylinder. The third sealing plate, the third top plate, and the third support cylinder form a third air duct for ventilating and cooling the third top plate; The third top plate is provided with a third air inlet that communicates with the third air duct; The control rod drive valve includes: a second top plate, a second sealing plate disposed above the second top plate, a second support cylinder connecting the second sealing plate and the second top plate, a second air-cooled confining cylinder disposed radially outside the second support cylinder, and a second annular plate connecting the second air-cooled confining cylinder and the second support cylinder; A second air duct for ventilating and cooling the second top plate is formed between the second sealing plate, the second top plate, the second support cylinder, and the third air-cooled enclosure cylinder. The third air-cooled enclosure, the third annular plate, the third support cylinder, and the second top plate form a third connecting ventilation duct for connecting the second air duct and the third air duct.

9. The three-turn valve assembly according to claim 8, characterized in that, The distance between the center of the third through hole and the center of the container opening stopcock is equal to twice the distance between the center of the control rod drive stopcock and the center of the container opening stopcock.

10. The three-turn plug assembly according to claim 8, characterized in that, The material changing valve is also provided with an eccentric fourth through hole for placing a spare material changing machine or flow meter; The fourth through hole and the third through hole are symmetrically distributed with respect to the center of the material changing valve, and the center of the fourth through hole, the center of the third through hole and the center of the material changing valve are collinear.

11. The three-turn plug assembly according to claim 8, characterized in that, The refill valve further includes a third gamma shield section and a third connecting section, wherein the third gamma shield section is connected to the third body section through the third connecting section.

12. The three-turn valve assembly according to claim 11, characterized in that, The third body section also includes a multi-layer neutron shielding layer and a multi-layer thermal shielding layer disposed within the third housing.

13. The three-turn valve assembly according to claim 12, characterized in that, The third housing also includes a third bottom plate, a third radial outer plate, a third through-hole surrounding plate, and a fourth through-hole surrounding plate, which together with the third top plate form a sealed space. The upper part of the sealed space is provided with multiple layers of the neutron shielding layer; The lower part of the sealed space is alternately provided with the neutron shielding layer and the thermal shielding layer, with the thermal shielding layer being the lowest.

14. The three-turn plug assembly according to claim 8, characterized in that, The refueling valve also includes: A third ventilation plate is disposed between the third top plate and the third sealing plate; The third ventilation plate forms a through hole, and the area of ​​the third support cylinder located below the third ventilation plate forms ventilation holes of the third support cylinder distributed in a circumferential direction. The air in the third air duct flows into the lower part of the third ventilation plate through the through hole of the third ventilation plate, and enters the third connecting ventilation duct through the ventilation hole of the third support cylinder.

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