Reactor core melt trapping and decay heat exporting system and method

Abstract

The invention discloses a reactor core melt trapping and decay heat exporting system and method.The system comprises a heat exchanger and trapping solids, the heat exchanger comprises a shell and a heat exchange tube assembly arranged in the shell, the heat exchange tube assembly comprises at least one heat exchange tube, and the heat exchange tube assembly is used for introducing a first cooling medium for heat exchange; the space defined by the heat exchange tube assembly and the shell is a shell pass cavity, and the trapping solid is located in the shell pass cavity and used for melting and absorbing heat when making contact with reactor core melt. According to the system and the method, the safety and the stability of the nuclear power station under the extreme accident condition are improved. Solid for trapping is used as a trapping medium, and the solid for trapping can be melted to form a liquid environment after receiving the reactor core melt. In the process, the molten metal salt not only can effectively capture reactor core melts, but also can exchange heat with the wall surface of a heat transfer pipe of a heat exchange pipe assembly in the heat exchanger, and decay heat is conducted out through the first cooling agent, so that the temperature of the system is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power plant safety, and in particular relates to a system and method for capturing core melt and extracting decay heat. Background Art

[0002] After the serious accidents at the Three Mile Island and Chernobyl nuclear power plants, the nuclear power industry began to focus on research and tackle the prevention and consequence mitigation of serious accidents. Many conclusions have clarified the requirements for preventing and mitigating serious accidents, improving safety and reliability, and improving human factors engineering. When a serious accident occurs in a pressurized water reactor nuclear power plant, the loss of the means of removing residual heat from the core will cause the coolant to evaporate and exhaust, the core will be exposed and continue to heat up, the fuel elements will melt due to the loss of cooling, and the core melt will fall into the lower chamber of the pressure vessel (RPV), which will then cause the lower head of the pressure vessel to fail. If effective measures are not taken to cool it, the core melt may melt through the pressure vessel. After the pressure vessel is melted through, the melt will directly spray onto the raft foundation of the containment and interact with the structural concrete (MCCI), gradually eroding the raft foundation of the containment at a faster speed within a certain period of time. If the raft foundation is not thick enough, the bottom plate may be melted through, resulting in the destruction of the integrity of the containment. Subsequently, radioactive materials will directly enter the soil, causing serious impacts on the environment. In order to avoid the large-scale release of radioactive materials caused by core melt, the relevant design of the core catcher has gradually emerged.

[0003] At present, the cooling and collection strategies of core melt in case of severe accidents can be mainly divided into two types: cooling and maintaining melt inside the pressure vessel (IVR), which is adopted in the design of the AP1000 model in the United States; cooling and collecting melt outside the pressure vessel (EVR), which is adopted in the WWER1000 model in Russia and the EPR model in France. The WWER1000 model adopts a "crucible" core catcher, which is an independent container structure located at the bottom of the pressure vessel, mainly composed of a lower bottom plate, sacrificial materials and a fan-shaped heat exchanger. The EPR model adopts a "spreading" core catcher. In the case of severe accidents, the core forms a flowable liquid melt that flows directly into the reactor pit. Under the action of high temperature, the melt reacts with the sacrificial concrete of the pit, gradually melting the sacrificial concrete, and achieving the function of preliminary cooling and collecting the melt.

[0004] The research on core catchers started earlier in foreign countries, and many related patents have been published. However, the capture efficiency of existing core catchers is low. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a core melt capture and decay heat removal system and method in view of the above-mentioned deficiencies in the prior art, thereby improving the safety and stability of nuclear power plants in extreme accident situations.

[0006] The technical solution adopted to solve the technical problem of the present invention is to provide a core molten material capture and decay heat removal system, including: a heat exchanger, a capture solid, the heat exchanger includes: a shell, a heat exchange tube assembly arranged in the shell, the heat exchange tube assembly includes at least one heat exchange tube, the heat exchange tube assembly is used to pass a first cooling medium for heat exchange, the space enclosed by the heat exchange tube assembly and the shell is a shell side chamber, the capture solid is located in the shell side chamber, and the capture solid is used to melt and absorb heat when it contacts the core molten material.

[0007] Preferably, the capture solid is any one or more of solid metal, solid metal salt, and solid alloy.

[0008] Preferably, the solid metal is lead;

[0009] The solid metal salt is any one of uranium tetrafluoride and thorium tetrafluoride;

[0010] The solid alloy is any one of a sodium-potassium alloy and a lead-bismuth alloy.

[0011] Preferably, the core melt capture and decay heat removal system further comprises:

[0012] The protective layer is arranged on the inner wall of the shell and the outer wall of the heat exchange tube assembly, and the protective layer is formed by a protective material.

[0013] Preferably, the protective material is a high temperature ceramic material, and the protective material is any one of zirconium oxide, aluminum oxide, and beryllium oxide.

[0014] Preferably, the heat exchanger is a tube-sheet heat exchanger, and the heat exchanger further comprises: a tube sheet, the tube sheet is arranged in the shell, and the heat exchange tube assembly is arranged on the tube sheet.

[0015] Preferably, the core melt capture and decay heat removal system further comprises:

[0016] The molten salt pump, the molten salt pump inlet and the molten salt pump outlet are respectively connected with the shell side chamber.

[0017] Preferably, the core melt capture and decay heat removal system further comprises:

[0018] A first cooling device is connected to the inlet of the heat exchange tube assembly, and the first cooling device is used to cool the first cooling medium in the heat exchange tube assembly;

[0019] The first external circulation pump is connected to the first cooling device and the outlet of the heat exchange tube assembly respectively.

[0020] Preferably, the core melt capture and decay heat removal system further comprises:

[0021] The cooling shell layer is arranged on the inner wall of the shell side chamber. The cooling shell layer is used to pass the second cooling medium for heat exchange. After the capture solid is melted into a liquid phase, the second cooling medium exchanges heat with the liquid phase.

[0022] Preferably, the core melt capture and decay heat removal system further comprises:

[0023] A second cooling device is connected to the cooling shell inlet, and the second cooling device is used to cool the second cooling medium in the cooling shell;

[0024] The second external circulation pump is connected to the second cooling device and the cooling shell outlet respectively.

[0025] Preferably, the second cooling medium is any one of water, chlorine, carbon dioxide, nitrogen and oxygen.

[0026] Preferably, the first cooling medium is any one of water, chlorine, carbon dioxide, nitrogen and oxygen.

[0027] The present invention also provides a method for capturing core melt and extracting decay heat using the above system, comprising the following steps:

[0028] Inert gas is introduced into the shell side chamber of the heat exchanger, and the core melt is introduced into the shell side chamber through the inert gas. The capture solid captures the core melt, and the capture solid melts and absorbs heat. The core melt is also cooled through the heat exchange tube assembly.

[0029] Preferably, the inert gas is hydrogen or argon.

[0030] The present invention relates to a system and method for capturing core molten material and extracting decay heat, which improves the safety and stability of nuclear power plants under extreme accident conditions. Capture solids are used as capture media, and these capture solids will melt to form a liquid environment after receiving the core molten material. In this process, the molten metal salt can not only effectively capture the core molten material, but also exchange heat with the wall surface of the heat transfer tube of the heat exchange tube assembly inside the heat exchanger, and extract the decay heat through the first coolant, thereby reducing the temperature of the system. In addition, the flow channel design on the outside of the heat exchange tube assembly helps to establish a simple flow and improve the heat exchange efficiency. The core advantage of the present invention lies in its efficient heat management capabilities and flexible cooling method selection. In extreme cases, such as core melting accidents, the core molten material is effectively captured and the remaining decay heat is extracted to prevent further nuclear accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of a core melt capture and decay heat removal system in Example 2 of the present invention;

[0032] Figure 2It is a schematic diagram of the structure of the core melt capture and decay heat removal system in Example 2 of the present invention.

[0033] In the figure: 1-reactor pressure vessel; 2-molten salt pump; 3-capture solid; 4-inert gas storage tank; 5-tube side fluid; 6-cold trap; 7-protective material; 8-inert gas; 9-reactor pit. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0035] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0036] In the description of this patent, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this patent and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this patent.

[0037] In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, it can be fixedly connected or set, or it can be detachably connected or set, or connected or set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0038] Example 1

[0039] The present embodiment provides a core melt capture and decay heat removal system, including: a heat exchanger, a capture solid, the heat exchanger including: a shell, a heat exchange tube assembly arranged in the shell, the heat exchange tube assembly including at least one heat exchange tube, the heat exchange tube assembly is used to pass a first cooling medium for heat exchange, the space enclosed by the heat exchange tube assembly and the shell is a shell side chamber, the capture solid is located in the shell side chamber, and the capture solid is used to melt and absorb heat when it contacts the core melt.

[0040] This embodiment also provides a method for capturing core melt and extracting decay heat using the above system, including the following steps:

[0041] Inert gas is introduced into the shell side chamber of the heat exchanger, and the core melt is introduced into the shell side chamber through the inert gas. The capture solid captures the core melt, and the capture solid melts and absorbs heat. The core melt is also cooled through the heat exchange tube assembly.

[0042] The present embodiment relates to a system and method for capturing core melt and extracting decay heat, which improves the safety and stability of nuclear power plants under extreme accident conditions. Capture solids are used as capture media, and these capture solids will melt to form a liquid environment after receiving the core melt. In this process, the molten metal salt can not only effectively capture the core melt, but also exchange heat with the heat transfer tube wall of the heat exchange tube assembly inside the heat exchanger, and extract the decay heat through the first coolant to reduce the temperature of the system. In addition, the flow channel design on the outside of the heat exchange tube assembly helps to establish a simple flow and improve the heat exchange efficiency. The core advantage of this embodiment lies in its efficient heat management capabilities and flexible cooling method selection. In extreme cases, such as core melting accidents, the core melt is effectively captured and the remaining decay heat is extracted to prevent further nuclear accidents.

[0043] Example 2

[0044] like Figure 1 , 2 As shown, this embodiment provides a core melt capture and decay heat removal system, including: a heat exchanger, a capture solid 3, the heat exchanger includes: a shell, a heat exchange tube assembly arranged in the shell, the heat exchange tube assembly includes at least one heat exchange tube, the heat exchange tube assembly is used to pass a first cooling medium for heat exchange, the space enclosed by the heat exchange tube assembly and the shell is a shell side chamber, the capture solid 3 is located in the shell side chamber, and the capture solid 3 is used to melt and absorb heat when it contacts the core melt.

[0045] Specifically, in this embodiment, the reactor pressure vessel 1 is located in the reactor pit 9, and the reactor pit 9 is connected to the shell side chamber. After the core melt penetrates the reactor pit, it enters the shell side chamber, and the capture solid 3 melts and absorbs heat when it contacts the core melt. The tube side fluid 5 of the heat exchanger is the first cooling medium.

[0046] Preferably, the capture solid 3 is any one or more of solid metal, solid metal salt, and solid alloy.

[0047] Preferably, the solid metal is lead;

[0048] The solid metal salt is any one of uranium tetrafluoride and thorium tetrafluoride;

[0049] The solid alloy is any one of a sodium-potassium alloy and a lead-bismuth alloy.

[0050] Specifically, the capture solid in this embodiment is solid metal, and the solid metal is lead.

[0051] The capture solid 3 (such as any one of sodium-sodium-potassium alloy, lead, lead-bismuth, uranium tetrafluoride, and thorium tetrafluoride) is introduced on the shell side of the heat exchanger so that it can melt quickly when encountering a high-temperature molten material to form a liquid environment. In this way, heat can be dispersed more effectively and the heat exchange efficiency can be improved.

[0052] Preferably, the core melt capture and decay heat removal system further comprises:

[0053] The protective layer is arranged on the inner wall of the shell and the outer wall of the heat exchange tube assembly, and the protective layer is formed by a protective material 7.

[0054] Preferably, the protective material 7 is a high temperature ceramic material, and the protective material 7 is any one of zirconium oxide, aluminum oxide, and beryllium oxide.

[0055] Specifically, the protective material in this embodiment is zirconium oxide.

[0056] The use of the protective material 7 is to prevent the core melt from directly contacting the heat exchanger shell, especially when the shell is made of metal material. These materials can withstand high temperatures and protect the shell from being damaged or corroded by the melt, thereby extending the service life of the heat exchanger.

[0057] Preferably, the heat exchanger is a tube-sheet heat exchanger, and the heat exchanger further comprises: a tube sheet, the tube sheet is arranged in the shell, and the heat exchange tube assembly is arranged on the tube sheet.

[0058] The core melt capture and decay heat removal system in this embodiment is designed based on the surface heat exchange principle, and specifically adopts a tube-sheet heat exchanger for the core heat exchange process.

[0059] Preferably, the core melt capture and decay heat removal system further comprises:

[0060] The molten salt pump 2, the molten salt pump inlet and the molten salt pump outlet are respectively connected to the shell side chamber.

[0061] The system includes a molten salt pump 2, which is used to stir and homogenize the molten salt for more efficient heat exchange. A protective material 7 is also provided on the surface of the molten salt pump 2 to ensure stable operation under extreme conditions. In addition, the molten salt pump 2 is equipped with a safe emergency power supply, or is powered by a thermoelectric conversion device to improve the self-sufficiency of the system.

[0062] Preferably, the core melt capture and decay heat removal system further comprises:

[0063] A first cooling device, connected to the inlet of the heat exchange tube assembly, and used to cool the first cooling medium in the heat exchange tube assembly, the first cooling device is a cold trap 6;

[0064] The first external circulation pump is connected to the first cooling device and the outlet of the heat exchange tube assembly respectively.

[0065] Preferably, the core melt capture and decay heat removal system further comprises:

[0066] The cooling shell layer is arranged on the inner wall of the shell side chamber. The cooling shell layer is used to pass the second cooling medium for heat exchange. After the capture solid 3 is melted into a liquid phase, the second cooling medium exchanges heat with the liquid phase.

[0067] Preferably, the core melt capture and decay heat removal system further comprises:

[0068] A second cooling device is connected to the cooling shell inlet, and the second cooling device is used to cool the second cooling medium in the cooling shell;

[0069] The second external circulation pump is connected to the second cooling device and the cooling shell outlet respectively.

[0070] Preferably, the second cooling medium is any one of water, chlorine, carbon dioxide, nitrogen and oxygen.

[0071] Preferably, the first cooling medium is any one of water, chlorine, carbon dioxide, nitrogen and oxygen.

[0072] The first cooling medium is the tube-side fluid 5 of the heat exchanger, which is used to carry and conduct heat.

[0073] The shell side of the heat exchanger comprises protective material 7, capture solid 3, molten salt pump 2 and inert gas 8. The shell side chamber is connected to the inert gas storage tank 4, and the inert gas 8 is introduced into the shell side chamber through the inert gas storage tank 4.

[0074] This embodiment also provides a method for capturing core melt and extracting decay heat using the above system, including the following steps:

[0075] Inert gas 8 is introduced into the shell side chamber of the heat exchanger, and the core melt is introduced into the shell side chamber through the inert gas 8. The capture solid 3 captures the core melt, and the capture solid 3 melts and absorbs heat. The core melt is also cooled through the heat exchange tube assembly.

[0076] Preferably, the inert gas 8 is hydrogen or argon.

[0077] Inert gas 8, such as hydrogen or argon, is introduced into the shell side of the heat exchanger. These gases can help the core melt to quickly enter the heat exchanger, effectively melt the capture solid 3 on the shell side, and help eliminate potential spaces such as water vapor and hydrogen, thereby optimizing the heat exchange process.

[0078] The working process of the system mainly involves several key steps to achieve effective capture of core melt and extraction of decay heat:

[0079] Core molten material capture: When a serious accident occurs in a nuclear reactor and the core begins to melt, the high-temperature core molten material will be guided into the shell side of the heat exchanger. The capture solid 3 contained in the shell side of the heat exchanger will melt rapidly after contacting the high-temperature molten material, forming a liquid environment. In this process, a large amount of heat is absorbed, thereby playing the role of capturing the molten material and initially cooling it.

[0080] Heat exchange process: The melted solid capture 3 (now containing the heat of the core melt) then exchanges heat with the heat exchange tube assembly inside the system. The first cooling medium (tube side fluid 5), such as water, flowing in the heat exchange tube assembly absorbs the heat in the melted solid capture 3, thereby further reducing the temperature of the system.

[0081] Coolant circulation: The first cooling medium after absorbing heat is led out of the heat exchanger through the external circulation of the system, releases heat to the environment through the first cooling device or other cooling devices, and then returns to the heat exchanger after cooling again, forming a closed circulation cooling system.

[0082] Function of the molten salt pump 2: In order to ensure that the molten capture solid 3 can evenly distribute heat and effectively exchange heat with the heat exchange tube assembly, the molten salt pump 2 works continuously throughout the process to stir the melt and the molten capture solid 3 to maintain their fluidity, thereby optimizing the heat exchange efficiency.

[0083] Inert gas 8 protection: During the entire process, the shell side is filled with inert gas 8 (such as argon or nitrogen) to prevent the molten material from chemically reacting or oxidizing when in contact with the outside air. It also helps to reduce the direct contact between the molten material and the heat exchanger material, reducing the risk of corrosion.

[0084] Heat extraction: Through this series of heat exchange and cooling cycles, the heat in the core melt is eventually effectively extracted from the system, thereby protecting the nuclear reactor structure from direct damage by the high-temperature melt and slowing down the further development of the accident. The heat of the core melt is effectively extracted through the outer shell cooling system. The active circulation process outside the shell is a way to force the flow of the cooling medium through an external power system, such as the first external circulation pump and the second external circulation pump, so as to achieve efficient heat extraction. The heated first cooling medium is then pumped out of the heat exchange tube assembly by the first external circulation pump and flows into the external first cooling device, such as the cooling water system. In these external cooling devices, the first cooling medium releases the absorbed heat to the external water body or to the atmosphere through evaporative heat dissipation through further heat exchange. After releasing the heat, the temperature of the first cooling medium drops and is pumped back to the heat exchange tube assembly by the first external circulation pump again to continue to participate in the next round of heat absorption and transfer process. In this way, a closed loop is formed to continuously extract decay heat.

[0085] Through the above working process, the system can effectively handle the core melt when a serious accident occurs in a nuclear reactor.

[0086] In addition, the heat of the system described in this patent needs to be further extracted to ensure the stability of the system, so the setting of the cooling device of the system needs to be considered. At this time, the cooling system has two modes: internal shell circulation and external shell circulation cooling.

[0087] The above scheme (such as Figure 1 As shown in FIG. 1 , the heat exchanger tube side fluid 5 takes away the heat of the melted capture solid 3 containing the molten fuel. The overall operating principle is as follows: Figure 2 shown.

[0088] The present embodiment relates to a system and method for capturing core melt and extracting decay heat, which improves the safety and stability of nuclear power plants under extreme accident conditions. Using capture solids 3 as capture media, these capture solids 3 will melt to form a liquid environment after receiving the core melt. In this process, the molten metal salt can not only effectively capture the core melt, but also exchange heat with the heat transfer tube wall of the heat exchange tube assembly inside the heat exchanger, and extract the decay heat through the first coolant to reduce the temperature of the system. In addition, the flow channel design on the outside of the heat exchange tube assembly helps to establish a simple flow and improve the heat exchange efficiency. The core advantage of this embodiment lies in its efficient heat management capabilities and flexible cooling method selection. In extreme cases, such as core melting accidents, the core melt is effectively captured and the remaining decay heat is extracted to prevent further nuclear accidents.

[0089] Example 3

[0090] This embodiment provides a core melt capture and decay heat removal system, which is different from the embodiment 2 in that:

[0091] The capture solid in this embodiment is a solid metal salt, and the solid metal salt is uranium tetrafluoride.

[0092] The protective material in this embodiment is aluminum oxide.

[0093] This embodiment also provides a method for capturing core melt and extracting decay heat using the above system, comprising the following steps:

[0094] Inert gas is introduced into the shell side chamber of the heat exchanger, and the core melt is introduced into the shell side chamber through the inert gas. The capture solid captures the core melt, and the capture solid melts and absorbs heat. The core melt is also cooled through the heat exchange tube assembly.

[0095] Example 4

[0096] This embodiment provides a core melt capture and decay heat removal system, which is different from the embodiment 2 in that:

[0097] The capture solid in this embodiment is a solid metal salt, and the solid metal salt is thorium tetrafluoride.

[0098] The protective material in this embodiment is beryllium oxide.

[0099] This embodiment also provides a method for capturing core melt and extracting decay heat using the above system, including the following steps:

[0100] Inert gas is introduced into the shell side chamber of the heat exchanger, and the core melt is introduced into the shell side chamber through the inert gas. The capture solid captures the core melt, and the capture solid melts and absorbs heat. The core melt is also cooled through the heat exchange tube assembly.

[0101] Example 5

[0102] This embodiment provides a core melt capture and decay heat removal system, which is different from the embodiment 2 in that:

[0103] The capture solid in this embodiment is a solid alloy, and the solid alloy is a sodium-potassium alloy.

[0104] This embodiment also provides a method for capturing core melt and extracting decay heat using the above system, comprising the following steps:

[0105] Inert gas is introduced into the shell side chamber of the heat exchanger, and the core melt is introduced into the shell side chamber through the inert gas. The capture solid captures the core melt, and the capture solid melts and absorbs heat. The core melt is also cooled through the heat exchange tube assembly.

[0106] Example 6

[0107] This embodiment provides a core melt capture and decay heat removal system, which is different from the embodiment 2 in that:

[0108] The capture solid in this embodiment is a solid alloy, and the solid alloy is a lead-bismuth alloy.

[0109] This embodiment also provides a method for capturing core melt and extracting decay heat using the above system, including the following steps:

[0110] Inert gas is introduced into the shell side chamber of the heat exchanger, and the core melt is introduced into the shell side chamber through the inert gas. The capture solid captures the core melt, and the capture solid melts and absorbs heat. The core melt is also cooled through the heat exchange tube assembly.

[0111] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A core melt capture and decay heat removal system, characterized in that: include: A heat exchanger and a solid for capture. The heat exchanger comprises: a shell, a heat exchange tube assembly arranged in the shell, the heat exchange tube assembly comprises at least one heat exchange tube, the heat exchange tube assembly is used for passing a first cooling medium for heat exchange, the space enclosed between the heat exchange tube assembly and the shell is a shell side chamber, the solid for capture is located in the shell side chamber, and the solid for capture is used for melting and absorbing heat when it contacts the core molten material.

2. The core melt capture and decay heat removal system according to claim 1, characterized in that: The capture solid is any one or more of solid metal, solid metal salt and solid alloy.

3. The core melt capture and decay heat removal system according to claim 2, characterized in that: The solid metal is lead; The solid metal salt is any one of uranium tetrafluoride and thorium tetrafluoride; The solid alloy is any one of a sodium-potassium alloy and a lead-bismuth alloy.

4. The core melt capture and decay heat removal system according to claim 1, characterized in that: Also includes: The protective layer is arranged on the inner wall of the shell and the outer wall of the heat exchange tube assembly, and the protective layer is formed by a protective material.

5. The core melt capture and decay heat removal system according to claim 4, characterized in that: The protective material is a high temperature ceramic material, and the protective material is any one of zirconium oxide, aluminum oxide, and beryllium oxide.

6. The core melt capture and decay heat removal system according to claim 1, characterized in that: The heat exchanger is a tube-sheet heat exchanger, and the heat exchanger further comprises: a tube sheet, the tube sheet is arranged in the shell, and the heat exchange tube assembly is arranged on the tube sheet.

7. The core melt capture and decay heat removal system according to claim 1, characterized in that: Also includes: The molten salt pump, the molten salt pump inlet and the molten salt pump outlet are respectively connected with the shell side chamber.

8. The core melt capture and decay heat removal system according to claim 1, characterized in that: Also includes: A first cooling device is connected to the inlet of the heat exchange tube assembly, and the first cooling device is used to cool the first cooling medium in the heat exchange tube assembly; The first external circulation pump is connected to the first cooling device and the outlet of the heat exchange tube assembly respectively.

9. The core melt capture and decay heat removal system according to claim 1, characterized in that: Also includes: The cooling shell layer is arranged on the inner wall of the shell side chamber, and the cooling shell layer is used for passing the second cooling medium for heat exchange.

10. The core melt capture and decay heat removal system according to claim 9, characterized in that: Also includes: A second cooling device is connected to the cooling shell inlet, and the second cooling device is used to cool the second cooling medium in the cooling shell; The second external circulation pump is connected to the second cooling device and the cooling shell outlet respectively.

11. The core melt capture and decay heat removal system according to claim 9, characterized in that: The second cooling medium is any one of water, chlorine, carbon dioxide, nitrogen and oxygen.

12. The core melt capture and decay heat removal system according to any one of claims 1 to 11, characterized in that: The first cooling medium is any one of water, chlorine, carbon dioxide, nitrogen and oxygen.

13. A method for capturing core melt and extracting decay heat using the system according to any one of claims 1 to 12, characterized in that: The following steps are involved: Inert gas is introduced into the shell side chamber of the heat exchanger, and the core melt is introduced into the shell side chamber through the inert gas. The capture solid captures the core melt, and the capture solid melts and absorbs heat. The core melt is also cooled through the heat exchange tube assembly.

14. The method for capturing core melt and extracting decay heat according to claim 13, characterized in that: The inert gas is hydrogen or argon.

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