A ductile containment structure with expansion membrane

Abstract

A resilient containment structure with an expansion membrane belongs to the field of nuclear power safety technology. The present invention addresses the problem of single failure performance in the load-resistance model of the nuclear island containment, which can easily cause accidents. The present invention's solution: Under normal conditions, the prestressed spring is in a compressed state. When the pressure within the steel containment increases, the high-pressure gas from the accident enters the annular cavity and space 2 through the bleed valve, releasing the prestressed pressure in the prestressed spring, which together lifts the dome. Water from the cooling water tank enters space 3, expanding the expansion membrane. The pressure decreases, reaching the expansion state. Then, the bleed valve is closed, and the drain valve is opened, allowing the water in the cooling water tank to be discharged into the annular cavity and space 2, cooling the interior of the steel containment. After cooling and pressure reduction are complete, the prestressed spring contracts, the dome descends, and the expansion membrane recovers, entering a recovery state.

Description

Technical Field

[0001] The invention relates to a tough containment structure with an expansion membrane, belonging to the technical field of nuclear power safety. Background Art

[0002] The nuclear island containment is the outermost enclosure of the nuclear power plant and the final barrier to nuclear safety. In the event of a serious accident, it must effectively withstand the pressure and temperature of the nuclear island while maintaining a tight seal and accident containment. This ensures the safety of nuclear power plant personnel and the surrounding public in extreme environments such as strong winds, earthquakes, explosions, and nuclear accidents, while protecting the surrounding environment from nuclear leakage that could contaminate the environment beyond acceptable limits.

[0003] Nuclear island containment structures can be divided into three types based on their structural systems: reinforced concrete, prestressed concrete, and steel. To reduce costs and construction difficulty, concrete containment was adopted and gradually developed. Currently, the most commonly used structure in existing nuclear power plants is a single-layer prestressed concrete shell with a steel lining. Although nuclear power plant containment structures utilize a structural reliability analysis method that takes into account design uncertainties such as material properties and load variations, this method allows engineers to assess the containment's reliability over its design life and ensure its performance under various uncertainties. However, due to its application of a load-resistance model and method, it is based on single-failure performance and cannot prevent single-failure mode failures from causing serious accidental consequences in nuclear power plants.

[0004] Currently, nuclear island containment designs both domestically and internationally are designed using the load-resistance model. This model is a fundamental physical model in structural and civil engineering, used to describe the interaction and relationship between a structure's external loads and its resistance. By plotting the load S and resistance R, along with their probability distributions, in the same coordinate system, the equation of state G = RS allows for intuitive judgment of structural failure. When resistance R is greater than load S, the structure is in a safe state, meaning it can function normally. When resistance R is less than load S, the structure is in a failed state, meaning it cannot function normally. When resistance R equals load S, the structure is in a safety limit state, or the ultimate operating state. This region is referred to as the interference zone between load S and resistance R. Because the factors influencing load S and resistance R are random, the main factors affecting generalized load S include the external load, the structural geometry and dimensions, and the physical properties of the material. The main factors affecting generalized resistance R include the mechanical properties of the material, the processing method, and the operating environment. That is, both load S and resistance R are random variables with a probability distribution. In a generalized sense, load S is the load that causes failure, and in a generalized sense, resistance R is the ability to resist failure. Obviously, the load-resistance model is based on a single state equation and does not reflect the ability of the structure to recover to other equilibrium safe states.

[0005] The contradiction between the single steady state of the load-resistance model and the study of multiple stable states in complex systems has become increasingly prominent. Based on the fact that ecosystems have multiple stable equilibrium states, Berkes and Falk proposed that systems can exist in multiple equilibrium states, that is, external disturbances can cause the system to shift from one equilibrium state to another. Based on this, they proposed ecological resilience. The word "resilience" derives from the Latin "Re-silio" (Re = back; Silio = to leap), meaning the act of jumping back. In the mid-19th century, resilience was successfully applied to mechanical engineering to describe the ability of mechanical structures to return to their original state after external forces, and gradually developed into the theory of engineering resilience. Because engineering resilience only has a single stable state and is inconsistent with the multiple stable states of ecosystems, Holling in 1973 studied the ability of ecosystems to recover, namely, the ability of ecosystems to evolve from one equilibrium state to another under external disturbances, thus developing ecological resilience into engineering resilience. In 1998, Berkes applied ecological resilience to human social phenomena and found that ecological resilience only reflects equilibrium states and cannot reflect the evolutionary complexity of society. Based on this, in 2004, Walker et al. described the dynamic process of change, adaptation, and transformation in societies triggered by pressures and constraints, and proposed the concept of evolutionary resilience. The 2015 Third United Nations Conference on Disaster Risk Reduction defined resilience as the ability of a system, community, or society exposed to hazards to effectively and promptly resist, absorb, adapt to, and recover from disasters by protecting and restoring essential structures and functions. Clearly, evolutionary resilience has become a growing trend in the study of the safety performance of complex systems. Summary of the Invention

[0006] Aiming at the problem that the nuclear island containment is prone to accidents due to a single failure performance when applying a load-resistance confrontation model, the present invention provides a tough containment structure with an expansion membrane.

[0007] The flexible containment structure with an expansion membrane of the present invention comprises a containment shell 1, a dome 2, a steel containment shell 3, a gas relief valve 4, a prestressed spring 5, a cooling water tank 6, an expansion membrane 7 and a water relief valve 8;

[0008] The steel containment shell 3 is attached to the inner wall of the containment shell 1 and forms a roof structure at the top opening of the containment shell 1; the dome 2 is slidably connected to the top opening of the containment shell 1, and the expansion membrane 7 is fixedly connected to the top opening of the containment shell 1 and stacked on top of the dome 2;

[0009] The annular cavity formed by the dome 2 and the containment shell 1 at the sliding connection section serves as a cooling water tank 6, which is replenished with water from the outside as needed; an annular cavity 9 is formed below the cooling water tank 6 and between the outer wall of the steel containment shell 3 and the containment shell 1;

[0010] A plurality of longitudinally retractable prestressed springs 5 ​​are arranged along the circumferential direction between the bottom end of the dome 2 and the top end of the containment shell 1;

[0011] A gas relief valve 4 is provided on the side wall of the steel containment shell 3 at the connection between the dome 2 and the containment shell cylinder 1. The gas relief valve 4 serves as a passage for gas circulation in the containment shell and is used for atmospheric balance between the interior of the containment shell and the annular cavity 9.

[0012] A drain valve 8 is provided between the cooling water tank 6 and the annular cavity 9 for draining the water in the cooling water tank 6 into the annular cavity 9;

[0013] Under normal conditions, the drain valve 8 is closed, the prestressed spring 5 is in a compressed state, and the annular cavity 9 is empty; the air relief valve 4 is closed, and there is no communication between the interior of the steel containment vessel 3 and the annular cavity 9; the expansion membrane 7 is attached to the top of the dome 2;

[0014] When the pressure in the steel containment shell 3 increases, the relief valve 4 opens, and the accident high-pressure gas in the containment shell enters the annular cavity 9 and the space 2 between the steel containment shell 3 and the dome 2 connected thereto through the relief valve 4. The prestressed spring 5 releases the pre-stress, and together they lift the dome 2 and make it slide upward along the side wall of the containment shell cylinder 1. The water in the cooling water tank 6 enters the space 3 between the expansion membrane 7 and the dome 2, and the expansion membrane 7 is expanded. The capacity of the containment shell increases, and the pressure decreases, reaching the expansion state.

[0015] Then, the air release valve 4 is closed and the water release valve 8 is opened. The water in the cooling water tank 6 is released into the annular cavity 9 and the space 2. The cooling water and the hot air meet and condense in the space 2. The steel containment shell 3 acts as a heat transfer surface. The steam condenses on the inner and outer surfaces and releases heat, achieving temperature and pressure reduction, and reaching a cooling layer flow state.

[0016] After the temperature and pressure are lowered, the prestressed spring 5 contracts, the dome 2 descends, and the expansion membrane 7 recovers, entering a recovery state.

[0017] Preferably, the top of the containment shell 1 has an outward convex sliding section, which includes a bottom ring 1-1, a sliding side wall 1-2 and a limit ring 1-3. The bottom ring 1-1 is connected between the top of the side wall of the containment shell 1 and the bottom end of the sliding side wall 1-2. The upper inner wall of the sliding side wall 1-2 is provided with a limit ring 1-3.

[0018] The outer side wall of the bottom end of the dome 2 has an upper side ring 2-1 and a lower side ring 2-2;

[0019] In the normal state, the upper ring 2-1 is aligned and spliced ​​with the limit ring 1-3 to form a complete ring, and the lower ring 2-2 slides up and down along the sliding side wall 1-2. In the normal state, when the dome 2 is in the lower limit position, the annular cavity surrounded by the lower ring 2-2, the sliding side wall 1-2 and the upper aligned and spliced ​​upper ring 2-1 and the limit ring 1-3 serves as a cooling water tank 6;

[0020] A prestressed spring 5 is provided between the lower surface of the lower ring 2 - 2 of the dome 2 and the upper surface of the bottom ring 1 - 1 of the containment shell 1 .

[0021] Preferably, the capacity expansion membrane 7 includes a support layer 7-1, a sealing layer 7-2 and a radiation shielding layer 7-3; the support layer 7-1, the sealing layer 7-2 and the radiation shielding layer 7-3 are stacked in sequence.

[0022] Preferably, the steel containment shell 3 and the containment shell cylinder 1 are fixedly connected by welding.

[0023] Beneficial effects of the present invention:

[0024] The present invention adds a special membrane structure on the basis of the above-mentioned expandable containment with variable height, which is referred to as an expansion membrane in the present invention. The membrane has a multi-layer structure, including a radiation shielding layer, a sealing layer and a support layer. The radiation shielding layer is used to block the penetration of radioactive particles, the sealing layer is used to ensure the sealing performance of the membrane, and the support layer is used to improve the mechanical strength and stability of the membrane. Therefore, the membrane structure selects materials with high density and radiation shielding capabilities as the main material, such as lead, tungsten or polymer lead. These materials can effectively block the penetration of radioactive particles and reduce the possibility of leakage. At the same time, considering that radioactive substances may be corrosive, the material of the membrane needs to have good corrosion resistance and be able to maintain stability and functionality under long-term contact with radioactive substances. The expansion membrane wraps the entire containment dome. When the containment is working normally, the expansion membrane is close to the outer surface of the dome, and the water tank part is folded and stacked on top of the cooling water tank. When an accident occurs, the expansion membrane is opened to contain radioactive gases or be used as a temporary water tank.

[0025] This invention improves the containment shell's traditional connection method, imbuing it with ecological resilience. By utilizing prestressed springs and accident pressure, the containment shell's height is resiliently altered, expanding its volume during an accident, thereby reducing internal pressure and simultaneously expanding the expansion membrane to prevent radioactive leakage. If the temperature inside the containment shell exceeds the safety threshold during an accident, cooling water is supplied through a cooling water tank connected to the expansion membrane, filling the outer surface of the containment shell with cooling water, forming a cooling layer and accelerating the cooling process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 11 is a schematic structural diagram of a flexible containment structure with an expansion membrane according to the present invention, in a normal working state 1;

[0027] Figure 2 2 is a schematic structural diagram of a flexible containment structure with an expansion membrane according to the present invention, in expansion state 2;

[0028] Figure 3 3 is a schematic structural diagram of a flexible containment structure with an expansion membrane according to the present invention, in a cooling layer flow state 3;

[0029] Figure 4 is a schematic structural diagram of a flexible containment structure with an expansion membrane according to the present invention, in a recovery state 4;

[0030] Figure 5 yes Figure 1 A partial enlarged view of

[0031] Figure 6 It is a structural diagram of the expansion membrane. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0035] Specific implementation method 1: Figures 1 to 6 This embodiment is described. A flexible containment structure with an expansion membrane in this embodiment includes a containment shell 1, a dome 2, a steel containment shell 3, a gas relief valve 4, a prestressed spring 5, a cooling water tank 6, an expansion membrane 7, and a water relief valve 8.

[0036] The steel containment shell 3 is attached to the inner wall of the containment shell 1 and forms a roof structure at the top opening of the containment shell 1; the dome 2 is slidably connected to the top opening of the containment shell 1, and the expansion membrane 7 is fixedly connected to the top opening of the containment shell 1 and stacked on top of the dome 2;

[0037] The annular cavity formed by the dome 2 and the containment shell 1 at the sliding connection section serves as a cooling water tank 6, which is replenished with water from the outside as needed; an annular cavity 9 is formed below the cooling water tank 6 and between the outer wall of the steel containment shell 3 and the containment shell 1;

[0038] A plurality of longitudinally retractable prestressed springs 5 ​​are arranged along the circumferential direction between the bottom end of the dome 2 and the top end of the containment shell 1;

[0039] A gas relief valve 4 is provided on the side wall of the steel containment shell 3 at the connection between the dome 2 and the containment shell cylinder 1. The gas relief valve 4 serves as a passage for gas circulation in the containment shell and is used for atmospheric balance between the interior of the containment shell and the annular cavity 9.

[0040] A drain valve 8 is provided between the cooling water tank 6 and the annular cavity 9 for draining the water in the cooling water tank 6 into the annular cavity 9;

[0041] Under normal conditions, the drain valve 8 is closed, the prestressed spring 5 is in a compressed state, and the annular cavity 9 is empty; the air relief valve 4 is closed, and there is no communication between the interior of the steel containment shell 3 and the annular cavity 9; the expansion membrane 7 is attached to the top of the dome 2, see Figure 1 As shown;

[0042] When the pressure in the steel containment 3 increases, the relief valve 4 opens, and the accident high-pressure gas in the containment enters the annular cavity 9 and the space 2 between the steel containment 3 and the dome 2 connected thereto through the relief valve 4. The prestressed spring 5 releases the pre-pressure, and together they lift the dome 2 and make it slide upward along the side wall of the containment cylinder 1. Figure 2 As shown; the water in the cooling water tank 6 enters the space 3 between the expansion membrane 7 and the dome 2, and the expansion membrane 7 is expanded; the containment capacity increases, the pressure decreases, and the expansion state is reached, see Figure 3 As shown;

[0043] Then, close the air release valve 4 and open the water release valve 8. The water in the cooling water tank 6 is released into the annular cavity 9 and the space 2. The cooling water and the hot air meet and condense in the space 2. The steel containment shell 3 acts as a heat transfer surface. The steam condenses on the inner and outer surfaces and releases heat, achieving temperature and pressure reduction, and reaching a cooling layer flow state. Figure 4 As shown;

[0044] After the temperature and pressure are lowered, the prestressed spring 5 contracts, the dome 2 descends, and the expansion membrane 7 recovers, entering a recovery state.

[0045] Space 1: inside the containment vessel;

[0046] Space 2: between the steel containment vessel 3 and the dome 2;

[0047] Space 3: between the expansion membrane 7 and the dome 2.

[0048] State 1: Figure 1 Normal state shown;

[0049] State 2: Figure 2 The dome is shown in its raised state;

[0050] State 3: Figure 3 The expansion status shown;

[0051] State 4: Figure 4 The recovery status is shown.

[0052] See also Figure 5 As shown, the top of the containment shell 1 has an outward convex sliding section, which includes a bottom ring 1-1, a sliding side wall 1-2 and a limit ring 1-3. The bottom ring 1-1 is connected between the top of the side wall of the containment shell 1 and the bottom end of the sliding side wall 1-2. The upper inner wall of the sliding side wall 1-2 is provided with a limit ring 1-3.

[0053] The outer side wall of the bottom end of the dome 2 has an upper side ring 2-1 and a lower side ring 2-2;

[0054] In the normal state, the upper ring 2-1 is aligned and spliced ​​with the limit ring 1-3 to form a complete ring, and the lower ring 2-2 slides up and down along the sliding side wall 1-2. In the normal state, when the dome 2 is in the lower limit position, the annular cavity surrounded by the lower ring 2-2, the sliding side wall 1-2 and the upper aligned and spliced ​​upper ring 2-1 and the limit ring 1-3 serves as a cooling water tank 6;

[0055] A prestressed spring 5 is provided between the lower surface of the lower ring 2 - 2 of the dome 2 and the upper surface of the bottom ring 1 - 1 of the containment shell 1 .

[0056] See also Figure 6 As shown, the capacity expansion membrane 7 includes a support layer 7-1, a sealing layer 7-2 and a radiation shielding layer 7-3; the support layer 7-1, the sealing layer 7-2 and the radiation shielding layer 7-3 are stacked in sequence.

[0057] The present invention builds upon the previously described expandable containment vessel with variable height flexibility by incorporating a unique membrane structure, referred to herein as an expandable membrane. This membrane has a multi-layered structure, comprising a support layer 7-1, a sealing layer 7-2, and a radiation shielding layer 7-3. The radiation shielding layer 7-3 blocks the penetration of radioactive particles, the sealing layer 7-2 ensures the membrane's sealing performance, and the support layer 7-1 enhances the membrane's mechanical strength and stability. Therefore, the membrane structure is constructed from materials with high density and radiation shielding capabilities, such as lead, tungsten, or polymer lead. These materials effectively block the penetration of radioactive particles and reduce the possibility of leakage. Furthermore, given the potential corrosiveness of radioactive materials, the membrane material must possess excellent corrosion resistance and be able to maintain stability and functionality even under long-term exposure to radioactive materials. The expandable membrane wraps the entire dome 2 of the containment vessel. During normal operation, the expandable membrane 7 adheres closely to the outer surface of the dome 2, while the cooling water tank 6 portion is folded and stacked on top of the cooling water tank 9. In the event of an accident, the expandable membrane 7 unfolds to contain radioactive gases or serve as a temporary water tank.

[0058] Production and installation process:

[0059] The specific implementation method of the present invention is essentially the same as that of traditional containment construction. First, before construction begins, a construction site must be selected. Once a suitable site is chosen, the ground must be cleaned and leveled to ensure the safety and stability of the construction area. Only then can the construction of the nuclear containment vessel officially begin.

[0060] After the construction area is determined, the basic construction work of the nuclear containment vessel begins. This includes excavating the foundation pit, pouring the concrete foundation, and laying underground pipes and cable channels.

[0061] While the above work is ongoing, the containment main shell and expansion membrane can be prefabricated in a dedicated factory according to the inventive design. After the foundation work is completed, they will be transported to the construction site for assembly. During the assembly process, the quality and dimensions of the components must be strictly controlled to ensure that the final containment structure meets the design requirements.

[0062] According to the design requirements, the containment shell 1 required for concrete pouring is properly installed. After the containment shell 1 is partially installed, a steel lining is sequentially positioned, assembled, and welded layer by layer across the entire inner surface of the shell, forming a single unit with the steel containment shell 3. A prestressed spring 5 is installed at the top of the containment shell 1, and the top of the prestressed spring 5 is welded to the reinforced concrete dome 2. The bottom of the steel containment shell 3 is welded to the containment shell 1, forming a continuous, integrated structure. An air relief valve 4 is installed at the level of the prestressed spring 5, and a water relief valve 8 is installed at the bottom of the reinforced concrete dome. Only the cylinder portion of the steel containment shell is connected to the reinforced concrete containment shell. The dome portion can be separated from the reinforced concrete dome to form a space 2, allowing for expansion of the containment shell. Except for the bottom end of the reinforced concrete dome 2, which is welded to the prestressed spring 5, the rest of the reinforced concrete dome 2 can move up and down as the spring expands and contracts. This movement of the reinforced concrete dome 2 causes the cooling water tank to move, allowing cooling water to enter space 3. Finally, a special expansion membrane 7 is installed on the outer surface of the reinforced concrete containment dome 2. The end of the expansion membrane 7 is firmly connected to the upper end of the containment cylinder 1, and sufficient expansion margin is reserved. When the dome 2 is lifted, cooling water enters the space 3, and the expansion membrane 7 is expanded. After the temperature and pressure are reduced, the expansion membrane 7 is restored. During the entire working process, the containment maintains the strength, airtightness and anti-radioactive material leakage functions required by the project. The present invention also adds a new function of expandable toughness.

[0063] Workflow:

[0064] The present invention achieves the toughness function of the containment shell for special properties such as extremely high safety and disaster material containment by changing the structure of the containment shell cylinder and inventing a method of expanding the membrane. When the pressure reaches the expected safety threshold, the volume of the containment shell is increased to reduce the accident pressure, thereby achieving the transition from state 1 to state 2. When the temperature reaches the expected safety threshold, a cooling layer is formed on the outer surface of the steel containment shell 3 by opening the drain valve 8, achieving the transition from state 2 to state 3 and achieving the purpose of cooling. At the same time, the expansion membrane 7 ensures the sealing and accident containment functions of the containment shell, significantly improving the safety performance of the containment shell in preventing the leakage of radioactive materials, and opening up new technologies and methods for improving the containment shell of nuclear power plants and their disaster prevention performance.

[0065] This is achieved primarily through a novel connection method for the containment cylinder. Under normal operating conditions, the prestressed spring 5 at the bottom of the dome 2 is compressed, holding the dome 2 in close contact with the steel containment 3 and the expansion membrane 7 against the dome 2. In the event of an accident, the prestressed spring 5 releases its preload, acting along with the accident pressure on the containment dome 2, lifting the dome 2, increasing the containment height, volume, and pressure.

[0066] A membrane expansion 7 is attached to the outer surface of the containment dome at the top of the water tank. This membrane expansion 7 is a special membrane structure consisting of three layers: a radiation shielding layer, a sealing layer, and a support layer. During normal containment operation, the membrane expansion 7 adheres closely to the outer surface of the dome 2. In the event of an accident, cooling water expands the membrane expansion 7, creating a space 3 with the dome 2. This serves as a temporary container for the cooling water, forming a cooling flow layer. This increases the contact area between the containment and the cooling water, accelerating the cooling rate of the containment after an accident.

[0067] At the beginning of the accident, a large amount of energy is released into the containment vessel, causing space 1 to rapidly heat up and increase in pressure. Heat conduction occurs on the surface of the steel containment vessel 3, achieving a certain degree of cooling. The air vent valve 4 opens, allowing hot air to enter space 2. The accident pressure, combined with the prestressed spring 5, lifts the containment dome 2, allowing cooling water to enter space 3, increasing its volume and reducing pressure. The air vent valve 4 closes, and the water vent valve 8 opens, allowing cooling water in space 3 to enter space 2. Heat convection occurs within space 2, and the steel containment vessel 3 acts as a heat transfer surface. Steam condenses on the inner surface, releasing heat and achieving a cooling effect. As the accident progresses, the energy released into the containment vessel gradually decreases, cooling and decompression are completed, the springs contract, and the dome 2 and expansion membrane 7 recover, completing a single operating cycle. If the next accident occurs, the containment vessel will continue to function normally.

[0068] This invention innovates a design approach based on traditional containment, imbuing the containment model, which previously had a single-failure performance, with new resilience capabilities. This allows the resilient containment to undergo a dynamic process of active change, adaptation, and adaptation under the influence of pressure and constraints. The expansion membrane, in conjunction with the expansion of the containment volume, simultaneously achieves new functions of cooling, reducing pressure, and preventing radioactive material leakage.

[0069] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in conjunction with other described embodiments.

Claims

1. A tough containment structure with an expansion membrane, characterized in that: It comprises a containment shell (1), a dome (2), a steel containment shell (3), a gas relief valve (4), a prestressed spring (5), a cooling water tank (6), an expansion membrane (7) and a water relief valve (8); The steel containment shell (3) is attached to the inner wall of the containment shell cylinder (1) and forms a roof structure at the top opening of the containment shell cylinder (1); the dome (2) is slidably connected to the top opening of the containment shell cylinder (1), and the expansion membrane (7) is fixedly connected to the top opening of the containment shell cylinder (1) and stacked on the top of the dome (2); The annular cavity formed by the dome (2) and the containment shell (1) at the sliding connection section serves as a cooling water tank (6), and the cooling water tank (6) is replenished with water from the outside as needed; an annular cavity (9) is formed below the cooling water tank (6) and between the outer wall of the steel containment shell (3) and the containment shell (1); A plurality of longitudinally retractable prestressed springs (5) are arranged along the circumference between the bottom end of the dome (2) and the top end of the containment shell (1); A gas relief valve (4) is provided on the side wall of the steel containment shell (3) at the connection between the dome (2) and the containment shell cylinder (1). The gas relief valve (4) serves as a passage for gas circulation in the containment shell and is used for atmospheric balance between the interior of the containment shell and the annular cavity (9). A drain valve (8) is provided between the cooling water tank (6) and the annular cavity (9) for draining the water in the cooling water tank (6) into the annular cavity (9); Under normal conditions, the water discharge valve (8) is closed, the prestressed spring (5) is in a compressed state, and the annular cavity (9) is empty; the air discharge valve (4) is closed, and the interior of the steel containment vessel (3) is not connected to the annular cavity (9); the expansion membrane (7) is attached to the top of the dome (2); When the pressure in the steel containment shell (3) increases, the air release valve (4) opens, and the accident high-pressure gas in the containment shell enters the annular cavity (9) and the space 2 between the steel containment shell (3) and the dome (2) connected thereto through the air release valve (4). The prestressed spring (5) releases the pre-pressure, and together they lift the dome (2) so that it slides upward along the side wall of the containment shell cylinder (1); the water in the cooling water tank (6) enters the space 3 between the expansion membrane (7) and the dome (2), and the expansion membrane (7) is stretched open; the capacity of the containment shell increases, and the pressure decreases, reaching the expansion state; Then, the air release valve (4) is closed and the water release valve (8) is opened. The water in the cooling water tank (6) is released into the annular cavity (9) and the space 2. The cooling water and the hot air meet and condense in the space 2. The steel containment shell (3) serves as a heat transfer surface. The steam condenses on the inner and outer surfaces to release heat, thereby reducing the temperature and pressure and achieving a cooling layer flow state. After the temperature and pressure are lowered, the prestressed spring (5) contracts, the dome (2) descends, and the expansion membrane (7) recovers, entering a recovery state.

2. A flexible containment structure with an expansion membrane according to claim 1, characterized in that: The top end of the containment shell (1) is provided with an outwardly convex sliding section, the outwardly convex sliding section comprising a bottom ring (1-1), a sliding side wall (1-2) and a limiting ring (1-3); the bottom ring (1-1) is connected between the top end of the side wall of the containment shell (1) and the bottom end of the sliding side wall (1-2); and the limiting ring (1-3) is provided on the upper inner wall of the sliding side wall (1-2); The outer side wall of the bottom end of the dome (2) has an upper side ring (2-1) and a lower side ring (2-2); In a normal state, the upper ring (2-1) and the limit ring (1-3) are aligned and spliced ​​to form a complete ring, and the lower ring (2-2) slides up and down along the sliding side wall (1-2). In a normal state, when the dome (2) is at the lower limit position, the annular cavity formed by the lower ring (2-2), the sliding side wall (1-2), and the upper aligned and spliced ​​upper ring (2-1) and the limit ring (1-3) serves as a cooling water tank (6); A prestressed spring (5) is provided between the lower surface of the lower side ring (2-2) of the dome (2) and the upper surface of the bottom ring (1-1) of the containment shell (1).

3. The flexible containment structure with an expansion membrane according to claim 2, characterized in that: The capacity expansion membrane (7) comprises a support layer (7-1), a sealing layer (7-2) and a radiation shielding layer (7-3); the support layer (7-1), the sealing layer (7-2) and the radiation shielding layer (7-3) are stacked in sequence.

4. The flexible containment structure with an expansion membrane according to claim 1, characterized in that: The steel containment shell (3) and the containment shell cylinder (1) are fixedly connected by welding.

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