Containment pressure suppression structure capable of weakening pool swelling, thermal stratification and condensate water hammer

Abstract

The invention discloses a containment pressure suppression structure capable of weakening pool swelling, thermal stratification and condensate water hammer, relates to the technical field of reactor thermal hydraulic power, and solves the problems of condensate water hammer and thermal stratification caused by water seal removal, pool swelling and low-speed discharge in the whole operation stage of a pressure suppression system in the prior art. The suppression spray pipe comprises an inner pipe and an outer pipe. The inner pipe is arranged at the bottom of the pressure suppression box, one end is communicated with the containment, and the other end penetrates through the water space in the pressure suppression box and is arranged above the liquid level of the water space; the upper end of the outer pipe is closed, and the lower end movably sleeves the inner pipe; an air space in the pressure suppression box is communicated with the interior of the containment through a vacuum release valve; the section of the inner pipe is circular. The pressure suppression spray pipe adopts a passive design, the immersion depth of the spray pipe is automatically adjusted by virtue of the spring, the gravity of the outer pipe and the pressure difference between the containment and the pressure suppression box, and the through hole is formed in the lower limiting ring, so that the problems of condensate water hammer and thermal stratification in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of reactor thermal hydraulics, and particularly to a containment suppression structure with reduced pool swelling, thermal stratification, and condensate water hammer. Background Art

[0002] When a large-break loss-of-coolant accident (LOCA) occurs in a pressurized water reactor, a large amount of high-temperature and high-pressure coolant will be discharged and flashed into the containment within dozens of seconds. The steam-non-condensable gas mixture in the containment will flow through the discharge pipeline into the suppression pool under the action of the pressure difference between the containment and the suppression pool. The lower water space of the suppression pool serves as a hot well to absorb the latent heat released by steam condensation, and the upper gas space provides a retention space for non-condensable gases. The suppression system will go through typical stages such as water seal clearance, pool swelling, and low-speed discharge. The water seal clearance time and pool swelling directly depend on the immersion depth of the suppression nozzle in the pool. The smaller the immersion depth of the nozzle, the shorter the water seal clearance time, the better the containment suppression effect, and at the same time, the smaller the load caused by pool swelling. The low-speed discharge of steam may cause condensate water hammer and pool thermal stratification. Reducing the flow area of the suppression nozzle is beneficial to eliminating condensate water hammer, and increasing the immersion depth of the suppression nozzle is beneficial to eliminating thermal stratification. Therefore, how to design the suppression nozzle has become an engineering problem.

[0003] The Chinese patent with the authorization announcement number CN105957565B discloses a suppression pool, which is installed inside the containment vessel and is annularly arranged around the reactor pit of the containment vessel. The suppression pool includes a water space and a gas space. A number of anti-slosh partitions are provided in the water space, and communication holes communicating with both sides are opened at the bottom of the anti-slosh partitions. The Chinese patent with the authorization announcement number CN116246804B discloses a suppression pool and a safety system of an offshore floating nuclear power plant. The suppression pool is arranged outside the containment vessel of the offshore floating nuclear power plant and is connected to the containment vessel through a conduit. The suppression pool includes a housing, which is internally divided into a first space located above and a second space located below, and is respectively used for accommodating non-condensable gas and a condensing medium; the conduit passes through the first space and extends into the second space, and is used to introduce the steam-air mixture formed in the containment vessel under accident conditions into the condensing medium to condense the mixture by using the condensing medium; the inside of the suppression pool is separated by baffles arranged horizontally and vertically, and through holes and drainage tapered pipes connecting the through holes are arranged between the baffles for accelerating the flow and circumferential flow guiding; a pressure relief valve is connected to the housing and communicates with the first space, and is used to open when the pressure in the first space is higher than a preset threshold. The Chinese patent with the authorization announcement number CN106098111B discloses a containment vessel with a suppression pool structure. An suppression pool and a dry well located above the suppression pool and isolated from the suppression pool are provided inside the containment vessel. The suppression pool has a water space and a gas space. A gas-liquid circulation pipe communicating with both of them is vertically arranged between the water space and the dry well. A vacuum breaker is provided between the gas space and the dry well. A first isolation hole is provided in the suppression pool. The first isolation hole is isolated from the suppression pool and communicates with the dry well. The first isolation hole houses the reactor pressure vessel; the water space surrounds the first isolation hole, so that the water in the water space surrounds the reactor pressure vessel on all sides. The Chinese patent with the authorization announcement number CN107293336B discloses a suppression system for the containment vessel of an offshore nuclear power plant, including a suppression pool provided inside the containment vessel. The suppression pool includes a water space and a gas space. The water space is arranged at the bottom of the containment vessel and surrounds the reactor core. The water space is communicated with the dry well of the containment vessel. The gas space is arranged above the water space and surrounds the main equipment. The gas space cavity is directly communicated with the water space.When a LOCA occurs in a nuclear power plant, the gas, steam, and water mixture in the dry well of the containment is introduced into the water space and quickly condensed by the cooling water therein, thereby alleviating the pressure increase effect of the containment; Chinese Patent Publication No. CN108346475A discloses a passive suppression system for a small reactor containment, which includes a containment, a suppression pool, and a suppression pool cooling device; the containment and the suppression pool are connected by a vertical communication pipe, and a horizontal discharge pipe is connected to the vertical communication pipe, and the horizontal discharge pipe is used to guide the gas, steam, and liquid mixture in the containment into the suppression pool for condensation; both ends of the suppression pool cooling device are connected to the suppression pool through pipelines to form a circulation loop, and the suppression pool cooling device is used to cool the suppression pool water passing through the circulation loop to cool the suppression pool to control the temperature range of the suppression pool water temperature. Chinese Patent Authorization Publication No. CN107093470B discloses a containment suppression system with enhanced cooling. The system includes a large-volume closed water tank, a ventilation pipe, a condensation return pipe, and a waste liquid pool. The large-volume closed water tank is arranged inside the containment, with a gas space left at the upper part and water filled in the lower space; the ventilation pipe is arranged inside the containment and passes through the large-volume closed water tank for guiding the gas inside the containment into the large-volume closed water tank; the condensation return pipe is immersed in the water filled in the large-volume closed water tank for connecting the ventilation pipe and the internal space of the large-volume closed water tank and for condensing and returning the gas inside the containment flowing through the ventilation pipe; the waste liquid pool is arranged in front of the gas outlet of the ventilation pipe inside the containment for receiving the condensed liquid led out by the ventilation pipe. The above patents are all about the overall description of the suppression system and the design of the suppression pool, and the partitioned pool has a certain weakening effect on the pool swelling problem. However, engineering problems such as condensate water hammer and thermal stratification faced during system operation are not mentioned, and the specific structure of the suppression nozzle is not designed.

[0004] Chinese Patent Authorization Publication Nos. CN111599492B, CN111599493B, and CN111599494B disclose a suppression pipe and a suppression pool using the suppression pipe. At least one gas one-way conduction component is arranged on the suppression pipe, and the conduction direction is from the outside of the pipe into the inside of the pipe, and it conducts when the air pressure outside the pipe is greater than the air pressure inside the pipe. The suppression pool using this suppression pipe is a closed structure. The suppression pool is filled with liquid for condensation, and an incondensable gas space is above the liquid. The vent pipe passes through the pool and extends below the liquid level and is fixedly connected to the suppression pool. One end of the vent pipe is connected to the gas space inside the containment, and the other end is immersed in the liquid. The gas one-way conduction component connects the gas inside the pipe and the gas space inside the suppression pool. Although this patent can effectively suppress the pressure oscillation in the suppression pool during the low-speed steam discharge stage through the enclosure component and the bubble cutting component, it cannot solve problems such as pool swelling and thermal stratification.

[0005] The Chinese patent with the authorization announcement number CN107578826B discloses a containment suppression and water washing filtration integrated system, including a containment and a suppression pool. The upper part of the suppression pool is an air space, and the lower part is water. The lower part of the containment is connected to the suppression pool through a spray pipe. The spray pipe includes an inlet section, a contraction section, and a throat section connected in sequence. The diameter of the throat section is smaller than that of the inlet section, and the diameter of the contraction section gradually shrinks. A cooling water inlet is provided above the throat section. When a break accident occurs, the mixed steam containing radioactive substances enters the suppression pool through the spray pipe to achieve rapid pressure relief of the containment. The cooling water in the suppression pool enters the throat section through the cooling water inlet, is atomized under the action of high-speed air flow, and collides with the radioactive substances in the mixed steam to remove the radioactive substances. This patent uses a Venturi spray pipe, which can improve the steam condensation efficiency, but cannot solve problems such as pool swelling and thermal stratification.

[0006] In summary, the existing technologies do not comprehensively consider the problems of water seal removal, pool swelling, and condensate water hammer and thermal stratification caused by low-speed discharge faced in the whole operation stage of the suppression system. Summary of the Invention

[0007] In order to solve the problems mentioned above that the existing technologies do not comprehensively consider the problems of water seal removal, pool swelling, and condensate water hammer and thermal stratification caused by low-speed discharge faced in the whole operation stage of the suppression system, the present invention hereby proposes a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer. The suppression spray pipe of the present invention adopts a passive design, and relies on the spring, the gravity of the outer pipe, and the pressure difference between the containment and the suppression tank to automatically adjust the immersion depth of the spray pipe. Moreover, a number of through holes are provided on the lower limit ring, solving the problems of water seal removal, pool swelling, and condensate water hammer and thermal stratification caused by low-speed discharge.

[0008] The present invention proposes a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer, which specifically includes a suppression spray pipe, a suppression tank, and a containment. The suppression spray pipe includes an inner pipe and an outer pipe. The inner pipe is arranged at the bottom of the suppression tank, one end is connected to the containment, and the other end passes through the water space inside the suppression tank and is arranged above the liquid level of the water space. The upper end of the outer pipe is closed, and the lower end is movably sleeved outside the inner pipe. The air space inside the suppression tank is connected to the inside of the containment through a vacuum relief valve. The cross-section of the inner pipe is circular.

[0009] Furthermore, the top of the inner pipe is connected to the outer pipe through a spring.

[0010] Furthermore, an upper limit ring is arranged at the top of the inner pipe, and a lower limit ring is arranged at the lower part. A middle limit ring is arranged inside the outer pipe, and the middle limit ring is arranged between the upper limit ring and the lower limit ring.

[0011] Furthermore, a number of through holes are provided on the lower limit ring.

[0012] Furthermore, the outer diameter of the lower limit ring is greater than the outer diameter of the outer tube.

[0013] Furthermore, a number of circular limiting structures are provided on the outer ring of the upper limit ring.

[0014] Furthermore, a number of circular limiting structures are provided on the inner ring of the middle limit ring.

[0015] Furthermore, the suppression tank is arranged outside the containment vessel, the vacuum relief valve is arranged at the upper end of the outer tube, and the lower end of the inner tube is communicated with the containment vessel through a discharge pipeline; the gas space is communicated with the containment vessel through the vacuum relief valve, the inner tube and the discharge pipeline.

[0016] Furthermore, the suppression tank is arranged outside the containment vessel, a vacuum relief pipeline is arranged at the upper end of the suppression tank, and the suppression tank is communicated with the containment vessel through the vacuum relief pipeline; a vacuum relief valve is arranged on the vacuum relief pipeline; the lower end of the inner tube is communicated with the containment vessel through a discharge pipeline.

[0017] Furthermore, the suppression tank is arranged inside the containment vessel, and the vacuum relief valve is arranged at the upper end of the outer tube.

[0018] The beneficial effects of the containment suppression structure with functions of reducing pool swelling, thermal stratification and condensate water hammer according to the present invention are as follows:

[0019] (1) The containment suppression structure with functions of reducing pool swelling, thermal stratification and condensate water hammer according to the present invention comprehensively considers different stages of the suppression system operation, solves the problems of water seal removal, pool swelling, and condensate water hammer and thermal stratification caused by low-speed discharge. The suppression nozzle adopts a passive design, and automatically adjusts the immersion depth of the suppression nozzle by relying on the spring, the gravity of the outer tube, and the pressure difference between the containment vessel and the suppression tank, which is simple and reliable; the size of steam bubbles is reduced by a number of through holes provided on the lower limit ring, and the steam condensation heat transfer coefficient is increased, which is beneficial to eliminating condensate water hammer and fluid oscillation.

[0020] (2) The containment suppression structure with functions of reducing pool swelling, thermal stratification and condensate water hammer according to the present invention effectively reduces the vibration and noise caused during system operation through the spring arranged between the inner tube and the outer tube, and reduces the probability of running wear and fatigue damage of the equipment. Description of the Drawings

[0021] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0022] In the drawings:

[0023] Figure 1It is a schematic structural diagram of the first specific embodiment of a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer according to the present invention;

[0024] Figure 2 It is a schematic diagram of the working of the suppression nozzle of a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer during the pool swelling stage according to the present invention;

[0025] Figure 3 It is a schematic diagram of the working of the suppression nozzle of a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer during the low-speed steam discharge stage according to the present invention;

[0026] Figure 4 It is a schematic structural diagram of the upper limit ring of a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer according to the present invention;

[0027] Figure 5 It is a schematic structural diagram of the middle limit ring of a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer according to the present invention;

[0028] Figure 6 It is a schematic structural diagram of the lower limit ring of a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer according to the present invention;

[0029] Figure 7 It is a schematic structural diagram of the second specific embodiment of a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer according to the present invention;

[0030] Figure 8 It is a schematic structural diagram of the third specific embodiment of a containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer according to the present invention;

[0031] Wherein: 1 - inner pipe; 2 - outer pipe; 3 - spring; 4 - upper limit ring; 5 - middle limit ring; 6 - water space; 7 - gas space; 8 - suppression tank; 9 - lower limit ring; 10 - containment; 11 - discharge pipeline; 12 - vacuum relief valve; 13 - vacuum relief pipeline. Specific embodiments

[0032] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present invention 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 should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] Specific Embodiment 1: Refer to Figures 1-6 Specifically illustrate this embodiment. A containment suppression structure with reduced pool swelling, thermal stratification, and condensate water hammer described in this embodiment specifically includes a suppression spray pipe, a suppression chamber 8, and a containment 10. The suppression chamber 8 is arranged outside the containment 10. The suppression chamber 8 is composed of a lower water space 6 and an upper gas space 7. The water space 6 serves as a hot well to absorb the latent heat released by steam condensation, and the gas space 7 accommodates air. A suppression spray pipe is arranged inside the suppression chamber 8; the suppression spray pipe includes an inner pipe 1 and an outer pipe 2, and the outer diameter of the inner pipe 1 is smaller than the outer diameter of the outer pipe 2; the inner pipe 1 is vertically fixed at the bottom of the suppression chamber 8, and the lower end is communicated with the containment 10 through a discharge pipeline 11, and the upper end passes through the water space 6 inside the suppression chamber 8 and is arranged above the liquid level of the water space 6; the upper end of the outer pipe 2 is closed, and the lower end is open and movably sleeved outside the inner pipe 1; a vacuum relief valve 12 is arranged at the upper end of the outer pipe 2; the gas space 7 is communicated with the containment 10 through the vacuum relief valve 12, the inner pipe 1, and the discharge pipeline 11; the cross-section of the inner pipe 1 is circular and is a circular straight pipe.

[0037] The top of the inner pipe 1 is connected to the outer pipe 2 through a spring 3, and the spring 3 is used to balance the gravitational force of the outer pipe 2 and limit the up and down displacement of the outer pipe 2.

[0038] The top of the inner tube 1 is provided with an upper limit ring 4, and the bottom is provided with a lower limit ring 9; a middle limit ring 5 is arranged inside the outer tube 2, and the middle limit ring 5 is arranged between the upper limit ring 4 and the lower limit ring 9. The annular channel between the inner tube 1 and the outer tube 2 is positioned by the upper limit ring 4, the middle limit ring 5 and the lower limit ring 9 to eliminate the lateral movement of the outer tube 2.

[0039] The inner wall of the lower limit ring 9 is fixed to the inner tube 1, and a plurality of through holes are arranged on the lower limit ring 9, and the plurality of through holes can reduce the size of steam bubbles. The outer diameter of the lower limit ring 9 is larger than the outer diameter of the outer tube 2.

[0040] The upper limit ring 4 includes a circular ring structure body, the circular ring structure body is sleeved outside the inner tube 1, and a plurality of circular limit structures are arranged on the outer ring of the circular ring structure body, such as Figure 4 shown; there is a certain installation gap between the circular fixed points of the circular limit structures of the upper limit ring 4 and the outer tube 2, so that the outer tube 2 can move up and down without obvious lateral movement.

[0041] The middle limit ring 5 includes a circular ring structure body, the circular ring structure body is arranged on the inner wall of the outer tube 2, and a plurality of circular limit structures are arranged on the inner ring of the circular ring structure body, such as Figure 5 shown; there is a certain installation gap between the circular fixed points of the circular limit structures of the middle limit ring 5 and the inner tube 1, so that the outer tube 2 can move up and down without obvious lateral movement.

[0042] As Figure 2 shown, in the initial stage of the accident, the large pressure difference between the containment 10 and the suppression pool 8 causes the outer tube 2 to move upward, reducing the immersion depth of the outer tube 2, effectively reducing the water seal removal time and the swelling degree of the pool;

[0043] As Figure 3 shown, in the stage of low steam flow rate discharge, the small pressure difference between the containment 10 and the suppression pool 8 causes the outer tube 2 to move downward. At this time, the outer tube 2 has sufficient immersion depth to eliminate thermal stratification, and the porous structure arranged on the lower limit ring 9 can effectively eliminate the condensate water hammer phenomenon.

[0044] After the accident ends, the pressure in the containment may be lower than the atmospheric pressure, and there is a risk of negative pressure breakage. The one-way vacuum relief valve 12 arranged at the top of the outer tube 2 at a position higher than the water space 6 liquid level opens, and the air in the gas space 7 of the suppression pool 8 returns to the inside of the containment 10 through the inner tube 1 and the discharge pipe 11.

[0045] Specific Embodiment 2: Refer to Figures 4-7Specifically describe this embodiment. A containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer described in this embodiment has a suppression tank 8 disposed outside the containment 10. A vacuum release pipe 13 is provided at the upper end of the suppression tank 8. The gas space 7 in the suppression tank 8 is communicated with the containment 10 through the vacuum release pipe 13; a vacuum release valve 12 is provided on the vacuum release pipe 13; the lower end of the inner pipe 1 is communicated with the containment 10 through a discharge pipe 11. The other components and connection relationships of this embodiment are the same as those of the first specific embodiment.

[0046] In the initial stage of the accident, the large pressure difference between the containment 10 and the suppression tank 8 causes the outer pipe 2 to move upward, reducing the immersion depth of the outer pipe 2, effectively reducing the water seal clearance time and the degree of pool swelling;

[0047] In the stage of low steam flow rate discharge, the small pressure difference between the containment 10 and the suppression tank 8 causes the outer pipe 2 to move downward. At this time, the outer pipe 2 has sufficient immersion depth to eliminate thermal stratification, and the lower limit ring 9 is provided with a porous structure that can effectively eliminate the condensate water hammer phenomenon.

[0048] After the accident ends, the pressure in the containment may be lower than the atmospheric pressure, posing a risk of negative pressure breakage. The one-way vacuum release valve 12 provided on the vacuum release pipe 13 at a position higher than the liquid level of the water space 6 is opened, and the air in the gas space 7 of the suppression tank 8 returns to the inside of the containment 10 through the vacuum release pipe 13.

[0049] Specific embodiment three: Refer to Figures 4-6 and Figure 8 Specifically describe this embodiment. A containment suppression structure with weakened pool swelling, thermal stratification, and condensate water hammer described in this embodiment has a suppression tank 8 disposed inside the containment 10, and a vacuum release valve 12 is provided at the upper end of the outer pipe 2; the suppression discharge pipe 11 and the vacuum release pipe 13 are omitted, increasing the compactness of the containment suppression system and reducing the weight and volume of the suppression system. The other components and connection relationships of this embodiment are the same as those of the first specific embodiment.

[0050] In the initial stage of the accident, the large pressure difference between the containment 10 and the suppression tank 8 causes the outer pipe 2 to move upward, reducing the immersion depth of the outer pipe 2, effectively reducing the water seal clearance time and the degree of pool swelling;

[0051] In the stage of low steam flow rate discharge, the small pressure difference between the containment 10 and the suppression tank 8 causes the outer pipe 2 to move downward. At this time, the outer pipe 2 has sufficient immersion depth to eliminate thermal stratification, and the lower limit ring 9 is provided with a porous structure that can effectively eliminate the condensate water hammer phenomenon.

[0052] After the accident, the pressure in the containment may be lower than the atmospheric pressure, presenting a risk of negative pressure breakage. The one-way vacuum relief valve 12 installed at the top of the outer pipe 2 at a position higher than the water level 6 in the water space opens, and the air in the gas space 7 of the suppression pool 8 returns to the inside of the containment 10 through the inner pipe 1.

[0053] Summarizing the above embodiments, a containment suppression structure with reduced pool swelling, thermal stratification, and condensate water hammer according to the present invention comprehensively considers different stages of the suppression system operation, solves the problems of water seal removal, pool swelling, and condensate water hammer and thermal stratification caused by low-speed discharge. The suppression spray pipe adopts a passive design and automatically adjusts the immersion depth of the suppression spray pipe by relying on the spring 3, the gravity of the outer pipe, and the pressure difference between the containment 10 and the suppression pool 8, which is simple and reliable; the size of steam bubbles is reduced by several through holes provided on the lower limit ring 9, improving the steam condensation heat transfer coefficient, which is beneficial to eliminating condensate water hammer and fluid oscillation. A containment suppression structure with reduced pool swelling, thermal stratification, and condensate water hammer according to the present invention effectively reduces the vibration and noise generated during system operation and the probability of running wear and fatigue damage of equipment through the spring 3 provided between the inner pipe 1 and the outer pipe 2.

[0054] In the above specific embodiments, the purpose, technical solutions, and beneficial effects of the present invention are further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the invention. It can also be a reasonable combination of the features described in the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A containment pressure suppression structure capable of reducing pool swelling, thermal stratification and condensation water hammer, characterized in that: The invention comprises a pressure suppression nozzle, a pressure suppression box (8) and a containment shell (10), wherein the pressure suppression nozzle comprises an inner tube (1) and an outer tube (2); the inner tube (1) is arranged at the bottom of the pressure suppression box (8), one end of the inner tube (1) is connected to the containment shell (10), and the other end of the inner tube (1) passes through a water space (6) inside the pressure suppression box (8) and is arranged above the liquid level of the water space (6); the upper end of the outer tube (2) is closed, and the lower end is movably sleeved outside the inner tube (1); the gas space (7) inside the pressure suppression box (8) is connected to the inside of the containment shell (10) through a vacuum release valve (12); and the cross section of the inner tube (1) is circular.

2. The containment pressure suppression structure with reduced pool swelling, thermal stratification and condensation water hammer according to claim 1, characterized in that: The top of the inner tube (1) is connected to the outer tube (2) via a spring (3).

3. The containment pressure suppression structure with reduced pool swelling, thermal stratification and condensation water hammer according to claim 1, characterized in that: The inner tube (1) is provided with an upper limiting ring (4) at the top and a lower limiting ring (9) at the bottom; a middle limiting ring (5) is provided inside the outer tube (2), and the middle limiting ring (5) is provided between the upper limiting ring (4) and the lower limiting ring (9).

4. The containment pressure suppression structure with reduced pool swelling, thermal stratification and condensation water hammer according to claim 3, characterized in that: The lower limiting ring (9) is provided with a plurality of through holes.

5. The containment pressure suppression structure with reduced pool swelling, thermal stratification and condensation water hammer according to claim 4, characterized in that: The outer diameter of the lower limiting ring (9) is greater than the outer diameter of the outer tube (2).

6. The containment pressure suppression structure with reduced pool swelling, thermal stratification and condensation water hammer according to claim 4, characterized in that: The outer ring of the upper limiting ring (4) is provided with a plurality of circular limiting structures.

7. The containment pressure suppression structure with reduced pool swelling, thermal stratification and condensation water hammer according to claim 4, characterized in that: The inner ring of the middle limiting ring (5) is provided with a plurality of circular limiting structures.

8. The containment pressure suppression structure with reduced pool swelling, thermal stratification and condensation water hammer according to any one of claims 1 to 7, characterized in that: The pressure suppression box (8) is arranged outside the containment shell (10), the vacuum release valve (12) is arranged at the upper end of the outer tube (2), the lower end of the inner tube (1) is connected to the containment shell (10) through a discharge pipe (11); the gas space (7) is connected to the containment shell (10) through the vacuum release valve (12), the inner tube (1), the discharge pipe (11) and the containment shell (10).

9. The containment pressure suppression structure with reduced pool swelling, thermal stratification and condensation water hammer according to any one of claims 1 to 7, characterized in that: The pressure suppression box (8) is arranged outside the containment shell (10); a vacuum release pipe (13) is arranged at the upper end of the pressure suppression box (8), and the pressure suppression box (8) is connected to the containment shell (10) through the vacuum release pipe (13); a vacuum release valve (12) is arranged on the vacuum release pipe (13); and the lower end of the inner tube (1) is connected to the containment shell (10) through a discharge pipe (11).

10. The containment pressure suppression structure with reduced pool swelling, thermal stratification and condensation water hammer according to any one of claims 1 to 7, characterized in that: The pressure suppression box (8) is arranged inside the containment shell (10), and the vacuum release valve (12) is arranged at the upper end of the outer tube (2).

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