Nuclear power plant containment cooling system and nuclear power plant containment

Abstract

A nuclear power plant containment cooling system disclosed by the present invention comprises a storage box and a phase change material, the phase change material is a material with a melting point higher than the normal working condition temperature of a containment and lower than the accident working condition temperature of the containment, the phase change material is accommodated in the storage box, and a heat exchange structure is arranged on at least one side surface of the storage box. The heat exchange structure is exposed in the environment in the containment so as to transfer heat to the phase change material in the storage box under the working condition of a containment accident, so that the phase change material absorbs heat in a phase change manner. The nuclear power plant containment cooling system provided by the invention is quick and efficient in response, and can improve the accident mitigation ability and ensure the safety. The invention also provides the nuclear power plant containment.

Description

Technical Field

[0001] The present invention particularly relates to a nuclear power plant containment cooling system and a nuclear power plant containment. Background Art

[0002] When a nuclear power plant accident occurs, high-energy water and steam from the primary circuit rapidly enter the containment vessel, causing the temperature and pressure inside to rise rapidly. Since the containment vessel is the third or final barrier in a nuclear power plant, a rupture due to overheating and overpressure could release radioactive materials into the environment, posing a threat to the environment and human health.

[0003] Therefore, various nuclear power plants currently employ various heat removal devices to address containment temperature and pressure increases, including traditional active spray systems and passive heat removal systems. However, due to the delay in activation of active systems and the delay in heat transfer of passive systems, the rapid peak temperature and pressure increases in the containment caused by early mass-energy release are difficult to mitigate. Furthermore, both of these systems require cooling water from water tanks, placing high demands on the system equipment. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art and provide a nuclear power plant containment cooling system that is responsive and efficient, can improve accident mitigation capabilities, and ensure safety. The present invention also provides a nuclear power plant containment.

[0005] The present invention provides a nuclear power plant containment cooling system, comprising a storage box and a phase change material. The phase change material is a material having a melting point higher than the containment's normal operating temperature and lower than the containment's accident operating temperature, and is accommodated in the storage box. A heat exchange structure is provided on at least one side surface of the storage box. The heat exchange structure is exposed to the environment within the containment so as to transfer heat to the phase change material in the storage box under the containment's accident operating condition, thereby causing the phase change material to undergo phase change and absorb heat.

[0006] Furthermore, the heat exchange structure is a heat exchange rib plate group, including multiple rib plates, one group of heat exchange rib plate groups is installed on one side surface of the storage box, and the rib plates are arranged parallel to each other and are vertically connected to the surface.

[0007] Furthermore, the storage box is provided with a plurality of heat-conducting fins, all of which are connected to the inner side of the surface of the storage box where the heat exchange structure is provided, and the heat-conducting fins are arranged parallel to each other in the storage box and in direct contact with the phase change material.

[0008] Furthermore, each of the heat-conducting fins has a set volume and a set surface area, so that the heat transfer efficiency to the phase change material is not less than 0.8.

[0009] Furthermore, the thickness of the heat-conducting fin is 2 mm to 4 mm, the height is 120 mm to 180 mm, and the length is 120 mm to 180 mm.

[0010] Furthermore, the distance between two adjacent heat-conducting fins is 10 mm to 40 mm.

[0011] Furthermore, the storage box includes a shell and an insulation structure. The shell is used to accommodate phase change material. The surface of the shell provided with the heat exchange structure is the heat transfer base surface. The outer side of the remaining surfaces of the shell except the heat transfer base surface is covered with the insulation structure.

[0012] Furthermore, the thermal insulation structure is a plate-shaped structure made of insulating material.

[0013] The present invention also provides a nuclear power plant containment, comprising a containment body and the above-mentioned nuclear power plant containment cooling system, wherein a storage box of the nuclear power plant containment cooling system is arranged at a predetermined accident temperature rise position in the containment body, and a heat exchange structure of the storage box is exposed to the internal environment of the containment body, so as to transfer heat to the phase change material in the storage box under the containment accident condition, thereby causing the phase change material to undergo phase change and absorb heat to cool the internal environment of the containment body.

[0014] The nuclear power plant containment cooling system of the present invention accommodates a phase change material having a melting point higher than the normal operating temperature of the containment and lower than the accident operating temperature of the containment in a storage box, and then utilizes a heat exchange structure in direct contact with the environment inside the containment to perform heat exchange and heat transfer, thereby utilizing the heat absorption characteristics of the phase change material during the phase change process to store heat in the containment after an accident and indirectly eliminate the high pressure caused by high temperature, thereby achieving the purpose of cooling and reducing the pressure of the nuclear power plant containment and increasing the overall safety of the nuclear power plant.

[0015] Phase change materials remain in a solid state under normal operating conditions, avoiding meaningless heat absorption; but under accident conditions, they quickly melt and absorb heat, directly reducing the ambient temperature inside the containment vessel and improving the system's response speed and reliability. The entire process can automatically trigger the phase change heat absorption mechanism when an accident occurs, without any lag, and without relying on external energy or active control. It avoids the risk of active system failure and the risk of power outages in the entire nuclear power plant, forming a passive (non-passive) safety cooling function that responds quickly and efficiently, improving the nuclear power plant's ability to mitigate accidents and the overall safety of the nuclear power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the nuclear power plant containment cooling system in Example 1 of the present invention.

[0017] In the figure: 1. storage box; 11. heat-conducting fin; 12. shell; 121. heat transfer base surface; 13. insulation structure; 2. phase change material; 3. heat exchange rib group; 31. rib. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of the present invention.

[0019] In the description of the present invention, it should be noted that the terms "upper" and "lower" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience and simplification of the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present invention.

[0020] In the description of the present invention, the terms “first”, “second” and “third” are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0021] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connect," "dispose," "install," "fix," etc. should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integral connection; they may refer to direct connection, indirect connection through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0022] Example 1

[0023] like Figure 1 As shown, the nuclear power plant containment cooling system of this embodiment includes a storage box 1 and a phase change material 2. The phase change material 2 is a material with a melting point higher than the normal operating temperature of the containment and lower than the accident operating temperature of the containment. The phase change material 2 is accommodated in the storage box 1. A heat exchange structure is provided on at least one side surface of the storage box 1. The heat exchange structure is exposed to the environment inside the containment to transfer heat to the phase change material 2 in the storage box 1 under the accident operating condition of the containment, so that the phase change material 2 undergoes phase change and absorbs heat.

[0024] The nuclear power plant containment cooling system of this embodiment contains a phase change material 2 having a melting point higher than the containment's normal operating temperature and lower than the containment's accident operating temperature in a storage tank 1, and then utilizes a heat exchange structure in direct contact with the containment's internal environment for heat exchange and heat transfer. The heat absorption characteristics of the phase change material 2 during the phase change process are utilized to store heat within the containment after an accident, and indirectly eliminate the high pressure caused by high temperature, thereby achieving the purpose of cooling and reducing the pressure of the nuclear power plant containment and increasing the overall safety of the nuclear power plant.

[0025] Phase change material 2 remains solid under normal operating conditions, preventing pointless heat absorption. However, under accident conditions, it rapidly melts and absorbs heat, directly lowering the ambient temperature within the containment vessel and improving system response speed and reliability. This entire process automatically triggers the phase change heat absorption mechanism upon an accident, without hysteresis and without reliance on external energy or active control. This mitigates the risk of active system failure and plant-wide power outages, creating a passive (non-passive) safety cooling function with rapid and efficient response, enhancing the plant's accident mitigation capabilities and overall safety. Phase change material 2 can be composed of any suitable organic or inorganic material, whether traditional or novel. Its melting point is greater than the normal operating temperature within the containment vessel, and materials with good latent heat of phase change and specific heat capacity, such as paraffin, can be selected.

[0026] In this embodiment, the storage tank 1 can be placed in any compartment within the containment vessel; multiple storage tanks 1 can also be combined and placed in a larger space. For example, they can be placed in the mass-energy release (or adjacent) compartment to achieve rapid cooling of a local compartment, placed in a large upper space (such as an operating platform), or fixed to the side of the containment vessel's inner wall to achieve long-term temperature and pressure control of the entire containment vessel.

[0027] In this embodiment, the heat exchange structure is a heat exchange rib assembly 3, comprising multiple ribs 31. One rib assembly 3 is mounted on a side surface of the storage tank 1, with each rib 31 arranged parallel to one another and perpendicular to the surface. The rib assembly 3, through its multiple parallel, vertically arranged ribs 31, significantly increases the effective heat exchange area on the surface of the storage tank 1, enhancing the rate of heat transfer from the containment environment to the storage tank 1 during an accident. The gaps between the ribs 31 allow the natural flow of the medium (such as air or steam) within the containment, preventing localized heat accumulation. The simple structure and ease of manufacture and installation enhance the system's maintainability and seismic performance, making it suitable for the rigorous physical environment of nuclear power plants.

[0028] In this embodiment, the storage box 1 is also provided with a plurality of heat-conducting fins 11, each connected to the inner side of the surface of the storage box 1 provided with the heat exchange structure. The heat-conducting fins 11 are arranged parallel to each other within the storage box 1 and in direct contact with the phase change material 2. The heat-conducting fins 11 extend into the interior of the phase change material 2, quickly transferring heat absorbed by the outer wall of the storage box 1 to the depth of the phase change material 2, thus overcoming the problems of low material utilization and large internal temperature gradients caused by relying solely on surface heat transfer. The parallel arrangement of the heat-conducting fins 11 forms a regular heat flow channel, promoting uniform melting of the phase change material 2 and avoiding premature local exhaustion, thereby extending the overall heat absorption duration and improving the stability of the cooling system.

[0029] In this embodiment, each thermally conductive fin 11 has a set volume and surface area to ensure a heat transfer efficiency of no less than 0.8 for the phase change material 2. By limiting the specifications of each thermally conductive fin 11 to ensure a heat transfer efficiency of no less than 0.8 for the phase change material 2, the balance between the thermal conductivity of the thermally conductive fin 11 and material cost is optimized. High heat transfer efficiency means more heat is absorbed by the phase change material 2 per unit time, shortening the duration of peak temperature rise under accident conditions and reducing the risk of containment overpressure. It also avoids excessive storage tank 1 volume due to redundant thermally conductive fin 11 designs.

[0030] In this embodiment, the thickness of the heat-conducting fins 11 ranges from 2mm to 4mm, ensuring sufficient mechanical strength to resist the expansion stress of the phase-change material 2 while avoiding increased thermal resistance due to excessive thickness. The height and length range from 120mm to 180mm, ensuring the maximum extension depth of the heat-conducting fins 11 within the limited space, forming an efficient three-dimensional heat transfer network while avoiding the risk of structural deformation caused by excessive length. In this embodiment, the heat-conducting fins 11 are composed of one or more metal materials with strong heat transfer capabilities. The heat-conducting fins 11 are installed within the storage box 1, ensuring full contact with the phase-change material 2.

[0031] In this embodiment, the spacing between two adjacent heat-conducting fins 11 is 10 mm to 40 mm. This spacing range prevents a too small spacing from hindering the natural convection of the molten phase change material 2 (affecting the efficiency of latent heat release), while also avoiding an excessively large spacing that results in insufficient heat transfer area. This optimizes the synergistic effect of heat transfer and mass transfer during the solid-liquid phase change process, further increasing the heat absorption rate.

[0032] In this embodiment, the storage box 1 includes a shell 12 and an insulating structure 13. The shell 12 is used to accommodate the phase change material 2. The surface of the shell 12 provided with the heat exchange structure is the heat transfer base surface 121. The outer sides of the remaining surfaces of the shell 12 except the heat transfer base surface 121 are covered with the insulating structure 13. In this embodiment, by covering the non-heat transfer surface of the storage box 1 with the insulating structure 13, heat transfer in non-target areas (such as the outside of the containment) is effectively blocked, and cooling capacity is concentrated to cope with accident conditions. The heat exchange structure transfers heat to the phase change material 2 in the storage box 1 through condensation heat exchange. At the same time, condensation heat exchange can reduce the temperature and pressure of the atmosphere in the containment in contact. Covering the remaining surfaces of the storage box 1 except the heat transfer base surface 121 with the insulating structure 13 can prevent heat from being dissipated to the outside (i.e., inside the containment) through the storage box 1.

[0033] In this embodiment, the insulation structure 13 is a plate-like structure made of insulating material. This plate-like structure fits snugly against the surface of the shell 12, reducing thermal bridges at the joints. Its rigidity also protects against airflow within the containment vessel, preventing the insulation structure 13 from breaking and failing, and ensuring consistent insulation performance throughout the system's lifecycle. The insulation structure 13 can be made of insulating ceramics, for example.

[0034] In general, this embodiment can be used in the field of nuclear power technology. It can be said to be a nuclear power plant containment cooling system based on the phase change energy storage principle and proposed by the passive principle in response to the safety design requirements of nuclear power plants. The system can respond quickly to the phenomenon of temperature and pressure increase in the containment. At the same time, the passive design can reduce the risk of failure of the active system, reduce the risk of power outages in the entire nuclear power plant, and extend the access time of the backup emergency power supply system, thereby improving the nuclear power plant's ability to mitigate accidents and the overall safety of the nuclear power plant.

[0035] The system generally comprises a storage tank 1 (shell 12 with a heat transfer base 121 and an insulation structure 13, also referred to as a phase change energy storage material storage tank), a heat exchange rib assembly 3, heat conductive fins 11, and phase change material 2. The storage tank 1 and the external heat exchange rib assembly 3 are connected to the heat transfer base 121 for heat transfer. The external heat exchange rib assembly 3 is composed of a metal material and is in direct contact with the containment environment. Through condensation, heat is transferred to the storage tank 1 to reduce the temperature and pressure inside the containment. The shell 12 of the storage tank 1 can be made of a different metal material than the heat conductive fins 11.

[0036] Specifically, after an accident at a nuclear power plant, the temperature and pressure inside the containment vessel rise. Water vapor in contact with the heat exchange fin assembly 3 undergoes condensation and heat transfer, transferring heat to the storage tank 1. Simultaneously, the temperature and pressure inside the containment vessel decrease. The heat transferred to the storage tank 1 is transferred to the phase change material 2 via the heat-conducting fins 11. As the temperature rises, the phase change material 2 gradually melts, absorbing the latent heat of phase change. Even after complete melting, the temperature of the phase change material 2 can continue to rise, storing and removing heat through sensible heat.

[0037] The system of this embodiment has the following beneficial effects: (1) reducing the peak pressure and temperature of the containment after a nuclear power plant accident, reducing the overall accident risk of the nuclear power plant, and improving the overall safety of the nuclear power plant; (2) the passive design reduces the problem of unavailability of the active removal system in the event of a power outage in the entire nuclear power plant, improves the success rate of the safety system, and reduces the probability of human failure; (3) improving the ability of the nuclear power plant to mitigate accidents, which is beneficial to reducing the frequency of core damage and large-scale radioactive release in the nuclear power plant.

[0038] Example 2

[0039] The nuclear power plant containment of this embodiment includes the containment body and the nuclear power plant containment cooling system of Example 1. A storage tank 1 of the containment cooling system is positioned within the containment body at a predetermined location where the temperature would rise during an accident. The heat exchange structure of the storage tank 1 is exposed to the internal environment of the containment body. Under containment accident conditions, heat is transferred to the phase change material 2 within the storage tank 1, causing the phase change material 2 to undergo a phase change and absorb heat, thereby cooling the internal environment of the containment body. This embodiment mitigates the overall temperature rise pressure of the nuclear power plant containment through phase change and heat absorption, enhancing the containment's integrity assurance capabilities during severe accidents, thus complying with the principle of defense in depth.

[0040] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A nuclear power plant containment cooling system, characterized by: It comprises a storage box (1) and a phase change material (2), The phase change material (2) is a material having a melting point higher than the normal operating temperature of the containment shell and lower than the accident operating temperature of the containment shell, and is contained in the storage box (1). A heat exchange structure is provided on at least one side surface of the storage box (1), and the heat exchange structure is exposed to the environment inside the containment shell so as to transfer heat to the phase change material (2) inside the storage box (1) under the condition of a containment shell accident, thereby causing the phase change material (2) to undergo phase change and absorb heat.

2. The nuclear power plant containment cooling system according to claim 1, characterized in that: The heat exchange structure is a heat exchange rib plate group (3), comprising a plurality of rib plates (31), A group of heat exchange rib plates (3) is installed on a side surface of the storage box (1), and the rib plates (31) are arranged parallel to each other and are vertically connected to the surface.

3. The nuclear power plant containment cooling system according to claim 1, characterized in that: The storage box (1) is further provided with a heat-conducting fin plate (11), and a plurality of the heat-conducting fin plates (11) are provided, all of which are connected to the inner side of the surface of the storage box (1) provided with a heat exchange structure. The heat-conducting fins (11) are arranged in parallel with each other in the storage box (1) and are in direct contact with the phase change material (2).

4. The nuclear power plant containment cooling system according to claim 3, characterized in that: Each of the heat-conducting fins (11) has a set volume and a set surface area so that the heat transfer efficiency to the phase change material (2) is not less than 0.

8.

5. The nuclear power plant containment cooling system according to claim 4, characterized in that: The heat-conducting fin plate (11) has a thickness of 2 mm to 4 mm, a height of 120 mm to 180 mm, and a length of 120 mm to 180 mm.

6. The nuclear power plant containment cooling system according to claim 3, characterized in that: The distance between two adjacent heat-conducting fin plates (11) is 10 mm to 40 mm.

7. The nuclear power plant containment cooling system according to claim 1, characterized in that: The storage box (1) comprises a shell (12) and a heat insulating structure (13). The shell (12) is used to accommodate the phase change material (2); the surface of the shell (12) provided with the heat exchange structure is a heat transfer base surface (121); and the outer sides of the remaining surfaces of the shell (12) except the heat transfer base surface (121) are covered with the heat insulation structure (13).

8. The nuclear power plant containment cooling system according to claim 7, characterized in that: The thermal insulation structure (13) is a plate-shaped structure made of insulating material.

9. A nuclear power plant containment vessel, characterized by: A nuclear power plant containment cooling system comprising a containment body and any one of claims 1 to 8, The storage box (1) of the nuclear power plant containment cooling system is arranged at a predetermined accident temperature rise position in the containment body, and the heat exchange structure of the storage box (1) is exposed to the internal environment of the containment body, so as to transfer heat to the phase change material (2) in the storage box (1) under the containment accident working condition, thereby causing the phase change material (2) to undergo phase change and absorb heat to cool the internal environment of the containment body.

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