Nuclear reactor and its passive damper system

Abstract

The application provides a nuclear reactor and a passive damper system thereof, and relates to the technical field of nuclear reactors.The application is characterized in that an expansion container and a damper counterweight are arranged, the expansion container is in communication with a coolant pipeline of the nuclear reactor and can accommodate the coolant of the nuclear reactor, the damper counterweight is connected with the damper and can float on the liquid level of the coolant in the expansion container, the damper counterweight is used for controlling the opening degree of the damper to increase as the liquid level of the coolant in the expansion container rises after the nuclear reactor enters a passive residual heat removal mode, and the opening degree of the damper is controlled to decrease as the liquid level of the coolant in the expansion container decreases, so that the opening degree of the damper is automatically adjusted according to the temperature change of the coolant.When the temperature of the coolant decreases, the liquid level of the coolant in the expansion container decreases, the opening degree of the damper is automatically reduced to reduce the air cooling channel, the decrease of the temperature of the coolant is inhibited, the risk of solidification of the coolant is reduced, and the safety and reliability of the nuclear reactor are improved.

Description

Technical Field

[0001] This application relates to the field of nuclear reactor technology, and in particular to a nuclear reactor and its passive damper system. Background Technology

[0002] With the development of fourth-generation nuclear energy systems, advanced reactor types such as lead-bismuth cooled fast reactors, sodium-cooled fast reactors, and molten salt reactors have gradually become research hotspots due to their higher safety, better fuel resource utilization, and more flexible coolant selection. Unlike traditional water-cooled or gas-cooled reactors, fourth-generation reactors mostly adopt low-pressure operation, large temperature difference, strong natural circulation, or passive safety design concepts. Coolants such as lead-bismuth alloys, liquid sodium, and molten salts are widely used due to their excellent thermal properties such as high heat capacity, good thermal conductivity, and low vapor pressure. However, these coolants generally have melting points above room temperature; for example, the melting point of liquid sodium is approximately 98 °C, that of lead-bismuth alloys is approximately 125 °C, and that of FLiBe molten salt is approximately 459 °C. During normal reactor operation, the coolant remains in a high-temperature liquid state, but after reactor shutdown, as the decay heat gradually decreases and the coolant flow rate slows down or even stops, there is a risk that the coolant temperature will drop to the freezing point. Once solidification occurs, the coolant loses its fluidity, interrupting the heat transfer path, leading to the accumulation of decay heat, increased core temperature, intensified structural stress, and even core damage. Especially in passive residual heat removal systems, whose operation depends on natural forces, the system response is weak and disturbances are large, making coolant solidification one of the most challenging safety issues at this stage.

[0003] Existing nuclear reactors typically employ active control methods. When the coolant temperature at a specific location falls below a set limit, dampers are automatically closed to reduce air cooling power and prevent coolant condensation. However, this type of active control relies on external signals and power, and inherently suffers from drawbacks such as response lag, system complexity, and high failure rates. Summary of the Invention

[0004] The purpose of this application is to provide a nuclear reactor and its passive damper system to improve the safety and reliability of the nuclear reactor.

[0005] In a first aspect, this application provides a passive damper system for a nuclear reactor, the nuclear reactor including a primary loop system and a passive residual heat removal system, the passive residual heat removal system including an air-cooled tower and dampers disposed within the air-cooled tower, the passive damper system comprising:

[0006] An expansion container is connected to the coolant piping of the nuclear reactor. The expansion container is capable of containing the coolant of the nuclear reactor, and the coolant has the property of thermal expansion and contraction.

[0007] A damper counterweight is connected to the damper and can float on the surface of the coolant in the expansion vessel. The damper counterweight is used to control the opening of the damper to increase as the coolant level in the expansion vessel rises after the nuclear reactor enters the passive residual heat removal mode, and to control the opening of the damper to decrease as the coolant level in the expansion vessel falls.

[0008] In one possible implementation, the passive damper system further includes:

[0009] A damper opening and closing device is connected to the damper. The damper opening and closing device is used to control the damper to remain closed under normal operating conditions of the nuclear reactor, and to control the damper to open to the fully open position in response to the nuclear reactor entering the passive residual heat removal mode.

[0010] A connecting device is provided, one end of which is connected to the damper and the other end of which is connected to the damper counterweight. The connecting device is used to, after the nuclear reactor enters the passive residual heat removal mode, in response to the coolant level in the expansion vessel being lower than a first threshold, cause the damper counterweight to pull the damper to reduce its opening degree through the connecting device, and in response to the coolant level in the expansion vessel being higher than a second threshold, cause the damper to increase its opening degree under the action of gravity.

[0011] In one possible implementation, the connecting device includes:

[0012] A damper connector, connected to the damper;

[0013] A redundant connector is provided, with one end connected to the damper connector and the other end connected to the damper counterweight. Under normal operating conditions, the redundant connector is in a relaxed state. After the nuclear reactor enters the passive residual heat removal mode, the redundant connector can be straightened when the damper is in the fully open position.

[0014] In one possible implementation, the length of the redundant connector is set such that the redundant connector can be taut when the damper opening and closing device controls the damper to open to the fully open position.

[0015] In one possible implementation, the redundant connector is disposed within the expansion container.

[0016] In one possible implementation, the space above the coolant level within the expansion container is formed as a covering gas space, which is connected to a covering gas source via a covering gas circuit. The passive damper system further includes:

[0017] A seal is disposed at the top of the expansion container, through which the damper connector passes into the expansion container or through which the redundant connector passes out of the expansion container.

[0018] In one possible implementation, the weight of the damper counterweight is set to be greater than the force required to pull the damper.

[0019] In one possible implementation, the overall average density of the damper counterweight is less than the density of the coolant.

[0020] In one possible implementation, the damper opening and closing device includes:

[0021] A damper fixing device is used to guide the damper;

[0022] An electromagnetic interlocking device for a damper is used to hold the damper closed under normal operating conditions, and to release the damper by de-energizing it in response to the nuclear reactor entering the passive residual heat removal mode, allowing the damper to open freely under gravity.

[0023] In one possible implementation, the bottom of the expansion vessel is connected to the coolant piping of the nuclear reactor via a connecting pipe; and / or the expansion vessel is connected to the coolant piping of the primary loop system.

[0024] Secondly, this application provides a nuclear reactor, including a primary loop system and a passive residual heat removal system, wherein the passive residual heat removal system includes an air-cooled tower and a damper disposed within the air-cooled tower, and the nuclear reactor includes the passive damper system described in the first aspect.

[0025] This application incorporates an expansion vessel and a damper counterweight. The expansion vessel is connected to the coolant pipeline of the nuclear reactor and can hold the reactor's coolant. The damper counterweight is connected to the damper and floats on the coolant surface within the expansion vessel. When the nuclear reactor enters passive residual heat removal mode, the damper counterweight controls the damper opening by increasing as the coolant level in the expansion vessel rises and decreasing as the coolant level decreases. This allows for autonomous adjustment of the damper opening based on coolant temperature changes. When the coolant temperature decreases, the coolant level in the expansion vessel drops, automatically reducing the damper opening to decrease the air cooling channel, suppressing the coolant temperature drop, thereby reducing the risk of coolant solidification and improving the safety and reliability of the nuclear reactor. Attached Figure Description

[0026] The accompanying drawings are included to provide a further understanding of this application; they are incorporated into and constitute a part of this application. The drawings illustrate embodiments of this application and, together with this specification, serve to explain the principles of this application. In the drawings:

[0027] Figure 1 This is a schematic diagram of a nuclear reactor under normal operating conditions provided in an embodiment of this application;

[0028] Figure 2 This is a schematic diagram of a nuclear reactor at the initial moment of an accident, provided in an embodiment of this application.

[0029] Figure 3 This is a schematic diagram of the adaptive adjustment of a nuclear reactor after an accident, provided in an embodiment of this application.

[0030] Figure 4 This is a structural schematic diagram of the expansion container and damper counterweight provided in the embodiments of this application.

[0031] The reference numerals in the figure are as follows:

[0032] 100. Nuclear reactor; 1. Reactor body; 2. Core heat exchanger; 3. Expansion vessel; 4. Flow diode; 5. Air-cooled exhaust heat exchanger; 6. Air-cooled tower; 7. Damper counterweight; 7-1. Counterweight metal; 7-2. Cavity; 8. Coolant; 9. Redundant connector; 10. Seal; 11. Damper connector; 12. Fixed pulley; 13. Damper fixing device; 14. Damper; 15. Damper electromagnetic interlocking device; 16. Covered gas loop; 17. Connecting intermediate parts; 18. Covered gas space. Detailed Implementation

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0034] As indicated in this application, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. Furthermore, it should be noted that the use of words such as "first" and "second" to define the object is merely for the purpose of distinguishing the corresponding objects, and unless otherwise stated, the above words have no special meaning and therefore should not be construed as limiting the scope of protection of this application.

[0035] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0036] Furthermore, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of the description herein. Moreover, this application is to be understood not only by the actual terms used, but also by the meaning implied by each term.

[0037] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0038] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0039] It should be understood that when a component is referred to as "on another component," "connected to another component," "coupled to another component," or "in contact with another component," it can be directly on, connected to, coupled to, or in contact with that other component, or there may be an insert component. In contrast, when a component is referred to as "directly on another component," "directly connected to," "directly coupled to," or "directly in contact with" another component, there is no insert component. Similarly, when a first component is referred to as "electrically contacting" or "electrically coupled to" a second component, there is an electrical path between the first and second components that allows current to flow. This electrical path may include capacitors, coupled inductors, and / or other components that allow current to flow, even if there is no direct contact between metallic components.

[0040] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0041] Please refer to Figure 1 , Figure 1 A schematic diagram of a nuclear reactor 100 under normal operating conditions according to an exemplary embodiment of this application is shown. It will be understood that the nuclear reactor 100 is not required to include... Figure 1 All the elements shown in the diagram may also be included in nuclear reactor 100. Figure 1 Other elements not shown in the text.

[0042] Nuclear reactor 100 includes a primary loop system and a passive residual heat removal system. The primary loop system includes the reactor body 1, the hot side of the core heat exchanger 2, and corresponding piping, such as coolant piping. The passive residual heat removal system is connected in parallel to the cold side of the core heat exchanger 2 and includes a flow diode 4, an air-cooled residual heat exchanger 5, an air-cooled tower 6, and corresponding piping, such as coolant piping. A damper 14 is installed inside the air-cooled tower 6. The air cooling passages inside the air-cooled tower 6 are opened / closed by opening / closing the damper 14.

[0043] The nuclear reactor 100 also includes a passive damping system. The passive damping system includes an expansion vessel 3 and damper counterweights 7. The expansion vessel 3 is connected to the coolant conduits of the nuclear reactor 100 and is capable of containing the coolant 8 of the nuclear reactor. In some embodiments, the bottom of the expansion vessel 3 is connected to the coolant conduits of the nuclear reactor via connecting pipes, which facilitates a passive design. The coolant conduits are used for the flow of coolant 8. The coolant 8 of the nuclear reactor 100 typically exhibits thermal expansion and contraction characteristics. Exemplarily, the coolant 8 includes lead, a lead-bismuth alloy, liquid sodium, or molten salt, etc. Figure 1 In the illustrated embodiment, the expansion vessel 3 is connected to the coolant piping of the primary loop system. In other embodiments, the expansion vessel 3 may also be installed on the cold-side piping of the heat exchanger in the passive residual heat removal system to monitor the secondary loop temperature of the nuclear reactor 100, or it may be installed in the intermediate loop of the tertiary loop system, as long as the coolant level change in the expansion vessel 3 can reliably reflect the system temperature that needs to be prevented from overcooling.

[0044] The damper counterweight 7 is connected to the damper 14 and can float on the surface of the coolant 8 in the expansion vessel 3. The damper counterweight 7 is used to control the opening of the damper 14 to increase as the coolant 8 level in the expansion vessel 3 rises after the nuclear reactor 100 enters the passive residual heat removal mode, and to control the opening of the damper 14 to decrease as the coolant 8 level in the expansion vessel 3 falls.

[0045] This application utilizes the physical phenomenon of coolant density changes caused by temperature variations in the nuclear reactor 100, leading to fluctuations in the liquid level within the expansion vessel 3. This fluctuation serves as the input signal to control the opening of the damper 14, transmitting the liquid level change as the opening or closing action of the damper 14, thereby regulating the heat dissipation intensity of the air-cooled tower 6. When the coolant temperature is too low and there is a risk of solidification, the liquid level in the expansion vessel 3 drops, driving the damper 14 to close slightly to maintain temperature; when the coolant temperature rises, the liquid level in the expansion vessel 3 rises, causing the damper 14 to open wider to enhance heat dissipation. This forms an internal, continuously acting negative feedback loop, achieving intelligent temperature self-regulation without external energy intervention. This fundamentally reduces the risk of overcooling and solidification in passive systems during the later stages of an accident, improving the safety and reliability of the nuclear reactor. Furthermore, this application's embodiments are applicable to advanced nuclear energy systems employing high-melting-point coolants, such as molten salt reactors, lead-based cooled fast reactors, and sodium-cooled fast reactors.

[0046] In some embodiments, the passive damper system further includes a damper opening / closing device and a connecting device. The damper opening / closing device is connected to the damper 14. The damper opening / closing device is used to control the damper 14 to remain closed under normal operating conditions of the nuclear reactor 100, and to control the damper 14 to open to the fully open position in response to the nuclear reactor 100 entering a passive residual heat removal mode. Figure 1In the illustrated embodiment, the damper opening and closing device includes a damper fixing device 13 and a damper electromagnetic interlocking device 15. The damper fixing device 13 is used to guide the damper 14. The damper electromagnetic interlocking device 15 is used to hold the damper 14 closed under normal operating conditions, and in response to the nuclear reactor 100 entering a passive residual heat removal mode, to release the damper 14 upon de-energization, allowing the damper 14 to open freely under gravity. It is understood that the damper opening and closing device is not limited to... Figure 1 In the embodiments shown, other embodiments may also employ spring energy storage (releasing the potential energy of a torsion spring or compression spring during an accident), pneumatic / hydraulic energy storage (releasing compressed gas or hydraulic drive), or active motor drive, as long as passive or reliable triggering is achieved at the initial stage of an accident. The embodiments of this application achieve the initial opening of the damper 14 through the loss of maintaining force or the release of the energy storage element, ensuring automatic activation without external intervention when safety functions are required.

[0047] One end of the connecting device is connected to the damper 14, and the other end is connected to the damper counterweight 7. The connecting device is used to, after the nuclear reactor 100 enters the passive residual heat removal mode, respond to the coolant 8 level in the expansion vessel 3 being lower than a first threshold, causing the damper counterweight 7 to pull the damper 14 to reduce its opening; and respond to the coolant 8 level in the expansion vessel 3 being higher than a second threshold, causing the damper 14 to increase its opening under gravity. The first and second thresholds can be set in advance according to actual conditions, such as based on the thermal expansion coefficient of the coolant, the geometry of the expansion vessel 3, and the relationship between the expected threshold liquid level and the steady-state liquid level of the system, as long as there is a one-to-one correspondence between the average temperature of the loop coolant (such as primary or secondary coolant) and the expected liquid level in the expansion vessel 3. Figure 1 In the illustrated embodiment, the connecting device includes a damper connector 11 and a redundant connector 9. The damper connector 11 is connected to the damper 14 and can be a rope, rod, or chain. One end of the redundant connector 9 is connected to the damper connector 11, and the other end is connected to the damper counterweight 7. The redundant connector 9 can be a rope, chain, or spring, or other telescopic connector. Under normal operating conditions, the redundant connector 9 is in a relaxed state. After the nuclear reactor 100 enters the passive residual heat removal mode, the redundant connector 9 can taut when the damper 14 is in the fully open position. In an exemplary embodiment, the length of the redundant connector 9 is set such that the redundant connector 9 can taut when the damper opening and closing device controls the damper 14 to open to the fully open position. The following description uses the example where both the damper connector 11 and the redundant connector 9 are ropes.

[0048] Continue to refer to Figure 1The damper 14 is connected to the damper counterweight 7 floating on the surface of the coolant 8 in the expansion container 3 via the damper connector 11, which bypasses the fixed pulley 12, and is connected to the damper counterweight 7 in the air-cooled tower 6 via a redundant connector 9 of reserved length. This embodiment of the application creates a direct mechanical causal chain by setting a damper counterweight 7 floating on the surface of the coolant 8 in the expansion container 3 and connecting it to the damper 14 in the air-cooled tower 6 via a rope bypassing the fixed pulley 12: liquid level change - vertical displacement of the damper counterweight 7 - slack or tension of the rope - opening or closing of the damper 14. It is understood that the fixed pulley 12 can be replaced with other guiding devices, such as gears and racks, linkage mechanisms, etc., as long as they can convert the liquid level change into a mechanical linkage for damper action.

[0049] Under normal operating conditions, the coolant in the primary loop system is heated by the reactor body 1 and releases heat on the hot side of the core heat exchanger 2. The passive residual heat removal system restricts the inflow of only a small amount of coolant through the flow diode 4, maintaining a hot standby state. This portion of the incoming coolant is cooled by the air-cooled residual heat removal heat exchanger 5 and then flows into the main loop. At this time, the damper 14 is held closed by the damper electromagnetic interlocking device 15. The weight of the damper counterweight 7 is set to be greater than the force required to pull the damper, and the redundant connector 9 has a reserved length. The damper counterweight 7 floats on the coolant surface of the expansion vessel 3, and the redundant connector 9 is in a relaxed state. This ensures that the damper 14 is reliably closed before an accident, while reserving operational space for the opening of the damper 14 during an accident.

[0050] In some embodiments, the overall average density of the damper counterweight 7 is less than the density of the coolant 8, thereby allowing the damper counterweight 7 to both float on the surface of the coolant 8 within the expansion container 3 and pull the damper 14. Exemplarily, the damper counterweight 7 can be in the form of an internal cavity, a hollow seal, a porous structure, a composite material, etc. It is understood that the damper counterweight 7 can also float on the surface of the coolant 8 within the expansion container 3 with the assistance of other devices (such as connecting devices).

[0051] At the time of the accident, reactor 100 entered passive residual heat removal mode. Please refer to... Figure 2 At the initial moment of the accident, the electromagnetic interlock device 15 of the damper was de-energized and released, causing the damper 14 to rapidly open to the fully open position under its own gravity. The opening of the damper 14 simultaneously sturdied the slack redundant connector 9. At this time, the primary loop relied on natural circulation to transfer the core residual heat to the hot side of the core heat exchanger 2. Since the cold side of the core heat exchanger 2 also lost its forced circulation power, and the fully open damper 14 significantly enhanced the natural circulation driving force on the air side of the air-cooled tower 6, the combined effect reversed the coolant flow direction in the passive residual heat removal system, establishing natural circulation. Thus, the residual heat generated by the core and primary loop was ultimately discharged into the ambient atmosphere through the natural circulation of the primary loop, the natural circulation of the passive residual heat removal system, and the natural air circulation within the air-cooled tower 6.

[0052] Post-accident adaptive adjustment, such as Figure 3 As shown. In the initial stage of the accident, because the waste heat power of the primary loop is higher than the heat removal power of the passive waste heat removal system, the average temperature of the primary loop rises, the coolant density decreases, and the coolant level 8 in the expansion container 3 rises. The rise in liquid level causes the damper counterweight 7 to float upward, causing the redundant connecting parts 9, which were taut at the beginning of the accident, to relax again. At this time, the damper 14 remains fully open under the action of gravity, and the system's heat removal capacity is maintained at its maximum value. As the accident progresses into the later stage, the decay heat power of the primary loop continues to decrease, the average temperature of the primary loop decreases, the coolant density increases and contracts, causing the liquid level in the expansion container 3 to drop. The damper counterweight 7 descends with the liquid level. When the damper counterweight 7 descends to the point that it tauts the relaxed redundant connecting parts 9 again, it begins to pull the damper 14, causing it to slowly close against gravity, thereby reducing the heat removal power of the air-cooled tower 6. If the temperature of the primary loop rises again due to reduced heat dissipation, the coolant level 8 in the expansion container 3 will rise accordingly, causing the damper counterweight 7 to float upwards. The damper 14 will then reopen under gravity to enhance heat dissipation. This cycle repeats, forming a negative feedback adaptive adjustment process around a certain equilibrium temperature point, fundamentally reducing the risk of coolant solidification due to overcooling in the primary loop and passive waste heat removal system.

[0053] In the above embodiments, when an accident occurs, the opening of the damper 14 simultaneously straightens the redundant connector 9, which is in a relaxed state. It should be understood that in some other embodiments, the opening of the damper 14 may simultaneously leave the redundant connector 9 in a relaxed state. In this case, when the coolant level 8 in the expansion container 3 drops to a certain position, such as when the coolant level 8 in the expansion container 3 is below a first threshold, the redundant connector 9 will then straighten and pull the damper 14 to close. The length of the redundant connector 9 can be specifically set according to the properties of the coolant.

[0054] Please refer to Figure 4 , Figure 4 A schematic diagram of the expansion container 3 and the damper counterweight 7 according to an exemplary embodiment of this application is shown. The space above the liquid level of the coolant 8 inside the expansion container 3 is formed as a covering gas space 18. The covering gas space 18 is connected to a covering gas source (not shown) via a covering gas circuit 16, thereby the pressure of the covering gas space 18 is controlled by the covering gas circuit 16.

[0055] The redundant connector 9 is disposed inside the expansion container 3. In some embodiments, the redundant connector 9 is connected to the damper counterweight 7 via the connecting intermediate member 17, and a length is reserved to provide the necessary stroke for the up and down floating of the damper counterweight 7 and the opening and closing of the damper 14 after an accident.

[0056] The passive damper system also includes a seal 10. The seal 10 is located at the top of the expansion container 3. Figure 4 In the illustrated embodiment, the damper connector 11 passes through the seal 10 into the expansion container 3 and is then connected to the redundant connector 9. This ensures the airtightness of the covered gas space 18 when the damper connector 11 is in motion, preventing leakage of the covered gas. In other embodiments, the redundant connector 9 passes through the seal 10 out of the expansion container 3 and is then connected to the damper connector 11.

[0057] The damper counterweight 7 includes a counterweight metal 7-1. The counterweight metal 7-1 is made of a high-temperature resistant and corrosion-resistant alloy, such as UNS N10003 or GH3535. The counterweight metal 7-1 has an internal cavity 7-2, making the overall average density of the damper counterweight 7 less than the density of the coolant 8, thus allowing the damper counterweight 7 to float on the surface of the coolant 8. Simultaneously, the weight of the damper counterweight 7 is greater than the minimum force required to close the damper 14, thereby ensuring reliable damper locking before an accident and adaptive adjustment after an accident.

[0058] This application's embodiment achieves a completely passive process from triggering and execution to regulation. Its working principle is based on inherent physical laws: gravity (driving the damper downwards), buoyancy (supporting the counterweight), and thermal expansion and contraction (the medium's volume changes with temperature). In the initial stage of an accident, the damper opens automatically by gravity, requiring no external energy; in subsequent long-term regulation, its opening change is directly driven by the fluctuations in coolant level caused by temperature. This design eliminates reliance on external active components (such as motors and pumps), control signals, or human intervention. Because this application's embodiment does not rely on potentially failing external factors, it possesses inherent safety characteristics; that is, its safety is guaranteed by natural laws and is an inherent attribute of the system. This reduces the probability of functional failure due to power source loss or control system malfunction, thereby improving the inherent safety level of the nuclear energy system.

[0059] This application embodiment constructs an inherent, highly efficient negative feedback regulation loop. This embodiment directly translates the core parameter of the primary loop average temperature into mechanical control of the damper opening through changes in the coolant level within the expansion container. Its regulation logic precisely corresponds to safety requirements: when there is a risk of coolant solidification (in the later stages of an accident, decay heat decreases, and the temperature drops), the coolant level in the expansion container decreases, and the damper counterweight pulls the damper closed via a rope mechanism, weakening the heat dissipation capacity of the air-cooled tower and achieving heat preservation; conversely, if the temperature rises, the coolant level in the expansion container rises, and the damper opens wider under gravity, enhancing heat dissipation. This demand-driven adaptive process is similar to an intelligent thermostat, dynamically maintaining the primary loop temperature within a safe window, effectively reducing the risk of overcooling that may occur in traditional passive systems in the later stages of an accident, and physically reducing the risk of coolant solidification in the waste heat removal system, thus improving the continuity of long-term heat removal function.

[0060] Furthermore, the core operating components of this application embodiment consist of a damper counterweight, a connecting device, and a damper, exhibiting far fewer failure modes than those of active actuators (such as electric or pneumatic valves) that contain precision parts and require electrical drive. The simpler mechanical system implies a lower inherent failure rate, stronger anti-interference capabilities (robustness), and better tolerance to harsh environments (such as earthquakes, high temperatures, and radiation). Even under extreme accident conditions, the functionality of this application embodiment is not easily degraded. Based on simple physical principles, the design demonstrates far greater resilience and survivability than complex systems when facing the complex and ever-changing accident conditions of nuclear power plants, providing a solid and reliable underlying guarantee for nuclear safety.

[0061] Meanwhile, the embodiments of this application feature a simple structure and significant economic advantages. On the one hand, the embodiments of this application reduce initial construction costs by eliminating expensive active control valves, corresponding sensors, actuators, and complex control cabinets, cabling, and power supply systems. On the other hand, the embodiments of this application significantly reduce the overall lifecycle maintenance costs. The simple mechanical structure virtually eliminates the need for regular maintenance and replacement of vulnerable parts. Furthermore, its high reliability reduces the risk of unplanned reactor shutdowns due to equipment failure and the resulting economic losses. In addition, the simplified structure reduces the engineering complexity of design, installation, and commissioning, thereby shortening the construction period and further improving economic efficiency.

[0062] The passive damper system of this application embodiment can be conveniently added as a relatively independent functional module to existing or newly designed passive waste heat removal systems and air-cooled towers. This design eliminates the need for any modifications to core equipment such as the reactor primary loop and main heat exchanger, significantly reducing the difficulty and risk of technical upgrades and facilitating safety improvements for in-service units or design optimizations for new units under construction. Furthermore, it offers high engineering feasibility, enabling rapid and effective improvement of the safety performance of the entire nuclear energy system at a relatively low cost, thus possessing significant engineering application value.

[0063] The basic concepts have been described above. Obviously, for those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0064] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0065] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the present application requires more features than those mentioned. In fact, the embodiments have fewer features than all the features of the single embodiments disclosed above.

[0066] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the scope of the essential spirit of this application will fall within the scope of this application.

Claims

1. A passive damper system for a nuclear reactor, the nuclear reactor including a primary loop system and a passive residual heat removal system, the passive residual heat removal system including an air cooling tower and a damper disposed within the air cooling tower, characterized by, The non-active air door system comprises: an expansion vessel in communication with a coolant pipe of the nuclear reactor, the expansion vessel being capable of containing the coolant of the nuclear reactor, the coolant having the property of thermal expansion and contraction; an air door counterweight connected with the air door and capable of floating on the liquid level of the coolant in the expansion vessel, the air door counterweight being used to control the increase of the opening degree of the air door with the increase of the liquid level of the coolant in the expansion vessel and to control the decrease of the opening degree of the air door with the decrease of the liquid level of the coolant in the expansion vessel after the nuclear reactor enters a non-active residual heat removal mode; an air door opening and closing device connected with the air door, the air door opening and closing device being used to control the air door to keep closed in a normal operating condition of the nuclear reactor and to control the air door to open to a full opening position in response to the nuclear reactor entering the non-active residual heat removal mode; a connecting device, one end of the connecting device being connected with the air door and the other end being connected with the air door counterweight, the connecting device being used to make the air door counterweight pull the air door to decrease the opening degree in response to the liquid level of the coolant in the expansion vessel being lower than a first threshold value and to make the air door increase the opening degree under the action of gravity in response to the liquid level of the coolant in the expansion vessel being higher than a second threshold value after the nuclear reactor enters the non-active residual heat removal mode; wherein the air door opening and closing device comprises: an air door fixing device used to guide the air door; an air door electromagnetic locking device used to adsorb the air door to keep the air door closed in the normal operating condition of the nuclear reactor and to release the air door to make the air door freely open under the action of gravity in response to the nuclear reactor entering the non-active residual heat removal mode.

2. The passive damper system of claim 1, wherein, the connecting device comprises: an air door connecting member connected with the air door; a redundant connecting member, one end of the redundant connecting member being connected with the air door connecting member and the other end being connected with the air door counterweight, the redundant connecting member being in a relaxed state in the normal operating condition of the nuclear reactor and being capable of being straightened when the air door is in the full opening position after the nuclear reactor enters the non-active residual heat removal mode.

3. The passive damper system of claim 2, wherein, The length of the redundant connecting member is set to enable the redundant connecting member to be straightened when the air door opening and closing device controls the air door to open to the full opening position.

4. The passive damper system of claim 2, wherein, The redundant connecting member is arranged in the expansion vessel.

5. The passive damper system of claim 4, wherein, A space above the liquid level of the coolant in the expansion vessel is formed into a cover gas space, the cover gas space being in communication with a cover gas source through a cover gas loop, and the non-active air door system further comprises: a seal arranged at the top of the expansion vessel, the air door connecting member penetrating into the expansion vessel through the seal or the redundant connecting member penetrating out of the expansion vessel through the seal.

6. The passive damper system of claim 1, wherein, The weight of the air door counterweight is set to be greater than the force required to pull the air door.

7. The passive damper system of claim 6, wherein, The overall average density of the air door counterweight is less than the density of the coolant.

8. The passive damper system of any one of claims 1-7, wherein, The bottom of the expansion vessel is in communication with the coolant pipe of the nuclear reactor through a connecting pipe; and / or The expansion vessel is in communication with the coolant pipe of the one loop system.

9. A nuclear reactor comprising a primary loop system and a passive residual heat removal system, the passive residual heat removal system comprising an air cooling tower and a damper disposed within the air cooling tower, characterized in that, The nuclear reactor comprises the passive damper system of any one of claims 1-8. The nuclear reactor comprises the passive damper system of any one of claims 1-8.

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