Self-starting and self-adjusting passive residual discharge system of lead-based reactor

Abstract

The invention belongs to the technical field of lead-based reactors, and particularly relates to a self-starting and self-adjusting passive residual discharge system of a lead-based reactor. The device comprises a residual heat exchanger, a reactor container, a residual system final heat trap and a steam pocket, the residual heat exchanger is mounted on the reactor container, one end of the residual heat exchanger extends out of the reactor container, and the other end of the residual heat exchanger is immersed in a reactor coolant in the reactor container; the upper end of the waste heat exchanger is communicated with the waste system final heat trap through a waste system steam pipeline, the waste system final heat trap is communicated with the steam pocket through a water supply pipeline, and the bottom of the steam pocket is connected with the waste heat exchanger through the waste system water supply pipeline to form a loop. According to the invention, comprehensive passive design from starting to operation is ensured, the reliability of putting the residual discharge system into operation is effectively improved, and the self-adjusting capability of the residual discharge system is further enhanced.

Description

Technical Field

[0001] This invention belongs to the field of lead-based reactor technology, specifically relating to a self-starting and self-regulating passive residual discharge system for lead-based reactors. Background Technology

[0002] The residual heat removal system is a safety-level system within the reactor. It ensures the normal operation of the reactor's residual heat removal function after the normal heat removal system fails, and is crucial for reactor safety.

[0003] With the widespread adoption of passive safety design principles in the design of advanced light water reactors such as Hualong One, fourth-generation nuclear energy systems are also continuously drawing on relevant experience to further improve their safety and reliability, avoiding the use of non-novel coolants as weak points in safety design. As a typical representative of reactor types in fourth-generation nuclear energy systems, lead-based reactors have received long-term and continuous research investment both domestically and internationally due to their inherent safety and economic advantages. In lead-based reactors, to greatly reduce the demands on power supply, energy storage, and related technology reliability, safety systems such as emergency shutdown systems, residual heat removal systems, reactor vessel overpressure protection systems, and radioactive containment systems adopt passive operation design principles as much as possible, which is also a major characteristic of fourth-generation nuclear energy system design. Internationally, numerous passive waste heat removal system designs have been proposed, such as waste heat removal systems based on main steam generators, independent condenser cooling systems, reactor vessel cooling systems, and covering gas spray systems. Their basic passive operation design principles are mainly based on the natural circulation of the cooling loop (the thermal expansion and contraction or phase change of the coolant creates a density difference, thereby increasing the driving force of the natural circulation), the pre-installation of water storage tanks (evaporation / boiling or thermal convection), or the use of a continuous supply of fresh air (thermal convection) as the heat removal medium.

[0004] Although passive residual heat recovery systems operate passively, the vast majority of their activation and startup are active, requiring external power supplies and control signals for valve opening and closing. Utilizing the reactor's own energy to automate valve operation, thus eliminating the need for external power supplies, is crucial for improving the reliability of residual heat recovery systems. Furthermore, allowing valve operation to be controlled mechanically, rather than solely relying on digital control systems, is also significant for enhancing the reliability of residual heat recovery systems in the face of digital control system failures, electromagnetic interference (such as solar storms), and electromagnetic attacks. Currently, there are limited technological solutions developed domestically and internationally for the self-starting of residual heat recovery systems. A typical example is the reactor vessel air cooling system, where louvers automatically open to a certain degree due to thermal expansion when the air temperature reaches a certain level, thereby dissipating residual heat. Further research is needed on specific self-starting solutions for residual heat recovery systems.

[0005] Unlike pressurized water reactors, lead-based reactors use lead-based coolants with higher melting points. The melting point of lead-bismuth alloy is 124.85℃, while that of pure lead is 327.85℃. Compared to iron, the melting points of lead-bismuth alloy and pure lead are relatively low, allowing them to remain liquid without requiring extremely high temperatures. However, their melting points are still much higher than ambient temperature (25℃). If ambient air or water is used as the heat transfer medium, the lead-based coolant is likely to solidify during waste heat removal. Of course, the "condensed shell" formed by the solidification of the lead-based coolant close to the heat exchange wall will trigger a negative feedback effect in heat transfer; that is, the presence of the "condensed shell" will narrow the coolant flow path, reduce heat transfer capacity, and thus inhibit further "condensation." However, the structural stability of the "condensed shell" still requires further study. An unstable "condensed shell" may lead to damage to structural materials such as heat exchange tubes or blockage of local flow channels in the core, resulting in deterioration of local heat transfer in the core and threatening the integrity of the reactor fuel element cladding and the primary coolant loop. Therefore, lead-based reactors have special requirements for the exhaust system, emphasizing its self-regulating capability. That is, the exhaust system should adaptively adjust its heat removal capacity according to the state of the primary side of the heat exchanger (temperature, heat production power, etc.), thereby ensuring that the reactor primary loop reaches the expected state as soon as possible while avoiding overcooling of the primary loop and causing the primary coolant to solidify. The development of self-regulating technologies for residual exhaust systems, both domestically and internationally, is limited. The most well-known scheme is the one proposed by Alemberti et al. in Italy, which weakens heat transfer through non-condensable gas mixing. This scheme works by entraining more non-condensable gases into the system when the natural circulation flow rate is high, thus preventing excessive heat transfer. Conversely, when the natural circulation flow rate is low, some of the entrained non-condensable gases return to the non-condensable gas tank, preventing the system's heat removal capacity from becoming too low. However, the entrainment of non-condensable gases into the residual exhaust system presents significant challenges to analytical models, especially concerning multi-component, multiphase flow problems that remain unresolved, requiring extensive and complex experimental research. Further research and improvement are needed for specific residual exhaust system solutions.

[0006] Therefore, proposing a self-starting and self-regulating passive residual discharge system for lead-based reactors, while ensuring that the functional characteristics conform to the reactor design concept, and minimizing the design and manufacturing burden to meet industrial needs to the greatest extent, is a very important technological innovation consideration. Summary of the Invention

[0007] The technical problem solved by this invention is to provide a self-starting and self-regulating passive residual exhaust system for lead-based reactors, ensuring a fully passive design from startup to operation, effectively improving the reliability of the residual exhaust system in operation, and further enhancing the self-regulating capability of the residual exhaust system.

[0008] The technical solution adopted in this invention is as follows:

[0009] A self-starting and self-regulating passive residual heat exchange system for a lead-based reactor includes a residual heat exchanger, a reactor vessel, a residual heat system final heat sink, and a steam drum. The residual heat exchanger is installed on the reactor vessel, with one end extending outside the reactor vessel and the other end immersed in the reactor coolant inside the reactor vessel. The upper end of the residual heat exchanger is connected to the residual heat system final heat sink via a residual heat system steam pipeline. The residual heat system final heat sink is connected to the steam drum via a feedwater pipeline. The bottom of the steam drum is connected to the residual heat exchanger via a residual heat system feedwater pipeline, forming a loop.

[0010] The residual heat sink of the system is equipped with a small heat exchanger and a large heat exchanger, which are arranged in parallel. The steam pipeline of the residual heat sink is connected to the small heat exchanger and the large heat exchanger respectively.

[0011] The water supply pipeline includes a first water supply pipeline and a second water supply pipeline. The first water supply pipeline is connected to a small heat exchanger, and the second water supply pipeline is connected to a large heat exchanger.

[0012] The first water supply pipeline is equipped with a second isolation control valve, the second water supply pipeline is equipped with a third isolation control valve, and the residual discharge system water supply pipeline is equipped with a first isolation control valve.

[0013] The steam drum is equipped with an L-shaped partition plate that separates the natural circulation water drum and the buffer water drum. The buffer water drum and the natural circulation water drum share a steam drum.

[0014] The natural circulation water tank adopts a structural design that is narrow at the top and open at the bottom, and the cross-sectional area of ​​the upper part of the natural circulation water tank is much smaller than that of the buffer water tank.

[0015] The buffer water tank is located inside the isolation plate, and the natural circulation water tank is located outside the isolation plate. The natural circulation water tank and the buffer water tank are connected externally through an isolation valve.

[0016] The exhaust heat exchanger is equipped with a self-starting temperature sensing module. The first isolation control valve, the second isolation control valve, and the third isolation control valve are respectively equipped with a first isolation control valve automatic control mechanism, a second isolation control valve automatic control mechanism, and a third isolation control valve automatic control mechanism. The self-starting temperature sensing module is connected to the first isolation control valve automatic control mechanism, the second isolation control valve automatic control mechanism, and the third isolation control valve automatic control mechanism through temperature / pressure transmission lines.

[0017] The natural circulation water tank is located above the exhaust heat exchanger, and the small heat exchanger and the large heat exchanger are located above the natural circulation water tank and the buffer water tank.

[0018] The working fluid flowing from the final heat sink of the residual discharge system first passes through the steam drum area directly above the buffer water tank and then enters the buffer water tank.

[0019] The opening of the first isolation control valve, the second isolation control valve, and the third isolation control valve adopts two methods: active start and automatic start. The opening degree determines whether the residual discharge system is opened and the flow resistance of the corresponding pipeline.

[0020] The self-starting of the first isolation control valve, the second isolation control valve, and the third isolation control valve adopts multiple methods such as bimetallic differential expansion, pneumatic or hydraulic drive.

[0021] In temperature conduction mode, the temperature / pressure conduction line is a high thermal conductivity heat conductor, which needs to be insulated from the external environment; in pressure conduction mode, the temperature / pressure conduction line is a gas channel or liquid channel, which needs to be sealed from the external environment.

[0022] The self-starting temperature sensing module is mass-isolated from the reactor primary loop, but heat can be freely transferred.

[0023] After the first, second, and third isolation control valves are opened, under the action of natural circulation driving force, the water in the natural circulation water tank will flow into the secondary side of the residual heat exchanger along the feed water pipeline of the residual heat exchange system. Under the heating of the primary coolant, it will quickly boil and vaporize, and then flow through the two heat exchangers in two paths along the steam pipeline. After cooling and condensation, it will enter the steam drum along the feed water pipeline of the residual heat exchange system heat dissipation section. In the steam drum, the water and steam will automatically separate, and the water will remain in the buffer water tank. When the water level in the buffer water tank rises to the upper limit of the isolation plate, the water that the buffer water tank cannot hold will flow into the natural circulation water tank.

[0024] The resistance of the first water supply pipeline is less than that of the second water supply pipeline.

[0025] The beneficial effects of this invention are:

[0026] (1) The lead-based reactor self-starting and self-regulating passive exhaust system provided by the present invention can ensure that the exhaust system has sufficiently strong self-starting, exhaust power self-regulation and passive characteristics. It can be combined with the current active start-up, thereby greatly improving the reliability of the passive exhaust system. While avoiding the solidification caused by excessive cooling of the primary loop of the lead-based reactor, it can greatly reduce the need for exhaust system analysis methods, models and related experiments.

[0027] (2) The lead-based reactor self-starting and self-regulating passive residual discharge system provided by the present invention can reduce or even eliminate the dependence on emergency power supply and its reliability, while the implementation scheme selection is more flexible;

[0028] (3) The lead-based reactor self-starting and self-regulating passive residual discharge system provided by the present invention can achieve the purpose of self-regulating residual discharge power, reducing the need for analysis models (such as phase change model and flow heat transfer model of multi-component multiphase fluid after non-condensable gas is mixed with water / water vapor).

[0029] (4) The present invention provides a self-starting and self-regulating passive exhaust system for lead-based reactors. The passive operation capability of the exhaust system for lead-based reactors is still achieved in the traditional way, including but not limited to: for loop type, the heat sink is arranged above the heat source to establish a certain natural circulation height, thereby providing a natural circulation driving head; for continuous air cooling, the flow channel needs to be reasonably arranged to remove heat by relying on the thermal convection effect; for cases that rely on additional working fluids such as water, a high-level water tank or high-pressure working fluid tank needs to be set up in advance. When exhaust needs to be started, the valve is opened to allow water / cooling working fluid to be injected into the corresponding chamber under the action of gravity, and heat is removed by phase change processes such as heating and evaporation / boiling.

[0030] (5) This invention provides a self-starting and self-regulating passive exhaust system for a lead-based reactor. The self-starting capability of the exhaust system is achieved by relying on the primary loop to provide energy and drive signals to control the valves related to the exhaust system startup. This invention provides diverse self-starting schemes, including a pneumatic valve control scheme based on primary loop temperature, a hydraulic valve control scheme based on primary loop temperature, a bimetallic strip differential expansion valve control scheme based on primary loop temperature, and a pneumatic valve control scheme based on primary loop flow rate. To ensure that the self-starting scheme can be reused multiple times, and considering a certain degree of self-regulation capability, the Curie point temperature lock scheme and the melt lock scheme, which have obvious one-time characteristics, are excluded.

[0031] (6) The self-regulating capability of the lead-based reactor exhaust system is based on the natural circulation principle and common design concepts such as buffer / bypass parallel connection to achieve a high self-regulating capability. The passive exhaust heat removal capability depends on the relationship between the loop natural circulation drive head and the loop flow resistance, while the natural circulation drive head depends on the natural circulation height and the density difference between the hot and cold fluids. By adding an intermediate structure to the steam-water drum and adopting a vertical, narrow water drum structure, the sensitivity of the natural circulation height to the water volume is increased, thereby preventing the exhaust system's heat removal capability from being at a high level for a long time. By adding a buffer structure, the sensitivity of the natural circulation height to the water volume is ensured. By adding a heat sink bypass parallel structure, the heat removal capability of the exhaust system's heat sink is adaptively adjusted, thereby adaptively adjusting the exhaust system's heat removal capability. Attached Figure Description

[0032] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in describing the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments recorded in the present invention. Those skilled in the art can derive other drawings from the following drawings without any creative effort.

[0033] Figure 1 This is a schematic diagram of a self-starting and self-regulating passive residual exhaust system for a lead-based reactor provided by the present invention;

[0034] In the diagram: 1. Excess heat exchanger, 2. Reactor coolant, 3. Reactor vessel, 4. Self-starting temperature sensing module, 5. Temperature / pressure transmission line, 6. First isolation control valve, 7. Automatic control mechanism of the first isolation control valve, 8. Temperature / pressure transmission line, 9. Second isolation control valve, 10. Automatic control mechanism of the second isolation control valve, 11. Temperature / pressure transmission line, 12. Third isolation control valve, 13. Automatic control mechanism of the third isolation control valve, 14. Excess system feedwater pipeline, 15. Natural circulation water tank, 16. Isolation valve, 17. Buffer water tank, 18. Isolation plate, 19. Steam drum, 20. First feedwater pipeline, 21. Second feedwater pipeline, 22. Excess system final heat sink, 23. Small heat exchanger, 24. Large heat exchanger, 25. Excess system steam pipeline. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0036] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., refer to the orientation or positional relationship shown in the accompanying drawings, and are used only for the convenience of describing the invention and simplifying the description, and 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 of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or a connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] like Figure 1As shown, the present invention provides a self-starting and self-regulating passive residual exhaust system for a lead-based reactor, comprising a residual exhaust heat exchanger 1, a reactor vessel 3, a residual exhaust system final heat sink 22, and a steam drum 19. The residual exhaust heat exchanger 1 is installed on the reactor vessel 3, with one end extending outside the reactor vessel 3 and the other end immersed in the reactor coolant 2 inside the reactor vessel 3. The upper end of the residual exhaust heat exchanger 1 is connected to the residual exhaust system final heat sink 22 via a residual exhaust system steam pipeline 25. The residual exhaust system final heat sink 22 is equipped with a small heat exchanger 23 and a large heat exchanger 24, which are arranged in parallel. The waste heat system steam pipeline 25 is connected to the small heat exchanger 23 and the large heat exchanger 24 respectively; the waste heat system final heat sink 22 is connected to the steam drum 19 through a feedwater pipeline, which includes a first feedwater pipeline 20 and a second feedwater pipeline 21. The first feedwater pipeline 20 is connected to the small heat exchanger 23 and is equipped with a second isolation control valve 9; the second feedwater pipeline 21 is connected to the large heat exchanger 24 and is equipped with a third isolation control valve 12; the bottom of the steam drum 19 is connected to the waste heat exchanger 1 through the waste heat system feedwater pipeline 14, forming a loop, and the waste heat system feedwater pipeline 14 is equipped with... There is a first isolation control valve 6; the steam drum 19 is equipped with an L-shaped isolation plate 18, which separates the natural circulation water tank 15 and the buffer water tank 17. The buffer water tank 17 and the natural circulation water tank 15 share a steam drum 19; the buffer water tank 17 is located inside the isolation plate 18, and the natural circulation water tank 15 is located outside the isolation plate 18. The natural circulation water tank 15 adopts a structure design that is narrow at the top and open at the bottom, and the cross-sectional area of ​​the upper part of the natural circulation water tank 15 is much smaller than that of the buffer water tank 17; the natural circulation water tank 15 and the buffer water tank 17 are connected externally through an isolation valve 16; the steam flows from the final heat sink 22 of the exhaust system. The working fluid is first introduced into the steam drum area directly above the buffer water tank 17; the residual heat exchanger 1 is equipped with a self-starting temperature sensing module 4, and the first isolation control valve 6, the second isolation control valve 9, and the third isolation control valve 12 are respectively equipped with a first isolation control valve automatic control mechanism 7, a second isolation control valve automatic control mechanism 10, and a third isolation control valve automatic control mechanism 13. The self-starting temperature sensing module 4 is connected to the first isolation control valve automatic control mechanism 7, the second isolation control valve automatic control mechanism 10, and the third isolation control valve automatic control mechanism 13 through temperature / pressure transmission lines.

[0039] The natural circulation water tank 15 is located above the exhaust heat exchanger 1, and the small heat exchanger 23 and the large heat exchanger 24 are located above the natural circulation water tank 15 and the buffer water tank 17.

[0040] The opening of the first isolation control valve 6, the second isolation control valve 9, and the third isolation control valve 12 adopts two methods: active start and automatic start. The opening degree determines whether the residual discharge system is opened and the flow resistance of the corresponding pipeline.

[0041] The self-starting of the first isolation control valve 6, the second isolation control valve 9, and the third isolation control valve 12 can be achieved by various methods, including bimetallic differential expansion, pneumatic or hydraulic drive.

[0042] The self-starting power (temperature, pressure, etc.) is conducted through a temperature / pressure conduction line. In the temperature conduction mode, the temperature / pressure conduction line is a high thermal conductivity heat conductor (such as copper), which needs to be insulated from the external environment; in the pressure conduction mode, the temperature / pressure conduction line is a gas or liquid channel, which needs to be sealed from the external environment.

[0043] The signal transmitted by the temperature / pressure transmission line comes from the self-starting temperature sensing module 4.

[0044] The self-starting temperature sensing module 4 is mass-isolated from the reactor primary loop, but heat can be freely transferred.

[0045] The self-starting temperature sensing module 4 (temperature conduction mode) uses a high thermal conductivity material in contact with the primary coolant.

[0046] The self-starting temperature sensing module 4 (pressure transmission mode) uses a working fluid with good thermal expansion performance or low boiling point temperature.

[0047] The working principle of this invention is as follows:

[0048] When the residual exhaust system is not required, the first isolation control valve 6, the second isolation control valve 9, and the third isolation control valve 12 are all closed, thereby avoiding ineffective heat loss caused by the accidental activation of the residual exhaust system, which is detrimental to the reactor's economic efficiency.

[0049] When abnormal operating conditions or even accidents occur in the reactor, preventing the normal heat removal system from properly removing reactor heat, the residual heat removal system needs to be started and put into operation. In this invention, the residual heat removal system is started using a combination of active and automatic start-up. When critical primary loop status parameters such as the reactor outlet temperature become abnormal and exceed expected set values, the reactor control system may provide drive signals to the first isolation control valve 6, the second isolation control valve 9, and the third isolation control valve 12. These isolation control valves open under the power supply of the relevant power source, thereby starting the residual heat removal system.

[0050] When critical primary loop parameters such as reactor outlet temperature continue to deteriorate and reach a certain level, the first isolation control valve 6, the second isolation control valve 9, and the third isolation control valve 12 will also open under the drive of the automatic mechanical control system. The self-starting temperature sensing module 4 makes indirect thermal contact with the primary loop coolant (whose temperature is close to the reactor outlet temperature). This indirect thermal contact is to prevent the automatic mechanical control system of the residual exhaust system from becoming a primary loop boundary. When the primary loop temperature rises, the temperature sensing module in the self-starting temperature sensing module 4 will respond instantly to the temperature change, converting it into liquid level, gas pressure, and temperature, and mechanically transmitting the temperature / pressure changes from the sensing module to the automatic control mechanism of the control valves via temperature / pressure transmission lines. The automatic control mechanism of the control valves adjusts the opening of the residual exhaust system isolation control valves through differential expansion bimetallic strips or mechanical actuation (hydraulic or pneumatic drive).

[0051] After the first isolation control valve 6, the second isolation control valve 9, and the third isolation control valve 12 are opened, under the action of natural circulation driving force, the water in the natural circulation water tank 15 will flow into the secondary side of the residual discharge heat exchanger 1 along the residual discharge system water supply pipeline 14. Under the heating of the primary loop coolant 2, it will rapidly boil and vaporize, and then flow through the two heat dissipation heat exchangers in two paths along the steam pipeline 25. After cooling and condensation, it will enter the steam drum 19 along the residual discharge system heat dissipation section water supply pipeline. In the steam drum 19, the water and steam will automatically separate, and the water will remain in the buffer water tank 17. When the water level in the buffer water tank 17 rises to the upper limit of the isolation plate 18, the water that the buffer water tank 17 cannot hold will flow into the natural circulation water tank 15.

[0052] The self-regulating mechanism of the residual venting system is as follows: First, when the residual venting system is first put into operation, the temperature of the primary coolant 2 is very high, and the short-term strong cooling will not cause a solidification safety risk. When the residual venting system is first put into operation, the water volume in the natural circulation water tank 15 is large, its corresponding water level is also the highest, and the provided natural circulation drive head is also much larger. As the residual venting system continues to operate, a large amount of liquid water is heated into water vapor. The narrow-top, open-bottom structure of the natural circulation water tank 15 causes the water level in the natural circulation water tank to drop rapidly in the early stages, effectively preventing the residual venting capacity from remaining at a high level. The buffer water tank 17 initially contains the water generated after condensation from the residual venting system, ensuring that the presence of this water has no impact on the liquid level of the natural circulation water tank 15, thus helping to prevent the residual venting capacity from remaining in a strong state for a long time. Relatively speaking, the cross-sectional area of ​​the buffer water tank 17 is much larger than the upper cross-sectional area of ​​the natural circulation water tank 15, thus ensuring that more water vapor liquefies and preferentially falls into the buffer water tank 17. Later, when the buffer water tank 17 is full, even if excess water flows into the natural circulation water tank 15, the natural circulation water level will not be too high. Simultaneously, the narrow-at-the-top, open-at-the-bottom structure of the natural circulation water tank 15 ensures that its liquid level is not highly sensitive to changes in water volume, thus guaranteeing a high level of residual discharge capacity. The branch resistance characteristics of the large and small residual discharge heat exchangers are different (mainly determined by the opening degrees of the second isolation control valve 9 and the third isolation control valve 12). The resistance of the first feedwater line 20 is lower than that of the second feedwater line 21, ensuring that more steam flows out from the small residual discharge radiator branch under high steam flow conditions, thus moderately reducing the heat exchange capacity of the residual discharge system. Furthermore, the parallel arrangement of the large and small residual discharge heat exchangers increases the variety of combinations of parallel branch resistance and heat exchange capacity, providing more optimization variables for the later design of the residual discharge system capacity and improving the design scalability of the residual discharge system.

[0053] An isolation valve 16 is also installed between the natural circulation water tank 15 and the buffer water tank 17. When the excess discharge system stops operating, the valve can be opened by a corresponding control signal, thereby connecting the buffer water tank 17 and the natural circulation water tank 15, so that the two water levels reach the same height (communicating vessel principle), which serves to replenish the water in the natural circulation water tank 15.

[0054] While those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention, the embodiments should be considered illustrative and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and therefore all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0055] Furthermore, it should be understood that although the present invention is described according to embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A lead-based reactor self-starting self-regulating passive residual heat removal system, characterized in that, The system includes a residual heat exchanger (1), a reactor vessel (3), a residual heat sink (22) of the residual system, and a steam drum (19). The residual heat exchanger (1) is installed on the reactor vessel (3), with one end extending into the outside of the reactor vessel (3) and the other end immersed in the reactor coolant (2) inside the reactor vessel (3). The upper end of the residual heat exchanger (1) is connected to the residual heat sink (22) of the residual system through the residual steam pipeline (25). The residual heat sink (22) of the residual system is connected to the steam drum (19) through the feedwater pipeline. The bottom of the steam drum (19) is connected to the residual heat exchanger (1) through the residual feedwater pipeline (14), forming a loop.

2. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 1, wherein, The final heat sink (22) of the residual exhaust system is equipped with a small heat exchanger (23) and a large heat exchanger (24). The small heat exchanger (23) and the large heat exchanger (24) are arranged in parallel. The steam pipeline (25) of the residual exhaust system is connected to the small heat exchanger (23) and the large heat exchanger (24) respectively.

3. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 2, wherein, The water supply pipeline includes a first water supply pipeline (20) and a second water supply pipeline (21). The first water supply pipeline (20) is connected to a small heat exchanger (23), and the second water supply pipeline (21) is connected to a large heat exchanger (24).

4. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 3, wherein, The first water supply pipeline (20) is equipped with a second isolation control valve (9), the second water supply pipeline (21) is equipped with a third isolation control valve (12), and the residual discharge system water supply pipeline (14) is equipped with a first isolation control valve (6).

5. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 4, wherein, The steam drum (19) is provided with an L-shaped isolation plate (18) inside, which separates the natural circulation water drum (15) and the buffer water drum (17). The buffer water drum (17) and the natural circulation water drum (15) share a steam drum (19).

6. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 5, wherein, The natural circulation water bag (15) adopts a structure design that is narrow at the top and open at the bottom. The cross-sectional area of ​​the upper part of the natural circulation water bag (15) is much smaller than that of the buffer water bag (17).

7. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 6, wherein, The buffer water tank (17) is located inside the isolation plate (18), and the natural circulation water tank (15) is located outside the isolation plate (18). The natural circulation water tank (15) and the buffer water tank (17) are connected externally through the isolation valve (16).

8. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 7, wherein, The heat exchanger (1) is equipped with a self-starting temperature sensing module (4). The first isolation control valve (6), the second isolation control valve (9), and the third isolation control valve (12) are respectively equipped with a first isolation control valve automatic control mechanism (7), a second isolation control valve automatic control mechanism (10), and a third isolation control valve automatic control mechanism (13). The self-starting temperature sensing module (4) is connected to the first isolation control valve automatic control mechanism (7), the second isolation control valve automatic control mechanism (10), and the third isolation control valve automatic control mechanism (13) through temperature / pressure transmission lines.

9. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 8, wherein, The natural circulation water tank (15) is located above the exhaust heat exchanger (1), and the small heat exchanger (23) and the large heat exchanger (24) are located above the natural circulation water tank (15) and the buffer water tank (17).

10. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 9, wherein, The working fluid flowing from the final heat sink (22) of the residual discharge system first flows into the steam drum area directly above the buffer water tank (17) and then into the buffer water tank (17).

11. The lead-based reactor self-starting, self-regulating, passive residual heat removal system of claim 10, wherein, The opening of the first isolation control valve (6), the second isolation control valve (9), and the third isolation control valve (12) adopts two methods: active start and automatic start. The opening degree determines whether the residual discharge system is opened and the flow resistance of the corresponding pipeline.

12. The lead-based reactor self-starting and self-regulating passive residual discharge system according to claim 11, characterized in that, The first isolation control valve (6), the second isolation control valve (9), and the third isolation control valve (12) are self-started using a variety of methods, including bimetallic differential expansion, pneumatic or hydraulic drive.

13. The lead-based reactor self-starting and self-regulating passive residual discharge system according to claim 12, characterized in that, In temperature conduction mode, the temperature / pressure conduction line is a high thermal conductivity heat conductor, which needs to be insulated from the external environment; in pressure conduction mode, the temperature / pressure conduction line is a gas channel or liquid channel, which needs to be sealed from the external environment.

14. The lead-based reactor self-starting and self-regulating passive residual discharge system according to claim 13, characterized in that, The self-starting temperature sensing module (4) is mass-isolated from the reactor primary loop, but heat can be freely transferred.

15. The lead-based reactor self-starting and self-regulating passive residual discharge system according to claim 14, characterized in that, After the first isolation control valve (6), the second isolation control valve (9), and the third isolation control valve (12) are opened, under the action of the natural circulation driving force, the water in the natural circulation water tank (15) will flow into the secondary side of the residual heat exchanger (1) along the residual discharge system water supply pipeline (14). Under the heating of the primary loop coolant (2), it will quickly boil and vaporize, and then flow through the two heat dissipation heat exchangers in two paths along the steam pipeline (25). After cooling and condensation, it will enter the steam tank (19) along the residual discharge system heat dissipation section water supply pipeline. In the steam tank (19), the water and steam will automatically separate, and the water will remain in the buffer water tank (17). When the water level in the buffer water tank (17) rises to the upper limit of the isolation plate (18), the water that the buffer water tank (17) cannot hold will flow into the natural circulation water tank (15).

16. The lead-based reactor self-starting and self-regulating passive residual discharge system according to claim 15, characterized in that, The resistance of the first water supply pipeline (20) is less than that of the second water supply pipeline (21).

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