A sodium water post-accident pressure relief system and method

Abstract

The application provides a pressure relief system after a sodium water accident, mainly composed of three relief pipelines where three relief valves are located, a multi-stage discharge assembly and a cold sodium pool, which are respectively: a relief pipeline where a first relief valve is located, connecting a cold sodium pool at an outlet of an intermediate heat exchanger; a relief pipeline where a second relief valve is located, connecting the multi-stage discharge assembly at a lower cavity of a superheater; and a relief pipeline where a third relief valve is located, connecting the multi-stage discharge assembly at a lower cavity of an evaporator. Pressure and temperature detectors are respectively installed in the intermediate heat exchanger, the superheater and the evaporator, and the relief valves act after obtaining detection signals. The multi-stage discharge assembly comprises a plurality of multi-stage discharge tanks connected in series, and a pressure relief device is installed on an outlet pipeline of the multi-stage discharge tank. The intermediate heat exchanger is arranged in the cold sodium pool. The pressure relief system can reduce the probability of a secondary accident caused by the over-high pressure of the secondary loop due to the explosion of a non-active bursting disc or the explosion failure, and effectively prevent the equipment damage caused by the rapid increase of pressure and even more serious safety accidents.

Description

Technical Field

[0001] This invention belongs to the field of local accident protection technology for sodium-cooled fast reactors, specifically to a pressure relief system and method after a sodium-water accident. Background Technology

[0002] In a sodium-cooled fast reactor, a rupture in the heat transfer tubes of the steam generator can cause water or steam to rush into the liquid sodium, triggering a sodium-water reaction. This reaction is a highly exothermic chemical reaction that produces a large amount of hydrogen gas. The sodium-water reaction rapidly releases a large amount of heat energy, which cannot be immediately absorbed or dissipated by the system. Therefore, it accumulates rapidly in a localized area. When the pressure exceeds the system's tolerance limit, it can lead to an explosion, causing a severe sodium-water accident in the primary loop. Furthermore, during the pressure buildup in the localized area, heat energy also gradually accumulates, causing a sharp rise in temperature. Simultaneously, the sudden pressure increase propagates as a pressure wave to various critical systems in the secondary loop, causing a pressure rise in the secondary loop. In the secondary loop, the pressure peak occurs in the lower chamber of the intermediate heat exchanger, leading to the failure of the intermediate heat exchanger.

[0003] Currently, in order to ensure rapid pressure relief of the intermediate heat exchanger and protect the safety of the primary loop after a shutdown, passive rupture discs are often installed on equipment such as the intermediate heat exchanger. When the pressure exceeds the set value, the passive rupture disc will automatically rupture, quickly releasing the pressure and protecting the safety of the intermediate heat exchanger and the secondary loop. However, after the passive rupture disc ruptures, it will become ineffective, which will increase the probability of secondary accidents caused by untimely pressure relief in the secondary loop. Summary of the Invention

[0004] To address the problem that passive rupture discs in existing sodium-cooled fast reactor systems can fail, leading to secondary accidents due to untimely depressurization in the secondary circuit, this invention provides a depressurization system and method for sodium water accidents.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a pressure relief system after a sodium water accident, including a cold sodium tank, an intermediate heat exchanger installed in the cold sodium tank, the liquid sodium outlet of the intermediate heat exchanger being connected to the liquid sodium inlet of a superheater via a connecting pipe, the liquid sodium outlet of the superheater being connected to the liquid sodium inlet of an evaporator via a connecting pipe, and the liquid sodium outlet of the evaporator being connected to a liquid sodium treatment device via a connecting pipe.

[0007] The superheater and the evaporator are connected to a passage control component via pipelines. The passage control component is connected to a multi-stage emission component. The passage control component and the multi-stage emission component are connected to detectors via signal connections. The detectors are respectively installed in the intermediate heat exchanger, the superheater, and the evaporator.

[0008] The multi-stage emission assembly includes multi-stage emission tanks connected in series. One end of each multi-stage emission tank is connected to the pathway control assembly via a pipeline, and a pressure relief device is installed on the other end of each multi-stage emission tank.

[0009] Preferably, the multi-stage emission tank includes a primary emission tank, the inlet of which is connected to the passage control component via a pipeline, the outlet of which is connected to the inlet of a secondary emission tank via a pipeline, and the pressure relief component is installed on the outlet of the secondary emission tank.

[0010] Preferably, the pressure relief component is a rupture disc for a discharge tank.

[0011] Preferably, the passage control component includes a second vent valve and a third vent valve, one end of the second vent valve is connected to the vent pipe of the superheater via a pipeline, and the other end of the second vent valve is connected to the inlet of the primary discharge tank via a pipeline;

[0012] One end of the third vent valve is connected to the vent pipe of the evaporator via a pipeline, and the other end of the third vent valve is connected to the inlet of the primary discharge tank via a pipeline.

[0013] Preferably, the inlet of the primary discharge tank and the vent pipe of the superheater are connected by a pipeline to a superheater rupture disc.

[0014] Preferably, the inlet of the primary discharge tank is connected to the evaporator rupture disc via a pipeline.

[0015] Preferably, both the primary discharge tank and the secondary discharge tank are equipped with pressure gauges and level gauges.

[0016] Preferably, a first vent valve is connected to the connecting pipe between the liquid sodium outlet of the intermediate heat exchanger and the liquid sodium inlet of the superheater. The first vent valve is connected to the cold sodium tank, and the first vent valve signal is connected to the detector.

[0017] Preferably, the detector is connected to an alarm component, which includes an alarm light, an alarm processor, and a voice alarm. The alarm light and the voice alarm are signal-connected to the alarm processor, and the alarm processor is signal-connected to the detector.

[0018] This invention provides a method for relieving pressure after a sodium water accident, applied to the aforementioned pressure relief system, comprising the following steps:

[0019] Step 1: The detector will compare the real-time pressure data and real-time temperature data acquired in the intermediate heat exchanger, superheater and evaporator with the corresponding preset pressure data and preset temperature data, and generate a control signal based on the comparison results.

[0020] Step 2: The first venting valve opens the connection between the intermediate heat exchanger and the superheater and the cold sodium pool based on the control signal, thereby depressurizing the intermediate heat exchanger and discharging liquid sodium.

[0021] The second relief valve opens the pipeline between the superheater and the primary discharge tank based on the control signal, thereby depressurizing the superheater and discharging liquid sodium.

[0022] The third vent valve opens the pipeline between the evaporator and the primary discharge tank based on the control signal, thereby depressurizing the evaporator and discharging liquid sodium.

[0023] Step 3: Based on the pressure value and liquid sodium level detected in the primary discharge tank, the pressure gauge and level gauge cause the primary discharge tank to depressurize into the secondary discharge tank and discharge liquid sodium; the evaporator rupture disc on the secondary discharge tank opens to release a mixture of hydrogen and argon into the air to depressurize the system after the sodium-cooled fast reactor sodium-water reaction accident.

[0024] Compared with the prior art, the present invention has the following beneficial technical effects:

[0025] This invention provides a pressure relief system after a sodium-water accident. The system utilizes a series layout of a cold sodium tank, an intermediate heat exchanger, a superheater, an evaporator, and liquid sodium treatment equipment to effectively cool and circulate high-temperature liquid sodium. This effectively addresses the extreme high temperatures and sudden pressure increases that may occur during a sodium-water reaction. Within the system, detectors monitor key parameters such as temperature and pressure in the intermediate heat exchanger, superheater, and evaporator in real time. If an anomaly is detected, such as excessive temperature or a sharp rise in pressure, the flow control component will respond rapidly, automatically adjusting the fluid flow direction and guiding the high-temperature, high-pressure liquid sodium to the multi-stage discharge assembly. This improves the stability of pressure relief after a sodium-water reaction accident in a sodium-cooled fast reactor. The multi-stage discharge assembly uses series-connected multi-stage discharge tanks to progressively reduce the pressure and temperature of the liquid sodium, ensuring that the discharge process does not harm the external environment and quickly releasing pressure. This effectively prevents equipment damage or more serious safety accidents that could result from system overpressure. This system can rapidly activate the multi-stage discharge mechanism when an anomaly is detected in the intermediate heat exchanger, superheater, or evaporator, releasing pressure step by step, effectively preventing equipment damage or more serious safety accidents caused by pressure surges. Meanwhile, the ingenious layout of the cold sodium pool and heat exchange system ensures continuous circulation and heat exchange of the sodium solution, maintaining stable system operation. The entire system responds quickly and controls precisely, providing a safer and more reliable guarantee for industrial fields such as nuclear energy.

[0026] Furthermore, the multi-stage discharge tanks in this system adopt a series layout of primary and secondary discharge tanks. The primary discharge tank serves as an initial pressure reduction stage, effectively mitigating the impact of high-temperature and high-pressure liquid sodium. Subsequently, the outlet of the primary discharge tank is connected to the inlet of the secondary discharge tank through pipelines, achieving further pressure reduction and gradual temperature cooling. This not only improves the stability and reliability of the system but also enables efficient and safe handling of high-temperature liquid sodium, enhancing the system's safety and efficiency.

[0027] Furthermore, this system uses rupture discs for discharge tanks as pressure relief components for multi-stage discharge tanks, which can quickly respond to overpressure, enhance system safety, and effectively prevent accidents from escalating.

[0028] Furthermore, the second and third vent valves in this system precisely regulate the fluid path from the superheater and evaporator to the primary discharge tank, ensuring that high-temperature, high-pressure liquid sodium can be rapidly and orderly transferred to the safe treatment stage in emergencies. The addition of superheater and evaporator rupture discs between the inlet of the primary discharge tank and the vent pipes of the superheater and evaporator significantly enhances the system's safety protection capabilities. As pre-pressure relief devices, the superheater and evaporator rupture discs can respond in advance before the system pressure reaches a preset threshold, releasing pressure through instantaneous rupture. This effectively prevents equipment damage or more serious accidents that may result from continuously rising pressure, reducing the processing pressure on subsequent discharge tanks and improving the overall system's stability and safety. This pressure relief system achieves efficient and safe treatment of high-temperature liquid sodium, effectively addressing the challenges posed by sodium-water accidents. The synergistic effect of the various discharge tanks and rupture discs ensures a gradual reduction in pressure and temperature until safe discharge standards are met. This not only improves the system's automation and intelligence level but also provides strong support for the sustainable development of nuclear energy and related industries.

[0029] Furthermore, pressure gauges and level gauges are installed in both the primary and secondary discharge tanks of this system. By monitoring the changes in pressure and level inside the tanks in real time, operators can accurately grasp the working status of the discharge tanks and take corresponding measures to deal with abnormal situations in a timely manner. This not only enhances the safety and stability of the system, but also facilitates the safe and efficient treatment of high-temperature liquid sodium, greatly improving the system's monitoring capabilities and operating efficiency.

[0030] Furthermore, a first vent valve is added to the connecting pipeline between the liquid sodium outlet of the intermediate heat exchanger and the liquid sodium inlet of the superheater in this system, and is directly connected to the cold sodium pool. At the same time, the valve signal is connected to the detector, which enhances the emergency response capability and flexibility of the system. When the detector detects abnormal pressure or temperature in the intermediate heat exchanger or subsequent pipelines, the first vent valve can respond quickly, automatically open, and safely guide the high-temperature liquid sodium back to the cold sodium pool for cooling treatment. This not only effectively avoids further damage to the system by high-temperature and high-pressure liquid sodium, but also ensures the continuity and stability of the entire treatment process.

[0031] This invention provides a depressurization method after a sodium-water accident. This method integrates intelligent detection, precise control, and multi-stage discharge technology to achieve rapid and effective handling of high-temperature, high-pressure liquid sodium in a sodium-cooled fast reactor system. First, the method uses detectors to monitor the pressure and temperature in the intermediate heat exchanger, superheater, and evaporator in real time. Upon detecting an anomaly, a control signal is immediately generated, rapidly activating the first, second, and third vent valves to guide the high-temperature liquid sodium to the cold sodium pool and multi-stage discharge tanks for cooling and depressurization. Subsequently, precise monitoring by pressure gauges and level gauges ensures that the pressure and liquid level in the first-stage discharge tank remain within safe ranges, and the system is transferred to the second-stage discharge tank as needed. Finally, a mixture of hydrogen and argon is safely released through the evaporator rupture discs, achieving comprehensive system depressurization. This method not only improves emergency response speed but also enhances processing efficiency and safety, providing a solid guarantee for the safe operation of the sodium-cooled fast reactor. Attached Figure Description

[0032] Figure 1 This invention provides a connection diagram of a pressure relief system after a sodium water accident;

[0033] In the attached diagram: 1. Cold sodium tank; 2. Intermediate heat exchanger; 3. First vent valve; 4. Superheater; 5. Superheater rupture disc; 6. Second vent valve; 7. Evaporator; 8. Evaporator rupture disc; 9. Third vent valve; 10. Primary discharge tank; 11. Secondary discharge tank; 12. Discharge tank rupture disc. Detailed Implementation

[0034] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this 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. Therefore, they should not be construed as limitations on this invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

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

[0038] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0039] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0040] See Figure 1 This invention proposes a pressure relief system after a sodium water accident. The system includes a cold sodium tank 1, in which multiple intermediate heat exchangers 2 are installed. The liquid sodium outlet of each intermediate heat exchanger 2 is connected to the liquid sodium inlet of a superheater 4 via a connecting pipe. The liquid sodium outlet of the superheater 4 is connected to the liquid sodium inlet of an evaporator 7 via a connecting pipe. The liquid sodium outlet of the evaporator 7 is connected to a liquid sodium treatment component.

[0041] In this system, a first vent valve 3 is connected to one end of the connecting pipe between the liquid sodium outlet of the intermediate heat exchanger 2 and the liquid sodium inlet of the superheater 4. The other end of the first vent valve 3 is connected to the cold sodium pool 1. The first vent valve 3 is connected to a detector, which is installed in the intermediate heat exchanger 2, the superheater 4, and the evaporator 7. When the detector detects a pressure rise in the intermediate heat exchanger 2 and a sodium-water reaction occurring in the superheater 4 or the evaporator 7, causing a sharp increase in pressure and abnormal temperature, the detector sends a signal to the first vent valve 3, causing it to open and rapidly transfer the liquid sodium from the intermediate heat exchanger 2 to the superheater 4 to the cold sodium pool 1. This prevents the superheater 4 from overpressure, overheating, or even exploding, thus protecting the superheater 4 and the safety of the operators. When the intermediate heat exchanger 2 or the superheater 4 malfunctions, the first vent valve 3 acts as an isolation point, isolating the faulty part from the rest of the system to reduce the impact of the fault on the overall system operation.

[0042] One end of the second vent valve 6 is connected to the vent pipe on the superheater 4. The other end of the second vent valve 6 is connected to a multi-stage discharge assembly via a pipeline. The signal of the second vent valve 6 is also connected to a detector. When the detector detects a sharp increase in pressure or abnormal temperature inside the superheater 4 or evaporator 7, the signal controls the second vent valve 6 to open, transporting the liquid sodium in the superheater 4 to the multi-stage discharge assembly. This prevents the superheater 4 from overpressure, overheating, or even exploding due to the rupture of the heat transfer tubes of the superheater 4 or evaporator 7 after the sodium-water reaction occurs, thus improving the safety of the system.

[0043] The port of the vent pipe on the superheater 4 is also connected to one end of the superheater rupture disc 5 via a pipeline. The other end of the superheater rupture disc 5 is also connected to the multi-stage discharge assembly. The superheater rupture disc 5 and the second vent pipe valve 6 form two discharge paths in the vent pipe of the superheater 4 and the multi-stage discharge assembly. When the heat transfer tube of the superheater 4 or the evaporator 7 ruptures, causing a sodium-water reaction, the pressure and temperature in the superheater 4 rise sharply. The superheater rupture disc 5 is used to depressurize, cool down, and discharge sodium from the superheater 4, further protecting the superheater 4 and improving the safety of the superheater 4 after a sodium-water reaction accident.

[0044] The port of the vent pipe on the evaporator 7 is connected to one end of the port of the third vent valve 9 via a pipeline. The other end of the third vent valve 9 is also connected to the multi-stage discharge assembly via a pipeline. The third vent valve 9 is connected to a detector. When the detector detects a sharp increase in pressure or abnormal temperature in the intermediate heat exchanger 2, superheater 4, and evaporator 7, it controls the third vent valve 9 to open, transporting the liquid sodium in the evaporator 7 to the multi-stage discharge assembly. This prevents the pressure from rising in the superheater 4 or intermediate heat exchanger 2 due to the rupture of the heat transfer tubes of the superheater 4 or evaporator 7, which could lead to a sodium-water reaction and the resulting pressure wave being transmitted to the evaporator 7, causing overpressure, overheating, or even explosion in the evaporator 7, thus improving the safety of the system.

[0045] The port of the vent pipe on the evaporator 7 is also connected to one end of the evaporator rupture disc 8 via a pipeline. The other end of the evaporator rupture disc 8 is also connected to the multi-stage discharge assembly. The evaporator rupture disc 8 and the third vent pipe valve 9 form two discharge paths in the vent pipe of the evaporator 7 and the multi-stage discharge assembly. When the heat transfer tube of the superheater 4 or the evaporator 7 ruptures, causing a sodium-water reaction, the pressure and temperature in the evaporator 7 rise sharply. The evaporator rupture disc 8 is used to depressurize, cool down, and discharge sodium from the superheater 4, further protecting the evaporator 7 and improving the safety of the evaporator 7 after a sodium-water reaction accident.

[0046] The multi-stage emission assembly includes a multi-stage emission tank, comprising a primary emission tank 10. The inlet of the primary emission tank 10 is connected via piping to a superheater rupture disc 5, a second vent valve 6, an evaporator rupture disc 8, and a third vent valve 9. The outlet of the primary emission tank 10 is connected via piping to the inlet of a secondary emission tank 11, and the outlet of the secondary emission tank 11 is connected to an emission tank rupture disc 12. The multi-stage emission tank system allows for step-by-step pressure release under different pressure or fault conditions, preventing damage to the emission tanks or personal injury that could result from sudden pressure release. Each emission tank acts as a buffer for the preceding stage, ensuring a smooth and orderly emission process.

[0047] Each discharge tank of the multi-stage emission assembly is equipped with a pressure gauge and a level gauge. The pressure gauge and level gauge are used to monitor the pressure and liquid sodium level in the discharge tank. If the pressure value in the first-stage discharge tank 10 reaches the preset pressure value or the liquid sodium level exceeds the preset liquid sodium level, the first-stage discharge tank 10 will supply liquid sodium to the second-stage discharge tank 11 or depressurize it. The second-stage discharge tank 11 will release a mixture of hydrogen and argon gas into the air through the discharge tank rupture disc 12 to prevent the multi-stage emission assembly from exploding.

[0048] The detector is equipped with an alarm component, which includes an alarm light, an alarm processor, and a voice alarm. The alarm light and the voice alarm are connected to the alarm processor, and the alarm processor is connected to the detector. The alarm light and the voice alarm are used to alert the staff.

[0049] This invention proposes a method for depressurizing after a sodium water accident, which includes the following steps:

[0050] Step 1: The detector acquires real-time pressure data and real-time temperature data in the intermediate heat exchanger, superheater and evaporator. The acquired real-time pressure data is compared with the preset pressure data and the real-time temperature data is compared with the preset temperature data. If the real-time pressure data exceeds the preset pressure data or the real-time temperature data exceeds the preset temperature data, it is determined that the system has undergone a sodium-water reaction and a control signal is generated.

[0051] Step 2: After receiving the control signal, the first venting pipe valve opens, connecting the liquid sodium outlet of the intermediate heat exchanger and the liquid sodium inlet of the superheater to the cold sodium pool, and discharging the liquid sodium from the intermediate heat exchanger to the superheater into the cold sodium pool.

[0052] After receiving the control signal, the second vent valve opens, connecting the pipeline between the vent pipe on the superheater and the inlet of the first-stage discharge tank, and transporting the liquid sodium and pressure in the superheater to the first-stage discharge tank.

[0053] After receiving the control signal, the third vent valve opens, connecting the pipeline between the vent pipe on the evaporator and the inlet of the primary discharge tank, and transporting the liquid sodium and pressure in the evaporator to the primary discharge tank.

[0054] Step 3: The pressure gauge detects the pressure value in the primary discharge tank, and the liquid level gauge detects the liquid sodium level in the primary discharge tank. If the pressure value reaches the preset pressure value or the liquid sodium level exceeds the preset liquid sodium level, the primary discharge tank depressurizes into the secondary discharge tank and discharges liquid sodium. The evaporator rupture disc on the secondary discharge tank opens to release a mixture of hydrogen and argon into the air to depressurize the system after the sodium-cooled fast reactor sodium-water reaction accident.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0056] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A pressure relief system after a sodium water accident, characterized in that, Includes a cold sodium pool (1), in which an intermediate heat exchanger (2) is installed. The liquid sodium outlet of the intermediate heat exchanger (2) is connected to the liquid sodium inlet of the superheater (4) through a connecting pipe. The liquid sodium outlet of the superheater (4) is connected to the liquid sodium inlet of the evaporator (7) through a connecting pipe. The liquid sodium outlet of the evaporator (7) is connected to a liquid sodium processing device through a connecting pipe. The superheater (4) and the evaporator (7) are connected to a passage control component via pipelines. The passage control component is connected to a multi-stage emission component. The passage control component and the multi-stage emission component are connected to a detector. The detectors are respectively installed in the intermediate heat exchanger (2), the superheater (4) and the evaporator (7). The multi-stage emission assembly includes multi-stage emission tanks connected in series. One end of each multi-stage emission tank is connected to the pathway control assembly via a pipeline. A pressure relief device is installed on the other end of each multi-stage emission tank. The passage control component includes a second vent valve (6) and a third vent valve (9). One end of the second vent valve (6) is connected to the vent pipe of the superheater (4) via a pipeline, and the other end of the second vent valve (6) is connected to the inlet of the primary discharge tank (10) via a pipeline. One end of the third vent valve (9) is connected to the vent pipe of the evaporator (7) through a pipeline, and the other end of the third vent valve (9) is connected to the inlet of the primary discharge tank (10) through a pipeline. The inlet of the primary discharge tank (10) and the vent pipe of the superheater (4) are connected by a pipeline to a superheater rupture disc (5). The inlet of the primary discharge tank (10) and the discharge pipe of the evaporator (7) are connected by a pipeline to an evaporator rupture disc (8). A first vent valve (3) is connected to the connecting pipe between the liquid sodium outlet of the intermediate heat exchanger (2) and the liquid sodium inlet of the superheater (4). The first vent valve (3) is connected to the cold sodium pool (1), and the first vent valve (3) is signal-connected to the detector.

2. The pressure relief system after a sodium water accident according to claim 1, characterized in that, The multi-stage emission tank includes a primary emission tank (10), the inlet of which is connected to the passage control component via a pipeline, and the outlet of the primary emission tank (10) is connected to the inlet of a secondary emission tank (11) via a pipeline, and the pressure relief component is installed on the outlet of the secondary emission tank (11).

3. The pressure relief system after a sodium water accident according to claim 2, characterized in that, The pressure relief component is a rupture disc (12) for the discharge tank.

4. A pressure relief system after a sodium water accident according to claim 2, characterized in that, Both the primary discharge tank (10) and the secondary discharge tank (11) are equipped with pressure gauges and level gauges.

5. A method for relieving pressure after a sodium water accident, applied to the pressure relief system described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: The detector will compare the real-time pressure data and real-time temperature data acquired in the intermediate heat exchanger, superheater and evaporator with the corresponding preset pressure data and preset temperature data, and generate a control signal based on the comparison results. Step 2: The first venting valve opens the connection between the intermediate heat exchanger and the superheater and the cold sodium pool based on the control signal, thereby depressurizing the intermediate heat exchanger and discharging liquid sodium. The second relief valve opens the pipeline between the superheater and the primary discharge tank based on the control signal, thereby depressurizing the superheater and discharging liquid sodium. The third vent valve opens the pipeline between the evaporator and the primary discharge tank based on the control signal, thereby depressurizing the evaporator and discharging liquid sodium. Step 3: Based on the pressure value and liquid sodium level detected in the primary discharge tank, the pressure gauge and level gauge cause the primary discharge tank to depressurize into the secondary discharge tank and discharge liquid sodium; the evaporator rupture disc on the secondary discharge tank opens to release a mixture of hydrogen and argon into the air to depressurize the system after the sodium-cooled fast reactor sodium-water reaction accident.

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