Integrated reactor safety system and control method therefor

Abstract

The present invention provides an integrated reactor safety system and a control method therefor. The system comprises an integrated reactor pressure vessel and a containment building. The integrated reactor pressure vessel is arranged in the containment building, and a primary and secondary side heat exchanger is arranged in the integrated reactor pressure vessel, a secondary side inlet of the primary and secondary side heat exchanger is connected to secondary side water supply piping, and a secondary side outlet of the primary and secondary side heat exchanger is connected to secondary side outlet piping; a passive residual heat discharge heat exchanger is arranged on an outer side of the containment building; an outlet of the passive residual heat discharge heat exchanger is connected to the secondary side water supply piping by means of residual heat discharge outlet piping, and an inlet of the passive residual heat discharge heat exchanger is connected to the secondary side outlet piping by means of a residual heat discharge inlet piping. The present invention meets design-basis accident mitigation requirements for reactors, ensures reactor safety, simplifies the equipment to the maximum extent, improves arrangement space utilization, and is more economical.

Description

Integrated reactor safety system and control method thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311221353.X, filed on September 20, 2023, entitled “An integrated reactor safety system and method,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of nuclear reactor safety systems, and in particular to an integrated reactor safety system and method. Background Art

[0004] Integrated pressurized water reactors (PWRs) feature small size, compact structure, and high system integration. They can be used for specialized applications such as marine development and industrial production, meeting diverse needs for power, heating, and steam supply. PWRs place high demands on system simplicity, efficient layout space utilization, safety, and cost-effectiveness.

[0005] Under normal operating conditions, heat from the reactor core is transferred through primary heat exchangers such as steam generators to the steam turbine, generating electricity, or to the heat / steam supply system to generate heat or steam. However, in the event of a non-LOCA accident (no breach of the reactor pressure vessel pressure boundary, such as a loss of normal feedwater), the steam generators and other primary heat exchangers become unavailable, rendering the residual heat from the core impossible to remove through normal means. In the event of a LOCA accident (a breach of the reactor pressure vessel pressure boundary), the reactor loses a significant amount of water, potentially deteriorating the exposed core heat transfer. Furthermore, the containment vessel may continue to pressurize after the accident, leading to overpressure failure and consequently damage to the radioactive barrier. Therefore, a dedicated safety system is essential to promptly remove the residual heat from the core and replenish the lost water to prevent the accident from escalating into a serious core failure and to prevent overpressure failure of the containment vessel, resulting in a significant radioactive release.

[0006] Traditional dedicated safety systems for pressurized water reactors generally include active residual heat removal systems, active high-pressure, medium-pressure, and low-pressure safety injection systems, and active containment spray systems. However, existing dedicated safety system design and configuration schemes have the following problems: 1) they require the coordinated operation of multiple systems and equipment, resulting in complex system configuration and a long accident mitigation path. Failure of a system or equipment could affect the entire accident mitigation process, necessitating the deployment of a large number of redundant equipment. 2) most of them are active systems that rely on external power and require support systems such as equipment cooling water. If external power or support systems are lost, the active dedicated safety systems will be unable to perform their functions. 3) the systems, equipment, and related support systems are complex, requiring a large amount of space for layout and occupying a large amount of free space within the containment, making operation and maintenance difficult. 4) in the later stages of an accident, once the cooling water source is exhausted, additional recirculation pumps (or low-pressure injection pumps) are required to pump water from the containment pit into the reactor pressure vessel. This cooling process requires additional equipment to maintain reliability, and post-accident recovery also requires the removal of radioactivity from the pit. Therefore, the existing technology's dedicated safety system design and configuration scheme cannot be applied to the special requirements of the integrated reactor dedicated safety system, such as simplification, small layout space, high safety and economic requirements.

[0007] Summary of the Invention

[0008] In response to the shortcomings of the existing technology, the present invention provides an integrated reactor safety system and method to meet the needs of mitigating reactor design basis accidents (LOCA and non-LOCA accidents), ensure reactor safety, simplify equipment to the greatest extent, improve layout space utilization, and enhance economic efficiency.

[0009] A first aspect of the present invention provides an integrated reactor safety system, comprising:

[0010] containment;

[0011] an integrated reactor pressure vessel, which is disposed within the containment vessel, wherein a reactor core and a built-in pressurizer are disposed within the integrated reactor pressure vessel, wherein the reactor core is disposed at the lower portion of the integrated reactor pressure vessel, and the built-in pressurizer is disposed at the top portion of the integrated reactor pressure vessel;

[0012] A primary and secondary side heat exchanger is disposed inside the integrated reactor pressure vessel, wherein the secondary side inlet of the primary and secondary side heat exchanger is connected to the secondary side water feed pipeline, and the secondary side outlet of the primary and secondary side heat exchanger is connected to the secondary side outlet pipeline;

[0013] a passive waste heat removal heat exchanger, which is arranged outside the containment, wherein the outlet of the passive waste heat removal heat exchanger is connected to the secondary side water supply pipeline via a waste heat outlet pipeline, and the inlet of the non-kinetic waste heat removal heat exchanger is connected to the secondary side outlet pipeline via a waste heat inlet pipeline;

[0014] Among them, an upper chamber is arranged between the built-in pressurizer and the reactor core, and the in-core components and the control rod drive mechanism are arranged in the upper chamber; an upper chamber water flow hole is opened on the side wall of the upper chamber, the primary and secondary side heat exchanger is located outside the upper chamber, and the upper chamber water flow hole is located above the primary and secondary side heat exchanger.

[0015] Preferably, a pressure relief valve is provided on the top of the integrated reactor pressure vessel, and the top of the built-in pressurizer is connected to the pressure relief valve.

[0016] Preferably, a secondary water supply line isolation valve is provided on the secondary water supply line, and a secondary outlet line isolation valve is provided on the secondary outlet line.

[0017] Preferably, one end of the excess discharge outlet pipeline is connected between the secondary water supply pipeline isolation valve and the secondary side inlet of the primary and secondary side heat exchanger, and one end of the excess discharge inlet pipeline is connected between the secondary side outlet pipeline isolation valve and the secondary side outlet of the primary and secondary side heat exchanger.

[0018] Preferably, a pressure accumulator and injection tank is also provided in the containment shell, which is connected to the integrated reactor pressure vessel through an injection pipeline. The pressure accumulator and injection tank is filled with coolant, and the injection pipeline is provided with an injection pipeline check valve and an injection pipeline isolation valve. The injection pipeline isolation valve is connected in parallel with the bypass pipeline.

[0019] Preferably, the passive residual heat removal heat exchanger is placed in an external heat sink outside the containment vessel.

[0020] Preferably, the external heat sink is provided with an external heat sink cooling arrangement.

[0021] Preferably, a containment suppression pool is provided inside the containment. The containment suppression pool is a sealed tank filled with coolant. The top of the containment suppression pool is connected to the containment space through a suppression pool inlet pipeline.

[0022] Preferably, a suppression pool bubbler is provided inside the containment suppression pool. The suppression pool bubbler is located below the coolant liquid level in the containment suppression pool and is connected to the end of the suppression pool inlet pipeline.

[0023] A second aspect of the present invention provides a method for controlling an integrated reactor safety system, wherein the integrated reactor safety system according to the first aspect of the present invention is used to perform safety control on the integrated reactor, the method comprising the following steps:

[0024] When a non-LOCA accident occurs, close the secondary side water supply pipeline isolation valve and the secondary side outlet pipeline isolation valve;

[0025] Open the isolating valve of the waste heat discharge inlet pipeline and confirm that the isolating valve of the waste heat discharge outlet pipeline is normally open. At this time, the primary and secondary side heat exchangers and the passive waste heat discharge heat exchanger rely on natural circulation to form a closed circulation loop, bringing the heat of the reactor core to the external heat sink.

[0026] Preferably, the control method of the integrated reactor safety system further includes the following steps:

[0027] When a LOCA accident occurs, close the isolation valve of the secondary water supply pipeline and the isolation valve of the secondary outlet pipeline;

[0028] Open the exhaust inlet pipeline isolation valve and confirm that the exhaust outlet pipeline isolation valve is always open to continuously remove the reactor core heat to the external heat sink;

[0029] When the pressure of the integrated reactor pressure vessel drops to the opening pressure of the pressure relief valve, the pressure relief valve is triggered to open, so that the pressure of the integrated reactor pressure vessel drops to the initial pressure accumulation pressure of the pressure accumulation and injection tank;

[0030] The pressurized nitrogen in the pressure accumulator injection tank pushes the internal coolant, enters the integrated reactor pressure vessel through the injection pipeline to replenish the lost water, and through the configuration of the valves and bypass lines on the injection pipeline, different injection flow rates before and after injection are achieved, ensuring that the water level in the integrated reactor pressure vessel is always higher than the upper chamber water flow hole during the entire accident process, ensuring that natural circulation can always be established between the reactor core and the primary and secondary side heat exchangers, thereby using the primary and secondary side heat exchangers to remove the heat of the reactor core for a long time.

[0031] Preferably, the control method of the integrated reactor safety system further includes the following steps:

[0032] When the containment pressure is high, high-temperature and high-pressure steam is passively sucked into the containment suppression pool from the suppression pool inlet pipeline and condensed, thereby ensuring that the pressure inside the containment does not exceed the limit.

[0033] The integrated reactor safety system and control method of the present invention can cope with various design basis accidents (LOCA and non-LOCA accidents), continuously remove reactor heat, maintain reactor cooling, and eliminate high-pressure and low-pressure injection, as well as active dedicated safety systems and equipment in traditional reactor safety systems. This greatly simplifies the equipment, allows for flexible layout, and requires minimal space. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application.

[0035] FIG1 is a schematic diagram of an integrated reactor safety system according to a specific embodiment of the present invention.

[0036] FIG2 is a flow chart of a control method of an integrated reactor safety system according to a specific embodiment of the present invention.

[0037] Reference numerals:

[0038] 100-Integrated Reactor Safety System;

[0039] 10-Integrated reactor pressure vessel;

[0040] 11- Reactor core;

[0041] 12-Built-in voltage regulator;

[0042] 13- Reactor internals and control rod drive mechanism;

[0043] 14- water flow hole in the upper chamber;

[0044] 15-pressure relief valve;

[0045] 16-upper chamber;

[0046] 20-primary and secondary side heat exchanger;

[0047] 21-Secondary side water supply pipeline;

[0048] 22-secondary side outlet pipeline;

[0049] 23-Secondary side water supply line isolation valve;

[0050] 24-Secondary side outlet pipeline isolation valve;

[0051] 30-pressure storage and injection box;

[0052] 31-Injection line check valve;

[0053] 32-An injection pipeline;

[0054] 33-Injection line isolation valve;

[0055] 34-Bypass line;

[0056] 40- passive waste heat removal heat exchanger;

[0057] 41-exhaust outlet pipeline;

[0058] 42-residue discharge inlet pipeline;

[0059] 43-excess discharge outlet pipeline isolation valve;

[0060] 44-exhaust inlet pipeline isolation valve;

[0061] 50-containment suppression pool;

[0062] 51-suppression tank inlet pipeline;

[0063] 52-suppression cell bubbler;

[0064] 53-suppression cell housing;

[0065] 60-containment;

[0066] 70 - external heat sink;

[0067] 71-External heat sink cooling device. DETAILED DESCRIPTION

[0068] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0069] FIG1 is a schematic diagram of an integrated reactor safety system according to a specific embodiment of the present invention.

[0070] As shown in FIG1 , the integrated reactor safety system 100 provided in this embodiment includes: a containment vessel 60 , an integrated reactor pressure vessel 10 , primary and secondary side heat exchangers 20 , and a passive residual heat removal heat exchanger 40 .

[0071] The integrated reactor pressure vessel 10 is arranged in the containment vessel 60. A reactor core 11 and a built-in pressurizer 12 are arranged in the integrated reactor pressure vessel 10. The reactor core 11 is arranged at the lower part of the integrated reactor pressure vessel 10, and the built-in pressurizer 12 is arranged at the top of the integrated reactor pressure vessel 10.

[0072] The primary and secondary side heat exchangers 20 are arranged inside the integrated reactor pressure vessel 10 , the secondary side inlets of the primary and secondary side heat exchangers 20 are connected to the secondary side water supply pipeline 21 , and the secondary side outlets of the primary and secondary side heat exchangers 20 are connected to the secondary side outlet pipeline 22 .

[0073] The passive waste heat removal heat exchanger 40 is arranged outside the containment shell 60, and the outlet of the passive waste heat removal heat exchanger 40 is connected to the secondary side water supply pipeline 21 through the waste heat removal outlet pipeline 41, and the inlet of the non-kinetic waste heat removal heat exchanger 40 is connected to the secondary side outlet pipeline 22 through the waste heat removal inlet pipeline 42.

[0074] Multiple primary and secondary heat exchangers 20 are configured. Two or more independent passive heat removal systems are configured for the passive waste heat removal heat exchanger 40, each connected to one or more primary and secondary heat exchangers 20. The passive waste heat removal heat exchanger 40 can be a bundled tube type, with a higher elevation than the primary and secondary heat exchangers 20.

[0075] An upper chamber 16 is arranged between the built-in pressurizer 12 and the reactor core 11, and the upper chamber 16 contains the in-core components and the control rod drive mechanism 13; an upper chamber water flow hole 14 is opened on the side wall of the upper chamber 16, and the primary and secondary side heat exchanger 20 is located outside the upper chamber 16, and the upper chamber water flow hole 14 is located above the primary and secondary side heat exchanger 20.

[0076] During normal reactor operation, the primary coolant is heated by the reactor core 11, passes through the internals of the upper chamber 16 and the control rod drive mechanism 13, and then flows through the upper chamber water holes 14. After heat exchange in the primary and secondary heat exchangers 20, the coolant returns to the reactor core 11, completing the cycle. The secondary coolant enters the primary and secondary heat exchangers 20 through the secondary feedwater line 21, removes heat from the primary side, and then flows out through the secondary outlet line 22.

[0077] The integrated reactor pressure vessel 10 may be provided with a primary side coolant pump to perform forced circulation on the primary side; or may not be provided with a primary side coolant pump and adopt natural circulation to circulate the primary side coolant.

[0078] The integrated reactor safety system 100 of this embodiment can cope with various design basis accidents (LOCA and non-LOCA accidents), continuously remove reactor heat, maintain reactor cooling, eliminate high-pressure and low-pressure injection, and active dedicated safety systems and equipment in traditional reactor safety systems, simplify equipment to the greatest extent, and have flexible layout and small space requirements.

[0079] In one embodiment, a pressure relief valve 15 is provided at the top of the integrated reactor pressure vessel 10. The top of the built-in pressurizer 12 is connected to the pressure relief valve 15. When the pressure of the integrated reactor pressure vessel 10 needs to be reduced, the pressure can be released into the containment vessel 60 through the pressure relief valve 15. The pressure relief valve 15 can be configured in a manner of multiple parallel connections and multiple stages of separate openings, with two or more independent series.

[0080] The secondary inlet of the primary and secondary heat exchanger 20 is connected to a secondary water supply line 21, and the secondary outlet of the primary and secondary heat exchanger 20 is connected to a secondary outlet line 22. A secondary water supply line isolation valve 23 is installed on the secondary water supply line 21, and a secondary outlet line isolation valve 24 is installed on the secondary outlet line 22. During normal reactor operation, secondary fluid enters the primary and secondary heat exchanger 20 from the secondary water supply line 21, removes primary heat, and then flows out of the primary and secondary heat exchanger 20 from the secondary outlet line 22. The fluid at the secondary outlet of the primary and secondary heat exchanger 20 is in the form of steam or liquid water.

[0081] A passive residual heat removal heat exchanger 40 is provided on the outside of the containment vessel 60, and is equipped with two or more independent passive residual heat removal series, each of which is respectively connected to one or a group of primary and secondary side heat exchangers 20. The outlet of the passive residual heat removal heat exchanger 40 is connected to the residual heat outlet pipeline 41, and its inlet is connected to the residual heat inlet pipeline 42. A residual heat outlet pipeline isolation valve 43 is provided on the residual heat outlet pipeline 41, and the residual heat outlet pipeline isolation valve 43 is a normally open valve. A residual heat inlet pipeline isolation valve 44 is provided on the residual heat inlet pipeline 42, and the residual heat inlet pipeline isolation valve 44 is a normally closed valve. After an accident occurs, if the valve actuation system (such as the power supply or pneumatic system) fails, the residual heat inlet pipeline isolation valve 44 will perform the opening action. The excess discharge outlet pipeline 41 is connected to the secondary water supply pipeline 21, and the connection point is located between the secondary water supply pipeline isolation valve 23 and the secondary side inlet of the primary and secondary side heat exchanger 20; the excess discharge inlet pipeline 42 is connected to the secondary side outlet pipeline 22, and the connection point is located between the secondary side outlet pipeline isolation valve 24 and the secondary side outlet of the primary and secondary side heat exchanger 20.

[0082] When the passive waste heat removal heat exchanger 40 needs to be put into operation after an accident, a closed circulation loop can be formed between the secondary side heat exchanger 20 and the passive waste heat removal heat exchanger 40 by closing the secondary side water supply pipeline isolation valve 23 and the secondary side outlet pipeline isolation valve 24 and opening the waste heat inlet pipeline isolation valve 44.

[0083] In a specific embodiment, the passive residual heat removal heat exchanger 40 is placed in an external heat well 70 outside the containment vessel 60. The external heat well 70 is a water pool structure, which has a large capacity that can meet the core residual heat removal requirements for at least 7 days. An external heat well cooling device 71 is provided on the external heat well 70, and the external heat well 70 can be cooled by the external heat well cooling device 71.

[0084] The external heat sink 70 may also be a natural cooling water source such as a river, lake, or sea. The external heat sink cooling device 71 may be a non-safety grade cooling device.

[0085] This embodiment provides an external heat sink 70 outside the containment vessel, which can meet the core cooling demand for at least 7 days after an accident and achieve long-term removal of reactor heat.

[0086] The containment vessel 60 is also equipped with pressure accumulator and injection tanks 30, configured with two or more independent pressure accumulator and injection systems. These pressure accumulator and injection tanks 30 are connected to the integrated reactor pressure vessel 10 via injection pipelines 32. The pressure accumulator and injection tanks 30 are filled with coolant and a certain proportion of nitrogen for pressure accumulation. These tanks replenish coolant in the event of a coolant loss in the integrated reactor pressure vessel 10. In this embodiment, the coolant is water.

[0087] Safety injection line 32 is equipped with a check valve 31 and an isolation valve 33. This valve is normally open and connected in parallel with bypass line 34. The resistance of the isolation valve 33 and the parallel branch in which it is connected is much lower than that of the bypass line 34 and its parallel branch.

[0088] The injection line check valve 31 has a non-return function. When the pressure of the integrated reactor pressure vessel 10 is higher than that of the pressure accumulator and injection tank 30, it prevents fluid inside the integrated reactor pressure vessel 10 from entering the pressure accumulator and injection tank 30. Because the injection line check valve 31 has a smaller opening when the pressure differential across the two ends is small, and a smaller opening results in greater resistance, the injection flow rate through the injection line check valve 31 is small during the late injection phase of the pressure accumulator and injection tank 30, when the pressure in the pressure accumulator and injection tank 30 is low.

[0089] The function of the injection line isolation valve 33 is to isolate the pipeline in the late stage of pressure accumulator injection, so that all flow from the pressure accumulator injection tank 30 flows through the bypass line 34. Specifically, when a certain amount of coolant remains inside the pressure accumulator injection tank 30, the injection line isolation valve 33 is triggered to close, allowing the remaining coolant in the pressure accumulator injection tank 30 to continue to be injected into the integrated reactor pressure vessel 10 through the bypass line 34. Because the resistance of the bypass line 34 and the parallel branch to which it is connected is much greater than that of the injection line isolation valve 33 and the parallel branch to which it is connected, the injection flow rate is significantly reduced.

[0090] When the pressure accumulator injection tank 30 replenishes coolant into the pressure vessel 10, during the initial injection phase, the injection line isolation valve 33 is open, and the injection line check valve 31 is also open because the pressure in the pressure accumulator injection tank 30 is greater than the pressure in the pressure vessel 10. Later in the injection phase, when a certain amount of coolant still remains inside the pressure accumulator injection tank 30, the injection line isolation valve 33 closes, allowing the injection flow to flow solely through the parallel, higher-resistance bypass line 34. As the injection progresses, the pressure in the pressure accumulator injection tank 30 gradually decreases, and the pressure differential with the pressure vessel 10 also decreases. Consequently, the opening of the injection line check valve 31 also decreases (it does not close), and the resistance gradually increases. This increases the resistance from the pressure accumulator injection tank 30 to the pressure vessel 10 during the later stages of the injection phase, achieving an injection flow rate different from that achieved during the initial injection phase.

[0091] The safety injection line check valve 31 is a swing check valve. When the pressure differential across the safety injection line check valve 31 is low, the valve opening is small, resulting in greater resistance and a smaller safety injection flow rate. In the event of an accident, the pressurized nitrogen can propel the coolant within the pressure-accumulated safety injection tank 30 through the safety injection line 32 to the integrated reactor pressure vessel 10 for water replenishment. This ensures that the water level within the integrated reactor pressure vessel 10 remains above the upper chamber water flow hole 14, ensuring that natural circulation between the reactor core 11 and the primary and secondary heat exchangers 20 is always established, thereby utilizing the primary and secondary heat exchangers 20 to continuously remove heat from the reactor core 11.

[0092] This embodiment maintains natural circulation between the reactor core 11 and the primary and secondary side heat exchangers 20 through pressurized injection and passive residual heat removal heat exchangers 40, without the need for containment pit recirculation, greatly simplifying the post-accident mitigation path and facilitating post-accident recovery.

[0093] In one embodiment, a containment suppression tank 50 is further disposed within the containment shell 60. The containment suppression tank 50 is located at the bottom of the containment shell 60. The containment suppression tank 50 is a sealed tank comprising a suppression tank inlet pipeline 51, a suppression tank bubbler 52, and a suppression tank shell 53. The suppression tank shell 53 shares a portion of the wall of the containment shell 60. The containment suppression tank 50 is filled with coolant and leaves a certain proportion of air space. The containment suppression tank 50 communicates with the containment shell 60 space only through the suppression tank inlet pipeline 51. The suppression tank bubbler 52 is located below the coolant liquid level in the containment suppression tank 50 and is connected to the end of the suppression tank inlet pipeline 51.

[0094] When the pressure of the containment vessel 60 is high, high-temperature and high-pressure steam is passively sucked into the containment vessel suppression pool 50 from the suppression pool inlet pipeline 51 and condensed, thereby ensuring that the pressure inside the containment vessel 60 does not exceed the limit.

[0095] The suppression tank bubbler 52 reduces the occurrence of steam hammer. This process does not require the containment vessel 60's walls to have good thermal conductivity or cooling capabilities. The suppression tank housing 53 shares a portion of the containment vessel 60's walls, allowing for flexible utilization of space within the containment vessel 60 and reducing the need for overall containment vessel and suppression tank layout.

[0096] This embodiment provides a containment pressure suppression pool 50, which can passively reduce or maintain the pressure of the containment 60 at a low level. It does not require complex active spraying equipment and support systems, nor does it require the wall of the containment 60 to have good thermal conductivity or cooling capabilities. In addition, the containment pressure suppression pool 50 is simply arranged and has a high utilization rate of the arrangement space.

[0097] FIG2 is a flow chart of a control method of the integrated reactor safety system 100 according to a specific embodiment of the present invention.

[0098] This embodiment provides a control method for an integrated reactor safety system 100, which utilizes the integrated reactor safety system 100 to perform safety control on an integrated reactor. The method includes the following steps:

[0099] Step S1 : When a non-LOCA accident occurs, the integrated reactor safety system 100 is controlled.

[0100] Step S2: When a LOCA accident occurs, the integrated reactor safety system 100 controls the system.

[0101] Step S3, when the pressure of the containment vessel 60 is high, the control method of the integrated reactor safety system 100.

[0102] In step S1, when a non-LOCA accident occurs, the control method of the integrated reactor safety system 100 specifically includes the following steps:

[0103] Step S11: When a non-LOCA accident occurs, close the secondary water supply pipeline isolation valve 23 and the secondary outlet pipeline isolation valve 24.

[0104] In step S12, the waste heat inlet pipeline isolation valve 44 is opened, and the waste heat outlet pipeline isolation valve 43 is confirmed to be normally open. At this time, the primary and secondary side heat exchangers 20 and the passive waste heat removal heat exchanger 40 rely on natural circulation to form a closed circulation loop, bringing the heat of the reactor core 11 to the external heat sink 70.

[0105] In step S2, when a LOCA accident occurs, the control method of the integrated reactor safety system 100 specifically includes the following steps:

[0106] Step S21: When a LOCA accident occurs, close the secondary water supply pipeline isolation valve 23 and the secondary outlet pipeline isolation valve 24.

[0107] In step S22 , the waste gas inlet pipeline isolation valve 44 is opened, and the waste gas outlet pipeline isolation valve 43 is confirmed to be normally open, so as to continuously remove the heat of the reactor core to the external heat sink 70 .

[0108] Due to the strong heat-carrying capacity of the circulation loop, a large amount of water loss caused by continuous boiling of water in the integrated reactor pressure vessel 10 can be avoided.

[0109] Step S23 , when the pressure of the integrated reactor pressure vessel 10 drops to the opening pressure of the pressure relief valve 15 , the pressure relief valve 15 is triggered to open, so that the pressure of the integrated reactor pressure vessel 10 drops to the initial pressure accumulation pressure of the pressure accumulation and injection tank 30 .

[0110] In step S24, the pressurized nitrogen in the pressure accumulator injection tank 30 pushes the internal coolant to enter the integrated reactor pressure vessel 10 through the injection line 32 to replenish the lost water volume, and through the configuration of the valves on the injection line 32 and the bypass line 34, different injection flow rates are achieved before and after injection, ensuring that the water level in the integrated reactor pressure vessel 10 is always higher than the upper chamber water flow hole 14 during the entire accident process, ensuring that natural circulation can always be established between the reactor core 11 and the primary and secondary side heat exchangers 20, thereby utilizing the primary and secondary side heat exchangers 20 to remove heat from the reactor core 11 for a long time.

[0111] In the long term after the LOCA accident, due to the heat carried by the passive residual heat removal heat exchanger 40, the pressure relief valve 15, and the reduction of the decay heat of the reactor core 11, when the pressure of the integrated reactor pressure vessel 10 further drops below a certain value, a certain amount of coolant still remains in the pressure accumulator injection tank 30, triggering the closure of the injection line isolation valve 33. The remaining coolant in the pressure accumulator injection tank 30 can continue to be injected into the integrated reactor pressure vessel 10 through the bypass line 34, but the flow rate will be greatly reduced, which can prevent the pressure accumulator injection tank 30 from being flooded. Excessive injection causes the water in the integrated reactor pressure vessel 10 to overflow from the rupture, and can also replenish the water volume lost due to long-term evaporation and the water body shrinkage caused by excessive cooling, thereby maintaining the water level in the integrated reactor pressure vessel 10 always higher than the upper chamber water flow hole 14, ensuring that the heat of the reactor core 11 is always taken out by the natural circulation between the reactor core 11 and the primary and secondary side heat exchangers 20. Therefore, there is no need to use pit recirculation to maintain long-term cooling after the LOCA accident, which greatly simplifies the post-accident mitigation path and is conducive to post-accident recovery.

[0112] In step S3, when the pressure of the containment vessel 60 is high, the control method of the integrated reactor safety system 100 specifically includes the following steps:

[0113] Step S31, when the pressure of the containment 60 is high, high-temperature and high-pressure steam is passively sucked into the containment suppression pool 50 from the suppression pool inlet pipeline 51 and condensed, thereby ensuring that the pressure inside the containment 60 does not exceed the limit.

[0114] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. An integrated reactor safety system, characterized in that: include: Containment; An integrated reactor pressure vessel, which is arranged in the containment vessel, wherein a reactor core and a built-in pressurizer are arranged in the integrated reactor pressure vessel, wherein the reactor core is arranged at the lower part of the integrated reactor pressure vessel, and the built-in pressurizer is arranged at the top of the integrated reactor pressure vessel; A primary and secondary side heat exchanger, which is arranged inside the integrated reactor pressure vessel, wherein the secondary side inlet of the primary and secondary side heat exchanger is connected to the secondary side water supply pipeline, and the secondary side outlet of the primary and secondary side heat exchanger is connected to the secondary side outlet pipeline; A passive residual heat removal heat exchanger, which is arranged outside the containment, the outlet of the passive residual heat removal heat exchanger is connected to the secondary side water supply pipeline through a residual discharge outlet pipeline, and the inlet of the non-kinetic residual heat removal heat exchanger is connected to the secondary side outlet pipeline through a residual discharge inlet pipeline; in, An upper chamber is arranged between the built-in pressurizer and the reactor core, and in-core components and a control rod drive mechanism are arranged in the upper chamber; an upper chamber water flow hole is opened on the side wall of the upper chamber, the primary and secondary side heat exchangers are located outside the upper chamber, and the upper chamber water flow hole is located above the primary and secondary side heat exchangers.

2. The integrated reactor safety system according to claim 1, characterized in that: A pressure relief valve is arranged on the top of the integrated reactor pressure vessel, and the top of the built-in pressurizer is connected to the pressure relief valve.

3. The integrated reactor safety system according to claim 1, characterized in that: The secondary water supply pipeline is provided with a secondary water supply pipeline isolation valve, and the secondary outlet pipeline is provided with a secondary outlet pipeline isolation valve.

4. The integrated reactor safety system according to claim 3, characterized in that: One end of the excess discharge outlet pipeline is connected between the secondary water supply pipeline isolation valve and the secondary side inlet of the secondary side heat exchanger, and one end of the excess discharge inlet pipeline is connected between the secondary side outlet pipeline isolation valve and the secondary side outlet of the secondary side heat exchanger.

5. The integrated reactor safety system according to claim 1, characterized in that: A pressure accumulator and injection tank is also provided in the containment shell. The pressure accumulator and injection tank is connected to the integrated reactor pressure vessel through an injection pipeline. Coolant is filled in the pressure accumulator and injection tank. A injection pipeline check valve and an injection pipeline isolation valve are provided on the injection pipeline. The injection pipeline isolation valve is connected in parallel with a bypass pipeline.

6. The integrated reactor safety system according to claim 1, characterized in that: The passive residual heat removal heat exchanger is placed in an external heat sink outside the containment vessel.

7. The integrated reactor safety system according to claim 6, characterized in that: The external heat sink is provided with an external heat sink cooling device.

8. The integrated reactor safety system according to claim 1, characterized in that: A containment pressure suppression pool is also provided inside the containment. The containment pressure suppression pool is a closed tank body filled with a coolant. The top of the containment pressure suppression pool is connected to the containment space through a pressure suppression pool inlet pipeline.

9. The integrated reactor safety system according to claim 8, characterized in that: A suppression pool bubbler is arranged inside the containment suppression pool. The suppression pool bubbler is located below the coolant liquid level in the containment suppression pool and is connected to the end of the suppression pool inlet pipeline.

10. A control method for an integrated reactor safety system, using the integrated reactor safety system according to any one of claims 1 to 9 to perform safety control on an integrated reactor, characterized in that: Including the control method when a non-LOCA accident occurs, specifically including the following steps: Close the isolation valve of the secondary water supply pipeline and the isolation valve of the secondary outlet pipeline; Open the isolating valve of the waste heat discharge inlet pipeline and confirm that the isolating valve of the waste heat discharge outlet pipeline is normally open. At this time, the primary and secondary side heat exchangers and the passive waste heat discharge heat exchanger rely on natural circulation to form a closed circulation loop, bringing the heat of the reactor core to the external heat sink.

11. The control method of the integrated reactor safety system according to claim 10, further comprising a control method when a LOCA accident occurs, specifically comprising the following steps: Close the secondary side water supply pipeline isolation valve and the secondary side outlet pipeline isolation valve; Open the waste inlet pipeline isolation valve, and confirm that the waste outlet pipeline isolation valve is normally open, and continuously carry out the reactor core heat to the external heat sink; When the pressure of the integrated reactor pressure vessel drops to the opening pressure of the pressure relief valve, the pressure relief valve is triggered to open, so that the pressure of the integrated reactor pressure vessel drops to the initial pressure accumulation pressure of the pressure accumulation injection tank; The pressurized nitrogen in the pressure accumulator injection tank pushes the internal coolant to enter the integrated reactor pressure vessel through the injection pipeline to replenish the lost water volume, and the different injection flow rates before and after injection are achieved through the configuration of the valves and bypass pipelines on the injection pipeline, ensuring that the water level in the integrated reactor pressure vessel is always higher than the water flow hole in the upper chamber during the entire accident process, ensuring that a natural circulation can always be established between the reactor core and the primary and secondary side heat exchangers. ring, thereby utilizing the primary and secondary side heat exchangers to remove the heat of the reactor core for a long time.

12. The control method of the integrated reactor safety system according to claim 10, further comprising a control method when the containment pressure is high, specifically comprising the following steps: High-temperature and high-pressure steam is passively sucked from the suppression pool inlet pipeline into the containment suppression pool and condensed, thereby ensuring that the pressure inside the containment does not exceed the limit value.

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