An overpressure protection pressure relief discharge system and a nuclear power plant having the same

Abstract

The present invention provides an overpressure protection pressure relief discharge system and a nuclear power plant having the same. The nuclear power plant includes a reactor coolant system, a safety injection system, a residual heat removal system and a built-in refueling water tank. The overpressure protection pressure relief discharge system includes: a first connecting pipeline, one end of which is connected to the safety injection system, and the other end of which extends into the built-in refueling water tank; a second connecting pipeline, one end of which is connected to the residual heat removal system, and the other end of which extends into the built-in refueling water tank; a first safety valve, which is arranged on the first connecting pipeline, and when the pressure value of the first safety valve is greater than or equal to the first preset pressure value, the first safety valve is opened to connect the first connecting pipeline; a second safety valve, which is arranged on the second connecting pipeline, and when the pressure value of the second safety valve is greater than or equal to the second preset pressure value, the second safety valve is opened to connect the second connecting pipeline. The embodiment of the present invention can simplify the structure of the overpressure protection pressure relief discharge system.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear energy, and in particular to an overpressure protection pressure relief discharge system and a nuclear power plant having the same. Background Art

[0002] In a pressurized water reactor nuclear power plant, it includes: reactor coolant system, safety injection system, residual heat removal system and stabilizer pressure relief tank.

[0003] In the related art, safety valves are respectively provided on the pipelines connecting the safety injection system and the reactor coolant system, and on the pipelines connecting the waste heat removal system and the reactor coolant system. When the set pressure value is reached, the safety valve opens to release the pressure, and the discharged fluid enters the pressure relief tank of the pressurizer to achieve overpressure protection.

[0004] However, in the overpressure protection pressure relief discharge system, the pressure stabilizer pressure relief tank has a large volume and the discharge piping is difficult to arrange.

[0005] It can be seen from the above that the overpressure protection pressure relief discharge system in the related art has the defect of complex structure. Summary of the invention

[0006] The embodiment of the present invention provides an overpressure protection pressure relief discharge system and a nuclear power plant having the same, so as to solve the problem of complex structure of the overpressure protection system in the related art.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] In a first aspect, an embodiment of the present invention provides an overpressure protection pressure relief discharge system, which is applied to a nuclear power plant, wherein the nuclear power plant includes a reactor coolant system, a safety injection system, a residual heat removal system, and a built-in refueling water tank, wherein the safety injection system is connected to a cold pipe section of the reactor coolant system, and the residual heat removal system is connected to a hot pipe section of the reactor coolant system, and the overpressure protection pressure relief discharge system includes:

[0009] A first connecting pipeline, one end of which is connected to the safety injection system, and the other end of which extends into the internal replacement water tank;

[0010] a second connecting pipeline, one end of which is connected to the waste heat removal system, and the other end of which extends into the internal displacement water tank;

[0011] a first safety valve, disposed on the first connecting pipeline, and when a pressure value of the first safety valve is greater than or equal to a first preset pressure value, the first safety valve is opened to connect the first connecting pipeline;

[0012] The second safety valve is arranged on the second connecting pipeline. When the pressure value of the second safety valve is greater than or equal to the second preset pressure value, the second safety valve is opened to connect the second connecting pipeline.

[0013] Optionally, the overpressure protection pressure relief discharge system further includes:

[0014] A first pressure relief diffusion device, which is disposed at one end of the first connecting pipeline extending into the internal displacement water tank;

[0015] A second pressure relief diffusion device is arranged at one end of the second connecting pipeline extending into the internal replacement water tank.

[0016] Optionally, the first safety valve and / or the second safety valve is any one of the following:

[0017] Spring loaded safety valve;

[0018] Pilot operated safety valve.

[0019] Optionally, the first pressure relief diffusion device and / or the second pressure relief diffusion device is any one of the following:

[0020] A barrel expander, the barrel expander comprising a cylindrical body and a nozzle fixed to the cylindrical body and connected to the inner cavity of the cylindrical body, wherein the outlet direction of the nozzle is perpendicular to the axial direction of the cylindrical body;

[0021] A discharge plate, wherein a discharge hole is formed on the discharge plate;

[0022] A venturi diffuser comprises a barrel portion and a venturi nozzle fixed to the barrel portion and connected to an inner cavity of the barrel portion.

[0023] Optionally, the overpressure protection pressure relief discharge system further includes:

[0024] A safety injection pump return pipeline, one end of which is connected to the safety injection system, and the other end of which extends into the internal replacement water tank;

[0025] A waste heat discharge pump return pipeline, one end of which is connected to the waste heat discharge system, and the other end of which extends into the internal displacement water tank.

[0026] Optionally, the overpressure protection pressure relief discharge system further includes:

[0027] A third pressure relief diffusion device, the third pressure relief diffusion device is arranged at one end of the return pipeline of the safety injection pump extending into the internal replacement water tank;

[0028] A fourth pressure relief diffusion device is arranged at one end of the waste heat discharge pump return pipeline extending into the internal replacement material water tank.

[0029] Optionally, when the overpressure protection pressure relief discharge system includes a first pressure relief diffuser and a second pressure relief diffuser, the third pressure relief diffuser and the first pressure relief diffuser are the same pressure relief diffuser, and the fourth pressure relief diffuser and the second pressure relief diffuser are the same pressure relief diffuser.

[0030] Optionally, the safety injection system includes a safety injection pump, and one end of the safety injection pump return pipeline connected to the safety injection system is located downstream of the safety injection pump;

[0031] The waste heat removal system comprises a waste heat removal pump, and one end of the waste heat removal pump return pipeline connected to the waste heat removal system is located downstream of the waste heat removal pump.

[0032] Optionally, a first check valve is provided on the return pipeline of the safety injection pump, and a second check valve is provided on the return pipeline of the waste heat discharge pump.

[0033] In a second aspect, an embodiment of the present invention further provides a nuclear power plant, comprising: a reactor coolant system, a safety injection system, a residual heat removal system, a built-in refueling water tank, and the overpressure protection pressure relief and discharge system provided in the first aspect of the embodiment of the present invention, wherein the safety injection system is connected to the cold pipe section of the reactor coolant system, the residual heat removal system is connected to the hot pipe section of the reactor coolant system, one end of a first connecting pipeline in the overpressure protection pressure relief and discharge system is connected to the safety injection system, and the other end of the first connecting pipeline extends into the built-in refueling water tank; one end of a second connecting pipeline in the overpressure protection pressure relief and discharge system is connected to the residual heat removal system, and the other end of the second connecting pipeline extends into the built-in refueling water tank.

[0034] In the overpressure protection pressure relief discharge system provided by the embodiment of the present invention, a first connecting pipeline is arranged between the safety injection system and the built-in refueling water tank, and a second connecting pipeline is arranged between the residual heat removal system and the built-in refueling water tank, and when the pressure value of the first safety valve is greater than or equal to the first preset pressure value, the first safety valve is opened to connect the first connecting pipeline, and when the pressure value of the second safety valve is greater than or equal to the second preset pressure value, the second safety valve is opened to connect the second connecting pipeline. In this way, when the first connecting pipeline is connected, the fluid in the cold pipe section of the reactor coolant system can be discharged into the built-in refueling water tank, and when the second connecting pipeline is connected, the fluid in the hot pipe section of the reactor coolant system can be discharged into the built-in refueling water tank, so as to reuse the built-in refueling water tank in the nuclear power plant to realize the pressure relief protection function, and the built-in refueling water tank is located in the containment of the nuclear power plant, so that the first connecting pipeline and the second connecting pipeline are easy to wire and set, thereby simplifying the structural complexity of the overpressure protection pressure relief discharge system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 It is a structural diagram of an overpressure protection pressure relief discharge system provided by an embodiment of the present invention;

[0037] Figure 2 is a structural diagram of another overpressure protection pressure relief discharge system provided by an embodiment of the present invention;

[0038] Figure 3 1 is a front view of a first type of pressure relief diffusion device in an overpressure protection pressure relief discharge system provided by an embodiment of the present invention;

[0039] Figure 4 is a side view of a first type of pressure relief diffusion device in the overpressure protection pressure relief discharge system provided by an embodiment of the present invention;

[0040] Figure 5 It is a structural diagram of a second type of pressure relief diffusion device in the overpressure protection pressure relief discharge system provided in an embodiment of the present invention;

[0041] Figure 6 It is a structural diagram of a third type of pressure relief diffusion device in the overpressure protection pressure relief discharge system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The overpressure protection pressure relief and discharge system provided in the embodiment of the present invention can reduce the pressure in the reactor coolant system, the safety injection system and the residual heat discharge system in the nuclear power plant, so as to avoid excessive pressure in the pipelines of each system, causing pipeline loss or even nuclear leakage, and the fluid discharged during the pressure relief process is contained in the internal refueling water tank, so as to avoid the need to set up a stabilizer pressure relief tank separately, and the internal refueling water tank is located in the containment of the nuclear power plant. When arranging the pipelines between the internal refueling water tank and the reactor coolant system, the safety injection system and the residual heat discharge system in the containment, the embodiment of the present invention can set the pipelines in the containment to simplify the complexity of the pipeline wiring, thereby simplifying the structural complexity of the overpressure protection pressure relief and discharge system.

[0044] See also Figure 1 , is a schematic diagram of the structure of an overpressure protection pressure relief discharge system provided by an embodiment of the present invention, and the overpressure protection pressure relief discharge system is applied to a nuclear power plant, such as Figure 1 As shown, the nuclear power plant includes a reactor coolant system 10, a safety injection system 20, a waste heat removal system 30 and an internal refueling water tank 40. The safety injection system 20 is connected to the cold pipe section 101 of the reactor coolant system 10, and the waste heat removal system 30 is connected to the hot pipe section 102 of the reactor coolant system 10. The overpressure protection pressure relief discharge system includes: a first connecting pipeline 11, a second connecting pipeline 12, a first safety valve 13 and a second safety valve 14.

[0045] Among them, one end of the first connecting pipeline 11 is connected to the safety injection system 20, and the other end of the first connecting pipeline 11 extends into the built-in replacement water tank 40; one end of the second connecting pipeline 12 is connected to the waste heat discharge system 30, and the other end of the second connecting pipeline 12 extends into the built-in replacement water tank 40; the first safety valve 13 is arranged on the first connecting pipeline 11, and when the pressure value of the first safety valve 13 is greater than or equal to the first preset pressure value, the first safety valve 13 is opened to connect the first connecting pipeline 11; the second safety valve 14 is arranged on the second connecting pipeline 12, and when the pressure value of the second safety valve 14 is greater than or equal to the second preset pressure value, the second safety valve 14 is opened to connect the second connecting pipeline 12.

[0046] In a specific implementation, the first safety valve 13 and the second safety valve 14 may be spring-loaded safety valves or pilot safety valves, or the first safety valve 13 and the second safety valve 14 may be electrically controlled valves with pressure detection devices to control the opening of the electrically controlled valves when the pressure value detected by the pressure detection device exceeds a limit. The specific structure and type of the first safety valve 13 and the second safety valve 14 are not limited herein. In addition, the specific values ​​of the first preset pressure value and the second preset pressure value can be determined according to the actual operation of the nuclear power plant and the accident condition design. For example, the situation where the pressure value of the first safety valve 13 is greater than or equal to the first preset pressure value may be: during the operation of the nuclear power plant, the safety injection system 20 is in an isolated state. If the check valve in the safety injection system 20 leaks, the high-pressure fluid in the reactor coolant system 10 will enter the safety injection system 20, so that the pressure value of the first safety valve 13 exceeds the first preset pressure value. At this time, the first safety valve 13 opens to discharge the high-pressure fluid in the cold pipe section 101 of the reactor coolant system 10 to the internal replacement water tank 40 through the first connecting pipeline 11 to reduce the pressure in the safety injection system 20.

[0047] Another example: the situation where the pressure value of the above-mentioned second safety valve 14 is greater than or equal to the second preset pressure value may be: during the shutdown of the nuclear power plant, the residual heat removal system 30 is started. If the main pump of the reactor coolant system 10 is suddenly started at this time, the pressure in the residual heat removal system 30 will rise, and the pressure value of the second safety valve 14 will be greater than or equal to the second preset pressure value. At this time, the second safety valve 14 opens to discharge the fluid in the hot pipe section 102 of the reactor coolant system 10 to the internal refueling water tank 40 through the second connecting pipeline 12 to reduce the pressure in the residual heat removal system 30.

[0048] In practical applications, such as Figure 2 As shown, the internal refueling water tank 40 is located in the containment of the nuclear power plant, wherein the containment surrounds Figure 2 The area between the first containment wall 501 and the second containment wall 502 shown in the figure, and the pipelines between the reactor coolant system 10, the safety injection system 20 and the internal refueling water tank 40 (including the first connecting pipeline 11 and the safety injection pump return pipeline 204), and the pipelines between the residual heat removal system 30 and the internal refueling water tank 40 (including the second connecting pipeline 12 and the residual heat removal pump return pipeline 304) are all located inside the containment. In this way, the arrangement of the pipelines can be simplified and the penetration of the containment can be reduced, thereby simplifying the structural complexity of the overpressure protection pressure relief discharge system.

[0049] Optional, such as Figure 2 As shown, the overpressure protection pressure relief discharge system also includes:

[0050] A first pressure relief diffusion device 5, which is disposed at one end of the first connecting pipeline 11 extending into the internal displacement water tank 40;

[0051] The second pressure relief diffusion device 6 is arranged at one end of the second connecting pipeline 12 extending into the internal displacement water tank 40 .

[0052] In implementation, when the first safety valve 13 is opened, the fluid in the first connecting pipeline 11 enters the internal replacement material water tank 40 after diffusion through the first pressure relief diffusion device 5, and the water outlet of the first pressure relief diffusion device 5 can be immersed in the liquid in the internal replacement material water tank 40; when the second safety valve 14 is opened, the fluid in the second connecting pipeline 12 enters the internal replacement material water tank 40 after diffusion through the second pressure relief diffusion device 6, and the water outlet of the second pressure relief diffusion device 6 can be immersed in the liquid in the internal replacement material water tank 40.

[0053] In this way, after the fluid in the first connecting pipeline 11 and the second connecting pipeline 12 is depressurized and diffused by the first pressure relief diffusion device 5 and the second pressure relief diffusion device 6, the pressure of the discharged fluid can be reduced, thereby avoiding excessive fluid pressure in the first connecting pipeline 11 and the second connecting pipeline 12 to damage the steel cladding of the internal displacement water tank 40.

[0054] Further, the first pressure relief diffusion device 5 and / or the second pressure relief diffusion device 6 is any one of the following:

[0055] like Figure 3 and Figure 4 The drum expander 7 shown in the figure comprises a cylindrical body 71 and a nozzle 72 fixed to the cylindrical body 71 and connected to the inner cavity of the cylindrical body 71, and the outlet direction of the nozzle 72 is perpendicular to the axial direction of the cylindrical body 71;

[0056] like Figure 5 The discharge plate 8 shown in the figure has a discharge hole 81 formed thereon;

[0057] like Figure 6 The Venturi diffuser 9 shown in the figure comprises a barrel portion 91 and a Venturi nozzle 92 fixed to the barrel portion 91 and connected to the inner cavity of the barrel portion 91 .

[0058] Among them, Figure 3 and Figure 4The barrel expander 7 shown in the figure has a cylindrical body 71 connected to one end of the first connecting pipeline 11 close to the internal discharging water tank 40, and a nozzle 72 having a first tube body portion 721 connected to the inner cavity of the cylindrical body 71, and a second tube body portion 722 connected to the first tube body portion 721 and perpendicular to the first tube body portion 721, and the first tube body portion 721 and the second tube body portion 722 are both perpendicular to the axial direction of the cylindrical body 71. In this way, when the nozzle 72 discharges the fluid, the barrel expander 7 is rotated along its axial direction by the recoil force of the fluid to evenly sprinkle the discharged fluid into the internal discharging water tank 40. In addition, the number of nozzles 72 on the cylindrical body 71 can be multiple, for example: 3, 4, etc., and each nozzle 72 can be evenly distributed on the circumference of the cylindrical body 71, so that the liquid in the internal discharging water tank 40 is more uniform.

[0059] In addition, if Figure 5 The discharge plate 8 shown in the figure has its periphery sealing the outlet of the connecting pipeline, so that the fluid in the connecting pipeline is discharged into the internal displacement water tank 40 after being depressurized and dispersed through the discharge holes 81 opened on the discharge plate 8. Figure 4 In the discharge plate 8 shown, the number of the discharge holes 81 is 3, and they are rectangular through-hole structures. Of course, in a specific implementation, the number of the discharge holes 81 can also be other numbers, for example: 5, 10, etc., and the shape of the discharge holes 81 can also be circular, diamond, etc., which is not specifically limited here.

[0060] In addition, if Figure 6 The Venturi diffuser 9 shown in the figure can be understood as a nozzle with a Venturi structure, which has a good pressure relief effect. It should be noted that the barrel portion 91 of the Venturi diffuser 9 can be the same structure as the end of the connecting pipeline extending to the internal displacement water tank 40, and the Venturi nozzle 92 in the Venturi diffuser 9 is connected to the inner cavity of the connecting pipeline, and the number of the Venturi nozzles 92 can be multiple, for example: 3, 4, etc., and the multiple Venturi nozzles 92 can face different directions.

[0061] It should be noted that the above-mentioned first pressure relief diffuser 5 and / or second pressure relief diffuser 6 can also be pressure relief diffusers of other structures, which are only used to reduce the pressure of the discharged liquid through the pressure relief diffuser and increase the discharge area of ​​the discharged liquid so that the liquid in the internal displacement water tank 40 can be evenly mixed.

[0062] Optional, such as Figure 2 As shown, the overpressure protection pressure relief discharge system also includes:

[0063] A safety injection pump return pipeline 204, one end of which is connected to the safety injection system 20, and the other end of which extends into the internal displacement water tank 40;

[0064] A waste heat removal pump return pipeline 304 , one end of which is connected to the waste heat removal system 30 , and the other end of which extends into the internal displacement water tank 40 .

[0065] In the specific implementation, Figure 2 As shown, the safety injection system 20 includes a safety injection system pipeline 201, a safety injection pump 202 and a first isolation valve 203 arranged on the safety injection system pipeline 201, and the safety injection pump return pipeline 204 is connected to the safety injection system pipeline 201 at a position downstream of the safety injection pump 202, so that the fluid injected by the safety injection pump 202 can enter the safety injection pump return pipeline 204. In a specific application, when the nuclear power plant is operating normally, the first isolation valve 203 is in a closed state to isolate the safety injection system 20 from the reactor coolant system 10.

[0066] In addition, the above-mentioned residual heat removal system 30 includes a residual heat removal system pipeline 301, a residual heat removal pump 302 and a second isolation valve 303 arranged on the residual heat removal system pipeline 301, and the above-mentioned residual heat removal pump return pipeline 304 is connected to the residual heat removal system pipeline 301 at a position downstream of the residual heat removal pump 302, so that the fluid injected through the residual heat removal pump 302 can enter the residual heat removal pump return pipeline 204. In a specific application, when the nuclear power plant is operating normally, the second isolation valve 303 is in a closed state to isolate the residual heat removal system 30 from the reactor coolant system 10.

[0067] It should be noted that the downstream of the above-mentioned waste heat discharge pump 302 represents the direction of the fluid discharged by the waste heat discharge pump 302 ; similarly, the downstream of the above-mentioned safety injection pump 202 represents the direction of the fluid discharged by the safety injection pump 202 .

[0068] Before the nuclear power plant is started or during normal operation, when the internal replacement fuel water tank 40 needs to be initially filled with water or regularly replenished with water, one or both of the first isolation valve 203 and the second isolation valve 303 are opened to start the safety injection pump 202 when the first isolation valve 203 is opened, and to start the waste heat discharge pump 302 when the second isolation valve 303 is opened. In this way, fluid can be discharged into the internal replacement fuel water tank 40 through the safety injection system 20 and the safety injection pump return pipeline 204, and fluid can be discharged into the internal replacement fuel water tank 40 through the waste heat discharge system 30 and the waste heat discharge pump return pipeline 304, so as to achieve a stirring and mixing effect on the fluid in the internal replacement fuel water tank 40, so as to make the boron concentration in each area of ​​the internal replacement fuel water tank 40 uniform.

[0069] Optionally, the overpressure protection pressure relief discharge system further includes:

[0070] A third pressure relief diffusion device, which is disposed at one end of the safety injection pump return pipeline 204 extending into the internal displacement water tank 40;

[0071] The fourth pressure relief diffusion device is arranged at one end of the waste heat discharge pump return pipeline 304 extending into the internal displacement water tank 40 .

[0072] It should be noted that if Figure 2 In the illustrated embodiment, the third pressure relief diffuser and the first pressure relief diffuser 5 are the same pressure relief diffuser, that is, the first connecting pipeline 11 and the safety injection pump return pipeline 204 at one end close to the internal displacement water tank 40 share a pipeline, and the fourth pressure relief diffuser and the second pressure relief diffuser 6 are the same pressure relief diffuser, that is, the second connecting pipeline 12 and the waste heat discharge pump return pipeline 304 at one end close to the internal displacement water tank 40 share a pipeline. In this way, the structure of the overpressure protection pressure relief discharge system can be simplified and costs can be saved.

[0073] In this way, when fluid is injected into the internal replacement material water tank 40 through the safety injection pump return pipeline 204 and the waste heat discharge pump return pipeline 304 to mix the internal replacement material water tank 40, the boron concentration in the internal replacement material water tank 40 is made more uniform through the pressure relief diffusion device 5, thereby improving the mixing effect. Taking the first connecting pipeline 11, the safety injection pump return pipeline 204 and the first pressure relief diffusion device 5 as examples, the working process of the nuclear power plant is explained. During the application process, when the pressure relief protection is working, the first safety valve 13 on the first connecting pipeline 11 is opened to allow the pressure relief discharge fluid to be discharged into the internal replacement fuel water tank 40. At the same time, through the pressure relief diffusion device 5, the high-pressure discharge fluid is prevented from impacting and damaging the steel cladding of the internal replacement fuel water tank 40; in addition, the pressure relief diffusion device 5 is connected to the safety injection pump return pipeline 204, so that when the safety injection pump 202 is started, the fluid is driven to be discharged into the internal replacement fuel water tank 40 through the safety injection pump return pipeline 204 and the pressure relief diffusion device 5, which has the effect of stirring the boron-containing water in the internal replacement fuel water tank 40, so that the boron concentration in the internal replacement fuel water tank 40 is more uniform. Of course, the working process of the second connecting pipeline 12, the waste heat discharge pump return pipeline 304 and the second pressure relief diffusion device 6 is similar to the working process of the first connecting pipeline 11, the safety injection pump return pipeline 204 and the first pressure relief diffusion device 5 mentioned above, and will not be repeated here.

[0074] Optionally, a first check valve 205 is provided on the safety injection pump return pipeline 204 , and a second check valve 305 is provided on the waste heat discharge pump return pipeline 304 .

[0075] In a specific implementation, the first check valve 205 and the second check valve 305 can be electric check valves, and of course, they can also be hydraulic check valves, etc., which are not specifically limited here. The first check valve 205 is used to limit the flow direction of the fluid in the safety injection pump return line 204 from the end connected to the safety injection system pipeline 201 to the end connected to the internal displacement water tank 40; the second check valve 305 is used to limit the flow direction of the fluid in the waste heat discharge pump return line 204 from the end connected to the waste heat discharge system pipeline 301 to the end connected to the internal displacement water tank 40.

[0076] In a specific implementation, a third check valve 206 and a fourth check valve 207 are also provided on the above-mentioned safety injection system pipeline 201, and one end of the safety injection pump return pipeline 204 is connected between the third check valve 206 and the fourth check valve 207, and one end of the first connecting pipeline 11 is connected between the third check valve 206 and the fourth check valve 207.

[0077] Among them, Figure 2 In the illustrated embodiment, the number of the fourth check valves 207 is two.

[0078] In addition, the waste heat discharge system pipeline 301 is also provided with a third isolation valve 306 and a fifth check valve 307, wherein the number of the third isolation valves 306 is two and they are located upstream of the second isolation valve 303, and the fifth check valve 307 is located downstream of the waste heat discharge pump 302. One end of the second connecting pipeline 12 is connected between the third isolation valve 306 and the second isolation valve 303, and one end of the waste heat discharge pump return pipeline 304 is connected between the fifth check valve 307 and the waste heat discharge pump 302.

[0079] In the overpressure protection pressure relief discharge system provided by the embodiment of the present invention, a first connecting pipeline is arranged between the safety injection system and the built-in refueling water tank, and a second connecting pipeline is arranged between the residual heat removal system and the built-in refueling water tank, and when the pressure value of the first safety valve is greater than or equal to the first preset pressure value, the first safety valve is opened to connect the first connecting pipeline, and when the pressure value of the second safety valve is greater than or equal to the second preset pressure value, the second safety valve is opened to connect the second connecting pipeline. In this way, when the first connecting pipeline is connected, the fluid in the cold pipe section of the reactor coolant system can be discharged into the built-in refueling water tank, and when the second connecting pipeline is connected, the fluid in the hot pipe section of the reactor coolant system can be discharged into the built-in refueling water tank, so as to reuse the built-in refueling water tank in the nuclear power plant to realize the pressure relief protection function, and the built-in refueling water tank is located in the containment of the nuclear power plant, so that the first connecting pipeline and the second connecting pipeline are easy to set up, and the penetration of the containment is reduced, thereby simplifying the structural complexity of the overpressure protection pressure relief discharge system.

[0080] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An overpressure protection and pressure relief discharge system, applied to a nuclear power plant, characterized in that: The nuclear power plant comprises a reactor coolant system, a safety injection system, a residual heat removal system and an internal refueling water tank, wherein the safety injection system is connected to a cold pipe section of the reactor coolant system, the residual heat removal system is connected to a hot pipe section of the reactor coolant system, and the overpressure protection pressure relief discharge system comprises: A first connecting pipeline, one end of which is connected to the safety injection system, and the other end of which extends into the internal replacement water tank; a second connecting pipeline, one end of which is connected to the waste heat removal system, and the other end of which extends into the internal displacement water tank; a first safety valve, disposed on the first connecting pipeline, and when a pressure value of the first safety valve is greater than or equal to a first preset pressure value, the first safety valve is opened to connect the first connecting pipeline; a second safety valve, disposed on the second connecting pipeline, and when a pressure value of the second safety valve is greater than or equal to a second preset pressure value, the second safety valve is opened to connect the second connecting pipeline; The first connecting pipeline, the second connecting pipeline and the internal refueling water tank are all arranged in the containment shell of the nuclear power plant; The overpressure protection pressure relief discharge system also includes: A first pressure relief diffusion device, which is disposed at one end of the first connecting pipeline extending into the internal displacement water tank; A second pressure relief diffusion device is arranged at one end of the second connecting pipeline extending into the internal replacement water tank.

2. The overpressure protection and pressure relief discharge system according to claim 1, characterized in that: The first safety valve and / or the second safety valve is any one of the following: Spring loaded safety valve; Pilot operated safety valve.

3. The overpressure protection and pressure relief discharge system according to claim 1, characterized in that: The first pressure relief diffuser and / or the second pressure relief diffuser is any one of the following: A barrel expander, the barrel expander comprising a cylindrical body and a nozzle fixed to the cylindrical body and connected to the inner cavity of the cylindrical body, wherein the outlet direction of the nozzle is perpendicular to the axial direction of the cylindrical body; A discharge plate, wherein a discharge hole is formed on the discharge plate; A venturi diffuser comprises a barrel portion and a venturi nozzle fixed to the barrel portion and connected to an inner cavity of the barrel portion.

4. The overpressure protection and pressure relief discharge system according to claim 1, characterized in that: The overpressure protection pressure relief discharge system also includes: A safety injection pump return pipeline, one end of which is connected to the safety injection system, and the other end of which extends into the internal replacement water tank; A waste heat discharge pump return pipeline, one end of which is connected to the waste heat discharge system, and the other end of which extends into the internal displacement water tank.

5. The overpressure protection and pressure relief discharge system according to claim 4, characterized in that: The overpressure protection pressure relief discharge system also includes: A third pressure relief diffusion device, the third pressure relief diffusion device is arranged at one end of the return pipeline of the safety injection pump extending into the internal replacement water tank; A fourth pressure relief diffusion device is arranged at one end of the waste heat discharge pump return pipeline extending into the internal replacement material water tank.

6. The overpressure protection and pressure relief discharge system according to claim 5, characterized in that: When the overpressure protection pressure relief discharge system includes a first pressure relief diffuser and a second pressure relief diffuser, the third pressure relief diffuser is the same as the first pressure relief diffuser, and the fourth pressure relief diffuser is the same as the second pressure relief diffuser.

7. The overpressure protection and pressure relief discharge system according to claim 4, characterized in that: The safety injection system comprises a safety injection pump, and one end of the safety injection pump return pipeline connected to the safety injection system is located downstream of the safety injection pump; The waste heat removal system comprises a waste heat removal pump, and one end of the waste heat removal pump return pipeline connected to the waste heat removal system is located downstream of the waste heat removal pump.

8. The overpressure protection and pressure relief discharge system according to claim 4, characterized in that: A first check valve is arranged on the return pipeline of the safety injection pump, and a second check valve is arranged on the return pipeline of the waste heat discharge pump.

9. A nuclear power plant, characterized in that: include: A reactor coolant system, a safety injection system, a residual heat removal system, a built-in refueling water tank and an overpressure protection pressure relief and discharge system as described in any one of claims 1 to 8, wherein the safety injection system is connected to the cold pipe section of the reactor coolant system, the residual heat removal system is connected to the hot pipe section of the reactor coolant system, one end of a first connecting pipeline in the overpressure protection pressure relief and discharge system is connected to the safety injection system, and the other end of the first connecting pipeline extends into the built-in refueling water tank; one end of a second connecting pipeline in the overpressure protection pressure relief and discharge system is connected to the residual heat removal system, and the other end of the second connecting pipeline extends into the built-in refueling water tank.

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