CN214279617U - Safety system of nuclear power station - Google Patents

Abstract

The application provides a nuclear power station safety system which comprises a pressure vessel, a steam generator, a refueling water tank, a first injection unit, a boron injection unit, a steam discharge unit and a pressure relief unit; the first end of the pressure vessel is connected with the first end of the steam generator through a first pipeline, and the second end of the steam generator is connected with the second end of the pressure vessel through a second pipeline; the second pipeline is communicated with the first end of the first injection unit, the first end of the refueling water tank is connected with the first end of the first injection unit, the second end of the first injection unit is connected with the third end of the pressure vessel, the first end of the boron injection unit is connected with the third end of the pressure vessel, the third end of the steam generator is connected with the first end of the steam discharging unit, the first pipeline is communicated with the first end of the pressure relief unit, and the second end of the pressure relief unit is connected with the second end of the refueling water tank. The safety of the nuclear power station safety system can be improved.

Description

Safety system of nuclear power station

Technical Field

The present application relates to the field of nuclear power technology, and more particularly, to a nuclear power plant safety system.

Background

Currently, existing safety systems of nuclear power plants include various systems such as an emergency water supply system and a containment vessel spraying system, which can be used for ensuring the safety of the nuclear power plants, but the safety is low.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides a nuclear power station safety system to solve the problem of low safety.

The embodiment of the application provides a nuclear power station safety system, which comprises a pressure vessel, a steam generator, a refueling water tank, a first injection unit, a boron injection unit, a steam discharge unit and a pressure release unit, wherein the pressure vessel, the steam generator, the refueling water tank and the pressure release unit are arranged inside a containment, and the first injection unit, the boron injection unit and the steam discharge unit are arranged outside the containment;

the first end of the pressure vessel is connected with the first end of the steam generator through a first pipeline, and the second end of the steam generator is connected with the second end of the pressure vessel through a second pipeline;

the first pipeline is communicated with the first end of the first injection unit, the first end of the refueling water tank is connected with the first end of the first injection unit, the second end of the first injection unit is connected with the third end of the pressure vessel, the first end of the boron injection unit is connected with the third end of the pressure vessel, the third end of the steam generator is connected with the first end of the steam discharge unit, the first pipeline is communicated with the first end of the pressure release unit, and the second end of the pressure release unit is connected with the second end of the refueling water tank.

In this way, in the embodiment of the application, if a safety accident occurs, the steam is discharged through the steam discharge unit to lead out heat and reduce pressure, when the pipeline operates normally, a large amount of heat medium generated in the pressure vessel can be led out to the first injection unit through the second pipeline and the third pipeline, and the heat medium is cooled by the first injection unit and then returns to the pressure vessel; when a pipeline is broken, the pressure relief unit drains water to the refueling water tank and is opened, water in the refueling water tank can be filled into the pressure container through the first injection unit, the water in the pressure container flows back to the refueling water tank through the pressure relief unit, in the process, the first injection unit guides out heat, and meanwhile, the boron injection unit is matched to control reaction in the pressure container, so that the running safety of the nuclear power station is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

FIG. 1 is a schematic diagram of a nuclear power plant safety system provided by an embodiment of the present application;

fig. 2 is a second schematic diagram of a nuclear power plant safety system according to an embodiment of the present disclosure.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Referring to fig. 1, fig. 1 is a schematic view of a safety system of a nuclear power plant according to an embodiment of the present disclosure, and as shown in fig. 1, the safety system includes a pressure vessel 10, a steam generator 20, a refueling water tank 30, a first injection unit 40, a boron injection unit 50, a steam exhaust unit 60, and a pressure relief unit 70, where the pressure vessel 10, the steam generator 20, the refueling water tank 30, and the pressure relief unit 70 are disposed inside a containment vessel 80, and the first injection unit 40, the boron injection unit 50, and the steam exhaust unit 60 are disposed outside the containment vessel 80;

a first end of the pressure vessel 10 is connected to a first end of the steam generator 20 through a first pipe 11, and a second end of the steam generator 20 is connected to a second end of the pressure vessel 10 through a second pipe 12;

the first pipeline 11 is communicated with the first end of the first injection unit 40 through a third pipeline 41, the first end of the refueling water tank 30 is connected with the first end of the first injection unit 40, the second end of the first injection unit 40 is connected with the third end of the pressure vessel 10, the first end of the boron injection unit 50 is connected with the third end of the pressure vessel 10, the third end of the steam generator 20 is connected with the first end of the steam discharging unit 60, the first pipeline 11 is communicated with the first end of the pressure relief unit 70, and the second end of the pressure relief unit 70 is connected with the second end of the refueling water tank 30.

The pressure vessel 10 may be used for a core reaction, heat generated from the core may be discharged through the first pipe 11, and boron may be injected into the pressure vessel 10 through the boron injection unit 50 to control the reactivity of the core.

Specifically, the steam discharging unit 60 and the pressure releasing unit 70 may be used to determine whether a main pipe rupture accident or a steam generator heat transfer pipe rupture accident exists during the nuclear power plant heat export, for example: in a design reference condition (DBC), when the steam discharging unit 60 depressurizes the primary circuit to a predetermined pressure, if the water level of the pressure relief unit 70 can be maintained to indicate that there is no main pipe rupture accident or steam generator heat transfer pipe rupture accident, the heat medium output from the first end of the pressure vessel 10 may reach the first injecting unit 40 through the third pipe 41, the heat medium may be returned to the pressure vessel 10 through the second pipe 12 after the first injecting unit 40 is cooled, and boron may be injected into the pressure vessel 10 through the boron injecting unit 50 to control the reactivity of the core, that is, the heat may be directly extracted by the circulation flow of the medium between the first injecting unit 40 and the pressure vessel 10; if the water level of the pressure relief unit 70 cannot be maintained, indicating that there is a main pipe rupture accident or a steam generator heat transfer pipe rupture accident, the first injection unit 40 may deliver the water in the refueling water tank 30 into the pressure vessel 10, and the water may be heated in the pressure vessel 10 and returned to the refueling water tank 30 through the pressure relief unit 70, in this process, the first injection unit 40 may lead decay heat out to the sea water, that is, heat may be led out through a circulation flow of a medium among the refueling water tank 30, the pressure vessel 10, the pressure relief unit 70, and the first injection unit 40.

In the embodiment of the present application, if a safety accident occurs, the steam is discharged through the steam discharge unit 60 to discharge heat and reduce pressure, when the pipeline operates normally, a large amount of heat medium generated in the pressure vessel 10 may be discharged to the first injection unit 40 through the second pipeline 12 and the third pipeline 41, and the heat medium is cooled by the first injection unit 40 and then returns to the pressure vessel 10; when a pipeline is broken, the pressure relief unit 70 drains water to the refueling water tank 30 and is opened, water in the refueling water tank 30 can be filled into the pressure container 10 through the first injection unit 40, water in the pressure container 10 flows back to the refueling water tank 30 through the pressure relief unit 70, in the process, the first injection unit 40 guides out heat, and meanwhile, the boron injection unit 50 is matched to control reaction in the pressure container 10, so that the running safety of the nuclear power station is improved.

In addition, the first injection unit 40 can realize the cooling function of the existing containment spraying system, and the steam discharge unit 60 can realize the function of the existing emergency water supply system, so that the existing containment spraying system and the existing emergency water supply system can be eliminated from the nuclear power plant safety system provided by the application, the number of devices and pipes in the nuclear power plant safety system is reduced, the structure of the nuclear power plant safety system can be simplified, the devices are fully utilized, and the economy of the nuclear power plant is improved.

Optionally, as shown in fig. 2, the first injection unit 40 includes a safety injection pump 42 and a first heat exchanger 43, the second pipeline 12 is communicated with a first end of the safety injection pump 42 through a third pipeline 41, a first end of the refueling water tank 30 is connected to a first end of the safety injection pump 42, and a second end of the safety injection pump 42 is connected to a first end of the first heat exchanger 43;

the second end of the first heat exchanger 43 is connected to the third end of the pressure vessel 10 through a fourth pipeline 44, or the second end of the first heat exchanger 43 is respectively communicated with the first pipeline 11 and the second pipeline 12 through the fourth pipeline 44.

The starting pressure of the first heat exchanger 43 may be preset, for example: when an accident occurs, it is necessary to first discharge steam through the steam discharge unit 60 to achieve heat conduction and pressure reduction, and stop the steam discharge of the steam discharge unit 60 when the pressure of the primary circuit reaches a preset pressure, which may be set to 6 mpa, and at the same time, the first heat exchanger 43 may be set to automatically start at a pressure of 6 mpa to discharge decay heat in the pressure vessel 10 and the second pipeline.

A first end of the fourth pipe 44 may communicate with the first heat exchanger 43, and a second end of the fourth pipe 44 may communicate with the pressure vessel 10, or may communicate with the first pipe 11 and the second pipe 12, respectively, for example: when the other end of the fourth pipe 44 is connected to the pressure vessel 10, the cooling water output from the second end of the first heat exchanger 43 may directly flow into the pressure vessel 10 through the fourth pipe 44; when the other end of the fourth pipe 44 is communicated with the first pipe 11 and the second pipe 12, the cooling water output from the second end of the first heat exchanger 43 may flow into the first pipe 11 and the second pipe 12 through the fourth pipe 44, and then flow into the pressure vessel 10 through the second pipe 12, which is not limited in this embodiment.

In addition, a main pump 14 may be disposed on the second pipe 12, and a medium in the second pipe 12 may be driven to flow from the second end of the steam generator 20 to the second end of the pressure vessel 10, so as to promote circulation of the medium.

In this embodiment, the second end of the first heat exchanger 43 is connected to the third end of the pressure vessel 10 through a fourth pipe 44, or the second end of the first heat exchanger 43 is communicated with the second pipe 12 through the fourth pipe 44, so that the cooling water passing through the first heat exchanger 43 can flow into the pressure vessel 10, thereby preventing the occurrence of core melting accident in the pressure vessel 10 and improving the safety of the nuclear power plant safety system.

Optionally, as shown in fig. 2, a reactor cavity 13 is provided outside the pressure vessel 10, the system further includes a reactor cavity water injection pump 91 and a first water tank 92, wherein:

a first end of the first water tank 92 is communicated with the fourth pipeline 44 through a fifth pipeline 93, the first end of the first water tank 92 is connected with a first end of the reactor chamber 13 through a sixth pipeline 94, the sixth pipeline 94 is provided with a first isolation valve 95 and a first check valve 96, and a third end of the refueling water tank 30 is connected with a first end of the reactor chamber water injection pump 91;

the second end of the reactor cavity water injection pump 91 is connected with the first end of the reactor cavity 13, or the second end of the reactor cavity water injection pump 91 is communicated with the fourth pipeline 44.

The reactor cavity 13 may be a cavity formed by the pressure vessel 10 and a thermal insulation layer on the outer surface thereof, the cold water output from the second end of the reactor cavity water injection pump 91 may flow into the reactor cavity 13 to prevent the pressure vessel 10 from being penetrated by a molten core, or may flow into the pressure vessel 10 through the fourth pipe 44 to prevent the molten core, and either of the above two modes may be selected, or a valve switch may be installed at the second end of the reactor cavity water injection pump 91 to selectively flow into the reactor cavity 13 or into the pressure vessel 10 according to the core condition in the pressure vessel 10, for example: if the core in the pressure vessel 10 is not melted or is not melted seriously, the cold water output from the second end of the core filling pump 91 can be selectively flowed into the pressure vessel 10 through the fourth pipeline 44 by the valve switch to prevent the core from being melted; if a core meltdown accident occurs in the pressure vessel 10, the cold water output from the second end of the core injection pump 91 can be selectively fed into the cavity 13 by the valve switch to prevent the pressure vessel 10 from being penetrated by the molten core.

Specifically, the first tank 92 may be an IVR (In-Vessel Retention) tank, and when the Station Black-out access (SBO) is In an extreme state, the first injection unit 40 may not normally operate when power is lost, may be depressurized by the cavity water injection pump 91, and may inject water into the pressure Vessel 10 through the fifth pipe 93 and the fourth pipe 44 to prevent a serious Accident of core melting; if the core is melted, the first water tank 92 may inject water into the reactor cavity 13 outside the pressure vessel 10 by gravity, prevent the molten core from penetrating the pressure vessel 10 by cooling the pressure vessel 10, and inject water in the refueling water tank 30 into the reactor cavity 13 by the reactor cavity injection pump 91, thereby further improving the cooling effect of the pressure vessel 10.

In addition, the input end of each pump can be provided with an isolation valve, and the output end can be provided with a check valve, for example: the first end of the refueling water tank 30 can be connected with the first end of the safety injection pump 42 through an isolation valve, and the second end of the safety injection pump 42 is connected with the first end of the first heat exchanger 43, so that the effects of safely isolating and preventing media from flowing backwards can be achieved, and the safety is improved.

Optionally, as shown in fig. 2, the boron injection unit 50 includes a boron acid tank 51 and a boron injection pump 52, wherein a first end of the boron acid tank 51 is connected to a first end of the boron injection pump 52;

the second end of the boron injection pump 52 is connected with the third end of the pressure vessel 10, or the second end of the boron injection pump 52 is communicated with the fourth pipeline 44.

The boric acid solution placed in the boric acid tank 51 may be pressurized by a boron pump 52 and then injected into the pressure vessel 10, for example: the second end of the boron injection pump 52 and the third end of the pressure vessel 10 may be directly connected by a pipe, or the boric acid solution may be injected into the fourth pipe 44 and then injected into the pressure vessel 10 through the fourth pipe 44, thereby reducing the number of pipes.

In this embodiment, the second end of the boron injection pump 52 is connected to the third end of the pressure vessel 10, or the second end of the boron injection pump 52 is communicated with the fourth pipe 44, so that the reaction of the pressure vessel 10 can be controlled by the boric acid solution injected into the boric acid tank 51, thereby improving the safety of the safety system of the nuclear power plant.

Optionally, as shown in fig. 2, the pressure relief unit 70 includes a voltage stabilizer 71 and a pressure relief device 72, wherein:

the first pipeline 11 is communicated with a first end of the pressure stabilizer 71, a second end of the pressure stabilizer 71 is connected with a first end of the pressure relief device 72, and a second end of the pressure relief device 72 is connected with a second end of the refueling water tank 30.

Wherein, the refueling water tank 30 may be open at the top, a medium may flow into the second end of the refueling water tank 30 from the second end of the pressure relief device 72 by using gravity, the second end of the refueling water tank 30 is the open at the top of the refueling water tank 30, and the water level of the pressure stabilizer 71 may be used to determine whether a pipe rupture accident occurs in the safety system, for example: the first pipe 11 is connected to a first end of the pressurizer 71, and if there is a rupture accident of the first pipe 11 or a rupture accident of the heat transfer tubes of the steam generator 20, the water level of the pressurizer 71 may change, and the pressure relief device 72 may connect the pressurizer 71 to the refueling water tank 30 when the water level of the pressurizer 71 changes, and circulate a heat medium among the pressure vessel 10, the pressure relief unit 70, the refueling water tank 30, and the first injection unit to discharge heat from the core.

Optionally, as shown in fig. 2, the system further includes a second injection unit 100, where the second injection unit 100 is disposed inside the containment vessel 80;

the second injection unit includes a safety injection tank 101, a second isolation valve 102, and a second check valve 103, wherein:

the first end of the safety injection tank 101 is connected with the first end of the second isolation valve 102, the second end of the second isolation valve 102 is connected with the first end of the second check valve 103, and the second end of the second check valve 103 is communicated with the second pipeline 12.

Specifically, the compressed inert gas may be stored in the upper portion of the interior of the safety injection tank 101, and after the pressure of the primary circuit is reduced by the steam discharge unit 60, the solution in the safety injection tank 101 may be injected into the second pipe 12 through the second isolation valve 102 and the second check valve 103, and finally flow into the pressure vessel 10 to reduce the temperature of the pressure vessel 10.

In this embodiment, the first end of the safety tank 101 is connected to the first end of the second isolation valve 102, the second end of the second isolation valve 102 is connected to the first end of the second check valve 103, and the second end of the second check valve 103 is communicated with the second pipe 12, so that the solution in the safety tank 101 can also be used as a coolant for the core in the pressure vessel 10, thereby preventing the core from melting due to insufficient cooling water injected by the first injection unit 40, and improving the safety of the nuclear power plant safety system.

Alternatively, as shown in fig. 2, the steam discharging unit 60 includes an atmospheric vent valve 61, and the third end of the steam generator 20 is connected to the first end of the atmospheric vent valve 61.

In this embodiment, the steam output from the steam generator 20 can be directly discharged to the atmosphere through the atmospheric discharge valve 61, so as to achieve the heat derivation and pressure reduction functions.

Optionally, as shown in fig. 2, the system further includes a third isolation valve 21 and a fourth isolation valve 22, the third isolation valve 21 and the fourth isolation valve 22 are both disposed outside the containment vessel 80, a third end of the steam generator 20 is connected to a first end of the third isolation valve 21 through a seventh pipe 23, a first end of the fourth isolation valve 22 is connected to a fourth end of the steam generator 20 through an eighth pipe 24, and the seventh pipe 23 is communicated with a first end of the atmospheric vent valve 61.

In this embodiment, the seventh pipe 23 may be a main steam pipe for outputting steam generated by the steam generator 20, the eighth pipe 24 may be a main water supply pipe for supplying water for generating steam to the steam generator 20, the first end of the third isolation valve 21 is connected to the third end of the steam generator 20 through the seventh pipe 23, and the first end of the fourth isolation valve 22 is connected to the fourth end of the steam generator 20 through the eighth pipe 24, thereby achieving heat dissipation in both circuits.

Optionally, as shown in fig. 2, the system further includes a waste heat discharging unit 120, the waste heat discharging unit 120 is disposed outside the containment vessel 80, the waste heat discharging unit 120 includes a second water tank 121 and a second heat exchanger 122, and the second heat exchanger 122 is disposed inside the second water tank 121, where:

the seventh pipeline 23 is communicated with the first end of the second heat exchanger 122 through a ninth pipeline 123, the second end of the second heat exchanger 122 is communicated with the eighth pipeline 24 through a tenth pipeline 124, a fifth isolation valve 125 is arranged on the ninth pipeline 123, and a sixth isolation valve 126 and a third check valve 127 are arranged on the tenth pipeline 124.

Specifically, the second water tank 121 may be disposed at a position above the containment vessel 80, for example: after the third isolation valve 21 and the fourth isolation valve 22 are isolated, the fifth isolation valve 125 and the sixth isolation valve 126 are opened, the steam generated in the steam generator 20 may enter the second heat exchanger 122 through the seventh pipe 23 and the ninth pipe 123 to be condensed, the condensed water may return to the steam generator 20 through the eighth pipe 24 and the tenth pipe 124, and a unidirectional flow of the medium in the tenth pipe 124 may be ensured by the third check valve 127.

In addition, in the second heat exchanger 122, the density difference between the hot steam and the liquid water can drive the flow of the medium in the pipe, and the second heat exchanger 122 can be a C-type heat exchanger, which increases the contact area of the heat exchange pipe and improves the heat conduction effect.

Optionally, as shown in fig. 2, the system further includes a separator 131 and a third heat exchanger 132, the separator 131 is disposed outside the containment vessel 80, the third heat exchanger 132 is disposed inside the containment vessel 80, and the separator 131 is disposed inside the second water tank 121;

a first end of the third heat exchanger 132 is connected to a first end of the separator 131, a second end of the separator 131 is connected to a first end of the second water tank 121, and a second end of the second water tank 121 is connected to a second end of the third heat exchanger 132.

The containment vessel may be a shell building isolated from the external environment, such as: the reactor pressure vessel and part of the safety system are completely isolated from the external environment by the housing building, the safety plant, the containment building or the enclosing body containing most of systems and equipment of the nuclear steam supply system, so that the function of a safety protection barrier is realized. In addition, the second water tank 121 may be annularly disposed along the outer wall of the containment vessel, and may serve as a cold source for heat conduction of the second heat exchanger 122, and may also serve as a cold source for heat conduction of the third heat exchanger 132.

The third heat exchanger 132 may be used to conduct heat inside the containment vessel 80 to the outside, for example: since the containment vessel 80 is a closed space, the temperature inside the containment vessel will also rise in the later period of an accident, when the temperature inside the containment vessel 80 rises to a certain value, the water flowing from the second water tank 121 to the third heat exchanger 132 will absorb heat and vaporize, and the density difference between the vaporized water and the liquid water will drive the vaporized water to enter the separator 131, and become liquid through the separation of the separator 131 and return to the second water tank 121.

In this embodiment, the water in the second water tank 121 flows into the third heat exchanger 132, and due to the steam generated at a high temperature, the steam is condensed into a liquid state by the separator 131 disposed in the second water tank 121 and then returns to the second water tank 121, so that the heat inside the containment vessel can be discharged, and the safety of the safety system of the nuclear power plant can be improved.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Further, it should be noted that the scope of the methods and apparatus of the embodiments of the present application is not limited to performing the functions in the order illustrated or discussed, but may include performing the functions in a substantially simultaneous manner or in a reverse order based on the functions involved, e.g., the methods described may be performed in an order different than that described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

While the present embodiments have been described with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments described above, which are meant to be illustrative and not restrictive, and that various changes may be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. A nuclear power station safety system is characterized by comprising a pressure vessel, a steam generator, a refueling water tank, a first injection unit, a boron injection unit, a steam discharge unit and a pressure relief unit, wherein the pressure vessel, the steam generator, the refueling water tank and the pressure relief unit are arranged inside a containment, and the first injection unit, the boron injection unit and the steam discharge unit are arranged outside the containment;

the first end of the pressure vessel is connected with the first end of the steam generator through a first pipeline, and the second end of the steam generator is connected with the second end of the pressure vessel through a second pipeline;

the first pipeline through the third pipeline with the first end of first injection unit is linked together, the first end of reloading water tank is connected the first end of first injection unit, the second end of first injection unit is connected pressure vessel's third end, the first end of boron notes unit is connected pressure vessel's third end, steam generator's third end is connected the first end of steam exhaust unit, the first pipeline with the first end of pressure release unit is linked together, the second end of pressure release unit is connected the second end of reloading water tank.

2. The nuclear power plant safety system of claim 1, wherein the first injection unit includes a safety injection pump and a first heat exchanger, the second conduit communicates with a first end of the safety injection pump through the third conduit, a first end of the refueling water tank is connected to the first end of the safety injection pump, and a second end of the safety injection pump is connected to the first end of the first heat exchanger;

the second end of the first heat exchanger is connected with the third end of the pressure vessel through a fourth pipeline, or the second end of the first heat exchanger is respectively communicated with the first pipeline and the second pipeline through the fourth pipeline.

3. The nuclear power plant safety system of claim 2, wherein a reactor cavity is provided outside the pressure vessel, the system further comprising a reactor cavity flooding pump and a first water tank, wherein:

the first end of the first water tank is communicated with the fourth pipeline through a fifth pipeline, the first end of the first water tank is connected with the first end of the reactor cavity through a sixth pipeline, a first isolation valve and a first check valve are arranged on the sixth pipeline, and the third end of the refueling water tank is connected with the first end of the reactor cavity water injection pump;

and the second end of the reactor cavity water injection pump is connected with the first end of the reactor cavity, or the second end of the reactor cavity water injection pump is communicated with the third pipeline.

4. The nuclear power plant safety system of claim 2, wherein the boron injection unit includes a boron tank and a boron injection pump, a first end of the boron tank being connected to a first end of the boron injection pump;

and the second end of the boron injection pump is connected with the third end of the pressure vessel, or the second end of the boron injection pump is communicated with the fourth pipeline.

5. The nuclear power plant safety system of claim 1, wherein the pressure relief unit comprises a pressure regulator and a pressure relief device, wherein:

the first pipeline is communicated with the first end of the voltage stabilizer, the second end of the voltage stabilizer is connected with the first end of the pressure relief device, and the second end of the pressure relief device is connected with the second end of the refueling water tank.

6. The nuclear power plant safety system of claim 1, further comprising a second injection unit disposed inside the containment vessel;

the second injection unit includes ann's notes case, second isolating valve and second check valve, wherein:

the first end of the safety injection box is connected with the first end of the second isolation valve, the second end of the second isolation valve is connected with the first end of the second check valve, and the second end of the second check valve is communicated with the second pipeline.

7. The nuclear power plant safety system of claim 1, wherein the steam vent unit includes an atmospheric vent valve, and the third end of the steam generator is connected to the first end of the atmospheric vent valve.

8. The nuclear power plant safety system of claim 7, further comprising a third isolation valve and a fourth isolation valve, the third and fourth isolation valves each disposed outside the containment vessel, the third end of the steam generator connected to the first end of the third isolation valve by a seventh conduit, the first end of the fourth isolation valve connected to the fourth end of the steam generator by an eighth conduit, the seventh conduit in communication with the first end of the atmospheric vent valve.

9. The nuclear power plant safety system of claim 8, further comprising a residual heat removal unit disposed outside the containment, the residual heat removal unit including a second water tank and a second heat exchanger, and the second heat exchanger disposed inside the second water tank, wherein:

the seventh pipeline is communicated with the first end of the second heat exchanger through a ninth pipeline, the second end of the second heat exchanger is communicated with the eighth pipeline through a tenth pipeline, a fifth isolation valve is arranged on the ninth pipeline, and a sixth isolation valve and a third check valve are arranged on the tenth pipeline.

10. The nuclear power plant safety system as recited in claim 9, further comprising a separator and a third heat exchanger, the separator disposed outside the containment vessel, the third heat exchanger disposed inside the containment vessel, and the separator disposed inside the second water tank;

the first end of the third heat exchanger is connected with the first end of the separator, the second end of the separator is connected with the first end of the second water tank, and the second end of the second water tank is connected with the second end of the third heat exchanger.

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