CN220933769U - Nuclear power plant safety injection system - Google Patents

Abstract

The utility model relates to a safe injection system of a nuclear power plant, which is applied to a nuclear power system, wherein the nuclear power system comprises a reactor pressure vessel, a cold pipe section and a hot pipe section of a loop; the safety injection system comprises: the full-pressure water supplementing tank, the safety injection tank with the top filled with pressure accumulating nitrogen, the material changing water tank and the high-pressure safety injection pump; the inlet of the full-pressure water supplementing tank is connected with the cold pipe section through a pressure balance pipeline; the bottom of the full-pressure water supplementing tank is provided with a water supplementing tank water outlet, and the water supplementing tank water outlet is provided with a water outlet valve and is connected to the pressure vessel through a pressure vessel direct injection pipeline; the bottom of the safety injection box is provided with a safety injection box water outlet which is connected to the pressure vessel through a pressure vessel direct injection pipeline; the high-pressure safety injection pump is connected between the refueling water tank and the pressure vessel direct injection pipeline. The purpose of reducing the release of radioactive liquid caused by the rupture of the heat transfer tube while meeting the coolant requirement of the pressure vessel in the event of loss of the primary circuit coolant or rupture of the heat transfer tube of the steam generator is achieved.

Description

Nuclear power plant safety injection system

Technical Field

The utility model relates to the technical field of nuclear safety, in particular to a safety injection system of a nuclear power plant.

Background

Loss of coolant accident (LOCA) and steam generator heat transfer tube rupture accident (SGTR) in a reactor nuclear power plant are important design basis accidents. The coolant safety injection system is generally used for emergency cooling and boration of the core after a LOCA accident to control and mitigate the accident, preventing the expansion to over design benchmark accidents.

When a loop coolant loss accident occurs, the pressure of the loop is reduced, and the loop needs to be supplemented with coolant in time, and the accident alleviation means is that the loop is supplemented with coolant through a safety injection system, and the pressure of the loop is gradually increased along with the injection of the coolant. However, after a reactor has a steam generator heat transfer tube rupture event, the primary circuit of radioactive liquid will be discharged to the environment through the heat transfer tube rupture to the secondary circuit of the steam generator, the primary means of accident mitigation of which is to reduce the primary circuit pressure and thereby maintain the primary and secondary circuit pressure balance.

Thus, if the safety injection system has less injection in the high pressure section of the first circuit, it may not be possible to replenish lost coolant of the first circuit, resulting in overheating of the core; if there is more injection in the high pressure section, it may result in the release of too much radioactive liquid to the environment. In the prior art, the high-pressure safety injection pump is triggered when the pressure of the loop is reduced, and due to the pressure head effect of the high-pressure safety injection pump, the high-pressure safety injection pump is more in injection at the high-pressure section of the loop, and the lost coolant of the loop can be supplemented, but excessive radioactive liquid is highly likely to be released to the environment, so that the accidents that the lost coolant of the loop and the heat transfer pipe of the steam generator are broken cannot be well solved.

Disclosure of utility model

The utility model aims to solve the technical problem of providing a safe injection system of a nuclear power plant.

The technical scheme adopted for solving the technical problems is as follows: a nuclear power plant safety injection system is constructed.

In the safety injection system of the nuclear power plant, the safety injection system is applied to a nuclear power system, and the nuclear power system comprises a reactor pressure vessel, a cold pipe section and a hot pipe section of a loop; the safety injection system includes: the full-pressure filling tank is arranged in the containment, the top of the full-pressure filling tank is filled with pressure-accumulating nitrogen, the full-pressure filling tank is provided with a material-changing water tank, and the full-pressure filling pump is arranged outside the containment;

the inlet of the full-pressure water supplementing tank is connected with the cold pipe section through a pressure balance pipeline; the bottom of the full-pressure water supplementing tank is provided with a water supplementing tank water outlet, and the water supplementing tank water outlet is provided with a water outlet valve and is connected to the pressure container through a pressure container direct injection pipeline;

The bottom of the safety injection box is provided with a safety injection box water outlet which is connected to the pressure container through a pressure container direct injection pipeline;

The high-pressure safety injection pump is connected between the refueling water tank and the pressure vessel direct injection pipeline.

Preferably, the inlet of the full-pressure water supplementing tank is arranged at the top of the tank body of the full-pressure water supplementing tank; the pressure balance pipeline is a normally open pipeline.

Preferably, the refueling water tank is arranged at a pit position below the reactor pressure vessel; the high-pressure safety injection pump takes coolant from the refueling water tank through a pit filter screen and a water taking pipeline and injects the coolant into the pressure container to be directly injected into the pipeline.

Preferably, the safety injection box water outlet of the safety injection box is provided with a check valve for preventing the coolant from flowing back.

Preferably, the safety injection system further comprises: a pressure sensor connected to the hot pipe section; the pressure sensor measures the pressure of the first circuit.

Preferably, the safety injection system further comprises a level gauge; the liquid level meter monitors the liquid level of the coolant stored in the full-pressure water supplementing tank.

Preferably, the nuclear power system comprises a reactor cooling system and a steam generator; the hot pipe section for coolant flow from the reactor pressure vessel to the steam generator; the cold leg provides for the coolant to flow from the reactor cooling system to the reactor pressure vessel.

Preferably, the full pressure water replenishing tank is passive; the full-pressure water supplementing tank comprises a first full-pressure water supplementing tank and a second full-pressure water supplementing tank which are mutually independent;

The water outlet of the first full-pressure water supplementing tank is connected to a direct injection pipeline of the first pressure container; the inlet of the first full-pressure water supplementing tank is directly connected with the first cold pipe section through a first pressure balance pipeline;

The water outlet of the second full-pressure water supplementing tank is connected to a direct injection pipeline of the second pressure container; the inlet of the second full-pressure water supplementing tank is directly connected with the second cold pipe section of the first loop through a second pressure balance pipeline.

Preferably, the safety injection box is passive; the safety injection box comprises a first safety injection box and a second safety injection box which are mutually independent;

The water outlet of the first safety injection box is connected to the first pressure container direct injection pipeline; the water outlet of the second safety injection box is connected to the direct injection pipeline of the second pressure container.

Preferably, the high-pressure safety injection pump comprises a first high-pressure safety injection pump and a second high-pressure safety injection pump which are mutually independent;

The first high-pressure safety injection pump is arranged between the first pressure container direct injection pipeline and the material changing water tank;

The second high-pressure safety injection pump is arranged between the second pressure container direct injection pipeline and the material changing water tank.

The nuclear power plant safety injection system has the following beneficial effects: the inlet of the full-pressure water supplementing tank is connected with a cold pipe section of a loop through a pressure balance pipeline; the bottom of the full-pressure water supplementing tank is provided with a water supplementing tank water outlet, and the water supplementing tank water outlet is provided with a water outlet valve and is connected to the pressure vessel through a pressure vessel direct injection pipeline; the technical effect that coolant can be timely supplemented to the pressure vessel when the pressure of the primary loop is reduced is achieved, and the coolant supplementing requirement of the reactor core can be met under the normal working condition; the bottom of the safety injection box with the top filled with pressure-accumulating nitrogen is provided with a safety injection box water outlet which is connected to a pressure container through a pressure container direct injection pipeline; when the pressure of the first loop is reduced to the nitrogen pressure, the coolant stored in the first loop is injected into the pressure vessel, so that the coolant replenishing requirement of the reactor core is met; the high-pressure safety injection pump is connected between the refueling water tank and the pressure vessel direct injection pipeline. The purpose of reducing the release of radioactive liquid caused by the rupture of the heat transfer tube while meeting the coolant requirement of the pressure vessel in the event of loss of the primary circuit coolant or rupture of the heat transfer tube of the steam generator is achieved.

Drawings

The utility model will be further described with reference to the accompanying drawings and examples, in which:

fig. 1 is a schematic structural diagram of a safe injection system of a nuclear power plant according to an embodiment of the present utility model.

Detailed Description

For a clearer understanding of technical features, objects and effects of the present utility model, a detailed description of embodiments of the present utility model will be made with reference to the accompanying drawings.

As shown in fig. 1, in a first embodiment of the safety injection system of a nuclear power plant of the present utility model, the nuclear power system includes a cold leg, a hot leg, and a reactor pressure vessel 7 of a loop. The safety injection system further comprises: the full-pressure water supplementing tank 1 is arranged in the containment 8 of the nuclear power plant, the top of the full-pressure water supplementing tank is filled with pressure-accumulating nitrogen, the full-pressure water supplementing tank is filled with pressure-accumulating nitrogen, and the full-pressure water supplementing tank is filled with pressure-accumulating nitrogen;

The inlet of the full-pressure water supplementing tank 1 is connected with a cold pipe section through a pressure balance pipeline 5; the bottom of the full-pressure water supplementing tank 1 is provided with a water supplementing tank water outlet which is provided with a water outlet valve and is connected to a reactor pressure vessel 7 through a pressure vessel direct injection pipeline 4;

the bottom of the safety injection box 3 is provided with a safety injection box water outlet which is connected to a reactor pressure vessel 7 through a pressure vessel direct injection pipeline 4; the high pressure safety injection pump 2 is connected between the refueling water tank 6 and the pressure vessel direct injection line 4.

In some embodiments, the full pressure make-up tank 1 is passive; the inlet of the full-pressure water supplementing tank 1 is arranged at the top of the tank body of the full-pressure water supplementing tank 1, cooling water is stored in the full-pressure water supplementing tank 1, and the inlet of the full-pressure water supplementing tank 1 is connected with the cold pipe section through a pressure balance pipeline 5. The pressure balance pipeline 5 is a normally open pipeline.

In some embodiments, the safety injection tank 3 is passive; the safety injection box water outlet of the safety injection box 3 filled with pressure-accumulating nitrogen at the top is arranged at the bottom and is connected to the pressure vessel direct injection pipeline 4 through a pipeline provided with a check valve and/or a water outlet valve. When the pressure of the primary loop is reduced to the nitrogen pressure in the safety injection box 3, namely the pressure at the water outlet of the safety injection box is lower than the nitrogen pressure in the safety injection box, under the action of the accumulated nitrogen, cooling water in the safety injection box 3 can automatically flow to the pressure container from the water outlet at the bottom to be directly injected into the pipeline 4. Wherein the pressure of nitrogen in the injection box 3 is 5.0MPa. It will be appreciated that the pressure of the nitrogen gas in the tank may be any pressure value in the range 4.5 to 5.0MPa.

In some embodiments, the reloading water tank 6 is built in the containment 8, the inside of the reloading water tank 6 is stored with cooling water, and the reloading water tank 6 is arranged at the pit position below the reactor pressure vessel 7, so that the influence of external disasters on the safety of the reloading water tank 6 can be reduced, and the reliability of emergency water sources after accidents is improved. The high-pressure safety injection pump 2 is active; the high-pressure safety injection pump 2 is connected between the refueling water tank 6 and the pressure vessel direct injection pipeline 4, and when the safety injection is started by the high-pressure safety injection pump 2, the high-pressure safety injection pump 2 takes water from the refueling water tank 6 through a pit filter screen and a water taking pipeline and continuously injects cooling water into the pressure vessel through the pressure vessel direct injection pipeline 4. It will be appreciated that the implementation of the mobility of the high pressure injection pump 2 may be referred to the prior art.

In addition, as shown in FIG. 1, the nuclear power system includes a Steam Generator (SG) that isolates the primary and secondary circuits; the nuclear power system further includes a reactor cooling system (RCP); the cold leg is connected to a coolant outlet of the reactor cooling system through which coolant flows from the reactor cooling system to the reactor pressure vessel 7. The steam generator is connected between the reactor coolant system and the hot pipe section, and coolant which absorbs heat of the reactor core in the reactor pressure vessel 7 flows from the reactor pressure vessel 7 to the steam generator heat transfer pipe through the hot pipe section; the steam generator sub-cools the coolant and transfers heat to the secondary side of the steam generator to circulate the coolant in a circuit.

In some embodiments, the safety injection system further comprises a pressure sensor; the pressure sensor is arranged on a hot pipe section of the loop and is used for measuring the pressure of the loop so as to timely send out an injection signal when the pressure of the loop is reduced to the starting pressure of the full-pressure water supplementing tank 1, and further the water outlet valve of the full-pressure water supplementing tank 1 is opened; and/or when the pressure of the loop is reduced to the nitrogen pressure of the safety injection box 3, timely sending out a safety injection signal to enable the water outlet valve of the safety injection box 3 to be automatically opened. It is understood that the water outlet valve is an electric valve and is connected with the pressure sensor. It will be appreciated that pressure sensor measurement, processing, and signal output may be referred to in the art.

In some embodiments, the safety injection system further comprises a level gauge connected to the high pressure safety injection pump 2 and the full pressure makeup tank 1, by measuring the level of cooling water stored in the full pressure makeup tank 1 in real time. When the liquid level of the cooling water in the full-pressure water supplementing tank 1 for supplementing water gradually decreases to 15% of the initial liquid level, that is, a signal of low water level appears, and the cooling water in the full-pressure water supplementing tank 1 is insufficient to support the water injection requirement of the reactor pressure vessel 7, the high-pressure safety injection pump 2 is started to continuously inject the cooling water into the reactor pressure vessel 7 so as to meet the cooling requirement of the reactor core.

In some embodiments, the full pressure tank 1 includes a first full pressure tank 11 and a second full pressure tank 12 that are disposed independently of each other; the water outlet of the first full pressure make-up tank 11 is connected to a first pressure vessel direct injection line 41; the inlet of the first full pressure water supplementing tank 11 is directly connected with the first cold pipe section through a first pressure balance pipeline 51; the outlet of the second full pressure make-up tank 12 is connected to a second pressure vessel direct injection line 42; the inlet of the second full pressure makeup tank 12 is directly connected to the second cold leg of the circuit by a second pressure balance line 52.

The safety injection box 3 comprises a first safety injection box 31 and a second safety injection box 32 which are mutually independent; the water outlet of the first safety injection box 31 is connected to a first pressure vessel direct injection line 41; the water outlet of the second safety injection tank 32 is connected to a second pressure vessel direct injection line 42.

The high-pressure safety injection pump 2 comprises a first high-pressure safety injection pump 21 and a second high-pressure safety injection pump 22 which are arranged independently; the first high pressure safety injection pump 21 is arranged between the first pressure vessel direct injection line 41 and the refueling water tank 6; the second high pressure safety injection pump 22 is arranged between the second pressure vessel direct injection line 42 and the refueling water storage tank 6.

It will be appreciated that the safety injection system provided by the utility model comprises two rows of mutually independent full pressure water replenishing tanks 1, safety injection tanks 3 and high pressure safety injection pumps 2 for replenishing the reactor pressure vessel with coolant, as shown in fig. 1. Typically, the primary coolant loop is of a three-loop design, with three inlet and three outlet nozzles on the reactor pressure vessel 7, connected to the cold and hot sections of each cooling loop, respectively.

In one embodiment, as shown in FIG. 1, one of the cooling loops is taken as an example:

when a loss of coolant accident occurs, the coolant of the primary circuit is lost, resulting in a pressure drop of the primary circuit, and the reactor core is not cooled well. At the moment, the full-pressure water supplementing tank 1, the safety injection tank 3 and the high-pressure safety injection pump 2 are used for injecting water into the reactor pressure vessel 7, so that the water filling amount can be quickly supplemented, the purpose of reactor protection is achieved, and the reactor core is cooled in time.

A first full pressure makeup tank 11 is provided within the containment vessel 8, the inlet of the first full pressure makeup tank 11 being connected by a first pressure balance line 51 to a cold pipe section of a primary circuit in which loss of coolant occurs; the water replenishing tank water outlet of the first full-pressure water replenishing tank 11 is arranged at the bottom of the first full-pressure water replenishing tank 11 and is connected to the first pressure container direct injection pipeline 41, and the water replenishing tank water outlet is provided with a water outlet valve.

When the safety injection system generates a safety injection signal, namely, the pressure of the primary circuit is reduced and the pressure is reduced to the starting pressure of the full-pressure water supplementing tank 1, a water outlet valve of the first full-pressure water supplementing tank 11 is automatically opened, the coolant in the first full-pressure water supplementing tank 11 directly flows out from a water supplementing tank outlet at the bottom to a first pressure container direct injection pipeline 41, and the coolant is supplemented to the reactor pressure container 7 through the first pressure container direct injection pipeline 41. Wherein the first full pressure water compensating tank 11 is passive, and the inlet of the top of the first full pressure water compensating tank 11 is connected to the first circuit cold pipe section through the first pressure balance line 51, so that the pressure inside the first full pressure water compensating tank 11 and the pressure of the cold pipe section are kept in a balance state, and the coolant inside the first full pressure water compensating tank 11 can smoothly flow out from the water compensating tank outlet.

In addition, a first safety injection box 31 is arranged in the safety shell 8, and the bottom of the first safety injection box 31 is provided with only a safety injection box water outlet which is connected to a first pressure vessel direct injection pipeline 41 through a pipeline provided with a check valve; the first tank 31 has nitrogen gas stored therein and a coolant stored therein. When the pressure of the primary loop drops below the nitrogen pressure in the first safety injection tank 31, the first safety injection tank 31 automatically injects the boron-containing coolant stored in the first safety injection tank 31 into the reactor pressure vessel 7 through the first pressure vessel direct injection pipeline 41 under the action of the accumulated nitrogen, so that the reactor core can meet the coolant requirement.

Under the working condition of the vast majority of design reference accidents, the boron-containing coolant is supplemented to the pressure container through the first full-pressure water supplementing tank 11 until the pressures of the first loop and the second loop reach balance, and the water outlet valve of the first full-pressure water supplementing tank 11 is closed to stop water supplementing. At this time, the coolant stored in the first full pressure makeup tank 11 is sufficient for the reactor core to meet the cooling requirements. Under the serious condition of loss of coolant, as the coolant stored in the first full-pressure water supplementing tank 11 is injected into the reactor pressure vessel 7, the water level of the cooling water in the first full-pressure water supplementing tank 11 gradually decreases, which is insufficient to meet the cooling requirement of the reactor core, and at the moment, the first high-pressure safety injection pump 21 is triggered to start.

The first high pressure safety injection pump 21 is arranged outside the containment vessel 8, after the low water level signal of the first full pressure water supplementing tank 11 appears, the first high pressure safety injection pump 21 is started, coolant is taken from the refueling water tank 6 through a pit filter screen and a water taking pipeline, and is injected into the first pressure vessel direct injection pipeline 41 through a pipeline provided with a valve, and the coolant is continuously and stably supplemented to the reactor pressure vessel 7 so as to continuously meet the core coolant requirement of the reactor pressure vessel 7.

In another embodiment, as shown in FIG. 1:

when the steam generator heat transfer pipe breaks, the radioactive liquid in the primary loop is discharged to the secondary side of the steam generator in the secondary loop through the break of the steam generator heat transfer pipe so as to be discharged to the environment in a radioactive way, so that the primary loop coolant is lost, the secondary side of the broken steam generator is polluted, and the reactor is in emergency shutdown and the steam turbine is tripped. At this time, main water supply isolation and auxiliary water supply operation are needed to meet the coolant requirement of the reactor core.

A first full pressure makeup tank 11 is provided within the containment vessel 8, the inlet of the first full pressure makeup tank 11 being connected by a first pressure balance line 51 to a cold pipe section of a primary circuit in which loss of coolant occurs; the water replenishing tank water outlet of the first full-pressure water replenishing tank 11 is arranged at the bottom of the first full-pressure water replenishing tank 11 and is connected to the first pressure container direct injection pipeline 41, and the water replenishing tank water outlet is provided with a water outlet valve.

When the safety injection system generates an safety injection signal, namely, the pressure of the first loop is reduced and is reduced to the starting pressure of the first full-pressure water supplementing tank 11, a water outlet valve of the first full-pressure water supplementing tank 11 is automatically opened, the coolant in the first full-pressure water supplementing tank 11 directly flows out from a water supplementing tank outlet at the bottom to a first pressure container direct injection pipeline 41, and the boron-containing coolant is supplemented to the reactor pressure container through the first pressure container direct injection pipeline 41. Wherein the first full pressure water compensating tank 11 is passive, and the inlet of the top of the first full pressure water compensating tank 11 is connected to a cold pipe section of a loop through a first pressure balancing line 41, so that the pressure inside the first full pressure water compensating tank 11 and the pressure of the cold pipe section are kept in a balanced state, and the coolant inside the first full pressure water compensating tank 11 can smoothly flow out from the outlet of the water compensating tank.

In addition, a first safety injection box 31 is arranged in the safety shell 8, and the bottom of the first safety injection box 31 is provided with only a safety injection box water outlet which is connected to a first pressure vessel direct injection pipeline 41 through a pipeline provided with a check valve; the first tank 31 has nitrogen gas stored therein and a coolant stored therein. When the pressure of the primary loop drops below the nitrogen pressure in the first safety injection tank 31, the first safety injection tank 31 automatically injects the boron-containing coolant stored in the first safety injection tank 31 into the reactor pressure vessel 7 through the first pressure vessel direct injection pipeline 41 under the action of the accumulated nitrogen, so that the reactor core can meet the coolant requirement.

In normal cases, the coolant stored in the first full-pressure water supplementing tank 11 can meet the demand of the core coolant for a long time, and when the pressure difference between the first loop and the second loop is balanced, the water supplementing of the first full-pressure water supplementing tank 11 to the reactor pressure vessel 7 is automatically stopped, and the water outlet valve of the water outlet of the water supplementing tank is closed; during this period, since the first high-pressure injection pump 21 is not triggered to start temporarily, the pressure head of the first high-pressure injection pump 21 is not used, and the technical effect of replenishing the coolant to the core and greatly reducing the radioactive release of the broken loop can be achieved.

After the first full-pressure water replenishing tank 11 has a low water level signal, the first high-pressure safety injection pump 21 is started, takes coolant from the refueling water tank 6 through a pit filter screen and a water intake pipeline, and injects the coolant into the first pressure vessel direct injection pipeline 41 through a pipeline provided with a valve, so as to continuously and stably replenish the coolant to the reactor pressure vessel 7. Different requirements on the safety injection system under LOCA and SGTR accidents can be effectively balanced, and the purpose of reactor protection is effectively achieved.

In which a circuit whose pressure drops due to loss of coolant is gradually increased by injection of the first full-pressure tank 11, a circuit pressure may be released radially to the environment. However, because the first full-pressure water supplementing tank 11 is started before the first high-pressure safety injection pump 21 is started, when the first high-pressure safety injection pump 21 is not started, the pressure head effect of the first high-pressure safety injection pump 21 is not provided, so that the time for delaying the overflow of the steam generator to a large extent can be met, the overflow risk of the steam generator can be reduced, the flow rate released to the environment in the case of the breakage accident of the heat transfer tube of the steam generator can be reduced, the excessive pressure difference between the first circuit and the second circuit is avoided, and the design of artificially expanding the break by the automatic pressure relief system arranged in the first circuit is avoided; the safety performance of the nuclear power plant reactor is improved.

It will be appreciated that, referring to the two embodiments, the other coolant loop implements the pressure vessel coolant replenishment through the second full pressure replenishment tank 12, the second safety injection tank 32, the second high pressure safety injection pump 21, the second pressure balance line 52 and the second pressure vessel direct injection line 42, and the implementation, connection and the like of the two embodiments are similar or identical to those of the two embodiments, and will not be repeated.

It is to be understood that each embodiment is described in an incremental manner, and each embodiment is mainly described in a different manner from other embodiments, and identical and similar parts between the embodiments are referred to each other. The foregoing examples illustrate only a few embodiments of the present utility model and are described in detail herein without thereby limiting the scope of the utility model; it should be noted that, for a person skilled in the art, the above technical features can be freely combined, and several variations and modifications can be made without departing from the scope of the utility model; therefore, all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (10)

1. A nuclear power plant safety injection system for use in a nuclear power system including a reactor pressure vessel, a cold leg and a hot leg of a circuit, the safety injection system comprising: the full-pressure filling tank is arranged in the containment, the top of the full-pressure filling tank is filled with pressure-accumulating nitrogen, the full-pressure filling tank is provided with a material-changing water tank, and the full-pressure filling pump is arranged outside the containment;

the inlet of the full-pressure water supplementing tank is connected with the cold pipe section through a pressure balance pipeline; the bottom of the full-pressure water supplementing tank is provided with a water supplementing tank water outlet, and the water supplementing tank water outlet is provided with a water outlet valve and is connected to the pressure container through a pressure container direct injection pipeline;

The bottom of the safety injection box is provided with a safety injection box water outlet which is connected to the pressure container through a pressure container direct injection pipeline;

The high-pressure safety injection pump is connected between the refueling water tank and the pressure vessel direct injection pipeline.

2. The nuclear power plant safety injection system of claim 1, wherein the inlet of the full pressure make-up tank is disposed at a tank top of the full pressure make-up tank; the pressure balance pipeline is a normally open pipeline.

3. The nuclear power plant safety injection system of claim 1, wherein the refueling water tank is disposed at a pit location below the reactor pressure vessel; the high-pressure safety injection pump takes coolant from the refueling water tank through a pit filter screen and a water taking pipeline and injects the coolant into the pressure container to be directly injected into the pipeline.

4. The nuclear power plant safety injection system of claim 1, wherein the safety injection tank outlet of the safety injection tank is provided with a check valve that prevents backflow of coolant.

5. The nuclear power plant safety injection system of claim 1, further comprising: a pressure sensor connected to the hot pipe section; the pressure sensor measures the pressure of the first circuit.

6. The nuclear power plant safety injection system of claim 1, further comprising a level gauge; the liquid level meter monitors the liquid level of the coolant stored in the full-pressure water supplementing tank.

7. The nuclear power plant safety injection system of claim 1, wherein the nuclear power system comprises a reactor cooling system and a steam generator; the hot pipe section for coolant flow from the reactor pressure vessel to the steam generator; the cold leg provides for the coolant to flow from the reactor cooling system to the reactor pressure vessel.

8. The nuclear power plant safety injection system of claim 1, wherein the full pressure make-up tank is passive; the full-pressure water supplementing tank comprises a first full-pressure water supplementing tank and a second full-pressure water supplementing tank which are mutually independent;

The water outlet of the first full-pressure water supplementing tank is connected to a direct injection pipeline of the first pressure container; the inlet of the first full-pressure water supplementing tank is directly connected with the first cold pipe section through a first pressure balance pipeline;

The water outlet of the second full-pressure water supplementing tank is connected to a direct injection pipeline of the second pressure container; the inlet of the second full-pressure water supplementing tank is directly connected with the second cold pipe section of the first loop through a second pressure balance pipeline.

9. The nuclear power plant safety injection system of claim 8, wherein the safety injection box is passive; the safety injection box comprises a first safety injection box and a second safety injection box which are mutually independent;

The water outlet of the first safety injection box is connected to the first pressure container direct injection pipeline; the water outlet of the second safety injection box is connected to the direct injection pipeline of the second pressure container.

10. The nuclear power plant safety injection system of claim 9, wherein the high pressure safety injection pump comprises a first high pressure safety injection pump and a second high pressure safety injection pump that are disposed independently of each other;

The first high-pressure safety injection pump is arranged between the first pressure container direct injection pipeline and the material changing water tank;

The second high-pressure safety injection pump is arranged between the second pressure container direct injection pipeline and the material changing water tank.