阅读说明：本技术 一种核电站的安全注入系统 (Safe injection system of nuclear power station ) 是由 詹经祥 杨长江 石雪垚 黄树亮 方俊 郑云涛 孙燕宇 陈巧艳 于 2021-06-22 设计创作，主要内容包括：本发明属于核电站安全技术领域,具体涉及一种核电站的安全注入系统,用于为核电站的安全壳(1)内的压力容器(3)注入冷却水并对与压力容器(3)连通的一回路进行降压,一回路由环路构成,环路包括串联的热段(5)和冷段(6),热段(5)和冷段(6)与二回路上的二回路换热器(9)相连,该安全注入系统通过直接注入管线(4)与压力容器(3)连通非能动堆芯补水箱(10)和非能动安注箱(12),设置在热段(5)上的热段卸压阀(15)和稳压器卸压阀(14)。本发明利用稳压器卸压阀(14)和热段卸压阀(15)实现一回路快速非完全降压,并提供非能动和能动组合的安全注入方式,取消了传统的高压安注泵,降低了设备投资和建设成本。(The invention belongs to the technical field of nuclear power station safety, and particularly relates to a safety injection system of a nuclear power station, which is used for injecting cooling water into a pressure container (3) in a containment (1) of the nuclear power station and reducing the pressure of a primary circuit communicated with the pressure container (3), wherein the primary circuit is formed by a loop, the loop comprises a hot section (5) and a cold section (6) which are connected in series, the hot section (5) and the cold section (6) are connected with a two-circuit heat exchanger (9) on the two circuits, the safety injection system is communicated with the pressure container (3) through a direct injection pipeline (4) to form a passive reactor core water supplementing tank (10) and a passive safety injection tank (12), and a hot section pressure relief valve (15) and a pressure stabilizer pressure relief valve (14) which are arranged on the hot section (5). The invention utilizes the pressure relief valve (14) of the voltage stabilizer and the pressure relief valve (15) of the hot section to realize the rapid incomplete pressure reduction of a loop, provides a safe injection mode combining passive and active, cancels the traditional high-pressure safety injection pump, and reduces the equipment investment and the construction cost.)

1. A safety injection system of a nuclear power station is used for injecting cooling water into a pressure container (3) in a containment (1) of the nuclear power station and depressurizing a primary circuit communicated with the pressure container (3), wherein the primary circuit is composed of a loop, the loop comprises a hot section (5) and a cold section (6) which are connected in series, the hot section (5) and the cold section (6) are connected with a two-circuit heat exchanger (9) on the two circuits, and the safety injection system is characterized in that: through direct injection line (4) with pressure vessel (3) intercommunication passive reactor core moisturizing case (10) and passive safe injection case (12), set up hot section relief valve (15) and stabiliser relief valve (14) on hot section (5).

2. A safety injection system for a nuclear power plant as claimed in claim 1, wherein: and the system also comprises an active low-pressure safety injection pipeline (16) which is connected with the pit (2) and the direct injection pipeline (4) and is used for injecting cooling water in the pit (2) into the direct injection pipeline (4).

3. A safety injection system for a nuclear power plant as claimed in claim 1, wherein: and the system also comprises a secondary side passive residual heat removal system (19) connected with the two loops.

4. A safety injection system for a nuclear power plant as claimed in claim 2, wherein:

the number of the direct injection pipelines (4) is 2, and each direct injection pipeline (4) is provided with one passive core water replenishing tank (10) and one passive safety injection tank (12);

the bottom of the passive core water replenishing tank (10) is communicated with the direct injection pipeline (4) through a pipeline, a tank inlet at the top of the passive core water replenishing tank (10) is communicated with the hot section (5) of the loop through a pressure balance pipeline (11), and a valve is arranged on the pressure balance pipeline (11);

the bottom of the passive safety injection box (12) is communicated with the direct injection pipeline (4) through a pipeline.

5. A safety injection system for a nuclear power plant as claimed in claim 3, wherein:

the loops of the loop comprise a first loop, a second loop and a third loop, a voltage stabilizer (13) is communicated with the hot section (5) of the first loop, a voltage stabilizer pressure relief valve (14) is arranged on the voltage stabilizer (13), and the number of the voltage stabilizer pressure relief valves (14) is 3, and the voltage stabilizer pressure relief valves are connected in parallel with each other and used for reducing the pressure of the loop to a low-pressure safety injection pressure head;

the number of the hot section pressure relief valves (15) is 2, the hot section pressure relief valves are respectively communicated with the hot section (5) of the second loop circuit and the hot section (5) of the third loop circuit through a pipeline, and the hot section pressure relief valves (15) are used as redundancy of the pressure stabilizer pressure relief valves (14).

6. A safety injection system for a nuclear power plant as claimed in claim 4, wherein: the number of the active low-pressure safety injection pipelines (16) is 2, each active low-pressure safety injection pipeline (16) is correspondingly communicated with one direct injection pipeline (4), a low-pressure safety injection pump (17) is arranged on each active low-pressure safety injection pipeline (16) and used for providing water injection kinetic energy, and a low-pressure safety injection heat exchanger (18) and a valve are arranged on each active low-pressure safety injection pipeline (16) and used for guiding out heat of the pressure container (3); the low-pressure safety injection pump (17) and the low-pressure safety injection heat exchanger (18) are positioned outside the containment vessel (1).

7. A safety injection system for a nuclear power plant as claimed in claim 5, wherein:

the secondary loop comprises a secondary loop water outlet section (8) and a secondary loop water inlet section (7), and the secondary loop water outlet section (8) and the secondary loop water inlet section (7) are respectively connected with the secondary loop heat exchanger (9);

the first loop, the second loop and the third loop are provided with a set of secondary side passive waste heat discharge system (19);

the secondary side passive waste heat discharge system (19) comprises an ascending pipe section (20), a water tank heat exchanger (21), a cooling water tank (22) and a descending pipe section (23); the cooling water tank (22) is positioned outside the containment vessel (1) and is higher than the position of the two loops; the water tank heat exchanger (21) is positioned in the cooling water tank (22); one end of the ascending pipe section (20) is connected with the water tank heat exchanger (21), and the other end of the ascending pipe section is connected with the two-loop water outlet section (8); one end of the descending pipe section (23) is connected with the water tank heat exchanger (21), and the other end of the descending pipe section is connected with the two-loop water inlet section (7); valves are arranged on the ascending pipe section (20) and the descending pipe section (23); the secondary side passive residual heat removal system (19) is used for reducing the temperature and the pressure of the pressure container (3) and leading out the residual heat of the pressure container (3).

Technical Field

The invention belongs to the technical field of nuclear power station safety, and particularly relates to a safety injection system of a nuclear power station.

Background

The existing special safety injection system for the active nuclear power plant mostly adopts a high-pressure safety injection pump, a safety injection tank and a low-pressure safety injection pump to realize water injection to a primary circuit, mainly adopts an active injection mode, generally does not perform active pressure reduction on the primary circuit, and is shown in a schematic diagram of the special safety injection system for the traditional active nuclear power plant in figure 1. The AP1000 nuclear power plant adopts a reactor core water replenishing tank, a safety injection tank, IRWST gravity injection and long-term recirculation injection full-range passive safe injection mode. An ADS automatic pressure reduction system is arranged for the purpose, and the ADS comprises four stages of valves. The 1 st, 2 nd and 3 rd stage pressure reduction pipelines are respectively provided with 2 groups, each group is connected with a safety valve of the pressure stabilizer in parallel, and the 4 th stage is directly connected with the top of a heat pipe section of a loop by adopting a blasting valve. Due to the fact that a large number of active pumps and related support systems (emergency power supplies and emergency cooling water) are used in the active nuclear power plant, the probability of equipment failure caused by power machinery faults is high, safety of a nuclear power unit is affected, and the probability of damage (CDF) of a reactor core of the nuclear power plant is high. The AP1000 nuclear power plant adopts passive systems and equipment in large quantity, is driven by means of gravity and natural circulation, and has low failure probability. However, the precondition for realizing the full-range passive injection is that a loop system needs to be completely depressurized, namely, the 1 st to 4 th grade valves of the ADS are sequentially opened to reduce the pressure of the loop to be slightly higher than the pressure of a containment vessel, which puts high requirements on the design and manufacture of the ADS-4 grade valves, and the ADS explosion valve belongs to Chinese 'neck' equipment in the United states and has a plurality of problems in domestic manufacture. In addition, the passive injection system has some uncertainties, the containment pit recycles the containment submerging water level to drive the injection core to take away decay heat, the effective driving pressure head is small, and if the problems of pipeline blockage and the like occur, the injection core cannot be injected, and the core damage can be caused.

The cold and hot section injection pipelines of the existing most of nuclear power plant safety injection systems adopt a main pipe connection mode, namely two lines of high-pressure safety injection pump outlets and two lines of low-pressure safety injection pumps are combined into a main pipe, and then three branches are divided to respectively inject cold pipe sections of three loops. Under the accident condition, if the main pipe is broken, two series of water injection can be simultaneously influenced, and the injection safety by adopting the main pipe mode is greatly controversial at present.

In addition, in order to prevent the core boron crystallization in the long-term cooling stage, the active nuclear power plant is provided with cold and hot sections for simultaneous injection, and a safety injection connecting pipe is designed on the cold and hot sections of each loop. After about a few hours after the accident, the operator must establish recirculation through the cold and hot sections. Therefore, the safety injection pipelines are various and complex in arrangement, and more safety injection interfaces need to be arranged on the main pipeline of the primary circuit. And an operator is required to manually switch, so that human misoperation is more easily caused.

In the long-term cooling stage of the reactor core, a general nuclear power plant is provided with a safety injection system and a containment vessel spraying system, wherein the safety injection system is used for supplementing water to the reactor core and guiding out the heat of the reactor core to the containment vessel, and the containment vessel spraying system is used for guiding out the heat in the containment vessel under the accident condition. Therefore, two sets of safety systems are matched to take out the waste heat of the reactor core, and the construction and operation maintenance costs are high.

Disclosure of Invention

Aiming at the defects of the existing specially-designed safety injection system of the traditional active nuclear power plant, the invention aims to provide the safety injection system which adopts a loop rapid non-complete depressurization mode under design basis accidents and design extension working conditions, mainly takes passive injection (a reactor core water supplementing tank and a safety injection tank) and combines an active low-pressure safety injection pump for injection, realizes effective safety injection of the reactor core and continuous heat discharge of the reactor core, ensures the safety of the reactor core, and further improves the safety and the economical efficiency of the nuclear power plant

In order to achieve the above purpose, the technical scheme adopted by the invention is a safety injection system of a nuclear power station, which is used for injecting cooling water into a pressure vessel in a containment vessel of the nuclear power station and reducing the pressure of a primary circuit communicated with the pressure vessel, wherein the primary circuit is composed of a loop, the loop comprises a hot section and a cold section which are connected in series, the hot section and the cold section are connected with two loop heat exchangers on two loops, a passive core water supplementing tank and a passive safety injection tank are communicated with the pressure vessel through direct injection pipelines, and a hot section pressure relief valve and a pressure stabilizer pressure relief valve are arranged on the hot section.

Further, the system also comprises an active low-pressure safety injection pipeline which is connected with the pit and the direct injection pipeline and is used for injecting cooling water in the pit into the direct injection pipeline.

Further, the device also comprises a secondary side passive residual heat removal system connected with the two loops.

Further, in the present invention,

the number of the direct injection pipelines is 2, and each direct injection pipeline is provided with one passive core water replenishing tank and one passive safety injection tank;

the bottom of the passive core water replenishing tank is communicated with the direct injection pipeline through a pipeline, a tank inlet at the top of the passive core water replenishing tank is communicated with the hot section of one loop through a pressure balance pipeline, and a valve is arranged on the pressure balance pipeline;

the bottom of the passive safety injection box is communicated with the direct injection pipeline through a pipeline.

Further, in the present invention,

the loops of the loop comprise a first loop, a second loop and a third loop, the hot section of the first loop is communicated with a voltage stabilizer, the voltage stabilizer pressure relief valves are arranged on the voltage stabilizer, the number of the voltage stabilizer pressure relief valves is 3, the voltage stabilizer pressure relief valves are connected in parallel, and the voltage stabilizer pressure relief valves are used for reducing the voltage of the loop to a low-voltage safety injection pressure head;

the number of the hot section pressure relief valves is 2, the hot section pressure relief valves are respectively communicated with the hot section of the second loop circuit and the hot section of the third loop circuit through a pipeline, and the hot section pressure relief valves are used as redundancy of the pressure stabilizer pressure relief valves.

Furthermore, the number of the active low-pressure safety injection pipelines is 2, each active low-pressure safety injection pipeline is correspondingly communicated with one direct injection pipeline, a low-pressure safety injection pump is arranged on each active low-pressure safety injection pipeline and used for providing water injection kinetic energy, and a low-pressure safety injection heat exchanger and a valve are arranged on each active low-pressure safety injection pipeline and used for guiding out heat of the pressure container; the low-pressure safety injection pump and the low-pressure safety injection heat exchanger are positioned outside the containment vessel.

Further, in the present invention,

the secondary loop comprises a secondary loop water outlet section and a secondary loop water inlet section, and the secondary loop water outlet section and the secondary loop water inlet section are respectively connected with the secondary loop heat exchanger;

the first loop, the second loop and the third loop are provided with a set of secondary side passive waste heat removal systems;

the secondary side passive waste heat discharge system comprises an ascending pipe section, a water tank heat exchanger, a cooling water tank and a descending pipe section; the cooling water tank is positioned outside the containment vessel and is higher than the position of the two loops; the water tank heat exchanger is positioned in the cooling water tank; one end of the ascending pipe section is connected with the water tank heat exchanger, and the other end of the ascending pipe section is connected with the water outlet section of the second loop; one end of the descending pipe section is connected with the water tank heat exchanger, and the other end of the descending pipe section is connected with the water inlet section of the second loop; valves are arranged on the ascending pipe section and the descending pipe section; the secondary side passive waste heat discharge system is used for reducing the temperature and the pressure of the pressure container and leading out the waste heat of the pressure container.

The invention has the beneficial effects that:

1. the invention utilizes the pressure relief valve 14 of the voltage stabilizer and the redundant pressure relief valve 15 of the hot section to realize the rapid incomplete pressure reduction of a loop and provides a safe injection mode combining passive and active modes. The passive reactor core water supplementing tank 10 is utilized to supplement high-pressure water to the reactor core in the early period of an accident, and the voltage of a primary circuit is quickly reduced by automatically starting the voltage stabilizer 13 and the hot section pressure relief valve 15 according to the low water level signal of the passive reactor core water supplementing tank 1. When the system pressure drops to the passive safety injection tank 12 and the low-pressure safety injection pressure head 3, the passive safety injection tank 12 realizes large-flow injection, and the reactor core can be cooled for a long time after the active low-pressure safety injection pipeline 16 is injected. Therefore, high, medium and low safety injection under the condition of the first loop break accident and the second loop break accident of the nuclear power plant can be completely realized. For a small break of a primary circuit, the passive core water replenishing tank 10 can be used for injecting water without reducing the pressure of the primary circuit for relieving; for major and minor crevasses, middle crevasses and major crevasses of a primary circuit, partial pressure reduction of the primary circuit is utilized, and a passive reactor core water replenishing tank 10, a passive safety injection tank 12 and an active low-pressure safety injection pipeline 16 are injected to relieve the major and minor crevasses, middle crevasses and major crevasses of the primary circuit; in the SGTR accident, a first loop and a second loop are balanced and relieved by using a passive core water replenishing tank 10 and a secondary side passive waste heat discharging system 19; the secondary loop breach accident may utilize the passive core makeup tank 10 to compensate for coolant shrinkage and core borylation. The scheme adopts two series of passive reactor core water supplementing tanks 10, passive safety injection tanks 12 and active low-pressure safety injection pipelines 16.

2. Compared with the prior art, the invention cancels a high-pressure safety injection pump in the traditional active nuclear power plant, reduces a safety injection box, a low-pressure safety injection pump and corresponding support systems, reduces the equipment investment and construction cost, enhances the effect of the passive system on relieving accidents, and greatly improves the safety and the economy of the nuclear power plant. Meanwhile, the requirement of the AP1000 nuclear power plant on complete depressurization of a primary circuit is lowered, only partial depressurization of the primary circuit is needed, and the system pressure is reduced to low-pressure safety injection (about 1.5MPa), so that the problem of uncertainty caused by the adoption of full-range passive injection in the AP1000 nuclear power plant is solved.

3. The invention adopts a direct injection pipeline 4(DVI) which is connected with a passive reactor core water supplementing tank 10, a passive safety injection tank 12 and an active low-pressure safety injection pipeline 16 to a pressure container 3 to realize injection, eliminates injection interfaces on a cold section 6 and a hot section 5, and eliminates a public main pipe, a large amount of safety injection pipelines, valves and the like of the traditional active nuclear power plant. Therefore, the safety injection pipeline is simplified, the opening of a primary circuit is reduced, equipment is easier to arrange in the containment, the volume of the containment is favorably reduced, and the construction cost of the containment is reduced.

4. The invention sets two hot section pressure relief valves 15 on the hot section 5 as the redundancy of the rapid pressure reduction of the primary circuit, and is used for preventing the core boron crystallization under the primary circuit cold section break accident. When the cold section of the primary loop is broken, the water is injected from the cold section 6 or the pressure container direct injection pipeline 4. For an active nuclear power plant, most of the safety injection flow is directly bypassed and lost through a break, and only little water reaches the reactor core, which may cause boron crystallization of the reactor core. If set up hot section relief valve 15 exhaust on hot section 5, can realize the safety water injection and get into the reactor core, avoid the reactor core to appear boron crystallization problem.

5. The active low-pressure safety injection pipeline 16 is provided with the low-pressure safety injection heat exchanger 18 for leading out the waste heat of the reactor core, so that a containment spraying system is omitted, the special safety facilities are simplified, and the construction and operation maintenance cost is reduced.

Drawings

FIG. 1 is a schematic diagram of a conventional active nuclear power plant dedicated safety injection system as described in the background section of the invention;

FIG. 2 is a schematic diagram of a safety injection system for a nuclear power plant in accordance with an embodiment of the present invention;

in the figure: 1-containment vessel, 2-pit, 3-pressure vessel, 4-direct injection pipeline, 5-hot section, 6-cold section, 7-two-loop water inlet section, 8-two-loop water outlet section, 9-two-loop heat exchanger, 10-passive core water replenishing tank, 11-pressure balance pipeline, 12-passive safety injection tank, 13-voltage stabilizer, 14-voltage stabilizer pressure relief valve, 15-hot section pressure relief valve, 16-active low-pressure safety injection pipeline, 17-low-pressure safety injection pump, 18-low-pressure safety injection heat exchanger, 19-secondary side passive waste heat discharge system, 20-ascending pipe section, 21-water tank heat exchanger, 22-cooling water tank, 23-descending pipe section and 24-main pump.

Detailed Description

The invention is further described below with reference to the figures and examples.

As shown in fig. 2, the safety injection system of a nuclear power plant according to the present invention is configured to inject cooling water into a pressure vessel 3 in a containment 1 of the nuclear power plant and depressurize a loop communicated with the pressure vessel 3, where the loop is formed by a loop, the loop includes a hot section 5 and a cold section 6 connected in series, and further includes a main pump 24 disposed on the loop and configured to provide power for circulation of a medium in the loop; the hot section 5 and the cold section 6 are connected with a two-loop heat exchanger 9 on a two-loop, wherein a passive core water replenishing tank 10 and a passive safety injection tank 12 are communicated with the pressure vessel 3 through a direct injection pipeline 4, and a hot section pressure relief valve 15 and a pressure stabilizer pressure relief valve 14 are arranged on the hot section 5.

Also included is an active low pressure safety injection line 16 connecting the pit 2 and the direct injection line 4 for injecting cooling water in the pit 2 into the direct injection line 4.

And a secondary side passive residual heat removal system 19 connected with the two loops.

The number of the direct injection pipelines 4 is 2, and each direct injection pipeline 4 is provided with a passive core water replenishing tank 10 and a passive safety injection tank 12;

the bottom of the passive reactor core water replenishing tank 10 is communicated with the direct injection pipeline 4 through a pipeline, the tank inlet at the top of the passive reactor core water replenishing tank 10 is communicated with the hot section 5 of a loop through a pressure balance pipeline 11, and the pressure balance pipeline 11 is provided with a valve;

the bottom of the passive safety injection tank 12 is communicated with the direct injection pipeline 4 through a pipeline.

The loop of the loop comprises a first loop, a second loop and a third loop, a voltage stabilizer 13 is communicated with the hot section 5 of the first loop, voltage stabilizer pressure relief valves 14 are arranged on the voltage stabilizer 13, the number of the voltage stabilizer pressure relief valves 14 is 3, the voltage stabilizer pressure relief valves are connected in parallel, and the voltage stabilizer pressure relief valves are used for quickly reducing the voltage of the loop to a low-voltage safety injection pressure head;

the hot section pressure relief valves 15 are 2 and are respectively communicated with the hot section 5 of the second loop and the hot section 5 of the third loop through a pipeline, and the hot section pressure relief valves 15 are used for being used as the redundancy of the pressure stabilizer pressure relief valves 14 and simultaneously used for preventing the boron crystallization function.

The number of the active low-pressure safety injection pipelines 16 is 2, each active low-pressure safety injection pipeline 16 is correspondingly communicated with one direct injection pipeline 4, a low-pressure safety injection pump 17 is arranged on each active low-pressure safety injection pipeline 16 and used for providing water injection kinetic energy, and a low-pressure safety injection heat exchanger 18 and a valve are arranged on each active low-pressure safety injection pipeline 16 and used for leading out heat of the pressure container 3 in a long-term cooling stage of the pressure container 3 in a primary circuit breach accident; the low-pressure safety injection pump 17 and the low-pressure safety injection heat exchanger 18 are positioned outside the containment vessel 1.

The second loop comprises a second loop water outlet section 8 and a second loop water inlet section 7, and the second loop water outlet section 8 and the second loop water inlet section 7 are respectively connected with a second loop heat exchanger 9;

the first loop, the second loop and the third loop are provided with a set of secondary side passive waste heat discharge system 19;

the secondary side passive waste heat discharge system 19 comprises an ascending pipe section 20, a water tank heat exchanger 21, a cooling water tank 22 and a descending pipe section 23; the cooling water tank 22 is positioned outside the containment vessel 1 and is higher than the position of the two loops; the water tank heat exchanger 21 is positioned in the cooling water tank 22; one end of the ascending pipe section 20 is connected with the water tank heat exchanger 21, and the other end is connected with the secondary loop water outlet section 8; one end of the descending pipe section 23 is connected with the water tank heat exchanger 21, and the other end is connected with the secondary loop water inlet section 7; valves are arranged on the ascending pipe section 20 and the descending pipe section 23; the secondary side passive waste heat discharge system 19 is used for reducing the temperature and the pressure of the pressure container 3 and leading out the waste heat of the pressure container 3 under the conditions of primary loop transient state, secondary loop transient state, small break accident, SGTR accident, design expansion working condition and the like.

Two parallel rows of electric isolation valves are arranged on a pipeline connecting the bottom of the passive core makeup tank 10 and the direct injection pipeline 4, and the cooling water in the passive core makeup tank 10 can be injected into the pressure vessel 3 by opening the isolation valves. When a low signal of the primary circuit pressure triggers one of the two rows of electric isolation valves to be opened, the passive core makeup tank 10 can inject cooling water into the pressure vessel 3 by using a liquid gravity head. The mode of operation of the passive core makeup tank 10 depends on the primary system conditions, primarily whether the cold leg 6 is empty. When the cold pipeline of the cold section 6 is filled with water, the pressure balance pipeline 11 of the passive core water replenishing tank 10 is also filled with water, and safety injection is performed in a water circulation mode. If the water charge of the primary loop system is reduced so that the cold leg 6 is empty, steam enters the passive core makeup tank 10 through the pressure balance line 11 of the passive core makeup tank 10, and a steam replacement cycle mode is initiated. The passive core makeup tank 10 is already mature in China in equipment manufacturing.

When the passive reactor core water supplementing tank 10 generates a water level low signal to trigger a loop rapid depressurization signal, three voltage stabilizer pressure relief valves 14 on the trigger voltage stabilizer 13 and a hot section pressure relief valve 15 on the hot section 5 are opened, and the loop pressure is rapidly reduced to a low-pressure safety injection pressure head. The stabiliser pressure relief valve 14 is retrofitted with the stabiliser SIBIM valve of an existing nuclear power plant, and the two hot leg pressure relief valves 15 on the hot leg 5 may not be burst valves.

The passive safety injection tank 12 and the low-pressure safety injection pump 17 are devices which are mature and applied in the existing nuclear power plant, and can be automatically started to operate under corresponding pressure signals, so that the safety function of medium-pressure and low-pressure safety injection is realized. After a break occurs in a loop, most of cooling water in the cooling water in a loop, the passive core water supplementing tank 10 and the passive safety injection tank 12 is gathered in the pit 2, the low-pressure safety injection pump 17 absorbs water from the pit 2 and injects the water into the pressure container 3, the cooling water flows through and cools the core (the core is arranged in the pressure container 3), the steam is discharged through the hot section pressure relief valve 15, meanwhile, liquid is entrained, and finally, the cooling water returns to the pit 2 to form closed circulation without water source switching. The active low-pressure safety injection pipeline 16 is provided with a low-pressure safety injection heat exchanger 18, and the waste heat of the reactor core can be taken away through the low-pressure safety injection heat exchanger 18, so that the long-term cooling of the reactor core is realized.

The secondary side passive waste heat discharge system 19 provides a primary circuit cooling and pressure reduction function in a primary circuit small break and SGTR accidents, and can be used as a backup of a primary circuit rapid pressure reduction function.

The device according to the present invention is not limited to the embodiments described in the specific embodiments, and those skilled in the art can derive other embodiments according to the technical solutions of the present invention, and also belong to the technical innovation scope of the present invention.