CN110415847B - System and method for relieving serious accident of nuclear power plant - Google Patents

Abstract

The invention provides a system and a method for relieving serious accidents of a nuclear power plant, which comprises the following steps: the system comprises a relieving system storage battery component, a central control component and a water storage component; the central control assembly is connected with the nuclear island DCS distribution board and the relieving system storage battery assembly and is used for detecting the power supply states of the nuclear island DCS distribution board and the relieving system storage battery assembly in real time and sending a water injection instruction to the water storage assembly in a delayed or real-time mode according to the detected power supply states of the nuclear island DCS distribution board and the relieving system storage battery assembly; the water storage assembly is connected with the central control assembly and used for receiving the water injection instruction sent by the central control assembly and then providing cooling water for the nuclear power plant reactor core. The invention provides cooling water for the reactor core of the nuclear power plant when a serious accident occurs in the nuclear power plant, and improves the operation safety of the nuclear power plant.

Description

System and method for relieving serious accident of nuclear power plant

Technical Field

The invention relates to the technical field of nuclear safety, in particular to a system and a method for relieving serious accidents of a nuclear power plant.

Background

When the spent fuel pool loses normal cooling after an over-design basis accident, pool water in the spent fuel pool boils and evaporates to cause liquid level reduction, if cooling and water replenishing can not be recovered, the spent fuel is exposed and melted finally, so that a reactor core is melted down, and a large amount of radioactive substances are released.

In the prior art, the design schemes of different reactor types for dealing with serious accidents are slightly different, the main means for preventing the reactor core from being melted down at present is to inject water into a reactor pit through a safety injection system or an additional water supplement system, the water injection process of the reactor pit needs to be controlled through a main control room DCS (distributed control system), namely, human intervention is needed, the water flow in the water injection process cannot be controlled, the problem of the reactor core melting down after the serious accidents occur cannot be quickly and effectively relieved, safety systems such as the safety injection system or the additional water supplement system need to realize the action and control of a pump valve by means of power supply, and when alternating current supplied by a diesel engine and direct current supplied by a storage battery are completely lost, the normal operation of the system and equipment for relieving the serious accidents cannot be. And when the nuclear power plant emergency power supply system is completely powered off (after all diesel engine power supplies and storage battery power supplies are lost), the DCS or the nuclear power plant central control system cannot work normally, so that the cooling water source of the nuclear power plant cannot be controlled, and further the reactor core is melted down after a serious accident occurs.

Therefore, a system for relieving serious accidents of the nuclear power plant more safely and effectively is urgently needed to be found.

Disclosure of Invention

The invention provides a system and a method for relieving a serious accident of a nuclear power plant, which are used for providing cooling water for a reactor core of the nuclear power plant when the serious accident occurs in the nuclear power plant, aiming at the problem that the reactor core is melted down after the serious accident can not be effectively relieved in the prior art.

The technical scheme provided by the invention for the technical problem is as follows: an emergency power supply system of a nuclear power plant for providing cooling water to a core of the nuclear power plant when a serious accident occurs in the nuclear power plant, comprising: the method comprises the following steps: the system comprises a relieving system storage battery component, a central control component and a water storage component; the central control assembly is connected with the nuclear island DCS distribution board and the relieving system storage battery assembly and is used for detecting the power supply states of the nuclear island DCS distribution board and the relieving system storage battery assembly in real time and sending a water injection instruction to the water storage assembly in a delayed or real-time mode according to the detected power supply states of the nuclear island DCS distribution board and the relieving system storage battery assembly; the water storage assembly is connected with the central control assembly and used for receiving the water injection instruction sent by the central control assembly and then providing cooling water for the nuclear power plant reactor core.

Wherein the central control assembly comprises: the detection unit is connected with the nuclear island DCS distribution board and the buffering system storage battery assembly and is used for detecting the power supply states of the nuclear island DCS distribution board and the buffering system storage battery assembly in real time; the first judgment unit is connected with the detection unit and is used for judging whether the nuclear island DCS distribution board and the buffer system storage battery assembly are all out of power or not, and if yes, a water injection instruction is sent to the water storage assembly in real time; if the distribution board of the nuclear island DCS is power-off and the battery pack of the relieving system is not power-off, counting power-off time; the second judgment unit is connected with the first judgment unit, and is used for judging whether the electric quantity of the relieving system storage battery assembly is sufficient or not if the power-off time exceeds the preset power-off time, and if so, sending a power supply instruction to the relieving system storage battery assembly to supply power to the nuclear island DCS distribution board; if not, sending a water injection instruction to the water storage assembly; and if the power-off time does not exceed the preset power-off time, not performing any operation.

The water storage assembly comprises a water storage tank, a water injection loop connected with the water storage tank, and a first valve and a second valve which are arranged on the water injection loop; one end of the water injection loop is connected with the water storage tank, the other end of the water injection loop is connected with the nuclear power plant reactor core, and after the storage battery assembly receives a water injection instruction, the first valve and the second valve are opened to inject water in the water storage tank into the nuclear power plant reactor core; the retaining subassembly is still including setting up auxiliary water pump and flow monitor on the water injection return circuit, auxiliary water pump and flow monitor with central control subassembly is connected, is used for when cooling water flow in the water injection return circuit is less than when predetermined flow, central control subassembly control auxiliary water pump is opened, increases cooling water flow improves the reactor core cooling rate.

The first valve and the second valve are further used for controlling the opening and closing of the storage battery assembly manually by a worker in the process that the central control assembly delays to send a power supply instruction to the storage battery assembly, so that misoperation is prevented.

The system further comprises a temperature control assembly, the temperature control assembly comprises a temperature monitoring unit, a heating unit and a refrigerating unit, the temperature monitoring unit is arranged in the water storage tank and connected with the central control assembly and used for detecting the actual temperature of cooling water in the water storage tank in real time and transmitting the real-time temperature to the central control assembly, if the central control assembly judges that the actual temperature is below the preset lowest temperature, the heating unit is controlled to heat the cooling water in the water storage tank, and if the central control assembly judges that the actual temperature is above the preset highest temperature, the refrigerating unit is controlled to refrigerate the cooling water in the water storage tank.

Wherein the water storage assembly further comprises: the central control assembly controls the third valve to be opened so as to convey a cooling water source in the water storage tank to an external container in the maintenance process.

The system also comprises a wind-solar complementary energy storage assembly, wherein the wind-solar complementary energy storage assembly is connected with the storage battery assembly and the central control assembly and is used for charging the storage battery assembly through the central control assembly in a controllable manner.

The wind-solar complementary energy storage assembly comprises a storage battery electric quantity detection unit, a wind driven generator and a photovoltaic generator, wherein the storage battery electric quantity detection unit is connected with the central control assembly and the storage battery assembly, when the storage battery electric quantity detection unit detects that the electric quantity of the storage battery assembly is lower than the preset lowest electric quantity, the central control assembly sends a charging instruction, and the wind driven generator and the photovoltaic generator charge the storage battery.

The water level detector is connected to the central control assembly and used for controlling the internal power system of the nuclear power plant to transmit cooling water into the water storage tank through the water pump when the water level in the water storage tank is lower than a preset value.

On the other hand, the invention also provides a method for relieving the serious accident of the nuclear power plant, which comprises the following steps:

s1, detecting the power supply state of a nuclear island DCS distribution board and a buffer system storage battery assembly in real time by the central control assembly;

s2, judging whether the nuclear island DCS distribution board and the buffer system storage battery assembly are all out of power, if so, sending a water injection instruction to the water storage assembly in real time; if the nuclear island DCS system distribution board is power-off, the relieving system storage battery assembly is not power-off, the power-off time is counted, if the power-off time exceeds the preset power-off time, whether the electric quantity of the relieving system storage battery assembly is sufficient is judged, if yes, a power supply instruction is sent to the relieving system storage battery assembly to supply power to the nuclear island DCS system distribution board; if not, sending a water injection instruction to the water storage assembly; if the power-off time does not exceed the preset power-off time, no operation is carried out;

and S3, the water storage component receives the water injection instruction sent by the central control component and provides cooling water for the nuclear power plant reactor core.

The technical scheme provided by the invention has the beneficial effects that: the system for relieving the serious accident of the nuclear power plant is used for providing cooling water for the reactor core of the nuclear power plant when the nuclear power plant has the serious accident, and is used as the last defense line of nuclear safety. The system utilizes wind energy and light energy in various ways as a standby replaceable power supply of the safety system, supplies power to the central control system when the distribution board of the nuclear island DCS system cannot work, and ensures that the central control system can normally operate to relieve serious accident conditions. By specific design, it may be considered to provide cooling water to the heat rejection system in the event of a cooling system failure or a serious accident to further prevent a heap melt event. The technical scheme provided by the invention can detect the flow of the cooling water in real time when the cooling water is injected into the reactor pit, further improve the speed of cooling the reactor core, effectively prevent further worsening of accidents and ensure safe and stable operation of the nuclear power plant.

Drawings

Fig. 1 is a schematic structural diagram of a system for mitigating a severe accident in a nuclear power plant according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a central control assembly of a system for mitigating a severe accident in a nuclear power plant according to an embodiment of the present invention.

Fig. 3 is a structural diagram of other components of a system for mitigating a severe accident in a nuclear power plant according to an embodiment of the present invention.

Fig. 4 is a flowchart of a method for mitigating a severe accident in a nuclear power plant according to a second embodiment of the present invention.

Detailed Description

In order to solve the problem that the reactor core is melted down after a serious accident cannot be effectively relieved in the prior art, the invention aims to provide a system and a method for relieving the serious accident of a nuclear power plant, which are used for providing cooling water for the reactor core of the nuclear power plant when the serious accident occurs in the nuclear power plant. The core idea is as follows: through the design of control logic in the central control assembly, when the nuclear island completely loses all power supplies (including all diesel generators and storage batteries in the nuclear island region), the pump valve is controlled through the self power supply of the system for relieving the serious accident of the nuclear power plant, and cooling water in the water storage tank is injected into the pile pit, so that the occurrence of the pile melting accident is prevented or relieved. The safety function can be realized by the control logic design of the central control unit, and the effect of the safety function is similar to that of passive safety measures under the condition of non-human intervention. The central control assembly is powered by two paths, one path is powered by a storage battery assembly of a system for relieving serious accidents of the nuclear power plant, and the other path is connected with a distribution board of the nuclear island DCS system. When the nuclear island DCS system loses power, the central control unit receives a power loss signal, the storage battery of the system for relieving the serious accident of the nuclear power plant supplies power after delayed triggering, the valve for connecting the reactor core water injection is opened by the power supply of the storage battery loop, and water in the reservoir is injected into the stack pit through the cooling water conveying loop under the action of gravity. The valve control logic for connecting the reactor core water injection adopts the control logic of delayed opening of the power-off valve of the main control room, and during the delay period, workers in the main control room have time to manually operate or close the valve, so that misoperation is avoided; according to the invention, the water flow detector is arranged in the water injection loop, so that the purpose of preventing the reactor core from being melted down can be realized by ensuring the flow of the cooling water, and the safe operation of the nuclear power plant is ensured.

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example one

An embodiment of the present invention provides a system for relieving a severe accident in a nuclear power plant, and referring to fig. 1, fig. 1 is a structural diagram of a device according to a first embodiment of the present invention, where the device includes: a mitigation system battery assembly 200, a central control assembly 100, and a water storage assembly 300; the central control assembly 100 is connected with the nuclear island DCS distribution board and the relieving system storage battery assembly 200, and is used for detecting the power supply states of the nuclear island DCS distribution board and the relieving system storage battery assembly 200 in real time and sending a water injection instruction to the water storage assembly 300 in a delayed or real-time manner according to the detected power supply states of the nuclear island DCS distribution board and the relieving system storage battery assembly 200; the water storage assembly 300 is connected with the central control assembly 100 and is used for receiving a water injection command sent by the central control assembly 100 and providing cooling water for the nuclear power plant core. The cooling water is provided for the reactor core of the nuclear power plant when the serious accident of the nuclear power plant occurs, so that the reactor core of the nuclear power plant can be prevented from being melted down, the serious accident of the nuclear power plant is relieved, and the safe and stable operation of the nuclear power plant is guaranteed. The system can be used as a standby or supplement system of a safety system, when all diesel generators cannot work and the existing safety shutdown related systems fail due to power failure and other reasons, the system provides an additional cold source for the nuclear power plant reactor, and can avoid the occurrence of reactor core fusion under the condition of non-human intervention. Under specific conditions, through different design schemes, extra power support can be provided, normal shutdown of the power station is guaranteed, and the working condition of serious accidents is relieved. By specific design, it may be considered to provide cooling water to the heat rejection system in the event of a cooling system failure or a serious accident and further prevent a heap melt event.

Further, with reference to fig. 2, the central control assembly 100 includes: the detection unit 110 is connected with the nuclear island DCS distribution board and the buffering system storage battery assembly 200 and is used for detecting the power supply states of the nuclear island DCS distribution board and the buffering system storage battery assembly 200 in real time; the first judging unit 120 is connected with the detecting unit 110 and is used for judging whether the nuclear island DCS distribution board and the buffer system storage battery assembly 200 are both out of power, and if so, sending a water injection instruction to the water storage assembly 300 in real time; if the distribution board of the nuclear island DCS is power-off and the storage battery assembly 200 is not power-off, counting the power-off time; the second judging unit 140 is connected to the first judging unit 120, and is used for judging whether the power failure time exceeds the preset power failure time, if so, sending a power supply instruction to the relieving system storage battery assembly 200 to supply power to the distribution board of the nuclear island DCS; if not, sending a water injection instruction to the water storage component 300; and if the power-off time does not exceed the preset power-off time, not performing any operation. The invention supplies power to the central control assembly 100 through the distribution board of the nuclear island DCS system and the storage battery assembly 200 of the relieving system, can realize that when all power supplies (including a diesel engine power supply and the storage battery power supply of the nuclear power plant) of the nuclear island DCS are in power failure, the power is supplied to the distribution board of the nuclear island DCS system and the central control unit 100 through the storage battery assembly 200 of the relieving system of the nuclear island DCS system, thereby improving the fault tolerance rate of the system, furthermore, the central control unit 100 is provided with two-stage judgment units, can judge the power failure signal of the distribution board of the nuclear island DCS system, judge whether the signal is a real power failure signal or a false power failure signal, delay trigger the storage battery assembly 200 to supply power to the central control assembly 100, prevent misoperation, and can realize that the water storage assembly 300 is automatically controlled to inject water to a reactor core in real time after the storage battery assembly 200 of the relieving system of the nuclear island, the technical effect of relieving serious accidents of the nuclear power plant through non-manual intervention is achieved.

Further, in conjunction with fig. 3, it can be seen that: the water storage assembly 300 comprises a water storage tank 310, a water filling circuit 320 connected with the water storage tank, and a first valve 321 and a second valve 322 arranged on the water filling circuit 320; the water storage tank 3100 is filled with cooling water, one end of the water injection loop 320 is connected with the water storage tank 310, the other end of the water injection loop 320 is connected with the reactor core of the nuclear power plant, after the storage battery assembly 300 receives a water injection instruction, the first valve 321 and the second valve 322 are opened, water in the water storage tank 310 is injected into the reactor core of the nuclear power plant, and the reactor core is prevented from being damaged by melting; the purpose of the two valves is to prevent the water injection circuit 320 from losing control when one of the valves fails, which leads to a safety accident in the nuclear power plant; it should be noted that: the first valve 321 and the second valve 322 are also used for controlling the opening and closing of the water storage component 300 by a worker in the process of delaying the water supply instruction sent to the water storage component 300 by the central control component 100, so as to prevent misoperation, the water storage component 300 further comprises a water drainage loop 330 connected with the water storage tank 310, and a third valve 331 arranged on the water drainage loop 330, and the central control component 100 is used for controlling the opening of the third valve 331 in the maintenance process, so as to convey cooling water in the water storage tank 310 to an external container, so that the maintenance is convenient.

It can further be seen from fig. 3 that: the water storage assembly 300 further comprises an auxiliary water pump 324 and a flow monitor 323 arranged on the water injection loop 320, the flow monitor 323 is used for detecting the flow rate of cooling water in the water injection loop 320, and the auxiliary water pump 324 and the flow monitor 323 are connected with the central control assembly 100, and when the flow rate of cooling water in the water injection loop 320 is lower than a preset flow rate, the central control assembly 100 controls the auxiliary water pump 324 to be opened, the flow rate of cooling water in the water injection loop 320 is increased, the core cooling speed is increased, the accident is prevented from further deteriorating, and the preset flow rate in the flow monitor 323 meets the requirement of preventing the core from being melted down. Meanwhile, the auxiliary water pump 324 and the flow monitor 323 are arranged to prevent the problem of system failure caused by the fact that the height difference between the water storage tank 310 and the stack pit is not enough to inject water in the water storage tank 310 into the stack pit through the water injection loop 320 by means of gravity due to different plant sites and different project design schemes.

Further, the system further comprises a temperature control assembly 400, the temperature control assembly comprises a temperature monitoring unit 410, a heating unit 420 and a refrigerating unit 430, the temperature monitoring unit 410 is arranged in the water storage tank 310 and connected with the central control assembly 100 and used for detecting the actual temperature of the cooling water in the water storage tank 310 in real time and transmitting the real-time temperature to the central control assembly 100, the central control assembly judges whether the actual temperature of the cooling water is lower than the preset minimum temperature, if so, the heating unit 420 is controlled to heat the cooling water in the water storage tank 310, and if the central control assembly 100 judges that the actual temperature is higher than the preset maximum temperature, the refrigerating unit 430 is controlled to refrigerate the cooling water in the water storage tank 310. Set up temperature control assembly 400 and can realize that the cooling water temperature in the water storage box 310 keeps invariable basically, realize the safety and stability operation of system, avoid nuclear power plant because in different areas, or the four seasons replace the temperature variation that leads to the cooling water in the water storage box 310, prevent that the water in the water storage box 310 leads to the system can't effectively alleviate the nuclear power plant accident because the evaporation water level is low excessively or because the weather is cold freezes.

Further, the system further comprises a wind-solar hybrid energy storage assembly 500, wherein the wind-solar hybrid energy storage assembly 500 is connected with the storage battery assembly 200 and the central control assembly 100 and is used for charging the storage battery assembly 200 in a controllable manner through the central control assembly 100. Specifically, the wind-solar hybrid energy storage assembly 500 includes a storage battery capacity detection unit 510, a wind power generator 520 and a photovoltaic power generator 530, wherein the storage battery capacity detection unit 510 is connected to the central control assembly 100 and the storage battery assembly 200 and is configured to detect a capacity of the storage battery assembly 200, when the capacity of the storage battery assembly 200 is detected to be lower than a preset minimum capacity, the central control assembly 100 issues a charging instruction, and the wind power generator 520 and the photovoltaic power generator 530 charge the storage battery assembly 200, wherein the storage battery is always in a floating state after being fully charged and supplies power to the central control unit 100 of the mitigation system when necessary. In consideration of the fact that the plant site of the nuclear power plant is generally located in the mountains and seas and the wind power and light energy resources are better, the wind power generator 520 and the photovoltaic generator 530 are utilized to generate power simultaneously in the day and at night to store energy for the storage battery assembly 200. The battery assembly 200 may include a plurality of batteries, each of which may have a capacity designed according to actual needs, and may have a smaller capacity if not considered to supply power to other systems in the plant, and may be used as a backup power source for the central control assembly 100 of the system for relieving a severe accident of the nuclear power plant. If the storage battery is considered as a standby power supply of a direct current system of the nuclear power plant, the capacity of the storage battery can be properly increased to be used as the standby power supply for relieving serious accidents of the nuclear power plant, and the capacity of the storage battery is designed according to the capacity of the storage battery in serious accidents of the nuclear power plant; each storage battery is connected with the central control assembly 100 and is used for providing power for the central control assembly 100 under the condition that the existing emergency power supply is lost under the working condition of a serious accident; during normal operation, wind energy and solar energy are transmitted to the battery assembly 200 through the wind power generator 520 and the photovoltaic power generator 530 for energy storage. When the severe accident condition is met, the storage battery assembly 200 preferentially provides power for the central control assembly 100, normal operation of a system for relieving the severe accident of the nuclear power plant is guaranteed, and operation safety of the nuclear power plant is improved.

In one embodiment of the present invention, a water level detector (not shown) for detecting a water level of the water storage tank 310 may be disposed in the water storage tank 310, and the water level detector is connected to the central control assembly 100 and is configured to control the internal power system of the nuclear power plant to transfer the cooling water to the water storage tank 310 through the water pump when the water level of the cooling water in the water storage tank 310 is detected to be lower than a preset value, so that the cooling water in the water storage tank 310 can meet the requirement of preventing the core from being melted down when a serious accident occurs, the problem of insufficient cooling water is avoided, and the purpose of relieving the serious accident of the nuclear power plant is further achieved.

It should be noted that: according to different design schemes of specific projects, the system can also be put into operation earlier than the serious accident condition, but the allowance enough for pit water injection is considered to be reserved.

Example two

The embodiment of the invention provides a method for relieving a severe accident of a nuclear power plant, which is suitable for a system for relieving the severe accident of the nuclear power plant shown in the first embodiment, and referring to fig. 4, the method comprises the following steps:

s1, detecting the power supply states of the distribution board of the nuclear island DCS system and the storage battery assembly 200 in real time by the central control assembly 100;

s2, judging whether the distribution board and the storage battery component 200 of the nuclear island DCS system are all power-off, if so, sending a water injection instruction to the water storage component 200 in real time; if the distribution board of the nuclear island DCS is power-off and the storage battery assembly 200 is not power-off, counting the power-off time; judging whether the power-off time exceeds the preset power-off time, if so, judging whether the power quantity of the relieving system storage battery assembly 200 is sufficient, and if so, sending a power supply instruction to the relieving system storage battery assembly 200 to supply power to a nuclear island DCS distribution board; if not, sending a water injection instruction to the water storage component 300; if the power-off time does not exceed the preset power-off time, no operation is carried out; when the nuclear island DCS distribution board loses power and the electricity of the relieving system storage battery assembly 200 is sufficient, the relieving system storage battery assembly 200 can provide power for the central control assembly 100 and the nuclear island DCS distribution board, so that serious accidents are effectively relieved; furthermore, by setting the logic of the delay trigger relieving system storage battery assembly 200, an alarm can be given in the statistical process of the power failure time, so that an operator is reminded to identify the truth of a power failure signal of a distribution board of the nuclear island DCS, and misoperation is prevented;

s3, the water storage component 300 receives the water injection command sent by the central control component 100 and provides cooling water for the nuclear power plant core. Wherein the water storage assembly 300 comprises a water storage tank 310, a water filling loop 320 connected with the water storage tank, and a first valve 321 and a second valve 322 arranged on the water filling loop 320; the water storage tank 3100 is filled with cooling water, one end of the water injection loop 320 is connected with the water storage tank 310, the other end of the water injection loop 320 is connected with the reactor core of the nuclear power plant, after the storage battery assembly 300 receives a water injection instruction, the first valve 321 and the second valve 322 are opened, water in the water storage tank 310 is injected into the reactor core of the nuclear power plant, and the reactor core is prevented from being damaged by melting; the purpose of the two valves is to prevent the water injection circuit 320 from losing control when one of the valves fails, which leads to a safety accident in the nuclear power plant; it should be noted that: the first valve 321 and the second valve 322 are also used for controlling the opening and closing of the water storage component 300 by a worker in the process of delaying the water supply instruction sent to the water storage component 300 by the central control component 100, so as to prevent misoperation, the water storage component 300 further comprises a water drainage loop 330 connected with the water storage tank 310, and a third valve 331 arranged on the water drainage loop 330, and the central control component 100 is used for controlling the opening of the third valve 331 in the maintenance process, so as to convey cooling water in the water storage tank 310 to an external container, so that the maintenance is convenient. The water storage assembly 300 further comprises an auxiliary water pump 324 and a flow monitor 323 which are arranged on the water injection loop 320, the flow monitor 323 is used for detecting the flow rate of the cooling water in the water injection loop 320, and the auxiliary water pump 324 and the flow monitor 323 are connected with the central control assembly 100, and are used for controlling the auxiliary water pump 324 to be turned on by the central control assembly 100 when the flow rate of the cooling water in the water injection loop 320 is lower than a preset flow rate, so that the flow rate of the cooling water in the water injection loop 320 is increased, the core cooling speed is increased, further accident deterioration is prevented, and the preset flow rate in the flow monitor 323 meets the requirement for preventing the core from being melted down. Meanwhile, the auxiliary water pump 324 and the flow monitor 323 are arranged to prevent the problem of system failure caused by the fact that the height difference between the water storage tank 310 and the stack pit is not enough to inject water in the water storage tank 310 into the stack pit through the water injection loop 320 by means of gravity due to different plant sites and different project design schemes.

It should be noted that: in the embodiment, when the system is implemented in a method for alleviating a serious accident, only the division of the functional modules is used for illustration, and in practical application, the functions may be distributed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules, so as to complete all or part of the functions described above. In addition, the system and method embodiments provided by the above embodiments belong to the same concept, and specific implementation processes thereof are described in detail in the method embodiments and are not described herein again.

Those skilled in the art will appreciate that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing associated hardware, and the program may be stored in a computer readable storage medium. The above mentioned control or switching function is realized by a controller, and the controller may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, a discrete Gate or transistor logic device, a discrete hardware component, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

In conclusion, the invention realizes the safety controllability of relieving accidents when serious accidents occur in the nuclear power plant by additionally arranging the central control unit, automatically provides cooling water for the reactor core of the power plant when all diesel generators and the storage batteries of the nuclear power plant cannot work, ensures the normal shutdown of the power plant and relieves the working conditions of the serious accidents; and make full use of wind-force, photovoltaic power generation green energy technique carries out the energy storage, and highly be higher than the height of heap pit through setting up the water storage box, utilize the gravity that is located cooling water in the water storage box to realize passive water injection, and in order to prevent its discharge undersize, add flow detection unit and auxiliary water pump, make the cooling water flow in the water injection return circuit satisfy the requirement that prevents the reactor core and melt, improve nuclear power plant operation security, through specific design, can provide the cooling water and further prevent the heap and melt incident for heat extraction system when cooling system inefficacy or serious accident. The technical scheme provided by the invention can improve the safety and reliability of the nuclear power plant when being applied to the nuclear power plant; the system can be used as an emergency water source for preventing the melting in the heaps, is convenient to overhaul, test and maintain, and has economical efficiency while improving the overall safety index of the nuclear power plant.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (9)

1. The utility model provides a alleviate serious accident system of nuclear power plant for provide the cooling water for the nuclear power plant reactor core when the serious accident takes place for nuclear power plant, a serial communication port, include: the system comprises a relieving system storage battery component, a central control component and a water storage component;

the central control assembly is connected with the nuclear island DCS distribution board and the relieving system storage battery assembly and is used for detecting the power supply states of the nuclear island DCS distribution board and the relieving system storage battery assembly in real time and sending a water injection instruction to the water storage assembly in a delayed or real-time mode according to the detected power supply states of the nuclear island DCS distribution board and the relieving system storage battery assembly;

the water storage assembly is connected with the central control assembly and is used for receiving a water injection instruction sent by the central control assembly and providing cooling water to the nuclear power plant reactor core;

the central control assembly comprises:

the detection unit is connected with the nuclear island DCS distribution board and the buffering system storage battery assembly and is used for detecting the power supply states of the nuclear island DCS distribution board and the buffering system storage battery assembly in real time;

the first judgment unit is connected with the detection unit and is used for judging whether the nuclear island DCS distribution board and the buffer system storage battery assembly are all out of power or not, and if yes, a water injection instruction is sent to the water storage assembly in real time; if the distribution board of the nuclear island DCS is power-off and the battery pack of the relieving system is not power-off, counting power-off time;

the second judgment unit is connected with the first judgment unit, and is used for judging whether the electric quantity of the relieving system storage battery assembly is sufficient or not if the power-off time exceeds the preset power-off time, and if so, sending a power supply instruction to the relieving system storage battery assembly to supply power to the nuclear island DCS distribution board; if not, sending a water injection instruction to the water storage assembly; and if the power-off time does not exceed the preset power-off time, not performing any operation.

2. The system of claim 1, wherein the water storage assembly comprises a reservoir, a fill circuit connected to the reservoir, and first and second valves disposed on the fill circuit;

one end of the water injection loop is connected with the water storage tank, the other end of the water injection loop is connected with the nuclear power plant reactor core, and after the storage battery assembly receives a water injection instruction, the first valve and the second valve are opened to inject water in the water storage tank into the nuclear power plant reactor core;

the retaining subassembly is still including setting up auxiliary water pump and flow monitor on the water injection return circuit, auxiliary water pump and flow monitor with central control subassembly is connected, is used for when cooling water flow in the water injection return circuit is less than when predetermined flow, central control subassembly control auxiliary water pump is opened, increases cooling water flow improves the reactor core cooling rate.

3. The system of claim 2, wherein the first valve and the second valve are further configured to be manually controlled to open and close by a worker during a time delay from the central control unit to the water storage unit to prevent a malfunction.

4. The system of claim 3, further comprising a temperature control component comprising a temperature monitoring unit, a heating unit and a cooling unit, wherein the temperature monitoring unit is disposed in the reservoir and connected to the central control component for detecting the actual temperature of the cooling water in the reservoir in real time and transmitting the real-time temperature to the central control component, and wherein the heating unit is controlled to heat the cooling water in the reservoir if the central control component determines that the actual temperature is below a predetermined minimum temperature, and wherein the cooling unit is controlled to cool the cooling water in the reservoir if the central control component determines that the actual temperature is above a predetermined maximum temperature.

5. The system of claim 4, wherein the water storage assembly further comprises: the central control assembly controls the third valve to be opened so as to convey cooling water in the water storage tank to an external container in the maintenance process.

6. The system of claim 5, further comprising a wind-solar hybrid energy storage assembly connected to the battery assembly and the central control assembly for controllably charging the battery assembly via the central control assembly.

7. The system of claim 6, wherein the wind-solar hybrid energy storage assembly comprises a storage battery capacity detection unit, a wind power generator and a photovoltaic power generator, the storage battery capacity detection unit is connected with the central control assembly and the storage battery assembly and is used for detecting the capacity of the storage battery assembly, when the capacity of the storage battery assembly is lower than a preset minimum capacity, the central control assembly sends a charging instruction, and the wind power generator and the photovoltaic power generator charge the storage battery assembly.

8. The system of claim 7, wherein a water level detector is disposed in the water storage tank for detecting a water level of the cooling water, and the water level detector is connected to the central control unit for controlling the internal power system of the nuclear power plant to deliver the cooling water into the water storage tank through the water pump by the central control unit when the water level of the cooling water in the water storage tank is detected to be lower than a preset value.

9. A method of mitigating a severe accident at a nuclear power plant, the method comprising the steps of:

s1, detecting the power supply state of a nuclear island DCS distribution board and a buffer system storage battery assembly in real time by the central control assembly;

s2, judging whether the nuclear island DCS distribution board and the buffer system storage battery assembly are all out of power, if so, sending a water injection instruction to the water storage assembly in real time; if the nuclear island DCS system distribution board is power-off, the relieving system storage battery assembly is not power-off, the power-off time is counted, if the power-off time exceeds the preset power-off time, whether the electric quantity of the relieving system storage battery assembly is sufficient is judged, if yes, a power supply instruction is sent to the relieving system storage battery assembly to supply power to the nuclear island DCS system distribution board; if not, sending a water injection instruction to the water storage assembly; if the power-off time does not exceed the preset power-off time, no operation is carried out;

and S3, the water storage component receives the water injection instruction sent by the central control component and provides cooling water for the nuclear power plant reactor core.

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