CN118507088A - Emergency core cooling system - Google Patents

Abstract

The invention relates to an emergency reactor core cooling system, which comprises a first pipeline and a second pipeline, wherein the first pipeline comprises a first safety injection pump, a second safety injection pump, a first emergency reactor core water injection pipeline and a first connecting pipeline for conveying emergency coolant to a second interface of a reactor pressure vessel; the second pipeline comprises a third safety injection pump, a fourth safety injection pump, a second emergency reactor core water injection pipeline and a second connecting pipeline for conveying emergency coolant to the first interface. The emergency reactor core water injection path after an accident can be effectively shortened, the reliability of the emergency reactor core injection function is improved, the probability of damage of a break accident to the reactor core is reduced, the production cost can be reduced, and the balance design of system safety and economy is facilitated.

Description

Emergency core cooling system

Technical Field

The application relates to the technical field of nuclear power, in particular to an emergency reactor core cooling system.

Background

A loss of coolant accident (LOCA) of a reactor is a typical design benchmark accident condition that needs to be considered in the design of a nuclear power plant. After the LOCA accident, the emergency cooling of the reactor core is one of the main purposes of accident handling. If emergency cooling water cannot be provided for the reactor core in time, the reactor cannot effectively cool the reactor core due to the loss of emergency coolant, and finally, the reactor core fuel cladding is damaged and radioactive substances are uncontrollably released. Therefore, in order to cope with the LOCA accident condition, the pressurized water reactor nuclear power plant is provided with an emergency core cooling system for executing emergency core injection after the LOCA accident.

The emergency core cooling system is one of the important safety systems of the nuclear power plant, and the arrangement must meet the independence requirement and meet a single failure criterion. The independent claim is that mutual interference between systems or redundant components of the same system is prevented by proper means such as physical isolation, electrical isolation, functional independence, communication (data transmission) independence and the like; the single failure criteria requires that the emergency core cooling system be assumed to be in the most adverse configuration state permitted under the LOCA accident, i.e., any equipment failure in the emergency core cooling system results in functionality being unavailable.

In the existing emergency core cooling system design of the nuclear power plant, the requirement on the independence and the requirement on the single fault criterion of the system are generally realized through a redundant configuration and physical isolation mode. The redundant configuration is to configure the 'n+1' column emergency core cooling system. "N" represents the number of columns that consider LOCA originating events, single faults, and system on-line maintenance leading to failure of the emergency core cooling system, and "1" represents the remaining one column valid, with the independent design being a further design optimization based on redundant design, i.e., mutual interference between the columns of the emergency core cooling system is prevented by appropriate means such as physical isolation, electrical isolation, functional independence, and communication (data transmission) independence. For example, as shown in fig. 2, a first prior art construction of an emergency core cooling system is composed of three systems, namely, high pressure safety injection, medium pressure safety injection and low pressure safety injection, wherein the high pressure safety injection is configured with three high pressure safety injection pumps (HHSI), the medium pressure safety injection is mainly configured with three medium pressure safety injection boxes (ACC), and the low pressure safety injection is configured with two low pressure safety injection pumps (LHSI). As another example, as shown in FIG. 3, the emergency core cooling system of the prior art two configuration includes an independent, redundant three column system. Each train consists of low pressure safety injection (LHSI), medium pressure safety injection (MHSI) and safety injection box systems. For another example, as shown in FIG. 4, an emergency core cooling system of the prior art three configuration includes two separate rows HHSI of pumps, two rows of ACCs, and two rows LHSI of pumps, each of which is filled with water to the core through two rows of DVI. Also for example, as shown in FIG. 5, a prior art four-configuration emergency core cooling system includes four separate lines that are rigidly physically separated, one for each loop of the reactor coolant system. Each column is located in a separate safe partition, including an safe injection tank, an MHSI pump and a LHSI pump (combined waste heat removal pump).

In the prior art, three HHSI pumps and two LHSI pumps are connected in parallel to the RCP system by adopting a main pipe system, the main pipe system leads to mutual communication among each row of the ECCS system, and part of emergency coolant which is effectively injected into the row under the LOCA accident working condition flows out through a break to influence the effective injection flow of the emergency reactor core. The redundancy of the second and fourth technologies is high, the number of columns of the system configuration is increased, the corresponding columns of supporting matched systems (such as an emergency diesel engine, a cold chain system, a heating and ventilation system and the like) also need to be correspondingly arranged, the scale of a safety factory building is increased, and the economy is optimized. The prior art III cannot meet a single fault criterion, and the system configuration scheme only configures one stage HHSI and LHSI in each column, considers DVI pipeline break accidents between a check valve and an RPV, and considers the other column HHSI and LHSI to fail according to the single fault criterion, so that the emergency reactor core injection function is lost, and the DVI pipeline break accidents cannot be dealt with.

Disclosure of Invention

The technical problem to be solved by the present application is to provide an improved emergency core cooling system, which aims at the above-mentioned drawbacks of the prior art.

The technical scheme adopted by the embodiment of the application for solving the technical problems is as follows: an emergency core cooling system is configured, comprising:

The first pipeline comprises a first injection pump, a second injection pump, a first emergency reactor core water injection pipeline and a first connecting pipeline for conveying emergency coolant to a second interface of the reactor pressure vessel, wherein the input end of the first emergency reactor core water injection pipeline is communicated with a replacement water tank in the containment, the output end of the first emergency reactor core water injection pipeline is communicated with the first interface of the reactor pressure vessel, the first injection pump is arranged on the first emergency reactor core water injection pipeline, the input end of the first connecting pipeline is communicated with the replacement water tank in the containment, the output end of the first connecting pipeline is communicated with the second interface, and the second injection pump is arranged on the first connecting pipeline;

The second pipeline comprises a third injection pump, a fourth injection pump, a second emergency reactor core water injection pipeline and a second connecting pipeline, wherein the second connecting pipeline is used for conveying emergency coolant to the first interface, the input end of the second emergency reactor core water injection pipeline is communicated with the inner replacement material water tank of the containment, the output end of the second emergency reactor core water injection pipeline is communicated with the second interface, the third injection pump is arranged on the second emergency reactor core water injection pipeline, the input end of the second connecting pipeline is communicated with the inner replacement material water tank of the containment, the output end of the second connecting pipeline is communicated with the first interface, and the fourth injection pump is arranged on the second connecting pipeline.

In some embodiments, the first pipeline further comprises a first safety tank disposed downstream of the first safety pump, and the second pipeline further comprises a second safety tank disposed downstream of the third safety pump.

In some embodiments, the first pipeline further comprises a first safety injection heat exchanger, the second pipeline further comprises a second safety injection heat exchanger, the first safety injection heat exchanger is arranged downstream of the first safety injection pump, and the second safety injection heat exchanger is arranged downstream of the third safety injection pump;

The output end of the first connecting pipeline is communicated with the pipeline between the second safety injection heat exchanger and the third safety injection pump, and the output end of the second connecting pipeline is communicated with the pipeline between the first safety injection heat exchanger and the first safety injection pump.

In some embodiments, the first emergency core water injection pipeline comprises a first cold section pipe section positioned outside the boundary of the containment and a first output pipe section positioned in the boundary of the containment, two ends of the first cold section pipe section are respectively communicated with the inner-containment replacement water tank and the input end of the first output pipe section, the output end of the first output pipe section is communicated with the first interface, the first injection pump is arranged on the first cold section pipe section, and the first injection tank is communicated with the first output pipe section;

The second pipeline comprises a second cold section pipe section positioned outside the boundary of the containment and a second output pipe section positioned in the boundary of the containment, two ends of the second cold section pipe section are respectively communicated with the inner-containment replacement water tank and the input end of the second output pipe section, the output end of the second output pipe section is communicated with the second interface, and the third injection pump is arranged on the second cold section pipe section, and the second injection tank is communicated with the second output pipe section.

In some embodiments, the first pipeline further comprises a first hot leg pipe, an input end of the first hot leg pipe being in communication with an output end of the first cold leg pipe section, the output end of the first hot leg pipe being in communication with one of the reactor loop hot legs;

The second pipeline further comprises a second hot section pipeline, the input end of the second hot section pipeline is communicated with the output end of the second cold section pipeline, and the output end of the second hot section pipeline is communicated with the other reactor loop hot section.

In some embodiments, the first pipeline further comprises a third connecting pipeline with two ends respectively communicated with the first safety injection box and the first output pipe section, and a check valve and an electric control valve are arranged on the third connecting pipeline; the second pipeline further comprises a fourth connecting pipeline with two ends respectively communicated with the second safety injection box and the second output pipe section, and a check valve and an electric control valve are arranged on the fourth connecting pipeline.

In some embodiments, the first pipeline further comprises a first water intake pipe section positioned within the containment boundary, two ends of the first water intake pipe section being respectively communicated with the in-containment replacement water tank and the input end of the first cold section pipe section;

the second pipeline further comprises a second water taking pipe section positioned in the boundary of the containment, and two ends of the second water taking pipe section are respectively communicated with the inner-containment material replacing water tank and the input end of the second cold section pipe section.

In some embodiments, the input end of the first connecting pipe is communicated with the output end of the first water intake pipe section and is communicated with the containment internal reloading water tank through the first water intake pipe section;

The input end of the second connecting pipeline is communicated with the output end of the second water taking pipe section, and the second water taking pipe section is communicated with the inner-containment material replacing water tank.

In some embodiments, pit screens are arranged between the first water intake pipe section and the second water intake pipe section and the containment internal reloading water tank.

In some embodiments, the two ends of the first cold section pipe section and the second cold section pipe section are respectively provided with an electric control valve, and the first output pipe section and the second output pipe section are respectively provided with three check valves.

In some embodiments, the first heat pipe and the second heat pipe are partially located outside the containment boundary, and partially located in the containment boundary, and are further provided with an electric control valve and three check valves respectively, wherein the electric control valves on the first heat pipe and the second heat pipe are both arranged outside the containment boundary, and the three check valves on the first heat pipe and the second heat pipe are both arranged in the containment boundary.

In some embodiments, the output ends of the first safety injection pump, the second safety injection pump, the third safety injection pump and the fourth safety injection pump are all provided with check valves.

In some embodiments, the first, second, third, and fourth safety pumps are all medium pressure safety pumps.

The embodiment of the invention has at least the following beneficial effects:

According to the invention, two pipelines are arranged, two safety injection pumps are arranged on each pipeline in parallel, and one of the two safety injection pumps is communicated with the other pipeline, so that the four safety injection pumps can independently pump emergency coolant to a reactor pressure vessel through a DVI pipeline, at least two safety injection pumps can simultaneously inject coolant to a reactor core aiming at large break accidents, at least one safety injection pump can inject coolant to the reactor core aiming at small break accidents with break diameters smaller than the inner diameter of the DVI pipeline, the requirement on the quantity of coolant required by the reactor under different accident conditions is met, the safety injection pumps are not required to be switched according to different conditions in the injection process, the emergency reactor core injection process after the accident is effectively shortened, the possibility of operation errors is avoided, and the reliability of the emergency injection function is improved;

meanwhile, the emergency coolant is pumped into the reactor by the corresponding safety injection pump under the condition of considering the least unfavorable single fault, so that the probability of damage of the broken accident to the reactor core is reduced, meanwhile, the system is simple in structure, the number of the corresponding heating, electric and instrument control systems of the two independent safety injection columns is reduced, the redundancy is reasonably reduced, the number of the safety injection pumps and the number of the matched systems are reduced, the scale of a factory building for accommodating the systems and the equipment are reduced, the construction cost of the system is greatly reduced, and the balance design of the safety and the economy of the system is facilitated.

Drawings

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

FIG. 1 is a schematic structural view of an emergency core cooling system according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of a prior art emergency core cooling system;

FIG. 3 is a schematic structural view of a prior art emergency core cooling system II;

FIG. 4 is a schematic structural view of a prior art three emergency core cooling system;

Fig. 5 is a schematic structural view of an emergency core cooling system of the fourth prior art.

Detailed Description

For a clearer understanding of technical features, objects and effects of the present application, a detailed description of embodiments of the present application will be made with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "rear", "upper", "lower", "left", "right", "longitudinal", "transverse", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail", etc. are configured and operated in specific directions based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present application, and do not indicate that the apparatus or element to be referred to must have specific directions, and thus should not be construed as limiting the present application.

It should also be noted that unless explicitly stated or limited otherwise, terms such as "mounted," "connected," "secured," "disposed," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. When an element is referred to as being "on" or "under" another element, it can be "directly" or "indirectly" on the other element or one or more intervening elements may also be present. The terms "first," "second," "third," and the like are used merely for convenience in describing the present application and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, whereby features defining "first," "second," "third," etc. may explicitly or implicitly include one or more such features. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

Fig. 1 shows an emergency core cooling system constructed in accordance with the present invention for timely injection of emergency coolant (cooling water in this embodiment) into a reactor in the event of a reactor breach leading to a loss of coolant accident (LOCA) to avoid core fuel cladding damage and uncontrolled release of radioactive materials. The emergency core cooling system includes a first pipeline 1 and a second pipeline 2.

The first pipeline 1 includes a first safety injection pump 101, a second safety injection pump 102, a first emergency core water injection pipe, and a first connection pipe 15. The second pipeline 2 comprises a third safety injection pump 201, a fourth safety injection pump 202, a second emergency core water injection pipe and a second connecting pipe 25. The input ends of the first emergency reactor core water injection pipeline and the second emergency reactor core water injection pipeline are communicated with the containment built-in material changing water tank 001, water in the containment built-in material changing water tank 001 is used as emergency coolant, and the emergency coolant is injected into the reactor core when an emergency coolant loss accident occurs. The output ends of the first emergency core water injection pipeline and the second emergency core water injection pipeline are respectively communicated with the reactor pressure vessel so as to inject emergency coolant into the reactor pressure vessel. The arrangement of the first emergency core water injection pipeline and the second emergency core water injection pipeline enables the first emergency core water injection pipeline and the second emergency core water injection pipeline to be capable of independently injecting water to meet the requirement of independence. Specifically, the output of the first emergency core injection conduit communicates with a first port 109 of the reactor pressure vessel and the output of the second emergency core injection conduit communicates with a second port 209 of the reactor pressure vessel.

The first safety injection pump 101 is disposed on a first emergency core water injection pipeline, and is configured to pump cooling water from a built-in containment tank 001 to the first interface 109 through the first emergency core water injection pipeline. The input end of the first connecting pipeline 15 is communicated with the containment built-in material-changing water tank 001, the output end is communicated with the second interface 209, and the second injection pump 102 is arranged on the first connecting pipeline 15 and is used for pumping emergency coolant to the second interface 209 by utilizing the power of the first pipeline 1, so that the emergency core cooling system can not inject the emergency coolant into the reactor when, for example, the second pipeline 2 loses the power source and the first emergency core water injection pipeline breaks.

The third safety injection pump 201 is disposed on the second emergency core water injection pipe for pumping cooling water from the in-containment refueling water tank 001 through the second emergency core water injection pipe to the second interface 209. The input end of the second connecting pipeline 25 is communicated with the containment built-in material-changing water tank 001, the output end is communicated with the first interface 109, and the fourth injection pump 202 is arranged on the second connecting pipeline 25 and is used for pumping emergency coolant to the first interface 109 by utilizing the power of the second pipeline 2, so that the emergency core cooling system can not inject the emergency coolant into the reactor when, for example, the first pipeline 1 loses a power source and a break occurs in the water injection pipeline of the second emergency core.

According to the invention, two safety injection pumps are arranged on each pipeline in parallel, so that when a large break accident occurs on the main pipeline of the reactor coolant system, even if one pipeline fails (for example, the second pipeline 2 loses power source, the third safety injection pump 201 and the fourth safety injection pump 202 cannot operate) under the least adverse working condition according to a single failure criterion, two safety injection pumps (the first safety injection pump 101 and the second safety injection pump 102) on one pipeline (the first pipeline 1) still can simultaneously inject water into the reactor core, and the water injection flow is ensured to meet the water demand of the large break accident of the main pipeline.

When a small break accident occurs, wherein the diameter of the break is smaller than the inner diameter of the DVI pipeline (for example, the break accident occurs in the second pipeline 2), the pressure drop is relatively slow due to the fact that the size of the break of the pipeline is smaller than that of the main pipeline, and meanwhile, the water quantity to be supplemented is small, and at the moment, only one safety injection pump is required to be ensured to be effective, so that the loss of a loop coolant under the accident condition can be compensated. Therefore, under the premise that even if one safety injection pump (such as the second safety injection pump 102) on the other pipeline without the break (the first pipeline 1) fails to operate under the least adverse condition according to the single failure criterion, the rest safety injection pumps (the first safety injection pump 101) can also independently realize water injection operation.

The safety injection pump is arranged on each pipeline in parallel, so that the safety injection pump can meet the treatment of all accident conditions under any accident condition only by completing one-time starting, and the safety injection pump is not required to be switched for different accident conditions, so that the treatment of accidents can be completed by starting the operation of the safety injection pump once, the safety injection flow interruption risk caused by the safety injection pump switching process is avoided, the operation steps are reduced, and the possibility of operation errors is avoided.

Meanwhile, the emergency reactor core injection system constructed by the application does not need to be provided with safety injection pumps of different types (such as high-pressure safety injection pumps, medium-pressure safety injection pumps and low-pressure safety injection pumps), can process all accident conditions by only one safety injection pump, reduces the number of safety injection pumps and other settings supporting matched systems (such as heating ventilation, electric, instrument control, factory buildings and power source equipment), and has the advantages of simpler system configuration, lower cost and higher economical efficiency. In this embodiment, all the devices of the first pipeline 1 share a line of emergency diesel power supply. All the equipment of the second pipeline 2 also shares an emergency diesel power supply line so as to ensure the independence between the two pipelines. It will be appreciated that "losing power" in this embodiment means that the emergency diesel engine common to the pipeline is not able to supply power to the pipeline.

It should be understood that the first pipeline 1 and the second pipeline 2 may be directly communicated with the descending section of the reactor pressure vessel through the first interface 109 and the second interface 209, respectively, so that the emergency coolant is pumped to the descending section of the reactor pressure vessel, thereby achieving the effect of rapid emergency injection.

In some embodiments, the first safety injection pump 101, the second safety injection pump 102, the third safety injection pump 201, and the fourth safety injection pump 202 are all medium pressure safety injection pumps. The selection of the medium-pressure safety injection pump is matched with two pipelines and the arrangement of two safety injection pumps of each pipeline, so that the emergency reactor core cooling system can cope with various accident problems such as large break, small break and the like. For example, in a large break accident, four safety injection pumps can be started simultaneously to improve the overall flow. In small break accidents, no larger flow is needed, and only one or two safety injection pumps can be used.

It is to be understood that the existing safety injection pump is divided into a high-pressure safety injection pump, a medium-pressure safety injection pump and a low-pressure safety injection pump, the higher the applicable pressure of the safety injection pump is, the lower the pumping flow of the safety injection pump is, and in a large break accident, the back pressure of a loop is fast to drop due to the occurrence of the large break, so that the starting requirement of the medium-pressure safety injection pump can be met, and at the moment, the flow requirement can be met only by connecting a plurality of safety injection pumps in parallel. In the small break accident, the break is smaller, so that the back pressure at the moment is reduced slowly, the starting requirement of the medium-pressure safety injection pump can not be met (namely, the starting requirement of the medium-pressure safety injection pump can not be met in the range of the lift of the safety injection pump at the early stage), at the moment, the safety injection pump is matched with the medium-pressure quick cooling valve on the secondary side of the steam generator, the reactor is quickly reduced in pressure through the medium-pressure quick cooling valve, and the back pressure of the primary loop is quickly reduced to meet the starting requirement of the medium-pressure safety injection pump.

In some embodiments, the first pipeline 1 further comprises a first safety injection tank 104, and the second pipeline 2 further comprises a second safety injection tank 204, both of which are used for passively injecting emergency coolant into the reactor as an inactive supplementary injection function, and water can be injected into the reactor whenever the pressure of the first circuit is reduced below the target pressure in spite of any break accident.

Specifically, the first safety injection tank 104 is disposed on the first emergency core water injection pipe and downstream of the first safety injection pump 101. The second safety injection tank 204 is disposed on the second emergency core water injection pipe and downstream of the third safety injection pump 201 to facilitate faster injection of emergency coolant into the reactor.

It should be appreciated that the first and second safety injection boxes 104, 204 each contain boron water therein, and that the compressed nitrogen blanketing provides a rapid injection that can be accomplished using prior art techniques.

In some embodiments, the first pipeline 1 further includes a first injection heat exchanger 103, and the second pipeline 2 further includes a second injection heat exchanger 203, both of which are used for exchanging heat with water pumped by each injection pump, reducing the temperature of cooling water, improving the cooling effect, and further shortening the path of the heat of the core led out of the containment.

Specifically, the first heat-injection heat exchanger 103 is disposed downstream of the first heat-injection pump 101, and the second heat-injection heat exchanger 203 is disposed downstream of the third heat-injection pump 201.

In this embodiment, the output end of the first connection pipe 15 is connected to the second safety injection heat exchanger 203 and the third safety injection pump 201, so that the cooling water pumped by the second safety injection pump 102 can exchange heat and cool in the second safety injection heat exchanger 203. The output end of the second connecting pipe 25 is connected to the pipe between the first heat exchanger 103 and the first pump 101. So that the cooling water pumped out by the fourth safety injection pump 202 can exchange heat and cool down in the first safety injection heat exchanger 103.

In some embodiments, the first emergency core water injection pipe includes a first cold leg section 11 and a first output leg section 13. Wherein, this first cold leg pipe section 11 is located outside the containment boundary, and its input is in communication with the in-containment refueling water tank 001, and the output is in communication with the input of the first output pipe section 13, and this first output pipe section 13 is located inside the containment boundary, and its output is in communication with the first interface 109. The first safety injection pump 101 and the first safety injection heat exchanger 103 are both disposed on the first cold leg 11, and the first safety injection box 104 is communicated with the first output leg 13.

The second emergency core water injection pipe includes a second cold leg section 21 and a second output leg section 23. Wherein the second cold leg 21 is located outside the containment boundary and has an input end in communication with the in-containment refueling water tank 001 and an output end in communication with the input end of the second output leg 23. The second outlet pipe section 23 is located within the containment boundary and its outlet communicates with the second port 209. The third injection pump 201 and the second injection heat exchanger 203 are disposed on the second cold leg 21, and the second injection tank 204 is in communication with the second output leg 23.

It should be understood that, since the in-containment refueling water tank 001 is disposed in the containment, the first emergency core water injection pipeline further includes a first water intake pipe section 12, an input end of which is in communication with the in-containment refueling water tank 001, and an output end of which is in communication with an input end of the first cold leg pipe section 11. The second emergency core water injection pipe also includes a second water intake pipe section 22, the input end of which is connected to the containment internal refueling water tank 001, and the output end of which is connected to the input end of the second cold leg pipe section 21.

In other alternative embodiments, the first emergency core water injection pipe and the second emergency core water injection pipe may share a water intake pipe section, and the output ends of the water intake pipe section are respectively connected to the input ends of the first cold leg pipe section 11 and the second cold leg pipe section 21, so as to reduce the number of penetrations on the containment.

In some embodiments, a pit filter is further disposed between the first water intake pipe section 12 and the second water intake pipe section 22 and the containment tank 001 to filter out impurities in the cooling water.

In some embodiments, the input end and the output end of the first cold leg 11 are respectively provided with an electrically controlled valve, a first electrically controlled valve 108 and a second electrically controlled valve 110. The input end and the output end of the second cold leg segment 21 are also respectively provided with an electric control valve, namely a third electric control valve 208 and a fourth electric control valve 210.

In some embodiments, three check valves, namely a first check valve 105, a second check valve 106 and a third check valve 107, are provided on the first output pipe section 13. The second outlet pipe section 23 is also provided with three non-return valves, a fourth non-return valve 205, a fifth non-return valve 206 and a sixth non-return valve 207, respectively.

It should be understood that, since the apparatus structure to which the first output pipe section 13 and the second output pipe section 23 are connected is a pressure boundary of the reactor, at least two check valves are disposed at portions of the first output pipe section 13 and the second output pipe section 23 closest to the first port 109 and the second port 209, respectively. The containment is another pressure boundary of the reactor, so that a check valve and an electric control valve are also required to be arranged inside and outside the containment respectively. Three check valves are provided in the first and second output pipe sections 13 and 23, respectively, and electronically controlled valves are provided in the output ends of the first and second cold pipe sections 11 and 21, respectively.

In some embodiments, the input end of the first connecting pipe 15 is in communication with the output end of the first water intake pipe section 12, and the first connecting pipe 15 is in communication with the containment in-tank refueling water tank 001 through the first water intake pipe section 12. The input end of the second connecting pipeline 25 is communicated with the output end of the second water taking pipe section 22, and the second connecting pipeline 25 is communicated with the containment built-in material changing water tank 001 through the second water taking pipe section 22. Through sharing first water intaking pipe section 12 and second water intaking pipe section 22 from the interior water intaking of containment built-in reload water tank 001, can reduce the through-hole setting quantity in containment boundary, reduce the risk that the containment leaked or bypassed, reduced the setting quantity and the total length of pipeline simultaneously, improved emergency reactor core cooling system's economic nature.

In this embodiment, the output end of the first connecting pipe 15 is connected to the first cold leg 11 between the first electrically controlled valve 108 and the first injection pump 101, and further connected to the output end of the first water intake leg 12. The output end of the second connecting pipe 25 is communicated with the second cold section pipe section 21 between the third electric control valve 208 and the third injection pump 201, and further communicated with the output end of the second water intake pipe section 22. The number of electrically controlled valves provided at the containment boundary may be reduced to further enhance the economic performance of the emergency core cooling system.

In other alternative embodiments, the output end of the first water intake pipe section 12 (the output end of the second water intake pipe section 22) may be further communicated with the input end of the first cold leg pipe section 11 (the second cold leg pipe section 21) and the input end of the first connecting pipe 15 (the second connecting pipe 25) through a three-way valve or the like, and an electric control valve is respectively disposed on the input end of the first cold leg pipe section 11 (the second cold leg pipe section 21) and the input end of the first connecting pipe 15 (the second connecting pipe 25).

In other alternative embodiments, the output end of the first water intake pipe section 12 (the output end of the second water intake pipe section 22) may be further communicated with the input end of the first connecting pipe 15 (the second connecting pipe 25), the input end of the first cold leg pipe section 11 (the second cold leg pipe section 21) is communicated with the first connecting pipe 15 (the second connecting pipe 25) upstream of the second injection pump 102 (the fourth injection pump 202), and the communication with the output end of the first water intake pipe section 12 (the output end of the second water intake pipe section 22) is achieved through a part of the first connecting pipe 15 (the second connecting pipe 25).

In other alternative embodiments, four water intake pipe sections may be provided, and their input ends are respectively connected to the in-containment tank 001, and the output ends are respectively connected to the input end of the first connecting pipe 15, the input end of the second connecting pipe 25, the input end of the first cold leg pipe section 11, and the input end of the second cold leg pipe section 21.

In some embodiments, the first line 1 further comprises a first hot leg pipe 14, the first hot leg pipe 14 having an input end in communication with the first cold leg pipe segment 11 and an output end in communication with one of the reactor loop hot legs. The second line 2 further comprises a second hot leg pipe 24, the input end of the second hot leg pipe 24 being in communication with the second cold leg pipe section 21 and the output end being in communication with the other reactor loop hot leg. The first hot leg pipe 14 and the second hot leg pipe 24 are used to inject emergency coolant into the reactor loop hot leg when a breach occurs therein. The arrangement of two independent hot-section pipelines can meet a single fault criterion while meeting an independence principle, and ensures that one pipeline can be put into use when the other pipeline fails.

It should be appreciated that the number of reactor loop hot legs is three and communicates with each other, so that the output ends of the first hot leg pipe 14 and the second hot leg pipe 24 can communicate with two different reactor loop hot legs at will.

In some embodiments, the first hot leg pipe 14 and the second hot leg pipe 24 are each disposed partially outside the containment boundary and partially inside the containment boundary. And an electric control valve is also arranged on a part of the pipeline outside the boundary of the containment, and three check valves are also arranged on a part of the pipeline inside the boundary of the containment. To protect the two pressure boundaries, and are not described in detail herein.

In the present embodiment, the input end of the first hot leg pipe 14 is connected to the pipe between the first heat injection heat exchanger 103 and the second electric control valve 110, and the input end of the second hot leg pipe 24 is connected to the pipe between the second heat injection heat exchanger 203 and the fourth electric control valve 210.

It is to be understood that the output ends of the first hot leg piping 14 and the second hot leg piping 24 may share a filler neck with the waste heat removal system in communication with the reactor loop hot leg. And further, the number of openings on the reactor main equipment is reduced, and the probability of fracture accidents of the main pipeline of the reactor coolant system is reduced.

In some embodiments, the first pipeline 1 further comprises a third connecting pipe 16, two ends of which are respectively communicated with the first safety injection box 104 and the first output pipe section 13, and are used for outputting the emergency coolant in the first safety injection box 104 to the reactor pressure vessel through the first output pipe section 13. The second pipeline 2 further comprises a fourth connecting pipeline 26, two ends of which are respectively communicated with the second safety injection box 204 and the second output pipe section 23, and the second pipeline is used for outputting emergency coolant in the second safety injection box 204 to the reactor pressure vessel through the second output pipe section 23.

Specifically, the third connecting pipe 16 is further provided with a fifth electrically controlled valve 113 and a seventh check valve 114, wherein the fifth electrically controlled valve 113 is located upstream of the seventh check valve 114. The fourth connecting line 26 is further provided with a sixth electrically controlled valve 213 and an eighth non-return valve 214, wherein the sixth electrically controlled valve 213 is located upstream of the eighth non-return valve 214.

In some embodiments, the output end of the first safety injection pump 101 is provided with a ninth check valve 111, the output end of the second safety injection pump 102 is provided with a tenth check valve 112, the output end of the third safety injection pump 201 is provided with an eleventh check valve 211, and the output end of the fourth safety injection pump 202 is provided with a twelfth check valve 212 to prevent backflow of the emergency coolant.

In the present embodiment, the output end of the first connection pipe 15 is in communication with the pipe between the eleventh check valve 211 and the second safety injection heat exchanger 203, and the output end of the second connection pipe 25 is in communication with the pipe between the ninth check valve 111 and the first safety injection heat exchanger 103.

The emergency core cooling system is further described below by the different reactions of the emergency core cooling system in different states of the nuclear power unit:

During normal operation of the unit. In order to ensure timely response when an accident occurs, the emergency core cooling system is always in a standby state, valves (except for check valves) on the two main pipelines, the third connecting pipeline 16 and the fourth connecting pipeline 26 are all in an open state, valves on the first hot section pipeline 14 and the second hot section pipeline 24 are all in a closed state, and the first safety injection pump 101, the second safety injection pump 102, the third safety injection pump 201 and the fourth safety injection pump 202 are all in a stop standby state.

Under the working conditions of large break (LB-LOCA) and medium LOCA with larger break size of the unit. Because the unit breach is great, and the back pressure is faster in this moment, and the backpressure can drop fast below the applicable pressure of each middling pressure ampere injection pump, and four ampere injection pumps start (when the pressure of a circuit drops below the nitrogen pressure of two ampere injection boxes simultaneously, two passive ampere injection boxes also carry out emergency coolant's injection to the reactor core), to the reactor core injection cooling water, realize the re-submerging of reactor core, resume reactor core water charge.

Considering the most disadvantageous single failure at this time, one of the lines (e.g., the first line 1) is not in use, the emergency core cooling system may also inject emergency coolant into the core through two safety injection pumps in the other intact line (the second line 2).

In the event of a direct injection breach (DVI-LOCA) of the pressure vessel, i.e. the first outlet pipe section 13 or the second outlet pipe section 23, a breach occurs. At this time, one of the lines is not available (e.g., the first line 1), and the emergency core cooling system can only inject emergency coolant into the core through two safety injection pumps in the other line (the second line 2). When the back pressure is reduced below the applicable pressure of the two medium pressure safety injection pumps, the emergency core injection signal triggers the two safety injection pumps to start (in the process, when the pressure of a loop is reduced below the nitrogen pressure of the second safety injection box 204, emergency coolant injection is started to the core), cooling water is injected into the core, re-flooding of the core is achieved, and the core water loading is restored.

At this time, considering the most disadvantageous single failure such as the power supply failure of the second pipeline 2 (emergency diesel failure), the two safety injection pumps of the second pipeline 2 cannot be started to be used. At this time, the second injection pump 102 of the first pipeline 1 can be supplied to the emergency diesel engine of the first pipeline 1 and is communicated with the second emergency core water injection pipeline through the first connecting pipeline 15, so that cooling water is injected into the core.

It should be understood that in this process, if such a break accident occurs, and such a single failure occurs, only one safety injection pump is available, but the reactor back pressure is high, and the starting pressure of the safety injection pump cannot be reduced, so that the loop pressure can be quickly reduced by matching with the secondary side medium pressure quick cooling valve of the steam generator.

And pipeline break of the waste heat discharging system in the waste heat discharging mode. At this time, one of the two waste heat removal systems, which is broken, is isolated, and only the other is left in operation. At this time, considering a single failure criterion, the waste heat removal system in operation fails and is shut down. At this time, water can be injected into a loop through the emergency reactor core cooling system, a safety valve of a pressure stabilizer (PZR) is opened simultaneously, water is discharged into the containment internal replacement water tank through a pressure relief tank and a water return pipe of the communication containment internal replacement water tank connected with the pressure relief tank, a charging-discharging function of the loop is realized, heat of the reactor core is discharged into the containment internal replacement water tank, heat in the containment internal replacement water tank is finally taken away by the first safety injection heat exchanger 103 and the second safety injection heat exchanger 203 through heat exchange and cooling, and then heat is discharged by replacing a waste heat discharging system, so that a path of the reactor core heat led out of the containment is shortened.

It is to be understood that the above examples represent only some embodiments of the invention, which are described in more detail and are not to be construed as limiting the scope of the invention; 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 invention; 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 (13)

1. An emergency core cooling system, comprising:

The first pipeline (1) comprises a first safety injection pump (101), a second safety injection pump (102), a first emergency reactor core water injection pipeline and a first connecting pipeline (15) for conveying emergency coolant to a second interface (209) of a reactor pressure vessel, wherein the input end of the first emergency reactor core water injection pipeline is communicated with a containment internal material replacement water tank (001), the output end of the first emergency reactor core water injection pipeline is communicated with the first interface (109) of the reactor pressure vessel, the first safety injection pump (101) is arranged on the first emergency reactor core water injection pipeline, the input end of the first connecting pipeline (15) is communicated with the containment internal material replacement water tank (001), the output end of the first connecting pipeline (15) is communicated with the second interface (209), and the second safety injection pump (102) is arranged on the first connecting pipeline (15);

Second pipeline (2), including third ampere annotate pump (201), fourth ampere annotate pump (202), second emergent reactor core water injection pipeline and be used for to first interface (109) carry emergent coolant's second connecting tube (25), the input of second emergent reactor core water injection pipeline with in the containment reload water tank (001) be linked together, the output with second interface (209) are linked together, third ampere annotate pump (201) set up in on the emergent reactor core water injection pipeline of second, the input of second connecting tube (25) with in the containment reload water tank (001) be linked together, the output with first interface (109) are linked together, fourth ampere annotate pump (202) set up in on second connecting tube (25).

2. The emergency core cooling system of claim 1, wherein the first pipeline (1) further comprises a first safety injection tank (104), the first safety injection tank (104) being disposed downstream of the first safety injection pump (101), the second pipeline (2) further comprising a second safety injection tank (204), the second safety injection tank (204) being disposed downstream of the third safety injection pump (201).

3. The emergency core cooling system of claim 1, wherein the first pipeline (1) further comprises a first safety injection heat exchanger (103), the second pipeline (2) further comprises a second safety injection heat exchanger (203), the first safety injection heat exchanger (103) is disposed downstream of the first safety injection pump (101), and the second safety injection heat exchanger (203) is disposed downstream of the third safety injection pump (201);

The output end of the first connecting pipeline (15) is communicated with the pipeline between the second safety injection heat exchanger (203) and the third safety injection pump (201), and the output end of the second connecting pipeline (25) is communicated with the pipeline between the first safety injection heat exchanger (103) and the first safety injection pump (101).

4. The emergency core cooling system of claim 2, wherein the first emergency core water injection pipeline comprises a first cold leg pipe section (11) located outside a containment boundary and a first output pipe section (13) located inside the containment boundary, two ends of the first cold leg pipe section (11) are respectively communicated with an inner containment refueling water tank (001) and an input end of the first output pipe section (13), an output end of the first output pipe section (13) is communicated with the first interface (109), the first safety injection pump (101) is arranged on the first cold leg pipe section (11), and the first safety injection tank (104) is communicated with the first output pipe section (13);

The second pipeline (2) comprises a second cold section pipe section (21) located outside the boundary of the containment and a second output pipe section (23) located inside the boundary of the containment, two ends of the second cold section pipe section (21) are respectively communicated with an inner material replacement water tank (001) of the containment and an input end of the second output pipe section (23), an output end of the second output pipe section (23) is communicated with a second interface (209), a third injection pump (201) is arranged on the second cold section pipe section (21), and a second injection box (204) is communicated with the second output pipe section (23).

5. The emergency core cooling system of claim 4, wherein the first pipeline (1) further comprises a first hot leg pipe (14), an input end of the first hot leg pipe (14) being in communication with an output end of the first cold leg pipe section (11), an output end of the first hot leg pipe (14) being in communication with one of the reactor loop hot legs;

the second pipeline (2) further comprises a second hot section pipeline (24), the input end of the second hot section pipeline (24) is communicated with the output end of the second cold section pipeline section (21), and the output end of the second hot section pipeline (24) is communicated with the other reactor loop hot section.

6. The emergency core cooling system according to claim 4, characterized in that the first pipeline (1) further comprises a third connecting pipeline (16) with two ends respectively communicated with the first safety injection box (104) and the first output pipe section (13), and a check valve and an electric control valve are arranged on the third connecting pipeline (16); the second pipeline (2) further comprises a fourth connecting pipeline (26) with two ends respectively communicated with the second injection tank (204) and the second output pipe section (23), and a check valve and an electric control valve are arranged on the fourth connecting pipeline (26).

7. The emergency core cooling system of claim 4, wherein the first pipeline (1) further comprises a first water intake pipe section (12) located within a containment boundary, both ends of the first water intake pipe section (12) being respectively in communication with the in-containment refueling water tank (001) and the input end of the first cold leg pipe section (11);

the second pipeline (2) further comprises a second water taking pipe section (22) positioned in the boundary of the containment, and two ends of the second water taking pipe section (22) are respectively communicated with the built-in material changing water tank (001) in the containment and the input end of the second cold section pipe section (21).

8. The emergency core cooling system of claim 7, wherein an input end of the first connecting pipe (15) is in communication with an output end of the first water intake pipe section (12) and is in communication with the containment-internal refueling water tank (001) through the first water intake pipe section (12);

the input end of the second connecting pipeline (25) is communicated with the output end of the second water taking pipe section (22), and the second water taking pipe section (22) is communicated with the built-in material changing water tank (001) in the containment.

9. The emergency core cooling system of claim 7, wherein pit screens are provided between the first water intake pipe section (12) and the second water intake pipe section (22) and the containment internal refueling water tank (001).

10. The emergency core cooling system of claim 4, wherein the first cold leg segment (11) and the second cold leg segment (21) are each provided with an electrically controlled valve at both ends, and the first output leg segment (13) and the second output leg segment (23) are each provided with three check valves.

11. The emergency core cooling system of claim 5, wherein the first hot leg pipe (14) and the second hot leg pipe (24) are partially located outside the containment boundary, partially located inside the containment boundary, and are further provided with an electrically controlled valve and three check valves, respectively, the electrically controlled valves on the first hot leg pipe (14) and the second hot leg pipe (24) are all disposed outside the containment boundary, and the three check valves on the first hot leg pipe (14) and the second hot leg pipe (24) are all disposed inside the containment boundary.

12. The emergency core cooling system of claim 1, wherein the output ends of the first safety injection pump (101), the second safety injection pump (102), the third safety injection pump (201) and the fourth safety injection pump (202) are respectively provided with a check valve.

13. The emergency core cooling system of claim 1, wherein the first safety injection pump (101), the second safety injection pump (102), the third safety injection pump (201), and the fourth safety injection pump (202) are all medium pressure safety injection pumps.