CN210956180U

CN210956180U - Nuclear power safety injection system and nuclear power system

Info

Publication number: CN210956180U
Application number: CN201921862492.XU
Authority: CN
Inventors: 陶俊; 咸春宇; 谢小飞; 梁潇; 陈军; 孔翔程
Original assignee: Hualong International Nuclear Power Technology Co Ltd
Current assignee: Hualong International Nuclear Power Technology Co Ltd
Priority date: 2019-10-31
Filing date: 2019-10-31
Publication date: 2020-07-07
Anticipated expiration: 2029-10-31

Abstract

The embodiment of the utility model provides a nuclear power safety injection system and nuclear power system relates to nuclear power technical field; wherein, above-mentioned nuclear power safety injection system includes: a reactor pressure vessel; the steam generator is connected with the reactor pressure vessel through a heat pipe section and a cold pipe section respectively to form a loop; the reactor core liquid supplementing container is connected with the reactor pressure vessel through a first pipeline; the liquid replenishing pump is connected with the reactor pressure vessel through a second pipeline; and the pressure relief device is communicated with a loop. The embodiment of the utility model provides an having adopted the active safety injection structure that combines together with the non-activity, can guarantee the promptness of reply accident through setting up reactor core fluid infusion container, and then sustainable to reactor pressure vessel in pour into liquid into through the fluid infusion pump, combine pressure vessel direct injection technique and pressure relief device, effectively improve the stability and the reliability of safe injection into, promote the treatment effect of accident.

Description

Nuclear power safety injection system and nuclear power system

Technical Field

The utility model relates to a nuclear power technical field especially relates to a nuclear power safety injection system and nuclear power system.

Background

The nuclear power system of the pressurized water reactor nuclear power plant generally comprises a primary loop and a secondary loop, wherein a flowing medium in the primary loop can absorb heat of a reactor core and transfer the heat to the flowing medium in the secondary loop to generate steam, and the temperature of the reactor core is controlled. When a Loss of coolant Accident (LOCA) occurs due to a primary circuit pipe Break, or a primary circuit supercooling Accident occurs due to a Steam pipe Break (slam Line Break, SLB), a Safety Injection System (Safety Injection System) is used to inject a coolant (e.g., boron-containing water) into the primary circuit.

To ensure that the cooling fluid is continuously injected into the primary circuit, the conventional safety injection system generally injects the cooling fluid in a container disposed at a high position directly into the primary circuit pipe by using gravity. The existing safety injection system has the defects that: the coolant is injected into a loop only by means of gravity, the driving force is limited, and the coolant cannot effectively reach the reactor core, so that the accident handling requirement is high, and the effect is poor.

SUMMERY OF THE UTILITY MODEL

An embodiment of the utility model provides a nuclear power safety injection system and nuclear power system to coolant liquid is difficult in order effectively to reach reactor core department in solving current nuclear power safety injection system, leads to the relatively poor problem of accident handling effect.

In order to solve the technical problem, the utility model discloses a realize like this:

an embodiment of the utility model provides a nuclear power safety injection system, include:

a reactor pressure vessel;

a steam generator connected to the reactor pressure vessel by a hot leg and a cold leg, respectively, to form a loop;

the reactor core liquid supplementing container is connected with the reactor pressure vessel through a first pipeline;

the liquid replenishing pump is connected with the reactor pressure vessel through a second pipeline;

a pressure relief device in communication with the primary circuit.

Optionally, the nuclear power safety injection system further comprises a refueling liquid container;

the pressure relief device comprises a pressure relief pipe, and the pressure relief pipe is communicated with the refueling liquid container.

Optionally, the pressure relief device comprises a surge tank and a pressure relief valve;

the pressure stabilizing container is connected with the heat pipe section through a third pipeline and is communicated with the refueling liquid container through a fourth pipeline;

the pressure relief valve is disposed in the fourth line.

Optionally, the number of the second pipelines is multiple, and the second pipeline is connected with the fluid replacement pump;

at least two of the plurality of second pipelines are connected in parallel on a fifth pipeline, and the fifth pipeline is communicated with the refueling liquid container.

Optionally, the safety injection device further comprises a safety injection container, wherein the safety injection container is connected to the second pipeline through a sixth pipeline.

Optionally, the fluid infusion pump is a low pressure safety injection pump.

Optionally, the first interface of the core makeup vessel is connected to the cold pipe section through a seventh pipeline;

and the second interface of the reactor core liquid supplementing container is connected with the reactor pressure vessel through the first pipeline and the second pipeline in sequence.

The embodiment of the utility model provides a nuclear power system is still provided, a serial communication port, including foretell nuclear power safety injection system.

The embodiment of the utility model provides a nuclear power safety injection system adopts the safety injection structure that combines active and passive, when a loop leads to pressure reduction because of accident condition, can pour into liquid into reactor pressure vessel rapidly through reactor core fluid infusion container, guarantees the promptness of coping with the accident; and the liquid can be continuously injected into the reactor pressure vessel through the liquid supplementing pump, and the stability and the reliability of safe injection are effectively improved and the accident treatment effect is improved by combining the direct injection technology and the pressure relief device of the pressure vessel.

Drawings

Fig. 1 is a schematic structural diagram of a nuclear power safety injection system provided by an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a nuclear power safety injection system provided in an embodiment of the present invention in a preferred embodiment;

fig. 3 is a flowchart of a control method applicable to the nuclear power safety injection system provided by the embodiment of the present invention.

The figures show that: the system comprises a reactor pressure vessel 1, a steam generator 2, a reactor core fluid supplementing vessel 3, a fluid supplementing pump 4, a pressure stabilizing vessel 5, a pressure relief valve 6, a refueling fluid vessel 7, a safety injection vessel 8, a main pump 9, a hot pipe section 10, a cold pipe section 11, a first pipeline 12, a second pipeline 13, a third pipeline 14, a fourth pipeline 15, a fifth pipeline 16, a sixth pipeline 17, a first isolation valve 18, a second isolation valve 19, a check valve 20, a third isolation valve 21, a seventh pipeline 22 and a containment vessel 23.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description will be given with reference to the accompanying drawings and specific embodiments. In the following description, specific details are provided, such as specific configurations and components, merely to facilitate a thorough understanding of embodiments of the invention. Thus, it will be apparent to those skilled in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

As shown in FIG. 1, the embodiment of the utility model provides a nuclear power safety injection system, include: reactor Pressure Vessel (RPV) 1; a steam generator 2, wherein the steam generator 2 is connected with the reactor pressure vessel 1 through a hot pipe section 10 and a cold pipe section 11 respectively to form a loop; a reactor core fluid replacement vessel 3, wherein the reactor core fluid replacement vessel 3 is connected to the reactor pressure vessel 1 through a first pipeline 12; the liquid supplementing pump 4 is connected with the reactor pressure vessel 1 through a second pipeline 13; a pressure relief device in communication with the primary circuit.

In the present embodiment, in the above-mentioned primary circuit, the number of RPVs is generally one, and the number of the steam generator 2, the hot pipe section 10 and the cold pipe section connected to the RPV is generally plural. For the sake of understanding, the structure in which the RPV, the hot pipe section 10, the steam generator 2 and the cold pipe section 11 connected in sequence form a closed loop may be regarded as a loop structure, and the loop may include one loop structure or a plurality of loop structures. As shown in fig. 1, in a specific application example, three loop structures are provided, and the three loop structures share one RPV, wherein a schematic diagram of the connection structure of the hot tube section 10, the steam generator 2 and the cold tube section 11 on one loop structure is shown, and the connection structure of the components of the other two loop structures is similar to the illustrated loop structure.

The fluid infusion pump 4 as an active Injection device of the nuclear power safety Injection system can inject fluid into the RPV depending on power input, and the second pipeline 13 for connecting the fluid infusion pump 4 is relatively independent from the loop structure and is directly connected with the RPV, that is, a Direct Vessel Injection (DVI) technology is adopted. Compared with the prior art, most of the safety injection systems are injected with water from the main loop pipe, and under the working condition that a large break occurs in the main loop pipe to cause Loss of Coolant Accident (Loss of Coolant Accident, LOCA), the water injected into the main loop pipe is completely lost, so that one column of the safety injection systems is completely failed, and the requirements on the number of the configured columns of the safety injection systems and the flow of the safety injection pumps on the intact main loop pipe are improved. In this embodiment, DVI technology is used to inject water directly into the loop from a second line 13 independent of the loop configuration. Even if a primary loop main pipeline large-break LOCA accident occurs, failure of movable injection equipment in the nuclear power safety injection system cannot be caused.

The reactor core fluid infusion container 3 is a component of a passive injection device in a nuclear power safety injection system, is opened when the pressure in a primary circuit is reduced to a certain value, and injects internal liquid into the primary circuit by means of gravity or pressure difference without depending on external power. The reactor core replenishing vessel 3 is connected to the RPV through the first line 12, and the first line 12 may be directly connected to the RPV, or the first line 12 may be connected to the second line 13 and indirectly connected to the RPV through the second line 13; that is, when the core makeup tank 3 is operated, the liquid may be directly injected into the RPV without passing through the loop structure.

The liquid replenishing pump 4 generally needs to be put into operation when the pressure in a primary circuit is reduced to a lower value, and in practical application, when the working conditions of LOCA accidents such as medium and small openings occur, the pressure in the primary circuit can not be reduced to a pressure value at which the liquid replenishing pump 4 can be put into operation; or the pressure drop speed is slow, and after the reactor core fluid replacement container 3 is put into operation and the internal liquid is nearly consumed, the pressure of the primary circuit cannot be reduced to the pressure value at which the fluid replacement pump 4 can be put into operation. Aiming at the accident condition, the pressure relief device can be arranged on one loop, and the pressure relief device is started at a proper time to reduce the pressure of the loop, so that the liquid supplementing pump 4 can be put into operation.

The nuclear power safety injection system provided by the embodiment adopts a safety injection structure combining active and passive, when the pressure of a primary circuit is reduced due to accident conditions, liquid can be rapidly injected into an RPV through a reactor core liquid supplementing container, and the timeliness of dealing with accidents is ensured; and can continuously inject liquid into the RPV through the liquid supplementing pump, and the stability and reliability of safe injection are effectively improved by combining the DVI technology and the pressure relief device, and the accident treatment effect is improved.

Optionally, the nuclear power safety injection system further comprises a refueling liquid container 7; the pressure relief device comprises a pressure relief pipe, and the pressure relief pipe is communicated with the refueling liquid container 7.

In this embodiment, the pressure relief pipe is directly connected to the feed liquid container 7, and when the pressure relief device relieves the pressure in the primary circuit, the fluid medium in the primary circuit, such as radioactive vapor, radioactive iodine, aerosol, and the like, is introduced into the feed liquid container 7 and effectively retained in the liquid in the feed liquid container 7. Compared with a structure for directly releasing pressure to the atmosphere of the containment vessel in the prior art, the containment vessel air pressure relief structure can effectively reduce pollution to the atmosphere of the containment vessel, further reduce radioactive release to the external environment, and enable a nuclear power system to be easier to recover after an accident; compared with a structure for reducing the temperature and the pressure of the primary loop through the steam release of the two loops in the prior art, the steam pressure reducing device has the advantage of high pressure relief efficiency.

Optionally, the pressure relief device comprises a surge tank 5 and a pressure relief valve 6; the pressure stabilizing container 5 is connected with the heat pipe section 10 through a third pipeline 14 and is communicated with the refueling liquid container 7 through a fourth pipeline 15; the pressure relief valve 6 is provided in the fourth line 15.

The third line 14 and the fourth line 15 are both part of the pressure relief tube described above. The pressure stabilizing container 5 is used for adjusting the pressure in the primary circuit and balancing the pressure fluctuation caused by instantaneous fluctuation; the pressure stabilizer is provided with a gas phase side and a liquid phase side, a third pipeline 14 is connected with the liquid phase side, and a fourth pipeline 15 is connected with the gas phase side. The pressure relief valve 6 is a special pressure relief valve for safe injection, and under a normal working condition, the pressure relief valve 6 is in a closed state; when accident conditions occur and a loop needs to be relieved, the pressure relief valve 6 is opened, and the operation is simple and reliable.

Of course, in practical application, the position of the pressure stabilizing container 5 in a loop can be adjusted according to actual needs; the other piping structures necessary for realizing the pressure stabilizing function of the pressure stabilizing vessel 5 are not limited herein.

Alternatively, as shown in fig. 2, the number of the second pipelines 13 is plural, and the make-up fluid pump 4 is connected to each of the second pipelines 13; at least two of the second lines 13 of the plurality of second lines 13 are connected in parallel to a fifth line 16, and the fifth line 16 is communicated with the refueling liquid container 7.

The diameter of the DVI line at the portion where it connects to the RPV (e.g., the second line 13 described above) is typically much smaller than the diameter of the primary loop pipe of the prior art, e.g., the size specification for the second line 13 may be set to DN150, whereas the size specification for the primary loop pipe of the prior art may typically be up to DN 760. In view of the influence of the size of the opening on the strength of the RPV, more secondary lines 13 may be provided to communicate with the RPV than in the prior art with a primary main pipe for safe injection, and a make-up fluid pump 4 may be installed on each secondary line 13. The increase of the number of the liquid supplementing pumps 4 can effectively improve the efficiency of injecting liquid into the RPV from the liquid replacing container 7, and improve the reliability of the nuclear power safety injection system.

Further alternatively, the number of the fifth pipelines 16 may also be multiple, and multiple second pipelines 13 are connected in parallel to any one of the fifth pipelines 16. The second pipeline 13, the fluid infusion pump 4, the first isolation valve 18 and the like connected with each fifth pipeline 16 can be used as one row, and the plurality of fifth pipelines 16 are correspondingly arranged, namely, a plurality of rows of the structure are correspondingly arranged, so that the single fault design principle is mainly considered, namely, when one row of the nuclear power safety injection system fails, other rows can still independently operate. Of course, the provision of a plurality of fifth lines 16 also improves injection efficiency.

Optionally, the nuclear power safety injection system further comprises a safety injection container 8, and the safety injection container 8 is connected to the second pipeline 13 through a sixth pipeline 17.

The safety injection container 8 is also a component part of the passive injection equipment, and a sixth pipeline 17 is provided with valve structures such as a second isolation valve 19, a check valve 20 and the like; the safety injection container 8 may store a liquid and a gas under a predetermined pressure, such as boron-containing water and nitrogen gas under a cover pressure of about 5 MPa. When the pressure in the primary circuit drops below the gas blanketing pressure, the valve arrangement on the sixth line 17 opens and liquid from the safety filling vessel 8 is injected into the RPV in a passive manner. Of course, the gas and the like stored in advance in the safety injection container 8 may be changed according to actual needs. Through the arrangement of the safety injection container 8, when the pressure in the primary circuit is reduced to a certain value, the liquid can be ensured to be injected into the RPV in a passive mode.

Optionally, the fluid infusion pump 4 is a low-pressure safety injection pump.

The Low-pressure safety injection pump and corresponding pipelines, valves and the like jointly form a Low-pressure safety injection (LHSI) subsystem, the operating pressure range of the Low-pressure safety injection pump is generally 0.1-2.0 MPa, the pressure in a loop can be effectively reduced to be lower than 2.0MPa by adopting a mode of directly relieving the pressure of the loop, the liquid supplementing pump 4 is set as the Low-pressure safety injection pump, the flow of active injection can be effectively increased, the injection efficiency is improved, meanwhile, a plurality of active safety injection subsystems with different injection pressures are not needed, the requirements on the active equipment and a support system thereof are reduced, the design of the active safety injection subsystems is simplified, and the economical efficiency is improved.

Of course, in some possible embodiments, the fluid infusion pump 4 may also be a medium-pressure safety injection pump (the operating pressure range is generally 0.1-8.0 MPa), or a high-pressure safety injection pump (the operating pressure range is generally 0.1-11.9 MPa), or a plurality of safety injection pumps with different operating pressures exist at the same time. However, the adoption of a medium-pressure safety injection pump or a high-pressure safety injection pump has the defect that the pump flow is relatively small, so that the large-break LOCA accident can not be dealt with.

Optionally, the first port of the core makeup vessel 3 is connected to the cold pipe segment 11 through a seventh pipeline 22; the second port of the reactor core fluid replacement vessel 3 is connected to the reactor pressure vessel 1 through the first pipeline 12 and the second pipeline 13 in this order.

The aforementioned seventh line 22, i.e. the pressure-equalizing line, is normally always in communication with the cold leg 11 of the circuit (generally downstream of the main pump); the first line 12 is a core makeup line, and is isolated from the primary circuit by a third isolation valve 21 under normal operating conditions. Under the accident condition, the third isolation valve 21 on the reactor core liquid supplementing pipeline is opened, high-temperature water with low density is filled in the pressure balance pipeline, low-temperature water with high density is filled in the reactor core liquid supplementing container 3 and the reactor core liquid supplementing pipeline, liquid in the reactor core liquid supplementing container 3 is injected into a primary circuit in a passive mode under the action of pressure difference caused by water density difference in the pressure balance pipeline, the reactor core liquid supplementing container 3 and the reactor core liquid supplementing pipeline, and the operation of the primary circuit has high reliability.

Further optionally, the core makeup tank 3 is located above the primary loop main pipe (i.e. the hot pipe 10 and the cold pipe 11) and the second pipeline 13, and the first interface of the core makeup tank 3 is located at a position higher than the second interface of the core makeup tank 3, so as to inject the liquid in the core makeup tank 3 into the RPV by using gravity. In some possible embodiments, the first line 12 may also be directly connected to the RPV.

Fig. 1 and 2 show the structure of the nuclear power safety injection system in a preferred embodiment.

Specifically, the method comprises the following steps:

the reactor Core fluid supplementing container is a reactor Core Water supplementing Tank (CMT), the fluid supplementing pump is a low-pressure safety injection pump, the Refueling fluid container 7 is an In-Containment Refueling Water Tank (IRWST), and the safety injection container is an ACCUMULATOR (ACC).

Four second pipelines 13 on the RPV are DVI-1, DVI-2, DVI-3 and DVI-4 respectively; each second pipeline 13 is provided with one ACC and a corresponding second isolation valve 19 and a corresponding check valve 20, the four ACCs are respectively defined as ACC-1, ACC-2, ACC-3 and ACC-4, the ACC can be a boron-containing water storage container covered by nitrogen, and the initial covering pressure of the nitrogen can be about 5 MPa; the low-pressure safety injection pump on each second pipeline 13 is respectively defined as a low-pressure safety injection pump-1, a low-pressure safety injection pump-2, a low-pressure safety injection pump-3 and a low-pressure safety injection pump-4; a first isolation valve 18 is provided on each second line 13. The water intake source of the four low-pressure safety injection pumps is IRWST, namely a boron-containing water storage tank arranged in the containment 23. The four low-voltage safety injection pumps are respectively positioned in two rows, the low-voltage safety injection pump-2 and the low-voltage safety injection pump-3 are positioned in the same row (row A) and share one row of emergency alternating-current power supply and equipment cooling water system, and the low-voltage safety injection pump-1 and the low-voltage safety injection pump-4 are positioned in the other row (row B) and share the other row of emergency alternating-current power supply and equipment cooling water system. The IRWST is provided with an a row suction port and a B row suction port as water intake ports for the a row and the B row, respectively.

The loop is provided with an RPV and three sets of loop structures connected to the RPV in parallel, and the loop structures mainly comprise a hot pipe section 10, a steam generator 2, a cold pipe section 11, a main pump 9 installed on the cold pipe section 11 and the like. Three hot pipe sections 10 are respectively defined as HL-1, HL-2 and HL-3, three cold pipe sections 11 are respectively defined as CL-1, CL-2 and CL-3, and three steam generators 2 are respectively defined as SG-1, SG-2 and SG-3 (wherein SG-2 and SG-3 are not shown in the figure, and the connection position is similar to SG-1).

Meanwhile, three CMTs and a set of pressure relief devices are also arranged. Three CMTs are respectively defined as CMT-1, CMT-2 and CMT-3; two ends of the CMT1 are respectively connected with CL-1 and DVI-1, two ends of the CMT2 are respectively connected with CL-2 and DVI-2, and two ends of the CMT3 are respectively connected with CL-3 and DVI-3; the CMT is pre-stored with water containing boron. The pressure relief device comprises a pressure stabilizing container 5 (namely a pressure stabilizer) and a pressure relief valve 6, wherein one end of the pressure stabilizing container 5 is connected to the HL-1, and the other end of the pressure stabilizing container is communicated to the IRWST through the pressure relief valve 6.

Of course, the number of the loop structures, the CMT structures, the low-pressure safety injection pumps, the ACC structures and the like can be selected according to actual needs.

In this embodiment, the CMT, ACC, and IRWST pre-store boron-containing water for injection into the RPV under accident conditions. For example, under the working condition of LOCA accidents of various sizes, boron-containing water is injected into a primary circuit for cooling, the water level of the reactor core is recovered and maintained in time, the effective cooling of the reactor core is ensured, and the overheating damage and radioactive release of the reactor core are prevented; under the working condition of a primary circuit supercooling accident such as Steam pipeline breakage (SLB), boron-containing water is injected into the primary circuit to compensate the positive reactivity introduced by primary circuit cooling, so that the reactor core is ensured to be in a subcritical state and maintain enough shutdown depth, and the safety of the reactor core of the reactor is ensured.

The embodiment of the utility model provides a nuclear power system is still provided, including foretell nuclear power safety injection system.

The nuclear power system also comprises a secondary circuit, a containment 23 and other structures. Wherein, the flowing medium in the second loop generates steam after passing through the steam generator 2, and is used for doing work on external structures such as a steam turbine; the containment vessel 23 is used to protect the reactor pressure vessel 1 and the like.

Adopt above-mentioned nuclear power safety injection system, when to a return circuit release, can directly open relief valve 6 on the pressure relief pipe, compare the mode in order to reduce the temperature and reduce the pressure to a return circuit steam release to two return circuits, this embodiment release process is more high-efficient. In addition, in some embodiments, the pressure relief pipe is directly communicated to the refueling liquid container 7, and fluid media in the primary circuit, such as radioactive steam, radioactive iodine, aerosol and the like, are directly introduced into the refueling liquid container 7 during pressure relief.

As shown in fig. 3, the hardware platform provided in the embodiment of the present invention is further improved, and the following steps of the control method can be applied to the nuclear power safety injection system:

step S100, controlling the reactor core fluid replenishing container to be opened under the condition that the pressure value in the primary circuit is lower than a first threshold value;

step S200, controlling the pressure relief device to be opened under the condition that the liquid level of the reactor core liquid supplementing container is lower than a preset value and the pressure value of the primary loop is not lower than a second threshold value;

and step S300, after the pressure relief device is started, if the pressure value of the primary circuit is lower than a second threshold value, controlling the liquid supplementing pump to be started.

The control method of the nuclear power safety injection system adopts a safety injection mode combining active and passive, and when the pressure of a primary circuit is reduced due to accident conditions, liquid can be rapidly injected into the RPV through the reactor core liquid supplementing container, so that the timeliness of dealing with accidents is guaranteed; and the liquid can be continuously injected into the RPV through the liquid supplementing pump, and the stability and the reliability of safe injection are effectively improved by combining the pressure relief device, so that the accident treatment effect is improved.

Optionally, in step S100, after controlling the core replenishing vessel to be opened when the pressure value in the primary circuit is lower than the first threshold value, the method further includes:

and controlling the liquid supplementing pump to be started under the conditions that the liquid level of the reactor core liquid supplementing container is not lower than a preset value and the pressure value of the primary circuit is lower than a second threshold value.

When LOCA accident condition with large break appears, the depressurization rate in a primary circuit is relatively high, the pressure of the primary circuit is rapidly reduced to below 2MPa probably soon after the reactor core fluid infusion container is opened, at the moment, the liquid level of the reactor core fluid infusion container does not need to be reduced to below a preset value, the fluid infusion pump is directly opened, liquid is injected into the RPV in time, and the reactor core is submerged and cooled.

In some possible embodiments, the rate of pressure drop in the primary circuit may also be obtained, and when the rate of pressure drop exceeds a preset value, the reactor core fluid replacement vessel and the fluid replacement pump are controlled to operate simultaneously. For example, under the working condition of a large-break-opening LOCA accident, the pressure in a primary circuit may be reduced to the atmospheric pressure within tens of seconds, and at the moment, in order to reduce the influence of the starting response time of the fluid replacement pump on the safety injection process, the fluid replacement pump can be controlled to operate while the reactor core fluid replacement container is put into operation.

The embodiment of the utility model provides a nuclear power safety injection system after combining above-mentioned control method, all kinds of practical application scenes are dealt with to the accessible as follows mode:

when a nuclear power system of a pressurized water reactor nuclear power plant normally operates, the nuclear power safety injection system is in a standby state, and after various size break LOCA accidents and primary circuit supercooling accidents occur, the nuclear power safety injection system is put into operation.

(1) And (4) responding to LOCA accidents of medium and small crevasses. Under the normal operation condition of a nuclear power system, the pressure of a primary circuit is about 15.5MPa, under the working condition of LOCA (local area of the absorption) with a medium or small break, the pressure of the primary circuit is reduced due to the release of the break, when the pressure is reduced to about 13.5MPa, a reactor shutdown signal is triggered, and a control rod is inserted into a reactor core to shut down the reactor. The safety injection signal is triggered when the loop pressure continues to drop to about 11.5MPa (first threshold). In a short-term stage, a third isolation valve on a liquid supplementing pipeline of the CMT reactor core is automatically opened after receiving a safe injection signal, and water in the CMT reactor core is injected into a loop in a passive mode. In a long-term stage, the pressure reduction effect on a loop is limited due to the small size of the break, and the pressure of the loop cannot be reduced to the pressure at which the ACC and the low-pressure safety injection pump can be put into operation. Therefore, when the water level in the CMT is reduced to a certain preset water level, a pressure relief valve opening signal on the voltage stabilizer is triggered, and the pressure relief valve is automatically opened, so that the pressure of the loop is quickly reduced. When the pressure of a primary circuit is reduced to the pressure which can be input by the ACC and the low-pressure safety injection pump, the ACC and the low-pressure safety injection pump inject cooling water into the primary circuit, the water level of the reactor core is quickly recovered, and the reactor core is ensured to be submerged and cooled.

(2) And the LOCA accident with a large break can be dealt with. Under the LOCA accident condition with a large break, the reactor shutdown is similar to the medium and small LOCA accidents. The large-size break reduces the pressure of the primary circuit rapidly, and the pressure of the primary circuit can be reduced to the pressure which can be input by the ACC and the low-pressure safety injection pump without opening a pressure relief valve on the voltage stabilizer. And the CMT, the ACC and the low-pressure safety injection pump simultaneously inject cooling water into the primary circuit, so that the water level of the reactor core of the reactor is quickly recovered, and the reactor core is ensured to be submerged and cooled.

(3) To deal with primary circuit subcooling such as SLB accidents. The SLB accident causes the temperature and pressure of a primary circuit to be reduced, when the pressure of the primary circuit is reduced to about 13.5MPa, a reactor shutdown signal is triggered, and a control rod is inserted into a reactor core to shut down the reactor. But the primary loop will continue to cool, and due to the negative moderator temperature coefficient and doppler temperature coefficient reactivity feedback effect, the reactor core will continue to introduce positive reactivity, with the risk of re-critical core. When the pressure of the primary loop is continuously reduced to about 11.5MPa due to continuous cooling of the secondary loop, a safety injection signal is triggered, a third isolation valve on a liquid supplementing pipeline of the CMT reactor core is automatically opened, boron-containing water in the CMT is injected into the primary loop, and the positive reactivity introduced by cooling of the primary loop is compensated, so that the reactor core is ensured to be in a subcritical state and a sufficient shutdown depth is maintained.

The foregoing is directed to the preferred embodiments of the present invention, and it will be understood by those skilled in the art that various changes and modifications may be made without departing from the principles of the invention, and that such changes and modifications are intended to be included within the scope of the invention.

Claims

1. A nuclear power safety injection system, comprising:

a reactor pressure vessel;

a pressure relief device in communication with the primary circuit.

2. The nuclear power safety injection system of claim 1, further comprising a refueling fluid container;

3. The nuclear power safety injection system of claim 2, wherein the pressure relief device includes a surge tank and a pressure relief valve;

the pressure relief valve is disposed in the fourth line.

4. The nuclear power safety injection system of claim 2, wherein the number of the second lines is plural, and the replenishment pump is connected to each of the second lines;

5. The nuclear power safety injection system of claim 1, further comprising a safety injection vessel connected to the second line by a sixth line.

6. The nuclear power safety injection system of claim 1, wherein the fluid replacement pump is a low pressure safety injection pump.

7. The nuclear power safety injection system of claim 1, wherein the first interface of the core makeup vessel is connected to the cold leg by a seventh line;

8. Nuclear power system comprising a nuclear power safety injection system according to any of claims 1 to 7.