CN115274151A - Passive flow self-adaptation safety injection box and nuclear power plant safety system - Google Patents

Abstract

The invention discloses a passive flow self-adaptive safety injection tank which comprises a safety injection tank shell and a flow channel assembly, wherein the safety injection tank shell is used for containing cooling water, a water outlet pipeline is arranged at the bottom of the safety injection tank shell, the flow channel assembly is arranged in the safety injection tank shell and comprises a pipeline, a moving shaft and a floating plug, the pipeline is vertically arranged in the safety injection tank shell, the outlet at the bottom end of the pipeline is communicated with the water outlet pipeline, a through hole is formed in the pipe wall at the bottom end of the pipeline, the floating plug is arranged in the safety injection tank shell and floats on the water surface of the cooling water, and the moving shaft is inserted in the pipeline and is connected with the floating plug. The invention also discloses a nuclear power plant safety system. The safety injection box disclosed by the invention can automatically adapt to the injection flow, realize the functions of short-term fast water injection and long-term slow water injection after the LOCA accident occurs, reduce the failure risk of an active safety system, reduce the power failure accident risk of a whole nuclear power plant, prolong the access time of a standby emergency power supply system, and improve the accident relieving capability of the nuclear power plant and the overall safety of the nuclear power plant.

Description

Passive flow self-adaptation safety injection box and nuclear power plant safety system

Technical Field

The invention belongs to the technical field of nuclear, and particularly relates to a passive flow self-adaptive safety injection tank and a nuclear power plant safety system.

Background

After a large break coolant loss accident (LOCA) occurs in a nuclear power plant, the liquid level of a reactor core is reduced, the pressure of a primary loop is reduced rapidly, when the pressure is lower than the pressure of a passive safety injection tank of an emergency reactor core cooling system (ECCS), boron-containing cooling water in the safety injection tank is injected into a lower end socket and a lower cavity through a pressure vessel descending section, and the liquid level of the reactor core is recovered gradually along with the continuous injection of the cooling water. When the water in the safety injection box is completely injected, the coolant in the primary loop continuously flows out of the break to cause the liquid level of the reactor core to drop again, at the moment, if no safety injection system injects the cooling water, the reactor core is gradually exposed, the temperature of the reactor core is increased, the fuel rods are gradually melted and repositioned, and finally the lower end socket can be melted through. Therefore, water injection cooling is performed on the core in a short period after the LOCA accident, and long-term cooling is performed on the core.

At present, the scheme adopted by nuclear power plants at home and abroad is generally as follows: the passive safety injection tank is used for short-term water injection, and other safety injection systems or containers are used for long-term water injection, for example, a low-pressure safety injection system or a passive injection container with lower pressure is arranged. However, low pressure safety injection systems may fail during a plant blackout, and adding a lower pressure passive injection vessel may further complicate the overall system.

Disclosure of Invention

The invention aims to solve the technical problems in the prior art and provides a passive flow self-adaptive safety injection box and a nuclear power plant safety system, wherein the safety injection box can automatically adapt to the requirement of injection flow, and realizes the functions of short-term fast water injection and long-term slow water injection after an LOCA accident occurs, so that the failure risk of the active safety system is reduced, the power failure accident risk of the whole nuclear power plant is reduced, the access time of a standby emergency power supply system is prolonged, the reliability of the nuclear power plant safety system is improved, and the accident relieving capacity of the nuclear power plant and the overall safety of the nuclear power plant are improved.

The technical scheme for solving the technical problems is as follows:

according to one aspect of the invention, a passive flow adaptive safety injection box is provided, which comprises a safety injection box shell and a flow channel assembly, wherein:

the safety injection box shell is used for containing cooling water, a water outlet pipeline is arranged at the bottom of the safety injection box shell and provided with a check valve, and the water outlet pipeline is used for injecting the cooling water in the safety injection box shell into the reactor core;

the runner subassembly is located casing in the safety injection case, it includes the pipeline, removes the axle and float the stopper, the pipeline is erect in the safety injection case casing, the bottom export of pipeline with outlet pipe line intercommunication, and be equipped with the through-hole on the bottom pipe wall of pipeline, float the stopper and locate in the safety injection case casing to float on the cooling water surface of water, float about following the cooling water level change for carry out the shutoff to the top entry of pipeline, with the switching of control pipeline top entry, remove the axle and insert and locate in the pipeline to link to each other with the float stopper, be arranged in the cooling water and fall to the pipeline top entry and following position when guaranteeing the shutoff of float stopper in the top entry of pipeline.

Preferably, the top of the safety injection box shell is provided with an inflation pipeline for inflating the safety injection box shell with gas so as to ensure that a certain pressure is kept in the safety injection box shell.

Preferably, the flow channel assembly further comprises a support frame, the support frame is fixedly arranged in the pipeline, an opening is formed in the support frame, and the moving shaft penetrates through the opening.

Preferably, the support frame is a cross structure, and the opening is formed in the center of the cross structure.

Preferably, the top end inlet of the pipeline is a tapered hole, and the floating plug is in a shape of a taper matched with the tapered hole.

Preferably, the floating plug is a hollow structure.

Preferably, the number of the through holes is multiple, and the multiple through holes are uniformly distributed in a ring shape.

According to another aspect of the invention, a nuclear power plant safety system is provided, which comprises a safety injection box, wherein the safety injection box adopts the passive flow adaptive safety injection box.

Has the advantages that:

the passive flow self-adaptive safety injection box and the nuclear power plant safety system can automatically adapt to the requirement of the injection flow of cooling water, can realize a passive short-term quick injection function and a passive long-term slow injection function after an LOCA accident and the like, can reduce the failure risk of an active safety system (such as a low-voltage safety injection system), reduce the risk that an active valve cannot be opened possibly under the nuclear power plant whole plant power failure accident, prolong the access time of a standby emergency power supply system, enable the standby emergency power supply to be put into use later, and improve the reliability and the success rate of the nuclear power plant safety system, thereby improving the accident relieving capability of a nuclear power plant and the overall safety of the nuclear power plant.

Drawings

FIG. 1 is a schematic structural diagram of a passive flow adaptive safety injection tank according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a flow channel assembly according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view showing a structural schematic of a flow path member in an embodiment of the present invention

FIG. 4 is a schematic diagram of a passive flow adaptive safety injection tank in an embodiment of the invention when an inlet at the top end of a pipeline is opened;

fig. 5 is a schematic diagram of the passive flow adaptive safety injection tank in the embodiment of the invention when the inlet at the top end of the pipeline is closed.

In the figure: 1-a safety injection box shell; 2-an inflation line; 3-water outlet pipeline; 4-a pipeline; 5-a floating plug; 6-a moving axis; 7-a support frame; 8-through holes.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "on" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience and simplicity of description, and do not indicate or imply that the indicated device or element must be provided with a specific orientation, configured and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected," "disposed," "mounted," "fixed," and the like are to be construed broadly, e.g., as being fixedly or removably connected, or integrally connected; either directly or indirectly through intervening media, or through the interconnection of two elements. The specific meaning of the above terms in the present invention can be understood in specific cases for those skilled in the art.

Example 1

As shown in fig. 1, the present embodiment discloses a passive flow self-adaptation safety injection tank, which includes a safety injection tank housing 1 and a flow channel component, wherein:

the safety injection box shell 1 is used for containing cooling water, a water outlet pipeline 3 is arranged at the bottom of the safety injection box shell 1, a check valve (not shown in the figure) is arranged on the water outlet pipeline, the check valve is used for controlling the on-off of the water outlet pipeline 3, the check valve is normally in a normally closed state, the water outlet pipeline 3 is in an off state, when the pressure of a primary circuit or a pressure container in a nuclear reactor is lower than the pressure in the safety injection box shell 1, the check valve is automatically opened under the action of pressure difference, the water outlet pipeline 3 is automatically connected, the water outlet pipeline 3 is used for being connected with the primary circuit or the pressure container in the nuclear reactor, so that the cooling water in the safety injection box shell 1 is injected into the primary circuit or the pressure container after an LOCA accident and other breach accidents occur, and the safety of a reactor core is further ensured.

The flow channel assembly is arranged in the safety injection box shell 1 and comprises a pipeline 4, a moving shaft 6 and a floating plug 5, wherein the pipeline 4 is erected in the safety injection box shell 1, a bottom end outlet of the pipeline 4 is communicated with a water outlet pipeline 3, the floating plug 5 is arranged in the safety injection box shell 1, floats on the water surface of cooling water and is used for plugging a top end inlet of the pipeline 4 along with the lifting of the water level of the cooling water so as to control the opening and closing of the top end inlet of the pipeline 4, specifically, when the water level of the cooling water is above the top end of the pipeline 4, the top end inlet of the pipeline 4 is opened, the cooling water can rapidly enter the water outlet pipeline 3 through the top end inlet of the pipeline 4 and can be injected into a loop or a pressure container, when the water level of the cooling water is lowered to a position above the top end inlet of the pipeline 4, the floating plug 5 is plugged in the top end inlet of the pipeline 4, the top end inlet of the pipeline 4 is closed, the cooling water stops rapidly entering the water outlet pipeline 3 through the top end inlet of the pipeline 4, and accordingly, the function of rapidly injecting the cooling water in a short period is achieved; the moving shaft 6 is inserted into the pipeline 4, is connected with the floating plug 5, can move up and down along the length direction of the pipeline 4 along with the up-and-down floating of the floating plug 5, and is used for limiting the up-and-down floating position of the floating plug 5, so that the floating plug 5 can be blocked in the top inlet of the pipeline 4 when the cooling water falls to the top inlet of the pipeline 4 or below; the bottom pipe wall of the pipeline 4 is provided with a through hole 8, the through hole 8 can introduce cooling water into the water outlet pipeline 3 for a long time, so that the long-term slow injection function is realized, and particularly, the specific position, size, quantity, shape and arrangement condition of the through hole 8 can be selected according to actual requirements, so that the cooling water can be injected slowly according to the flow rate meeting the requirements. In this embodiment, as shown in fig. 2, the number of the through holes 8 is preferably multiple, the through holes 8 are preferably uniformly distributed in a ring shape, and the through holes 8 may be divided into one row or multiple rows, the aperture size of the through holes 8 is preferably 1-10cm, and is specifically adjusted according to actual requirements to ensure that cooling water can be injected slowly according to the flow rate meeting requirements, the positions of the through holes 8 are preferably set at the height of 0.5-1.5m from the bottom of the injection tank housing 1, and the shape of the through holes 8 is preferably circular.

In some embodiments, an inflation line 2 is provided at the top of the safety injection tank housing 1, and the inflation line 2 is used for inflating gas (preferably nitrogen) into the safety injection tank housing 1 so as to ensure a certain pressure (generally 4MPa-6 MPa) in the safety injection tank housing 1, thereby ensuring that the pressure in the safety injection tank housing 1 is higher than that of a primary circuit or a pressure container in case of LOCA accident and other breaches, and further passively injecting cooling water from the inside of the safety injection tank housing 1 into the primary circuit or the pressure container.

In some embodiments, the flow channel assembly further comprises a support 7, the support 7 is fixed in the pipe 4, specifically, fixed on the inner wall of the pipe 4, the support 7 is provided with an opening, and the movable shaft 6 passes through the opening. By arranging the support frame 7, the position of the movable shaft 6 moving up and down along the length direction of the pipeline 4 can be fixed, and the floating plug 5 can be further ensured to block the top end inlet of the pipeline 4.

In some embodiments, as shown in fig. 2, the support frame 7 is preferably a cross structure, and the opening is provided at the center of the cross structure. As shown in fig. 4 and 5, the support 7 is preferably positioned at the upper end of the pipe 4.

In some embodiments, the top end inlet of the pipeline 4 is preferably a tapered hole, that is, the inner wall of the top end inlet of the pipeline 4 has a certain inclination angle, and the floating plug 5 is in a shape of a taper matched with the tapered hole, so that the floating plug blocks and opens the top end inlet of the pipeline 4.

In this embodiment, the angle of inclination of the inner wall of the top inlet of the duct 4 is preferably 10-30 °.

In some embodiments, as shown in fig. 3, the floating plug 5 is a hollow structure, and the floating plug 5 is fixed to the top end of the moving shaft 6.

The working engineering of the passive flow self-adaptive safety injection box of the embodiment is described in detail below by taking a nuclear power plant LOCA accident as an example, and the details are as follows:

under normal working conditions, sufficient cooling water is filled in the safety injection tank shell 1, the water level of the cooling water is at least located above the top inlet of the pipeline 4, a certain amount of nitrogen is filled into the safety injection tank shell 1 through the inflation pipeline 2 until the pressure in the safety injection tank shell 1 reaches 4.2MPa, the floating plug 5 floats on the water surface of the cooling water, at the moment, the top inlet of the pipeline 4 is in an open state (as shown in figure 4), however, because a loop of the nuclear power plant under normal working conditions is intact, the pressure (generally 15.5 MPa) of the loop is higher than the pressure in the installation tank shell, and the check valve on the water outlet pipeline 3 is in a closed state, so that water in the safety injection tank shell 1 cannot be injected into the loop.

When LOCA accident occurs, the pressure of a primary loop of the nuclear power plant is rapidly reduced, when the pressure is reduced to be lower than the pressure (such as 4.2MPa and below) in the safety injection box shell 1, a check valve on a water outlet pipeline 3 is automatically opened, so that cooling water in the safety injection box shell 1 rapidly enters the water outlet pipeline 3 through a top inlet of a pipeline 4, meanwhile, the cooling water in the safety injection box shell 1 also enters the water outlet pipeline 3 through a through hole 8 on the bottom end of the pipeline 4, then the cooling water is injected into the primary loop or a pressure container through the water outlet pipeline 3, passive short-term rapid water injection is achieved, the floating plug 5 is blocked in a top inlet of the pipeline 4 (shown in figure 5) until the water level of the cooling water in the safety injection box shell 1 is reduced to be below the top inlet of the pipeline 4, rapid water injection is stopped, at the moment, the pressure in the safety injection box shell 1 is still far higher than the pressure in the primary loop, the top inlet of the pipeline 4 is blocked by the floating plug 5, and the cooling water in the primary loop can only enter the through hole 8 on the bottom end of the pipeline 4, and the water injection is slowly performed for a long time.

The passive flow self-adaptation safety injection box of this embodiment, can let the automatic demand that adapts to of injected flow of cooling water, both can realize passive short-term fast injection function and can realize passive long-term slow injection function after accidents such as LOCA take place, compare with the conventional art, can reduce the active safety coefficient (like low pressure safety injection system) failure risk, reduce the risk that the active valve can't be opened that probably meets under the whole factory outage accident of nuclear power plant, the reserve emergency power supply system access time of extension, make reserve emergency power supply can the input later, thereby improve the reliability and the success rate of nuclear power plant safety system, and then improve the ability that the nuclear power plant alleviated the accident and the overall safety nature of nuclear power plant.

Example 2

The embodiment discloses a nuclear power plant safety system, which comprises a safety injection box, wherein the safety injection box adopts the passive flow self-adaptive safety injection box in the embodiment 1.

The nuclear power plant safety system of this embodiment, owing to adopted in embodiment 1 passive flow self-adaptation safety injection case, compare with the conventional art, not only the flow is simple, can also reduce the risk that probably runs into under the power failure accident of the whole factory of nuclear power plant because of the inefficacy risk and the people and can't open active valve, extension reserve emergency power supply system access time for reserve emergency power supply can the input later, improves reliability and success rate, thereby improves the ability and the whole security of nuclear power plant that nuclear power plant alleviated the accident.

It will be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principles of the present invention, and the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.

Claims (8)

1. A passive flow self-adaptive safety injection tank is characterized by comprising a safety injection tank shell (1) and a flow channel component,

the safety injection box shell is used for containing cooling water, a water outlet pipeline (3) is arranged at the bottom of the safety injection box shell, a check valve is arranged on the water outlet pipeline, and the water outlet pipeline is used for injecting the cooling water in the safety injection box shell into the reactor core;

the flow channel assembly is arranged in the inner shell of the safety injection box and comprises a pipeline (4), a moving shaft (6) and a floating plug (5),

the pipeline is vertically arranged in the shell of the safety injection box, the outlet at the bottom end of the pipeline is communicated with the water outlet pipeline, the pipe wall at the bottom end of the pipeline is provided with a through hole (8),

the floating plug is arranged in the shell of the safety injection box, floats on the water level of the cooling water, floats up and down along with the change of the water level of the cooling water, is used for plugging the top inlet of the pipeline (4) so as to control the opening and closing of the top inlet of the pipeline (4),

the moving shaft (6) is inserted into the pipeline (4) and connected with the floating plug (5) and is used for ensuring that the floating plug is plugged in the inlet at the top end of the pipeline (4) when the cooling water descends to the inlet at the top end of the pipeline (4) and below.

2. The passive flow adaptive safety injection box according to claim 1, wherein an inflation pipeline (2) is arranged at the top of the safety injection box shell and used for inflating air into the safety injection box shell so as to enable the safety injection box shell to have certain pressure.

3. The passive flow adaptive safety injection tank according to claim 1, wherein the flow channel assembly further comprises a support frame (7),

the support frame is fixedly arranged in the pipeline, a hole is formed in the support frame, and the moving shaft penetrates through the hole.

4. The passive flow adaptive safety injection box according to claim 3, wherein the support frame is of a cross structure, and the opening is formed in the center of the cross structure.

5. The passive flow adaptive safety injection box according to claim 3, wherein the top end inlet of the pipeline is a tapered hole, and the floating plug is in a shape of a cone matched with the tapered hole.

6. The passive flow adaptive safety injection tank of claim 3, wherein the floating plug is a hollow structure.

7. The passive flow adaptive safety injection box according to claim 3, wherein the number of the through holes is multiple, and the multiple through holes are uniformly distributed in a ring shape.

8. A nuclear power plant safety system comprising a safety injection box, wherein the safety injection box adopts the passive flow adaptive safety injection box of any one of claims 1-7.

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