Safety injection system and method

Abstract

The embodiment of the invention provides a safety injection system and method, and relates to the field of reactor safety systems. The problem that the water injection flow of a safety injection system is not matched with the flow needed in the reactor water loss accident stage is solved. The safety injection device comprises a pressure-bearing container and a damping device, wherein a safety injection outlet pipe is arranged at the bottom of the pressure-bearing container; the damping device is arranged in the pressure-bearing container, the damping device is provided with a water inlet and a water outlet, and safety injection water in the pressure-bearing container flows through the damping device from the water inlet and then flows to the safety injection outlet pipe from the water outlet. The drainage flow of the safety injection water in the pressure-bearing container is gradually reduced along with the process of the water loss accident, and compared with a pressure-bearing container without the damping, the flow in the initial stage is lower, so that the water quantity of the safety injection bypass can be reduced; the flow in the middle stage can quickly realize refilling of water in the lower cavity of the reactor core and resubmerging of the reactor core; the flow submerged in the reactor core is maintained to be lower in the later period of the accident, the safety injection time is fully prolonged, and safety injection water is effectively utilized.

Description

Technical Field

[0001] The present invention relates to the field of reactor safety systems, and in particular to a safety injection system and method. Background Art

[0002] The safety injection system is an important part of the reactor safety system. Its main function is to ensure the flooding and cooling of the reactor core to ensure the integrity of the core when a loss of coolant accident occurs in the reactor.

[0003] The injection tank is an important part of the safety injection system. The traditional injection tank is usually a pressure container containing a large amount of boronized water, and the upper part of the tank is filled with high-pressure nitrogen. When a loss of coolant accident occurs, such as a large break loss of coolant accident (LBLOCA), the boronized water in the injection tank will be injected into the reactor main system under the pressure of the internal nitrogen, flooding the reactor core and keeping it cool. At the same time, the boronized water can also control the reactivity. The traditional injection tank quickly reaches the maximum injection flow rate a few seconds after the injection begins, and then the injection flow rate gradually decreases until the boronized water in the tank is emptied.

[0004] In a large-break reactor loss of coolant accident, the blowdown stage, refilling stage and reflooding stage are the core links of the accident development. In the initial stage of a large-break loss of coolant accident, there is a large amount of high-temperature and high-pressure steam in the reactor core. For a large-break loss of coolant accident in the cold section, the steam will flow from the reactor pressure vessel downcomer to the cold section breach; at this time, when the injection water of the injection tank enters the downcomer, it may be entrained and flow to the breach under the influence of these steam, and thus cannot enter the reactor core, which is the so-called injection bypass phenomenon. In the core refilling stage and reflooding stage of a large-break loss of coolant accident, a large injection flow rate is required to quickly fill the lower chamber and realize the core reflooding. The traditional injection tank can provide a large flow rate that meets the requirements at this stage. After the core is reflooded, only a small injection flow rate is required. However, even though the injection flow of the traditional injection tank gradually decreases as the accident progresses, the flow provided by the traditional injection tank at this time still exceeds the injection flow required after the core is re-flooded, causing excessive boron-containing water to overflow from the rupture and failing to effectively utilize the boron-containing water in the injection tank. Summary of the invention

[0005] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0006] The purpose of the present invention includes, for example, providing a safety injection system that can improve the problem of mismatch between the water injection flow rate of the safety injection system and the flow rate required during the loss of coolant accident stage of the reactor.

[0007] The purpose of the present invention also includes providing a safety injection method, which can improve the problem of mismatch between the water injection flow rate of the safety injection system and the flow rate required during the reactor loss of coolant accident stage.

[0008] The embodiments of the present invention can be implemented as follows: An embodiment of the present invention provides a safety injection system, including a pressure container and a damping device, wherein the pressure container is used to contain nitrogen and safety injection water, and a safety injection outlet pipe is arranged at the bottom of the pressure container; the damping device is arranged in the pressure container, and the damping device is provided with a water inlet and a water outlet, the water inlet is connected to the interior of the pressure container, and the water outlet is connected to the safety injection outlet pipe; the safety injection water in the pressure container flows from the water inlet through the damping device, and then flows from the water outlet to the safety injection outlet pipe.

[0009] In addition, the safe injection system provided by the embodiment of the present invention may also have the following additional technical features: Optionally, the damping device includes a suction pipe, which is arranged above the Anzhu outlet pipe and connected to the Anzhu outlet pipe. The interior of the suction pipe is provided with rotating blades distributed in a clockwise or counterclockwise direction, and the rotating blades are used to guide the Anzhu water to be injected into the Anzhu outlet pipe in a counterclockwise or clockwise direction.

[0010] Optionally, the damping device further comprises a first cyclone, the first cyclone is provided with a first chamber and a drainage pipe communicating with the first chamber, the drainage pipe is communicated with the interior of the pressure container, and the drainage pipe is used to guide the injection water to be injected into the first chamber in a clockwise or counterclockwise direction; The suction pipe is arranged above the first cyclone and is connected to the first chamber. The rotary vane is used to guide the injection water to be injected into the first chamber in a counterclockwise or clockwise direction. The height of the suction pipe is higher than that of the drainage pipe.

[0011] Optionally, the damping device also includes a second cyclone, which is arranged above the injection outlet pipe; the second cyclone is provided with a second chamber connected to the injection outlet pipe, and a water inlet channel connected to the pressure container and the second chamber and bent in the height direction; a water seal can be formed in the water inlet channel to prevent nitrogen from entering the second chamber from the water inlet channel; the first cyclone is arranged above the second cyclone, and the first chamber is connected to the second chamber.

[0012] Optionally, a spiral channel rotating in a clockwise or counterclockwise direction is further provided in the second cyclone, the spiral channel connects the second chamber and the water inlet channel, and the spiral channel is used to guide the injection water to rotate in a clockwise or counterclockwise direction and be injected into the second chamber.

[0013] Optionally, the second cyclone includes an upper shell and a lower shell, the upper shell and the lower shell are spaced apart, the second chamber and the water inlet channel are formed between the upper shell and the lower shell around the second chamber; the lower shell is connected to the injection outlet pipe.

[0014] Optionally, the upper shell comprises a first circular flat plate, an upper outer ring side wall and an upper inner ring side wall which are connected in sequence, the upper inner ring side wall is arranged at an angle with the upper outer ring side wall, and the upper inner ring side wall is located on the inner side of the upper outer ring side wall; The lower shell comprises a lower inner ring side wall, a circular ring flat plate and a lower outer ring side wall which are connected in sequence, and the lower inner ring side wall and the lower outer ring side wall are arranged at intervals; The upper outer ring side wall is spaced apart from the inner wall of the pressure container, the first circular flat plate and the circular flat plate are spaced apart, the lower inner ring side wall is connected to the injection outlet, and the second chamber is formed between the lower inner ring side wall and the first circular flat plate; the lower inner ring side wall, the upper inner ring side wall, the lower outer ring side wall and the upper outer ring side wall are sequentially spaced apart along the diameter direction of the first circular flat plate, forming the water inlet channel that bends up and down from the bottom of the pressure container and enters the second chamber; When the water level of the injection water is lower than the height of the top end of the upper inner ring side wall, the water seal is formed between the lower inner ring side wall, the upper inner ring side wall, the lower outer ring side wall and the upper outer ring side wall.

[0015] Optionally, the second cyclone further comprises an arc-shaped plate, and the arc-shaped plate is spirally fixed between the first circular flat plate and the annular flat plate to form the spiral channel arranged to rotate counterclockwise or clockwise.

[0016] Optionally, the safety injection system further comprises a support block and a guide vane, and the upper shell is connected and supported to the inner wall of the pressure container via the support block or the guide vane; the guide vane is spirally arranged in a clockwise or counterclockwise manner.

[0017] An embodiment of the present invention further provides a safe injection method, which is implemented by a safe injection system. The safe injection method includes: When a reactor loss of coolant accident occurs, the injection water in the pressure vessel flows through the damping device and then is injected into the reactor main system from the injection outlet pipe.

[0018] The beneficial effects of the safe injection system and method of the embodiments of the present invention include, for example: The safety injection system comprises a pressure container and a damping device. The pressure container is used to contain nitrogen and safety injection water. A safety injection outlet pipe is arranged at the bottom of the pressure container. The damping device is arranged in the pressure container. The damping device is provided with a water inlet and a water outlet. The water inlet is communicated with the inside of the pressure container, and the water outlet is connected with the safety injection outlet pipe. The safety injection water in the pressure container flows from the water inlet through the damping device and then flows from the water outlet to the safety injection outlet pipe.

[0019] The pressure vessel with damping device can automatically adjust the injection flow. The injection flow of the pressure vessel gradually decreases with the progress of the loss of coolant accident. Compared with the pressure vessel without damping device, the flow is lower in the initial stage of the accident, avoiding the loss of injection water. The flow in the refilling and reflooding stage of the accident can quickly realize the refilling of the lower chamber and the reflooding of the core. The injection flow is lower after the core is reflooded, which fully extends the injection time. Effectively responding to the loss of coolant accident can also fully improve the safety of the reactor, ensure that radioactive materials do not leak, and ensure safety for a longer period of time after the accident.

[0020] The safety injection method, implemented using the above-mentioned safety injection system, can improve the problem of mismatch between the water injection flow of the safety injection system and the flow required during the reactor loss of coolant accident stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0022] Figure 1 A schematic diagram of the internal structure of a safe injection system provided by an embodiment of the present invention; Figure 2 A top view of a straw in a safe injection system provided by an embodiment of the present invention; Figure 3 The first cyclone in the safety injection system provided by the embodiment of the present invention is Figure 1 Top view of the AA section; Figure 4 The second cyclone in the safety injection system provided by the embodiment of the present invention is Figure 1 Top view of the BB section.

[0023] Icons: pressure vessel -10; injection outlet pipe -11; suction pipe -20; rotary vane -21; first cyclone -30; drainage pipe -31; first chamber -311; cyclone outlet pipe -32; second cyclone -40; first circular plate -401; upper outer ring side wall -411; outer ring shell -41; annular side wall -48; upper inner ring side wall -42; lower outer ring side wall -43; circular plate -47; lower inner ring side wall -44; support block -12; drainage plate -45; guide plate -46; second chamber -50; spiral channel -60; water inlet channel -70. DETAILED DESCRIPTION

[0024] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the aspects described below in conjunction with the accompanying drawings and specific embodiments are only exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0025] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", "vertical" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or is the orientation or position relationship in which the product of the invention is usually placed when used, rather than indicating or implying that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0026] At the same time, it should be noted that the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified or limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, an integral connection, or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or the internal communication of two components, etc. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Combine the following Figures 1 to 4 The safe injection system provided in this embodiment is described in detail.

[0029] Please refer to Figure 1An embodiment of the present invention provides a safety injection system, including a pressure container 10 and a damping device. The pressure container 10 is used to contain nitrogen and safety injection water. A safety injection outlet pipe 11 is arranged at the bottom of the pressure container 10; the damping device is arranged in the pressure container 10, and the damping device is provided with a water inlet and a water outlet. The water inlet is connected to the inside of the pressure container 10, and the water outlet is connected to the safety injection outlet pipe 11; the safety injection water in the pressure container 10 flows from the water inlet through the damping device, and then flows from the water outlet to the safety injection outlet pipe 11.

[0030] Reference Figure 1 Specifically, the pressure vessel 10 is hollow inside, the middle part of the pressure vessel 10 is a cylindrical body, and the top and bottom of the pressure vessel 10 are semi-ellipsoidal or hemispherical. The material of the pressure vessel 10 is stainless steel, or carbon steel with a stainless steel cladding layer, which can withstand an internal pressure of more than 4 to 7 MPa. The bottom of the pressure vessel 10 is opened and connected to the injection outlet pipe 11. A certain proportion of injection water containing boric acid is filled inside the pressure vessel 10, and pressurized nitrogen is filled in the remaining upper space. The proportion of nitrogen in the internal space of the pressure vessel 10 is about 1 / 7 to 1 / 3, and the nitrogen pressure is about 3 to 6 MPa. When a loss of coolant accident occurs in the reactor, the injection water will flow from the pressure vessel 10 through the damping device under the pressure of the internal nitrogen and then be discharged from the injection outlet pipe 11 to enter the main system of the reactor.

[0031] A damping device is provided in the pressure vessel 10. When a loss of coolant accident occurs, the injection water flows through the damping device and is injected into the reactor main system from the injection outlet pipe 11. The damping device has a damping effect on the discharge of the injection water. Therefore, compared with the pressure vessel 10 without a damping device, in the initial stage of injection, the flow rate discharged from the injection outlet pipe 11 will be reduced within only 10 seconds during the accident process, which can prevent the injection water from being entrained out of the main system due to the interaction with a large amount of high-temperature and high-pressure water vapor in the main system in the initial stage of the accident, thereby reducing the bypass loss of the injection water. In the middle stage of a loss of coolant accident, the level of the anvil water is still very high. Under the action of nitrogen pressure and the pressure of the anvil water, the pressure vessel 10 can still discharge a large amount of anvil water to quickly flood the lower chamber of the core and the exposed reactor core; in the later stage of a loss of coolant accident, the level of the anvil water in the pressure vessel 10 drops and the flow rate decreases. Compared with the pressure vessel 10 without a damping device, after the damping device is installed, the anvil water flow rate will be lower and the discharge time will be extended, thereby meeting the demand for a very small anvil flow rate after the core is flooded again, thereby extending the flooding time and avoiding the waste of anvil water.

[0032] Therefore, the pressure vessel 10 with the damping device can automatically adjust the injection flow rate. Compared with the pressure vessel 10 without the damping device, the flow rate is low in the initial stage to avoid injection water loss; the flow rate in the middle stage can quickly achieve the refilling of the lower chamber and the reflooding of the core; the flow rate is low in the late injection stage to fully extend the injection time. Effectively responding to the loss of coolant accidents can also fully improve the safety of the reactor, ensure that radioactive materials do not leak, and ensure safety for a longer period of time after the accident.

[0033] Reference Figure 1 and Figure 2 In this embodiment, the damping device includes a suction pipe 20, which is arranged above the injection outlet pipe 11 and communicated with the injection outlet pipe 11. The suction pipe 20 is provided with a rotating vane 21 that rotates clockwise or counterclockwise. The rotating vane 21 is used to guide the injection water to be injected into the injection outlet pipe 11 in a counterclockwise or clockwise direction. At this time, the water inlet of the damping device is the top end of the suction pipe 20, and the water outlet of the damping device is the bottom end of the suction pipe 20.

[0034] Specifically, refer to Figure 2 The suction pipe 20 is a circular tube, the lower end of which is vertically inserted into the first cyclone 30 mentioned below, and the upper end is immersed below the water level of the injection water in the pressure container 10. A rotary blade 21 is arranged inside the suction pipe 20. The rotary blade 21 can be a spiral blade type, or it can be composed of 2 or more blades with a certain inclination angle. Whether it is a spiral blade type or multiple blades are spirally distributed, it can rotate clockwise or counterclockwise. When water flows into the suction pipe 20 from top to bottom, under the action of the rotary blade 21, the injection water will be converted into a counterclockwise or clockwise downward circumferential flow.

[0035] When a loss of coolant occurs, the injection water enters from the suction pipe 20, flows through the rotary vane 21, circulates counterclockwise or clockwise downward, and then flows out from the injection outlet pipe 11. The damping effect of the rotary vane 21 can reduce the drainage flow of the injection outlet pipe 11, thereby reducing the injection water loss caused by the injection bypass phenomenon in the initial stage of the loss of coolant, and can also meet the problem of a small injection water flow required in the later stage of the loss of coolant.

[0036] Reference Figure 1 and Figure 3In this embodiment, the damping device further comprises a first cyclone 30, which is provided with a first chamber 311 and a drainage pipe 31 connected to the first chamber 311, the drainage pipe 31 is connected to the inside of the pressure container 10, and the drainage pipe 31 is used to guide the injection water to be injected into the first chamber 311 in a clockwise or counterclockwise direction; the suction pipe 20 is provided above the first cyclone 30, and the suction pipe 20 is connected to the first chamber 311, and the rotary vane 21 is used to guide the injection water to be injected into the first chamber 311 in a counterclockwise or clockwise direction, and the height of the suction pipe 20 is higher than the height of the drainage pipe 31. At this time, the water inlet of the damping device is the top pipe opening of the suction pipe 20, and the water outlet of the damping device is the cyclone outlet pipe 32 of the first cyclone 30.

[0037] Specifically, the first cyclone 30 has an inverted cone at the bottom and a cylinder at the top. The top of the first cyclone 30 is a horizontal circular flat plate. The first cyclone 30 is hollow inside. Figure 3 As shown, at the upper part of the first cyclone 30, a drainage pipe 31 is horizontally connected along the tangent line of the side wall in a counterclockwise or clockwise direction, so that the injection water in the pressure container 10 can be introduced into the first chamber 311 in a counterclockwise or clockwise direction.

[0038] The first cyclone 30 is also provided with a cyclone outlet pipe 32 at the bottom, and the injection water entering the first chamber 311 can flow out from the cyclone outlet pipe 32. The lower end of the cyclone outlet pipe 32 is vertically inserted into the second cyclone 40 mentioned below.

[0039] Since the injection water entering the first chamber 311 from the suction pipe 20 flows counterclockwise under the action of the suction pipe vane 21, and the injection water entering the first chamber 311 from the drainage pipe 31 of the first cyclone 30 also flows counterclockwise, and the inverted cone at the bottom of the first cyclone 30 allows the two streams of water to still flow downward in a counterclockwise direction after merging, which makes the two streams of water have a greater damping effect when discharged from the cyclone outlet pipe 32. Therefore, compared with the pressure container without the suction pipe 20 and the first cyclone 30, in the initial stage of injection, the flow rate discharged from the cyclone outlet pipe 32 is lower, which can avoid the loss of injection water caused by the interaction between the injection water and the large amount of high-temperature and high-pressure water vapor in the main system in the initial stage of the accident and being entrained out of the main system. In the later stage of the accident, the low flow rate can just meet the water demand in the re-flooding stage, reduce the loss of injection water, and effectively utilize the injection water.

[0040] Reference Figure 1 and Figure 3 In this embodiment, only one drainage pipe 31 may be provided, or two or more drainage pipes 31 may be provided which are symmetrical with respect to the center. When a plurality of drainage pipes 31 are provided, each drainage pipe 31 can ensure that the injection water in the pressure vessel 10 is introduced into the first cyclone 30 in a counterclockwise direction.

[0041] Reference Figure 1 and Figure 4 In this embodiment, the damping device further includes a second cyclone 40, which is arranged above the injection outlet pipe 11; the second cyclone 40 is provided with a second chamber 50 connected to the injection outlet pipe 11, and a water inlet channel 70 connected to the pressure container 10 and the second chamber 50 and bent in the height direction; a water seal can be formed in the water inlet channel 70 to prevent nitrogen from entering the second chamber 50 from the water inlet channel 70; the first cyclone 30 is arranged above the second cyclone 40, and the first chamber 311 is connected to the second chamber 50. At this time, the water inlet of the damping device is the top pipe opening of the suction pipe 20, and the water outlet of the damping device is the bottom end of the second cyclone 40 connected to the injection outlet pipe 11.

[0042] Specifically, the suction pipe 20, the first cyclone 30 and the second cyclone 40 are sequentially arranged and installed in the pressure container 10 from top to bottom. For the existing injection box, the container shell itself is the pressure container 10. If it is improved based on the present invention, it only needs to connect the bottom end of the second cyclone 40 to the outlet of the existing injection box internally to complete the installation. The installation is simple and convenient, and the transformation and upgrading of the existing injection box can be realized.

[0043] The installation process of the suction pipe 20, the first cyclone 30 and the second cyclone 40 in the pressure container 10 is as follows: Similarly, a certain proportion of injection water containing boric acid is pre-filled into the pressure vessel 10, and pressurized nitrogen is filled into the remaining upper space, and the injection water surface is higher than the suction tube 20. After a loss of coolant accident occurs in the reactor system, when the main system pressure is lower than the pressure of the nitrogen pre-filled into the pressure vessel 10, the injection water in the pressure vessel 10 will be discharged outward under the drive of the nitrogen.

[0044] At the beginning of the accident, when the water level is higher than the top of the suction pipe 20, the injection water can enter the first cyclone 30 from the suction pipe 20, or enter the first cyclone 30 from the drainage pipe 31, and can also enter the second cyclone 40 from the water inlet channel 70. The injection water entering the suction pipe 20 and the first cyclone 30 enters the second cyclone 40 from the cyclone outlet pipe 32, and all the injection water will be discharged from the injection outlet pipe 11 to the reactor main system.

[0045] Since the injection water entering the first cyclone 30 from the suction pipe 20 rotates counterclockwise or clockwise, and the injection water entering the first cyclone 30 from the drainage pipe 31 rotates counterclockwise or clockwise, the two water flows merge at the inverted cone at the bottom of the first cyclone 30 and still flow downward in a counterclockwise or clockwise direction, which makes the two water flows have a greater damping effect when discharged from the cyclone outlet pipe 32.

[0046] The injection water entering the second cyclone 40 from the water inlet channel 70 will pass through the water inlet channel 70 with up and down bends in sequence, that is, the flow speed will be damped. "Up and down bends" refers to a channel that is bent up and down in the height direction or bent up and down, and bends twice or more, and after multiple damping effects, finally flows into the second chamber 50 of the second cyclone 40.

[0047] Therefore, in the initial stage of the safety injection (only within 10 seconds during the accident process), the flow rate discharged from the cyclone outlet pipe 32 is low, and the flow rate discharged from the second cyclone 40 is low, which can avoid the loss of safety injection water caused by the safety injection water being entrained out of the main system due to the interaction with the large amount of high-temperature and high-pressure water vapor in the main system in the initial stage of the accident, and can reduce the amount of water in the safety injection bypass.

[0048] In the middle of the accident, as the temperature and pressure of the main system decrease, the water vapor in the main system cannot carry the injection water out of the main system, and a large amount of injection water is needed to quickly submerge the exposed reactor core. At this time, the water level in the pressure vessel 10 has dropped below the top of the suction pipe 20. Therefore, the rotor 21 will not play the role of making the injection water flow counterclockwise, reducing the damping effect when it is discharged from the cyclone outlet pipe 32. At the same time, from the initial water level of the pressure vessel 10 to the top of the suction pipe 20, the water volume can be adjusted to within 5% of the total water volume. According to the different designs of the reactor, the length of the suction pipe 20 can be adjusted as needed, and then the ratio can be adjusted. The pressure of nitrogen reduced by expansion is small, and a large driving force can still be guaranteed. Therefore, the injection water discharged from the cyclone outlet pipe 32 and then from the second cyclone 40 at this stage can have a large flow rate, and the core can be quickly re-flooded.

[0049] In the later stage of the accident, the water level in the pressure vessel 10 has dropped below the drainage pipe 31, and the injection water can only enter the second cyclone 40 through the water inlet channel 70 and be discharged. From the initial water level of the pressure vessel 10 to the elevation of the drainage pipe 31, the water volume can be adjusted to within 70% of the total water volume. According to the different designs of the reactor, the length of the cyclone outlet pipe 32 can be adjusted as appropriate to adjust the ratio. Since the injection water needs to pass through the water inlet channel 70 bent in the height direction to enter the second chamber 50, and finally be discharged from the injection outlet pipe 11 to the reactor main system. This process path is long, so there is a large resistance, which makes the flow rate discharged from the injection outlet pipe 11 to the reactor main system low, which fully extends the injection time.

[0050] Finally, when the water level in the pressure container 10 drops below the highest water level of the upper and lower bends in the water inlet channel 70, the injection water can no longer flow into the second chamber 50 through the water inlet channel 70, and a water seal will be formed in the water inlet channel 70, preventing nitrogen from entering the second chamber 50 from the water inlet channel 70. Figure 1The approximate location where the water seal is formed is shown in the figure. Figure 1 The figure is only a schematic representation and does not represent the exact location where the water seal is formed.

[0051] Therefore, the safety injection system provided by the present embodiment can automatically adjust the injection flow rate in the early stage, middle stage and late stage of the accident. The injection water discharge volume of the pressure vessel 10 gradually decreases with the progress of the accident, and the damping effect of the damping device gradually decreases with the progress of the accident. Compared with the pressure vessel without a damping device, in the initial stage, the suction pipe 20, the first cyclone 30 and the second cyclone 40 have damping effects, and the flow rate is low, thereby avoiding the loss of injection water. In the middle stage, the injection discharge volume of the pressure vessel 10 itself is large, and the damping of the suction pipe 20 is reduced at the same time, and the injection water discharge volume can quickly achieve core re-flooding. In the late injection stage, the injection discharge volume of the pressure vessel 10 itself is small, and there is also the damping effect of the second cyclone 40, and the flow rate is low, which fully extends the injection time, effectively utilizes the injection water, and provides sufficient redundant time for the investment of the low-pressure injection pump. In the final stage, a water seal can be formed in the water inlet channel 70. If it is emptied, the pressurized nitrogen injected into the main system may block the safety injection flow channel and may also affect the core heat exchange. Therefore, the water seal is used to prevent nitrogen from entering the main system, which can avoid the impact of nitrogen on the mitigation of loss of coolant accidents.

[0052] It should be noted that there is no restriction on whether the water flow in the suction pipe 20, the first cyclone 30 and the second cyclone 40 is counterclockwise or clockwise. As long as it is clockwise or counterclockwise, it can cause a damping effect and hinder the flow of the injection water. In this embodiment, the counterclockwise direction is mainly used as an example for illustration. Figure 2 In the process, the rotary blade 21 guides the injection water to rotate counterclockwise. Figure 3 In the process, the drainage pipe 31 guides the injection water to rotate counterclockwise. Figure 4 The arc plate guides the water injection to rotate counterclockwise; the rotary blade 21, the drainage tube 31 and the arc plate can guide the water injection to rotate counterclockwise, or they can guide the water injection to rotate clockwise, and the counterclockwise direction or clockwise direction of the three do not need to be consistent.

[0053] Reference Figure 1 In this embodiment, a spiral channel 60 rotating in a clockwise or counterclockwise direction is further provided in the second cyclone 40. The spiral channel 60 connects the second chamber 50 and the water inlet channel 70. The spiral channel 60 is used to guide the injection water to rotate in a clockwise or counterclockwise direction and be injected into the second chamber 50.

[0054] The water inlet channel 70 and the spiral channel 60 make the process of the injection water entering the second chamber 50 not only have a longer path, but the injection water entering the second chamber 50 through the spiral channel 60 continues to flow around in the cone of the second cyclone 40, which also has a large damping effect on the discharge of the injection water, which makes the flow rate discharged from the injection outlet pipe 11 to the reactor main system lower, thereby fully extending the injection time.

[0055] The water seal formed in the water inlet channel 70 isolates the interior of the pressure vessel 10 and the second chamber 50, and the injection water that previously entered the second chamber 50 through the water inlet channel 70 and the spiral channel 60 enters tangentially through the spiral channel 60, forming a forced vortex flow in the conical second chamber 50. The liquid has a large density and is thrown to the wall of the cyclone, while the nitrogen has a small density and migrates to the center; the low-pressure area in the second chamber 50 prompts the central nitrogen to flow upward, enter the first cyclone 30 through the cyclone outlet pipe 32, and then be discharged upward to the pressure vessel 10, while the injection water flows downward through the injection outlet pipe 11 into the core, and the centrifugal force of the second cyclone 40 is used to achieve gas-liquid separation without additional energy consumption, preventing nitrogen from entering the main system downward through the injection outlet pipe 11, which may block the pipeline or reduce the cooling efficiency.

[0056] Reference Figure 1 In this embodiment, the second cyclone 40 includes an upper shell and a lower shell, the upper shell and the lower shell are spaced apart, a second chamber 50 is formed between the upper shell and the lower shell, and a water inlet channel 70 is arranged around the second chamber 50; the lower shell is connected to the injection outlet pipe 11.

[0057] The second chamber 50 is located at the center of the second cyclone 40, and the water inlet channel 70 is arranged around the second chamber 50. The water inlet channel 70 bends up and down for many times before entering the second chamber 50. Specifically, after the water enters the water inlet channel 70, it flows upward, then flows downward, and then flows upward. After flowing for several times, it enters the second chamber 50. The specific number of up and down cycles can be designed according to the relationship between the flow rate and the damping effect provided by actual needs. The more cycles, the greater the damping and the smaller the flow rate; the fewer cycles, the smaller the damping and the greater the flow rate. In other embodiments, the water inlet channel 70 can also adopt a channel structure similar to a maze distribution.

[0058] Reference Figure 1In this embodiment, the upper shell includes a first circular flat plate 401, an upper outer ring side wall 411 and an upper inner ring side wall 42 which are connected in sequence. The upper inner ring side wall 42 is arranged at an angle with the upper outer ring side wall 411, and the upper inner ring side wall 42 is located on the inner side of the upper outer ring side wall 411; the lower shell includes a lower inner ring side wall 44, a circular flat plate 47 and a lower outer ring side wall 43 which are connected in sequence. The lower inner ring side wall 44 and the lower outer ring side wall 43 are arranged at intervals; the upper outer ring side wall 411 is arranged at intervals from the inner wall of the pressure container 10, and the first circular flat plate 401 and the circular flat plate 47 are arranged at intervals. The lower inner ring side wall 44 is connected to the injection outlet, and a second chamber 50 is formed between the lower inner ring side wall 44 and the first circular flat plate 401; the lower inner ring side wall 44, the upper inner ring side wall 42, the lower outer ring side wall 43 and the upper outer ring side wall 411 are arranged in sequence along the diameter direction of the first circular flat plate 401 to form a water inlet channel 70 that bends up and down from the bottom of the pressure container 10 to enter the second chamber 50; when the water level of the injection water is lower than the height of the top of the upper inner ring side wall 42, a water seal is formed between the lower inner ring side wall, the upper inner ring side wall, the lower outer ring side wall and the upper outer ring side wall.

[0059] Specifically, the upper outer ring sidewall 411 includes a vertical annular sidewall 48 and a downwardly curved outer ring shell 41 connected in sequence. The first circular plate 401 is a circular plate with a central opening, connected to the cyclone outlet pipe 32, and the circular plate 47 is kept horizontal with the first circular plate 401 at the top of the second cyclone 40.

[0060] The annular side wall 48 is a vertical cylinder, the top of the annular side wall 48 is connected to the outer edge of the first circular flat plate 401, the bottom of the annular side wall 48 is connected to the top of the outer ring shell 41, and a certain gap is left between the annular side wall 48 and the inner wall of the pressure container 10, which serves as the entrance of the water inlet channel 70. The outer ring shell 41 is a thin shell with a certain curvature and a central symmetry, and has the same curvature as the bottom of the pressure container 10.

[0061] The upper inner ring side wall 42, the lower outer ring side wall 43, and the lower inner ring side wall 44 are all inverted cones and have the same cone angle. The three are respectively the lower inner ring side wall 44, the upper inner ring side wall 42, and the lower outer ring side wall 43 from the inside to the outside in the radial direction. The bottom end of the lower inner ring side wall 44 is connected to the top of the injection outlet pipe 11, that is, the bottom of the pressure container 10; the top end of the lower inner ring side wall 44 is connected to the central opening of the circular ring plate 47. The bottom end of the upper inner ring side wall 42 is connected to the lower end of the outer ring shell 41, and a certain gap is left between the top end of the upper inner ring side wall 42 and the circular ring plate 47 in the vertical direction. The top end of the lower outer ring side wall 43 is connected to the outer edge of the circular ring plate 47, and a certain gap is left between the bottom end of the lower outer ring side wall 43 and the outer ring shell 41 in the vertical direction. The upper inner ring side wall 42 is inserted between the lower inner ring side wall 44 and the lower outer ring side wall 43 , and the lower outer ring side wall 43 is inserted between the upper inner ring side wall 42 and the outer ring shell 41 , forming a water inlet channel 70 flowing from the bottom of the pressure container 10 into the second chamber 50 .

[0062] The height setting of the upper inner ring side wall 42 determines the position of forming a water seal. When the water level in the pressure container 10 is lower than the top surface of the upper inner ring side wall 42, the injection water cannot enter the second chamber 50 through the water inlet channel 70 to form a water seal.

[0063] In the early, middle and late stages of an accident, the process of entering the second cyclone 40 from the water inlet channel 70 is as follows: the injection water entering the second cyclone 40 from the gap between the outer wall of the outer ring shell 41 of the second cyclone 40 and the inner wall of the pressure vessel 10 will sequentially pass through the gap flow channel between the lower inner ring side wall 44 and the upper inner ring side wall 42, the gap flow channel between the upper inner ring side wall 42 and the lower outer ring side wall 43, the gap flow channel between the lower outer ring side wall 43 and the inner wall of the outer ring shell 41, and the gap flow channel between the guide plate 45 and the annular side wall 48, and enter the second chamber 50.

[0064] Reference Figure 1 and Figure 4 In this embodiment, the second cyclone 40 further includes an arc plate, which is spirally fixed between the first circular flat plate 401 and the annular flat plate 47 to form a spiral channel 60 that rotates counterclockwise or clockwise. The spiral channel 60 connects the water inlet channel 70 and the second chamber 50.

[0065] An arc plate is arranged in the interlayer between the first circular flat plate 401 and the annular flat plate 47. The arc plate is a vertical arc plate, and its top and bottom are respectively connected to the first circular flat plate 401 and the annular flat plate 47. The injection water enters the gap flow channel between the arc plate and the guide plate 46, and then flows around in a counterclockwise direction to enter the lower inner ring side wall 44, and finally discharged from the injection outlet pipe 11 to the reactor main system.

[0066] Reference Figure 1 and Figure 2In this embodiment, the number of the arc-shaped plates is two, and the two arc-shaped plates are symmetrically arranged with respect to the center of the first circular flat plate 401 to form a spiral channel 60 .

[0067] Specifically, each arc plate includes a guide plate 45 and a guide plate 46 ; the guide plate 45 and the guide plate 46 have different curvatures and lengths, and both the guide plate 45 and the guide plate 46 are vertically arranged arc plates connected to the first circular flat plate 401 and the annular flat plate 47 .

[0068] Reference Figure 4 There are two guide plates 45, which are centrally symmetrically arranged; there are two guide plates 46, which are centrally symmetrically arranged; one end of the guide plate 45 is connected to the annular side wall 48, and a certain gap is left between the guide plate 45 and the annular side wall 48; the other end of the guide plate 45 is connected to the guide plate 46, and a certain gap is left between the guide plate 46 and the guide plate 45.

[0069] The guide plate 45, the annular side wall 48, and the gap flow passages formed by the guide plate 45 and the guide plate 46 in spiral communication in sequence can make the injection water flow in a counterclockwise direction, be introduced into the lower inner annular side wall 44, and then be discharged to the reactor main system from the injection outlet pipe 11. If it is desired to achieve a clockwise flow, it is also possible, and the clockwise flow can be achieved by simply changing the arrangement direction of the guide plate 45 and the guide plate 46.

[0070] Reference Figure 1 In this embodiment, the safe injection system also includes a support block 12 and a guide vane. The upper shell is connected and supported to the inner wall of the pressure container 10 through the support block 12 or the guide vane; the guide vane is spirally arranged clockwise or counterclockwise.

[0071] In the gap between the outer ring housing 41 and the inner wall of the pressure container 10, 2 to 4 support blocks 12 are arranged, or multiple support blocks are arranged, to support the second cyclone 40. In other embodiments, the support blocks 12 can also be replaced by guide vanes, which can play a supporting role and a counterclockwise or clockwise guiding role, so that the injection water entering the water inlet channel 70 rotates clockwise or counterclockwise.

[0072] Reference Figure 1 In this embodiment, the central axes of the pressure container 10, the suction pipe 20, the first cyclone 30, the second cyclone 40 and the injection outlet pipe 11 all coincide with each other.

[0073] Among them, the suction pipe 20, the first cyclone 30, the drainage pipe 31, the cyclone outlet pipe 32, the second cyclone 40, the outer ring shell 41, the upper inner ring side wall 42, the lower outer ring side wall 43, the lower inner ring side wall 44, the drainage plate 45, the guide plate 46, the circular ring flat plate 47, and the annular side wall 48 can all be made of stainless steel or other corrosion-resistant metals or high-strength high-polymer materials.

[0074] The embodiment of the present invention further provides a safe injection method. The safe injection method is implemented by a safe injection system and includes: When a reactor loss of coolant accident occurs, the injection water in the pressure vessel flows through the damping device and is injected into the reactor main system from the injection outlet pipe.

[0075] Specifically, when the water level of the injection water is higher than the height of the suction pipe 20 , the injection water is respectively injected into the second chamber 50 from the suction pipe 20 , the drainage pipe 31 and the water inlet channel 70 , and is discharged from the injection outlet pipe 11 .

[0076] When the water level of the injection water is lower than the height of the suction pipe 20 and higher than the height of the drainage pipe 31 , the injection water is respectively injected into the first chamber 311 from the drainage pipe 31 , injected into the second chamber 50 from the water inlet channel 70 , and discharged from the injection outlet pipe 11 .

[0077] When the water level of the injection water is lower than the height of the drainage pipe 31, the injection water is injected into the second chamber 50 from the water inlet channel 70, discharged from the injection outlet pipe 11, and finally forms a water seal in the water inlet channel 70 to prevent nitrogen from entering the second chamber 50 from the water inlet channel 70. Specifically, in the late stage of the accident, water is injected only through the water inlet channel 70, the water flow rate is reduced, and the injection time is prolonged.

[0078] According to a safe injection system provided in this embodiment, the working principle of the safe injection system includes: A completely passive safety injection water tank design suitable for pressurized water reactors is proposed. It can fully and effectively utilize the boron-containing water stored in the tank, significantly extend the injection time, effectively deal with loss of coolant accidents, and fully improve reactor safety, ensure that radioactive materials do not leak, and ensure safety for a longer period of time after an accident.

[0079] Three-stage damping devices are arranged in the pressure vessel 10, namely the suction pipe 20, the first cyclone 30 and the second cyclone 40. Compared with the original injection tank, in the initial stage of the accident, the suction pipe 20, the second cyclone 40 and the first cyclone 30 work at the same time, and the discharge flow rate of the injection water is reduced the most; in the middle stage of the accident, the suction pipe 20 does not work, the first cyclone 30 and the second cyclone 40 work, and the reduction range of the discharge flow rate of the injection water is narrowed; in the late stage of the accident, the suction pipe 20 and the first cyclone 30 do not work, the second cyclone 40 works, and the discharge flow rate of the injection water is reduced the least. Combined with the trend that the water injection amount of the pressure vessel itself gradually decreases with the progress of the accident, it can just meet the water amount required to maintain the core flooding in the late stage of the accident without waste.

[0080] The safe injection system provided by this embodiment has at least the following advantages: A damping device is installed in the pressure vessel to automatically adjust the injection flow rate. The flow rate is low in the initial stage to avoid injection water loss; the flow rate is high in the middle stage to quickly refill the lower chamber and reflood the core; the flow rate is low in the late injection period to fully extend the injection time, effectively utilize the injection water, and provide sufficient redundant time for the low-pressure injection pump. The passive technology is adopted, there are no moving parts, which greatly reduces the possibility of failure and is easy to maintain.

[0081] In the later stage of the accident, a water seal can be formed in the water inlet channel 70, which prevents the pressurized nitrogen from being injected into the main system during emptying, thereby avoiding the influence of nitrogen on the mitigation of the loss of coolant accident.

[0082] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technology in the field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A safe injection system, characterized in that: include: A pressure container, the pressure container is used to contain nitrogen and injection water, and the bottom of the pressure container is provided with an injection outlet pipe; and a damping device, the damping device being arranged in the pressure container, the damping device being provided with a water inlet and a water outlet, the water inlet being communicated with the interior of the pressure container, the water outlet being connected with the anzhu outlet pipe; the anzhu water in the pressure container flows from the water inlet through the damping device, and then flows from the water outlet to the anzhu outlet pipe; The damping device includes a suction pipe, which is arranged above the anzhu outlet pipe and is connected to the anzhu outlet pipe. The interior of the suction pipe is provided with rotating blades that rotate in a clockwise or counterclockwise direction. The rotating blades are used to guide the anzhu water to be injected into the anzhu outlet pipe in a counterclockwise or clockwise direction.

2. The safe injection system according to claim 1, characterized in that: The damping device further comprises a first cyclone, wherein the first cyclone is provided with a first chamber and a drainage pipe communicating with the first chamber, the drainage pipe being communicated with the interior of the pressure container, and the drainage pipe being used to guide the injection water to be injected into the first chamber in a clockwise or counterclockwise direction; The suction pipe is arranged above the first cyclone and is connected to the first chamber. The rotary vane is used to guide the injection water to be injected into the first chamber in a counterclockwise or clockwise direction. The height of the suction pipe is higher than that of the drainage pipe.

3. The safe injection system according to claim 2, characterized in that: The damping device further comprises a second cyclone, which is arranged above the injection outlet pipe; the second cyclone is provided with a second chamber connected to the injection outlet pipe, and a water inlet channel connected to the pressure container and the second chamber and bent in the height direction; a water seal can be formed in the water inlet channel to prevent nitrogen from entering the second chamber from the water inlet channel; The first cyclone is arranged above the second cyclone, and the first chamber is communicated with the second chamber.

4. The safe injection system according to claim 3, characterized in that: The second cyclone is also provided with a spiral channel rotating in a clockwise or counterclockwise direction, the spiral channel connecting the second chamber and the water inlet channel, and the spiral channel is used to guide the injection water to rotate in a clockwise or counterclockwise direction and be injected into the second chamber.

5. The safe injection system according to claim 4, characterized in that: The second cyclone comprises an upper shell and a lower shell, the upper shell and the lower shell are spaced apart, the second chamber and the water inlet channel arranged around the second chamber are formed between the upper shell and the lower shell; the lower shell is connected to the injection outlet pipe.

6. The safe injection system according to claim 5, characterized in that: The upper shell comprises a first circular flat plate, an upper outer ring side wall and an upper inner ring side wall which are connected in sequence, the upper inner ring side wall is arranged at an angle with the upper outer ring side wall, and the upper inner ring side wall is located on the inner side of the upper outer ring side wall; The lower shell comprises a lower inner ring side wall, a circular ring flat plate and a lower outer ring side wall which are connected in sequence, and the lower inner ring side wall and the lower outer ring side wall are arranged at intervals; The upper outer ring side wall is spaced apart from the inner wall of the pressure container, the first circular flat plate and the circular flat plate are spaced apart, the lower inner ring side wall is connected to the injection outlet, and the second chamber is formed between the lower inner ring side wall and the first circular flat plate; the lower inner ring side wall, the upper inner ring side wall, the lower outer ring side wall and the upper outer ring side wall are sequentially spaced apart along the diameter direction of the first circular flat plate, forming the water inlet channel that bends up and down from the bottom of the pressure container and enters the second chamber; When the water level of the injection water is lower than the height of the top end of the upper inner ring side wall, the water seal is formed between the lower inner ring side wall, the upper inner ring side wall, the lower outer ring side wall and the upper outer ring side wall.

7. The safe injection system according to claim 6, characterized in that: The second cyclone further includes an arc plate, which is spirally fixed between the first circular flat plate and the annular flat plate to form the spiral channel arranged in a counterclockwise or clockwise rotation.

8. The safe injection system according to any one of claims 5 to 7, characterized in that: The safety injection system further comprises a support block and a guide vane, and the upper shell is connected and supported to the inner wall of the pressure container via the support block or the guide vane; the guide vane is spirally arranged in a clockwise or counterclockwise manner.

9. A safe injection method, implemented by using the safe injection system according to any one of claims 1 to 8, characterized in that: The safe injection method comprises: When a reactor loss of coolant accident occurs, the injection water in the pressure vessel flows through the damping device and then is injected into the reactor main system from the injection outlet pipe.

Images