Safe injection system and method

Abstract

Embodiments of the present invention provide a safety injection system and method, which relate to the field of reactor safety systems. The aim is to improve the problem that the water injection flow rate of the safety injection system does not match the flow rate required during the loss-of-coolant accident stage of the reactor. It includes a pressure-bearing container and a damping device. An emergency injection outlet pipe is provided at the bottom of the pressure-bearing container; the damping device is arranged inside the pressure-bearing container. The damping device is provided with a water inlet and a water outlet. The emergency injection water inside the pressure-bearing container flows through the damping device from the water inlet and then flows from the water outlet to the emergency injection outlet pipe. The discharge flow rate of the emergency injection water inside the pressure-bearing container shows a gradually decreasing trend along with the process of the loss-of-coolant accident. Compared with the pressure-bearing container without damping, the flow rate in the initial stage is lower, which can reduce the amount of water bypassed during emergency injection; the flow rate in the intermediate stage can quickly realize the re-filling of the lower plenum of the reactor core and the re-submergence of the reactor core; the flow rate for maintaining the submergence of the reactor core in the later stage of the accident is lower, which can fully extend the emergency injection time and effectively utilize the emergency injection water.

Description

Technical Field

[0001] The present invention relates to the field of reactor safety systems, and more particularly, 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 when a loss-of-coolant accident occurs in the reactor, so as to ensure the integrity of the core.

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

[0004] In a large-break reactor loss-of-coolant accident, the blowdown phase, reflooding phase, and reflooding phase are the core links in the development of the accident. 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 cold-leg large-break loss-of-coolant accident, the steam will flow from the downcomer of the reactor pressure vessel to the cold-leg break. At this time, when the safety injection water from the accumulator enters the downcomer, affected by these steams, it may be entrained and flow towards the break, thus unable to enter the reactor core, that is, the so-called safety injection bypass phenomenon occurs. In the core reflooding phase and reflooding phase of a large-break loss-of-coolant accident, a relatively large injection flow rate is required to quickly fill the lower plenum and achieve core reflooding. The traditional accumulator can provide a large flow rate that meets the requirements in this phase. After the core is reflooded, only a very small injection flow rate is needed at this time. However, even though the injection flow rate of the traditional accumulator gradually decreases with the progress of the accident, the flow rate provided by the traditional accumulator at this time still exceeds the injection flow rate required after the core is reflooded, causing excessive boron-containing water to overflow from the break and failing to effectively utilize the boron-containing water in the accumulator. Summary of the Invention

[0005] The following presents a brief overview of one or more aspects to provide a basic understanding of these aspects. This overview is not an exhaustive survey of all contemplated aspects, and is neither intended to identify key or decisive elements of all aspects nor to attempt to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that follows.

[0006] The objectives of the present invention include, 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 required flow rate during the loss-of-coolant accident stage of the reactor.

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

[0008] Embodiments of the present invention can be implemented as follows:

[0009] Embodiments of the present invention provide a safety injection system, including a pressure-bearing container and a damping device. The pressure-bearing container is used to contain nitrogen and safety injection water, and a safety injection outlet pipe is provided at the bottom of the pressure-bearing container; the damping device is arranged inside the pressure-bearing container, and the damping device is provided with a water inlet and a water outlet. The water inlet is communicated with the inside of the pressure-bearing container, and the water outlet is connected to the safety injection outlet pipe; the safety injection water in the pressure-bearing container flows from the water inlet through the damping device and then flows from the water outlet to the safety injection outlet pipe.

[0010] In addition, the safety injection system provided by the embodiments of the present invention may also have the following additional technical features:

[0011] Optionally, the damping device includes a suction pipe, which is arranged above the safety injection outlet pipe and communicated with the safety injection outlet pipe. Inside the suction pipe, there are rotating blades distributed in a clockwise or counterclockwise direction for guiding the safety injection water to be injected into the safety injection outlet pipe in a counterclockwise or clockwise direction.

[0012] Optionally, the damping device further includes a first cyclone. The first cyclone is provided with a first chamber and a drainage pipe communicated with the first chamber. The drainage pipe is communicated with the inside of the pressure-bearing container for guiding the safety injection water to be injected into the first chamber in a clockwise or counterclockwise direction;

[0013] The suction pipe is arranged above the first cyclone and communicated with the first chamber. The rotating blades are used to guide the safety injection water to be injected into the first chamber in a counterclockwise or clockwise direction, and the height of the suction pipe is higher than that of the drainage pipe.

[0014] Optionally, the damping device further includes a second cyclone, which is disposed above the safety injection outlet pipe; the second cyclone is provided with a second chamber communicating with the safety injection outlet pipe, and a water inlet channel that communicates the pressure-bearing container and the second chamber and is bent in the height direction; a water seal capable of preventing nitrogen from entering the second chamber from the water inlet channel can be formed in the water inlet channel; the first cyclone is disposed above the second cyclone, and the first chamber communicates with the second chamber.

[0015] Optionally, a spiral channel that rotates in a clockwise or counterclockwise direction is further provided in the second cyclone, the spiral channel communicates the second chamber and the water inlet channel, and the spiral channel is used to guide the safety injection water to be injected into the second chamber in a clockwise or counterclockwise direction.

[0016] Optionally, the second cyclone includes an upper housing and a lower housing, the upper housing and the lower housing are spaced apart, the second chamber is formed between the upper housing and the lower housing, and the water inlet channel is disposed around the periphery of the second chamber; the lower housing is connected to the safety injection outlet pipe.

[0017] Optionally, the upper housing includes a first circular flat plate, an upper outer ring side wall, and an upper inner ring side wall that are connected in sequence, the upper inner ring side wall and the upper outer ring side wall are disposed at an angle, and the upper inner ring side wall is located inside the upper outer ring side wall;

[0018] The lower housing includes a lower inner ring side wall, a circular flat plate, and a lower outer ring side wall that are connected in sequence, and the lower inner ring side wall and the lower outer ring side wall are spaced apart;

[0019] The upper outer ring side wall is spaced apart from the inner wall of the pressure-bearing container, the first circular flat plate and the circular flat plate are spaced apart, the lower inner ring side wall is connected to the safety 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-bearing container and enters the second chamber;

[0020] When the water level of the safety injection water is lower than the top height 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.

[0021] Optionally, the second cyclone further includes an arc plate, which is spirally fixed between the first circular flat plate and the circular flat plate to form the spiral channel that rotates in a counterclockwise or clockwise direction.

[0022] Optionally, the safety injection system further includes a support block and a diversion vane. The upper housing is connected and supported to the inner wall of the pressure-bearing container through the support block or the diversion vane; the diversion vane is arranged in a clockwise or counterclockwise spiral.

[0023] An embodiment of the present invention also provides a safety injection method, which is implemented by using the safety injection system. The safety injection method includes:

[0024] When a reactor loss-of-coolant accident occurs, the safety injection water in the pressure-bearing container flows through the damping device and then is injected into the reactor main system from the safety injection outlet pipe.

[0025] The beneficial effects of the safety injection system and method of the embodiments of the present invention include, for example:

[0026] A safety injection system includes a pressure-bearing container and a damping device. The pressure-bearing container is used to contain nitrogen and safety injection water, and 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, and the damping device is provided with a water inlet and a water outlet. The water inlet is communicated with the inside of the pressure-bearing container, and the water outlet is connected to the safety injection outlet pipe; the safety injection water in the pressure-bearing container flows through the damping device from the water inlet and then flows from the water outlet to the safety injection outlet pipe.

[0027] The pressure-bearing container provided with the damping device realizes automatic adjustment of the safety injection flow rate. The safety injection flow rate of the pressure-bearing container gradually decreases with the progress of the loss-of-coolant accident. Compared with the pressure-bearing container without the damping device, the flow rate in the initial stage of the accident is lower, avoiding the loss of safety injection water; the flow rate in the accident re-filling water and re-flooding stages can quickly realize the re-filling of the lower chamber and the re-flooding of the core; the injection flow rate is lower after the core is re-flooded, fully extending the safety injection time. It can effectively cope with the loss-of-coolant accident, and can also fully improve the safety of the reactor, ensure that radioactive substances do not leak, and ensure the safety for a longer time after the accident.

[0028] The safety injection method implemented by using the above safety injection system can improve the problem that the water injection flow rate of the safety injection system does not match the required flow rate in the stage of the reactor loss-of-coolant accident. Description of the Drawings

[0029] After reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings, the above features and advantages of the present invention can be better understood. In the drawings, the components are not necessarily drawn to scale, and components with similar related characteristics or features may have the same or similar reference numerals.

[0030] Figure 1 It is a schematic internal structure diagram of the safety injection system provided by the embodiment of the present invention;

[0031] Figure 2 It is a top view of the straw in the safety injection system provided by the embodiment of the present invention;

[0032] Figure 3 The top view of the first cyclone along the Figure 1 A - A cross - section in the safety injection system provided by the embodiment of the present invention;

[0033] Figure 4 The top view of the second cyclone along the Figure 1 B - B cross - section in the safety injection system provided by the embodiment of the present invention.

[0034] Icon: Pressure - bearing container - 10; Safety injection outlet pipe - 11; Suction pipe - 20; Rotating blade - 21; First cyclone - 30; Drainage pipe - 31; First chamber - 311; Cyclone outlet pipe - 32; Second cyclone - 40; First circular flat plate - 401; Upper outer ring side wall - 411; Outer ring housing - 41; Annular side wall - 48; Upper inner ring side wall - 42; Lower outer ring side wall - 43; Circular ring flat plate - 47; Lower inner ring side wall - 44; Support block - 12; Drainage plate - 45; Deflector - 46; Second chamber - 50; Spiral channel - 60; Water inlet channel - 70. Detailed implementation manners

[0035] The following describes the present invention in detail with reference to the accompanying drawings and specific embodiments. Note that the aspects described below in conjunction with the accompanying drawings and specific embodiments are merely exemplary and should not be construed as imposing any limitation on the protection scope of the present invention.

[0036] In the description of the present invention, it should be noted that if terms such as "upper", "lower", "inner", "outer", "vertical", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, 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. Therefore, it should not be construed as a limitation to the present invention.

[0037] Meanwhile, it should be noted that if terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0038] In the description of the present invention, it should also be noted that unless otherwise clearly specified or limited, the terms "installation", "connection", "coupling" 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 directly connected or indirectly connected through an intermediate medium, or the internal communication of two elements, etc. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] The following in conjunction with Figures 1 to 4A detailed description of the safety injection system provided in this embodiment will be given.

[0040] Please refer to Figure 1 , an embodiment of the present invention provides a safety injection system, including a pressure-bearing container 10 and a damping device. The pressure-bearing container 10 is used to contain nitrogen and safety injection water. An injection outlet pipe 11 is provided at the bottom of the pressure-bearing container 10; the damping device is arranged inside the pressure-bearing container 10, and the damping device is provided with a water inlet and a water outlet. The water inlet is communicated with the inside of the pressure-bearing container 10, and the water outlet is connected to the injection outlet pipe 11; the safety injection water in the pressure-bearing container 10 flows through the damping device from the water inlet and then flows from the water outlet to the injection outlet pipe 11.

[0041] Refer to Figure 1 , specifically, the inside of the pressure-bearing container 10 is hollow. The middle part of the pressure-bearing container 10 is a cylindrical barrel, and the top and bottom of the pressure-bearing container 10 are semi-ellipsoidal or hemispherical. The material of the pressure-bearing container 10 is stainless steel or carbon steel with a stainless steel surfacing layer, and it can withstand an internal pressure of more than 4 - 7 MPa. An opening is made at the bottom of the pressure-bearing container 10 and is connected to the injection outlet pipe 11. The inside of the pressure-bearing container 10 is filled with safety injection water containing boric acid in a certain proportion, and pressurized nitrogen is filled in the remaining upper space. The proportion of nitrogen in the internal space of the pressure-bearing container 10 is about 1 / 7 - 1 / 3, and the nitrogen pressure is about 3 - 6 MPa. When a loss-of-coolant accident occurs in the reactor, the safety injection water will flow out of the pressure-bearing container 10 through the damping device under the action of the internal nitrogen pressure and then be discharged from the injection outlet pipe 11 and enter the reactor main system.

[0042] A damping device is arranged inside the pressure-bearing container 10. When a loss-of-coolant accident occurs, the safety 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 safety injection water. Therefore, compared with the pressure-bearing container 10 without a damping device, in the initial stage of the injection, within only 10 seconds during the accident process, the flow rate discharged from the injection outlet pipe 11 will decrease, which can avoid the safety injection water being entrained out of the main system due to interaction with a large amount of high-temperature and high-pressure steam in the main system at the initial stage of the accident, and reduce the bypass loss of the safety injection water caused; in the middle stage of the loss-of-coolant accident, the water level of the safety injection water is still very high. Under the action of the nitrogen pressure and the water pressure of the safety injection water, the pressure-bearing container 10 can still discharge a large amount of safety injection water to quickly submerge the lower cavity of the reactor core and the exposed reactor core; in the later stage of the loss-of-coolant accident, the water level of the safety injection water in the pressure-bearing container 10 decreases, and the flow rate will decrease. Compared with the pressure-bearing container 10 without a damping device, after the damping device is set, the flow rate of the safety injection water will be lower and the discharge time will be extended, meeting the requirement of only a very small safety injection flow rate after the reactor core is re-submerged, extending the submergence time, and avoiding waste of the safety injection water.

[0043] Therefore, the pressure-bearing container 10 provided with the damping device realizes automatic adjustment of the safety injection flow rate. Compared with the pressure-bearing container 10 without the damping device, the flow rate is low in the initial stage, avoiding the loss of safety injection water; the flow rate can quickly realize the re-filling of the lower chamber and the re-flooding of the core in the middle stage; the flow rate is low in the later stage of injection, fully prolonging the safety injection time. It can effectively cope with the loss-of-coolant accident, and can also fully improve the safety of the reactor, ensure that radioactive substances do not leak, and ensure safety for a longer time after the accident.

[0044] Referring to Figure 1 and Figure 2 , in this embodiment, the damping device includes a suction pipe 20. The suction pipe 20 is arranged above the safety injection outlet pipe 11 and is communicated with the safety injection outlet pipe 11. Inside the suction pipe 20, there are rotating blades 21 distributed in a clockwise or counterclockwise direction. The rotating blades 21 are used to guide the safety injection water to be injected into the safety injection outlet pipe 11 in a counterclockwise or clockwise direction. At this time, the water inlet of the damping device is the top pipe orifice of the suction pipe 20, and the water outlet of the damping device is the bottom pipe orifice of the suction pipe 20.

[0045] Specifically, referring to Figure 2 , the suction pipe 20 is a circular pipe. The lower end is inserted vertically into the first cyclone 30 mentioned below, and the upper end is immersed below the water surface of the safety injection water inside the pressure-bearing container 10. Inside the suction pipe 20, there are rotating blades 21. The rotating blades 21 can be spiral blade type, or can be composed of two or more blades with a certain inclination angle. Whether it is spiral blade type or multiple blades spirally distributed, they can rotate clockwise or counterclockwise. When water flows into the suction pipe 20 from top to bottom, under the action of the rotating blades 21, the safety injection water will be transformed into a counterclockwise or clockwise downward circumferential flow.

[0046] When a loss-of-coolant accident occurs, the safety injection water enters from the suction pipe 20, flows through the rotating blades 21, and undergoes a counterclockwise or clockwise downward circumferential flow, and then flows out from the safety injection outlet pipe 11. Through the damping effect of the rotating blades 21, the drainage flow rate of the safety injection outlet pipe 11 can be reduced, thereby reducing the loss of safety injection water caused by the safety injection bypass phenomenon in the initial stage of the loss-of-coolant accident, and also being able to adapt to the problem that the required safety injection water flow rate is not much in the later stage of the loss-of-coolant accident.

[0047] Referring to Figure 1 and Figure 3, in this embodiment, the damping device further includes a first cyclone 30. The first cyclone 30 is provided with a first chamber 311 and a drain pipe 31 communicating with the first chamber 311. The drain pipe 31 communicates with the inside of the pressure-bearing container 10, and the drain pipe 31 is used to guide the accumulator injection water to be injected into the first chamber 311 in a clockwise or counterclockwise direction; the suction pipe 20 is arranged above the first cyclone 30, and the suction pipe 20 communicates with the first chamber 311. The rotating blade 21 is used to guide the accumulator 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 that of the drain pipe 31. At this time, the water inlet of the damping device is the top pipe orifice of the suction pipe 20, and the water outlet of the damping device is the cyclone outlet pipe 32 of the first cyclone 30.

[0048] Specifically, the lower part of the first cyclone 30 is an inverted cone, the upper part is a cylinder, the top of the first cyclone 30 is a horizontal circular flat plate, and the inside of the first cyclone 30 is hollow. As Figure 3 shown, in the upper part of the first cyclone 30, a drain pipe 31 is horizontally connected to the side wall tangent in a counterclockwise or clockwise direction, and the accumulator injection water in the pressure-bearing container 10 can be introduced into the first chamber 311 in a counterclockwise or clockwise direction by circumferential flow.

[0049] The bottom of the first cyclone 30 is further provided with a cyclone outlet pipe 32, and the accumulator 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 inserted vertically into the second cyclone 40 mentioned below.

[0050] Since the accumulator injection water entering the first chamber 311 from the suction pipe 20 flows counterclockwise under the action of the rotating blade 21 of the suction pipe, and the accumulator injection water entering the first chamber 311 from the drain pipe 31 of the first cyclone 30 also flows counterclockwise, and the inverted cone at the lower part of the first cyclone 30 enables the two water flows to still flow downward counterclockwise after convergence, which results in a greater damping effect when the two water flows are discharged from the cyclone outlet pipe 32. Therefore, compared with the pressure-bearing container without the suction pipe 20 and the first cyclone 30, at the initial stage of accumulator injection, the flow rate discharged from the cyclone outlet pipe 32 is lower, which can avoid the loss of accumulator injection water caused by the accumulator injection water being entrained out of the main system due to interaction with a large amount of high-temperature and high-pressure steam in the main system at the initial stage of the accident. In the later stage of the accident, the low flow rate can just meet the water demand in the reflooding stage, reduce the loss of accumulator injection water, and effectively utilize the accumulator injection water.

[0051] Referring to Figure 1 and Figure 3 , in this embodiment, the drain pipe 31 can be provided with only one, or can be provided with 2 or more than 2 that are centrosymmetric. When multiple drain pipes 31 are provided, each can ensure that the accumulator injection water in the pressure-bearing container 10 is introduced into the first cyclone 30 in a counterclockwise circumferential flow.

[0052] Reference Figure 1 and Figure 4 In this embodiment, the damping device further includes a second cyclone 40, which is arranged above the safety injection outlet pipe 11; the second cyclone 40 is provided with a second chamber 50 communicating with the safety injection outlet pipe 11, and a water inlet channel 70 that communicates the pressure-bearing container 10 and the second chamber 50 and is bent in the height direction; a water seal capable of preventing nitrogen from entering the second chamber 50 from the water inlet channel 70 can be formed in the water inlet channel 70; the first cyclone 30 is arranged above the second cyclone 40, and the first chamber 311 communicates with the second chamber 50. At this time, the water inlet of the damping device is the top pipe orifice of the suction pipe 20, and the water outlet of the damping device is the opening where the bottom end of the second cyclone 40 communicates with the safety injection outlet pipe 11.

[0053] Specifically, the suction pipe 20, the first cyclone 30, and the second cyclone 40 are arranged and installed in the pressure-bearing container 10 from top to bottom in sequence. For an existing safety injection tank, its container shell itself is the pressure-bearing container 10. If it is improved based on the present invention, only the bottom end of the second cyclone 40 needs to be connected to the outlet of the existing safety injection tank inside to complete the installation. The installation is simple and can realize the transformation and upgrade of the existing safety injection tank.

[0054] The safety injection process of the pressure-bearing container 10 installing the suction pipe 20, the first cyclone 30, and the second cyclone 40 is as follows:

[0055] Similarly, a certain proportion of safety injection water containing boric acid is pre-filled inside the pressure-bearing container 10, and pressurized nitrogen is filled in the remaining upper space, and the safety injection water surface is higher than the suction pipe 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 inside the pressure-bearing container 10, the safety injection water inside the pressure-bearing container 10 will be discharged outward under the drive of the nitrogen.

[0056] In the initial stage of the accident, when the water surface is higher than the top of the suction pipe 20, the safety 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 safety 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 safety injection water will be discharged to the reactor main system from the safety injection outlet pipe 11.

[0057] Since the safety injection water entering the first cyclone 30 from the suction pipe 20 rotates counterclockwise or clockwise, and the safety injection water entering the first cyclone 30 from the drainage pipe 31 rotates counterclockwise or clockwise, after the two water flows converge at the inverted cone at the lower part of the first cyclone 30, they still flow downward in the counterclockwise or clockwise direction, which results in a large damping effect when the two water flows are discharged from the cyclone outlet pipe 32.

[0058] The safety injection water entering the second cyclone 40 from the water inlet channel 70 will successively pass through the water inlet channel 70 that is bent up and down, that is, the flow velocity will be affected by the damping effect. "Bent up and down" refers to a channel that is bent up and down or bent up and down in the height direction, and is bent twice or more times, and has undergone multiple damping effects, and finally flows into the second chamber 50 of the second cyclone 40.

[0059] Therefore, in the initial stage of safety injection (within only 10 seconds during the accident), the flow rate discharged from the cyclone outlet pipe 32 and the flow rate discharged from the second cyclone 40 are relatively 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 interaction with a large amount of high-temperature and high-pressure steam in the main system during the initial stage of the accident, and can reduce the amount of safety injection bypass water.

[0060] In the middle stage of the accident, as the main system cools down and depressurizes, the steam in the main system cannot entrain the safety injection water out of the main system, and at the same time, a large amount of safety injection water is required 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 rotating blade 21 will not play the role of making the safety injection water flow counterclockwise, reducing the damping effect when 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 be within 5% of the total water volume. According to different reactor designs, the length of the suction pipe 20 can be adjusted as appropriate to adjust this ratio. The pressure reduced by the expansion of nitrogen is relatively small, and a large driving force can still be ensured. Therefore, in this stage, the safety injection water discharged from the cyclone outlet pipe 32 and then discharged from the second cyclone 40 can have a relatively large flow rate, and the core reflooding can be quickly achieved.

[0061] In the later stage of the accident, the water level in the pressure vessel 10 has dropped below the drainage pipe 31, and the safety 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 be within 70% of the total water volume. According to different reactor designs, the length of the cyclone outlet pipe 32 can be adjusted as appropriate to adjust this ratio. Since the safety injection water needs to enter the second chamber 50 through the water inlet channel 70 that is bent up and down in the height direction and finally be discharged from the safety injection outlet pipe 11 to the reactor main system. This process has a long path, so there is a large resistance, which makes the flow rate discharged from the safety injection outlet pipe 11 to the reactor main system relatively low, fully extending the safety injection time.

[0062] Finally, when the water level of the pressure vessel 10 drops below the highest water level of the up and down bends in the water inlet channel 70, the safety injection water cannot continue to 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 to prevent nitrogen from entering the second chamber 50 through the water inlet channel 70. Figure 1The approximate position where the water seal is formed is schematically shown, Figure 1 This is only a schematic illustration and does not represent the exact position where the water seal is formed.

[0063] Therefore, for the safety injection system provided in this embodiment, the safety injection flow rate can be automatically adjusted in the early stage, middle stage, and late stage of the accident. The discharge amount of the safety injection water from the pressure-bearing container 10 gradually decreases as the accident progresses. The damping effect of the damping device gradually decreases as the accident progresses. Compared with the pressure-bearing container without a damping device, in the initial stage, there is a damping effect of the suction pipe 20, the first cyclone 30, and the second cyclone 40, and the flow rate is low, avoiding the loss of safety injection water; in the middle stage, the discharge amount of the safety injection water from the pressure-bearing container 10 itself is large, and at the same time, the damping of the suction pipe 20 is reduced, and the discharge amount of the safety injection water can quickly achieve core reflooding; in the late stage of injection, the discharge amount of the safety injection water from the pressure-bearing container 10 itself is small, and with the damping effect of the second cyclone 40, the flow rate is low, fully extending the safety injection time, effectively utilizing the safety injection water, and providing sufficient redundant time for the start-up of the low-pressure safety injection pump. In the final stage, a water seal can be formed in the water inlet channel 70. If it is emptied, the nitrogen gas stored under pressure injected into the main system may block the safety injection flow path and may also affect core heat transfer. Therefore, by preventing nitrogen gas from entering the main system through the water seal, the impact of nitrogen gas on the mitigation of the loss-of-coolant accident can be avoided.

[0064] 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 play a role in hindering the flow of the safety injection water. In this embodiment, mainly taking the counterclockwise direction as an example for illustration, for example Figure 2 in, the rotating blade 21 guides the safety injection water to rotate counterclockwise, Figure 3 in, the diversion pipe 31 guides the safety injection water to rotate counterclockwise, Figure 4 in, the arc-shaped plate guides the safety injection water to rotate counterclockwise; the rotating blade 21, the diversion pipe 31, and the arc-shaped plate can guide the safety injection water to rotate counterclockwise or clockwise, and the counterclockwise or clockwise directions of the three do not need to be consistent.

[0065] Referring to Figure 1 , in this embodiment, a spiral channel 60 that rotates in the clockwise or counterclockwise direction is further provided in the second cyclone 40. The spiral channel 60 communicates the second chamber 50 and the water inlet channel 70, and the spiral channel 60 is used to guide the safety injection water to be injected into the second chamber 50 in the clockwise or counterclockwise direction.

[0066] The water inlet channel 70 and the spiral channel 60 make the process of the accumulator injection water entering the second chamber 50 not only have a relatively long path, but also the accumulator 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 greater damping effect on the discharge of the accumulator injection water. This results in a relatively low flow rate discharged from the accumulator injection outlet pipe 11 to the reactor primary system, and fully extends the accumulator injection time.

[0067] The water seal formed in the water inlet channel 70 isolates the inside of the pressure vessel 10 and the second chamber 50. The accumulator 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 with a large density is thrown towards the wall of the cyclone, and the nitrogen with a small density migrates towards the center; the low-pressure area in the second chamber 50 causes 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. The accumulator injection water then flows downward through the accumulator injection outlet pipe 11 into the core, achieving gas-liquid separation by using the centrifugal force of the second cyclone 40 without additional energy consumption, preventing nitrogen from entering the primary system downward through the accumulator injection outlet pipe 11, which may block the pipeline or reduce the cooling efficiency.

[0068] Refer to Figure 1 In this embodiment, the second cyclone 40 includes an upper housing and a lower housing. The upper housing and the lower housing are spaced apart, and a second chamber 50 is formed between the upper housing and the lower housing, and a water inlet channel 70 is arranged around the second chamber 50; the lower housing is connected to the accumulator injection outlet pipe 11.

[0069] The second chamber 50 is located at the center of the second cyclone 40. The water inlet channel 70 is arranged around the second chamber 50 and enters the second chamber 50 after bending up and down multiple times. Specifically, after the accumulator injection water enters the water inlet channel 70, it flows upward, then downward, and then upward, and enters the second chamber 50 after flowing several times. The specific number of up and down cycles can be designed according to the relationship between the actual required flow rate and the damping effect. 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.

[0070] Refer to Figure 1, in this embodiment, the upper housing includes a first circular flat plate 401, an upper outer ring side wall 411, and an upper inner ring side wall 42 that 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 inside the upper outer ring side wall 411; the lower housing includes a lower inner ring side wall 44, a circular flat plate 47, and a lower outer ring side wall 43 that 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 an interval from the inner wall of the pressure vessel 10, the first circular flat plate 401 and the circular flat plate 47 are arranged at an interval, the lower inner ring side wall 44 is connected to the safety 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 at intervals in the diameter direction of the first circular flat plate 401, forming a water inlet channel 70 that bends up and down from the bottom of the pressure vessel 10 and enters the second chamber 50; when the water level of the safety injection water is lower than the top height 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.

[0071] Specifically, the upper outer ring side wall 411 includes a vertical annular side wall 48 and a downwardly curved outer ring housing 41 that are connected in sequence. The first circular flat plate 401 has a hole in the center of the circular flat plate and is connected to the outlet pipe 32 of the hydrocyclone. The circular flat plate 47 is kept horizontal with the first circular flat plate 401 at the top of the second hydrocyclone 40.

[0072] The annular side wall 48 is a vertical cylinder. The top end of the annular side wall 48 is connected to the outer edge of the first circular flat plate 401, the bottom end of the annular side wall 48 is connected to the top end of the outer ring housing 41, and there is a certain gap between the annular side wall 48 and the inner wall of the pressure vessel 10, serving as the inlet of the water inlet channel 70. The outer ring housing 41 is a thin shell that is centrosymmetric with a certain arc and has the same arc as the bottom of the pressure vessel 10.

[0073] The upper inner ring sidewall 42, the lower outer ring sidewall 43, and the lower inner ring sidewall 44 are all inverted conical in shape and have the same cone angle. Along the radial direction from the inside to the outside, the three are the lower inner ring sidewall 44, the upper inner ring sidewall 42, and the lower outer ring sidewall 43 respectively. The bottom end of the lower inner ring sidewall 44 is connected to the top of the safety injection outlet pipe 11, that is, the bottom of the pressure vessel 10; the top end of the lower inner ring sidewall 44 is connected to the central opening of the circular flat plate 47. The bottom end of the upper inner ring sidewall 42 is connected to the lower end of the outer ring housing 41, and there is a certain gap in the vertical direction between the top end of the upper inner ring sidewall 42 and the circular flat plate 47. The top end of the lower outer ring sidewall 43 is connected to the outer edge of the circular flat plate 47, and there is a certain gap in the vertical direction between the bottom end of the lower outer ring sidewall 43 and the outer ring housing 41. The upper inner ring sidewall 42 is inserted between the lower inner ring sidewall 44 and the lower outer ring sidewall 43, and the lower outer ring sidewall 43 is inserted between the upper inner ring sidewall 42 and the outer ring housing 41, forming a water inlet channel 70 that flows from the bottom of the pressure vessel 10 into the second chamber 50.

[0074] The height setting of the upper inner ring sidewall 42 determines the position where the water seal is formed. When the water level in the pressure vessel 10 is lower than the top surface of the upper inner ring sidewall 42, the safety injection water cannot enter the second chamber 50 through the water inlet channel 70, forming a water seal.

[0075] In the initial stage, the middle stage, and the late stage of the accident, the process of the safety injection water entering the second cyclone 40 from the water inlet channel 70 is as follows: The safety injection water entering the second cyclone 40 from the gap between the outer wall of the outer ring housing 41 of the second cyclone 40 and the inner wall of the pressure vessel 10 will successively pass through the gap flow channel between the lower inner ring sidewall 44 and the upper inner ring sidewall 42, the gap flow channel between the upper inner ring sidewall 42 and the lower outer ring sidewall 43, the gap flow channel between the lower outer ring sidewall 43 and the inner wall of the outer ring housing 41, and the gap flow channel between the drainage plate 45 and the annular sidewall 48, and then enter the second chamber 50.

[0076] Refer to 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 circular flat plate 47, forming a spiral channel 60 that rotates counterclockwise or clockwise. The spiral channel 60 communicates with the water inlet channel 70 and the second chamber 50.

[0077] An arc plate is arranged in the interlayer between the first circular flat plate 401 and the circular flat plate 47. The arc plate is a vertical arc plate, and its top end and bottom end are respectively connected to the first circular flat plate 401 and the circular flat plate 47. The safety injection water enters the gap flow channel between the arc plate and the guide plate 46, and then flows around in a counterclockwise direction and enters the lower inner ring sidewall 44, and finally is discharged to the reactor main system through the safety injection outlet pipe 11.

[0078] Refer to Figure 1 and Figure 2, in this embodiment, the number of arc-shaped plates is two, and the two arc-shaped plates are arranged symmetrically about the center of the first circular flat plate 401 to form a spiral channel 60.

[0079] Specifically, each arc-shaped plate includes a drainage plate 45 and a diversion plate 46; the radian and length of the drainage plate 45 and the diversion plate 46 are different. The drainage plate 45 and the diversion plate 46 are both vertically arranged arc-shaped plates and are connected between the first circular flat plate 401 and the annular flat plate 47.

[0080] Refer to Figure 4 , the number of drainage plates 45 is two and is arranged symmetrically about the center; the number of diversion plates 46 is two and is arranged symmetrically about the center; one end of the drainage plate 45 is connected to the annular side wall 48, and there is a certain gap between the drainage plate 45 and the annular side wall 48. The other end of the drainage plate 45 is connected to the diversion plate 46, and there is a certain gap between the diversion plate 46 and the drainage plate 45.

[0081] The drainage plate 45, the annular side wall 48, and the gaps between the drainage plate 45 and the diversion plate 46 form a sequentially spirally connected gap flow channel, which can deflect the safety injection water counterclockwise and introduce it into the lower inner annular side wall 44, and then discharge it from the safety injection outlet pipe 11 to the reactor main system. If clockwise deflection is to be achieved, it is also possible, as long as the arrangement directions of the drainage plate 45 and the diversion plate 46 are changed to achieve clockwise deflection.

[0082] Refer to Figure 1 , in this embodiment, the safety injection system further includes a support block 12 and a diversion vane. The upper shell is connected and supported to the inner wall of the pressure vessel 10 through the support block 12 or the diversion vane; the diversion vane is arranged in a clockwise or counterclockwise spiral.

[0083] In the gap between the outer ring shell 41 and the inner wall of the pressure vessel 10, 2 to 4 support blocks 12 are provided, or there can be multiple ones, for supporting the second cyclone 40. In other embodiments, the support block 12 can also be replaced by a diversion vane, which can not only play a supporting role but also play a role in counterclockwise or clockwise diversion, so that the safety injection water entering the water inlet channel 70 rotates clockwise or counterclockwise.

[0084] Refer to Figure 1 , in this embodiment, the central axes of the pressure vessel 10, the suction pipe 20, the first cyclone 30, the second cyclone 40, and the safety injection outlet pipe 11 all coincide.

[0085] Among them, the straw 20, the first cyclone 30, the drainage pipe 31, the cyclone outlet pipe 32, the second cyclone 40, the outer ring housing 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 flat plate 47, and the annular side wall 48 can all be made of stainless steel, or can be made of other corrosion-resistant metals or high-strength high-polymer materials.

[0086] An embodiment of the present invention also provides a safe injection method. It is implemented using a safe injection system. The safe injection method includes:

[0087] When a loss-of-coolant accident occurs in the reactor, the safety injection water in the pressure vessel flows through the damping device and is injected into the reactor main system from the safety injection outlet pipe.

[0088] Specifically, when the water level of the safety injection water is higher than the height of the straw 20, the safety injection water is respectively injected into the second chamber 50 from the straw 20, the drainage pipe 31, and the water inlet channel 70, and is discharged from the safety injection outlet pipe 11.

[0089] When the water level of the safety injection water is lower than the height of the straw 20 and higher than the height of the drainage pipe 31, the safety 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 safety injection outlet pipe 11.

[0090] When the water level of the safety injection water is lower than the height of the drainage pipe 31, the safety injection water is injected into the second chamber 50 from the water inlet channel 70 and discharged from the safety injection outlet pipe 11, and finally a water seal is formed in the water inlet channel 70 to prevent nitrogen from entering the second chamber 50 from the water inlet channel 70. Specifically, in the later stage of the accident, only water injection is carried out through the water inlet channel 70, the water flow rate decreases, and the water injection time is extended.

[0091] According to a safe injection system provided by this embodiment, the working principle of the safe injection system includes:

[0092] A design of a fully passive safety injection water tank applicable to a pressurized water reactor is proposed, which can make full and effective use of the boron-containing water stored in the water tank, can significantly extend the safety injection time, effectively cope with the loss-of-coolant accident, can fully improve the safety of the reactor, ensure that radioactive substances do not leak out, and ensure safety for a longer time after the accident.

[0093] A three-stage damping device is provided inside the pressure-bearing container 10, namely the suction pipe 20, the first cyclone 30 and the second cyclone 40. Compared with the original accumulator tank, at the initial stage of the accident, the suction pipe 20, the second cyclone 40 and the first cyclone 30 work simultaneously, and the discharge flow rate of the accumulator water decreases the most; at the middle stage of the accident, the suction pipe 20 does not work, and the first cyclone 30 and the second cyclone 40 work, and the decreasing range of the discharge flow rate of the accumulator water narrows; at the late stage of the accident, the suction pipe 20 and the first cyclone 30 do not work, and the second cyclone 40 works, and the discharge flow rate of the accumulator water decreases the least. Matching the trend that the water injection volume of the pressure-bearing container itself gradually decreases with the progress of the accident can just meet the water volume required to maintain core flooding in the late stage of the accident without waste.

[0094] The safety injection system provided by this embodiment has at least the following advantages:

[0095] By providing a damping device inside the pressure-bearing container, automatic adjustment of the accumulator injection flow rate is achieved. The flow rate is low in the initial stage to avoid loss of accumulator water; the flow rate is high in the middle stage to quickly achieve re-filling of the lower chamber and core re-flooding; the flow rate is low in the late stage of injection to fully extend the accumulator injection time, effectively utilize the accumulator water, and provide sufficient redundant time for the start-up of the low-pressure accumulator pump. The use of passive technology, without moving parts, greatly reduces the possibility of failure and is easy to maintain.

[0096] In the late stage of the accident, a water seal can be formed inside the water inlet channel 70, avoiding the injection of the pressurized nitrogen into the main system during emptying, and thus avoiding the influence of nitrogen on the mitigation of the loss-of-coolant accident.

[0097] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art 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 comprises a suction pipe, which is arranged above the anzhu outlet pipe and communicated with the anzhu outlet pipe, and the interior of the suction pipe is provided with rotating vanes that rotate in a clockwise or counterclockwise direction, and the rotating vanes are used to guide the anzhu water to be injected into the anzhu outlet pipe in a counterclockwise or clockwise direction; 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, wherein 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 provided above the first cyclone, and the suction pipe is communicated with the first chamber, and the rotary vane is used to guide the injection water to be injected into the first chamber in a counterclockwise or clockwise direction, and the height of the suction pipe is higher than the height of the drainage pipe; 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.

2. The safe injection system according to claim 1, 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.

3. The safe injection system according to claim 2, 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.

4. The safe injection system according to claim 3, 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.

5. The safe injection system according to claim 4, 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.

6. The safe injection system according to any one of claims 3 to 5, 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.

7. A safe injection method, implemented by using the safe injection system according to any one of claims 1 to 6, 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