Backwater pipeline, pool type reactor and operation method of pool type reactor

Abstract

The invention provides a water return pipeline, a pool type reactor and an operation method thereof. The water return pipeline comprises a body, one end of the body is used for extending into a pool, the other end of the body extends out of the pool and is connected with one end of a discharge pipeline, and the other end of the discharge pipeline extends to a reactor core in the pool; the section, extending into the pool, of the body is provided with a reducing section which is connected with an exhaust pipeline, one end of the exhaust pipeline is connected with the reducing section, the other end of the exhaust pipeline extends upwards to the first position of the body, and the first position is higher than the reducing section. The water return pipeline comprises a first flow path and a second flow path, and the first flow path is configured in the mode that when siphoning occurs, water flow enters the body from one end of the body and flows to the other end of the body in the extending direction of the body, and liquid phase flow is provided; and the second flow path is configured as follows: when siphoning occurs, gas is separated out when water flow passes through the reducing section, and the gas enters the exhaust pipeline and upwards flows to the other end of the exhaust pipeline in the extension direction of the exhaust pipeline, so that two-phase flow for breaking siphoning is formed in the first flow path.

Description

Technical Field

[0001] The present invention relates to the technical field of safety design of pool-type reactors, and particularly relates to a return water pipe, a pool-type reactor and an operation method thereof. Background Art

[0002] Research reactors are usually pool-type reactors with light water moderation and cooling, and beryllium and heavy water as reflectors. The coolant circulation pipe usually extends from the top of the pool to the bottom of the pool. The circulation water pump is arranged at the low point, and the hot water in the pool is circulated to the coolant heat exchanger, and after cooling, it is injected into the pool through the top return water pipe to achieve circulation.

[0003] Since the return water pipe is inserted into the pool through the top of the pool, when a break occurs in the lower part of the return water pipe outside the pool, due to the siphon effect, the water in the pool will continuously flow out through the break, reducing the water inventory in the pool for cooling the reactor core, and further causing the reactor core at the bottom to be exposed, threatening the safety of the reactor.

[0004] Based on this, the inventors of the present application propose a return water pipe, a pool-type reactor and an operation method thereof, in order to solve the above technical problems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defect that the siphon effect caused by the break in the prior art leads to potential safety hazards in the reactor core, and to provide a return water pipe, a pool-type reactor and an operation method thereof.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] The present invention provides a return water pipe, including:

[0008] A main body, one end is used to extend into the pool, and the other end is used to extend outside the pool and connect to one end of the discharge pipe, and the other end of the discharge pipe extends into the reactor core in the pool;

[0009] A section of the main body for extending into the pool has a reduced-diameter section, and an exhaust pipe is connected to the reduced-diameter section. One end of the exhaust pipe is connected to the reduced-diameter section, and the other end extends upward to a first position of the main body, and the first position is higher than the reduced-diameter section; wherein,

[0010] The return water pipe includes a first flow path and a second flow path. The first flow path is configured such that when siphonage occurs, water flows into the main body from one end of the main body and flows along the extension direction of the main body to the other end of the main body, providing a liquid-phase flow. The second flow path is configured such that when siphonage occurs, gas is separated out when the water flows through the reduced-diameter section. The gas enters the exhaust pipe and flows upward along the extension direction of the exhaust pipe to the other end of the exhaust pipe and merges into the first flow path to form a two-phase flow that breaks the siphonage in the first flow path.

[0011] According to an embodiment of the present invention, the main body includes a first connecting pipe section, a second connecting pipe section, and a third connecting pipe section arranged in sequence. The first connecting pipe section is located outside the water tank and one end thereof is connected to the discharge pipe. The second connecting pipe section is higher than the first connecting pipe section and the third connecting pipe section. One end of the third connecting pipe section extends into the water tank.

[0012] The reduced-diameter section is provided on the third connecting pipe section. One end of the exhaust pipe is connected to the reduced-diameter section, and the other end is connected to the second connecting pipe section.

[0013] When a break occurs in the first connecting pipe section to generate a siphon effect, the exhaust pipe transports the gas separated out by the reduced-diameter section to the second connecting pipe section.

[0014] According to an embodiment of the present invention, the diameter of the exhaust pipe is smaller than the diameters of the first connecting pipe section and the second connecting pipe section.

[0015] According to an embodiment of the present invention, an air-introducing pipe is further connected to the reduced-diameter section. One end of the air-introducing pipe is communicated with the reduced-diameter section, and the other end extends upward and has an air inlet. The height of the air inlet from the bottom surface of the water tank is lower than the normal liquid level of the water tank.

[0016] According to an embodiment of the present invention, the air inlet is arranged downward.

[0017] According to an embodiment of the present invention, the cross-sectional dimensions of the two opposite ends of the reduced-diameter section decrease in the direction towards the middle, and a minimum cross-section position is formed at the middle position.

[0018] Both the exhaust pipe and the air-introducing pipe are communicated with the minimum cross-section position of the reduced-diameter section.

[0019] According to an embodiment of the present invention, the diameter of the air-introducing pipe is the same as that of the exhaust pipe, and both are smaller than the diameter of the reduced-diameter section at the minimum cross-section position.

[0020] According to an embodiment of the present invention, the number of the air inlets is at least two. At least two air inlets are arranged side by side and the height from the bottom surface of the water tank increases or decreases.

[0021] The present invention also provides a pool-type reactor, characterized in that it includes:

[0022] A water pool with a reactor core at the bottom;

[0023] A discharge pipe, one end of which extends into the water pool and is connected to the reactor core;

[0024] The return water pipe as described above, one end of the return water pipe extends into the water pool, and the other end is connected to the discharge pipe.

[0025] The present invention also provides an operation method for a pool-type reactor, using the pool-type reactor as described above. The operation method includes:

[0026] When the pool-type reactor is in a normal operation state, the circulating water pump pumps out the high-temperature liquid output by the pool-type reactor, and the pumped high-temperature liquid flows through the heat exchanger and then flows into the water pool through the return water pipe;

[0027] When the pool-type reactor is in an accident state, the circulating pump stops running, the return water pipe breaks and forms a siphon, and the exhaust pipe in the return water pipe conveys the gas precipitated at the reduced-diameter section upward to the inside of the main body to form a two-phase flow that destroys the siphon in the main body.

[0028] The positive and progressive effects of the present invention are as follows:

[0029] For the return water pipe of the present invention, a reduced-diameter section is provided on the main body. When a break occurs in the main body outside the water pool and siphon water loss occurs, the water in the water pool gradually accelerates when passing through the reduced-diameter section of the main body, resulting in a decrease in static pressure, and the non-condensable gas contained in the water continuously precipitates. Then, the exhaust pipe provided on the reduced-diameter section can lead the precipitated gas upward and refill it into the main body. Then, the precipitated gas mixes with the water in the main body to form a two-phase flow of gas-water entrainment, thereby destroying the siphon effect, preventing the water in the water pool from being continuously discharged and exposing the reactor core at the bottom, and improving the operation safety of the reactor. Description of the Drawings

[0030] The above-mentioned and other features, properties and advantages of the present invention will become more obvious through the following description in conjunction with the drawings and embodiments, wherein:

[0031] Figure 1 is a schematic structural diagram of the pool-type reactor of the present invention;

[0032] Figure 2 is a pipeline layout diagram of an existing reactor;

[0033] Figure 3 is a schematic diagram of the medium flow inside the main body when the liquid level in the water pool is lower than the air inlet;

[0034] 1. Body; 11. Reduced-diameter section; 12. First connecting pipe section; 13. Second connecting pipe section; 14. Third connecting pipe section; 15. Air extraction pipeline; 151. Air inlet; 16. First position; 17. First flow path; 18. Second flow path;

[0035] 2. Water pool;

[0036] 3. Discharge pipeline;

[0037] 4. Reactor core;

[0038] 5. Exhaust pipeline;

[0039] 6. Circulation water pump;

[0040] 7. Heat exchanger. Detailed implementation manners

[0041] The present invention will be further described below in conjunction with specific embodiments and the accompanying drawings. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention is clearly capable of being implemented in many other ways different from this description. Those skilled in the art can make similar generalizations and deductions according to the actual application situation without departing from the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above accompanying drawings are intended to cover non-exclusive inclusion.

[0043] Please refer to Figures 1 to 3 , the present invention provides a return water pipeline, including a body 1. One end of the body 1 is used to extend into the water pool 2, and the other end is used to extend outside the water pool 2 and connect to one end of the discharge pipeline 3. The other end of the discharge pipeline 3 extends to the reactor core 4 in the water pool 2.

[0044] Referring to Figure 2 , it can be seen that the return water pipeline and the discharge pipeline 3 together form a circulation pipeline. A circulation water pump 6 and a cooling water heat exchanger 7 are also provided on the circulation pipeline. One end of the discharge pipeline 3 is communicated with the outlet end of the reactor core 4. Driven by the circulation water pump 6, the discharge pipeline 3 draws out the hot water on the reactor core 4 side and transports it to the heat exchanger 7. The heat exchanger 7 takes away the heat after heat exchange, and then the cooled water is discharged back into the water pool 2 through the return water pipeline, and circulates in this way to complete the cooling of the reactor core 4. When there is a siphon in the body 1 in an accident state, in the existing solution, the water in the pool will flow out of the pool continuously under the action of the siphon, and then there is a risk of the reactor core 4 being exposed.

[0045] Based on this, a reduced-diameter section 11 is provided on a section of the main body 1 extending into the water pool 2. An exhaust pipe 5 is connected to the reduced-diameter section 11. One end of the exhaust pipe 5 is connected to the reduced-diameter section 11, and the other end extends upward to the first position 16P1 of the main body 1, and the first position 16P1 is higher than the reduced-diameter section 11.

[0046] It should be noted that the return water pipe includes a first flow path 17 and a second flow path 18. The first flow path 17 is configured such that when siphon occurs, water flows into the main body 1 from one end of the main body 1 and flows along the extension direction of the main body 1 to the other end of the main body 1, providing a liquid-phase flow. The second flow path 18 is configured such that when siphon occurs, gas is separated out when the water flows through the reduced-diameter section 11. The gas enters the exhaust pipe 5 and flows upward along the extension direction of the exhaust pipe 5 to the other end of the exhaust pipe 5, and merges into the first flow path 17 to form a two-phase flow that breaks the siphon in the first flow path 17.

[0047] Refer to Figure 1 , under the normal operating state of the reactor, the liquid level in the water pool 2 is at the A height position. The water cooled by the heat exchanger 7 is discharged into the reactor core 4 through the return water pipe. The water flow direction refers to the arrow flow direction of the dotted line in Figure 1 , that is, the direction corresponding to from outside the pool to inside the pool.

[0048] In the accident condition, when there is a break in the return water pipe (the break position is lower than the liquid level in the water pool 2), due to the siphon effect, the water in the water pool 2 will continuously flow out through the break, reducing the water inventory in the water pool 2 for cooling the reactor core 4. Among them, the water flow direction refers to the solid arrow flow direction in the main body 1 in Figure 1 , that is, the direction corresponding to from inside the pool to outside the pool.

[0049] Based on this, in order to prevent the water in the water pool 2 from continuously flowing out and exposing the reactor core 4, a reduced-diameter section 11 is provided on a section of the main body 1 extending into the water pool 2. When the water in the water pool 2 passes through the reduced-diameter section 11, the flow rate of the water increases, the static pressure decreases, and the non-condensable gas contained in the water is continuously separated out. The separated gas is introduced upward into the main body 1 through the exhaust pipe 5, forming a two-phase flow of gas-water entrainment that breaks the siphon effect in the main body 1, breaking the flow negative pressure, cutting off the water flow, realizing siphon breakage, preventing further water loss in the water pool 2, and improving the operating safety of the reactor core 4.

[0050] Please refer to Figure 1 , the main body 1 specifically includes a first connecting pipe section 12, a second connecting pipe section 13, and a third connecting pipe section 14 that are connected in sequence. The first connecting pipe section 12 is located outside the water pool 2 and one end is connected to the discharge pipe 3. The second connecting pipe section 13 is higher than the first connecting pipe section 12 and the third connecting pipe section 14. One end of the third connecting pipe section 14 extends into the water pool 2.

[0051] The reduced-diameter section 11 is provided in the third connecting pipe section 14. One end of the exhaust pipe 5 is connected to the reduced-diameter section 11, and the other end is connected to the second connecting pipe section 13. When a break occurs in the first connecting pipe section 12 to generate a siphon effect, the exhaust pipe 5 transports the gas separated from the reduced-diameter section 11 to the second connecting pipe section 13.

[0052] As Figure 1 shown, the first connecting pipe section 12, the second connecting pipe section 13, and the third connecting pipe section 14 are arranged in a U shape. When an accident break occurs, the water in the pool 2 is discharged successively through the third connecting pipe section 14, the second connecting pipe section 13, and the first connecting pipe section 12. When the water passes through the reduced-diameter section 11 of the third connecting pipe section 14, the flow rate increases, the static pressure decreases, and the non-condensable gas contained in the water is separated out. The gas is led upward through the exhaust pipe 5 to the second connecting pipe section 13. Thus, a two-phase flow with gas entrainment is formed in the second connecting pipe section 13, realizing siphon breakage.

[0053] In some other embodiments, the exhaust pipe 5 can also be led to a position above the reduced-diameter section 11 of the third connecting pipe section 14, which can also meet the requirements of siphon breakage. That is, the first position 16 only needs to be higher than the reduced-diameter section 11, and the specific position is not limited.

[0054] Please continue to refer to Figure 1 , the diameter of the exhaust pipe 5 is smaller than the diameters of the first connecting pipe section 12 and the second connecting pipe section 13.

[0055] As can be seen, when the return water pipe is operating normally, the cooling water is led to the pool 2 through the return water pipe. When the water flows through the second connecting pipe section 13, part of the water will flow through the exhaust pipe 5 to the reduced-diameter section 11, and then converge at the reduced-diameter section 11 and flow to the pool 2 together.

[0056] Because the second connecting pipe section 13 is at the top of the pool 2 and the diameter of the exhaust pipe 5 is small, the downward drainage of the exhaust pipe 5 accounts for a relatively low proportion of the total drainage of the main body 1 and will not hinder the total drainage. Moreover, the exhaust pipe 5 with a small size will not occupy too much space in the pool 2, which is beneficial to the layout of other components in the pool 2.

[0057] When an accident occurs and a break appears in the first connecting pipe section 12, most of the water in the pool 2 will be discharged outward through the third connecting pipe section 14, and gas will be separated out when the flow rate increases at the reduced-diameter section 11. The separated gas and part of the water flow upward to the second connecting pipe section 13 together and are mixed with the water in the second connecting pipe section 13 to form a two-phase flow with gas and water entrainment, destroying the siphon effect.

[0058] Preferably, the diameter of the exhaust pipe 5 is at least not higher than one-tenth of the diameters of the first connecting pipe section 12 and the second connecting pipe section 13. This can not only meet the requirements of siphon breakage but also not occupy too much space in the pool.

[0059] Please continue to refer to Figure 1 , an air intake pipe 15 is also connected to the reduced-diameter section 11. One end of the air intake pipe 15 is communicated with the reduced-diameter section 11, and the other end extends upward and has an air inlet 151. The height of the air inlet 151 from the bottom surface of the water pool 2 is lower than the normal liquid level of the water pool 2.

[0060] The normal liquid level is the liquid level in the water pool 2 corresponding to the normal operation of the reactor. This liquid level can be a dynamic value, and the specific value is not limited.

[0061] Under accident conditions, when a break occurs in the first connecting pipe section 12, the water in the water pool 2 will continuously drain out under the action of siphon. When the liquid level in the water pool 2 drops below the height of the air inlet 151 (refer to the B height in Figure 3 ), the negative pressure at the reduced-diameter section 11 will suck in the gas above the liquid level of the water pool 2. Part of the sucked gas is mixed with the water in the third connecting pipe section 14 to form a two-phase flow of gas-liquid entrainment, and is transported to the second connecting pipe section 13. The other part will be transported upward through the air intake pipe 15 to the second connecting pipe section 13, increasing the gas content in the two-phase flow in the second connecting pipe section 13, thereby destroying the flow negative pressure, cutting off the water flow, realizing siphon breakage, avoiding further water loss, and improving the operation safety of the reactor core 4.

[0062] Refer to Figure 1 and Figure 3 , the third connecting pipe section 14 is bent at the air inlet 151 so that the air inlet 151 is arranged downward.

[0063] During the normal operation of the return water pipe, part of the water will flow from the reduced-diameter section 11 to the air intake pipe 15 and be discharged into the pool from the air inlet 151. To avoid the discharged water from splashing upward, the third connecting pipe section 14 is bent at the air inlet 151 so that the air inlet 151 is arranged downward, improving the safety of introducing water into the pool from the air intake pipe 15 during the normal operation of the return water pipe.

[0064] In one embodiment, the cross-sectional dimensions of the two opposite ends of the reduced-diameter section 11 decrease in the direction towards the middle, and a minimum cross-section position is formed at the middle position; both the exhaust pipe 5 and the air intake pipe 15 are communicated with the minimum cross-section position of the reduced-diameter section 11.

[0065] Since the static pressure at the minimum cross-section position of the reduced-diameter section 11 is the lowest, in order to increase the air precipitation amount, the exhaust pipe 5 and the air intake pipe 15 are respectively connected to the minimum cross-section position.

[0066] Preferably, the diameter of the air intake pipe 15 is the same as that of the exhaust pipe 5, and both are smaller than the diameter of the reduced-diameter section 11 at the minimum cross-section position.

[0067] The air intake pipe 15, the exhaust pipe 5 and the main body 1 can be integrally formed, or can be connected by other means such as welding and bonding, which is not limited herein.

[0068] The diameters of the air intake pipe 15 and the exhaust pipe 5 are both relatively small, so that they will not occupy too much space in the pool, and can satisfy the requirement of destroying the siphon effect at the break to avoid further water loss.

[0069] In one embodiment, the number of the air inlets 151 is at least two, and the at least two air inlets 151 are arranged side by side and the height from the bottom surface of the water pool 2 increases or decreases.

[0070] When siphon water loss occurs at the break, when the liquid level reaches different air inlets 151, the amount of gas sucked into the main body 1 is also different. In this way, it is beneficial to gradually improve the siphon breaking effect and slow down the water loss speed of the water pool 2.

[0071] The number of the air inlets 151 can be adjusted according to actual needs, which is not limited herein.

[0072] In the present invention, a reduced-diameter section 11 is provided at one end of the main body 1 extending into the water pool 2. When a break occurs outside the main body 1 of the water pool 2 and siphon water loss occurs, the water in the water pool 2 gradually accelerates through the reduced-diameter section 11, the static pressure decreases, and the non-condensable gas contained in the water continuously precipitates. The precipitated water is led to the second connecting pipe section 13 by the exhaust pipe 5 provided at the reduced-diameter section 11, enhancing the siphon breaking ability.

[0073] Meanwhile, an air intake pipe 15 is also provided at the position of the minimum cross-section of the reduced-diameter section 11. The air intake pipe 15 extends upward. After siphon water loss occurs at the break, the liquid level in the water pool 2 gradually decreases. When the liquid level drops below the air inlet 151 of the air intake pipe 15, due to the lower static pressure at the minimum cross-section of the reduced-diameter section 11, air is gradually sucked into the reduced-diameter section 11 and enters the inside of the main body 1 to be mixed with the water inside to form a two-phase flow of gas-water entrainment, destroying the flow negative pressure, cutting off the water flow, realizing siphon breaking, avoiding further water loss, and improving the operation safety of the reactor.

[0074] The present invention also provides a pool-type reactor, which includes a water pool 2, a discharge pipe 3 and the above-mentioned return water pipe. One end of the return water pipe extends into the water pool 2, and the other end is connected to the discharge pipe 3.

[0075] Since the pool-type reactor includes the above-mentioned return water pipe, it has all the beneficial effects of the return water pipe, which will not be elaborated herein.

[0076] The present invention also provides an operation method of a pool-type reactor. Using the above pool-type reactor, the operation method includes:

[0077] When the pool-type reactor is in a normal operating state, the circulating water pump pumps out the high-temperature liquid output by the pool-type reactor. The pumped high-temperature liquid flows through the heat exchanger and then flows back to the water pool through the return water pipeline;

[0078] When the pool-type reactor is in an accident state, the circulating pump stops operating, the return water pipeline breaks and forms a siphon, and the exhaust pipeline in the return water pipeline conveys the gas separated at the reduced-diameter section upward to the inside of the body to form a two-phase flow that destroys the siphon inside the body.

[0079] Using the above operation method, the present invention satisfies the siphon-breaking function under normal operation and accident conditions of the pool-type reactor, which is beneficial to improving the safety of reactor operation.

[0080] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific situations.

[0081] The present application uses specific terms to describe the embodiments of the present application. Such as "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification is not necessarily the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the present application can be combined appropriately.

[0082] Although the present invention is disclosed above in preferred embodiments, it is not used to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention all fall within the protection scope defined by the claims of the present invention.

Claims

1. A water return pipe, characterized in that: include: A body, one end of which is used to extend into the water pool, and the other end of which is used to extend out of the water pool and connected to one end of a discharge pipe, and the other end of the discharge pipe extends to the core in the water pool; The body is used to extend into the pool and has a reduced diameter section, the reduced diameter section is connected to an exhaust pipe, one end of the exhaust pipe is connected to the reduced diameter section, and the other end extends upward to a first position of the body, the first position is higher than the reduced diameter section; wherein, The return water pipe includes a first flow path and a second flow path. The first flow path is configured such that: when siphoning occurs, water flows into the body from one end of the body and flows along the extension direction of the body to the other end of the body to provide a liquid phase flow; the second flow path is configured such that: when siphoning occurs, gas is precipitated when the water flows through the reduced diameter section, and the gas enters the exhaust pipe and flows upward along the extension direction of the exhaust pipe to the other end of the exhaust pipe and merges into the first flow path to form a two-phase flow that destroys the siphoning in the first flow path.

2. The water return pipe according to claim 1, characterized in that: The body comprises a first connecting pipe section, a second connecting pipe section and a third connecting pipe section which are arranged in sequence, wherein the first connecting pipe section is located outside the pool and one end of the first connecting pipe section is connected to the discharge pipe, the second connecting pipe section is higher than the first connecting pipe section and the third connecting pipe section, and one end of the third connecting pipe section extends into the pool; The reduced diameter section is provided on the third connecting pipe section, one end of the exhaust pipe is connected to the reduced diameter section, and the other end is connected to the second connecting pipe section; When a siphon effect occurs when a breach occurs in the first connecting pipe section, the exhaust pipe transports the gas released from the reduced diameter section to the second connecting pipe section.

3. The water return pipe according to claim 2, characterized in that: The diameter of the exhaust pipe is smaller than the diameters of the first connecting pipe section and the second connecting pipe section.

4. The water return pipe according to claim 2, characterized in that: The reduced diameter section is also connected to an air duct, one end of which is connected to the reduced diameter section, and the other end of which extends upward and has an air inlet, and the height of the air inlet from the bottom of the pool is lower than the normal liquid level of the pool.

5. The water return pipe according to claim 4, characterized in that: The air inlet is arranged downward.

6. The water return pipe according to claim 4, characterized in that: The cross-sectional dimensions of the reduced diameter section decrease gradually from the opposite ends to the middle, and a minimum cross-sectional position is formed in the middle; The exhaust duct and the bleed air duct are both in communication with the minimum cross-section position of the reduced diameter section.

7. The water return pipe according to claim 6, characterized in that: The diameter of the bleed air duct is consistent with that of the exhaust duct, and both are smaller than the diameter of the reduced diameter section at the minimum cross-section position.

8. The water return pipe according to claim 4, characterized in that: The number of the air inlets is at least two, and at least two of the air inlets are arranged side by side and their heights from the bottom surface of the pool increase or decrease gradually.

9. A pool-type reactor, characterized in that: include: A water pool with a core at the bottom; a discharge pipe, one end of which extends into the water pool and is connected to the core; The return pipe according to any one of claims 1 to 8, wherein one end of the return pipe extends into the pool and the other end is connected to the discharge pipe.

10. A method for operating a pool reactor, characterized in that: Using the pool-type reactor as claimed in claim 9, the operating method comprises: When the pool-type reactor is in normal operation, the circulating water pump extracts the high-temperature liquid output by the pool-type reactor, and the extracted high-temperature liquid flows through the heat exchanger and then flows into the water pool through the return water pipe; When the pool-type reactor is in an accident state, the circulation pump stops running, the return pipe breaks and forms a siphon, and the exhaust pipe in the return pipe transports the gas separated at the reduced diameter section upward into the body to form a two-phase flow in the body that destroys the siphon.

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