Pool type reactor passive heat removal device and arrangement method thereof

Abstract

This invention discloses a passive heat removal device for a pool-type reactor and its arrangement method. The device includes an upper heat exchange system and a lower heat exchange system, each system comprising a hot-end heat exchanger and a cold-end heat exchanger, with a pipe connecting the two heat exchangers to form an internal circulation of the working medium. The hot-end heat exchanger is arranged inside the reactor water pool, and the cold-end heat exchanger is arranged outside the reactor water pool. Considering the deep-well structure with a large length-to-diameter ratio of the reactor water pool, the temperature differences at different pool depths, and the complex and compact arrangement of internal reactor components, the hot-end heat exchangers are arranged in layers utilizing the longitudinal space within the reactor water pool; the cold-end heat exchangers are arranged against the outer wall of the reactor hall building, and a chimney structure or cooling tower is constructed around them to enhance heat exchange. This invention utilizes heat pipe technology, and through the rational arrangement of the passive heat removal device, enables the device to quickly remove heat from the reactor water pool in an accident situation, preventing the pool water from boiling.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor cooling device safety design technology, specifically to a passive heat removal device for pool reactors and its arrangement method, which is mainly used for removing heat from the reactor water pool of low-temperature atmospheric pressure pool reactors. Background Technology

[0002] The ability to perform passive residual heat removal is one of the key features of modern advanced reactors. Passive residual heat removal systems are installed in advanced reactor types such as AP1000, VVER, PIUS, 600, SMART, and CAREM.

[0003] In pool reactor design, due to the open design of the reactor pool, it can only operate at low temperature and normal pressure. In the event of an accident, the heat generated by the reactor core in the reactor pool is still removed by the safety-level active system, which does not achieve the goal of passive residual heat removal in current advanced reactor types. If the heat generated by the reactor core in the reactor pool is removed by boiling of the pool water, it will lead to the problem of radioactive material being released into the environment, which will greatly reduce environmental friendliness and produce the "NIMBY effect".

[0004] Currently, most passive residual heat removal technologies used in reactor engineering are based on shell-and-cell reactors. Patent applications include Chinese invention patents with authorization announcement numbers CN105957567B and CN115240880B. While these patents achieve core residual heat removal, their application in the high-temperature, high-pressure environment within the containment vessel and the heat exchanger arrangement are unsuitable for the atmospheric pressure, low-temperature operating environment of pool-type reactors. Furthermore, compared to the large space within the containment vessel, the pool-type reactor's water tank has a deep-well structure and a complex internal component arrangement, resulting in limited space for passive heat removal devices.

[0005] Chinese invention patent CN111508624A discloses a cooling system. This patent describes placing a first heat exchanger in the pooled reactor water tank. Water inside the first heat exchanger absorbs heat from the pool water and evaporates into gas. This gas then moves to a second heat exchanger outside the pool, exchanging heat with the air in the induced draft device to remove residual heat from the reactor core. However, this patent does not provide a reasonable arrangement of heat exchangers for deep-well reactor water tanks, nor does it address interference between the heat exchangers and objects within the pool. Under accident conditions, it cannot adjust the activation time of the heat exchange system based on the pool water temperature changes caused by the core heat release during the accident process, thus failing to maximize the matching of pool water heat conduction requirements. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to provide a passive heat removal device and its arrangement method arranged in a longitudinal layer, taking into account the characteristics of deep well structure and complex arrangement of objects in the pool, as well as the temperature field distribution characteristics in the pool. This overcomes the interference problem caused by the same layer arrangement of objects in the existing cooling system, and makes full use of the higher temperature of the deep water layer to improve heat exchange efficiency or to put it into operation in advance.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A passive heat removal device for a pool reactor includes:

[0009] The lower heat exchange system has a first hot-end heat exchanger and a first cold-end heat exchanger that form an internal circulation of working medium between them. The first hot-end heat exchanger is arranged in the lower area of ​​the water tank, and the first cold-end heat exchanger is arranged outside the water tank. The lower heat exchange system is suitable for being put into operation and operating independently at the initial stage of an accident, so as to quickly remove the heat from the lower area of ​​the water tank.

[0010] The upper heat exchange system has a second hot-end heat exchanger and a second cold-end heat exchanger that form an internal circulation of the working medium between them. The second hot-end heat exchanger is arranged in the upper region of the water tank, and the second cold-end heat exchanger is arranged outside the water tank. The upper heat exchange system is adapted to start when the water temperature in the upper region of the water tank reaches a set temperature, and to operate in conjunction with the lower heat exchange system to quickly remove heat from the water tank.

[0011] The first hot-end heat exchanger and the second hot-end heat exchanger of the lower heat exchange system are distributed along the inner wall of the water tank in the space between each internal component and the water tank gate. The heat in the water tank is carried to the respective cold-end heat exchanger outside the tank through the hot-end heat exchangers at different positions in the lateral and longitudinal spaces.

[0012] To further optimize the technical solution, the lower region of the reactor water pool is the region close to the reactor core, and the upper region of the reactor water pool is the region far from the reactor core; the lower region of the reactor water pool is located below the upper region of the reactor water pool, and the hot-end heat exchanger of the lower heat exchange system is located below the hot-end heat exchanger of the upper heat exchange system.

[0013] The technical solution is further optimized. The lower heat exchange system includes at least one first hot-end heat exchanger, a first cooling tower, and at least one first cold-end heat exchanger. The working medium outlet of the first hot-end heat exchanger and the working medium inlet of the first cold-end heat exchanger are connected through a lower-level riser pipe, and the working medium outlet of the first cold-end heat exchanger and the working medium inlet of the first hot-end heat exchanger are connected through a lower-level downcomer pipe. A first isolation valve is provided on the lower-level riser pipe and the lower-level downcomer pipe respectively.

[0014] The upper heat exchange system includes at least one second hot-end heat exchanger, and also includes a second cooling tower and at least one second cold-end heat exchanger; the working medium outlet of the second hot-end heat exchanger and the working medium inlet of the second cold-end heat exchanger are connected through an upper zone riser pipe, and the working medium outlet of the second cold-end heat exchanger and the working medium inlet of the second hot-end heat exchanger are connected through an upper zone downcomer pipe, and a second isolation valve is respectively provided on the upper zone riser pipe and the upper zone downcomer pipe.

[0015] The technical solution is further optimized as follows: the lower heat exchange system has several first hot-end heat exchangers that are distributed along the surrounding wall of the water tank, and the first hot-end heat exchangers are connected in parallel or are independent of each other; the lower heat exchange system has several first cold-end heat exchangers that are arranged at an angle, and the first cold-end heat exchangers are connected in parallel or are independent of each other.

[0016] and / or

[0017] The upper heat exchange system has several second hot-end heat exchangers that are distributed along the surrounding wall of the water tank, and the second hot-end heat exchangers are connected in parallel or are independent of each other; the upper heat exchange system has several second cold-end heat exchangers that are arranged at an angle, and the second cold-end heat exchangers are connected in parallel or are independent of each other.

[0018] Further optimize the technical solution: the first cooling tower is a water-cooled tower or a chimney structure; the second cooling tower is a water-cooled tower or a chimney structure.

[0019] Further optimization of the technical solution also includes:

[0020] A vacuum unit is connected to the upper heat exchange system and / or the lower heat exchange system, and the vacuum unit is adapted to evacuate the upper heat exchange system and / or the lower heat exchange system to reduce the boiling point of the working medium.

[0021] and / or

[0022] A working medium replenishment unit is connected to the upper heat exchange system and / or the lower heat exchange system, and the working medium replenishment unit is adapted to replenish the working medium for the upper heat exchange system and / or the lower heat exchange system.

[0023] A method for arranging passive heat removal devices in a pool reactor, wherein the method is based on the structure and layout requirements of the pool reactor and the temperature field characteristics within the reactor pool, and sets the passive heat removal devices as a lower heat exchange system and an upper heat exchange system, making full use of the longitudinal space, reducing interference between the heat exchange system equipment and reactor components and pool gates at the same pool water depth, and increasing the heat removal efficiency of the heat exchange system by utilizing the temperature difference of the pool water at different pool water depths.

[0024] Further optimization of the technical solution includes the following steps:

[0025] The water storage tank is divided into a lower zone and an upper zone, distributed from bottom to top;

[0026] The first hot-end heat exchanger of the lower heat exchange system is arranged in the lower area of ​​the water storage tank, and the first cold-end heat exchanger of the lower heat exchange system is arranged outside the water storage tank.

[0027] The second hot-end heat exchanger of the upper heat exchange system is arranged in the upper area of ​​the water storage tank, and the second cold-end heat exchanger of the upper heat exchange system is arranged outside the water storage tank.

[0028] To further optimize the technical solution, when arranging the hot-end heat exchangers of the lower heat exchange system, one or more first hot-end heat exchangers are dispersed along the surrounding wall of the water tank.

[0029] When arranging the hot-end heat exchangers of the upper heat exchange system, one or more second hot-end heat exchangers are distributed along the surrounding wall of the water tank.

[0030] To further optimize the technical solution, when arranging the first cold-end heat exchanger of the lower heat exchange system, one or more first cold-end heat exchangers are arranged at an angle inside the first cooling tower, and the working medium inlet of the first cold-end heat exchanger is located at the top, and the working medium outlet of the first cold-end heat exchanger is located at the bottom.

[0031] When arranging the second cold-end heat exchangers in the upper heat exchange system, one or more second cold-end heat exchangers are arranged at an angle inside the second cooling tower, with the working medium inlet of the second cold-end heat exchanger located at the top and the working medium outlet of the second cold-end heat exchanger located at the bottom.

[0032] To further optimize the technical solution, when arranging the first cooling tower for the first cold-end heat exchanger of the lower heat exchange system, the first cooling tower is arranged around the first cold-end heat exchanger using the outer wall of the valve operating room of the reactor building.

[0033] When arranging the second cooling tower for the second cold-end heat exchanger in the upper heat exchange system, the second cooling tower is arranged around the second cold-end heat exchanger using the outer wall of the valve operating room of the reactor building.

[0034] Further optimize the technical solution by setting up an outdoor valve operating room for the passive heat removal device on the outer wall of the reactor building, and arranging the lower zone riser pipe, lower zone downpipe, upper zone riser pipe and upper zone downpipe, and correspondingly arranging the lower zone riser pipe isolation valve, lower zone downpipe isolation valve, upper zone riser pipe isolation valve and upper zone downpipe isolation valve.

[0035] The technical solution of this invention has the following advantages:

[0036] 1. The passive heat removal device for a pool-type reactor provided by the present invention rationally divides the reactor pool according to the temperature field distribution formed by the heat of the reactor core in the reactor pool. The area near the upper water surface in the reactor pool is divided into the upper layer zone, and the area near the lower reactor core is divided into the lower layer zone. Using separate heat pipe technology, the hot end heat exchangers are arranged in the lower layer zone and the upper layer zone respectively, and the corresponding cold end heat exchangers are arranged outside the reactor building. Under accident conditions, the water temperature in the lower zone of the reactor water tank reaches the set start-up temperature (e.g., 70°C) of the passive heat removal system first, and the lower heat exchange system starts to rapidly remove heat from the lower zone of the reactor water tank. As the accident progresses, the water temperature in the upper zone of the reactor water tank subsequently reaches the set start-up temperature (e.g., 70°C), and the upper heat exchange system starts to rapidly remove heat from the upper zone of the reactor water tank. Thus, the present invention can operate the upper and lower heat exchange systems simultaneously. Since the water temperature in the lower zone is higher than that in the upper zone, the heat transfer temperature difference of the heat exchangers arranged in the lower zone is greater, so the overall heat transfer efficiency is effectively improved after the layered arrangement.

[0037] 2. The passive heat removal device for pool-type reactors provided by the present invention, taking into account the structural characteristics of deep-well reactor pools, vertically arranges the upper and lower heat exchange systems within the reactor pool, effectively utilizing the vertical space within the reactor pool and greatly reducing the probability of collisions with reactor components in the lateral space.

[0038] 3. The passive heat removal device for pool reactors provided by this invention is suitable for atmospheric pressure pool reactors. It can utilize heat pipe technology and, through the reasonable arrangement of the passive heat removal device, quickly remove the heat from the pool water in an accident situation, thus preventing the pool water from boiling.

[0039] 4. The passive heat removal device for pool reactors provided by the present invention reduces the absolute pressure in the upper heat exchange system and / or the lower heat exchange system by evacuating the upper heat exchange system and / or the lower heat exchange system, making it easier for the working medium water in the upper heat exchange system and / or the pool water to boil and evaporate after heat exchange.

[0040] 5. The arrangement method of the passive heat removal device for pool reactors provided by the present invention utilizes the existing structure of the reactor building to set up a chimney structure around the cold end heat exchanger, and uses the chimney effect to achieve a stable airflow velocity, so that the device can operate in a passive manner to introduce heat into the ambient atmosphere without relying on external power supply and cold source. Attached Figure Description

[0041] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the passive heat removal device for a pool reactor provided by the present invention.

[0043] Figure 2 A schematic diagram of the arrangement of the second cold-end heat exchanger of the passive heat removal device for a pool reactor provided by the present invention.

[0044] Figure 3 A schematic diagram of the arrangement of the first cold-end heat exchanger of the passive heat removal device for a pool reactor provided by the present invention.

[0045] Figure 4 A heat exchange principle diagram of the chimney structure of the passive heat removal device for a pool reactor provided by the present invention;

[0046] Figure 5 A schematic diagram of the heat exchange principle of the cold end heat exchanger in the chimney structure of the passive heat removal device for a pool reactor provided by the present invention.

[0047] Figure 6 This is a schematic diagram of the arrangement of the upper zone heat exchanger of the passive heat removal device for a pool reactor provided by the present invention.

[0048] Figure label:

[0049] 1. Second hot-end heat exchanger; 2. First hot-end heat exchanger; 3. Second cold-end heat exchanger; 4. First cold-end heat exchanger; 5. Upper zone riser pipe; 6. Lower zone riser pipe; 7. Upper zone downcomer pipe; 8. Lower zone downcomer pipe; 9. Upper zone riser pipe isolation valve; 10. Upper zone downcomer pipe isolation valve; 11. Lower zone riser pipe isolation valve; 12. Lower zone downcomer pipe isolation valve; 13. Water filling valve; 14. Vacuum valve. 15. Chimney structure; 16. Vacuum unit; 17. First temperature measuring instrument; 18. First pressure measuring instrument; 19. Second temperature measuring instrument; 20. Second pressure measuring instrument; 21. Upper zone level gauge; 22. Lower zone level gauge; 23. Lower zone water filling pipe; 24. Upper zone water filling pipe; 25. Water filling port; 26. Vacuum interface; 27. Reactor building; 28. Reactor core; 29. ​​Pool gate. Detailed Implementation

[0050] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] In the description of this invention, it should be noted that the terms "upper," "lower," "vertical," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0052] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0054] Example 1

[0055] The reactor water pool has an inner diameter of 10m and a depth of 25m, forming a deep-well structure. The reactor core is located at the bottom of the pool. Numerous reactor components are arranged on the surrounding walls, such as four reactor coolant outlet pipes, four return pipes, reactor internals, and 29 pool gates. The lateral space available for arranging heat exchangers within the pool is limited. Under accident conditions, the heat generated by the reactor core is transferred from bottom to top, causing the pool water temperature to rise from top to bottom.

[0056] To solve the above-mentioned technical problems, the present invention, based on the above-mentioned pool-type reactor structure and layout requirements, as well as the temperature field characteristics inside the pool, sets the passive heat removal device as a lower heat exchange system and an upper heat exchange system, making full use of the longitudinal space, reducing the interference between the heat exchange system equipment and pipes and the reactor components and pool gates at the same pool water depth, and increasing the heat removal efficiency of the heat exchange system by utilizing the temperature difference of the pool water at different pool water depths.

[0057] like Figures 1 to 3As shown in the figure, this embodiment discloses a passive heat removal device for a pool reactor, including a lower heat exchange system and an upper heat exchange system.

[0058] The lower heat exchange system comprises a first hot-end heat exchanger and a first cold-end heat exchanger that form an internal circulation of the working medium between them. The first hot-end heat exchanger is located in the lower zone of the reactor water pool, and the first cold-end heat exchanger is located outside the reactor water pool. The lower heat exchange system is suitable for being put into operation and operating independently at the initial stage of an accident, rapidly removing heat from the lower zone of the reactor water pool.

[0059] The upper heat exchange system comprises a second hot-end heat exchanger and a second cold-end heat exchanger that form an internal circulation of the working medium. The second hot-end heat exchanger is located in the upper zone of the reactor water tank, while the second cold-end heat exchanger is located outside the reactor water tank. The upper heat exchange system is adapted to start when the water temperature in the upper zone of the reactor water tank reaches a set temperature, and operates in conjunction with the lower heat exchange system to rapidly remove heat from the reactor water tank.

[0060] The first hot-end heat exchanger of the lower heat exchange system and the second hot-end heat exchanger of the upper heat exchange system are distributed along the inner wall of the reactor water pool in the space between each reactor internal component and the water pool gate. The heat in the reactor water pool is carried to their respective cold-end heat exchangers outside the pool through the hot-end heat exchangers at different positions in the lateral and longitudinal spaces.

[0061] In this embodiment, deionized water is used as the working medium, which is suitable for the strong radiation environment inside the reactor. The working medium includes, but is not limited to, water, and can also be methanol, ethanol, or other coolants.

[0062] The aforementioned passive heat removal device for a pool-type reactor rationally divides the reactor water pool according to the temperature field distribution formed by the heat from the reactor core 28 within the pool. The area near the upper water surface is designated as the upper zone, and the area near the lower reactor core 28 is designated as the lower zone. The lower zone is located below the upper zone. A first hot-end heat exchanger is positioned in the lower zone, and a second hot-end heat exchanger is positioned in the upper zone. Under accident conditions, when the water temperature in the lower zone reaches the set start-up temperature of the heat exchange system (e.g., 70°C), the lower heat exchange system activates and rapidly removes heat from the lower zone. As the accident progresses, when the water temperature in the upper zone reaches the set start-up temperature of the heat exchange system (e.g., 70°C), the upper heat exchange system activates and rapidly removes heat from the upper zone. Therefore, this invention can simultaneously operate both the upper and lower heat exchange systems to rapidly remove heat from the pool water.

[0063] In one specific implementation, the lower heat exchange system's water tank includes at least one first hot-end heat exchanger 2, which is arranged in the lower part of the water tank. The lower heat exchange system's water tank includes a first cooling tower and at least one first cold-end heat exchanger 4, which is located inside the outdoor first cooling tower. The working medium outlet of the first hot-end heat exchanger 2 and the working medium inlet of the first cold-end heat exchanger 4 are connected by a lower-level riser pipe 6, and the working medium outlet of the first cold-end heat exchanger 4 and the working medium inlet of the first hot-end heat exchanger 2 are connected by a lower-level downcomer pipe 8. More specifically, one end of the lower-level riser pipe 6 is connected to the upper end cap of the first hot-end heat exchanger 2, and the other end is connected to the upper end cap of the first cold-end heat exchanger 4; one end of the lower-level downcomer pipe 8 is connected to the lower end cap of the first cold-end heat exchanger 4, and the other end is connected to the lower end cap of the first hot-end heat exchanger 2. In this embodiment, a closed circulation system is formed between the first hot-end heat exchanger 2, the lower zone riser 6, the first cold-end heat exchanger 4, and the lower zone downcomer 8, and the circulation system is filled with a working medium.

[0064] In one specific implementation, the upper heat exchange system's water tank includes at least one second hot-end heat exchanger 1, which is arranged in the upper space of the water tank. The outer portion of the upper heat exchange system's water tank includes a second cooling tower and at least one second cold-end heat exchanger 3, which is located inside the outdoor second cooling tower. The working medium outlet of the second hot-end heat exchanger 1 and the working medium inlet of the second cold-end heat exchanger 3 are connected by an upper-level riser pipe 5, and the working medium outlet of the second cold-end heat exchanger 3 and the working medium inlet of the second hot-end heat exchanger 1 are connected by an upper-level downcomer pipe 7. More specifically, one end of the upper-level riser pipe 5 is connected to the upper end cap of the second hot-end heat exchanger 1, and the other end is connected to the upper end cap of the second cold-end heat exchanger 3; one end of the upper-level downcomer pipe 7 is connected to the lower end cap of the second cold-end heat exchanger 3, and the other end is connected to the lower end cap of the second hot-end heat exchanger 1. In this embodiment, a closed circulation system is formed between the second hot-end heat exchanger 1, the upper zone riser 5, the second cold-end heat exchanger 3, and the upper zone downcomer 7, and the circulation system is filled with a working medium.

[0065] A first isolation valve is respectively installed on the lower-level riser pipe 6 and the lower-level downcomer pipe 8. More specifically, the first isolation valve on the lower-level riser pipe 6 is the lower-level riser pipe isolation valve 11, and the first isolation valve on the lower-level downcomer pipe 8 is the lower-level downcomer pipe isolation valve 12. As a further improved embodiment, two normally closed electric isolation valves are provided in parallel on the upper-level riser pipe, and the normally closed electric isolation valves in this embodiment are not limited to two; two normally closed electric isolation valves are provided in parallel on the lower-level downcomer pipe, and the normally closed electric isolation valves in this embodiment are not limited to two.

[0066] A second isolation valve is respectively installed on the upper-level riser pipe 5 and the upper-level downcomer pipe 7. More specifically, the second isolation valve on the upper-level riser pipe 5 is the upper-level riser pipe isolation valve 9, and the second isolation valve on the upper-level downcomer pipe 7 is the upper-level downcomer pipe isolation valve 10. As a further improved embodiment, two normally closed electric isolation valves are provided in parallel on the upper-level riser pipe, and the normally closed electric isolation valves in this embodiment are not limited to two; two normally closed electric isolation valves are provided in parallel on the upper-level downcomer pipe 7, and the normally closed electric isolation valves in this embodiment are not limited to two.

[0067] The second hot-end heat exchanger 1 and the first hot-end heat exchanger 2 are made of heat exchange tubes, which are arranged into a tube sheet structure. The heat exchange tubes are finned. The heat exchange tubes can be plain tubes, radial or axial finned tubes to enhance heat transfer.

[0068] like Figure 1 As shown, more specifically, in this embodiment, several first hot-end heat exchangers 2 are provided and distributed along the side wall of the water storage tank. Each first hot-end heat exchanger 2 is connected in parallel via pipelines or is independent of the others. Each first hot-end heat exchanger 2 is equipped with a lower-level level gauge 22 for detecting the liquid level within the first hot-end heat exchanger. In some embodiments, the water storage tank is circular, with each first hot-end heat exchanger 2 correspondingly distributed circumferentially within the water storage tank.

[0069] Several first cold-end heat exchangers 4 are provided and arranged at an angle, and each first cold-end heat exchanger 4 is connected in parallel or independently. In some specific embodiments, two first cold-end heat exchangers 4 are provided and arranged at an angle relative to each other.

[0070] Several second hot-end heat exchangers 1 are provided and arranged at intervals along the side wall of the water storage tank. The second hot-end heat exchangers 1 are connected in parallel or independently via pipelines. Each second hot-end heat exchanger 1 is equipped with an upper-level liquid level gauge 21 for detecting the liquid level in the upper-level heat exchanger. In some embodiments, the water storage tank is circular, and the second hot-end heat exchangers 1 are correspondingly distributed circumferentially within the water storage tank.

[0071] Several second cold-end heat exchangers 3 are provided and arranged at an angle, and each second cold-end heat exchanger 3 is connected in parallel or independently. In some specific embodiments, two second cold-end heat exchangers 3 are provided and arranged at an angle relative to each other.

[0072] In one specific implementation, the first cooling tower is a water-cooled tower or a chimney structure. The second cooling tower is also a water-cooled tower or a chimney structure. The first and second cooling towers can be configured according to actual conditions, and are not limited to water-cooled towers or chimney structures; other structures for dissipating heat from the air can also be used.

[0073] As a further improved implementation, a vacuum unit 16 is also included. The vacuum unit 16 is connected to the upper and / or lower heat exchange systems and is adapted to evacuate the upper and / or lower heat exchange systems to lower the boiling point of the working medium. That is, by evacuating the upper and / or lower heat exchange systems, the absolute pressure within the upper and / or lower heat exchange systems is reduced, making it easier for the working medium (water) to boil and evaporate after heat exchange with the pool water. Currently, the design operating temperature of the pool reactor is below 100°C. To enable the circulating working medium (i.e., deionized water) in the passive heat removal device under normal pressure to achieve boiling heat transfer, a vacuum unit is arranged near the device, and the length of the vacuum evacuation pipeline is shortened as much as possible. Under normal operating conditions, water is introduced into the device through the water filling valve 13 to maintain a certain liquid level in the second hot end heat exchanger and the first hot end heat exchanger. Then, the equipment in the vacuum unit 16 is used to perform a vacuuming operation. After the device reaches a certain vacuum level, the riser isolation valve and the downcomer isolation valve are closed to put the device into standby mode.

[0074] More specifically, the vacuum unit 16 is connected to the lower zone riser pipe 6 via a vacuum extraction pipeline. The vacuum extraction pipeline is equipped with a vacuum valve 14, a second temperature measuring instrument 19, and a second pressure measuring instrument 20. The vacuum valve 14 controls the opening and closing of the vacuum extraction pipeline, the second temperature measuring instrument 19 detects the temperature in the vacuum extraction pipeline and the lower zone riser pipe 6, and the second pressure measuring instrument 20 detects the pressure in the vacuum extraction pipeline and the lower zone riser pipe 6. A vacuum port 26 is provided on the upper zone riser pipe 5, and the vacuum unit 16 is connected to the vacuum port 26 via the second vacuum extraction pipeline.

[0075] As a further improved implementation, a working medium replenishment unit is also included. The working medium replenishment unit is connected to the upper heat exchange system and / or the lower heat exchange system, and is suitable for replenishing the working medium for the upper and / or lower heat exchange systems. The working medium replenishment unit includes a replenishment tank, a replenishment pipeline, and a water filling valve 13. The replenishment tank and the vacuum unit are housed in the same enclosure. The replenishment pipeline is connected to the side of the lower downcomer 8, and a water filling valve 13 is installed on the replenishment pipeline. The replenishment tank is also equipped with a water filling port 25, and a water filling valve is installed at the water filling port 25. Before replenishing water, the vacuum unit evacuates the upper heat exchange system, opens the water filling valve and the water filling valve 13, and because the external pressure is greater than the internal pressure of the closed-loop system, the working medium to be replenished can automatically flow into the lower downcomer 8 in a passive manner, thus achieving the replenishment of the working medium.

[0076] In a preferred embodiment, the upper and lower heat exchange systems share a vacuum unit 16 and a working medium supply unit. Specifically, in this embodiment, the lower heat exchange system is connected to a lower zone water filling pipe 23, and the upper heat exchange system is connected to an upper zone water filling pipe 24. The lower zone water filling pipe 23 and the upper zone water filling pipe 24 are connected in parallel and both are connected to the supply tank. Vacuum extraction pipelines are respectively installed on the riser pipes of the upper and lower heat exchange systems. The two vacuum extraction pipelines are connected in parallel and both are connected to the vacuum unit 16. Vacuum valves are installed on the vacuum extraction pipelines. A first temperature measuring instrument 17 and a first pressure measuring instrument 18 are installed on the upper zone riser pipe 5 of the upper heat exchange system.

[0077] The operation process of the passive heat removal device for the above-mentioned pool reactor is as follows:

[0078] In the event of an accident in a pool reactor, the pool water temperature near the core region rises abnormally before that near the surface. At this point, the first hot-end heat exchanger 2 quickly starts interlocked based on a detection signal, and the lower-level riser isolation valve 11 and lower-level downcomer isolation valve 12 are also interlocked based on the detection signal. The first hot-end heat exchanger 2 absorbs heat from the pool water through convection and radiation. The working medium inside the first hot-end heat exchanger 2 undergoes a boiling phase change at a temperature far below its atmospheric boiling point under a certain vacuum. The working medium vapor enters the inlet of the first cold-end heat exchanger 4 along the lower-level riser pipe 6, where it condenses after exchanging heat with the outside air. The condensed liquid working medium enters the outlet of the first cold-end heat exchanger 4, and then flows back to the first hot-end heat exchanger 2 along the lower-level downcomer pipe 8, where it is reheated for the next evaporation-condensation cycle.

[0079] As the accident progresses, core heat accumulates in the reactor pool, causing the water temperature in the upper zone to rise. The second hot-end heat exchanger 1 activates, interlocking with the upper zone riser isolation valve 9 and the upper zone downcomer isolation valve 10 based on detection signals. The second hot-end heat exchanger 1 absorbs heat from the pool water. The working medium undergoes a boiling phase change at a temperature far below its atmospheric boiling point under a certain vacuum. The working medium vapor enters the inlet of the second cold-end heat exchanger 3 via the upper zone riser pipe 5, where it condenses after exchanging heat with the outside air. The condensed liquid working medium enters the outlet of the second cold-end heat exchanger 3 and then flows back to the second hot-end heat exchanger 1 via the upper zone downcomer 7, where it is reheated for the next evaporation-condensation cycle.

[0080] The lower zone riser isolation valve 11, the lower zone downcomer isolation valve 12, the upper zone riser isolation valve 9, and the upper zone downcomer isolation valve 10 are all located in the external space of the reactor building 27, which facilitates the operation and maintenance of the valves.

[0081] Example 2

[0082] To improve the heat exchange efficiency of the passive heat removal system in a pool reactor, a reasonable layout of the passive heat removal device is required to maximize the use of various favorable conditions inside and outside the reactor and establish a passive natural circulation heat conduction path from the reactor pool to the outdoor environment. Therefore, this embodiment discloses a method for arranging the passive heat removal device of a pool reactor, which is the arrangement method of the passive heat removal device of the pool reactor in Embodiment 1, and specifically includes the following steps:

[0083] The reactor core is located at the bottom of the reactor pool. The heat generated by the reactor core is transferred from the bottom to the upper water surface. The reactor pool has a deep well structure. According to the temperature field distribution formed by the heat from the reactor core in the reactor pool, the area near the upper water surface is divided into the upper layer area, and the area near the lower reactor core is divided into the lower layer area.

[0084] The hot-end heat exchangers of the upper heat exchange system are arranged in the upper area of ​​the water storage tank, while the cold-end heat exchangers of the upper heat exchange system are arranged outside the water storage tank.

[0085] The hot-end heat exchangers of the lower heat exchange system are arranged in the lower area of ​​the water storage tank, while the cold-end heat exchangers of the lower heat exchange system are arranged outside the water storage tank.

[0086] When arranging the hot-end heat exchangers of the upper heat exchange system, one or more second hot-end heat exchangers 1 are distributed along the side wall of the water tank to ensure the temperature uniformity of each position in the same layer of water in the water tank.

[0087] When arranging the hot-end heat exchangers of the lower heat exchange system, one or more first hot-end heat exchangers 2 are distributed along the side wall of the water tank to ensure the temperature uniformity of the water in the same layer of the water tank.

[0088] When arranging the cold-end heat exchangers in the lower heat exchange system, one or more first cold-end heat exchangers 4 are arranged at an angle inside the first cooling tower, with the working medium inlet of the first cold-end heat exchanger 4 located at the top and the working medium outlet of the first cold-end heat exchanger 4 located at the bottom. On the one hand, the working medium inside the inclined first cold-end heat exchanger 4 has a longer contact time with the cooling air of the first cooling tower; on the other hand, it can ensure that the condensed working medium flows smoothly into the downcomer 8 in the lower zone.

[0089] When arranging the cold-end heat exchangers of the upper heat exchange system, one or more second cold-end heat exchangers 3 are arranged obliquely inside the second cooling tower, with the working medium inlet of the second cold-end heat exchanger 3 located at the top and the working medium outlet of the second cold-end heat exchanger 3 located at the bottom. On the one hand, the working medium inside the obliquely arranged second cold-end heat exchanger 3 has a longer contact time with the cooling air of the second cooling tower; on the other hand, it can ensure that the condensed working medium flows smoothly into the downcomer 7 in the upper zone.

[0090] like Figures 2 to 6 As shown, the operating areas of the first cold-end heat exchanger 4, the second cold-end heat exchanger 3, and the valves of the device are located adjacent to the outer wall of the reactor building. An outdoor valve operating room for the passive heat removal device is set up on the outer wall of the reactor building, and the lower zone riser pipe 6, the lower zone downcomer pipe 8, the upper zone riser pipe 5, and the upper zone downcomer pipe 7 are arranged there, along with the corresponding lower zone riser pipe isolation valve 11, lower zone downcomer pipe isolation valve 12, upper zone riser pipe isolation valve 9, and upper zone downcomer pipe isolation valve 10 on the pipes.

[0091] The first cold-end heat exchanger 4 and the second cold-end heat exchanger 3 are arranged adjacent to the valve operating room. Cooling towers are arranged around the cold-end heat exchangers using the outer wall of the valve operating room. That is, the first cooling tower is arranged around the first cold-end heat exchanger 4 using the outer wall of the valve operating room of the reactor building 27; and the second cooling tower is arranged around the second cold-end heat exchanger 3 using the outer wall of the valve operating room of the reactor building 27.

[0092] like Figure 4 and Figure 5 As shown, in this embodiment, both the first and second cooling towers are chimney structures 15. Utilizing the existing structure of the reactor building, chimney structures are installed around the second and first cold-end heat exchangers. Outdoor cold air enters the chimney structure through the air inlet below the air cooler. After exchanging heat with the cold-end heat exchangers, the hot air rises along the chimney structure, creating a thermal pressure difference between the chimney inlet and outlet. When the hot air is discharged, a local negative pressure is formed inside the chimney structure. The chimney structure's air inlet then draws in outside cold air to fill this negative pressure area. Cooling of the cold-end heat exchangers is achieved through the automatic entry and exit of outside cold air.

[0093] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A passive heat removal device for a pool reactor, characterized in that, include: The lower heat exchange system has a first hot-end heat exchanger and a first cold-end heat exchanger that form an internal circulation of the working medium between them. The first hot-end heat exchanger is arranged in the lower region of the reservoir, and the first cold-end heat exchanger is arranged outside the reservoir. The lower heat exchange system is suitable for being put into operation and operating independently at the initial stage of an accident, so as to quickly remove the heat from the lower region of the reservoir. The upper heat exchange system has a second hot-end heat exchanger and a second cold-end heat exchanger that form an internal circulation of the working medium between them. The second hot-end heat exchanger is arranged in the upper region of the water tank, and the second cold-end heat exchanger is arranged outside the water tank. The upper heat exchange system is adapted to start when the water temperature in the upper region of the water tank reaches a set temperature, and to operate in conjunction with the lower heat exchange system to quickly remove heat from the water tank. The first hot-end heat exchanger of the lower heat exchange system and the second hot-end heat exchanger of the upper heat exchange system are distributed along the inner wall of the water tank in the space between each internal component and the water tank gate. The heat in the water tank is carried to the respective cold-end heat exchanger outside the tank through the hot-end heat exchangers at different positions in the horizontal and vertical spaces.

2. The passive heat removal device for a pool reactor according to claim 1, characterized in that, The lower region of the reactor water pool is the region close to the reactor core, and the upper region of the reactor water pool is the region far from the reactor core; the lower region of the reactor water pool is located below the upper region of the reactor water pool, and the hot-end heat exchanger of the lower heat exchange system is located below the hot-end heat exchanger of the upper heat exchange system.

3. The passive heat removal device for a pool reactor according to claim 1, characterized in that, The lower heat exchange system includes at least one first hot end heat exchanger (2), and the lower heat exchange system also includes a first cooling tower and at least one first cold end heat exchanger (4); the working medium outlet of the first hot end heat exchanger (2) and the working medium inlet of the first cold end heat exchanger (4) are connected through a lower zone riser pipe (6), and the working medium outlet of the first cold end heat exchanger (4) and the working medium inlet of the first hot end heat exchanger (2) are connected through a lower zone downcomer pipe (8), and a first isolation valve is provided on the lower zone riser pipe (6) and the lower zone downcomer pipe (8); The upper heat exchange system includes at least one second hot-end heat exchanger (1), and the upper heat exchange system also includes a second cooling tower and at least one second cold-end heat exchanger (3); the working medium outlet of the second hot-end heat exchanger (1) and the working medium inlet of the second cold-end heat exchanger (3) are connected through an upper zone riser pipe (5), and the working medium outlet of the second cold-end heat exchanger (3) and the working medium inlet of the second hot-end heat exchanger (1) are connected through an upper zone downcomer pipe (7), and a second isolation valve is provided on the upper zone riser pipe (5) and the upper zone downcomer pipe (7).

4. The passive heat removal device for a pool reactor according to claim 1, characterized in that, The lower heat exchange system has several first hot end heat exchangers (2) arranged dispersedly along the surrounding wall of the water tank, and each first hot end heat exchanger (2) is connected in parallel or independent of each other; the lower heat exchange system has several first cold end heat exchangers (4) arranged at an angle, and each first cold end heat exchanger (4) is connected in parallel or independent of each other. and / or The upper heat exchange system has several second hot-end heat exchangers (1) arranged dispersedly along the surrounding wall of the water tank, and each second hot-end heat exchanger (1) is connected in parallel or independent of each other; the upper heat exchange system has several second cold-end heat exchangers (3) arranged at an angle, and each second cold-end heat exchanger (3) is connected in parallel or independent of each other.

5. The passive heat removal device for a pool reactor according to claim 3, characterized in that, The first cooling tower is a water-cooled tower or a chimney structure; the second cooling tower is a water-cooled tower or a chimney structure.

6. The passive heat removal device for a pool reactor according to any one of claims 1 to 5, characterized in that, Also includes: A vacuum unit (16) is connected to the upper heat exchange system and / or the lower heat exchange system, and the vacuum unit (16) is adapted to evacuate the upper heat exchange system and / or the lower heat exchange system to reduce the boiling point of the working medium. and / or A working medium replenishment unit is connected to the upper heat exchange system and / or the lower heat exchange system, and the working medium replenishment unit is adapted to replenish the working medium for the upper heat exchange system and / or the lower heat exchange system.

7. A method for arranging passive heat removal devices for a pool-type reactor, characterized in that, The method is the arrangement method of the passive heat removal device for the pool reactor as described in any one of claims 1 to 6, and specifically includes the following steps: The water storage tank is divided into a lower zone and an upper zone, distributed from bottom to top; The first hot-end heat exchanger of the lower heat exchange system is arranged in the lower area of ​​the water storage tank, and the first cold-end heat exchanger of the lower heat exchange system is arranged outside the water storage tank. The second hot-end heat exchanger of the upper heat exchange system is arranged in the upper area of ​​the water storage tank, and the second cold-end heat exchanger of the upper heat exchange system is arranged outside the water storage tank.

8. The method for arranging the passive heat removal device for a pool reactor according to claim 7, characterized in that, When arranging the heat exchangers at the hot end of the lower heat exchange system, one or more first hot end heat exchangers (2) are dispersed along the surrounding wall of the water tank. When arranging the heat exchangers at the hot end of the upper heat exchange system, one or more second heat exchangers (1) are distributed along the surrounding wall of the water tank.

9. The method for arranging the passive heat removal device for a pool reactor according to claim 7, characterized in that, When arranging the first cold end heat exchanger (4) of the lower heat exchange system, one or more first cold end heat exchangers (4) are arranged at an angle in the first cooling tower, and the working medium inlet of the first cold end heat exchanger (4) is set at the top and the working medium outlet of the first cold end heat exchanger (4) is set at the bottom. When arranging the second cold-end heat exchanger (3) of the upper heat exchange system, one or more second cold-end heat exchangers (3) are arranged at an angle in the second cooling tower, and the working medium inlet of the second cold-end heat exchanger (3) is set at the top, and the working medium outlet of the second cold-end heat exchanger (3) is set at the bottom.

10. The method for arranging the passive heat removal device for a pool reactor according to any one of claims 7 to 9, characterized in that, When arranging the first cooling tower for the first cold end heat exchanger (4) of the lower heat exchange system, the first cooling tower is arranged around the first cold end heat exchanger (4) using the outer wall of the valve operating room of the reactor building (27). When arranging the second cooling tower for the second cold end heat exchanger (3) of the upper heat exchange system, the second cooling tower is arranged around the second cold end heat exchanger (3) using the outer wall of the valve operating room of the reactor building (27).

11. The method for arranging the passive heat removal device for a pool reactor according to any one of claims 7 to 9, characterized in that, An outdoor valve operating room for a passive heat removal device is set up on the outer wall of the reactor building. The lower zone riser pipe (6), the lower zone downpipe (8), the upper zone riser pipe (5) and the upper zone downpipe (7) are arranged, and the lower zone riser pipe isolation valve (11), the lower zone downpipe isolation valve (12), the upper zone riser pipe isolation valve (9) and the upper zone downpipe isolation valve (10) are arranged accordingly.

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