Nuclear power plant water system and cooling method

Abstract

The present application discloses a nuclear power plant water system and a cooling method. The nuclear power plant water system comprises a plurality of trains and non-safety-related pools, each train is provided with a safety-related pool, and the safety-related pools are pairwise communicated with each other; each train has a first working condition and a second working condition, and the total volume of water carried by any two safety-related pools is sufficient to support the operation of the system under the second working condition for at least three days. The non-safety-related pools are capable of storing at least a volume of water that is sufficient for the system to operate under the second working condition for 27 days. Water resources stored in the non-safety-related pools and the safety-related pools can be flexibly allocated to different trains according to actual needs, thereby avoiding underutilization and waste of water resources, effectively lowering the demand for total water storage capacity, and thus reducing the construction and maintenance costs of pools. The reduction in total water storage capacity of a nuclear power plant means a decrease in the occupation and consumption of land and water resources during the construction of pools.

Description

A nuclear power plant water system and cooling method Technical Field

[0001] This application relates to the field of nuclear power technology, and in particular to a water system and cooling method for nuclear power plants. Background Technology

[0002] HAD102 / 08-2020 (full name: Design of Reactor Coolant Systems and Related Systems for Nuclear Power Plants) requires that when the capacity requirements of the final heat sink in the short and long term do not allow for the use of inexhaustible natural water bodies, "the capacity of the final heat sink should be guaranteed by the readily available water supply within the plant site," and "the readily available water supply... is generally 30 days"; "...after any hypothetical initiating event (such as an external emergency like an earthquake) occurs, the minimum amount of water required immediately to bring the reactor to a safe shutdown state (including margins considering uncertainties) should be available," and this minimum amount of water "is designed to ensure heat removal for 3 days" and "...should already be stored in the corresponding final heat sink system (such as water tanks or cooling tower pools)."

[0003] Since the final heat trap system typically consists of several redundant series, the design usually involves equipping each series with a water tank capable of holding enough water for 30 days, and these tanks are isolated from each other. In other words, in traditional designs, the total volume of the system's water tanks is the number of series multiplied by the water volume required for 30 days in the event of a single series failure. While this design meets regulatory requirements, it significantly increases engineering costs. Summary of the Invention

[0004] The main purpose of this application is to propose a water system and cooling method for nuclear power plants, aiming to solve the technical problem of how to reduce the cost of the water system for nuclear power plants while ensuring that nuclear power plants have sufficient water.

[0005] To achieve the above objectives, this application proposes a water system for nuclear power plants, comprising:

[0006] Multiple series, each series is equipped with a safety-grade water tank, each safety-grade water tank is connected to each other in pairs, each series has a first operating condition and a second operating condition, and the total water volume carried by any two safety-grade water tanks is configured to supply the system for at least 3 days of operation under the second operating condition;

[0007] The non-safety-grade water tank is configured to store enough water for the system to operate under the second operating condition for at least 27 days. After the safety-grade water tank has been operating under the second operating condition for 3 days, the non-safety-grade water tank is connected to each of the safety-grade water tanks.

[0008] Specifically, the total volume of the safety-grade and non-safety-grade water pools in the nuclear power plant water system provided in this application is the water volume required for the entire system to operate for 30 days under accident conditions (at least two safety-grade water pools provide water for 3 days, and the non-safety-grade water pools provide water for 27 days). It should be noted that although the water volume required for the entire system for 30 days under accident conditions is greater than the water volume required for a single series for 30 days, compared to related technologies where each series is individually equipped with water for 30 days under accident conditions, the water volume of the nuclear power plant water system in this application is far smaller than the total volume of the system in traditional designs (total volume in traditional designs = number of series multiplied by the water volume required for a single series for 30 days under accident conditions). Furthermore, in the nuclear power plant water system of this application, the volume of the safety-grade water pools in each series is smaller, significantly reducing the volume of each safety-grade water pool, thereby reducing the engineering construction and maintenance costs of each safety-grade water pool and reducing the system's occupation and consumption of land and water resources.

[0009] In some embodiments, each of the series includes a cooling tower, a water pump, and a heat exchanger. The water pump is configured to connect to the safety-grade water tank and to direct cooling water in the safety-grade water tank to the heat exchanger. The heat exchanger is configured to transfer high-temperature heat generated by the nuclear reactor to the cooling water. The cooling water passes through the heat exchanger, enters the cooling tower to release heat, and then flows back into the safety-grade water tank.

[0010] In some embodiments, each of the series further includes a first filter and a second filter, the first filter being disposed between the safety-grade water tank and the water pump, and the second filter being disposed between the water pump and the heat exchanger.

[0011] In some embodiments, the nuclear power plant water system further includes a wastewater discharge device configured to discharge wastewater generated by the first filter;

[0012] And / or,

[0013] The sewage discharge device is configured to discharge the wastewater generated by the second filter;

[0014] And / or,

[0015] The wastewater discharge device is configured to discharge wastewater generated by the cooling tower.

[0016] In some embodiments, the heat exchangers of each series are configured to be able to connect to the safety-grade water tanks of any other series.

[0017] In some embodiments, the nuclear power plant water system further includes a first connecting pipe and a plurality of first isolation valves, wherein each of the safety-grade water pools is connected through the first connecting pipe, and the first isolation valve is disposed on the first connecting pipe and configured to enable two connected safety-grade water pools to be connected or isolated.

[0018] In some embodiments, two first isolation valves are provided between two connected safety-grade water tanks, namely a first valve and a second valve. The two connected safety-grade water tanks are a first water tank and a second water tank. The non-safety-grade water tank is connected to the first connecting pipe between the first water tank and the second water tank. The first valve is configured to connect or disconnect the first water tank from the non-safety-grade water tank, and the second valve is configured to connect or disconnect the second water tank from the non-safety-grade water tank.

[0019] In some embodiments, the nuclear power plant water system further includes a plurality of second connecting pipes, each of the safety-grade water tanks is connected to at least one second connecting pipe, and each of the second connecting pipes is connected to the non-safety-grade water tank.

[0020] In some embodiments, the nuclear power plant water system further includes a second isolation valve, which is disposed between the non-safety-grade water tank and the safety-grade water tank, for controlling the connection or isolation between the safety-grade water tank and the non-safety-grade water tank.

[0021] In some embodiments, the nuclear power plant water system further includes a water replenishment device configured to replenish cooling water to the safety-grade pool operating under the first condition.

[0022] In some embodiments, the nuclear power plant water system further includes a makeup water pump, which is located between the non-safety level water tank and the safety level water tank, and is configured to direct cooling water from the non-safety level water tank to the safety level water tank.

[0023] and / or

[0024] The water replenishment pump is located between the connected safety-grade water tanks.

[0025] In some embodiments, the nuclear power plant water system further includes a dosing device configured to dispense chemicals into the safety-grade pool.

[0026] A second aspect of this application also provides a cooling method applicable to the nuclear power plant water system described in any of the above embodiments, the cooling method comprising:

[0027] When any of the series enters the second working condition, the safety-level water tank in the series becomes an emergency water tank, and at least one other safety-level water tank connected to the emergency water tank is controlled to replenish water to the emergency water tank.

[0028] After the accident water tank has been in operation for 3 days, the non-safety level water tank will be used to replenish the accident water tank.

[0029] In some embodiments, when the non-safety level water tank replenishes water to the emergency water tank, the non-safety level water tank replenishes water to the second connecting pipe connecting the non-safety level water tank and the emergency water tank;

[0030] Alternatively, the non-safety-grade water tank may replenish water to the first connecting pipe that connects the two safety-grade water tanks.

[0031] In some embodiments, each of the series includes a cooling tower, a water pump, and a heat exchanger, the heat exchanger being disposed between the water pump and the cooling tower, the water pump being connected to the safety-level water tank, wherein the heat exchanger connected to the emergency water tank is a first heat exchanger, and the cooling method further includes:

[0032] When any of the series enters the second operating condition and the emergency water tank is unable to supply water to the first heat exchanger, at least one of the safety-grade water tanks in another series is controlled to supply water to the first heat exchanger.

[0033] Compared with the prior art, the beneficial effects of this application are:

[0034] In the technical solution of this application, the nuclear power plant water system includes multiple series and non-safety-grade pools. Each series is equipped with a safety-grade pool, and all safety-grade pools are interconnected. The system has a first operating condition and a second operating condition. The total water volume carried by any two safety-grade pools is sufficient to supply the system for at least three days under the second operating condition. Therefore, when a safety-grade pool fails, the safety-grade pools of other series can support the operation of the series whose safety-grade pool has failed, reducing the impact on the cooling capacity of the entire nuclear power plant. Furthermore, when a series is in the second operating condition, the interconnected design of the safety-grade pools allows water from other safety-grade pools to be allocated to the series in the second operating condition, ensuring a rapid supply of cooling water, enhancing the system's flexibility and responsiveness, and thus ensuring the continuous cooling operation of the entire nuclear power plant to guarantee its safety. The total water volume of any two safety-grade water tanks is configured to supply the system for at least 3 days under the second operating condition. In an emergency, the system can maintain sufficient cooling capacity to cope with short-term failures or power outages. This reduces the construction and maintenance costs of the safety-grade water tanks, saves water resources, and ensures sufficient cooling water, effectively reducing safety hazards.

[0035] In addition, the non-safety-grade pool in this application can store enough water to supply the system for at least 27 days of operation under Condition 2. Compared to related technologies where each series is equipped with a pool capable of storing enough water for 30 days to meet regulatory requirements, this effectively reduces the overall water storage requirement, thereby lowering the construction and maintenance costs of the pool. Furthermore, since not all series are simultaneously in Condition 2 during nuclear power plant operation, the water resources stored in the non-safety-grade and safety-grade pools can be flexibly allocated to different series according to actual needs, avoiding idle and wasted water resources. The reduction in the overall water storage capacity of the nuclear power plant means a reduction in the land and water resources occupied and consumed during pool construction. This helps reduce the environmental impact of nuclear power plant construction and improves the feasibility of environmental protection and sustainable development. It should be noted that although the total water storage capacity of this application is lower than that of traditional system designs, the 27-day storage capacity of the non-safety-grade pool combined with the 3-day storage capacity of the safety-grade pool still meets the regulatory requirements for the safe operation of nuclear power plants. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0037] Figure 1 is a schematic diagram of the structure of a nuclear power plant water system according to an embodiment of this application;

[0038] Figure 2 is a schematic flowchart of a cooling method in one embodiment of this application;

[0039] Figure 3 is a schematic flowchart of a cooling method in another embodiment of this application.

[0040] Reference numerals: Nuclear power plant water system 100; Series 110; Safety-grade water tank 111; Cooling tower 112; Water pump 113; Heat exchanger 114; First filter 115; Second filter 116; Non-safety-grade water tank 120; First isolation valve 130; Second isolation valve 140; Makeup water pump 150; First connecting pipe 160; Second connecting pipe 170.

[0041] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0043] In related technologies, seawater is commonly used to cool nuclear power plant equipment. However, during the heat exchange process between the cooling tower and the heat-carrying seawater, water droplets are blown away, causing salt from the seawater to adhere to the equipment, leading to structural corrosion and even environmental problems. Therefore, some mature designs use desalinated water as the working medium. However, nuclear power plant cooling systems require large amounts of water, especially in inland areas. The seawater desalination process consumes a significant amount of energy, and the large consumption of desalinated water would severely increase the operating costs of nuclear power plants (for inland nuclear power plants, the transportation costs of bringing desalinated water are extremely high). Furthermore, if freshwater is used directly to cool inland nuclear power plants, the massive consumption of freshwater by the cooling system could lead to insufficient cooling water supply, increasing safety hazards. Furthermore, the design of cooling systems for nuclear power plants in related technologies typically involves setting up a water tank in each series that can store enough water to supply the series for at least 30 days of operation under high load conditions. This results in a huge water consumption for the entire system. Since freshwater resources are already scarce, the cooling system in these technologies will seriously lead to insufficient cooling water supply, resulting in extremely high safety hazards. Moreover, equipping each series with a water tank that can store at least 30 days of water will significantly increase the construction and maintenance costs of the water tank and will also occupy too much land resources.

[0044] Therefore, referring to Figure 1, this application provides a nuclear power plant water system 100, including multiple series 110 and a non-safety-grade water pool 120. Each series 110 is equipped with a safety-grade water pool 111, and each safety-grade water pool 111 is interconnected. Each series 110 has a first operating condition and a second operating condition. In some embodiments, the cooling water source for series 110 in the first operating condition can be provided by the safety-grade water pool 111 or by other external water sources. The cooling water source for series 110 in the second operating condition can also be provided by the safety-grade water pool 111. It should be noted that in some embodiments, series 110 in the first operating condition can be in a normal operating state, while series 110 in the second operating condition can be in an abnormal operating state (including earthquakes and loss of external power). For ease of understanding, the following description uses the system operating under high load as an example of the second operating condition. The water consumption of series 110 in the first operating condition is supplemented by an external water supply system. The total water volume held by any two safety-level water tanks 111 is configured to supply the system for at least 3 days of operation under the second condition.

[0045] Specifically, each series 110 is equipped with a safety-grade water tank 111. These safety-grade water tanks 111 are connected in pairs via pipes to form a redundant water supply network. To ensure sufficient cooling water supply under the second operating condition, the total water volume of any two safety-grade water tanks 111 is sufficient to supply the system for at least 3 days under the second operating condition. This ensures that in emergencies, the system has sufficient cooling water supply to maintain adequate cooling capacity to cope with short-term failures or power outages, reducing safety hazards and thus ensuring the safe operation of the nuclear power plant. In addition, the nuclear power plant water system 100 also includes a non-safety-grade water tank 120. The non-safety-grade water tank 120 is configured to store enough water to supply the system for at least 27 days under the second operating condition. After the safety-grade water tanks 111 have been operating under the second operating condition for 3 days, the non-safety-grade water tank 120 can be connected to each safety-grade water tank 111 via pipes to provide additional cooling water to each series 110. This ensures that the system can continuously provide sufficient cooling water during long-term high-load operation, thereby ensuring the normal operation of the nuclear power plant. Compared to related technologies that require each series to have a water storage capacity sufficient for 30 days to meet regulatory requirements, this approach effectively reduces the overall water storage demand, thereby lowering the number of pools needed and maintenance costs. It should be noted that reducing the overall water storage capacity of a nuclear power plant means reducing the land and water resource occupation and consumption during pool construction, contributing to ecological protection. In other words, the proposed solution not only meets nuclear power safety regulations but also optimizes water resource utilization and reduces project costs.

[0046] Each series 110 is equipped with a safety-level water tank 111, and all safety-level water tanks 111 are interconnected. This allows safety-level water tanks 111 of other series 110s to provide a backup water source if a safety-level water tank 111 of one series 110 fails, thereby improving system redundancy and safety. For example, when a safety-level water tank 111 fails or has insufficient water, the safety-level water tanks 111 of other series 110s can support the operation of the failed series 110, reducing the impact on the cooling capacity of the entire nuclear power plant. When a series 110 is in the second operating condition, the interconnected design of the safety-level water tanks 111 allows water from other safety-level water tanks 111 to be allocated to the series 110 in the second operating condition, ensuring a rapid supply of cooling water and enhancing the system's flexibility and responsiveness.

[0047] Referring to Figure 1, in some embodiments, each series 110 includes a cooling tower 112, a water pump 113, and a heat exchanger 114. The water pump 113 is configured to connect to the safety-grade water tank 111 and direct the cooling water from the safety-grade water tank 111 to the heat exchanger 114. The heat exchanger 114 is configured to transfer the high-temperature heat generated by the nuclear reactor to the cooling water. After passing through the heat exchanger 114, the cooling water enters the cooling tower 112 to release heat and then flows back into the safety-grade water tank 111. Specifically, the cooling process of each series 110 is as follows: Cooling water in the safety-grade water tank 111 is drawn by the water pump 113 and directed to the heat exchanger 114; the heat exchanger 114 transfers the high-temperature heat generated by the nuclear reactor to the cooling water, raising its temperature; the high-temperature cooling water enters the cooling tower 112, releasing heat through air cooling or other heat dissipation methods, lowering its temperature; the cooled cooling water then flows back into the safety-grade water tank 111, completing one cooling cycle. This ensures continuous circulation of cooling water and efficient heat dissipation, thereby maintaining the normal operation of the nuclear reactor.

[0048] The design of cooling tower 112 ensures effective heat dissipation of cooling water, reducing cooling water consumption and maintaining the system's cooling effect. Furthermore, heat exchanger 114 can be connected to the safety-grade water tanks 111 of any other series 110. If a tank in one series 110 fails, the tanks in other series 110 can provide a backup water source, thereby improving system redundancy and safety, and enhancing system flexibility and responsiveness. Through the coordinated operation of cooling tower 112, water pump 113, and heat exchanger 114, the system can efficiently circulate cooling water, ensuring that the cooling water temperature remains within a safe range. This not only improves the system's cooling efficiency but also reduces energy consumption, thus improving the system's economic efficiency.

[0049] Referring to Figure 1, in some embodiments, each series 110 further includes a first filter 115 and a second filter 116. The first filter 115 is disposed between the safety-grade water tank 111 and the water pump 113, and the second filter 116 is disposed between the water pump 113 and the heat exchanger 114. The first filter 115 is used to filter the cooling water drawn from the safety-grade water tank 111, removing impurities and suspended solids from the water, ensuring that the cooling water entering the water pump 113 is clean, and preventing the water pump 113 from becoming clogged or damaged. The second filter 116 is used to filter the cooling water delivered from the water pump 113 to the heat exchanger 114, further removing small particles and impurities from the water, ensuring that the cooling water entering the heat exchanger 114 is clean, preventing the heat exchanger 114 from becoming clogged and reducing heat exchange efficiency. By setting the first filter 115 and the second filter 116, the cleanliness of the cooling water is ensured, improving the reliability and heat exchange efficiency of the system. Clean cooling water can more effectively absorb the high-temperature heat generated by the nuclear reactor and quickly release the heat through the cooling tower 112, ensuring the cooling effect of the system. This avoids equipment damage caused by water quality issues and reduces maintenance costs, thereby improving the system's economy, environmental friendliness, and cooling efficiency, reducing energy consumption, and further enhancing the system's environmental performance.

[0050] In some embodiments, the nuclear power plant water system 100 further includes a wastewater discharge device. The cooling water stored in the safety-grade water tank 111 and the non-safety-grade water tank 120 can be fresh water or desalinated seawater. In some embodiments, the wastewater discharge device can be configured to discharge wastewater generated by the first filter 115, preventing the accumulation of contaminants from affecting the normal operation of the system. Alternatively, it can discharge wastewater generated by the second filter 116, ensuring the cleanliness of the cooling water entering the heat exchanger 114. Alternatively, it can discharge wastewater generated by the cooling tower 112, which may generate wastewater containing impurities during heat dissipation; this wastewater is discharged through the wastewater discharge device to prevent contamination of the cooling water system. In other embodiments, the wastewater discharge device can also be configured to treat and discharge wastewater generated by equipment such as the first filter 115, the second filter 116, and the cooling tower 112. By providing a wastewater discharge device, it is ensured that wastewater generated in the system can be discharged in a timely manner, preventing the accumulation of contaminants from affecting the normal operation of the system, thereby improving the reliability and cooling efficiency of the system.

[0051] In some embodiments, the heat exchangers 114 of each series 110 are configured to connect to the safety-grade water tanks 111 of any other series 110. Specifically, the heat exchangers 114 of each series 110 can connect not only to the safety-grade water tanks 111 of their own series 110, but also to the safety-grade water tanks 111 of any other series 110. This allows the safety-grade water tanks 111 of other series 110 to allocate cooling water to the faulty series 110 via the heat exchangers 114 when a problem occurs in the water tank of one series 110, ensuring its cooling needs are met, thereby improving system redundancy and safety. In some embodiments, the heat exchangers 114 of the faulty series 110 can be connected between the water pumps 113 and the heat exchangers 114 of other series 110. Preferably, the heat exchangers 114 of the faulty series 110 are connected between the second filter 116 and the heat exchangers 114 of other series 110.

[0052] Referring to Figure 1, in some embodiments, the nuclear power plant water system 100 further includes a first connecting pipe 160 and a plurality of first isolation valves 130. Each safety-level water tank 111 is connected via the first connecting pipe 160, and the first isolation valves 130 are disposed on the first connecting pipe 160 and configured to connect or disconnect two connected safety-level water tanks 111. Specifically, the first connecting pipe 160 connects each safety-level water tank 111, allowing each safety-level water tank 111 to be connected to each other in pairs. This ensures that if a problem occurs in a safety-level water tank 111 of one series 110, safety-level water tanks 111 of other series 110 can provide a backup water source, thereby improving system redundancy and safety. The first isolation valves 130 allow a safety-level water tank 111 to be isolated for repair or maintenance when needed, without affecting the normal operation of other series 110. By incorporating the first connecting pipe 160 and the first isolation valve 130, flexible allocation of cooling water is ensured, improving system reliability and maintenance convenience, extending system service life, and reducing system maintenance costs, thereby enhancing overall system performance. The design of the first connecting pipe 160 and the first isolation valve 130 also allows for flexible allocation of cooling water between different series 110, ensuring uniform distribution and efficient utilization of the cooling water.

[0053] Referring to Figure 1, in some embodiments, two first isolation valves 130 are provided between two connected safety-grade water tanks 111, namely a first valve and a second valve. The two connected safety-grade water tanks 111 are a first water tank and a second water tank. A non-safety-grade water tank 120 is connected to a first connecting pipe 160 between the first water tank and the second water tank. Thus, the non-safety-grade water tank 120 can replenish water to the first connecting pipe 160, and cooling water flows through the first connecting pipe 160 to the safety-grade water tank 111 connected to the first connecting pipe 160. The first valve is configured to connect or disconnect the first water tank and the non-safety-grade water tank 120. When the first water tank needs to replenish cooling water, the first valve can be opened to introduce cooling water from the non-safety-grade water tank 120 into the first water tank, ensuring the cooling water supply to the first water tank. The second valve is configured to connect or disconnect the second water tank and the non-safety-grade water tank 120. When the second water tank needs additional cooling water, the second valve can be opened to introduce cooling water from the non-safety-grade water tank 120 into the second water tank, ensuring a stable cooling water supply. This ensures flexible allocation of cooling water, improving system reliability and ease of maintenance. The design of the first and second valves allows for flexible allocation of cooling water between different series 110, ensuring uniform distribution and efficient utilization. This not only improves system cooling efficiency but also reduces system failures caused by insufficient cooling water, thereby enhancing system stability. Furthermore, if a safety-grade water tank 111 malfunctions, it can be isolated from other water tanks using the first and second valves, thus not affecting the cooling water supply to other series 110.

[0054] In some embodiments, the nuclear power plant water system 100 further includes a plurality of second connecting pipes 170, each safety-level water tank 111 being connected to at least one second connecting pipe 170, and each second connecting pipe 170 being connected to a non-safety-level water tank 120. Specifically, the second connecting pipes 170 are used to connect each safety-level water tank 111 and the non-safety-level water tank 120, ensuring that after the system has been operating under the second operating condition for 3 days, cooling water can be replenished from the non-safety-level water tank 120 to any safety-level water tank 111 through the second connecting pipes 170. By setting up the second connecting pipes 170, flexible allocation of cooling water is ensured, improving the reliability and emergency response capability of the system.

[0055] In some embodiments, the nuclear power plant water system 100 further includes a water replenishment device configured to replenish cooling water to the safety-grade water tank 111 operating under a first operating condition. Specifically, the water replenishment device is installed in the system to replenish cooling water to the safety-grade water tank 111 under the first operating condition. This design ensures that the water volume in the safety-grade water tank 111 can be replenished in a timely manner under low-load conditions, maintaining the normal operation of the system. For example, when the water volume in the safety-grade water tank 111 falls below a preset threshold, the water replenishment device automatically activates, drawing cooling water from an external water source and transporting it to the safety-grade water tank 111 through pipelines. This ensures a continuous supply of cooling water without depleting the water volume in the non-safety-grade water tank 120, improving the reliability and stability of the system. It should be noted that the system consumes very little cooling water under low-load conditions (i.e., the first operating condition), and the water replenishment device prevents a decrease in the water volume of the safety-grade water tank 111 from affecting the cooling of the system during the first three days of operation under the second operating condition. In some embodiments, the water replenishment device can also be configured with a manual activation function to allow for manual intervention in special circumstances, ensuring the normal operation of the system.

[0056] Referring to Figure 1, in some embodiments, the nuclear power plant water system 100 further includes a second isolation valve 140. The second isolation valve 140 is located between the non-safety-grade water tank 120 and the safety-grade water tank 111, and is used to control the connection or disconnection between the safety-grade water tank 111 and the non-safety-grade water tank 120. Specifically, when the water volume in the safety-grade water tank 111 is insufficient, cooling water from the non-safety-grade water tank 120 can be introduced into the safety-grade water tank 111 through the second isolation valve 140 to ensure a continuous supply of cooling water. When connection is not required, the non-safety-grade water tank 120 can be isolated from the safety-grade water tank 111 through the second isolation valve 140 for maintenance or repair. By setting the second isolation valve 140, flexible allocation of cooling water is ensured, improving the reliability and maintenance convenience of the system. In some embodiments, the second isolation valve 140 may be equipped with a sensor and a control system. When the control system detects that any series 110 is in a second operating condition, and that series 110 has been operating in this second operating condition for 3 days, the second isolation valve 140 automatically opens, introducing cooling water from the non-safety-grade water tank 120 into the safety-grade water tank 111. The design of the second isolation valve 140 allows for flexible allocation of cooling water under different operating conditions, ensuring uniform distribution and efficient utilization of cooling water, and reducing water waste.

[0057] Referring to Figure 1, in some embodiments, the nuclear power plant water system 100 further includes a makeup water pump 150, which is located between the non-safety-grade water tank 120 and the safety-grade water tank 111, and is configured to direct cooling water from the non-safety-grade water tank 120 to the safety-grade water tank 111. The makeup water pump 150 may also be located between connected safety-grade water tanks 111. By providing the makeup water pump 150, cooling water can be rapidly replenished when needed, improving system reliability and emergency response capabilities.

[0058] In some embodiments, the nuclear power plant water system 100 further includes a chemical dosing device configured to dispense chemicals into the safety-grade water tank 111. These chemicals include, but are not limited to, corrosion inhibitors, scale inhibitors, bactericides, and pH adjusters. Corrosion inhibitors include, but are not limited to, phosphates, nitrites, molybdates, chromates, hydrazine, and silicates. In some embodiments, the chemical dosing device is equipped with sensors and a control system. When water quality parameters (such as pH and dissolved oxygen) in the safety-grade water tank 111 are detected to exceed preset ranges, the chemical dosing device automatically activates and dispenses an appropriate amount of chemicals into the safety-grade water tank 111 to ensure water quality stability. By installing the chemical dosing device, it is ensured that necessary chemicals can be added to the safety-grade water tank 111 when needed to improve water quality, prevent corrosion and scaling, enhance system reliability and safety, and extend equipment lifespan.

[0059] In some embodiments, the nuclear power plant water system 100 includes multiple interconnected non-safety-grade water pools 120. Each non-safety-grade water pool 120 is configured to connect to each safety-grade water pool 111, and the total water volume stored in all non-safety-grade water pools 120 is sufficient to supply the system for at least 27 days of operation under the second operating condition. Specifically, the number of non-safety-grade water pools 120 is less than the number of safety-grade water pools 111, but the total water volume stored in all non-safety-grade water pools 120 is sufficient to supply the system for at least 27 days of operation under the second operating condition. This effectively reduces the overall water storage requirement, effectively avoids water resources being idle or even wasted, and lowers the construction and maintenance costs of the water pools. For example, the nuclear power plant water system 100 is equipped with two non-safety-grade water pools 120, which are interconnected. This prevents water supply from the non-safety-grade water pool 120 from failing to reach the safety-grade water pool 111 if the connection between the non-safety-grade water pool 120 and the safety-grade water pool 111 fails, thereby effectively improving the reliability and safety of the system. Specifically, setting up two (or more) non-safety-grade water pools 120 can disperse risks. Even if one non-safety-grade water pool 120 fails, the other one or more can continue to operate, ensuring the reliability of the system. Furthermore, when maintenance or cleaning of any of the non-safety-grade water pools 120 is required, the water stored in the non-safety-grade water pool 120 can be drained to other non-safety-grade water pools 120 without affecting the normal operation of the entire system.

[0060] Referring to Figure 2, a second aspect of this application also provides a cooling method applicable to the nuclear power plant water system 100 described in any of the above embodiments and implementations. The cooling method includes, but is not limited to, the following steps:

[0061] When any series 110 enters the second operating condition, for ease of description, the safety-level water tank 111 within that series 110 is defined as the emergency water tank. At least one other safety-level water tank 111 connected to the emergency water tank is controlled to replenish water to the emergency water tank. This ensures that when the water level in the emergency water tank is insufficient, cooling water can be quickly replenished from other safety-level water tanks 111, improving the system's reliability and emergency response capability. In some embodiments, multiple other safety-level water tanks 111 can be controlled simultaneously to replenish water to the emergency water tank, further improving replenishment efficiency and system stability.

[0062] After the emergency water pool has been in operation for 3 days, water is replenished to the emergency water pool from the non-safety-level water pool 120. This ensures a continuous supply of cooling water under prolonged high-load conditions, further improving the system's reliability and stability. Furthermore, since the non-safety-level water pool 120 stores enough water to sustain the system for at least 27 days under the second operating condition, combined with the water level maintained by the safety-level water pool 111 for 3 days under the second operating condition, the system complies with nuclear power safety regulations.

[0063] In some embodiments, the non-safety level water tank 120 is connected to the first connecting pipe 160. Therefore, when controlling the non-safety level water tank 120 to replenish water to the emergency water tank, the non-safety level water tank 120 can be controlled to replenish water to the first connecting pipe 160 connecting the non-safety level water tank 120 and the emergency water tank. By controlling the opening of the first valve or the second valve (the first valve is opened when the connection between the emergency water tank and other water tanks is controlled by the first valve, and similarly, the second valve is opened when the connection between the emergency water tank and other water tanks is controlled by the second valve), the cooling water in the non-safety level water tank 120 flows rapidly into the safety level water tank 111, so as to ensure the continuous supply of cooling water under long-term high-load conditions and improve the reliability and stability of the system.

[0064] In other embodiments, the non-safety level water tank 120 supplies water to the first connecting pipe 160 that connects the two safety level water tanks 111. Since the safety level water tanks 111 are connected to each other in pairs, water can be supplied to the emergency water tank through the interconnectivity of the safety level water tanks 111. In one embodiment, the heat exchanger 114, which belongs to the same series 110 as the emergency water tank, can obtain sufficient water to cool the emergency series 110 by connecting to the safety level water tanks 111 of other series 110.

[0065] In some other embodiments, the non-safety level water tank 120 is directly connected to the safety level water tank 111 via the second connecting pipe 170. Thus, after the accident water tank has been in operation for 3 days, the non-safety level water tank 120 can directly supply water to the accident water tank via the second connecting pipe 170 connected to the accident water tank.

[0066] Referring to Figure 3, in some embodiments, each series 110 includes a cooling tower 112, a water pump 113, and a heat exchanger 114. The heat exchanger 114 is located between the water pump 113 and the cooling tower 112, and the water pump 113 is connected to a safety-level water tank 111. For ease of description, the heat exchanger 114 connected to the emergency water tank is defined as the first heat exchanger 114. The cooling method further includes: when the emergency water tank cannot supply water to the first heat exchanger 114, controlling at least one other series 110's safety-level water tank 111 to supply water to the first heat exchanger 114. This ensures that the first heat exchanger 114 of the series 110 containing the emergency water tank can still operate normally when the water volume in the emergency water tank is insufficient or the emergency water tank fails, improving the system's reliability and emergency response capability.

[0067] In some embodiments, when a blockage occurs between the emergency water tank and the first heat exchanger 114 of its series 110, preventing the emergency water tank from supplying cooling water to the first heat exchanger 114, the first heat exchanger 114 is connected between the second filter 116 of any other series 110 and the heat exchanger 114, thereby enabling the safety-level water tanks 111 of other series 110 to supply water to the first heat exchanger 114. After passing through the first heat exchanger 114, the cooling water flows to the cooling tower 112 of the series 110 containing the emergency water tank. The cooling tower 112 treats the cooling water and discharges it back to the emergency water tank. The emergency water tank is connected to the safety-level water tanks 111 of other series 110 via a first connecting pipe 160. Therefore, in this configuration, during the first three days of operation under either the first or second operating condition, sufficient and effective use of cooling water can be ensured. In other embodiments, when the connection between the emergency water tank and the first heat exchanger 114, as well as the safety-level water tanks 111 of other series 110, fails, preventing the emergency water tank from supplying cooling water to the first heat exchanger 114, the first heat exchanger 114 is connected between the second filter 116 of any other series 110 and the heat exchanger 114. The cooling tower 112 of the series 110 containing the emergency water tank is connected to the safety-level water tanks 111 of any other series 110. Therefore, when the cooling water from the safety-level water tanks 111 of any other series 110 flows through the first heat exchanger 114 to the cooling tower 112 of the series 110 containing the first heat exchanger 114, the cooling tower 112 processes the water and discharges it to the safety-level water tanks 111 of any other series 110, thereby reducing the impact of the emergency water tank on the system and ensuring the stable operation of each series 110.

[0068] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0069] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or," "and / or," or "and / or" throughout the text implies three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where A and B are simultaneously satisfied. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0070] The above are merely preferred embodiments of this application and do not limit the scope of the patent application. Any equivalent structural transformations made based on the inventive concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of this application.

Claims

1. A water system for a nuclear power plant, characterized in that, include: Multiple series, each series is equipped with a safety-grade water tank, each safety-grade water tank is connected to each other in pairs, each series has a first operating condition and a second operating condition, the water consumption of the series in the first operating condition is less than the water consumption of the series in the second operating condition, and the total water volume carried by any two safety-grade water tanks is configured to be able to supply the system to operate for at least 3 days in the second operating condition; The non-safety-grade water tank is configured to store enough water for the system to operate under the second operating condition for at least 27 days. After the safety-grade water tank has been operating under the second operating condition for 3 days, the non-safety-grade water tank is connected to each of the safety-grade water tanks.

2. The nuclear power plant water system as described in claim 1, characterized in that, Each of the aforementioned series includes a cooling tower, a water pump, and a heat exchanger. The water pump is configured to connect to the safety-grade water tank and to direct the cooling water in the safety-grade water tank to the heat exchanger. The heat exchanger is configured to transfer the high-temperature heat generated by the nuclear reactor to the cooling water. After passing through the heat exchanger, the cooling water enters the cooling tower to release heat and then flows back into the safety-grade water tank.

3. The nuclear power plant water system as described in claim 2, characterized in that, Each of the series also includes a first filter and a second filter, wherein the first filter is disposed between the safety-grade water tank and the water pump, and the second filter is disposed between the water pump and the heat exchanger.

4. The nuclear power plant water system as described in claim 3, characterized in that, The nuclear power plant water system also includes a wastewater discharge device configured to discharge wastewater generated by the first filter; And / or, The sewage discharge device is configured to discharge the wastewater generated by the second filter; And / or, The wastewater discharge device is configured to discharge wastewater generated by the cooling tower.

5. The nuclear power plant water system as described in claim 2, characterized in that, The heat exchangers of each of the aforementioned series are configured to be connected to the safety-grade water tanks of any other of the aforementioned series.

6. The nuclear power plant water system as described in claim 1, characterized in that, The nuclear power plant water system also includes a first connecting pipe and a plurality of first isolation valves. Each of the safety-grade water pools is connected through the first connecting pipe. The first isolation valve is installed on the first connecting pipe and configured to enable two connected safety-grade water pools to be connected or isolated.

7. The nuclear power plant water system as described in claim 6, characterized in that, Two first isolation valves, namely a first valve and a second valve, are provided between two connected safety-grade water tanks. The two connected safety-grade water tanks are a first water tank and a second water tank. The non-safety-grade water tank is connected to the first connecting pipe between the first water tank and the second water tank. The first valve is configured to connect or disconnect the first water tank from the non-safety-grade water tank, and the second valve is configured to connect or disconnect the second water tank from the non-safety-grade water tank.

8. The nuclear power plant water system as described in claim 1, characterized in that, The nuclear power plant water system also includes multiple second connecting pipes, each of the safety-grade water tanks is connected to at least one second connecting pipe, and each second connecting pipe is connected to the non-safety-grade water tank.

9. The nuclear power plant water system as described in claim 1, characterized in that, The nuclear power plant water system also includes a second isolation valve, which is located between the non-safety level water tank and the safety level water tank, and is used to control the connection or isolation between the safety level water tank and the non-safety level water tank.

10. The nuclear power plant water system as described in claim 1, characterized in that, The nuclear power plant water system also includes a water replenishment device configured to replenish cooling water to the safety-grade pool operating under the first condition.

11. The nuclear power plant water system as described in claim 1, characterized in that, The nuclear power plant water system also includes a makeup water pump, which is located between the non-safety level water tank and the safety level water tank, and is configured to direct the cooling water from the non-safety level water tank to the safety level water tank. and / or The water replenishment pump is located between the connected safety-grade water tanks.

12. The nuclear power plant water system as described in claim 1, characterized in that, The nuclear power plant water system also includes a dosing device configured to dispense chemicals into the safety-grade pool.

13. A cooling method applicable to the nuclear power plant water system according to any one of claims 1-12, characterized in that, The cooling method includes: When any of the series enters the second working condition, the safety-level water tank in the series becomes an emergency water tank, and at least one other safety-level water tank connected to the emergency water tank is controlled to replenish water to the emergency water tank. After the accident water tank has been in operation for 3 days, the non-safety level water tank will be used to replenish the accident water tank.

14. The cooling method as described in claim 13, characterized in that, When controlling the replenishment of water from the non-safety-level water tank to the emergency water tank... The non-safety level water tank replenishes water to the second connecting pipe that connects the non-safety level water tank and the accident water tank; Alternatively, the non-safety-grade water tank may replenish water to the first connecting pipe that connects the two safety-grade water tanks.

15. The cooling method as described in claim 13, characterized in that, Each of the aforementioned series includes a cooling tower, a water pump, and a heat exchanger, wherein the heat exchanger is disposed between the water pump and the cooling tower, and the water pump is connected to the safety-grade water tank. The heat exchanger connected to the emergency water tank is a first heat exchanger. The cooling method further includes: When any of the series enters the second operating condition and the emergency water tank is unable to supply cooling water to the first heat exchanger, at least one of the safety-grade water tanks in another series is controlled to supply water to the first heat exchanger.

Images