Drainage method and system after refueling of CPR1000 nuclear power plant during overhaul

Abstract

This invention relates to a drainage method and system for CPR1000 nuclear power plants after overhaul and refueling, comprising: performing drainage preparation; upon receiving a drainage command, activating a first drainage path to drain the reactor pool; real-time monitoring of the reactor pool's water level changes and the drainage status of the first drainage path, and acquiring monitoring information of the reactor pool; determining whether the conditions for simultaneous drainage by two pumps are met based on the monitoring information of the reactor pool; if the conditions for simultaneous drainage by two pumps are met, activating a second drainage path to drain the reactor pool; real-time monitoring of the reactor pool's water level changes and acquiring real-time water level information of the reactor pool; determining whether the conditions for switching from two pumps to one pump drainage are met based on the real-time water level information of the reactor pool; if the conditions for switching from two pumps to one pump drainage are met, closing the first drainage path and maintaining the second drainage path to drain the reactor pool. This invention, by employing a dual drainage path during a stage with very large drainage volumes, can significantly reduce drainage time, significantly improve drainage efficiency, and effectively shorten the overhaul period.

Description

Technical Field

[0001] This invention relates to the technical field of nuclear power plant overhaul, and more specifically, to a drainage method and system for CPR1000 nuclear power plant after fuel loading during overhaul. Background Technology

[0002] During the overhaul of the CPR1000 nuclear power plant, after fuel loading, the traditional method for draining the reactor pools was as follows: first, a single PTR002PO pump was used to drain the reactor pools and component pools from 19.5m to 12.16m, and then a PTR005PO pump was used to completely empty the reactor pools and component pools. The process of draining the reactor pools and component pools from 19.5m to 12.16m involved a very large volume of water and was very time-consuming. Therefore, this drainage process severely affected subsequent reactor pool decontamination and reactor cover installation, reduced drainage efficiency, and delayed the overhaul schedule. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a drainage method and system after refueling during the overhaul of a CPR1000 nuclear power plant.

[0004] The technical solution adopted by this invention to solve its technical problem is: to construct a drainage method after refueling during a major overhaul of a CPR1000 nuclear power plant, comprising the following steps:

[0005] Perform drainage preparations;

[0006] Upon receiving the drainage command, the first drainage path is initiated to drain the pile.

[0007] Real-time monitoring of water level changes in the storage pool and drainage status of the first drainage path, and acquisition of monitoring information of the storage pool;

[0008] Determine whether the condition for simultaneous discharge of two pumps is met based on the monitoring information of the pile pool;

[0009] If the condition of simultaneous drainage by both pumps is met, the second drainage path is activated to drain the pile.

[0010] Real-time monitoring of water level changes in the reactor pool and acquisition of real-time water level information of the reactor pool;

[0011] Determine whether the conditions for switching from a dual-pump to a single-pump drainage are met based on the real-time water level information of the pile.

[0012] If the conditions for switching from dual-pump to single-pump drainage are met, then the first drainage path is closed, while the second drainage path continues to drain water from the pile.

[0013] In the drainage method following overhaul and refueling of the CPR1000 nuclear power plant described in this invention, the drainage preparation includes:

[0014] Before receiving a drainage command, the first drainage path and the second drainage path are set to drainage status.

[0015] In the drainage method after fuel loading during a CPR1000 nuclear power plant overhaul as described in this invention, the step of initiating a first drainage path to drain the reactor pool after receiving a drainage command includes:

[0016] Upon receiving a drainage command, the first drainage pump installed on the first drainage path is activated;

[0017] Open the first drain valve, which is located on the first drainage path and in the outlet direction of the first drainage pump.

[0018] Open the main drain valve located on the main drainage path.

[0019] In the drainage method after refueling during the overhaul of the CPR1000 nuclear power plant described in this invention, the monitoring information includes: the rate of change of the liquid level in the reactor pool and the real-time flow rate of the first drainage pump.

[0020] The step of determining whether the dual-pump simultaneous discharge condition is met based on the monitoring information of the pile includes:

[0021] Determine whether the rate of change of the liquid level in the pool is greater than a set rate;

[0022] If the rate of change of liquid level is greater than the set rate, then determine whether the real-time flow rate of the first drainage pump is greater than the set flow rate.

[0023] If the real-time flow rate of the first drainage pump is greater than the set flow rate, then the condition of simultaneous drainage by both pumps is met.

[0024] In the drainage method following overhaul and refueling of the CPR1000 nuclear power plant described in this invention, the method further includes:

[0025] Before determining that the conditions for simultaneous discharge by both pumps are met and starting the second drainage path, the following steps are performed:

[0026] The first drainage path is maintained to continuously drain water for a preset time period, and after the preset time period is reached, the second drainage path is activated to drain water from the pile.

[0027] In the drainage method following overhaul and refueling of the CPR1000 nuclear power plant described in this invention, the step of activating the second drainage path to drain the reactor pool includes:

[0028] Open the second drain valve located on the second drainage path;

[0029] After the second drain valve is opened, the second drain pump installed on the second drain path is turned on to start the second drain path to drain the pile.

[0030] In the drainage method after refueling during the overhaul of the CPR1000 nuclear power plant described in this invention, the real-time water level information includes: the real-time liquid level of the reactor pool;

[0031] The step of determining whether the conditions for switching from a dual-pump to a single-pump drainage are met based on the real-time water level information of the pump pool includes:

[0032] The real-time liquid level of the pool is compared with the set liquid level;

[0033] If the real-time liquid level of the pool is less than or equal to the set liquid level, it is determined that the condition for switching from dual pumps to single pump drainage is met.

[0034] The present invention also provides a drainage system after refueling during the overhaul of a CPR1000 nuclear power plant, comprising: a first drainage path, a second drainage path, a main drainage path, and a control cabinet;

[0035] The input port of the first drainage path is connected to the first drainage outlet of the storage tank, and the output port of the first drainage path is connected to the input port of the main drainage path. The input port of the second drainage path is connected to the second drainage outlet of the storage tank, and the output port of the second drainage path is connected to the input port of the main drainage path. The output port of the main drainage path is connected to a water storage tank. The control cabinet is used to perform the following operations on the first drainage path and the second drainage path:

[0036] Upon receiving the drainage command, the first drainage path is initiated to drain the pile.

[0037] Real-time monitoring of water level changes in the storage pool and drainage status of the first drainage path, and acquisition of monitoring information of the storage pool;

[0038] Determine whether the condition for simultaneous discharge of two pumps is met based on the monitoring information of the pile pool;

[0039] If the condition of simultaneous drainage by both pumps is met, the second drainage path is activated to drain the pile.

[0040] Real-time monitoring of water level changes in the reactor pool and acquisition of real-time water level information of the reactor pool;

[0041] Determine whether the conditions for switching from a dual-pump to a single-pump drainage are met based on the real-time water level information of the pile.

[0042] If the conditions for switching from dual-pump to single-pump drainage are met, then the first drainage path is closed, while the second drainage path continues to drain water from the pile.

[0043] In the drainage system after refueling during the overhaul of the CPR1000 nuclear power plant as described in this invention, the reactor pool includes: a reactor water pool and a component pool;

[0044] The first drain outlet of the reactor pool is located on the main pipe from which the coolant enters the reactor core, and the second drain outlet of the reactor pool is located at the bottom of the component pool.

[0045] In the drainage system after refueling during the CPR1000 nuclear power plant overhaul as described in this invention, the first drainage path includes: a first drainage pump and a first drainage valve; the second drainage path includes: a second drainage pump and a second drainage valve; and the total drainage path includes: a total drainage valve.

[0046] The inlet of the first drainage pump is connected to the first drain outlet through the first drainage pipeline, and the outlet of the first drainage pump is connected to the input of the main drainage pipeline through the second drainage pipeline. The first drainage valve is installed on the second drainage pipeline.

[0047] The inlet of the second drainage pump is connected to the second drain outlet through the third drainage pipeline, and the outlet of the second drainage pump is connected to the input of the main drainage pipeline through the fourth drainage pipeline. The second drainage valve is installed on the fourth drainage pipeline.

[0048] The output end of the main drain pipeline is connected to the water storage tank, and the main drain valve is installed on the main drain pipeline.

[0049] The drainage method and system for CPR1000 nuclear power plants after overhaul and refueling, implementing the present invention, has the following beneficial effects: It includes: performing drainage preparation; upon receiving a drainage command, activating a first drainage path to drain the reactor pool; real-time monitoring of the reactor pool's water level changes and the drainage status of the first drainage path, and obtaining monitoring information of the reactor pool; determining whether the conditions for simultaneous drainage by two pumps are met based on the reactor pool's monitoring information; if the conditions for simultaneous drainage by two pumps are met, activating a second drainage path to drain the reactor pool; real-time monitoring of the reactor pool's water level changes and obtaining real-time water level information of the reactor pool; determining whether the conditions for switching from two pumps to one pump drainage are met based on the real-time water level information of the reactor pool; if the conditions for switching from two pumps to one pump drainage are met, closing the first drainage path and maintaining the second drainage path to drain the reactor pool. By employing a dual drainage path during a stage with a very large drainage volume, the present invention can significantly reduce drainage time, significantly improve drainage efficiency, and effectively shorten the overhaul period. Attached Figure Description

[0050] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0051] Figure 1 This is a schematic flowchart of the drainage method after refueling during the overhaul of the CPR1000 nuclear power plant, provided in an embodiment of the present invention.

[0052] Figure 2 This is a partial structural schematic diagram of the drainage system after the overhaul and refueling of the CPR1000 nuclear power plant according to the present invention. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0054] refer to Figure 1 This invention provides a drainage method for the CPR1000 nuclear power plant after fuel loading during an overhaul. This drainage method can be applied to the drainage of reactor pools and component pools after fuel loading during an overhaul of the CPR1000 nuclear power plant.

[0055] Specifically, such as Figure 1 As shown, the drainage method after refueling during the overhaul of the CPR1000 nuclear power plant includes the following steps:

[0056] Step S101: Perform drainage preparation.

[0057] In this embodiment of the invention, performing drainage preparation includes: setting the first drainage path 10 and the second drainage path 20 to a drainage state before receiving a drainage instruction.

[0058] Specifically, in this step, after loading, to save time, the first drainage path 10 and the second drainage path 20 can be set to drainage mode in advance while the site is online. That is, the on-site operator can operate the drainage valves corresponding to the first drainage path 10 and the second drainage path 20 to set the drainage valves on the drainage pipelines to drainage mode, so that when drainage is possible, only the drainage pump needs to be started and the drainage valves opened to carry out drainage.

[0059] By setting the first drainage path 10 and the second drainage path 20 to drainage status in advance, the time spent on-site valve operation and back-and-forth travel during drainage can be reduced.

[0060] Step S102: After receiving the drainage command, start the first drainage path 10 to drain the pile pool.

[0061] In this embodiment of the invention, after receiving a drainage command, starting the first drainage path 10 to drain the pool includes: after receiving the drainage command, turning on the first drainage pump 12 installed on the first drainage path 10; turning on the first drainage valve 14 installed on the first drainage path 10 and located in the water outlet direction of the first drainage pump 12; and turning on the main drainage valve 31 installed on the main drainage path 30.

[0062] Specifically, after receiving a drainage command, the first drainage pump 12 can be activated by the corresponding button on the local control cabinet. After activating the first drainage pump 12, the first drainage valve 14 can be opened, thereby opening the first drainage path 10 and draining the pile through the first drainage path 10.

[0063] In this embodiment of the invention, the reactor pool includes a reactor water pool and a component pool. The reactor water pool and the component pool (i.e., the in-reactor component pool) are separated by a gate. When drainage is required, the gate between the reactor water pool and the component pool is removed before drainage, so that the reactor water pool and the component pool are connected as one unit.

[0064] Step S103: Monitor the water level changes in the storage pool and the drainage status of the first drainage path 10 in real time and obtain the monitoring information of the storage pool.

[0065] Optionally, in this embodiment of the invention, the monitoring information includes: the rate of change of liquid level in the pool and the real-time flow rate of the first drainage pump 12.

[0066] The rate of change of liquid level in the reactor pool is monitored using existing methods. For example, a liquid level sensor installed in the reactor pool can be used to monitor the liquid level in real time and output the corresponding liquid level monitoring signal to the control cabinet, which then calculates the rate of change of liquid level based on the liquid level monitoring signal.

[0067] The real-time flow rate of the first drainage pump 12 is monitored using existing methods. For example, it can be obtained in real time by a flow meter installed at the outlet of the first drainage pump 12 or in the direction of water flow.

[0068] Step S104: Determine whether the condition for simultaneous discharge of two pumps is met based on the monitoring information of the pile pool.

[0069] Optionally, in this embodiment of the invention, determining whether the dual-pump simultaneous discharge condition is met based on the monitoring information of the storage pool includes: determining whether the liquid level change rate of the storage pool is greater than a set rate; if the liquid level change rate is greater than the set rate, then determining whether the real-time flow rate of the first drainage pump 12 is greater than the set flow rate; if the real-time flow rate of the first drainage pump 12 is greater than the set flow rate, then determining that the dual-pump simultaneous discharge condition is met. The set rate and set flow rate can be adjusted and set according to actual engineering applications, and this invention does not impose specific limitations.

[0070] Step S105: If the condition of simultaneous drainage by two pumps is met, then the second drainage path 20 is started to drain the pool.

[0071] Furthermore, in this embodiment of the invention, before determining that the conditions for simultaneous discharge of two pumps are met and the second drainage path 20 is started, the following steps are performed: the first drainage path 10 is kept draining continuously for a preset time period, and after the preset time period is reached, the second drainage path 20 is started to drain the pile.

[0072] Specifically, after determining that the conditions for simultaneous drainage by both pumps are met, the first drainage pump 12 is kept running for a preset time period. After the preset time period is reached, the second drainage path 20 is then activated to drain the pool. The preset time period can be set to 3 to 10 minutes, preferably 5 minutes.

[0073] In this embodiment of the invention, activating the second drainage path 20 to drain the reactor pool includes: opening the second drainage valve 24 disposed on the second drainage path 20; after opening the second drainage valve 24, controlling the second drainage pump 22 disposed on the second drainage path 20 to open, thereby activating the second drainage path 20 to drain the reactor pool. When the second drainage path 20 is activated, both pumps simultaneously drain the reactor pool.

[0074] Specifically, after the dual-pump drainage conditions are met and the first drainage pump 12 has been running stably for a preset period of time, the second drainage valve 24 is opened first, and then the second drainage pump 22 is started via the local control cabinet. The second drainage pump 22 draws water from the bottom of the component pool, achieving simultaneous drainage by both pumps. Experimental verification shows that after starting the second drainage pump 22, the drainage flow rate can increase by approximately 90 m³ / s. 3 / h can significantly improve drainage efficiency and greatly shorten drainage time, increasing efficiency by nearly 30% or more, and shortening the time by about 1 hour or even more.

[0075] Step S106: Monitor the water level changes in the reactor pool in real time and obtain the real-time water level information of the reactor pool.

[0076] Optionally, in this embodiment of the invention, the real-time water level information includes: the real-time liquid level of the pool.

[0077] Similarly, the rate of change of the reactor pool level is monitored using existing methods. For example, the level can be monitored in real time by a level sensor installed in the reactor pool, and the corresponding level monitoring signal can be output. The real-time level of the reactor pool can be obtained through this level monitoring signal.

[0078] Step S107: Determine whether the conditions for switching from dual pumps to single pump drainage are met based on the real-time water level information of the pump pool.

[0079] In this embodiment of the invention, determining whether the conditions for switching from a dual-pump to a single-pump drainage are met based on the real-time water level information of the pump pool includes: comparing the real-time liquid level of the pump pool with a set liquid level; if the real-time liquid level of the pump pool is less than or equal to the set liquid level, then it is determined that the conditions for switching from a dual-pump to a single-pump drainage are met.

[0080] Optionally, in this embodiment of the invention, the liquid level can be set to 12.16m.

[0081] Step S108: If the conditions for switching from dual pumps to single pump drainage are met, then close the first drainage path 10 and keep the second drainage path 20 draining the pile.

[0082] Specifically, when the real-time liquid level in the reactor pool is less than or equal to 12.16m, the first drainage pump 12 stops, while the second drainage pump 22 continues to run, thereby continuing to drain the reactor pool through the second drainage path 20 until the water in the reactor pool is emptied. That is, when the water level in the reactor pool is less than or equal to 12.16m, the first drainage pump 12 is automatically controlled to stop running.

[0083] It should be noted that, to ensure the safe operation of the equipment, when the water level in the reservoir drops to 12.16m, the first drainage pump 12 will automatically stop, without requiring a pump stop control operation. In some embodiments, steps S107 and S108 can be omitted. That is, during the dual-pump drainage process after starting the second drainage path 20, the real-time water level information of the reservoir does not need to be monitored. As the water level in the reservoir drops, when it reaches 12.16m, since no water flows out of the first drainage outlet 111, the first drainage pump 12 will automatically stop because it cannot pump water, thus achieving the effect of automatic shutdown. At the same time, the start-stop control operation can be omitted.

[0084] By simultaneously draining water using the first drain pump 12 and the second drain pump 22 during the dual-pump drainage stage, drainage time can be significantly saved and drainage efficiency improved. Furthermore, below 12.16, drainage continues via the second drain pump 22, eliminating the need for additional start-stop operations and ensuring seamless operation.

[0085] refer to Figure 2 , Figure 2 This is a schematic diagram of some components of the drainage system after refueling during the overhaul of the CPR1000 nuclear power plant, provided by the present invention.

[0086] like Figure 2 As shown, the gate between the reactor pool and the in-core components pool is removed before drainage to facilitate the discharge of water from both pools.

[0087] Specifically, such as Figure 2As shown, the drainage system of the PR1000 nuclear power plant after overhaul and refueling includes: a first drainage path 10, a second drainage path 20, a main drainage path 30, and a control cabinet (the control cabinet is not located in...). Figure 2 (Not yet shown). The control cabinet can be installed on-site.

[0088] like Figure 2 As shown, the input port of the first drainage path 10 is connected to the first drainage port 111 of the reactor pool, and the output port of the first drainage path 10 is connected to the input port of the main drainage path 30. The input port of the second drainage path 20 is connected to the second drainage port 112 of the reactor pool, and the output port of the second drainage path 20 is connected to the input port of the main drainage path 30. The output port of the main drainage path 30 is connected to the water storage tank. The control cabinet is used to perform the following operations on the first drainage path 10 and the second drainage path 20:

[0089] Upon receiving the drainage command, the first drainage path 10 is activated to drain the pile pool.

[0090] Real-time monitoring of water level changes in the storage pool and drainage status of the first drainage path 10, and acquisition of monitoring information of the storage pool;

[0091] Determine whether the conditions for simultaneous discharge of two pumps are met based on the monitoring information of the pile pool;

[0092] If the conditions for simultaneous drainage by both pumps are met, then the second drainage path 20 will be activated to drain the sump.

[0093] Real-time monitoring of water level changes in the reactor pool and acquisition of real-time water level information;

[0094] Determine whether the conditions for switching from a dual-pump to a single-pump drainage system are met based on the real-time water level information of the pump pool.

[0095] If the conditions for switching from dual-pump to single-pump drainage are met, then the first drainage path 10 is closed, while the second drainage path 20 continues to drain the storage tank.

[0096] It should be noted that the drainage command is generated by relevant personnel triggering the corresponding operation button after the drainage preparation is completed and the drainage test is received.

[0097] like Figure 2 As shown, the first drain outlet 111 of the reactor pool is located on the main duct (RCP main duct) from which the coolant enters the reactor core, and the second drain outlet 112 of the reactor pool is located at the bottom of the component pool.

[0098] like Figure 2 As shown, the first drainage path 10 includes a first drainage pump 12 and a first drainage valve 14; the second drainage path 20 includes a second drainage pump 22 and a second drainage valve 24; and the main drainage path 30 includes a main drainage valve 31. Wherein, Figure 2PTR002PO is the first drain pump 12, PTR006VB is the first drain valve 14, PTR005PO is the second drain pump 22, PTR155VB is the second drain valve 24, PTR016VB is the main drain valve 31, and PTR001BA is the water storage tank.

[0099] Specifically, the inlet of the first drainage pump 12 is connected to the first drain outlet 111 via the first drainage pipeline 11, and the outlet of the first drainage pump 12 is connected to the input of the main drainage pipeline 32 via the second drainage pipeline 13. The first drainage valve 14 is installed on the second drainage pipeline 13. The inlet of the second drainage pump 22 is connected to the second drain outlet 112 via the third drainage pipeline 21, and the outlet of the second drainage pump 22 is connected to the input of the main drainage pipeline 32 via the fourth drainage pipeline 23. The second drainage valve 24 is installed on the fourth drainage pipeline 23. The output of the main drainage pipeline 32 is connected to the water storage tank, and the main drainage valve 31 is installed on the main drainage pipeline 32.

[0100] like Figure 2 As shown, upon receiving a drainage command, the first drainage pump 12 can be started via the corresponding button on the control cabinet (or the control cabinet can directly output a start signal to control the first drainage pump 12 to start based on the drainage command). Then, the first drainage valve 14 is opened, and the reactor pool is drained through the first drainage path 10. When the first drainage pump 12 is running stably (i.e., the rate of change of the reactor pool level and the real-time flow rate of the first drainage pump 12 meet the conditions), the first drainage pump 12 is controlled to continue running for a preset time period. Then, the second drainage valve 24 is opened to open the second drainage path 20. The second drainage pump 22 is then started via the control cabinet to draw water from the bottom of the reactor internals pool, so that both drainage pumps can drain water simultaneously. When the real-time liquid level in the reactor pool drops from full (19.56m) to 12.16m, the first drainage pump 12 automatically stops. At this time, only the second drainage pump 22 needs to continue draining water until the water in the pool is emptied.

[0101] It should be noted that the specific coordination and operation process between the components in the drainage system after the overhaul and refueling of the CPR1000 nuclear power plant disclosed in this embodiment of the invention can be referred to the drainage method after the overhaul and refueling of the CPR1000 nuclear power plant described above, and will not be repeated here.

[0102] This invention significantly improves drainage efficiency (by nearly 30% or more) by employing dual pumps for simultaneous drainage. Simultaneously, this process optimizes on-site operations (by pre-setting the PTR005PO drainage status), resulting in substantial operational burden reduction and further minimizing path time. Furthermore, this invention can be adopted for all subsequent overhauls and other nuclear power units to optimize processes, saving overhaul time and reducing production costs.

[0103] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0104] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0105] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0106] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They do not limit the scope of protection of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for draining water after refueling during a major overhaul of a CPR1000 nuclear power plant, characterized in that, Includes the following steps: Perform drainage preparations; Upon receiving the drainage command, the first drainage path is activated to drain the pile. The system monitors the water level changes in the storage pool and the drainage status of the first drainage path in real time and obtains monitoring information about the storage pool. The monitoring information includes the rate of change of the liquid level in the storage pool and the real-time flow rate of the first drainage pump. The condition for simultaneous discharge of two pumps is determined based on the monitoring information of the pool. The determination of whether the condition for simultaneous discharge of two pumps is met based on the monitoring information of the pool includes: determining whether the liquid level change rate of the pool is greater than a set rate; if the liquid level change rate is greater than the set rate, then determining whether the real-time flow rate of the first drainage pump is greater than the set flow rate; if the real-time flow rate of the first drainage pump is greater than the set flow rate, then determining that the condition for simultaneous discharge of two pumps is met. If the condition of simultaneous drainage by both pumps is met, the second drainage path is activated to drain the pile. The system monitors the water level changes in the reactor pool in real time and obtains the real-time water level information of the reactor pool; the real-time water level information includes: the real-time liquid level of the reactor pool; Determine whether the conditions for switching from dual pumps to single pump drainage are met based on the real-time water level information of the pile pool; the determination of whether the conditions for switching from dual pumps to single pump drainage are met based on the real-time water level information of the pile pool includes: comparing the real-time liquid level of the pile pool with a set liquid level; if the real-time liquid level of the pile pool is less than or equal to the set liquid level, it is determined that the conditions for switching from dual pumps to single pump drainage are met. If the conditions for switching from dual-pump to single-pump drainage are met, then the first drainage path is closed, while the second drainage path continues to drain water from the pile.

2. The drainage method after refueling during a major overhaul of a CPR1000 nuclear power plant according to claim 1, characterized in that, The drainage preparation includes: Before receiving a drainage command, the first drainage path and the second drainage path are set to drainage status.

3. The drainage method after refueling during a major overhaul of a CPR1000 nuclear power plant according to claim 1, characterized in that, The step of initiating the first drainage path to drain the pile after receiving the drainage command includes: Upon receiving a drainage command, the first drainage pump installed on the first drainage path is activated; Open the first drain valve, which is located on the first drainage path and in the outlet direction of the first drainage pump. Open the main drain valve located on the main drainage path.

4. The drainage method after refueling during a major overhaul of a CPR1000 nuclear power plant according to claim 1, characterized in that, The method further includes: Before determining that the conditions for simultaneous discharge by both pumps are met and starting the second drainage path, the following steps are performed: The first drainage path is maintained to continuously drain water for a preset time period, and after the preset time period is reached, the second drainage path is activated to drain water from the pile.

5. The drainage method after refueling during a major overhaul of a CPR1000 nuclear power plant according to claim 1, characterized in that, The step of activating the second drainage path to drain the pile includes: Open the second drain valve located on the second drainage path; After the second drain valve is opened, the second drain pump installed on the second drain path is turned on to start the second drain path to drain the pile.

6. A drainage system after refueling during a major overhaul of a CPR1000 nuclear power plant, characterized in that, include: First drainage path, second drainage path, main drainage path and control cabinet; The input port of the first drainage path is connected to the first drainage outlet of the storage tank, and the output port of the first drainage path is connected to the input port of the main drainage path. The input port of the second drainage path is connected to the second drainage outlet of the storage tank, and the output port of the second drainage path is connected to the input port of the main drainage path. The output port of the main drainage path is connected to a water storage tank. The control cabinet is used to perform the following operations on the first drainage path and the second drainage path: Upon receiving the drainage command, the first drainage path is activated to drain the pile. The system monitors the water level changes in the storage pool and the drainage status of the first drainage path in real time and obtains monitoring information about the storage pool. The monitoring information includes the rate of change of the liquid level in the storage pool and the real-time flow rate of the first drainage pump. The condition for simultaneous discharge of two pumps is determined based on the monitoring information of the pool. The determination of whether the condition for simultaneous discharge of two pumps is met based on the monitoring information of the pool includes: determining whether the liquid level change rate of the pool is greater than a set rate; if the liquid level change rate is greater than the set rate, then determining whether the real-time flow rate of the first drainage pump is greater than the set flow rate; if the real-time flow rate of the first drainage pump is greater than the set flow rate, then determining that the condition for simultaneous discharge of two pumps is met. If the condition of simultaneous drainage by both pumps is met, the second drainage path is activated to drain the pile. The system monitors the water level changes in the reactor pool in real time and obtains the real-time water level information of the reactor pool; the real-time water level information includes: the real-time liquid level of the reactor pool; Determine whether the conditions for switching from dual pumps to single pump drainage are met based on the real-time water level information of the pile pool; the determination of whether the conditions for switching from dual pumps to single pump drainage are met based on the real-time water level information of the pile pool includes: comparing the real-time liquid level of the pile pool with a set liquid level; if the real-time liquid level of the pile pool is less than or equal to the set liquid level, it is determined that the conditions for switching from dual pumps to single pump drainage are met. If the conditions for switching from dual-pump to single-pump drainage are met, then the first drainage path is closed, while the second drainage path continues to drain water from the pile.

7. The drainage system after refueling during the overhaul of the CPR1000 nuclear power plant according to claim 6, characterized in that, The reactor pool includes: a reactor water pool and a component pool; The first drain outlet of the reactor pool is located on the main pipe from which the coolant enters the reactor core, and the second drain outlet of the reactor pool is located at the bottom of the component pool.

8. The drainage system after refueling during the overhaul of the CPR1000 nuclear power plant according to claim 7, characterized in that, The first drainage path includes: a first drainage pump and a first drainage valve; the second drainage path includes: a second drainage pump and a second drainage valve; the main drainage path includes: a main drainage valve; The inlet of the first drainage pump is connected to the first drain outlet through the first drainage pipeline, and the outlet of the first drainage pump is connected to the input of the main drainage pipeline through the second drainage pipeline. The first drainage valve is installed on the second drainage pipeline. The inlet of the second drainage pump is connected to the second drain outlet through the third drainage pipeline, and the outlet of the second drainage pump is connected to the input of the main drainage pipeline through the fourth drainage pipeline. The second drainage valve is installed on the fourth drainage pipeline. The output end of the main drain pipeline is connected to the water storage tank, and the main drain valve is installed on the main drain pipeline.

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