A hot spot flushing method and electronic equipment for a nuclear power unit primary circuit system

Abstract

The present invention relates to a method and electronic equipment for hot spot flushing of a nuclear power plant's primary circuit system. The method comprises: generating node models of the nuclear power plant's primary circuit system, residual heat removal system, medium-pressure safety injection system, reactor pool, and reactor core based on a preset estimation model; generating input cards corresponding to the nodes based on the node models; setting the node models to initial operating conditions of the nuclear power plant; setting flow parameters of flow passages within the reactor core and residual heat removal system in the node models to rated values ​​to obtain corresponding resistance coefficient parameters; determining a target circuit and generating several different safety injection modes based on the node models, respectively obtaining the pressure and flow rate corresponding to the target circuit under each safety injection mode; and selecting the safety injection mode that maximizes the pressure and flow rate corresponding to the target circuit as the hot spot flushing method for the target circuit. Implementation of the present invention enables the most reliable hot spot flushing method to be obtained based on rigorous quantitative analysis.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power technology, and more particularly to a hot spot flushing method for a primary circuit system of a nuclear power unit and electronic equipment. Background Art

[0002] Corrosion products in the primary circuit of a pressurized water reactor migrate with the coolant and activate in the highly irradiated areas of the core. These activated corrosion products, carried by the coolant, are deposited in non-irradiated areas, forming radiation fields, posing a serious radiation hazard to power plant maintenance and operating personnel. Deposition hotspots, a flow-accelerated deposition phenomenon, often occur in fluid-constrained areas such as pipe reducers and valves. These deposits manifest as large accumulations of localized deposits. Because these deposits contain large amounts of activated corrosion products, these deposits directly lead to increased local radioactivity, forming radioactive hotspots.

[0003] The presence of radioactive hotspots poses a radiation risk to operators during nuclear power plant overhauls. Therefore, flushing of radioactive hotspots is necessary. However, in practice, the selection of flushing methods is largely based on experience, and reliability cannot be guaranteed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and electronic equipment for flushing hot spots in the primary circuit system of a nuclear power unit in response to some of the above technical defects in the prior art.

[0005] The technical solution adopted by the present invention to solve the technical problem is to construct a hot spot flushing method for the primary circuit system of a nuclear power unit, the method comprising:

[0006] S1. Based on a preset estimation model, generate node models of the primary circuit system, residual heat removal system, medium-pressure safety injection system, reactor pool, and reactor core in the nuclear power unit, wherein the primary circuit system includes a first loop, a second loop, and a third loop; the medium-pressure safety injection system includes a first medium-pressure safety injection tank corresponding to the first loop, a second medium-pressure safety injection tank corresponding to the second loop, and a third medium-pressure safety injection tank corresponding to the third loop;

[0007] S2. Generate an input card corresponding to a node according to the node model, wherein the input card includes node parameters corresponding to the node in the node model;

[0008] S3, setting the node model to correspond to the initial operating condition of the nuclear power unit, and setting the water level parameter of the reactor pool of the nuclear power unit in the node model to a preset value;

[0009] S4. Setting the flow parameters of the flow channel in the reactor core in the node model to rated values, and adjusting the resistance coefficient parameters of the nuclear power unit in the node model so that the pressure difference values ​​of the nodes in the node model are respectively corresponding to the target values;

[0010] S6. Determine a target loop based on the hotspot location of the unit to be flushed, and generate several different safety injection modes corresponding to the target loop based on a combination of the first medium-pressure safety injection box, the second medium-pressure safety injection box, and the third medium-pressure safety injection box. Generate the safety injection modes respectively according to the node model, and obtain the pressure and flow rate corresponding to the target loop under each safety injection mode, wherein the target loop is any one of the first loop, the second loop, and the third loop.

[0011] S7. Selecting a safe injection mode when the pressure and flow rate corresponding to the hot spot position of the unit in the target loop are both at their maximum values, and using the safe injection mode as the hot spot flushing method corresponding to the target loop.

[0012] Preferably, in the hot spot flushing method for the primary circuit system of a nuclear power unit according to the present invention, in step S1, generating a node model including the primary circuit system, the residual heat removal system, the medium-pressure injection system, the reactor pool, and the reactor core in the nuclear power unit based on a preset estimation model includes:

[0013] Based on the light water reactor best estimate model RELAP, the primary system, residual heat removal system, medium pressure injection system, reactor pool and reactor core of the pressurized water reactor unit are integrally modeled to obtain the node model.

[0014] Preferably, in the hot spot flushing method of the primary circuit system of a nuclear power unit according to the present invention, in step S2,

[0015] When the node of the node model corresponds to a flow component, the node parameters include one or more of the flow area, length, inclination angle, height change, wall roughness, hydraulic diameter, resistance coefficient during forward flow and reverse flow, initial flow rate, and flow velocity of the flow component;

[0016] When a node in the node model corresponds to a thermal component, the node parameters include the material of the thermal component and one or more of its thermal conductivity and volumetric heat capacity, heat transfer area, source term, and heat sink.

[0017] Preferably, in the hot spot flushing method of the primary circuit system of a nuclear power unit according to the present invention, in step S3, setting the node model to correspond to the initial operating condition of the nuclear power unit includes:

[0018] The node model is set to correspond to the nuclear power unit operating in a single-loop open condition with a single RRA pump.

[0019] Preferably, in the hot spot flushing method for the primary circuit system of a nuclear power unit according to the present invention, in step S4, setting the flow parameter of the flow channel in the reactor core in the node model to a first rated value includes:

[0020] The rated flow rate of the reactor at zero power is calculated based on the node model, and the rated flow rate is used as the first rated value of the flow parameter of the flow channel in the reactor core in the node model.

[0021] Preferably, in the hot spot flushing method for the primary circuit system of a nuclear power plant according to the present invention, in step S6, determining the target circuit and generating a plurality of different injection modes corresponding to the target circuit based on the combination of the first medium-pressure injection tank, the second medium-pressure injection tank and the third medium-pressure injection tank include:

[0022] A mode in which the medium-pressure safety injection tank corresponding to the target loop among the first medium-pressure safety injection tank, the second medium-pressure safety injection tank and the third medium-pressure safety injection tank is independently injected is referred to as a first safety injection mode;

[0023] A mode in which the medium-pressure safety injection tanks other than the medium-pressure safety injection tank corresponding to the target loop among the first medium-pressure safety injection tank, the second medium-pressure safety injection tank and the third medium-pressure safety injection tank are simultaneously injected is referred to as a second injection mode;

[0024] The mode in which the first medium-pressure safety injection tank, the second medium-pressure safety injection tank and the third medium-pressure safety injection tank are simultaneously injected is the third injection mode.

[0025] Preferably, in the hot spot flushing method of the primary circuit system of a nuclear power unit according to the present invention, the method further comprises:

[0026] The compressed air pressure parameters corresponding to the first medium-pressure safety injection tank, the second medium-pressure safety injection tank and the third medium-pressure safety injection tank are set respectively.

[0027] Preferably, in the hot spot flushing method of the primary circuit system of a nuclear power unit according to the present invention, in step S7, the compressed air pressure parameters corresponding to the first medium-pressure safety injection tank, the second medium-pressure safety injection tank and the third medium-pressure safety injection tank are set according to the following formulas respectively;

[0028]

[0029] Among them, P1 is the set value of the compressed air pressure at the top of the injection tank, V1 is the gas phase volume corresponding to the highest liquid level of the injection tank, V2 is the gas phase volume corresponding to the lowest liquid level of the injection tank, and P2 is the atmospheric pressure after the injection tank is connected to the primary circuit system.

[0030] Preferably, in the hot spot flushing method of the primary circuit system of a nuclear power unit according to the present invention, in step S6, obtaining the pressure and flow rate corresponding to the target circuit in each injection mode includes:

[0031] A target pipe section or device in the target loop is selected, and the pressure and flow rate corresponding to the target pipe section or device are used as the pressure and flow rate corresponding to the target loop.

[0032] In another embodiment of the present invention, an electronic device is provided, comprising a memory and a processor;

[0033] The memory is used to store computer programs;

[0034] The processor is configured to execute the computer program to implement the method described above.

[0035] The hot spot flushing method and electronic equipment for a primary circuit system of a nuclear power unit implemented in the present invention have the following beneficial effects: based on rigorous quantitative analysis, the most reliable hot spot flushing method is obtained to ensure the safety of nuclear power unit workers. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0037] Figure 1 This is a flowchart of an embodiment of a method for flushing hot spots in a primary circuit system of a nuclear power unit according to the present invention;

[0038] Figure 2 yes Figure 1 A schematic diagram of the partial structure of an embodiment of a medium-medium pressure injection system;

[0039] Figure 3 yes Figure 1 Schematic diagram of the structure of the mid-node model. DETAILED DESCRIPTION

[0040] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0041] like Figure 1 FIG. 1 shows an embodiment of a method for flushing hot spots in a primary circuit system of a nuclear power plant according to the present invention. Figure 1In an embodiment of a hot spot flushing method for a primary circuit system of a nuclear power plant of the present invention, the method specifically includes: S1, based on a preset estimation model, generating a node model of a primary circuit system, a residual heat removal system, a medium-pressure safety injection system, a reactor water pool and a reactor core in a nuclear power plant, wherein the primary circuit system includes a first loop, a second loop and a third loop, and the medium-pressure safety injection system includes a first medium-pressure safety injection tank corresponding to the first loop, a second medium-pressure safety injection tank corresponding to the second loop and a third medium-pressure safety injection tank corresponding to the third loop; S2, generating an input card corresponding to a node according to the node model, wherein the input card includes a node parameter corresponding to the node in the node model; S3, setting the node model to correspond to the initial operating condition of the nuclear power plant, and setting the water level parameter of the reactor water pool of the nuclear power plant in the node model to a preset value; S4, setting The flow parameters of the flow channel in the reactor core in the node model are rated values, and the resistance coefficient parameters of the nuclear power unit in the node model are adjusted so that the pressure difference values ​​of each node in the node model are corresponding target values; S5, determine the target loop according to the hot spot position of the unit to be flushed, and generate several different injection modes corresponding to the target loop based on the combination of the first medium-pressure injection box, the second medium-pressure injection box and the third medium-pressure injection box, generate the injection modes respectively according to the node model, and obtain the pressure and flow rate corresponding to the target loop under each injection mode respectively, wherein the target loop is any one of the first loop, the second loop and the third loop; S6, select the injection mode when the pressure and flow rate corresponding to the hot spot position of the unit in the target loop are both maximum, and use the injection mode as the hot spot flushing method corresponding to the target loop.

[0042] Based on step S1 above, a node model for the primary circuit system, residual heat removal system, medium-pressure injection system, reactor pool, and reactor core of a nuclear power unit can be established using a commonly used best-estimation procedure in the nuclear power field. The specific node model establishment process includes, but is not limited to, generating a number of nodes based on the purpose of each device or component in the nuclear power unit and the connection relationships between the devices or components, and then connecting the connections between the nodes based on the actual connection relationships. The node configuration can be implemented as a single component or a collection of components as needed. For example, a single component can be assigned to a node in the node model, or a functional module containing multiple single components can be assigned to a node in the node model. In one specific embodiment, the primary circuit system includes three loops, defined as a first loop, a second loop, and a third loop. Each loop can include a pressure vessel, a hot pipe section, a steam generator, a pressurizer, a steam generator primary section, valves, a main pump, and a cold pipe section. Each loop is equipped with a corresponding medium-pressure injection tank to implement the medium-pressure injection operating conditions of the corresponding loop. The first medium-pressure injection tank corresponds to the first loop, the second medium-pressure injection tank corresponds to the second loop, and the third medium-pressure injection tank corresponds to the third loop. All medium-pressure injection tanks and their corresponding peripheral equipment constitute the medium-pressure injection system in the nuclear power unit.

[0043] Optionally, in step S1, generating a node model encompassing the primary circuit, reactor pool, and reactor core of a nuclear power unit based on a preset estimation model includes: comprehensively modeling the primary circuit system, intermediate-pressure safety injection system, residual heat removal system, reactor pool, and reactor core of the pressurized water reactor unit based on the light water reactor optimal estimation model (RELAP) to obtain the node model. Specifically, the node model is established using the light water reactor optimal estimation model (RELAP), a commonly used light water reactor optimal estimation model in the nuclear power field. The specific modeling process includes, but is not limited to, comprehensively modeling the primary circuit system (reactor, steam generator, main pump, etc.), residual heat removal system, intermediate-pressure safety injection tank and corresponding pipelines, reactor pool and reactor core, and refueling water tank of the pressurized water reactor unit.

[0044] like Figure 2 As shown in the figure, taking the primary circuit system of a specific nuclear power unit as an example, in a pressurized water reactor nuclear power unit, the medium-pressure injection system is mainly composed of three injection boxes (RIS001BA, RIS002BA, RIS003BA) and their corresponding peripheral equipment. The three injection boxes are respectively connected to the cold pipe sections of the three loops (LOOP1, LOOP2, LOOP3) of the reactor coolant system RCP to realize the medium-pressure injection working conditions of the corresponding loops. Figure 3The figure shows a functional module diagram for a nuclear power unit, with corresponding node numbers generated for each component. Specifically, the reactor pool node is set based on the unit's reactor pool dimensions and capacity. The residual heat removal system pump and heat exchanger nodes are set based on the dimensions of the unit's residual heat removal system. The intermediate pressure injection tank #1, #2, and #3 nodes, as well as the refueling tank nodes, are set based on the dimensions and capacity of the unit's intermediate pressure injection tank and refueling tank. The reactor core includes the active area and associated components. For example, each heat pipe segment is segmented into components, and node numbers are generated for each component or connection relationship. This is not limited in this embodiment. For example, different node numbers 235, 335, and 435 are generated for the main pumps in different loops. This is just an example. In another embodiment, nodes can also be text information. Among them, the injection box #1 can correspond to the injection box RIS001BA, the first loop corresponds to LOOP1, the injection box #2 can correspond to the injection box RIS002BA, the second loop corresponds to LOOP2, the injection box #3 corresponds to the injection box RIS003BA, and the third loop corresponds to LOOP3.

[0045] Based on step S2, corresponding input cards are generated for some or all of the nodes in the node model. These input cards define the corresponding functional modules of the software program. During the operation of the node model, the software program calls each functional module as needed, enabling the node model to implement its corresponding functions. In this embodiment, input cards are used to set the node parameters corresponding to each node in the node model. When performing calculations based on the node model, the input cards are called as needed to obtain the corresponding operating parameters.

[0046] In step S3, the node model state is set to correspond to the initial operating condition of the nuclear power unit. This initial operating condition refers to the condition before the nuclear power unit is filled with water. The choice of operating condition can be the same or different depending on the operating scenario. Furthermore, the reactor pool water level parameters in the node model are set based on the actual water level in the reactor pool. For example, in the initial calculation condition, the reactor pool water level is at the full level (19.5 meters), and an RRA pump is used to drain the pool to the refueling tank.

[0047] Based on step S4, the flow parameters corresponding to the flow channels in the reactor core in the node model are set to rated values ​​and remain unchanged. By adjusting the resistance coefficient parameters of the reactor core in the node model, it is confirmed during the adjustment process whether the pressure difference values ​​of each node in the reactor core meet the requirements, for example, whether they are within the preset requirement range, and the adjustment is stopped when the pressure difference values ​​are within the preset requirement range.

[0048] Based on step S5, the flow parameters corresponding to the flow channels in the waste heat removal system in the node model are set to rated values ​​and remain unchanged. By adjusting the resistance coefficient parameters of the waste heat removal system in the node model, it is confirmed during the adjustment process whether the pressure difference values ​​of each node in the waste heat removal system meet the requirements, for example, whether they are within the preset requirement range, and the adjustment is stopped when the pressure difference values ​​are within the preset requirement range.

[0049] Based on steps S6 and S7, a target loop is selected from the first, second, and third loops as needed. For example, a target loop is selected from the three loops based on the location of the hotspot of the unit to be flushed. After obtaining the target loop, the first, second, and third medium-pressure safety injection tanks are combined to enable one or more of them to enter the safety injection mode. The corresponding safety injection mode is generated using the node model, and the pressure and flow rate corresponding to the target loop under each safety injection mode are obtained. The safety injection mode with the highest pressure and flow rate is selected as the optimal hotspot flushing method for the target loop.

[0050] Based on the above process, during a nuclear power unit overhaul shutdown or complete unloading mode, water injection can be used to alter the flow and pressure fields within the primary circuit, allowing deposited hot spots to re-enter the primary coolant and ultimately achieve cleanup. The intermediate-pressure (IP) injection tank contains a certain concentration of boron-containing water, which is covered by gas from above. When the RCP pressure drops below the injection tank pressure, the gas from above injects the boron-containing water into the RCP cold section. During complete unloading mode with the unit down, compressed air is injected from above to force coolant from the IP injection tank into the primary circuit. The higher pressure and flow displace activated corrosion products deposited on primary circuit piping and equipment, effectively removing hot spots. Taking into account the actual differences between individual IP injection tanks and individual circuits, selecting the highest pressure and flow rate achieves the highest efficiency in removing hot spots within the target circuit.

[0051] Optionally, in step S2, when generating input cards corresponding to nodes, when the nodes of the node model correspond to flow components, the node parameters include one or more of the flow area, length, inclination angle, height change, wall roughness, hydraulic diameter, resistance coefficient during forward and reverse flow, initial flow rate, and flow velocity of the flow component; when the nodes in the node model correspond to thermal components, the node parameters include one or more of the material of the thermal component and its thermal conductivity and volumetric heat capacity, heat transfer area, source term, and heat sink. Specifically, the input cards in the node model are set based on the design parameters and operating parameters of the system and equipment in the nuclear power unit. The design parameters and operating parameters of the system and equipment can be refined to specific components or assemblies, and different parameters can be selected as design input cards based on the type or function of the component or assembly.

[0052] Optionally, in step S3, setting the node model to correspond to the initial operating condition of the nuclear power unit includes setting the node model to correspond to the nuclear power unit operating in an open-loop primary circuit condition with a single RRA pump. Specifically, during calculation based on the node model, the initial state of the node model is first set to correspond to the nuclear power unit operating in an open-loop primary circuit condition with a single RRA pump, and subsequent parameter settings are performed under this operating condition.

[0053] Optionally, in step S4, setting the flow parameter of the flow channel in the reactor core in the node model to a rated value includes: calculating the rated flow at zero power of the reactor based on the node model, and taking the rated flow as the first rated value of the flow parameter of the flow channel in the reactor core in the node model. Specifically, in actual applications, the resistance coefficient of the flow channel in the reactor core has a greater influence on the final calculation result of the node model. Therefore, it is necessary to adopt a method with higher accuracy to calculate the resistance coefficient. During the calculation process, the rated flow at zero power of the reactor is calculated by using the established node model, and the rated flow is used as the first rated value of the flow parameter of the flow channel in the reactor core in the node model.

[0054] Optionally, in step S6, the target loop is determined based on the hotspot location of the unit to be flushed, and several different injection modes corresponding to the target loop are generated based on the combination of the first, second, and third medium-pressure safety injection tanks, including: a first injection mode in which the medium-pressure safety injection tank corresponding to the target loop among the first, second, and third medium-pressure safety injection tanks is injected alone; a second injection mode in which the medium-pressure safety injection tanks other than the medium-pressure safety injection tank corresponding to the target loop among the first, second, and third medium-pressure safety injection tanks are injected simultaneously; and a third injection mode in which the first, second, and third medium-pressure safety injection tanks are injected simultaneously. Specifically, after the target loop is selected, such as after the second loop is selected, a first injection mode in which only the second medium-pressure safety injection tank is injected can be generated through the node model, and the corresponding pressure and flow in the second loop can be obtained. The node model was used to generate a second injection pattern in which the first and third medium-pressure injection tanks were simultaneously activated, and the corresponding pressure and flow in the second loop were obtained. A third injection pattern was also generated in which the first, second, and third medium-pressure injection tanks were simultaneously activated, and the corresponding pressure and flow in the second loop were obtained. The injection pattern with the highest pressure and flow was used to perform hotspot flushing for the injection pattern required for the current nuclear power unit.

[0055] In one embodiment, the hot spot flushing method for the primary circuit system of a nuclear power plant of the present invention further includes setting the compressed air pressure parameters corresponding to the first, second, and third medium-pressure injection tanks. During the filling process of the medium-pressure injection tanks, as the liquid level decreases, the upper compressed air will expand. This process can be regarded as the expansion process of an ideal gas, so it is necessary to set the compressed air pressure parameters in each medium-pressure injection tank. The upper compressed air pressure setting value P1 of the injection tank can be determined by the following formula:

[0056] ,

[0057] In this formula, V1 is the gas phase volume corresponding to the highest liquid level of the injection tank, V2 is the gas phase volume corresponding to the lowest liquid level of the injection tank, and P2 is conservatively selected as the atmospheric pressure after connecting to the primary circuit.

[0058] In one embodiment, in step S6, the obtaining of the pressure and flow rate corresponding to the target loop in each injection mode includes: selecting a target pipe section or equipment in the target loop, and taking the pressure and flow rate corresponding to the target pipe section or equipment as the pressure and flow rate corresponding to the target loop. Specifically, the process of obtaining the pressure and flow rate corresponding to the target loop may include obtaining the pressure and flow rate corresponding to a specific pipe section or equipment in the target loop for correspondence. That is, the pressure and flow rate calculation results of the corresponding node are obtained based on the node model, and then the corresponding pressure and flow rate of the target loop are obtained. For example, the calculation results of the pressure and flow rate of the cold pipe section node in the target loop may be selected. The selection of the node can be selected according to the actual needs of the on-site personnel, such as selecting the equipment or pipe section that the current on-site personnel need to be close to in order to improve safety.

[0059] In addition, an electronic device of the present invention may further include a memory and a processor; the memory is used to store a computer program; the processor is used to execute the computer program to implement the above method. Specifically, according to an embodiment of the present invention, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present invention includes a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program contains program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed by an electronic device and, when executed, performs the above functions defined in the method of the embodiment of the present invention. The electronic device in the present invention may be a terminal such as a notebook, desktop, tablet computer, smart phone, or a server.

[0060] It is understandable that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, all of which fall within the scope of protection of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of coverage of the claims of the present invention.

[0061] It is understandable that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, all of which fall within the scope of protection of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of coverage of the claims of the present invention.

Claims

1. A method for flushing hot spots in a primary circuit system of a nuclear power unit, characterized in that: The method comprises: S1. Based on a preset estimation model, generate a node model including a primary circuit system, a residual heat removal system, a medium-pressure safety injection system, a reactor pool, and a reactor core in a nuclear power unit, wherein the primary circuit system includes a first loop, a second loop, and a third loop; the medium-pressure safety injection system includes a first medium-pressure safety injection tank corresponding to the first loop, a second medium-pressure safety injection tank corresponding to the second loop, and a third medium-pressure safety injection tank corresponding to the third loop; S2. Generate an input card corresponding to a node according to the node model, wherein the input card includes node parameters corresponding to the node in the node model; S3, setting the node model to correspond to the initial operating condition of the nuclear power unit, and setting the water level parameter of the reactor pool of the nuclear power unit in the node model to a preset value; S4. Setting a flow parameter of a flow channel in the reactor core in the node model to a first rated value, and adjusting a resistance coefficient parameter of the reactor core in the node model so that a pressure difference value of each node in the reactor core is a corresponding target value; S5. Setting a flow parameter of a flow channel in the residual heat removal system in the node model to a second rated value, and adjusting a resistance coefficient parameter of the residual heat removal system in the node model so that a pressure difference value of each node in the residual heat removal system is a corresponding target value; S6. Determine a target loop based on the hotspot location of the unit to be flushed, and generate several different safety injection modes corresponding to the target loop based on a combination of the first medium-pressure safety injection box, the second medium-pressure safety injection box, and the third medium-pressure safety injection box. Generate the safety injection modes respectively according to the node model, and obtain the pressure and flow rate corresponding to the target loop under each safety injection mode, wherein the target loop is any one of the first loop, the second loop, and the third loop. S7. Selecting a safe injection mode when the pressure and flow rate corresponding to the hot spot position of the unit in the target loop are both at their maximum values, and using the safe injection mode as the hot spot flushing method corresponding to the target loop.

2. The hot spot flushing method of the primary circuit system of a nuclear power unit according to claim 1, characterized in that: In step S1, based on the preset estimation model, a node model including the primary circuit system, residual heat removal system, medium-pressure injection system, reactor pool, and reactor core in the nuclear power unit is generated, including: Based on the light water reactor best estimate model RELAP, the primary system, intermediate pressure injection system, residual heat removal system, reactor pool and reactor core of the pressurized water reactor unit are integrally modeled to obtain the node model.

3. The hot spot flushing method of the primary circuit system of a nuclear power plant according to claim 1, characterized in that: In step S2, When the node of the node model corresponds to a flow component, the node parameters include one or more of the flow area, length, inclination angle, height change, wall roughness, hydraulic diameter, resistance coefficient during forward flow and reverse flow, initial flow rate, and flow velocity of the flow component; When a node in the node model corresponds to a thermal component, the node parameters include the material of the thermal component and one or more of its thermal conductivity and volumetric heat capacity, heat transfer area, source term, and heat sink.

4. The hot spot flushing method of the primary circuit system of a nuclear power plant according to claim 1, characterized in that: In step S3, setting the node model to correspond to the initial operating condition of the nuclear power unit includes: The node model is set to correspond to the nuclear power unit operating in a single-loop open condition with a single RRA pump.

5. The hot spot flushing method of the primary circuit system of a nuclear power unit according to claim 1, characterized in that: In step S4, setting the flow parameter of the flow channel in the reactor core in the node model to a first rated value includes: The rated flow rate of the reactor at zero power is calculated based on the node model, and the rated flow rate is used as the first rated value of the flow parameter of the flow channel in the reactor core in the node model.

6. The hot spot flushing method of the primary circuit system of a nuclear power plant according to claim 1, characterized in that: In step S6, the target loop is determined according to the hotspot position of the unit to be flushed, and several different injection modes corresponding to the target loop are generated based on the combination of the first medium-pressure injection tank, the second medium-pressure injection tank, and the third medium-pressure injection tank, including: A mode in which the medium-pressure safety injection tank corresponding to the target loop among the first medium-pressure safety injection tank, the second medium-pressure safety injection tank and the third medium-pressure safety injection tank is independently injected is referred to as a first safety injection mode; A mode in which the medium-pressure safety injection tanks other than the medium-pressure safety injection tank corresponding to the target loop among the first medium-pressure safety injection tank, the second medium-pressure safety injection tank and the third medium-pressure safety injection tank are simultaneously injected is referred to as a second injection mode; The mode in which the first medium-pressure safety injection tank, the second medium-pressure safety injection tank and the third medium-pressure safety injection tank are simultaneously injected is the third injection mode.

7. The hot spot flushing method of a nuclear power plant primary circuit system according to claim 1, characterized in that: The method further comprises: The compressed air pressure parameters corresponding to the first medium-pressure safety injection tank, the second medium-pressure safety injection tank and the third medium-pressure safety injection tank are set respectively.

8. The hot spot flushing method of the primary circuit system of a nuclear power plant according to claim 7, characterized in that: In the step S7, the compressed air pressure parameters corresponding to the first medium-pressure injection tank, the second medium-pressure injection tank and the third medium-pressure injection tank are set according to the following formulas respectively; Among them, P1 is the set value of the compressed air pressure at the top of the injection tank, V1 is the gas phase volume corresponding to the highest liquid level of the injection tank, V2 is the gas phase volume corresponding to the lowest liquid level of the injection tank, and P2 is the atmospheric pressure after the injection tank is connected to the primary circuit system.

9. The hot spot flushing method of a nuclear power plant primary circuit system according to claim 1, characterized in that: In step S6, obtaining the pressure and flow rate corresponding to the target loop in each safe injection mode includes: A target pipe section or device in the target loop is selected, and the pressure and flow rate corresponding to the target pipe section or device are used as the pressure and flow rate corresponding to the target loop.

10. An electronic device, characterized in that: including memory and processor; The memory is used to store computer programs; The processor is configured to execute the computer program to implement the method according to any one of claims 1 to 9.

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