Method for flushing hot spots of primary loop system of nuclear power unit and electronic equipment

Abstract

The invention relates to a nuclear power unit primary loop system hot spot flushing method and electronic equipment, and the method comprises the steps: generating node models of a primary loop system, a residual heat removal system, a medium-pressure safety injection system, a reactor pool and a reactor core in a nuclear power unit based on a preset estimation model; generating an input card corresponding to the node according to the node model; setting an initial working condition of the nuclear power unit corresponding to the node model; setting flow parameters of a reactor core in the node model and a flow channel in the waste heat removal system as rated values to obtain corresponding resistance coefficient parameters; a target loop is determined, a plurality of different safety injection modes are generated according to the node model, and pressure and flow velocity corresponding to the target loop in each safety injection mode are obtained; and selecting the safety injection mode as the hot spot flushing method of the target loop when the pressure and the flow rate corresponding to the target loop are both maximum values. According to the method, the most reliable hot spot flushing method can be obtained based on rigorous quantitative analysis.

Description

Technical Field

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

[0002] The corrosion products in the primary circuit of the pressurized water reactor migrate with the coolant and are activated in the high-irradiation area of ​​the core. The activated corrosion products are deposited in the non-irradiated area under the coolant to form a radiation field, which poses a serious radiation hazard to the maintenance and operation personnel of the power plant. Deposition hotspots are a flow-accelerated deposition phenomenon that often occurs in fluid-constrained areas such as reducers and valves in pipelines. They are manifested as a large amount of local deposits. Since the deposits contain a large amount of activated corrosion products, the deposition hotspots will directly lead to an increase in local radioactivity and form radioactive hotspots.

[0003] The presence of radioactive hot spots will bring radiation risks to operators when personnel approach during the overhaul of nuclear power units. Therefore, it is necessary to flush the radioactive hot spots. However, in actual applications, most of the flushing methods are based on experience, and reliability cannot be well guaranteed. Summary of the invention

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

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

[0006] S1. Generate node models of a primary loop system, a residual heat removal system, a medium-pressure safety injection system, a reactor pool, and a reactor core in a nuclear power unit based on a preset estimation model, wherein the primary loop 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;

[0007] S2. generating 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 parameter of the flow channel in the reactor core in the node model to the rated value, and adjusting the resistance coefficient parameter of the nuclear power unit in the node model so that the pressure difference value of each node in the node model is the corresponding target value;

[0010] S6. Determine the target loop according to the hot spot position of the unit to be flushed, and generate several different safety injection modes corresponding to the target loop based on the combination of the first medium-pressure safety injection box, the second medium-pressure safety injection box and the third medium-pressure safety injection box, respectively generate the safety injection modes according to the node model, and respectively 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 the injection mode when the pressure and flow rate corresponding to the hot spot position of the unit in the target loop are both at the maximum value, and using this installation mode as the hot spot flushing method corresponding to the target loop.

[0012] Preferably, in the hot spot flushing method of the primary circuit system of a nuclear power unit described in the present invention, in the step S1, generating the node model of 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 the preset estimation model includes:

[0013] Based on the light water reactor best estimate model RELAP, the primary loop 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 parameter includes 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 its thermal conductivity and one or more of 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 of the primary circuit system of a nuclear power unit according to the present invention, in the step S4, setting the flow parameter of the flow channel in the reactor core in the node model to a rated value comprises:

[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 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 of the primary circuit system of a nuclear power unit according to the present invention, in the step S6, the target loop is determined, and a plurality of 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:

[0022] A mode in which a medium-pressure safety injection box corresponding to the target loop among the first medium-pressure safety injection box, the second medium-pressure safety injection box and the third medium-pressure safety injection box is used 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 a second safety 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 safety injection mode.

[0025] Preferably, in the hot spot flushing method of the primary circuit system of a nuclear power unit described in 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 described in the present invention, 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;

[0028]

[0029] Among them, P1 is the set value of the compressed air pressure on the upper part of the injection box, V1 is the gas phase volume corresponding to the highest liquid level of the injection box, V2 is the gas phase volume corresponding to the lowest liquid level of the injection box, and P2 is the atmospheric pressure after the installation box 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 described in the present invention, in step S6, the obtaining of 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] Another electronic device provided by the present invention includes 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 the primary loop 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 It is a program flow chart of an embodiment of a method for flushing hot spots of a primary loop 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 loop system of a nuclear power unit according to the present invention. Figure 1In an embodiment of a hot spot flushing method for a primary loop system of a nuclear power unit of the present invention shown, the method specifically includes: S1, based on a preset estimation model, generating a node model of a primary loop system, a residual heat removal system, a medium-pressure safety injection system, a reactor water pool and a reactor core in a nuclear power unit, wherein the primary loop 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 unit, and setting the water level parameter of the reactor water pool of the nuclear power unit 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 the corresponding target values ​​respectively; 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 values, and use this installation mode as the hot spot flushing method corresponding to the target loop.

[0042] Based on the above step S1, a node model of a primary loop system, a residual heat removal system, a medium-pressure injection system, a reactor pool and a reactor core in a nuclear power unit can be established based on the best estimation procedure commonly used in the field of nuclear power. In the specific node model establishment process, it 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 relationship between the devices or components, and connecting the connection relationship between the nodes according to the actual connection relationship. The setting of the node can be implemented as a single component or a component set as needed. For example, a node in a node model corresponding to a certain monomer component can be set, and a node in a node model corresponding to a functional module containing multiple monomer components can also be set. In a specific embodiment, the primary loop system includes three loops, which are respectively defined as a first loop, a second loop and a third loop, and each loop can include a pressure vessel, a hot pipe section, a steam generator, a pressurizer, a primary side part of a steam generator, a valve, a main pump and a cold pipe section. Each loop is provided with a medium-pressure injection box for realizing the medium-pressure injection working condition of the corresponding loop. Among them, the first medium-voltage safety injection box corresponds to the first loop, the second medium-voltage installation box corresponds to the second loop, and the third medium-voltage installation box corresponds to the third loop. All medium-voltage installation boxes and their corresponding peripheral equipment constitute the medium-voltage safety injection system in the nuclear power unit.

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

[0044] like Figure 2 As shown in the figure, taking the primary loop 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 conditions of the corresponding loops. Figure 3As shown, it is a functional module schematic diagram of a nuclear power unit, and the corresponding node number is generated based on each component. In the specific setting, the node of the reactor pool is set with reference to the structural size and capacity of the reactor pool of the unit; the node of the waste heat removal system pump and the heat exchanger are set according to the structural size of the waste heat removal pump and the waste heat removal exchanger in the waste heat removal system of the unit; the node medium pressure injection tank #1, #2, #3 and the refueling water tank are set with reference to the structural size and capacity of the medium pressure injection tank and the refueling water tank of the unit. The reactor core includes an active area and an associated structure. For example, each heat pipe section is divided into components, and a node number is generated corresponding to each component or connection relationship. It is not limited in this embodiment. For example, different node numbers 235, 335 and 435 are generated for the main pumps in different loops, which is only used as an example here. In another embodiment, the node 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, and the functional modules corresponding to the software program are defined by the input cards. During the operation of the node model, the software program calls each functional module as needed, so that the node model realizes the corresponding function. In this embodiment, the node parameters corresponding to each node in the node model are set by setting the input card, so that when calculating based on the node model, the input card is called as needed to obtain the corresponding working parameters.

[0046] Based on step S3, in the specific calculation, the state of the node model is set to correspond to the initial operating condition of the nuclear power unit. It can be understood that the initial operating condition is the operating condition before the nuclear power unit is filled with water. The selection of this operating condition can select the same operating condition or different operating conditions based on different working scenarios. At the same time, the water level parameters of the reactor pool of the nuclear power unit in the node model are set according to the actual water level height in the reactor pool of the nuclear power unit. For example, the water level of the reactor pool in the initial calculation condition is the full water level (19.5 meters), and the RRA pump is used to drain the pool to the refueling water tank.

[0047] Based on step S4, the flow parameter corresponding to the flow channel in the reactor core in the node model is set to the rated value and remains unchanged. By adjusting the resistance coefficient parameter of the reactor core in the node model, it is confirmed during the adjustment process whether the pressure difference value of each node in the reactor core meets the requirements, for example, whether it is within the preset requirement range, and the adjustment is stopped when the pressure difference value is within the preset requirement range.

[0048] Based on step S5, the flow parameter corresponding to the flow channel in the waste heat removal system in the node model is set to the rated value and remains unchanged. By adjusting the resistance coefficient parameter of the waste heat removal system in the node model, it is confirmed during the adjustment process whether the pressure difference value of each node in the waste heat removal system meets the requirements, for example, whether it is within the preset requirement range, and the adjustment is stopped when the pressure difference value is within the preset requirement range.

[0049] Based on step S6 and step S7, a target loop is selected from the first loop, the second loop and the third loop as needed, for example, a target loop is selected from the above three loops according to the hotspot position of the unit to be flushed. After obtaining the target loop, the first medium-pressure safety injection box, the second medium-pressure safety injection box and the third medium-pressure safety injection box are combined to achieve one or more of the safety injection boxes entering the safety injection mode. The corresponding safety injection mode is generated through the node model, and the pressure and flow rate corresponding to the target loop under each installation mode are obtained. The safety injection mode with the highest pressure and the highest flow rate is selected as the optimal hotspot flushing method corresponding to the target loop.

[0050] Based on the above process, in the refueling shutdown or complete unloading mode of the nuclear power unit overhaul, the flow field and pressure field of the primary circuit can be changed with the help of relevant water filling means, so that the deposited hot spots can re-enter the primary circuit coolant and finally achieve purification. The medium-pressure injection box contains a certain concentration of boron-containing water, and the upper part is covered with gas. When the RCP pressure drops below the injection box pressure, the upper covering gas injects the boron-containing water into the RCP cold section. In the complete unloading mode of the reactor in the downward direction of the unit, compressed air is filled in the upper part to drive the coolant in the medium-pressure injection box into the primary circuit. The higher pressure and flow will drive the activated corrosion products deposited on the surface of the primary circuit pipeline or equipment to achieve the removal of hot spots. Taking into account the actual differences between each medium-pressure installation box and each loop, when the pressure and flow are selected to be the largest, the removal efficiency of the hot spots in the target loop can be made higher.

[0051] Optionally, in step S2, when generating an input card corresponding to a node, 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 the node in the node model corresponds to a thermal component, the node parameters include one or more of the material of the thermal component and its thermal conductivity and volume heat capacity, heat transfer area, source term, and heat sink. Specifically, the input card in the node model is set based on the design parameters and operating parameters of the system and equipment in the nuclear power unit. Among them, the design parameters and operating parameters of the system and equipment can be refined to specific components or assemblies, and different parameters are 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 operating condition of the nuclear power unit operating in a single RRA pump with a single circuit open. Specifically, in the process of calculating based on the node model, the initial state of the node model is first set to correspond to the operating condition of the nuclear power unit operating in a single RRA pump with a single circuit open, and the 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 practical 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. In the calculation process, the rated flow at zero power of the reactor is calculated by 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 according to the hot spot 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 box, the second medium-pressure injection box and the third medium-pressure injection box, including: the mode in which the medium-pressure injection box corresponding to the target loop among the first medium-pressure injection box, the second medium-pressure injection box and the third medium-pressure injection box is injected alone as the first injection mode; the mode in which the medium-pressure injection boxes among the first medium-pressure injection box, the second medium-pressure injection box and the third medium-pressure injection box except the medium-pressure injection box corresponding to the target loop are injected at the same time as the second injection mode; the mode in which the first medium-pressure injection box, the second medium-pressure injection box and the third medium-pressure injection box are injected at the same time as the third injection mode. Specifically, after the target loop is selected, such as after the second loop is selected, the first injection mode in which only the second medium-pressure injection box 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 is used to generate the second injection mode in which the first medium-pressure injection box and the third medium-pressure injection box are simultaneously put into injection, and the corresponding pressure and flow in the second loop are obtained at this time. The node model is used to generate the third injection mode in which the first medium-pressure installation box, the second medium-pressure injection box and the third medium-pressure injection box are simultaneously put into injection, and the corresponding pressure and flow in the second loop are obtained at this time. The injection mode with the largest pressure and flow is used to perform hot spot flushing on the injection mode that needs to be selected for the current nuclear power unit.

[0055] In one embodiment, the hot spot flushing method of the primary loop system of a nuclear power unit of the present invention further includes setting 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 respectively. During the water filling process of the medium-pressure injection tank, as the liquid level decreases, the upper compressed air will expand. This process is 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 pressure and flow rate corresponding to the target loop in each injection mode are obtained, including: 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 pressure and flow rate of the target loop are obtained accordingly. For example, the calculation results of the pressure and flow rate of the cold pipe section node in the target loop can 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 approach to improve safety.

[0059] In addition, an electronic device of the present invention may also 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 with reference to the flowchart above 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 a 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, it performs the above functions defined in the method of the embodiment of the present invention. The electronic device in the present invention can be a terminal such as a notebook, a desktop, a tablet computer, a smart phone, or a server.

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

[0061] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the 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, a node model including a primary loop system, a residual heat removal system, a medium-pressure safety injection system, a reactor pool, and a reactor core in a nuclear power unit is generated, wherein the primary loop 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 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 the flow parameter of the flow channel in the reactor core in the node model to a first rated value, and adjusting the resistance coefficient parameter of the reactor core in the node model so that the pressure difference value of each node in the reactor core is respectively the corresponding target value; S5, setting the flow parameter of the flow channel in the residual heat removal system in the node model to a second rated value, and adjusting the resistance coefficient parameter of the residual heat removal system in the node model so that the pressure difference value of each node in the residual heat removal system is respectively the corresponding target value; S6. Determine the target loop according to the hot spot position of the unit to be flushed, and generate several different safety injection modes corresponding to the target loop based on the combination of the first medium-pressure safety injection box, the second medium-pressure safety injection box and the third medium-pressure safety injection box, respectively generate the safety injection modes according to the node model, and respectively 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 the injection mode when the pressure and flow rate corresponding to the hot spot position of the unit in the target loop are both at the maximum value, and using this installation mode as the hot spot flushing method corresponding to the target loop.

2. The method for hot spot flushing of a primary circuit system of a nuclear power unit according to claim 1, characterized in that: In step S1, the node models of 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 are generated based on the preset estimation model, including: Based on the light water reactor best estimate model RELAP, the primary loop system, medium 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 method for flushing hot spots in the primary circuit system of a nuclear power unit according to claim 1, characterized in that: In step S2, When the node of the node model corresponds to a flow component, the node parameter includes 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 its thermal conductivity and one or more of volumetric heat capacity, heat transfer area, source term and heat sink.

4. The method for hot spot flushing of a primary circuit system of a nuclear power unit 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 method for flushing hot spots in the primary circuit system of a nuclear power unit according to claim 1, characterized in that: In the step S4, setting the flow parameter of the flow channel in the reactor core in the node model to a 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 rated value of the flow parameter of the flow channel in the reactor core in the node model.

6. The method for flushing hot spots in the primary circuit system of a nuclear power unit according to claim 1, characterized in that: In step S6, the target loop is determined according to the hot spot 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 a medium-pressure safety injection box corresponding to the target loop among the first medium-pressure safety injection box, the second medium-pressure safety injection box and the third medium-pressure safety injection box is used 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 a second safety 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 safety injection mode.

7. The method for flushing hot spots in the primary circuit system of a nuclear power unit 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 method for flushing hot spots in the primary circuit system of a nuclear power unit 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 respectively set according to the following formulas; Among them, P1 is the set value of the compressed air pressure on the upper part of the injection box, V1 is the gas phase volume corresponding to the highest liquid level of the injection box, V2 is the gas phase volume corresponding to the lowest liquid level of the injection box, and P2 is the atmospheric pressure after the installation box is connected to the primary circuit system.

9. The method for flushing hot spots in the primary circuit system of a nuclear power plant 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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