Multi-unit cold source risk difference test method based on obstruction migration

Abstract

The invention relates to the crossing technical field of water conservancy and nuclear power engineering, in particular to a multi-unit cold source risk difference test method based on obstruction migration, and solves the problems that in the prior art, cold source risk assessment mainly depends on numerical simulation or empirical judgment, interaction between complex water flow and obstacles is difficult to truly restore, and the risk is poor. The migration behavior of the blockages under the condition of water intake of multiple units and the risk difference caused by the migration behavior cannot be accurately reflected. The method comprises the following steps: establishing a physical model for accurately simulating key structures such as a water taking open channel, a pump room and a trash holding net, setting a plurality of tide and water taking flow combined working conditions, and putting bulkheads such as marine organisms and floating objects. According to the method, through a mode of combining a physical model test and numerical simulation, the actual migration process of the blockages in a complex flow field can be reproduced more truly, the accuracy and intuition of cold source risk assessment are remarkably improved, and a scientific basis is provided for safety design and operation management of a multi-unit water intake system of a nuclear power plant.

Description

Technical Field

[0001] The present invention relates to the technical field of intersection between water conservancy and nuclear power engineering, and in particular to a multi-unit cold source risk difference test method based on blockage migration. Background Art

[0002] Multi-unit cooling risk differentiation refers to the phenomenon of inconsistent cooling water safety faced by different units when multiple units in a nuclear power plant operate in parallel due to factors such as water flow organization, topographic conditions, and water intake layout. Among these factors, the migration paths and distribution patterns of obstructions (such as marine organisms and floating debris) are key factors influencing the differences in cooling water risk across units. Therefore, conducting research on multi-unit cooling risk differentiation based on obstruction migration is of great significance for optimizing water intake system design and improving nuclear power plant operational safety.

[0003] Existing cold source risk assessment methods primarily rely on numerical simulations or empirical judgment. These methods struggle to accurately reproduce the complex interactions between water flows and obstacles when simulating the migration of obstructions. This is especially true when multiple units are operating in parallel. These methods are unable to accurately reflect the differences in cold source risk between units due to uneven water flow distribution and varying obstruction accumulation trends. These issues directly lead to significant deviations in risk assessment results, making it difficult to support scientific design decisions and meet the high-standard, high-reliability water safety requirements of nuclear power plants. More seriously, these issues can cause certain units to operate in a high-risk state for extended periods, increasing the probability of unplanned outages and threatening the overall operational safety of the nuclear power plant.

[0004] Therefore, to address the shortcomings of existing technologies, a multi-unit cooling source risk differential testing method based on blockage migration is urgently needed to address this challenge. This new technology should significantly improve the accuracy and intuitiveness of multi-unit cooling source risk differential assessments, while better reflecting the actual migration behavior of blockages in complex flow fields, providing strong support for the safe design and operation management of nuclear power plant water intake systems. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-unit cold source risk difference test method based on blockage migration, which solves the problem that the cold source risk assessment method in the existing technology mainly relies on numerical simulation or empirical judgment, and it is difficult to truly restore the interaction between complex water flow and obstacles when simulating the blockage migration process.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A multi-unit cooling source risk differentiation test method based on blockage migration involves establishing a physical model of the nuclear power plant's water intake system. This model must accurately simulate key components such as the intake channel, pump house, and trash screen to ensure similar water flow between the model and the prototype.

[0008] The flow field in the water intake channel is simulated in a physical model, taking into account the combined effects of offshore tides, unit water intake flow, water temperature, water quality and other environmental factors;

[0009] Place blockages at designated locations in the physical model to simulate possible blockages in actual operation. Blockages include marine organisms, floating objects, etc.

[0010] Use advanced monitoring equipment to record the movement of obstructions within the open intake channel, including key parameters such as movement path, speed, and distribution;

[0011] Based on the movement of blockages, assess the differences in cooling source risks faced by each unit and analyze the degree of impact on different units;

[0012] Based on the assessment results, we propose optimization recommendations for the water intake system, including improving the design of the trash screen, adjusting the water intake strategy, and adding cleaning equipment to improve the safety and stability of the water intake system.

[0013] Combined with numerical simulation technology, the results of physical model tests are verified and supplemented to improve the accuracy and reliability of cold source risk assessment.

[0014] Preferably, the construction scale of the physical model needs to be determined according to the actual situation of the water intake system of the nuclear power plant to ensure the geometric similarity and dynamic similarity between the model and the prototype.

[0015] Preferably, the flow field simulation needs to consider a variety of operating conditions, including different tidal conditions, different unit water intake flow combinations, etc., to fully reflect the complex flow field conditions in actual operation.

[0016] Preferably, the placement and quantity of the blockages should be determined according to the actual situation and test requirements to simulate blockages of different severity.

[0017] Preferably, the monitoring equipment includes a camera, a flow meter, a water level meter, etc., which are used to comprehensively record the movement of the blockage and the flow field characteristics.

[0018] Preferably, the cold source risk assessment needs to consider the impact of the blockage on the water intake of the unit, the impact on the water flow pattern of the pump room, and the impact on the overall operating efficiency of the nuclear power plant.

[0019] Preferably, the optimization suggestions should be specific and feasible, and be able to propose effective improvement measures for the differences in cold source risks found in the assessment results.

[0020] The present invention has at least the following beneficial effects:

[0021] In view of the problem that the existing cold source risk assessment method proposed in the background technology mainly relies on numerical simulation or empirical judgment, and it is difficult to truly restore the interaction between complex water flows and obstacles, the present invention constructs a high-precision physical model and conducts blockage migration tests in combination with actual operating conditions, which effectively improves the ability to reproduce key problems such as uneven flow fields and differences in blockage migration paths under water intake conditions of multiple units, and makes up for the shortcomings of traditional methods in boundary condition simplification and migration process modeling; for the problem of being unable to accurately reflect the difference in cold source risks between different units, the present invention places blockages at fixed points and adopts high-precision monitoring manual The arrival probability, accumulation trend and impact degree of blockages near the water intakes of different units can be intuitively obtained, thereby realizing the accurate division of the risk level of the cold source of each unit and providing a scientific basis for differentiated management. In addition, the present invention also comprehensively considers the influence of environmental factors such as tidal changes, water intake flow fluctuations, water temperature and water quality, so that the test is closer to the actual operating conditions and enhances the representativeness and generalizability of the test results. At the same time, the physical model test results are verified and supplemented in combination with numerical simulation technology, which not only improves the accuracy and completeness of the cold source risk assessment, but also provides data support for the formulation of subsequent optimization measures. In summary, the present invention solves the problems of large assessment deviations and lack of intuitive migration information in the existing technology by combining physical model tests with numerical simulations, significantly improves the scientificity and practicality of the risk difference assessment of cold sources of multiple units, and provides strong technical support for the safety improvement and operation optimization of the water intake system of nuclear power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a schematic diagram of the process of the present invention;

[0024] Figure 2 This is a schematic diagram of the secondary circulation process of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0026] Example 1

[0027] See also Figure 1-2As shown, a multi-unit cold source risk differential testing method based on blockage migration in this embodiment includes establishing a physical model of the nuclear power plant's water intake system. The model must accurately simulate key components such as the water intake channel, pump house, and trash screen to ensure similar water flow between the model and the prototype. The flow field within the water intake channel is simulated in the physical model, taking into account the combined effects of offshore tides, unit water intake flow, and environmental factors such as water temperature and water quality. Blockages, such as marine organisms and floating debris, are placed at designated locations in the physical model to simulate blockages that may occur during actual operation. Advanced monitoring equipment is used to record the movement of the blockages within the water intake channel, including key parameters such as migration path, speed, and distribution. Based on the movement of the blockages, the cold source risk differences faced by each unit are assessed, and the degree of impact on different units is analyzed. Based on the assessment results, optimization suggestions for the water intake system are proposed, including improving the design of the trash screen, adjusting the water intake strategy, and adding cleaning equipment to improve the safety and stability of the water intake system. Numerical simulation technology is used to verify and supplement the results of the physical model test to improve the accuracy and reliability of the cold source risk assessment. By simulating the movement of blockages, the present invention can accurately assess the differences in cold source risks of different units when facing blockages. Compared with the existing technology, the present invention has the following advantages: First, the present invention takes into account the combined effects of offshore tides, unit water intake flow, and environmental factors such as water temperature and water quality, and can more comprehensively reflect the complex flow field conditions in actual operation; second, the present invention uses advanced monitoring equipment to record the movement of blockages, and can more accurately obtain key parameters such as the migration path, speed, and distribution of blockages; finally, the present invention combines numerical simulation technology to verify and supplement the results of physical model tests, thereby improving the accuracy and reliability of cold source risk assessment. Through the present invention, it is possible to understand the differences in cold source risks of each unit, optimize the design and operation strategies of the water intake system in a targeted manner, and improve the overall safety and stability of the system. At the same time, when a blockage occurs, it is possible to quickly determine the degree of impact on each unit and guide the formulation and implementation of emergency treatment measures.

[0028] Water intake and water intake parameters of units 1-6

[0029]

[0030] The complete workflow is as follows: First, a physical model of the nuclear power plant's water intake system is established. The model accurately simulates key structures such as the water intake channel, pump house, and trash screen to ensure the similarity between the model and the actual project in terms of geometric shape and water flow characteristics; then, the flow field in the water intake channel is simulated in the physical model, and the combined influence of offshore tides, water intake flow rates of different units, and environmental factors such as water temperature and water quality are comprehensively considered to restore the complex hydrodynamic environment under real operating conditions; then, blockages of different types and densities (such as marine organisms, floating objects, etc.) are placed at designated locations in the physical model to simulate possible blockages in actual operation; then, Advanced monitoring equipment is used to record key parameters such as the migration path, speed, and distribution of blockages, so as to capture the entire process of the dynamic behavior of the blockages. On this basis, the differences in cold source risks faced by each unit are evaluated based on the recorded data, and high-risk units and their causes are identified, such as uneven flow fields and areas where blockages gather. Subsequently, optimization suggestions are put forward based on the evaluation results, including improving the design of the pollution control net, adjusting the unit water intake strategy, and increasing the density of cleaning equipment, so as to enhance the safety and stability of the water intake system. Finally, combined with numerical simulation technology, the physical model test results are compared and verified and the data is supplemented to further improve the accuracy and comprehensiveness of the cold source risk assessment.

[0031] Example 2

[0032] See also Figure 1-2 As shown in this embodiment, a multi-unit cold source risk differentiation test method based on blockage migration is proposed. The scale of the physical model construction must be determined based on the actual conditions of the nuclear power plant water intake system to ensure geometric and dynamic similarity between the model and the prototype. Flow field simulation must consider multiple operating conditions, including different tidal conditions and different unit water intake flow combinations, to fully reflect the complex flow field conditions in actual operation. The location and number of blockages must be determined based on actual conditions and test requirements to simulate blockages of varying severity. By constructing a physical model with a scale determined according to the actual situation of the nuclear power plant's water intake system, taking into account different tidal conditions and unit water intake flow combinations in flow field simulation, and setting the location and quantity of blockages according to test requirements, the specific methods of model construction and test condition design are further refined in Example 2, thereby achieving the effect of improving model similarity and test coverage and ensuring that the test results are closer to the actual project; through the setting of monitoring equipment including cameras, flow meters, water level meters and other structures, the full process and multi-parameter synchronous recording of the blockage migration path, speed and flow field characteristics is achieved in Example 3, thereby achieving the effect of improving data collection integrity and the accuracy of cold source risk assessment.

[0033] According to the unsteady flow motion equation and the continuity equation, the relationship between the similarity scale of water flow motion is as follows:

[0034] Gravity similarity:

[0035] λ Q =λ h 5 / 2 (6.3-2)

[0036] Resistance similarity: λ c =(λ l / λ h ) 1 / 2 (6.3-3)

[0037] Water flow time scale:

[0038] If the Manning formula is used to determine the Xie Cai coefficient, that is:

[0039]

[0040] The roughness scale is:

[0041] On the other hand, the model water flow is in a turbulent state, and the vertical scale of the model should meet the following conditions:

[0042]

[0043] Where: λu and λv are velocity scales, λQ is the flow scale; λh is the vertical scale; λl is the horizontal scale; λt is the flow time scale; and λC is the Schertz coefficient scale. Therefore, in terms of water flow similarity, if the gravity similarity (Equation 6.3-1), resistance similarity (Equation 6.3-3 or (Equation 6.3-6), and vertical scale constraint conditions (Equation 6.3-7) are satisfied, the model will meet water flow similarity.

[0044] Example 3

[0045] See also Figure 1-2 As shown, this embodiment is a multi-unit cold source risk difference test method based on the movement of blockages. The monitoring equipment includes cameras, flow meters, water level meters, etc., which are used to comprehensively record the movement of blockages and flow field characteristics. The cold source risk assessment needs to consider the impact of blockages on the water intake of the unit, the impact on the water inlet flow pattern of the pump room, and the impact on the overall operating efficiency of the nuclear power plant. The optimization suggestions must be specific and feasible, and be able to propose effective improvement measures for the cold source risk differences found in the assessment results. Through the cold source risk assessment, the impact of blockages on the water intake of the unit, the water inlet flow pattern of the pump room and the operating efficiency of the nuclear power plant is comprehensively considered, and the setting of specific and feasible optimization suggestions is proposed. In Example 3, a complete chain from test data to engineering application is established, which achieves the effect of combining risk difference identification with the formulation of targeted optimization measures to improve the safety and stability of the water intake system.

[0046] Model scale summary table

[0047] parameter Model Value Scale conversion Prototype value Geometric dimensions (length, width, height, etc.) 1 λ 50 time 1 <![CDATA[λ 1 / 2 ]]> 7.07 Speed ​​(flow rate, etc.) 1 <![CDATA[λ 1 / 2 ]]> 7.07 flow 1 <![CDATA[λ 5 / 2 ]]> 17677.68

[0048] The present invention provides a multi-unit cold source risk difference test method based on blockage migration, and its complete workflow is as follows: first, a physical model of the nuclear power plant water intake system is established, which accurately simulates key structures such as the water intake channel, pump room, and trash net, and determines the construction scale according to actual conditions to ensure geometric similarity and dynamic similarity; then, the flow field in the water intake channel is simulated in the physical model, considering various working conditions such as different tidal conditions, different unit water intake flow combinations, etc., as well as the combined influence of environmental factors such as offshore tides, water temperature, and water quality, to restore the complex hydrodynamic environment under actual operating conditions; then, blockages of different types and densities are placed at designated locations in the physical model, and the placement locations and quantities are set according to actual conditions and test requirements to simulate different degrees of blockage. ; Then, advanced monitoring equipment such as cameras, flow meters, water level meters, etc. are used to record key parameters such as the migration path, speed, distribution, etc. of the blockage, so as to capture the dynamic behavior of the blockage throughout the entire process; on this basis, the differences in cold source risks faced by each unit are evaluated based on the recorded data, high-risk units and their causes are identified, and the impact of blockages on the unit water intake, pump room water flow pattern and the overall operating efficiency of the nuclear power plant are comprehensively considered; then, optimization suggestions are put forward based on the evaluation results, including specific feasible measures such as improving the design of the pollution control net, adjusting the unit water intake strategy, and increasing the layout density of cleaning equipment to improve the safety and stability of the water intake system; finally, combined with numerical simulation technology, the physical model test results are compared and verified and the data is supplemented to further improve the accuracy and comprehensiveness of the cold source risk assessment.

[0049] The present invention has significant benefits compared to existing technologies. By determining the scale of the physical model based on the actual conditions of the nuclear power plant's water intake system, considering different tidal conditions and unit water intake flow combinations in flow field simulation, and setting the location and quantity of obstruction placement based on test requirements, the model's similarity and test coverage are improved, ensuring that the test results are closer to the actual project. By setting up monitoring equipment including cameras, flow meters, and water level gauges, the full-process, multi-parameter simultaneous recording of the obstruction's migration path, velocity, and flow field characteristics is achieved, thereby improving data acquisition integrity and the accuracy of cold source risk assessment. Through the cold source risk assessment, the impact of obstructions on unit water intake, pump room inlet flow patterns, and nuclear power plant operating efficiency is comprehensively considered, and specific and feasible optimization suggestions are proposed. This establishes a complete chain from test data to engineering application, achieving the combination of risk difference identification and targeted optimization measures, and improving the safety and stability of the water intake system. Furthermore, by combining numerical simulation technology to verify and supplement the physical model test results, the accuracy and integrity of the cold source risk assessment are not only improved, but also data support is provided for the formulation of subsequent optimization measures. In summary, the present invention solves the problems of large assessment deviation and lack of intuitive migration information in the existing technology by combining physical model experiments with numerical simulations, significantly improves the scientificity and practicality of the risk difference assessment of multi-unit cold source, and provides strong technical support for the safety improvement and operation optimization of the water intake system of nuclear power plants.

[0050] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-unit cooling source risk difference test method based on blockage migration, characterized in that: The following steps are involved: Build a physical model of the nuclear power plant's water intake system. This model must accurately simulate key components such as the intake channel, pump house, and trash screen, ensuring similar water flow between the model and the prototype. The flow field in the water intake channel is simulated in a physical model, taking into account the combined effects of offshore tides, unit water intake flow, water temperature, water quality and other environmental factors; Place blockages at designated locations in the physical model to simulate possible blockages in actual operation. Blockages include marine organisms, floating objects, etc. Use advanced monitoring equipment to record the movement of obstructions within the open intake channel, including key parameters such as movement path, speed, and distribution; Based on the movement of blockages, assess the differences in cooling source risks faced by each unit and analyze the degree of impact on different units; Based on the assessment results, we propose optimization recommendations for the water intake system, including improving the design of the trash screen, adjusting the water intake strategy, and adding cleaning equipment to improve the safety and stability of the water intake system. Combined with numerical simulation technology, the results of physical model tests are verified and supplemented to improve the accuracy and reliability of cold source risk assessment.

2. A multi-unit cooling source risk difference test method based on blockage migration according to claim 1, characterized in that: The construction scale of the physical model needs to be determined according to the actual situation of the water intake system of the nuclear power plant to ensure the geometric and dynamic similarity between the model and the prototype.

3. The multi-unit cooling source risk difference test method based on blockage migration according to claim 1 is characterized in that: Flow field simulation needs to take into account a variety of operating conditions, including different tidal conditions, water intake flow combinations of different units, etc., in order to fully reflect the complex flow field conditions in actual operation.

4. The multi-unit cooling source risk difference test method based on blockage migration according to claim 1 is characterized in that: The placement and quantity of blockages need to be determined based on actual conditions and test requirements to simulate blockages of varying severity.

5. The multi-unit cooling source risk difference test method based on blockage migration according to claim 1 is characterized in that: Monitoring equipment includes cameras, flow meters, water level meters, etc., which are used to comprehensively record the movement of blockages and flow field characteristics.

6. The multi-unit cooling source risk difference test method based on blockage migration according to claim 1 is characterized in that: The cold source risk assessment needs to consider the impact of blockages on the unit's water intake, the impact on the pump room inlet flow pattern, and the impact on the overall operating efficiency of the nuclear power plant.

7. The multi-unit cooling source risk difference test method based on blockage migration according to claim 1 is characterized in that: Optimization suggestions must be specific and feasible, and be able to propose effective improvement measures based on the differences in cold source risks found in the assessment results.

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