Simulation method and device for near-earth migration of nuclear accident leakage source item

Abstract

The invention relates to a simulation method and device for near-earth migration of a nuclear accident leakage source item. The method comprises the following steps: simulating migration of radionuclides released in a nuclear accident in the atmosphere by adopting a Gaussian diffusion model to obtain an atmospheric migration model; correcting the atmospheric migration model according to the concentration change of radionuclides in the atmosphere caused by evaporation by using a Dalton evaporation formula; migrating of radionuclides leaked in the nuclear accident in a river is simulated based on a two-dimensional Gaussian dispersion equation, and a river migration model is obtained; and performing numerical simulation on the atmospheric migration model and the river migration model by using a Matlab programming mode to generate a nuclide concentration distribution diagram and a diffusion path diagram.

Description

Technical Field

[0001] The present application relates to the technical field of code segment adaptation, and in particular to a method and device for simulating the near-ground migration of nuclear accident leakage sources. Background Art

[0002] Nuclear accidents have far-reaching impacts and are extremely important for the sustainable development of nuclear energy. Once a nuclear accident occurs, human activities will be impossible within a few kilometers of the leak, which is not only harmful to the entire country but also to the world's ecological environment.

[0003] Radioactive substances have various behaviors in the environment. The main nuclides that cause harm to the human body include: 137 Cs, 131 I, 3 H et al., among which 137 Cs, 131 I, 3 H will be transported and diffused through the atmosphere. 131 I, 3 H will be transported, dispersed and migrated through rivers. Radioactive nuclide leakage is difficult to detect without close-range detection by professional instruments, and the wide diffusion range makes it difficult to accurately measure the scope by instruments. Therefore, the migration of radioactive nuclides is simulated by software, and the leakage of radioactive materials is analyzed more accurately and visually, so as to deal with the consequences of leakage of small nuclear power plants more accurately and controllably. Summary of the invention

[0004] Based on this, it is necessary to provide a simulation method and device for the near-ground migration of nuclear accident leakage sources in response to the above-mentioned technical problems.

[0005] A method for simulating near-ground migration of nuclear accident leakage source items, the method comprising:

[0006] The Gaussian diffusion model is used to simulate the migration of radionuclides released in nuclear accidents in the atmosphere, and an atmospheric migration model is obtained;

[0007] The atmospheric migration model is corrected by using Dalton's evaporation formula to account for changes in the concentration of radionuclides in the atmosphere due to evaporation;

[0008] The migration of radionuclides leaked in nuclear accidents in rivers is simulated based on the two-dimensional Gaussian dispersion equation, and a river migration model is obtained.

[0009] The atmospheric migration model and the river migration model are numerically simulated by Matlab programming to generate a distribution map of nuclide concentration and a diffusion path map.

[0010] In one embodiment, the method further includes: obtaining the emission rate Q of a uniform continuous emission source of nuclear waste water vapor from a nuclear accident as:

[0011]

[0012] Where X is the concentration of radioactivity in the air at the reference coordinate (x, y, z), and u is the average wind speed;

[0013] According to the emission rate Q, the atmospheric migration model of the concentration of airborne substances in the atmosphere is obtained as follows:

[0014]

[0015] σ y , σ z are the diffusion coefficients in the y and z directions respectively, and h is the release height of the emission source.

[0016] In one embodiment, the atmospheric migration model is modified by using Dalton's evaporation formula to calculate the concentration change of radionuclides in the atmosphere due to evaporation:

[0017] W=C(Ee) / Pa

[0018] W is the evaporation rate of the water surface, Ee is the air saturation difference, Pa is the atmospheric pressure, and C is a proportional function related to the wind speed.

[0019] In one embodiment, the method further includes: performing a two-stage simulation of the migration of radioactive nuclides leaked in a nuclear accident in a river based on a two-dimensional Gaussian diffusion equation, wherein the incomplete diffusion stage is:

[0020]

[0021] Where C is the pollutant concentration at the downstream of the discharge port (x, y), Q is the emission rate, and K is the lateral diffusion coefficient;

[0022] Complete mixing section:

[0023]

[0024] in, F is the sum of river flow and waste flow, B is the width of the river, K is the a represents the diffusion coefficient in the direction of water flow, λ r represents the decay constant of the nuclide;

[0025] The river migration model for the fully mixed section is simplified as:

[0026]

[0027] Introducing correction factor f = e (-λt) Correction for emission rates.

[0028] A device for simulating near-ground migration of nuclear accident leakage source items, the device comprising:

[0029] The atmospheric migration module is used to simulate the migration of radionuclides released in nuclear accidents in the atmosphere using the Gaussian diffusion model to obtain an atmospheric migration model;

[0030] A correction module, for correcting the atmospheric migration model based on the concentration change of radionuclides in the atmosphere caused by evaporation using the Dalton evaporation formula;

[0031] The river migration module is used to simulate the migration of radionuclides leaked in nuclear accidents in rivers based on the two-dimensional Gaussian dispersion equation to obtain a river migration model;

[0032] The numerical simulation module is used to perform numerical simulation on the atmospheric migration model and the river migration model by using Matlab programming to generate a distribution map of nuclide concentration and a diffusion path map.

[0033] In one embodiment, the atmospheric migration module is also used to obtain the emission rate Q of the uniform continuous emission source of nuclear waste water vapor in a nuclear accident as follows:

[0034]

[0035] Where X is the concentration of radioactivity in the air at the reference coordinate (x, y, z), and u is the average wind speed;

[0036] According to the emission rate Q, the atmospheric migration model of the concentration of airborne substances in the atmosphere is obtained as follows:

[0037]

[0038] σ y , σ z are the diffusion coefficients in the y and z directions respectively, and h is the release height of the emission source.

[0039] In one embodiment, the correction module is further used to use the Dalton evaporation formula to correct the atmospheric migration model according to the concentration change of radionuclides in the atmosphere caused by evaporation:

[0040] W=C(Ee) / Pa

[0041] W is the evaporation rate of the water surface, Ee is the air saturation difference, Pa is the atmospheric pressure, and C is a proportional function related to the wind speed.

[0042] In one embodiment, the river migration module is also used to perform a two-stage simulation of the migration of radionuclides leaked in a nuclear accident in a river based on a two-dimensional Gaussian diffusion equation, wherein the incomplete diffusion stage is:

[0043]

[0044] Where C is the pollutant concentration at the downstream of the discharge port (x, y), Q is the emission rate, and K is the lateral diffusion coefficient;

[0045] Complete mixing section:

[0046]

[0047] in, F is the sum of river flow and waste flow, B is the width of the river, K is the a represents the diffusion coefficient in the direction of water flow, λ r represents the decay constant of the nuclide;

[0048] The river migration model for the fully mixed section is simplified as:

[0049]

[0050] Introducing correction factor f = e (-λt) Correction for emission rates.

[0051] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0052] The Gaussian diffusion model is used to simulate the migration of radionuclides released in nuclear accidents in the atmosphere, and an atmospheric migration model is obtained;

[0053] The atmospheric migration model is corrected by using Dalton's evaporation formula to account for changes in the concentration of radionuclides in the atmosphere due to evaporation;

[0054] The migration of radionuclides leaked in nuclear accidents in rivers is simulated based on the two-dimensional Gaussian dispersion equation, and a river migration model is obtained.

[0055] The atmospheric migration model and the river migration model are numerically simulated by Matlab programming to generate a distribution map of nuclide concentration and a diffusion path map.

[0056] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the following steps:

[0057] The Gaussian diffusion model is used to simulate the migration of radionuclides released in nuclear accidents in the atmosphere, and an atmospheric migration model is obtained;

[0058] The atmospheric migration model is corrected by using Dalton's evaporation formula to account for changes in the concentration of radionuclides in the atmosphere due to evaporation;

[0059] The migration of radionuclides leaked in nuclear accidents in rivers is simulated based on the two-dimensional Gaussian dispersion equation, and a river migration model is obtained.

[0060] The atmospheric migration model and the river migration model are numerically simulated by Matlab programming to generate a distribution map of nuclide concentration and a diffusion path map.

[0061] The above-mentioned simulation method and device for the near-ground migration of nuclear accident leakage sources, by modeling atmospheric migration and river migration, and by using the Dalton evaporation formula to correct the evaporation loss of radioactive nuclides in the atmosphere, can more accurately simulate the actual diffusion process of nuclides after nuclear accident leakage, avoiding concentration errors caused by ignoring the effect of evaporation. This correction improves the simulation accuracy, makes the nuclide concentration distribution more consistent with the actual environmental conditions, and provides a more reliable basis for assessing the environmental impact of nuclear accident leakage and formulating emergency response measures, thereby effectively improving the environmental protection and risk management capabilities after the accident. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A schematic flow chart of a method for simulating near-ground migration of a nuclear accident leakage source in one embodiment;

[0063] Figure 2 A schematic diagram of the structure of a simulation device for near-ground migration of a nuclear accident leakage source in one embodiment;

[0064] Figure 3 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0066] In one embodiment, if Figure 1 As shown, a simulation method for near-ground migration of nuclear accident leakage source items is provided, including:

[0067] Step 102, using a Gaussian diffusion model to simulate the migration of radioactive nuclides released in a nuclear accident in the atmosphere to obtain an atmospheric migration model.

[0068] Step 104, using Dalton's evaporation formula to correct the atmospheric migration model based on the concentration change of radioactive nuclides in the atmosphere caused by evaporation.

[0069] Step 106, simulating the migration of radioactive nuclides leaked in the nuclear accident in the river based on the two-dimensional Gaussian diffusion equation to obtain a river migration model.

[0070] Step 108, using Matlab programming to perform numerical simulation on the atmospheric migration model and the river migration model, and generate a distribution map of nuclide concentration and a diffusion path map.

[0071] The above-mentioned simulation method of near-ground migration of nuclear accident leakage sources models atmospheric migration and river migration, and uses the Dalton evaporation formula to correct the evaporation loss of radioactive nuclides in the atmosphere. This method can more accurately simulate the actual diffusion process of nuclides after nuclear accident leakage, avoiding concentration errors caused by ignoring the effect of evaporation. This correction improves the simulation accuracy, making the nuclide concentration distribution more consistent with the actual environmental conditions, and provides a more reliable basis for assessing the environmental impact of nuclear accident leakage and formulating emergency response measures, thereby effectively improving the environmental protection and risk management capabilities after the accident.

[0072] In the present invention, for atmospheric migration, there are the following migration processes:

[0073] 1. Dry and wet deposition

[0074] After falling to the ground, radionuclides may be adsorbed or evaporated by the surface of soil, buildings, etc., causing changes in the concentration of radionuclides in the surface layer. When it rains, the radionuclides will be carried by raindrops and fall to the ground, forming a wet deposition process. During the wet deposition process, radionuclides may also be adsorbed on sediment particles to form suspended particles, which are transported to other places with the water flow. These sediments and particles are difficult to remove and will exist in the environment for a long time, posing potential hazards to ecosystems and human health.

[0075] 2. Wake effect

[0076] The wake effect in atmospheric diffusion refers to the fact that when pollutants emitted by pollution sources diffuse into the surrounding air, they will affect the surrounding airflow due to the effects of eddies and turbulence, producing an effect similar to that of an airplane wake. When airflow passes through a building, it will be disturbed by the building, and at the same time, airflow will flow back on the leeward side of the building, which will increase the complexity of airflow analysis. When the height of the gas released by the pollution source is less than 2.5 times that of the surrounding buildings, the impact of the building on the airflow will be more significant.

[0077] For atmospheric diffusion simulation calculations, the wake effect may have a significant impact on the simulation results. This is because the wake effect will form turbulence and eddies, thereby changing the flow speed and direction of the surrounding air, resulting in uneven distribution of pollutant concentrations. When the pollutant release source is on the ground and due to the influence of terrain elements such as islands and mountains, the convection conditions are inconsistent within their influence range, the wake effect will be more significant. In order to reduce the impact of the wake effect on atmospheric diffusion simulation calculations, various factors need to be considered in the model, such as terrain height difference, wind direction, wind speed, meteorological conditions, nearby buildings and forests, etc. At the same time, increasing the height of the pollutant release source can reduce the impact of the wake effect. In addition, for high-precision simulation and measured data, multi-point sampling and averaging processing can be used for simulation and calculation.

[0078] The reasons for migration in water bodies are as follows:

[0079] 1. Horizontal transport

[0080] Horizontal transport refers to the movement of materials relative to the average speed of water movement. In water bodies, materials mainly move slowly in the direction of water flow, so it is one of the main factors affecting material migration and diffusion. According to the location and characteristics of the pollutant release source, water flow speed, river channel morphology and other factors, mathematical models can be used to calculate the impact of horizontal transport on the diffusion of radioactive materials. Among them, the commonly used mathematical models are Gaussian model and Lagrangian model. Transport dispersion refers to the phenomenon of discretization, mixing and diffusion of materials due to water flow movement. It is another important factor affecting material migration and diffusion. In inland rivers, the degree of transport dispersion is affected by factors such as the width, depth and flow rate of the river channel. According to the characteristics of transport dispersion, some empirical formulas or models based on physical principles can be used to calculate the diffusion and migration of radioactive materials in water bodies. In actual work, in order to ensure the monitoring accuracy, it is usually necessary to adopt a combination of field observation and data processing. Through the monitoring stations installed in the river, real-time observation of river water quality, water level and river bank changes can be carried out. By analyzing the observation data, relatively accurate data on water flow velocity, water level changes, riverbank erosion, etc. can be obtained, providing a basis for the transmission and diffusion of radioactive substances.

[0081] 2. Dispersion of transport in the direction of water flow and river width

[0082] Through in-depth research on the physical model of migration and diffusion, it can be found that after pollutants enter the water body, in addition to the advection diffusion of water species, there are three processes of diffusion in different directions: 1. Diffusion in the direction of water flow. 2. Diffusion in the direction of river width. 3. Diffusion in the direction of water depth. Combining its movement law with the gradient diffusion theory and the mass balance equation, the basic equation of river transport diffusion (in a uniform and stable water flow field) can be obtained:

[0083]

[0084] Where:

[0085] C—Concentration of pollutants at a certain point in the water body

[0086] t—time

[0087] x, y, z—represent the width of the river and the direction of the water depth respectively

[0088] u—is the velocity of the water flow in the x component (the velocity of the y and z components in a steady water flow field is 0)

[0089] Kx, Ky, Kz—represent the turbulent diffusion coefficients in the x, y, and z directions respectively

[0090] When radioactive pollutants enter a river, they begin to be transported downstream in the water, while being mixed and evenly distributed vertically and across the river width. For wide and shallow rivers, the distance required for uniform vertical mixing of pollutants is proportional to the water depth, while the distance required for uniform horizontal mixing is much longer than the vertical mixing distance. In this process, different river flow rates and water densities will affect the speed of vertical mixing. Without considering turbulence factors, in order to achieve uniform vertical mixing, the distance from the pollutant inlet needs to be 100 times the water depth to be completely mixed. After uniform horizontal mixing, the pollutant concentration at each point on the river section is completely evenly distributed. The upstream river section is the front part of the wastewater entering the river. The river section from the discharge port to the uniform horizontal mixing section is called the mixing process river section, and the river section after uniform horizontal mixing is called the completely mixed river section. Due to the different degrees of dispersion of pollutants in the mixing process river section and the completely mixed river section, different concentration formulas are required for calculation.

[0091] In one embodiment, the emission rate Q of a uniform continuous emission source of nuclear waste water vapor from a nuclear accident is obtained as:

[0092]

[0093] Where X is the concentration of radioactivity in the air at the reference coordinate (x, y, z), and u is the average wind speed;

[0094] According to the emission rate Q, the atmospheric migration model of the concentration of airborne substances in the atmosphere is obtained as follows:

[0095]

[0096] σ y , σ z are the diffusion coefficients in the y and z directions respectively, and h is the release height of the emission source.

[0097] In this embodiment, it is assumed that an accidental radioactive source causes nuclear waste water to evaporate and rise to a certain height, and it is regarded as an isotropic, uniform and continuous emission source Q. The height of the source from the ground is h. Here, we take the wind direction as the x-axis, the horizontal direction perpendicular to the wind direction as the y-axis, and the z-axis perpendicular to the x- and y-axis as the reference system, and set the origin O at the vertical ground of the emission point A. Under flat terrain conditions, when the vertical temperature gradient in the atmosphere is uniform and the wind direction is unchanged, we can assume that the concentration of airborne substances has a symmetrical lateral (y-direction) and vertical (z-direction) distribution at each position downwind. It is assumed that the airborne substances neither disappear nor increase from the smoke cloud when moving downwind.

[0098] In the radiation assessment process, the most noteworthy thing is the air pollution concentration near the ground, which can more directly quantify the dose of pollutants to the human body and determine the degree of harm to the human body. Therefore, when the z value is 0, we can get the pollutant concentration near the ground of the high-level continuous power supply:

[0099]

[0100] At the same time, it can be found from the image that the X function is an even function symmetric about the x-axis. The pollutant concentration is highest in the x-axis direction and shows exponential decay in the +y and -y directions. Therefore, when y=0, the near-ground air pollution concentration can be obtained.

[0101]

[0102] In one embodiment, the atmospheric migration model is modified by using the Dalton evaporation formula to account for the concentration change of radionuclides in the atmosphere due to evaporation:

[0103] W=C(Ee) / Pa

[0104] W is the evaporation rate of the water surface, Ee is the air saturation difference, Pa is the atmospheric pressure, and C is a proportional function related to the wind speed.

[0105] Specifically, we first determine the environmental parameters at the time of the nuclear accident, such as:

[0106] Air temperature (usually expressed in degrees Celsius);

[0107] Air humidity (relative humidity, expressed as a percentage);

[0108] Wind speed (in meters per second);

[0109] Atmospheric pressure (in Pascals)

[0110] Then calculate the saturated water vapor pressure and the actual water vapor pressure, and then use the Dalton evaporation formula to calculate the amount of water lost due to evaporation (and the radionuclides carried therein), and calculate the change in radionuclide concentration due to evaporation based on the evaporation rate. Assuming that the radionuclides are mixed with the evaporated water, the amount of nuclides lost due to evaporation can be calculated, and the original nuclide concentration can be corrected. The updated nuclide concentration is:

[0111] Cnew=Cinitial-W×nuclide ratio

[0112] Cnew is the corrected nuclide concentration, Cinitia is the initial nuclide concentration, W is the evaporation rate, and the nuclide ratio represents the distribution of nuclides in the evaporated water. Finally, based on the effect of wind speed on evaporation rate, the diffusion pattern of nuclide concentration is further adjusted, considering that when wind speed increases, the evaporation rate will also increase, thus affecting the concentration distribution of nuclides in the atmosphere.

[0113] In one embodiment, a two-stage simulation is performed on the migration of radionuclides leaked in a nuclear accident in a river based on a two-dimensional Gaussian diffusion equation, wherein the incomplete diffusion stage is:

[0114]

[0115] Where C is the pollutant concentration at the downstream of the discharge port (x, y), Q is the emission rate, and K is the lateral diffusion coefficient;

[0116] Complete mixing section:

[0117]

[0118] in, F is the sum of river flow and waste flow, B is the width of the river, K is the a represents the diffusion coefficient in the direction of water flow, λ r represents the decay constant of the nuclide;

[0119] The river migration model for the fully mixed section is simplified as:

[0120]

[0121] Introducing correction factor f = e (-λt) Correction for emission rates.

[0122] In actual simulation, By making reasonable simplifications, without considering new pollutants in the transmission process and the long-term deposition of radionuclides on the riverbed, if pollutants are discharged into a river with a uniform and stable flow field at a constant discharge rate, the distribution of pollutant concentrations in the river water can be estimated according to the mixing model of pollutants discharged from continuous point sources in a stable dispersion state medium. Under this condition, shortly after the discharge begins, the distribution of pollutant concentrations at various points in the water will remain constant and will not change over time. The flow velocity and diffusion coefficient of the river water are also constant values. Combined with the diffusion stage of the water flow over the river width, the river simulation is divided into two stages.

[0123] Specifically, when Matlab is used for numerical simulation, the conditions are set as follows:

[0124] 1. The source term is mainly 131 I, 137 Cs can be regarded as a point source on a large spatial scale, and the leakage point is at a height of 200m.

[0125] 2. Radioactive leakage source item value: 131 I. 137 The concentration of Cs in nuclear wastewater is 3×10 10 BQ / L, 3×10 9 BQ / L.

[0126] 3. Assuming the water surface temperature is 25°C and the humidity is 60%, the saturated water vapor pressure is calculated by the Clapeyron equation: 3.17×10 3 Pa, the actual water vapor pressure at an altitude of 200m is 2.21×10 3 Pa.

[0127] 4. 131 I. 137 The half-life of Cs is 8.02d and 30a.

[0128] The point source leakage condition was simulated by Matlab, and the point source dispersion Gaussian distribution model was combined. During the concentration calculation process, the Dalton evaporation formula was used to calculate the pollutants reduced by evaporation.

[0129] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0130] In one embodiment, Figure 2 As shown, a simulation device for near-ground migration of nuclear accident leakage source items is provided, including: an atmospheric migration module 202, a correction module 204, a river migration module 206 and a numerical simulation module 208, wherein:

[0131] The atmospheric migration module 202 is used to simulate the migration of radionuclides released in a nuclear accident in the atmosphere using a Gaussian diffusion model to obtain an atmospheric migration model;

[0132] A correction module 204 is used to correct the atmospheric migration model based on the concentration change of radionuclides in the atmosphere caused by evaporation using the Dalton evaporation formula;

[0133] A river migration module 206 is used to simulate the migration of radioactive nuclides leaked in a nuclear accident in a river based on a two-dimensional Gaussian dispersion equation to obtain a river migration model;

[0134] The numerical simulation module 208 is used to perform numerical simulation on the atmospheric migration model and the river migration model by using Matlab programming to generate a distribution map of nuclide concentration and a diffusion path map.

[0135] In one embodiment, the atmospheric migration module 202 is also used to obtain the emission rate Q of the uniform continuous emission source of nuclear waste water vapor in a nuclear accident as follows:

[0136]

[0137] Where X is the concentration of radioactivity in the air at the reference coordinate (x, y, z), and u is the average wind speed;

[0138] According to the emission rate Q, the atmospheric migration model of the concentration of airborne substances in the atmosphere is obtained as follows:

[0139]

[0140] σ y , σ z are the diffusion coefficients in the y and z directions respectively, and h is the release height of the emission source.

[0141] In one embodiment, the correction module 204 is further used to use the Dalton evaporation formula to correct the atmospheric migration model according to the concentration change of radionuclides in the atmosphere caused by evaporation:

[0142] W=C(Ee) / Pa

[0143] W is the evaporation rate of the water surface, Ee is the air saturation difference, Pa is the atmospheric pressure, and C is a proportional function related to the wind speed.

[0144] In one embodiment, the river migration module 206 is also used to perform a two-stage simulation of the migration of radioactive nuclides leaked in a nuclear accident in a river based on a two-dimensional Gaussian diffusion equation, wherein the incomplete diffusion stage is:

[0145]

[0146] Where C is the pollutant concentration at the downstream of the discharge port (x, y), Q is the emission rate, and K is the lateral diffusion coefficient;

[0147] Complete mixing section:

[0148]

[0149] in, F is the sum of river flow and waste flow, B is the width of the river, K is the a represents the diffusion coefficient in the direction of water flow, λ r represents the decay constant of the nuclide;

[0150] The river migration model for the fully mixed section is simplified as:

[0151]

[0152] Introducing correction factor f = e (-λt) Correction for emission rates.

[0153] For the specific definition of the simulation device for the near-ground migration of nuclear accident leakage source items, please refer to the definition of the simulation method for the near-ground migration of basic nuclear accident leakage source items above, which will not be repeated here. Each module in the above-mentioned simulation device for the near-ground migration of nuclear accident leakage source items can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above-mentioned modules.

[0154] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 3As shown. The computer device includes a processor, a memory, a network interface and a database connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store historical clock error and frequency error data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a radionuclide gamma spectrum analysis method based on sequential Bayesian analysis is implemented.

[0155] Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0156] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method in the above embodiment when executing the computer program.

[0157] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method in the above embodiment are implemented.

[0158] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0159] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for simulating the near-ground migration of nuclear accident leakage sources, characterized in that: The method comprises: The Gaussian diffusion model is used to simulate the migration of radionuclides released in nuclear accidents in the atmosphere, and an atmospheric migration model is obtained; The atmospheric migration model is corrected by using Dalton's evaporation formula to account for changes in the concentration of radionuclides in the atmosphere due to evaporation; The migration of radionuclides leaked in nuclear accidents in rivers is simulated based on the two-dimensional Gaussian dispersion equation, and a river migration model is obtained. The atmospheric migration model and the river migration model are numerically simulated by Matlab programming to generate a distribution map of nuclide concentration and a diffusion path map.

2. The method according to claim 1, characterized in that The Gaussian diffusion model is used to simulate the migration of radionuclides released in nuclear accidents in the atmosphere, and the atmospheric migration model is obtained, including: The emission rate Q of the uniform continuous emission source of nuclear waste water vapor from a nuclear accident is obtained as: Where X is the concentration of radioactivity in the air at the reference coordinate (x, y, z), and u is the average wind speed; According to the emission rate Q, the atmospheric migration model of the concentration of airborne substances in the atmosphere is obtained as follows: σ y , σ z are the diffusion coefficients in the y and z directions respectively, and h is the release height of the emission source.

3. The method according to claim 2, characterized in that The atmospheric migration model is corrected by using the Dalton evaporation formula to account for the concentration change of radionuclides in the atmosphere due to evaporation, including: The atmospheric migration model is corrected by using Dalton's evaporation formula to account for the concentration change of radionuclides in the atmosphere due to evaporation: W=C(Ee) / Pa W is the evaporation rate of the water surface, Ee is the air saturation difference, Pa is the atmospheric pressure, and C is a proportional function related to the wind speed.

4. The method according to claim 1, characterized in that: Based on the two-dimensional Gaussian dispersion equation, the migration of radionuclides leaked in nuclear accidents in rivers is simulated, and a river migration model is obtained, including: Based on the two-dimensional Gaussian diffusion equation, a two-stage simulation of the migration of radionuclides leaked in a nuclear accident in a river is conducted, in which the incomplete diffusion stage is: Where C is the pollutant concentration at the downstream of the discharge port (x, y), Q is the emission rate, and K is the lateral diffusion coefficient; Complete mixing section: in, F is the sum of river flow and waste flow, B is the width of the river, K is the a represents the diffusion coefficient in the direction of water flow, λ r represents the decay constant of the nuclide; The river migration model for the fully mixed section is simplified as: Introducing correction factor f = e (-λt) Correction for emission rates.

5. A simulation device for near-ground migration of nuclear accident leakage source items, characterized in that: The device comprises: The atmospheric migration module is used to simulate the migration of radionuclides released in nuclear accidents in the atmosphere using the Gaussian diffusion model to obtain an atmospheric migration model; A correction module, for correcting the atmospheric migration model based on the concentration change of radionuclides in the atmosphere caused by evaporation using the Dalton evaporation formula; The river migration module is used to simulate the migration of radionuclides leaked in nuclear accidents in rivers based on the two-dimensional Gaussian dispersion equation to obtain a river migration model; The numerical simulation module is used to perform numerical simulation on the atmospheric migration model and the river migration model by using Matlab programming to generate a distribution map of nuclide concentration and a diffusion path map.

6. The device according to claim 5, characterized in that The atmospheric transport module is also used to obtain the emission rate Q of the uniform continuous emission source of nuclear waste water vapor from nuclear accidents: Where X is the concentration of radioactivity in the air at the reference coordinate (x, y, z), and u is the average wind speed; According to the emission rate Q, the atmospheric migration model of the concentration of airborne substances in the atmosphere is obtained as follows: σ y , σ z are the diffusion coefficients in the y and z directions respectively, and h is the release height of the emission source.

7. The device according to claim 6, characterized in that The correction module is also used to use the Dalton evaporation formula to correct the atmospheric migration model according to the concentration change of radionuclides in the atmosphere caused by evaporation: W=C(Ee) / Pa W is the evaporation rate of the water surface, Ee is the air saturation difference, Pa is the atmospheric pressure, and C is a proportional function related to the wind speed.

8. The device according to claim 5, characterized in that The river migration module is also used to simulate the migration of radionuclides leaked in a nuclear accident in a river in two stages based on the two-dimensional Gaussian diffusion equation, where the incomplete diffusion stage is: Where C is the pollutant concentration at the downstream of the discharge port (x, y), Q is the emission rate, and K is the lateral diffusion coefficient; Complete mixing section: in, F is the sum of river flow and waste flow, B is the width of the river, K is the a represents the diffusion coefficient in the direction of water flow, λ r represents the decay constant of the nuclide; The river migration model for the fully mixed section is simplified as: Introducing correction factor f = e (-λt) Correction for emission rates.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 4 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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