Inland nuclear power source item diffusion calculation method and system based on Gaussian smoke flow correction

Abstract

The invention discloses an inland nuclear power source item diffusion calculation method and system based on Gaussian smoke flow correction, and relates to the field of nuclear power plant accident source item atmospheric diffusion assessment, and the method comprises the steps that control flow software transmits input data to mesoscale forecasting software; the mesoscale forecasting software completes scheme setting, the control flow software outputs a grid file, and the self-programming software reads and reconstructs a grid; the control flow software calls system-level source item calculation software to calculate an accident source item; calling mesoscale forecasting software to calculate and output a physical quantity; performing correction judgment on the statistical physical quantity; and calling self-programming software, inputting an accident source item, and traversing the atmospheric area grid to calculate the accident source item by adopting a correction formula. According to the method, the influence of specific'heat island effect ', temperature inversion and the like of an inland city on a background wind field is considered, atmosphere prediction is provided through mesoscale forecasting software, real-time calculation is performed in combination with a correction model, accident source item atmosphere diffusion distribution with relatively high precision is given, empirical conservative hypothesis is reduced, and a reasonable and extensible calculation mode is provided.

Description

Technical Field

[0001] The invention relates to the field of nuclear accident radioactive source term diffusion assessment, and in particular to an inland nuclear power source term diffusion calculation method and system based on Gaussian smoke flow correction. Background Art

[0002] With the widespread application of nuclear technology and nuclear energy, nuclear application facilities and nuclear power plants tend to be built in inland urban areas with high population density. The establishment of inland nuclear power projects has led to the construction of nuclear power plants built on the coast turning to inland cities. At the same time, there are still a large number of nuclear energy utilization experimental devices and radioactive waste repositories in inland urban areas. There are radioactive sources in cities and their surrounding areas. If there are accidents such as fires or explosions, radioactive leaks and spreads may occur.

[0003] The air temperature in urban areas with frequent population activities is higher than that in rural areas, forming an urban heat island circulation. From the perspective of the change in air temperature with altitude, the surface air temperature in urban areas increases with altitude, which is called the "inversion" phenomenon. The atmospheric structure in which the temperature increases with altitude in the vertical direction is called the "mixing layer". The inversion phenomenon in meteorology greatly affects the transportation and diffusion process of urban pollutants in the atmosphere.

[0004] In terms of radionuclide diffusion models, atmospheric diffusion models mainly include CFD turbulence models for microscale simulation, Gaussian models for small-scale simulation, Lagrangian models and Euler models for mesoscale simulation. The existing atmospheric diffusion theory is obtained under certain ideal conditions. For the actual complex situation of atmospheric pollutant diffusion, there is currently no atmospheric diffusion model that can be used under various conditions.

[0005] As for the diffusion of radionuclides in inland urban areas, the meteorological conditions in inland urban areas are more complex and changeable, and the spatial span of the meteorological field is large. If microscale simulation is used, it will undoubtedly increase the amount of calculation and the precision of the work; if mesoscale simulation is used, the diffusion phenomenon of the urban underlying surface cannot be captured. Therefore, it is necessary to modify the widely used Gaussian smoke flow model and establish an improved calculation method for the atmospheric diffusion of accidental radionuclides, which will help to accurately grasp the diffusion and migration laws of radionuclides, so as to formulate targeted emergency measures to ensure the radiation safety of the public. Summary of the invention

[0006] In view of the above-mentioned problems, the present invention is proposed.

[0007] Therefore, the technical problem solved by the present invention is that the meteorological conditions in inland urban areas are complex and changeable, and there are phenomena such as atmospheric inversion (mixing layer) and urban heat island effect. In addition, the meteorological field has a large spatial span, and traditional simulation methods cannot capture the diffusion phenomenon of the urban underlying surface.

[0008] In order to solve the above technical problems, the present invention provides the following technical solution: a method for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction, which comprises the following steps:

[0009] Determine data information based on nuclear power plant type and geographical location;

[0010] The geographical information and grid nesting scheme of the simulation domain of the control flow software are input as static data, and the meteorological parameters are input as dynamic data and passed to the mesoscale numerical weather prediction software;

[0011] The mesoscale numerical weather forecast software completes the setting of the parameterization scheme of the model microphysical process, the control flow software outputs the grid node file of the mesoscale numerical weather forecast software geographic model, and the self-programming software rebuilds the grid model according to the grid node file;

[0012] The control flow software calls the system-level source term calculation and analysis software to perform source term calculations for accident conditions;

[0013] The control flow software calls the mesoscale numerical weather forecast software to calculate and output the spatiotemporal distribution results of various physical quantity fields;

[0014] Statistical analysis of the temporal and spatial variation of various physical quantity parameters at the grid nodes of the mesoscale numerical weather forecast software to determine the vertical inversion and atmospheric dominant wind;

[0015] The control flow software calls the self-programming software, takes the accident condition source term calculation as the calculation input, adopts the modified Gaussian smoke diffusion formula or the composite source correction formula, and considers the inversion correction and the atmospheric dominant wind correction. The self-programming software traverses all the grids in the atmospheric area grid group to perform formula calculations and determine the concentration of the accident source term at each grid.

[0016] As a preferred solution of the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction described in the present invention, wherein: the data information is based on the type of nuclear power plant, the urban area where the nuclear power plant is located is determined, and the grid resolution of the simulation domain is determined according to the environmental conditions of the city and its surroundings;

[0017] The mesh resolution of the domain includes the area range of the simulation domain, the number of mesh nesting layers, and the thickness of each nested mesh layer;

[0018] The grid centers of each layer are the same and the grid centers are by default the geographical location of the nuclear power plant. The geographical information of the simulation domain is determined. According to the altitude data and land use data of different resolutions, the idealized experimental conditions of the simulation domain or the real meteorological parameters of the current area are determined. The underlying surface reflection coefficient of the accident radioactive nuclides, the half-life time of the nuclides, the terminal settling velocity of the nuclides particles, the standard deviation of the normal distribution of the lateral and vertical nuclides concentrations are determined. The specified time for calculation and the time step for division are determined.

[0019] According to the N-layer grid nesting scheme of the simulation domain, the number of horizontal grid points and grid spacing of the center of each layer of grid and the range of the coarse grid parent layer are determined. When the grids are nested, the horizontal resolution is increased from the outermost grid to the innermost grid at a downscaling ratio of 1:(N-1), and the downscaling ratio from the parent layer to the child layer remains the same.

[0020] As a preferred solution of the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction described in the present invention, wherein: the reconstruction of the grid model according to the grid node file is that the control flow software uses the geographical information of the simulation domain as static data, and the idealized experimental conditions or the real meteorological parameters of the area as dynamic data, and the dynamic data is the initialization condition and boundary condition of the numerical simulation calculation. The static data and the dynamic data are both used as input files of the mesoscale numerical weather forecast software. After correcting the Gaussian smoke flow diffusion of the elevated continuous point source and passing the input file to the mesoscale numerical weather forecast software, the control flow software determines the vertical coordinates of the grid of the simulation domain of the mesoscale numerical weather forecast software, and completes the setting of the parameterization scheme of the model microphysical process;

[0021] The control flow software outputs the grid node file according to the geographic model and its vertical coordinates and horizontal grid calculated by the mesoscale numerical weather forecast software;

[0022] Import the grid node file into the self-programming software, establish the grid model of the geographic model, and use the right-hand coordinate system (xyz) as the default coordinate system. Traverse all spatial grids and mark the grids with numbers 1, 2, ..., M, and save the grid spatial positions and corresponding numbers.

[0023] For some grids of the urban underlying surface, if the actual geographical situation is a non-atmospheric area or the volume of the non-atmospheric area accounts for >50%, the grid will be numbered with a1, a2, ..., ai, ..., an and grouped into a non-atmospheric area grid group. If the volume of the non-atmospheric area accounts for <50% or it is completely an atmospheric area, the grid will be numbered with b1, b2, ..., bj, ..., bq and grouped into an atmospheric area grid group.

[0024] As a preferred scheme of the inland nuclear power source diffusion calculation method based on Gaussian smoke correction described in the present invention, the model microphysical process parameterization scheme includes a coarse grid scheme, a fine grid scheme, a long-wave radiation scheme, a short-wave radiation scheme, a near-ground scheme, a parameterization scheme of land surface processes and coupled urban canopy model, cumulus scheme, and boundary layer scheme.

[0025] As a preferred solution of the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction described in the present invention, the source term calculation of the accident condition is that the control flow software calls the system-level source term calculation and analysis software, and according to the specified calculation time, t=0 is taken as the initial state of the accident, the nuclear power plant accident source term result Q(t) is calculated, and output and saved in a file;

[0026] The control flow software completes the settings of the time integration scheme, grid nesting mode, integration step, and calculation output time interval in the mesoscale numerical weather forecast software and saves them;

[0027] The spatiotemporal distribution results of the various physical quantity fields are obtained by the software calling the mesoscale numerical weather forecast software, which performs a time step calculation and outputs the spatiotemporal distribution results of various physical quantity fields;

[0028] The spatiotemporal distribution results include temperature, ground horizontal wind speed, sensible heat flux, latent heat flux, and wind field.

[0029] As a preferred solution of the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction described in the present invention, wherein: the vertical inversion temperature and atmospheric dominant wind judgment are the spatiotemporal distribution results of various physical quantities calculated by the control flow software statistical mesoscale numerical weather forecast software, and according to the spatial position of the grid node, the linear interpolation of each scalar physical quantity at the grid node in the current time and space, and the wind speed of the dominant wind direction of the vector physical quantity wind field at the grid node are calculated, and the parameters of each physical quantity are written in the order of the grid number saved by the self-programming software, and saved as the self-programming software pre-processing data file at the current time step;

[0030] The control flow software determines the vertical temperature gradient of the grid model at the current time step based on the spatial position of the grid node and the corresponding temperature in the pre-processing data file. The expression is:

[0031]

[0032] Where γ is the temperature gradient; T is the temperature, and z is the vertical height;

[0033] Determine whether the temperature gradient γ>0. If there is a temperature inversion, the control flow software uses the grid number and the required temperature inversion correction signal as the basis for the temperature inversion correction and writes it into the file. If there is no temperature inversion phenomenon γ<0, the control flow software calls the self-programming software, and the self-programming software reads the pre-processing data file as the initial state of the atmospheric diffusion of the accident source item at the current time step.

[0034] As a preferred solution of the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction described in the present invention, wherein: the determination of the accident source term concentration at each grid is that the control flow software calls the self-programming software, and the self-programming software reads the nuclear power plant accident source term result Q(x,Δt) at the current time step as the boundary condition for atmospheric diffusion calculation;

[0035] The self-programming software performs the same time step simulation as the mesoscale numerical weather forecast software on the jth grid (j=1~q) of the atmospheric regional grid group, taking into account the influence of various removal and migration transformation processes, and the modified elevated continuous point source Gaussian smoke diffusion is expressed as:

[0036]

[0037] Where q(x, y, z; H) is the average concentration of radionuclides at the space (x, y, z); Q(Δt) is the radionuclide source term; (x, y, z) is the position of the computational grid node; is the average wind speed of the environment, u is the ambient wind speed, is the effect of gravity sedimentation of large particles, V s is the final particle settling velocity, α is the underlying surface reflection coefficient, is the half-life of the nuclide, σ y , σ z is the standard deviation of the normal distribution of radionuclide concentration in the crosswind direction y and vertical direction z;

[0038] Determine the inversion correction signal. If there is an inversion phenomenon, the modified elevated continuous point source Gaussian smoke diffusion formula is calculated with y = 0 and the height Hm of the inversion layer. and x m ;

[0039] in, is the standard deviation of the normal distribution of radionuclide concentration in the vertical direction z corresponding to the maximum value of the concentration; x m is the distance where the highest ground concentration occurs;

[0040] When the downwind distance x≤xm, the modified elevated continuous point source Gaussian smoke diffusion formula is used for calculation. When the downwind distance x≥2xm, the modified formula for composite source is used for calculation within the range of (xm, 2xm) by logarithmic interpolation of concentration. The expression is:

[0041]

[0042] in, are the average wind speed of the i-th grid in the current time step;

[0043] The default dominant wind in the self-programming software is the x-axis. If the current time step is the first time step, and there is an angle θ between the dominant wind in the ith grid and the x-axis, the Gaussian smoke diffusion formula needs to be corrected. The expression is:

[0044]

[0045] Among them, (x, y) is the default coordinate system direction of the self-programming software, and (i, j) is the grid node coordinate;

[0046] If the current time step is not the first time step, and the dominant wind in the ith grid is at an angle α to the dominant wind in the grid under the previous time step, another correction is made to the Gaussian smoke diffusion formula, which is expressed as follows:

[0047]

[0048] Where (x', y') is the new coordinate, Δt is the time step, is the average wind speed of the i-th grid in the current time step, otherwise, no correction is performed;

[0049] After completing the calculation of the current time step, the accident source item concentration of each grid in all atmospheric area grid groups is traversed, and the files are output and saved as the source items calculated in the next time step. The control flow software calls the mesoscale numerical weather forecast module according to the divided time steps to calculate and output the physical quantities; statistical physical quantities are used for correction and judgment; the self-programming software is called, the accident source items are input, and the correction formula is used to traverse the atmospheric area grids to calculate the accident source items until the specified calculation time is reached.

[0050] Another object of the present invention is to provide an inland nuclear power source diffusion calculation system based on Gaussian smoke flow correction, which can solve the shortcomings of existing systems in simulation accuracy, calculation efficiency and emergency response through modular design, dynamic data input, accurate numerical simulation and correction algorithm.

[0051] In order to solve the above technical problems, the present invention provides the following technical solutions: an inland nuclear power source diffusion calculation system based on Gaussian smoke flow correction, comprising: a data input module, a mesoscale numerical weather forecast module, a grid reconstruction and management module, an accident source term calculation module and a diffusion calculation and correction module;

[0052] The data input module provides initial geographic information and meteorological parameters, which are input into the mesoscale numerical weather forecast module and the grid reconstruction and management module;

[0053] The mesoscale numerical weather forecast module is to set the model microphysical process parameterization scheme, perform mesoscale numerical weather forecast calculations, and output the spatiotemporal distribution results of various physical quantity fields;

[0054] The grid reconstruction and management module is to reconstruct the grid model, determine the grid center position, set the grid resolution, and divide the atmospheric region and non-atmospheric region grid groups according to the grid node file output by the mesoscale numerical weather forecast software;

[0055] The accident source term calculation module calls the system-level source term calculation and analysis software to perform source term calculations for accident conditions, sets the time integration scheme, grid nesting method, integration step length and calculation output time interval, and calculates the accident source term results of the nuclear power plant;

[0056] The diffusion calculation and correction module uses self-programming software to read the source term calculation results, adopts the modified Gaussian smoke flow diffusion formula or the composite source correction formula, considers the influence of inversion temperature and atmospheric dominant wind, calculates the accident source term concentration at each grid, outputs and saves the results as the input of the next time step until all calculation time steps are completed.

[0057] A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction as described above are implemented.

[0058] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction as described above.

[0059] Beneficial effects of the invention: The invention takes into account the influence of the "heat island effect" and temperature inversion phenomenon unique to inland cities on the background wind field. The invention provides atmospheric forecasts for the region through mesoscale numerical weather forecast software, and combined with the real-time calculation of the modified Gaussian smoke model, it can provide a high-precision atmospheric diffusion distribution of accident source items, avoiding the use of traditional empirical coefficients; the invention provides a reasonable model for calculating atmospheric diffusion of inland nuclear power accident source items, which can be expanded according to the meteorological characteristics of different regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0061] Figure 1 This is an overall flow chart of the inland nuclear power source diffusion calculation method based on Gaussian smoke correction provided in the first embodiment of the present invention.

[0062] Figure 2A comparison chart of load balancing rates of various algorithms under the same task request in the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction provided in the second embodiment of the present invention.

[0063] Figure 3 A schematic diagram of an N-grid nesting scheme for a Gaussian smoke-modified inland nuclear power source diffusion calculation method provided in the third embodiment of the present invention.

[0064] Figure 4 A schematic diagram of constructing a grid model based on a geographic model in a method for calculating the diffusion of inland nuclear power sources based on Gaussian smoke flow correction provided in a third embodiment of the present invention.

[0065] Figure 5 A comparison diagram of the results of atmospheric inversion layer correction at a certain grid node in the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction provided in the third embodiment of the present invention.

[0066] Figure 6 A comparison diagram of the results of variable wind direction correction at a certain grid node in the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction provided in the third embodiment of the present invention.

[0067] Figure 7 A schematic diagram of atmospheric diffusion simulation of a nuclear power plant at the peak moment of an accident condition nuclide after correction considering multiple factors in the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction provided in the third embodiment of the present invention. DETAILED DESCRIPTION

[0068] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0069] Example 1, reference Figure 1 As one embodiment of the present invention, a method for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction is provided, comprising:

[0070] Step 1: Determine the type of nuclear power plant, determine the urban area where the nuclear power plant is located, and determine the grid resolution of the simulation domain according to the environmental conditions of the city and its surroundings (within 50km), that is, the regional scope of the simulation domain, the number of grid nesting layers, the thickness of each nested grid, the center of each grid layer is the same and the grid center defaults to the geographical location of the nuclear power plant (that is, the accident source item). Determine the geographical information of the simulation domain, including altitude data and land use data of different resolutions, determine the idealized experimental conditions of the simulation domain or the real meteorological parameters of the area, determine the underlying surface reflection coefficient of the accident radioactive nuclides, the half-life time of the nuclides, the terminal settling velocity of the nuclides particles, the standard deviation of the normal distribution of the lateral and vertical nuclides concentration, determine the specified time for calculation and the time step. The specified calculation time can be in days, months, quarters, and years. The time step can be divided according to the time period from sunrise to sunset. The subsequent calculation process is as follows: Figure 1 shown.

[0071] It should be further explained that the specified calculation time can be the same as or longer than the calculation time of the accident condition source term. The atmospheric diffusion model established by this method can be calculated for several months (or the number of days that the current weather forecast accuracy can reach the required level) because it is combined with real-time weather forecasts.

[0072] For a particular radionuclide, a time step smaller than its half-life can capture the variation and distribution of the nuclide in the atmospheric dispersion.

[0073] Step 2: According to the N-layer grid nesting scheme of the simulation domain, determine the number of horizontal grid points and grid spacing of the center of each layer of grid and the range of the coarse grid (mother layer), and meet the requirements that the horizontal resolution increases from the outermost grid to the innermost grid at a downscaling ratio of 1:(N-1) when the grids are nested, and the downscaling ratio from the mother layer to the child layer remains the same, such as Figure 3 shown.

[0074] Step 3: The control flow software uses the geographic information of the simulation domain as static data and the idealized experimental conditions or the real meteorological parameters of the area as dynamic data. The dynamic data is the initialization condition and boundary condition of the numerical simulation calculation. Both static data and dynamic data are used as input files of the mesoscale numerical weather forecast software.

[0075] Step 4: After the control flow software passes the input file to the mesoscale numerical weather prediction software, the control flow software determines the vertical coordinates of the mesoscale numerical weather prediction software simulation domain grid and completes the setting of the model microphysical process parameterization scheme, including coarse grid scheme, fine grid scheme, longwave radiation scheme, shortwave radiation scheme, near-ground scheme, parameterization scheme of land surface processes and coupled urban canopy model, cumulus scheme, and boundary layer scheme.

[0076] Step 5: The control flow software outputs the grid node file according to the geographic model and its vertical coordinates and horizontal grid calculated by the mesoscale numerical weather forecast software.

[0077] Step 6: The control flow software imports the grid node file into the self-programming software, and the self-programming software automatically builds the grid model of the geographic model, such as Figure 3 The default coordinate system shown is the right-hand coordinate system (xyz). All spatial grids are traversed, and the grids are marked with numbers 1, 2, ..., M to save the spatial positions of the grids and the corresponding numbers. For some grids of the urban underlying surface that are non-atmospheric areas or contain non-atmospheric areas with a volume ratio of >50% due to actual geographical conditions, the grids are numbered a1, a2, ..., ai, ..., an and grouped into non-atmospheric area grid groups. If the volume ratio of non-atmospheric areas is <50% or it is completely an atmospheric area, the grids are numbered b1, b2, ..., bj, ..., bq and grouped into atmospheric area grid groups.

[0078] Step 7: The control flow software calls the system-level source term calculation and analysis software. The source term calculation and analysis software calculates the nuclear power plant accident source term result Q(t) based on the specified calculation time and takes t=0 as the initial state of the accident, outputs it and saves it in a file.

[0079] It should be further explained that the calculation result Q(t) of the nuclear power plant accident source term is obtained through system-level source term calculation and analysis software, such as MALCOR for pressurized water reactors and software independently developed by scientific research institutes, which can realize the calculation of accident condition source terms. This type of software links the accident process of the nuclear power plant with the distribution of radioactive nuclides released in the reactor.

[0080] Step 8: The control flow software completes the settings of the time integration scheme, grid nesting method, integration step, and calculation output time interval in the mesoscale numerical weather forecast software and saves them.

[0081] Step 9: The control flow software calls the mesoscale numerical weather forecast software, which performs a time step calculation and outputs the spatiotemporal distribution results of various physical quantity fields, including temperature, ground horizontal wind speed, sensible heat flux, latent heat flux, and wind field.

[0082] Step 10: The control flow software counts the spatiotemporal distribution results of each physical quantity calculated by the mesoscale numerical weather forecast software, and calculates the linear interpolation of each scalar physical quantity at the grid node in the current time and space according to the spatial position of the grid node saved by the self-programming software. The grid node value of the vector physical quantity, i.e. the wind field, counts the wind speed of the dominant wind direction. To determine, and write the parameters of each physical quantity in the order of the grid numbers saved by the self-programming software, and save it as the pre-processing data file of the self-programming software under the current time step.

[0083] Step 11: The control flow software determines the vertical temperature gradient of the grid model at the current time step, i.e., the vertical temperature decrease rate, based on the spatial position of the grid node and the corresponding temperature in the pre-processing data file. Is there γ>0? If there is a temperature inversion, the control flow software uses the grid number and the required temperature inversion correction signal as the basis for the temperature inversion correction and writes it into the file. If there is no temperature inversion phenomenon, that is, γ<0, the control flow software calls the self-programming software, and the self-programming software reads the pre-processing data file as the initial state of the atmospheric diffusion of the accident source item at the current time step.

[0084] Step 12: The control flow software calls the self-programming software, and the self-programming software reads the result of the nuclear power plant accident source term Q(x,Δt) at the current time step as the boundary condition for the atmospheric diffusion calculation;

[0085] Step 13: The control flow software calls the self-programming software, and the self-programming software performs the calculation of the modified elevated continuous point source Gaussian smoke diffusion formula within the time step of step 6 for the jth grid (j=1~q) of the atmospheric region grid group, considering the influence of various removal and migration transformation processes, as shown in Formula 1:

[0086]

[0087] in, is the effect of gravity sedimentation of large particles, V s is the final particle settling velocity, α is the underlying surface reflection coefficient, is the half-life of the nuclide, σ y , σ z is the standard deviation of the normal distribution of radionuclide concentration in the crosswind direction y and the vertical direction z.

[0088] Step 14: Determine the inversion correction signal of step 11. If there is an inversion phenomenon, the correction formula of step 13 is calculated with y=0 and the height Hm of the inversion layer. and x m , when the downwind distance (i.e., the grid position relative to the source position) is ≤ xm, then the correction formula in step 13 is used for calculation. If the downwind distance is ≥ 2xm, then the composite source correction is used (Formula 2 replaces Formula 1) and the concentration is calculated by logarithmic interpolation within the range of (xm, 2xm);

[0089]

[0090] Step 15: Since the radionuclide varies with the source distance x, it can be expressed as Formula 3:

[0091]

[0092] Step 16: The default dominant wind of the self-programming software is the x-axis. If the current time step is the first time step, and there is an angle θ between the dominant wind in the i-th grid and the x-axis, the Gaussian smoke diffusion formula needs to be corrected. The correction method is shown in Formula 4:

[0093]

[0094] Where (x, y) is the default coordinate system direction of the self-programming software, (i, j) is the grid node coordinate, if the current time step is not the first time step, and the dominant wind in the i-th grid is at an angle α to the dominant wind of the grid in the previous time step, then use the correction method of formula 4:

[0095]

[0096] Where (x', y') is the new coordinate, Δt is the time step, is the average wind speed of the ith grid in the current time step, otherwise, no correction is made.

[0097] Step 17: After the self-programming software completes the calculation of the current time step, it traverses the accident source item concentration of each grid in all atmospheric area grid groups, outputs and saves the file as the source item Q calculated in the next time step mesh-i (Δt).

[0098] Step 18: Repeat steps 9-17 at the divided time steps until the specified calculation time is reached.

[0099] It should be further explained that the source items of each grid node of the atmospheric region grid group have a time sequence. In particular, for the source items that have diffused to the node, in the next time step calculation, due to the change of the dominant wind direction, the source items of the node can be calculated by superimposing the source items (at the center of the grid) being released by the accident condition of the nuclear power plant and diffused to the node at the current time point.

[0100] Example 2, reference Figure 2 , which is an embodiment of the present invention, provides a system for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction, including: a data collection module, a control algorithm module, an equipment control module, a status display module and a learning optimization module.

[0101] The data collection module collects the operating status data of new energy equipment and grid voltage data in real time.

[0102] The control algorithm module is responsible for calculating the optimized equipment operation strategy based on the collected data to achieve collaborative work among devices.

[0103] The device control module sends control instructions to the new energy equipment based on the calculation results of the control algorithm module, so that the equipment operates according to the optimized strategy.

[0104] The status display module visualizes the equipment status and grid voltage status information, allowing operators to intuitively understand the current operating conditions.

[0105] The learning optimization module uses machine learning algorithms to automatically learn and optimize the control strategy of equipment from historical data, thereby improving the effectiveness and efficiency of grid voltage support.

[0106] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0107] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0108] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0109] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0110] Example 3, reference Figure 3 to Figure 7 This is another embodiment of the present invention. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments. This embodiment experiments the existing traditional method and the method of this embodiment respectively.

[0111] Figure 4 The figure shows the appearance of the surrounding area (100km) of a nuclear power plant in a certain place. The nuclear power plant is located at the origin of the coordinate system (not shown in the figure). Figure 3 The grid nesting scheme of this implementation plan adopts a four-layer grid nesting scheme, and the radionuclide calculated for the accident condition source term is I-131. Through the technical solution of the present invention, this implementation plan calculates the sensitivity analysis of the chimney height and the vertical atmospheric inversion (mixing layer height) and the different average wind speeds in the dominant wind direction. Figure 5 This is a sensitivity analysis of the chimney height and the vertical atmospheric inversion (mixing layer height). When the chimney height is fixed, the lower the vertical atmospheric inversion (mixing layer height), that is, the closer the inversion layer is to the nuclear power plant, the greater the impact on the activity concentration of radionuclides in the downwind direction. Figure 6The sensitivity analysis of different average wind speeds in the dominant wind direction shows that the smaller the wind speed, the greater the change in the nuclide concentration in the downwind distance. The superiority of this technical solution can be seen through the sensitivity analysis. Combined with the actual environmental conditions of a certain place, this implementation plan gives the atmospheric diffusion situation at the peak concentration of I-131, such as Figure 7 As shown, the dominant wind direction at this time is southeast.

[0112] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. The inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction is characterized by: include: Determine data information based on nuclear power plant type and geographical location; The geographical information and grid nesting scheme of the simulation domain of the control flow software are input as static data, and the meteorological parameters are input as dynamic data and passed to the mesoscale numerical weather prediction software; The mesoscale numerical weather forecast software completes the setting of the parameterization scheme of the model microphysical process, the control flow software outputs the grid node file of the mesoscale numerical weather forecast software geographic model, and the self-programming software rebuilds the grid model according to the grid node file; The control flow software calls the system-level source term calculation and analysis software to perform source term calculations for accident conditions; The control flow software calls the mesoscale numerical weather forecast software to calculate and output the spatiotemporal distribution results of various physical quantity fields; Statistical analysis of the temporal and spatial variation of various physical quantity parameters at the grid nodes of the mesoscale numerical weather forecast software to determine the vertical temperature inversion and atmospheric dominant wind; The control flow software calls the self-programming software, takes the accident condition source term calculation as the calculation input, adopts the modified Gaussian smoke diffusion formula or the composite source correction formula, and considers the inversion correction and the atmospheric dominant wind correction. The self-programming software traverses all the grids in the atmospheric area grid group to perform formula calculations and determine the concentration of the accident source term at each grid.

2. The inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction as claimed in claim 1 is characterized by: The data information is to determine the urban area where the nuclear power plant is located according to the type of the nuclear power plant, and to determine the grid resolution of the simulation domain according to the environmental conditions of the city and its surroundings; The mesh resolution of the domain includes the area range of the simulation domain, the number of mesh nesting layers, and the thickness of each nested mesh layer; The grid centers of each layer are the same and the grid centers are by default the geographical location of the nuclear power plant. The geographical information of the simulation domain is determined. According to the altitude data and land use data of different resolutions, the idealized experimental conditions of the simulation domain or the real meteorological parameters of the current area are determined. The underlying surface reflection coefficient of the accident radioactive nuclides, the half-life time of the nuclides, the terminal settling velocity of the nuclides particles, the standard deviation of the normal distribution of the lateral and vertical nuclides concentrations are determined. The specified time for calculation and the time step for division are determined. According to the N-layer grid nesting scheme of the simulation domain, the number of horizontal grid points and grid spacing of the center of each layer of grid and the range of the coarse grid parent layer are determined. When the grids are nested, the horizontal resolution is increased from the outermost grid to the innermost grid at a downscaling ratio of 1:(N-1), and the downscaling ratio from the parent layer to the child layer remains the same.

3. The method for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction according to claim 2 is characterized in that: The said reconstruction of the grid model according to the grid node file is that the control flow software uses the geographical information of the simulation domain as static data, and the idealized experimental conditions or the real meteorological parameters of the area as dynamic data. The dynamic data is the initialization conditions and boundary conditions of the numerical simulation calculation. The static data and the dynamic data are both used as input files of the mesoscale numerical weather forecast software. After the elevated continuous point source Gaussian smoke diffusion is corrected and the input file is passed to the mesoscale numerical weather forecast software, the control flow software determines the vertical coordinates of the grid of the simulation domain of the mesoscale numerical weather forecast software, and completes the setting of the parameterization scheme of the model microphysical process; The control flow software outputs the grid node file according to the geographic model and its vertical coordinates and horizontal grid calculated by the mesoscale numerical weather forecast software; Import the grid node file into the self-programming software, establish the grid model of the geographic model, and use the right-hand coordinate system (xyz) as the default coordinate system. Traverse all spatial grids and mark the grids with numbers 1, 2, ..., M, and save the grid spatial positions and corresponding numbers. For some grids of the urban underlying surface, if the actual geographical situation is a non-atmospheric area or the volume of the non-atmospheric area accounts for >50%, the grid will be numbered with a1, a2, ..., ai, ..., an and grouped into a non-atmospheric area grid group. If the volume of the non-atmospheric area accounts for <50% or it is completely an atmospheric area, the grid will be numbered with b1, b2, ..., bj, ..., bq and grouped into an atmospheric area grid group.

4. The method for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction according to claim 3 is characterized in that: The model microphysical process parameterization scheme includes a coarse grid scheme, a fine grid scheme, a long-wave radiation scheme, a short-wave radiation scheme, a near-ground scheme, a parameterization scheme for land surface processes, and is coupled with an urban canopy model, a cumulus scheme, and a boundary layer scheme.

5. The method for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction according to claim 4 is characterized in that: The source term calculation of the accident condition is that the control flow software calls the system-level source term calculation and analysis software, calculates the nuclear power plant accident source term result Q(t) according to the specified calculation time, takes t=0 as the initial state of the accident, outputs and saves it in a file; The control flow software completes the settings of the time integration scheme, grid nesting mode, integration step, and calculation output time interval in the mesoscale numerical weather forecast software and saves them; The spatiotemporal distribution results of the various physical quantity fields are obtained by the software calling the mesoscale numerical weather forecast software, which performs a time step calculation and outputs the spatiotemporal distribution results of various physical quantity fields; The spatiotemporal distribution results include temperature, ground horizontal wind speed, sensible heat flux, latent heat flux, and wind field.

6. The method for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction according to claim 5 is characterized in that: The vertical inversion and atmospheric dominant wind judgment are the spatiotemporal distribution results of various physical quantities calculated by the mesoscale numerical weather forecast software using the control flow software to count, and the linear interpolation of various scalar physical quantities at the grid nodes in the current space and time, as well as the wind speed of the dominant wind direction of the vector physical quantity wind field at the grid nodes are calculated according to the spatial position of the grid nodes, and the parameters of various physical quantities are written in the order of the grid numbers saved by the self-programming software, and saved as the pre-processing data file of the self-programming software at the current time step; The control flow software determines the vertical temperature gradient of the grid model at the current time step based on the spatial position of the grid node and the corresponding temperature in the pre-processing data file. The expression is: Where γ is the temperature gradient; T is the temperature, and z is the vertical height; Determine whether the temperature gradient γ>0. If there is a temperature inversion, the control flow software uses the grid number and the required temperature inversion correction signal as the basis for the temperature inversion correction and writes it into the file. If there is no temperature inversion phenomenon γ<0, the control flow software calls the self-programming software, and the self-programming software reads the pre-processing data file as the initial state of the atmospheric diffusion of the accident source item at the current time step.

7. The method for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction according to claim 6, characterized in that: Determining the concentration of the accident source term at each grid is that the control flow software calls the self-programming software, and the self-programming software reads the result Q(x,Δt) of the accident source term of the nuclear power plant at the current time step as the boundary condition for the atmospheric diffusion calculation; The self-programming software performs the same time step simulation as the mesoscale numerical weather forecast software on the jth grid (j=1~q) of the atmospheric regional grid group, taking into account the influence of various removal and migration transformation processes, and the modified elevated continuous point source Gaussian smoke diffusion is expressed as: Where q(x, y, z; H) is the average concentration of radionuclides at the space (x, y, z); Q(Δt) is the radionuclide source term; (x, y, z) is the position of the computational grid node; is the average wind speed of the environment, u is the ambient wind speed, is the effect of gravity sedimentation of large particles, V s is the final particle settling velocity, α is the underlying surface reflection coefficient, is the half-life of the nuclide, σ y , σ z is the standard deviation of the normal distribution of radionuclide concentration in the crosswind direction y and vertical direction z; Determine the inversion correction signal. If there is an inversion phenomenon, the modified elevated continuous point source Gaussian smoke diffusion formula is calculated with y = 0 and the height Hm of the inversion layer. and x m ; in, is the standard deviation of the normal distribution of radionuclide concentration in the vertical direction z corresponding to the maximum value of the concentration; x m is the distance where the highest ground concentration occurs; When the downwind distance x≤xm, the modified elevated continuous point source Gaussian smoke diffusion formula is used for calculation. When the downwind distance x≥2xm, the modified formula for composite source is used for calculation within the range of (xm, 2xm) by logarithmic interpolation of concentration. The expression is: in, are the average wind speed of the i-th grid in the current time step; The default dominant wind in the self-programming software is the x-axis. If the current time step is the first time step, and there is an angle θ between the dominant wind in the ith grid and the x-axis, the Gaussian smoke diffusion formula needs to be corrected. The expression is: Among them, (x, y) is the default coordinate system direction of the self-programming software, and (i, j) is the grid node coordinate; If the current time step is not the first time step, and the dominant wind in the ith grid is at an angle α to the dominant wind in the grid under the previous time step, another correction is made to the Gaussian smoke diffusion formula, which is expressed as follows: Where (x', y') is the new coordinate, Δt is the time step, is the average wind speed of the i-th grid in the current time step, otherwise, no correction is performed; After completing the calculation of the current time step, the accident source item concentration of each grid in all atmospheric area grid groups is traversed, and the files are output and saved as the source items calculated in the next time step. The control flow software calls the mesoscale numerical weather forecast module according to the divided time steps to calculate and output the physical quantities; statistical physical quantities are used for correction and judgment; the self-programming software is called, the accident source items are input, and the correction formula is used to traverse the atmospheric area grids to calculate the accident source items until the specified calculation time is reached.

8. A system using the inland nuclear power source diffusion calculation method based on Gaussian smoke flow correction as claimed in any one of claims 1 to 7, characterized in that: It includes data input module, mesoscale numerical weather forecast module, grid reconstruction and management module, accident source term calculation module and diffusion calculation and correction module; The data input module provides initial geographic information and meteorological parameters, which are input into the mesoscale numerical weather forecast module and the grid reconstruction and management module; The mesoscale numerical weather forecast module is to set the model microphysical process parameterization scheme, perform mesoscale numerical weather forecast calculations, and output the spatiotemporal distribution results of various physical quantity fields; The grid reconstruction and management module is to reconstruct the grid model, determine the grid center position, set the grid resolution, and divide the atmospheric region and non-atmospheric region grid groups according to the grid node file output by the mesoscale numerical weather forecast software; The accident source term calculation module calls the system-level source term calculation and analysis software to perform source term calculations for accident conditions, sets the time integration scheme, grid nesting method, integration step length and calculation output time interval, and calculates the accident source term results of the nuclear power plant; The diffusion calculation and correction module uses self-programming software to read the source term calculation results, adopts the modified Gaussian smoke flow diffusion formula or the composite source correction formula, considers the influence of inversion temperature and atmospheric dominant wind, calculates the accident source term concentration at each grid, outputs and saves the results as the input of the next time step until all calculation time steps are completed.

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 for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction according to any one of claims 1 to 7 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 for calculating the diffusion of inland nuclear power source items based on Gaussian smoke flow correction as described in any one of claims 1 to 7 are implemented.

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