Forecasting and early warning methods for inert material release and atmospheric diffusion in various types of explosion events

Abstract

This invention discloses a forecasting and early warning method for the release and atmospheric diffusion of inert substances in various types of explosion events, belonging to the field of explosion consequence analysis technology. It includes: Step 1: Parameterizing the initial plume source strength to describe the release process of radioactive materials, biotoxic compounds, and malodorous inert substances; Step 2: Using virtual point cloud technology to create a three-dimensional spatial grid of the initial plume source strength; Step 3: Conducting short-term diffusion simulations for each virtual point source to form a three-dimensional gridded file of stable plume source strength; Step 4: Using atmospheric diffusion model tools to simulate the diffusion of inert substances at multiple scales and time periods, combining the atmospheric concentration of inert substances and dry and wet deposition fluxes to conduct an impact assessment of the explosion event. This invention can provide decision-makers with rapid, scientific, and effective suggestions and plans for personnel evacuation or emergency decisions, thereby protecting public and environmental safety.

Description

Technical Field

[0001] This invention relates to the field of explosion consequence analysis technology, and in particular to forecasting and early warning methods for the release of inert substances and atmospheric diffusion in various types of explosion events. Background Technology

[0002] Forecasting and early warning systems for the release and atmospheric diffusion of inert materials in various types of explosions have become a national necessity for war preparedness and emergency response. Current technologies typically treat the explosion plume as a single source intensity and input it into atmospheric diffusion models to simulate the atmospheric diffusion and deposition of various inert materials over 3 hours to 7 days after the event, determining the level and extent of environmental impact. However, in reality, the initial source intensity range of a large-scale explosion plume can exceed 1 km. Directly inputting this plume as a point source into the atmospheric diffusion model would severely underestimate the impact range of atmospheric diffusion and deposition after the release of inert materials.

[0003] Therefore, a forecasting and early warning method is needed to predict and warn of the release of inert materials and atmospheric diffusion in various types of explosion events, so as to provide forecasts and early warnings of emergencies within a designated area. Summary of the Invention

[0004] The purpose of this invention is to propose a forecasting and early warning method for the release of inert materials and atmospheric diffusion in various types of explosion events, comprising the following steps:

[0005] Step 1: Considering the explosion mode, explosion yield, and detonation location, parameterize the initial smoke source strength to describe the release process of radioactive materials, biotoxic compounds, and malodorous inert substances;

[0006] Step 2: Use virtual point cloud technology to create a three-dimensional spatial mesh of the initial smoke source intensity to reflect the spatiotemporal morphology of the initial smoke.

[0007] Step 3: Conduct short-term diffusion simulations for each virtual point source to generate a three-dimensional mesh file of the stable plume source strength, in order to reflect the spatiotemporal morphology of the stable plume;

[0008] Step 4: Using atmospheric diffusion modeling tools, conduct multi-scale and multi-time-period diffusion simulations of inert materials, and combine atmospheric concentration of inert materials and dry and wet deposition fluxes to conduct an impact assessment of the explosion event.

[0009] The explosion types in step 1 include high-altitude explosions, ground explosions, sea surface explosions, and deep-sea explosions.

[0010] The initial smoke cloud height, top height, and radius are characterized based on the explosive yield.

[0011] Step 2 specifically includes the following sub-steps:

[0012] Step 21: Unify the latitude and longitude of the smoke cloud center into the universal transverse Mercator grid system and convert it into projected coordinates in meters;

[0013] Step 22: Based on the projection coordinates and the number of point clouds in different directions, obtain the location of each virtual point cloud and its emission amount;

[0014] Step 23: Convert the projected coordinates in Step 21 into geographic coordinates in latitude and longitude units to form a virtual point cloud 3D grid emission file that includes virtual point cloud latitude and longitude, altitude, and emission information.

[0015] Step 3 specifically includes the following sub-steps:

[0016] Step 31: Calculate the stabilization time of the entire stable smoke plume, and calculate the time step and simulation steps based on the morphology;

[0017] Step 32: Calculate the spatial location of each virtual point at time t;

[0018] Step 33: Repeatedly calculate the three-dimensional position changes of the virtual points based on the time step and the number of simulation steps to obtain the spatiotemporal morphology of the stable smoke plume after short-term diffusion.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. This invention generates equidistant virtual point cloud files, avoiding the problem of difficulty in generating equidistant virtual point cloud files based on latitude and longitude.

[0021] 2. The method of the present invention can provide decision-makers with quick, scientific and effective suggestions and plans for personnel evacuation or emergency decisions, thereby protecting public and environmental safety. Attached Figure Description

[0022] Figure 1 This is a flowchart of the forecasting and early warning method for the release of inert materials and atmospheric diffusion in various types of explosion events according to the present invention;

[0023] Figure 2 This is a rendering of a high-altitude explosion.

[0024] Figure 3 This is an illustration of a near-ground explosion.

[0025] Figure 4 This is a rendering of a naval explosion.

[0026] Figure 5 The virtual point cloud construction diagram is the initial source strength 5 minutes after an explosion with a point cloud interval of 1km.

[0027] Figure 6 The virtual point cloud construction diagram is the initial source strength of an explosion 5 minutes after a point cloud interval of 5km.

[0028] Figure 7 This is a graph showing the vertical diffusion changes of smoke particles during the stable period of 1 hour.

[0029] Figure 8 Point cloud map of a 9km study area in Shanxi Province;

[0030] Figure 9 This is a spatial distribution map of the explosion point cloud;

[0031] Figure 10 For I 131 Graph showing the variation of grid-averaged hourly concentration with increasing layer number and time;

[0032] Figure 11(a) shows the 20|131 layer I 131 A 24-hour grid average concentration map;

[0033] Figure 11(b) shows the 5|131 layer I 131 A 24-hour grid average concentration map;

[0034] Figure 11(c) shows layer I of layer 1|131. 131 The average concentration of the grid over 24 hours. Detailed Implementation

[0035] This invention proposes a forecasting and early warning method for the release of inert materials and atmospheric diffusion in various types of explosion events. The invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] Figure 1 The flowchart below shows the forecasting and early warning method for the release of inert materials and atmospheric diffusion in various types of explosion events according to the present invention.

[0037] (1) Initial smoke source strength parameterization

[0038] Figure 2 This is a rendering of a high-altitude explosion. The shape and spatial location of the smoke plume after the explosion are the basis for describing the spatiotemporal distribution characteristics of inert materials and constructing a virtual point cloud for explosions. For high-altitude explosions, based on the method of estimating the geometric dimensions of stable smoke plumes, the height, thickness, radius, and density distribution of inert materials of the smoke plume are described using formulas (1) to (6), with a spherical smoke plume as the basis. The top height, bottom height, and radius of the smoke plume can be estimated by the user-defined explosion equivalent, as shown in formulas (1) to (3). The formulas for calculating the vertical and horizontal diffusion coefficients and the relative density of inert materials after the explosion are (4) to (6).

[0039] H B =a*yield b (1)

[0040] H T=c*yield d (2)

[0041] R C =exp(6.7553+0.32055*ln(yield)+0.01137478((ln(yield)) 2 (3)

[0042]

[0043] σ h =0.18*(44+6.1*ln(yield)-0.205*|ln(yield)+2.42|*(ln(yield)+2.42))(5)

[0044]

[0045] In the formula, yield is the explosive TNT equivalent, kt; parameters a, b, c, and d are determined according to the explosion scale; H B H T H c The heights of the base, top, and center of the cloud are given in meters (m); ρ(x, y, h) represents the species concentration distribution at different locations; σ o σ is the horizontal diffusion coefficient in miles; h R is the vertical diffusion coefficient, kilofeet; C Let be the diameter of the smoke plume, in meters (m).

[0046] Figure 3 This is a diagram illustrating the effect of a near-ground explosion. When the blast source is close to the ground, ground reflection and ground-medium coupling significantly affect the overpressure waveform parameters generated by the explosion. Regarding ground reflection, the equivalent TNT equivalent is twice the actual TNT equivalent when the blast source is placed on a rigid surface. When the blast source is located above a rigid surface, considering that blast sources such as car bombs, ammunition depots, and hazardous chemical storage facilities are relatively close to the ground, the specific blast height is typically 0.2–9.11 m·kg⁻¹. -1 / 3 An explosion exceeding 9.11 is considered an airburst. When the height H of the explosion's epicenter is input by the user, it is H' greater than the explosion height. s Calculate using formula (7); if the user cannot confirm the explosion height, the default value of Hs is 4.5 m·kg. -1 / 3 The height H of the explosion core is calculated using formula (8). The equivalent TNT equivalent is calculated using formulas (9) to (10). The formulas for calculating the radius, vertical and horizontal diffusion coefficients, and relative density of inert material after the equivalent explosion are (4) to (6).

[0047]

[0048]

[0049]

[0050] yield eq =F*yield (10)

[0051] In the formula, H represents the height of the explosion nucleus in meters (m); H s For higher specific explosiveness; F is the equivalent equivalence factor; yield eq t is the equivalent of TNT.

[0052] Figure 4 The image shows the effect of a sea explosion. The smoke cloud forms of sea explosions and air explosions differ. The radius and height of the water column of a sea explosion are estimated using the maximum expansion radius of the explosion bubble, as shown in formula (11). At the same time, the maximum expansion radius of the water column is used as the radius and height of the water column to parameterize the sea explosion smoke cloud. The formulas for calculating the vertical and horizontal diffusion coefficients and the relative density of inert materials after the explosion are (4) to (6).

[0053]

[0054] In the formula, W is the explosive yield, and H is the height above the water surface.

[0055] (2) Virtual point cloud construction

[0056] Based on the explosion type, location, height, and the aforementioned steady-state smoke plume parameterization method, the latitude, longitude, thickness, height, and radius of the steady-state smoke plume center approximately 5 minutes after the explosion are obtained. Furthermore, the smoke plume is divided into emission point clouds in three-dimensional space using an equidistant grid. The number of point clouds (nx, ny, nz) in different directions is determined based on the smoke plume radius and grid spacing, as shown in equations (12) to (15). The amount of inert material emitted in each point cloud is calculated based on the relative concentration value of each point using formula (6), and this value is used as the weight to spatially allocate the total amount of inert material emitted, as shown in formula (15).

[0057] nx = R C / dx (12)

[0058] ny = R C / dy (13)

[0059] nz = R C / dz (14)

[0060]

[0061] In the formula, dx, dy, and dz represent the spacing of the point cloud in different directions, in meters (m); E total E(x,y,h) represents the total emissions of the input species; E(x,y,h) represents the emissions at a certain point.

[0062] Latitude and longitude are non-equidistant geographic coordinate systems; the higher the latitude, the shorter the distance. Therefore, it is difficult to form equidistant virtual point cloud files based on latitude and longitude. This embodiment avoids this problem by using the method of "geographic coordinate system → projected coordinate system → geographic coordinate system" and forms equidistant virtual point cloud files. First, the latitude and longitude of the smoke cloud center are unified into the Universal Transverse Mercator Grid System (UTM) and converted into projected coordinates in meters. This projected coordinate is a plane rectangular coordinate. This coordinate grid system and the projection it is based on have been widely used in topographic maps and as a reference grid for satellite imagery and natural resource databases, as well as other applications requiring precise positioning. Second, the location of each virtual point cloud and its emission amount are obtained according to the projected coordinates and equations (12) to (15). Third, the projected coordinates of each virtual point source in meters are converted into geographic coordinates in latitude and longitude. Finally, a three-dimensional grid emission file of virtual point cloud including information such as latitude and longitude, altitude, and emission amount of virtual point cloud is formed. Figure 5 This is a virtual point cloud construction diagram based on the initial source strength after an explosion 5 minutes prior to the point cloud, with a point cloud interval of 1km. Figure 6 The virtual point cloud is constructed based on the initial source strength 5 minutes after an explosion with a point cloud interval of 5km. The size of the origin is proportional to the emission amount.

[0063] (3) Parameterization of point cloud emission morphology after short-term diffusion

[0064] Explosions are instantaneous and sudden, and the initial smoke plume can change rapidly due to the influence of wind fields at different altitudes. Atmospheric diffusion models often use hourly meteorological input data, and there may be a time lag between the start time of the meteorological input data and the detonation time, during which the changes in the initial smoke plume morphology cannot be ignored. Therefore, considering the stable morphology of the smoke plume after it enters the model is crucial for accurately assessing the environmental impact of the explosion.

[0065] In this embodiment, the time interval between the detonation time and the model reporting time is defined as the smoke cloud stabilization time, as shown in Equation (16). Based on the virtual point cloud described above, this embodiment describes the morphological changes of the smoke cloud by using the meteorological parameters and stabilization time of each virtual point source location. First, the stabilization duration of the entire stable smoke cloud is calculated, and the step size is calculated according to the morphology to calculate the number of simulation steps, as shown in Equation (17). Second, the spatial position of each virtual point at time t is calculated. Taking the x-direction as an example, the spatial position of a virtual point is calculated based on the meridional wind at its location and the time step, as shown in Equation (18). Finally, the three-dimensional position changes of the virtual points at each time step in the above steps are repeated to obtain the point cloud morphological changes after short-term diffusion.

[0066] Tstable =T boom -T model (16)

[0067] nstep = T stable / dt (17)

[0068] x t =x t-1 +u t-1 ×dt (18)

[0069] In the formula, T Stable ,T model ,T boom These represent the stabilization duration, model initiation time, and detonation time, respectively, in seconds; dt is the time step; nstep is the number of simulation steps; dy,dz are the spacing of the point cloud in different directions, in meters; E total E(x,y,h) represents the total emissions of the input species; E(x,y,h) represents the emissions at a certain point.

[0070] (4) Multi-scale and multi-time period atmospheric diffusion simulation

[0071] Based on the parameterization of point cloud emission morphology after short-term diffusion simulation, a three-dimensional spatially meshed emission inventory input file is generated, which can be used for atmospheric diffusion models such as CALPUFF and CMAQ. This inventory describes the emission amounts of gaseous and particulate inert matter in each virtual point cloud in terms of mole / s and g / s, respectively, and reflects the altitude of different point clouds. When setting the explosion source, instantaneous emissions are used, with emissions occurring in the first hour and zero emissions at other times. During the simulation of atmospheric diffusion of inert matter, conventional atmospheric pollutants are only considered as essential conditions for the normal operation of the model; clean air is selected as the initial condition for numerical simulation.

[0072] This explanation uses the CMAQ model to simulate radioactive elements as an example. The chemical mechanism details the complex chemical reaction processes in the atmosphere, including atmospheric simulated species and chemical reaction processes, determining the atmospheric components and their reaction processes that the CMAQ model can simulate. Modifying the chemical reaction mechanism of the CMAQ model is fundamental to incorporating radioactive elements into the model. The commonly used cb5aero6 mechanism in the CMAQ model is modified to simulate radioactive species by "adding defined radioactive species → adding decay reactions → regenerating chemical mechanisms." Specifically, the chemmech tool in the CMAQ model's UTIL module regenerates the chemical mechanism, and the create_ebi tool regenerates the corresponding solver for the new mechanism. For radioactive materials, the Mech.def file defines the chemical reaction processes considered in the CMAQ simulation, such as the decay processes of Cs to Ba and I to Xe, which are included as chemical reaction processes in the mech.def file. Specifically, 7.3E-10 and 1E-06 are the reaction rates of cesium and iodine decay reactions calculated based on their half-lives, respectively. The AERO_DATA.F file defines the aerosol species to be simulated, including the number of aerosol simulations and the definition of newly added aerosol species. The CMAQ model includes a built-in combine.exe data post-processing module, which can output custom variables based on input meteorological files, air concentration files, and dry / wet deposition result files. Figure 7 This is a graph showing the vertical diffusion changes of smoke particles during the stable period of 1 hour.

[0073] The following is a specific case to illustrate this.

[0074] (1) Input file preparation

[0075] This case study proposes inputting an explosion source (circular area) in Shanxi Province. The main information of the emission source in the Emisprep input.csv parameter file is shown in Table 1. For the airburst scenario with sequence number (ID) 1, TLX and TLY are the latitude and longitude of the explosion center. TRX, TRY, DLX, DLY, DRX, and DRY have the same latitude and longitude. The airburst height is set to 1000 meters, the explosive yield is 50,000 tons of TNT, and the iodine emission (IOE) is 10 grams. Parameters such as explosive yield and detonation height can be left blank or entered as 0. The iodine emission (IOE) is 100 grams. Furthermore, since the model's minimum resolution is 5–9 km, the interval between each virtual point source is set to 3 km in this case study.

[0076] Table 1. Input.csv contains the main input data.

[0077]

[0078] (2) Emission Inventory Results

[0079] Figure 8 This is a point cloud map of a 9km study area in Shanxi Province, where circles represent explosion-type areas. The generated STACK_GROUPS_NUE.csv and STACK_GROUPS_NUB.csv files were then placed onto the map using GIS tools.

[0080] The STACK_GROUPS_NUB.csv explosion emission inventory is plotted on a map, with Cs as an example, and the emission amount is used as the size of the dots. As can be seen from the graph, this emission source file reflects the emission characteristics of an explosion process, where the emission amount is large at the center and small at the edges. The emission amounts of each point source in the STACK_GROUPS_NUE.csv leak source emission inventory are consistent. Figure 9 This is a spatial distribution map of the explosion point cloud, where the dots represent virtual point sources, and their size is proportional to the emission volume.

[0081] The GRIDCRO2D file is the grid parameter output result of the WRF model output wrfout file processed by the MCIP meteorological module into a CMAQ-usable meteorological file. The Emis2CMAQ module requires an emission inventory of radioactive materials from the explosion source and conventional air pollutants. STACK_GROUPS_IN.csv is the preprocessed inventory file included with the module, and STACK_GROUPS_NUB.csv is the explosion-related emission inventory file generated by the Emisprep module. Running the point source emission and chimney location netcdf emission inventory files generates emission files (IN.nc, NUE.nc, NUB.nc) and point source location files (STACK_GROUPS_IN.nc, STACK_GROUPS_NUE.nc, STACK_GROUPS_NUB.nc) upon completion.

[0082] (3) CMAQ model simulation

[0083] The input data mainly includes meteorological documents, emission inventories, initial field, and boundary field. This case study primarily simulates radioactive elements; atmospheric pollutants are only a necessary condition for the model's normal operation. Therefore, clean air is selected as the initial condition for numerical simulation. Similar to the initial field, clean air boundary conditions are used for numerical simulation. The main operating module of the CMAQ model is CCTM, which can simulate processes such as pollutant diffusion and deposition. This case study uses the panoply tool for simple visualization to reflect the structure and effect of the simulation results. The concentration distribution of iodine and cesium in the simulation model is basically consistent with the area delineated from the leak source. Simultaneously, it can reflect the different processes of atmospheric concentration and deposition. Therefore, the entire framework for simulating radioactive nuclides in leak scenarios can run smoothly and obtain corresponding results. However, due to the high explosion altitude and instantaneous emission, the related pollutants diffused rapidly. After 24 hours, the iodine and cesium pollutants had been transported outside the study area. Figure 10 For I 131 The graph shows the average hourly concentration variation across the grid with varying layers and time. It can be seen from the graph that the pollutants were rapidly diluted and dispersed within two hours of the explosion. Furthermore, since the top of the explosion source reached an altitude of 12,000 meters, iodine-131 was mainly distributed within higher vertical layers, such as layer 21.

[0084] Figures 11(a), 11(b), and 11(c) represent layers I with 20|131 layers, 5|131 layers, and 1|131 layers, respectively. 131 The graph shows the 24-hour grid average concentration. It can be seen that after the explosion, due to atmospheric diffusion, the concentration values ​​varied at different levels. Furthermore, since the explosion primarily occurred at high altitudes, the concentration of I at higher levels was also higher. 131 The concentration in the environment is relatively higher.

[0085] Therefore, this invention can complete the simulation framework design and support the horizontal and vertical simulation of radioactive elements produced by an explosion. Furthermore, the method of this invention can provide decision-makers with rapid, scientific, and effective suggestions and plans for personnel evacuation or emergency response, thereby protecting public and environmental safety.

Claims

1. A forecasting and early warning method for the release of inert materials and atmospheric diffusion in various types of explosion events, characterized in that, Includes the following steps: Step 1: Considering the explosion mode, explosion yield, and detonation location, parameterize the initial smoke source strength to describe the release process of radioactive materials, biotoxic compounds, and malodorous inert substances; Step 2: Use virtual point cloud technology to create a three-dimensional spatial mesh of the initial smoke source intensity to reflect the spatiotemporal morphology of the initial smoke. Step 3: Explosion events are instantaneous and sudden. Affected by wind fields at different altitudes, the initial smoke plume will change in a short time. Short-term diffusion simulation is carried out for each virtual point source to form a three-dimensional mesh file of the stable smoke plume source strength to reflect the spatiotemporal morphology of the stable smoke plume. Step 3 specifically includes the following sub-steps: Step 31: Calculate the stabilization time of the entire stable smoke plume, and calculate the time step and simulation steps based on the morphology; Step 32: Calculate the spatial location of each virtual point at time t; Step 33: Repeatedly calculate the three-dimensional position changes of the virtual points based on the time step and the number of simulation steps to obtain the spatiotemporal morphology of the stable smoke plume after short-term diffusion; Step 4: Using atmospheric diffusion modeling tools, conduct multi-scale and multi-time-period diffusion simulations of inert materials. Combine the atmospheric concentration of inert materials and dry and wet deposition fluxes to conduct an impact assessment of the explosion event. Based on the parameterization of the emission morphology of the point cloud after the short-term diffusion simulation, generate a three-dimensional spatially gridded emission inventory input file for CALPUFF and CMAQ atmospheric diffusion models. This inventory describes the emission of gaseous and particulate inert materials in each virtual point cloud in terms of mole / s and g / s, respectively, and reflects the altitude position of different point clouds. When setting the explosion source, use instantaneous emission with emission in the first hour and zero emission at other times. In the simulation of atmospheric diffusion of inert substances, conventional atmospheric pollutants are only used as a necessary condition for the normal operation of the model, and the initial condition of clean air is selected for numerical simulation.

2. The forecasting and early warning method for inert material release and atmospheric diffusion in various types of explosion events according to claim 1, characterized in that, The explosion types in step 1 include high-altitude explosions, ground explosions, sea surface explosions, and deep-sea explosions.

3. The forecasting and early warning method for inert material release and atmospheric diffusion in various types of explosion events according to claim 2, characterized in that, The initial smoke cloud height, top height, and radius are characterized based on the explosive yield.

4. The forecasting and early warning method for inert material release and atmospheric diffusion in various types of explosion events according to claim 1, characterized in that, Step 2 specifically includes the following sub-steps: Step 21: Unify the latitude and longitude of the smoke cloud center into the universal transverse Mercator grid system and convert it into projected coordinates in meters; Step 22: Based on the projection coordinates and the number of point clouds in different directions, obtain the location of each virtual point cloud and its emission amount; Step 23: Convert the projected coordinates in Step 21 into geographic coordinates in latitude and longitude units to form a virtual point cloud 3D grid emission file that includes virtual point cloud latitude and longitude, altitude, and emission information.

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