Mobile source nuclear accident consequence evaluation method and system, computing device and storage medium

Abstract

The invention relates to a mobile source nuclear accident consequence evaluation method and system, computing equipment and a storage medium. The method comprises the following steps: acquiring geographic data and meteorological data; calculating a meteorological field according to the geographic data and the meteorological data, generating meteorological field data, and obtaining source item data of the moving source according to a plurality of point sources of the moving source on the moving path; diffusion calculation of the moving source is carried out according to the source item data and the meteorological field data, and concentration field data of the moving source is generated; and performing dose calculation according to the concentration field data to generate dose field data of the mobile source. According to the technical scheme provided by the invention, the radioactive substance diffusion process of the mobile source can be effectively evaluated.

Description

Technical Field

[0001] The present disclosure relates to the field of nuclear technology, and in particular, to a method, system, computing device and storage medium for evaluating accident consequences of a mobile source. Background Art

[0002] Nuclear accident consequence assessment technology is an important part of nuclear emergency preparedness and a necessary technical means in the nuclear emergency response process. The technical route adopted by the current accident consequence assessment technology focuses on fixed point source events, such as nuclear power plant leaks. The current accident consequence assessment technology also focuses on the simulated diffusion of pollutants at different scales and their migration in water bodies. These pollutants at different scales typically focus on the range of 100km around the nuclear power plant site, focus on trajectory simulation at the global level, and focus on the impact of buildings on diffusion at the local scale.

[0003] However, with the widespread use of mobile nuclear facilities such as nuclear-powered ships, spent fuel transportation, and nuclear-powered spacecraft, there is a great lack of simulation calculations, emergency preparedness, and technical supervision for mobile sources. There are still many difficulties in the existing technology for the consequence assessment of mobile nuclear accidents.

[0004] First, it is difficult for existing technologies to effectively evaluate the diffusion process of radioactive materials from mobile sources. Traditional accident consequence rating models are mostly used for fixed point sources. Even if some models can consider multi-point releases, they are limited by the calculation interval (for example, usually once an hour), calculation space (for example, usually limited to 100km around the nuclear power plant), and calculation storage capacity. It is impossible to give real-time diffusion rules of radionuclides released from mobile sources at different locations over time.

[0005] In addition, existing technologies make it difficult to obtain basic data in real time. The location and time of accidents at mobile nuclear facilities are highly uncertain, especially in complex environments such as the ocean and the air. Traditional accident consequence assessment requires the introduction of basic data such as geographic information of the surrounding environment and meteorological numerical forecast products at the corresponding time in advance, which is difficult to meet the large spatial changes of mobile sources and the need to obtain relevant data at any location in real time.

[0006] In addition, the emergency response speed of existing technologies is lagging behind. Traditional accident consequence assessment is limited by its own model framework. The calculation of concentration fields and dose fields of multiple nuclides requires repeated calculations, and the simulation time is long. The source items of mobile nuclear facilities may change with time and location, and the traditional fixed point source model cannot effectively capture this dynamic change. Summary of the invention

[0007] In order to solve at least one of the above problems, a method, system, computing device and storage medium for evaluating the consequences of a mobile source nuclear accident are provided, which can effectively evaluate the diffusion process of radioactive substances in a mobile source.

[0008] According to another aspect of the present disclosure, a method for evaluating the consequences of a mobile source nuclear accident is provided, the method comprising: acquiring geographic data and meteorological data; calculating a meteorological field based on the geographic data and the meteorological data to generate meteorological field data; acquiring source term data of the mobile source based on a plurality of point sources on a mobile path of the mobile source; performing diffusion calculation of the mobile source based on the source term data and the meteorological field data to generate concentration field data of the mobile source; and performing dose calculation based on the concentration field data to generate dose field data of the mobile source.

[0009] In some embodiments, obtaining the source item data of the mobile source includes: based on the positions of the multiple point sources, using a zero-order interpolation method to perform an encrypted simulation on the point source positions of the mobile source, so that each encrypted point source of the mobile source matches the corresponding source item data.

[0010] In some embodiments, the concentration field data of the mobile source is generated by establishing a simulation area corresponding to each point source on the moving path of the mobile source, so that there is an overlapping part between two adjacent simulation areas, and there is at least one point source in the overlapping part.

[0011] In some embodiments, the corresponding source item data of each point source of the mobile source are grouped according to the attributes of the nuclides in the source item data.

[0012] In some embodiments, the concentration field of each group of nuclides of each point source is calculated separately in the diffusion calculation, and based on the concentration field of each group of nuclides, the concentration field of each nuclide of each point source is calculated according to the proportion of each nuclide in each group of nuclides, thereby generating the concentration field data of the mobile source.

[0013] In some embodiments, the formats of the concentration field data include the following four data formats that can be directly used in the dose calculation: compressed binary format, uncompressed binary format, compressed text format, and uncompressed text format.

[0014] In some embodiments, decoupling calculation is used to calculate the dose field of each point source through the corresponding source term data of each point source of the mobile source, the concentration field of each nuclide of each point source and the dose conversion factor to generate the dose field data of the mobile source.

[0015] In some embodiments, the diffusion calculation is performed based on a puff model.

[0016] According to another aspect of the present disclosure, a mobile source nuclear accident consequence assessment system is also provided, the system comprising: a data acquisition module, which acquires geographic data and meteorological data; a meteorological field generation module, which calculates the meteorological field based on the geographic data and the meteorological data, and generates meteorological field data; a source item data acquisition module, which acquires source item data of the mobile source based on multiple point sources on the mobile path of the mobile source; a concentration field generation module, which performs diffusion calculation of the mobile source based on the source item data and the meteorological field data, and generates concentration field data of the mobile source; and a dose field generation module, which performs dose calculation based on the concentration field data, and generates dose field data of the mobile source.

[0017] According to another aspect of the present disclosure, there is also provided a computing device, including a memory and a processor, wherein the memory stores a computer program, and when the processor runs the computer program stored in the memory, the processor executes the aforementioned mobile source nuclear accident consequence assessment method.

[0018] According to another aspect of the present disclosure, a computer-readable storage medium is also provided, on which a computer program is stored. When the computer program is executed by a processor, the processor executes the aforementioned mobile source nuclear accident consequence assessment method.

[0019] According to the mobile source nuclear accident consequence assessment method, system, computing device and storage medium disclosed in the present invention, it is possible to quickly simulate the concentration field and dose field of the mobile source, improve the computing efficiency, and thus effectively assess the consequences of the mobile source nuclear accident. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0021] Figure 1 is a flow chart showing a method for evaluating consequences of a mobile source nuclear accident according to one embodiment of the present disclosure;

[0022] Figure 2 is a schematic diagram showing division of a simulation area of ​​a mobile source according to one embodiment of the present disclosure.

[0023] Figure 3 is a structural schematic diagram showing a mobile source nuclear accident consequence assessment system according to an embodiment of the present disclosure;

[0024] Figure 4 is a schematic diagram showing the structure of a computing device according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the exemplary embodiments will be described in detail below. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with the present disclosure. On the contrary, they are merely examples of systems and methods consistent with some aspects disclosed in the present embodiment as detailed in the attached claims. In addition, the elements in the drawings are not necessarily drawn to scale, but are mainly used to illustrate the principles of the present disclosure.

[0026] The terms used in the present disclosure are only used to describe specific embodiments and are not intended to limit the present disclosure. The term "and / or" as used in the present disclosure includes any and all combinations of at least one related enumerated item. The singular forms "one" and "the" as used in the present disclosure are also intended to include plural forms, unless the context clearly indicates otherwise. The terms "including", "consisting of..." as used in the present disclosure specify the presence of the features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of at least one other feature, whole, step, operation, element, component and / or its group.

[0027] Unless otherwise defined, all terms (including technical and scientific terms) used in this disclosure have the same meaning as commonly understood by those of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning unless explicitly defined in this disclosure.

[0028] like Figure 1 As shown, the present disclosure provides a method for evaluating the consequences of a mobile source nuclear accident, the method comprising: step S1, acquiring geographic data and meteorological data; step S2, calculating the meteorological field based on the geographic data and the meteorological data, and generating meteorological field data; step S3, acquiring source item data of the mobile source based on multiple point sources on the mobile path of the mobile source; step S4, performing diffusion calculation of the mobile source based on the source item data and the meteorological field data, and generating concentration field data of the mobile source; and step S5, performing dose calculation based on the concentration field data, and generating dose field data of the mobile source.

[0029] The mobile source here can be a mobile nuclear facility such as a nuclear-powered ship, a floating reactor, spent fuel transportation, a nuclear-powered spacecraft, etc. By obtaining the source item data of the mobile source based on multiple point sources on the mobile path, the concentration field and dose field of the mobile source after a nuclear accident can be accurately and quickly simulated.

[0030] The preferred embodiments of the mobile source nuclear accident consequence assessment method will be described in detail below. It should be understood that the following preferred embodiments are not intended to limit the present disclosure but are exemplary illustrations of the present disclosure. It should also be understood that the mobile source nuclear accident consequence assessment method of the present disclosure can be implemented even without using some or all of these preferred embodiments.

[0031] Data such as geographic data and meteorological data may be acquired by any suitable method.

[0032] The location and time of accidents of mobile sources such as mobile nuclear facilities are highly uncertain, especially in complex environments such as the ocean and the air. Traditional accident consequence assessment requires the introduction of basic data such as geographic information of the surrounding environment and numerical meteorological forecast products at the corresponding time in advance, which is difficult to meet the large spatial changes of mobile sources. In some embodiments of the present disclosure, in order to meet the requirements of the consequence assessment of mobile nuclear accidents, relevant data of any location can be obtained in real time. In other embodiments, geographic data and meteorological data are obtained by achieving real-time acquisition of global data.

[0033] In some embodiments, the acquired meteorological data is first converted to a time zone, automatically matched to a latitude and longitude range, and real-time forecast data is obtained by automatically accessing the Internet. In addition, the acquired meteorological data is subjected to necessary data control, screening, and element calculation, and then hierarchically output as a meteorological data file required by a model for the consequence assessment of a mobile source nuclear accident.

[0034] In some embodiments, for geographic data such as land use data, the projection coordinates are automatically matched to images of appropriate resolution (such as images in formats such as tiff, jpeg, and bmp), the images are cut and rendered, and a land use image is output; raster data information can be obtained based on the width, height, and band information of the image, and the grid is refined by interpolation and other methods, and the required terrain elevation image is output after rendering. The projection information of the above land use image and terrain elevation image is output as a document that meets the requirements of the model.

[0035] In conventional fixed source nuclear accident consequence assessment technology, the grid of the model used for nuclear accident consequence assessment is divided into a grid whose side length represents, for example, 1 km, 5 km or 10 km (different grids are divided according to different simulation ranges). However, in the present disclosure, in order to give the diffusion law of radioactive nuclides released by mobile sources at different positions over time in real time, the grid of the model is refined so that the side length of each grid represents, for example, a distance of 10 meters to 100 meters. It should be understood that the value of the grid refinement is not limited to this, and the grid refinement can correspond to different precisions according to different simulation ranges.

[0036] Compared with the usual meteorological data, which needs to be manually copied, decoded and calculated separately, and geographic information data, which also needs to be manually initialized, automatic real-time data acquisition can improve data acquisition efficiency.

[0037] Although the method for assessing the consequences of a mobile source nuclear accident is described as including obtaining geographic data and meteorological data, the method may also obtain other data as needed.

[0038] Meteorological field data can be generated by calculating the meteorological field based on geographic data and meteorological data. In some embodiments, the mass conservation continuity equation is used to combine the acquired geographic data and meteorological data to describe the hourly wind field and temperature field in the three-dimensional grid simulation domain, and the core includes the diagnostic wind field and micro-meteorological field mode. The wind field is diagnosed by the mass conservation continuity equation. After the above-mentioned processed meteorological data, the three-dimensional wind field and micro-meteorological field data including the hourly wind field, mixing layer height, atmospheric stability and micro-meteorological parameters will be automatically calculated and generated to obtain meteorological field data.

[0039] Previous models mostly used the Gaussian plume model to generate meteorological field data, which could not well characterize the changes in wind direction and the influence of terrain. The Gaussian plume model is used to describe the diffusion process of pollutants (such as smoke) in the vertical and horizontal directions after being emitted from the source. The Gaussian plume model assumes that pollutants form a narrow "plume" at the emission source, and then diffuse with the changes in wind speed and atmospheric stability, forming a feather-like diffusion path. The Gaussian plume model also assumes that the average flow field of the wind is stable, the wind speed is uniform, and the wind direction is straight; the y and z axis directions conform to the normal distribution; the mass of pollutants is conserved during transport and diffusion; and the source strength of the pollution source is uniform and continuous. Therefore, the Gaussian plume model is only suitable for simulating fixed point sources that are related to wind direction and blow in a fixed direction.

[0040] In the embodiments of the present disclosure, the dynamic influence of terrain, oblique airflow and blocking effect are considered in detail during the three-dimensional wind field simulation process.

[0041] The source item data of the mobile source can be obtained according to the multiple point sources on the mobile path of the mobile source. The source item here refers to the form, quantity, composition and other release characteristics of the radioactive materials released into the environment by the nuclear accident source in the event of an accident, which change over time. The source item data of the mobile source can be obtained according to the multiple point sources on the mobile path of the mobile source. In some embodiments, obtaining the source item data of the mobile source includes: based on the positions of multiple point sources, using the zero-order interpolation method to encrypt and simulate the point source positions of the mobile source, so that the encrypted point sources of the mobile source match the corresponding source item data. In this way, it is ensured that even if only the longitude and latitude and time of the position of an individual point source are known, the corresponding longitude and latitude positions can still be matched according to the speed of the point source movement, and the source items of the point source are allocated to the corresponding time period. Encrypted simulation here refers to encrypting the release time and position of the source item. In the traditional fixed source nuclear accident assessment, the source item release time is simulated by hours, for example, according to the source item release every 0 to 2 hours, every 2 to 8 hours, or every 8 to 48 hours. In the case of the mobile source of the present disclosure, the source item is matched to the release in minutes. In addition, in the encrypted simulation of the present disclosure, the location of the source item also changes with time and is expressed as precise longitude and latitude.

[0042] In some embodiments, the concentration field data of the mobile source is generated by establishing a simulation area corresponding to each point source on the moving path of the mobile source, so that there is an overlapping part between two adjacent simulation areas, and there is at least one point source in the overlapping part.

[0043] Specifically, if Figure 2 As shown in the figure, in addition to simply refining the spatial grid, it is also necessary to consider the superposition of dose simulations brought about by the release of different point sources, that is, it is necessary to establish multiple simulation cases based on, for example, the route (path) of the ship, each case corresponds to a multi-point release, and the position and intensity of the simulated source change over time. After that, the results of all cases are superimposed to obtain the total cumulative result of the whole process. Of course, the results of any time point in the middle can also be obtained.

[0044] It should be noted that the corresponding simulation area should be established according to the change of the release point position. There is overlap between the simulation areas, but the release positions are completely continuous. Figure 2 As shown: the two simulation areas correspond to simulation area 1 (sim1) and simulation area 2 (sim2). A, B, and C are multiple point sources corresponding to the mobile source, and the arrows from A to B to C correspond to the moving paths of the mobile source. Point source B is in the overlapping area of ​​simulation area 1 and simulation area 2. However, it should be understood that the simulation area can also be divided into multiple point sources in the overlapping area.

[0045] The roughly linear release area (i.e., point source) is in the middle of the simulation area to ensure that the simulation area has a certain envelope range. In simulation area 1, the release range is A and B, and the corresponding time range is t0-t1; in simulation area 2, the release range is B and C, and the corresponding time is t1-t2. For each simulation area, each release point (point source) can be approximated as an instantaneous release. A separate simulation method is used in the processing, which is roughly divided into 20 to 50 typical simulation areas based on the grid, which is sufficiently accurate. For a simulation area, all simulations are superimposed in time to obtain the results of all release points. If further accumulated and summed, the cumulative concentration can be obtained.

[0046] The above idea of ​​generating concentration field data of mobile sources by dividing the simulation area can theoretically be used for long-distance and complex routes of any shape. However, in the demonstration, for convenience, it may be necessary to interpolate the grid into the latitude and longitude grid (or directly project the coordinates).

[0047] In some embodiments, the corresponding source item data of each point source of the mobile source are grouped according to the properties of the nuclides in the source item data. This grouping of nuclides greatly improves the processing and calculation efficiency of the source item data. This grouping of nuclides will also be described in detail below.

[0048] In the embodiments of the present disclosure, by means of encrypted simulation of mobile sources and grouping of nuclides, the computational efficiency can be effectively improved, thereby greatly increasing the speed of accident consequence assessment of mobile sources.

[0049] The diffusion calculation of mobile sources can be performed based on source data and meteorological field data to generate mobile source concentration field data. Due to the complexity of nuclear release (such as thousands of nuclides, intermittent release from multiple sources, etc.), the existing models cannot cope with these complex diffusion calculations in terms of long-term probability statistics of concentration fields. Since the existing models can only simulate the release of dozens of species, even if the diffusion of thousands of nuclides can be simulated, it will consume a lot of machine time and the calculation efficiency is too low.

[0050] As described above, the corresponding source item data of each point source of the mobile source are grouped according to the properties of the nuclides in the source item data, that is, the nuclides are grouped using the similar properties of each type of nuclides. No matter how many types of nuclides there are (depending on the accident source items, sometimes more than thirty or forty types, sometimes more than one hundred types), they are classified into, for example, 11 categories (the module classifies the nuclides according to the grouping code of each nuclide), and the proportion of each nuclide in each group is recorded. In this way, the module for the consequence assessment of mobile source nuclear accidents only needs to calculate the diffusion of, for example, 11 species at most, which greatly saves calculation time. In some embodiments, the concentration field of each group of nuclides of each point source is calculated separately in the diffusion calculation, and based on the concentration field of each group of nuclides, the concentration field of each nuclide of each point source is calculated (reduced) according to the proportion of each nuclide in each group of nuclides, thereby generating the concentration field data of the mobile source. Through the above grouping, the calculation efficiency of multiple nuclides can be greatly improved.

[0051] In some embodiments, hundreds of nuclides are classified into categories such as the following based on the chemical properties of the elements, the decay characteristics of the radioisotopes, the behavior in the reactor, and the needs for nuclear waste management, environmental impact, and radiation protection:

[0052] Noble gases: Noble gases generally do not participate chemically in nuclear reactions, so their radioactivity comes primarily from the decay of their isotopes, and their gaseous form makes them less interactive with other substances when handled.

[0053] Halogen ELE, Halogen ORG and Halogen ARE: Halogen elements include fluorine, chlorine, bromine, iodine, etc. These elements have strong chemical reactivity and can form various compounds with other substances. They are divided into different subgroups according to their chemical form. ELE refers to halogens in simple form, ORG refers to halogens combined with carbon to form organic halogen compounds, and ARE refers to halogen compounds formed with other elements or minerals.

[0054] Alkali metals: Alkali metals include elements such as lithium, sodium, potassium, rubidium and cesium. Alkali metals are highly chemically active in nuclear reactors, especially sodium, which is often used as coolant. The decay of alkali metal radionuclides is closely related to their chemical properties, and they tend to react violently with water at high temperatures.

[0055] Tellurium group elements: including tellurium, selenium, etc. Tellurium group elements are usually considered separately in radioactive waste treatment because they are more active in nuclear reactions, and some isotopes of tellurium and selenium have a long half-life, which affects the long-term management of nuclear waste.

[0056] Precious metals: including platinum, gold, palladium and other elements. Precious metal elements are relatively stable in chemical reactions and rarely participate in chemical reactions in nuclear reactions. Therefore, they are usually relatively stable in nuclear waste treatment, but some isotopes still have certain radioactivity.

[0057] Barium and strontium: Considering that the radioactive isotopes of these two elements have long half-lives, especially strontium-90, which is widely present in nuclear waste, it is helpful to group them separately to assess their environmental risks and radiation protection.

[0058] Lanthanides, cerium group elements and others.

[0059] Table 1 below shows the above classification of nuclides. In Table 1 below, the nuclides are grouped using the similar properties of each type of nuclide (see the table below for the nuclide grouping code), and each nuclide has a corresponding grouping code in the nuclide library parameter file Nuc_Lib.csv.

[0060] Table 1 Nuclide groups and their corresponding codes

[0061]

[0062]

[0063] The diffusion field also involves the problem of time and space cutting and allocation of mobile sources, which is the same as the improvement of source items, mainly for the allocation and processing of multiple source items in time and grid. At the same time, although the original mode has its own post-processing module for the diffusion field, its calculation efficiency is very low. It is acceptable for a small amount of calculation for a single diffusion simulation, but it is unacceptable for the massive calculation required for the simulation of mobile sources in the embodiment of the present disclosure. In the embodiment of the present disclosure, not only can the concentration and deposition amount of each nuclide be restored from the nuclide grouping, but also the data format required for direct conversion of dose calculation is provided. In some embodiments, four data formats of output concentration field and dry deposition are provided, that is, the format of concentration field data includes the following four data formats that can be directly used in the following dose calculation: compressed binary format, uncompressed binary format, compressed text format and uncompressed text format. By providing the above four formats, users can not only improve the running speed and save disk space when using, but also store the text format during debugging, which is convenient for users to judge whether the calculation results are correct. Therefore, fast diffusion calculation can be achieved.

[0064] In some embodiments, diffusion calculations are performed based on a puff model. In some embodiments, a Gaussian puff model is used. The Gaussian puff model is a model based on tracking pollutants as individual "puffs". The Gaussian puff model assumes that after pollutants are emitted, multiple independent and relatively dispersed "puffs" are formed. These puffs gradually diffuse in the atmosphere, and the diffusion process of each puff can be described separately. Puffs are usually assumed to be released instantaneously, that is, pollutants are emitted into the atmosphere in the form of a pulse, and more attention is paid to the position changes of pollutants at different time points, which can more accurately describe the instantaneous situation of pollutant diffusion. Compared with the plume model, the puff model can better handle asymmetric diffusion situations, such as drastic changes in wind speed and wind direction.

[0065] The equation for pollutant concentration in the Gaussian puff model is:

[0066]

[0067] in,

[0068] C is the ground concentration;

[0069] Q is the mass of pollutants in a puff;

[0070] σ x , σ y , σ z are the diffusion parameters in the horizontal longitudinal, lateral and vertical directions respectively;

[0071] d a is the downwind distance from the center of the puff to the receptor (m);

[0072] d c is the crosswind distance from the center of the puff to the receptor (m);

[0073] g is the vertical term in the Gaussian equation (m), and the sum of the following terms represents multiple reflections between the top of the mixed layer and the ground, that is,

[0074]

[0075] in,

[0076] H e is the effective height of the center of the smoke puff from the ground (m);

[0077] h is the height of the mixing layer (m).

[0078] The calculation formula of diffusion parameters in the diffusion process is as follows:

[0079]

[0080] Where: yn , znis the virtual pollution source parameter, such as time, distance. It is required that when Δξ=0, the diffusion parameter should be consistent with the value at the end of the previous step.

[0081] σ yn , σ zn is the total diffusion parameter in the horizontal and vertical directions at a specified position at the nth sampling step in the diffusion process;

[0082] σ yt , σ zt is the diffusion parameter σ due to atmospheric turbulence y and σ z The functional form of

[0083] σ yb , σ zb is the σ due to the buoyancy of the plume during release y and σ z Quantity;

[0084] σ ys It is the horizontal diffusion parameter component caused by the lateral (across wind) scale of the surface source.

[0085] In some embodiments, the final concentration field is, for example: it can be seen that while the mobile source moves in a certain direction over time, new radioactive substances are continuously produced, and the diffusion of radioactive substances at the previous moment is superimposed, eventually forming a concentration field in which the pollutants move with the point source, drift with the wind direction, and accumulate over time.

[0086] The dose calculation can be performed based on the concentration field data to generate the dose field data of the mobile source. In some embodiments, decoupling calculation is used to calculate the dose field of each point source through the corresponding source term data of each point source of the mobile source, the concentration field of each nuclide of each point source, and the dose conversion factor to generate the dose field data of the mobile source.

[0087] In some embodiments, during the accident release, the public is considered to be affected by three ways: external exposure to smoke, internal exposure to air inhalation, and external exposure to ground deposition. The dose field is decoupled from the concentration field, and the effective doses of the three ways of external exposure to air, external exposure to ground deposition, and internal exposure to inhalation, the thyroid equivalent dose of the inhalation pathway, and the acute doses of red bone marrow, lungs, and skin are calculated by reading data such as source terms, radionuclide concentrations, and dose conversion factors.

[0088] In dose calculation, decoupling calculation is used to avoid repeating the calculation of dose and wind field. Instead, the dose field is directly obtained based on the obtained concentration and dose conversion factor.

[0089] In some embodiments, the efficiency of the mobile source nuclear accident consequence assessment can be further improved by refining the spatial grid of the model used for the assessment, so as to better characterize the concentration dose of radioactive materials on the mobile path. In some embodiments, the efficiency of the mobile source nuclear accident consequence assessment can be further improved by optimizing the simulation time, so as to match the source term of the hour level with the output result to the minute level. The minute level can be 1 minute, 5 minutes, etc. without special restrictions, and can be selected according to the actual needs of the user.

[0090] In addition, in order to meet the real-time simulation requirements for mobile source items, in some embodiments, the overall technical framework is optimized, and multiple methods such as parallel computing and decoupled computing are used, so that when the mobile source is divided into, for example, 100 point sources or even more, the time for a single simulation is shortened from, for example, 10 minutes to 20 minutes to seconds, and the overall simulation time is, for example, about 2 minutes. In this way, the response speed of the consequence assessment of mobile source nuclear accidents is greatly improved.

[0091] In some embodiments, parallel computing can be achieved by rewriting the code framework and adopting a multi-core parallel approach. For example, parallel computing can be achieved by the following code:

[0092] max_cpu=min(os.cpu_count() / / 2,len(dir_cal))#define the number of CPU cores

[0093] with Pool(max_cpu)as p:

[0094] p.map(partial(cal_dose1,grd=grd),dir_cal).

[0095] Usually, in previous calculations, pollutant diffusion and dose calculations are output together, that is, each nuclide needs to repeat the diffusion field simulation. In the present disclosure, by using decoupled calculations and changing the output code of calpuff, a set of diffusion fields can be output separately, and then the concentration and dose calculations can be performed. In this way, the diffusion, concentration and dose are decoupled, which can avoid repeated calculations and save a lot of time.

[0096] The dose calculation is performed by reading source items, nuclide concentrations, and dose conversion factor data through the module, and cycling through different nuclides. During the accident release period, the public is considered to be affected by three ways: external exposure to smoke clouds, internal exposure to air inhalation, and external exposure to ground deposition. The accident dose calculation formula is as follows:

[0097] (1) Calculation of dose from external exposure to plume

[0098] The dose rate of direct external exposure to the plume is calculated using the following formula:

[0099]

[0100] in:

[0101] DC(x,y,o,t) is the external exposure dose (Sv) of the smoke plume received by organ o at the grid (x,y) at the time interval t. The time interval used in the current program is 1h.

[0102] AC(x,y,n,t) is the air concentration of nuclide n near the ground at the grid (x,y) (Bq / m 3 );

[0103] DFC(n,o) is the plume external radiation dose conversion factor of nuclide n to organ o [Sv / (Bq·s / m 3 )];

[0104] SFC is the shielding factor for external radiation from the plume.

[0105] When calculating the external exposure dose of the plume, the approximation of a "semi-infinite" plume is used, that is, it is assumed that the exposed individual is located on an infinite ground and is filled with the radionuclide concentration at that location.

[0106] (2) Calculation of dose of external radiation on the ground

[0107] Radioactive substances in the plume will cause ground contamination due to dry and wet deposition, thus causing radiation exposure to residents. The external radiation dose to the human body from ground-based radioactivity is calculated by the following formula:

[0108]

[0109] in:

[0110] DG(x,y,o) is the ground external radiation dose (Sv) received by organ o at the grid (x,y);

[0111] GC(x,y,n) is the ground concentration of nuclide n at grid (x,y) (Bq / m 2 );

[0112] DFG(n,o) is the ground external radiation dose conversion factor of nuclide n to organ o [Sv / (Bq / m 2 )];

[0113] SFG is the shielding factor for external radiation on the ground.

[0114] (3) Calculation of dose of internal radiation by inhalation

[0115] The amount of radioactivity inhaled by a person through breathing is equal to the integrated concentration of the nuclide in the air multiplied by the person's breathing rate during the passage of the plume. The inhalation dose is calculated by multiplying the inhaled radioactivity by the inhalation dose conversion factor:

[0116]

[0117] in:

[0118] DI(x,y,o) is the committed dose (Sv) caused by the radioactive material inhaled by organ o at grid (x,y);

[0119] AC(x,y,n) is the time-integrated air concentration of nuclide n near the ground at grid (x,y) (Bq·s / m 3 );

[0120] DFI(n,o) is the inhalation internal radiation dose conversion factor of nuclide n to organ o (Sv / Bq);

[0121] BR is the respiratory rate of human beings (m 3 / s);

[0122] SFI is the shielding factor for inhalation internal radiation.

[0123] In the calculation of the effective dose of inhalation dose, the 50-year accumulated dose of inhaled radioactive substances to the human body is taken into account, and in the calculation of the acute exposure dose, the 2-day exposure dose is taken into account.

[0124] like Figure 3 As shown, the present disclosure also provides a mobile source nuclear accident consequence assessment system 10, which includes: a data acquisition module 11, which acquires geographic data and meteorological data; a meteorological field generation module 12, which calculates the meteorological field based on the geographic data and meteorological data and generates meteorological field data; a source item data acquisition module 13, which acquires source item data of the mobile source based on multiple point sources on the mobile path of the mobile source; a concentration field generation module 14, which performs diffusion calculation of the mobile source based on the source item data and the meteorological field data and generates concentration field data of the mobile source; and a dose field generation module 15, which performs dose calculation based on the concentration field data and generates dose field data of the mobile source.

[0125] like Figure 4 As shown, the present disclosure also provides a computing device 20, including a memory 21 and a processor 22, wherein the memory 21 stores a computer program, and when the processor 22 runs the computer program stored in the memory 21, the processor 22 executes the above-mentioned mobile source nuclear accident consequence assessment method.

[0126] The present disclosure also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the processor executes the above-mentioned method for evaluating the consequences of a mobile source nuclear accident.

[0127] Existing nuclear accident consequence assessments often focus on point source releases from fixed facilities such as nuclear power plants, and the scope of the assessment is also concentrated in a limited area around nuclear power plants. It is impossible to simulate emergency accidents in mobile nuclear facilities such as nuclear-powered ships, floating reactors, spent fuel transportation, and nuclear-powered spacecraft in a timely and rapid manner, and it is even more impossible to directly give the superposition of accident consequences of release sources within the mobile range.

[0128] Based on the puff model, the present disclosure improves the whole process from data preparation, source term setting, meteorological field, diffusion field simulation to dose calculation and post-processing. In some embodiments, the calpuff system is used to evaluate the consequences of mobile source nuclear accidents.

[0129] The present disclosure can realize the simulation of nuclear accident consequence assessment of mobile sources, and can be widely used for mobile nuclear facilities such as nuclear-powered ships, spent fuel transportation, and nuclear-powered spacecraft. It can realize the release at any location, divide the mobile source term into at least 100 point sources, and provide the simulation results of the concentration field and dose field of pollutant diffusion within 2 minutes.

[0130] In addition, the present disclosure refines the pattern time of the source term and superimposes the spatial field, so that the model can perform simulation calculations for different release points of the mobile facility (for example, given a few known position times, hundreds of point sources are generated according to the speed, and the corresponding time is matched for release).

[0131] The present disclosure also optimizes the core algorithms for concentration and dose calculation (including parallel calculation, nuclide group calculation, dose field decoupling calculation, etc.), optimizes the diffusion post-processing model, and uses advanced compression formats to achieve rapid call of calculation files, while reducing the occupation of computer storage space, thereby greatly improving the calculation speed. It makes it possible to simulate hundreds or thousands of release sources at the same time, which can meet the needs of engineering applications and emergency response.

[0132] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0133] Finally, 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the consequences of a mobile source nuclear accident, characterized in that: The method comprises: Obtain geographic and meteorological data; Calculate the meteorological field according to the geographic data and the meteorological data to generate meteorological field data; Acquiring source item data of the mobile source according to a plurality of point sources on a mobile path; Performing diffusion calculation of the mobile source according to the source term data and the meteorological field data to generate concentration field data of the mobile source; and Dose calculation is performed according to the concentration field data to generate dose field data of the mobile source.

2. The mobile source nuclear accident post-evaluation method according to claim 1, characterized in that: Acquiring the source item data of the mobile source includes: based on the positions of the multiple point sources, using a zero-order interpolation method to perform encrypted simulation on the point source positions of the mobile source, so that each encrypted point source of the mobile source matches the corresponding source item data.

3. The mobile source nuclear accident post-evaluation method according to claim 2, characterized in that: The concentration field data of the moving source is generated in the following manner: a simulation area corresponding to each point source is established on the moving path of the moving source, so that there is an overlapping part between two adjacent simulation areas, and there is at least one point source in the overlapping part.

4. The mobile source nuclear accident post-evaluation method according to claim 2, characterized in that: The corresponding source item data of each point source of the mobile source are grouped according to the attributes of the nuclides in the source item data.

5. The mobile source nuclear accident post-evaluation method according to claim 4, characterized in that: In the diffusion calculation, the concentration field of each group of nuclides of each point source is calculated respectively, and based on the concentration field of each group of nuclides, the concentration field of each nuclide of each point source is calculated according to the proportion of each nuclide in each group of nuclides, thereby generating the concentration field data of the mobile source.

6. The mobile source nuclear accident post-evaluation method according to claim 1, characterized in that: The formats of the concentration field data include the following four data formats that can be directly used in the dose calculation: a compressed binary format, an uncompressed binary format, a compressed text format, and an uncompressed text format.

7. The mobile source nuclear accident post-evaluation method according to claim 5, characterized in that: By utilizing decoupling calculation, the dose field of each point source is calculated through the corresponding source term data of each point source of the mobile source, the concentration field of each nuclide of each point source and the dose conversion factor, thereby generating the dose field data of the mobile source.

8. The mobile source nuclear accident post-evaluation method according to any one of claims 1 to 7, characterized in that: The diffusion calculation is performed based on a puff model.

9. A mobile source nuclear accident consequence assessment system, characterized in that: The system comprises: A data acquisition module, which acquires geographic data and meteorological data; A meteorological field generation module, which calculates the meteorological field according to the geographic data and the meteorological data, and generates meteorological field data; A source item data acquisition module, which acquires source item data of the mobile source according to a plurality of point sources on the mobile path; a concentration field generating module, which performs diffusion calculation of the mobile source according to the source term data and the meteorological field data to generate concentration field data of the mobile source; and A dose field generating module performs dose calculation according to the concentration field data to generate dose field data of the mobile source.

10. A computing device, characterized in that: It comprises a memory and a processor, wherein the memory stores a computer program, and when the processor runs the computer program stored in the memory, the processor executes the method for evaluating the consequences of a mobile source nuclear accident according to any one of claims 1 to 8.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the processor executes the method for evaluating the consequences of a mobile source nuclear accident according to any one of claims 1 to 8.

Images