Nuclear accident surface water radioactive migration and diffusion numerical simulation evaluation system

Abstract

The invention belongs to the technical field of nuclear accident consequence evaluation, and particularly relates to a nuclear accident surface water radioactive migration and diffusion numerical simulation evaluation system which is used for simulation calculation and analysis of migration and diffusion numerical values of radionuclides in a surface water environment after a nuclear accident. The simulation module is used for simulation calculation and analysis of migration and diffusion numerical values of radionuclides in a river water area environment; the lake and reservoir water area environment module is used for simulation calculation and analysis of migration and diffusion numerical values of radionuclides in the lake and reservoir water area environment; the system further comprises an ocean water area environment module which is used for simulation calculation and analysis of migration and diffusion numerical values of radionuclides in the ocean water area environment. According to the method, timely calculation modes suitable for different response periods are researched, developed and designed, hydrodynamic force, source item conditions and other related calculation parameters are input, a model is established to carry out nuclide migration and diffusion prediction calculation and evaluation, and scientific and reasonable data support is provided for nuclear accident emergency decision making.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear accident consequence assessment, and in particular relates to a numerical simulation assessment system for radioactive migration and diffusion of surface water in a nuclear accident. Background Art

[0002] In response to the demand for technical capabilities in nuclear accident consequence assessment, many assessment simulation systems, represented by RODOS, have emerged, which have put forward higher requirements for the assessment technical capabilities of water environment, especially surface water environment, in consequence assessment systems. The US NRC has conducted a hypothetical simulation of the migration of pollutants in freshwater environments after accidents. South Korea's KAERI has developed an ocean diffusion model (LORAS) to deal with the migration and diffusion analysis of marine pollutants under accident conditions. IAEA and UNSCEAR have also organized multinational forces to simulate and compare the migration and diffusion of radionuclides in the water environment after accidents. my country urgently needs to establish a consequence assessment model specifically for the water environment to provide technical support for emergency response and decision-making. At present, domestic consequence assessment is basically based on atmospheric diffusion simulation research, and related research on the simulation of the migration and diffusion of pollutants in the water environment is still in a blank stage. Summary of the invention

[0003] The purpose of the present invention is to provide a simulation system that can respond to nuclear accidents in the early, middle and late stages, study water environments including rivers, lakes and oceans, design and develop simple, real-time, fast and timely calculation models, establish radioactive pollutant migration and diffusion models, and predict the laws and paths of nuclide migration and diffusion.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is a numerical simulation evaluation system for the migration and diffusion of radioactive nuclides in surface water after a nuclear accident, which is used for the simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the surface water environment after a nuclear accident. It includes a river water environment module for the simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the river water environment; it also includes a lake water environment module for the simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the lake water environment; it also includes a marine water environment module for the simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the marine water environment.

[0005] Furthermore, it also includes a model building and prediction module, which is used to build a corresponding model and make predictions based on the results of simulation calculation and analysis of the river water environment module, the lake water environment module or the ocean water environment module.

[0006] Furthermore, it also includes a result production module, which is used to display the model and prediction results established by the model establishment and prediction module, and the displayed content includes the model and charts.

[0007] further,

[0008] The river water environment module is provided with a one-dimensional / two-dimensional empirical model of pollutant transport and diffusion in rivers, which is used for simulation, calculation and analysis of the migration and diffusion values ​​of radionuclides in the early stages of nuclear accidents; the one-dimensional / two-dimensional empirical model of pollutant transport and diffusion in rivers is established based on the one-dimensional / two-dimensional convection-diffusion equation and adding the inherent characteristics of radionuclides;

[0009] The hydrodynamic parameters that need to be input include model range, river width, river depth, river velocity, and discrete spatial scale;

[0010] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description;

[0011] By determining the scope and discrete spatial scale of the one-dimensional / two-dimensional empirical model of pollutant transport and diffusion in the river, the early consequences of the accident can be calculated and evaluated, thereby achieving an early emergency response to the nuclear accident.

[0012] further,

[0013] The river water environment module is also equipped with a two-dimensional / three-dimensional river hydrodynamic nuclide migration and diffusion CFD model, which is used for simulation and analysis of the migration and diffusion values ​​of radioactive nuclides in the middle and late stages of nuclear accidents and in the retrospective evaluation stage, so as to achieve the middle and late stages of accidents and retrospective response;

[0014] The accurate solution calculation mode of the river two-dimensional / three-dimensional hydrodynamic nuclide migration and diffusion CFD model includes two types: fast mode and real-time mode;

[0015] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description;

[0016] When using the fast mode, it is also necessary to input the river flow field information of typical water areas, including the flood season, normal water season and dry season;

[0017] When the real-time mode is adopted, it is also necessary to input real-time hydrological parameters and real-time wind field parameters; the real-time hydrological parameters include water level and flow.

[0018] further,

[0019] The lake and reservoir water environment module is provided with a lake and reservoir two-dimensional nuclide migration and diffusion CFD distributed decoupling model, and the lake and reservoir two-dimensional nuclide migration and diffusion CFD distributed decoupling model includes a fast mode, and the fast mode is used for simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the early stage of nuclear accidents;

[0020] The hydrodynamic parameters that need to be input include the model range, lake flow field and river flow field information of typical water areas, and the river flow field information of typical water areas includes the flood season, normal water season and dry season;

[0021] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description;

[0022] By determining the scope of the two-dimensional nuclide migration and diffusion CFD distributed decoupling model of the lake reservoir, the early consequences of the accident can be calculated and evaluated, thereby achieving an early emergency response to the nuclear accident.

[0023] further,

[0024] The lake and reservoir water environment module is also provided with a two-dimensional / three-dimensional nuclide migration and diffusion CFD coupling model of the lake and reservoir, and the two-dimensional / three-dimensional nuclide migration and diffusion CFD coupling model of the lake and reservoir includes a real-time mode, and the real-time mode is used for the simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the middle and late stages of nuclear accidents and the retrospective evaluation stage, so as to realize the middle and late stages of nuclear accidents and the retrospective response;

[0025] The hydrodynamic parameters that need to be input include real-time wind field, real-time flow field, and water level and flow in typical waters;

[0026] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description.

[0027] Furthermore, the marine water environment module is used for accident response to near-shore nuclear facilities and accident response to any point in the far-sea accidents; the near-shore nuclear facilities refer to my country's coastal nuclear facilities; the far-sea accidents at any point refer to the conditions where pollutants from nuclear facilities in other countries leak into the ocean, that is, far-sea accidents.

[0028] further,

[0029] The marine water environment module is provided with a marine two-dimensional nuclide migration and diffusion CFD fast automated distributed decoupling calculation mode, which is used for the simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the early stage of a nuclear accident in the offshore nuclear facility, so as to realize the early emergency response to the nuclear accident;

[0030] The ocean two-dimensional nuclide migration and diffusion CFD fast automated distributed decoupling calculation model needs to determine the model range, and also needs to establish a flow field model of China's coastal waters;

[0031] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description.

[0032] further,

[0033] The marine water environment module is provided with a marine three-dimensional nuclide migration and diffusion CFD real-time coupling calculation mode, which is used for the simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the middle and late stages of nuclear accidents and the retrospective evaluation stage of the offshore nuclear facilities, so as to achieve the middle and late stages and retrospective response to nuclear accidents;

[0034] The ocean three-dimensional nuclide migration and diffusion CFD real-time coupling calculation model requires real-time wind field and real-time flow field data;

[0035] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description.

[0036] further,

[0037] The marine water environment module is also provided with an ocean current model of the National Marine Environmental Forecast Center and a foreign ocean current model;

[0038] The source terms that need to be input include model scope, nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description;

[0039] The ocean current model of the National Marine Environmental Forecast Center and the foreign ocean current model adopt the Lagrangian random free particle model to simulate and calculate and analyze the migration and diffusion values ​​of radioactive nuclides in the early stages of offshore accidents, thereby realizing emergency response to offshore accidents in the early stages.

[0040] Furthermore, the programming languages ​​used by the river water environment module, the lake water environment module, the ocean water environment module, the model building and prediction module and the result production module include Fortran, C# and Python.

[0041] The beneficial effects of the present invention are:

[0042] The research and development design is suitable for timely calculation models in different response periods. It mainly involves three types of surface water environments, namely rivers, lakes and oceans. Regardless of the type of water area, it is necessary to select a timely calculation model according to the different stages of the accident (early, middle and late stages of the accident and retrospective evaluation), input hydrodynamics, source conditions and other relevant calculation parameters, and establish a model to carry out prediction calculation and evaluation of radionuclide migration and diffusion, so as to provide scientific and reasonable data support for nuclear accident emergency decision-making. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1It is a technical flow diagram of a numerical simulation evaluation system for radioactive migration and diffusion of surface water in a nuclear accident described in a specific implementation manner of the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0045] The present invention provides a numerical simulation evaluation system for the migration and diffusion of radioactive substances in surface water during nuclear accidents (see Figure 1 ), which is used for simulation calculation and analysis of the migration and diffusion values ​​of radionuclides in the surface water environment after a nuclear accident. It includes a river water environment module, which is used for simulation calculation and analysis of the migration and diffusion values ​​of radionuclides in the river water environment; it also includes a lake water environment module, which is used for simulation calculation and analysis of the migration and diffusion values ​​of radionuclides in the lake water environment; it also includes a marine water environment module, which is used for simulation calculation and analysis of the migration and diffusion values ​​of radionuclides in the marine water environment.

[0046] It also includes a model building and prediction module, which is used to build corresponding models and make predictions based on the results of simulation calculations and analysis of the river water environment module, the lake water environment module or the ocean water environment module.

[0047] It also includes a result production module, which is used to display the model and prediction results established by the model establishment and prediction module, and the displayed content includes the model and charts.

[0048] The river water environment module is equipped with a one-dimensional / two-dimensional empirical model of pollutant transport and diffusion in rivers, which is used for numerical simulation and analysis of the migration and diffusion of radionuclides in the early stages of nuclear accidents. The one-dimensional / two-dimensional empirical model of pollutant transport and diffusion in rivers is established based on the one-dimensional / two-dimensional convection-diffusion equation and adds the inherent characteristics of radionuclides.

[0049] The hydrodynamic parameters that need to be input include model range, river width, river depth, river velocity, and discrete spatial scale;

[0050] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description, etc.

[0051] By determining the scope and discrete spatial scale of the one-dimensional / two-dimensional empirical model of pollutant transport and diffusion in the river, the early consequences of the accident can be quickly calculated and evaluated, thereby achieving an early emergency response to the nuclear accident.

[0052] The river water environment module also has a two-dimensional / three-dimensional river hydrodynamic nuclide migration and diffusion CFD model, which is used for the simulation and analysis of the migration and diffusion values ​​of radioactive nuclides in the middle and late stages of nuclear accidents and the retrospective evaluation stage, so as to achieve the middle and late stages of accidents and retrospective response;

[0053] The exact solution calculation modes of the river 2D / 3D hydrodynamic nuclide migration and diffusion CFD model include fast mode and real-time mode;

[0054] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description, etc.

[0055] When using the fast mode, it is also necessary to input the river flow field information of typical water areas, including the flood season, normal water season and dry season;

[0056] When using the real-time mode, it is also necessary to input real-time hydrological parameters and real-time wind field parameters; real-time hydrological parameters include water level and flow.

[0057] The lake and reservoir water environment module is equipped with a two-dimensional nuclide migration and diffusion CFD distributed decoupling model for lakes and reservoirs. The two-dimensional nuclide migration and diffusion CFD distributed decoupling model for lakes and reservoirs includes a fast mode, which is used for numerical simulation and analysis of the migration and diffusion of radioactive nuclides in the early stages of nuclear accidents; (Based on the open source calculation code EFDC, secondary research and development of the model was carried out, and a two-dimensional nuclide migration and diffusion CFD distributed decoupling model for lakes and reservoirs was established according to the characteristics of lakes and reservoirs and radioactive nuclides)

[0058] The hydrodynamic parameters that need to be input include the model range, lake flow field and river flow field information of typical water areas. The river flow field information of typical water areas includes the flood season, normal water season and dry season, etc.

[0059] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description, etc.

[0060] By determining the scope of the two-dimensional CFD distributed decoupling model of nuclide migration and diffusion in lakes and reservoirs, it is possible to quickly calculate and evaluate the early consequences of accidents and achieve early emergency response to nuclear accidents.

[0061] The lake and reservoir water environment module also has a two-dimensional / three-dimensional nuclide migration and diffusion CFD coupling model for lakes and reservoirs. The two-dimensional / three-dimensional nuclide migration and diffusion CFD coupling model for lakes and reservoirs includes a real-time mode, which is used for numerical simulation and analysis of the migration and diffusion of radioactive nuclides in the middle and late stages of nuclear accidents and in the retrospective evaluation stage, so as to achieve the middle and late stages of nuclear accidents and retrospective response; (Based on the open source calculation code EFDC, the secondary research and development of the model was carried out, and the two-dimensional / three-dimensional nuclide migration and diffusion CFD coupling model for lakes and reservoirs was established according to the characteristics of lakes and reservoirs and the characteristics of radioactive nuclides)

[0062] The hydrodynamic parameters that need to be input include real-time wind field, real-time flow field, and water level and flow in typical waters;

[0063] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description.

[0064] The marine water environment module is used for accident response to near-shore nuclear facilities and accident response to any point in the far-sea accidents; near-shore nuclear facilities refer to my country's coastal nuclear facilities; any point in the far-sea accidents refers to the conditions where pollutants from nuclear facilities in other countries leak into the ocean, that is, far-sea accidents.

[0065] The marine water environment module is equipped with a CFD fast automated distributed decoupling calculation mode for the migration and diffusion of two-dimensional nuclides in the ocean. The CFD fast automated distributed decoupling calculation mode for the migration and diffusion of two-dimensional nuclides in the ocean is used for numerical simulation and analysis of the migration and diffusion of radioactive nuclides in the early stages of nuclear accidents in offshore nuclear facilities, so as to achieve early emergency response to nuclear accidents; (Based on the open source calculation code EFDC, secondary research and development of the ocean model was carried out, and according to the characteristics of the ocean and radioactive nuclides, a CFD fast automated distributed decoupling calculation mode for the migration and diffusion of two-dimensional nuclides in the ocean was established)

[0066] The CFD rapid automated distributed decoupling calculation mode for the migration and diffusion of two-dimensional nuclides in the ocean requires the determination of the model scope (the model scope actually refers to the calculation domain scope), and the independent establishment of the flow field model of China's coastal waters (that is, the "China Coastal Waters Flow Field Model" is used in the "Marine Waters Environment Module", and the "China Coastal Waters Flow Field Model" is an independently established model);

[0067] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description.

[0068] The marine water environment module is equipped with a marine three-dimensional nuclide migration and diffusion CFD real-time coupling calculation mode, which is used for the numerical simulation and analysis of the migration and diffusion of radioactive nuclides in the middle and late stages of nuclear accidents and the retrospective evaluation stage of offshore nuclear facilities, so as to achieve the middle and late stages and retrospective response to nuclear accidents; (Based on the open source calculation code EFDC, secondary research and development of the ocean model was carried out, and according to the characteristics of the ocean and radioactive nuclides, a marine three-dimensional nuclide migration and diffusion CFD real-time coupling calculation mode was established)

[0069] The CFD real-time coupled calculation model of ocean three-dimensional nuclide migration and diffusion requires real-time wind field and real-time flow field data;

[0070] The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description.

[0071] The marine water environment module also has the ocean current model of the National Marine Environmental Forecast Center and foreign ocean current models (such as NOAA);

[0072] The source terms that need to be input include model scope (model scope refers to the scope to be calculated, that is, the scope to establish the model), nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description, etc.

[0073] The ocean current model of the National Marine Environmental Forecast Center and foreign ocean current models use the Lagrangian random free particle model to simulate and analyze the migration and diffusion of radioactive nuclides in the early stages of offshore accidents, thereby achieving emergency response to offshore accidents in the early stages.

[0074] The river water environment module, lake water environment module, marine water environment module, model building and prediction module and result production module are based on semi-empirical formulas and open source environmental fluid mechanics codes, and the programming languages ​​used include Fortran, C# and Python.

[0075] The device described in the present invention is not limited to the embodiments described in the specific implementation manner. Those skilled in the art may derive other implementation manners based on the technical solution of the present invention, which also fall within the technical innovation scope of the present invention.

Claims

1. A numerical simulation evaluation system for radioactive migration and diffusion in surface water after a nuclear accident, used for simulation calculation and analysis of the migration and diffusion values ​​of radionuclides in the surface water environment after a nuclear accident, characterized by: It includes a river water environment module, which is used for simulation calculation and analysis of the migration and diffusion values ​​of radionuclides in river water environments; it also includes a lake and reservoir water environment module, which is used for simulation calculation and analysis of the migration and diffusion values ​​of radionuclides in lake and reservoir water environments; it also includes a marine water environment module, which is used for simulation calculation and analysis of the migration and diffusion values ​​of radionuclides in marine water environments.

2. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 1, characterized in that: It also includes a model building and prediction module, which is used to build a corresponding model and make predictions based on the results of simulation calculation and analysis of the river water environment module, the lake water environment module or the ocean water environment module.

3. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 2, characterized in that: It also includes a result production module, which is used to display the model and prediction results established by the model establishment and prediction module, and the displayed content includes the model and charts.

4. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 3, characterized in that: The river water environment module is provided with a one-dimensional / two-dimensional empirical model of pollutant transport and diffusion in rivers, which is used for simulation, calculation and analysis of the migration and diffusion values ​​of radionuclides in the early stages of nuclear accidents; the one-dimensional / two-dimensional empirical model of pollutant transport and diffusion in rivers is established based on the one-dimensional / two-dimensional convection-diffusion equation and adding the inherent characteristics of radionuclides; The hydrodynamic parameters that need to be input include model range, river width, river depth, river velocity, and discrete spatial scale; The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description; By determining the scope of the one-dimensional / two-dimensional empirical model of pollutant transport and diffusion in the river and the discrete spatial scale, the early consequences of the accident can be calculated and evaluated.

5. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 4, characterized in that: The river water environment module also has a river two-dimensional / three-dimensional hydrodynamic nuclide migration and diffusion CFD model, which is used for simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the middle and late stages of nuclear accidents and the retrospective evaluation stage; The accurate solution calculation mode of the river two-dimensional / three-dimensional hydrodynamic nuclide migration and diffusion CFD model includes two types: fast mode and real-time mode; The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description; When using the fast mode, it is also necessary to input the river flow field information of typical water areas, including the flood season, normal water season and dry season; When the real-time mode is adopted, it is also necessary to input real-time hydrological parameters and real-time wind field parameters; the real-time hydrological parameters include water level and flow.

6. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 3, characterized in that: The lake and reservoir water environment module is provided with a lake and reservoir two-dimensional nuclide migration and diffusion CFD distributed decoupling model, and the lake and reservoir two-dimensional nuclide migration and diffusion CFD distributed decoupling model includes a fast mode, and the fast mode is used for simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the early stage of nuclear accidents; The hydrodynamic parameters that need to be input include the model range, lake and reservoir flow field, and river flow field information of typical water areas. The river flow field information of typical water areas includes the flood season, normal water season, and dry season. The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description; By determining the scope of the two-dimensional nuclide migration and diffusion CFD distributed decoupling model of the lake reservoir, the early consequences of the accident can be calculated and evaluated.

7. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 6, characterized in that: The lake and reservoir water environment module is also provided with a two-dimensional / three-dimensional nuclide migration and diffusion CFD coupling model for lakes and reservoirs, and the two-dimensional / three-dimensional nuclide migration and diffusion CFD coupling model for lakes and reservoirs includes a real-time mode, and the real-time mode is used for simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the middle and late stages of nuclear accidents and the retrospective evaluation stage; The hydrodynamic parameters that need to be input include real-time wind field, real-time flow field, and water level and flow in typical waters; The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description.

8. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 3, characterized in that: The marine water environment module is used for accident response to near-shore nuclear facilities and accident response to any point in the far-sea accidents; the near-shore nuclear facilities refer to my country's coastal nuclear facilities; the far-sea accidents at any point refer to the conditions where pollutants from nuclear facilities in other countries leak into the ocean, i.e., far-sea accidents.

9. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 8, characterized in that: The marine water environment module is provided with a marine two-dimensional nuclide migration and diffusion CFD fast automated distributed decoupling calculation mode, and the marine two-dimensional nuclide migration and diffusion CFD fast automated distributed decoupling calculation mode is used for the simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the early stage of nuclear accidents in offshore nuclear facilities; The ocean two-dimensional nuclide migration and diffusion CFD fast automated distributed decoupling calculation model needs to determine the model range, and also needs to establish a flow field model of China's coastal waters; The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description.

10. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 9, characterized in that: The marine water environment module is provided with a marine three-dimensional nuclide migration and diffusion CFD real-time coupling calculation mode, which is used for simulation calculation and analysis of the migration and diffusion values ​​of radioactive nuclides in the middle and late stages of nuclear accidents and the retrospective evaluation stage of the offshore nuclear facilities; The ocean three-dimensional nuclide migration and diffusion CFD real-time coupling calculation model requires real-time wind field and real-time flow field data; The source terms that need to be input include nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description.

11. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 8, characterized in that: The marine water environment module is also provided with an ocean current model of the National Marine Environmental Forecast Center and a foreign ocean current model; The source terms that need to be input include model scope, nuclide type, release amount, release location, release time, release duration, nuclide calculation parameters and task description; The ocean current model of the National Marine Environmental Forecast Center and the foreign ocean current model use the Lagrangian random free particle model to simulate and analyze the migration and diffusion values ​​of radioactive nuclides in the early stages of offshore accidents.

12. A numerical simulation evaluation system for radioactive migration and diffusion of surface water in nuclear accidents as claimed in claim 3, characterized in that: The programming languages ​​used by the river water environment module, the lake water environment module, the ocean water environment module, the model building and prediction module and the result production module include Fortran, C# and Python.

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