A distributed decoupling calculation method for the migration and diffusion of radionuclides in water environment

Abstract

The present invention relates to a distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment. The distributed decoupling calculation is performed on the hydrodynamic motion equation of radionuclides in a water environment and the nuclide migration and diffusion equation. The migration and diffusion law of nuclides can be quickly calculated to improve the simulation calculation efficiency. The simulation accuracy of nuclide migration and diffusion is improved by optimizing the radionuclide migration and diffusion equation. When the hydrodynamic model cannot output the input parameter data required by the nuclide migration and diffusion model, the external existing input parameter data or the stored historical parameter data is introduced to perform real-time numerical simulation calculation of nuclide migration and diffusion. The method of the present invention has high real-time performance, high accuracy, and wide applicability in aquatic environments. It can timely and efficiently simulate and predict the migration and diffusion behavior law of radionuclides in a water environment, can be applied to nuclear accident consequence assessment, and provide technical basis and support for emergency decision-making at different stages of nuclear accidents. It has practical and application value.

Description

Technical Field

[0001] The invention belongs to the field of water body radiation protection and nuclear accident consequence assessment, and specifically relates to a distributed decoupling calculation method for the migration and diffusion of radioactive nuclides in a water environment. Background Art

[0002] Nuclear accident consequence assessment is a prerequisite for emergency planning and emergency preparedness of nuclear facilities, as well as emergency protection action decision-making. In order to evaluate the consequences of nuclear accidents in a timely and efficient manner, it is necessary to monitor the migration and diffusion behavior of radionuclides in the water environment.

[0003] At present, mature commercial software is usually used to perform numerical simulation calculations on the migration and diffusion behavior of radionuclides in water environments. The migration and diffusion parameters of radionuclides in water environments are calculated by coupling the hydrodynamic motion equation and the nuclide migration and diffusion equation. However, the establishment and verification of hydrodynamic models are cumbersome and rely on sufficient input parameter data. Therefore, they have relatively high requirements on the environment and have certain limitations in responding to the rapid evaluation of the impact of radionuclide migration and diffusion, resulting in low efficiency in nuclide migration and diffusion simulation calculations. Summary of the invention

[0004] In view of the defects existing in the prior art, the purpose of the present invention is to provide a distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment, add nuclide source terms and nuclide inherent characteristics (comprehensive decay coefficient) on the basis of the existing nuclide migration and diffusion equation, perform distributed decoupling calculation on the hydrodynamic motion equation and migration and diffusion equation of radionuclides in a water environment, quickly perform distributed decoupling simulation calculation on the migration and diffusion laws of nuclides, improve the simulation calculation efficiency, and be able to timely and efficiently simulate and predict the migration and diffusion behavior laws of radionuclides in a water environment. At the same time, it can be applied to nuclear accident consequence assessment, provide technical basis and support for emergency decision-making at different stages of nuclear accidents, and has certain practical and application value.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment, the method comprising the following steps:

[0006] S1. Modify the control equations involved in the hydrodynamic model, discretize the output of the hydrodynamic model according to a predetermined format, and form a flow field distributed file;

[0007] S2, adding an input data storage module and / or a real-time flow field data calling module to the nuclide migration and diffusion model, wherein the nuclide migration and diffusion model first determines whether the hydrodynamic model has an output flow field output data file, and if the hydrodynamic model has an output flow field output data file, then receiving the flow field output data file output by the hydrodynamic model;

[0008] S3. If the hydrodynamic model does not output a flow field output data file, directly retrieve existing real-time flow field data from the target area, and process the retrieved real-time flow field data into a preset format;

[0009] S4. Modify the control equations involved in the nuclide migration and diffusion model, develop and integrate the real-time flow field text file reading interface and the nuclide migration and diffusion analytical flow field data file interface to realize the automated calculation of the nuclide hydrodynamics and nuclide migration and diffusion processes in distributed water environments.

[0010] Further, step S1 includes ignoring the change of physical quantity along the water depth direction from the basic equation of incompressible fluid motion, integrating along the water depth direction, and obtaining the modified hydrodynamic motion equation as follows:

[0011] Continuity equation:

[0012]

[0013] The equation of motion for water flow is:

[0014]

[0015]

[0016] in: is the relative base surface water level, m; H is the underwater terrain elevation, m; t is the time, s; ρ is the water density, kg / m 3 ; g is the acceleration due to gravity, m / s 2 ; C is Xie Cai coefficient, m 1 / 2 / s; f is the Coriolis force coefficient, s -1 ; τ sx ,τ sy is the wind-induced stress; Ex, Ey are the generalized eddy viscosity coefficients in the x and y directions, m 2 / s; u and v are the average flow velocities in the x and y directions, respectively, in m / s.

[0017] Furthermore, the output of the hydrodynamic model is underwater terrain elevation H and flow velocity (u, v).

[0018] Further, step S1 also includes

[0019] According to the discrete grid number ID of the hydrodynamic model calculation domain, the set file format is adopted to output the underwater terrain elevation H and flow velocity (u, v) at each moment according to the change over time, and form a flow field distributed file.

[0020] Further, step S3 includes directly retrieving real-time flow field data from the target website if the hydrodynamic model does not output the flow field output data file, and processing the retrieved real-time flow field data into a preset format.

[0021] Furthermore, the target websites include the National Center for Ocean Forecasting and NOAA.

[0022] Further, step S3 includes retrieving the average value of several adjacent recent historical real-time flow field data from the data storage module if the hydrodynamic model does not output the flow field output data file.

[0023] Further, step S3 includes retrieving the historical real-time flow field data of the nearest time from the data storage module if the hydrodynamic model does not output the flow field output data file.

[0024] Further, step S4 includes adding a radionuclide material source term to the radionuclide migration and diffusion equation involved in the nuclide migration and diffusion model and the inherent characteristics of nuclides The modified radionuclide migration and diffusion equation is:

[0025]

[0026] Where: H is the underwater terrain elevation, m; t is time, s; Liquid effluent concentration; Emission concentration; Dx, Dy are diffusion coefficients in the x and y directions, m 2 / s; k is the nuclide-specific coefficient (decay, adsorption and sedimentation), d -1 ; q is the emission, m 3 / s; u and v are the average flow velocities in the x and y directions, respectively, in m / s.

[0027] Further, the nuclide-specific coefficient k is calculated by the following formula, k=k decay +k lm , where the decay effect T is the half-life of the nuclide, s; adsorption and sedimentation A 悬浮 / 颗粒 - equilibrium concentration of radionuclide A in suspended / particulate matter; A 水 -Equilibrium concentration of radionuclide A in fluid water.

[0028] The effect of the present invention is that the distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment disclosed by the present invention has high real-time performance, high accuracy, and wide applicability in aquatic environments. It can accurately reflect the migration and diffusion behavior of radionuclides in coastal water environments in real time, and can timely and efficiently simulate and predict the laws of the migration and diffusion behavior of radionuclides in aquatic environments. It can also be applied to nuclear accident consequence assessment, and provide a technical basis and support for emergency decision-making at different stages of nuclear accidents, and has certain practical and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a method flow chart of a distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0031] Embodiment 1

[0032] like Figure 1 As shown, the present invention discloses a distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment, the method comprising the following steps:

[0033] S1: Based on the open source fluid mechanics model, the control equations involved in the hydrodynamic model are corrected, and the output of the hydrodynamic model is discretized according to a predetermined format to form a flow field distributed file.

[0034] The control equation involved in the hydrodynamic model is the hydrodynamic motion equation, which adopts a general two-dimensional planar mathematical model. The basic equation of incompressible fluid motion ignores the change of physical quantities along the water depth direction, and integrates along the water depth direction to obtain the depth-averaged two-dimensional planar water flow motion equation.

[0035] The corrected hydrodynamic equation of motion is:

[0036] Continuity equation:

[0037]

[0038] The equation of motion for water flow is:

[0039]

[0040]

[0041] in: is the relative base surface water level, m; H is the underwater terrain elevation, m; t is the time, s; ρ is the water density, kg / m 3 ; g is the acceleration due to gravity, m / s 2; C is Xie Cai coefficient, m 1 / 2 / s; f is the Coriolis force coefficient, s -1 ; τ sx ,τ sy is the wind-induced stress; Ex, Ey are the generalized eddy viscosity coefficients in the x and y directions, m 2 / s; u and v are the average flow velocities in the x and y directions, respectively, in m / s.

[0042] According to the above equations, the output of the hydrodynamic model is corrected, and the underwater terrain elevation H and flow velocity (u, v) calculated by the hydrodynamic model are output. According to the discrete grid number ID of the model calculation domain, a self-defined file format is used to arrange and output the underwater terrain elevation H and flow velocity (u, v) at each moment according to the change over time, and form a flow field distributed file, which is convenient for the nuclide migration and diffusion model to call the output of the hydrodynamic model.

[0043] S2: Add an input data storage module and / or a real-time flow field data calling module to the nuclide migration and diffusion model. The nuclide migration and diffusion model first determines whether the hydrodynamic model has an output flow field output data file. If the hydrodynamic model has an output flow field output data file, the flow field output data file output by the hydrodynamic model is received.

[0044] S3: If the hydrodynamic model does not output a flow field output data file, the existing real-time flow field data is directly retrieved from the target area, and the retrieved real-time flow field data is processed into a preset format.

[0045] As an implementation method, if the hydrodynamic model does not output a flow field output data file, the real-time flow field data is directly retrieved from the target website, and the retrieved real-time flow field data is processed and processed into a preset format before performing radionuclide migration and diffusion simulation calculations. The target website includes the National Center for Marine Forecasting and NOAA.

[0046] In general, in the same coastal water environment, the real-time flow field data are basically the same, or the real-time flow field data changes are continuous. As another implementation, if the hydrodynamic model does not output a flow field output data file, the average value of several adjacent recent historical real-time flow field data is retrieved from the data storage module.

[0047] As another implementation, if the hydrodynamic model does not output a flow field output data file, the historical real-time flow field data at the nearest time is retrieved from the data storage module.

[0048] S3: Add radioactive nuclide material source terms and nuclide inherent characteristics to the control equations involved in the nuclide migration and diffusion model for correction, develop and integrate the hydrodynamic flow field text file reading interface and the nuclide migration and diffusion analytical flow field data file interface to realize the automated calculation of the nuclide hydrodynamics and nuclide migration and diffusion processes in distributed water environments.

[0049] Adding a radionuclide material source term to the radionuclide migration and diffusion equation involved in the nuclide migration and diffusion model and the inherent characteristics of nuclides The modified radionuclide migration and diffusion equation is:

[0050]

[0051] Where: H is the underwater terrain elevation, m; t is time, s; Liquid effluent concentration; Emission concentration; Dx, Dy are diffusion coefficients in the x and y directions, m 2 / s; k is the nuclide-specific coefficient (decay, adsorption and sedimentation), d -1 ; q is the emission, m 3 / s; u and v are the average flow velocities in the x and y directions, respectively, in m / s.

[0052] The nuclide-specific coefficient k is calculated by the following formula: k = k decay +k lm , where the decay effect T is the half-life of the nuclide, s; adsorption and sedimentation A 悬浮 / 颗粒 - equilibrium concentration of radionuclide A in suspended / particulate matter; A 水 -Equilibrium concentration of radionuclide A in fluid water.

[0053] Adding Radioactive Nuclide Source Term to Migration-Diffusion Equation and the inherent characteristics of nuclides Can improve the model data fitting accuracy.

[0054] It can be seen from the above embodiments that the invention discloses a distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment, which performs distributed decoupling calculation on the hydrodynamic motion equation of radionuclides in a water environment and the nuclide migration and diffusion equation, can quickly calculate the migration and diffusion law of nuclides, improve the simulation calculation efficiency, and improve the simulation accuracy of nuclide migration and diffusion by optimizing the radionuclides migration and diffusion equation. At the same time, when the hydrodynamic model cannot output the input parameter data required by the nuclide migration and diffusion model, the external existing input parameter data or the stored historical parameter data is introduced to perform real-time numerical simulation calculation of nuclide migration and diffusion. The method of the invention has high real-time performance, high accuracy, and wide applicability in aquatic environments. It can timely and efficiently simulate and predict the migration and diffusion behavior law of radionuclides in a water environment, and can be applied to nuclear accident consequence assessment, providing technical basis and support for emergency decision-making at different stages of nuclear accidents, and has certain practical and application value.

[0055] The method 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 distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment, the method comprising the following steps: S1. Modify the control equations involved in the hydrodynamic model, discretize the output of the hydrodynamic model according to a predetermined format, and form a flow field distributed file; S2, adding an input data storage module and / or a real-time flow field data calling module to the nuclide migration and diffusion model, wherein the nuclide migration and diffusion model first determines whether the hydrodynamic model has an output flow field output data file, and if the hydrodynamic model has an output flow field output data file, then receiving the flow field output data file output by the hydrodynamic model; S3. If the hydrodynamic model does not output a flow field output data file, directly retrieve existing real-time flow field data from the target area, and process the retrieved real-time flow field data into a preset format; S4. Modify the control equations involved in the nuclide migration and diffusion model, develop and integrate the real-time flow field text file reading interface and the nuclide migration and diffusion analytical flow field data file interface to realize the automated calculation of the nuclide hydrodynamics and nuclide migration and diffusion processes in distributed water environments.

2. A distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment as claimed in claim 1, characterized in that: Step S1 includes ignoring the change of physical quantity along the water depth direction from the basic equation of incompressible fluid motion, integrating along the water depth direction, and obtaining the modified hydrodynamic motion equation as the continuity equation: The equation of motion for water flow is: in: is the relative base surface water level, m; H is the underwater terrain elevation, m; t is the time, s; ρ is the water density, kg / m 3 ; g is the acceleration due to gravity, m / s 2 ; C is Xie Cai coefficient, m 1 / 2 / s; f is the Coriolis force coefficient, s -1 ; τ sx ,τ sy is the wind-induced stress; Ex, Ey are the generalized eddy viscosity coefficients in the x and y directions, m 2 / s; u and v are the average flow velocities in the x and y directions, respectively, in m / s.

3. A distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment as claimed in claim 2, characterized in that: The output of the hydrodynamic model is underwater terrain elevation H and flow velocity (u, v).

4. A distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment as claimed in claim 3, characterized in that: Step S1 also includes According to the discrete grid number ID of the hydrodynamic model calculation domain, the set file format is adopted to output the underwater terrain elevation H and flow velocity (u, v) at each moment according to the change over time, and form a flow field distributed file.

5. A distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment as claimed in claim 1, characterized in that: Step S3 includes directly retrieving real-time flow field data from the target website if the hydrodynamic model does not output a flow field output data file, and processing the retrieved real-time flow field data into a preset format.

6. A distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment as claimed in claim 5, characterized in that: The target websites include the National Center for Ocean Forecasting and NOAA.

7. A distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment as claimed in claim 1, characterized in that: Step S3 includes retrieving the average value of several historical real-time flow field data at the nearest adjacent moments from the data storage module if the hydrodynamic model does not output the flow field output data file.

8. A distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment as claimed in claim 1, characterized in that: Step S3 includes retrieving the historical real-time flow field data of the nearest time from the data storage module if the hydrodynamic model does not output the flow field output data file.

9. A distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment as claimed in claim 1, characterized in that: Step S4 includes adding a radionuclide material source term to the radionuclide migration and diffusion equation involved in the nuclide migration and diffusion model. and the inherent characteristics of nuclides The modified radionuclide migration and diffusion equation is: Where: H is the underwater terrain elevation, m; t is time, s; Liquid effluent concentration; Emission concentration; Dx, Dy are diffusion coefficients in the x and y directions, m 2 / s; k is the nuclide specific coefficient, d -1 ; q is the emission, m 3 / s; u and v are the average flow velocities in the x and y directions, respectively, in m / s.

10. A distributed decoupling calculation method for the migration and diffusion of radionuclides in a water environment as claimed in claim 9, characterized in that: The nuclide-specific coefficient k is calculated by the following formula: k = k decay +k lm , where the decay effect T is the half-life of the nuclide, s; adsorption and sedimentation A 悬浮 / 颗粒 - equilibrium concentration of radionuclide A in suspended / particulate matter; A 水 -Equilibrium concentration of radionuclide A in fluid water.

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