Journal of NUCLEAR SCIENCE and TECHNOLOGY, Vol. 40, No. 11, p. 975–979 (November 2003)
TECHNICAL REPORT
Development of a Code MOGRA for Predicting the Migration of Ground Additions and Its Application to Various Land Utilization Areas Hikaru AMANO1,* , Tomoyuki TAKAHASHI2 , Shigeo UCHIDA3 , Syungo MATSUOKA4 , Hiroshi IKEDA4 , Hiroko HAYASHI4 and Naohiro KUROSAWA4 2
1 Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-1195 Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 3 National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba 263-8555 4 Visible Information Center, Inc., Tokai-mura, Naka-gun, Ibaraki 319-1112
(Received June 6, 2003 and accepted in revised form July 25, 2003) A Code MOGRA (Migration Of GRound Additions) is a migration prediction code for toxic ground additions including radioactive materials in a terrestrial environment, which consists of computational codes that are applicable to various evaluation target systems, and can be used on personal computers. The computational code has the dynamic compartment analysis block at its core, the graphical user interface (GUI) for model formation, computation parameter settings, and results displays. The compartments are obtained by classifying various natural environments into groups that exhibit similar properties. The functionality of MOGRA is being verified by applying it in the analyses of the migration rates of radioactive substances from the atmosphere to soils and plants and flow rates into the rivers. In this report, a hypothetical combination of land usage was supposed to check the function of MOGRA. The land usage was consisted from cultivated lands, forests, uncultivated lands, urban area, river, and lake. Each land usage has its own inside model which is basic module. Also supposed was homogeneous contamination of the surface land from atmospheric deposition of 137 Cs (1.0 Bq/m2 ). The system analyzed the dynamic changes of 137 Cs concentrations in each compartment, fluxes from one compartment to another compartment. KEYWORDS: MOGRA, dynamic compartment model, radionuclide, migration, GUI, data base, functionality
I. Introduction To evaluate the effects of environmental-load substances such as radioactive ones that impose environmental loads it is essential to identify the migration patterns and behaviors of these substances in the environments of the human life sphere. The mechanisms affecting their migration patterns and behaviors are very complicated and cover a wide range of disciplines including physics, chemistry and biology.1–3) Figure 1 shows the outline of main phenomena related to migration of environmental radionuclides in the surface environment. In addition, as the human life sphere contains a mixed variety of land usage modes (including forests, farming fields and rice paddies), the migration patterns of the substances in each of the various land usage classifications are quite diverse. To evaluate these effects, it is effective to use mathematical models of dynamic compartment model.4) In such models, fluxes and parameters between compartments usually described as time dependent movement of radionuclides between the various environmental compartments. As a convenient means of analyzing and predicting the migration of the substances under the above conditions, Japan Atomic Energy Research Institute (JAERI) has developed the fundamentals of the MOGRA (Migration Of GRound Additions) code, a universal migration prediction code for toxic ground additions including radioactive materials in the terrestrial environment. The code MOGRA is a generic code which solves dynamic ∗
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compartment model and can apply in every occasion using a personal computer. In cases of terrestrial contamination, not only atmospheric discharge but also groundwater/soil contamination can be analyzed in the consequences considering the phenomena shown in the Fig. 1. Compartment settings are usually made considering the sizes of homogeneous environmental target media appropriately. To save calculation time, not only the number of the compartments but also the time interval for the calculation should appropriately be set. Remarkable progress of personal computer in these days makes these calculations possible in reasonable time. Here, we describe the Code.
II. Concepts and Function of MOGRA 1. Concepts MOGRA is a migration prediction code for toxic ground additions including radioactive materials in a terrestrial environment. The code MOGRA consists of computational codes that are applicable to various evaluation target systems, and can be used on personal computers. The computational code has the dynamic compartment analysis block at its core, the graphical user interface (GUI) for computation parameter settings and results displays, data files and so on. The compartments are obtained by classifying various natural environments into groups that exhibit similar properties. The concept of MOGRA is shown in the Fig. 2. This code is able to create or delete compartments and set the migration of environmental-load substances between compartments by a simple mouse operation.
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H. AMANO et al. Deposition
Diffusion Radioactive Material, Gas, Particle
Effluent
Deposition
Resuspension
Plant Ground Surface
Erosion Nuclear Facilities
Soil
Plant Uptake
Elution
Runoff River
Penetration
Radioactive Waste Lake
Deposition Ground Water
River
Deposition
Sea
Fig. 1 Main phenomena related to migration of environmental radionuclides in the surface environment
Modules
Cultivated lands Paddy field Orchard Farm
Forest Uncultivated Land Urban area River, Lake
Classification of Land by Topography and Land Use
Experiment & Observation Migration, Transfer, Runoff,Accumulation
Nuclide j Decay Inflow
Numerical formula
Compartments
Data Files
Compartment m
Setting Parameters for Calculation by GUI
Calculation
Display the Results by GUI
Analysis
Decay Outflow
Nuclide i
Compartment l
Compartment n
Compartment o
Nuclide i
Nuclide i
Nuclide i
GUI : Graphical User Interface
Fig. 3 Block diagram of a dynamic compartment model Fig. 2 Concept of MOGRA
The system features high universality and excellent expandability in the application of computations to various nuclides. An evaluation begins with a classification of the target land according to a land usage classification (modularization). Next, desired compartments are set within each module together with the setting of migration patterns of substances between modules. The flow of environmental-load substances between compartments is expressed in the formulae obtained from theoretical consideration and scientific experimental results, which is written in FORTRAN 77. When a compartment in a module is subject to pollution by an environmentalload substance, these codes can be used to evaluate how and how much/far the surrounding environments will be polluted in the future. 2. Analysis Method In this code, the simultaneous ordinary differential equations are solved by using the sixth-step fifth-order Runge– Kutta method which is called the Fehlberg formula. The dy-
namic change of the amount in the compartment m in Fig. 3 is expressed as follows, and the dynamic change of the amount in each compartment is expressed in same manner, then the equations same as the number of the dynamic compartments in the model are solved at the same time: dYm,i = − km→l,i + λm,i + λi Ym,i dt l=m +
l=m
kl→m,i Yl,i +
p j →i λ j Ym, j + qm,i ,
j =i
here, Ym,i , Ym, j : Amount of Nuclide i, j in the Compartment-m (atom) Yl,i : Amount of Nuclide i in the Compartment-l (atom) km→l,i : Transfer factor of Nuclide i from the Compartmentm to the Compartment-l (1/yr) kl→m,i : Transfer factor of Nuclide i from the Compartmentl to the Compartment-m (1/yr)
JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Development of a Code MOGRA for Predicting the Migration of Ground Additions
λm,i : Elimination factor of Nuclide i from the Compartment-m (1/yr) λi , λ j : Decay constant of Nuclide i, j (1/yr) p j →i : Branching ratio of Nuclide i qm,i : Inflow factor of Nuclide i into the Compartmentm (atom/yr). 3. System Feature of MOGRA MOGRA is used on a Windows based personal computer. MOGRA is composed with 3 programs and FORTRAN compiler described below. The structure of MOGRA is shown in the Fig. 4. (1) MOGRA for Windows The user of MOGRA can arrange the Compartment Model templates connection by dragging templates and connector. Calculation condition parameters such as time interval and
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through time end can be put on GUI. Calculation results are presented in Tables and Figures on the CRT of a personal computer. (2) MOGRA Compartment Model Editor MOGRA Compartment Model Editor creates and compiles compartment models of each module which will be used on MOGRA for Windows on the GUI of a computer. MOGRA Compartment Model Editor also compiles transfer equations and parameters of each compartment model. The created and compiled compartment models can easily be reported and printed. (3) MOGRA Calculation Program MOGRA Calculation Program calculates according to the equation described in Sec. II-2 using calculation condition data files from the MOGRA for Windows. The calculation results is brought to the MOGRA for Windows.
III. Examples for Application to Land Contamination
Fig. 4 The structure of MOGRA
1. Atmosphere–Plant–Soil Figure 5 shows an example which analyzes time dependent contamination of surface soil and plant, created using the MOGRA Compartment Model Editor. In this figure, firstly the soil surface and plant surface are contaminated with radioactive 90 Sr. We can assume for example that the growth period of the vegetables is 60 d and that 90 Sr is emitted in the initial 10 days or 60 days of growth. We also assume that the 90 Sr deposition on the target land is 100 Bq/m2 . Then, we predict the 90 Sr concentrations on their surfaces and internally throughout their growth period of 60 d. Figures 6 and 7 shows the result using the MOGRA for Windows. In the Fig. 6, the total surface and internal concentration of the vegetables reaches a maximum value immediately after the end of emissions, while the concentration inside the vegetables reaches a maximum value within 2 d of the completion of the emission under continuous discharge of 10 d. The figure also
Fig. 5 Example of a Model (Atmosphere–Plant–Soil) constructed using MOGRA Compartment Model Editor (Right side figure explains the meaning of each arrow)
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Forest-2
Forest-1
Urban River-1 (Upstream)
Lake Cultivated land-1
Uncultivated land
Fig. 6 Dynamic change of 90 Sr concentration in plant (Total, surface and inside) under continuous discharge of 10 d
Fig. 7 Dynamic change of 90 Sr flux from atmosphere to plant and soil under continuous discharge of 60 d
shows that the total concentration at the harvest period after 50 d from the termination of the emission drops to about 2% of the value immediately after the emission, and that most of this concentration is inside the vegetables. Figure 7 shows the 90 Sr fluxes from atmosphere to soil and plant surface under continuous discharge of 60 d. Because of the low density of the vegetation in the first 10 days, most flux of 90 Sr from the atmosphere is to soil surface in the first 10 days. Along with the growth of the vegetation, the flux to plant exceeds that to soil around the 30th day. In the figure, daily flux to the vegetation from atmosphere increases according to sigmoid curve, because the growth rate of the vegetation follows a sigmoid curve. 2. Functionality of MOGRA, Its Application to Various Land Utilization Areas The functionality of MOGRA is being verified by applying it in the analyses of the migration rates of radioactive substances from the atmosphere to soils and plants and flow rates into the rivers. This has been achieved by also taking their mode classifications into consideration. A hypothetical combination of land usage as shown in Fig. 8 was supposed to check the function of MOGRA. Figure 8 was constructed us-
Cultivated land-2
Cultivated land-3
River-2 (Downstream)
Fig. 8 Hypothetical environment constructed on PC-CRT using MOGRA for Windows
Fig. 9 Dynamic changes of 137 Cs in crops in cultivated land (1), (2) and (3) The change of 137 Cs concentration with elapsed time in cultivated land (1) and cultivated land (2) is same under homogeneous atmospheric deposition of 137 Cs in the model. So, their lines representing 137 Cs concentration in crop in cultivated land (1) and (2) in the figure overlap with each other.
ing the MOGRA for Windows. The land usage was consisted from cultivated lands, forests, uncultivated lands, urban area, river, and lake. The arrows represent the flow of target materials among each land usage. In this example, major flows of target material are toward river and lake. Each land usage has its own inside model which is basic module, for example, as shown in the Fig. 5. The details of each module are presented elsewhere.5) Also supposed was homogeneous contamination of the surface land from atmospheric deposition of 137 Cs (1.0 Bq/m2 ). Figures 9 and 10 show a few example of results gained from MOGRA for Windows. Figure 9 shows dynamic changes of 137 Cs in crops in cultivated land (1), (2) and (3) of Fig. 8 during the growth period, respectively. The change of 137 Cs concentration with elapsed time in cultivated land (1) and cultivated land (2) is same under homogeneous atmospheric deposition of 137 Cs in the model. Peak concentration in the cultivated land (3) appears 2.5 years after the initial de-
JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Development of a Code MOGRA for Predicting the Migration of Ground Additions
Fig. 10 Dynamic changes of 137 Cs fluxes between lake water and lake sediment
position on cultivated land, because in the model the lake water is used for irrigation to the cultivated land (3). Figure 10 shows dynamic changes of 137 Cs fluxes, one is from lake water to lake sediment, the other is from lake sediment to lake water. These results can easily be seen on the CRT of a computer using MOGRA.
IV. MOGRA Data Bases Code MOGRA-DB, Graphic Map Code MOGRA-MAP and Future Plans The code MOGRA has varieties of databases, which is called MOGRA-DB. This additional code MOGRA-DB consists of radionuclides decay chart, distribution coefficients between solid and liquid, transfer factors from soil to plant, transfer coefficients from feed to beef and milk, concentration factors, and age dependent dose conversion factors for many radionuclides. The exact features of MOGRA Data Bases are presented elsewhere.6) Another additional code MOGRA-MAP can take in graphic map such as JPEG, TIFF, BITMAP, and GIF files, and calculate the square measure about the target land. MOGRA will be connected with the GIS (Geographical Information System) data bases which consist of soil map, Geomorphological Land Classification Map, Subsurface Geological Map, Land Utilization Map, and Water Utilization Map, developed by Ministry of Land, Infrastructure and Transport, Government of Japan. Also will be introduced are the sensitivity analyses, the probabilistic analyses of environmental parameters. MOGRA will be connected with atmospheric dispersion models, groundwater flow models and ocean pollution prediction models.
V. Conclusion MOGRA consists of computational codes that are applicable to various evaluation target systems, and can be used on
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personal computers. The computational code has the dynamic compartment model analysis block at its core, the graphical user interface (GUI) for computation parameter settings and results displays, data files and so on. The compartments are obtained by classifying various natural environments into groups that exhibit similar properties. These codes are able to create or delete compartments and set the migration of environmental-load substances between compartments by a simple mouse operation. The system features high universality and excellent expandability in the application of computations to various nuclides. The flow of environmental-load substances between compartments is expressed in the formulae obtained from theoretical consideration and scientific experimental results. When a compartment in a module is subject to pollution by an environmental-load substance, these codes can be used to evaluate how and how much/far the surrounding environments will be polluted in the future.
Acknowledgments Prof. S. Matsumoto, Saitama University encouraged us very much for the development of MOGRA. MOGRA has been developed in the framework of the 3rd Nuclear Energy Generic Cross-over Research under the auspices of the Ministry of Education, Culture, Sports, Science and Technology, Japan. References 1) P. J. Coughtrey, M. C. Thorne, Radionuclide Distribution and Transport in Terrestrial and Aquatic Ecosystems: A Critical Review of Data, Volume 1, A. A. Balkema, Rotterdam, 1 (1983). 2) A. S. Szabo, Radioecology and Environmental Protection, Ellis Horwood, New York, 40 (1993). 3) J. R. Cooper, K. Randle, R. S. Sokhi, Radioactive Releases in the Environment: Impact and Assessment, John Wiley & Sons, New York, 381 (2003). 4) J. R. Cooper, K. Randle, R. S. Sokhi, Radioactive Releases in the Environment: Impact and Assessment, John Wiley & Sons, New York, 344 (2003). 5) H. Amano, T. Takahashi, S. Uchida, S. Matsuoka, H. Ikeda, H. Hayashi, N. Kurosawa, “Application of MOGRA for migration of contaminants through different land utilization areas,” Proc. Int. Sympo. on Transfer of Radionuclides in Biosphere— Prediction and Assessment, To be published in JAERI-Conf 2003-0010, (2003). 6) H. Amano, H. Ikeda, T. Sasaki, S. Matsuoka, N. Kurosawa, T. Takahashi, S. Uchida, “MOGRA-DB: Database System for Migration Prediction Code MOGRA,” Proc. 4th Workshop on Environmental Radioactivity, Tsukuba, Japan, To be published in KEK Proceedings, (2003), [in Japanese].
