Karachay: geomigration model for unloading section
Creation of 3D Geomigration Model for Unloading Section of Contaminated Groundwaters from the Karachay Lake to the Open Hydrographic Network
Tech Area / Field
- ENV-MRA/Modelling and Risk Assessment/Environment
- INF-SOF/Software/Information and Communications
8 Project completed
Senior Project Manager
VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- Gidrospetsgeologiya, Russia, Moscow\nNPO Mayak, Russia, Chelyabinsk reg., Oziorsk
- Lawrence Livermore National Laboratory, USA, CA, Livermore
Project summaryThe Karachay lake is the biggest open storage of fluid radioactive waste with middle activity in the world. Use of this reservoir as a waste storage leads industrial solutions to filter into the underground hydrosphere that resulted in appearance of contaminated groundwaters halo around the lake stretching from north to south for 10 km. To carry out work on rehabilitation of Karachay region and maintenance of healthy men’s vital functions it is important to be able to give correct contamination value, to forecast its propagation and influence on the hydrographic environment.
At present time contaminated groundwaters have approached to the river valley threatening with contamination unloading to the Mishelyak river, which flows into the Techa river. Working out protective measures to localize the contamination and to prevent its propagation over the boundary of sanitary safe zone is possible only on the basis of long-term scientifically proved forecast of contamination migration in the river valley. Forecast estimation is supposed to answer the questions: when, where and how many radionuclides and chemical components can fall into the open hydrographic network.
The main aim of the present project is to estimate the value of contaminated groundwaters unloading to the Mishelyak river, to locate contaminants falling into the river and timing of this process.
Solving of this problem is possible on the basis of numerical simulation of contamination migration process. It is necessary to create 3D geomigration model because of complexity of hydrogeological and hydrochemical conditions of this region.
Work package on geomigration model development includes:
1. Collecting and processing of materials on characteristics of contaminated groundwaters sources.
2. Preparation of materials on geological massif characteristics.
3. Development of contaminants propagation physical model.
4. Planning of modeling region.
5. Mathematical formulation.
6. Development of mathematical model for contaminants propagation in unloading section of groundwaters to the Mishelyak river including:
– choice of differential equations digitization method and construction of numerical scheme;
– software development;
– carrying out epignose computation;
– estimation of developed model adequacy to geographical description;
– model correction.
Geomigration model development is usually realized in two ways: first – development of mathematical application package which allows to consider the whole variety of conditions and processes taking place, second – satiation of the model with hydrogeological and geochemical source information.
The model must consider all geological, hydrogeological, and hydrochemical features of the region:
– presence of tectonically broken zones with high conductivity;
– development of porous sediment cover with different lithologic structure and variable power;
– sharp heterogeneity and conductivity anisotropy of water-bearing rocks;
– changeability of capacitive properties;
– time variation of water-bearing horizon infiltration feed;
– complicated structure of groundwaters flow;
– density differentiation of groundwaters flow;
– modification of groundwaters level;
– difficulty in connection of ground and surface waters;
– radioactive decay of separate migratory components and delay of main dose-generating radionuclides by rocks (including sorption and desorption processes) and so on.
Important stage in model creation is adjustment of the model and estimation of its adequacy to geographical description based on series of epignose tasks computation.
Use of the developed model will allow to carry out the prediction computations of contamination coming into the Mishelyak river, to estimate the danger of radionuclides propagation over the boundary of sanitary safe zone of IA “Mayak” and to work out the nature-protection package plan.
The developed model will also allow to estimate effectiveness of proposed technical measures on contaminants localization.
At present time 2D and 3D filtration and migratory models for Karachay region have been built, applications GEON-2D, GEON-3D, MIF have been written, simulation of real contaminants migration with GEON code and MIF in 2D formulation have been fulfilled. The developed models allow to describe the process of contaminants propagation from the Karachay lake, to estimate the ways of radionuclides migration, and to determine on half-quantitative level the values of Sr-90 unloading to the Mishelyak river and Techa’s reservoir cascade. However the forecast of radionuclides’ behavior at the local section of river valley is necessary for control decision making and for working out technical measures on contamination localization.
To carry out such computations it is necessary to develop local inset model with the results of GEON-3D or MIF as boundary conditions.
The main aims of the project are:
– creation of geomigration model for section of contaminated groundwaters unloading to the Mishelyak river;
– realization of forecast computations allowing to locate contaminants falling into the open hydrographic network, the time when contaminant components fall into the river and their concentration in unloading groundwaters and in the river;
– working out technical measures allowing to localize the contamination and to prevent its falling into the open hydrographic network (erection of intercepting water scoops, drains, compound drainage etc.);
– modeling of proposed technical constructions work and their effectiveness estimation;
– the most effective technical designs validation;
– carrying out analysis of constructions at preproject stage with the help of developed model.
The developed geomigration model, data base B9-BASE, and worked out mathematical codes can be used for description of other ecologically inauspicious situations.
The project allows to bent efforts of the scientists earlier occupied with nuclear weapons development to investigation of important ecological problem inherited from intense nuclear programs of cold war time. It allows to utilize to the maximum the experience and software of RFNC-VNIITF physicists and mathematicians, of IA “MAYAK” and SGE “Hydrospetsgeologiya” specialists.
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