Speakers
Description
Forecast of engineering barriers evolution is an important problem of radioecology.
The goal of the following study is the development of complex methodology of modeling different processes, occurring during evolution of multibarrier system, and creating a uniform approach to safety analysis.
Methods of the description of the major factors, important for modeling multibarrier system (thermal emission, illitization of bentonite buffer, degradation of concrete and glass matrices, corrosion of a metalwork, processes on barrier/barrier border) are developed.
Algorithms of sodium phosphate glass matrix leaching modeling, corrosion of steel, degradation of concrete, bentonite evolution at a chloritization and an illitization are developed. The described algorithms are implemented in the form of templates for calculation of chemical processes at specific conditions of barriers evolution.
The basic structure of the main modules of DESTRUCT software is created. It consists of blocks of data processing, modeling of evolution processes of safety barriers, modeling of radionuclides migration in a near field, postprocessings of calculation results, interactions between the blocks providing prognosis of dynamics of parameters changes of materials.
The developed models are tested on the example of calculation of processes of barriers degradation and radionuclides transport for a a prospective Russian radioactive waste disposal site.
Results of leaching calculation from various glass matrices, calculations of corrosion rates in anaerobic conditions in a bentonite environment depending on temperature and acidity of the environment, changes of of mineral phases array in concrete are presented in this study
Application of DESTRUCT has allowed to estimate rate of steel corrosion in. The illitization is proved to be neglectible at predicted temperature fields.
As a result of test of DESTRUCT complex a number of problems of various barriers evolution assessment and radionuclide transport are solved. Influence of physical and chemical processes on evolution of parameters of steel corrosion and evolution of concrete barriers, bentonite swelling, evolution of glass matrices and also radionuclide transport through the multibarrier system for a prospective radioactive waste disposal is estimated.
Tests have shown efficiency of the applied approaches to assessment of evolution of multibarrier system. At the same time need for development and updating of chemical models of processes is confirmed.
