The application and development of geochemical modeling in high-level radioactive waste disposal

Abstract

With the development of nuclear industry, the treatment and disposal of radioactive wastes are becoming increasingly urgent and challenging. Investigation of the migration behavior of radionuclides in the environment is the most important and direct way to obtain the basic parameters used to assess the influence of radionuclides on the surrounding environment and peoples health. In recent years, geochemical models based on numerical method, using the experimental data, thermodynamic and kinetic data of radionuclides has been established to analysis the continuous and long-term change of radionuclides in geological media. Up to now, there are more than ten geochemical codes commonly used in the world. In this paper, a brief introduction of geochemical models in terms of thermodynamic equilibrium principles, speciation distribution calculation methods and surface complexation assumptions are presented. Case study in the application and development of geochemical models with respect to the speciation calculation and surface complexation is disscussed. Furthermore, an example of Ca-U-CO3 complex is used to elucidate the importance of the integrality of the thermodynamic database, in order to propagate the application and development of geochemical models in China.