飽和土壌水中における放射性核種の 非線形吸着モデルに関する研究

Abstract

A number of models of sorption have been used to describe the transport of chemicals through porous media, some representing an equilibrium between the concentration in adsorbed and in solution phase, and some modeling the kinetics to equlibrium. Though analytical solutions for the material balance equation were obtained in linear isotherm systems, some concentration distributions were not expected by them under practical soil conditions. In this study, the finite difference method using quasilinearization technique was applied to solve the palabolic partial differential equation which describes the transport of solutes, and contains the nonlinear sorption equations. These models well describe the shapes of the concentration curves rather than the linear models. So, this numerical approximation appears to have broad and practical utility so as to choose the sorption model of radionuclides to soils and/or to predict the contamination spread accurately in case of the accidental release of radionuclides from a repository into a subsurface aquifaer.