Abstract
The purposes of this thesis are to develop various models including (1) A model of a two-member radionuclides decay chain with linear kinetic sorption in a single fractured porous medium. (2) A model of a two-member radionuclides decay chain with linear equilibrium sorption in the presence of colloids in a single fractured porous medium. (3) A model of single and a two-member radionuclides decay chain with non-linear kinetic sorption in the presence of colloids in a single fractured porous medium. First, in (1), assuming the members of the decay chain have identical transport properties and neglecting all possible intermediate nuclides for simplification. Four models considering kinetic sorption of radionuclides on fracture surface or/and rock matrix is established. Those are, in case 1, radionuclides are sorbed at equilibrium both at the fracture surface and in porous rock (E-E model). In case 2, radionuclides are sorbed at equilibrium at the fracture surface and are kinetically sorbed in porous rock (E-K model). In case 3, radionuclides are kinetically sorbed at the fracture surface and are sorbed at equilibrium in porous rock (K-E model). In case 4, radionuclides are kinetically sorbed at the fracture surface and in porous rock (K-K model). Accordingly, these models can help us understand the effect of the various rate constants and various parents half-lives on the transport of the daughter product. Second, in (2), also assuming the members of the decay chain have identical transport properties. Since the isotopes of plutonium and americium are both radionuclides of strongly sorbing ability, a proper decay chain of is applied. Thus, our model will be more reliable and useful. By sensitivity analyses of model parameters, we can clarify the effect of colloid on the transport of parent radionuclide as well as the daughter product. Finally, in (3), we will study the effect of non-linear kinetic sorption rates for radionuclides on colloids on radionuclide transport in a single fracture. In the model, two kinds of radionuclides with different sorption abilities are selected. is a typical of strongly sorbing radionuclide, is a selection of weakly adsorbing radionuclide. Owing to the difference of their sorption ability, the effect of colloids on those radionuclides are expected not the same. Moreover, a study extended to the transport of the decay chain radionuclides considering nonlinear kinetic sorption will be also included.