Diffusion in Crushed Rock and in Bentonite Clay

摘要

Energy production in nuclear power plants produces many kinds of radioactivewastes that must be isolated from the environment long enough for radioactive decay to render them harmless. The most usual method of isolation is disposal in repositories built underground or in bedrock. Nuclear waste repositories are typically planned to be surrounded by some material with a very low hydraulic conductivity. Thus, the flow velocities will be very low and the main transport mechanism is diffusion. This thesis has two main aims: (1) to present in a systematic way standard diffusion theories applied in nuclear waste management and to develop computer programs to solve relevant equations in a few important cases, and (2) to develop a self-consistent model for the diffusion of major ions in bentonite-water systems and to solve this model with efficient numerical methods.