Tritium percolation through porous ceramic breeders: A random-lattice approach

摘要

Among the major processes leading to tritium transport through Li ceramic breeders the percolation of gaseous tritium species through the connected porosity remains the least amenable to a satisfactory treatment. The combination of diffusion and reaction through the convoluted transport pathways prescribed by the system of pores poses a formidable challenge. The key issue is to make the fundamental connection between the tortuousity of the medium with the transport processes in terms of only basic parameters that are amenable to fundamental understanding and experimental determinations. This fundamental challenge is met within the following approaches. On the microscale the short range transport is modeled via a convection-diffusion-reaction approach. On a macro scale the long range transport is described within a matrix formalism. The convoluted microstructure of the pore system as prescribed from experimental measurements is synthesized into the present approach via Monte Carlo simulation techniques. In this way the approach requires as inputs only physical-chemical parameters that are amenable to clear basic understanding and experimental determination. In this sense it provides predictive capability. Using this approach the concept of residence time has been analyzed in a critical manner. Implication for tritium release experiments was discussed. 14 refs., 5 figs., 1 tab.