Mistral: A comprehensive model for tritium transport in lithium-base ceramics: Part I: Theory and description of model capabilities

Abstract

MISTRAL is a theoretical model developed to describe tritium transport and release in fine-grained ceramic materials for tritium breeding applications in fusion blankets. The model includes as relevant physical processes tritium diffusion in the effective bulk (grains and grain boundaries), adsorption, recombination and desorption at the breeder surface and diffusion through the network of pores. A key improvement of the model, compared with those already in the literature, consists of a better characterization of the processes at the breeder surface and their linking to the bulk and pore regions. The sets of governing transport equations and corresponding boundary conditions are formulated together with the choice of the computational algorithm. A computer code with transient capabilities has been developed based on the model. It aims at describing tritium release for several transient conditions relevant for in-pile tritium recovery experiments and for fusion blankets. To assess the range of applicability of the model, several calculations have been performed and the results of the analysis are herein presented and discussed.