TRITIUM INVENTORY AND PERMEATION IN THE ITER BERYLLIUM

Beryllium is presently selected for use in International Thermonuclear Experimental Reactor (ITER) as the primary plasma-facing material. The surface conditions of the beryllium as well as its tritium diffusion and solubility coefficients will determine the permeation rate of tritium to the coolant of ITER. The in-vessel tritium inventory will be affected by these coefficients and the neutron damage-induced trap density and energy. This paper presents the results of modeling of the permeation and inventory of tritium in the beryllium components of ITER. The DIFFUSE computer code was used for this modeling. Diffusivities, solubilities, surface conditions, trapping densities, and trapping energies were extracted from the most recent laboratory studies. The code predicted that the tritium inventory is a strong function of both the assumed surface recombination rate constant and the trap density.