Retention and recycling of plasma edge hydrogen isotopes in C and TiC

Abstract

The retention, release, and isotopic exchange of hydrogen, deuterium, and tritium incident on room temperature C and TiC with Maxwellian velocity and isotropic angular distributions have been calculated using the Local Mixing Model. The calculations are based on the hydrogen saturation concentration, range distributions and isotopic exchange behavior, all of which have been verified experimentally by monoenergetic implants. Particle fluences (10 16 to 10 20/cm 2) and characteristic Maxwellian energies (50 eV to 3200 eV) were chosen in the range of interest for tokamak plasma edge conditions. The results of these calculations are used to estimate tritium inventory buildup and to predict tritium changeout rates by isotopic exchange in tokamaks and other fusion devices. Tritium inventories in the TiC components (which comprise ≳ 20% of the TFTR first-wall surface) are anticipated to remain at reasonable levels in TFTR, and isotopic exchange is shown to be a feasible method to reduce these tritium inventories.