Computer simulation methods were used to examine He and H interactions, with radiation-induced vacancies and interstitial atoms, in order to determine the defect formations that were responsible for gas migration. A more mobile mixed cluster, H+2V, was discovered. Reactions were identified which involved the pushing out of He from substitutional positions by self-interstitial atoms, and the pushing out of H by He atoms. The latter reaction raised the possibility that competition between He and H, when they occupied vacancy traps, could cause a reduction in He permeability when compared with H permeability.

V.V.Kirsanov: Fusion Technology, 1995, 28[3], 1200-4