Superpermeability in Fusion Technology: Tritium Accumulation and Compression

Superpermeable membranes based on Group Va metals can be applied in fusion devices for a short way separation of D/T mixtures from He, for an active control of particle fluxes and as a general-purpose D/T pump that may be used in particularly in tritium handling systems. Superpermeable membranes being used for D/T separation from helium are able to drastically reduce the tritium load on the He pump (cryopump), while tritium accumulation in the membrane itself does not exceed a few g for a machine of ITER scale. A possible way to decrease the tritium inventory in the membrane is to combine a higher dissociative barrier at the upstream surface with the operation at higher temperature. Compression of permeating D/T attainable with superpermeable membranes is totally determined by the sticking coefficient of thermal hydrogen molecules at the upstream surface. The degree of compression has a significant effect on the tritium inventory and the inventory dependence on the state of the downstream surface.¹ Permanent address: Bonch-Bruyevich University, 61 Moika, St. Petersburg 191186, Russia