Tech Briefs

Description

Efficient and economical water detritiation is very challenging for large quantities of tritium-contaminated water since tritium is part of the water molecule and exhibits almost identical chemical and physical properties to that of its non-radioactive counterpart. Recently graphene and other 2-D crystals were reported to sieve hydrogen isotopes with 10:1 H/D selectivity, and SRNL predicts even higher H/T selectivity at 58.5. However, typical nuclear operation requires much higher decontamination factor (DF) in the order of 1000 to million or even higher. To scale up and stage the membrane separation efficiently for water detritiation is the core of this patented technology. Methods include counter-current flow of an aqueous stream on either side of a separation membrane in a circulation loop. The separation membrane includes an isotope selective layer ( e.g., graphene) with electrochemical cell for hydrogen pumping. The isotopes selectivity across the membrane magically places lighter isotopes at top and heavier isotopes at bottom with many hundreds of separate stages, as illustrated with H/D example on the right. Beneficially, the methods can be carried out at ambient temperature and pressures and require no electrolysis of the water prior to the separation process. Moreover, the system design greatly simplifies the membrane separation process and can be scaled up economically. It is suitable to remove and recover tritium from contaminated water.