Tritium in the quantum sieve: First-ever separation of the three hydrogen isotopes for the fuel cycle of nuclear fusion

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"... As a result, the isotopes are released at different temperatures when the zeolite is heated: protium desorbs first, followed by deuterium and finally tritium. ...

The decisive step was the experiment using tritium. “It’s the first time anyone has managed to separate a hydrogen isotope mixture of protium, deuterium and tritium using a porous solid material,” ... After contact with the silver-containing zeolite, the mixture that initially contained equal amounts of the three isotopes emerged with an H₂:D₂:T₂ ratio of 1:41:175 . So, tritium was retained much more strongly than deuterium, while protium was hardly retained at all. ...

The material also exhibited high selectivity in experiments with mixtures of two isotopes. The greatest difference was observed between tritium and protium. “These are not just marginal differences,” ... “The separation process is highly efficient even in a single step.” The results also represent an important milestone for fundamental research, as they provide the first experimental validation of theoretical predictions involving tritium.

Another aspect is the stability of the material. Tritium undergoes radioactive decay, emitting beta radiation that could potentially damage the silver sites in the zeolite. However, even after several hours of exposure to tritium, the experiments revealed no measurable decline in separation performance. ..."

Tritium in the quantum sieve: HZDR team achieves first-ever separation of a hydrogen isotope mixture containing tritium using quantum effects - Helmholtz-Zentrum Dresden-Rossendorf, HZDR "Fusion power plants of the future will not only require extremely hot plasmas and strong magnetic fields but also a fuel cycle in which the hydrogen isotopes deuterium and tritium can be recovered, separated, and reused. ... a team ... has now demonstrated a highly efficient method for separating hydrogen isotopes using a silver-containing zeolite  ... Zeolite is a porous crystal material with a network of tiny cavities. ... The results represent an important advance in isotope separation and lay the foundation for the efficient recovery and processing of tritium in future fusion fuel cycles. They also open up potential applications in medicine and materials research."

From the abstract:

"Efficient separation of hydrogen isotopologues is crucial for applications such as the recycling of exhaust streams in nuclear fusion reactors.

We report on separation of a ternary 1,2,3H isotope mixture using thermal desorption spectroscopy (TDS), achieving an enrichment of 1:41:175 (H2:D2:T2) from an initially equimolar (1:1:1) gas mixture, based on selective adsorption using an Ag(I)-exchanged zeolite type Y.

Further experiments on binary hydrogen isotope mixtures validated numerical predictions of the separation efficiency for T2.

Specifically, the high selectivity for tritium over protium of 244 makes the Ag(I)-exchanged zeolite an excellent candidate for energy-efficient isotope separation at liquid-nitrogen temperature."

Tritium separation from gaseous 1,2,3H isotopologue mixtures by selective adsorption on Ag-exchanged zeolite type Y (open access)

Credits: Recycling für die Kernfusion: Leipziger Team gelingt fast unmögliche Trennung