Fusion Energy and Tritium Fuel Cycle: Hydrogen Isotope Separation Technologies and Sorbent Materials

Fusion using tritium and deuterium as the fuel has the potential for large-scale carbon-free energy generation but faces several key technical challenges; One of these is the need to develop a hydrogen isotope separation technique with the combined requirements of high separation and energy efficiency and low tritium inventory. Since only a small fraction of the injected fuel undergoes fusion per cycle, the mixture of hydrogen isotopes must be recycled and the isotope composition rebalanced, requiring hydrogen isotope separation. This task is technically complex because hydrogen isotopes exhibit nearly identical physicochemical properties making them difficult to separate conventionally. Cryogenic distillation currently serves as the reference technology for isotope separation but suffers from high energy demand, extreme cryogenic operating temperatures, and significant tritium hold-up. Sorbent-based processes have emerged as promising candidates, offering advantages in scalability, energy efficiency, and isotope selectivity. Sorbent materials that could be used in these processes have been reported to have high hydrogen isotope selectivity and so could have significant potential. This review examines recent advances in sorbent development and their integration into separation processes relevant to fusion fuel cycles, while also addressing key challenges such as stability, radiolytic degradation, and tritium exchange in organometallic porous adsorbents.