Tritium issues toward fusion plants

Technical issues on tritium technology are investigated from the aspects of processing, safety and fuel supply, considering the concept of DEMO plant following ITER as the next target. Fusion plant equipped with power blanket will contain high temperature heat transfer medium and bred tritium in a tritium cycle. Although the inventory and throughput may not increase drastically from ITER, tritium plant will require significant technical improvements characterized by the self-consistent tritium fuel cycle and safety function to maintain the tritium level in the power train at adequately low level. Tritium balance issue will be one of the most important features because it will strongly affect the fusion in energy market by supplying initial loading. Tritium processing for coolant that will be mainly used for normal operation will dominate the safety feature of the entire plant by its technical difficulty and importance. Under off-normal conditions, this coolant tritium process can remove possible spill within the confinement, and thus fusion plant will not have any major process dedicated for accidents. Tritium technology is essential to make fusion energy attractive from the aspect of socio-economics, and its success in development is of vital importance toward fusion power plant as viable energy source for future.