Study on cascade configuration and hydrogen isotope inventory of cryogenic distillation columns for isotope separation system of the ITER tritium plant

The Isotope Separation System (ISS) for the ITER FDR steady state plasma operation (burn time 10,000 s, fuelling throughput 200 Pa m3/s) was designed on the basis of a substantial reduction of hydrogen flow rate from water detritiation system. Three feed streams (plasma exhaust gas, streams from the CECE and from the NB injectors) are fed to the ISS. A four-column cascade was proposed in this study considering a scenario of phased construction of ITER. The maximum refrigeration duty was reduced to be 44 % of that of the original design of the FDR-ISS. This is mainly because of the elimination of a large re-circulation deuterium flow in this cascade. The maximum tritium inventory of this study was about the same that of the original FDR-ISS, but substantial reduction of tritium inventory is found to be possible with the progress in the investigation of the correspondent flow rate of tritium product stream (T > 90%) for pellet with the option of operation condition. (author)