Performance of exhaust detritiation system for a fusion test device in the initial phase of the operation

摘要

The exhaust detritiation system (EDS) has been operating for the deuterium plasma experiment in large fusion test device since 2016. The EDS consists of two systems: the molecular sieves (MS) type for plasma exhaust gas, the polymer membrane (PM) type for vacuum vessel purge gas during the maintenance activity. The tritium removal performance of the EDS was evaluated for four years. As the operation results, the maximum detritiation factor (DF) of the MS system was achieved to be more than 10(3) even though the average tritium concentration in the process gas was less than 10(4) Bq/m(3). On the other hand, the DF of the PM system was less than 10(3), because the average tritium concentration during the vacuum vessel maintenance activity was at the order of less than 10(2) Bq/m(3). Throughout the initial phase of the deuterium plasma experiment, the tritium concentration at the outlet of EDS was maintained to be less than the order of 10(2) Bq/m(3). Also, a failure analysis was performed to evaluate the reliability of the EDS in the initial phase of the operation. Over the four years of operation, the overall failure rate of the MS system was on the order of 10(-5) events/hour.