Monitoring of tritium concentration by simplified active sampler in a fusion test facility

From the viewpoints of radiation management and public acceptance, the monitoring of tritium concentration in the stack is one of the key issues for the deuterium plasma experiment in the Large Helical Device (LHD). Since 2012, an active tritium sampler was employed in the stack to monitor the background levels of tritium and discriminate between its chemical forms. However, the operation procedure became complicated, so we developed a simplified active tritium sampler to reduce the work after sampling. In this sampler system, there was no discrimination between tritium chemical forms, instead, all tritium chemical forms were collected in one process. To verify the performance of the simplified active tritium sampler, tritium concentration data was compared with the existing tritium active sampler and environmental tritium data at the NIFS site. The results revealed a correlation between these tritium data. Therefore, the simplified active tritium sampler was applied in the stack with a primary monitoring system for the deuterium plasma experiment in the LHD. © 2019 The Japan Society of Plasma.