Comprehensive Assessment of Tritium to the Environment Discharged By Deuterium Plasma Experiment Using Large Helical Device, Japan

Abstract At the National Institute of Fusion Science (NIFS), the deuterium plasma experiment was conducted using the large helical device (LHD) from 2017 to 2022 for the high performance of the plasma experiment. Through this experiment, a small amount of tritium was produced by D-D fusion reaction and released to the atmospheric environment through the stack. To understand the impact of tritium on the environment, environmental tritium monitoring was conducted before, during, and after the experiment for public acceptance and in accordance with local governments. From this monitoring, no impacts were observed on monthly precipitation and pine needle samples at the NIFS site. As the result of a comprehensive assessment combined with atmosphere and environmental water monitoring, it was concluded that the impact of discharged tritium from the stack of LHD to the surrounding environment would be none and/or negligibly small.