Environmental Tritium Around a Fusion Test Facility

Abstract

Deuterium plasma operations using a large fusion test device have been carried out since 2017 at the National Institute for Fusion Science. A small amount of tritium was produced by the fusion reaction, d(d, p)t. Then, a part of the tritium was released into the environment. Thus, monitoring the level of tritium in the environment around the fusion test facility is important. This is done before starting the deuterium plasma experiment. The environmental tritium concentrations indicated that they are at background levels in Japan. After starting the deuterium plasma experiment, the environmental tritium around the fusion test facility was within the range of environmental variation. This suggests that there was no impact of tritium on the environment during the first deuterium plasma experimental campaign.

Isotope Composition and Chemical Species of Monthly Precipitation Collected at the Site of a Fusion Test Facility in Japan

“…This also suggested that there were no impacts by tritium and deuterium on the surrounding environment of the fusion test facility after the deuterium plasma experiment. Additionally, these results supported those reported by Tanaka et al [20]. A committed effective dose equivalent of 6.2 × 10 −6 mSv y −1 was estimated for an annual consumption of drinking water having the highest tritium concentration in precipitation after starting the deuterium plasma experiment (0.47 Bq L −1 ) by using a dose conversion factor of 1.8 × 10 −11 Sv/Bq [39] and a daily water intake rate of 2.0 L [40].…”

“…The tritium concentrations in environmental samples (environmental water, air, vegetation, etc.) were monitored before and after the deuterium plasma experiment to assess the impact of released tritium [17,18,19,20,21]. The tritium concentration levels were within the background range of the environmental variation.…”