Preliminary tritium safety analysis and problems with obtaining public consent to deuterium plasma experiments in the LHD

The Large Helical Device (LHD) is the largest super-conducting heliotron type device with two continuous helical winding coils. The first plasma shot in the LHD was carried out in March, 1998, and since then, plasma confinement experiments have been performed. As a future plan, a DD plasma experiment, which is an experiment with deuterium (D) beam injection into D plasma, has been proposed by researchers. Conducting such an experiment is essential for the progress in magnetic fusion research. In DD plasma experiments, tritium and neutrons are generated as a result of nuclear fusion reaction. The maximum annual amount of tritium is about 370 GBq. We are planning to remove tritium with an efficiency greater than 99 %. We conducted a tritium safety analysis and found that for inhabitants around the LHD facility, the annual dose of exposure to tritium is less than 1x10⁻⁷ mSv, which is a result of off gases and effluent liquid being released into the environment. However, to perform DD experiments, we need to obtain public consent, which is not easy. The National Research Institute for Fusion Science (NIFS) is open to the public, and we at the NIFS make every effort to communicate to the public and the municipal governments information on radiation safety. The present report shows results of preliminary safety analysis and problems with obtaining public consent to future experiments of the LHD.