Study on the long-term stability of the geological environment; Current status and prospect of development of dating technique about study on long-term stability, 2; Development of (U-Th)/He dating technique; Aming at the practical use of dating technique at the first case in Japan

Hanamuro, Takahiro  ; Yamada, Kunimi; Umeda, Koji

(U-Th)/He dating method is one of the radioactive dating methods by using alpha-decay nuclides and producing He, and it is practically applied at apatite and zircon those closed temperature are determined. This method is also expected to apply the effect of low-temperature (ca.100C) geothermal activities, that is important for maintenance of overpack performance at geological disposal, or determination of fault activities, etc.. There are no facilities for dating this method in Japan, so, JAEA started system installation and research for the measurement from fiscal year 2006, aiming at the practical use of (U-Th)/He dating technique at the first case in Japan. The prospect of practical use of the dating for zircon was obtained now. Age-known samples are already analyzed and geological samples are analyzing. This dating method for apatite are scheduled to be established in this fiscal year.