Study on the residence time of deep groundwater for high-level radioactive waste geological disposal

Residence time of deep groundwater is one of the most important parameters insafety and performance assessment for high-level radioactive waste geological disposal. In thisstudy, we collected the deep groundwater samples of Jijicao in Gansu Beishan pre-selectedregion. The deep groundwater residence time at two depths estimated by Helium-4accumulation method were 3.8 ka and 5.0 ka respectively upon measurement and calculation,which indicates that the deep groundwater is not derived from the deep crust circulationprocess. Hence, deep groundwater is featured with long residence time as well as slowcirculation and update rate, and such features are conductive to the safe disposal of high-levelradioactive waste.