Isotope characteristics for the groundwater in the potential site of China's high-level waste repository

Using the isotope techniques, the groundwater origin, evolution and circulation in the potential site of China's high-level waste repository are studied. The results indicate that both groundwaters are mainly recharged by modern and local precipitation, and the deep groundwaters in the site area are of meteoric origin. The shallow groundwaters are mainly-recharged by modern and local precipitation, and the deep groundwaters are originated from regional precipitation at higher elevation, or may be from the precipitation during the geological history period with lower temperature. Through the study we can also understand that the deep underground is a very low-permeability system where the groundwater flow rates are very low. (authors)