Assesment of tritium activity in groundwater at the nuclear objects sites in Lithuania

The assessment of nuclear objects sites in Lithuania, including groundwater characterization, took place in the last few years. Tritium activity in groundwater is a very useful tool for determining how groundwater systems function. Natural and artificial tritium was measured in 8 wells in different layers (from 1.5 to 15 meters depth). The results were compared with other regions of Lithuania also. The evaluated tritium activities varied from 1.8 to 6.4 Bq/l at nuclear object sites in Lithuania and it is coming to background level (1.83 Bq/l) and other places in Lithuania. The data show, that groundwater at the nuclear power object sites is not contaminated with artificial tritium. In this work the vertical tritium transfer from soil water to the groundwater well at nuclear objects site was estimated. The data show, that the main factor for vertical tritium transfer to the well depends on the depth of wells