Abstract
Surface waters of Shagan river are one of the major sources of radiation hazard on the Semipalatinsk test site (STS). The chemical composition, mineralization, and microelement content of the Shagan river waters were determined along with the radionuclide content within the discharge zone with the aim to reveal relationships in the present-day supply of tritium-contaminated underground waters into the Shagan river (a tribute of the Irtysh river). Processing of the data obtained revealed the main zone of discharge of tritiumcontaining underground waters. The tritium distribution along the Shagan river and in the Irtysh river was studied.