Radioactive contamination of the Shagan river: results of the study-2011

Authors present the study aimed at the research into tritium distribution in the Shagan river from the Atomic Lake down the river and, second, the identification of possible sources of the river contamination with strontium-90. From 2005 abnormally high level of tritium and significant concentration of strontium-90 in the river were documented annually. That was the reason for analysis of 3H and 90Sr concentration in the surface water of the river and identification of the main sources of contamination with 90Sr. The field study was carried out in August, 2011. Concentration of radionuclides was estimated in samples taken from the surface of the river in 6 points located from its inflow to the Atomic Lake external water reservoir down the river till its inflow to Irtysh. Results of study show that concentration of 90Sr was below the lower level of detection by the available instrument. It means that the Atomic Lake is not a main contributor to the contamination of the Shagan river with 90Sr. Significant change of 90Sr concentration may result from changes in hydrologic regime in the river stream. Analysis of 3H concentration in the Shagan river from the Atomic Lake down the river flow to Irtysh showed its variability. The highest level of the radionuclide in the river, 200 kBq/kg, was in spring, at the same time it was 50 Bq/kg in the place of confluence of Shagan and Irtysh rivers. Comparison of previous data on tritium concentration in the river and data of the present study gives the evidence that location of high tritium contamination was variable.