Testing the method of Cs-137 determination in natural waters

A method of determining Cs-137 in natural waters was tested. The method is based on sorption concentrating of cesium by using ferrocyanide sorbent NPF-HTD with the detection limit of 0.0003 Bq L⁻¹ when the concentrate was measured with a scintillation gamma-spectrometer, and that of 0.0001 Bq L⁻¹ when a semiconductor gamma-spectrometer was used. Activity concentrations of Cs-137 were determined in 18 natural water samples taken in the areas affected by activities of nuclear fuel cycle enterprises and contaminated by radiation accidents, 8 samples from RW storage site, and 3 samples from RW subsurface final disposal site. The effects of natural water macro-components on the chemical yield of cesium into the NPF-HTD concentrate were studied. It is shown that the method can be used to determine Cs-137 in waters of any composition and hardness. The cesium chemical yield into the concentrate for all the samples was 98–99%. Cs-137 activity concentrations were less than the allowed limit of 11 Bq L⁻¹ for drinking water in all the samples, and were not higher than the control level in the waters from the monitoring wells.