Natural radioactivity measurement in spring waters by the use of SARAD U/Ra-disc method

Full text: High costs and the duration of the conventional radiochemical preparation methods for analysis of radium and uranium are the elements that considerably limit the number of samples that can be analysed. SARAD GmbH group developed U/Ra-disc method that is highly competitive in comparison with standard radiochemical methods (H. Surbeck, 7th Int. Symp. on Environmental Radiochemical Analysis, UK, 1994). The new procedure is based on the selective absorption of uranium and radium at thin, chemically activated layers. These layers are carried by small discs made of Polyamide. The thin films absorb uranium and radium from aqueous solutions, for example from drinking water. The discs are simply immersed into the solution to be measured to absorb and accumulate radionuclides with high efficiency. The alpha spectrum of a water sample with the nuclides of the uranium decay chain can be analysed using a conventional alpha spectrometer. The purpose of the project is to test the U/Ra-disc method developed by SARAD on several natural water samples. In order to get quantitative results the whole system has to be previously calibrated with respect to the sample volume, the exposition time, temperature and pH of water sample, the detector geometry and the alpha analysis time. The analysis time should be chosen in accordance to the expected nuclide concentration of the sample and the maximum allowable statistical error. The whole project is carried out at the Laboratory of Low Activities, Institute of Physics, University of Silesia, Katowice, Poland. (author)