Abstract
The use of the method of nonequilibrium uranium in various branches of science led to the necessity to determine its isotopic composition. The content of uranium isotopes in natural waters is often extremely low, therefore, it is necessary to collect significant volumes of samples in order to obtain reliable results of analysis. In this paper, it is proposed to concentrate uranium isotopes from water in-situ. Two alternative methods of uranium coprecipitation in field conditions (on activated carbon and iron (III) hydroxide) are considered. The desorbed uranium isotopes are determined by an alpha-spectrometric method with preliminary radiochemical preparation in laboratory conditions, including extraction with tributyl phosphate and electrodeposition on a steel disc. It was found that when concentrating on activated carbon the chemical yield was from 2 to 32%, and when concentrating on iron (III) hydroxide it is from 15 to 62%. For the second case, the chemical yield is acceptable for radiochemical work, and the proposed method for concentrating of uranium isotopes is recommended for usage in field conditions. Approbation of the method was carried out within the framework of the PEER454 project in 2017 in the valley of the river Ziddy, Pamir-Alay, Republic of Tajikistan. Work in the field conditions showed high efficiency of the method and its full feasibility even in the absence of acceptable laboratory conditions.