AMS measurement of environmental U-236. Preliminary results and perspectives

236U is a 23.4 Ma half-life radioactive isotope whose natural global abundance is expected to be overwhelmed in many places by its production and release during nuclear power generation. The detection of excess 236U in the environment is therefore a method of monitoring the presence of activated uranium. However, 236U has not been widely used for environmental studies due to the difficulties of measuring it at low levels with standard α-spectrometry or thermal ionization mass spectrometry. In principle, accelerator mass spectrometry can overcome some of the difficulties encountered in the traditional methods, making it possible to detect 236U at very low levels so that a large range of environmental samples can be analyzed. In this paper, we report some preliminary results of the 236U measurements of four water samples from the US Idaho Chemical Processing Plant. Limitations with our current AMS system and the perspectives for considerable improvements will be discussed. (orig.)