The first use of 236U in the general environment and near a shutdown nuclear power plant

We present a first effort to investigate 236U in the environment near a shutdown nuclear power plant far away from highly contaminated sites, by using accelerator mass spectrometry. The detection limit of about 1 pg 236U allowed us to identify a minimal increase of the 236U/238U isotopic ratio correlated to a peak of 137Cs in river sediments downstream of the nuclear power plant, and to detect anthropogenic 236U also upstream, where it is probably not related to the power plant but to global fallout. The 236U content shoved variations of the 236U/238U isotopic ratio in relation to the chemical–physical characteristics of the sediments. This demonstrates the potential of 236U as an environmental tracer, and as an indicator for releases from nuclear facilities.