Analysis of the characteristics of hot particles related to environmental fate and interaction with living organisms

The radiological residues at the former British weapons testing sites at Maralinga, Emu and the Monte Bello Islands often occur in particulate form (so called hot particles). Large numbers of these particles were emitted from nuclear and non-nuclear tests. For example each square meter in a plume that extends for tens of kilometres at the Taranaki site (Maralinga) can contain more than 3000 readily identifiable particles. The physical and chemical characteristics of these particles affect their mobility and availability for uptake into living organisms. When they contain long-lived radionuclides (e.g. 239Pu) these particles may slowly weather, and thus provide a persistent source of ionic forms, or smaller particles, for many thousands of years.

Here we present a status on a range of methods being used at ANSTO to evaluate the physical and chemical characteristics of particles gathered from Australian sites. Methods include gamma spectrometry, autoradiography, high sensitivity Accelerator Mass Spectrometry analysis (AMS), leaching studies, and synchrotron-based X-ray fluorescence microscopy/spectroscopy. We focus on some of the practical issues involved when gathering and working with hot particles, as well as challenges in determining speciation and its influence on radioecological outcomes. We discuss data gaps and recommendations for current and future use of analysis methods in radioecological studies in Australia and the wider international community.