Spatially resolved isotope analysis of a Chernobyl corium fragment extracted from environmental soil

Abstract

Micrometer sized particles accounted for a considerable fraction of the radioactivity released into the environment during the Chernobyl accident. In addition, there is a special kind of particles, so called shelter-derived fuel containing material (FCM), that formed as a consequence of the cooling of the reactor melt, and was so far only found inside the reactor building. For the first time, a FCM particle was located in and extracted from soil of a former agricultural field 5 km south-southeast of the former nuclear power plant. Using a combination of energy scanning electron microcopy and dispersive x-ray analysis and Secondary Neutral Mass Spectrometry we found that the particle is comprised of a silicon matrix containing evenly distributed amounts of U, Pu and Am. Embedded in that chemically stable matrix are small inclusions of reactor U of varying chemical composition. We could show this particle type to be largely unaffected by weathering under environmental conditions.