High-Activity Microscopic Nuclear-Sourced Particles to Investigate Nuclear Release Scenarios - 18026

Advances in microscopy and materials analysis have allowed for the study of materials at resolutions not previously attainable a decade ago. Such information extends to not only their existence, but also their composition, the likely source term and if applicable, their short or long-term environmental stability. This work describes the analysis undertaken on the larger 'ejecta' type of particulate collected following the INES Level 7 incident at the Fukushima Daiichi Nuclear Power Plant in March 2011. However, the methods and procedures employed during this work, on material with enormously contrasting characteristics, have far wider applications within nuclear forensics, safeguards, security and material compliance. Resulting from the analysis of micron-scale 'atmospheric' material in previous works have been able to derive information relating to the emission and subsequent transportation characteristics of the release event, as well as determining the local-scale impacts of this radioactive fallout. This analysis of the larger-scale (100's of micron) 'ejecta' material, collected from closer to the plant, has been able to reveal details pertaining to the specific in-reactor conditions at the time of the release as well as the nature of the explosion events. (authors)