Predictive Radiological Background Distributions from Geologic Data

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Aerial radiological surveys have a decades-long history of use in prospecting, consequence management, and search applications. Recent experience during the Fukushima nuclear power plant accident exposed the need for better knowledge of the normal radiological landscape before a radioactive release occurs, and modern search algorithms are increasingly making use of a priori data to estimate anticipated background radiation distributions. This project is using available information in the form of existing geochemical data, geologic maps, remote sensing data, and sparse radiological data to create high-resolution maps of estimated background radiation levels. In FY 2014, we developed a successful method for creating high spatial resolution background predictions by extrapolating low spatial resolution background radiation data using radiological background units that we defined based on geologic information. In FY 2015 we will continue to investigate the best method to construct a background model using potassium, uranium, and thorium contents of bedrock and soils measured by standard geochemical techniques, combined with chemical weathering and photon transport models.