Discharges of dust from NORM facilities: Key parameters to assess effective doses for public exposure

In transposing Directive 2013/59/Euratom (European Basic Safety Standards or EU BSS) into national law, it was necessary to identify industrial sectors which involve naturally occurring radioactive materials (NORM) which may lead to public exposure that cannot be disregarded from a radiation protection point of view. A research project was implemented that resulted in a comprehensive survey of all potentially relevant industrial sectors operating in Germany. Major efforts were made to determine source terms of airborne discharges, atmospheric dispersion models, and dose calculations.The study arrived at the conclusion that the discharge and the settlement of dust in agricultural and horticultural areas is the most relevant dispersion and exposure pathway, while discharges of radon are of minor importance.The original study used a number of rather complex models that may distract from the fact that very few key parameters and assumptions determine the effective dose of members of the public. This paper revisits the study and identifies those parameters and assumptions and provides a simplified, generic, yet sufficiently reliable and robust assessment methodology to determine the radiological relevance of dust discharges from NORM industries under the typical geographical and meteorological conditions of Germany.This paper provides examples of dose estimates for members of the public for selected industries operating in Germany. Due to its simplicity and robustness, the methodology can also be used to assess effective doses resulting from discharges in other industries in Germany, and it can be adapted to conditions in other countries in a straightforward way. Keywords: NORM, Dust discharge, Public exposure, High temperature processes, Atmospheric dispersion mode

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