Assessments of boundary conditions and requirements for Rare Earth Underground Mining due to presence of NORMs

Rare earths contain NORMs, such as uranium, thorium and their progeny, like radium and radon. The varying concentrations of NORMs are quite often significant enough to result in occupational and environmental radiation exposures during the mining, milling and processing procedures of rare earths and compounds. Ventilation is the primary technique of controlling ambient concentrations of radon. Fresh air volume flow rates, the distribution of airflow within the mine and the radon emanation rate are primary factors affecting such concentrations. In this paper, it is attempted to determine the factors that may result in radiation risks and evaluate the boundary conditions that will contribute to the restriction or even elimination of radon progeny, with a goal to use the evaluations in order to build an overall assessment tool.