An activity concentration-based proposal for radon management in workplaces involving NORM in Canada

The Canadian Guidelines for the Management of Naturally Occurring Radioactive Materials (NORM) have been developed to manage radiation doses received in workplaces involving NORM, such as mineral extraction and processing, oil and gas production, metal recycling or water treatment facilities. This management strategy works well for most naturally occurring radioactive materials in workplaces, with the exception of radon. Radon is a naturally occurring radioactive gas generated by the decay of uranium-bearing minerals in rocks and soils. Because radon exists everywhere in varying concentrations, it is not feasible to use incremental radon generated or enhanced by a practice as a means for assessing the need for radon management programs. Drawing from lessons learned through implementing the current NORM Guidelines, we propose decoupling the decision thresholds for NORM management (excluding radon) and radon management so that the two are considered separately, and quantifying decision-points for managing occupational radon exposure as average annual activity concentrations, with no requirement for dose calculations. Proposed application of this approach in the updated Canadian NORM Guidelines is described.