NORM-related industrial activities in Estonia – Establishing national NORM inventory

摘要

There is incomplete information available concerning NORM-related (naturally occurring radioactive material) industries in Estonia. In order to fill the gap in this knowledge, a nationwide study was carried out between 2015 and 2017 to determine and radiologically characterize potential NORM-related industries. The study included compiling available literature and studies as well as on-site measurements (external dose rate and radon) and samplings in multiple industries, which had been determined to be potential NORM creators. The results from this study concluded that there are 3 industries in Estonia where the activity concentrations of naturally occurring radionuclides can reach an increased level which may require further regulatory control. Radionuclide exemption values were clearly exceeded in the filter materials of drinking water treatment plants that use water from Cambrian-Vendian aquifer.226Ra and228Ra values in filter materials reached over 40 kBq kg?1. Additionally, the gross radionuclide activity concentrations of238U and232Th in waste from a rare metal production industry reached up to 191 kBq kg?1. Clinker dust from the cement industry showed elevated concentrations of210Pb, rising to over 2 kBq kg?1in fine clinker dust.The creation of a national NORM inventory can be the basis for establishing a national NORM strategy for the management of NORM residues. This work provides a thorough overview of the radiological parameters of the potential NORM-related industries, describes the radionuclides that have elevated concentrations, provides estimations on their yearly creation amounts and produces input for determining possible NORM management options.