Modelling the Exposure of Residents of a Radium-Contaminated Living Place.

Within the framework of the Swiss Radium Action Plan 2015-22, which aims to investigate and remediate sites contaminated by the radium used in the Swiss watch industry, a reference level of 1 mSv per y has been defined for the exposure of residents. An additional protection objective has been set for soil contamination, which should not exceed the value of 1000 Bq per kg 226Ra. Based on measurements on the study sites, the doses received by residents were calculated accordingly to the methodology, in both indoor and outdoor areas, taking into account external exposure and ingestion. The site diagnosis approach consists of a screening procedure based on a rapid measurement, followed, if necessary, by additional analysis to estimate doses. Sites where modelling indicates that the reference level or the complementary protection objective for soil contamination have been exceeded are subject to remediation. The application of the methodology based on these radiological criteria to 752 sites diagnosed until December 2020 indicates a rate of sites (buildings and outdoor areas) requiring remediation of ~16%. The annual doses to residents calculated by modelling are between 1 and 20 mSv per y for these sites.