Population exposure by thoron decay products in multi-story buildings on example of large cities in Russia

The aim of the research is to develop a new method for estimation of the annual effective dose of thoron decay products for the population living in multi-story buildings. Preliminary measurements of the annual average thoron equilibrium equivalent concentration were performed in Ekaterinburg city considering the uncertainties of the developed method. The results were extrapolated to nine Russian cities using a non-destructive gamma-spectrometry technique, along with thoron equilibrium equivalent concentration estimations. Assessed annual average effective dose from thoron decay products was 0.32 mSv year^–1 and ranged from 0.12 to 0.63 mSv year^–1 depending on the city.