Gamma-radiation exposure by natural radionuclides in residential building materials on example of nine Russian cities

The objective of the study was to estimate the effective dose rates of external population exposure based on measurements of average specific activity of natural radionuclides ( 226 Ra, 232 Th and 40 K) in building materials of existing buildings. The measurements were performed using new developed non-destructive technique in 100 apartments in 9 Russian cities. The effective dose rate is 34 nSv h –1 in average and varies from 10 to 102 nSv h –1 between cities. Specific factors of conversion from specific activity to effective dose rate were obtained taking into account the real room geometries.