Natural radioactivity in clay bricks and cements used in Albania.

This study has the aim to determine the radioactivity content of clay bricks and cements used as building materials in Albania in order to characterize their potential radiological hazard to humans. Up to 60 samples are investigated in order to measure the natural activity concentrations of 226Ra (238U), 232Th and 40K. The measurements were carried out using a fully automated high-resolution gamma-ray spectrometry using two coupled HPGe detectors (MCA_Rad system). The results indicate that the activity concentration in clay bricks ranges between 490.6 ± 19.4 Bq/kg to 820.3 ± 27.0 Bq/kg for 40K, between 25.8 ± 1.4 Bq/kg to 51.9 ± 1.7 Bq/kg for 226Ra and between 29.2 ± 1.9 Bq/kg to 55.1 ± 2.5 Bq/kg for 232Th. While for cement the radioactivity content range between 107.3 ± 6.2 Bq/kg to 250.8 ± 10.6 Bq/kg for 40K, between 40.9 ± 1.2 Bq/kg to 61.4 ± 1.6 Bq/kg for 226Ra and between 11.5 ± 1.0 Bq/kg to 22.9 ± 1.3 Bq/kg for 232Th. The radiological hazards due to the natural radioactivity in the samples were inferred by calculation of the activity concentration index (ACI). The corresponds activity concentration index range between 0.48 ± 0.02 to 0.63 ± 0.04 for clay bricks and 0.29 ± 0.03 to 0.37 ± 0.02 for cements. These values correspond to an annual effective dose rate lower than 1mSv/y. Indeed due to the final utilization of clay bricks and cements in the dwelling the annual effective dose rate was calculated to range between 0.28 ± 0.02 mSv/y to 0.45 ± 0.04 mSv/y and 0.08 ± 0.04 mSv/y to 0.17 ± 0.02 mSv/y respectively. Therefore, these materials are classified as A1 category (according to European Commission recommendations), i.e. materials used as bulk material without restriction.