Natural radiation exposure from the reinforced cement concrete building materials used in the Northern districts of Manipur, India

Natural radioactivity is commonly found in building materials, and an understanding of its associated radiological risks is important as people spend maximum time indoors. This study aims to evaluate the natural radiation exposure from natural radionuclides in the reinforced cement concrete (RCC) building materials used in the northern districts of Manipur, India. Reinforced cement concrete (RCC) building materials used in the study area were collected and assessed for radioactive elements using a NaI (Tl) scintillation detector-based gamma spectrometer. The observed mean concentrations of radioactivity in the RCC building materials are as follows: for 226 Ra, it is 36 Bqkg −1 (ranging from 29 Bk kg −1 in concrete to 49 Bqkg −1 in sand); for 232 Th, it is 85 Bqkg −1 (ranging from 31 Bqkg −1 in cement to 134 Bqkg −1 in sand); and for 40 K, it is 1242 Bqkg −1 (ranging from 494 Bqkg −1 in concrete to 1731 Bqkg −1 in sand). The absorbed dose rates due to radioactive elements in common building materials range from 130 nGyh−1 to 331 nGyh −1 , with a mean value of 226 nGyh −1 , which is significantly higher than the world average of 84 nGyh −1 . The annual effective dose derived from these building materials has a mean value of 1.1 mSvy −1 (ranging from 0.6 to 1.6 mSvy −1 ). The gamma index averages 1.0, with a range of 0.6 - 1.4.