Assessment of natural radioactivity levels in building materials and evaluation of indoor radiation exposure

摘要

Building materials used is some cement houses in Greater Bombay and nearby areas were analysed gamma speotrometrically using a bulk material gamma counter, having 20 cm (dia) x 10 cm (thickness) NaI (T1) detector. Radium#x2010;226 was determined through Bi#x2010;214 (1.76 MeV) and Thorium#x2010;232 through T1#x2013;208 (2.61 MeV) while Potassium#x2010;40 by its 1.46 MeV gamma photons. Average Ra#x2010;226 content in cement was found to be the highest (60.4 Bq, Kg#x2010;1) and that in granite the lowest (10.7 Bq. Kg#x2010;1). Ra#x2010;226 gives #x2018;Q#x2019; the Radon#x2010;222 emanation rate from which Rn#x2010;222 concentration is calculated. From Rn#x2010;222, indoor internal exposure in mWLM Y#x2010;1and from Bi, T1 and K indoor air dose in urad h#x2010;1inside a model room that can be built from such materials has been computed. It is 3.9 urad h#x2010;1(0.04 uGy h#x2010;1) and is comparable with values obtained by actual measurements in other countries (1).