Determination of natural radioactivity in building materials used in the Rawalpindi/Islamabad area by gamma-ray spectrometry and instrumental neutronactivation analysis

Samples of sand and manufactured building materials collected from the Rawa lpindi/Islamabad area have been analyzed for the primordial natural radionu clides U-238, Th-232 and K-40 using gamma-ray spectrometry. The uranium and thorium contents have also been determined by instrumental neutron activat ion analysis (INAA). The specific activities of these radionuclides in the samples are compared with those of the world averages for soil. The compari son shows that, of the nine samples analyzed, only the three brick samples have higher activities than the world averages for soil. The specific activ ities in these materials, having a radium equivalent activity of less than 370 Bq kg(-1), when evaluated for radiological effects show that all materi als meet the external gamma-ray dose limitation of 1.5 mSv y(-1). The gamma -spectrometric and INAA techniques complemented each other well in this stu dy. (C) 1999 Elsevier Science Ltd. All rights reserved.