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

Samples of sand and manufactured building materials collected from the Rawalpindi/Islamabad area have been analyzed for the primordial natural radionuclides 238U, 232Th and 40K using gamma-ray spectrometry. The uranium and thorium contents have also been determined by instrumental neutron activation analysis (INAA). The specific activities of these radionuclides in the samples are compared with those of the world averages for soil. The comparison shows that, of the nine samples analyzed, only the three brick samples have higher activities than the world averages for soil. The specific activities in these materials, having a radium equivalent activity of less than 370 Bq kg-1, when evaluated for radiological effects show that all materials 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 study.