Radiation doses due to the natural radioactivity in Pakistan marble

Abstract

In view of its high potential for containing large amounts of radioactive materials and due to its wide-spread use as construction and facing material worldwide, radiation doses received from the marble used in dwellings have been determined. As a first step, specific activity measurements were made using a NaI(Tl) gamma ray spectrometer using the spectrum stripping technique. For the samples studied, the average values of specific activities for ²²⁶Ra, ²³²Th and ⁴⁰K have been found to be 27, 26 and 58 Bg kg^-1 respectively. The mesh-adaptive, volume-integral method based code INGRE (Mirza et al., 1991) gave calculated values of the dose equivalent rates inside the standard room (Tufail et al., 1994) due to ²²⁶Ra, ²³²Th and ⁴⁰K; these we re found to lie between 5-77, 12-52 and 1-11 nGy h^-1 respectively. The values of whole-body dose equivalent rates have been found to lie in the 27-108 nGy h^-1 range. As these values are below internationally accepted maximum permissible values, therefore marble available in Pakistan can safelybe used in dwellings as a construction material.