Investigation of natural radionuclide and associated radiological parameters of selected construction materials used...

The present study investigated the natural radioactivity levels of $_{}^{226}$ Ra, $_{}^{232}$ Th, and $_{}^{40}$ K in various construction and building materials commonly used in Central Nepal, expressed in Bq kg $_{}^{-1}$ , and analyzed the associated 13 radiological parameters for the evaluation of risks. Activity concentrations were determined using a thallium-activated sodium iodide crystal NaI(Tl) 3" $\times$ 3" scintillator detector. Multivariate statistical analysis was used to discern trends and depict the data. Among the material studied, granites, sand, and bricks exhibited concentrations and associated radiological parameters that exceeded world average. However, remaining aggregate, cement, concrete bricks, marble, and tiles showed activity concentrations and hazard indices comparable to or lower than the global average value reported by UNSCEAR, 1993 for building materials. The overall revealed mean ± S.D. concentration of $_{}^{226}$ Ra, $_{}^{232}$ Th and $_{}^{40}$ K across 41 different materials as 43.2 ± 1.0 Bq kg $_{}^{-1}$ , 56.8 ± 1.4 Bq kg $_{}^{-1}$ , and 281.1 ± 5.3 Bq kg $_{}^{-1}$ , respectively. The average values $_{}^{226}$ Ra, $_{}^{232}$ Th were above the world population average values of 50 and 50 Bq kg $_{}^{-1}$ whereas the concentration of $_{}^{40}$ K was well below the average value 500 Bq kg $_{}^{-1}$ respectively. From this, it is concluded that the studied samples are safe to use. However, regulations are needed to evaluate the natural activity concentrations of radionuclides in geologically derived samples and the associated health implications related to materials utilized from the internal resources of the country and imported materials from a different country.