Assessment of Natural Radioactivity and Radiological Hazards in Brick Samples Used in Tiruvannamalali District, Tamilnadu, India, With a Statistical Approach.

The activity concentration of Ra, Th and K in brick samples used in Tiruvannamalai District of Tamilnadu has been determined using gamma ray spectrometry. The activity concentration ranges from BDL to 16.02 Bq kg, 17.86 to 120.19 Bq kg, 240.09 to 481.35 Bq kg for Ra, Th, and K, respectively. The concentration of these radionuclides is compared with reported data from other countries. The radium equivalent activity (Raeq), absorbed gamma dose rate (DR), annual effective dose rate (HR), annual gonadal dose equivalent (AGDE), criteria formula (CF), representative level index (RLI), activity utilization index (AUI), gamma index (Iγ), alpha index (Iα), the external hazard (Hex), and internal hazard (Hin) indices are calculated for the measured samples to assess the radiation hazards due to the use of these materials in the construction of dwellings. Multivariate statistical techniques (Pearson correlation, principal component analysis and cluster analysis) are used to study the relation between radionuclides and radiation hazards. The treatment of 14 radioactive variables sampled at 32 bricks by the factor and cluster analyses provided a possible interpretation of the collective data. The spatial distribution pattern of radionuclides has been depicted through the Kriging method using MapInfo software.

Multivariate statistical analysis of radiological data of building materials used in Tiruvannamalai, Tamilnadu, India.

Using γ spectrometry, the concentration of the naturally occurring radionuclides (226)Ra, (232)Th and (40)K has been measured in soil, sand, cement, clay and bricks, which are used as building materials in Tiruvannamalai, Tamilnadu, India. The radium equivalent activity (Raeq), the criterion formula (CF), indoor gamma absorbed dose rate (DR), annual effective dose (HR), activity utilization index (AUI), alpha index (Iα), gamma index (Iγ), external radiation hazard index (Hex), internal radiation hazard index (Hin), representative level index (RLI), excess lifetime cancer risk (ELCR) and annual gonadal dose equivalent (AGDE) associated with the natural radionuclides are calculated to assess the radiation hazard of the natural radioactivity in the building materials. From the analysis, it is found that these materials used for the construction of dwellings are safe for the inhabitants. The radiological data were processed using multivariate statistical methods to determine the similarities and correlation among the various samples. The frequency distributions for all radionuclides were analyzed. The data set consisted of 15 measured variables. The Pearson correlation coefficient reveals that the (226)Ra distribution in building materials is controlled by the variation of the (40)K concentration. Principal component analysis (PCA) yields a two-component representation of the acquired data from the building materials in Tiruvannamalai, wherein 94.9% of the total variance is explained. The resulting dendrogram of hierarchical cluster analysis (HCA) classified the 30 building materials into four major groups using 15 variables.