This study presents the results of outdoor ambient gamma and gross alpha activity of Sirumalai, Dindigul district, Tamil Nadu, and these measurements were carried out by using environmental radiation Scintillation Counter (UR-705). Results showed that the terrestrial Gamma radiation levels of the Sirumalai was ranged from 4.33±0.47µR/h to 12.67±0.47µR/h. The Gross alpha radioactivity levels of the Sirumalai ranged between 8.25Bq/kg and 26.56 Bq/kg. The calculated ambient gamma and gross alpha activity were found to be lesser than the world average. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 37.671nGy/h and 110.23nGy/h. This value is slightly higher than the population weighted world-averaged of 60 nGy/h. Inhabitants of Sirumalai are subjected to external gamma Annual dose exposure ranging between 0.0462mGy/y and 0.1352mGy/y. The result reveals the non-uniform distribution of Gamma radiation and an irregular distribution of radiation profile was observed during the survey period. The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels.

Sirumalai hills, Gross alpha, terrestrial gamma radiation

The present study investigates on the ambient gamma survey of Sirumalai sediment samples and the resulting radiation dose from ambient gamma radionuclides. In addition to that, the estimation of the absorbed gamma dose rate, and the annual effective dose rate were also studied. The data presented in this study will serve as a baseline survey for naturally occurring radionuclides concentration and radiation exposure in Sirumalai. The ambient gamma values ranged from 4.33±0.47 to 12.67±0.47µR/h, ambient gamma absorbed dose rate (37.67-110.23Gy/h) and ambient gamma annual effective dose rate (0.046-0.135mSv/y) in the Panrimalai area measured from radiation survey meter was found to be lower when compared to the worldwide average value of 0.42 mSv/y. From the present study, it was concluded that the non-uniform distribution of ambient gamma, absorbed dose rate, and annual effective dose rate in the soil samples of Sirumalai was found to be less than that of the recommended safe levels.

M. Mohamed Thasneem and R. Krishnamoorthy (2022). A Study on the Level of Terrestrial Gamma and Gross Alpha Activity in Sirumalai, Dindigul District, Tamil Nadu. Biological Forum – An International Journal, 14(4a): 600-604.