SOIL RADIOACTIVITY MEASUREMENTS AND ESTIMATION OF RADON/THORON EXHALATION RATE IN SOIL SAMPLES FROM KALPAKKAM RESIDENTIAL COMPLEX

The objective of this study is to compute the primordial radionuclides activity in soil samples and estimate the radon/thoron exhalation rates. A total of 25 locations were chosen for the study at Kalpakkam. Ambient radiation levels were monitored prior to collection of samples, which were subjected to gamma spectrometry. While U-238 concentration was found to be below detectable limit, the activities of Th-232 and K-40 were varying from 34.53 to 1093.11 Bq kg(-1) and 36.6 to 570.08 Bq kg(-1), respectively. The radium equivalent activities (Ra-eq) were in the range of 83-1574 Bq kg(-1). There was no appreciable radon exhalation, and the thoron surface exhalation rate varied from 942 to 7720 Bq m(-2) h(-1). The annual effective dose was ranging from 0.05 to 0.81 mSv y(-1). Good correlation was observed between Th-232 content and thoron exhalation rate. The details of the study are presented in this article.