Cs-137 concentration in the environment of Kaiga of south west coast of India

This paper presents the results of Cs-137 activity in soil and vegetation o btained through a carefully planned pre-operational survey for the establis hment of baseline data on background radiation level and distribution of ra dionuclides in the environment of Kaiga, in the south west coast of India, where two nuclear power reactors of 235 MWe each are under construction, Th e vertical profile in soil and the seasonal variation in the activity have been studied. Nine commonly available vegetation species of Kaiga region we re analyzed for their Cs-137 activity, and the soil-to-plant transfer coeff icients were evaluated. Measurements were made by gamma spectrometry method employing a 90 cc HpGe detector and a 3 x 3-inch well type NaI(TI) detecto r. Results show significant levels of Cs-137 activity in soil samples - ran ging from below detection limit (BDL) to 65.4 Bq kg(-1). The mean value of activity observed in 0-5 cm soil profiles of Kaiga environs is significantl y higher when compared to the reported values for other environs of India, Depth profile studies show that the Cs-137 activity decreases with the incr easing soil depth, and it is below detection limit for depths more than 25 cm, The mean value of effective dose commitment due to the presence of Cs-1 37 in soil was 167.2 mu Sv. Vegetation samples of the region show elevated Levels of Cs-137 concentration. Epiphytic plants Cymbidium aloifolium (Lo.) Swartz, and Petrobryopsis tumida (Hook,) I)ix. have been identified as bio -indicators to monitor the fallout of this radionuclide in the environment of Kaiga, Seasonal variation studies indicate higher fallout of this radion uclide along with rain.