RADIOACTIVITY CONCENTRATIONS OF SOILS FROM THE VICINITY OF LYNAS PLANT AT GEBENG, KUANTAN AND ITS POTENTIAL RADIATION RISK
Natural radioactivity in the surface soil from the vicinity of Lynas Rare-earth plant in Kuantan, Pahang had been studied with aim of evaluating environmental radioacitivity of that area. The radioactivities of the samples have been measured using a low-background HPGe gamma detector. The concentration of 226Ra ranged found to be between 8.7 – 76.9 Bq/kg (mean 33.7 Bq/kg); activity of 238U from 8.7 to 80.5 Bq/kg (mean 36.9 Bq/kg); as for 232Th, it ranged from 6.2 to 121.5 Bq/kg (mean 58.2 Bq/kg) and that of 40K, the values was from 19.1 to 778.9 Bq/kg (mean of 221.3 Bq/kg). Activity standard deviation for 226Ra, 238U, 232Th and 40K were 14.2 Bq/kg, 14.7 Bq/kg, 26.1 Bq/kg and 185.6 Bq/kg, respectively. To evaluate the risk of radiation hazard to human, several parameters, i.e. the radium equivalent activity, External hazard index, Representative level index and dose rate in air from the terrestrial natural gamma radiation were calculated with the mean values found to be 136.7 Bq/kg, 0.4, 1.0, 65 nGy/h, respectively. The data were discussed and compared with those obtained from the previous studies given in the literatures. This study found that the mean dose equivalent received by an individual at the vicinity area (outdoor) of Lynas plant was estimated to be 82.0 mSv/yr, which is far below the annual dose limit of 1,000 mSv/yr for general public as stipulated in the national act.