Assessment of environmental ra-226, th-232 and k-40 concentrations in the region of elevated radiation background in Segamat District, Johor, Malaysia

Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276nGyh-1 and 1.169mSvy-1, respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of 232Th, 226Ra and 40K. The results of the gamma spectrometry range from 11±1 to 1210±41Bqkg-1 for 232Th, 12±1 to 968±27Bqkg-1 for 226Ra, and 12±2 to 2450±86Bqkg-1 for 40K. Gross alpha and gross beta activity concentrations range from 170±50 to 4360±170Bqkg-1 and 70±20 to 4690±90Bqkg-1, respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000