Natural radionuclides and assessment of radiological hazards in different geological formations in Khammouan province, Laos

The 226 Ra, 232 Th ( 228 Ra), 40 K activity concentrations in soil distributed in 67 points belonging to different geological formations in Khammouan, Laos were measured using HPGe detector. The results showed that the activity concentration varies from (6.0 ± 0.61) Bq/kg to (68.5 ± 8.0) Bq/kg, (8.7 ± 1.0) Bq/kg to (78.9 ± 8.3) Bq/kg, (32.1 ± 3.1) Bq/kg to (812 ± 63) Bq/kg with the mean values of (32.2 ± 1.7) Bq/kg, (41.6 ± 2.2) Bq/kg, (279 ± 24) Bq/kg for 226 Ra, 232 Th ( 228 Ra), 40 K respectively. The highest and lowest average activities were found at cPz2 (Middle Paleozoic) and Mz1 (Lower Mesozoic) formations respectively. With regard to radiation hazards, the 232 Th ( 228 Ra) concentration has a major contribution to the Ra eq . In general, in the study area, the activity concentration of natural radionuclides has an insignificant effect on human health.