Assessment of Radiological Hazards of Sedimentary, Igneous and Sediments Natural Rocks

Gamma-ray spectroscopy based on a 100% efficiency hyper-pure germanium detector was used to evaluate the activity concentrations of 226Ra, 232Th, and 40K natural radionuclides in sedimentary, conglomerate, igneous and sedi-ments rock samples collected from four different locations in Eastern desert in Egypt. The obtained activity concentrations are used to evaluate the radi-ological hazards indices, absorbed dose rate, annual effective dose equivalent in air, radium equivalent, external and internal hazard index, radiation level index, annual gonadal dose equivalent, excess lifetime cancer risk and expo-sure rate. The results show that 1) the absorbed dose rate depends on the rock type, 2) the annual effective dose equivalent in air in 71% of sample below 20 mSvy-1 (permissible limit for workers), 3) the conglomerate rocks show low radioactivity level, 4) sedimentary rocks are rich in radium while igneous rocks are rich in thorium and the sediments rocks are rich in both radium and thorium.

Assessment of Background Radiation and Associated Dose Rates in Soil Samples from Norochcholai in the North Western Coast of Sri Lanka

This study assesses radiation levels in soil, water and air in the Norochcholai, an area in Sri Lanka closest to the Kundankulam nuclear power plant, India which is situated in the North Western coast. This is important for monitoring radiation hazards and will be useful in case of a nuclear accident. Superficial soil and water samples from 23 locations were analyzed by Gamma spectrometry using HPGe detector. The activity concentrations of Th232, K40, Ra226 and Pb210 in the soil were 56.0 Bq·kg-1, 96.0 Bq·kg-1, 24.0 Bq·kg-1 and 27.0 Bq·kg-1 respectively. Dose rate at 1 m height was recorded using a survey meter (Automess 6150AD). Median dose rate was 0.098 μSv·h-1. The median gamma ray absorbed dose rate was 51.2 nGy·h-1, which is lower than the global average of 57 nGy·h-1. Radium equivalent activity (Raeq) ranged from 30.3 Bq/Kg - 458.3 Bq/Kg and only one sample recorded the Raeq > 370 Bq/Kg as safe to be used in building materials. External hazardous indices of all the samples were below 1 and the mean annual effective dose was within the safe limit of 1 mSv/y. The health risk of exposure to terrestrial radiation from the soil in the area is minimal. These data could be used as baseline for radiation assessment.