The Measurements of Radon Concentration and Thoron to Radon Ratio in Soil Gas in the Environs of Al-Kufa City-Iraq

Soil gas Radon ( ) and Thoron ( ) concentrations were measured at 20 locations in the Kufa city (Iraq), using RAD7 radon monitoring system of Durridge company USA. In each location four different depths were taken for soil gas measurements, starting from 5cm below the ground surface. Important differences in the radon and thoron concentrations were found between stations, with average values comprised. The results suggested that the largest radon concentration was 9200±407 Bq/m3 for 60cm depth at in Al-Saray, point sample P9, district and the smallest concentration was 8.79±18 Bq/m3 for 5cm depth at Al-Jameaa, point sample P19 district. The measurement shows that thoron can interfere in certain flow-through radon monitors, by causing an addition signal. The maximum thoron concentration was 98.25±35 in sample P9, Al-Saray district and minimum level was 1.6±3.0 Bq/m3. Results obtained from this study indicate that the region has background radioactivity levels within the natural limits.