Study of Radioactive Radon Gas Exhaled from Some Materials

Soil samples and some different materials were collected for radon exhalation measurements. In this study radon exhalation was determined and the effect of filter paper above the sample inside the hollow holder (dosimeter), and relative humidity were investigated. Although the soil gas represents the major source of indoor radon, the characteristics of the house construction and lifestyle of the occupants can play an equally important role in defining the indoor concentration. By using the calibrated track detector CR-39 the radon exhalation rates from building materials and building surfaces could be measured. Placing the CR-39 in an inverted hollow holder to measure the radon exhalation rates is a convenient method. Tracks due to alpha particles from radon that migrate from the building materials into the air space in the chamber were registered on the CR-39 detector. The detectors were etched in 8 M NaOH solution at 70 degree for 8 hours. The arrangement used for the measurement of radon exhalation consists of solid- state track detectors and image analysis system (Quantimet 500). The equilibrium factor and alpha dose were calculated. All measurements were normalized according to the results of 1999 intercomparison at NRPB (UK). Phosphogypsum produced the highest exhalation rate, but wood had the lowest exhalation rate. Ceramics as a building surface has higher exhalation rate than from plaster paint suraces