Radiological survey of Hungarian clays; radon emanation and exhalation influential effect of sample and internal structure conditions

In case of indoor conditions the probability of the radon accumulation is high, greatly depends on the features of the surrounding materials. In order to prevent the elevated indoor radon levels in buildings the influencing parameters of the migration and origin of the radon-generated in the building materials-should be investigated beyond the Ra-226 content. The natural radioactive content of 27 clay samples, which are used as raw material in brick factories were investigated in radiological point of view. The radon emanation factors were determined as well. The optimal sample thickness of the powdered and wet clay samples were determined in order to measure the free exhalation. The effect of the moisture content modifying the radon emanation was determined as well. The obtained results clearly prove that the measurement of emanation in dry state is not enough to characterize the radon emanation features and via that the radon exhalation capacity of the material.