Application of numerical modelling for the better design of radon preventive and remedial measures

The risk of radon penetration from soils into buildings is in several countries (Czech Republic, Sweden, Germany, etc.) expressed by the radon index of the building site [5]. Its determination is based on the assessment of the soil permeability and soil gas radon concentration. Both parameters are measured directly on the particular building site at a depth of 0.8 m below ground level. The results of the radon index assessment are used for the design of protective measures against radon from the soil. It is usually assumed that the radon concentration under the house corresponds to the concentration measured at a depth of 0.8 m below the uncovered ground level. However, radon concentrations measured in the sub-floor layer under completed houses revealed that this assumption is mostly not true. We had found out that from 65 single family houses resting on the ground level radon concentrations measured in the sub-floor layer of 21 houses were up to 3.3 times higher than the concentrations measured in the soil around particular houses at a depth of 0.8 m. Situations that could be especially dangerous are those, when the radon concentration under the real house is higher than the concentration measured during the assessment of the radon index of the building site. If the design of radon reduction techniques is based on Application of numerical modelling for the better design of radon preventive and remedial measures Martin Jiranek