Uncertainty, variability and sensitivity analysis applied to the ragena model of radon generation, entry and accumulation indoors

The application of a radon model is useful to understand the processes that drive the radon gasbehaviour from its sources to its accumulation indoors. Since in a given inhabited house the detailedknowledge of the values of all the parameters that affect indoor radon levels is not available, theresponse of the model has to be explored in a reference site in which all the parameters are supposedto be known. We call this site the reference configuration. In this paper we report on the procedurefollowed to carry out uncertainty, sensitivity and variability analysis of the model response for areference configuration that corresponds to a single family multi-zone house. We have obtained fromthe uncertainty analysis that, assuming a normal distribution of all the input parameters with a 10%relative standard deviation (RSD), the model outputs present a RSD in the range [17-22]%. Thesensitivity analysis reflects, in general, a good behaviour of the model, in the sense that its responsedescribes a realistic behaviour of the system. The variability analysis has shown that the model isapplicable to a wide range of situations, and that the most relevant parameters for the referenceconfiguration are: the soil gas-permeability (obtained from the mean soil grain diameter), theventilation rate of the rooms, the air-exchange rate between the basement and room 2, the soil-indoorpressure difference, the open area and the concrete radium content.