| NUKLEONIKA 2010, 55(4):463-469
SPECIFIC PROPERTIES OF A MODEL OF THORON AND ITS DECAY PRODUCTS IN INDOOR ATMOSPHERESOliver Meisenberg, Jochen Tschiersch Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, 1 Ingolstädter Landstr., 85764 Neuherberg, Germany Whereas several models of indoor concentrations of radon and its decay products exist, models for the occurrence and spatial distribution of thoron (220Rn) and its decay products are lacking. This study highlights the specific properties of the thoron decay chain and presents their consequences for a thoron model. The short half-life of thoron results in an inhomogeneous spatial distribution, which is determined by diffusive and advective transport. The long half-life of the decay product 212Pb accounts for a strong influence of air exchange on its overall concentration as well as on its unattached fraction. It could further be predicted that also the unattached part of 212Pb is distributed inhomogeneously. The theoretical structure of a thoron model, which can neglect the most short-lived decay products but must account for the influence of air exchange in a stronger way than it is the case for radon, results from these considerations. Close X |