Radioactivity in building materials: room model analysis and experimental methods.

First, models (room models) published in the international literature allowing the exposure to gamma radiation indoors due to building materials to be assessed are reviewed and discussed. For one of them, a sensitivity analysis concerning the effect of changing the parameters (e.g. dimensions of the room, thickness and density of the walls, etc.) used in calculations is performed. Second, a method is proposed for calculating the activity concentration in the walls of a room using: (a) the measured absorbed dose rate in air in the room; (b) the contributions of natural radionuclides (238U, 232Th and 40K) to the absorbed dose rate in air assessed by means of gamma spectrometry indoors; and (c) the specific dose rate (nGy h(-1) per Bq kg(-1)) of natural radionuclides, for the chosen room geometry, calculated with the room model.