Calculation of the indoor gamma dose rate distribution due to building materials in the Netherlands.

In this study, a model to determine the indoor absorbed dose rate in air due to building materials is applied to a representative set of 1336 Dutch dwellings of which the areas occupied by the various kinds of building material are well documented. Using a Monte Carlo method, the building material and housing data are combined with activity concentrations and densities of 90 samples of building material. From (100,000) repeated calculations according to the model, the distribution of the absorbed dose rate in Dutch livings is computed. The outcomes are compared with those of earlier national measuring campaigns on the indoor dose rate. When corrected for cosmic and terrestrial radiation, a similar distribution of the indoor dose rate is found with an average value within 5% of that found by measurements. A sensitivity analysis revealed that the three most influential input parameters of the model are the density and thickness of the construction parts, the presence of doors and windows and attenuation by the inner cavity wall.