Determination of natural radioactivity in building materials used in Tunisian dwellings by gamma ray spectrometry

The radioisotopic content of 17 samples of natural and manufactured building materials collected in Tunisia have been analysed by using gamma spectrometry. From the measured gamma ray spectra, activity concentrations are determined for 232Th, 226Ra, 235U and 40K. The total effective dose and the activity concentration index are calculated applying the dose criteria recommended by the European Union for building materials. The results of 226Ra, 232Th and 40K found in Tunisian building materials indicate that radium and thorium concentrations do not exceed 40 Bq kg-1, but potassium concentration varies between 50 and 1215 Bq kg-1. The total effective dose rates per person indoors are determined to be between 0.07 and 0.86 mSv y-1. Only two materials exceed the reference level of 0.3 mSv y-1. The activity concentration index is <1. (authors)