In situ gamma spectroscopy to characterize building materials as radon andthoron sources

In situ gamma spectroscopy is widely utilized to determine the outdoor gamm a dose rate from the soil and to calculate the natural and artificial radio nuclide concentration and their contribution to the dose rate. The applicat ion of in situ gamma spectroscopy in indoor environments can not supply qua ntitative information about activity concentration of radionuclides in buil ding materials, but this technique can provide interesting information abou t building materials as radon source. In fact, a method based on analyses o f gamma spectra data has been developed by the authors to provide, in field , quantitative estimation of disequilibrium in Ra-226 and Ac-228 sub-chains due to Rn-222 and Rn-220 exhalation. The method has been applied to data o f gamma spectroscopy measurements carried out with HPGe detector (26%) in s even dwellings and one office in Rome. The first results of the data analys is show that, as regards especially the Ra-226 sub-chain disequilibrium, di fferent building materials (tuff, concrete, etc.) can show very different c haracteristics. If, in addition to the spectrometric data, other indoor env ironment parameters (indoor gamma dose rates, room dimensions, wail thickne ss, etc.) (Bochicchio ct al., Radiat Prot Dosim 1994;56(1-4):137-140; Bochi cchio et at., Environ Int 1996a;22:S633-S639) are utilized in a room model, an evaluation of Ra-226, Ac-228 and K-40 activity concentration and an ind ication of the exhalation features, by means of estimation of exhaled Rn-22 2 activity concentration, can be achieved. (C) 2001 Elsevier Science B.V. A ll rights reserved.