Accident dosimetry using porcelain: TL analysis of low dose samples

Some of the bricks and tiles collected on previous occasions from the region of Chernobyl were found to be contaminated. In addition, in some regions there was a lack of quartz-bearing ceramic building materials. Porcelain fittings, however, are plentiful, both inside and outside dwellings and give a sensitive thermoluminescent signal when using the pre-dose technique. Four types of porcelain domestic fittings, with accumulated doses of less than 200 mGy, were collected from an apartment block in Pripyat which is being modelled and for which accurate TL measurements are required for comparison. The work has concentrated on establishing criteria for the selection of the samples with the best TL properties and on improving the precision of the pre-dose additive dose method for dose evaluation. Important factors for selection of samples in this dose range (<200 mGy) are the ratio S0/Sn and the sensitivity. The image intensifier proved to be a useful tool for examining the spatial distribution of TL over the porcelain surface and identified one high S0 sample where the signals from the unactivated and activated sample were emitted from different regions of the surface. (Author)