First international intercomparison of luminescence techniques using samples from the Techa River Valley.

GSF-National Research Centre for Environment and Health, Germany.
Health Physics (Impact Factor: 1.02). 02/2002; 82(1):94-101. DOI: 10.1097/00004032-200201000-00012
Source: PubMed

ABSTRACT Bricks collected from a contaminated village (Muslyumovo) of the lower Techa river valley, Southern Urals, Russia, were measured using thermoluminescence and optically stimulated luminescence by four European laboratories and a U.S. laboratory to establish and compare the applied dose reconstruction methodologies. The bricks, collected from 60-100-year-old buildings, had accumulated a relatively high dose due to natural sources of radiation in the brick and from the surrounding environment. This work represents the results of a first international intercomparison of luminescence measurements for bricks from the Southern Urals. The luminescence measurements of absorbed dose in bricks collected from the most shielded locations of the same buildings were used to determine the background dose due to natural sources of radiation and to validate the age of the bricks. The absorbed dose in different bricks measured by four laboratories using thermoluminescence and optically stimulated luminescence at a depth of 10 +/- 2.5 mm from the exposed brick surface agreed within +/-21%. After subtraction of the natural background dose, the absorbed dose in brick due to contaminated river sediments and banks was calculated and found to range between 150 and 200 mGy. The cumulative doses in brick due to man-made sources of radiation at 100 and 130 mm depths in the bricks were also measured and found to be consistent with depth dose profiles calculated by Monte Carlo simulations of photon transport for possible source distributions.

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    ABSTRACT: The potential of the 210°C Thermoluminescence (TL) peak in quartz for accurate dose reconstruction is studied by comparative TL and optically simulated luminescence (OSL) measurements on quartz extracted from bricks from a mill in a contaminated village of the Techa River valley, Southern Urals, Russia. The cumulative doses measured with TL were found to be continuously lower (on average 10–20%) than the ones measured with OSL for the same sample and using the same luminescence reader. From dose recovery tests, laboratory kinetic analysis and available meteorological parameters of the sample site for the past 100 years, it is concluded that the most likely reason for the discrepancy is thermal fading of the 210°C TL peak. By applying a suitable model, an effective lifetime of the electron trap of the 210°C TL peak of 200–700 years is estimated for the moderate continental climate at the sample site. It is concluded that for samples in regions of continental climate and directly exposed to sunlight, dose measurements using the 210°C TL peak should be restricted to the last 50–60 years. Applications to older samples should only be considered if bricks are not directly exposed to sunlight or if the background dose is small compared to the anthropogenic dose, as the latter will have been acquired during shorter times and will thus not have been subjected to significant thermal fading.
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