Abstract
Radon gas is the largest natural source of human exposure to ionizing radiation and most of that exposure occurs in indoor air. Bedrock geology is an important factor in radon hazard evaluation of an area. The presence of rock types usually rich in uranium can be considered an indication of a potential radon hazard. In this study the average 226Ra activity concentration of the main rock types (orthogneiss, micaschist, leucophyllite) in the Sopron Mountains was measured by gamma-spectroscopy, to reveal the uranium rich areas. This work is focusing on the distribution of 226Ra among the different rock types of the Sopron Mountains with similar geological origin. The effect of different retrograde processes such as mylonitisation, fluid migration and argillitic–limonitic alteration on 226Ra activity concentration was investigated. A few anomalies occurred in these metamorphic rocks. One explanation of the high uranium concentration is the high radioactive level of the rocks before the metamorphosis, but we demonstrated the significance of the above mentioned secondary processes as well. At Nándormagaslat quarry the presence of radium anomaly we found in the limonitic alteration of weathered gneiss (range: 131–726 Bq kg−1) in fractures explains the high air concentration nearby in houses (96–2,051 Bq m−3) and in a corresponding tunnel (maximum 600 kBq m−3).
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2013/59/EURATOM
Acknowledgments
The authors are grateful to Dr. Csaba Szabó and his crew in the Lithosphere Fluid Research Lab (LRG) for helping in sample preparation, to Viktor Wesztergom and Gyula Mentes for their help on accessing some part of the field, to Gyula Pávó and Ottó Csorba for their help during the measurements and for the two anonymous reviewers on behalf of the journal, whose constructive remarks and criticism helped to improve the quality of the manuscript. Special thanks are due to Tibor Horváth, who helped to carry out all of the sampling.
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Freiler, Á., Horváth, Á. & Török, K. 226Ra activity distribution of rocks in the Sopron Mts. (West-Hungary). J Radioanal Nucl Chem 306, 243–247 (2015). https://doi.org/10.1007/s10967-014-3914-3
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DOI: https://doi.org/10.1007/s10967-014-3914-3