Estimation and mapping of uranium content of geological units in France.
In France, natural radiation accounts for most of the population exposure to ionizing radiation. The Institute for Radiological Protection and Nuclear Safety (IRSN) carries out studies to evaluate the variability of natural radioactivity over the French territory. In this framework, the present study consisted in the evaluation of uranium concentrations in bedrocks. The objective was to provide estimate of uranium content of each geological unit defined in the geological map of France (1:1,000,000). The methodology was based on the interpretation of existing geochemical data (results of whole rock sample analysis) and the knowledge of petrology and lithology of the geological units, which allowed obtaining a first estimate of the uranium content of rocks. Then, this first estimate was improved thanks to some additional information. For example, some particular or regional sedimentary rocks which could present uranium contents higher than those generally observed for these lithologies, were identified. Moreover, databases on mining provided information on the location of uranium and coal/lignite mines and thus indicated the location of particular uranium-rich rocks. The geological units, defined from their boundaries extracted from the geological map of France (1:1,000,000), were finally classified into 5 categories based on their mean uranium content. The map obtained provided useful data for establishing the geogenic radon map of France, but also for mapping countrywide exposure to terrestrial radiation and for the evaluation of background levels of natural radioactivity used for impact assessment of anthropogenic activities.
Institut de Radioprotection et de Sûreté Nucléaire, PRP-DGE/SEDRAN/BERAM, BP17, 92262 Fontenay aux Roses Cedex, France. Electronic address: geraldine.ielsch@irsn.fr.
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Ielsch
GéoRessources, CNRS, CREGU, Université de Lorraine, BP 239, 54506 Vandoeuvre les Nancy cedex, France. Electronic address: michel.cuney@univ-lorraine.fr.
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Cuney
GEOTER SAS, Géologie Tectonique Environnement et Risques, 3, rue Jean Monnet, 34830 Clapiers, France. Electronic address: francois.buscail@geoter.fr.
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Buscail
GEOTER SAS, Géologie Tectonique Environnement et Risques, 3, rue Jean Monnet, 34830 Clapiers, France. Electronic address: frederic.rossi@geoter.fr.
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Rossi
GEOTER SAS, Géologie Tectonique Environnement et Risques, 3, rue Jean Monnet, 34830 Clapiers, France. Electronic address: amelie.leon@geoter.fr.
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Leon
Institut de Radioprotection et de Sûreté Nucléaire, PRP-DGE/SCAN/BERSSIN, BP17, 92262 Fontenay aux Roses Cedex, France. Electronic address: edward.cushing@irsn.fr.
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Cushing
D005602:France; D019015:Geologic Sediments / Q000737:chemistry*; D011834:Radiation Monitoring; D011848:Radioactive Pollutants / Q000032:analysis*; D014501:Uranium / Q000032:analysis*
D011848:Radioactive Pollutants; D014501:Uranium
France; Geochemistry; Geology; Mapping; Natural radioactivity; Uranium