[en] Since 2011 the CETAMA (Analytical Methods Committee) has organized 3 Round-Robin tests successively to determine the capability of laboratories to measure gross alpha and beta in various waters. Different parameters are considered such as the origin of radionuclides (natural and artificial) and the variation of the salt content (from a low mineralized solution to highly mineralized water such as seawater). Technical specifications are defined within the working group 'Water analysis' in order to solve some problems observed in measurement of gross alpha and beta activity concentrations. The objective is to identify the causes of a discrepancy between the values obtained from the total counts and the sum of the reference values of each radionuclide alone. These Round-Robin tests allow accredited laboratories (or nearly accredited) to train in order to obtain accepted results in French regulatory proficiency tests organized by the IRSN. From the reference values of the various radionuclides (delivered by a primary metrology laboratory) contained in the samples, the averages of the results obtained by the laboratories are calculated and compared. Synthesis of the results highlighted the difficulty in obtaining reference values for gross alpha and gross beta activity. A method is proposed, established from standard and official guidelines based on robust calculation, to determine these assigned values with their associated uncertainty. Feedback from the various interlaboratory comparisons led to suggesting recommendations, particularly in terms of calibration and sample preparation, which allow a significant improvement in the accuracy (trueness and precision) of the method. (authors)

[en] Application of on-line X-ray fluorescence (XRF) analysis in the mining and processing industry of uranium (U) can improve the representativeness and speed of analysis and lower costs. Potential applicability of the industrial XRF analyser CON-X series is demonstrated for continuous measurement of uranium content in various uranium-bearing materials (heavy mineral sands, phosphate rock and fertilizers, U ore residues after heap-leaching, monazite ore etc.) and at wide ranges of U concentrations (from 100 ppm up to tens of percent). In addition to the physical components required to perform on-line XRF measurements, analyser design and analytical method can be customized to the requirements of specific field or process. The dynamic laboratory simulation of on-line measurement of uranium in ground N-P-K fertilizers indicates statistically acceptable correlation with routine analysis. Estimated detection limit (DL) obtained with replicate measurements is 25–50 ppm depending on the type of phosphate material. On-site test of the CON-X analyser for continuous analysis of uranium in ore residues after heap-leaching showed that the difference between on-line and laboratory results was within 10% relative at the level of 100 ppm U. DL is estimated at 30–50 ppm in 5-minute measurements depending on interfering elements. Advantages and limitations of CON-X analyser for on-line analysis of uranium in solid materials transported by the conveyor are also discussed. (author)

[en] The introduction of on-line X-ray fluorescence (XRF) analysis in the mining and processing industry of uranium (U) can improve the representativeness and speed of analysis and lower costs. Potential applicability of the industrial XRF analyzer CON-X series is demonstrated for continuous measurement of uranium content in various materials (rutile and zircon sands, phosphate rock and fertilizers, U ore residues after leaching, monazite ore etc.) and at wide ranges of U concentrations (from 100 ppm up to tens %). In addition to the physical components required to perform on-line XRF measurements, analyzer design and analytical method can be customized to the requirements of specific field or process. The dynamic laboratory simulation of on-line measurement of uranium in ground N-P-K fertilizers indicates statistically acceptable correlation with routine analysis. Estimated detection limit obtained with replicate measurements is 25-50 ppm depending on the type of phosphate material. On-site test of the CON-X analyzer for continuous analysis of uranium in ore residues after heap leaching showed that the difference between on-line and laboratory results was within 10% relative at the level of 100 ppm U. Uranium detection limit is estimated at 30-50 ppm in 5 minute measurements depending on interfering element. Advantages and limitations of CON-X analyzer for on-line analysis of uranium solid materials transported by the conveyor are also discussed. (author)

[en] This study investigated the influence of uranium on the indigenous bacterial community structure in natural soils with high uranium content. Radioactive soil samples exhibiting 0.26% - 25.5% U in mass were analyzed and compared with nearby control soils containing trace uranium. EXAFS and XRD analyses of soils revealed the presence of U(VI) and uranium phosphate mineral phases, identified as sabugalite and meta-autunite. A comparative analysis of bacterial community fingerprints using denaturing gradient gel electrophoresis (DGGE) revealed the presence of a complex population in both control and uranium-rich samples. However, bacterial communities inhabiting uraniferous soils exhibited specific fingerprints that were remarkably stable over time, in contrast to populations from nearby control samples. Representatives of Acidobacteria, Proteobacteria, and seven others phyla were detected in DGGE bands specific to uraniferous samples. In particular, sequences related to iron-reducing bacteria such as Geobacter and Geothrix were identified concomitantly with iron-oxidizing species such as Gallionella and Sideroxydans. All together, our results demonstrate that uranium exerts a permanent high pressure on soil bacterial communities and suggest the existence of a uranium redox cycle mediated by bacteria in the soil. (authors)

[en] Radon is considered to be the main source of human exposure to natural radiation. As stated by the World Health Organization, the exposure due to the inhalation of indoor radon is much greater than the one via the ingestion of water as radon degasses from water during handling. In response to these concerns about the universal presence of radon, environmental assessment studies are regularly commissioned to assess the radon exposure of public and workers. The credibility of such studies relies on the quality and reliability of radon analysis as well as on the sample representativeness of the radiological situation. The standard-setting approach, based on consensus, seemed to lend itself to a settlement of technical aspects of potential comparison. At present, two Working Groups of the International Standardization Organization are focussing on drafting standards on radon and its decay products measurement in air and water. These standards, which aim for a set of rigorous metrology practices, will be useful for persons in charge of the initial characterisation of a site with respect to natural radioactivity as well as to those performing the routine surveillance of specific sites. (authors)