French National Radioactive Waste Management Agency Andra

Châtenay-Malabry, France

French National Radioactive Waste Management Agency Andra

Châtenay-Malabry, France

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PubMed | Électricité de France, Ecole Normale Superieure de Cachan, University Paris Est Creteil, French National Radioactive Waste Management Agency Andra and Bauhaus University Weimar
Type: Journal Article | Journal: Sensors (Basel, Switzerland) | Year: 2016

Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain sensor response is required. For this purpose, dielectric properties of intact clay rock samples experimental determined in the frequency range from 1 MHz to 10 GHz were used as input data in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rods based sensor embedded in the clay-rock. The sensor response in terms of the reflection factor was analyzed in time domain with classical travel time analysis in combination with an empirical model according to Topp equation, as well as the theoretical Lichtenecker and Rother model (LRM) to estimate the volumetric water content. The mixture equation considering the appropriate porosity of the investigated material provide a practical and efficient approach for water content estimation based on classical travel time analysis with the onset-method. The inflection method is not recommended for water content estimation in electrical dispersive and absorptive material. Moreover, the results clearly indicate that effects due to coupling of the sensor to the material cannot be neglected. Coupling problems caused by an air gap lead to dramatic effects on water content estimation, even for submillimeter gaps. Thus, the quantitative determination of the in situ water content requires careful sensor installation in order to reach a perfect probe clay rock coupling.


Jia Y.,Wuhan University | Jia Y.,Lille University of Science and Technology | Bian H.B.,French National Center for Scientific Research | Duveau G.,Lille University of Science and Technology | Poutrel A.,French National Radioactive Waste management Agency ANDRA
Computers and Geotechnics | Year: 2016

In this paper, the effects of steel corrosion on the THM response of the geological barrier is studied by simulating a disposal tunnel of high-level radioactive wastes (HLW). The simulation is performed by using a coupled THM finite element code and two different constitutive models: a visco-elastoplastic model for the geological barrier and a von-Mises type model for the steel barriers. The corrosion effects are numerically simulated by a decrease of mechanical properties of steel and a volumetric expansion related to corrosion products. The detailed geometries of engineered barriers and their internal void spaces are incorporated into the numerical simulation. The evolutions of temperature, liquid pressure, displacement, and stress fields in the geological barrier (called the Callovo-Oxfordian claystone) are analyzed. The numerical results exhibit that the influence of steel corrosion on the THM response of the claystone is limited in the near field of disposal tunnel, especially for the displacement and stress fields in the claystone. However, the evolutions of temperature, liquid pressure and plastic zone in the claystone are not disturbed by the corrosion process of steel barriers and are controlled essentially by its THM properties. © 2015 Elsevier Ltd.


Ait Chaou A.,Ecole des Mines de Nantes | Abdelouas A.,Ecole des Mines de Nantes | El Mendili Y.,Ecole des Mines de Nantes | Bouakkaz R.,Ecole des Mines de Nantes | And 3 more authors.
RSC Advances | Year: 2015

Vapor hydration of a simulated typical French nuclear intermediate-level waste (ILW) glass in unsaturated conditions has been studied in order to simulate its behaviour under repository conditions before complete saturation of the disposal site. The experiments were conducted for one year at 50 °C and 90 °C and the relative humidity (RH) was maintained at 92% and 95%. The glass hydration was followed by Fourier Transform Infra-Red spectroscopy (FTIR). The surface of the reacted glass was characterised by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The chemical and mineralogical composition of the alteration products were studied by Energy Dispersive X-ray Spectroscopy (EDX) and μ-Raman spectroscopy, respectively. The glass hydration increased with temperature and RH and led to the formation of a depolymerized gel layer depleted in alkalis. The glass hydration rate decreased with time and remained almost unchanged for the last three months of exposure. Overall, the ILW glass hydration rate was similar to that obtained with the SON68 high-level waste glass. © The Royal Society of Chemistry 2015.


Gorny J.,CNRS Laboratory of Infrared and Raman Spectrochemistry | Lesven L.,CNRS Laboratory of Infrared and Raman Spectrochemistry | Billon G.,CNRS Laboratory of Infrared and Raman Spectrochemistry | Dumoulin D.,CNRS Laboratory of Infrared and Raman Spectrochemistry | And 3 more authors.
Talanta | Year: 2015

Abstract A new laboratory-made Zn-ferrite (ZnFe2O4) binding gel is fully tested using Diffusive Gradient in Thin films (DGT) probes to measure total As [including inorganic As(III) and As(V), as well as MonoMethyl Arsenic Acid (MMAAV) and DiMethyl Arsenic Acid (DMAAV)] in river waters and sediment pore waters. The synthesis of the binding gel is easy, cheap and its insertion into the acrylamide gel is not problematic. An important series of triplicate tests have been carried out to validate the use of the Zn-ferrite binding gel in routine for several environmental matrixes studies, in order to test: (i) the effect of pH on the accumulation efficiency of inorganic As species; (ii) the reproducibility of the results; (iii) the accumulation efficiency of As species; (iv) the effects of the ionic strength and possible competitive anions; and (v) the uptake and the elution efficiency of As species after accumulation in the binding gel. All experimental conditions have been reproduced using two other existing binding gels for comparison: ferrihydrite and Metsorb® HMRP 50. We clearly demonstrate that the Zn-ferrite binding gel is at least as good as the two other binding gels, especially for pH values higher than 8. In addition, by taking into consideration the diffusion rates of As(III) and As(V) in the gel, combining the 3-mercaptopropyl [accumulating only As(III)] with the Zn-ferrite binding gels allows for performing speciation studies. An environmental study along the Marque River finally illustrates the ability of the new binding gel to be used for field studies. © 2015 Published by Elsevier B.V.


Gorny J.,CNRS Laboratory of Infrared and Raman Spectrochemistry | Dumoulin D.,CNRS Laboratory of Infrared and Raman Spectrochemistry | Lesven L.,CNRS Laboratory of Infrared and Raman Spectrochemistry | Noiriel C.,Toulouse University Midi-Pyrénées | And 2 more authors.
Journal of Analytical Atomic Spectrometry | Year: 2015

A new sensitive chromatographic method has been developed for As speciation determination in anoxic pore waters. Starting from aliquots of 25 μL, the different As species As(iii), As(v), MMAAV and DMAAV were separated in less than 4 min by HPIC-ICP-MS using the IonPac® AG7-AS7 anion-exchange column set and dilute HNO3 as mobile phase. The detection limits were below or equal to 0.25 μg L-1 for each As species, which makes the method efficient to determine As speciation in poorly-contaminated sediments. In addition, no precipitation of iron and manganese (hydr)-oxides was observed since the anoxic samples were systematically carefully manipulated under nitrogen atmosphere. Chlorides were eliminated by the chromatographic separation, thus making possible speciation analysis in estuarine or seawater samples. The use of internal standard was not necessary due to good signal stability (<10%) at m/z 75 over 4 h of analysis. An environmental application has also been successfully performed in the Marque River (Northern France). Inorganic As species were detected in pore waters at low concentrations [below 1 and 10 μg L-1, for As(v) and As(iii) respectively]. Others As species, identified as thioarsenic species, were also detected. This journal is © The Royal Society of Chemistry.


El Hajj H.,CNRS Laboratory of Subatomic Physics and Associated Technologies | Abdelouas A.,CNRS Laboratory of Subatomic Physics and Associated Technologies | El Mendili Y.,CNRS Laboratory of Subatomic Physics and Associated Technologies | Karakurt G.,CNRS Laboratory of Subatomic Physics and Associated Technologies | And 2 more authors.
Corrosion Science | Year: 2013

We investigated sequential aerobic and anaerobic microbiologically induced corrosion of carbon steel to simulate deep geological disposal conditions. Under limited oxygen supply, lepidocrocite and magnetite corrosion products formed on the steel coupon, while under continuous oxygen supply, a mixture of lepidocrocite, maghemite and magnetite was identified. Upon oxygen consumption and establishment of sulphidogenic conditions, due to sulphate-reducing bacteria activity, all these oxides disappeared via transformation into pyrrhotite. Corrosion rate of steel in direct anaerobic cultures was higher than that of steel initially corroded in aerobic condition, suggesting a protective role of corrosion product layer formed under sequential aerobic-anaerobic conditions. © 2013 Elsevier Ltd.


Gorny J.,Lille University of Science and Technology | Billon G.,Lille University of Science and Technology | Lesven L.,Lille University of Science and Technology | Dumoulin D.,Lille University of Science and Technology | And 2 more authors.
Science of the Total Environment | Year: 2015

The fate of arsenic - a redox sensitive metalloid - in surface sediments is closely linked to early diagenetic processes. The review presents the main redox mechanisms and final products of As that have been evidenced over the last years. Oxidation of organic matter and concomitant reduction of oxidants by bacterial activity result in redox transformations of As species. The evolution of the sediment reactivity will also induce secondary abiotic reactions like complexation/de-complexation, sorption, precipitation/dissolution and biotic reactions that could, for instance, lead to the detoxification of some As species. Overall, abiotic redox reactions that govern the speciation of As mostly involve manganese (hydr)-oxides and reduced sulfur species produced by the sulfate-reducing bacteria. Bacterial activity is also responsible for the inter-conversion between As(V) and As(III), as well as for the production of methylated arsenic species. In surficial sediments, sorption processes also control the fate of inorganic As(V), through the formation of inner sphere complexes with iron (hydr)-oxides, that are biologically reduced in buried sediment. Arsenic species can also be bound to organic matter, either directly to functional groups or indirectly through metal complexes. Finally, even if the role of reduced sulfur species in the cycling of arsenic in sediments has been evidenced, some of the transformations remain hypothetical and deserve further investigation. © 2014 Elsevier B.V.


PubMed | Toulouse University Midi-Pyrénées, French National Radioactive Waste Management Agency Andra and Lille University of Science and Technology
Type: | Journal: The Science of the total environment | Year: 2014

The fate of arsenic - a redox sensitive metalloid - in surface sediments is closely linked to early diagenetic processes. The review presents the main redox mechanisms and final products of As that have been evidenced over the last years. Oxidation of organic matter and concomitant reduction of oxidants by bacterial activity result in redox transformations of As species. The evolution of the sediment reactivity will also induce secondary abiotic reactions like complexation/de-complexation, sorption, precipitation/dissolution and biotic reactions that could, for instance, lead to the detoxification of some As species. Overall, abiotic redox reactions that govern the speciation of As mostly involve manganese (hydr)-oxides and reduced sulfur species produced by the sulfate-reducing bacteria. Bacterial activity is also responsible for the inter-conversion between As(V) and As(III), as well as for the production of methylated arsenic species. In surficial sediments, sorption processes also control the fate of inorganic As(V), through the formation of inner sphere complexes with iron (hydr)-oxides, that are biologically reduced in buried sediment. Arsenic species can also be bound to organic matter, either directly to functional groups or indirectly through metal complexes. Finally, even if the role of reduced sulfur species in the cycling of arsenic in sediments has been evidenced, some of the transformations remain hypothetical and deserve further investigation.


PubMed | University Paul Sabatier, Lille University of Science and Technology and French National Radioactive Waste Management Agency Andra
Type: | Journal: Talanta | Year: 2015

A new laboratory-made Zn-ferrite (ZnFe2O4) binding gel is fully tested using Diffusive Gradient in Thin films (DGT) probes to measure total As [including inorganic As(III) and As(V), as well as MonoMethyl Arsenic Acid (MMAA(V)) and DiMethyl Arsenic Acid (DMAA(V))] in river waters and sediment pore waters. The synthesis of the binding gel is easy, cheap and its insertion into the acrylamide gel is not problematic. An important series of triplicate tests have been carried out to validate the use of the Zn-ferrite binding gel in routine for several environmental matrixes studies, in order to test: (i) the effect of pH on the accumulation efficiency of inorganic As species; (ii) the reproducibility of the results; (iii) the accumulation efficiency of As species; (iv) the effects of the ionic strength and possible competitive anions; and (v) the uptake and the elution efficiency of As species after accumulation in the binding gel. All experimental conditions have been reproduced using two other existing binding gels for comparison: ferrihydrite and Metsorb HMRP 50. We clearly demonstrate that the Zn-ferrite binding gel is at least as good as the two other binding gels, especially for pH values higher than 8. In addition, by taking into consideration the diffusion rates of As(III) and As(V) in the gel, combining the 3-mercaptopropyl [accumulating only As(III)] with the Zn-ferrite binding gels allows for performing speciation studies. An environmental study along the Marque River finally illustrates the ability of the new binding gel to be used for field studies.


Farin S.,French National Radioactive Waste Management Agency Andra | Ouzounian G.,French National Radioactive Waste Management Agency Andra
13th International High-Level Radioactive Waste Management Conference 2011, IHLRWMC 2011 | Year: 2011

This article shows the progression of the French National Radioactive Waste Management Agency approach since 2006, by presenting the method it used in designing, implementing and monitoring its information and consultation approach. The determination of a 30-km2 zone to reduce reduced the potential disposal implantation zone will serve as an example in concretely illustrating how this approach was handled day to day. Lastly, it will analyse the initial consultation phase to help outline the sources of satisfaction and the progress made by Andra with respect to this issue.

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