Evaluation of meat and bone meal combustion residue as lead immobilizing material for in situ remediation of polluted aqueous solutions and soils: “Chemical and ecotoxicological studies”.

International audienceAs a result of bovine spongiform encephalopathy (BSE) crisis, meat and bone meal (MBM) production can no longer be used to feed cattle and must be safely disposed of or transformed. MBM specific incineration remains an alternative that could offer the opportunity to achieve both thermal valorization and solid waste recovery as ashes are calcium phosphate-rich material. The aim of this work is to evaluate ashes efficiency for in situ remediation of lead-contaminated aqueous solutions and soils, and to assess the bioavailability of lead using two biological models, amphibian Xenopus laevis larvae and Nicotiana tabaccum tobacco plant. With the amphibian model, no toxic or genotoxic effects of ashes are observed with concentrations from 0.1 to 5 g of ashes/L. If toxic and genotoxic effects of lead appear at concentration higher than 1 mg Pb/L (1 ppm), addition of only 100 mg of ashes/L neutralizes lead toxicity even with lead concentration up to 10 ppm. Chemical investigations (kinetics and X-ray diffraction (XRD) analysis) reveals that lead is quickly immobilized as pyromorphite [Pb10(PO4)6(OH)2] and lead carbonate dihydrate [PbCO3•2H2O]. Tobacco experiments are realized on contaminated soils with 50, 100, 2000 and 10 000 ppm of lead with and without ashes amendment (35.3 g ashes/kg of soil). Tobacco measurements show that plant elongation is bigger in an ashes-amended soil contaminated with 10 000 ppm of lead than on the reference soil alone. Tobacco model points out that ashes present two beneficial actions as they do not only neutralize lead toxicity but also act as a fertilizer

Evaluation of meat and bone meal combustion residue as lead immobilizing material for in situ remediation of polluted aqueous solutions and soils: “Chemical and ecotoxicological studies”.

As a result of bovine spongiform encephalopathy (BSE) crisis, meat and bone meal (MBM) production can no longer be used to feed cattle and must be safely disposed of or transformed. MBM specific incineration remains an alternative that could offer the opportunity to achieve both thermal valorization and solid waste recovery as ashes are calcium phosphate-rich material. The aim of this work is to evaluate ashes efficiency for in situ remediation of lead-contaminated aqueous solutions and soils, and to assess the bioavailability of lead using two biological models, amphibian Xenopus laevis larvae and Nicotiana tabaccum tobacco plant. With the amphibian model, no toxic or genotoxic effects of ashes are observed with concentrations from 0.1 to 5 g of ashes/L. If toxic and genotoxic effects of lead appear at concentration higher than 1 mg Pb/L (1 ppm), addition of only 100 mg of ashes/L neutralizes lead toxicity even with lead concentration up to 10 ppm. Chemical investigations (kinetics and X-ray diffraction (XRD) analysis) reveals that lead is quickly immobilized as pyromorphite [Pb10(PO4)6(OH)2] and lead carbonate dihydrate [PbCO3•2H2O]. Tobacco experiments are realized on contaminated soils with 50, 100, 2000 and 10 000 ppm of lead with and without ashes amendment (35.3 g ashes/kg of soil). Tobacco measurements show that plant elongation is bigger in an ashes-amended soil contaminated with 10 000 ppm of lead than on the reference soil alone. Tobacco model points out that ashes present two beneficial actions as they do not only neutralize lead toxicity but also act as a fertilizer

Corrosion of carbon steel components in the French high-level waste program evolution of disposal concept and selection of materials.

International audienceIn France, the reference concept for the geological disposal of high-level waste (HLW) consists of horizontal micro-tunnels, containing carbon steel casing and overpacks (around a stainless steel container containing vitrified waste). The overpacks and casing will be exposed to an environment that will evolve over time: from a hot and humid atmosphere containing oxygen, to an anoxic environment saturated with water at the geothermal temperature. Lots of corrosion experiments have been performed in representative environments to study steel corrosion modes (general corrosion, pitting and crevice corrosion, stress corrosion cracking, hydrogen embrittlement…) while taking into account the influence of temperature, radiation, mechanical stresses and microorganisms. Some key results have influenced the design of the HLW disposal cell, including the carbon steel grades and dimensions of the casing and overpacks, or the addition of an alkaline grout material between the casing and the host rock

Corrosion of carbon steel components in the French high-level waste program evolution of disposal concept and choices of materials.

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Bio-corrosion detection by sulphur isotopic fractionation measurements using nanoSIMS

International audienceThe presence of Sulphate-Reducing Bacteria (SRB) may influence the corrosion rate of ferrous objects by inducing iron sulphides precipitation. The same phases are formed by biotic or abiotic ways. Yet, biotic iron sulphides are supposed to be depleted in heavy isotopes of sulphur relative to the starting sulphates[1]. So, sulphur isotopic composition analyses enable to determine the (a-)biotic origin of the iron sulfides. Previously, a single study [2] devoted to corrosion issues had used the sulphur isotopic composition to determine the origin of sulphides compounds formed on Cu/Ni steel. However, the sulphur isotopic fractionation was obtained by global mass spectrometry from the precipitation into BaSO4 of the remaining sulphates of the corrosion experiment. This method is not adapted to the iron sulphides formed in field samples, presents as strips of some micrometers size [3]. To fill this analytical gap, in the study presented here, nanoSIMS (nanoscale Secondary Ion Mass Spectrometry) is used to determine the local sulphur isotopic composition of the iron sulphides within the corrosion product layers oftwo kinds offield samples: a short term system consisting of a steel coupon buried for 24 months in the Andra (French National Radioactive Waste Management Agency) Underground Research Laboratory devoted to research onthe geological disposal of radioactive waste at Bure (Grand Est, France); and long term systems composed of iron nails buried in the water-saturated soil of the archeological site of Glinet (Normandie, France) during around 500 years. Thus, thanks to the methodology developed the iron sulphide bio-origin is proved in both corroded samples

Bio-corrosion detection by sulphur isotopic fractionation measurements using nanoSIMS

International audienceThe presence of Sulphate-Reducing Bacteria (SRB) may influence the corrosion rate of ferrous objects by inducing iron sulphides precipitation. The same phases are formed by biotic or abiotic ways. Yet, biotic iron sulphides are supposed to be depleted in heavy isotopes of sulphur relative to the starting sulphates[1]. So, sulphur isotopic composition analyses enable to determine the (a-)biotic origin of the iron sulfides. Previously, a single study [2] devoted to corrosion issues had used the sulphur isotopic composition to determine the origin of sulphides compounds formed on Cu/Ni steel. However, the sulphur isotopic fractionation was obtained by global mass spectrometry from the precipitation into BaSO4 of the remaining sulphates of the corrosion experiment. This method is not adapted to the iron sulphides formed in field samples, presents as strips of some micrometers size [3]. To fill this analytical gap, in the study presented here, nanoSIMS (nanoscale Secondary Ion Mass Spectrometry) is used to determine the local sulphur isotopic composition of the iron sulphides within the corrosion product layers oftwo kinds offield samples: a short term system consisting of a steel coupon buried for 24 months in the Andra (French National Radioactive Waste Management Agency) Underground Research Laboratory devoted to research onthe geological disposal of radioactive waste at Bure (Grand Est, France); and long term systems composed of iron nails buried in the water-saturated soil of the archeological site of Glinet (Normandie, France) during around 500 years. Thus, thanks to the methodology developed the iron sulphide bio-origin is proved in both corroded samples

Ruthenium p-cymene iminophosphonamide complexes: Activation under basic conditions and transfer hydrogenation catalysis

International audienceComplex [(η6-Cym)RuCl(NPN)] Cym = p-cymene; NPN = (pTolN)2PPh2 (1) yields a thermally sensitive hydride derivative [(η6-Cym)RuH(NPN)] (2) by reaction with iPrOH in the presence of a strong base, via an observable isopropoxide intermediate [(η6-Cym)Ru(OiPr)(NPN)] (3), or with NaBHEt3 in toluene. Partial conversion also occurs in iPrOH in the absence of base. 2 is stabilized by dihydrogen bonding with isopropyl alcohol, but attempts to isolate it induce isomerization by hydride migration to a ring CH position to yield a 16-electron cyclohexadienyl derivative [η5-p-C6H5(Me)(iPr)Ru(NPN)], which has been crystallographically characterized as a disordered mixture of two regioisomers (4/4′). Complex 2 is able to release H2 upon treatment with medium strength proton donors (fluorinated alcohols), but also slowly with iPrOH. 2 is an active catalyst for the transfer hydrogenation of acetophenone to phenylethanol in isopropyl alcohol. The catalytic transformation is first order in acetophenone and first order in catalyst, with k = 117 ± 10 m–1 h–1 at 40 °C. The temperature dependence of the rate constant (25–80 °C) gave the activation parameters ΔH‡ = 9.6 ± 1.3 kcal mol–1 and ΔS‡ = –31 ± 4 cal mol–1 K–1. DFT calculations have validated the slow isomerization of 2 to 4/4′ (high energy TS), the preference of the cyclohexadienyl system for 4/4′ relative to the other isomers 4Me and 4iPr, where the hydride has migrated to the CMe or CiPr position, and suggest that the hydrogen transfer mechanism involves outer sphere hydride transfer to the ketone substrate with H-bonding assistance of isopropyl alcohol to yield a σ complex intermediate [(η6-Cym)Ru+(NPN)H-C(Me)(Ph)O–]

The corrosion behaviour of candidate container materials for the disposal of high level waste and spent fuel – a summary of the state of the art and opportunities for synergies in future R&D

This paper presents a state-of-the-art analysis of the expected degradation processes of a variety of candidate container materials for the disposal of high-level waste and/or spent nuclear fuel. The work, focusing on the most recent developments, has been performed under the auspices of the Implementing Geological Disposal Technology Platform in the context of an international conference hosted by the Nuclear Waste Management Organisation of Canada (NWMO). The scope of the analysis includes the expected corrosion and environmentally assisted cracking behaviour of copper, carbon steel and titanium in contact with relevant buffer materials (e.g. bentonite, cement) and in conditions expected in an underground disposal facility (long-term anoxic conditions). Considerations relative to the expected evolution of the environmental conditions (especially in the period following backfilling) are also presented. Beyond summarising the current state of knowledge, areas in which opportunities for international collaboration may be present are also highlighted. This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.Peer reviewe