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The influence of near field hydrogen on actinide solubilities and spent fuel leaching
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Kastriot Spahiu
Published/Copyright:
September 25, 2009
Large amounts of hydrogen are produced as a result of the anoxic corrosion of iron in the proposed container materials for some geologic repositories. Another hydrogen source, less important than the anoxic corrosion of iron, is the radiolysis of water by the spent fuel radiation. Gas phase formation occurs when the pressure of the hydrogen equals at least the hydrostatic pressure, around 5 MPa at 500 meters depth. The effects of 5 MPa hydrogen pressure on spent PWR fuel leaching and on uranium oxide solubility have been studied in carbonated solutions at 70 °C. The experiments were performed in a 1 liter autoclave, filled with 950 ml of a solution 10 mM NaCl, 2 mM NaHCO3 and with hydrogen at a pressure of 5 MPa in the remaining 50 ml free volume. The leaching behavior of 2 g PWR spent fuel powder of the 0.25-0.50 mm fraction, placed in a gold basket was studied during several months by analyzing 10 ml solution samples taken after regular time intervals. A few experiments were performed also with unirradiated U(IV) oxide. In both cases extremely low concentrations of uranium (less than 10-9 M were measured in the solution samples. Furthermore the uranium levels in solution remained practically constant during the whole leaching period (more than one year), indicating the absence of any oxidative dissolution of the spent fuel matrix. The same conclusion is confirmed by the constant (within analytical errors) levels of strontium, cesium, molybdenum, iodine and technetium during the whole leaching period. These results have been compared with the ones obtained during the leaching of a spent fuel pin in anoxic conditions, where the uranium and other radionuclides levels are several orders of magnitude higher.
The surface of spent fuel or U(IV) oxide is partially oxidized during storage, giving rise to relatively high levels of U(VI) in solution even during leaching in anoxic conditions. No such effect could be observed in the presence of 5 MPa hydrogen, indicating that this initial amount of U(VI) should have been reduced to U(IV). The experimental study of the influence of various parameters as temperature and pressure is still in progress.
Published Online: 2009-9-25
Published in Print: 2000-9-1
© 2015 Oldenbourg Wissenschaftsverlag GmbH, Rosenheimer Str. 145, 81671 München
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Articles in the same Issue
- Preface: Migration Conference 1999
- The influence of near field hydrogen on actinide solubilities and spent fuel leaching
- Experimental determination and chemical modelling of radiolytic processes at the spent fuel/water interface
- Thermodynamic data for the solubility of tin(IV) in aqueous cementitious environments
- Leaching behaviour of UO2 containing α-emitting actinides
- Dehydration of synthetic autunite hydrates
- Aqueous dissolution kinetics of pyrochlore, zirconolite and brannerite at 25, 50, and 75 °C
- Complex formation of Np(V) with humic acid and polyacrylic acid
- Investigation of humic acid complexation behavior with uranyl ions using modified synthetic and natural humic acids
- Solution coordination chemistry of uranium in the binary UO22+-SO42- and the ternary UO22+-SO42--OH- system
- The speciation of Tc(IV) in chloride solutions
- The hydrolysis of uranium(VI) in sulfate media
- Complex formation of Eu(III) with polyacrylic acid
- Determination of Co(II) and Ni(II)-humate stability constants at high ionic strength NaCl solutions
- Analysis of Th(IV)-humate by XPS
- EXAFS structural analysis of aqueous uranium(VI) complexes with lignin degradation products
- Thermodynamic modeling of metal-ligand interactions in high ionic strength NaCl solutions: the Co2+-oxalate system
- Mixed Ca2+/UO22+/CO32- complex formation at different ionic strengths
- Humic colloid-borne Np migration: influence of the oxidation state
- Reduction of Pu(V) by humic acid
- Colloid-borne uranium and other heavy metals in the water of a mine drainage gallery
- Application of LIBD to the determination of the solubility product of thorium(IV)-colloids
- The Rossendorf Beam Line ROBL – a dedicated experimental station for XAFS measurements of actinides and other radionuclides
- Extended X-ray absorption fine structure and time differential perturbed angular correlation study of hafnium(IV) sorbed onto amorphous silica
- Speciation analysis on europium(III) using laser-induced breakdown spectroscopy
- The migration behavior of Np(V) in sandy soil and granite media in the presence of humic substances
- Uranium(VI) and neptunium(V) transport through fractured, hydrothermally altered concrete
- Experimental study and modeling of uranium (VI) transport through ferrous olivine rock columns
- Aqueous Pu(IV) sorption on brucite
- Surface spectroscopic studies of Cs+, and Ba2+ sorption on chlorite-illite mixed clay
- Approaches to modelling uranium(VI) adsorption on natural mineral assemblages
- Evaluation of radioactive nickel distribution coefficient by analyzing background stable nickel
- Application of electrokinetic data to test the adsorption models
- Sorption equilibrium and kinetics of NpO2+ on dispersed particles of Na-montmorillonite
- Sorption of Am(III) and Eu(III) onto γ-alumina: experiment and modelling
- Effects of humic acid on the sorption of Am(III) and Cm(III) on kaolinite
- Uranium(VI) sorption onto phyllite and selected minerals in the presence of humic acid
- The partitioning of uranium and neptunium onto hydrothermally altered concrete
- Alteration products of uraninite from the Colorado Plateau
- Fracture-filling minerals as uranium sinks and sources, a natural analogue study at Palmottu, Finland
- Spectroscopic properties of uranium(VI) minerals studied by time-resolved laser-induced fluorescence spectroscopy (TRLFS)
- Fracture smectite as a long-term sink for natural radionuclides – indications from unusual U-series disequilibria
- The potential of subterranean microbes in facilitating actinide migration at the Grimsel Test Site and Waste Isolation Pilot Plant
- Application of gel electrophoretic techniques to the investigation of actinide-humic interactions in soils
- Applications of NAA, PIXE and XPS for the quantification and characterization of the humic substances/iodine association
- Quantitative assessment of radiocaesium bioavailability in forest soils
- Actinide partitioning to an acidic, sandy lake sediment
- Adsorption of Cs and U(VI) on soils of the Australian arid zone
- Natural and artificial radionuclides in forest and bog soils: Tracers for migration processes and soil development
- Distribution of natural radionuclides during the processing of phosphate rock from Itataia-Brazil for production of phosphoric acid and uranium concentrate
- An electrostatic approach for the prediction of actinide complexation constants with inorganic ligands-application to carbonate complexes
- Determination and uncertainties of radioelement solubility limits to be used by SKB in the SR 97’ performance assessment exercise
Articles in the same Issue
- Preface: Migration Conference 1999
- The influence of near field hydrogen on actinide solubilities and spent fuel leaching
- Experimental determination and chemical modelling of radiolytic processes at the spent fuel/water interface
- Thermodynamic data for the solubility of tin(IV) in aqueous cementitious environments
- Leaching behaviour of UO2 containing α-emitting actinides
- Dehydration of synthetic autunite hydrates
- Aqueous dissolution kinetics of pyrochlore, zirconolite and brannerite at 25, 50, and 75 °C
- Complex formation of Np(V) with humic acid and polyacrylic acid
- Investigation of humic acid complexation behavior with uranyl ions using modified synthetic and natural humic acids
- Solution coordination chemistry of uranium in the binary UO22+-SO42- and the ternary UO22+-SO42--OH- system
- The speciation of Tc(IV) in chloride solutions
- The hydrolysis of uranium(VI) in sulfate media
- Complex formation of Eu(III) with polyacrylic acid
- Determination of Co(II) and Ni(II)-humate stability constants at high ionic strength NaCl solutions
- Analysis of Th(IV)-humate by XPS
- EXAFS structural analysis of aqueous uranium(VI) complexes with lignin degradation products
- Thermodynamic modeling of metal-ligand interactions in high ionic strength NaCl solutions: the Co2+-oxalate system
- Mixed Ca2+/UO22+/CO32- complex formation at different ionic strengths
- Humic colloid-borne Np migration: influence of the oxidation state
- Reduction of Pu(V) by humic acid
- Colloid-borne uranium and other heavy metals in the water of a mine drainage gallery
- Application of LIBD to the determination of the solubility product of thorium(IV)-colloids
- The Rossendorf Beam Line ROBL – a dedicated experimental station for XAFS measurements of actinides and other radionuclides
- Extended X-ray absorption fine structure and time differential perturbed angular correlation study of hafnium(IV) sorbed onto amorphous silica
- Speciation analysis on europium(III) using laser-induced breakdown spectroscopy
- The migration behavior of Np(V) in sandy soil and granite media in the presence of humic substances
- Uranium(VI) and neptunium(V) transport through fractured, hydrothermally altered concrete
- Experimental study and modeling of uranium (VI) transport through ferrous olivine rock columns
- Aqueous Pu(IV) sorption on brucite
- Surface spectroscopic studies of Cs+, and Ba2+ sorption on chlorite-illite mixed clay
- Approaches to modelling uranium(VI) adsorption on natural mineral assemblages
- Evaluation of radioactive nickel distribution coefficient by analyzing background stable nickel
- Application of electrokinetic data to test the adsorption models
- Sorption equilibrium and kinetics of NpO2+ on dispersed particles of Na-montmorillonite
- Sorption of Am(III) and Eu(III) onto γ-alumina: experiment and modelling
- Effects of humic acid on the sorption of Am(III) and Cm(III) on kaolinite
- Uranium(VI) sorption onto phyllite and selected minerals in the presence of humic acid
- The partitioning of uranium and neptunium onto hydrothermally altered concrete
- Alteration products of uraninite from the Colorado Plateau
- Fracture-filling minerals as uranium sinks and sources, a natural analogue study at Palmottu, Finland
- Spectroscopic properties of uranium(VI) minerals studied by time-resolved laser-induced fluorescence spectroscopy (TRLFS)
- Fracture smectite as a long-term sink for natural radionuclides – indications from unusual U-series disequilibria
- The potential of subterranean microbes in facilitating actinide migration at the Grimsel Test Site and Waste Isolation Pilot Plant
- Application of gel electrophoretic techniques to the investigation of actinide-humic interactions in soils
- Applications of NAA, PIXE and XPS for the quantification and characterization of the humic substances/iodine association
- Quantitative assessment of radiocaesium bioavailability in forest soils
- Actinide partitioning to an acidic, sandy lake sediment
- Adsorption of Cs and U(VI) on soils of the Australian arid zone
- Natural and artificial radionuclides in forest and bog soils: Tracers for migration processes and soil development
- Distribution of natural radionuclides during the processing of phosphate rock from Itataia-Brazil for production of phosphoric acid and uranium concentrate
- An electrostatic approach for the prediction of actinide complexation constants with inorganic ligands-application to carbonate complexes
- Determination and uncertainties of radioelement solubility limits to be used by SKB in the SR 97’ performance assessment exercise
