Corrosion and dissolution studies of UO2 containing α-emitters
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J. Cobos
, L. Havela , V.V. Rondinella , Joan de Pablo , T. Gouder , J.-P. Glatz , P. Carbol and Hj. Matzke
Summary
Corrosion and dissolution of UO2 doped with short-lived α-emitters, the so called α-doped UO2, was investigated in leaching experiments combined with X-ray Photoelectron Spectroscopy (XPS) analyses. These experiments are part of an ongoing set of tests aiming at evaluating the effects of α-radiolysis on the dissolution of the UO2 spent fuel matrix when it will become exposed to groundwater in a deep final repository. Pellets of UO2 containing ∼10 and ∼0.1 wt.% 238Pu were used. These compositions simulate the α-radiation field of different types of commercial LWR spent fuel after different storage times. Undoped UO2 pellets were also used as reference. Static sequential leaching experiments in demineralised water at room temperature under anoxic conditions confirmed that higher fractions of uranium are released in the case of α-doped materials compared with undoped UO2. Relatively large amounts of plutonium were found in the leachate of the materials doped with 238Pu. Significant contributions to the total amount released of uranium were found in the rinse solutions of the leaching vessels. The evolution of the U(VI)/U(IV) ratio on the leached surfaces as a function of contact time was studied by deconvolution of the 4f7/2 uranium peak obtained from the XPS spectra. In the case of undoped UO2, after ∼1000 h of leaching the increase of the U(VI)/U(IV) ratio stabilized to a level corresponding to ∼UO2.33. The XPS results for both α-doped materials showed a continuing increase of the U(VI) fraction on the surface with increasing leaching times after the first ∼10 h. The rate of increase depended on the α-activity of the fuel sample, hence on the amount of radiolysis in the water. After ∼1000 h of leaching, essentially only U(VI) was detected on the surface of the high activity α-doped UO2. The presence of a yellowish layer of reprecipitated U(VI) phases covering the surface could be observed optically already after ∼100 h of leaching.
© Oldenbourg Wissenschaftsverlag, München
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Articles in the same Issue
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- Thermodynamics of the U(VI)-Ca2+-Cl −-OH −-H2O system: Solubility product of becquerelite
- Control of plutonium dioxide solubility by amorphous tetrahydroxide: A critical review of the model
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- Uranium release from boom clay in bicarbonate media
- Coprecipitation of thorium with UO2
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- Sorption behaviour of Am on precorroded HLW glass in water and brines
- Molecular fluorescence spectroscopy and mixture analysis for the evaluation of the complexation between humic acid and UO22+
- Investigation on uranyl interaction with bioactive ligands. Synthesis and structural studies of the uranyl complexes with glycine and N-(2-mercaptopropionyl)glycine
- Complex formation of calcium with humic acid and polyacrylic acid
- Complexation of americium with humic, fulvic and citric acids at high ionic strength
- Complex formation of Eu(III) with humic acid and polyacrylic acid
- XAS study of technetium(IV) polymer formation in mixed sulphate/chloride media
- Complexation of uranium(VI) with malonate at variable temperatures
- The hydrolysis of uranium(VI)
- Corrosion and dissolution studies of UO2 containing α-emitters
- The effects of alpha-radiolysis on UO2 dissolution determined from electrochemical experiments with 238Pu-doped UO2
- Radiolytic formation of Tc(IV) oxide colloids
- Radiation-chemical effects in the near-field of a final disposal site: role of bromine on the radiolytic processes in NaCl-solutions
- The reduction of U(VI) on corroded iron under anoxic conditions
- New selenium solution speciation method by ion chromatography + gamma counting and its application to FeS2-controlled reducing conditions
- Uptake of oxo-anions by cements through solid-solution formation: experimental evidence and modelling
- Iodine species uptake by cement and CSH studied by I K-edge X-ray absorption spectroscopy
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- Uptake mechanism of IO3− to NO3−-hydrotalcite
- Structure alteration of C-S-H (calcium silicate hydrated phases) caused by sorption of caesium
- The effect of α-isosaccharinic acid on the stability of and Th(IV) uptake by hardened cement paste
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- Spectroscopic studies on the interaction of U(VI) with Bacillus sphaericus
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