BEHAVIORS OF MOLYBDENUM IN UO<sub>2</sub>FUEL MATRIX

Ha, Yeong-Keong; Kim, Jong-Goo; Park, Yang-Soon; Park, Soon-Dal; Song, Kiwon

doi:10.5516/net.2011.43.3.309

Cited by 12 publications

(2 citation statements)

References 16 publications

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“…They attributed the presence of Mo(+IV) to the fact that their samples were slightly hyper-stoichiometric. In contrast, Ha et al showed that in Mo mixed UO 2 pellets (containing 1–15 atom % of Mo) sintered in a reducing atmosphere Mo atoms cluster together to form Mo-rich regions in a solid solution. A clear formation of metallic clusters was observed for Mo concentrations higher than 4 atom %.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Sarrasin¹,

Gaillard²,

Panetier³

et al. 2019

Inorg. Chem.

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Molybdenum is an abundant element produced by fission in the nuclear fuel UO2 in a pressurized water reactor. Although its radiotoxicity is low, this element has a key role on the fuel oxidation and other fission products migration, in particular in the case of an accidental scenario. This study aims to characterize the behavior of molybdenum in uranium dioxide as a function of environmental conditions (oxygen partial pressure, high temperature, UO2 oxidation) typical of an accidental scenario. To do so, molybdenum was introduced in UO2 or UO2+x pellets by ion implantation, a technique that allows us to mimic the production of Mo in the nuclear fuel by fission. Then, thermal treatments at high temperature and different oxygen partial pressures were carried out. The mobility of Mo in UOX samples was followed by secondary ion mass spectrometry (SIMS), while the Mo chemical speciation was investigated by spectroscopic techniques (XANES, Raman). In parallel, ab initio calculations were performed showing the effect of interstitial oxygen atoms on the Mo incorporation sites in UO2. We show that the Mo mobility is directly connected to its chemical state, which in turn, is linked to the redox conditions. Indeed, under reducing atmosphere, Mo is present in UO2 or UO2+x samples under a metallic state Mo(0). Its mobility, being quite low, is driven by a diffusion mechanism. An increase of pO2 entails the UO2 and Mo oxidation and, as a consequence, a strong release of this element. We show an increase of the Mo release rate with the increase of the UO2+x hyper-stoichiometry x. After thermal treatment, Mo remaining in the samples is located in the grains under the MoO2 form. Our experimental results are assessed by ab initio calculations showing that in the presence of oxygen Mo atoms adopt in UO2 a local structure close to the octahedral local geometry of Mo oxides.

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Section: Introductionmentioning

confidence: 99%

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Sarrasin¹,

Gaillard²,

Panetier³

et al. 2019

Inorg. Chem.

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“…These in turn destabilize the glass and increase the rate of corrosion and leaching of other radionuclides. Ceramic-glasses are an alternative waste form in which a source of calcium is added to the borosilicate vitrification process to precipitate powellite, CaMoO 4 , and thereby increase the molybdenum fixing capacity of the waste form. − …”

Section: Introductionmentioning

confidence: 99%

Structural and Morphological Influences on Neptunium Incorporation in Uranyl Molybdates

Meredith

Sigmon

Simonetti

et al. 2015

Crystal Growth & Design

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The in situ incorporation of pentavalent neptunium has been studied in the structurally related uranyl molybdate frameworks (NH 4 ) 4 [(UO 2 ) 5 (MoO 4 ) 7 ](H 2 O) 5 and (NH 4 ) 2 [(UO 2 ) 6 (MoO 4 ) 7 ](H 2 O) 2 prepared under similar synthetic conditions. The presence of Np(V) was confirmed by UV-vis-NIR spectroscopy in the first compound whereas Np(VI) was identified in the second based on the observation of a unit cell contraction and the lack of a spectral signature for Np(V). The incorporation of neptunium does not affect the overall structure of the host compound based on the crystallographic unit cell parameters. Neptunium appears to preferentially incorporate in the structure of (NH 4 ) 2 [(UO 2 ) 6 (MoO 4 ) 7 ](H 2 O) 2 due to the formation of Np(VI) during synthesis, although higher total uptakes were observed in (NH 4 ) 4 [(UO 2 ) 5 (MoO 4 ) 7 ](H 2 O) 5 due to a higher initial concentration of neptunium in solution despite maintaining the same ratio of U:Np.

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Thermodynamic investigations of the uranium-molybdenum-oxygen system by a coupling of density functional theory and CALPHAD methodologies

Corcoran

Flèche

Dupin

et al. 2018

Calphad

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BEHAVIORS OF MOLYBDENUM IN UO₂FUEL MATRIX

Cited by 12 publications

References 16 publications

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Structural and Morphological Influences on Neptunium Incorporation in Uranyl Molybdates

Thermodynamic investigations of the uranium-molybdenum-oxygen system by a coupling of density functional theory and CALPHAD methodologies

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BEHAVIORS OF MOLYBDENUM IN UO2FUEL MATRIX

Cited by 12 publications

References 16 publications

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO2 and UO2+x

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO2 and UO2+x

Structural and Morphological Influences on Neptunium Incorporation in Uranyl Molybdates

Thermodynamic investigations of the uranium-molybdenum-oxygen system by a coupling of density functional theory and CALPHAD methodologies

Contact Info

Product

Resources

About

BEHAVIORS OF MOLYBDENUM IN UO₂FUEL MATRIX

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO₂ and UO_2+x