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|Title:||Characterization of the Penetration Mechanisms of Water Into Polycrystalline UO2|
|Authors:||MARCHETTI Ilaria; BELLONI Fabio; HIMBERT Jerome; CARBOL Paul; FANGHAENEL Thomas|
|Citation:||Proceedings of the 2010 MRS Spring Meeting vol. 1265 p. 1-6|
|Publisher:||Materials Research Society|
|Type:||Articles in periodicals and books|
|Abstract:||Following containment failure in the scenario of geological disposal of spent nuclear fuel, the penetration rate of groundwater into the UO2 matrix could cause a rapid increase of the fraction of inventory becoming available for prompt dissolution. In this respect, oxygen and water diffusion mechanisms are key issues to investigate. In this work, secondary-ion-mass-spectrometry (SIMS) depth profiling has been applied to characterize a polycrystalline UO2 pellet exposed to 18O-labelled water at room temperature. 18O depth profiling up to 25 µm beneath the pellet surface clearly indicates a combination of oxygen diffusion into the UO2 lattice and water diffusion along grain boundaries, behaving as high diffusivity paths. The lattice diffusion coefficient of oxygen, DL, and the quantity dDB ¿ product of the grain boundary width, d, and the grain boundary diffusion coefficient of water, DB ¿ have been measured, resulting in DL = (2.5 ± 0.1) *10-24 m2 s-1 and dDB = (7.5 ± 0.3) *10-24 m3 s-1.|
|JRC Directorate:||Nuclear Safety and Security|
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