Title: Characterization of the Penetration Mechanisms of Water Into Polycrystalline UO2
Citation: Proceedings of the 2010 MRS Spring Meeting vol. 1265 p. 1-6
Publisher: Materials Research Society
Publication Year: 2010
JRC N°: JRC57872
URI: http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=26169&DID=319078
DOI: 10.1557/PROC-1265-AA05-06-Z07-06
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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