The use of µCT and ESEM in the study of the osmosis-induced water uptake by Eurobitum bituminized radioactive waste

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Abstract

Laboratory water uptake tests are performed at the SCK•CEN to obtain insight into the hydromechanical behavior of Eurobitum bituminized radioactive waste under geological disposal conditions. Small nonradioactive and radioactive Eurobitum samples are hydrated in restricted swelling conditions (i.e. nearly constant volume conditions and constant stress conditions). Microfocus X-ray Computer Tomography (µCT) proves to be a very suitable technique to follow up the ingress of water in the samples. µCT analyses demonstrate that, under the studied hydration conditions, the water uptake by Eurobitum samples is a diffusion controlled process. A characterization of the partially leached samples with Environmental Scanning Electron Microscopy (ESEM) shows that the hydration of salt crystals and the subsequent dilution of the salt solution result in an increase in pore size that is limited to a few tens of µm in restricted swelling conditions. The µCT and ESEM analyses allow improvement in the understanding of water uptake by Eurobitum in restricted swelling conditions. In this article we discuss the µCT and ESEM analyses of nonradioactive Eurobitum samples that were hydrated for 2 to 4 years at a constant stress of 1, 22, 33, and 44 bar or in nearly constant volume conditions.

Details

Original languageEnglish
Pages (from-to)1163-1180
JournalMicroscopy and Microanalysis
Volume18
Issue number05
DOIs
Publication statusPublished - Oct 2012

Keywords

  • Eurobitum bituminized radioactive waste, osmosis, NaNO3, water uptake, microfocus X-ray Computer Tomography, Environmental Scanning Electron Microscopy

ID: 82031