Osmosis-induced swelling of Eurobitum bituminized radioactive waste in constant total stress conditions

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Abstract

In geological disposal conditions, contact of Eurobitum bituminized radioactive waste, which contains high amounts of the hygroscopic and highly soluble NaNO3, with groundwater will result in water uptake and swelling of the waste, and in subsequent leaching of the embedded NaNO3 and radionuclides. The swelling of and the NaNO3 leaching from non-radioactive Eurobitum samples, comprized between two stainless steel filters and in contact with 0.1 M KOH, was studied in restricted (semi-confined) swelling conditions, i.e. under a constant total stress, or counterpressure, of 2.2, 3.3, or 4.4 MPa (i.e. oedometer conditions). Four tests were stopped after hydration times between 800 and 1500 days, and the samples were analyzed by micro-focus X-ray Computer Tomography (µCT) and by Environmental Scanning Electron Microscopy (ESEM). The complete set of data enabled a consistent interpretation of the observations and lead to an improved understanding of the phenomenology of the water uptake, swelling, and NaNO3 leaching in restricted swelling conditions.

Details

Original languageEnglish
Pages (from-to)304-316
JournalJournal of Nuclear Materials
Volume406
Issue number3
DOIs
Publication statusPublished - Nov 2010

Keywords

  • Eurobitum, bituminized radioactive waste, intermediate level radioactive waste, osmosis, swelling, pressure increase, NaNO3, NaNO3 leaching, Boom Clay, geological disposal

ID: 251003