Deep disposal of EUROBITUM bituminised waste: scoping calculations of nitrate release

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Abstract

The Eurobitum bituminised waste product from the former EUROCHEMIC reprocessing plant in Mol-Dessel (Belgium) contains a lot of salts, mainly NaNO3. This NaNO3 may possibly affect the repository's integrity through redox and ion exchange reactions with Boom Clay, which in Belgium is studied as a reference host rock. The leaching behaviour of NaNO3 from the Eurobitum and its migration in the Boom Clay is rather unclear. Simplified numerical calculations have been performed. First, we calculated the water flux towards the disposal gallery to assess the timescale of the saturation process of the disposal galleries. Then, the leaching rate of NaNO3 out of the drums was compared with its diffusive removal through the clay. Different NaNO3 source term models were used in the calculations. For a previously assessed leaching rate of 1 mm/year, the calculations show that the NaNO3 concentrations in the first decimetres of Boom Clay will not be much higher than 1 M. A sensitivity analysis showed that if the nitrate release from the BWP takes 100 to 10 000 years, the Boom Clay controls the concentration profiles. If the release is slower, the source term has a more pronounced effect on the near field concentrations.

Details

Original languageEnglish
Title of host publicationSymposium Proceedings. Scientific Basis for Nuclear Waste Management XXIX
Place of PublicationWarrendale, United States
Pages735-742
Publication statusPublished - Jun 2006
EventMRS 2005. 29th International Symposium on the Scientific Basis for Nuclear Waste Management - SCK•CEN, Gent, Belgium
Duration: 12 Sep 200516 Sep 2005

Conference

ConferenceMRS 2005. 29th International Symposium on the Scientific Basis for Nuclear Waste Management
CountryBelgium
CityGent
Period2005-09-122005-09-16

Keywords

  • bitumens, nitrate, simulation, flow models, Radioactive waste disposal, Boom Clay, leaching, diffusion

ID: 314905