Coupled modeling of cement/claystone interactions and radionuclide migration

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doi: 10.1016/S0169-7722(03)00148-7
Authors:De Windt, L.; Pellegrini, D.; van der Lee, J.
Author Affiliations:Primary:
Ecole des Mines de Paris, Centre d'Informatique Géologique, Fontainebleau, France
Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France
Volume Title:Journal of Contaminant Hydrology
Source:Journal of Contaminant Hydrology, 68(3-4), p.165-182. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0169-7722
Publication Date:2004
Note:In English. 38 refs.; illus., incl. 4 tables
Summary:The interactions between cement and a clayey host-rock of an underground repository for intermediate-level radioactive waste are studied with the reactive transport code HYTEC for supporting performance assessment. Care is taken in using relevant time scales (100,000 years) and dimensions. Based on a literature review, three hypotheses are considered with respect to the mineralogical composition of the claystone and the neo-formed phases. In the long term, the pH is buffered for all hypotheses and important mineral transformations occur both in cement and the host-rock. The destruction of the primary minerals is localized close to the cement/claystone interface and is characterized by the precipitation of secondary phases with retention properties (illite, zeolite). However, beyond the zone of intense mineral transformations, the pore water chemistry is also disturbed over a dozen meters due to an attenuated but continuous flux of hydroxyl, potassium and calcium ions. Four interdependent mechanisms control the profile in the whole system: diffusion of the alkaline plume, mineralogical buffering, ion exchange and clogging of the pore space at the cement/claystone interface. The migration of a selected group of radionuclides (Cs, Ra, Tc and U) is explicitly integrated in the simulations of the strongly coupled system. Theoretical profiles of distribution coefficient (Kd) and solubility limit values are derived from the simulations, and their sensitivity with respect to the system evolution is estimated. Abstract Copyright (2004) Elsevier, B.V.
Subjects:Actinides; Alkali metals; Alkaline earth metals; Aquifers; Buffers; Cement; Cesium; Clastic rocks; Clastic sediments; Clay minerals; Claystone; Controls; Destruction; Host rocks; Interfaces; Ion exchange; Isotopes; Metals; Migration of elements; Mobility; Models; Oxides; Physical properties; Pollution; Pore water; Portlandite; Radioactive isotopes; Radioactive waste; Radium; Reactive transport; Retention; Sedimentary rocks; Sediments; Sheet silicates; Silicates; Simulation; Solubility; Thermodynamic properties; Transformations; Underground disposal; Uranium; Waste disposal
Record ID:2004052954
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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