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CHARACTERIZATION OF CLAY (BENTONITE) CRUSHED GRANITE MIXTURES TO BUILD BARRIERS AGAINST THE MIGRATION OF RADIONUCLIDES: DIFFUSION STUDIES AND PHYSICAL PROPERTIES.

Objective

THE OBJECTIVE OF THIS RESEARCH WORK IS THE ANALYSIS OF THE PHYSICAL AND CHEMICAL-PHYSICAL CHARACTERISTICS OF THE SPANISH MATERIALS CAPABLE OF BECOMING ENGINEERED BARRIERS FOR THE ISOLATION OF RADIOACTIVE WASTES.

IT HAS BEEN DECIDED TO ANALIZE THE BEHAVIOUR OF COMPACTED BLOCKS MADE OF A MIXTURE OF CLAYS (BENTONITE) AND CRUSHED GRANITE, IN ORDER TO DIMINISH THE INTERACTION BETWEEN THE SEALING MATERIALS AND THE HOST ROCK.

THE COMMUNITARIAN AND SCIENTIFIC-TECHNICAL INTEREST MAY REST UPON A BETTER KNOWLEDGE OF THE BEHAVIOUR OF ARTIFICIAL BARRIERS IN THE GRADIENT FIELDS EXPECTED AFTER THE CONFINEMENT OF WASTES IN GRANITIC ROCKS, AND ALSO UPON THE FEASIBILITY OF USING THE ARGILLACEOUS MATERIALS AVAILABLE IN SPAIN.

THESE STUDIES MUST LEAD TO OBTAIN A SEALING MATERIAL THAT WOULD CREATE THE SMALLEST DISEQUILIBRIUM IN THE INTERFACE HOST ROCK/BARRIER.
In Spain the possibility of storing radioactive waste in granitic rocks is being considered, using Spanish clays as backfill and sealing materials. The study and selection of these materials is the objective of the work. With the aim of minimising the chemical mineralogical disequilibrium between the granitic rock and the artificial barrier, the possibility has been studied of using molten granite as an additive and illite as a clay type material, instead of the normal use of smectite (montmorillonite).
Studies have been done with 30 commercial Spanish clays and 2 kinds of granites and have been oriented to the selection of materials and the optimisation of the clay granite mixtures, chemical characterisation, mechanics and physics of the mixtures and compacted blocks, determination of their behaviour in the gradient fields of temperature, pressure and chemical potentials, and to the determination of the migration parameters.

In Spain, the possibility of storing radioactive waste in granitic rocks, using Spanish clays as backfill and sealing materials, is being considered. With the aim of minimizing the chemicomineralogical disequilibrium between the granitic rock and the artificial barrier, the possibility of using molten granite as an additive and illite as clayish material has been studied, instead of the normal use of smectite (montmorillonite).

The studies have been carried out on 30 commercial Spanish clays and 2 kinds of granite. They have concentrated on the selection of materials and the optimization of the clay granite mixtures, chemical characterization, mechanics and physics of the mixtures and compacted blocks, determination of their behaviour in the gradient fields of temperature, pressure and chemical potentials and the determination of the migration parameters.
CHARACTERIZATION OF THE MATERIALS USED:

- QUANTITATIVE MINERALOGICAL COMPOSITION AND SPECIFIC WEIGHT.
- CHEMICAL COMPOSITION.
- LIQUID AND PLASTIC LIMITS, RETRACTION INDEX.
- GRANULOMETRY.
- SPECIFIC AREA. CATION EXCHANGE

CHARACTERIZATION OF THE COMPACTED BLOCKS.

- ANALYSIS OF THE INFLUENCE OF GRANULOMETRY, PRESSURE AND SATURATION DEGREE ON THE COMPACTATION AND PERMEABILITY OF THE COMPACTED BLOCKS.
- ANALYSIS OF HYDRATATION PRESSURE IN A CLOSED AND OPENED SYSTEM

ANALYSIS OF THE CHANGES IN VOLUME, DIAMETER AND AREA OF THE COMMUNICATING PORES IN THE COMPACTED BLOCKS, AS A FUNCTION OF PRESSURE AND OF THE COMPACTATION METHODS.

ANALYSIS OF THE VARIATION OF THE MICROFISSURAL FIELD AS A FUNCTION OF TEMPERATURE (O - 200 CELSIUS DEGREES) AND ENVIRONMENTAL SATURATION HUMIDITY. THE MEASUREMENTS WILL BE DONE BY THERMIC OSCILLATION AT DIFFERENT SPEEDS.

ANALYSIS OF THE DIFFUSIBILITY OF THE SOLUTIONS IN THE COMPACTED BLOCKS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

CENTRO DE INVESTIGACIONES ENERGETICAS, MEDIAMBIENTALES Y TECNOLOGICAS
Address
22,Avenida Complutense 22
28040 Madrid
Spain