Water corrosion and release mechanism of cement matrix incorporating simulated medium-level waste
Previous works on cement leached in water and containing radioactive wastes like cesium and strontium agree to attribute the release in the liquid phase to a diffusion mechanism. The kinetic release can be represented by an empirical relationship in which the dependence of the leached fraction Fr = C/C/sub o/ versus time t assumes the form Fr = Bt/sup n/ and the factor n = 0.5 is typical of a diffusion process. On the other hand, the results of the authors' studies on cement leached in static water demonstrate that the release of calcium, considered to be representative of matrix degradation, follows a time dependence of t/sup 0.25/. A model is suggested for which the release of calcium depends on superposition of two processes: a diffusion through a reaction layer of calcium silicate hydrate around the cement particles during the hydration step and a diffusion of elements from the bulk of cement toward the external surface of the specimen. Based on this schematic diffusion mechanism, some suggestions are advanced to improve the physical characteristics and to increase the retention of the radioactive waste encapsulated in the cement matrix.
- Research Organization:
- Commission of the European Communities, Joint Research Centre-Ispra Establishment, 21020 Ispra (Va) (IT)
- OSTI ID:
- 5321114
- Journal Information:
- Nucl. Technol.; (United States), Journal Name: Nucl. Technol.; (United States) Vol. 77:3; ISSN NUTYB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
510300 -- Environment
Terrestrial-- Radioactive Materials Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
BUILDING MATERIALS
CALCIUM
CALCIUM COMPOUNDS
CALCIUM SILICATES
CEMENTS
CESIUM
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CORROSION
CORROSIVE EFFECTS
DIFFUSION
DISSOLUTION
ECOLOGICAL CONCENTRATION
ELEMENTS
ENCAPSULATION
ENVIRONMENTAL TRANSPORT
GROUND WATER
HYDRATES
HYDROGEN COMPOUNDS
INTERMEDIATE-LEVEL RADIOACTIVE WASTES
KINETICS
LEACHING
MANAGEMENT
MASS TRANSFER
MATERIALS
MATHEMATICAL MODELS
METALS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PROCESSING
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE PROCESSING
RADIOACTIVE WASTES
RADIOECOLOGICAL CONCENTRATION
RADIONUCLIDE MIGRATION
REACTION KINETICS
SEPARATION PROCESSES
SILICATES
SILICON COMPOUNDS
STRONTIUM
UNDERGROUND DISPOSAL
WASTE DISPOSAL
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
WATER
YIELDS