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Experimental and modelling studies to formulate a source term of nuclear waste glass in representative geological storage conditions

Ziel



The project comprises four research domains to be investigated simultaneously. The first domain consists in compiling a computerized data base of experimental data acquired to date in the partners' laboratories relating to the leaching of nonradioactive and radioactive R7T7 glass. The resulting data base will constitute a coherent source for qualifying long-term glass behavior models.
The second domain covers the definition of the glass corrosion kinetics, notably under conditions representative of long-term geological disposal. Long-term glass corrosion kinetics are currently based on an empirical concept (silica solubility) and on mechanistic hypotheses (control by water diffusion, Si diffusion in the alteration films, Si adsorption), and must be elucidated to provide a better quantitative description of the phenomena involved. Glass interactions with metal canister corrosion products and repository environmental materials also affect the glass corrosion kinetics - possibly to the point of controlling them. Leaching experiments with nonradioactive glass specimens will b e conducted: (1) to measure the effects of elements other than silica on controlling the dissolution kinetics and on glass solubility, (2) to identify the chemical bonds at the glass surface controlling the corrosion reaction, and (3) to measure the diffusion/interdiffusion coefficients in the alteration film and the reaction zone.
The third objective is to quantify the behavior of radionuclides with major effects on longterm safety during corrosion of the glass matrix. The chemical distribution of the species according to the nature of the leaching solution, nearfield and environmental materials (clays, salts, metal corrosion products) will be determined. Radionuclide sorption phenomena, coprecipitation and colloid formation will be quantified. Experiments will be conducted with nonradioactive and radioactive glass specimens (containing notably technetium and actinide elements). The alteration products (gels) containing actinides (U, Pu, Np, Am) will be synthesized and characterized, and their radiation stability will be assessed .
The fourth research area consists in modeling alteration phenomena both for explanatory purposes and to permit long-term extrapolation and performance assessments of the lifetime of the glass package and source term. This task will implement enhanced geochemical codes (EQ3/6, K
(Monte Carlo, GLADIS) with data common to all the partners. The objective will be to allow for the corrosion reaction progress, to describe the glass matrix corrosion kinetics and to specify the behavior of the major glass elements and radionuclides (precipitation, sorption, coprecipitation) for specific disposal environments. The data base (the first research domain) will provide the parameters for predictive modeling.

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Finanzierungsplan

CSC - Cost-sharing contracts

Koordinator

Commissariat à l'Energie Atomique
EU-Beitrag
Keine Daten
Adresse
Ctr Etudes Vallée du Rhône - CE-VALRHO
30205 Bagnols-sur-Cèze
Frankreich

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Beteiligte (4)

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Letzte Aktualisierung: 2 April 1996

Mein Booklet

Permalink: https://cordis.europa.eu/project/id/FI4W950001/de

European Union, 2024