Objective 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. Programme(s) EAEC-NFS 2 - Specific research and training programme in the field of nuclear safety and safeguards, 1994-1998 Topic(s) 030302 - Characterization of waste forms and matrices Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator Commissariat à l'Energie Atomique EU contribution No data Address Ctr Etudes Vallée du Rhône - CE-VALRHO 30205 Bagnols-sur-Cèze France See on map Total cost No data Participants (4) Sort alphabetically Sort by EU Contribution Expand all Collapse all BELGIAN NUCLEAR RESEARCH CENTRE Belgium EU contribution No data Address 200,Boeretang 200 2400 MOL See on map Total cost No data FORSCHUNGSZENTRUM KARLSRUHE GMBH - TECHNIK UND UMWELT Germany EU contribution No data Address Herrmann-von-Helmholtz-Platz 1 76344 EGGENSTEIN-LEOPOLDSHAFEN See on map Total cost No data Organisme National des Déchets Radioactifs et des Matières Fissiles enrichies Belgium EU contribution No data Address 1,Place Madou - Boites 24/25 1030 Bruxelles See on map Total cost No data Paul Scherrer Institut Switzerland EU contribution No data Address 5232 Villigen See on map Total cost No data