Objective
BOROSILICATE GLASSES ARE PROPOSED AS WASTE FORM FOR THE FINAL DISPOSAL OF HIGH LEVEL WASTE (HLW) BY THE FEDERAL REPUBLIC OF GERMANY. BETWEEN 1980 AND 1985 EXTENSIVE STUDIES ON THE CORROSION MECHANISMS OF THE INACTIVE HLW GLASS TYPE SM 58 IN A SALT BRINE WERE PERFORMED BY THE CONTRACTOR (CONTRACT NOS. WAS-232-81-53 D (B) AND WAS-323-83-53 D (B)). IN 1988 THE LONG TIME CORROSION TESTS WITH THE HLW GLASS SM 58 WERE FINISHED (TEST DURATIONS UP TO 5 YEARS IN SOLUTION 1 (TABLE II) AT TEMPERATURES UP TO 200 CELSIUS DEGREES /1/); A SHORT SUMMARY OF THESE RESULTS IS INCLUDED IN THIS REPORT.
A THEORETICAL STUDY /2/ ON REPORTED CORROSION DATA (FOR DIFFERENT GLASSES AND DIFFERENT CORROSION CONDITIONS) SHOWED THAT MOST HLW GLASSES CORRODE ACCORDING TO A VERY SIMILAR PATTERN. THE MAIN MECHANIMS ARE:
- NETWORK DISSOLUTION,
- FORMATION OF REACTION PRODUCT LAYERS ON TOP OF THE GLASS, AND
- ION EXCHANGE.
THE FOLLOWING MODEL WAS DEVELOPED FROM THESE RESULTS: IN FRESH LEACHANTS THE CORROSION STARTS WITH AN INITIAL RATE R0 LINEARLY DEPENDING ON T. DUE TO THE ACCUMULATION OF REACTION PRODUCTS IN THE LEACHATE, THIS INITIAL RATE SLOWS DOWN AND REACHES FINALLY A LONG TERM RATE R00, WHICH IS TYPICAL OF CORROSION IN LEACHATES SATURATED WITH RESPECT TO SILICA. THE RATE R00 SHOULD DEPEND LINEARLY ON T.
AT THE START OF THE INVESTIGATIONS PRESENTED HERE, ONLY FEW DATA WERE AVAILABLE FOR THIS LONG TERM CORROSION OF HLW GLASS IN SALT SOLUTIONS. THEREFORE, THE CORROSION OF THE HLW GLASS TYPE SON 68 (OR R7T7)IN SALT BRINES WAS INVESTIGATED UNDER THE CONDITIONS OF SILICA SATURATION. SILICA SATURATION WAS ACHIEVED IN THE LABORATORY BY ENLARGING THE RATIO OF SAMPLE SURFACE AREA TO SOLUTION VOLUME (S/V). THE INTEREST WAS FOCUSED ON THE COMPOSITION OF THE SURFACE OF THE RESIDUAL GLASS AS WELL AS ON THE COMPOSITION OF THE LEACHATE AND ON THE INVESTIGATION OF THEIR INFLUENCES ON THE CORROSION PROCESS. THE CORROSION TESTS WERE PERFORMED IN COOPERATION WITH THE HAHN-MEITNER-INSTITUT (HMI), BERLIN.
A theoretical study, based on a broad set of corrosion data with different glasses and different corroding agents, showed that all high level waste (HLW) glasses corrode according to very similar patterns.
The main mechanisms can be summarised as follows:
the glass is submitted to a network dissolution process responsible for almost the whole corrosion process;
as long as an accumulation of reaction products in the solution is avoided, the network dissolution rate has an intital value r-0 which is a function of the individual glass composition and of the activities of the corresponding species in solution;
the dissolution rate slows down with increasing amounts of accumulated reaction products and finally reaches a long term rate r;
reaction products (eventually involving components of the attacking solution) form layers on top of the residual glass;
the reaction product layers in many cases act as transport barriers and reduce further corrosion attack;
the surface zone of the residual glass is altered by ion exchange processes.
A theorectical study based on a broad set of corrosion data with different glasses and different corroding agents shows that all high level radioactive wastes (HLW) glasses corrode according to very similar patterns. The main mechanisms can be summarized as follows:
(i) the glass is submitted to a network dissolution process responsible for almost the total corrosion progress;
(ii) as long as an accumulation of reaction products in the solution is avoided, the network dissolution rate has an initial value which is a function of the individual glass composition and of the activities of the corresponding species in solution;
(iii) the dissolution rate slows down with increasing amounts of accumulated reaction products and finally reaches a long term rate;
(iv) reaction products (eventually involving components of the attacking solution) form layers on top of the residual glass;
(v) the reaction products layers in many cases act as transport barriers and reduce a further corrosion attack;
(vi) the surface zone of the residual glass is altered by ion exchange processes.
B.1. CORROSION PRE-TESTS FOR THE OPTIMIZATION OF ANALYTICAL TECHNIQUES.
B.2. SUPPLEMENTARY CORROSION TESTS.
B.3. OPTIMIZATION OF ANALYTICAL TECHNIQUES (PHOTOELECTRON SPECTROSCOPY (XPS), ACID ETCHING).
B.4. OPTIMIZATION OF PREPARING METHODS.
B.5. PREPARATION AND MEASUREMENT OF STANDARD SAMPLES WITH XPS.
B.6. SURFACE ANALYSIS OF CORRODED GLASS SAMPLES.
B.7. PREPARATION AND SAMPLING OF SATURATED LEACHATES AT TEST TEMPERATURE WITH SUBSEQUENT CHEMICAL ANALYSIS.
B.8. EVALUATION OF TEST RESULTS.
Fields of science (EuroSciVoc)
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
- engineering and technology other engineering and technologies nuclear engineering nuclear waste management
- engineering and technology materials engineering amorphous solids inorganic amorphous solids
- natural sciences physical sciences optics spectroscopy
You need to log in or register to use this function
Programme(s)
Multi-annual funding programmes that define the EU’s priorities for research and innovation.
Multi-annual funding programmes that define the EU’s priorities for research and innovation.
Topic(s)
Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.
Data not available
Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.
Call for proposal
Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.
Data not available
Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.
Funding Scheme
Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.
Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.
Coordinator
76139 Karlsruhe
Germany
The total costs incurred by this organisation to participate in the project, including direct and indirect costs. This amount is a subset of the overall project budget.