TESTING OF THE ALTERATION OF WASTE GLASSES UNDER GEOLOGICAL STORAGE CONDITIONS

Cel

A LARGE NUMBER OF PARAMETERS MUST BE TAKEN INTO ACCOUNT TO PREDICT GLASS ALTERATION BEHAVIOUR IN A GEOLOGICAL REPOSITORY: FLOW RATE, TEMPERATURE, PRESSURE, PH, EH, CO2 CONTENT, RADIOLYSIS, WATER COMPOSITION, NATURE OF THE SURROUNDING ROCK, BACKFILL MATERIAL, POSSIBLE CORROSION PRODUCTS, ETC...
LABORATORY PARAMETER STUDIES HAVE BEEN CONDUCTED FOR MANY YEARS AND ARE INDISPENSIBLE TO AN UNDERSTANDING OF THE GLASS ALTERATION MECHANISMS AND THE EFFECTS OF EACH PARAMETER, HOWEVER, NONE OF THE PARAMETERS IS INDEPENDENT OF THE OTHERS AND ALTHOUGH INVESTIGATING THEM SEPARATELY IS NOT SUFFICIENT, A SYSTEMATIC STUDY OF ALL POSSIBLE COMBINATIONS WOULD BE PROHIBITIVE.

UNDER THESE CIRCUMSTANCES PARAMETER EXPERIMENTS MUST BE COMPLETED BY INTEGRAL TESTS WHICH SIMULATE ALL OF THE PARAMETERS OF A GRANITIC REPOSITORY AS REALISTICALLY AS POSSIBLE.

THE OBJECTIVE OF THIS PROGRAMME IS TO CONDUCT A SERIES OF INTEGRAL LEACHING EXPERIMENTS MEETING THIS CRITERION.
THE PROGRAMME IS EXPECTED TO PROVIDE INFORMATION IN THE FOLLOWING AREAS:
- EQUILIBRIUM CONCENTRATIONS WHICH TEND TO OCCUR WHEN ALL OF THE ENVIRONMENTAL MATERIALS ARE PRESENT;
- GLASS ALTERATION RATE UNDER STEADY-STATE CONDITIONS;
- EFFECT OF SMECTITE (CONSIDERED FOR STORAGE IN FRANCE) ON GLASS ALTERATION: PREVIOUS EXPERIMENTS SHOWED THE DETERMINING EFFECT OF THE NATURE OF THE CLAY USED AS A BACKFILL MATERIAL;
- IDENTIFICATION OF NEWLY FORMED COMPOUNDS UNDER INTEGRAL TEST CONDITIONS;
- ACTINIDE BEHAVIOUR IN A COMPLEX GEOLOGICAL MEDIUM: LEACHING RATE AND PHYSIOCOCHEMICAL FORM.
Integral experiments have been designed to simulate a geological storage environment. These included experiments with environmental materials simulating a granite repository.

Fracturation of the glass block did not appreciably increase aqueous corrosion, although all the fracture surfaces were accessible to water. Corrosion behaviour was not significantly different for inactive or radioactive specimens under these conditions. This investigation also reveals the strong influence of clays on glass alteration. The test clay (smectite) not only enhanced glass corrosion proportionally to the ratio between the clay mass and the glass surface area, but also diminished the actinide retention factor in the altered film that developed at the glass surface.

Integral experiments designed to simulate a geological storage environment were performed. These included 5 experiments with environmental materials simulating a granite repository:

2 tests with non-radioactive SON 68 18 17 glass (a monolithic block and a fractured block simulating an industrial waste glass), and

3 tests on alpha doped glass specimens neptunium-237, plutonium-239 and americium-241.

4 additional experiments with non-radioactive or plutonium-239 doped glass were conducted with moist clay as a simulated backfill material. Fracturation of the glass block did not increase aqueous corrosion significantly, although all the fracture surfaces were accessible to water. Corrosion behaviour was not significantly different for inactive or radioactive specimens under these conditions.

This investigation also reveals the strong influence of clays on glass alteration. The test clay not onlyenhanced glass corrosion proportionally to the ratio between the clay mass and the glass surface area, but also diminished the actinide retention factor in the alteration film that developed at the glass surface.
B1. TWO NON-RADIOACTIVE EXPERIMENTS WITH SIMULATED SON 68 GLASS USING MONOLITHIC AND FRACTURED BLOCKS TO SIMULATE AN INDUSTRIAL GLASS BLOCK.

B2. FOUR EXPERIMENTS WITH ALPHA-DOPED GLASSES: THE GLASS SAMPLES WILL BE SPIKED WITH URANIUM-THORIUM, NEPTUNIUM, PLUTONIUM AND AMERICIUM, RESPECTIVELY.

B3. FOUR MINI-EXPERIMENTS WITH MOIST CLAY ON NON-RADIOACTIVE GLASS AND ON PLUTONIUM-DOPED GLASS.

Dziedzina nauki

Program(-y)

FP1-RADWASTOM 3C - Research and development programme (Euratom) on the management and storage of radioactive waste, 1985-1989

Temat(-y)

Data not available

Zaproszenie do składania wniosków

Data not available

System finansowania

CSC - Cost-sharing contracts

Koordynator

Commissariat à l'Energie Atomique (CEA)

Wkład UE

Brak danych

Adres

Centre d'Études Nucléaires de la Vallée du Rhône Cité de Marcoule
30205 Bagnols-sur-Cèze
Francja

Koszt całkowity