Glass leaching performance
Current understanding of the leaching performance of high-level nuclear waste (HLW) glass is summarized. The empirical model of waste glass leaching behavior developed shows that at high water flow rates the glass leach rate is kinetically limited to a maximum value. At intermediate water flow rates, leaching is limited by the solution concentration of silica and decreases with decreasing water flow rates. Release of soluble elements is controlled by silica dissolution because silica forms the binding network of the glass. At low water flow rates, mass loss rates reach values controlled by formation rates of alteration minerals, or by diffusion of dissolution products through essentially stagnant water. The parameters reviewed with respect to their quantifiable influence on leaching behavior include temperature, pH, leachant composition, glass composition, thermal history, and radiation. Of these, temperature is most important since the rate of mass loss approximately doubles with each 10/sup 0/C increase in dilute solutions. The pH has small effects within the 4 to 10 range. The chemical composition of the leachant is most important with regard to its influence on alteration product formation. Glass composition exhibits the largest effects at high flow rates where improved glasses leach from ten to thirty times slower than glass 76 to 68. The effects of the thermal history (devitrification) of the glass are not likely to be significant. Radiation effects are important primarily in that radiolysis can potentially drive pH values to less than 4. Radiation damage to the glass causes insignificant changes in leaching performance.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6405886
- Report Number(s):
- PNL-4576; ON: DE83012465
- Resource Relation:
- Other Information: Portions are illegible in microfiche products. Original copy available until stock is exhausted
- Country of Publication:
- United States
- Language:
- English
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36 MATERIALS SCIENCE
BOROSILICATE GLASS
LEACHING
RADIATION EFFECTS
TEMPERATURE EFFECTS
HIGH-LEVEL RADIOACTIVE WASTES
PH VALUE
QUANTITY RATIO
DISSOLUTION
GLASS
MATERIALS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
SEPARATION PROCESSES
WASTES
052002* - Nuclear Fuels- Waste Disposal & Storage
360605 - Materials- Radiation Effects
360604 - Materials- Corrosion
Erosion
& Degradation