Date of Award
1989
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
Glass corrosion in MCC-1 tests at 90{dollar}\sp\circ{dollar}C and 30{dollar}\sp\circ{dollar}C was characterized by dissolution of glass and formation of surface layers. All three glasses studied showed greater durability in seawater (SW) than in distilled and deionized water (DDW). Among three types of glass, PNL 76-68 was least stable in both DDW and SW. ABS-118 glass and basaltic glass showed comparable dissolution rates.;A reaction zone was found between surface layer and unaltered glass. This was usually less than 1000 A and depleted in soluble elements such as B, Na, and Mo. For PNL 76-68 glass, Si was also depleted in this zone. When SW was used as leachant, Mg was found to diffuse through the reaction zone.;Glass corrosion consists of three successive stages: (1) ion-exchange between alkalis in glass and H{dollar}\rm\sb3O\sp+{dollar} (and/or Mg{dollar}\sp{lcub}2+{rcub}{dollar}) in leachant; (2) formation of a reaction zone depleted in B, Na, Li, Mo, and Si; and (3) slow dissolution of the reaction zone at solid/solution interface accompanied by diffusion of ions from the fresh glass boundary, and subsequent precipitation of hydroxides and silicates. The dissolution reaction slows down when silicate phases attain saturation. Mg diffusion through the reaction zone and rapid saturation of Mg layer silicate contribute to the enhanced stability of the glasses in SW.;Palagonitization of basaltic glass from DSDP Site 335 bears remarkable similarities to the corrosion processes in the laboratory conditions. The laboratory determined dissolution rate was found to be the same order as those of basaltic glass from Site 335. At 90{dollar}\sp\circ{dollar}C, the glasses studied would dissolved at a rate of a few to a few tens of micrometers per year.
Recommended Citation
Zhou, Zhihong, "Chemical Durability Of Simulated Nuclear Waste Glasses And Their Natural Analogues In Submarine Conditions" (1989). Digitized Theses. 1859.
https://ir.lib.uwo.ca/digitizedtheses/1859