Description
1st Paragraph: Radioactive waste, produced as a result of nuclear fission for power generation and weapons production, must be immobilized to limit radionuclide release into the biosphere over periods of many thousands of years. Several countries, including the United States, have chosen to vitrify nuclear waste materials prior to disposal. The solubility of ions in liquid, including if the liquid is super-cooled to a glass phase, is greater than in a corresponding crystalline solid; thus, radioactive ions are incorporated into a broad distribution of available sites in the glass structure, and the product is highly durable [1]. However, a glass phase is not thermodynamically stable and will, in principle, undergo some degree of alteration with time. Low level vitrified wastes will be disposed of in near surface sites, such as the Integrated Disposal Facility at the Hanford Nuclear Reservation, WA. Near-field solution chemistry, water diffusion, ion exchange, precipitation of mineral alteration phases, and microbial colonization could influence long-term glass performance, but not all of these parameters are currently captured in the modeling and performance assessments for low level nuclear waste glass disposal sites. Thus, robust models based on a mechanistic understanding of the processes responsible for glass degradation and radionuclide release in near surface environments are needed. These models will give confidence to performance assessments for nuclear waste disposal sites by predicting the durability of vitrified nuclear wastes over the course of thousands of years.
Authors: Carolyn I. Pearce, Jamie L. Weaver, Edward P. Vicenzi, Thomas Lam, Paula DePriest, Robert Koestler, Tamas Varga, Micah D. Miller, Bruce W. Arey, Michele A. Conroy, John S. McCloy, Rolf Sjoblom, Michael J, Schweiger, David K. Peeler, and Albert A. Kruger
Keywords: Nuclear Waste Glass Disposal, Glass Corrosion, Long-Term Analogues, Biodeterioration