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Background

The Office of Environmental Management in the US Department of Energy (DOE-EM) is responsible for management of defense wastes, including high-level tank wastes (HLW), that must be safely isolated from the environment for long periods. This requires understanding the performance and fundamental mechanisms of waste form degradation, and the design of new waste forms with improved performance, which comprise the goals of WastePD.

WastePD will develop innovative approaches and solutions to those goals through the synergistic interactions of individuals who are experts in the degradation behavior, modeling, and design of glasses, ceramics and metal alloys. WastePD is the first center ever created to address the degradation of this diverse group of materials in a comprehensive and coordinated manner. The science goals are grouped into three common topics: corrosion mechanisms via advanced characterization, environmental impacts, and materials design. The fundamental understanding of the degradation mechanisms of the waste forms and containers will allow DOE to develop new materials with improved properties, to prevent environmental contamination and to explore totally new disposal concepts. The waste forms of interest are tank waste transformed into glass, ceramic materials containing radionuclides, and metal canisters that protect the various waste forms.

The synergistic activities between the materials classes in the areas of experimental techniques, computational methodologies, and design approaches are a key component of WastePD. These synergistic activities will stimulate the achievement of new discoveries and reveal physical insights that would otherwise have been overlooked or not recognized. Sharing the understanding of the degradation mechanisms of glasses, ceramics, and alloys will lead to identification of commonalities and new materials design rules.

For organizational purposes, projects to address the degradation and design of waste forms are grouped into teams associated with the three materials classes. The Glass Team will develop a fundamental understanding of the structure and chemistry of the reacting glass-solution interface, determine the dominant mechanism of glass corrosion and the impact of environmental and chemical parameters, and develop methods to formulate high-performance glasses with tailored long-term performance. The Ceramics Team will develop a fundamental understanding of nano- to mesoscale phenomena including radionuclide incorporation, stability, transport, chemical corrosion, and surface interaction of ceramic waste forms upon near field interaction. New methods for ceramic waste form design will be developed with optimized waste loading, stability, and long-term performance. The Metals Team will investigate the fundamental aspects of alloying for controlling corrosion properties by focusing on bulk metallic glasses, high entropy alloys, and alloys that contain extremely high content of selected beneficial elements. It will also develop the mechanisms of stainless steel atmospheric pitting and cracking, and investigate the resistance of the newly developed alloys to storage and disposal conditions.

The schematic diagram in Figure 1 describes the organization of WastePD. The glass, ceramics, and metals teams are shown with the synergistic activities at the core. The management structure of WastePD is given in Figure 2.