A solid-state and X-ray spectroscopic study of transition-metal oxides: Developing materials for the sequestration of nuclear waste

点击翻译按钮获取中文摘要

INTRODUCTION: Many governments are considering expanding their fleet of nuclear power plants because of environmental concerns and the dwindling supply of fossil fuels. However, nuclear reactors produce radioactive waste. The long-term objective of this research program is the development of materials that can sequester nuclear waste.******OBJECTIVE 1: EFFECT OF THE STRUCTURE ON THE RADIATION RESISTANCE OF OXIDES: Titanium-containing crystalline oxides have received considerable attention for the sequestration of actinides because of their high chemical durability. A negative aspect of using crystalline materials for this application is that the decay of radioactive elements can result in the material becoming amorphous. The ability of materials to resist being damaged by radiation can be related to the structure. The objective of this study is to investigate the structural characteristics of a series of metal oxides containing corner-, edge-, and/or face-sharing metal-O polyhedra to understand the influence of crystal chemistry on the structural stability of the material. A comparative study of brannerite-, pyrochlore-, zirconolite-, and columbite-type oxides will be performed. Materials will be synthesized by solid-state methods and implanted using a beam of high-energy ions, which is an accepted method of simulating the effect of radioactive decay on a material. All materials will be studied by X-ray diffraction (XRD) and synchrotron radiation-based spectroscopic techniques.******OBJECTIVE 2: DEVELOPING GLASS-CERAMIC COMPOSITES: Spent nuclear fuel pellets are composed of a variety of fission products. We propose that glass-ceramic composites offer unprecedented flexibility for the sequestration of fission products. The objective of this study is the synthesis of glass-ceramic composites containing pyrochlore-, brannerite, or zirconolite-type oxides surrounded by a borosilicate glass. Composites involving slag from steel production will also be investigated. ******OBJECTIVE 3: THE INFLUENCE OF SYNTHETIC METHOD ON SITE DISORDER: Low-temperature synthesis methods are more economical to produce nuclear waste sequestration materials on the industrial scale compared to high-temperature methods. Site disorder within a structure may impact the resistance of the material to radiation-induced damage. The objective of this study is to determine how the synthetic method affects the metal site-disorder in zirconolite-, pyrochlore-, and perovskite- type oxides. ******SIGNIFICANCE: It is important to investigate various strategies to handle nuclear waste if we are to increase our reliance on nuclear power. This research program will be unique in that we will study how the resistance of materials to radiation damage changes depending on crystal structure, composition, and synthetic method. This program will also train students in solid-state chemistry and X-ray spectroscopy.