When placed in extreme environments, materials can behave in unexpected and unpredictable ways. Understanding the forces that affect material behavior in extreme environments is critical to assuring the safety and reliability of industrial processes and accelerating the processing of radioactive wastes at Department of Energy sites.
With more than 50 years studying material effects in high pressure, high temperature, and in radiologically active spaces, PNNL has established the scientific expertise necessary to advance understanding of material behavior in these environments. We have developed and employed specialized synthesis and characterization tools available in few other research settings. Our studies use the Radiochemical Processing Laboratory, which houses specialized labs for research with microgram-to-kilogram quantities of fissionable materials and megacurie activities of other radionuclides. Further, the transmission electron microscopes, nuclear magnetic spectrometers, and molecular beam epitaxy resources located in the Environmental Molecular Sciences Laboratory, a national user facility, all contribute to our research capabilities.
Areas where radioactive waste is stored, for example, are extremely alkaline with little water, and materials here are driven far from chemical equilibrium by ionizing radiation. This complex chemical milieu requires study to assure responsible stewardship. Toward that goal, PNNL leads a multidisciplinary, multi-institutional team examining the unique chemistry of this environment. The Interfacial Dynamics in Radioactive Environments and Materials (IDREAM) Energy Frontier Research Center combines theory with experimental testing toward the goal of predicting material behavior in radioactive environments.
For example, during radioactive waste treatment, the process of dissolving waste is often quite slow. To understand why, researchers used high-field magic angle spinning nuclear magnetic resonance spectroscopy to get a close-up view of how gibbsite, a type of aluminum crystal, forms and dissolves. They discovered that the process involves a complicated (and slow!) change in geometry that had not been fully understood. The team captured real-time system dynamics as a function of experimental conditions, revealing previously unknown details. Understanding how aluminum coordination changes in extreme environments may lead to efficiencies in aluminum production and accelerate radioactive waste processing.
Other research in extreme environments includes surface science, crystal growth, materials synthesis, self-assembly, and materials characterization, such as mineral carbonation in supercritical carbon dioxide using high-pressure scanning probe microscopy.