This volume is a continuation of the five volumes of "The Chemistry of the Actinide and Transactinide Elements" (published 2006). It expounds on topics in actinide science that are undergoing rapid scientific developments and that are germane to the safe development of nuclear energy in the 21st century, from nuclear fuels to the environmental science and management of waste. The scope of Volume 6 encompasses: actinides in the geosphere, subsurface interactions of actinides species with microorganisms, chemistry of nuclear fuels, actinide waste forms and radiation effects, analytical chemistry of plutonium, actinide chalcogenide compounds, molecular spectroscopy and reaction of the actinide ions in the gas phase and rare gas matrices, and hydrothermal synthesis of actinide compounds. This volume is written by active practitioners and recognized experts in their specialty areas. Each of the topics represents the current state of knowledge in this fascinating area of science and technology.