In a comprehensive and lucid manner this book presents an understanding of the aging degradation of the major pressurized and boiling water reactor structures and components. The design and fabrication of each structure or component is briefly described followed by information on the associated stressors. Interactions between the design, materials, and various stressors that cause aging degradation are reviewed. In many cases, aging degradation problems have occurred, and the plant experience to date is analysed. The discussions summarize the available aging-related information and are supported with extensive references, including references to U.S. Nuclear Regulatory Commission (USNRC) documents, Electric Power Research Institute reports, U.S. and international conference proceedings and other publications. The book will prove a useful reference for engineers engaged in the operation and life extension of the present generation of nuclear power plants and for those engaged in the design of advanced light water reactors. It will also provide engineering students with insight into the practical materials-related issues associated with the design and operation of nuclear power plants. The work will also serve as a basis for programs to address the new aging-related issues likely to arise as plants get older.