The basic objective of this book is to present the principles underlying the thermal and hydraulic design of pressurized water reactors. In addition, the empirical data, engineering properties, and computer techniques required for design, but not available in conventional handbooks, are presented or referenced. Because of the many advances and changes that have occurred since the second edition, extensive improvements in both understanding the phenomena involved and in calculational techniques are reflected in the substantial additions to this third edition. Also, an additional chapter has been added to accommodate the many developments in the area of safety analysis. This book is intended to provide an overview for nuclear engineering graduate students and to serve as a reference for engineers working in the nuclear power industry.