This book is aimed at the practicing engineer who is involved with the design, fabrication of operation of zirconium core components. The Metals Properties Council, as part of its continuing role of collecting, analyzing, and updating materials properties data, has arranged for the preparation of this book. STP 815 presents the reader with pertinent metallurgical and phenomenological aspects of creep in zirconium and zirconium alloys and the different ways in which this information is used in the design of core components for nuclear reactors.