Ageneralization and rationalization of the main safety design criteria and safety analysis methodologies developed in nuclear aerospace and chemical engineering is presnted in two comprehensive volumes. The concepts of risk, damage and probability of hazardous events are introduced. Risks connected with the use of main harmful substances are quantitatively identified. The methods employed for the safety analyses are described, together with the methodologies for seismic analyses and for Probabilistic Risk Assessment. The main criteria for protection of plants from internal and external events are introduced and described. In addition, the problem of emergency planning is considered. This book is particularly intended for engineers working in the nuclear field, in chemical industries, in industrial plants, in fuel storages and with high-risk substances, as well as for engineers operating in licensing organizations and for inspectors.