Passive safety concepts applied to critical functions

Safety is of paramount concern in todays high technology environment. Because of technological advances, there are numerous situations (high consequence operations) for which the implications of a safety failure are so severe that extreme attention to safety systems is essential. Some of those situations are: nuclear weapon detonation safety, nuclear reactor safety, dam safety, mass transit transportation safety, and hazardous materials transportation and handling safety. In each case, specific safety systems, human control, and administrative procedures have been designed to give a high level of assurance against disasters. In an overview sense, safety concepts can be divided into two broad approaches: active safety and passive safety. Active safety systems, in general, are based on the need for ``functioning`` elements (operating motors, operator action, etc.) and safety may be based in a large measure on ``reliability`` data (historical records of the operability success of components). Passive safety basically depends on non-functionality.