Dynamic fragility concepts for equipment design and qualification

Fragility concepts are explored for use in design and qualification of nuclear plant equipment, and for relating equipment ultimate capability to that of the overall plant. In the most general sense, the fragility level of a device may depend on several different types of environmental stress or challenge factors, (i.e., heat, nuclear radiation, vibration, etc.) that influence its operation. However, emphasis is concentrated on the dynamic, and particularly seismic fragility levels of equipment. A general definition of dynamic fragility and various methods for its measurement are described. The state of published data on nuclear equipment fragility is discussed, and limitations on its use are noted. From there, the concept of a standardized seismic fragility data base and its potential uses are considered. Various gaps in the methodology are identified, and recommendations for further research are suggested