Performance as a Measure of Robustness

Robustness of a structure, system, or component (SSC) is its ability to withstand types and magnitudes of demands that are significantly greater or different from the design basis demands without losing its ability to function or without suffering disproportionate damage. The need for robust SSCs has been recognized in view of a number of failures resulting from conditions that were not anticipated during the design developments of SSCs (e.g., human errors in design, fabrication and construction, deliberate attempts to destruct, and fire events). A robust SSC can also be defined as an SSC that is capable of coping well with changes in its operating environment, with minimal damage, alteration, or loss of functionality. In essence, the robustness indicates reliability of an SSC to perform its intended function. Therefore, it is an important characteristic in an SSC that is required for protection of public heath and safety and environment.