Probabilistic risk assessment application to equipment qualification

Probabilistic Risk Assessment (PRA) provides us with an estimation of the chances that a hazard may happen. In the area of Seismic Equipment Qualification, the chance that a component will experience and earthquake of highest magnitude (0.2g) can be predicted using PRA. Recent studies have shown that the components are over-designed to maintain their structural integrity and functionality. For the purpose of qualification, the Test Response Spectra (TRS) should envelop the Required Response Spectra (RRS). However, with the PRA approach, the magnitude of an earthquake can be estimated. PRA estimates are generally lower than those obtained using traditional methods but do not compromise the component's structural integrity and functionality. This approach will result in significant cost savings in design and construction. For expansion on the concept of PRA that estimates this frequency of occurrence of a given seismic event, refer to United States Nuclear Regulatory Commission (US NRC), Lawrence Livermore National Laboratory (LLNL), and Electrical Power Research Institute (EPRI) studies for development of Natural Phenomena Hazard Curves. Currently, US NRC, LLNL, and EPRI are involved in a joint program to address seismic hazard methodologies and to develop recommendations for improved hazard estimations for the future. The final product of this effort is expected to result in more realistic hazard estimates