Seismic Performance and Aging: A Correlation Study

The effects of time/temperature and operational cycling aging mechanisms on seismic performance of safety-related equipment was investigated. The approach was to perform seismic tests on identical samples of electrical and electronic safety-related components which had been preconditioned. The sample sets contained components which were unaged, thermally aged, cyclically aged and thermally/cyclically aged. Both the aging and seismic stresses applied to the components were purposely more severe than typically required for qualification. The results of this program demonstrate the adequacy of the selection process to determine age sensitivity and provide the technical justification for exemption from aging prior to seismic testing for those components which demonstrated no correlation between aging and seismic performance.