Aging and Seismic Performance for Safety-Related Equipment in a Mild Environment

The dominant aging mechanisms in mild environments (time-temperature (thermal) effects, radiation and operational cycling effects) were investigated for their impact on seismic performance. Sample sets of electrical and electronic safety-related components which had been preconditioned were subjected to seismic stresses. The sample sets contained identical components which had been thermally, cyclically and radiation aged as well as unaged. The aging and seismic stresses represented worst case conditions. 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.