Ultimate pressure capacity of nuclear reactor containment buildings under unaged and aged conditions

Using ABAQUS, a non-linear finite element analysis (FEA) was performed to evaluate and compare the effects of degradation mechanisms by aging on the ultimate pressure capacity (UPC) of APR1400 reactor containment building (RCB). As the primary degradation mechanisms, prestress loss, concrete aging, rebar corrosion, and liner corrosion were simulated in the modelling and calculations. The results for unaged reactor containment buildings showed that the failure sequence by the internal pressure build-up consisted of 4 stages and reinforcement yielding strain of reinforced concrete would be the most important factor governing the UPC of RCBs. Among the four degradation mechanisms, corrosion occurring on the outer and inner rebar layers was identified as the main degradation mechanism affecting most significantly the ultimate pressure capacity of the APR1400 reactor containment building.