Study on failure mechanism of prestressed concrete containments following a loss of coolant accident

A loss of coolant accident (LOCA) is considered as a severe accident in the safety of nuclear power plant. LOCA has significant negative influences on the containment structures. Because the characteristics of temperature variation are instantaneous, the thermal field in the inner wall of the containment has a remarkably non-uniform distribution, which leads to complex mechanical behavior. In this study, the distribution of the thermal field of a prestressed concrete containment vessel (PCCV) at different times under a LOCA is analyzed. On this basis, the mechanical behavior of the PCCV under the coupling effect of thermal load and internal pressure are systematically investigated, and the failure mechanism and failure mode of the structure are revealed. The results show that the structure fails with a large deformation near the largest hole and evident expansion at the dome considering the thermal load. However, the deformation develops deficiently under the high temperature of the LOCA. Finally, design suggestions are proposed for a containment under thermal–pressure coupling action.