Effects of steel liner corrosion on the leak-tightness of prestressed concrete containment structure under severe accident loads

This study evaluates the effect of steel liner corrosion on the leak-tightness of the prestressed concrete containment structure under severe accidents. Based on the nonlinear finite element method and sub-model technique in the ABAQUS platform, a global model of the containment structure and a detailed sub-model of the corroded steel liner are established. Different calculation methods for the multiaxial stress factor in the failure criterion of the steel liner are compared, and the failure criterion is modified by combining the uniaxial tensile test results of corroded steel liners. According to the modified failure criteria, the corrosion shape and corrosion degree of the steel liner, as well as the thermal effect on the containment structure, are studied in depth. Results indicate that the mechanical properties of the steel liner degrade significantly after corrosion, and the simulation method proposed in this study can reflect the corrosion state of the steel liner well. The multiaxial stress factor based on the Davis triaxiality coefficient is conservative in evaluating functional failure of the containment structure, and the calculation method of the corrosion factor proposed in this study can directly reflect the effect of the corrosion degree on the ductility of the steel liner. Considering that a less conservative calculation result will be obtained based on regular corrosion shapes, the corrosion shapes established from actual corrosion cases of steel liners in this study are available for reference. Pressure capacity of the containment structure corresponding to functional failure decreases with the increase in corrosion degree of the steel liner. When corrosion rates range from 10% to 50%, pressure capacity under the only pressure case and the coupled temperature and pressure case is decreased by 9.21% to 28.58% and 11.35% to 31.06%, respectively. The behavior of the steel liner is significantly affected by the temperature under corrosion conditions.