Nonlinear Analysis and Performance Evaluation of Prestressed Concrete Containment Structure under Severe Accident Condition

As the important leak-tight barrier in nuclear power plants, the prestressed concrete containment structure is essential to maintain the safe operation of nuclear power plants and ensure the safety of personnel. Based on the sequentially coupled thermal-stress method, nonlinear finite element analysis of the containment structure under severe accident loading is carried out in this study. Thermal and internal pressure effect is considered, and the displacement and strain response at current zone and singularity zone of the containment structure are studied in detail. Results indicate that the displacement response in the singularity zones of the containment structure along the thickness direction has the most significant difference, while that in the current zones are relatively small. Leakage failure mode of the containment is controlled by the location of the equipment hatch, and the break failure mode is controlled by the location of the cylinder wall. 50% percentile and 95% percentile pressure capacity corresponding to the dominant leakage mode of the containment is 1.266 MPa and 1.072 MPa, respectively, and 50% percentile and 95% percentile pressure capacity corresponding to the dominant break failure mode is 2.224 MPa and 1.883 MPa, respectively. The prestressed concrete containment analyzed in this paper meets the requirement of minimum margin not less than 2.5.