STR-944: EFFECTS OF FINITE ELEMENT MODELLING APPROACH FOR PRESTRESSING SYSTEM ON THE PRESSURE CAPACITY OF A CANDU CONTAINMENT STRUCTURE

The primary objective of this article is to investigate the response of a CANDU®1 nuclear power plant containment structure to a much higher internal pressure that could be encountered during a severe accident. In this study, for the prestressed containment structure, a detailed model is obtained by a full 3D model. Nonlinear finite element method is employed to predict the response of the structure using ANSYS software. The major challenges for modelling prestressing tendon elements are to accommodate parameters affecting prestressing forces. In previous research studies, the prestressing system is modelled using an equivalent pressure and tendon end forces, and tendons are modelled as smeared reinforcement in the concrete elements. In this study, the prestressing tendons are modelled using discrete elements. This method enables the capability of the model to update the prestressing forces accommodating the non-uniform losses. The difference in the response of the structure using the discrete model for the prestressing tendons and the smeared approach is 15 percent. It is observed that the containment structure, meets the design requirements of the current standards as it behaves linearly up to 1.5 times the design pressure, and the ultimate pressure capacity is estimated as 2.7 times the design pressure. The ultimate pressure capacity is reached when the prestressing tendon rupture at the dome