Study On The Failure Mechanism Of Containment For CPR1000Nuclear Power Plant

As a kind of safe and efficient energy, nuclear power is one of the main energy forms in the current and future China. The key to ensure the safety of nuclear power is to ensure the safety of nuclear power engineering structures. Containment is an important structure in nuclear power plant and is the last barrier to prevent the leakage of radioactive substances. So the importance of its safety is self-evident. The domestic advanced nuclear power plant CPR1000containment is taken as the object and the AN SYS software is used to establish the finite element model of containment in this paper. The failure mechanism of containment under internal pressure and earthquake action is emphatically analyzed, which provides the basis for the design and construction of nuclear power plant containment. The main research contents and conclusions are as follows:(1) The key to establish a reasonable finite element model of the containment is to accurately simulate the interaction between the prestressed tendons and the concrete. Various simulating methods are discussed and the bar element is used to simulate the prestressed tendons in this paper. Then the tendons elements and concrete elements are connected by common nodes. The calculation results of the axial forces of prestressed tendons show that the proposed method can accurately and reasonably simulate the interaction of the prestressed tendons and the concrete, which lays the foundation of the nonlinear damage analysis for the containment.(2) The high-stress areas occur at the buttresses, around the equipment hatch, near the ring beam and the bottom of the cylinder under the internal pressure. Special attention should be paid to the periphery of the equipment hatch and the bottom of the cylinder. No concrete cracks occur under the design internal pressure of0.4MPa, which meets the design requirements of the nuclear power plant containment. With the increase of internal pressure, concrete cracks occur above and under the equipment hatch firstly and gradually expand to the left and right sides of the equipment hatch. There are many concrete cracks around the equipment hatch under the internal pressure of0.8MPa. But the maximum stress of the steel liner is still less than the yield strength and the containment still performs the radiation protection function. (3) The results of the seismic response analyses of containment based on both rigid and viscoelastic foundation show that no concrete cracks occur in the CPR1000containment under the earthquake action with peak acceleration of0.3g (horizontal)+0.2g (vertical)(artificial wave of RG1.60spectrum). But for the peak acceleration of0.4g (horizontal)+0.27g (vertical) the concrete cracks occur nearby the base of the containment.(4) Though the concrete cracks occur nearby the base of the CPR1000containment under a strong earthquake action with the peak acceleration of0.5g (horizontal)+0.5g (vertical), no more damage and cracks occur under the design internal pressure of0.4MPa. this shows that the containment has quite seismic capacity and bearing capacity after the earthquake.