严重事故下预应力混凝土安全壳非线性分析及性能评估

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

预应力混凝土安全壳作为核电厂重要防泄漏屏障,对保证核电厂正常运行、确保人员安全至关重要。本文基于顺序热力耦合方法对严重事故工况下预应力混凝土安全壳进行非线性有限元分析,考虑了温度和内压荷载共同的影响,分析了安全壳结构典型不连续区域和连续区域的位移响应。研究表明:安全壳混凝土不连续区域位移响应沿厚度方向上差异较为显著,而连续区域处的差异相对较小;安全壳泄漏失效模式由设备闸门位置控制,50%和95%分位水平的内压分别为1.266 MPa和1.072 MPa;破口失效模式由筒体某一位置控制,50%和95%分位水平的内压分别为2.224 MPa和1.883 MPa;本文所分析的预应力混凝土安全壳的内压承载力满足最小安全裕度不小于2.5的要求。

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.