小型堆安全壳在地震激励下的动力响应分析

Dynamic Response Analysis of Small Nuclear Reactor Containment under Seismic Excitation

小型核反应堆(小型堆)因具有模块化、高灵敏性及安全性等优良特性备受关注,其安全壳结构在地震作用时的动力特性对小型堆的安全性评定有着重大影响作用。将小型堆安全壳用ABAQUS软件建立三维有限元模型并模拟非线性抗震分析,模拟在地震作用下小型堆安全壳模型的频率、振型和加速度及位移等动力特性,对比前16阶振型和频率,表明安全壳的1和2阶、3和4阶等阶次的振动频率分别接近且主要振动方向为水平方向。同时以峰值分别为0.2 g、0.3 g与0.4 g的地震动作为荷载输入,得到3种加速度峰值作用时预应力钢束和混凝土安全壳结构的最大主应力云图,对比发现3种地震峰值作用下混凝土安全壳的最大主应力均小于抗拉强度标准值2.65 MPa,且最大主应力主要集中分布在安全壳结构的闸门孔周边及基础相连的底部附近。最后对比安全壳结构的加速度与位移响应,评定结果表明在极限地震动作用下小型堆安全壳结构具有良好的安全性。

The excellent characteristics of small nuclear reactor,such as modularity,high sensitivity and safety,are attracted much attention.The dynamic characteristics of the containment structure during earthquakes have a significant impact on the safety assessment of small nuclear reactor.The small nuclear reactor containment was used to establish a three-dimensional finite element model and simulate nonlinear seismic analysis by ABAQUS code.The frequency,mode shape,acceleration and displacement dynamic characteristics of the small nuclear reactor containment model under the action of earthquakes were simulated,and the first 16 modes and frequencies were compared.The results show that the vibration frequencies of the 1st and 2nd,3rd and 4th orders of the containment are respectively close and the main vibration direction is horizontal.Also using the ground motions with peaks of 0.2 g,0.3 g and 0.4 g as the load input,the maximum principal stress distribution diagrams of the prestressed steel strands and the concrete containment structure under the action of three peak accelerations were obtained.The maximum principal stress of the concrete containment is less than the standard value of tensile strength(2.65 MPa),and the maximum principal stress is mainly distributed in the vicinity of the hole of the structure and the bottom of the foundation.The acceleration and displacement response of the containment structure were compared.The evaluation results show that the small nuclear reactor containment structure has good safety under the action of extreme ground motions.