反应堆吊篮在正常和劣化支撑条件下的振动模态特性

Vibration Characteristics of a Core Barrel with Conventional and Unconventional Core Support Barrel

反应堆正常运行时,吊篮组件受到冷却剂的作用而诱发振动,往往会造成吊篮及其支撑结构发生疲劳破坏或松动脱落,危及反应堆的安全。通过长期对运行中的反应堆吊篮振动特性的监测发现:随着反应堆的运行,吊篮的固有频率,特别是梁式频率会发生较大的变化,而常规吊篮模态的计算方法是无法模拟和预测该梁式频率的变化规律。针对该问题提出了在劣化支撑条件下吊篮结构模态分析的计算方法和力学模型,该方法准确模拟了不同的劣化状态下吊篮的约束边界。以国内某堆型的吊篮结构为研究对象,分别计算了在空气和静水中支撑条件劣化5%、10%、15%、20%、25%、30%、35%、40%时的振动模态,并与国外学者相关研究的试验结果进行对比,结果表明:本文提出的反应堆吊篮在劣化支撑条件下的振动模态计算方法与相关研究的试验结果趋势一致,吻合较好。因此,该计算模型是合理、可行的,能够满足工程计算分析的需求。

The flow-induced vibration(FIV) of the core barrel is very common, and the characteristics of the FIV is important to the security of the nuclear reactor. By monitoring the vibration characteristics of the core barrel, the natural frequencies of the core barrel would decrease, as the nuclear reactor is running, especially for the fundamental natural frequency of the core barrel. It is difficult to calculate this problem with the conventional method. In order to solve this problem, a new method to simulate loose-joined flange between the top of the core support barrel(CSB) and the head of the vessel was presented in this paper. The dynamical finite element model of the structure of the bore barrel was obtained and the fundamental frequencies of the core barrel were calculated, including 8 situations, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% loose-joined flange between the top of CSB and the head of the vessel. The comparison between the calculated results and the experimental ones show that the method developed in this paper is reasonable and feasible.