核反应堆驱动机构外套筒对整机抗震性能的影响

Influence of the Outer Sleeve on the Anti-seismic Characteristic of Nuclear-fuel-safety-rod-driving Mechanism

安全棒驱动机构是核反应堆的重要组成部分,其抗震性能是反应堆安全性评价中的重要指标。在设计初期预知地震载荷下的应力分布情况有助于提高该机构的高抗震性能。针对某型安全棒驱动机构的设计特征,建立一种基于反应谱原理的驱动机构外套筒抗震性能分析模型。基于国内外相关抗震设计标准确定地震反应谱,通过分析实际工况的载荷分布情况,确定模型的边界条件;通过对驱动机构整机、单独内部机构与外套筒3种模型的分析计算,获得了相同载荷及边界条件下的3种模型各自的应力分布。再根据3种模型的特点创建具有代表性的节点路径,通过提取路径上的应力分布并进行对比,清楚反映出该3种不同模型的应力分布情况,研究了外套筒对控制棒驱动机构抗震性能的影响。分析结果表明外套筒的结构参数直接决定驱动机构整机的抗震性能,外套筒可有效减小内部机构在地震载荷作用下产生的应力,整机外套筒上应力分布情况与整机内部机构应力分布情况基本一致,单独的外套筒与整机的外套筒应力分布趋势一致。这种分析技术可用于在结构设计初期对驱动机构抗震性能设计是否合理进行核算评价。这样可以有效提高设计效率,降低地震载荷带来的风险。

Nuclear-fuel-safety-rod-driving mechanism is an important part of the nuclear reactor and its seismic characteristic is a very critical parameter in safety evaluation.In the preliminary design stage,the simulation of the distribution of stress under seismic load is helpful to improve its seismic characteristic.To ensure that the nuclear fuel safety rod driving mechanism functions safely and reliably in the whole longevity,the seismic analysis was carried out at the level of preliminary design.First,the model of nuclear-fuel-safety-roddriving mechanism was simplified based on the parameter settings.Second,the seismic response spectrum was ensured,referring to domestic and overseas seismic fortification criterion,and then the practical condition was analyzed and converted to boundary condition in finite element model.The stress distribution of the whole mechanism and the outer sleeve and the single internal structure were calculated and compared.And the influence of the outer sleeve on seismic characteristic was studied.The typical node paths were constructed based on the features of three models.The comparison of the extracted stress from the node paths showed the difference of stress distribution of three models.The results indicated that directly analyzing the stress distribution of the outer sleeve could evaluate the rationality of the whole mechanism.The outer sleeve can efficiently reduce the stress of internal structure under seismic load,the stress distribution of the outer sleeve is nearly the same with the whole internal structure,and the stress distribution of the single outer sleeve is nearly the same with the outer sleeve,which is a great reference to the engineering design.By this way,the efficiency of design would be enhanced and the risk would be reduced.