反应堆结构类裂纹不连续区的疲劳损伤评价方法研究  

Fatigue Damage Assessment Method of Crack-like Discontinuous Zone in Nuclear Reactor Structure

作　　者：庾明达 张丽屏[1] 傅孝龙[1] 杜娟[1] 邵雪娇[1] 姜露 YU Mingda;ZHANG Liping;FU Xiaolong;DU Juan;SHAO Xuejiao;JIANG Lu(Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610213,China)

机构地区：[1]中国核动力研究设计院核反应堆系统设计技术重点实验室,四川成都610213

出　　处：《原子能科学技术》2022年第12期2707-2716,共10页Atomic Energy Science and Technology

基　　金：国家自然科学基金(51606180,11872060)。

摘　　要：反应堆结构中存在大量类裂纹形式的局部结构不连续区,其焊趾处由于应力集中,结构的疲劳性能将极大降低,因此类裂纹不连续区的疲劳损伤评定是反应堆结构分析中的一个重要问题。本文以反应堆压力容器贯穿件焊缝为对象,对规范通用的疲劳损伤评价方法及类裂纹不连续区疲劳损伤评价方法进行了研究,并对各评价方法的保守性进行了比较。结果表明,相比通用疲劳评价方法,类裂纹疲劳评价方法能准确模拟应力集中的影响,并通过引入特征距离,使疲劳损伤系数计算时所对应的应力水平趋于合理。同时,类裂纹疲劳评价方法能避免通用疲劳评价方法中无法确定合理的焊缝疲劳修正系数及疲劳减弱因子的困难,解决了通用疲劳评价方法在类裂纹不连续区疲劳分析评估中存在一定局限性的问题,因此类裂纹疲劳评价方法更适用于类裂纹不连续区的疲劳损伤评定。There are a large number of local structural discontinuous zones in the form of crack-like defects in the reactor structure, due to the existence of the stress concentration at weld toes, the fatigue performance of the structure will be remarkably reduced. Therefore, the fatigue damage assessment in the crack-like discontinuous zone becomes an important issue in the nuclear reactor structure analysis. In this paper, based on the crack-like discontinuous zone caused by the welds between the closure head on the reactor pressure vessel and a penetrated pipe, two types of fatigue assessment methods were studied which are the general fatigue assessment methods considering the correction coefficient for welds and the fatigue reduction factor, and the fatigue assessment methods for the crack-like discontinuous zone in RCC-MRx rules and RCC-M rules. In RCC-M rules, there are two approaches involved: the dedicated fatigue curve algorithm and the cyclic stress strain curve algorithm. For the crack-like fatigue assessment methods, singular elements were first used to calculate the stresses in the crack-like discontinuous zone, then the fatigue damage factors were calculated with the considerations of both the main cycles and sub-cycles of stresses, and the conservatism of the methods involved was compared. The results show that, compared with the general fatigue assessment methods, the stress concentration of the crack-like discontinuous zone can be better simulated by the crack-like fatigue assessment methods, and it is found that the stress level in the characteristic distance range is too high, and the stress curve is flat outside the characteristic distance, so the problem that the fatigue damage factors cannot be calculated caused by the stress singularity in the crack-like region tip, is effectively avoided. Compared with RCC-M rules, the fatigue damage factors calculated by the RCC-MRx method are higher due to the more conservative plastic correction. When the methods based on the RCC-M rules were used, the fatigue d

关 键 词：反应堆 类裂纹不连续区 疲劳损伤评价 

分 类 号：TL351[核科学技术—核技术及应用]