堆芯中子通量测量系统指套管磨损分布规律及处理准则优化研究

目的分析堆芯中子通量测量系统指套管磨损分布规律,提出处理准则优化建议。方法统计了指套管在堆芯不同位置的磨损数量,分析了指套管磨损分布规律。结合指套管和导向管的结构特点和视频检查结果,分析了指套管的磨损原因,并提出了指套管磨损处理准则优化建议。结果指套管磨损位置主要集中在P1和P4两处,其中P1位置磨损数量最多,而P2、P3和P5位置磨损数量较少。P1和P4两处的指套管磨损形貌差异较大,在P1位置,由于指套管易发生方向随机的高频低振幅微动磨损行为,导致产生较窄的环槽形缺陷;在P4位置,指套管则易发生低频高振幅的微动磨损行为,导致产生较宽的楔形缺陷。结论指套管和导向管的结构特性、冷却剂流场等因素均对指套管磨损有较大影响,不同位置处指套管磨损缺陷形貌差异较大。有必要分别建立针对P1位置和P4位置的指套管磨损处理准则,使得核电厂对于指套管的磨损处理更有针对性,以有效延长指套管的服役寿命。

Research on Wear Distribution and Wear Acceptance Criteria Optimization of In-core Neutron Flux Instrumentation System Thimble Tube

The purpose of this paper is to analyze the wear distribution of in-core neutron flux instrumentation system thimble tube and put forward suggestions for optimization of wear acceptance criteria. The research method in this paper is to analyze the wear distribution of thimble tube by counting the wear number of thimble tubes at different positions. And this paper analyzes wear causes of thimble tube by combined the design characteristics of thimble tube and guide card and video inspection results. Some suggestions of thimble tube wear acceptance criteria are given. There is obvious characteristics in wear distribution of thimble tube, which is the wear mainly concentrated in Point 1 and Point 4. And the wear at Point 1 is the most, while the wear at Point 2, Point 3 and Point 5 are less. The fretting wear behavior of high frequency and low amplitude with random direction is easy to occur at Point 1, which leads to narrow ring groove wear scars. The fretting wear behavior of low frequency and high amplitude is easy to occur at Point 4, which leads to wide wedge wear scars. The structural characteristics of thimble tube and guide card and reactor coolant flow field have a great influence on the thimble tube wear, and the wear defects of the thimble tube in different positions are greatly different. It is necessary to carry out related research to establish the wear acceptance criteria for the thimble tube at Point 1 and Point 4, respectively, so as to make the wear treatment of the thimble tube more targeted and prolong the service life of thimble tube.