压水堆核电机组二回路给水系统弯头减薄原因分析

Cause Analysis for Elbow Thinning of the Secondary Loop Feedwater System in PWR NPP

2012年3月,某核电厂大修期间对二回路部分管线进行了现场壁厚测量,发现电动主给水泵系统弯头存在壁厚减薄现象。文章对其中的一根弯头在实验室进行了失效分析。利用超声波测厚仪在实验室对换下的弯头进行壁厚测厚并利用等离子光谱发生仪等设备及分析手段对异常减薄部位和减薄一般部位进行了分析研究。结果表明管壁异常减薄是由于流动加速腐蚀(FAC)引起的。最后,根据分析结果,结合国内外的最新研究进展,对管道的管理及变更提出了建议。

Wall thickness of some secondary system pipelines were measured on site during the refueling outages in March 2012. Wall thinning happened in some components of APA system. This paper focused on the cause analysis of an elbow with that phenomenon. Wall thickness was carefully measured in laboratory using ultrasonic thickness meter and found that wall thinning happened nearly all elbows including two abnormal thinning regions. Analytical research was conducted using ICP, stereo microscope, SEM ,XRD, ANSYS. The result shows that the cause of wall thinning is flow accelerated corrosion. Based on the analysis result and international research progress, this paper makes some suggestions to avoid and alleviate FAC in the secondary system.