摘要
核电站换料大修期间需要对上堆芯板内的控制棒导向筒开口销进行检查,如发现损坏无法正常使用,就要对开口销进行水下更换,为了确保开口销在上堆芯板内不会受力旋转,开口销安装后需水下焊接一个锁紧销.文中针对某核电站上堆芯板内控制棒导向筒开口销构件的水下激光焊接难题,设计了应用于水下狭窄空间的激光焊接系统,并采用数值模拟和试验研究相结合的方法,在 2m水深下,进行了水下激光焊接工艺研究.结果表明,开口销水下激光焊缝无气孔、裂纹等缺陷,焊缝可承受最大拉伸力为 10 445 N,最大扭矩为 120 N·m.采用设计的水下激光焊接系统可以实现开口销构件的水下激光焊接,接头性能满足实际服役要求.
Abstract
During the refueling and overhaul period of nuclear power plant,it is imperative to inspect split pins of the control rod guiding tube in the upper grid plate.The split pin needs to be replaced underwater if any damage is found that makes it useless.After installation,a locking pin should be welded underwater to keep the split pin from rotating when the upper grid plate is under stress.This article focuses on the issues of underwater laser welding of split pins of the control rod guiding tube in the upper grid plate in nuclear power plant.A laser welding system was designed for underwater narrow spaces.The underwater laser welding process at a water depth of 2 m was investigated through a combination of numerical simulation and experimental research.The results showed that underwater laser welded joints of split pins had no defects such as pores and cracks.The welded joints could withstand a maximum tensile force of 10 445 N and a maximum torque of 120 N·m.The developed underwater laser welding system could achieve high-quality underwater laser welded joints of split pin,and the joint performance met practical service requirements.
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