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核电厂一回路系统设备的接管嘴与管道的焊缝结构广泛应用合金81/182,该类焊缝为异种金属焊(DMW),DMW焊缝对一次侧水应力腐蚀(PWSCC)较为敏感,运行过程中易发生裂纹泄漏等问题。堆焊修复方法在国外核电处理该类问题得到广泛应用。本文基于秦山一期核电厂稳压器喷雾管接管嘴尺寸,建立轴对称有限元模型,采用生死单元模拟焊接过程的瞬态热输入,研究了结构在堆焊修复过程中温度场的变化分布特性,将计算得到的结构热分布历程作为热载荷,进而获得了堆焊修复过程中结构残余应力的变化特性,结果表明堆焊修复完成后,DMW焊缝区域内壁的残余应力能够起到控制PWSCC的作用。
Alloy 81/182 is widely used for the joint structure of the nozzle and the pipe of the primary system of nuclear power plant. This kind of weld is the dissimilar metal welding (DMW). The DMW weld is sensitive to the primary water stress corrosion (PWSCC) Easily occur during the crack leak and other issues. Surfacing repair method is widely used in foreign nuclear power to deal with this kind of problem. Based on the nozzle size of the spray pipe of the voltage stabilizer of Qinshan Phase I NPP, an axisymmetric finite element model was established and the transient heat input of the welding process was simulated by life and death unit. The variation and distribution of the temperature field in the process of surfacing welding , The calculated thermal history of the structure was taken as the thermal load, and then the variation characteristics of the structural residual stress in the process of surfacing welding were obtained. The results show that the residual stress of the inner wall of the DMW weld zone can control the PWSCC effect.