压水堆材料冷却剂环境疲劳修正因子研究

Study on Environmental Fatigue Correction Factor of PWR Material Coolant Environment

本文对考虑压水堆一回路冷却剂环境对材料疲劳影响的环境疲劳修正因子Fen进行研究,结合核电厂延寿需求,确立基于环境疲劳修正因子的疲劳分析流程.针对典型接管嘴结构,采用考虑瞬态应力时间历程的应变增量方法计算转换应变率和Fen,对比了环境修正对疲劳结果的影响.考虑环境影响后,奥氏体不锈钢的疲劳使用系数增大3.2倍,低合金钢的疲劳使用系数增大8.5倍,冷却剂环境对疲劳寿命的影响显著.将考虑环境影响后的疲劳使用系数与EPRI导则的计算结果进行对比,二者计算结果接近,验证了考虑瞬态组合的环境疲劳修正因子分析计算方法的正确性.

The environmental fatigue correction factor Fen considering the effect of pres-surized water reactor(PWR)coolant environments on the fatigue life of materials was studied.Combined with the requirement of life extension of nuclear power plant,the fatigue analysis process based on environmental fatigue correction factor was estab-lished.For typical nozzle structure,the transformation strain rate and Fen were deter-mined adopting the strain increment method of using stress time history of transient,and then the effect of environmental modification on the fatigue life was compared.After considering the environmental impact,the fatigue usage coefficient of austenitic stainless steel increases by 3.2 times and the fatigue usage coefficient of low alloy steel increases by 8.5 times.The effect of coolant environment on the fatigue life of materials is significant.The fatigue usage coefficients considering environmental impact were compared with the results of EPRI guidelines,the results are close to each other,and it is verified that the calculation method of environmental fatigue correction factor consid-ering transient combination is correct.