基于ASME III规范的核级大气排放阀高温部件蠕变疲劳强度研究
Research on Creep Fatigue Strength of High Temperature Components of Nuclear Atmospheric Discharge Valve Based on ASME III Code

采用ANSYS软件建立了某核级大气排放阀高温部件(阀体和阀盖)蠕变疲劳分析的力学模型，介绍了基于ASME III规范的蠕变疲劳分析方法。计算考虑两种循环载荷工况：1) 低温工况，模拟正常运行，工作温度为370℃，因阀门打开和关闭而引起压力波动；2) 高温工况，模拟运行瞬态，最高工作温度480℃，有温度波动和压力波动。采用热固耦合方法计算了结构的热应力，与自重、压力及外部载荷产生的机械应力进行组合得到结构的总应力，采用主应力差方法计算结构的交变应力强度，依据ASME III规范进行应力评定。对于低温工况，依据设计疲劳曲线进行疲劳强度校核；对于高温工况，依据ASME III规范的弹性分析方法进行蠕变疲劳损伤评定。分析结果表明，大气排放阀高温部件的疲劳强度和蠕变疲劳性能满足规范要求。
A mechanical model for creep fatigue analysis of high-temperature components (valve body and bonnet) of a nuclear atmospheric discharge valve was established by using ANSYS software. The creep fatigue analysis method based on ASME III code was introduced. Two cyclic load conditions were considered in the calculation: 1) Low temperature condition, simulating normal operation, working temperature was 370℃, and pressure fluctuation was caused by valve opening and closing; 2) High temperature condition, simulated the transient operation, the maximum working temperature of 480℃, with temperature fluctuations and pressure fluctuations. The thermal stress of the structure was calculated by thermostructural coupling method, and the total stress of the structure was obtained by combining with the mechanical stress generated by dead weight, pressure and external load. The alternating stress intensity of the structure was calculated by principal stress difference method, and the stress was assessed according to ASME III code. For low temperature conditions, the fatigue strength was checked according to the designed fatigue curve. For high temperature conditions, creep fatigue damage was assessed according to the elastic analysis method of ASME III code. The analysis results show that the fatigue strength and creep fatigue performance of the high temperature components of the atmospheric discharge valve meet the requirements of the specification.