核电机组汽轮机低压叶轮叶根槽应力腐蚀裂纹扩展寿命分析

Analysis on Stress Corrosion Crack Propagation Life of Low-pressure Impeller Blade Root Groove in Nuclear Power Unit Steam Turbine

分析核电机组汽轮机低压叶轮应力腐蚀发生的机理及应力腐蚀裂纹扩展的原因,结合Clark模型和腐蚀环境下的Pairs模型建立应力腐蚀裂纹扩展寿命的计算模型。以某核电机组汽轮机的低压第2级、第3级叶轮叶根槽为研究对象,对应力腐蚀裂纹扩展寿命进行研究分析。结果表明:采用2种模型计算的裂纹扩展寿命均满足核电机组汽轮机耐用件使用寿命(60年)的要求。Pairs模型下的裂纹扩展寿命相比于Clark模型更加保守,在使用Clark模型对裂纹扩展寿命估算时,可以选取2~3的安全系数,并且温度变化对Clark模型下的裂纹扩展速率有较大的影响。

Analyses were conducted on the mechanism of stress corrosion and the cause of stress corrosion crack propagation of the steam turbine low-pressure impeller in nuclear power units,and the calculation model for stress corrosion crack propagation life was established combined with Clark model and Pairs model in the corrosion environment.Taking the second and third stage impeller blade root grooves of the low-pressure steam turbine in a nuclear power unit as the research object,the propagation life of stress corrosion crack was researched and analyzed.Results show that the crack propagation life calculated according to the stress corrosion crack propagation rate with the two models can meet the requirement of the service life(60 years)of the serviceable part of the steam turbine in nuclear power units.The crack propagation life from Pairs model is more conservative than that from Clark model,and the safety factor can be selected within 2-3 when estimating the crack propagation life with Clark model,while the change of temperature has a significant influence on the crack propagation rate with Clark model.