Background:Fatigue is an important ageing mechanism in RPV and it must be contained to ageing management working range.Purpose:In order to ensure the safety operation of nuclear power plants

as extension of RPV service time

it is necessary to assess the fatigue damage caused by actual operation transient.Methods:Based on monitoring data of actual operation during the past eleven years

refer to design transient

the statistic analysis for types and occurrence times of actual transient is carried out

at the same time

every transients are combined as different operation cycles and the temperature field and stress field of typical components are analyzed by FEM.Results:Based on these information

fatigue analysis and assessment are finished

if later-actual transients are similar with the previous transients

the calculation result shows that the ratio between maximum of cumulative usage factors and design calculation value is 0.4967 the design transients is conservative.Conclusions:Fatigue status of RPV could be assessed and traced quickly through fatigue status assessment method in this paper based on actual operational transient and assessment result would be a good reference for RPV aging management.