Evaluation of Reactor Pressure Vessel Irradiation Embrittlement of VVER-1000 Nuclear Power Unit

Irradiation surveillance and embrittlement evaluation of reactor pressure vessel is an important means to ensure the safe operation during reactor lifetime. This paper introduces the designation and test types of Tianwan NPP Unit 1 and 2（VVER-1000） unit irradiation surveillance sets. Also, the test results, irradiation embrittlement estimation models and lead factor are analyzed and discussed for the 1Л and 2Л sets of Tianwan NPP Unit 1. The irradiation surveillance data shows that the irradiation embrittlement effect of base metal and welds of RPV active area of Tianwan NPP Unit 1 is in the scope of the initial design. The RPV actual embrittlement trend is in good agreement with the estimation model. It is suggested that next irradiation surveillance set be unloaded during the 20 th year of reactor operation.