WWER RPV embrittlement: start of life toughness

It is well known that neutron irradiation affects the properties of reactor pressure vessel material. The methodologies to assess the embrittlement of LWR (PWR, BWR and WWER types) are all based on the shift induced by irradiation of a reference transition temperature. This shift is obviously defined as the transition temperature (RTNDT or T k ) for the irradiated material minus the transition temperature for the non-irradiated material. This shift is measured by Charpy impact tests and applied to the fracture toughness reference curves. The main objective of this paper is to review the available literature on fracture toughness data of non-irradiated material, which is start of life fracture toughness for WWER reactor pressure vessels.