Uncertainty analyses on fracture toughness of heat affected zone in an RPV steel

Ha, Yoosung  ; Shimodaira, Masaki ; Katsuyama, Jinya  ; Hata, Kuniki 

The fracture toughness values of heat-affected zone (HAZ) may show a large scatter due to inhomogeneous metallurgical structures. The inhomogeneous microstructure in HAZ may influence on the sensitivity to irradiation embrittlement. To be clear the fracture toughness and its uncertainty of HAZ with harvesting positions, we investigated the fracture toughness in HAZ of unirradiated material with respect to its distance from the fusion line of welds. in all positions of HAZ were significantly lower than that of base metal. In the HAZ at 2 mm, where was close to base metal, the uncertainty of fracture toughness was largest and the reference temperature was higher among all positions of HAZ. It can be said that the weak metallurgical structures were distributed at 2 mm HAZ from the fusion line.