Irradiation response of the IAEA CRP-3 material FFA measured by fracture toughness specimens

The irradiation response of the French forging material FFA offered by International Atomic Energy Agency (IAEA) has been measured. Charpy-5 and precracked specimens of three-point bending (3-PB) geometry for J-Δa curve measurement have been irradiated in the surveillance position of the Loviisa nuclear power plant (NPP) in a flux of 2 x 1011 n/cm²s to a fluence of approximately 2.0 x 1019 n/cm², E > 1 MeV, at a temperature of 265°C. The irradiation-induced transition temperature shifts measured with Charpy-5 and fracture toughness specimens are correlated by using indexed temperature values. The shape of the brittle fracture transition curves, measured with 3-PB specimen geometry, for irradiated and reference material states are compared using a statistical brittle fracture model. Both the shape of the average curve and the scatter of the measured points are considered. The effect of irradiation on the ductile fracture behavior based on the measured fracture resistance curves (J-Δa) is presented. The 3-PB specimen geometry is used also for measuring the fracture resistance curves