Master curve reference temperature behavior of steels with varying Ni/Mn content and subjected to a fluence of 11·1019 neutron/cm2

The degradation of fracture toughness due to irradiation needs to be understood to assess the structural integrity of reactor pressure vessels for long-term operation. The level of degradation is dependent on the chemical content, particularly of elements like Ni and Mn. The fracture toughness properties for three types of steels (i.e. VVER-1000 steel, western model steel and VVER-1000 welds) with varying contents of Ni and Mn were characterized based on Master Curve T 0 reference temperature in reference condition and in irradiated condition. The results show that, in the high fluence region, the shifts in T 0 correlate with the content of Ni and Mn, and the scatter in fracture toughness is mostly consistent for the reference and irradiated conditions. At higher T 0 values, above 75 °C, T 41J gives an increasingly larger estimate compared to T 0 . The obtained results can be applied to develop new improved embrittlement trends curves for NPP lifetime assessment. • Unexplored parameter region (high fluence, T 0 data and varying Ni/Mn content). • Master Curve characterization of steels with varying Ni and Mn content. • Ni and Mn govern the ΔT 0 even if the initial fracture toughness differs. • The scatter in fracture toughness is similar in the reference/irradiated conditions. • At higher T 0 values, >75 °C, T 41J gives an increasingly larger estimate.