Common comparison of the irradiation embrittlement of WWER/PWR reactor pressure vessel steels

• Comparison of Tk shifts due to neutron irradiation for WWER and PWR RPV materials.
• RPV steels were irradiated at both the same temperature and neutron fluence range.
• For both PWR and WWER RPV material types, there is a similar degradation in mechanical properties.
• Synergistic influence of copper, nickel and phosphorus is observed.

The paper presents the immediate comparison of Tk shifts due to neutron irradiation for WWER and PWR RPV materials and common experimental data analysis. The PWR and WWER RPV steels were irradiated at both the same temperature and neutron fluence range. For both PWR and WWER RPV material types, there is a similar degradation in mechanical properties. The comparison of “high sensitive” welds with “clean” welds reveals an expected influence of three main chemical elements (copper, nickel and phosphorus) on RPV steels irradiation embrittlement. The synergistic influence of these three elements is observed. Because the peak neutron fluence in WWER RPVs is significantly higher than for PWRs, the most part of WWER irradiation embrittlement data correspond to high fluence values. These additional data will greatly support the development of embrittlement correlations and embrittlement trend curves valid for long irradiation times.