Assessment of Ni and Mn effect on the irradiation hardening behavior of VVER-1000 model steels exposed to high fluences in the high flux reactor

In the present work, we aim at providing more data and insight related to the influence of Ni and Mn contents on the degree of irradiation hardening of Light Water Reactor RPV steels. A total of 20 model steels and realistic welds based on VVER-1000 and PWR RPVs compositions were irradiated at high flux and to high fluences in the LYRA-10 experiment, conducted in the High Flux Reactor, Petten. Among them, eight VVER-1000 model steels with 0.1 wt % Cu and systematically varied Mn and Ni contents were submitted to tensile and Vickers hardness testing for evaluation of their degree of hardening, and were characterized in detail, using Atom Probe Tomography, Transmission Electron Microscopy, Small Angle Neutron Scattering and Positron Annihilation Spectroscopy. The mechanical testing results show the clear increase in degree of irradiation hardening with the Mn and Ni contents, in particular for steels containing 1.4 wt % Mn. Microstructural observations show direct correlation between increase in yield strength and the formation of Mn-Ni-Si solute clusters. Calculations done using classic and multiscale models confirm that the solute clusters are the main hardening features present in the irradiated RPV model steels. Furthermore, TEM and PAS results suggest that dislocation loops have a more significant role on the formation of solute clusters than on irradiation hardening of the group of materials investigated.

MARQUES PEREIRA Vivian;  RADIGUET Bertrand;  ONORBE Elvira;  ULBRICHT Andreas;  SHARMA D.;  ETIENNE A.;  LAOT Mathilde;  SZAVAI S;  MARTIN Oliver;  KOLLURI M.; 

2025-08-01

ELSEVIER

JRC143159

1873-4820 (online),   

https://www.sciencedirect.com/science/article/pii/S0022311525003265?via%3Dihub,    https://publications.jrc.ec.europa.eu/repository/handle/JRC143159,   

10.1016/j.jnucmat.2025.155932 (online),