Studiecentrum voor Kernenergie/Centre d’étude de l’énergie nucléaire/

SCK•CEN is one of the largest research institutions in Belgium. Every day, more than 700 employees dedicate themselves to developing peaceful applications of radioactivity. Our developments have already resulted in a long list of innovative and forward-looking applications for the medical world, industry and the energy sector. We are renowned for our expertise world-wide.
The Structural materials group (SMA), participating in the SOTERIA project, has for aim to perform the scientific and technological studies of the structural materials used in current reactors, as well as those foreseen to be used in future reactors, with the aim to understand the material properties and behavior under conditions relevant for nuclear industry. Safety and lifetime extension are high priority topics for the operation of current light water reactors, Gen II and III. Our activities aim to understand quantify and predict the effect of material aging which are generally related to degradation of the mechanical properties under neutron irradiation.  For reactor pressure vessel (RPV) steels the embrittlement is of prime importance while for internal component mainly made out of stainless steels, the corrosion cracking, fatigue and swelling are under intense focus. The global research strategy is based on the combination of experimental and theoretical studies and multidisciplinary approach. A variety of experimental techniques are at our disposal as well as theoretical models starting from ab-initio approaches up to large scale empirical and engineering models. In the past, the SMA group participated in a variety of European projects such as PERFECT, PERFORM 60, as well a variety of national programs which provided the output relevant for the current project proposal SOTERIA.

Role in the project

SCK•CEN contributes to WP2 and WP5. The work in WP2 aims to investigate thermal stability and structure of MnNi rich clusters in neutron irradiated FeMnNi alloys and RPV steels. The focus will be on the synergy between vacancy, carbon and MnNi solute atoms. The properties of solute clusters will be studied by positron annihilation techniques which is known to be sensitive to the presence of vacancies. The results will be compared with atomistic simulations/calculations utilising developed models from previous projects such as P60 and PERFECT. Both molecular dynamics and Monte Carlo simulations will be used to identify the structure and composition of the experimentally observed point defect clusters.
The work in WP5 aims to refine existing OKMC models, by introducing explicitly solute atom transport and apply them to rationalise, in terms of physical processes, the effects of flux, fluence and post-irradiation annealing on the nanostructure in low-Cu RPV steels. These models will combine for the first time the description of microchemical processes with the description of the build-up of radiation damage in terms of point-defect clusters. In parallel, thanks to the development of interatomic potentials for complex systems in previous projects (FeCuMnNi) and to the large experience accumulated with studies of dislocation/defect interactions by means of molecular dynamics, it is now possible to study in detail the mechanisms of hardening due to the fauna of obstacles that form under irradiation, ranking the defects in terms of their effectiveness to harden. Solute-enriched dislocation loops appear to be to preliminary studies the most important contributors. The second objective of the work in WP5 is therefore to characterise the role of solute segregation at nano-scale dislocation loops using atomistic simulations and transfer this data to continuum dislocation dynamics methods to assess contribution to hardening due to local segregation effects.

Personnel involved

Dr Milan Konstantinovic, solid state physicist, positron annihilation experiment
He has a PhD from the Faculty of Physics, University of Belgrade, Yugoslavia, 1994. Knowledge in microstructure (positron annihilation, neutron scattering, X-ray photoelectron spectroscopy, X-ray diffraction); optical spectroscopy; transport properties; magentic properties; relaxation experiments; mechanical tests. He was a sub-project leader in the FP7 PERFORM 60 project. Current research: Physical properties of neutron irradiated materials; Iron alloys and RPV steels: Embrittlement and hardening, mechanical properties, microstructure, correlation between microstructure and mechanical properties.
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Dr Lorenzo Malerba, nuclear engineer, modelling of nanostructural evolution under irradiation
He has a PhD from the Institute of Nuclear Fusion, Universidad Politécnica de Madrid, Spain, 2000. Knowledge in nanostructure evolution models, especially kinetic Monte Carlo. Combination of models and experiments to address specific issues and deduce fundamental physical mechanisms. He was a WP leader in the FP6 PERFECT and the FP7 PERFORM 60 projects, as well as in the FP7 GETMAT project. He led several projects inside SCK•CEN.
Current research: Identification of main physical mechanisms leading to irradiation embrittlement in ferritic steels, starting from nanostructural changes.
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Dr Dmitry Terentyev, nuclear physicist, modelling of plasticity at the atomic  and dislocation level
He has a PhD from the Free University of Brussels, Belgium, 2006.
Specialist in numerical tools for material's modeling, especially atomistic and dislocation level applied to radiation damage production and evolution and plasticity problems.
He was principal investigator of several fusion materials tasks. Currently fusion coordinator at SCK•CEN. Current research: Identification of main physical mechanisms leading to radiation effects in ferritic and austenitic steels, focusing on effects on plasticity.
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Available Documentation

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