Nuclear Materials

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Team leader : Bertrand Radiguet

Team members : A. Etienne (IR), R. Henry (IR), C. Pareige (Pr), P. Pareige (Pr), B. Radiguet (MCF), S. Rouland (MCF),

 

Our internationally recognized research on nuclear reactor structural materials is based on an expertise developed at the GPM for over 30 years. We undertake the study of the effects of irradiation from the most fundamental approaches to the most important technological issues in the field. The construction of a platform dedicated to the study of radioactive materials (EQUIPEX GENESIS) and a joint laboratory with EDF R&D (EM2VM) now provides an ideal framework for these research activities, which are based on two main themes:

  • Aging of structural materials of pressurized water reactors (PWR)
  • The development of materials for tomorrow's nuclear reactors, i.e. generation 4 reactors, fusion, but also the new medium-term objectives of the industry: the development of the EPR2 and SMR (Small Modular Reactor).  

In both cases, the objectives are to understand the aging mechanisms, whether under thermal aging (duplex steels of the primary circuit of PWRs, for example) or under irradiation (low-alloy steels, stainless steels, etc.), and when data on mechanical properties exist, to understand the links between the evolution of the microstructure and these properties. 

In collaboration with our academic and industrial partners, both nationally and internationally (EDF, ATRON, CEA, SCK-CEN (Belgium), CIEMAT (Spain), CRIEPI (Japan), HZDR (Germany), Petten (Netherlands), USA (UNL), ...) our objectives are:
 

  1. The understanding of the mechanisms of thermal and irradiation aging:

     This research is central to the theme of nuclear materials. Thanks to the possibilities offered by the GENESIS platform which was inaugurated in 2017 and opened to active materials in 2019, it is now possible to select the areas where to take samples in massive materials irradiated with neutrons to analyze them on a fine scale, in atomic probe and / or electron microscopy (in situ traction, temperature) allowing to correlate chemistry, crystalline defects and mechanical properties. Particular attention is paid to the role of metallurgical heterogeneities (carbides, inclusions) and segregation under irradiation (interfaces, grain boundaries) and their influence on the mechanical behavior. 

     

  2. Relationship between microstructure and mechanical properties:

    The question of the relationship between microstructure evolution and mechanical properties has been addressed within the team for several years. We develop fine scale tests (nanoindentation, micropillar compression...) ex situ or in situ in our scanning electron microscope or in transmission (in situ traction). Chemical analysis by atomic probe of samples taken from the heart of these stressed specimens is a new source of information on the deformation mechanisms and their effects.

     

  3. Influence of the nature of the incident particles:

     Studies on samples from the monitoring program or from irradiation campaigns in experimental reactors are essential but experimentally extremely costly, involve long irradiation times and the handling of active samples. We are therefore led to use alternative sources based on ions or electrons. We are currently developing in partnership with the company CERAP/ATRON a new approach of electron irradiation allowing to reach previously unimaginable doses (0.1 dpa) in very short times (2 weeks) on massive materials. This world first opens up exceptional fundamental work. If we now know that neither ions, nor electrons, nor protons can reproduce the effects of neutrons, the understanding of the differences is essential for the transferability of the results.