Nuclear fuel behaviour
Tiret rouge


A platform specialised in the modelling and simulation of innovative fuels for all reactor technologies.​​​​​

The PLEIADES software platform has been developed in collaboration with the French nuclear industry - EDF and Framatome - for digital simulation of fuel elements during their different phases, from manufacturing and its behaviour under irradiation to storage. Fuel elements are generally composed of fissile material in the form of pellets, plates or pebbles, which are contained in a leaktight envelope (e.g. metal cladding) or encapsulated in a material to constitute the first containment barrier for the nuclear material. The aim of this platform is to predict the behaviour of such fuel elements in reactor conditions, taking into account the initial characteristics of the materials and their changes under irradiation. The integrity of the first containment barrier - the cladding - must be maintained in operating conditions. Other the operational issues of the French nuclear power plants, digital experiments can be used to explore areas of operation that are difficult to analyse experimentally over time (spent fuel storage phases) or extreme loads (accident conditions). By optimising this knowledge in scientific calculation tools, researchers gain insight and guidance on how to improve the design of optimised or innovative fuels with improved safety and performance features.
Fuel behaviour under irradiation calls into play a complex set of multi-physical (mechanical, thermal, chemical) phenomena that can be covered in calculation tools with a wide range of load levels: nominal, incident (power ramp-up) and accident conditions for different fuel technologies: loss-of-primary coolant accidents (LOCA), and reactivity insertion accidents (RIA), which are two essential safety criteria. Although each reactor technology has its own dedicated software application (ALCYONE for PWRs, GERMINAL for SFRs, MAIA for experimental fuel-plate reactors, and LICOS for fuel elements with special geometry, all these applications share common components, laws and material behaviour models (fuel and cladding), digital resolution methods, pre- and post-processing tools and a common architecture within the PLEIADES platform. The PLEIADES platform implements a multi-dimensional (1D, 2D and 3D) and multi-scale approach (from the ceramic grain (~ 10 µm) to the fuel rod ( ~ 4m)), enabling us to obtain results as close as possible to reality. Beyond the nuclear fuel, the platform's models and tools are used for applications in the energy sector (motors, batteries, etc.) to simulate the behaviour of materials.
The PLEIADES platform integrates experimental databases that allow us to compare calculation results with experience feedback: analytical experiments conducted in order to compare a specific phenomenon with its modelling in the calculation tool, or integral experiments (irradiation experiments in research reactors or in EDF power reactors) in which various coupled physical phenomena are involved. The wide range of data from CEA laboratories and international programmes guarantees the quality of the physical representation used in applications.

​Activités. © IRESNE/CEA​​


  • Nuclear fuel,
  • Numerical simulation,
  • Multiple physics,
  • Computer codes,
  • Multiple scales,
  • Software.
​Equipements majeurs. © IRESNE/CEA

Major equipment

  • ALCYONE applications,
  • MAIA,
  • CAST3M.
​​Chiffres clés. © IRESNE/CEA​​

​Key figures

  • 20 permanent staff,
  • 10 CDD projects,
  • 30 R&D computer tool user projects ,
  • ~1 to 2 patents per year.
​​Partenaires. © IRESNE/CEA​​


About ten clients and industry partners

  • EDF
  • Framatome,
  • Orano.​